U.S. patent application number 14/506493 was filed with the patent office on 2015-01-22 for power flow measurement and management.
The applicant listed for this patent is Reactive Technologies Limited. Invention is credited to Heikki HUOMO.
Application Number | 20150025701 14/506493 |
Document ID | / |
Family ID | 42084109 |
Filed Date | 2015-01-22 |
United States Patent
Application |
20150025701 |
Kind Code |
A1 |
HUOMO; Heikki |
January 22, 2015 |
POWER FLOW MEASUREMENT AND MANAGEMENT
Abstract
Methods and systems for measuring and/or managing power
consumption by power units connected to an electricity distribution
network are disclosed. Power flow to and/or from a power unit
connected to an electricity distribution network is controlled in
accordance with a control sequence, such that the consumption
and/or provision of power by the power unit results in a power flow
having a predefined flow pattern, and having a characteristic, such
as an amplitude, which can be remotely measured. This measurement
may be performed using a method in which a signal indicative of
power flowing at a measurement node is measured and correlated with
a predefined pattern, and a characteristic of the correlated signal
is measured. Thus, power flow characteristics resulting from a
group of one or more power flow devices can be remotely detected
and measured.
Inventors: |
HUOMO; Heikki; (Oulu,
FI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Reactive Technologies Limited |
Oxford |
|
GB |
|
|
Family ID: |
42084109 |
Appl. No.: |
14/506493 |
Filed: |
October 3, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12714879 |
Mar 1, 2010 |
8892268 |
|
|
14506493 |
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Current U.S.
Class: |
700/291 |
Current CPC
Class: |
G01R 21/005 20130101;
H02J 3/06 20130101; G05F 1/66 20130101 |
Class at
Publication: |
700/291 |
International
Class: |
G05F 1/66 20060101
G05F001/66; G01R 21/00 20060101 G01R021/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 28, 2010 |
GB |
1001397.7 |
Claims
1. A power flow control device configured for controlling power
flow within an electricity distribution network, the electricity
distribution network comprising a measurement node, the measurement
node being arranged to access a data store storing data indicative
of one or more predefined power flow patterns, the electricity
distribution network being connected to one or more power units
such that a change in consumption and/or provision of electric
power by a first power unit results in a change in power flow in
the network, wherein the power flow control device is configured to
control power flow to and/or from the first power unit in
accordance with a control sequence associated with the first power
unit, the control sequence corresponding to a first predefined
power flow pattern of the one or more predefined power flow
patterns, the first predefined power flow pattern being distinct
from an intrinsic characteristic of power flow of the first power
unit and defining a pattern of control signals for controlling
power flow to and/or from the first power unit, thereby providing,
in said electricity distribution network, a power flow pattern
corresponding to the first predefined power flow pattern and having
a characteristic relating to electric power flow to and/or from the
first power unit, said characteristic being measurable by the
measurement node.
2. A power flow control device according to claim 1, the power flow
control device comprising: a communications interface configured to
receive data indicating a control sequence associated with the
first power unit, the control sequence corresponding to a first
predefined power flow pattern and defining a pattern of control
signals for controlling power flow to and/or from the first power
unit; and a processor configured to control power flow to and/or
from the first power unit in accordance with a received control
sequence, thereby providing, in said electricity distribution
network, a power flow pattern corresponding to the first predefined
power flow pattern and having a characteristic relating to electric
power flow to and/or from the first power unit, said characteristic
being measurable by the measurement node.
3. A power flow control device according to claim 2, wherein the
communications interface is configured to receive data indicating a
control sequence from the measurement node.
4. A power flow control device according to claim 1, wherein the
measurable characteristic comprises an amplitude of the power
flow.
5. A power flow control device according to claim 1, wherein: the
control sequence represents a sequence of control signals for
controlling a switch, the switch being configured to turn power
flow to and/or from the first power unit on or off in accordance
with a control signal; and the switch is configured to be
controlled in accordance with the sequence of control signals.
6. A power flow control device according to claim 1, configured to:
receive an activation signal; and initiate the control sequence on
the basis of the received activation signal.
7. A power flow control device according to claim 6, wherein the
received activation signal specifies a time for initiating the
control sequence, and the power flow control device is configured
to initiate the control sequence at the specified time.
8. A power flow control device according to claim 1, configured to:
receive a disabling signal from the measurement node; and prevent
power flow to and/or from the first power unit in response to
receiving the disabling signal.
9. A power flow control device according to claim 1, wherein the
predefined power flow pattern resulting from the first power unit
comprises a repeating pattern, and the power flow control device is
configured to control power flow to and/or from the first power
unit continuously according to the repeating pattern.
10. A power flow control device according to claim 1, configured to
control an attenuator to modify power flow to and/or from the first
power unit.
11. A power unit comprising a power flow control device according
to claim 1.
12. A power unit according to claim 11, comprising position
determining means for determining a position of the unit and an
interface for sending an indication of a determined position of the
mobile unit to the measurement node.
13. A power unit according to claim 11, comprising a user interface
for providing an indication of availability of the unit for
provision and/or consumption of electric power to and/or from the
electricity distribution network, and an interface for transmitting
an indication of said availability.
14. A method of controlling power within an electricity
distribution network, the electricity distribution network
comprising a measurement node, the measurement node being arranged
to access a data store storing data indicative of one or more
predefined power flow patterns, the electricity distribution
network being connected to one or more power units such that a
change in consumption and/or provision of electric power by a first
power unit results in a change in power flow in the network, the
method comprising: controlling, at the power flow control device,
power flow to and/or from the first power unit in accordance with a
control sequence associated with the first power unit, the control
sequence corresponding to a first predefined power flow pattern of
the one or more predefined power flow patterns, the first
predefined power flow pattern being distinct from an intrinsic
characteristic of power flow of the first power unit and defining a
pattern of control signals for controlling power flow to and/or
from the first power unit, thereby providing, in said electricity
distribution network, a power flow pattern corresponding to the
first predefined power flow pattern and having a characteristic
relating to electric power flow to and/or from the first power
unit, said characteristic being measurable by the measurement
node.
15. A non-transitory computer-readable storage medium comprising
computer-executable instructions which, when executed by a
processor, cause a computing device to perform a method of
controlling power within an electricity distribution network, the
electricity distribution network comprising a measurement node, the
measurement node being arranged to access a data store storing data
indicative of one or more predefined power flow patterns, the
electricity distribution network being connected to one or more
power units such that a change in consumption and/or provision of
electric power by a first power unit results in a change in power
flow in the network, the method comprising: controlling, at the
power flow control device, power flow to and/or from the first
power unit in accordance with a control sequence associated with
the first power unit, the control sequence corresponding to a first
predefined power flow pattern of the one or more predefined power
flow patterns, the first predefined power flow pattern being
distinct from an intrinsic characteristic of power flow of the
first power unit and defining a pattern of control signals for
controlling power flow to and/or from the first power unit, thereby
providing, in said electricity distribution network, a power flow
pattern corresponding to the first predefined power flow pattern
and having a characteristic relating to electric power flow to
and/or from the first power unit, said characteristic being
measurable by the measurement node.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 12/714,879, filed Mar. 1, 2010, which claims
priority to GB Patent Application No. 1001397.7, filed Jan. 28,
2010. Each of the above-referenced patent applications is hereby
incorporated by reference in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to management of power flow in
an electricity distribution network. In particular, but not
exclusively, it relates to measurement of power consumption and
provision by power units connected to the network.
