U.S. patent application number 12/751845 was filed with the patent office on 2011-01-06 for systems and methods for electric vehicle grid stabilization.
This patent application is currently assigned to GridPoint, Inc.. Invention is credited to Seth B. Pollack.
Application Number | 20110001356 12/751845 |
Document ID | / |
Family ID | 42982790 |
Filed Date | 2011-01-06 |
United States Patent
Application |
20110001356 |
Kind Code |
A1 |
Pollack; Seth B. |
January 6, 2011 |
SYSTEMS AND METHODS FOR ELECTRIC VEHICLE GRID STABILIZATION
Abstract
A system and methods that enables power flow management using
AGC commands to control power resources. Power regulation can be
apportioned to the power resources. An AGC command requesting an
apportioned amount of the power regulation may be transmitted to a
power resource. The power flow manager can determine a power
regulation range for a power resource, and transmit an AGC command
based on the power regulation range. In addition, a power flow
management system can detect a change in an intermittent power flow
and implement a power flow strategy in response to the change in
the intermittent power flow. The power flow strategy may be a
smoothing strategy or a leveling strategy.
Inventors: |
Pollack; Seth B.; (Seattle,
WA) |
Correspondence
Address: |
GREENBERG TRAURIG, LLP (DC/ORL)
2101 L Street, N.W., Suite 1000
Washington
DC
20037
US
|
Assignee: |
GridPoint, Inc.
Arlington
VA
|
Family ID: |
42982790 |
Appl. No.: |
12/751845 |
Filed: |
March 31, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61165344 |
Mar 31, 2009 |
|
|
|
Current U.S.
Class: |
307/31 |
Current CPC
Class: |
H02J 3/381 20130101;
B60L 11/184 20130101; Y04S 10/126 20130101; B60L 53/63 20190201;
B60L 2240/70 20130101; B60L 53/18 20190201; Y02T 10/7072 20130101;
Y02T 10/72 20130101; Y02T 90/16 20130101; Y02T 90/168 20130101;
Y02T 90/12 20130101; Y02T 90/14 20130101; Y02T 90/167 20130101;
Y02T 10/70 20130101; B60L 55/00 20190201; Y02T 90/169 20130101;
Y04S 30/12 20130101; Y04S 30/14 20130101; B60L 53/68 20190201; B60L
53/64 20190201; B60L 53/665 20190201; Y02E 60/00 20130101; B60L
53/65 20190201; H02J 2300/10 20200101; B60L 53/305 20190201; H02J
7/00 20130101 |
Class at
Publication: |
307/31 |
International
Class: |
H02J 4/00 20060101
H02J004/00 |
Claims
1. A method for managing power flow, comprising the steps of:
controlling a plurality of power resources via Automatic Generation
Control (AGC) commands, wherein the AGC commands are transmitted by
a power flow manager to the plurality of power resources, wherein
the AGC commands request power regulation; apportioning the power
regulation to the plurality of power resources based on an
apportionment scheme; and, transmitting an AGC command to at least
one of the plurality of power resources, wherein the AGC command
requests an apportioned amount of the power regulation from the at
least one of the plurality of power resources.
2. The method of claim 1, wherein the power regulation is frequency
regulation.
3. The method of claim 1, wherein the power regulation is power
generation.
4. The method of claim 1, wherein the power regulation is power
consumption.
5. The method of claim 1, wherein the power regulation is requested
in response to a power surplus event, and wherein the power
regulation requests a decrease in power.
6. The method of claim 1, wherein the power regulation is requested
in response to a power shortage event, and wherein the power
regulation requests an increase in power.
7. The method of claim 1, wherein the power regulation is
bi-directional, wherein the power regulation requests an increase
in power from a first power resource and requests a decrease in
power from a second power resource.
8. The method of claim 1, furthering comprising: setting at least
one of the plurality of power resources to consume or generate at a
maximum rate; and, adjusting power consumption or power generation
for the at least one of the plurality of power resources in
response to the AGC commands, wherein the power consumption is
decreased or the power generation is increased during a power
shortage, wherein the power consumption is increased or the power
generation is decreased during a power surplus.
9. The method of claim 1, wherein the apportionment scheme relates
to factor selected from a group consisting of the following: power
range of each of the plurality of power resources; power range of a
portion of the plurality of power resources; minimization of
communications to the plurality of power resources; fairness to the
plurality of power resources; maximization future abilities to
provide power services by the plurality of power resources;
preferences of the plurality of power resources; or, requirements
of the plurality of power resources.
10. The method of claim 1, wherein the power resources are electric
vehicles.
11. A method for managing power flow, comprising the steps of:
controlling a plurality of power resources via Automatic Generation
Control (AGC) commands, wherein the AGC commands are transmitted by
a power flow manager to the plurality of power resources, wherein
the AGC commands request power regulation; determining a power
regulation range for at least one of the plurality of power
resources; and, transmitting an AGC command to the at least one of
the plurality of power resources, wherein the AGC command is based
on the power regulation range for the at least one of the plurality
of power resources.
12. The method of claim 11, wherein the AGC command comprises a
power level set point, wherein the power level set point is within
the power regulation range for the at least one of the plurality of
power resources.
13. The method of claim 12, wherein the power level set point is
negative.
14. The method of claim 13, wherein the power flow manager treats
the negative power level set point as requests for power
consumption.
15. The method of claim 13, wherein the power regulation range for
the at least one of the plurality of power resources shifts,
whereby the negative power level set point is set to zero, wherein
the an offset amount becomes a load amount.
16. The method of claim 11, wherein the AGC command comprises a
relative power request, wherein the relative power request
increases or decreases power relative a current power level, and
wherein the power increase or power decrease is within the power
regulation range for the at least one of the plurality of power
resources.
17. The method of claim 11, furthering comprising: adjusting a net
balance of power supply and power demand for the plurality of power
resources; and, aggregating power from the plurality of power
resources.
18. The method of claim 11, wherein the power resources are
electric vehicles.
19. A method for managing power flow, comprising the steps of:
detecting a change in an intermittent power flow, wherein a power
flow manager detects the change in the intermittent power flow;
and, implementing a power flow strategy in response to the change
in the intermittent power flow, wherein the power flow manager
coordinates a plurality of power resources to respond to the change
in the intermittent power flow.
20. The method for claim 19, wherein the power flow strategy is a
smoothing strategy, wherein the plurality of power resources are
utilized to spread the change in the intermittent power flow over a
time period.
21. The method for claim 20, wherein the smoothing strategy
utilizes stored power, deferred charging, or shifts in net power
draw.
22. The method for claim 19, wherein the power flow strategy is a
leveling strategy, wherein the plurality of power resources are
utilized to balance the change in the intermittent power flow.
23. The method for claim 22, wherein the leveling strategy requests
an adjustment to charging rates of a portion of the plurality of
power resources.
24. The method of claim 19, wherein the power resources are
electric vehicles.
Description
[0001] This non-provisional patent application claims priority to,
and incorporates herein by reference, U.S. Provisional Patent
Application No. 61/165,344 filed on Mar. 31, 2009. This application
also incorporates herein by reference the following: U.S. patent
application Ser. No. 12/252,657 filed Oct. 16, 2008; U.S. patent
application Ser. No. 12/252,209 filed Oct. 15, 2008; U.S. patent
application Ser. No. 12/252,803 filed Oct. 16, 2008; and U.S.
patent application Ser. No. 12/252,950 filed Oct. 16, 2008.
