U.S. patent application number 14/804745 was filed with the patent office on 2016-06-23 for facilitating revenue generation from wholesale electricity markets using an engineering-based energy asset model.
This patent application is currently assigned to VIRIDITY ENERGY, INC.. The applicant listed for this patent is Eunice B. Hameyie, Alain P. Steven, Jin Wen, Teresa Wu. Invention is credited to Eunice B. Hameyie, Alain P. Steven, Jin Wen, Teresa Wu.
Application Number | 20160180474 14/804745 |
Document ID | / |
Family ID | 51841954 |
Filed Date | 2016-06-23 |
United States Patent
Application |
20160180474 |
Kind Code |
A1 |
Steven; Alain P. ; et
al. |
June 23, 2016 |
FACILITATING REVENUE GENERATION FROM WHOLESALE ELECTRICITY MARKETS
USING AN ENGINEERING-BASED ENERGY ASSET MODEL
Abstract
The disclosure facilitates generation of energy-related revenue
for an energy customer of an electricity supplier. The disclosure
herein can be implemented to generate suggested operating schedules
for energy assets that include a controllable energy asset, using
an objective function. The objective function is determined based
on a dynamic simulation model of the energy profile of the energy
assets. The dynamic simulation model is adaptive to physical
changes in the energy assets based at least in part on a physical
model of the thermodynamic property of the at least one energy
asset and at least in part on data representative of an operation
characteristic of the controllable energy asset, a thermodynamic
property of the energy assets, and/or a projected environmental
condition. Energy-related revenue available to the energy customer
is based at least in part on a wholesale electricity market or on a
regulation market.
Inventors: |
Steven; Alain P.; (Lansdale,
PA) ; Hameyie; Eunice B.; (Havertown, PA) ;
Wen; Jin; (Glenside, PA) ; Wu; Teresa;
(Gilbert, AZ) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Steven; Alain P.
Hameyie; Eunice B.
Wen; Jin
Wu; Teresa |
Lansdale
Havertown
Glenside
Gilbert |
PA
PA
PA
AZ |
US
US
US
US |
|
|
Assignee: |
VIRIDITY ENERGY, INC.
Philadelphia
PA
|
Family ID: |
51841954 |
Appl. No.: |
14/804745 |
Filed: |
July 21, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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13888309 |
May 6, 2013 |
9171276 |
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14804745 |
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Current U.S.
Class: |
705/7.24 |
Current CPC
Class: |
G06Q 50/06 20130101;
Y04S 20/00 20130101; Y02B 90/20 20130101; H02J 13/0006 20130101;
G05B 13/02 20130101; Y02B 70/30 20130101; G06Q 10/06314 20130101;
G06F 30/20 20200101; Y02P 90/84 20151101; G06Q 10/06 20130101; H02J
13/0062 20130101; G06F 17/10 20130101 |
International
Class: |
G06Q 50/06 20060101
G06Q050/06; G06F 17/10 20060101 G06F017/10; G06Q 10/06 20060101
G06Q010/06; G06F 17/50 20060101 G06F017/50 |
Claims
1. An apparatus for determining a suggested operating schedule for
at least one energy asset operated by an energy customer, the
apparatus comprising: at least one communication interface; at
least one memory to store processing unit-executable instructions
and an objective function for the at least one energy asset,
wherein the at least one energy asset comprises at least one
controllable energy asset, wherein the objective function
facilitates a determination of the suggested operating schedule for
the at least one energy asset based at least in part on a physical
model of the thermodynamic property of the at least one energy
asset and at least in part on data representative of model
parameters, and wherein the model parameters are: (a) an operation
characteristic of the at least one controllable energy asset, and
(b) a projected environmental condition during time period T; and
at least one processing unit communicatively coupled to the at
least one memory, wherein, upon execution of the processing
unit-executable instructions, the at least one processing unit: A)
prior to time period T, determines the suggested operating schedule
based on an optimization of the objective function over time period
T, wherein the objective function is determined based on a dynamic
simulation model of the energy profile of the at least one energy
asset, a customer baseline (CBL) energy profile for the at least
one energy asset, and a forecast wholesale electricity price, over
time period T, associated with a wholesale electricity market,
wherein the dynamic simulation model is adaptive to physical
changes in the at least one energy asset based at least in part on
the physical model of the thermodynamic property of the at least
one energy asset, and wherein the dynamic simulation model is
trained using the data; and B) controls the at least one
communication interface to transmit to the energy customer the
suggested operating schedule determined in A), and/or controls the
at least one memory so as to store the determined suggested
operating schedule, wherein the operation of the at least one
energy asset according to the suggested operating schedule, over a
time period T, facilitates generation of energy-related revenue
based at least in part on the wholesale electricity market.
2-36. (canceled)
Description
BACKGROUND
[0001] In various regions across the United States, "regional
transmission operators" (RTOs) or "independent system operators"
(ISOs) generally are responsible for obtaining electricity from
electricity generators (e.g., operators of coal-fired plants, gas
plants, nuclear plants, hydroelectric plants, renewable resources,
etc.), and then transmitting the electricity provided by generators
over particular geographic regions (e.g., New England, the greater
New York area, the mid-Atlantic states) via an electricity
transmission infrastructure (also commonly referred to as the
electricity "grid"). RTOs generally are responsible for regional
planning of grid expansion and/or ordering deployment of new
electricity transmission infrastructure by transmission owners.
[0002] The Federal Energy Regulation Commission (FERC) presently
requires that, in addition to generally managing the operation of
the electricity grid in a given geographic area, RTOs/ISOs need to
manage the price of electricity generated and consumed on the grid
via "wholesale electricity markets." To this end, RTOs/ISOs
establish pricing auctions to provide and support wholesale
electricity markets. These pricing auctions, in addition to setting
wholesale prices as a function of time, also foster sufficient
electricity production for the grid at various locations to ensure
that the grid is capable of delivering adequate electricity to
respective locations of demand for electricity on the grid. Thus,
some of the key objectives of the RTOs/ISOs in overseeing wholesale
electricity markets include providing for efficient, economic and
reliable operation of the grid.
[0003] In general, a given RTO/ISO supports a wholesale electricity
market by allowing competing electricity generators to offer their
electricity production output to the RTO/ISO. Retail electricity
suppliers, also commonly referred to as "utilities," in turn supply
electricity to end-users/consumers, or "energy customers" of the
retail electricity suppliers, and are billed by the RTO/ISO for
their purchases. With respect to the wholesale electricity market,
the retail electricity suppliers make bids for the electricity
production output offered by the electricity generators that, once
accepted, establish market prices. The retail electricity suppliers
in turn typically re-price the electricity they purchase from
electricity generators on the wholesale market to sell to their
retail electricity customers.
[0004] One significant issue facing RTOs/ISOs relates to various
limitations that exist in connection with the grid that may impede
a sufficient flow of electricity on the grid under certain
circumstances. In particular, there may be time-dependent and/or
geographically-dependent limitations on the grid's ability to
support transmission of electricity, based on one or more of: 1) an
available overall supply of electricity from electricity
generators; 2) overall demand from retail electricity suppliers; 3)
general conditions on the grid itself (e.g., aging, failing or
dated equipment); and 4) "location-specific" or "congestion"
issues, e.g., respective geographic locations on the grid of
electricity generators, electricity consumers, particular demand
conditions, and/or particular grid-related conditions that in some
manner impede the transmission of available electricity to one or
more portions of the grid). In some circumstances, a grid
limitation may be caused by a particular branch of the grid
reaching a thermal limit, or a failure of a generator or
transformer on a branch of the grid; these limitations generally
are referred to as "security constraints" (i.e., particular grid
infrastructure cannot be overloaded without jeopardizing the grid).
As such, the electricity grid is sometimes referred to as a
"security constrained system."
[0005] In view of the foregoing, RTOs/ISOs may employ a process
known as "security constrained economic dispatch" for establishing
wholesale electricity prices on a wholesale electricity market.
Pursuant to this process, an RTO/ISO managing a particular
geographic region of an electricity grid determines particular
locations on the grid, or "nodes," at which there is a possibility
for security constraints to limit electricity transmission.
Wholesale electricity prices as a function of time are then
established independently for each node (i.e., on a
geographically-dependent, or "locational" basis) by accepting bids
from energy generators in sequence from the lowest priced offer to
the highest priced offer, up to an amount of electricity needed to
satisfy electricity demand conditions (e.g., bids from retail
electricity suppliers) at the node, so as to develop a supply and
demand equilibrium price. In this manner, the wholesale electricity
price at a particular node reflects the highest-priced accepted
generation offer needed to provide an adequate amount of
electricity to that node, taking into consideration various
security constraints that may be present at the node. This
location-based approach to wholesale electricity prices, which
takes into consideration security constraints on the grid, commonly
is referred to as "locational marginal pricing," and the wholesale
electricity price at a given node is commonly referred to a
Locational Marginal Price (LMP). Thus, the wholesale electricity
price generally varies at different locations on the grid, based at
least in part on security constraints.
[0006] While electricity generators and retail electricity
suppliers make up a significant constituency of the participants in
wholesale electricity markets, applicable market rules in some
wholesale electricity markets also permit electricity
consumers/end-users (e.g., energy customers of retail electricity
suppliers) and others to participate in wholesale electricity
markets so as to earn energy-related revenue and offset their
energy-related expenditures. In particular, market rules now permit
energy users (or their market representatives) to make offers to
curtail or otherwise alter their electricity use, or to sell
self-generated or stored electricity, to the wholesale market. If
such an offer by an energy customer to provide an
"electricity-related product or service" is accepted on the
applicable wholesale market, the customer endeavors to
appropriately control its various energy assets so as to make
available to the grid the offered product/service, in return for
payment pursuant to the terms of the offer. The concept of an
energy customer providing an electricity-related product or service
(e.g., electricity use curtailment) on a wholesale electricity
market in exchange for payment to the energy customer by the
RTO/ISO, commonly is referred to as "demand response" (DR).
[0007] Some of the currently more active wholesale electricity
sub-markets in which energy customers of retail service providers
may readily participate include the "energy markets" (e.g.,
"day-ahead" energy market, "real-time dispatched" energy market).
While various pricing models exist for participation in these
markets and other economic demand response wholesale electricity
markets (as well as various penalty models for customer
non-performance pursuant to an offer to reduce/curtail energy use),
often any revenue generated by the energy customer from
participation in these markets is based on the locational marginal
price (LMP). The LMP may be calculated periodically at specified
nodes (e.g., every 5 minutes, every half-hour, every hour)
depending on the particular market in which the energy customer is
participating. More generally, revenue generation relating to
participation in an economic demand response wholesale electricity
market is based on a prevailing "wholesale electricity price" for
the particular market in question, which in turn generally is based
on the LMP (calculated at various intervals), as discussed
above.
[0008] To determine revenue earned by participating energy
customers in a particular economic demand response wholesale
electricity market such as an "energy market," the amount of
electricity use reduction by the participating customer typically
has to be measured; subsequently, this measured amount of
electricity use reduction typically is multiplied by a price
relating to the prevailing wholesale electricity price for the
market in question (e.g., LMP). Electricity use reduction by the
energy customer conventionally is measured against a reference
electricity usage commonly referred to as a "customer baseline"
(CBL). The CBL is intended to represent what the participating
energy customer's electricity use normally would have been, over a
particular time period and typical ("business-as-usual" or BAU)
operating conditions for the customer's energy assets, absent the
customer's voluntary electricity use reduction based on the
incentive provided by the economic demand response wholesale
electricity market.
[0009] Conventionally, a customer baseline (CBL) electricity use
profile for an energy customer is derived by an RTO/ISO from an
historical sample of actual electricity use by the customer over a
particular time period and BAU operating conditions. In some cases,
the particular time period for which an historical sample of the
customer's actual electricity use is selected as a CBL may be
based, at least in part, on similar conditions prevailing at the
customer's site at the time of the historical sampling and
participation in the economic demand response program (e.g.,
similar weather conditions, similar seasons/time of year, similar
occupancy conditions at the customer's site, etc.). In other
instances, the time period for selecting an historical sample of
actual electricity usage as a CBL is based on relatively recent
actual electricity use by the energy customer just prior to the
customer's participation in the economic demand response program.
For example, the ISO PJM Interconnect calculates a
market-participating customer's CBL for a given weekday as "the
average of the highest four out of the five most recent highest
load (electricity use) weekdays in the 45 calendar day period
preceding the relevant load reduction event." In sum, revenue
generation from the economic demand response wholesale electricity
"energy markets" conventionally is based on an historical actual
electricity usage of a participating customer, which historical
actual electricity usage serves as a customer baseline (CBL)
against which electricity use reduction is measured for purposes of
paying the energy customer for the use reduction.
SUMMARY
[0010] The Inventors have recognized and appreciated that new
opportunities for participation in wholesale electricity markets by
electricity consumers/end-users (e.g., energy customers of retail
electricity suppliers) have created a need for energy management
tools to facilitate energy-related revenue generation from such
markets. In view of the foregoing, various embodiments are directed
generally to methods, apparatus and systems for determining
operating schedules for energy assets so as to facilitate revenue
generation from wholesale electricity markets. These energy assets
include energy storage assets, energy consuming assets and energy
generating assets. In different examples herein, an energy asset
can include an energy storage asset, an energy consuming asset,
and/or an energy generating asset.
[0011] Wholesale electricity markets in which the energy customer
may participate to earn energy-related revenue, and to which the
various methods, apparatus and systems according to the concepts
disclosed herein may apply, include various economic demand
response wholesale electricity markets, examples of which include,
but are not limited to, a "real-time energy market," a "day-ahead
energy market," a "day-ahead scheduling reserve market," a
"synchronized reserve" market, a "regulation" market, a "capacity"
market, and an "emissions" market. The various methods, apparatus
and systems according to the concepts disclosed herein may also
apply to facilitate the energy customer participating in a market
based on a voltage/VAR ancillary service to earn energy-related
revenue. In some examples, the methods, apparatus and systems
described herein may be implemented in whole or in part by a
curtailment service provider (CSP) or other entity acting as a
"broker" between energy customers and an RTO/ISO to facilitate
participation in various demand response programs supported by
wholesale electricity markets.
[0012] Suggested Operating Schedules for Energy Assets
[0013] In example implementations discussed in greater detail
below, the methods, apparatus and systems described herein
determine a suggested operating schedule for one or more energy
assets (including energy-consuming assets for which energy usage
may be curtailed), over a given time period T, that are operated by
an energy customer of a retail electricity supplier. The energy
assets operated by the energy customer may include
electricity-consuming assets as well as electricity-generating
assets (e.g., fossil-fuel-based generators, renewable energy
sources) and/or electricity storage assets (e.g., batteries). The
time period T over which a suggested operating schedule for the
energy asset(s) may be determined according to the inventive
concepts disclosed herein may be a portion of an hour, an hour, a
period of multiple hours, a day, or a period of multiple days, for
example (which in some instances may be based, at least in part, on
time-varying wholesale electricity prices on a particular wholesale
electricity market from which revenue may be generated). Similarly,
the suggested operating schedule(s) for the energy assets(s) may be
determined based at least in part on wholesale prices of various
wholesale electricity "products" offered on the wholesale
electricity markets in which the energy customer may participate
(e.g., based on a geographic region in which the energy customer is
located) to earn energy-related revenue.
[0014] In one example implementation, as discussed in greater
detail below, the suggested operating schedule for one or more
energy assets is determined via a mathematical optimization process
that reduces a net energy-related cost to the energy customer over
the time period T by increasing projected energy-related revenue
from one or more wholesale electricity markets in which the energy
customer may participate.
[0015] Energy Asset Modeling
[0016] To facilitate the mathematical optimization process for
generating a suggested operating schedule for one or more energy
assets, a mathematical model representing the customer's energy
asset(s) is formulated and employed in the mathematical
optimization process. The energy asset model is specified by one or
more mathematical functions for calculating an energy profile
(i.e., electricity use and/or electricity generation as a function
of time over the time period T) for the asset(s), based on a
proposed operating schedule for the asset(s) applied as an input to
the model. In one example of an engineering-based model, the
mathematical function(s) defining the asset model at least in part
represent physical attributes of the energy asset(s) themselves
that relate to electricity use and/or electricity generation.
Depending on the energy asset(s) operated by the energy customer, a
given model may represent a single energy asset or an aggregation
of multiple energy assets operated by the customer.
[0017] Also, depending on the type of energy asset(s) being
modeled, the asset model may be formulated to accept additional
inputs to facilitate calculation of an energy profile based on a
proposed operating schedule. Herein, in various examples, energy
storage assets, energy consuming assets and/or energy generating
assets are being modeled. For example, in the case of controllable
energy assets, including energy consuming assets such as building
assets including heating, ventilation and air conditioning (HVAC)
systems for temperature control in one or more buildings, and/or
other assets for which thermodynamic considerations are relevant
(including weather- or temperature-dependent energy generating
assets including photovoltaic cells and wind turbines), the
mathematical model for the asset(s) may be configured to consider
as an input to the model actual or forecast ambient environmental
conditions (e.g., temperature, humidity, ambient light/cloud cover,
etc.) as a function of time, as well as other variables that may
impact thermodynamics or the energy profile in general (e.g.,
building occupancy, a presence of equipment such as computers and
other instrumentation that may affect heating or cooling in an
environment, etc.).
[0018] Customer Baseline (CBL) Energy Profiles for
Business-As-Usual (BAU) Operating Schedules
[0019] In some examples, the mathematical model for the energy
asset(s) first is used to generate a simulated (or "predictive")
customer baseline (CBL) energy profile corresponding to a typical
operating schedule (also referred to herein as a
"business-as-usual" (BAU) operating schedule, or "BAU conditions").
In particular, an energy customer's BAU operating schedule for its
energy asset(s) is applied to the mathematical model, which in turn
provides as an output a simulated CBL energy profile representing a
typical electricity consumption or generation as a function of
time, over a given time period T, for the modeled energy asset(s).
In one aspect, the energy customer's BAU operating schedule
represents the customer's typical behavior with respect to
operating its energy asset(s), absent any incentive to reduce
energy costs and/or earn energy-related revenue from the wholesale
electricity market.
[0020] As discussed in greater detail below, a simulated and
predictive CBL energy profile based on a mathematical model
according to the concepts disclosed herein provides a significant
improvement over conventional approaches to determine a frame of
reference for typical energy profiles of energy customers (absent
an incentive to generate revenue via wholesale electricity
markets); as noted above, conventional approaches are limited to
considering only historical actual energy use information. In
particular, it is recognized and appreciated herein that
conventional backward-looking assessment of CBL is not necessarily
representative of what an energy customer's electricity usage
actually would have been on a given day for which economic demand
response revenue is being calculated--at best, such
backward-looking historical actual-use-based assessments of CBL
provide inconclusive estimates.
[0021] Additionally, it has been observed empirically that an
historical actual-use CBL provides incentives for some energy
customers to artificially inflate energy usage (i.e., by not
operating energy assets pursuant to "business-as-usual" or BAU
conditions, but instead purposefully adopting higher-consumption
operating conditions) prior to a period in which the customer
anticipates participation in economic demand response wholesale
electricity markets; an artificially higher historic
actual-use-based CBL, against which energy use reduction will be
measured, provides a potentially higher economic demand response
revenue. In this manner, the general goal of economic demand
response programs to incentivize reduced electricity usage is
undermined (by an artificially-increased electricity usage to
establish a higher CBL).
[0022] Furthermore, the Inventors have recognized and appreciated
that an historical actual-use-based CBL provides a long-term
disincentive to participate in economic demand response wholesale
electricity markets. In particular, as a given energy customer
participates in economic demand response wholesale electricity
markets over time, their average actual electricity use from retail
suppliers is expected to decrease. If revenue from such markets
continues to be calculated with reference to an historical
actual-use-based CBL, the potential for economic demand response
revenue will decrease over time, as an economic settlement approach
based on historical actual-use CBL eventually will begin to treat
incentivized electricity use reduction as "business-as-usual"
operating conditions for the energy customer. This type of
treatment arguably will ultimately discourage participation in
wholesale electricity markets. At very least, continued reliance on
historical actual-use-based CBL likely will compel an extension of
a "look-back" period serving as a basis for determining CBL for
energy customers who actively participate in economic demand
response wholesale electricity markets for significant periods of
time. As longer look-back periods are adopted, the accuracy and
relevance of historic actual-use-based CBLs from more distant time
periods arguably will significantly decrease.
[0023] Accordingly, for at least the foregoing reasons, a simulated
and predictive CBL energy profile, based on a mathematical model of
an energy customer's energy asset(s) according to the concepts
disclosed herein (rather than an historical actual-use-based CBL as
conventionally employed), provides a significant improvement for
more accurately determining revenue earned from economic demand
response wholesale electricity markets. In some examples, the
mathematical model for the energy asset(s) may not be predicated on
any significantly historical actual electricity use information for
the energy asset(s), and instead may be based in part on physical
attributes of the energy asset(s) themselves that relate to
electricity use and/or electricity generation (such as for an
engineering-based building asset model), as noted above. In this
manner, simulated and predictive CBL energy profiles based on such
mathematical models are not substantively influenced by
significantly historical actual electricity use information.
[0024] An engineering-based energy asset model according to a
principle herein may adapt itself to the current conditions of an
energy asset. That is, the computation of the CBL calculations may
reflect temporary changes or permanent changes in the physical
characteristics of an energy asset (such as but not limited to
building insulation). Non-limiting examples of such changes include
but are not limited to changes in the building materials or
building construction, changes in the types of energy assets
present in the system, the types of temperature control systems
present in the system. The historical actual-use-based CBL may
capture permanent changes in the building asset as well
[0025] In other examples, the mathematical model for energy
asset(s) may be predicated on some degree of essentially real-time
or near real-time feedback (e.g., from one or more control systems
actually controlling the modeled energy asset(s)), which feedback
may represent actual electricity use. This feedback may be used,
according to some examples of the methods, apparatus and systems
disclosed herein, to refine some aspects of the mathematical model;
however, even when real-time or near real-time feedback
representing actual electricity use is employed, in some examples
the mathematical model is may be based on physical attributes of
the energy asset(s) themselves relating to electricity use and/or
electricity generation (such as for an engineering-based energy
asset model described herein).
[0026] Objective Cost Functions
[0027] In some examples, the mathematical model for the energy
asset(s) is employed to determine a suggested operating schedule
over a given time period T for the energy asset(s) (different than
the BAU operating schedule) based on a mathematical optimization of
an "objective cost function" representing the net energy-related
cost to the energy customer for operating the asset(s). In example
implementations, the objective cost function incorporates the
mathematical model for the energy asset(s) and specifies
energy-related revenues from one or more wholesale energy markets
(e.g., based on forecasted wholesale energy prices over the time
period T for the one or more wholesale markets of interest), from
which possible revenue may be available to the energy customer. In
some examples, the energy-related revenues specified in the
objective cost function may take into consideration a simulated
customer baseline (CBL) energy profile (discussed above) as a basis
for determining such revenue.
[0028] The objective cost function employed in the mathematical
optimization to determine a suggested operating schedule for the
energy asset(s) also may specify energy-related costs which are
offset by the energy-related revenues. In particular, in some
examples, the energy-related costs included in the objective cost
function may include "actual" energy-related costs. Non-limiting
examples of the "actual" energy-related costs include retail
electricity costs, wholesale electricity costs representing revenue
earned by the energy customer, fuel costs to run one or more
electricity generation assets, operation and/or maintenance costs
that may be associated with electricity generation and/or energy
storage assets, lifetime and/or replacement costs for electricity
generation and/or energy storage assets, emissions-related costs,
tariffs that can be leveled in the industry, demand charges that
can be leveled at times of peak energy usage, etc. The
energy-related costs included in the objective cost function
additionally or alternatively may include "indirect" energy-related
costs, such as convenience/comfort costs associated with the energy
customer's adoption of a suggested operating schedule different
than the BAU operating schedule (the convenience/comfort cost
represents an "indirect" cost associated with a change in the
customer's behavior with respect to operating its asset(s), based
on the incentive of possible energy-related revenue from the
wholesale electricity markets). The energy-related costs may also
include a reliability cost (such as based on any voltage/VAR
control activity in a microgrid application) and/or an emissions
cost based on an emissions market.
[0029] Optimization of Objective Cost Function for Generating
Energy Asset Operating Schedules
[0030] In one example, the objective cost function (which
incorporates the mathematical model of the energy asset(s)) may be
provided to an optimizer (a particularly-programmed processor, also
referred to as a "solver") that implements a mathematical
optimization process to determine a suggested operating schedule
for the energy asset(s) over a given time period T. In one
conceptual illustration of the mathematical optimization process,
some number N of candidate operating schedules are successively
applied to the mathematical model to generate simulated energy
profiles corresponding to the candidate operating schedules. A net
energy-related cost represented by the objective cost function is
calculated for each simulated energy profile, and the candidate
operating schedule that minimizes the objective cost function
(i.e., minimizes the net energy-related cost) is selected as the
suggested operating schedule. In some implementations, the amount
of revenue available from the relevant wholesale electricity
markets over the given time period T is a significant factor
dictating the candidate operating schedule that is provided as an
output of the optimizer. The energy-related costs may also include
a reliability cost (such as based on any voltage/VAR control
activity in a microgrid application) and/or an emissions cost based
on an emissions market.
[0031] Adopting Operating Schedules, Market Bids and Settlement
[0032] The suggested operating schedule in turn may be transmitted
to the energy customer (e.g., to an energy management system of the
energy customer, including a building management system), and the
customer may choose to adopt or not adopt the suggested operating
schedule to actually operate its energy asset(s) over the
particular time period T for which the optimization is performed.
In some implementations, a given operating schedule is transmitted
to the energy customer in the form of one or more bias signals
representing a change in an operating set point of one or more
assets, as a function of time over the time period T, from the
typical or "business-as-usual" (BAU) operating set point for the
asset(s). In some examples, the energy customer makes a choice to
adopt a given suggested operating schedule in tandem with making an
offer (a "bid") to provide one or more wholesale electricity market
products to the appropriate market pursuant to the adopted
operating schedule.
[0033] If the energy customer adopts the suggested operating
schedule to actually operate its energy asset(s) so as to provide a
particular wholesale electricity market product pursuant to an
accepted bid (e.g., reduce its energy consumption), various
information ultimately is obtained from the energy customer to
facilitate a "settlement" process pursuant to which the customer is
paid by the wholesale market operator (i.e., the RTO/ISO overseeing
the wholesale electricity market(s) in which the customer is
participating). For example, in one example relating to energy
markets (wherein the "product" is energy use curtailment), the
energy customer's "metered load" (i.e., actual energy use during
the time period T in which the suggested operating schedule is
adopted) is measured, and compared to a simulated CBL based on the
mathematical model for the customer's energy asset(s). The energy
customer may then be paid for its economic demand response
electricity use reduction based on a difference between the
simulated CBL and the actual metered load, multiplied by the actual
wholesale energy price during the time period T for the market in
question (e.g., LMP).
[0034] Apparatus, methods and computer-readable media are described
for determining a suggested operating schedule for at least one
energy asset operated by an energy customer. In an example, the
apparatus includes at least one communication interface, at least
one memory to store processing unit-executable instructions and an
objective function for the at least one energy asset, and at least
one processor unit communicatively coupled to the at least one
memory. The at least one energy asset includes at least one
controllable energy asset. The objective function facilitates a
determination of the suggested operating schedule for the at least
one energy asset based at least in part on a physical model of the
thermodynamic property of the at least one energy asset and at
least in part on data representative of model parameters. The model
parameters are: (a) an operation characteristic of the at least one
controllable energy asset, and (b) a projected environmental
condition during time period T. Upon execution of the processing
unit-executable instructions, the at least one processing unit: (A)
prior to time period T, determines the suggested operating schedule
based on an optimization of the objective function over time period
T, and (B) controls the at least one communication interface to
transmit to the energy customer the suggested operating schedule
determined in (A), and/or controls the at least one memory so as to
store the determined suggested operating schedule. The objective
function is determined based on a dynamic simulation model of the
energy profile of the at least one energy asset, a customer
baseline (CBL) energy profile for the at least one energy asset,
and a forecast wholesale electricity price associated with a
wholesale electricity market and/or a regulation price associated
with a regulation market, over time period T. The dynamic
simulation model is adaptive to physical changes in the at least
one energy asset based at least in part on the physical model of
the thermodynamic property of the at least one energy asset, and
the dynamic simulation model is trained using the data. The
operation of the at least one energy asset according to the
suggested operating schedule, over a time period T, facilitates
generation of energy-related revenue based at least in part on the
wholesale electricity market.
[0035] In an example, the CBL energy profile is computed based on
applying the dynamic simulation model to the data representative of
the operation characteristic of the at least one controllable
energy asset, the thermodynamic property of the building asset, and
an environmental condition, all during a time period TA prior to
time period T.
[0036] In an example, the data representative of the projected
environmental condition is data representative of at least one of
an ambient temperature of the environment in which the building
asset is located; a humidity of the environment in which the
building asset is located; an amount of solar irradiance of the
environment in which the building asset is located, an amount of
cloud cover of the environment in which the building asset is
located, an outside air temperature, an outside air humidity, an
outside air enthalpy, an outside air wet bulb temperature, a
dewpoint temperature, and a heat index.