[0004] 2. Description of the Related Technology
[0005] Supply of electricity from providers such as power stations,
to consumers, such as domestic households and businesses, typically
takes place via an electricity distribution network. FIG. 1 shows
an exemplary distribution network comprising a transmission grid
100 and a distribution grid 102. The transmission grid is connected
to generating plants 104, which may be nuclear plants or gas-fired
plants, for example, from which it transmits large quantities of
electrical energy at very high voltages (in the UK, for example,
this is typically of the order of 204 kV; however this varies by
country), using power lines such as overhead power lines, to the
distribution grid 102; although, for conciseness, only one
distribution grid 102 is shown here, in practice a typical
transmission grid supplies power to multiple distribution grids.
The transmission grid 100 is linked to the distribution grid 102
via a transformer node 106, which includes a transformer 106 which
converts the electric supply to a lower voltage (in the UK, for
example, this is typically of the order of 50 kV; however, this
varies by country) for distribution in the distribution grid 102.
The distribution grid in turn links, via substations 108 comprising
further transformers for converting to still lower voltages, to
local networks such as a city network 112 supplying domestic users
114, and to industrial consumers such as a factory 110. Smaller
power providers such as wind farms 116 may also be connected to the
distribution grid 116, and provide power thereto.
[0006] The total power consumption associated with a given network
varies considerably from time to time; for example, peak
consumption periods may occur during the hottest part of the day
during summer, when many consumers use their air conditioning
units. Since it is expensive to store electricity in large
quantities, it is usually generated when it is required, which can
place a burden on providers as they attempt to meet demand at peak
times.
[0007] In recent years, there has been an increased demand for more
efficient ways of managing power distribution in electricity
networks; in particular it is desired to reduce wasteful
electricity consumption in order to reduce costs and the adverse
effect that some methods of electricity generation have on the
environment. There is also a shift towards forms of power
generation, such as wind power and solar power, which may only be
able to supply power intermittently when conditions allow,
increasing the need to reduce variation in power consumption with
time. Furthermore, there is also a trend towards more distributed
forms of power provision. For example, individual households and
businesses are increasingly generating their own power, for example
using solar panels installed on their premises; surplus power
generated using these power sources may be sold back to the
provider managing the network to which it is connected. Personal
Electric Vehicles (PEV) are a further example of an electricity
provider; PEVs typically have the capacity to store a large amount
of electricity, and may be connected to an electricity network when
they are stationary; this means that, in addition to being
consumers of power, they can be used as a source of power for the
network at times of high demand, with electricity stored in the
battery of the PEV being fed back to the network at such times.
[0008] In order to meet these changing requirements, more
sophisticated methods of measuring and controlling power
consumption are desirable. More sophisticated networks, sometimes
known as "smart grids", have been proposed, which may include may
include features such as a capability to turn off certain household
appliances or factory processes at times of peak demand. These
smart grids may use sophisticated meters, sometimes known as "smart
meters" capable of intermittently measuring power consumption in
near real time, and of indicating energy prices to consumers; this
information may be read manually, or it may be transmitted
automatically over a communications network using, for example,
TCP/IP technology, to a central location.
[0009] However such meters are typically located at the premises of
a consumer or provider, and measure the amount of electrical power
flow as a total of all devices located in the premises. This means
that power flows relating to individual devices at a given
premises, or a group of devices distributed across multiple
premises, cannot easily be measured, particularly in view of the
relatively high cost of smart meters making it prohibitive to
install a separate meter at each power consuming and/or providing
unit to be measured.
[0010] It is an object of the present invention to at least
mitigate some of the problems of the prior art.
SUMMARY
[0011] In accordance with a first embodiment of the present
invention, there is provided a method of controlling electricity
power within an electricity distribution network, the electricity
distribution network comprising a measurement node, the measurement
node being configured to access a data store storing data
indicative of one or more predefined power flow patterns, in which
a power unit is electrically connected to the electricity
distribution network and is configured to consume electric power
from and/or provide electric power to the electricity distribution
network such that a change in consumption and/or provision of
electric power by the power unit results in a change in power flow
in the network, the method comprising: controlling power flow to
and/or from the power unit in accordance with a control sequence,
such that the consumption and/or provision of power by the power
unit results in a power flow having a said predefined power flow
pattern, and a characteristic of the power flow resulting from the
unit is measurable by the measurement node.
[0012] By controlling the power flow at a power unit according to a
predefined power flow pattern, a measurement node in a network to
which the unit is connected having access to the pattern can detect
and measure the power flow resulting from the power unit, allowing
the power flow to be remotely detected and measured. Further, since
the method requires only that power flow to and/or from a power
unit be controlled (for example, switched on and off), it does not
require complicated and expensive measuring equipment, such as a
smart meter.
[0013] Preferably, the method comprises receiving the data sequence
at the power flow control unit from the measurement node. The
method may further comprise receiving an activation signal, and
initiating the control sequence on the basis of the received
activation signal. These features enable the power flow patterns of
multiple power units to be controlled centrally from measurement
node.
[0014] In some embodiments, the method comprises preventing power
flow to and/or from the power unit in response to a deactivation
signal. Thus, power units can be turned off centrally, allowing
central control of power flow in the network.
[0015] In some embodiments, the method comprises measuring electric
power consumption and/or provision at the power unit, and sending
an indication of a said measurement to the measurement node. This
enables measurement made at the measurement node to be calibrated
using a local reading made at the device.
[0016] Preferably, each of a distributed group said power units is
connected to the electricity distribution network, each of which
having an associated said power flow control device, and the method
comprises using the power flow control devices to control the power
flow to and/or from the plurality of units in accordance with the
control sequence, such that the consumption and/or provision of
power by the plurality of power units is coordinated to
collectively provide a power flow having the predefined power flow
pattern and a characteristic measurable by the measurement
node.
[0017] By providing a group of, perhaps distributed, power units
with the same control sequence, so that they collectively provide a
combined power flow according to the predefined pattern, the
combined power flow resulting from the group can be measured.
[0018] In some embodiments, a plurality of the groups is connected
to the network, and the method comprises controlling the power flow
to and/or from each of the groups according to different control
sequences, such that the power flow patterns resulting from said
groups are mutually orthogonal, or quasi-orthogonal, such that a
power flow characteristic associated with each of the power flow
patterns can be measured at the measurement node independently of
each of the other patterns.
[0019] By using orthogonal power flow patterns, power flow from
multiple groups of devices can be measured simultaneously.
[0020] In accordance with a second embodiment of the invention,
there is provided a method of measuring power flow in an
electricity distribution network comprising a measurement node, the
electricity distribution network being connected to a group of one
or more power units each configured to consume electricity from
and/or provide electricity to the electricity distribution network
such that a change in power provision and/or consumption by a said
unit results in a change in power flow in the network, wherein each
of the power units is associated with a respective power flow
control device configured to control power flow to and/or from a
power unit in accordance with a predefined control sequence,
resulting in a power flow having a predefined pattern, the
measurement node being configured to access a data store configured
to store data indicative of one or more said patterns, the method
comprising: measuring a signal indicative of power flowing at the
measurement node; analyzing the measured signal so as to correlate
a component thereof with a said pattern, whereby to generate one or
more correlated signals; measuring a characteristic of one or more
correlated signals, thereby determining a contribution to said
measured signal by the group of power units.