[0002] This application includes material which is subject to
copyright protection. The copyright owner has no objection to the
facsimile reproduction by anyone of the patent disclosure, as it
appears in the Patent and Trademark Office files or records, but
otherwise reserves all copyright rights whatsoever.
FIELD OF THE INVENTION
[0003] The present invention relates in general to the field of
electric vehicles, and in particular to novel systems and methods
for power flow management and electrical grid stabilization for
electric vehicles.
BACKGROUND OF THE INVENTION
[0004] The electric power grid has become increasingly unreliable
and antiquated, as evidenced by frequent large-scale power outages.
Grid instability wastes energy, both directly and indirectly, e.g.
by encouraging power consumers to install inefficient forms of
backup generation. While clean forms of energy generation, such as
wind and solar, can help to address the above problems, they suffer
from intermittency. Hence, grid operators are reluctant to rely
heavily on these sources, making it difficult to move away from
carbon-intensive forms of electricity.
[0005] With respect to the electric power grid, electric power
delivered during periods of peak demand costs substantially more
than off-peak power. The electric power grid contains limited
inherent facility for storing electrical energy. Electricity must
be generated constantly to meet uncertain demand, which often
results in over-generation (and hence wasted energy) and sometimes
results in under-generation (and hence power failures). The
communications protocol by which an utility controls a power plant
in regulation mode is known as Automatic Generation Control, or
AGC. AGC signals have been sent to large scale conventional power
plants, generally with a capacity of 1 Megawatt or more.
[0006] Significant opportunities for improvement exist in managing
power flow and stabilizing electrical grids. More economical,
reliable electrical power needs to be provided at times of peak
demand. Power services, such as regulation and spinning reserves,
can be provided to electricity markets to stabilize the grid and
provide a significant economic opportunity. Technologies can be
enabled to provide broader use of intermittent power sources, such
as wind and solar. Novel grid stabilization systems and methods are
needed that aggregate the power generation behavior of resources
via Automatic Generation Control (AGC), that provide system
frequency regulation via AGC, and that smooth and level power
generation.
SUMMARY OF THE INVENTION
[0007] In an embodiment, a method for managing power flow includes
controlling power resources via Automatic Generation Control (AGC)
commands. The AGC commands are transmitted by a power flow manager
to the power resources. The AGC commands request power regulation.
The method includes apportioning the power regulation to the power
resources based on an apportionment scheme. In addition, the method
may include transmitting an AGC command to a power resource,
wherein the AGC command requests an apportioned amount of the power
regulation from the power resource.
[0008] The apportionment scheme may relate to various factors,
including: power range of each power resource; power range of some
power resources; minimization of communications to the power
resources; fairness to the power resources; maximization future
abilities to provide power services by the power resources; and/or,
preferences or requirements of the power resources.
[0009] In another embodiment, the method for managing power flow
also includes controlling a plurality of power resources via
Automatic Generation Control (AGC) commands. The AGC commands are
transmitted by a power flow manager to power resources, and the AGC
commands request power regulation. Further, the method determines a
power regulation range for a power resource, and transmits an AGC
command to the power resource. The AGC command is based on the
power regulation range for the power resource.
[0010] In yet another embodiment, a method for managing power flow
may include detecting a change in an intermittent power flow.
Accordingly, a power flow manager detects the change in the
intermittent power flow. The power flow manager also coordinates
power resources to respond to the change in the intermittent power
flow by implementing a power flow strategy. The power flow strategy
may be a smoothing strategy or a leveling strategy.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The foregoing and other objects, features, and advantages of
the invention will be apparent from the following more particular
description of embodiments as illustrated in the accompanying
drawings, in which reference characters refer to the same parts
throughout the various views. The drawings are not necessarily to
scale, emphasis instead being placed upon illustrating principles
of the invention.
[0012] FIG. 1 is a diagram of an example of a power aggregation
system.
[0013] FIGS. 2A-2B are diagrams of an example of connections
between an electric vehicle, the power grid, and the Internet.
[0014] FIG. 3 is a block diagram of an example of connections
between an electric resource and a flow control server of the power
aggregation system.
[0015] FIG. 4 is a diagram of an example of a layout of the power
aggregation system.
[0016] FIG. 5 is a diagram of an example of control areas in the
power aggregation system.
[0017] FIG. 6 is a diagram of multiple flow control centers in the
power aggregation system and a directory server for determining a
flow control center.
[0018] FIG. 7 is a block diagram of an example of flow control
server.
[0019] FIG. 8A is a block diagram of an example of remote
intelligent power flow module.
[0020] FIG. 8B is a block diagram of an example of transceiver and
charging component combination.
[0021] FIG. 8C is an illustration of an example of simple user
interface for facilitating user controlled charging.
[0022] FIG. 9 is a diagram of an example of resource communication
protocol.
[0023] FIG. 10 is a flow chart of an example for AGC
virtualization.
[0024] FIG. 11 is a flow chart of an example for AGC for resources
beyond generation.
[0025] FIG. 12 is a flow chart of an example of smoothing and
leveling intermittent generation.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0026] Reference will now be made in detail to the embodiments of
the present invention, examples of which are illustrated in the
accompanying drawings.
[0027] Overview
[0028] Described herein is a power aggregation system for
distributed electric resources, and associated methods. In one
implementation, a system communicates over the Internet and/or some
other public or private networks with numerous individual electric
resources connected to a power grid (hereinafter, "grid"). By
communicating, the system can dynamically aggregate these electric
resources to provide power services to grid operators (e.g.
utilities, Independent System Operators (ISO), etc).
[0029] "Power services" as used herein, refers to energy delivery
as well as other ancillary services including demand response,
regulation, spinning reserves, non-spinning reserves, energy
imbalance, reactive power, and similar products.
[0030] "Aggregation" as used herein refers to the ability to
control power flows into and out of a set of spatially distributed
electric resources with the purpose of providing a power service of
larger magnitude.
[0031] "Charge Control Management" as used herein refers to
enabling or performing the starting, stopping, or level-setting of
a flow of power between a power grid and an electric resource.
[0032] "Power grid operator" as used herein, refers to the entity
that is responsible for maintaining the operation and stability of
the power grid within or across an electric control area. The power
grid operator may constitute some combination of manual/human
action/intervention and automated processes controlling generation
signals in response to system sensors. A "control area operator" is
one example of a power grid operator.
[0033] "Control area" as used herein, refers to a contained portion
of the electrical grid with defined input and output ports. The net
flow of power into this area must equal (within some error
tolerance) the sum of the power consumption within the area and
power outflow from the area.
[0034] "Power grid" as used herein means a power distribution
system/network that connects producers of power with consumers of
power. The network may include generators, transformers,
interconnects, switching stations, and safety equipment as part of
either/both the transmission system (i.e., bulk power) or the
distribution system (i.e. retail power). The power aggregation
system is vertically scalable for use within a neighborhood, a
city, a sector, a control area, or (for example) one of the eight
large-scale Interconnects in the North American Electric
Reliability Council (NERC). Moreover, the system is horizontally
scalable for use in providing power services to multiple grid areas
simultaneously.
[0035] "Grid conditions" as used herein, refers to the need for
more or less power flowing in or out of a section of the electric
power grid, in response to one of a number of conditions, for
example supply changes, demand changes, contingencies and failures,
ramping events, etc. These grid conditions typically manifest
themselves as power quality events such as under- or over-voltage
events or under- or over-frequency events.