[0037] In an example, the at least one energy asset comprises at
least one building asset. In an example implementation, the
physical model of the thermodynamic property of the at least one
building asset is determined based on at least in part on
state-space model computations of the at least one building asset,
and on data representative of at least one of an occupancy schedule
of the building asset, a relative humidity of the building asset, a
temperature of the building asset, and a lighting level of the
building asset.
[0038] In an example, the physical model of the thermodynamic
property of the at least one energy asset models a zone
temperature, and the zone temperature is computed based on at least
one heat-balance state-space model of the at least one energy
asset.
[0039] In an example, the at least one processing unit determines
the suggested operating schedule for the at least one energy asset
as at least one bias signal, as an interruptible load function, or
as at least one use modulation signal. In this example, the at
least one processing unit can determine the suggested operating
schedule for the at least one energy asset in (A) as at least one
bias signal, and controls the at least one communication interface
in (B) to transmit to the energy customer the at least one bias
signal at different times during time period T. In this example,
the at least one processing unit controls the at least one
communication interface to transmit to the energy customer the
suggested operating schedule as at least one use modulation signal,
and the operation of the at least one energy asset according to the
at least one use modulation signal causes a modulation with time of
the load use of the controllable energy asset.
[0040] In an example implementation, the dynamic simulation model
of the energy profile of the at least one energy asset can be a
semi-linear regression over at least one of the model parameters.
In this example, the dynamic simulation model of the energy profile
of the at least one energy asset can be a semi-linear regression
over at least one of a zone temperature of the at least one energy
asset, a load schedule of the at least one energy asset, the
projected environmental condition, and a control setpoint of the at
least one controllable energy asset. The zone temperature of the at
least one energy asset can be a semi-linear regression over at
least one of the projected environmental condition, the load
schedule of the at least one energy asset, and the control setpoint
of the at least one controllable energy asset.
[0041] In an example implementation, the dynamic simulation model
is trained using the data representative of the operation
characteristic of the at least one controllable energy asset and a
thermodynamic property of the at least one energy asset, during
operation of the at least one energy asset at under similar
environmental conditions to the projected environmental condition
during time period T.
[0042] In an example implementation, the dynamic simulation model
of the energy profile of the at least one energy asset can include
an environmental condition-independent load model and an
environmental condition-dependent load model.
[0043] In an example implementation, the at least one processing
unit can further: (C) determine an updated operating schedule for
the at least one energy asset, during time period T, based on
updated parameters of the suggested operating schedule, and (D)
controls the at least one communication interface to transmit to
the energy customer the updated operating schedule for at least one
energy asset determined in D), and/or controls the at least one
memory so as to store the determined updated operating schedule.
The updated parameters are determined using a feedback mechanism.
The feedback mechanism comprises comparing a predicted value of at
least one of the model parameters, computed using the suggested
operating schedule, to an actual value measured, during time period
T, of the respective at least one of the model parameters.
[0044] In an example implementation, the updated parameters of the
suggested operating schedule are computed based on Kalman
filtering.
[0045] In an example implementation, the at least one processing
unit determines the updated operating schedule for the at least one
energy asset as at least one bias signal, as an interruptible load
function, or as at least one use modulation signal.
[0046] Apparatus, methods and computer-readable media are described
for modeling of a building asset. The building asset models
generated using the apparatus, methods and computer-readable media
described herein facilitate revenue generation from wholesale
electricity markets. The wholesale electricity market may be an
energy market, a regulation market, and/or a spinning reserve
market. The revenue generation from the wholesale electricity
markets is based on the output of the building asset model. In an
example, the apparatus includes at least one communication
interface, at least one memory to store processor-executable
instructions and a mathematical model, and at least one processing
unit. The mathematical model is used to generate the building asset
model according to a method described herein, based at least in
part on at least one operation characteristic of the building
asset. The at least one processing unit is communicatively coupled
to the at least one communication interface and the at least one
memory. Upon execution of the processor-executable instructions,
the at least one processing unit determines the building asset
model using the mathematical model. Input to the mathematical model
includes at least one operation characteristic of the building
asset. Input to the mathematical model may include the time period
being modeled, and/or weather-related parameters, including outside
air temperature (OAT), outside air humidity (OAH), solar irradiance
(Q.sub.irradiance), and/or cloud cover. Upon execution of the
processor-executable instructions, the at least one processing unit
also controls the at least one communication interface to transmit
to the energy customer the determined building asset model, and/or
output generated based on the building asset model. In an example,
the output of the building asset model include values for building
zone air temperature and/or a set-point (SPT) for one or more
building components. In a non-limiting example, the building zone
air temperature is a return-air-temperature (RAT). In an example,
the output of the mathematical model include other parameters that
are determined based on the output of the building asset model such
as but not limited to including the building zone air temperature
(including a RAT), and/or the SPT. Output of the mathematical model
can include a projected value of energy usage.
[0047] In another example, a building asset model described herein
can be an engineering-based model. An example engineering-based
model described herein can be a two-node model that provides
improvement in thermodynamic and HVAC predictions with automated
parameter search and validation. An engineering-based model
described herein may provide an improvement on a physical model,
including a HVAC system model (such as a chiller model, AHU model,
ice-storage model, etc.). An example engineering-based model
described herein is applicable to a well-sensed buildings (for
which there is data on its operation characteristics, including the
operation characteristics of one or more of its components).
[0048] Apparatus, methods and computer-readable media are also
described for generating a building asset model to determine
operation parameters and operating schedules for at least one
building asset. In an example, the apparatus includes at least one
communication interface, at least one memory to store
processor-executable instructions and a mathematical model, and at
least one processing unit. The mathematical model is used to
generate the building asset model according to a method described
herein, based at least in part on at least one operation
characteristic of the building asset. The at least one processing
unit is communicatively coupled to the at least one communication
interface and the at least one memory. Upon execution of the
processor-executable instructions, the at least one processing unit
determines the building asset model using the mathematical model.
Input to the mathematical model includes at least one operation
characteristic of the building asset.
[0049] In one aspect, apparatus, methods and computer-readable
media are described for generating a day-ahead building asset model
to determine operation parameters and/or operating schedules for at
least one building asset. The apparatus includes at least one
communication interface, at least one memory to store
processor-executable instructions and a day-ahead building asset
model, and at least one processing unit. The day-ahead building
asset model is used to generate operation parameters and operating
schedules for at least one building asset according to a method
described herein, based at least in part on at least one operation
characteristic of the building asset. The at least one processing
unit is communicatively coupled to the at least one communication
interface and the at least one memory. Upon execution of the
processor-executable instructions, the at least one processing unit
determines the operation parameters and/or operating schedules for
at least one building asset using the day-ahead building asset
model. Input to the day-ahead building asset model includes at
least one operation characteristic of the building asset. For
example, input to the day-ahead building asset model may include
the time period being modeled, and/or weather-related parameters,
including outside air temperature (OAT), outside air humidity
(OAH), solar irradiance (Q.sub.irradiance), and/or cloud cover.
Upon execution of the processor-executable instructions, the at
least one processing unit also controls the at least one
communication interface to transmit to the energy customer the
determined operation parameters and/or operating schedules. In an
example, the operation parameters and/or operating schedules
include values for building zone air temperature (including a
return-air-temperature (RAT)) and/or a set-point (SPT) for one or
more building components. Output of the day-ahead building asset
model can be used to determine a projected value of energy usage.
The output of the day-ahead building asset model can be used to
project a day-ahead expected performance of at least one component
and/or system of the building asset when they are later
operated.
[0050] In one aspect, apparatus, methods and computer-readable
media are described for generating a real-time building asset model
to determine operation parameters and/or operating schedules for at
least one building asset. The apparatus includes at least one
communication interface, at least one memory to store
processor-executable instructions and a real-time building asset
model, and at least one processing unit. The real-time building
asset model is used to generate operation parameters and operating
schedules for at least one building asset according to a method
described herein, based at least in part on at least one operation
characteristic of the building asset. The at least one processing
unit is communicatively coupled to the at least one communication
interface and the at least one memory. Upon execution of the
processor-executable instructions, the at least one processing unit
determines the operation parameters and/or operating schedules for
at least one building asset using the real-time building asset
model. Input to the real-time building asset model includes a
measured value of at least one operation characteristic of the
building asset during real-time operation. For example, input to
the real-time building asset model may include weather-related
parameters, including outside air temperature (OAT), outside air
humidity (OAH), solar irradiance (Q.sub.irradiance), and/or cloud
cover. Upon execution of the processor-executable instructions, the
at least one processing unit also controls the at least one
communication interface to transmit to the energy customer the
determined operation parameters and/or operating schedules. In an
example, the operation parameters and/or operating schedules
include values for building zone air temperature (including a
return-air-temperature (RAT)) and/or a set-point (SPT) for one or
more building components. Output of the real-time building asset
model can used to determine a projected value of energy usage. The
output of the real-time building asset model can be used to adjust
or modify one or more operating schedules of the building asset
when it is being operated. In an example, the output of the
real-time building asset model can be used to adjust or modify one
or more operating schedules of the building asset when it is being
operated according to an output of a day-ahead building asset
model.
[0051] In one aspect, apparatus, methods and computer-readable
media are described for generating a day-after building asset model
to determine actual operation parameters of at least one building
asset. The apparatus includes at least one communication interface,
at least one memory to store processor-executable instructions and
a day-after building asset model, and at least one processing unit.
The day-after building asset model is used to generate operation
parameters for at least one building asset according to a method
described herein, based at least in part on at least one operation
characteristic of the building asset. The at least one processing
unit is communicatively coupled to the at least one communication
interface and the at least one memory. Upon execution of the
processor-executable instructions, the at least one processing unit
determines the operation parameters for at least one building asset
using the day-after building asset model. Input to the day-after
building asset model includes a measured value of at least one
operation characteristic of the building asset during a period of
operation of at least one component and/or system of the building
asset. For example, input to the day-after building asset model may
include the time period during which the building asset was
operated, and/or weather-related parameters, including outside air
temperature (OAT), outside air humidity (OAH), solar irradiance
(Q.sub.irradiance), and/or cloud cover. Upon execution of the
processor-executable instructions, the at least one processing unit
also controls the at least one communication interface to transmit
to the energy customer the determined actual operation parameters.
In an example, the actual operation parameters include values for
actual load and/or actual energy usage of the building asset. In an
example, the day-after building asset model can be used to
determine actual operation parameters of at least one building
asset that was operated according to operating schedules determined
using an output of a day-ahead building asset model and/or an
output of a real-time building asset model. The operation
parameters determined using the day-after building asset model can
be used for settlement purposes, e.g., to compute an amount of
energy-related revenue due to the energy customer. Output of the
day-after building asset model can used to determine a projected
value of energy usage.
[0052] Apparatus, methods and computer-readable media are described
for applying a different building asset models at different stages
during operation of at least one component and/or system of the
building asset. In different examples, the building asset model is
a day-ahead building asset model, a real-time building asset model,
or a day-after building asset model. The apparatus, methods and
computer-readable media can be used to generate the day-ahead
building asset model, and/or to apply the day-ahead building asset
model to input parameters characteristic of the building asset to
project a day-ahead expected performance of at least one component
and/or system of the building asset prior to operation. In an
example, the output of the day-ahead building asset model is used
in computation of an objective cost function. In an example, the
output of the day-ahead building asset model is used in computation
of an energy-related revenue. The apparatus, methods and
computer-readable media can be used to generate the real-time
building asset model, and/or to apply the real-time building asset
model to model a real-time performance of at least one component
and/or system of the building asset during the time period that
they are operated. The apparatus, methods and computer-readable
media can be used to generate the day-after building asset model,
and/or to apply the day-after building asset model to model an
actual performance of at least one component and/or system of a
building asset after they have been operated. In an example, the
output of the day-after building asset model is used in computation
of an objective cost function. In an example, the output of the
day-after building asset model is used in computation of an
energy-related revenue.
[0053] Apparatus, methods and computer-readable media are also
described for applying a building asset model, including a
day-ahead building asset model, a real-time building asset model,
or a day-after building asset model, to determine operation
parameters and, where pertinent, operating schedules, for
controllers of one or more components of the building asset.
[0054] Apparatus, methods and computer-readable media are also
described for generating a seasonal building asset model. For
example, the building asset model developed to model the building
asset for a summer season can differ from the building asset model
developed to model the building asset for a fall, winter, or spring
season, based on the differing environmental and weather conditions
and responses thereto. In an example, a seasonal building asset
model is generated by varying temperature-related terms. The
seasonal building asset model can be developed as a day-ahead
building asset model, a real-time building asset model, or a
day-after building asset model, to determine operation parameters
and operating schedules for the building asset or for one or more
components of the building asset. In another example, the seasonal
building asset model can be developed as a day-ahead building asset
model, a real-time building asset model, or a day-after building
asset model, to determine operation parameters and, where
pertinent, operating schedules, for the controllers of one or more
components of the building asset.
[0055] Apparatus, methods and computer-readable media described
herein can be used for determining an operating schedule of at
least one controller of at least one energy asset so as to generate
energy-related revenue, over a time period T, associated with
operation of the at least one energy asset according to the
operating schedule. The energy-related revenue available to the
energy customer over the time period T is based at least in part on
at least one wholesale electricity market. The apparatus includes
at least one communication interface, at least one memory to store
processor-executable instructions and a mathematical model for the
at least one energy asset, and at least one processing unit. The
mathematical model facilitates a determination of the operating
schedule for the controllers based at least in part on an operation
characteristic of the at least one energy asset and forecast
wholesale electricity prices associated with the at least one
wholesale electricity market. The at least one processing unit is
configured to determine the operating schedule for the at least one
controller of the at least one energy asset using the mathematical
model by minimizing a net energy-related cost over the time period
T. The net-energy related cost is based at least in part on at
least one energy supply cost and at least one demand response
revenue. The operating schedule specifies, during a time interval
within the time period T, conditions for use of the at least one
energy asset in respective ones of the at least one energy market.
The at least one processing unit is also configured to control the
at least one communication interface to transmit to the energy
customer the operating schedule for the at least one controller of
the at least one energy asset, control the at least one memory so
as to store the determined operating schedule for the at least one
controller, and/or control the at least one communication interface
to transmit to the at least one controller of at least one energy
asset the operating schedule. The energy asset can include at least
one of an energy storage asset, an energy generating asset, an
energy consuming asset, or any combination thereof. The at least
one wholesale electricity market can be at least one of an energy
market, a regulation market, a spinning reserve market, or any
combination thereof. The forecast wholesale electricity prices
associated with the energy market can be a wholesale price. The
forecast wholesale electricity prices associated with the
regulation market can be a regulation price. The forecast wholesale
electricity prices associated with the spinning reserve market can
be a spinning reserve market price.
[0056] At least one computer-readable storage medium is provided
herein. The at least one computer-readable storage medium is
encoded with instructions that, when executed using at least one
processor unit described herein, performs a method according to a
principle described herein. For example, the method can be for
modeling a building asset and/or for applying a building asset
model to operation characteristics of a building asset to generate
an operating schedule for the building asset or for a controller of
at least component of the building asset.
[0057] The following patent applications are hereby incorporated
herein by reference in their entirety:
[0058] U.S. Provisional Application No. 61/477,067, filed on Apr.
19, 2011;
[0059] U.S. Provisional Application No. 61/552,982, filed on Oct.
28, 2011;
[0060] U.S. Non-provisional application Ser. No. 12/850,918, filed
on Aug. 5, 2010; and
[0061] U.S. Provisional Application No. 61/279,589, filed on Oct.
23, 2009.
[0062] The entire disclosure of these applications is incorporated
herein by reference in its entirety, including drawings,
[0063] It should be appreciated that all combinations of the
foregoing concepts and additional concepts discussed in greater
detail below (provided such concepts are not mutually inconsistent)
are contemplated as being part of the inventive subject matter
disclosed herein. In particular, all combinations of claimed
subject matter appearing at the end of this disclosure are
contemplated as being part of the inventive subject matter
disclosed herein. It should also be appreciated that terminology
explicitly employed herein that also may appear in any disclosure
incorporated by reference should be accorded a meaning most
consistent with the particular concepts disclosed herein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0064] The skilled artisan will understand that the drawings
primarily are for illustrative purposes and are not intended to
limit the scope of the inventive subject matter described herein.
The drawings are not necessarily to scale; in some instances,
various aspects of the inventive subject matter disclosed herein
may be shown exaggerated or enlarged in the drawings to facilitate
an understanding of different features. In the drawings, like
reference characters generally refer to like features (e.g.,
functionally similar and/or structurally similar elements).
[0065] FIG. 1 shows an example system that includes an energy
asset, according to a principle described herein.
[0066] FIG. 2 shows an example system that includes an energy asset
and a controller, according to a principle described herein.
[0067] FIG. 3 shows an example apparatus according to a principle
described herein.
[0068] FIG. 4 illustrates an example block diagram representing an
asset model according to a principle described herein.
[0069] FIG. 5 illustrates an example block diagram representing
another asset model according to a principle described herein.
[0070] FIG. 6 illustrates an example block diagram representing
another asset model according to a principle described herein.
[0071] FIG. 7 illustrates an example block diagram representing
another asset model according to a principle described herein.
[0072] FIG. 8 illustrates an example block diagram representing
another asset model according to a principle described herein.
[0073] FIG. 9 summarizes a non-limiting example of a day-ahead
engineering-based model, a real-time engineering-based model, and a
day-after engineering-based model, according to a principle
described herein;
[0074] FIG. 10 shows an example of an effective element
representation of a building asset according to a principle
described herein.
[0075] FIG. 11A-11E show the example nodes of the effective element
representation of FIG. 10, according to a principle described
herein.
[0076] FIG. 12A-12B show example matrices for solving for the
coefficients of effective element representations of a building
asset according to a principle described herein.
[0077] FIG. 13 shows flowcharts of example procedures for
generating and training dynamic simulation load models and dynamic
simulation temperature models according to a principle described
herein.
[0078] FIG. 14 shows an example Kalman Filter process according to
a principle described herein.
[0079] FIG. 15 shows an example day-after engineering-based model
based on a neural network model according to a principle described
herein.
[0080] FIG. 16 shows an example day-after engineering-based model
based on a neural network model implemented in a parallel
architecture and a series-parallel architecture according to a
principle described herein.
[0081] FIG. 17 is an example plot showing the relationship between
different values of the comfort index (CI), the outside air
humidity and the humidity according to a principle described
herein.
[0082] FIG. 18 shows an example functional block diagram of a PID
controller according to a principle described herein.
[0083] FIG. 19 shows an example functional block diagram of a
configuration of a system and apparatus for implementing an example
CBL computation according to a principle described herein.
[0084] FIG. 20 shows an example functional block diagram of a
configuration of a system and apparatus for implementing an example
day-ahead engineering-based model according to a principle
described herein.
[0085] FIG. 21 shows an example functional block diagram of a
configuration of a system and apparatus for implementing an example
real-time engineering-based model according to a principle
described herein.
[0086] FIG. 22 shows an example functional block diagram of a
configuration of a system and apparatus for implementing an example
day-after engineering-based model according to a principle
described herein.
[0087] FIG. 23 illustrates a block diagram of an example energy
management environment that includes an energy management system to
facilitate generation of revenue from wholesale electricity
markets, according to a principle described herein;
[0088] FIG. 24 illustrates a block diagram showing additional
details of the example energy management system of FIG. 23,
according to a principle described herein;
[0089] FIG. 25 illustrates a block diagram of an example schedule
builder module of the example energy management system of FIG. 24,
according to a principle described herein;
[0090] FIG. 26 shows an example of an implementation based on an
example suggested operating schedule, according to a principle
described herein.
[0091] FIG. 27 shows an example energy storage asset optimization
according to a principle described herein.
DETAILED DESCRIPTION
[0092] Following below are more detailed descriptions of various
concepts related to, and embodiments of, inventive methods,
apparatus, and systems for determining a suggested operating
schedule for energy assets to facilitate revenue generation from
wholesale electricity markets. The systems, methods and apparatus
described herein can be applied to a building asset. The output of
the different models also can be used for determining a suggested
operating schedules for the building asset. It should be
appreciated that various concepts introduced above and discussed in
greater detail below may be implemented in any of numerous ways, as
the disclosed concepts are not limited to any particular manner of
implementation. Examples of specific implementations and
applications are provided primarily for illustrative purposes.
[0093] As used herein, the term "includes" means includes but not
limited to, the term "including" means including but not limited
to. The term "based on" means based at least in part on.
[0094] As used herein, the term "in communication with" includes
direct communication between elements as well as indirect
communication between the elements, such as by means of at least
one intermediate component. As used herein, the term "in electrical
communication with" includes direct electrical communication
between elements as well as indirect electrical communication
between the elements, such as by means of at least one intermediate
component.
[0095] The methods, apparatus, and systems disclosed herein provide
resources by which a certain environment that includes one or more
energy assets is modeled, energy use and/or generation profiles of
the assets may be simulated based on the model(s), and operating
schedules for the energy asset(s) may be suggested, based on such
simulations, to facilitate revenue generation from one or more
wholesale electricity markets for energy customers overseeing the
environment (e.g., operating the energy asset(s) within the
environment). Environments including one or more of a wide variety
of energy assets are contemplated, examples of which include, but
are not limited to, a building or group of buildings that include
one or more energy-consuming and/or energy-generating assets (e.g.,
heaters, HVAC systems, chillers/ice makers, fossil-fuel-based
and/or renewable electricity generators, energy storage devices),
as well as other environments in which one or more building may not
be involved (but which may nonetheless include one or more energy
assets).
[0096] In some examples, optimization software constituting an
"optimizer" module (also referred to as a "solver" or simply
"optimizer") is used to perform an optimization process to
determine suggested operating schedules for one or more energy
assets that minimize net energy-related costs for the energy
customer. In one aspect, the optimization process is based at least
in part on balancing respective energy-related costs and
energy-related revenues in connection with the energy customer's
operating environment and assets therein, in consideration of
wholesale electricity prices as a function of time. In other
aspects, an "objective cost function" that represents the net
energy-related cost as a function of an operating schedule for the
energy asset(s) and a mathematical model for the energy asset(s)
may include multiple constituent components, examples of which
include, but are not limited to: [0097] 1. a convenience or comfort
cost associated with deviation from the CBL or business-as-usual
(BAU) operating schedule, [0098] 2. a cost associated with electric
power production by the customer's energy generating assets (if
any), [0099] 3. a cost associated with electric power supply from a
retail electricity supplier, and [0100] 4. a cost associated with
economic demand response (DR) revenue from one or more wholesale
electricity markets.
[0101] Accordingly, salient aspects of example methods, apparatus
and systems according the principles described herein are to
provide energy asset management capabilities for reducing retail
electricity costs by optimizing electricity usage, generation, and
storage, while at the same time providing significant revenue
opportunities in markets, including wholesale electricity markets,
in regulation markets, in synchronized reserve markets and/or in
emissions markets.
[0102] In an example, an optimization module of an example energy
management system according to the principles described herein can
be used to perform an optimization process. In a non-limiting
example, the optimization process can be performed as a staged
process. In a stage of the optimization process, a computation can
be performed to calculate how a system including at least one
energy asset responds on a normal day using the default settings of
the energy assets and with no outside intervention. The result can
be used to determine a business-as-usual (BAU) schedule. A customer
baseline (CBL) schedule can be derived based on applying a
mathematical model to the BAU schedule. Alternatively, a
predetermined CBL or BAU schedule may be introduced into the
optimization process rather than calculated. Additionally, the
optimization may be used to determine the financial impact with
respect to the CBL schedule or the BAU schedule. In another stage
of the optimization process, an optimization can be run with
certain operating changes that may be entered by a system operator
of the energy management system. This stage may also factor in
energy prices and/or emissions trading prices. Again, the
optimization module may be used to determine the financial impact
of the optimized operating schedule, preferably showing the
financial benefit thereof as compared with a BAU schedule.
[0103] The apparatus and methods described herein are applicable to
a system that includes an energy asset 1. The energy asset 1 can be
a building asset. In the non-limiting example of FIG. 1, the energy
asset 1 is in communication with a power grid 2 (as depicted in the
example of FIG. 1). As depicted in the non-limiting example of FIG.
1, the energy asset 1 may be located behind a power meter 3. For
example, the energy asset 1 may be one or more facilities of the
energy consumer.
[0104] The apparatus and methods described herein are also
applicable to a system that includes an energy asset 1 and a
controller 4 in communication with at least one component of the
energy asset 1, where the energy asset 1 and the controller 4 are
in communication with a power grid 2 (as depicted in the example of
FIG. 2). The controller 4 facilitates operating the one or more
components of the energy asset 1 according to an operating schedule
and/or operation parameters generated using a building asset model
described herein. As depicted in the non-limiting example of FIG.
2, the controller 4 and the energy asset 1 may be located behind a
power meter 5. For example, the energy asset 1 may be one or more
facilities of the energy consumer and the controller 4 may be
located at any of the one or more facilities.
[0105] In any of the apparatus, methods, and/or computer readable
media described herein, the building asset model can be an
engineering-based model. For example, any of the day-ahead building
asset models, the real-time building asset models, or day-after
building asset models described herein can be an engineering-based
model. In an example, a combination of various types of
engineering-based models may be applied a given building asset as a
day-ahead building asset model, a real-time building asset model,
or a day-after building asset model. Various examples and aspects
of engineering-based building asset models that are applicable to
any of the apparatus, methods, and/or computer readable media are
described herein.
[0106] The output of the building asset models described herein may
be used to operate an energy asset in a way that facilitates
generation of energy-related revenue for an energy customer of an
electricity supplier. The energy customer may commit an amount of
energy or energy curtailment from the at least one energy asset to
an energy market. In an example, the electricity supplier may be a
retail electricity supplier that supplies the electricity to the
energy customer at a retail price. In another example, the
electricity supplier may supply the electricity to the energy
customer at a contracted for or negotiated price. In various
examples herein, the energy customer may allow an amount of
capacity of the energy asset to be committed to the energy
market.
[0107] In a non-limiting example, an apparatus or a method
described herein can be used to generate an operating schedule for
a controller that communicates with the energy asset and/or at
least one component of the energy asset. The controller is capable
of exercising an amount of control over the energy asset and/or at
least one component of the energy asset. Operation of the
controller, and hence the energy asset and/or at least one
component of the energy asset, according to the operating schedule
generated by a principle herein over the specified time period may
generate for the energy customer an amount of energy-related
revenue based at least in part on a wholesale electricity
market.
[0108] A non-limiting example of the apparatus 10 according to the
principles described herein is illustrated in FIG. 3. The apparatus
10 includes at least one communication interface 11, at least one
memory 12, and at least one processing unit 13. The at least one
processing unit 13 is communicatively coupled to the at least one
communication interface 11 and the at least one memory 12.
[0109] The at least one memory 12 is configured to store
processor-executable instructions 14 and a mathematical model 15.
In a non-limiting example, the mathematical model 15 can be used to
generate the building asset model according to a method described
herein, based at least in part on at least one operation
characteristic of the building asset. In another non-limiting
example, the mathematical model can be used to determine an
operating schedule for a controller of one or more components of a
building asset based on data 16 associated with parameters,
including but not limited to, an operation characteristic of the
energy asset and a forecast wholesale electricity price associated
with the wholesale electricity market.
[0110] In any of the examples according to the principles described
herein, the mathematical model 15 can include the dynamic
simulation model.
[0111] In an example, the wholesale electricity price for a market
differs according to the time period in the day, e.g., during
on-peak times versus off-peak times. In an example, the forecast
wholesale electricity prices used in the computation of the
day-ahead building asset model may be the same as the wholesale
electricity prices used for the real-time model and for the
day-after model. In another example, the forecast wholesale
electricity prices used in the computation of the day-ahead
building asset model may differ from the wholesale electricity
prices used for the real-time model, which in turn may differ from
the wholesale electricity prices used for the day-after model. In
an example, the wholesale electricity price is computed as a budget
or actual market prices on the day that the systems of the building
asset is run, as compared to a forecasted wholesale electricity
price for the day-ahead model. In an example, the wholesale
electricity prices, including the forecast wholesale electricity
prices, may be set by a market operator (such as but not limited to
a RTO), or other third party provider.
[0112] In a non-limiting example, the at least one processing unit
13 executes the processor-executable instructions 14 stored in the
memory 12 at least to determine the building asset model using the
mathematical model 15. The at least one processing unit 13 also
executes processor-executable instructions 14 to control the
communication interface 11 to transmit to the energy customer 17
the building asset model that has been determined and/or controls
the memory 12 to store the determined building asset model.