[0021] This provides a convenient method of measuring a power flow
resulting from a group one or more power units operated according
to the first embodiment of the invention.
[0022] Preferably, the predefined power flow pattern comprises a
repeating pattern, and the power flow control devices are
configured to controlling power to and/or from the group of one or
more power units continuously according to the repeating pattern.
The method of the present invention allows continuous measurement
of power consumption of a power unit, in contrast to prior art
methods, which generally provide only intermittent measurement.
[0023] Preferably, the method comprises allocating the control
sequence in accordance with a power consumption and/or provision
requirement relating to the one or more power units, whereby to
control an energy consumption and/or provision of the power units.
The method can be conveniently employed to control energy
consumption and/or provision by a power unit simultaneously with
allowing continuous measurement.
[0024] In accordance with a third embodiment of the invention,
there is provided a method of controlling electricity flow in an
electricity distribution network, the electricity distribution
network comprising a plurality of measurement nodes and a plurality
of distributed groups of power units, each of said power units
being configured to consume and/or provide electricity associated
with the electricity distribution network, wherein each power unit
in a given group is configured to be controlled by a control
sequence assigned to the group, the control sequence controlling
power consumption and/or provision by each unit of the group
according to a predefined pattern, resulting in an associated power
flow pattern, and each of the measurement nodes being configured to
measure a characteristic of power flowing in the network associated
with the power consumption and/or provision of one or more groups,
the method comprising: assigning a plurality of said control
sequences to a first plurality of groups of units, such that a
characteristic of power flow associated with the first plurality of
groups is measurable by a first said measurement node, wherein the
assigned control sequences result in mutually orthogonal patterns
of power flow, whereby flow characteristics associated with each of
the power flow patterns can be measured at the first node
independently of each of the other patterns; assigning a further
control sequence to a further, different, group of units, such that
a characteristic of modulated power flow associated with the
further group of units is measurable by a further, different,
measurement node; and controlling consumption or provision of power
in the network in accordance with the assigned control sequences,
wherein the further control sequence corresponding to a control
sequence assigned to the first plurality of groups.
[0025] Thus, according to this embodiment of the invention,
orthogonal codes can re-used between different measurement
nodes.
[0026] In accordance with a fourth embodiment of the present
invention, there is provided a method of controlling electricity
flow within an electricity distribution network, the electricity
distribution network comprising an measurement node and a plurality
of power units, each of the power units being configured to consume
and/or provide electricity associated with the electricity
distribution network, wherein each of the power units is configured
to be controlled by an assigned control sequence, the control
sequence controlling power consumption and/or provision by the unit
according to a predefined pattern, the method comprising; assigning
group membership to a plurality of the units, thereby defining at
least one group; and assigning a said control sequence to the
group, such that each unit of the group consumes and/or provides
power in accordance with a predefined pattern corresponding to the
assigned control sequence, resulting in a modulated power flow
pattern having a characteristic measurable at the measurement node,
the method further comprising: measuring a characteristic of the
modulated power flow pattern at the measurement node; based on the
measured characteristic and one or more predefined optimization
parameters, modifying the assigned group membership; and iterating
said measurement and modification, whereby to optimize a measured
characteristic associated with the group.
[0027] This provides a convenient method of defining groups for use
in measurement methods according to embodiments of the present
invention; by iterating the measurement and modification steps, it
can be assured that groups having appropriate characteristics are
defined.
[0028] In some embodiments, the network comprises a plurality of
geographical areas each associated with a said node, and in which
each unit located in a given said geographical area is associated
with the node associated with that area. In some embodiments one or
more of the units is capable of moving between the geographical
areas, and the method comprises: monitoring a location of one or
more of the units; determining that one or more units have entered
a given geographical area; in response to said determination,
associating the one or more units with a node associated with the
given area; analyzing group membership and associated modulated
power flows in the given area; and assigning group membership to
the one or more units that have entered the given geographical area
on the basis of the analysis.
[0029] This allows the group assignment to take account of the
movement of power units, and update group membership
accordingly.
[0030] Further features and advantages of the invention will become
apparent from the following description of preferred embodiments of
the invention, given by way of example only, which is made with
reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] FIG. 1 shows a prior art electricity distribution
network;
[0032] FIG. 2 shows a network comprising a measurement node and
groups of power units, according to one or more embodiments of the
present invention;
[0033] FIG. 3A shows a first type of repeating power flow patterns
according to one or more embodiments of the present invention;
[0034] FIG. 3B shows a second type of repeating power flow patterns
according to one or more embodiments of the present invention;
[0035] FIG. 3C shows a third type of repeating power flow patterns
according to one or more embodiments of the present invention;
[0036] FIG. 4 shows an arrangement including a power flow control
device according to one or more embodiments of the present
invention;
[0037] FIG. 5 shows a measurement node according to one or more
embodiments of the present invention; and
[0038] FIG. 6 is a flow diagram showing steps in assigning groups
of power flow control units according to one or more embodiments of
the present invention.
DETAILED DESCRIPTION OF CERTAIN INVENTIVE EMBODIMENTS
[0039] FIG. 2 illustrates an electricity distribution network in
which an embodiment of the present invention may be implemented.
The network comprises a measurement node 204 which is connected via
power lines 208 to power units 202a to 202l via power flow control
devices 200a to 200l. Each of the power units 202a to 202l consumes
and/or provides electric power. Examples of power units consuming
electric power include domestic appliances such as electric water
heaters and washing machines, as well as industrial devices, such
as factory machinery and desktop computers. Examples of providers
of electric power include solar panels and wind-turbines. Still
other power units may consume electric power at some times but
provide it at others, such as the PEVs described above. Further,
the term power unit is used herein to include collections of such
appliances and devices, such as a house. Each of the power units is
associated with a power flow control device 200a to 200l, which
controls transfer (i.e. provision and/or consumption) of power by
the associated power unit; a power flow control device 200 is
described in more detail below.
[0040] The measurement node 204 may be located at the transformer
node 106 described above, which links a transmission grid with a
distribution grid; alternatively, it may be located at a substation
108 in the distribution grid, or at any other location of the
electricity distribution network convenient for interacting with
power units as described herein.
[0041] Although, for the sake of simplicity, only twelve power
units are shown in FIG. 1, it will be understood that, in practice,
the network will typically comprise many hundreds or thousands of
such devices.
[0042] Further, the power units and associated power flow control
devices are divided into groups 206a to 206d. As shown, the
grouping need not contain equal numbers of member devices; further,
the grouping need not take account of geographical location, and
may be highly distributed. Further, the grouping need not take
account of power unit type; for example, some groups may include
both providers and consumers of electric power. Some groups may
only have a single member.
[0043] In some embodiments of the present invention, membership of
a group is not fixed, but can be varied with time to meet
requirements, as is described in more detail below.
[0044] Power flow control devices 200a to 200l each modify the
power flow to and/or from respective associated power unit 202a to
202l, according to a pattern which is uniquely defined for each
group 206a to 206d. Representations of these patterns are also
stored at the measurement node 204. The modified power flow
propagates through the power lines 208 in the network in the form
of an electric power signal (EPS); these EPSs may be thought of as
waves having a waveform corresponding to the pattern used for the
group, each group 206a to 206d having a uniquely associated
waveform.