[0036] "Power quality events" as used herein typically refers to
manifestations of power grid instability including voltage
deviations and frequency deviations; additionally, power quality
events as used herein also includes other disturbances in the
quality of the power delivered by the power grid such as sub-cycle
voltage spikes and harmonics.
[0037] "Electric resource" as used herein typically refers to
electrical entities that can be commanded to do some or all of
these three things: take power (act as load), provide power (act as
power generation or source), and store energy. Examples may include
battery/charger/inverter systems for electric or hybrid-electric
vehicles, repositories of used-but-serviceable electric vehicle
batteries, fixed energy storage, fuel cell generators, emergency
generators, controllable loads, etc.
[0038] "Electric vehicle" is used broadly herein to refer to pure
electric and hybrid electric vehicles, such as plug-in hybrid
electric vehicles (PHEVs), especially vehicles that have
significant storage battery capacity and that connect to the power
grid for recharging the battery. More specifically, electric
vehicle means a vehicle that gets some or all of its energy for
motion and other purposes from the power grid. Moreover, an
electric vehicle has an energy storage system, which may consist of
batteries, capacitors, etc., or some combination thereof. An
electric vehicle may or may not have the capability to provide
power back to the electric grid.
[0039] Electric vehicle "energy storage systems" (batteries, super
capacitors, and/or other energy storage devices) are used herein as
a representative example of electric resources intermittently or
permanently connected to the grid that can have dynamic input and
output of power. Such batteries can function as a power source or a
power load. A collection of aggregated electric vehicle batteries
can become a statistically stable resource across numerous
batteries, despite recognizable tidal connection trends (e.g., an
increase in the total number of vehicles connected to the grid at
night; a downswing in the collective number of connected batteries
as the morning commute begins, etc.) Across vast numbers of
electric vehicle batteries, connection trends are predictable and
such batteries become a stable and reliable resource to call upon,
should the grid or a part of the grid (such as a person's home in a
blackout) experience a need for increased or decreased power. Data
collection and storage also enable the power aggregation system to
predict connection behavior on a per-user basis.
[0040] An Example of the Presently Disclosed System
[0041] FIG. 1 shows a power aggregation system 100. A flow control
center 102 is communicatively coupled with a network, such as a
public/private mix that includes the Internet 104, and includes one
or more servers 106 providing a centralized power aggregation
service. "Internet" 104 will be used herein as representative of
many different types of communicative networks and network mixtures
(e.g., one or more wide area networks--public or private--and/or
one or more local area networks). Via a network, such as the
Internet 104, the flow control center 102 maintains communication
108 with operators of power grid(s), and communication 110 with
remote resources, i.e., communication with peripheral electric
resources 112 ("end" or "terminal" nodes/devices of a power
network) that are connected to the power grid 114. In one
implementation, power line communicators (PLCs), such as those that
include or consist of Ethernet-over-power line bridges 120 are
implemented at connection locations so that the "last mile" (in
this case, last feet--e.g., in a residence 124) of Internet
communication with remote resources is implemented over the same
wire that connects each electric resource 112 to the power grid
114. Thus, each physical location of each electric resource 112 may
be associated with a corresponding Ethernet-over-power line bridge
120 (hereinafter, "bridge") at or near the same location as the
electric resource 112. Each bridge 120 is typically connected to an
Internet access point of a location owner, as will be described in
greater detail below. The communication medium from flow control
center 102 to the connection location, such as residence 124, can
take many forms, such as cable modem, DSL, satellite, fiber, WiMax,
etc. In a variation, electric resources 112 may connect with the
Internet by a different medium than the same power wire that
connects them to the power grid 114. For example, a given electric
resource 112 may have its own wireless capability to connect
directly with the Internet 104 or an Internet access point and
thereby with the flow control center 102.
[0042] Electric resources 112 of the power aggregation system 100
may include the batteries of electric vehicles connected to the
power grid 114 at residences 124, parking lots 126 etc.; batteries
in a repository 128, fuel cell generators, private dams,
conventional power plants, and other resources that produce
electricity and/or store electricity physically or
electrically.
[0043] In one implementation, each participating electric resource
112 or group of local resources has a corresponding remote
intelligent power flow (IPF) module 134 (hereinafter, "remote IPF
module" 134). The centralized flow control center 102 administers
the power aggregation system 100 by communicating with the remote
IPF modules 134 distributed peripherally among the electric
resources 112. The remote IPF modules 134 perform several different
functions, including, but not limited to, providing the flow
control center 102 with the statuses of remote resources;
controlling the amount, direction, and timing of power being
transferred into or out of a remote electric resource 112;
providing metering of power being transferred into or out of a
remote electric resource 112; providing safety measures during
power transfer and changes of conditions in the power grid 114;
logging activities; and providing self-contained control of power
transfer and safety measures when communication with the flow
control center 102 is interrupted. The remote IPF modules 134 will
be described in greater detail below.
[0044] In another implementation, instead of having an IPF module
134, each electric resource 112 may have a corresponding
transceiver (not shown) to communicate with a local charging
component (not shown). The transceiver and charging component, in
combination, may communicate with flow control center 102 to
perform some or all of the above mentioned functions of IPF module
134. A transceiver and charging component are shown in FIG. 2B and
are described in greater detail herein.
[0045] FIG. 2A shows another view of electrical and communicative
connections to an electric resource 112. In this example, an
electric vehicle 200 includes a battery bank 202 and a remote IPF
module 134. The electric vehicle 200 may connect to a conventional
wall receptacle (wall outlet) 204 of a residence 124, the wall
receptacle 204 representing the peripheral edge of the power grid
114 connected via a residential powerline 206.
[0046] In one implementation, the power cord 208 between the
electric vehicle 200 and the wall outlet 204 can be composed of
only conventional wire and insulation for conducting alternating
current (AC) power to and from the electric vehicle 200. In FIG.
2A, a location-specific connection locality module 210 performs the
function of network access point--in this case, the Internet access
point. A bridge 120 intervenes between the receptacle 204 and the
network access point so that the power cord 208 can also carry
network communications between the electric vehicle 200 and the
receptacle 204. With such a bridge 120 and connection locality
module 210 in place in a connection location, no other special
wiring or physical medium is needed to communicate with the remote
IPF module 134 of the electric vehicle 200 other than a
conventional power cord 208 for providing residential line current
at any conventional voltage. Upstream of the connection locality
module 210, power and communication with the electric vehicle 200
are resolved into the powerline 206 and an Internet cable 104.
[0047] Alternatively, the power cord 208 may include safety
features not found in conventional power and extension cords. For
example, an electrical plug 212 of the power cord 208 may include
electrical and/or mechanical safeguard components to prevent the
remote IPF module 134 from electrifying or exposing the male
conductors of the power cord 208 when the conductors are exposed to
a human user.
[0048] In some embodiments, a radio frequency (RF) bridge (not
shown) may assist the remote IPF module 134 in communicating with a
foreign system, such as a utility smart meter (not shown) and/or a
connection locality module 210. For example, the remote IPF module
134 may be equipped to communicate over power cord 208 or to engage
in some form of RF communication, such as Zigbee or Bluetooth.TM.,
and the foreign system may be able to engage in a different form of
RF communication. In such an implementation, the RF bridge may be
equipped to communicate with both the foreign system and remote IPF
module 134 and to translate communications from one to a form the
other may understand, and to relay those messages. In various
embodiments, the RF bridge may be integrated into the remote IPF
module 134 or foreign system, or may be external to both. The
communicative associations between the RF bridge and remote IPF
module 134 and between the RF bridge and foreign system may be via
wired or wireless communication.