[0113] In an example, the at least one processing unit 13 executes
the processor-executable instructions 14 stored in the memory 12 at
least to determine the building asset model using the mathematical
model 15 as an engineering-based model. An example
engineering-based model described herein can be a single-node or a
two-node model that provides improvement in thermodynamic and HVAC
predictions with automated parameter search and validation. An
engineering-based model described herein may provide an improvement
on a physical model, including a HVAC system model (such as a
chiller model, AHU model, ice-storage model, etc.). In an example,
the engineering-based model includes one or more equations and/or
parameters that are based on physical components and/or systems in
the buildings. For example, an engineering-based model can be
developed to take into account the thermodynamics of some
components (e.g., using a thermodynamic equation for a HVAC), the
heat conduction or other energy exchange of the building asset
based on a temperature difference between the inside and outside of
the building (modeled as a circuit element equation). An example
engineering-based model described herein is applicable to a sensed
buildings (for which there is data on its operation
characteristics, including the operation characteristics of one or
more of its components). In another example, an engineering-based
model described herein is applicable to a sensed buildings for
which some amount of input data for an operation characteristic of
one or more components may be inferred (i.e., estimated or
projected).
[0114] Upon execution of the processor-executable instructions, the
at least one processing unit also controls the at least one
communication interface to transmit to the energy customer the
determined building asset model, and/or output generated based on
the building asset model. In an example, the output of the building
asset model includes values for building zone air temperature
(including a return-air-temperature (RAT)) and/or a set-point (SPT)
for one or more building components. In an example, the output of
the mathematical model include other parameters that are determined
based on the output of the building asset model such as but not
limited to the building zone air temperature (including a RAT)
and/or the SPT. Output of the mathematical model can include a
projected value of energy usage.
[0115] In a non-limiting example, the at least one processing unit
13 executes the processor-executable instructions 14 stored in the
memory 12 at least to generate a building asset model to determine
operation parameters and/or operating schedules for at least one
building asset. The mathematical model 15 is used to generate the
building asset model according to a method described herein, based
at least in part on at least one operation characteristic of the
building asset. Upon execution of the processor-executable
instructions 14, the at least one processing unit 13 determines the
building asset model using the mathematical model 15. Input to the
mathematical model 15 includes at least one operation
characteristic of the building asset.
[0116] In a non-limiting example, other possible input to the model
include information about weather condition, solar radiance, degree
of cloud cover, outside air temperature, or outside air
humidity.
[0117] The at least one operation characteristic of the building
asset in any of the building asset models described herein can be
at least one of a zone temperature, a prior load, a HVAC schedule,
a control setpoint, or a HVAC temperature.
[0118] The determined operation parameters and/or operating
schedules for the at least one building asset can be at least one
of a building zone air temperature (including a return air
temperature (RAT)), a setpoint (SPT), a zone temperature, a load,
or an HVAC schedule. In any of the examples described herein, the
RAT can be used as an indicator of the zone temperature
(T.sub.z).
[0119] In one aspect, the at least one processing unit 13 executes
the processor-executable instructions 14 stored in the memory 12 at
least to generate a day-ahead building asset model to determine
operation parameters and/or operating schedules for at least one
building asset. The day-ahead building asset model is used to
generate operation parameters and operating schedules for at least
one building asset according to a method described herein, based at
least in part on at least one operation characteristic of the
building asset. Output of the day-ahead building asset model can
used to determine a projected value of energy usage. The output of
the day-ahead building asset model can be used to project a
day-ahead expected performance of at least one component and/or
system of the building asset when they are later operated.
[0120] In one aspect, the at least one processing unit 13 executes
the processor-executable instructions 14 stored in the memory 12 at
least to generate a real-time building asset model to determine
operation parameters and/or operating schedules for at least one
building asset. The real-time building asset model is used to
generate operation parameters and operating schedules for at least
one building asset according to a method described herein, based at
least in part on at least one operation characteristic of the
building asset. Output of the real-time building asset model can
used to determine a projected value of energy usage. The output of
the real-time building asset model can be used to adjust or modify
one or more operating schedules of the building asset when it is
being operated. In an example, the output of the real-time building
asset model can be used to adjust or modify one or more operating
schedules of the building asset when it is being operated according
to an output of a day-ahead building asset model.
[0121] In one example, the at least one processing unit 13 executes
the processor-executable instructions 14 stored in the memory 12 at
least to generate a day-after building asset model to determine
actual operation parameters of at least one building asset. The
day-after building asset model is used to compute actual operation
parameters for at least one building asset according to a method
described herein, based at least in part on at least one operation
characteristic of the building asset. In an example, the actual
operation parameters include values for actual load and/or actual
energy usage of the building asset. In an example, the day-after
building asset model can be used to determine actual operation
parameters of at least one component or system of a building asset
that was operated according to operating schedules determined using
an output of a day-ahead building asset model and/or an output of a
real-time building asset model. Output of the day-after building
asset model can used to determine a projected value of energy
usage. The operation parameters determined using the day-after
building asset model can be used for settlement purposes, e.g., to
compute an amount of energy-related revenue due to the energy
customer. For example, the day-after building asset model can be
used to model actual readings of components or systems of a
building asset when, e.g., the HVAC is run, the zone temperature
(including the RAT) is measured, electricity used, and so can be
used to model the actual energy usage of a building asset.
[0122] In one example, the at least one processing unit 13 executes
the processor-executable instructions 14 stored in the memory 12 at
least to apply different building asset models at different stages
during operation of at least one component and/or system of the
building asset. In different examples, the building asset model is
a day-ahead building asset model, a real-time building asset model,
or a day-after building asset model. The at least one processing
unit 13 may execute the processor-executable instructions 14 stored
in the memory 12 at least to generate the day-ahead building asset
model, and/or to apply the day-ahead building asset model to input
parameters characteristic of the building asset to project a
day-ahead expected performance of at least one component and/or
system of the building asset and/or operating parameters of the
building asset prior to operation of at least one component and/or
system of the building asset. In an example, the at least one
processing unit 13 may execute the processor-executable
instructions 14 stored in the memory 12 at least to compute an
objective cost function based on the output of the day-ahead
building asset model. In an example, the at least one processing
unit 13 may execute the processor-executable instructions 14 stored
in the memory 12 at least to compute an energy-related revenue
based on the output of the day-ahead building asset model for
settlement purposes. The at least one processing unit 13 may
execute the processor-executable instructions 14 stored in the
memory 12 at least to generate the real-time building asset model,
and/or to apply the real-time building asset model to model a
real-time performance of at least one component and/or system of
the building asset during the time period that the building is
operated (and possibly modify the operating schedule based on
application of Kalman filtering to update the model). The at least
one processing unit 13 may execute the processor-executable
instructions 14 stored in the memory 12 at least to generate the
day-after building asset model, and/or to apply the day-after
building asset model to determine an actual performance of at least
one component and/or system of a building asset after they have
been operated. In an example, the at least one processing unit 13
may execute the processor-executable instructions 14 stored in the
memory 12 at least to compute an objective cost function based on
the output of the day-after building asset model. In an example,
the at least one processing unit 13 may execute the
processor-executable instructions 14 stored in the memory 12 at
least to compute an energy-related revenue based on the output of
the day-after building asset model for settlement purposes.
[0123] In a non-limiting example, the day-ahead building asset
model, the real-time building asset model and the day-after
building asset model are applied in time-order sequence to a single
building asset or collection of building assets.
[0124] In another non-limiting example, the day-ahead building
asset model, the real-time building asset model and the day-after
building asset model are applied to a single building asset or
collection of building assets in the same given day. For example,
on a given day the at least one processing unit 13 may apply to the
building asset (or collection of building assets):
(i) a day-after building asset model to determine the operating
schedule for the following day, to project a day-ahead expected
performance of at least one component and/or system of the building
asset and/or operating parameters of the building asset; (ii) a
real-time building asset model possibly to modify the operating
schedule based on application of Kalman filtering to update the
model as the given day progresses; and (iii) a day-after building
asset model to determine the actual performance of at least one
component and/or system of a building asset based on its operation
the previous day, e.g., with the computation of energy-related
revenue, for settlement purposes.
[0125] In an example, the at least one processing unit 13 executes
the processor-executable instructions 14 stored in the memory 12 at
least to apply a building asset model, including a day-ahead
building asset model, a real-time building asset model, or a
day-after building asset model, to determine operation parameters
and, where pertinent, operating schedules, for controllers of one
or more components of the building asset.
[0126] In a non-limiting example, the at least one processing unit
13 executes the processor-executable instructions 14 stored in the
memory 12 at least to determine the operating schedule for the
controller of the energy asset using the mathematical model 15. The
at least one processing unit 13 also executes processor-executable
instructions 14 to control the communication interface 11 to
transmit to the energy customer 17 the operating schedule that has
been determined for the controller and/or controls the memory 12 to
store the determined operating schedule for the controller. In a
non-limiting example, the processing unit 13 may execute
processor-executable instructions 14 to control the communication
interface 11 to transmit to the operating schedule directly to the
controller.
[0127] In a non-limiting example, the at least one processing unit
13 executes the processor-executable instructions 14 stored in the
memory 12 at least to determine an operating schedule of at least
one controller of at least one energy asset so as to generate
energy-related revenue, over a time period T, associated with
operation of the at least one energy asset according to the
operating schedule. The energy-related revenue available to the
energy customer over the time period T is based at least in part on
at least one wholesale electricity market. The mathematical model
15 facilitates a determination of the operating schedule for the
controllers based at least in part on an operation characteristic
of the at least one energy asset and forecast wholesale electricity
prices associated with the at least one wholesale electricity
market. The at least one processing unit 13 is configured to
determine the operating schedule for the at least one controller of
the at least one energy asset using the mathematical model 15 by
minimizing a net energy-related cost over the time period T. The
net-energy related cost is based at least in part on at least one
energy supply cost and at least one demand response revenue. The
operating schedule specifies, during a time interval within the
time period T, conditions for use of the at least one energy asset
in respective ones of the at least one energy market. The at least
one processing unit 13 is also configured to control the at least
one communication interface 11 to transmit to the energy customer
17 the operating schedule for the at least one controller of the at
least one energy asset, control the at least one memory so as to
store the determined operating schedule for the at least one
controller, and/or control the at least one communication interface
to transmit to the at least one controller of at least one energy
asset the operating schedule. The energy asset can include at least
one of an energy storage asset, an energy generating asset, an
energy consuming asset, or any combination thereof. The at least
one wholesale electricity market can be at least one of an energy
market, a regulation market, a spinning reserve market, or any
combination thereof. The forecast wholesale electricity prices
associated with the energy market can be a wholesale price. The
forecast wholesale electricity prices associated with the
regulation market can be a regulation price. The forecast wholesale
electricity prices associated with the spinning reserve market can
be a spinning reserve market price.
[0128] The operation characteristic of the energy storage asset may
be its state of charge, charge rate, the degree of non-linearity of
the charge rate, discharge rate, degree of non-linearity of the
discharge rate, round trip efficiency, and degree of life
reduction. In an example where the operation characteristic of the
energy storage asset is its charge rate and/or discharge rate, the
operating schedule for the controller may include suggested
different time intervals for charging the energy storage asset or
discharging the energy storage asset during the time period T that
the system is in operation.
[0129] The optimized operating schedule according to the systems,
apparatus and methods described herein is based on an optimization
of an objective cost function over an entire time period T. The
optimized schedule results from the maximization of the economic
benefit, given constraints on the controls or on the states, or
more generally from the minimization or maximization of an
objective function. As a non-limiting example, the suggested
operating schedule may calls for a counter-intuitive action, such
as sending a signal to a controller to increase a load, e.g., to
charge an energy storage asset (such as a battery) or increase the
load of another type of controllable energy asset (such as a HVAC),
even during a time interval when the forecast prices are expected
to be higher. The optimization according to the principles
described herein evaluate the various actions and responses of the
energy assets over the entire time period Tin order to optimize the
objective cost function, e.g., to maximize the economic benefit,
given constraints on the controls or on the states. Accordingly,
implementation of a suggested operating schedule generated
according to the system, method or apparatus described herein can
result in actions that differ from more heuristic approaches.
[0130] In an example, the operation characteristic of an energy
asset may be its load use schedule. For example, the operation
characteristic of the energy asset can be its energy consumption
profile as a function of time. The energy consumption
characteristics of a controllable energy asset may be modified by
changing parameters of operation of the system. A non-limiting
example of an operation characteristic for a controllable energy
asset is its set point. The set point may be a controllable set
point, e.g., it may be controllable as a function of time or
temperature. For example, where the controllable energy asset is a
building with a variable internal temperature controlled by a
heating, ventilation and air conditioning (HVAC) system, the
operation characteristic may be a temperature set point for the
HVAC system. In another example, the operation characteristic may
be a setting of the component. For example, where the component is
a HVAC or a chiller, the operation characteristic may be a cooling
rate/speed of the HVAC or a chill rate of the chiller,
respectively.
[0131] As described herein, in an example, an amount of energy of
the energy storage asset may be generated and supplied to the power
line at a discharge rate to generate energy-related revenue for the
energy customer in an energy market. The energy-related revenue can
depend on a forecast wholesale electricity price associated with
the wholesale electricity market, and may be determined based on
computation of a net-energy related cost. The net energy related
cost may be computed based on the supply costs for supplying
electricity to the customer and a demand response revenue. An
apparatus and method herein can be implemented to generate an
operating schedule for the controller of the energy storage asset
that provides recommendations for the timing of charging and
discharging of the energy storage asset.
[0132] In an example, the processing unit 13 can be configured to
determine the operating schedule for the controller of the at least
one energy asset using the mathematical model 15 by minimizing a
net energy-related cost over a relevant time period (T). The net
energy-related cost can be associated with electricity generation
by the energy storage asset, electricity consumption by the energy
storage asset, and electricity consumption by the energy consuming
asset. Here, the energy-related revenue available to the energy
customer may be computed based at least in part on the minimized
net energy-related cost.
[0133] The net energy-related cost may be specified as a difference
between the electricity supply cost and the economic demand
response revenue over the pertinent time period.
[0134] In an example, the processing unit 13 can be configured to
determine the operating schedule for the controller using the
mathematical model and a representative customer baseline (CBL)
energy profile for the energy consuming asset over the time period
(T). As used herein, the term "representative customer baseline
energy profile" or "representative CBL energy profile" encompasses
representations of the energy customer's energy usage in the
absence of change of behavior according to the principles described
herein. As non-limiting examples, the "representative customer
baseline energy profile" or "representative CBL energy profile"
includes an estimation based on the energy customer's
business-as-usual (BAU) operations, including any form of averaged
or weighted measure based on measures of historical BAU operations.
Herein, the representative CBL energy profile represents a typical
operation of the at least one energy consuming asset by the energy
customer. For example, where the energy consuming asset is a
fixed-load asset, the representative CBL may be determined as the
energy consumption profile for the energy consuming asset.
[0135] Where the operating schedule for the controller is generated
based on using the mathematical model and a representative customer
baseline (CBL) energy profile, the economic demand response revenue
may be computed based on the forecast wholesale electricity price,
the electricity generation by the energy storage asset, the
electricity consumption by the energy storage asset, and the
representative CBL energy profile for the energy consuming asset.
The values of economic demand response revenue computed according
to a principle herein may be used for settlement purposes. For
example, the values of economic demand response revenue computed
according to a principle herein may be provided to an energy
supplier for settlement purposes.
[0136] In an example herein, a portion of the energy of the energy
storage asset may be committed to the regulation market. That is,
the wholesale electricity market for the energy customer would
include an energy market and a regulation market. In an example
where the forecast wholesale electricity price is for the energy
market, the operating schedule for the controller may specify
optimal time intervals for use of the energy storage asset in the
regulation market. As a non-limiting example, the suggested
operating schedule may calls for a counter-intuitive action, such
as committing a portion of the energy of the energy storage asset
to the regulation market even during a time interval when the
forecast wholesale electricity price are expected to be higher than
the potential revenue from the regulation market during that time.
The optimization according to the principles described herein
evaluate the various actions and responses of the energy assets
over the entire time period Tin order to optimize the objective
cost function, e.g., to maximize the economic benefit, given
constraints on the controls or on the states. Accordingly,
implementation of a suggested operating schedule generated
according to the system, method or apparatus described herein can
result in actions that differ from more heuristic approaches.
[0137] According to an example of the principles herein, the
wholesale electricity market may include both the energy market and
the regulation market, and the operating schedule generated may
facilitate implementation of the energy storage asset in both the
energy market and the regulation market. According to a principle
of virtual partitioning described herein, the operating schedule
for the controller may be configured so that the energy customer
may participate in both the energy market and the regulation market
concurrently the energy storage asset. In a non-limiting example,
the operating schedule for the controller of the energy storage
asset may specify that, during a given time interval, a first
portion of an available state of charge (SOC) of the energy storage
asset may be used in the energy market and a second portion of the
available SOC of the energy storage asset may be committed to the
regulation market. The operating schedule generated for the
controller may be used to provide energy-related revenue for the
energy consumer based on both the energy market and the regulation
market. The principles and implementations described above in
connection to FIG. 1 are also applicable to a system operating
according to the principles of virtual partitioning.
[0138] In another non-limiting example, the apparatus of FIG. 3 can
be used for determining an operating schedule of a controller of at
least one energy asset operated by an energy customer of an
electricity supplier, so as to generate energy-related revenue,
over a time period T, associated with operation of the at least one
energy asset according to the operating schedule, wherein the
energy-related revenue available to the energy customer over the
time period T is based at least in part on a wholesale electricity
market. The wholesale electricity market may include an energy
market. The energy-related revenue may also be available from a
regulation market. The apparatus includes at least one
communication interface, at least one memory to store
processor-executable instructions and a mathematical model for the
at least one energy asset, and at least one processing unit. The
mathematical model facilitates a determination of the operating
schedule for the controller of the at least one energy asset based
at least in part on an operation characteristic of the at least one
energy asset, a forecast wholesale electricity price associated
with the energy market, and a regulation price associated with the
regulation market. The at least one processing unit is configured
to determine the operating schedule for the controller of the at
least one energy asset using the mathematical model by minimizing a
net energy-related cost over the time period T. The net-energy
related cost is based at least in part on the duration of energy
asset participation in the regulation market, electricity
generation by the at least one energy storage asset, and
electricity consumption by the at least one energy asset (including
the energy storage asset). The energy-related revenue available to
the energy customer is based at least in part on the minimized net
energy-related cost. The operating schedule specifies, during a
time interval within the time period T, a first portion of an
available output of the controller for use in the energy market and
a second portion of the available output of the controller for use
for use in the regulation market. The at least one processing unit
is also configured to control the at least one communication
interface to transmit to the energy customer the operating schedule
for the controller of the at least one energy asset and/or controls
the at least one memory so as to store the determined operating
schedule for the controller.
[0139] In this example, the available output of the controller is a
charge rate of the at least one energy storage asset or a discharge
rate of the at least one energy storage asset. The net
energy-related cost may be specified as a difference between an
electricity supply cost and an economic demand response revenue
over the time period T. The operation characteristic of the at
least one energy storage asset is a state of charge, a charge rate,
a degree of non-linearity of charge rate a discharge rate, a degree
of non-linearity of discharge rate, a round trip efficiency, or a
degree of life reduction.
[0140] Energy Asset Modeling
[0141] To facilitate the mathematical optimization process for
generating a suggested operating schedule for one or more energy
assets according to various examples of the principles herein, a
mathematical model representing an energy customer's energy
asset(s) is formulated and employed to simulate an "energy profile"
for the asset(s).
[0142] In an example, the building asset model is an
engineering-based model. Various examples and aspects of
engineering-based building asset models that are applicable to any
of the apparatus, methods, and/or computer readable media are
described herein. An example engineering-based model described
herein can be a two-node model that provides improvement in
thermodynamic and HVAC predictions with automated parameter search
and validation. The engineering-based model can generated from a
mathematical model that includes one or more terms to the physical
attributes of at least one component of the energy asset(s)
themselves as they relate to energy use and or generation,
including electricity use and/or electricity generation. An
engineering-based model described herein can be used to provide an
improvement on a physical model, including a HVAC system model
(such as a chiller model, AHU model, ice-storage model, etc.). In
an example, the engineering-based model includes one or more
equations and/or parameters that are based on physical components
and/or systems in the buildings. For example, an engineering-based
model can be developed to take into account the thermodynamics of
some components (e.g., using a thermodynamic equation for a HVAC
based on a heat capacity), the heat conduction or other energy
exchange of the building asset based on a temperature difference
between the inside and outside of the building (modeled as a
circuit element equation). A transfer function, as described, e.g.,
in Seem et al. (1989), "Transfer Functions for Efficient
Calculation of Multidimensional Transient Heat Transfer," ASME J.
Heat Transfer, Vol. 111, pp. 5-12 (which is incorporated herein by
reference in its entirety), may be used to model the heat change
behavior. An example engineering-based model described herein is
applicable to a sensed buildings (for which there is data on the
operation characteristics of its energy assets, including the
operation characteristics of one or more of its components).
[0143] Depending on the energy asset(s) operated by the energy
customer, the mathematical function(s) defining an asset model may
represent a single energy asset or an aggregation of multiple
energy assets operated by the customer. For purposes of the
discussion herein, the term "asset model," unless otherwise
qualified, is used generally to denote a model representing either
a single energy asset or an aggregation of multiple energy
assets.
[0144] To illustrate the general concept of an asset model, a model
is first considered for one or more energy assets that not only may
be turned "on" or "off," but that may be controlled at various
"operating set points." For example, consider the case of a
"building asset," e.g., one or more buildings including a heating,
ventilation and air conditioning (HVAC) system for temperature
control, for which the customer may choose different temperature
set points at different times (e.g., thermostat settings);
accordingly, in this example, the temperature set points constitute
"operating set points" of the building asset. In this example, the
magnitude of the operating set point may vary as a function of time
t, in a continuous or step-wise manner (e.g., Temp(t)=72 degrees F.
for 9 PM<t<9 AM; Temp(t)=68 degrees F. for 9 AM<t<9
PM). In other examples of energy assets that merely may be turned
"on" or "off," the magnitude of the operating set point may be
binary (i.e., on or off), but the respective on and off states may
vary as a function of time t (e.g., over a given time period
T).
[0145] Based on the notion of time-varying operating set points for
energy assets, the term "operating schedule" as used herein refers
to an operating set point of one or more energy assets as a
function of time, and is denoted by the notation SP(t):
SP(t).ident.operating schedule for one or more energy assets.
[0146] The amount of energy used (and/or generated) by a particular
asset or group of assets in a given time period T is referred to
herein as an "energy profile." In various implementations discussed
herein, the energy profile of one or more assets often depends at
least in part on a given operating schedule SP(t) for the asset(s)
during the time period T. For a fixed-load asset, the energy
profile may not depend on a given operating schedule SP(t).
Accordingly, an energy asset model specifies one or more
mathematical functions for calculating an energy profile (i.e.,
electricity use and/or electricity generation as a function of
time) for the asset(s), based on a proposed operating schedule for
the asset(s) applied as an input to the model. The one or more
functions constituting the asset model are denoted herein generally
as F (and for simplicity the term "function" when referring to F
may be used in the singular), and the model may be conceptually
represented using mathematical notation as:
F(SP(t))=EP(t), Eq. 1
where the operating schedule SP(t) is an argument of the function
F, and the energy profile of the modeled asset(s) as a function of
time is denoted as EP(t). In a non-limiting example, EP(t) has
units of MWh. FIG. 4 illustrates a simple block diagram
representing the asset model given by Eq. 1.
[0147] In various examples, the function(s) F defining a particular
asset model may be relatively simple or arbitrarily complex
functions of the argument SP(t) (e.g., the function(s) may involve
one or more constants, have multiple terms with respective
coefficients, include terms of different orders, include
differential equations, etc.) to reflect how the asset(s) consume
or generate energy in response to the operating schedule SP(t). In
general, the particular form of a given function F, and/or the
coefficients for different terms, may be based at least in part on
one or more physical attributes of the asset(s), and/or the
environment in which the asset(s) is/are operated, which may impact
the energy profile of the asset(s) pursuant to the operating
schedule. More specifically, depending on the type of energy
asset(s) being modeled, the mathematical model may be formulated to
accept other inputs (in addition to the operating schedule SP(t)),
and/or to accommodate variable parameters of a given function F
(e.g., via time-dependent coefficients of different terms of the
function), to facilitate calculation of the energy profile EP(t)
based on a proposed operating schedule SP(t).
[0148] For example, in the case of the building asset discussed
above, and/or other assets for which thermodynamic considerations
are pertinent, various internal factors that may impact the asset's
energy profile in general (e.g., building occupancy; a presence of
equipment such as computers and other instrumentation that may
affect heating or cooling in an environment; thermal inertia due to
insulation, building materials, windows; etc.) may be considered in
the formulation of the form of the function F itself, and/or
coefficients for different terms of the function F. In some
examples discussed in further detail below, such as with a
real-time building asset model, the function F may be dynamically
adjusted based on an observation/measurement of actual energy usage
over time by the asset(s) pursuant to the updating performed during
implementation of Kalman filtering. In some examples discussed in
further detail below, the function F may be dynamically adjusted
based on observing actual energy usage over time by the asset(s)
pursuant to control via a particular operating schedule (i.e.,
coefficients of function terms initially may be estimated, and
subsequently adjusted over time based on real-time feedback from
controlled assets).
[0149] Similarly, the mathematical model for the asset(s) may be
configured to consider as an input to the model actual or forecast
ambient environmental conditions (e.g., temperature, humidity,
ambient light/cloud cover, etc.) as a function of time,
collectively denoted as "weather information" W(t), which may
impact the energy profile of one or more assets. In this case, the
model may be conceptually represented as:
F(SP(t),W(t))=EP(t), Eq. 2
where both the operating schedule SP(t) and the weather information
W(t) are arguments of the function F. FIG. 5 illustrates a simple
block diagram representing the asset model given by Eq. 2. It
should be appreciated that, while weather information W(t) is noted
above as providing another possible input to the model in addition
to the operating schedule SP(t), in other examples one or more
other inputs to the model may be provided and considered as
arguments to the function F (and accordingly taken into
consideration in the function) for purposes of calculating an
energy profile EP(t) for the asset(s).
[0150] In another example herein, the mathematical model for a
system that includes a controllable asset, such as an energy
storage asset and an associated controller, or other component with
a controller (e.g., a HVAC), may be configured to consider as an
input to the model the control vector for the controller as a
function of time, denoted as u(t), which may impact the energy
profile. In this case, the model may be conceptually represented
as:
F(u(t))=EP(t), Eq. 3
where both the control vector of the controller is an argument of
the function F. FIG. 6 illustrates a simple block diagram
representing the asset model given by Eq. 3. It should be
appreciated that, while the control vector u(t) is noted above as
providing input to the model, in other examples, one or more other
inputs to the model may be provided and considered as arguments to
the function F (and accordingly taken into consideration in the
function) for purposes of calculating an energy profile EP(t) for
the asset(s). An energy storage asset herein generally refers to an
asset that can store a form of energy and release it as usable
energy (or power) over time. Non-limiting examples of energy
storage assets include batteries, ice units, compressed air,
flywheel, heated liquids, and heated solids. Non-limiting examples
of batteries include lithium ion batteries, lead-acid batteries,
flow batteries, or dry cell technology batteries.
[0151] In yet another example herein, the mathematical model for a
system that includes controllable energy assets, including energy
consuming assets such as but not limited to a building asset
including a (HVAC) system for temperature control, or an energy
storage asset and an associated controller, may be configured to
consider as an input to the model the control vector for the
controller as a function of time, denoted as u(t), and temperature
dependent operating set points for the energy consuming asset (its
operating schedule). In this case, the model may be conceptually
represented as:
F(u(t),SP(t))=EP(t), Eq. 4
where both the control vector of the controller is an argument of
the function F. FIG. 7 illustrates a simple block diagram
representing the asset model given by Eq. 4. In an example, the
control vector for a controller, u(t)=C.sub.t+D.sub.t, may be
expressed as:
D.sub.t=u.sub.1,t*C/D.sub.max
D.sub.t=u.sub.2,t*C/D.sub.max Eq. 5
with the constraints that u.sub.1,t*u.sub.2,t=0 and
0.ltoreq.u.sub.1,t, u.sub.2,t.ltoreq.1, where represents
C/D.sub.max the maximum charge rate or discharge rate capacity of
the controller in communication with the energy storage asset.
[0152] In yet another example herein, the mathematical model for a
system that includes an energy consuming asset, such as but not
limited to a building asset, and a controllable asset, such as but
not limited to an energy storage asset and an associated
controller, or other component with a controller (e.g., a HVAC),
may be configured to consider as an input to the model the control
vector for the controller as a function of time, denoted as u(t),
and temperature dependent operating set points for the energy
consuming asset (its operating schedule). FIG. 8 illustrates a
simple block diagram representing the asset model for such as
system according to the principles herein. In this case, the model
may have outputs of the state of charge (SOC.sub.t) of the energy
storage asset as a function of time t, the return-air-temperature
(RAT.sub.t) (including the zone temperature (T.sub.z)) as a
function of time t (for, e.g., a HVAC or other similar equipment),
and the energy profile as a function of time (EP.sub.t) of the
energy consuming asset (e.g., some components of the building
asset). In another example, the output is a zone temperature
(T.sub.z) as a function of time and the energy profile (EP.sub.t).