[0045] An exemplary arrangement for modifying the power transfer of
(i.e. the power consumed or produced by) a power unit as described
above is now described with reference to FIG. 4. FIG. 4 shows an
exemplary power unit 202 of FIG. 2 which consumes electricity
provided along power lines 208 connected to an electricity
distribution network. In accordance with an embodiment of the
present invention, a power flow control device 200 is arranged to
send signals to a switch 406 which controls the supply of power to
the power unit 202. The power flow control device 200 comprises a
clock 402, a data store 403, a processor 404, a user interface 405
and a communications interface 410 arranged to receive transmit and
receive information via a fixed or wireless communications means,
such as ADSL, GSM, 3G etc.; functions of these components are
described in detail below. A power meter 412 may also be provided
which is arranged to measure the power consumption at the power
unit 202; a use of this power meter is described below.
[0046] Although the power flow control device 200 is shown here as
a separate device to the power unit 202, in some cases it may
comprise an integrated part of the latter; further the switch 406
is not necessarily located exterior to the power unit 202, but may
instead be installed in the unit, and be arranged to control power
supply from the interior of the device; this latter case is
advantageous where the power unit may move from location to
location, for example if the power unit is a PEV.
[0047] The data store 403 of the power flow control device 200
stores one or more control sequences (referred to herein as
"codes") representing control signals for controlling the switch
according to a predefined pattern. The processor 404 accesses the
data store 403, retrieves a code and, based on the code, sends
control signals to the switch 406 for controlling the flow of power
to the power unit 202. The code typically defines a time-varying
pattern of control signals, in this case the signals are provided
with reference to the clock 402.
[0048] It should be noted that, although the codes are described
above as being stored in the data store 403 of the power flow
control device 200, in some embodiments they may be stored
remotely, with the device 200 accessing the remote store to receive
the codes when required. In some embodiments, the codes may be
transmitted to the device 200, for example from the measurement
node 204, in which case they may not be stored at the device 200,
or stored only in a temporary data store.
[0049] The switch may comprise a simple relay device which turns
power supply on- and off-periods at specific time instants.
Alternatively or additionally, the switch 406 may comprise an
attenuator or a phase inverter, etc. used to obtain a unique
waveform not necessarily including simply on- and off-periods. The
codes stored in the power flow control device may be prescribed in
the configuration of the power flow control device 200 when the
power flow control device 200 is set up, or it may be communicated
to the power flow control device 200 via the communications
interface 410; further details on the latter arrangement are
provided below.
[0050] The action of the switch 406 thus provides an EPS which
propagates through the power lines 414 to the electricity
distribution network, and whose amplitude depends on the power
consumption of the power unit 202. In embodiments of the present
invention, groups of one or more power flow control devices are
each assigned a common code and thereby coordinated such that a
combined EPS results which can be arranged to be of a size
sufficient to be detected at the measurement node 204. The EPSs
generated by each group of power units propagates through the
network to the measurement node 204, thereby modifying the total
power flow at the measurement node. Since the pattern by which the
EPS was generated is known by the measurement node 204, the
measurement node 204 can identify a given group by detecting the
EPS associated with a known pattern, and analyzing it to filter out
the contribution to the total power flow by the given group,
thereby determining the contribution to the total power flow by the
given group.
[0051] Although the power unit 202 has been described as consuming
power provided by the electricity distribution network, it will be
understood that the above described processes apply equally in the
case that the device is a provider of electrical power.
[0052] FIG. 5 shows an exemplary measurement node 204. The node 204
comprises a processor 504, a data store 503, a clock 502, a
communications interface 510 and a power meter 512 arranged to
measure the power flow through power lines 514 located at the node
204. The data store 503 stores one or more codes, corresponding to
those stored in the data store 403 of the power flow control device
200, along with information relating to the group associated with
each code. For example, the data store may contain an identifier of
each of the power units belonging to each group, along with an
address, such as IP address, of each device associated with a
group; use of this address data is described below.
[0053] The meter 512 may be an integrated component of the node
204, or may be in remote communication therewith. It may be
implemented as a coil wrapped around a power line. Typically, the
meter 512 senses temporal variations in the power flow.
[0054] The node processor 504 receives data from the meter 512
indicative of the amplitude, or some other characteristic of power
flow at the node 204. The processor 504 typically includes an
analogue to digital converter which converts the received signal to
digital data. The processor then filters this data, using one or
more of the codes stored in the data store 502 and timing data from
the clock 502, to correlate the received signal and identify one or
more groups of power units, and to determine a power flow amplitude
at the node 204 resulting from each identified group.
[0055] As mentioned above, the power flow control devices 200 may
also communicate with a power meter 412 local to the power units
202 with which they are associated. These local power meters 412
may be used to provide a local reading of power flow in relation to
the device, which may be communicated to the measurement node 204
e.g. via wireless or fixed line telecommunications mean in order to
calibrate readings made at the measurement node 204.
[0056] In some arrangements, only a single group is associated with
a given measurement node 204 s. However, typically multiple groups
will be associated with each node. In the latter case, and to
enable the contribution to the power flow at the measurement to be
distinguished from a given group can be distinguished from the
contribution from other groups, it is useful for the codes to
define patterns of control signals that are orthogonal or
quasi-orthogonal, and result in orthogonal or quasi-orthogonal
EPSs; that is, a respective pattern associated with a given group
is not correlated with patterns associated with other groups, or is
only very weakly correlated therewith.
[0057] Techniques for distinguishing power flows from different
groups are now described with reference to FIGS. 3A to 3C, which
show exemplary techniques that may be used to distinguish the power
flow patterns of different groups. As mentioned above, the groups
are preferably assigned mutually orthogonal codes so that activity
in respect of one group does not interfere with activity in respect
of another group. The codes can be orthogonal in frequency, time,
code or a combination thereof. In practice this may lead to the use
of frequency separation, time division separation, or code division
separation of the groups, or a combination thereof. The measurement
node 204 is accordingly tuned, synchronized, matched, correlated,
etc. to the code in order to identify the group providing/consuming
energy. The measurement node may further measure the power
amplitude of the load of the group.
[0058] FIG. 3A shows an example of N groups where the codes are
arranged according to a pattern of discrete power level transitions
which repeats with a predefined time period 300. If the on-state is
denoted as "1" and the off-state denoted "0", the switching pattern
during one cycle of the waveform 306A for the group #1 is
"0100000", whereas for the waveforms 306B and 306N the
corresponding orthogonal switching patterns are "0010000" and
"0000001" respectively. For the sake of clarity, the waveform
cycles are demarcated with vertical dashed lines 304A to 304C. It
is clear that as the switching patterns are orthogonal between each
other, and they allow identification of the groups.
[0059] Although each of the codes shown in Figure A comprise a
single "on" time slot, it should be noted, however, that one or
more of the codes may have a plurality of on-states during the
cycle 300. The pattern for a specific group may be "011101001", for
example.
[0060] The measurement node 204 may in this case comprise a
correlator for disambiguating signals from, and thus identifying,
the groups. This may be done by comparing each of the
group-specific patterns known to the measurement node with the
waveform of the EPS detected by the processor 504 and determining
which of the possible group-specific patterns results in the
highest correlation with the detected waveform. The processor 504
subsequently identifies the group assigned to use the pattern that
resulted in the highest correlation. In other words, the
measurement node 204 correlates the detected waveform with a
plurality of orthogonal waveforms for identifying the group
providing and/or consuming electric power, on the basis of the
group-specific switching pattern. This method, described with
reference to FIG. 3A, may be referred to as code separation of the
groups.