[0049] FIG. 2B shows a further view of electrical and communicative
connections to an electric resource 112. In this example, the
electric vehicle 200 may include a transceiver 212 rather than a
remote IPF module 134. The transceiver 212 may be communicatively
coupled to a charging component 214 through a connection 216, and
the charging component itself may be coupled to a conventional wall
receptacle (wall outlet) 204 of a residence 124 and to electric
vehicle 200 through a power cord 208. The other components shown in
FIG. 2B may have the couplings and functions discussed with regard
to FIG. 2A.
[0050] In various embodiments, transceiver 212 and charging
component 214 may, in combination, perform the same functions as
the remote IPF module 134. Transceiver 212 may interface with
computer systems of electric vehicle 200 and communicate with
charging component 214, providing charging component 214 with
information about electric vehicle 200, such as its vehicle
identifier, a location identifier, and a state of charge. In
response, transceiver 212 may receive requests and commands which
transceiver 212 may relay to vehicle 200's computer systems.
[0051] Charging component 214, being coupled to both electric
vehicle 200 and wall outlet 204, may effectuate charge control of
the electric vehicle 200. If the electric vehicle 200 is not
capable of charge control management, charging component 214 may
directly manage the charging of electric vehicle 200 by stopping
and starting a flow of power between the electric vehicle 200 and a
power grid 114 in response to commands received from a flow control
server 106. If, on the other hand, the electric vehicle 200 is
capable of charge control management, charging component 214 may
effectuate charge control by sending commands to the electric
vehicle 200 through the transceiver 212.
[0052] In some embodiments, the transceiver 212 may be physically
coupled to the electric vehicle 200 through a data port, such as an
OBD-II connector. In other embodiments, other couplings may be
used. The connection 216 between transceiver 212 and charging
component 214 may be a wireless signal, such as a radio frequency
(RF), such as a Zigbee, or Bluetooth.TM. signal. And charging
component 214 may include a receiver socket to couple with power
cord 208 and a plug to couple with wall outlet 204. In one
embodiment, charging component 214 may be coupled to connection
locality module 210 in either a wired or wireless fashion. For
example, charging component 214 might have a data interface for
communicating wirelessly with both the transceiver 212 and locality
module 210. In such an embodiment, the bridge 120 may not be
required.
[0053] Further details about the transceiver 212 and charging
component 214 are illustrated by FIG. 8B and described in greater
detail herein.
[0054] FIG. 3 shows another implementation of the connection
locality module 210 of FIG. 2, in greater detail. In FIG. 3, an
electric resource 112 has an associated remote IPF module 134,
including a bridge 120. The power cord 208 connects the electric
resource 112 to the power grid 114 and also to the connection
locality module 210 in order to communicate with the flow control
server 106.
[0055] The connection locality module 210 includes another instance
of a bridge 120, connected to a network access point 302, which may
include such components as a router, switch, and/or modem, to
establish a hardwired or wireless connection with, in this case,
the Internet 104. In one implementation, the power cord 208 between
the two bridges 120 and 120' is replaced by a wireless Internet
link, such as a wireless transceiver in the remote IPF module 134
and a wireless router in the connection locality module 210.
[0056] In other embodiments, a transceiver 212 and charging
component 214 may be used instead of a remote IPF module 134. In
such an embodiment, the charging component 214 may include or be
coupled to a bridge 120, and the connection locality module 210 may
also include a bridge 120', as shown. In yet other embodiments, not
shown, charging component 214 and connection locality module 210
may communicate in a wired or wireless fashion, as mentioned
previously, without bridges 120 and 120'. The wired or wireless
communication may utilize any sort of connection technology known
in the art, such as Ethernet or RF communication, such as Zigbee,
or Bluetooth.
[0057] System Layouts
[0058] FIG. 4 shows a layout 400 of the power aggregation system
100. The flow control center 102 can be connected to many different
entities, e.g., via the Internet 104, for communicating and
receiving information. The layout 400 includes electric resources
112, such as plug-in electric vehicles 200, physically connected to
the grid within a single control area 402. The electric resources
112 become an energy resource for grid operators 404 to
utilize.
[0059] The layout 400 also includes end users 406 classified into
electric resource owners 408 and electrical connection location
owners 410, who may or may not be one and the same. In fact, the
stakeholders in a power aggregation system 100 include the system
operator at the flow control center 102, the grid operator 404, the
resource owner 408, and the owner of the location 410 at which the
electric resource 112 is connected to the power grid 114.
[0060] Electrical connection location owners 410 can include:
[0061] Rental car lots--rental car companies often have a large
portion of their fleet parked in the lot. They can purchase fleets
of electric vehicles 200 and, participating in a power aggregation
system 100, generate revenue from idle fleet vehicles.
[0062] Public parking lots--parking lot owners can participate in
the power aggregation system 100 to generate revenue from parked
electric vehicles 200. Vehicle owners can be offered free parking,
or additional incentives, in exchange for providing power
services.
[0063] Workplace parking--employers can participate in a power
aggregation system 100 to generate revenue from parked employee
electric vehicles 200. Employees can be offered incentives in
exchange for providing power services.
[0064] Residences--a home garage can merely be equipped with a
connection locality module 210 to enable the homeowner to
participate in the power aggregation system 100 and generate
revenue from a parked car. Also, the vehicle battery 202 and
associated power electronics within the vehicle can provide local
power backup power during times of peak load or power outages.
[0065] Residential neighborhoods--neighborhoods can participate in
a power aggregation system 100 and be equipped with power-delivery
devices (deployed, for example, by homeowner cooperative groups)
that generate revenue from parked electric vehicles 200.
[0066] The grid operations 116 of FIG. 4 collectively include
interactions with energy markets 412, the interactions of grid
operators 404, and the interactions of automated grid controllers
118 that perform automatic physical control of the power grid
114.
[0067] The flow control center 102 may also be coupled with
information sources 414 for input of weather reports, events, price
feeds, etc. Other data sources 414 include the system stakeholders,
public databases, and historical system data, which may be used to
optimize system performance and to satisfy constraints on the power
aggregation system 100.
[0068] Thus, a power aggregation system 100 may consist of
components that: [0069] communicate with the electric resources 112
to gather data and actuate charging/discharging of the electric
resources 112; [0070] gather real-time energy prices; [0071] gather
real-time resource statistics; [0072] predict behavior of electric
resources 112 (connectedness, location, state (such as battery
State-Of-Charge) at a given time of interest, such as a time of
connect/disconnect); [0073] predict behavior of the power grid
114/load; [0074] encrypt communications for privacy and data
security; [0075] actuate charging of electric vehicles 200 to
optimize some figure(s) of merit; [0076] offer guidelines or
guarantees about load availability for various points in the
future, etc.
[0077] These components can be running on a single computing
resource (computer, etc.), or on a distributed set of resources
(either physically co-located or not).
[0078] Power aggregation systems 100 in such a layout 400 can
provide many benefits: for example, lower-cost ancillary services
(i.e., power services), fine-grained (both temporal and spatial)
control over resource scheduling, guaranteed reliability and
service levels, increased service levels via intelligent resource
scheduling, and/or firming of intermittent generation sources such
as wind and solar power generation.