In yet another example, the output is a return-air-temperature
(RAT.sub.t), a zone temperature (T.sub.z) and an energy profile
(EP.sub.t) as functions of time. In yet other examples, the output
is a load as a function of time. Other inputs to the system can be
weather information (W(t)) and/or feedback from other energy assets
in the system (V). This model can be used, e.g., for
co-optimization of an energy storage asset and an energy consuming
asset for the energy market.
[0153] In an example according to a principle herein, once an
appropriate asset model is established for a given energy asset or
group of energy assets, different candidate operating schedules may
be applied to the model to simulate how the energy profile EP(t) of
the asset(s) is affected as a function of time, over a given time
period T, by the different operating schedules.
[0154] An example technique for facilitating determination of
optimal operating schedule for energy cost reduction and/or revenue
generation from wholesale electricity markets according to various
examples disclosed herein is as follows. In this example, the
system includes an energy consuming asset, a controller of the
energy storage asset, and a controllable energy consuming asset. A
plurality of first candidate operating schedules is selected for
the controller, and a plurality of second candidate operating
schedules is selected for the energy consuming asset. Each second
candidate operating schedule for the energy consuming asset is
different from the BAU operating schedule for the energy consuming
asset. The plurality of first and second candidate operating
schedules are successively applied to the mathematical model to
generate corresponding plurality of simulated energy profiles for
the energy storage asset and the energy consuming asset. A
plurality of projected net energy-related costs to the energy
customer are computed, where each projected net energy-related cost
is computed based at least in part on the representative CBL energy
profile and the simulated energy profiles corresponding to the
respective first and second candidate operating schedules and the
forecast wholesale electricity price. Respective ones of the first
and second candidate operating schedules corresponding to one
simulated energy profile of the plurality of simulated energy
profiles that results in a minimum net energy-related cost of the
plurality of net energy-related costs calculated are selected as an
optimal first operating schedule and an optimal second operating
schedule. That is, namely, this technique can be implemented to
simulate how energy assets consume/generate electricity based on
different candidate operating schedules for the asset(s), and to
select a particular operating schedule that facilitates a
particular economic goal of the energy customer.
[0155] In another example, the operating schedules for the energy
storage asset and energy consuming asset can be calculated in
tandem based on minimizing the net energy-related costs (NEC), as
discussed in greater detail below.
[0156] Operating Schedules and Constraints
[0157] In considering various operating schedules SP(t) that may be
applied to the asset model so as to simulate a corresponding energy
profile EP(t), in some instances SP(t) may not be varied freely.
Such limitations on candidate operating schedules may be due at
least in part to physical limitations of the asset(s) being modeled
(such as for an engineering-based energy asset model), and/or
limitations on operation of the asset(s) dictated by the energy
customer itself. For example, in some instances the customer may
want to constrain the range in which the magnitude of SP(t) may be
varied at any given time, and/or the customer may wish to designate
particular periods of time (e.g., within the given time period T of
interest) during which particular values of SP(t) cannot be changed
(or only changed in a limited manner).
[0158] For purposes of illustration, again consider a building
asset with an HVAC system. The customer may specify that, in
considering candidate operating schedules SP(t) for the building
asset, temperature set points (i.e., the magnitude of SP(t) in this
example) must remain in a range of from between 65 to 75 degrees F.
in any proposed operating schedule; furthermore, the customer may
dictate that during a certain time frame, the temperature set point
may not exceed 70 degrees F. In general, magnitude and/or timing
limitations placed on a candidate operating schedule SP(t) for one
or more modeled assets are referred to herein as "constraints" on
the operating schedule.
[0159] The concept of candidate operating schedules for one or more
modeled energy assets subject to one or more "constraints" is
denoted herein as:
SP(t)|.sub.Constraints.ident.operating schedule for one or more
energy assets subject to constraints
[0160] The "constraints" may also be set to impose limitations on
state outputs, including the resulting temperature. The
"constraints" on the state outputs may impose limitations on ranges
of values for the state outputs, such as but not limited to
limiting the temperature of the building asset to specific ranges.
For example, the constraints imposed on the control inputs may be
optimized so that the state outputs (including temperature) are
maintained within specified ranges.
[0161] In an example, the system includes an energy storage asset,
and constraint may be placed on the allowed state of charge (SOC)
of the energy storage asset. For example, the constraint may be
placed that the SOC does should not be allowed to fall below a
minimal SOC value (i.e., not too depleted) and/or that the SOC does
should not be allowed to go above a maximal SOC (i.e., not
overly-charged).
[0162] Business-As-Usual (BAU) Conditions and Customer Baseline
(CBL) Energy Profiles
[0163] Once an appropriate asset model is established for a given
energy asset or group of energy assets, a particular operating
schedule of interest in some examples is referred to herein as a
"typical" or "business-as-usual" (BAU) operating schedule (also
referred to herein as "BAU conditions"), denoted as SP(t).sub.BAU.
In particular, "BAU conditions" refer to an operating schedule that
an energy customer would typically adopt for its energy asset(s),
absent the incentive to reduce energy costs and/or earn
energy-related revenue from wholesale electricity markets. Again
turning to the example of a building asset for purposes of
illustration, absent any incentive to change its behavior, during a
summer season in which cooling is desired an energy customer may
typically set the thermostat (i.e., temperature set points) for the
building asset at 72 degrees F. from 9 PM to 9 AM, and at 68
degrees F. from 9 AM to 9 PM; this can be represented conceptually
using the notation adopted herein as:
SP ( t ) BAU = { 72 , 9 PM < t < 9 AM 68 , 9 AM < t < 9
PM } . ##EQU00001##
[0164] When a typical operating schedule SP(t).sub.BAU is applied
to the asset model, the particular energy profile generated by the
model is a special case referred to herein as a simulated "customer
baseline" (CBL) energy profile, denoted as CBL(t). Using the
example relationship given in Eq. 2 above (which includes
consideration of weather information), the special case of a CBL
energy profile may be conceptually represented mathematically
as:
F(SP(t).sub.BAU,W(t))=CBL(t), Eq. 6
where the typical operating schedule SP(t).sub.BAU is an argument
of the function F (in this example together with the weather
information W(t)), and the CBL energy profile of the modeled
asset(s) as a function of time is denoted as CBL(t).
[0165] Although consideration of weather information W(t) is
included in the example above, it should be appreciated that the
simulation of a customer baseline (CBL) energy profile in other
examples may not consider weather information (as such information
may not be relevant to the energy profile of the asset(s) in
question). It should also be appreciated that while the simulation
of a CBL energy profile may be useful for mathematical optimization
techniques employed in some examples to facilitate energy cost
reduction and/or revenue generation from particular wholesale
electricity markets (e.g., economic demand response "energy
markets"), simulation of a CBL energy profile may not be applicable
or necessary in other examples to facilitate energy cost reduction
and/or revenue generation from wholesale electricity markets.
[0166] Objective Cost Functions and Optimal Control
[0167] For purposes of the present disclosure, an "objective cost
function" specifies all energy-related costs and energy-related
revenues associated with operating one or more modeled energy
assets of an energy customer so as to achieve a particular economic
goal (an economic "objective"). In one aspect, an objective cost
function incorporates the function(s) F representing the
mathematical model for one or more energy assets, and specifies an
energy customer's "net energy-related cost" (e.g., in dollars)
associated with operating the modeled asset(s) over a given time
period T. The energy customer's net energy-related cost as given by
the objective cost function is denoted herein as NEC$:
NEC$=net energy-related cost to operate one or more energy
assets.
As discussed in greater detail below, objective cost functions
providing a net energy-related cost NEC$ according to different
examples may have a variety of respective cost and revenue terms,
based at least in part on the types of asset(s) being operated and
the particular revenue-generation objective(s) (e.g., the
particular wholesale electricity market(s) from which revenue is
being sought).
[0168] In an example, the objective cost function, control inputs
to the objective cost function, and the state outputs can be
continuous functions of time, which can form a basis for the
optimal control (as opposed to parametric optimization). A
parametric optimization may find certain solutions for the PID that
deliver an extremum solution but which is not the optimized
solution.
[0169] For example, in some examples, the energy-related costs
included in the objective cost function may include "actual"
energy-related costs (e.g., retail electricity costs, wholesale
electricity costs representing revenue earned by the energy
customer, etc.). In some examples, the energy-related costs
included in the objective cost function additionally or
alternatively may include "indirect" energy-related costs, such as
convenience/comfort costs associated with the energy customer's
adoption of a suggested operating schedule different than the BAU
operating schedule (the convenience/comfort cost represents an
"indirect" cost associated with a change in the customer's behavior
with respect to operating its asset(s), based on the incentive of
possible energy-related revenue from the wholesale electricity
markets). In an example, energy-related costs included in the
objective cost function may include reliability costs associated
with voltage/VAR control in a microgrid application. Similarly, an
objective cost function may include one or more terms specifying
energy-related revenues corresponding to one or more wholesale
electricity markets (e.g., "energy markets," "synchronized
reserve," "regulation").
[0170] To provide a preliminary illustration of concepts germane to
an objective cost function specifying a net energy-related cost
NEC$, an example relating to economic demand response revenue from
the wholesale electricity "energy markets" is first considered. To
this end, retail electricity prices (i.e., what the energy customer
pays a "utility" for electricity usage) and wholesale
electricity-related product prices available to the energy customer
respectively are denoted as:
Retail$(t)=price of electricity from a retail electricity provider
("utility"); and
Wholesale$(t)=price of electricity-related product on applicable
wholesale electricity market,
where the retail electricity price Retail$(t) and the wholesale
electricity-related product price Wholesale$(t) may vary
independently of each other as a function of time. In an example,
the units of the retail electricity price Retail$(t) and the
wholesale electricity-related product price Wholesale$(t) are
$/MWh.
[0171] The wholesale price Wholesale$(t) can be dictated by (e.g.,
based at least in part on) the "locational marginal price" (LMP) as
a function of time, as noted above (see Background section).
However, depending on a given wholesale electricity market and/or a
particular electricity-related product in question, it should be
appreciated that the wholesale price Wholesale$(t) may be based on
other and/or additional factors. Also, practically speaking,
wholesale prices are not continuous functions of time; rather, as
discussed above, wholesale prices based on the LMP may be
calculated periodically at specified nodes of the grid (e.g., every
5 minutes, every half-hour, every hour) depending on the particular
market in which the energy customer is participating. Accordingly,
it should be appreciated that Wholesale$(t) typically is a discrete
function of time, with t having some periodicity (e.g., 5 minutes,
30 minutes, 60 minutes).
[0172] Given the notation above for retail and wholesale prices,
the energy customer's modeled retail electricity costs (or "supply
costs"), for operating one or more modeled electricity-consuming
assets pursuant to a particular operating schedule SP(t) applied to
an asset model, is denoted herein as Supply$(t), given by:
Supply$(t)=EP(t)*Retail$(t), Eq. 7
wherein EP(t) is the energy profile of the modeled asset(s) (e.g.,
given by any of Eqs. 1-4 above).
[0173] For the energy storage asset, the energy customer's "supply
costs" for charging the asset can be denoted herein as
Supply$(t).sub.ES, given by:
Supply$(t).sub.ES=EP(t)*Retail$(t), Eq. 8
wherein EP(t) is the energy profile of the modeled energy storage
asset(s). Since the energy profile for an energy storage asset can
be represented based on a charge rate (C.sub.t) for a time step
(t<T) over the amount of time of charging (.DELTA.t), the supply
costs can be expressed as:
Supply$(t).sub.ES=C.sub.t*.DELTA.t*Retail$(t). Eq. 9
The charge rate (C.sub.t) may be the maximum charge rate of the
energy storage asset, or a charge rate less than the maximum charge
rate. For example, in different examples herein, the output of the
controller may modify the charge rate of the energy storage asset
to values that are less than the maximum charge rate.
[0174] If the system includes an energy storage asset and an energy
generating asset, the total supply costs can be expressed, in a
non-limiting example, as the energy storage asset
(Supply$(t).sub.ES) reduced by a cost amount based on the amount of
energy provided by the energy generating asset (EG.sub.k). In an
example, the total supply costs can be expressed as:
Supply$(t).sub.total=(C.sub.k-EG.sub.k)*.DELTA.t*Retail$(t). Eq.
10
[0175] Supply costs may also apply to the system by virtue of an
emissions cost associated with the operation of at least one of the
energy assets. That is, the net-energy related cost can include a
term based on the emissions costs (Emissions$) associated with, as
non-limiting examples, the electricity consumption by an energy
consuming asset or an emissions cost based on operation of an
energy generating asset. The emissions costs can be associated with
greenhouse gas emissions during operation of the system.
Non-limiting examples of such emissions are CO.sub.x emissions
(e.g., carbon monoxide and carbon dioxide emissions), NO.sub.x
emissions (e.g., nitrogen dioxide and related pollutant emissions),
SO.sub.x emissions (e.g., sulfur dioxide and related pollutant
emissions), particulates, and methane (CH.sub.4) and related
pollutant emissions. In an example, the contribution to the supply
costs (Supply$(t)) based on the emissions costs (Emissions$) may be
computed based on an economic benefit, such as but not limited to a
prorated amount of a penalty cost leveled due to an amount of
emissions, over a time period T, associated with the operation of
the at least one energy asset. The penalty cost may be in staged
amounts. For example, a first penalty may be imposed for an amount
of emissions above a first threshold value but below a second
threshold emissions value, and a second (higher) penalty may be
imposed for an amount of emissions above the second threshold
emissions value. Such penalties may be leveled by a government
agency (in a command-and-control program, a regulation program, or
a voluntary program) or may be determined based on participation in
a non-governmental voluntary emissions reduction program. In
another example, the contribution to the supply costs based on the
emissions costs may be computed based on a trading price of an
emissions credit based on an amount of emissions, such as but not
limited to a trading price of a carbon credit based on CO.sub.x
emission (also an economic benefit). For example, trading on
financial markets may be performed under international protocol
(such as but not limited to the Kyoto Protocol). As another
example, trading may occur under a U.S. regional emissions
reduction program, such as but not limited to the Regional
Greenhouse Gas Initiative (RGGI).
[0176] The contribution to the (Supply$(t)) based on the emissions
costs (Emissions$) may be computed based on base emissions cost for
a minimal level of operation of the energy asset(s), over time
period T, and a marginal emissions cost per megawatt with each
increase or decrease in megawatt of operation. In an example, the
marginal emissions cost can be computed based on a change in the
amount of emissions generated by an energy generating asset that is
in communication with the at least one energy asset, associated
with the increase or decrease in megawatt of operation. As a
non-limiting example, where the energy generating asset is a diesel
generator, the emissions costs can include a term representing the
amount of emissions by virtue of use of diesel fuel. In an example,
the marginal emissions cost can be computed based on a marginal
supplier emissions cost associated with a change in electricity
usage by the energy customer associated with the increase or
decrease in megawatt of operation. The marginal supplier emissions
cost can be quantified based on an amount of emissions from an
electricity generating facility of the electricity supplier per
megawatt-hour of electricity supplied. The marginal supplier
emissions cost can very based on the type of electricity generation
facility. As an example, the emissions from a coal-based
electricity generation facility can be higher than the emissions
from a hydro-power electricity generation facility or a gas-powered
electricity generation facility. In this example, the marginal
supplier emissions cost for a coal-based electricity generation
facility for each incremental increase or decrease in megawatt-hour
of electricity supplied can be higher than the marginal supplier
emissions cost for a hydro-power electricity generation facility or
the marginal supplier emissions cost for a gas-powered electricity
generation facility.
[0177] The emissions costs (Emissions$) can be computed based on a
change in the energy customer's behavior in reducing its
electricity usage based on an operation of the at least one energy
asset. For example, the emissions cost can be specified as a cost
function based at least in part on at least one difference between
the energy customer's behavior in reducing its usage of the energy
asset(s) and their BAU operating schedule. In an example, the
energy asset(s) can include at least one building having a variable
internal temperature controlled by a HVAC system, and the emissions
cost is based on a difference between a candidate temperature set
point for the HVAC system as a function of time and the BAU
temperature set point. The emissions cost can be computed as
proportional to the magnitude of deviation of the temperature of
the building from a BAU temperature set point.
[0178] Supply costs may also apply to the system by virtue of
lifetime and/or replacement costs for electricity generation and/or
energy storage assets, such as but not limited to due to the
reduction in life of the energy storage asset. An energy storage
asset may have a limited life depending on its rating of expected
charge/discharge cycles. A portion of the costs associated with
ultimately replacing an energy storage asset at the end of its
lifetime may be included in the supply costs based on the number of
charge/discharge cycles it is expected to undergo when implemented
in an energy market and/or a regulation market as described herein.
The lifetime reduction supply costs may also depend on the number
of kWh is used in each charge or discharge cycle, and/or for what
length of time the energy storage asset is used in a market
(energy, regulation, etc.). For example, the contribution to the
supply costs based on the replacement cost (Replacement$) may be
computed according to the expression:
Supply$(t).sub.LIFE=Replacement$/n Eq. 11
where n represents an effective number of charge/discharge cycles.
The effective number of charge/discharge cycles can depend on the
number of cycles the asset is expected to undergo when implemented
in an energy market and/or a regulation market, the number of kWh
is used in each charge or discharge cycle, and/or for what length
of time the energy storage asset is used in a given market. This
lifetime supply cost would be additive to any of the expressions
for supply costs described herein for a system that includes an
energy storage asset.
[0179] Non-limiting examples of other energy-related costs
applicable to the systems, methods and apparatus described herein
include fuel costs to run one or more electricity generation
assets, operation and/or maintenance costs that may be associated
with electricity generation and/or energy storage assets, tariffs
that can be leveled in the industry, demand charges that can be
leveled at times of peak energy usage, etc.
[0180] With respect to economic demand response revenue from the
wholesale electricity energy markets, in the present example it is
presumed that the energy customer is amenable to operating its
energy asset(s) pursuant to a candidate operating schedule that is
different than its "typical operating schedule" or BAU conditions
(i.e., SP(t).sub.BAU), such that the energy profile EP(t) of the
asset(s) will be on average lower than the customer baseline CBL(t)
(see Eq. 6 and related description above). Altering the energy
profile of the asset(s) with respect to the customer baseline,
pursuant to a change in behavior represented by a candidate
operating schedule different than BAU conditions, provides the
source of opportunity for generating economic demand response
revenue from the wholesale electricity energy markets. Accordingly,
a wholesale electricity energy market "demand response revenue,"
denoted herein as DR$(t).sub.EM, is given generally by:
DR$(t).sub.EM=max{0,[(CBL(t)-EP(t))*Wholesale$(t)]}. Eq. 12
[0181] In an example, the DR$(t) represents the net difference
between actual net metered load and the BAU load. The participation
of any component of the energy asset in the energy market,
regulation market or spinning reserve market is included in the
computation of DR$(t) to the extent they affect the value of the
metered load. In addition, the energy generated by any energy
generating asset that is part of the energy asset may also be
included in the computation of DR$(t) to the extent this
behind-the-meter generated energy affects the value of the metered
load.
[0182] For an energy storage asset in an energy market, a demand
response revenue may be denoted herein as DR$(t).sub.ES, is given
generally by:
DR$(t).sub.ES=(0-(-(D.sub.t))*.DELTA.t*Wholesale$(t). Eq. 13
[0183] As described herein, a system that includes an energy
storage asset can participate in both an energy market (at a price
of Wholesale$(t)) and in a regulation market (at a price of
regulation$(t)). In this example, the demand response revenue may
be computed herein as DR$(t).sub.ES, denoted by:
DR$(t).sub.ES=(.epsilon.D.sub.t)*.DELTA.t*Wholesale$(t)+(.gamma.D.sub.t)-
*.DELTA.t*regulation$(t) Eq. 14
where D.sub.t denotes the discharge rate of the energy storage
asset at a time step. Where the system participates in the energy
market and the regulation market at different points in time during
overall time period T, both multipliers of the discharge rate,
.epsilon. and .gamma., may be equal to 1. In different examples
herein, the output of the controller may modify the discharge rate
of the energy storage asset to values that are less than the
maximum discharge rate. Using the principles of virtual
partitioning described herein, by apportioning an output of the
controller in communication with the energy storage asset, a
portion of the discharge rate may be directed to the regulation
market and another portion directed to the energy market during a
given time step. As a non-limiting example, the operating schedule
determined as described herein may cause the controller to
discharge the energy storage asset at a discharge rate of
.epsilon.D.sub.t to the energy market, while concurrently respond
to the regulation market at a discharge rate of .gamma.D.sub.t
along shorter timescales (such as but not limited to at 2-second
intervals or minute-by-minute time intervals). Here, the constraint
on the values may be .epsilon.+.gamma..ltoreq.1 if D.sub.t
represents the maximum discharge rate of the energy storage
asset.
[0184] In a non-limiting example, where the regulation price is not
based on the discharge rate, but rather depends only on the time
period of commitment of the energy storage asset to the regulation
market, the demand response revenue may be computed as:
DR$(t).sub.ES=(.epsilon.D.sub.t)*.DELTA.t*Wholesale$(t)+regulation$(t)*.-
DELTA.t Eq. 15
[0185] In another example, the demand response revenue for a system
that includes an energy storage asset and an energy generating
asset participating in an energy market may be computed as:
DR$(t).sub.ES+EG=(D.sub.t))*.DELTA.t*Wholesale$(t)+(E.sub.EG)*Wholesale$-
(t) Eq. 16
where D.sub.t denotes the discharge rate of the energy storage
asset at a time step and E.sub.EG denotes the energy provided by
the energy generating asset.
[0186] According to the principles described herein, a demand
response revenue may also be generated for a system that includes
an energy storage asset and an energy generating asset
participating in both an energy market and a regulation market.
[0187] Based on the equations for supply costs and demand response
above, an example of an objective cost function to provide a net
energy-related cost NEC$ over a given time period T for operating
the modeled asset(s), considering both retail electricity supply
costs and demand response revenue can be computed based on the
expression:
NEC$ = t T ( Supply$ ( t ) - DR$ ( t ) ) . Eq . 17 ##EQU00002##
[0188] In one example, an objective cost function as exemplified by
Eq. 17 may be provided to an optimizer (a particularly-programmed
processor, also referred to as a "solver"; such as processor unit
13 of FIG. 2) that implements a mathematical optimization process
to determine a suggested operating schedule for the energy asset(s)
over the time period T that minimizes the net energy-related cost
NEC$. Accordingly, the optimizer solves for:
Min [ t T ( Supply $ ( t ) - DR $ ( t ) ) ] Eq . 18
##EQU00003##
[0189] By substituting the pertinent equations for supply costs and
demand response (which depends on the modeling of the energy assets
in a given system) back into Eq. 18, the various informational
inputs provided to the optimizer may be readily ascertained.
Various examples and aspects of engineering-based building asset
models are described herein that are applicable to any of the
apparatus, methods, and/or computer readable media described herein
for solving an objective cost function using the optimizer.
[0190] As a non-limiting example, for a system that is
participating in the energy market, the various informational
inputs provided to the optimizer may be readily ascertained as
follows:
Min [ t T { ( EP ( t ) * Retail $ ( t ) ) - ( max { 0 , [ ( CBL ( t
) - EP ( t ) ) * Wholesale $ ( t ) ] } ) } ] , Eq . 19
##EQU00004##
where from Eq. 2
EP(t)=F(SP(t)|.sub.constraints,W(t)),
and from Eq. 6
CBL(t)=F(SP(t).sub.BAUW(t)),
where again it is presumed for purposes of illustration that
weather information W(t) is relevant in the present example. From
the foregoing, it may be seen that one or more of the following
inputs may be provided to the optimizer in various examples: [0191]
F--one or more functions defining the mathematical model for the
energy asset(s); [0192] SP(t).sub.BAU--BAU or "typical" operating
schedule for the energy asset(s); [0193] Constraints--any timing
and/or magnitude constraints placed on candidate operating
schedules for the energy asset(s); [0194] W(t)--weather information
as a function of time (if appropriate given the type of energy
asset(s) being operated); [0195] u(t)--control vector for the
controller in communication with the energy storage asset; [0196]
Retail$(t)--retail price of electricity as a function of time;
[0197] Wholesale$(t)--wholesale price of electricity-related
product as a function of time; [0198] Regulation$(t)--regulation
price in regulation market as a function of time; and [0199] NEC$
--the objective cost function describing the energy customer's net
energy-related cost associated with operating the modeled energy
asset(s). Based on the foregoing inputs, the optimizer solves Eq.
19 by finding an "optimal" operating schedule for the energy
asset(s), denoted herein as SP(t).sub.opt, that minimizes the net
energy-related cost NEC$ to the energy customer:
[0199] SP(t).sub.opt.ident."optimal" or suggested operating
schedule for one or more energy assets
[0200] In various implementations described herein, the optimizer
may receive one or more inputs, including but not limited to, the
weather information W(t), the retail electricity price Retail$(t),
and the wholesale price of the electricity-related product
Wholesale$(t) (and the regulation price (regulation$(t))) as
forecasted values provided from a third-party source, for the time
period T over which the optimization is being performed.
[0201] While a given optimizer in a particular implementation may
employ various proprietary techniques to solve for the minimization
of an objective cost function according to various examples of the
principles herein, conceptually the optimization process may be
generally understood as follows. In various implementations
discussed herein, the optimizer generates the operating schedule
using the model of the system through an optimal control procedure.
In the various example implementations, the optimizer determines an
optimal operating schedule over the defined time period (T) by
optimizing an objective cost function. For example, the optimizer
can be implemented to determine the operating schedule that
generates the energy-related revenue by minimizing a function
representing the net energy-related costs of the system over the
time period (T). The net energy-related costs can be computed based
on the supply costs and the demand response revenue as described
herein, including in Eqts. 1-19 above. The optimizer optimizes the
objective cost function over the entire defined time period (T) to
generate the operating schedule. The generated operating schedule
can include suggestions, for different specific time intervals
within the overall time period T, for when the controller can be
used to implement the energy storage asset in the energy market, in
the regulation market, or in both the energy market and regulation
market (through dynamic partitioning).
[0202] In a non-limiting example of an implementation of the
optimizer, some number N of candidate operating schedules
SP(t)|.sub.Constraints for the modeled asset(s) (together with
weather information W(t), if appropriate based on a given objective
function) can be successively applied to the asset model given by
the function(s) F to generate simulated energy profiles EP(t)
corresponding to the candidate operating schedules (see Eqs. 1-4).
A net energy-related cost NEC$ given by the objective cost function
is calculated for each such simulated energy profile EP(t) (see Eq.
17), and the candidate operating schedule that minimizes the
objective cost function (i.e., the "optimal" operating schedule
SP(t).sub.opt that minimizes the net energy-related cost NEC$) is
selected as the suggested operating schedule to be provided to the
energy customer.
[0203] As noted earlier, the example above in connection with the
objective cost function of Eq. 17 is based on actual energy-related
costs (e.g., retail electricity cost) Supply$(t). In other
examples, the energy-related costs included in a given objective
cost function additionally or alternatively may include "indirect"
energy-related costs, such as "convenience/comfort" costs
associated with the energy customer's adoption of a suggested
operating schedule SP(t).sub.opt different than its typical
operating schedule SP(t).sub.BAU. In one aspect of such examples, a
convenience/comfort cost represents an "indirect" cost in that it
does not necessarily relate to actual energy-related expenditures,
but rather attributes some cost (e.g., in dollars) relating to a
change in the customer's behavior with respect to operating its
asset(s), based on the incentive of possible energy-related revenue
from the wholesale electricity markets.
[0204] Accordingly, in some examples, an alternative objective cost
function similar to that shown in Eq. 17 may be given as:
NEC $ = t T ( Comfort $ ( t ) + Supply $ ( t ) - DR $ ( t ) ) , Eq
. 20 ##EQU00005##
where Comfort$(t) represents a convenience/comfort cost associated
with a change in the energy customer's behavior with respect to
operating its asset(s). In an example where the energy-related
costs included in the objective cost function include reliability
costs, they would be included in the computation (such as in Eq.
12) similarly to the Comfort$(t).
[0205] A convenience/comfort cost Comfort$(t) may be defined in any
of a variety of manners according to different examples. For
example, in one implementation, a convenience/comfort cost may be
based at least in part on a difference (e.g., a "mathematical
distance") between a given candidate operating schedule and the
typical operating schedule (BAU conditions) for the modeled
asset(s)--e.g., the greater the difference between the candidate
operating schedule and the typical operating schedule, the higher
the convenience/comfort cost (there may be more
inconvenience/discomfort attributed to adopting a "larger" change
in behavior). This may be conceptually represented by:
Comfort$(t)=G[|SP(t)|.sub.Constraints-SP(t).sub.BAU|], Eq. 21
where G specifies some function of the absolute value of the
"difference" between a candidate operating schedule (e.g., in a
given iteration of the optimization implemented by the optimizer)
and the typical operating schedule.