[0061] The measurement node 204 may also measure the amplitude of
the groups, and add the measured amplitudes together to obtain a
sum of controlled power usage/consumption in the given controlled
groups.
[0062] FIG. 3B shows an example where the groups are identified
with a group-specific time window for switching the electric power
to/from the electric power transmission network. That is, each
group is assigned a specific time window 310A to 310B during which
the associated switches are switched into the "on" state; these
time windows are demarcated with vertical dashed lines 314A to
314C. In FIG. 3B, the group #1 is determined to provide/consume
energy only during the time window 310A. The duration within the
assigned period during which the specific group provides/consumes
energy may be specified as well. As can be seen from FIG. 3B the
duration 312A to 312N of each waveform 316A to 316N, respectively,
may vary. Nevertheless, the activity takes place during the
specified time window 310A to 310B. That is, the load may be
switched on during the whole or a certain fraction of a time
window. This method, described with reference to figure B, may be
referred to as time slot separation of the groups.
[0063] A further technique for identifying groups from associated
EPS s will now be described with reference to FIG. 3C. This
technique applies switching in distinct group-specific frequencies.
That is, each group is specified with a distinct frequency
according to which the group consumes/provides electric power. For
example, group #1 transfers energy in intervals of a period 320A,
group #2 transfers energy in intervals of a period 320B, and group
#N transfers energy in intervals of a period 320N. The intervals
320A to 320N are different for each group and therefore the
waveforms 326A to 326N may be identified at the measurement node as
being associated with a certain group. This method may be referred
to as frequency separation of the groups.
[0064] In the frequency separation method, the processor 504 may
conveniently comprise a Phase Locked Loop (PLL) amplifier with a
plurality of base frequencies for filtering. The processor 504 may
perform a Fourier or a wavelet analysis in order to obtain the
total power associated with the group. Also, the duration for
transferring energy may be varied between groups and also between
different on-periods of one group. This way, the load can be
controlled by varying the ratio of the on/off-states from low to
high
[0065] The above descriptions made with reference to FIGS. 3A to 3C
provide examples of orthogonal switching patterns. Other types of
orthogonal patterns can be created by combining the frequency, time
slot and code separation methods described above. Irrespective of
the way in which power usage of one group is distinguished for that
of another group, the power flow pattern detected at the
measurement node 204 is compared with patterns stored at the
measurement node, and the group from which the detected power flow
pattern results identified on the basis of this comparison.
[0066] By designing the codes appropriately, it is possible to
measure power consumption/provision continuously, rather than
intermittently, and monitor these measurements in real time. That
is, a power flow control device 200 may control a power unit 202
according to a continuously repeating code or series of codes. The
codes can be designed to manipulate the proportion of time that
power is supplied to/from the power unit 202, and/or the amount of
attenuation of the power supply, so that the total energy
consumption over a given period can be managed at an acceptable or
desired level. The time slot separation method and frequency
separation methods described above are particularly advantageous in
relation to this embodiment of the invention.
[0067] For example, it may be acceptable for a domestic air
conditioner to be continuously running at only 80% power, without
any undesirable consequences for the performance of the heater. In
this case the codes can be designed so that the power flow control
device 200 switches off the power supply to the air conditioner for
20% of the time, with power being supplied for the rest of the
time, so that the total energy consumption over a given period is
80% of the maximum.
[0068] In some cases, the code used may vary from time to time,
such that the power consumption is turned on for a higher
proportion of the time at some times than at other times. This
adjustment could be made on the basis of user demand, for example a
user may require their air conditioner to consume more power at
some times than at others, or on the basis of network conditions,
for example switching to a code resulting in lower total power
consumption when it is desired to relieve demand on the
network.
[0069] As mentioned above, in the case that a group comprises more
than one power unit 202, it is advantageous for each power flow
control device 200 of the group to be configured with the same code
i.e. the processor 404 of each power flow control device 200 to use
the same code to control the switch 406. In the case that a group
includes both power providers and power consumers, the power flow
control devices may be arranged such that the switching of the
providers occurs in antiphase to that of the consumers so that, for
example, when the consumers are turned on, the providers are turned
off, and vice versa. This ensures that a power flow amplitude
indicative of the total contribution of the group is produced.
[0070] In order that the resulting EPS from each member of the
group constructively combines with the EPS from the other members,
the use of the codes may be synchronized i.e. the processor 404 of
each group member should activate the code in coordination (e.g.
simultaneously) with the other members of the group. This could be
achieved in a number of ways; for example, the clocks of each power
flow control device 200 could be synchronized, and the devices 200
configured to activate the code at a predetermined time. However,
in the case of code separation of the codes described above, the
use of the codes is not necessarily synchronized; instead, the
power flow control devices 204 of the group may activate a given
code at different times with the processor 504 of the measurement
node 204 being arranged to correlate different instances of the
pattern of power flow corresponding to the code resulting at
different times from different power units 202, and to sum up the
contributions from the different power units 202.
[0071] Activation of the code may be triggered by an activation
signal communicated to the control devices 200 via the
communications interface 410; the activation code could be
transmitted to the devices 200 from the measurement node 204, or
from some other location. The activation signal may trigger
immediate activation of a code, or it may specify a time at which
the code is to be activated. The activation signal may specify a
duration of activation of the code.
[0072] In some embodiments of the present invention, more than one
measurement node 204 is used to detect power flow patterns. Each
measurement node 204 may be assigned a defined geographical area,
with all power units 202 in a given area being associated with the
node for that area. Since the EPSs attenuate as they travel through
the network, the EPS resulting from a group whose member devices
are located in an area associated with a given node 204 will
typically be considerably weaker at other nodes. This means that,
provided the groups are arranged such that the EPS is not so large
as to interfere with signals in neighboring areas, it is possible
to use the same or corresponding codes for groups located in
different areas associated with different measurement nodes; that
is, a set of non-orthogonal code combinations can be re-used
between the different areas.
[0073] It is desirable to define groups such that the resulting EPS
produces a power flow at the measurement node 204 which is large
enough to be distinguished from other components making up the
total power flow at the node 204, and is detectable above the noise
of the power meter 512 etc. However, there may also be
considerations due to which it is desirable that the power flow
contribution from the group is not too large; for example, it may
be desirable to prevent the power flow contribution from becoming
so large that it interferes with readings made on measurement nodes
204 with which the group is not associated. There may also be
regulations associated with the network limiting the maximum amount
of switching that is allowable. A further factor is the length of
time over which the measurement is to be taken i.e. the time period
over which the code sequence is to be activated; a short activation
time requires a relatively large power flow amplitude in order to
be detectable, whereas if the activation time is long, a relatively
small power flow amplitude may be sufficient.
[0074] An exemplary process for allocating power flow control
devices 200 to a group will now be described. In the following
examples, the code allocation is performed at the measurement node
204; however, in some embodiments, this allocation and/or
transmission is performed by a further device, with which the node
and the devices communicate via their respective interfaces 410,
510.
[0075] In some embodiments, the power flow control devices 200 are
each registered with a measurement node 204. This registration
could be performed manually, for example via the user interface 405
of the node, and may involve the power flow control device 200
sending a signal via the communications interface 410; to this end,
the power flow control device 200 may have access to an IP address,
or other network address of the measurement node 204. Unit
information indicative of characteristics of the power unit 202
with which the power flow control device is associated may also be
provided; for example, a user may manually enter that the power
unit being controlled is a water heater, or enter an expected power
consumption of the power unit. Other unit information that may be
provided includes intervals when the associated power unit 202 is
available for measurement, and/or control without adverse
interference to the normal functioning of the device. If the user
subsequently decides to opt the power unit 202 out of measurement,
either permanently or temporarily, this information may also be
transmitted to the measurement node. When received by the
measurement node 204, such unit information is stored in the data
store 503.