[0079] The power aggregation system 100 enables a grid operator 404
to control the aggregated electric resources 112 connected to the
power grid 114. An electric resource 112 can act as a power source,
load, or storage, and the resource 112 may exhibit combinations of
these properties. Control of a set of electric resources 112 is the
ability to actuate power consumption, generation, or energy storage
from an aggregate of these electric resources 112.
[0080] FIG. 5 shows the role of multiple control areas 402 in the
power aggregation system 100. Each electric resource 112 can be
connected to the power aggregation system 100 within a specific
electrical control area. A single instance of the flow control
center 102 can administer electric resources 112 from multiple
distinct control areas 501 (e.g., control areas 502, 504, and 506).
In one implementation, this functionality is achieved by logically
partitioning resources within the power aggregation system 100. For
example, when the control areas 402 include an arbitrary number of
control areas, control area "A" 502, control area "B" 504, . . . ,
control area "n" 506, then grid operations 116 can include
corresponding control area operators 508, 510, . . . , and 512.
Further division into a control hierarchy that includes control
division groupings above and below the illustrated control areas
402 allows the power aggregation system 100 to scale to power grids
114 of different magnitudes and/or to varying numbers of electric
resources 112 connected with a power grid 114.
[0081] FIG. 6 shows a layout 600 of a power aggregation system 100
that uses multiple centralized flow control centers 102 and 102'
and a directory server 602 for determining a flow control center.
Each flow control center 102 and 102' has its own respective end
users 406 and 406'. Control areas 402 to be administered by each
specific instance of a flow control center 102 can be assigned
dynamically. For example, a first flow control center 102 may
administer control area A 502 and control area B 504, while a
second flow control center 102' administers control area n 506.
Likewise, corresponding control area operators (508, 510, and 512)
are served by the same flow control center 102 that serves their
respective different control areas.
[0082] In various embodiments, an electric resource may determine
which flow control center 102/102' administers its control area
502/504/506 by communicating with a directory server 602. The
address of the directory server 602 may be known to electric
resource 112 or its associated IPF module 134 or charging component
214. Upon plugging in, the electric resource 112 may communicate
with the directory server 602, providing the directory server 112
with a resource identifier and/or a location identifier. Based on
this information, the directory server 602 may respond, identifying
which flow control center 102/102' to use.
[0083] In another embodiment, directory server 602 may be
integrated with a flow control server 106 of a flow control center
102/102'. In such an embodiment, the electric resource 112 may
contact the server 106. In response, the server 106 may either
interact with the electric resource 112 itself or forward the
connection to another flow control center 102/102' responsible for
the location identifier provided by the electric resource 112.
[0084] In some embodiments, whether integrated with a flow control
server 106 or not, directory server 602 may include a publicly
accessible database for mapping locations to flow control centers
102/102'.
[0085] Flow Control Server
[0086] FIG. 7 shows a server 106 of the flow control center 102.
The illustrated implementation in FIG. 7 is only one example
configuration, for descriptive purposes. Many other arrangements of
the illustrated components or even different components
constituting a server 106 of the flow control center 102 are
possible within the scope of the subject matter. Such a server 106
and flow control center 102 can be executed in hardware, software,
or combinations of hardware, software, firmware, etc.
[0087] The flow control server 106 includes a connection manager
702 to communicate with electric resources 112, a prediction engine
704 that may include a learning engine 706 and a statistics engine
708, a constraint optimizer 710, and a grid interaction manager 712
to receive grid control signals 714. Grid control signals 714 are
sometimes referred to as generation control signals, such as
automated generation control (AGC) signals. The flow control server
106 may further include a database/information warehouse 716, a web
server 718 to present a user interface to electric resource owners
408, grid operators 404, and electrical connection location owners
410; a contract manager 720 to negotiate contract terms with energy
markets 412, and an information acquisition engine 414 to track
weather, relevant news events, etc., and download information from
public and private databases 722 for predicting behavior of large
groups of the electric resources 112, monitoring energy prices,
negotiating contracts, etc.
[0088] Remote IPF Module
[0089] FIG. 8A shows the remote IPF module 134 of FIGS. 1 and 2 in
greater detail. The illustrated remote IPF module 134 is only one
example configuration, for descriptive purposes. Many other
arrangements of the illustrated components or even different
components constituting a remote IPF module 134 are possible within
the scope of the subject matter. Such a remote IPF module 134 has
some hardware components and some components that can be executed
in hardware, software, or combinations of hardware, software,
firmware, etc. In other embodiments, executable instructions
configured to perform some or all of the operations of remote IPF
module 134 may be added to hardware of an electric resource 112
such as an electric vehicle that, when combined with the executable
instructions, provides equivalent functionality to remote IPF
module 134. References to remote IPF module 134 as used herein
include such executable instructions.
[0090] The illustrated example of a remote IPF module 134 is
represented by an implementation suited for an electric vehicle
200. Thus, some vehicle systems 800 are included as part of the
remote IPF module 134 for the sake of description. However, in
other implementations, the remote IPF module 134 may exclude some
or all of the vehicles systems 800 from being counted as components
of the remote IPF module 134.
[0091] The depicted vehicle systems 800 include a vehicle computer
and data interface 802, an energy storage system, such as a battery
bank 202, and an inverter/charger 804. Besides vehicle systems 800,
the remote IPF module 134 also includes a communicative power flow
controller 806. The communicative power flow controller 806 in turn
includes some components that interface with AC power from the grid
114, such as a powerline communicator, for example an
Ethernet-over-powerline bridge 120, and a current or
current/voltage (power) sensor 808, such as a current sensing
transformer.
[0092] The communicative power flow controller 806 also includes
Ethernet and information processing components, such as a processor
810 or microcontroller and an associated Ethernet media access
control (MAC) address 812; volatile random access memory 814,
nonvolatile memory 816 or data storage, an interface such as an
RS-232 interface 818 or a CANbus interface 820; an Ethernet
physical layer interface 822, which enables wiring and signaling
according to Ethernet standards for the physical layer through
means of network access at the MAC/Data Link Layer and a common
addressing format. The Ethernet physical layer interface 822
provides electrical, mechanical, and procedural interface to the
transmission medium--i.e., in one implementation, using the
Ethernet-over-powerline bridge 120. In a variation, wireless or
other communication channels with the Internet 104 are used in
place of the Ethernet-over-powerline bridge 120.
[0093] The communicative power flow controller 806 also includes a
bidirectional power flow meter 824 that tracks power transfer to
and from each electric resource 112, in this case the battery bank
202 of an electric vehicle 200.
[0094] The communicative power flow controller 806 operates either
within, or connected to an electric vehicle 200 or other electric
resource 112 to enable the aggregation of electric resources 112
introduced above (e.g., via a wired or wireless communication
interface). These above-listed components may vary among different
implementations of the communicative power flow controller 806, but
implementations typically include: [0095] an intra-vehicle
communications mechanism that enables communication with other
vehicle components; [0096] a mechanism to communicate with the flow
control center 102; [0097] a processing element; [0098] a data
storage element; [0099] a power meter; and [0100] optionally, a
user interface.
[0101] Implementations of the communicative power flow controller
806 can enable functionality including: [0102] executing
pre-programmed or learned behaviors when the electric resource 112
is offline (not connected to Internet 104, or service is
unavailable); [0103] storing locally-cached behavior profiles for
"roaming" connectivity (what to do when charging on a foreign
system, i.e., when charging in the same utility territory on a
foreign meter or in a separate utility territory, or in
disconnected operation, i.e., when there is no network
connectivity); [0104] allowing the user to override current system
behavior; and [0105] metering power-flow information and caching
meter data during offline operation for later transaction.