[0206] To provide an example of how Eqs. 20 and 21 may be employed
in an optimization process to determine a suggested operating
schedule SP(t).sub.opt for an energy customer according to one
example, again consider a building asset operated by the energy
customer, for which a given operating schedule SP(t) is constituted
by a temperature set point as a function of time. If T(t).sub.BAU
represents the temperature set points constituting a typical
operating schedule, and T(t)|.sub.Constraints represents different
temperature set points constituting a candidate operating schedule
that may be adopted to facilitate energy-cost reduction and/or
revenue generation, the convenience/comfort cost Comfort$(t) in
this example may be defined as a "temperature set point deviation"
T.sub.dev(t), according to:
Comfort$(t).ident.T.sub.dev(t)=A(|T(t)|.sub.Constraints-T(t).sub.BAU|),
Eq. 22
where A is a constant that converts temperature units to cost units
(e.g., degrees F. to dollars). In an example, A may be adjustable
for each individual time step, so A may be represented as a vector.
Eq. 22 specifies that there is a greater "indirect" cost associated
with candidate operating schedules having temperature set points
that deviate more significantly from the typical temperature set
points (albeit within the constraints provided by the energy
customer). In this manner, as part of the optimization process,
potential revenue from the wholesale electricity markets may be
"tempered" to some extent by a perceived cost, included in the
objective cost function (see Eq. 20), that is associated with the
inconvenience/discomfort of deviating significantly from the
typical operating schedule.
[0207] In the example above, although the multiplier A in Eq. 22 is
discussed as a conversion constant, it should be appreciated that
in other examples A may be an arbitrary function having as an
argument the absolute value of the difference between a candidate
operating schedule and the typical operating schedule as a function
of time. More generally, it should be appreciated that a
convenience/comfort cost Comfort$(t) is not limited to the
"temperature-related" example provided above in connection with a
building asset, and that other formulations of a
convenience/comfort cost as part of an objective function are
possible according to various examples of the principles
herein.
[0208] In yet other examples of objective cost functions, different
cost and revenue terms of a given objective cost function may
include corresponding "weighting factors" (e.g., specified by the
energy customer), so as to ascribe a relative importance to the
energy customer of the respective terms of the objective cost
function in arriving at a suggested operating schedule
SP(t).sub.opt. For example, in some instances, an energy customer
may want to emphasize the importance of increasing prospective
demand response revenue DR$(t) vis a vis decreasing supply costs
Supply$(t) in solving the optimization problem to arrive at a
suggested operating schedule; similarly, in other instances, an
energy customer may want to emphasize convenience/comfort costs
Comfort$(t) vis a vis increasing prospective demand response
revenue DR$(t) in solving the optimization problem to arrive at a
suggested operating schedule. The ability of an energy customer to
tailor a given objective cost function according to weighting
factors for respective terms of the objective cost function
provides an "elasticity" to the optimization process. Using the
objective cost function given in Eq. 20 above as an example, in one
example such weighting factors may be included in the specification
of an objective cost function as respective term multipliers:
NEC $ = t T [ ( .alpha. * Comfort $ ( t ) ) + ( .beta. * Supply $ (
t ) ) - ( .gamma. * DR $ ( t ) ) ] , Eq . 23 ##EQU00006##
where .alpha., .beta., and .gamma. constitute the weighting
factors. In an example, .alpha.+.beta.+.gamma.=1. In another
example, .alpha.+.beta.+.gamma.=1.
[0209] In another example, the value of a weighting factor may
differ at various points during the day. For example, if it is
preferred that the Comfort$(t) takes a bigger part in the objective
cost function computation at certain points during the day, the
factor .alpha. may be increased relative to the other weighting
factors.
[0210] In an example, the comfort cost is attributed to a change in
the energy customer's behavior in adopting the operating schedule,
over the time period T, for the at least one energy asset in lieu
of the BAU operating schedule. The comfort cost can be specified as
a cost function based at least in part on at least one difference
between the operating schedule and the BAU operating schedule. For
example, the comfort cost can be based at least in part on a
difference between the candidate temperature set point and the BAU
temperature set point. In an example where the energy asset is a
building, the change in the energy customer's behavior can be
monitored based on a difference in a return-air-temperature of a
section of the building as compared to a return-air-temperature
with the BAU operating schedule. In an example, the comfort cost
can be computed as proportional to a magnitude of deviation a
temperature of the building from a BAU temperature set point. In
another example, the comfort cost can be computed as proportional
to a magnitude of deviation a humidity of the building from a BAU
humidity set point.
[0211] In an example implementation, the operating schedule can be
generated through applying an optimization using a net-energy
related cost function based only on the energy market. The result
of the optimization can be used to provide recommendation for time
intervals for the energy customer to participate in the energy
market, regulation market, or both the energy market and the
regulation market. For example, based on the results of the
optimization, the operating schedule may determine that any excess
charge/discharge capacity of the controller of the energy storage
system may be committed to the regulation market on an hour-by-hour
basis. For example, it can be determined that the any excess
charge/discharge capacity of the controller may be committed to the
regulation market during the first 15 time intervals. The
optimization may make such a determination depending on whether the
forecast regulation price in the regulation market in this time
interval offers opportunity for energy-related revenue during this
time interval or if considered in the context of the global
optimization over time period T. In an example, such a
determination may be made depending on whether the SOC of the
energy storage asset is feasible for its use in the regulation
market. For example, it may be preferable for the energy storage
asset to be near around a 50% SOC for it to be applicable to the
regulation market. In addition, if it is decided to commit the
energy storage asset to the regulation market for a time interval,
e.g., for one or more 1-hour time intervals, the optimization
described herein may be re-performed based on the new input state
of the system. Such new inputs can include the state of charge of
the energy storage asset after its commitment to the regulation
market ends. In another non-limiting example, the optimization may
evaluate different SOC initial inputs to assess whether "recovery"
from the regulation market is feasible for later participation in
the energy market.
[0212] In an example, a predetermined threshold value of wholesale
electricity price can be set at which it is decided that the excess
charge/discharge capacity of the controller will be committed to
the regulation market. Based on the results of the optimization, a
predetermined threshold value of the LMP price, indicated by the
dashed horizontal line, may be set. In addition, it may be
determined that the first time interval of charging the energy
storage asset occurs during the time period that T coincides with
the time interval during which the forecast wholesale electricity
price falls below the predetermined threshold value. It may also be
determined in the operating schedule that a second time interval of
discharging the energy storage asset occurs coincides with a time
interval during which the forecast wholesale electricity price
exceed the predetermined threshold value.
[0213] While the discussion above of example objective cost
functions and optimization of same to generate suggested operating
schedules for energy assets has been based at least in part on
economic demand response revenue from wholesale electricity energy
markets (and in some particular examples involving building
assets), it should be appreciated that the disclosure is not
limited in this respect; namely, according to other examples,
objective cost functions may be formulated and optimized to achieve
a wide variety of energy-related objectives associated with
different types of energy assets and revenue generation
opportunities from wholesale electricity markets. For example,
computation based on revenue from the regulation market has also
been described herein above, and optimization based on the
wholesale price and the regulation price are described herein
below. In other examples, the principles herein can be applied to
other markets, such as the spinning reserve market.
[0214] Generating an Operating Schedule for Deriving Energy-Related
Revenue
[0215] As discussed above, the output of an optimization process to
minimize an energy customer's net energy-related cost NEC$ (e.g.,
as specified by an objective cost function) is typically provided
as a suggested operating schedule SP(t).sub.opt for one or more
energy assets. Generally speaking, the suggested operating schedule
SP(t).sub.opt may comprise one or more set point values as a
function of time that take into consideration all of the energy
customer's modeled and controllable energy assets.
[0216] For example, in some instances involving multiple
individually modeled and controllable energy assets, the suggested
operating schedule SP(t).sub.opt may comprise multiple time-varying
control signals respectively provided to corresponding controllers
for the different energy assets. In other cases, the energy
customer may have an energy management system (EMS) (or where
applicable, building management system (BMS), or a building
automation system (BAS)) that oversees control of multiple energy
assets, and the suggested operating schedule SP(t).sub.opt may
comprise a single control signal provided to the energy customer's
EMS, which EMS in turn processes/interprets the single control
signal representing the suggested operating schedule SP(t).sub.opt
to control respective energy assets. In an example, the EMS has
predefined "demand levels" that control the power consumption of
various assets, including modifying the setpoint for the building
zone air temperature, modifying lighting levels, and modifying
variable frequency and/or variable speed of components (such as but
not limited to modifying the frequency and/or speed of a motor, a
fan, any other ventilation equipment, and/or a pump). In an
example, modifying the setpoint for the building zone air
temperature results in relaxing zone temperature setpoint. In an
example, modifying lighting levels limits lighting levels to
certain predesignated settings. In an example, modifying variable
frequency and/or variable speed limits the variable frequency
and/or variable speed to certain predesignated settings.
[0217] In examples in which the energy customer normally operates
its energy asset(s) according to a typical operating schedule
SP(t).sub.BAU (absent any economic incentive to change its
energy-related behavior), the suggested operating schedule
SP(t).sub.opt may be conveyed to the energy customer in the form of
one or more "bias signals," denoted herein by Bias(t). In
particular, one or more bias signals Bias(t) may represent a
difference between the suggested operating schedule and the typical
operating schedule as a function of time, according to:
Bias(t)=SP(t).sub.opt-SP(t).sub.BAU. Eq. 24
[0218] Eq. 24 applies in certain cases. In a more general case, the
Bias offsets the "demand level" over components of the energy
asset. The bias signal (sent to a EMS) may cause controllers not
only to act on individual zone setpoints, but also may take other
actions such as but not limited to load sheddings (including
shutting off non-essential loads) changing lighting levels
(including dimming lights), and modifying the variable frequency
and/or variable speed of certain components (including motors, fans
or other types of ventilation equipment, and pumps). Reducing the
variable frequency and/or variable speed of certain components may
be implemented to reduce load.
[0219] In an example, in response to the signal sent to the EMS,
the EMS may make changes to operation settings of components of the
energy asset (i.e., modulate the operation parameters of
components). Non-limiting examples include adjusting zone
setpoints, dimming lights, shedding non essential loads, reducing
frequency and/or speed of variable components (including any
motors, any fans, any other ventilation equipment, or any
pumps).
[0220] Engineering-Based Models for Modeling Energy Assets
[0221] According to the principles herein, the engineering-based
modeling approach can be used to facilitate modeling of energy
assets. In an example, one or more buildings can be modeled as
energy asset.
[0222] Engineering-based models are described that can be
implemented to provide a dynamic simulation model of an energy
asset that is adaptive to physical changes in the energy asset.
[0223] For example, an engineering-based model according to the
principles described herein can be developed as a physical building
model with various numbers of input model parameters. A physical
building model can be implemented to output at least one of a BAU
customer load profile and a temperature profile. The results of the
dynamic simulation based on the engineering-based model can be
introduced to an optimization that is run to determine an optimal
suggested operating schedule for the energy assets being modeled,
including the and controllable energy asset resources of the
system.
[0224] Non-limiting example attributes of an engineering-based
model according to the principles described herein are as
follows.
[0225] In an example, a physical building model can be
computationally intensive, and can be time-consuming as a result:
Input to the physical building model may require review of
mechanical and architectural drawings of the building, including
as-built construction drawings and detailed site surveys to
calculate parameters such as area and mass. A physical model may
require manual tuning of area and mass when parameters in the
estimation. Parameters such as the number of people (building
occupancy) and equipment also may require manual tuning A fixed
load approximation may be required. The model may require model
validation for curve fitting to actual metered load. Some physical
models also may require multiple input data monitoring.
[0226] In an example, the robustness of the physical building model
may affect accuracy: The inertia of the thermodynamics (a time lag
in response) should be unaccounted for. The physical model may be a
single node model. The physical model is configured such that the
zone temperature (T.sub.z) setpoint is achieved and maintained.
FIG. 9 describes attributes of non-limiting example implementations
of a day-ahead engineering-based model, a real-time
engineering-based model, and a day-after engineering-based
model.
[0227] In an example, the physical building model according to the
principles described herein may be applicable to a building
portfolio that includes sensed buildings, i.e., buildings with some
amount of data available from monitoring of building performance
and/or buildings for which some amount of data can be inferred
(i.e., estimated or projected). While a physical building model may
perform well, an engineering-based building modeling may provide
enhanced, faster performance.
[0228] An example engineering-based model (EBM) can be used to
increase the speed of implementation with accuracy within or better
than industry standards. The EBM model can be a single-node model
or a two-node model. In an example, the EBM models may bring
together the effects of thermodynamic properties of the building
energy assets (including radiation, conduction, convection and
inertia) with the operation characteristics of controllable energy
assets, such as but not limited to the mechanical or HVAC systems.
In an example, goals of the EBM are improvement in thermodynamic
and HVAC predictions with automated model parameter search and
validation. This EBM model may also provide an improvement on an
HVAC system model (chiller model, AHU model, ice-storage model,
etc.). The EBM can be used for all building types, including sensed
buildings.
[0229] The EBM model according to the principles herein can be a
data-driven representation of the dynamics and operation of a
building asset.
[0230] The non-limiting examples of EBM models and implementation
are described in FIG. 9. The day-ahead EBM model for a system can
be based on a semi-non linear regression and at least one other
model term that is a physical model of the thermodynamic property
of the at least one energy asset and/or a physical model of an
operation characteristics of one or more controllable energy assets
of the system. The day-ahead EBM can be trained using past building
performance data. A real-time EBM model can be based on a KF update
to a linear regression and at least one model term that is a
physical model of the thermodynamic property of the at least one
energy asset and/or a physical model of an operation
characteristics of one or more controllable energy assets of the
system. Real-time feedback can be used to update model
parameter(s), such as but not limited to using Kalman Filtering.
The day-after EBM model can be based on a highly non linear
regression and at least one term that is a physical model of the
thermodynamic property of the at least one energy asset and/or a
physical model of an operation characteristics of one or more
controllable energy assets of the system. The day-after EBM model
can be fit to previous performance data when gathered when the
energy assets were operated according to the suggested operating
schedule.
[0231] Engineering-based models are described herein that can be
implemented to provide day-ahead energy asset models, the real-time
energy asset models, or day-after energy asset models. The
day-ahead energy asset models can be used to generate a suggested
operating schedule, prior to a time period T, that can be used to
operate the at least one energy asset to facilitate generation of
the energy-related revenue. The real-time energy asset models can
be used to generate updated operating schedules during operation of
the energy asset according to the suggested operating schedule
during time period T. The day-after model can be used to model the
operation characteristics of the energy asset after time period
T.
[0232] Terms of the Engineering-Based Models
[0233] In a non-limiting example, the dynamic simulation model of
the at least one energy asset according to the principles described
herein includes at least one term that is a physical model of a
thermodynamic property of the at least one energy asset. For
example, the energy asset is a building asset, and the term is
derived by solving a steady-state equation to provide a heat
balance equation at each node in the system.
[0234] FIG. 10 shows a building asset that is modeled based on a
lumped elements thermodynamic approximation. Each of the four nodes
(21-a, 21-b, 21-c, 21-d) in the approximation models the heat
balance at a section of the building asset. For example, nodes 21-a
and 21-c may relate to an inside wall and an outside wall,
respectively, of the building asset. Nodes 21-b and 21-d may relate
to the floor and ceiling of the building asset, respectively. The
R.sub.i terms and respective circuit elements approximate a thermal
resistivity at the portion of the building asset. The C.sub.i terms
and respective circuit elements approximate a heat capacity at the
portion of the building asset. The Q.sub.i terms indicate heat
flow.
[0235] The state-space equation in Eq. 25 is solved to model the
zone temperature (Tz) for the optimization.
x .tau. = Ax + Bu y = c T x + d T u Eq . 25 ##EQU00007##
Solving the state-space equation requires solving over a four-term
state (x) and nine inputs (u). As a non-limiting example, a
transfer function could be developed to solve the state-space
equation.
[0236] FIGS. 11A-11E show the effective element approximation at
each individual node (21-a to 21-d). Each node is centered at the
wall, floor, ceiling, or other similar boundary structure of the
building asset. The requirement for continuity of the heat balance
at the center point (shown in FIG. 11C) serves as a constraint on
the value of the coefficients of the circuit element approximation.
Specifically, the continuity at the mid-point (in FIG. 11C)
required for heat balance imposes constraints on the relationship
and values of the effective elements of the approximation. Based on
the state-space function coefficient, and the constraints on the
effective elements in FIGS. 11A-11E, the coefficients A, B, C and D
of Eq. 25 can be determined using matrices derived by solving the
heat balance equations at each node or state. FIGS. 12A and 12B
show a non-limiting example of the matrix forms of A, B, C, D based
on the R's and C's of the effective elements approximation, which
can be used to solver for the R's and C's using the historical
data.
[0237] An initial stage in the computation is to perform a
parameter search. The parameter search determines the number and
type of parameters to be used in the computation to reach an error
value below a desired value. The heat balance equation is solved to
provide a solution for the zone temperature. To solve the heat
balance equation, Eq. 26 is solved for heat capacity C.sub.z over
the effective element approximation at each individual node:
Cz T z t = Q sh ( t ) - Q clgHVAC ( t ) Eq . 26 ##EQU00008##
The R's and C's elements of the effective elements model are solved
using the historical data, i.e., data representative of the
operation characteristics and the thermodynamic properties of the
energy assets. For example, the R's and C's can be solved based on
historical data when heat balance is achieved, i.e., when the state
space equation heat gain load (Qsh) equals the cooling heat term
(Qclg) (Qsh=Qclg). As a non-limiting example, an algorithm to
determine the R's and the C's of the thermodynamic properties model
(such as but not limited to a genetic algorithm (GA)) can be
performed to identify the parameters sufficient for computing a
solution with a desired error in measurement.
[0238] As a non-limiting example, the R's and C's can be solved
using a transfer function, such as but not limited to the transfer
function developed by Seem et al., but modified to be applicable to
the systems described herein (where n=4). As a non-limiting
example, the transfer function can be determined based on Eq.
27:
Q w , k = j = 0 2 S w , j u w , k - j - j = 1 2 e w , j Q w , k - j
Eq . 27 ##EQU00009##
[0239] A solution can be found for C.sub.z when the cooling system
is set to "off" (i.e., Qclg=0). In the computation to perform the
optimization, T.sub.z can be constrained when solving for optimal
Qsh for load reduction. Tz bounded between a maximum and minimum
value (T.sub.z,min and T.sub.z,max) to serve as constraint points
in the simulation.
[0240] In an example, a relationship between the zone temperature
(Tz) and the set point temperature (Tspt) can be quantified in the
optimization. For example, the zone temperature (Tz) can be
quantified based on an average temperature (T.sub.average), a value
of temperature in a setting vs. (T.sub.instantaneous), or
represented by a controller function. When a change is made to a
temperature set point, the system may not necessarily reach the
value set. Therefore, the zone temperature (Tz) can differ from the
set point temperature (Tspt). According to a system, method and
apparatus herein, the differences between the zone temperature (Tz)
and the set point temperature (Tspt) can be quantified by computing
a conversion standard between Tz and Tspt, or by determining T as
function of a controller setting.
[0241] In an example, the dynamic simulation model of the at least
one energy asset according to the principles described herein
includes a total load as a function of time. According to the
principles herein, the forecast total load is computed as a
combination of a load term dependent on an environmental condition
(a weather dependent term) and a load term that is independent of
an environmental condition (a weather independent term).
[0242] In an example implementation, the weather independent (WI)
load forecast is modeled based on a time series, such as a schedule
dependent function. The weather independent (WI) load can be
modeled using a Fourier series, a frequency dependent relationship.
In a first instance, the weather independent load can include terms
to represent the weekends and holidays WI load equation, such as
modeled by Eq. 28:
P WI weekends = a 0 + h = 1 h ( a h cos ( nx ) + b h sin ( nx ) Eq
. 28 ##EQU00010##
where x=time and where h=number of hours/2-1. In a second instance,
the weather independent load can also include terms to represent
the weekday WI load equation, such as modeled by Eq. 29:
P WI weekends = a 0 + h = 1 h ( a h cos ( nx ) + b h sin ( nx ) + d
= 1 d ( c d cos ( my ) + b d sin ( my ) Eq . 29 ##EQU00011##
where x=time, y=day type, and h=number of hours/2-1.
[0243] In an example implementation, the weather dependent (Wd)
load forecast is modeled based on a Montgomery equations (Eq.
30):
P plant = a 0 + a 1 N chillers , active + a 2 i = 1 Nchillers ,
active Q chill , i + a 3 ( i = 1 Nchillers , active Q chill , i ) 2
+ a 4 i = 1 Nchillers , active T amb , wb , i + a 5 ( i = 1
Nchillers , active T amb , wb , i ) 2 + a 6 i = 1 Nchillers ,
active T CHWS , i + a 7 ( i = 1 Nchillers , active T CHWS , i ) 2 +
a 8 i = 1 Nchillers , active Q chill , j i = 1 Nchillers , active T
amb , wb , i + a 9 i = 1 Nchillers , active Q chill , i i = 1
Nchillers , active T CHWS , i + a 10 i = 1 Nchillers , active T amb
, wb , i i = 1 Nchillers , active T CHWS , i P ahu , pair = a 0 + a
1 v . mup , pair + a 2 v . mup , pair 2 P ahu , total = N ahu ,
pairs P ahu , pair Eq . 30 ##EQU00012##
The Montgomery equations can be trained based on historical data
representative of operation characteristics of energy assets, to
determine coefficients of model that model the energy assets. As
non-limiting examples, the data can be historical electric meter
data representative of the operation of controllable energy assets
such as the chillers or air-handlers electric meter. For example,
data can be collected as the chiller cools water and/or the air
handler uses the cooled water from the chillers to cool the
building asset. If such data is not available and/or costly, data
loggers can be used to record quality data at chillers and
air-handler.
[0244] According to an example of apparatus, systems and methods
described herein, the term in Qchill in the Montgomery equations is
replaced by a term in "u/k", where u is the bias temperature
setpoint shift, in units of .degree. F., and k is a constant
determined by regression (see Eq. 31).
P chiller i = a 0 + a 1 .times. N chillers + a 2 n = 1 N chillers (
u i k i ) n + a 3 n = 1 N chillers ( u i k i ) n 2 + a 4 i = n N
chillers WBT i n + a 5 n = 1 N chillers ( WBT i ) n 2 + a 6 n = 1 N
chillers ( u i k i ) n n = 1 N chillers WBT i n ##EQU00013##
Where WBTi=ambient wet-bulb temperature or ambient enthalpy, ui is
the control point (bias shift in .degree. F.). and k.sub.i is a
constant derived from regression analysis. For example, the
constant "k" in the term "u/k" can be determined based on a
regression using the training (historical) data.
[0245] In an example implementation, the term in T.sub.amb,wb can
be replaced by a term in enthalpy in the P.sub.plant equation,
where applicable. According to another example implementation, the
temperature bias can be to the term in the P.sub.ahu,total
equations.
P AHU i = a 0 + a 1 .times. u i k i + a 2 .times. ( u i k i ) 2 + a
3 .times. Q clgHVAC i + a 4 .times. Q clgHVAC i 2 + a 5 .times. u i
k i .times. Q clgHVAC i Eq . 32 P WeatherDependent i = P chillers i
+ n = 1 N AHUs P AHU i Eq . 33 ##EQU00014##
[0246] In Eqs. 31 and 32, Q.sub.clg,HVAC represents the forecast
cooling load required from solution of the zone temperature
state-space equation. In an example implementation, the term in
Q.sub.clg,HVAC can be replaced by the zone temperature (Tz.).
[0247] FIG. 13 shows a non-limiting example flowcharts of example
processes for performing the dynamic simulation modeling, including
training and validating the model. At 30, the total historical data
available about the total load for training the model is
evaluated.
[0248] As also shown in FIG. 13, the dynamic model terms in the
load model can be determined, trained and validated. At 31, it is
determined whether sufficient historical data about load (MW) is
available. If the data is insufficient, the process may not
continue (60). If there is sufficient data, the data is separated
(33) into the contribution for the chillers versus the contribution
from other systems, including the air-handlers (AHU). If the data
cannot be separated into chiller versus air-handler loads, meter
readings can be taken (34) to gather data. An initialization occurs
at 35 to determine the coefficients of P.sub.chiller and P.sub.AHU.
At learning block 36, controlled tests are carried out to derive
the coefficients of u/k. The results of provide the dynamic model
terms in the load.
[0249] As also shown in FIG. 13, the dynamic model terms in the
temperature model are also determined, trained and validated. At
41, it is determined whether sufficient historical data about Tz is
available. If the data is insufficient, the process may not
continue (60). At 43, it is determined whether sufficient
historical data about Qclg,HVAC is available. If no, meter readings
can be taken (44) to gather data. An initialization occurs at 45 to
run an algorithm to determine the R's and the C's of the
thermodynamic properties model (such as but not limited to a
genetic algorithm (GA)). At 45, a regression is also run to
determine the Cz. At learning block 46, controlled tests are
carried out to determine the global optima over the system for the
R's, C's and Cz.
[0250] According to the systems, apparatus and methods described
herein, the procedure for determining the dynamic simulation load
model (blocks 31-36 of FIG. 13) can be performed independently of
the procedure for determining the dynamic simulation temperature
model (blocks 41-46 of FIG. 13).
[0251] According to the example flowcharts of FIG. 13, the results
of the dynamic simulation load model (blocks 31-36) can be
performed independently of the procedure for determining the
dynamic simulation temperature model (blocks 41-46). Furthermore,
the procedures of blocks 31-36 may be performed prior to,
concurrently with, or subsequent to the procedures of blocks
41-46.
[0252] In the example of FIG. 13, an end-to-end test can be
performed at 54 to validate the forecasting robustness of the
dynamic simulation models. Once successfully validated (58), the
models are ready for use in any of the systems, methods, and
apparatus described herein to perform an optimization as part of an
objective function.
[0253] Day-Ahead Engineering-Based Models
[0254] In a non-limiting example, a day-ahead engineering-based
model can be generated using a system, method or apparatus
described herein. An example objective function can be generated to
facilitate a determination of the suggested operating schedule for
at least one energy asset that includes a controllable energy
asset, based at least in part on a physical model of the
thermodynamic property of the at least one energy asset and at
least in part on data representative of model parameters. The model
parameters can be one or more of model parameters are: (a) an
operation characteristic of the at least one controllable energy
asset, and (b) a projected environmental condition during time
period T.
[0255] An example suggested operating schedule can be generated
based on an optimization of the objective function over time period
T. The objective function is determined based on a dynamic
simulation model of the energy profile of the at least one energy
asset, a customer baseline (CBL) energy profile for the at least
one energy asset (see, e.g., section above on the terms of the
engineering-based dynamic simulation model), and a forecast
wholesale electricity price, over time period T, associated with
participation of the at least one energy asset in a market. As
non-limiting examples, the market can be a wholesale electricity
market and/or a regulation market. For example, the forecast market
price can be a forecast wholesale electricity price associated with
participation of the at least one energy asset in a wholesale
electricity market. As another example, the forecast market price
can be a forecast regulation price associated with participation of
the at least one energy asset in a regulation market. The dynamic
simulation model of the day-ahead EBM can be made adaptive to
physical changes in the at least one energy asset based at least in
part on the physical model of the thermodynamic property of the at
least one energy asset. The dynamic simulation model can be trained
using the data representative of the model parameters prior to time
period T. The operation of the at least one energy asset according
to the suggested operating schedule, over a time period T,
facilitates generation of energy-related revenue based at least in
part on the market, such as but not limited to the wholesale
electricity market and/or the regulation market.
[0256] The day-ahead engineering-based model can be configured as a
day-ahead predictive engineering-based building model (OD.sup.t-1)
model. The OD.sup.t-1 model is a representation of the building and
systems to be utilized for the day-ahead forecasting and
optimization, and can be made adaptive to any changes in the
building asset. The OD.sup.t-1 model can be based on a
semi-non-linear regression. The OD.sup.t-1 model can be used to
generate operating schedules in advance of a time period over which
the energy asset is operated. As a non-limiting example, the
OD.sup.t-1 model can be used to generate an operating schedule a
day in advance (e.g., over 48 time steps in 24 hour time period).
For example, the OD.sup.t-1 model can be used to generate models
for projected/expected load, zone temperature and/or return air
pressure for the energy assets. The projected/expected load, zone
temperature and/or return air pressure are introduced into an
objective cost function. An optimization tool of the system can be
used to generate a suggested operating schedule for the energy
asset based on an optimization, over time period T, of the
objective cost function. The suggested operating schedule can be
implemented for operation of the building asset during time period
T. An example of an OD.sup.t-1 model can be derived based on the
physical model described in the section above, for modeling the
zone temperature and the load as a function of time.
[0257] A customer baseline model (CBL) may be utilized for
day-ahead and real-time prediction and optimization. The CBL can be
generated based on the data representative of model parameters of
the energy asset prior to time period T. For example, the model can
be trained using an amount of past data of the energy assets during
operation, such as but not limited to at least about 15 days, about
30 days, about 45 days, or more, of past data. The training data
allows for the determination of the coefficients of the model
parameters described above in connection with FIGS. 9-13 for a
given system including the at least one energy asset (including a
building asset).