[0076] It should be noted that although unit information and other
data is described above as being stored in a data store 503 located
at the measurement node 204, in some cases it may be stored in one
or more remote data stores to which the node 204 has access.
[0077] FIG. 6 is a flow diagram showing a process by which power
units are allocated to a group. At step 600, a target is set for
the power flow value at the measurement node 204 resulting from the
EPS from the group, based on the factors such as signal to noise
ratio etc. described above. At step 601 the processor 504 of the
measurement node retrieves unit information from the data store
503. This unit information is used at step 602 to define a trial
group based on e.g. the number of units selected for the group
and/or expected power consumption/provision of the selected
units.
[0078] At step 604 a code is allocated to the group and code
information is sent, using the address data mentioned above, to the
selected power flow control devices 200 via the communication
interface 510 of measurement node. The code information may contain
the code itself, or may provide an indication of a code stored in
the database 403. At step 605 an activation signal, as described
above is similarly transmitted to the selected devices; in some
embodiments, the code information is sent concurrently with the
activation signal.
[0079] At step 606 the power flow resulting from the thus define
group is measured. It may be that the power flow is different to
the expected value because, for example, one or more of the devices
is not active (e.g. a solar panel at night) or because the unit
information stored in the data store 503 is not accurate, for
example.
[0080] At step 608, it is determined whether the measured power
flow amplitude satisfies certain predefined constraints, such as
whether the measured amplitude is within an acceptable range. If
the power flow amplitude is determined to be within the range it
may be considered optimized, and the information relating to the
group so defined and the code allocated to the group is stored in
the data store 503 of the measurement node 204 at step 610.
[0081] If at step 608 the amplitude is determined not to be within
the range, the process proceeds to step 612 where the group is
redefined; in other words group membership of the trial group is
altered. After the group has been redefined, the process returns to
step 604 and sends out code information to the selected power flow
control devices 200 in the redefined group. Steps 646 to 608 are
then repeated iteratively until an optimized group is obtained.
[0082] The redefining step 612 may be performed on the basis of the
unit information mentioned above; for example, a shortfall in the
size of the measured amplitude may be compensated for by including
power units 202 having an expected power consumption/provision
totaling this shortfall. Alternatively or additionally a random
allocation technique may be employed. For example, a number of
units 202 for inclusion in the group may be selected based on the
unit information, and the devices making up that number then
selected at random. Alternatively, in some embodiments, both the
number and the identify of units 202 may be selected at random with
steps 604 to 612 being performed iteratively until an optimized
amplitude is obtained.
[0083] In some embodiments, a random allocation technique as
described above could used for each iteration of the above process,
in which case the unit information is not used in the group
allocation process.
[0084] The above-described methods of defining groups are not
exhaustive; any method resulting in groups having the desired
characteristics may be used.
[0085] As mentioned above, some power flow control devices 200 may
be associated with power units 202 whose location changes from time
to time, for example a PEV, which may change location permanently
when its owner moves house, or temporarily when the owner for
example, goes on a day trip and parks in an area different to its
usual location. Even when the PEV has only changed locations
temporarily, it may be connected to the electricity distribution
network at the temporary location, for example to recharge a
depleted battery.
[0086] When a PEV changes location, it may move from an area
associated with a first measurement node and into a different area,
specifically one associated with a node other than the first node.
This other node could be associated with the same network operator
as the first node, or it could be associated with a different
network operator. It may be convenient to communicate this change
of location to the measurement nodes affected. The PEV may be
fitted with a Global Positioning System (GPS) navigation system
which monitors the position of the PEV and transmits this position
information. In some embodiments, the position information is
transmitted directly to each measurement node 204, with each node
receiving this information then determining whether the PEV is
within its zone; in some embodiments, the PEV transmits the
information to a master node which then assigns the PEV to a node
into whose allocated area the PEV is located. To this end, the PEV
may store data indicative of a network address, such as an IP
address, of each node 204 with which it communicates. In some
embodiments, the location information may be input manually by a
user using the user interface.
[0087] The area in which the PEV is located may be determined on
the basis of input from the user, for example, the user of the PEV
can use the user interface 405 to indicate (e.g. to the master node
mentioned above) that the PEV has changed location. A code is then
assigned to the PEV for activation over a time period long enough
that the resulting EPS can be detected at one or more measurement
nodes 204. It is then determined at which measurement node 204 the
EPS is strongest, and the PEV is assigned to that measurement node
204.
[0088] The movement of the PEV between areas may necessitate a
reallocation of codes, both in the area into which it has moved and
in the area it has left. For example, the master node mentioned
above may monitor changes of area, and transmit a signal to the
first node indicating that the PEV is no longer associated with the
first node, and a further signal to the other node, indicating that
the PEV is now assigned to that node.
[0089] If only a single PEV moves into a given area, it may be that
it can be allocated to an existing group without significant
disruption to the EPS of the group. Similarly, the PEV may simply
be removed from the group to which it was assigned in the area it
has left without having to make a change to this group, if this
does not have too large an impact on the EPS from the group.
However, where the number of PEVs changing areas is large, the
movement may disrupt the EPS to an extent that the group
allocations have to be altered; the power flow amplitudes resulting
from the different groups may be monitored, with the groups being
reallocated in the case that a power flow amplitude for any group
is outside of an acceptable range, for example. The group
reallocation process may involve repeating the process described
with reference to FIG. 6.
[0090] The above processes provide a method for remotely measuring
power consumption and/or provision by one or a group of electric
devices in real time, and allowing real time monitoring of the
measurement. This clearly has wide application in the field of
power management; for example, it could be used to provide real
time information on power available to be fed back into the network
from one or more PEVs plugged in to a charging station and, for
example, or to provide a real-time measurement of the power
consumption of an individual device, such as an electric oven or a
household immersion heater.
[0091] As regards users associated with the power units 202 being
measured, it is implicit that, for their power units to be
controlled according to embodiments of the invention, they agree to
enter into a scheme by which, in the case of electric power
providers, surplus power can be fed back into the electricity
distribution network and, in the case of electric power consumers,
the devices may be remotely turned off. This may be implemented,
by, for example, a disabling signal from the measurement node 204,
or from some other location, at certain times of day, especially in
the case of for example, air conditioners and water heaters, which
may not be used at specific times of day. The energy saving thus
generated could then be made available to a utility responsible for
providing power in the electricity distribution network.
[0092] Thus, an available power may be measured for a given group
according to the above described methods; and the measured amount
offered for sale to the utility provider. If the utility provider
agrees to the purchase, the measurement node may transmit a signal
to the power flow control devices 200 of the relevant group causing
all the electricity consuming devices of the group to be switched
off, and all electricity providing devices to be switched on.
[0093] As described above, the user may specify, using the user
interface 405, a time during which it is acceptable for the power
unit 202 to be turned off. Further, in the case of a PEV moved to a
new location, the user may provide information such as an
indication of the length of time the PEV is to be located at that
location, the amount of available charge in the battery.