[0106] Thus, the communicative power flow controller 806 includes a
central processor 810, interfaces 818 and 820 for communication
within the electric vehicle 200, a powerline communicator, such as
an Ethernet-over-powerline bridge 120 for communication external to
the electric vehicle 200, and a power flow meter 824 for measuring
energy flow to and from the electric vehicle 200 via a connected AC
powerline 208.
[0107] Power Flow Meter
[0108] Power is the rate of energy consumption per interval of
time. Power indicates the quantity of energy transferred during a
certain period of time, thus the units of power are quantities of
energy per unit of time. The power flow meter 824 measures power
for a given electric resource 112 across a bidirectional
flow--e.g., power from grid 114 to electric vehicle 200 or from
electric vehicle 200 to the grid 114. In one implementation, the
remote IPF module 134 can locally cache readings from the power
flow meter 824 to ensure accurate transactions with the central
flow control server 106, even if the connection to the server is
down temporarily, or if the server itself is unavailable.
[0109] Transceiver and Charging Component
[0110] FIG. 8B shows the transceiver 212 and charging component 214
of FIG. 2B in greater detail. The illustrated transceiver 212 and
charging component 214 is only one example configuration, for
descriptive purposes. Many other arrangements of the illustrated
components or even different components constituting the
transceiver 212 and charging component 214 are possible within the
scope of the subject matter. Such a transceiver 212 and charging
component 214 have some hardware components and some components
that can be executed in hardware, software, or combinations of
hardware, software, firmware, etc.
[0111] The illustrated example of the transceiver 212 and charging
component 214 is represented by an implementation suited for an
electric vehicle 200. Thus, some vehicle systems 800 are
illustrated to provide context to the transceiver 212 and charging
component 214 components.
[0112] The depicted vehicle systems 800 include a vehicle computer
and data interface 802, an energy storage system, such as a battery
bank 202, and an inverter/charger 804. In some embodiments, vehicle
systems 800 may include a data port, such as an OBD-II port, that
is capable of physically coupling with the transceiver 212. The
transceiver 212 may then communicate with the vehicle computer and
data interface 802 through the data port, receiving information
from electric resource 112 comprised by vehicle systems 800 and, in
some embodiments, providing commands to the vehicle computer and
data interface 802. In one implementation, the vehicle computer and
data interface 802 may be capable of charge control management. In
such an embodiment, the vehicle computer and data interface 802 may
perform some or all of the charging component 214 operations
discussed below. In other embodiments, executable instructions
configured to perform some or all of the operations of the vehicle
computer and data interface 802 may be added to hardware of an
electric resource 112 such as an electric vehicle that, when
combined with the executable instructions, provides equivalent
functionality to the vehicle computer and data interface 802.
References to the vehicle computer and data interface 802 as used
herein include such executable instructions.
[0113] In various embodiments, the transceiver 212 may have a
physical form that is capable of coupling to a data port of vehicle
systems 800. Such a transceiver 212 may also include a plurality of
interfaces, such as an RS-232 interface 818 and/or a CANBus
interface 820. In various embodiments, the RS-232 interface 818 or
CANBus interface 820 may enable the transceiver 212 to communicate
with the vehicle computer and data interface 802 through the data
port. Also, the transceiver may be or comprise an additional
interface (not shown) capable of engaging in wireless communication
with a data interface 820 of the charging component 214. The
wireless communication may be of any form known in the art, such as
radio frequency (RF) communication (e.g., Zigbee, and/or
Bluetooth.TM. communication). In other embodiments, the transceiver
may comprise a separate conductor or may be configured to utilize a
powerline 208 to communicate with charging component 214. In yet
other embodiments, not shown, transceiver 212 may simply be a radio
frequency identification (RFID) tag capable of storing minimal
information about the electric resource 112, such as a resource
identifier, and of being read by a corresponding RFID reader of
charging component 214. In such other embodiments, the RFID tag
might not couple with a data port or communicate with the vehicle
computer and data interface 802.
[0114] As shown, the charging component 214 may be an intelligent
plug device that is physically connected to a charging medium, such
as a powerline 208 (the charging medium coupling the charging
component 214 to the electric resource 112) and an outlet of a
power grid (such as the wall outlet 204 shown in FIG. 2B). In other
embodiments charging component 214 may be a charging station or
some other external control. In some embodiments, the charging
component 214 may be portable.
[0115] In various embodiments, the charging component 214 may
include components that interface with AC power from the grid 114,
such as a powerline communicator, for example an
Ethernet-over-powerline bridge 120, and a current or
current/voltage (power) sensor 808, such as a current sensing
transformer.
[0116] In other embodiments, the charging component 214 may include
a further Ethernet plug or wireless interface in place of bridge
120. In such an embodiment, data-over-powerline communication is
not necessary, eliminating the need for a bridge 120. The Ethernet
plug or wireless interface may communicate with a local access
point, and through that access point to flow control server
106.
[0117] The charging component 214 may also include Ethernet and
information processing components, such as a processor 810 or
microcontroller and an associated Ethernet media access control
(MAC) address 812; volatile random access memory 814, nonvolatile
memory 816 or data storage, a data interface 826 for communicating
with the transceiver 212, and an Ethernet physical layer interface
822, which enables wiring and signaling according to Ethernet
standards for the physical layer through means of network access at
the MAC/Data Link Layer and a common addressing format. The
Ethernet physical layer interface 822 provides electrical,
mechanical, and procedural interface to the transmission
medium--i.e., in one implementation, using the
Ethernet-over-powerline bridge 120. In a variation, wireless or
other communication channels with the Internet 104 are used in
place of the Ethernet-over-powerline bridge 120.
[0118] The charging component 214 may also include a bidirectional
power flow meter 824 that tracks power transfer to and from each
electric resource 112, in this case the battery bank 202 of an
electric vehicle 200.
[0119] Further, in some embodiments, the charging component 214 may
comprise an RFID reader to read the electric resource information
from transceiver 212 when transceiver 212 is an RFID tag.
[0120] Also, in various embodiments, the charging component 214 may
include a credit card reader to enable a user to identify the
electric resource 112 by providing credit card information. In such
an embodiment, a transceiver 212 may not be necessary.
[0121] Additionally, in one embodiment, the charging component 214
may include a user interface, such as one of the user interfaces
described in greater detail below.
[0122] Implementations of the charging component 214 can enable
functionality including: [0123] executing pre-programmed or learned
behaviors when the electric resource 112 is offline (not connected
to Internet 104, or service is unavailable); [0124] storing
locally-cached behavior profiles for "roaming" connectivity (what
to do when charging on a foreign system or in disconnected
operation, i.e., when there is no network connectivity); [0125]
allowing the user to override current system behavior; and [0126]
metering power-flow information and caching meter data during
offline operation for later transaction.
[0127] User Interfaces (UI)
[0128] Charging Station UI. An electrical charging station, whether
free or for pay, can be installed with a user interface that
presents useful information to the user. Specifically, by
collecting information about the grid 114, the electric resource
state, and the preferences of the user, the station can present
information such as the current electricity price, the estimated
recharge cost, the estimated time until recharge, the estimated
payment for uploading power to the grid 114 (either total or per
hour), etc. The information acquisition engine 414 communicates
with the electric resource 112 and with public and/or private data
networks 722 to acquire the data used in calculating this
information.