[0258] The past data can be data representative of operation
characteristic of the at least one controllable energy asset. For
example, the operation characteristics can be a load use schedule,
or a setpoint. As non-limiting examples, the data representative of
thermodynamic property of the at least one energy asset can be past
data, such as but not limited to at least about 15 days, about 30
days, about 45 days, or more, of past data, about thermodynamic
measures.
[0259] Non-limiting examples of data representative of
thermodynamic properties include of at least one of an occupancy
schedule of the building asset, a relative humidity of the building
asset, a temperature of the building asset, a lighting level of the
building asset, a chilled water temperature, an air temperatures,
and an ice loop temperature.
[0260] Non-limiting examples of the data representative of the
projected environmental condition during time period T include at
least one of an ambient temperature of the environment in which the
building asset is located; a humidity of the environment in which
the building asset is located; an amount of solar irradiance of the
environment in which the building asset is located, an amount of
cloud cover of the environment in which the building asset is
located, an outside air temperature, an outside air humidity, an
outside air enthalpy, an outside air wet bulb temperature, a
dewpoint temperature, and a heat index.
[0261] In a non-limiting example, the dynamic simulation model can
be trained using the data representative of the operation
characteristic of the at least one controllable energy asset and
the thermodynamic property of the at least one energy asset, during
operation of the at least one energy asset under similar
environmental conditions to the projected environmental condition
during time period T.
[0262] In an example, a suggested operating schedule may be
provided as a number of bias signals that are stored to a memory
and/or transmitted to the EMS of an energy customer. The bias
signals can be implemented according to the suggested operating
schedule to control the operation of the energy assets to
facilitate the generation of the energy-related revenue, as
described hereinabove.
[0263] In another example implementation, managing various energy
assets may be implemented according to the suggested operating
schedule in a phased manner to facilitate revenue generation from
wholesale electricity markets, regulation markets, or other
ancillary markets. Such a suggested operating schedule may be
provided as an interruptible load function, or as a modulation
signal. For an interruptible load function, the instructions would
specify the types of components, equipment, and/or computing
resources to power off or power on during various time intervals of
time period T, and in what combinations according to the suggested
operating schedule. For a modulation signal, the instructions would
specify the types of components, equipment, and/or computing
resources to whose operation parameters can be increased or
decreased, in order to increase or decrease its load during various
time intervals of time period T, and in what combinations according
to the suggested operating schedule. Each phase of the suggested
operating schedule may target a specific energy asset resource, and
phases may be implemented sequentially over time for a given set of
energy assets, or in any combination concurrently for a given set
of energy assets. For example, a first phase may target the HVAC
system of a building; a second phase may target backup generators,
other distributed energy generation resources (e.g., renewables),
and energy storage resources (e.g., batteries) (collectively "power
resources"); and a third phase may target other specific resources
of a site, such as but not limited to the different type of
equipment in a building complex of manufacturing site, or the
server computing load of the multiple servers at a building that
houses a data center.
[0264] Real-Time Engineering-Based Models
[0265] In a non-limiting example, a real-time engineering-based
model can be generated using a system, method or apparatus
described herein. The OD.sup.t model can be based on a linear
representation of the building and systems to be used in live
operation for adaptive optimization and short-term forecasting. In
an example, the OD.sup.t model can be used to generate models for
projected/expected load, zone temperature and/or return air
pressure that can be updated using a feedback mechanism, such as
but not limited to Kalman filtering, based on measurements during
operation of systems of the energy assets, such as the building
asset.
[0266] The OD.sup.t model can be updated in real time (adjustable)
using a Kalman Filter (KF) algorithm. For example, the OD.sup.t
model can be updated using a KF algorithm at regular intervals
(such as but not limited to about every minute, or about every few
minutes, or about every half hour). The KF is a recursive tool that
obtains optimal estimations of the system state as well as the
online identification of parameters of the system state-space
equation. The KF can be determined when the model is run for state
estimation, and/or for online parameter identification based on
targeted model accuracy. The OD.sup.t model can be run and updated
using KF as many times as required to reach a solution. The
OD.sup.t model can be described as a linear state-space system.
[0267] In a non-limiting example, the KF can be implemented as
described in FIG. 14. The state estimate and/or the model
parameters can be updated in real-time, such as but not limited to
about each minute, or every few minutes.
x.sub.k=G.sub.k*x.sub.k-1+I.sub.k+u.sub.k+e.sub.k
z.sub.k=H.sub.k*x.sub.k+.eta..sub.k Eq. 34
Nomenclature of abbreviations in FIG. 14 is as follows:
[0268] x.sub.k is the state vector at time step k
[0269] G.sub.k is the state transition matrix at time step k
[0270] u.sub.k is the input at time step k
[0271] I.sub.k is the input matrix at time step k
[0272] e.sub.k is the process noise, following normal distribution
i.i.d N(0,Q.sub.k)
[0273] z.sub.k is the observation vector at time step k
[0274] H.sub.k is the observation matrix at time step k
[0275] .eta..sub.k is the observation noise, following normal
distribution i.i.d N(0,R.sub.k)
[0276] As shown in FIG. 14, the KF can be implemented, during time
period T of operation of the energy asset(s) according to the
suggested operating schedule, as a time update in a first stage and
as a measurement update in a second stage. In the first stage, as
described in FIG. 14, the system state is predicted at a time t
during time period T based on the suggested operating schedule. The
estimation error is propagated to provide the time update. In the
second stage, a measurement update is performed. The predicted
state is compared to the measured state. As a non-limiting example,
a measurement is made of at least one of (i) an operation
characteristic of a controllable energy asset, (ii) a thermodynamic
property of the energy asset, (iii) an actual environmental
condition. Based on the comparison of the predicted state and the
measured state, the estimation error is updated. The parameters of
the suggested operating schedule are updated based on the results
of the KF process to provide an updated operating schedule. Using
the KF, the state estimate and/or the model parameters can be
updated in real-time, such as but not limited to about each minute,
or every few minutes during time period T.
[0277] Day-After Engineering-Based Models
[0278] In a non-limiting example, a day-after engineering-based
model can be generated using a system, method or apparatus
described herein. In a non-limiting example, the configuration of
the day-after engineering-based model can be used to generate the
CBL for the system.
[0279] The OD.sup.t+1 model can be based on a highly non-linear
representation of the building and systems. Three OD.sup.t+1 models
can be developed to closely match the customer load under
business-as-usual operations as well as under the control of the
operating schedule of the real-time OD.sup.t model. All of the CBL
models can be run and the model with the best accuracy can be
selected for settlement purposes with an industry participant in a
market and/or other RTOs/ISOs. The OD.sup.t+1 models can be
expressed as:
[0280] Non-Linear Kernel CBL Model
[0281] The non-linear kernel can be used to generate a non-linear
representation of a system that includes the at least one energy
asset. For example, for an energy asset that is a building asset,
the kernel CBL model may take the form of either Eq. 35, Eq. 36 or
Eq. 37:
ln ( Load ( t ) ) = A i .times. WeatherInput i ( t - j ) + B i
.times. ZoneTemperature ( t - j ) + C i .times. ln ( PriorLoad ( t
- j ) ) + D i .times. HVACSchedule ( t - j ) + F i .times.
ControlSetpoint ( t - j ) + G i .times. HVACTemperature i ( t - j )
or Eq . 35 Load 2 ( t ) = A i .times. WeatherInput i ( t - j ) + B
i .times. ZoneTemperature ( t - j ) + C i .times. PriorLoad 2 ( t -
j ) + D i .times. HVACSchedule ( t - j ) + F i .times.
ControlSetpoint ( t - j ) + G i .times. HVACTemperature i ( t - j )
Eq . 36 ( Load ( t ) ) neuralnetwork = funtion [ ( PriorLoad ( t -
i ) , WeatherInput ( t - i ) , PriorZoneTemperature ( t - i ) ,
weekday ( t - i , HVACShedule ( t - i ) Eq . 37 ##EQU00015##
[0282] FIG. 15 depicts the neural network of Eq. 37, and shows the
functional form of applicable transfer functions, including a
log-sigmond transfer function and a tan-sigmond transfer
function.
[0283] FIG. 16 depicts the parallel neural network architecture
that can be used where it re-iterates using the output from the
previous iteration. The series-parallel architecture can be used
using the input of a state function and some data representing
prior measurements of load.
[0284] Higher order representation may be used for load and/or all
inputs. The CBL model may be used for real-time optimization and
prediction. In such cases, the KF may be a non-linear tool such as
an extended Kalman Filter or similar.
[0285] Artificial Neural Network AutoRegressive
[0286] External Input (ANN-NARX) CBL Model
[0287] A feed forward NARX network architecture of the form shown
in Eq. 38 can be used in an example ANN-NARX for generating a CBL
Model:
Load(t)=(7)function[(Load(t-1),Load(t-1), . . .
,Load(t-j),WeatherInputs(t), . . .
,WeatherInputs(t-j),ZoneTemperatures(t-j),Weekday(t-j),HVACSchedule(t-j),-
ControlSetpoints(t-j),HVACTemperatures(t-j)] Eq. 38
[0288] In a non-limiting example, the neural network has two hidden
layers, each with ten neurons.
[0289] Another example engineering-based model that is applicable
to the systems, methods and apparatus described herein is shown in
Eq. 39.
kW = kWi + kWd Tz t = A ' * OAT + B ' * T z + C ' * ( T spt + bias
) kWd = occ * [ A * f ( weather ) + B * f ( indoor ) ] kWi = f (
time , day ) = time series model Eq . 39 ##EQU00016##
[0290] Eq. 39 show an example multiple regression engineering-based
model to which the physical model of the thermodynamic property can
be added. The model includes a total load term (in units of
kiloWatt (kW)) as a combination of a load term that is independent
of environmental conditions (a weather independent load term kWi)
and a load term that is dependent on environmental conditions (the
weather dependent load term kWd). The weather dependent load term
kWd is modeled as a term in an outside environmental condition
(such as but not limited to the outside air temperature (OAT) and
the outside air humidity (RH)) and the indoor inputs (such as but
not limited to the zone temperature and the zone humidity),
weighted by a value of "occ" (the building occupancy schedule or by
the HVAC operating schedule, which reflects when the building is
occupied vs. unoccupied). The kWd term may depend mainly on the
HVAC. A statistical analysis or other analysis tool can be
implemented to determine model parameters in the kWd model. The
weather independent load term kWd is modeled as a time series that
can vary with the day of the week and/or with the time of day. For
example, the weather independent load term on a weekday can differ
from that on a weekend, and can also vary according to time of day
for a given day. For example, the weather independent load term can
differ between business hours and off-peak times. In addition, the
weather independent term may vary with a time series dependent on
season, weekdays, holidays/weekend. A Fourier analysis can be used
to solve the weather independent load term.
[0291] In a non-limiting example, load modeling results with
application of the multiple regression are as follows. The
coefficient of variation from actual load is between about 3% to
about 10% within a day type; and within about 10-20% overall. The
example building asset load was on average 700 kW; the multiple
regression model root-mean-square error (RMSE) varied between 49 kW
to 65 kW per day type.
[0292] The model of Eq. 39 also includes a term for modeling the
zone temperature (Tz) of a building energy asset based on a
regression. The time-dependent variation in the zone temperature
(Tz) is modeled as a regression over the outside air temperature
(OAT), the zone temperature (T.sub.z), the target zone (setpoint)
temperature (T.sub.spt) and a temperature deviation (as a bias). As
described above, a term that models the thermodynamic properties of
the system is added, which increases the accuracy of the
modeling.
[0293] The coefficients A', B', C', are determined during the model
training and fitting process. These coefficients can be updated in
real-time through a feedback and auto-corrective loop, e.g., during
a real-time engineering-based operation.
[0294] The comfort index (CI) is used in this example to provide a
measure of an occupant's comfort on a scale of 0 to 100, where
CI=100% when Tz is within the cooling and heating setpoints (72 F
to 78 F) and RHz is within 40%-60% (consistent with the American
Society of Heating, Refrigerating and Air-Conditioning Engineers
(ASHRAE) Standard 55-2007).
[0295] FIG. 17 is a plot showing the relationship between different
values of the comfort index (CI), the outside air humidity and the
humidity.
[0296] Systems for Implementation of an Engineering-Based Model
[0297] FIGS. 18-22 show non-limiting examples of functional block
diagrams of systems and apparatus that can be implemented to
perform any of the engineering-based models according to the
principles described herein. FIG. 18 shows a functional block
diagram of a PID controller. FIGS. 19-22 show functional block
diagrams of configurations of systems and apparatus for
implementing a CBL computation, a day-ahead EBM modeling, a
real-time EBM modeling, a day-after EBM modeling, respectively.
[0298] Non-limiting examples of data that can be received by a
communication interface of the example systems and apparatus as
input date to implement an engineering-based model include: a) a
customer's total load, b) a customer's HVAC load (if applicable),
c) customer's weighted average building temperature, and d) a
customer's local weather conditions.
[0299] In an example, a test may be used to validate the customer's
load models and control.
[0300] Building Parameters Database for Faster Implementation
[0301] According to the principles described herein, the parameters
of a EBM model (including the day-ahead, real-time, day-after and
CBL models), may be stored in a database to result in faster
implementation. For example, once a EBM model is built and trained
as described herein, it may be implemented in an optimization over
an objective function to generate suggested operating schedules on
other physically comparable energy assets (including on physically
similar building assets). The database may be used to classify
buildings and parameters in categories, such as but not limited to
the following categories:
[0302] a) Building Envelope: light, medium or heavy
construction
[0303] b) Building Fenestration: light or heavy fenestration
[0304] c) Building Type: commercial, industrial, residential or
institutional
[0305] Proportional Integral Derivative (PID) Loop
[0306] A PID controller algorithm also is developed to correct in
real-time the bias signal sent to the building and ensure the
target load reduction is achieved. The PID can be used to provide a
measure of error (including ranges of values within the error)
around a bias signal and to refine a business-as-usual
approximation. BMS refers to the building management system that
controls, e.g., equipment in the building (control signals can be
sent to the BMS).
[0307] An example PID operates as illustrated shown in the
functional block diagram of FIG. 18. Non-limiting examples of a
"control" is a load (represented by kW), a zone temperature
(represented by Tz), or other controllable asset (any other
parameter sought to be controlled, including but not limited to a
voltage). The PID model of FIG. 18 may be implemented so that the
"control" is only the load (kW), only the zone temperature (Tz),
only one of the other controllable assets, or any combination of
two or more of the load, the zone temperature, and one or more of
the other controllable assets. Applying the PID to load (kW) can be
used to achieve an economic priority, i.e., ensuring that a load
(kW) target is maintained within a predetermined allowable economic
range. Applying the PID model to zone temperature (Tz) can be used
to achieve a comfort priority, i.e., seeking to ensure that a zone
temperature (Tz) target is maintained within a predetermined
allowable comfort zone. In an implementation, the PID model is
applied to both the load (kW) and the zone temperature (Tz) as
"controls".
[0308] System Configurations for Implementing Engineering-Based
Models
[0309] Non-limiting example system configurations for implementing
the example engineering-based models are described in connection
with FIGS. 19-22.
[0310] In each figure, the term M&V refers to measurement and
verification; ADP refers to a dynamic programming solver. The terms
RH and RH.sub.z refer to the relative humidity of outside air (RH)
and building humidity (RH.sub.z). T and T.sub.z refer to
temperature, where Tz is a target zone temperature.
[0311] Engineering-Based Models and Optimizers
[0312] Example outputs from the engineering-based models are
predicted load and predicted zone return air temperature. Examples
of optimizations that can be run include according to the systems,
apparatus, and methods described herein include a day-ahead
optimization and a real-time optimization.
[0313] Day-Ahead (OD.sup.t-1) Optimization
[0314] FIG. !9 shows a functional block diagram of a system
configuration for application of an optimization during the
day-ahead EBM computation. The OD.sup.t-1 predictive model can be
utilized to project the load in the energy asset (s), such as but
not limited to a building. Based on price and weather forecasts, an
optimal operating schedule of setpoints or biases can be determined
to maximize revenues while maintaining comfort. The day-ahead
optimization can be constrained by the zone temperature equation
(2). Boundaries can be set for setpoint control range of typical
occupants' comfort as determined by an energy customer or as set by
the ASHRAE Standard 55-2010.
[0315] For poorly sensed buildings, including buildings with
insufficient training data to capture the effect of temperature
setpoints on the real zone temperature, a hybrid zone temperature
equation of following form can be utilized:
A*RAT(t+1)=B*(OAT-RAT)(t)C*SPT(t)-D*RAT(t)+E Eq. 40
[0316] If the hybrid RAT equation does not provide robust
constraint for optimization, change in temperature setpoint can be
limited to the maximum recorded change in actual zone
temperature.
[0317] Real-Time (OD.sup.t) Optimization
[0318] FIG. 19 shows a functional block diagram of a system
configuration for application of an optimization during the
real-time EBM computation. In real-time operation, the OD.sup.t
model can be used to predict the load of the next time step. The
optimizer can be run after each Kalman Filter update.
[0319] Non-Limiting Example Implementation
[0320] The engineering-based model can be applied to all building
types, including but not limited to poorly-sensed buildings.
Results of non-limiting example implementations are described. In
these examples, the term AHU relates to the status of mechanical
equipment (such as a HVAC system), OAH refers to outside air
humidity, SPT refers to setpoint, and Qirr refers to solar
irradiance.
[0321] EBM Models Applied to First Example Building Asset
[0322] A non-limiting example is described of application of EBM
models for modeling energy assets of a First Example Building. The
EBM models can be used, according to the systems, methods and
apparatus described herein, to facilitate generation of
energy-related revenue based on optimization of an objective cost
function.
[0323] Day-Ahead EBM
[0324] Based on data representative of operation characteristics
and the thermodynamic properties of the First Example Building
Asset, a day-ahead EBM model of the building asset is computed as
described herein.
[0325] Optimizer Module
[0326] In an example, an optimizer can be implemented to provide at
least one solution set with respect to minimizing energy costs of a
customer site (including the at least one energy asset). As
described hereinabove, the optimizer can be implemented to minimize
the net energy related costs (expressed as follows) over a time
period T to determine the possible energy-related revenue that may
be derived:
Min [ t T ( Supply $ ( t ) - DR $ ( t ) ) ] Eq . 41
##EQU00017##
where the term Supply$(t) indicates the total cost to supply the
energy and demand response revenue. As a non-limiting example, the
optimizer can be implemented according to the following
equations.
Minimize[T$.sub.dev+Emission$+Gen$+Supply$-DR$] Eq. 42 [0327]
where
[0327] T$.sub.dev=Cost of deviations from the business-as-usual
comfort levels (including BAU temperature level)
Emission$=Cost/value of deviations from the emission target
Gen$=Cost of electric power production by the customer energy
generating assets
Supply$=Cost of electric power supply from the Load Serving Entity
or the Electric Distribution Company
DR$=max(0,(CBL-Load))*(LMP-G&T Rate) Eq. 43 [0328] where [0329]
CBL=Customer baseline [0330] Load=Actual customer usage [0331]
LMP=Locational Marginal Prices [0332] G&T Rate=Generation &
Transmission Rate
[0333] In an example implementation, the minimization
(Minimize|.sub.T) can be computed, for a specified time period T,
based on Eq. 41 or 42 for the time varying parameters. As a
non-limiting example, time period T can be a period of 24 hours, 48
hours, or any other specified time period. In this example, an
optimizer can be implemented to perform a method according to
minimization (Minimize|.sub.T), for the specified time period T. In
an example implementation, the minimization can be computed as a
continuous function over the entire time period T. In another
example implementation, the minimization can be computed over
discrete portions of the function for several time intervals
(.DELTA.t) that sum to time period T. As a non-limiting example,
the minimization can be computed over 48 different half-hour time
intervals, for a total time period of T=24 hours.
[0334] An aspect of an optimizer is that the optimization
determines a suggested operating schedule that can facilitate an
overall economic benefit (including deriving energy-related
revenue) over the entire time period T, even if the operating
schedule may call for a mode of operation during a given time
interval (t.sub.1 to t.sub.2) during time period T that may not
take advantage of the lowest energy market price or lowest cost of
energy production during that time interval (t.sub.1 to t.sub.2).
For example, the suggested operating schedule may determine an
operating schedule that calls for increased load if, for example,
the load is used to charge an energy storage asset that can be
committed to a regulation market if the regulation market price is
sufficiently favorable to the overall economic benefit, for the
entire time period T, when the suggested operating schedule is
performed over the entire time period T.
[0335] To generate the suggested operating schedule, the optimizer
can perform computations over various parameters, such as but not
limited to the forecast wholesale market price over time period T
for participating in the energy market, the regulation market price
available to the customer and over what time interval, other
potential energy-related revenue (including synchronized reserve
markets and capacity markets), and the energy responsive behavior
of each of the customer's energy assets. For example, the suggested
operating schedule may include processor-executable instructions
that cause a backup generator to be committed to an economic demand
response market, a synchronized reserve market, or a capacity
market as a part of the overall optimization over the time period
T. In another example, the building of the customer site, the
occupancy of the building, the HVAC systems; chillers; ventilators;
heaters; lighting; or other similar energy assets can exhibit
thermal inertia, i.e., it can take longer time scales for such
energy assets to respond to a change in signal to reach a change of
state (e.g., get to a lower temperature). The operating schedule
can include processor-executable instructions to commit these types
of energy assets to respond to an economic demand response market,
a capacity market and/or a power quality market at some time
interval during time period T based on the modulation of use of
these energy assets. In other examples, the state of charge of a
battery at a given point in the day determines whether it has
sufficient capacity to be committed to any of the economic demand
response market, regulation market, synchronized reserve market,
capacity market or power quality market. As another example, the
suggested operating schedule can include processor-executable
instructions that cause energy assets (including the servers in a
computing facility) to be committed to a regulation market based on
modulating the operation of the controllable energy asset, where
the controllable energy asset can respond on a fast timescale
(e.g., according to regulation signals that can change potentially
at 2-second time intervals). Non-limiting examples of the
modulation of the operation of controllable energy assets include
changing the speed of fans, changing the computing levels of
servers and other computing equipment, modifying variable frequency
and/or variable speed of components (such as but not limited to
modifying the frequency and/or speed of a motor, a fan, any other
ventilation equipment, and/or a pump), cooling rate/speed of the
HVAC and a chill rate of the chiller. Given that increased load
consumption of a controllable energy asset can cause them to heat,
and as a result may also require increased cooling, there can be an
interaction term between the modulation of controllable energy
assets and the usage of energy assets such as HVAC systems;
chillers; ventilators; or heaters. As a result, implementation of
controllable energy asset in, e.g., the regulation market, can
affect how energy assets such as HVAC systems; chillers;
ventilators; or heaters are implemented in the energy markets,
through time-based interaction terms. The systems, methods and
apparatus described herein perform optimization that evaluate the
types of energy assets in each customer site, the state of each of
the various energy assets at each customer site, the markets
available to each different customer site and the forecast prices
for each such market, and the behavior of each energy asset, all
over a specified time period T. The result is generation of a
suggested operating schedule for the various energy assets (and/or
for the controller of each energy asset), that, when executed, can
generate energy-related revenue, over a time period T, associated
with operation of the energy assets according to the operating
schedule.
[0336] Energy Management System
[0337] FIG. 23 illustrates a block diagram of an energy management
environment 100 that includes an energy management system 110 to
facilitate generation of revenue from energy markets, according to
the principles described herein. In FIG. 23, energy customers are
the end-users and/or consumers of electricity supplied by a retail
electricity supplier (via electricity grid 105). Additionally, some
customers may have electricity generation capabilities for
providing electricity back to the grid and/or for supplying
electricity to the customers' own electricity-consuming assets.
[0338] Energy management system 110 may include one or more
processors 112, one or more memory devices 114, and one or more
communication interfaces 115. Processors 112 may be configured to
execute software applications (e.g., processor-executable
instructions stored in one or more memory devices 114), and/or work
in tandem with other hardware components, for managing the overall
operations of energy management system 110. In a service-oriented
architecture (SOA), processors 112 may implement a variety of
functionality for supporting the SOA. In one example, communication
interfaces 115 may include a web interface and an enterprise
service bus. Additional details regarding processors 112, memory
114, and communication interfaces 115 are described with reference
to FIG. 24.
[0339] One or more system operators 116 may be associated with
energy management system 110. System operators 116 may access
energy management system 110 via an operator portal 118. Operator
portal 118 is the user interface by which a system operator 116 may
manage the process of creating an energy assets operating schedule.
The optimized operating schedule covers a chosen period of time.
Once an optimized operating schedule is transmitted to and accepted
by the customer, in some examples operator portal 118 may be used
by a system operator 116 for monitoring and/or controlling a
customer's energy assets in real time.
[0340] Customer sites 120 and end-users (energy customers) 128 of
energy management environment 100 represent the customers and/or
consumers of the electricity supplied by retail electricity
suppliers via the grid 105. Customer sites 120 may be any
electricity-consuming and/or electricity-generating environments,
such as, but not limited to, a building or group of buildings
belonging to energy grid customers. End-users 128 may be any
individuals associated with customer sites 120. Examples of
end-users 128 may include building supervisors, company employees,
company executives, and the like. Each customer site 120 may
include one or more energy assets 126. Energy assets 126 may be any
configuration of one or more energy usage assets, one or more
energy storage assets, one or more energy generation assets, one or
more renewable energy assets, and any combinations thereof. Groups
of energy assets 126 and/or buildings associated with a certain
customer site 120 may be in close physical proximity to each other
or may be physically distant and even separated by time zones.
[0341] A monitoring and control system 122 may be installed at each
customer site 120. One example of monitoring and control system 122
is a building management system (BMS). Another example of
monitoring and control system 122 is a building automation system
(BAS). The main function of a BMS and BAS is to manage the
environment within a building or group of buildings. For example,
the BMS or BAS may control temperature, carbon dioxide levels, and
humidity within a building via certain energy assets 126. In one
example, an end-user 128 of a certain customer site 120 uses
monitoring and control system 122 to monitor and/or manage the
energy assets 126 thereof. Monitoring and control system 122 may be
any commercially available BMS or BAS, such as those supplied by
Johnson Controls, Inc (Milwaukee, Wis.), Automated Logic
Corporation (Kennesaw, Ga.), and Honeywell International, Inc
(Morristown, N.J.).
[0342] The web-based operator portal 118 and/or the web-based
customer portal 130 may be accessed via any web-enabled device,
such as, but not limited to, any desktop computer, laptop computer,
tablet computer, net-book computing device, handheld computing
device, personal digital assistant, enterprise digital assistant,
portable digital assistant, cell phone, smart phone, and the
like.
[0343] Additionally, energy management environment 100 may include
any other entities that may be useful to (and communicate with from
time to time, e.g., via network 170) energy management system 110
for operating, using, and/or controlling energy assets 126 of
customer sites 120. Examples of other entities may include, but are
not limited to, energy regulatory agencies 150 (e.g., FERC) and
ISOs/RTOs 152. The energy regulatory agencies 150 and/or ISOs/RTOs
152 may be a source of any information that is useful to energy
management system 110 for operating, using, and/or controlling
energy assets 126 of customer sites 120. Examples of useful
information sources may include, but are not limited to, rules
information 154, and/or energy price information 156. Rules
information 154 may be any rules, regulations, and/or guidelines
according to any authorized entity related to the electric power
industry, such as, but not limited to, energy regulatory agencies
150 and/or ISOs/RTOs 152.
[0344] Additionally, energy management environment 100 may include
a source of weather information 160. In one example, weather
information 160 may be information supplied by a third party
service, such as, but not limited to, AWIS Weather Services, Inc.
(Auburn, Ala.). In another example, weather information 160 may be
information supplied by a national and/or regional weather service
that may be accessed using the Internet via a network 170. Examples
of weather websites may include, but are not limited to, the NOAA
National Weather Service website (at nws.noaa.gov), the Weather
Channel website (at weather.com), and the Weather Underground
website (at wunderground.com).
[0345] Weather information 160 may be useful to the optimization
function of energy management system 110 with respect to predicting
the actual environmental conditions in a building or group of
buildings. For example, the optimization function may factor in the
delta between the outside temperature and inside temperature.
Additionally, the optimization function may factor in the amount of
cloudiness with respect to solar gain calculations. For example,
the solar gain may be lowest on a cloudy day, highest on a day that
is not cloudy, and anything in between.
[0346] Additionally, energy management environment 100 may include
certain emissions regulatory agencies 162 that may be the source of
certain emissions information 164. Emissions regulatory agencies
162 may be any federal, regional, state, and/or municipal
regulatory bodies that facilitate emissions trading programs. In
the United States, the Environmental Protection Agency (EPA) is an
example of an emissions regulatory agency 162. In Europe, the
European Union (EU) is an example of an emissions regulatory agency
162. Emissions information 164 may include emissions cap
information, cost information for buying emissions credits, and/or
price information for selling emissions credits. Additionally,
emissions information 164 may include any published information
about the local energy grid (e.g., energy grid 140) with respect to
the emission of pollutants and/or greenhouse gases (GHG).