[0094] Information regarding the location of one or more power
units may also be used to, for example, monitor network power
consumption/provision in particular localities of the network in
order to ensure that "hot spots" of excessive power demand do not
occur.
[0095] The techniques and methods described herein may be
implemented by various means. For example, these techniques may be
implemented in hardware (one or more devices), firmware (one or
more devices), software (one or more modules), or combinations
thereof. For a hardware implementation, the apparatuses of FIGS. 4
and 5 may be implemented within one or more application-specific
integrated circuits (ASICs), digital signal processors (DSPs),
digital signal processing devices (DSPDs), programmable logic
devices (PLDs), field programmable gate arrays (FPGAs), processors,
controllers, micro-controllers, microprocessors, other electronic
units designed to perform the functions described herein, or a
combination thereof. For firmware or software, the implementation
can be carried out through modules of at least one chip set (e.g.,
procedures, functions, and so on) that perform the functions
described herein. The software codes may be stored in a data store
unit and executed by processors. The data store unit may be
implemented within the processor or externally to the processor. In
the latter case it can be communicatively coupled to the processor
via various means, as is known in the art. Additionally, the
components of the systems described herein may be rearranged and/or
complemented by additional components in order to facilitate the
achieving of the various aspects, etc., described with regard
thereto, and they are not limited to the precise configurations set
forth in the given figures, as will be appreciated by one skilled
in the art.
[0096] The above embodiments are to be understood as illustrative
examples of the invention. Further embodiments of the invention are
envisaged. For example, it is described above that a user may
interact with, and provide information to, the measurement node 204
via a user interface 405 of a power unit 202; however, in some
arrangements the user may instead interact with the node 204 using
a user interface located elsewhere, or use an internet browser to
communicate with the measurement node 204 via the internet. In some
arrangements, the communication described as being performed by a
user could instead be performed automatically, for example using a
computer algorithm which could be adapted to access the users
calendar, and/or other personal information to determine available
times of devices associated with the user, for example.
[0097] Further, it was mentioned above that a measurement node 204
may store address data indicating a network address, such as IP
address, of one or more power flow control devices 200 with which
it communicates. In some embodiments, the power flow control unit
200 may be fitted with a subscriber identity module SIM card, in
which case the address data comprises an identity number of the SIM
card, such as an MSISDN number. In some cases communications
between power flow control devices 200 and measurement nodes 204
may take place by transmission of data along the power lines
414.
[0098] In many of the above examples, it is described that the
measurement node measures an amplitude of power consumption;
however, in some cases, some other characteristic of the power flow
could be modified by the flow control devices and consequently
characterized at the measurement node; for example, complex
impedance of the power units could be used to modify the power
flow.
[0099] Further, in the embodiments discussed above, the electric
distribution network uses a single phase distribution. However, it
will be clear to the skilled person that the same principles apply
to multi-phase systems; for example, in a three phase system, the
measurement node sums the contribution for each group for each
phase and then sums over all the phases.
[0100] It is to be understood that any feature described in
relation to any one embodiment may be used alone, or in combination
with other features described, and may also be used in combination
with one or more features of any other of the embodiments, or any
combination of any other of the embodiments. Furthermore,
equivalents and modifications not described above may also be
employed without departing from the scope of the invention, which
is defined in the accompanying claims.
[0101] Numbered Clauses:
[0102] The following numbered clauses form a part of the present
disclosure and describe embodiments of the present invention.
[0103] 1. A method of controlling power flow within an electricity
distribution network, the electricity distribution network
comprising a measurement node, the measurement node being
configured to access a data store storing data indicative of one or
more predefined power flow patterns, wherein a power unit is
electrically connected to the electricity distribution network and
is configured to consume electric power from, and/or provide
electric power to, the electricity distribution network such that a
change in consumption and/or provision of electric power by the
power unit results in a change in power flow in the network, the
method comprising:
[0104] controlling power flow to and/or from the power unit in
accordance with a control sequence, such that the consumption
and/or provision of power by the power unit results in a power flow
having a said predefined power flow pattern, and a characteristic
of the power flow resulting from the unit is measurable by the
measurement node.
[0105] 2. A method according to clause 1, in which the measurable
characteristic comprises an amplitude of the power flow.
[0106] 3. A method according to either of clause 1 and clause 2,
comprising receiving a data sequence representing the control
sequence.
[0107] 4. A method according to clause 3, comprising receiving the
data sequence at the power flow control unit from the measurement
node.
[0108] 5. A method according to any preceding clause, comprising:
receiving an activation signal; and initiating the control sequence
on the basis of the received activation signal.
[0109] 6. A method according to clause 5, in which the received
activation signal specifies a time for initiating the control
sequence, and the method comprises initiating the control sequence
at the specified time.
[0110] 7. A method according to any of clauses 1 to 4, in which the
predefined power pattern resulting from the power unit comprises a
repeating pattern, and the method comprises controlling power flow
to and/or from the power unit continuously according to the
repeating pattern.
[0111] 8. A method according to any preceding clause, in which: the
control sequence represents a sequence of control signals for
controlling a switch, the switch being configured to turn power
flow to and/or from the power unit on or off in accordance with a
control signal; and the method comprises controlling the switch in
accordance with the sequence of control signals.
[0112] 9. A method according to any preceding clause, comprising
controlling an attenuator to modify power flow to and/or from the
device.
[0113] 10. A method according to any preceding clause, comprising
preventing power flow to and/or from the power unit in response to
a disabling signal.
[0114] 11. A method according to clause 10, comprising receiving
the disabling signal from the measurement node.
[0115] 12. A method according to any preceding clause, comprising:
measuring electric power consumption and/or provision at the power
unit; and sending an indication of a said measurement to the
measurement node.
[0116] 13. A method according to any preceding clause, in which the
measurement node comprises said data store.
[0117] 14. A method according to any preceding clause, in which
each of a distributed group of said power units is connected to the
electricity distribution network, and the method comprises:
controlling the power flow to and/or from the plurality of units in
accordance with the control sequence, such that the consumption
and/or provision of power by the plurality of power units is
coordinated to collectively provide a power flow having the
predefined power flow pattern and a characteristic measurable by
the measurement node.
[0118] 15. A method according to clause 14, in which a plurality of
said groups is connected to the network, and the method comprises
controlling the power flow to and/or from each said group according
to different control sequences, such that the power flow pattern
resulting from a respective group is mutually orthogonal, or
quasi-orthogonal, with respect to power flow patterns resulting
from each other said group, such that a power flow characteristic
associated with each of the power flow patterns can be measured at
the measurement node independently of each of the other
patterns.
[0119] 16. A power flow control device configured to perform the
method of any of clause 1 to clause 12.
[0120] 17. A power unit comprising a power flow control device
according to clause 16.
[0121] 18. A power unit according to clause 17, the unit comprising
position determining means for determining a position of the unit
and an interface for sending an indication of a determined position
of the mobile unit to the measurement node.
[0122] 19. A power unit according to either of clause 17 and clause
18, comprising a user interface for providing an indication of
availability of the unit for provision and/or consumption of
electric power to and/or from the electricity distribution network,
and an interface for transmitting an indication of said
availability.