[0129] The types of information gathered from the electric resource
112 could include an electric resource identifier (resource ID) and
state information like the state of charge of the electric resource
112. The resource ID could be used to obtain knowledge of the
electric resource type and capabilities, preferences, etc. through
lookup with the flow control server 106.
[0130] In various embodiments, the charging station system
including the UI might also gather grid-based information, such as
current and future energy costs at the charging station.
[0131] User Charge Control UI Mechanisms. In various embodiments,
by default, electric resources 112 may receive charge control
management via power aggregation system 100. In some embodiments,
an override control may be provided to override charge control
management and charge as soon as possible. The override control may
be provided, in various embodiments, as a user interface mechanism
of the remote IPF module 134, the charging component 214, of the
electric resource (for example, if electric resource is a vehicle
200, the user interface control may be integrated with dash
controls of the vehicle 200) or even via a web page offered by flow
control server 106. The control could be presented, for example, as
a button, a touch screen option, a web page, or some other UI
mechanism. In one embodiment, the UI may be the UI illustrated by
FIG. 8C and discussed in greater detail below. In some embodiments,
the override would be a one-time override, only applying to a
single plug-in session. Upon disconnecting and reconnecting, the
user may again need to interact with the UI mechanism to override
the charge control management.
[0132] In some embodiments, the user may pay more to charge with
the override on than under charge control management, thus
providing an incentive for the user to accept charge control
management. Such a cost differential may be displayed or rendered
to the user in conjunction with or on the UI mechanism. This
differential could take into account time-varying pricing, such as
Time of Use (TOU), Critical Peak Pricing (CPP), and Real-Time
Pricing (RTP) schemes, as discussed above, as well as any other
incentives, discounts, or payments that might be forgone by not
accepting charge control management.
[0133] UI Mechanism for Management Preferences. In various
embodiments, a user interface mechanism of the remote IPF module
134, the charging component 214, of the electric resource (for
example, if electric resource is a vehicle 200, the user interface
control may be integrated with dash controls of the vehicle 200) or
even via a web page offered by flow control server 106 may enable a
user to enter and/or edit management preferences to affect charge
control management of the user's electric resource 112. In some
embodiments, the UI mechanism may allow the user to enter/edit
general preferences, such as whether charge control management is
enabled, whether vehicle-to-grid power flow is enabled or whether
the electric resource 112 should only be charged with clean/green
power. Also, in various embodiments, the UI mechanism may enable a
user to prioritize relative desires for minimizing costs,
maximizing payments (i.e., fewer charge periods for higher
amounts), achieving a full state-of-charge for the electric
resource 112, charging as rapidly as possible, and/or charging in
as environmentally-friendly a way as possible. Additionally, the UI
mechanism may enable a user to provide a default schedule for when
the electric resource will be used (for example, if resource 112 is
a vehicle 200, the schedule would be for when the vehicle 200
should be ready to drive). Further, the UI mechanism may enable the
user to add or select special rules, such as a rule not to charge
if a price threshold is exceeded or a rule to only use charge
control management if it will earn the user at least a specified
threshold of output. Charge control management may then be
effectuated based on any part or all of these user entered
preferences.
[0134] Simple User Interface. FIG. 8C illustrates a simple user
interface (UI) which enables a user to control charging based on
selecting among a limited number of high level preferences. For
example, UI 2300 includes the categories "green", "fast", and
"cheap" (with what is considered "green", "fast", and "cheap"
varying from embodiment to embodiment). The categories shown in UI
2300 are selected only for the sake of illustration and may instead
includes these and/or any other categories applicable to electric
resource 112 charging known in the art. As shown, the UI 2300 may
be very basic, using well known form controls such as radio
buttons. In other embodiments, other graphic controls known in the
art may be used. The general categories may be mapped to specific
charging behaviors, such as those discussed above, by a flow
control server 106.
[0135] Electric Resource Communication Protocol
[0136] FIG. 9 illustrates a resource communication protocol. As
shown, a remote IPF module 134 or charging component 214 may be in
communication with a flow control server 106 over the Internet 104
or another networking fabric or combination of networking fabrics.
In various embodiments, a protocol specifying an order of messages
and/or a format for messages may be used to govern the
communications between the remote IPF module 134 or charging
component 214 and flow control server 106.
[0137] In some embodiments, the protocol may include two channels,
one for messages initiated by the remote IPF module 134 or charging
component 214 and for replies to those messages from the flow
control server 106, and another channel for messages initiated by
the flow control server 106 and for replies to those messages from
the remote IPF module 134 or charging component 214. The channels
may be asynchronous with respect to each other (that is, initiation
of messages on one channel may be entirely independent of
initiation of messages on the other channel). However, each channel
may itself be synchronous (that is, once a message is sent on a
channel, another message may not be sent until a reply to the first
message is received).
[0138] As shown, the remote IPF module 134 or charging component
214 may initiate communication 902 with the flow control server
106. In some embodiments, communication 902 may be initiated when,
for example, an electric resource 112 first plugs in/connects to
the power grid 114. In other embodiments, communication 902 may be
initiated at another time or times. The initial message 902
governed by the protocol may require, for example, one or more of
an electric resource identifier, such as a MAC address, a protocol
version used, and/or a resource identifier type.
[0139] Upon receipt of the initial message by the flow control
server 106, a connection may be established between the remote IPF
module 134 or charging component 214 and flow control server 106.
Upon establishing a connection, the remote IPF module 134 or
charging component 214 may register with flow control server 106
through a subsequent communication 903. Communication 903 may
include a location identifier scheme, a latitude, a longitude, a
max power value that the remote IPF module 134 or charging
component 214 can draw, a max power value that the remote IPF
module 134 or charging component 214 can provide, a current power
value, and/or a current state of charge.
[0140] After the initial message 902, the protocol may require or
allow messages 904 from the flow control server 106 to the remote
IPF module 134 or charging component 214 or messages 906 from
remote IPF module 134 or charging component 214 to the flow control
server 106. The messages 904 may include, for example, one or more
of commands, messages, and/or updates. Such messages 904 may be
provided at any time after the initial message 902. In one
embodiment, messages 904 may include a command setting, a power
level and/or a ping to determine whether the remote IPF module 134
or charging component 214 is still connected.
[0141] The messages 906 may include, for example, status updates to
the information provided in the registration message 903. Such
messages 906 may be provided at any time after the initial message
902. In one embodiment, the messages 906 may be provided on a
pre-determined time interval basis. In various embodiments,
messages 906 may even be sent when the remote IPF module 134 or
charging component 214 is connected, but not registered. Such
messages 906 may include data that is stored by flow control server
106 for later processing. Also, in some embodiments, messages 904
may be provided in response to a message 902 or 906.
[0142] AGC Virtualizer
[0143] An attribute of the electrical grid is that power production
must always be closely matched to power consumption. As such,
electric utilities predict power consumption in advance using a
variety of techniques in order to schedule power production to
match consumption. Because these predictions are never entirely
accurate, the electric utility is left with a shortfall or surplus
of produced electricity.