[0347] Network 170 may be, for example, any local area network
(LAN) and/or wide area network (WAN). Network 170 provides the
communication link between any and/or all entities of energy
management environment 100. For example, energy management system
110, operator portal 118, customer sites 120, customer portal 130,
regulatory agencies 150, ISOs/RTOs 152 and/or emissions regulatory
agencies 162 may be connected via network 170. Entities may connect
to network 170 using any wired and/or wireless networking
protocols. Additionally, rules information 154, energy price
information 156, weather information 160, and/or emissions
information 164 may be accessed via network 170.
[0348] Once a model is created, the environmental conditions within
the building or group of buildings of a certain customer site 120
may be simulated based on the input criteria of the model. The
simulation results are then fed into an optimization function,
which is a cost minimization function that includes a combination
of multiple sub-functions, of energy management system 110 that
processes the information and generates an optimized operating
schedule, within a set of constraints. That is, the optimization
function of energy management system 110 is used to create an
operating schedule (for a chosen period of time) for energy assets
126 of a customer site 120, wherein the operating schedule for the
energy assets 126 is optimized for reducing energy costs, reducing
emissions costs, and/or generating revenue from energy markets.
[0349] Energy management system 110 may also include a markets
component (see FIGS. 2 and 7) for interacting with any entities in
the energy markets. In one example, the markets component processes
settlements in any energy markets between the ISOs/RTOs and
consumers. Energy management system 110 also provides a simplified
and/or automated process of managing the energy assets in any
energy-consuming and/or energy-producing environment, such as, but
not limited to, a group of energy assets and/or a building or group
of buildings. Energy management system 110 is used to facilitate an
energy management service to customer sites 120 of energy
management environment 100.
[0350] The optimized operating schedule for the chosen period of
time is stored at energy management system 110 and then transmitted
(i.e., deployed) to the monitoring and control system 122 of the
customer site 120. The energy assets 126 are then operated and/or
controlled according to the optimized operating schedule. In the
deployment process, the process of an end-user 128 of a customer
site 120 accepting an optimized operating schedule from energy
management system 110 may be iterative. Once the optimized
operating schedule is deployed and in service, system operators 116
may use operator portal 118 to monitor and/or control the operation
of the energy assets 126 of customer site 120. Likewise, end-users
128 may use customer portal 130 to monitor and/or process
information about the operation of the energy assets 126 of
customer site 120. Additional details of an example of a process of
creating and optimizing a schedule for managing energy assets of
any energy-consuming and/or energy-producing environment are
described with respect to FIG. 21.
[0351] FIG. 24 illustrates a block diagram showing additional
details of energy management system 110 of FIG. 23. For example,
FIG. 24 shows energy management environment 100 of FIG. 23
implemented in a service-oriented architecture (SOA). In the
service-oriented architecture shown in FIG. 24, the server side of
energy management environment 100 is energy management system 110
while the client side of energy management environment 100 may
include any number of customer sites 120, such as customer sites
120-1 through 120-n.
[0352] In one example, energy management system 110 may include
certain functional components and/or modules that are installed and
executing in memory 114 and managed by the one or more processors
112. Examples of functional components and/or modules of energy
management system 110 may include, but are not limited to, certain
core SOA components 210, a schedule builder module 212 that feeds
an optimizer 214 (e.g., optimization software), a markets module
216, and a database 218. Energy management system 110 also includes
a supervisory control and data acquisition (SCADA) system 220 as
well as various servers 222 for supporting the SOA. The functional
components and/or modules of energy management system 110 may
communicate via an enterprise service bus 230. Enterprise service
bus 230 manages "calls" in and out of energy management system 110.
A set of adaptors (not shown) may be connected to enterprise
service bus 230 for interfacing with any entities that are outside
of energy management system 110, such as, but not limited to, the
monitoring and control system 122 of any customer sites 120, energy
regulatory agencies 150, ISOs/RTOs 152, rules information 154,
energy price information 156, weather information 160, emissions
regulatory agencies 162, and emissions information 164. The
adaptors (not shown) are connected to enterprise service bus 230
for handling various communication protocols.
[0353] Energy management system 110 also includes a web interface
232. Web interface 232 may be, for example, any web browser that
allows energy management system 110 to be accessed via a URL
address. In addition to using enterprise service bus 230, the
monitoring and control system 122 of any customer sites 120, energy
regulatory agencies 150, ISOs/RTOs 152, rules information 154,
energy price information 156, weather information 160, emissions
regulatory agencies 162, and emissions information 164 may
communicate with energy management system 110 via web interface
232. Additionally, the one or more operator portals 118 and
customer portals 130 may communicate with energy management system
110 via web interface 232.
[0354] To integrate diverse monitoring and control systems 122 with
energy management system 110, a physical connection from the
monitoring and control systems 122 to network 170 is required.
Therefore, a gateway 121 may be associated with each monitoring and
control system 122 of customer sites 120. Gateway 121 may be any
translation device between the output of energy management system
110, which is using a specified protocol, and one of any number of
different BMS or BAS protocols and/or different energy asset device
protocols. Accordingly, gateway 121 is installed at the physical
location of the monitoring and control system 122 of a customer
site 120. The presence of gateway 121 with each monitoring and
control system 122 allows energy management system 110 to be
substantially customer-agnostic by connecting common network
protocols, such as, but not limited to, LONWORKS.RTM. (Echelon
Corporation, San Jose, Calif.), BACNET.RTM. (ASHRAE, Atlanta, Ga.),
and MODBUS.RTM. (Modbus Organization, Inc.), along with many
proprietary network protocols.
[0355] In another example, optimizer 214 may use energy price
information 156 to indicate to customer sites 120 to charge
batteries at times of day when energy prices are lowest and to
utilize (discharge) the batteries at times of day when energy
prices are highest; again, reducing energy costs of a customer site
120.
[0356] In yet another example, optimizer 214 may use energy price
information 156 to generate optimized operating schedules for
energy assets 126 that may be used to indicate to end-users 128 at
customer sites 120 when to bid into any of the various wholesale
electricity markets, such as (1) the energy market, (2) the
day-ahead scheduling reserve market, (3) the capacity market, (4)
the synchronized reserve market, and (5) the regulation market.
[0357] With respect to emissions information, optimizer 214 may use
emissions information 164 to generate optimized operating schedules
for energy assets 126 that may be used to indicate to end-users 128
at customer sites 120 opportunities to buy and/or sell emissions
credits. In this way, customer sites 120 may have opportunity to
reduce emissions and/or receive revenue from emissions trading.
[0358] Markets module 216 may be a software component of energy
management system 110 for interacting with any entities in the
energy markets, such as ISOs/RTOs, any/or with any entities in the
emissions trading markets. For example, markets module 216 may
include certain market interfaces, which may be any mechanisms for
interfacing with the market. Further, markets module 216 may
include a registration component that is used for registering
energy assets in a particular market for committing assets.
Additionally, markets module 216 may include a markets bidding
component that is used to submit bids into certain energy markets.
Additionally, markets module 216 may include an energy markets
settlements component that is used to process settlements in any
energy markets between, for example, ISOs/RTOs 152 and customer
sites 120. Markets module 216 may also include an emissions market
settlements component that is used to process settlements with
respect to emissions trading, such as settlements between emissions
regulatory agencies 162 and customer sites 120.
[0359] SCADA stands for supervisory control and data acquisition.
It generally refers to industrial control systems, such as computer
systems that monitor and control industrial, infrastructure, and/or
facility-based processes. In energy management system 110, SCADA
system 220 may be used to communicate directly with customer sites
120. SCADA system 220 may also communicate with other components of
energy management system 110 via enterprise service bus 230. SCADA
system 220 handles, for example, ancillary services, such as
"regulation" and "synchronized reserve."
[0360] FIG. 25 illustrates a block diagram of schedule builder
module 212 of energy management system 110 of FIG. 24. Schedule
builder module 212 may include any components for processing any
information that may be useful with respect to creating an
optimization case 310 with respect to energy assets. For example,
schedule builder module 212 may include a customer component 312
for processing customer information (e.g., customer site 120
information), a location component 314 for defining and/or
configuring the customer's location, a supply contract component
316 for processing supply contract information, a strategy
component 317 for processing optimization strategy information, a
price component 318 for processing energy price information 156, a
weather component 320 for processing weather information 160, a
solar gain component 322 for processing solar gain information,
and/or an emissions component 324 for processing emissions
information 164.
[0361] Customer component 312 may process customer information
(e.g., customer site 120 information), such as, but not limited to,
customer name and contact information, customer type information
(e.g., a university, a business, a retailer, a hospital, a
factory), building (s) occupancy information, miscellaneous load
information (e.g., lighting, any electric powered equipment), and
the like.
[0362] Location component 314 may be used for defining and/or
configuring the customer's location. The definition of a customer's
location is not limited to a geographic address. Rather, the
customer's location may be any configuration of energy assets,
buildings, and/or geographic locations. For example, the customer's
location may be configured as one building; a groups of buildings;
one energy asset; a group of energy assets; one energy asset for
one building; one energy asset for multiple buildings; one
monitoring and control system 122 per building; multiple monitoring
and control systems 122 per building; one monitoring and control
system 122 for multiple buildings; energy assets and/or buildings
in one town, city, or state in combination with energy assets
and/or buildings in another town, city, or state; and the like.
Additionally, groups of energy assets or buildings may be in close
physical proximity to each other or may be physically distant and
even separated by time zones.
[0363] Supply contract component 316 may be used to process supply
contract information, which is the service contract between the
ISOs/RTOs 152 and customer sites 120.
[0364] Strategy component 317 may be used to process optimization
strategy information. For example, the optimization strategy may be
determined by the definition of a customer's location per location
component 314. That is, the grouping of energy assets and/or
buildings may determine the best optimization strategy for the
case. Example strategies include, but are not limited to single
optimization, iterative optimization, customer baseline (CBL)
optimization, parametric estimation optimization, and so on.
[0365] Price component 318 may be used to process energy price
information 156. For example, price component 318 may query
ISOs/RTOs 152 for energy price information 156 with respect to any
energy market in a certain geographic region, such as the day-ahead
energy market and the real-time energy market.
[0366] Weather component 320 may be used to process weather
information 160. For example, weather component 320 may query
weather information 160 for current and/or predicted temperature
and/or cloud cover information for a certain geographic location
per location component 314. Per weather component 320 and/or
weather information 160, optimizer 214 may factor in the delta
between the outside temperature and inside temperature of a
building or group of buildings. Additionally, per weather component
320 and/or weather information 160, optimizer 214 may factor in the
amount of cloudiness with respect to solar gain calculations.
[0367] Solar gain (also known as solar heat gain or passive solar
gain) refers to the increase in temperature in a space, object, or
structure that results from solar radiation. The amount of solar
gain increases with the strength of the sun, and with the ability
of any intervening material to transmit or resist the radiation.
With respect to schedule builder module 212, solar gain component
322 may process solar gain information about one or more buildings
of customer site 120 per location component 314. For example,
building-specific solar gain information, which is based on an
analysis of the customer's building and/or buildings and weather
information per weather component 320. That is, solar gain is
determined by the direction and orientation of windows, direction
and orientation of the sun (by day of the year), and amount of
cloud cover. For example, the solar gain may be lowest when cloudy
and highest when not cloudy, and anything in between. Again,
optimizer 214 may factor in the amount of cloudiness with respect
to solar gain calculations. Other factors of solar gain include
building information (e.g., size, mass, type and thickness of
building materials, R-factor, etc) and window information (e.g.,
type, size, thickness, direction, R-factor, etc).
[0368] Emissions component 324 may be used to query emissions
regulatory agencies 162 for emissions information 164 with respect
to any emissions market in a certain geographic region. For
example, emissions component 324 processes emissions cap
information, cost information for buying emissions credits, and/or
price information for selling emissions credits for the geographic
region of a certain customer site 120.
[0369] Optimization case 310 also includes defaults data 330,
forecasts data 332, constraints data 334, and readings data 336.
For each individual energy asset 126 of each customer site 120 a
set of default settings is established, which is defaults data 330.
For example, there is a set default settings for a certain HVAC
unit, another set default settings for a certain chiller, another
set default settings for a certain heater, and so on; all included
in defaults data 330. Defaults data 330 may be considered static
data. This is because the default settings remain substantially the
same from day to day for a given energy asset.
[0370] For each individual energy asset 126 of each customer site
120 there is also a set of forecast settings, which is forecasts
data 332. That is, forecasts data 332 includes forecast operating
values for each individual energy asset 126. The forecasts data 332
is set up by the system operator 116. The forecasts data 332 may
initially include default data and/or historical data. A system
operator 116 may modify the initial contents of forecasts data 332
based on any current conditions. Forecasts data 332 may include a
schedule, such as forecast data for every 15, 30, 45, or 60 minutes
for a chosen period of time. Forecasts data 332 may be considered
time series data. This is because the data may change over a time
period.
[0371] In one example, the forecast values in forecasts data 332
are used to modify the default values in defaults data 330 and,
thereby, achieve improved optimization with respect to reducing
energy costs and/or generating revenue from the day-ahead and/or
real-time energy markets. The forecast values in forecasts data 332
may cover the whole day or any portion of the day. For example,
forecast values may be used between noon and 6 pm and the default
values may be used for the rest of the day. In the optimization
process performed by optimizer 214, a first pass of the process may
be to optimize using the default settings in defaults data 330.
Then a second pass of the process may be to optimize using the
forecast settings in forecasts data 332.
[0372] Constraints data 334 may include any information for
constraining the operation and/or use of energy assets 126 of a
certain customer site 120. One example of constraints may be any
constraints that are on a particular energy asset 126, such as
minimum run time or startup time (e.g., ice making) Another example
of constraints may be constraints about the availability of a
certain energy asset 126, such as information from the customer
that a chiller is going to be down between 2 pm and 4 pm or that
the chiller is running at only 50% capacity. Yet another example of
constraints may be the allowable minimum and maximum internal
temperatures of buildings.
[0373] Readings data 336 are the actual readings from the
customer's monitoring and control system 122. For example, readings
data 336 may be meter readings, thermostat readings, any energy
assets readings. When creating a case, system operators 116 may
pull any useful readings from readings data 336 and use these
values as a baseline value into the optimizer. Further, system
operators 116 may monitor actual real-time readings. Then based on
actual readings from readings data 336, system operators 116 may
make certain adjustments to any energy asset 126 and then rerun the
optimization. Additionally, meter readings in readings data 336 may
be used for parametric estimation.
[0374] Schedule builder module 212 may also include a case modeling
and simulation component 340 for processing any information about
buildings and/or energy assets of a customer site 120 and then
models and simulates the environment. That is, case modeling and
simulation component 340 is used to simulate a model of energy
assets 126 and their operation in a given environment over a chosen
period of time given certain input information and/or variables.
For example, case modeling and simulation component 340 may include
a building input 342 for receiving any type of building information
(e.g., location, size, mass, # of floors, type and thickness of
building materials, R-factor, etc) and/or building zones
information (e.g., zone 1=floor 1, zone 2=floor 2, zone 3=floor 3,
etc). Additionally, case modeling and simulation component 340 may
include an energy assets input 344 for receiving any type of
information about energy assets 126, such as, but not limited to,
any operating specifications and/or attributes of, for example,
HVAC assets, chillers assets, heaters assets, energy storage assets
(i.e., thermal and electric storage), energy generation assets,
and/or renewable energy assets.
[0375] The aforementioned information about energy assets 126 may
originate from a customer (i.e., customer site 120). That is, the
attributes and/or technical specifications of each energy asset 126
may be supplied by the customer site 120 and initially entered
manually. However, in other examples, a simulation components
library of predefined assets may exist that provides a simulation
model of any types, brands, and/or models of energy assets. In this
example, the customer may supply only the types, brands, and/or
models of its energy assets and then case modeling and simulation
component 340 may pull the information from the simulation
components library when building an optimization case 310. In one
example, the simulation components library includes
industry-standard XML representations of any types, brands, and/or
models of energy assets 126.
[0376] Using the aforementioned information and/or variables, case
modeling and simulation component 340 creates a model of the
customer site 120 (e.g., a building or group of buildings per
location component 314 and associated energy assets 126) and
simulates the environment at the customer site 120 for a chosen
period of time. Schedule builder module 212 generates a case
snapshot file 350 that contains a snapshot of the simulation
results from case modeling and simulation component 340 and all
other information collected by and/or included in optimization case
310. Case snapshot file 350 is fed into optimizer 214. Optimizer
214 uses a two step process to process the information in case
snapshot file 350 and generate a solution set in the form of an
optimized schedule 352. The optimized schedule 352 is for a chosen
period of time, such as one 24-hour period (i.e., one calendar
day), and includes settings information on a predetermined
interval, such as every 15, 30, 45, or 60 minutes. The optimized
schedule 352 from optimizer 214 is returned to schedule builder
module 212. Schedule builder module 212 may then deploy the
optimized schedule 352 to a customer site 120.
[0377] Following is a description illustrate how the operation of
any of the energy assets described herein can be implemented in
different markets.
[0378] Dynamic Virtualization
[0379] Dynamic virtualization is an integrated solution for energy
generation and storage involving energy assets, such as batteries
and solar generators. This uses a version of examples with virtual
partitioning of an energy storage asset. Dynamic virtualization can
be used to co-optimize energy storage assets and solar generation
across different energy markets or other uses. These markets or
uses may include (1) electric energy provided over the grid to the
energy market, and (2) the ancillary services market (which may
include regulation, which is focused on regulation of power
frequency and voltage on the grid) or (3) use of the storage device
to maintain power quality at the owners' facilities.
[0380] Dynamic virtualization uses examples of systems with the
virtual partitioning of the battery or other type of energy storage
asset into virtual separate batteries, each virtual energy storage
asset being allocated to separate markets or functions, such as
participating in the energy market, and the ancillary services
(regulation) market or use to maintain power quality at the
premise. The virtual partition of the batteries is not physical,
but is instead an allocation of energy storage asset capacity to
various markets or uses. This virtual partition by allocation is
dynamic in that it can be constantly changed in response to
changing price points and performance requirements during the
day.
[0381] There are rapid swings in load on the spot electric energy
market. In order to maintain electrical balance on the grid and
regulate consistent power and voltage on the grid over short
periods of time, for example, over periods of four seconds, fifteen
seconds, or one minute, the grid operator sends out signals to
change generation to match the load changes. Batteries are
particularly well suited to respond to these short response time
signals.
[0382] With examples of the principles herein, energy storage
assets such as batteries can be applied to swing between the
markets for energy and ancillary services for regulation of the
grid or for the maintenance of power quality at the energy storage
asset owner's facility. In the past, batteries were not purchased
and installed for the purpose of providing regulation services,
because batteries tend to be too expensive for this purpose alone.
Most regulation services now come from gas powered generators
providing about 1-10 megawatts, and these energy assets take time
to turn on and off. Industrial batteries, however, are instant on
and off and usually provide power in the 1 megawatt range--and can
respond to grid operator signals in milliseconds.
[0383] In the past, energy storage and energy storage asset
facilities were usually purchased with the intent to provide backup
power for the owners, in case the electric power grid goes down or
temporarily provides inadequate power. However, once the battery or
other type of energy storage assets are installed to satisfy backup
capacity for the owner, they may also to some extent be active in
the regulation market to regulate the power and voltage on the
grid, and in the energy market, to sell power into the grid in
response to real-time pricing changes (or to cut the user's demand
on the grid). For example, energy storage assets may discharge to
the grid during high LMP price hours.
[0384] Energy storage assets may include batteries, ice units,
compressed air, or other technologies to store energy on site by
users and generators of power. Batteries may be of any type,
including lithium ion, lead acid, flow batteries, dry cell
batteries, or otherwise.
[0385] Solar generators of power may include solar panels, solar
cells, any other photovoltaic power generator, or any means for
generating power from sunlight. This may also include generation of
electricity from steam or similar use of liquid to gas phase
generation from sunlight, to generate electricity.
[0386] The energy market involves generating power, distributing
power into the grid, and drawing power out of the grid, each at a
price. This is measured in terms of megawatt hours that are the
amount of power delivered. Energy is delivered for sustained
periods of time, such as for 15 minutes or more.
[0387] The capacity market is measured in terms of megawatts of
capacity. In this market, a seller makes their facilities available
to generate electricity when needed and holds them in reserve for
that purpose, but may never actually distribute energy into the
grid rather than just be on-call. This, in effect, pays the seller
to be available and impacts the reliability of the grid.
[0388] The ancillary market includes regulation of frequency and
voltage in the grid, and the provision of an operating reserve. The
regulation of the voltage in the grid involves discharging energy
into the grid or absorbing energy from the grid in small
increments, frequently, for short periods of time, and very
rapidly.
[0389] Smart grid services increasingly rely on new technologies
such as renewable energy and large-scale storage resources.
Unfortunately, the life-cycle costs associated with such resources,
when taken individually, are still high compared with more
traditional forms of energy production. In addition, the desired
proliferation of distributed and renewable resources on the power
grid introduces new threats to its reliable operation, as they are
subject to unpredictable drops in output, such as when the wind
stops blowing. Consequently, both economic and reliability issues
introduce substantial obstacles to a high penetration of those
technologies in the power grid.
[0390] By themselves, storage resources such as electrical
batteries are presently high cost options. Likewise, photovoltaic
generation and wind turbines are comparatively quite expensive and
their intermittency creates new strains on the power grid.
[0391] However, when optimally managed by various examples
disclosed herein to provide timely support to the power grid, the
net cost of electrical storage can be substantially reduced, as the
result of payments by the grid operator (ISO/RTO) provides for
facilities that can be called on to provide such support. Also,
combining energy storage with intermittent generation makes
technologies such as wind and solar more predictable on the grid,
and hence, more valuable.
[0392] Examples, including dynamic virtualization, can dramatically
improve the economics of renewable generation and storage
technologies, by co-optimizing their operation to participate in
the various energy and ancillary services (including regulation)
markets and thus maximize their economic benefits.
[0393] Examples focus on the economics of batteries and energy
storage and, by providing energy resource optimization and a
gateway to the wholesale markets, can help facility managers deploy
a comprehensive energy storage solution that can cost-effectively
meet an organization's business objectives.
[0394] More broadly, when optimally coupling energy storage with
renewable generation, various examples redefine the economics of
such resources, while providing firm, dispatchable virtual
generation that supports the reliability objectives of the power
grid. Thus, by integrating distributed resources into virtual
generation via system operator dispatch, examples can help enable
the acceleration of renewable energy generation technologies such
as solar and wind.
[0395] Systems Including Energy Storage Assets
[0396] Large-scale storage is widely seen as a necessary piece of
the smart grid and a key component of America's electricity future.
This recognition is driven by the following factors: (1) the
growing adoption of intermittent renewable power sources; (2) state
and nationwide budget shortfalls, leading local governments to seek
cost-effective solutions for maintaining America's aging
infrastructure; and (3) the widespread belief that electric
vehicles ("EVs") will materially grow their market share over the
next 5 to 15 years.
[0397] In this context, stakeholders have been looking for ways to
accelerate the development and implementation of grid-level
storage. Effective battery and other energy storage asset solutions
can take unpredictable energy resources and turn them into reliable
power, while matching electricity supply to demand; they play a
crucial role in fostering microgrids and distributed generation,
viable alternatives to expanding the U.S.'s power infrastructure;
and they can address the new and unique concerns created by EVs,
such as helping to maintain grid stability and giving utilities and
grids more control over energy dispatch.
[0398] A key concern with batteries has long been their high
upfront cost and long payback periods. Various examples address
this by providing battery-owners a robust gateway to the wholesale
electricity markets, thus unlocking new streams of revenues that
increase their return on investment. This may also apply to other
types of energy storage assets.
[0399] Various examples provide processor-executable instructions
(including software solutions) that optimizes participation in
wholesale markets by providing energy storage asset owners with
dynamic virtualization, a service that continuously re-partitions
the energy storage asset for different markets and uses, chiefly
real-time energy, and regulation, and power quality control, in an
optimized manner, based on pricing and weather data, retail
electricity rates, and characteristics of the energy storage asset
and its host site.
[0400] For large retailers and supermarkets, backup generation is a
necessary but often expensive proposition. The nation's largest big
box chains have taken a variety of approaches to minimizing the
costs of providing substitute power in the case of an emergency or
brownout; but for many stores, their only choice to date has been
inefficient and costly diesel generators.
[0401] Examples with dynamic virtualization optimally manage an
energy storage asset's state of charge based on the revenue
producing opportunities in the wholesale market, as well as the
organization's business objectives, such as providing backup power
to critical loads for a given period of time. Thus, when paired
with these examples, the energy storage asset becomes an energy
resource that will concurrently: (1) participate in the energy
markets by providing a way to shift the net load of a facility from
high- to low-price periods; (2) participate in the frequency
regulation market by responding to real-time signals from the grid
operator; (3) participate in other wholesale markets, such as
energy and synchronized reserve; and (4) provide reactive/voltage
support to the microgrid/distribution grid.
[0402] Examples enable the energy storage asset to maximize
revenues from the various wholesale markets, while maintaining its
ability to achieve its main objective of providing a reliability
service to the organization. To achieve this, examples herein
describe virtualization of the energy storage asset and creating
dynamic "energy storage asset partitions," in a manner similar to
the way computing resources are virtualized. Through its
optimization capability, an example determines in hourly increments
which portion of the controller output (including its capacity),
and hence the energy storage asset capacity (including its SOC),
can be allocated to the energy and regulation markets respectively,
while maintaining sufficient reserve to meet the forecasted backup
requirements. The optimal control (to perform the optimization
described herein) can take into account the forecasted and
real-time hourly prices for each of the markets, along with the
time and weather dependent backup requirements of the facility.
When combined with other resources such as renewable generation,
backup generation or demand response, the examples described herein
can extract the maximum value of all such resources while meeting
the organization's reliability, comfort, and sustainability
objectives.
[0403] In energy markets, ancillary services support the reliable
operation of the transmission system as it moves electricity from
generating sources to retail customers. Examples of ancillary
services include "Synchronized Reserve" and "Regulation."
Synchronized Reserve supplies electricity if the grid has an
unexpected need for more power on short notice. Regulation is a
service that corrects for short-term changes in electricity use
that might affect the stability of the power system. An entity that
is participating in the Regulation service must be able to respond
rapidly (within a few seconds or minutes) to a "regulation"
signal.
[0404] The different types of energy assets available at a customer
site can determine the types of energy markets in which the
customer site may participate (e.g., capacity market, energy
market, or synchronized reserve market). For example, the capacity
of a backup generator, battery and HVAC can be committed for
economic demand response or a capacity market, according to any of
the principles described herein. In another example, the capacity
of a battery or a computing load management system can be committed
to a regulation market, according to any of the principles
described herein. As another example, the capacity of a backup
generator and a battery can be committed for a demand response,
according to any of the principles described herein. As yet another
example, the capacity of a battery and a HVAC can be committed for
power quality, according to any of the principles described
herein.
[0405] Following is a description of the different types of
markets, including energy markets and regulation markets, to
illustrate how the operation of any of the energy assets described
herein can be implemented in each market.
[0406] Regulation Market
[0407] In a non-limiting example, capacity of the energy storage
asset may be committed to the regulation market to maintain the
frequency and/or voltage on the power line. For example, system
operators seek to maintain the system frequency at very near to a
nominal frequency of around 60 Hz in the U.S. or around 50 Hz in
some other countries (including countries in the European Union).
If the frequency is too high, there is too much power being
generated in relation to load. A system operator would send a
signal to participants in the regulation market to increase their
load, or ask for generation to be reduced, to keep the system in
balance. If the frequency is too low, then there is too much load
in the system, and the system operator would send a signal asking
for generation to be increased or the load reduced. A grid operator
may use a real-time communication signal to call for either a
positive correction (referred to in the industry as "regulation
up") or negative correction (referred to as regulation down"). If
load exceeds generation, the frequency and voltage tend to drop.
The ISO/RTO system operator would relay a signal requesting
regulation up. If, however, generation exceeds load, the frequency
tends to increase. The ISO/RTO system operator would relay a signal
requesting regulation down (including asking for reduced
generation).
[0408] The regulation market may seek commitment of a system on an
hourly basis. However, the ISO/RTO system operator may relay
regulation signals for regulation up and/or regulation down at much
shorter timescales. For example, during the commitment period, the
adjustments of regulation may take place minute-by-minute, on the
order of a minute or a few minutes, or on the order of a few
seconds (e.g., at 2-second or 4-second intervals). Traditional
regulation applies to slower responding energy storage assets
(e.g., assets with about 5 minutes response time), such as but not
limited to chillers. Faster responding energy storage assets, such
as but not limited to batteries, can respond within about 2
seconds. In an example, the objective cost function may include a
term to performance incentives offered for fast responding energy
storage assets. To participate in the regulation market, a resource
may receive and may need to respond to a regulation signal
generated by the grid operator approximately every 2 seconds. (In
some territories, this rule may be relaxed somewhat for batteries.)