[0123] 20. A method of measuring power flow in an electricity
distribution network comprising a measurement node, the electricity
distribution network being connected to a group of one or more
power units each configured to consume electric power from and/or
provide electric power to the electricity distribution network such
that a change in power provision and/or consumption by a said unit
results in a change in power flow in the network, wherein each of
the power units is associated with a respective power flow control
device configured to control power flow to and/or from a power unit
in accordance with a predefined control sequence, resulting in a
power flow having a predefined pattern, the measurement node being
configured to access a data store configured to store data
indicative of one or more said patterns, the method comprising:
measuring a signal indicative of power flowing at the measurement
node: analyzing the measured signal so as to correlate a component
thereof with a said pattern, whereby to generate one or more
correlated signals; measuring a characteristic of the one or more
correlated signals, thereby determining a contribution to said
measured signal by the group of power units.
[0124] 21. A method according to clause 20, in which the
characteristic comprises an amplitude of the power flow.
[0125] 22. A method according to clause 20 or clause 21, comprising
sending a signal specifying said control sequence to each power
unit of the group.
[0126] 23. A method according to any of clause 20 to clause 22,
comprising sending an activation signal to the power units for
activating, at a predetermined time, the control sequence.
[0127] 24. A method according to clause 23, in which said
activation signal specifies a time of activation of said control
sequence.
[0128] 25. A method according to any of clause 20 to clause 24, in
which the predefined power flow pattern comprises a repeating
pattern, and the power flow control devices are configured to
control power to and/or from the group of one or more power units
continuously according to the repeating pattern.
[0129] 26. A method according to clause 25, comprising allocating
the control sequence in accordance with a power consumption and/or
provision requirement relating to the one or more power units,
whereby to control an energy consumption and/or provision of the
power units.
[0130] 27. A method according to any of clause 20 to clause 26, in
which the electricity distribution network is connected to a
plurality of said groups, the measurement node stores data
representing a plurality of said control sequences, and data
indicating associations between the stored control sequences and
the groups, and the method comprises: correlating the measured
signal with the stored sequences, so as to identify a contribution
of a given group to the total power consumption and/or provision
within the electricity distribution network.
[0131] 28. A method according to any of clause 20 to clause 27,
comprising: receiving, from at least one of said power units, a
signal indicative of a measurement of electricity consumption
and/or provision made at the unit; comparing the received
measurement with a determined contribution relating to the unit;
and calibrating the electricity distribution node on the basis of
said comparison.
[0132] 29. A method according to any of clause 20 to clause 28, in
which the measurement node comprises said data store.
[0133] 30. A measurement node configured to perform the method of
any of clause 20 to clause 29.
[0134] 31. A computer program comprising a set of instructions
which, when executed on a processing unit, causes the processing
unit to perform the method of any of clauses 20 to 30.
[0135] 32. A method of controlling electricity flow in an
electricity distribution network, the electricity distribution
network comprising a plurality of measurement nodes and a plurality
of distributed groups of power units, each of said power units
being configured to consume and/or provide electricity associated
with the electricity distribution network, wherein each power unit
in a given group is configured to be controlled by a control
sequence assigned to the group, the control sequence controlling
power consumption and/or provision by each unit of the group
according to a predefined pattern, resulting in an associated power
flow pattern, and each of the measurement nodes being configured to
measure a characteristic of power flowing in the network associated
with the power consumption and/or provision of one or more groups,
the method comprising: assigning a plurality of said control
sequences to a first plurality of groups of units, such that a
characteristic of power flow associated with the first plurality of
groups is measurable by a first said measurement node, wherein the
assigned control sequences result in mutually orthogonal patterns
of power flow, whereby flow characteristics associated with each of
the power flow patterns can be measured at the first node
independently of each of the other patterns; assigning a further
control sequence to a further, different, group of units, such that
a characteristic of modulated power flow associated with the
further group of units is measurable by a further, different,
measurement node; and controlling consumption or provision of power
in the network in accordance with the assigned control sequences,
wherein the further control sequence corresponding to a control
sequence assigned to the first plurality of groups.
[0136] 33. A method of controlling electricity flow within an
electricity distribution network, the electricity distribution
network comprising a measurement node and a plurality of power
units, each of the power units being configured to consume and/or
provide electricity associated with the electricity distribution
network, wherein each of the power units is configured to be
controlled by an assigned control sequence, the control sequence
controlling power consumption and/or provision by the unit
according to a predefined pattern, the method comprising; assigning
group membership to a plurality of the units, thereby defining at
least one group; and assigning a said control sequence to the
group, such that each unit of the group consumes and/or provides
power in accordance with a predefined pattern corresponding to the
assigned control sequence, resulting in a modulated power flow
pattern having an characteristic measurable at the measurement
node, the method further comprising: measuring a characteristic of
the modulated power flow pattern at the measurement node; based on
the measured characteristic and one or more predefined optimization
parameters, modifying the assigned group membership; and iterating
said measurement and modification, whereby to optimize a measured
characteristic associated with the group.
[0137] 34. A method according to clause 33, in which the assignment
of group membership is based, at least in part, on a random
selection technique.
[0138] 35. A method according to either of clause 33 and clause 34,
in which the one or more optimization parameters comprise a
parameter relating to network operational requirements.
[0139] 36. A method according to any of clause 33 to clause 35, in
which the one or more optimization parameters comprise a parameter
relating to the geographical distribution of the units.
[0140] 37. A method according to any of clause 33 to clause 36, in
which characteristic measured comprises an amplitude characteristic
and the one or more parameters comprise a parameter relating to
amplitude measurement.
[0141] 38. A method according to any of clause 33 to clause 37, in
which: the electricity distribution network comprises a plurality
of said measurement nodes; and the method comprises defining a
plurality of said groups, each group being associated with a node
of the plurality of measurement nodes.
[0142] 39. A method according to clause 38, in which the one or
more predefined amplitude measurement optimization parameters
include a parameter relating to attenuation of power flow between
different nodes, and the method comprises: assigning the group
membership for a first group associated with a first said node such
that the contribution of the first group to a power flow amplitude
at a second, different node, is small compared to the total power
flow amplitude at the second node.
[0143] 40. A method according to any of clause 38 to clause 39, in
which the geographical separation of the first and second nodes is
known and the control sequence assignment is based on the
separation.
[0144] 41. A method according either of clause 39 and clause 40, in
which the network comprises a plurality of geographical areas each
associated with a said node, and in which each unit located in a
given said geographical area is associated with the node associated
with that area.
[0145] 42. A method according to clause 41, in which one or more of
the units is capable of moving between the geographical areas, and
the method comprises: monitoring a location of one or more of the
units; determining that one or more units have entered a given
geographical area; in response to said determination, associating
the one or more units with a node associated with the given area;
analyzing group membership and associated modulated power flow
patterns in the given area; and assigning group membership to the
one or more units that have entered the given geographical area on
the basis of the analysis.
[0146] 43. A method according to any of clause 33 to clause 42, in
which a plurality of groups are associated with each node, and the
method comprises assigning mutually quasi-orthogonal control
sequences to each of the groups associated with a given node.
[0147] 44. A method according to clause 43, comprising assigning,
to a group associated with a different node, a control sequence
corresponding to a control sequence assigned to a group associated
with the given node.
[0148] 45. A method according to any of clause 33 to clause 44, in
which assignment of group membership is based on availability of
one or more of the devices and the method comprises receiving an
indication of an availability of a device from a user associated
with the device.
[0149] 46. A measurement node configured to perform the method of
any of clause 32 to clause 45.
[0150] 47. A computer program comprising a set of instructions
which, when executed on a processing unit, causes the processing
unit to perform the method of any of clauses 32 to 45.
* * * * *