[0144] To address this mismatch between predicted and actual power
consumption, utilities arrange for some power generation plant to
operate in a regulation mode. This is sometimes called system
regulation, or frequency regulation. In regulation mode, the power
output of a power plant can be increased or decreased in near real
time. In the event of a power surplus, the utility orders the power
plant in regulation mode to decrease power production. In the event
of a power shortage, the utility orders the power plant to increase
power production. Not all power plants are capable of operating in
this mode, and the power plants that are often incur increased
costs while in this mode. Issues such as fuel efficiently and
mechanical stress must be accounted for when figuring the cost of
regulation mode.
[0145] A power flow manager can provide system frequency regulation
via Automatic Generation Control (AGC) commands. As such, the
system may appear to behave as an ISO/TSO or a grid operator, such
as a power plant, even though it is not actually a power plant. The
power flow manager coordinates the behavior of power resources,
such as the following: load, generation, or storage. The power
resources can include plug-in vehicles, fixed energy storage, loads
such as HVAC, or other devices. The AGC commands can be translated
by the power flow manager into commands to specific devices, or
sets of devices within its pool, in order to achieve aggregate
behavior across the set of resources that matches the AGC
request.
[0146] In an embodiment, the AGC command can be transmitted to all
power resources. The magnitude of the command can be divided up
among the power resources in proportion to the power range of each
resource, accordingly to one embodiment. For example, a command for
1 MW of down regulation can be divided up such that a device with a
2 kW potential power swing between max power in and max power out
would be asked to provide half as much contribution as a device
with a 4 kW potential power swing. More complex schemes can
optimize dispatch based on a variety of factors, including:
minimizing communication to resources; fairness; maximizing ability
to provide services in the future, e.g. not filling up a plug-in
vehicle that can only be charged; or, resource owner preferences or
requirements.
[0147] AGC allows for regulation in two directions. Up regulation
is a request for additional power, while down regulation is the
request for a reduction in power. A power flow manager can
implement bi-directional regulation (both up and down) using only
power resources that are capable of unidirectional power flow. This
is accomplished by setting a population of power resources to
consume power at a rate less than their maximum (e.g. 50%), and
then adjusting power consumption up and down in accordance with AGC
commands. During periods of power shortage (resulting in up
regulation requests), the power resources could curtail energy use
and/or increase energy output. During periods of power surplus
(resulting in down regulation requests), the power resources could
increase energy use and/or decrease energy output relative to their
initial rate.
[0148] FIG. 10 shows an embodiment of power flow management using
AGC commands to control power resources 1010. Power regulation is
apportioned to the power resources 1020. An AGC command, which
requests an apportioned amount of the power regulation, is
transmitted to a power resource 1030.
[0149] AGC for Resources Beyond Generation
[0150] Automatic Generation Control (AGC) can be utilized to
control power plants so that they may provide system frequency
regulation. In an embodiment, a power plant might be scheduled to
provide 30 MW of power during a certain hour, while also being
available to provide 10 MW of down regulation and 20 MW of up
regulation during that hour. As such, the plant output might vary
anywhere from 20 MW to 50 MW. In an embodiment, AGC typically
transmits a power level set point within this range, e.g. 37 MW, or
may send relative power request, i.e. increase power or decrease
power relative to the current level.
[0151] Given a load or energy-storage based power resource, or an
aggregation of such power resources, system frequency regulation
can also be provided by adjusting the net balance of supply and
demand for energy. Energy storage in discharge mode can output
power much like a generation plant. Load, or energy storage in
charge mode, can consume power like negative generation. When a
number of vehicles/resources are grid-connected and charging, an up
regulation request can be serviced by temporarily reducing the rate
of vehicle charge. Additionally, generation based power resources
can be part of an aggregate of other load or energy-storage based
power resources.
[0152] In one embodiment, AGC systems and protocols can be extended
to handle power level set points that can be negative. As such, the
power flow manager receiving the request can treat negative values
as requests for energy consumption, and positive values as requests
for energy production. When the AGC system does not support
negative numbers, the entire power range can be shifted to start at
zero, such that the shift amount becomes a separate load amount
within the system. For example, a power range of -5 MW to 10 MW can
be shifted to be 0 MW to 15 MW with the offset amount becoming a
separate load amount of 5 MW.
[0153] FIG. 11 illustrates an embodiment of power flow management
using AGC commands to control power resources 1110 where a power
regulation range for a power resource is determined 1120. An AGC
command based on the power regulation range is transmitted to the
power resource 1130.
[0154] Intermittent Generation Smoothing and Leveling
[0155] Intermittent generation resources, such as wind or solar,
can suffer from sudden ramping up or down in output, as well as
somewhat unpredictable output levels over time. For example, the
wind speed or direction can shift rapidly or a cloud can
temporarily obscure the sun over a solar generation asset. Since
power production must always be closely matched to power
consumption, it is very difficult to integrate unreliable
generation resources in to the grid, particularly as the percentage
of power being provided by such resources increases in the
generation mix.
[0156] In some situations, utilities are forced to provision
conventionally fueled standby power generation assets to provide
backup to the intermittent generation resources. For example,
natural gas turbines are often used in this way. Other rapidly
adjustable generation such as hydro may also be used to provide
this firming of intermittent generation. This substantially
increases the real cost of renewable energy sources. To address
these issues, a single power source or an aggregated collection of
power resources can be controlled. Such resources may include load,
generation, or storage.
[0157] In the case of unexpected drop-off in electricity
production, managed power resources can reduce their electricity
consumption. Power resources capable of reverse energy flow may
also contribute electricity back to the grid. In the case of an
unexpected spike in electricity production, managed power resources
can consume the surplus electricity by increasing their rate of
energy consumption, or by other means. A collection of power
resources could be managed using at least two distinct strategies:
smoothing and leveling.
[0158] In a smoothing method, the rate of change of power output
can be limited. When a sudden increase or decrease in power
production occurs, the managed power resources can be used to
spread this sudden change over more time. As an example, a sudden
drop-off in wind production from 10 MW to 0 MW could be spread out
over 20 minutes (using stored power, deferred charging, and other
shifts in net power draw), affording the utility additional time to
locate replacement power sources or otherwise address the
shortfall.
[0159] In a leveling method, the overall contribution of the
generation resources to the grid can be balanced by the power
resources to provide a desired level of net generation. In an
embodiment, such methods are used when output from a wind farm
falls below a desired level. A collection of aggregated resources,
such as plug-in vehicles, are dispatched to absorb the power drop.
Some of the plug-in vehicles are requested to stop charging, or to
charge at a lower rate. With a sufficiently large and capable
collection of distributed power resources, leveling could increase
the reliability of renewables to the same level as conventional
power sources.
[0160] In an embodiment, leveling may be more valuable than
smoothing to an utility or other operator. However, leveling may
require a large amount of reserve capacity relative to the amount
of renewable energy being managed. Smoothing can provide
substantial benefit while requiring a smaller population of
distributed energy resources.
[0161] FIG. 12 illustrates an embodiment of power flow management
that detects a change in an intermittent power flow 1210 and
implements a power flow strategy in response to the change in the
intermittent power flow 1220. The power flow strategy may be a
smoothing strategy or a leveling strategy.
CONCLUSION
[0162] Although systems and methods have been described in language
specific to structural features and/or methodological acts, it is
to be understood that the subject matter defined in the appended
claims is not necessarily limited to the specific features or acts
described. Rather, the specific features and acts are disclosed as
examples of implementations of the claimed methods, devices,
systems, etc. It will be understood by those skilled in the art
that various changes in form and details may be made therein
without departing from the spirit and scope of the invention.
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