The energy storage asset responds to this signal with a percentage
of its maximum resource capability that is bid into the regulation
market. Examples receive and respond to this signal and distribute
it among the various resources participating in the regulation
market within a given price zone, based on the results produced by
an optimizer
[0409] If the ISO/RTO system operator sizes the regulation signals
to adequately balance the signal in the long run, the charge of the
energy storage asset may merely fluctuate around its initial state
of charge when it started to provide regulation. That is, the
proportion of the available state of charge of the energy storage
asset that is committed for use to provide regulation may be
delivered at variable charge rates or discharge rates. Adequately
balanced regulation signals should neither completely deplete nor
fill the energy storage asset.
[0410] In a non-limiting example, the regulation price may be set
at average values of around $30-$45/MW per hour, with hourly rates
fluctuating around this average value. Some regulation markets may
pay simply for the commitment of an available capacity of the
energy storage asset during a time period, such as for an hour,
with a separate payment for the total amount of energy ultimately
provided. Thus, payment at the regulation price may be made for the
period of commitment, even if the system is not called upon to
provide regulation during the commitment period.
[0411] There may also be additional payment from the energy market
for energy generated, based on the wholesale electricity market
price (the LMP).
[0412] Operating characteristics of the energy storage asset
include power (or its instantaneous delivery capability in kW) and
the energy stored in the energy storage asset (or the amount of
power it can generate over one hour, or kWh). In a non-limiting
example, a battery rated at 1.5 MW power and 1.0 MWh energy storage
capacity will be able to provide 1.5 MW power for a total period of
40 minutes (60.times.1/1.5). Thus, if the owner bids 1.5 MW into
the regulation market for a given hour, a 50% discharge signal over
2 seconds could decrease the battery's charge level by 0.8 kWh (1.5
MW.times.1/1800 hrs).
[0413] As part of a certification for participating in the
regulation market, the ISO/RTO system operator may verify that the
energy storage asset is capable of responding to the regulation bid
into the market. The ISO/RTO system operator may require that the
energy storage asset be able to be charged/discharged at its full
enrolled amount, when receiving a +/-100% regulation signal within
a duration of 10 minutes. In the 1.5 MW example above, the battery
charge would be increased/decreased by +/-250 kWh (1.5 MW.times.1/6
hr).
[0414] For example, assuming that the energy storage asset starts
with an initial state of charge of 50% at time t=0. Ideally, the
regulation signal is "net zero," meaning that the quantity of
charged/discharged energy averages to zero over a given 24-hour
period. In reality, the state of charge of the energy storage asset
may at times drift to the limits of the energy storage asset's
recommended state of charge. If the state of charge exceeds some
adjustable maximum or minimum values, various examples include
compensating by exiting the regulation market for the next hour and
bringing the energy storage asset back to its initial
set-point.
[0415] In an example, the operating schedule that is generated
according to an implementation of an apparatus herein specifies
intervals of time when the energy storage asset may be committed to
the regulation market. During these time periods, the operating
schedule may additionally indicate the points during these
intervals of time where energy may be bought to charge the energy
storage asset if its state of charge falls below a desirable limit,
or where excess energy may be sold if the state of charge is too
high. This discharge can contribute to a short-term demand response
action in the real-time energy market.
[0416] Energy Market
[0417] To participate in the energy market, the energy storage
asset should to be able to provide the "as bid" energy into the
real-time market for the next hour. Various examples compute the
optimal charge or discharge signal in anticipation of or in
response to the economic signals, while maintaining minimum and
maximum constraints on the state of charge of the energy storage
asset. When combined with other controllable resources, such as
renewable generation or advanced lighting and HVAC systems,
examples extract the maximum economic value of each resource, given
external factors and constraints. For example, examples can use an
energy storage asset to compensate for the intermittency of
renewable generation, and can include demand response actions to
help maintain the balance.
[0418] FIG. 26 shows an example energy storage asset optimization
in response to economic signals and performance needs. The
horizontal axis is time over a 24 hour cycle. The left vertical
axis is megawatt hours. The right vertical axis shows price in
dollars per megawatt hours. The volume under the line battery 810
shows the stored capacity in the battery. The three lines below the
horizontal axis shows the discharge 820 from the battery. The seven
vertical lines 830 above the horizontal axis shows charging to the
battery 830. The line 840 shows the LMP energy price throughout the
24-hour cycle to which indicated energy assets are responding. In
this example, examples determine the optimized hourly charge and
discharge schedule of a 1.5 MW/1.0 MWh battery in response to an
LMP price signal. The optimization is further constrained to
maintain a 200 kWh minimum capacity for backup purposes, and a
maximum capacity of 800 kWh to maintain charge/discharge cycle
efficiency.
[0419] Spinning Reserve Market
[0420] To participate in the spinning reserve market, the energy
asset should to be able to commit building asset resources to
provide power during unplanned outages of base load generators.
Spinning reserve is generation capability that can provide power to
the grid immediately when called upon by the ISO/RTO and reach full
capacity within 10 minutes. The energy storage asset included in
the building asset needs to be electrically synchronized with the
grid, e.g., through the controller, to participate in this market.
Revenue in the spinning reserve market is for capacity rather than
energy. It requires quick response but makes low total energy
demand. Requests in the spinning reserve market may be made around
20-50 times per year.
[0421] Revenue for the spinning reserve market may be determined
based on the ability of an energy storage asset to provide power
during an unplanned event, such as a generator failure. Revenue may
also be derived based on the amount of energy (MWh) that is
generated during active participation in the spinning reserve
market, such as based on the electricity wholesale price.
[0422] Market Based on Voltage/VAR Ancillary Service
[0423] To participate in a market based on a voltage/VAR ancillary
service, certain resources of the energy asset may be committed to
provide for voltage control and/or VAR control.
[0424] The voltage/VAR ancillary service seeks to maintain
reliability and power quality. It may appear at the microgrid level
or feeder level of a distribution system.
[0425] A voltage control ancillary service assists in maintaining
system voltages within an acceptable range (120 volts.+-.about 5%
or 220 volts.+-.about 5%) to customers served by a feeder. For
example, if the supply line voltage fluctuates by some amount,
resources of the energy asset may be committed to adjust the
distribution primary voltage so that the distribution primary
voltage also does not drift out of the acceptable range. In another
example, if the current (ampere) flowing on the feeder increases
during peak load conditions, the voltage along the feeder may
decrease due to an increase in current flow, resulting in decreased
voltage for customers that are further from the substation end of
the feeder. Here, resources of the energy asset may be committed to
raise the line voltage under peak load conditions to account for
any increased voltage drop. If instead the feeder is lightly
loaded, the voltage drop may be lower, and resources of the
building asset may be committed to lower the voltage to avoid
possible high voltage conditions.
[0426] VAR refers to the reactive power (measured in volt-ampere
reactive (VARs)). VAR is the electrical energy that energizes
capacitive components and inductive components in a power system. A
non-limiting example of a capacitive component is overhead
conductors, which are continuously charged and discharged by an
alternating current (AC) waveform. Non-limiting examples of
inductive components are electric motors and transformers, which
can store energy in magnetic fields that are used for device
operation. By reducing the amount of VARs flowing on the
distribution feeder, an electricity supplier can reduce electrical
losses and improve the voltage profile along the feeder. Where
reactive power varies throughout the day, the capacitive components
of a energy asset that are equipped with switches can be placed in
or out of service as needs vary during the day. These capacitive
components of the energy asset may be equipped with controllers. A
system, apparatus, or method may be used to determine when to
switch the switches on or off. For example, when the voltage at the
location of the capacitive component is low, the operating schedule
determined according to a principle herein may include instructions
for the controller to close the switch to place the capacitive
component in service. When the voltage is high, the operating
schedule may include instructions for the controller to open the
switch to remove the capacitive component from service.
[0427] Revenue from a market based on the voltage/VAR ancillary
service may be determined based on the ability of an energy storage
asset of the energy asset(s) to be used to provide the voltage
controls and/or the VAR controls. In an example, the voltage/VAR
control may apply in a microgrid application at the microgrid bus
level, which may introduce a reliability cost to the computation of
the net-energy-related cost.
[0428] Co-Optimization Across Multiple Markets and/or Ancillary
Services
[0429] As described above, the economic signal can be a driver for
the average charge status of the energy storage asset. It responds
to price signals that are averaged on an hourly basis. The
regulation signal can be seen as having a "bias" effect over the
average charge, in response to the regulation commands. Examples
co-optimize the energy storage asset charge by first economically
optimizing the charge status of the energy storage asset, then
allocating the balance of the available power to the regulation
market, on an hourly basis.
[0430] By adding user-adjustable upper and lower constraints to the
optimized energy storage asset charge, examples take into account
reliability objectives (e.g. backup) and charge/discharge cycle
efficiency. Other constraints can be added, based on the type of
energy storage asset technology used, to maximize charge/discharge
round trip efficiency, and optimize energy storage asset life
versus energy storage asset replacement costs.
[0431] In addition to co-optimizing a storage resource at a given
location, examples have the capability to perform a global
optimization across multiple customers within the same price zone,
and disaggregate the regulation and economic signals among the
various customers. In particular, this gives customers that do not
have the minimum energy storage asset capacity required the ability
to participate in the regulation market.
[0432] Co-Optimization with Other Distributed Resources
[0433] With various examples, distributed resources can earn
maximum economic benefit through co-optimization. Co-optimization
of various resources on one site results in accelerated payback for
all assets, and this, in turn, accelerates the market-wide
penetration of these resources.
[0434] FIG. 27 shows an example generation schedule for
battery-photovoltaic co-optimization. FIG. 27 shows an example
where the same battery used in the previous example in FIG. 26 is
combined with 0.5 MW of PV (solar-photovoltaic) generation. The
horizontal axis shows the time in the 24-hour cycle. The left
vertical axis shows megawatt hours. The right vertical axis shows
price in dollars per megawatt hours. The load 910 is the electric
load on the facilities. The import of power 920 shows the power
imported into the facilities from the grid. The battery 930 shows
the three bars below the horizontal axis for the power discharge
from the batteries at specific times. The diesel 940 is not shown
because diesel generation is not used in this co-optimization
because of its relative price. The solar 950 shows the power used
by the system and/or stored in the batteries from the solar
generator or photovoltaic generator at various times. The LMP line
960 shows the fluctuating price for electricity during the 24-hour
cycle.
[0435] Example Energy Storage Assets
[0436] Various examples are technology agnostic and can optimize
any storage installation. However, certain forms of storage, such
as compressed air and ice storage, are currently not recognized as
applicable resources for some regulation markets.
[0437] Aided by significant private investment, grid-scale
batteries have significantly reduced in cost over the past decade.
Different technologies appear to have converged around a similar
price: with batteries offered at roughly $1-2 per Watt, and $1-2
per Watt-hour, before Balance of Plant ("BoP") costs. (Watts [W,
kW, MW] are a measure of power, i.e., the charge and discharge rate
of an energy storage asset. Watt-hours [Wh, kWh, MWh] are a measure
of energy, i.e., the storage capacity of an energy storage asset.)
At these prices, energy storage asset owners and lessees can use
examples to achieve a positive return over the installed life while
meeting their sites' backup needs.
[0438] Below is a brief overview of each different types of energy
storage assets:
[0439] Lithium-Ion Battery
[0440] This "power battery" is well-suited for regulation with high
efficiency and hybrid opportunities. However, it has a high cost
and little data exists to corroborate lifespan claims
[0441] Quoted prices include $2 million for a 1 MW/1 MWh unit, and
$1.5 million for a 1 MW/250 kWh unit.
[0442] Lithium-Ion (Li-Ion) batteries are receiving great attention
because they are the preferred battery for electric vehicles.
Presently, Li-Ion batteries are among the most expensive of the
storage options available. This may change, as many companies are
pouring resources into new Li-Ion variants; however, some suggest
that the chemical characteristics of Li-Ion cells make it difficult
to significantly reduce their cost. Additionally, Li-Ion is a new
technology so that no company has empirically demonstrated Li-Ion's
lifespan. Companies have tried to allay these concerns through
"accelerated testing" that charge/discharge the battery more
rapidly, but this does not provide full insight into how well
Li-Ion batteries perform over time.
[0443] Li-Ion batteries are very dense and therefore very small
compared to other technologies. One manufacturer's 1 MW/1 MWh unit,
for example, has dimensions of 8'.times.20'. In comparison, a
quoted lead-acid unit with similar specs has dimensions of
40'.times.70'.
[0444] Hybrid opportunities for Li-Ion batteries are discussed in
the flow battery section.
[0445] Lead-Acid Battery
[0446] This battery is the lowest-cost option with long lifespan
and proven technology. However, it is physically large with high
maintenance and limited depth of discharge.
[0447] Quoted prices include $896,000 for a 1 MW/2 MWh unit, and
$512,000 for a 1 MW/500 kWh unit.
[0448] Lead-Acid batteries, which have the same chemistry as a car
battery, are proven for long-lasting grid applications. One
manufacturer's 1 MW/1.4 MWh unit lasted for 12 years, from
1996-2008, as both a provider of voltage support and a backup power
source, before the battery cells were replaced. The original power
electronics of that installation still function, and the unit is
running with a new set of lead-acid cells.
[0449] A downside of lead-acid batteries is that they are very
heavy and very large. This is why they are not being considered as
much for EVs, and this poses other logistical challenges for
metropolitan installations. Lead-acid batteries are also considered
to be high maintenance. They need to be kept within a narrow
temperature range, and therefore require their own building (for
industrial power uses), as well as periodic upkeep. Also, lead-acid
batteries are typically oversized because exceeding the lower
bounds of their state of charge can damage the cells. They are best
for regulation or voltage support, and as backup if sized
explicitly for that purpose.
[0450] Flow Batteries
[0451] These batteries can be fully charged and discharged without
damage to the battery. Also, "hybridization" is possible. However,
this "energy battery" limits regulation market opportunities and
has low round-trip efficiency.
[0452] Quoted prices include $1.15 million for a 1 MW/1 MWh
battery.
[0453] Flow batteries are energy batteries, i.e., they are best
suited for backup electricity, but their chemistry limits their
ability to provide high-MW regulation. The typically configured
flow battery takes 4 hours to charge/discharge, and flow batteries
have lower round-trip efficiencies than other types (roughly 75% in
contrast to Li-Ion's 90%). With flow batteries, a tank is filled
with electrolyte fluid that flows through solid cell stacks located
at the top of the unit. The liquid solution never degrades, but the
cells need to be replaced every 5 or 6 years. The cost of cell
replacement is 10-15% of the total unit.
[0454] The electrochemical characteristics prohibit them from
power-dense applications, unless they are oversized and paired with
a large inverter, or "hybridized" with another battery technology.
Hybridization can be provided by some suppliers in conjunction with
a well-established power electronics provider. One manufacturer has
created a system that allows its "energy" batteries to be paired
with "power" batteries, like lithium-ion, connected through a
single inverter. A leading lithium-ion battery manufacturer
recently announced a plan to provide a similar Li-Ion/flow battery
unit for grid-scale applications.
[0455] Dry Cell Technology
[0456] This power battery is good for the regulation market.
However, it has very small recommended depth of charge/discharge
and is expensive.
[0457] Quoted prices include $1.5 million for a 1.5 MW/1 MWh
battery, plus 30% extra for BoP ("Balance of Plant").
[0458] These batteries provide high power-to-energy ratios that
make them attractive for regulation, so long as they remain within
a fairly narrow range of state of charge. These batteries are not
meant to fully charge or discharge and pushing their recommended
operating parameters affects their lifespan. Ideal state of charge
is 20-80%. Because of these constraints, these batteries would need
to be oversized to provide backup. These batteries are more
expensive than cheaper options such as lead-acid.
[0459] Based on their characteristics, these batteries are likely
suited for projects whose primary objective is not backup power,
but rather systems support. They provide high-MW regulation, can
address voltage sag concerns, and can be recharged by regenerative
braking. However, when their state of charge limitations are taken
into account, they appear to be a costly technology, even in
comparison to lithium-ion.
[0460] Ice Units
[0461] The thermal storage capacity of an ice unit can be used
according to the principles herein as an energy storage asset.
[0462] Ice units can be used to modify how a building asset is
cooled, including how energy is consumed for cooling/air
conditioning. An ice unit generally consists of a
thermally-insulated storage tank that attaches to a building
asset's air-conditioning system. The unit makes ice (generally at
night when supply costs tend to be lower) and uses that ice during
the day to deliver cooling directly to the building asset's
existing air conditioning system. Storage tanks can be on the order
of hundreds of gallons of water (e.g., about 450 gallons) of water.
The water is frozen by circulating refrigerant through copper coils
within or surrounding the tank. The condensing unit then turns off,
and the ice is stored until its cooling energy is needed. During
the higher temperature daytime hours, the power consumption of air
conditioning and demand levels on the grid, increase. The ice unit
may be used to replaces the energy-demanding compressor of a
building asset's air conditioning unit. The melting ice of the ice
unit, rather than the air conditioning unit, can be piped around
the building asset to cool it.
[0463] Compressed Air
[0464] The storage capacity of compressed air can be used according
to the principles herein as an energy storage asset.
[0465] For example, compressed air energy storage (CAES) technology
provides a way to store compressed air, using energy generated at
lower cost at one time, and use that compressed air at another time
when energy costs are higher. For example, energy generated during
periods of low energy demand periods (such as during off-peak
electricity usage as night) may be released at on-peak times to
meet higher demand. The CAES system may be located where there is
large, accessible air-storage pockets or caverns, such as but not
limited to mines and underground formations. The air may be
compressed using electrically powered turbo-compressors. The
compressed air stored in these pockets may be later fed to, e.g.,
gas-fired turbine generators to generate electricity during
on-peak, higher-priced time periods. In another example, the
compressed air is expanded using turbo expanders or air engines
that are driving electrical generators to generate electricity.
[0466] In another example, the thermal storage capacity of
compressed air can be used according to the principles herein as an
energy storage asset.
[0467] Using a heat exchanger, it is possible to extract waste heat
from the lubricant coolers used in types of compressors, and use
the waste heat to produce hot water. Depending on its design, a
heat exchanger can produce non-potable or potable water. When hot
water is not required, the lubricant can be routed to the standard
components for lubricant cooling. The hot water can be used in
central heating or boiler systems, or any other application where
hot water is required. Heat exchangers also offer an opportunity to
produce hot air and hot water, and allow the operator some
flexibility to vary the hot air to hot water ratio.
[0468] Controller for an Energy Storage Asset
[0469] The controllers for the energy storage assets described
herein can be used to vary the input to or output from the energy
storage assets. When the controller functions as a converter, it
converts the AC signal to a DC signal. That DC signal may be used
to charge the energy storage asset. When the controller functions
as an inverter, it converts one type of voltage (direct current
(DC)) into another type of voltage (alternating current (AC)).
Since the electricity supplier generally supplies 110 or 220 volts
AC on the grid, the conversion may typically be from 12 volts DC to
110 or 220 volts AC. In another example, the output of the
controller may be different, depending on the type of load on the
system. Inverters called utility intertie or grid tie may connect
to energy generating assets such as solar panels or wind generator,
and can feed their output directly into the inverter. The inverter
output can be tied to the grid power.
[0470] In a non-limiting example, the inverter takes the DC output
from the energy storage asset and runs it into a number of power
switching transistors. These transistors are switched on and off to
feed opposite sides of a transformer, causing the transformer to
think it is getting an AC signal. Depending on the quality and
complexity of the inverter, it may put out a square wave, a
"quasi-sine" (sometimes called modified sine) wave, or a true sine
wave. The quality of the quasi-sine wave can vary among different
inverters, and also may vary somewhat with the load.
[0471] The virtual partitioning of the energy storage asset
described facilitates partitioning between energy and regulation
participation. The partitioning can be based on the available
capacity of the controller (i.e., the inverter/converter). The SOC
of the energy storage asset may be used to provide a constraint
within the optimization for determining the optimal
charge/discharge strategy for participation in these two different
markets. As a non-limiting example, an operating schedule generated
according to the principles herein can indicate the optimal
charge/discharge strategy for the controller, including on an
hourly basis, in response to or anticipation of projected LMPs. The
balance of the inverter capacity of the controller may be made
available to the regulation market at its shorter timescales (e.g.,
at the 2-second or minute-by-minute time intervals described
above). The proportion of the controller output (and hence the
energy storage asset) committed to the energy market and the
remaining proportion of the energy storage asset committed to the
regulation market are co-optimized based on the economic benefit
derived from the two markets, and subject to the SOC constraints.
The operating schedules generated based on any of the principles
described herein, and in any of the example, can suggest the
proportion of the controller output committed to the energy market
and to the regulation market in a given time interval t (less than
time period T), and for what length of time. the proportion of the
controller output committed to the energy market and to the
regulation market in a given time interval t (less than time period
T). For example, for a controller with a 1 MWatt inverter capacity,
the principles herein can be used to generate an operating schedule
that suggests the proportion of the controller's 1 MWatt inverter
capacity that can be committed to the energy market and to the
regulation market in a given time interval t to generate the
energy-related revenue.
[0472] Energy Generating Assets
[0473] Examples of energy generating asset applicable to the
apparatus and methods herein include photovoltaic cells, fuel
cells, gas turbines, diesel generators, flywheels, electric
vehicles and wind turbines.
[0474] Electric storage has the potential to address some of the
attributes of renewable energy generation. The intermittent nature
of energy generating assets, including solar generation, may
present some difficulty for grid operators. For example, weather
events can make energy output of energy generating assets,
including photovoltaic cells or wind turbines, difficult to
predict. As renewable generators make up a growing share of
regional generation portfolios, grid operators may require greater
real-time visibility of distributed generation and benefit from a
resource's ability to control bi-directional power flow. Adding
storage to distributed generation achieves new levels of
responsiveness not seen with existing systems.
[0475] According to principles described herein, the operating
schedule generated for a system that includes a controller, an
energy storage asset and an energy generating asset can firm up
intermittent renewable generation into dispatchable generation. The
operating schedule can provide for renewable generation forecasting
based on the forecasted weather conditions.
[0476] Dynamic virtualization can be beneficial to sites that
utilize both energy storage assets and energy generating assets.
For example, by integrating weather data, price forecasts, and
expected site load, examples can accurately predict a solar array's
output, determine how much solar generation should be captured by
an energy storage asset, and dispatch the energy storage asset at
the time of day that optimizes revenues derived from wholesale
market participation.
[0477] By passing energy through an energy storage asset and
exhibiting real-time control, power can be delivered strategically
and act as a price-responsive resource in the various wholesale
markets. In effect, storage allows the maturation of energy
generating assets as a resource that provides discrete power-flow
to the grid that is controllable, quantifiable, and dispatchable.
Solar power and its generation can be costly. Through dynamic
virtualization the value of renewable generation can be increased
by improving the resource with electric storage.
CONCLUSION
[0478] While various inventive embodiments have been described and
illustrated herein, those of ordinary skill in the art will readily
envision a variety of other means and/or structures for performing
the function and/or obtaining the results and/or one or more of the
advantages described herein, and each of such variations and/or
modifications is deemed to be within the scope of the inventive
embodiments described herein. More generally, those skilled in the
art will readily appreciate that all parameters, dimensions,
materials, and configurations described herein are meant to be
exemplary and that the actual parameters, dimensions, materials,
and/or configurations will depend upon the specific application or
applications for which the inventive teachings is/are used. Those
skilled in the art will recognize, or be able to ascertain using no
more than routine experimentation, many equivalents to the specific
inventive embodiments described herein. It is, therefore, to be
understood that the foregoing embodiments are presented by way of
example only and that inventive embodiments may be practiced
otherwise than as specifically described. Inventive embodiments
disclosed herein are directed to each individual feature, system,
article, material, kit, and/or method described herein. In
addition, any combination of two or more such features, systems,
articles, materials, kits, and/or methods, if such features,
systems, articles, materials, kits, and/or methods are not mutually
inconsistent, is included within the inventive scope of the present
disclosure.
[0479] The above-described embodiments of the disclosure can be
implemented in any of numerous ways. For example, some embodiments
may be implemented via one or more controllers, which may employ
hardware, software or a combination thereof. In some embodiments
discussed herein, one or more controllers may be implemented, at
least in part, as a state machine.
[0480] When any aspect of an embodiment is implemented at least in
part in software, the software code can be executed on any suitable
processor or collection of processors, whether provided in a single
device or computer or distributed among multiple
devices/computers.
[0481] In this respect, various aspects of the disclosure, may be
embodied at least in part as a computer readable storage medium (or
multiple computer readable storage media) (e.g., a computer memory,
one or more floppy discs, compact discs, optical discs, magnetic
tapes, flash memories, circuit configurations in Field Programmable
Gate Arrays or other semiconductor devices, or other tangible
computer storage medium or non-transitory medium) encoded with one
or more programs that, when executed on one or more computers or
other processors, perform methods that implement the various
embodiments of the technology discussed above. The computer
readable medium or media can be transportable, such that the
program or programs stored thereon can be loaded onto one or more
different computers or other processors to implement various
aspects of the present technology as discussed above.
[0482] The terms "program" or "software" are used herein in a
generic sense to refer to any type of computer code or set of
computer-executable instructions that can be employed to program a
computer or other processor to implement various aspects of the
present technology as discussed above. Additionally, it should be
appreciated that according to one aspect of this embodiment, one or
more computer programs that when executed perform methods of the
present technology need not reside on a single computer or
processor, but may be distributed in a modular fashion amongst a
number of different computers or processors to implement various
aspects of the present technology.
[0483] Computer-executable instructions may be in many forms, such
as program modules, executed by one or more computers or other
devices. Generally, program modules include routines, programs,
objects, components, data structures, etc. that perform particular
tasks or implement particular abstract data types. Typically the
functionality of the program modules may be combined or distributed
as desired in various embodiments.
[0484] Also, the technology described herein may be embodied as a
method, of which at least one example has been provided. The acts
performed as part of the method may be ordered in any suitable way.
Accordingly, embodiments may be constructed in which acts are
performed in an order different than illustrated, which may include
performing some acts simultaneously, even though shown as
sequential acts in illustrative embodiments.
[0485] All definitions, as defined and used herein, should be
understood to control over dictionary definitions, definitions in
documents incorporated by reference, and/or ordinary meanings of
the defined terms.
[0486] The indefinite articles "a" and "an," as used herein in the
specification, unless clearly indicated to the contrary, should be
understood to mean "at least one."
[0487] The phrase "and/or," as used herein in the specification,
should be understood to mean "either or both" of the elements so
conjoined, i.e., elements that are conjunctively present in some
cases and disjunctively present in other cases. Multiple elements
listed with "and/or" should be construed in the same fashion, i.e.,
"one or more" of the elements so conjoined. Other elements may
optionally be present other than the elements specifically
identified by the "and/or" clause, whether related or unrelated to
those elements specifically identified. Thus, as a non-limiting
example, a reference to "A and/or B", when used in conjunction with
open-ended language such as "comprising" can refer, in one
embodiment, to A only (optionally including elements other than B);
in another embodiment, to B only (optionally including elements
other than A); in yet another embodiment, to both A and B
(optionally including other elements); etc.
[0488] As used herein in the specification, "or" should be
understood to have the same meaning as "and/or" as defined above.
For example, when separating items in a list, "or" or "and/or"
shall be interpreted as being inclusive, i.e., the inclusion of at
least one, but also including more than one, of a number or list of
elements, and, optionally, additional unlisted items. Only terms
clearly indicated to the contrary, such as "only one of" or
"exactly one of," or, when used in claims, "consisting of," will
refer to the inclusion of exactly one element of a number or list
of elements. In general, the term "or" as used herein shall only be
interpreted as indicating exclusive alternatives (i.e. "one or the
other but not both") when preceded by terms of exclusivity, such as
"either," "one of," "only one of," or "exactly one of." "Consisting
essentially of," when used in claims, shall have its ordinary
meaning as used in the field of patent law.
[0489] As used herein in the specification and claims, the phrase
"at least one," in reference to a list of one or more elements,
should be understood to mean at least one element selected from any
one or more of the elements in the list of elements, but not
necessarily including at least one of each and every element
specifically listed within the list of elements and not excluding
any combinations of elements in the list of elements. This
definition also allows that elements may optionally be present
other than the elements specifically identified within the list of
elements to which the phrase "at least one" refers, whether related
or unrelated to those elements specifically identified. Thus, as a
non-limiting example, "at least one of A and B" (or, equivalently,
"at least one of A or B," or, equivalently "at least one of A
and/or B") can refer, in one embodiment, to at least one,
optionally including more than one, A, with no B present (and
optionally including elements other than B); in another embodiment,
to at least one, optionally including more than one, B, with no A
present (and optionally including elements other than A); in yet
another embodiment, to at least one, optionally including more than
one, A, and at least one, optionally including more than one, B
(and optionally including other elements); etc.
[0490] In the specification and claims, all transitional phrases
such as "comprising," "including," "carrying," "having,"
"containing," "involving," "holding," "composed of," and the like
are to be understood to be open-ended, i.e., to mean including but
not limited to. Only the transitional phrases "consisting of" and
"consisting essentially of" shall be closed or semi-closed
transitional phrases, respectively, as set forth in the United
States Patent Office Manual of Patent Examining Procedures, Section
2111.03.
* * * * *