Grid regulation services for energy storage devices based on grid frequency

Patent metadata

Field	Value
Publication number	US-9753440-B2
Application number	US-201313909893-A
Country	US
Kind code	B2
Filing date	Jun 4, 2013
Priority date	Apr 6, 2010
Publication date	Sep 5, 2017
Grant date	Sep 5, 2017

Abstract

Disclosed herein are representative embodiments of methods, apparatus, and systems for charging and discharging an energy storage device connected to an electrical power distribution system. In one exemplary embodiment, a controller monitors electrical characteristics of an electrical power distribution system and provides an output to a bi-directional charger causing the charger to charge or discharge an energy storage device (e.g., a battery in a plug-in hybrid electric vehicle (PHEV)). The controller can help stabilize the electrical power distribution system by increasing the charging rate when there is excess power in the electrical power distribution system (e.g., when the frequency of an AC power grid exceeds an average value), or by discharging power from the energy storage device to stabilize the grid when there is a shortage of power in the electrical power distribution system (e.g., when the frequency of an AC power grid is below an average value).

First claim

We claim:

1. A method, comprising:
using a computer processor, evaluating second data representing status of an energy storage device to make a determination whether the energy storage device has adequate state of charge for a discharging operation;
if the determination indicates that the energy storage device has adequate state of charge for a discharging operation, then selecting a discharging rate proportionally scaled based on an average discharge rate for a bi-directional charging system, the discharging rate being clamped between a maximum discharging rate and a zero discharging rate for the bi-directional charging system, the selected discharging rate being based on an average load rate for the bi-directional charging system and on first data representing one or more electrical characteristics of an electrical power distribution system, the bi-directional charging system being operable to charge or discharge the energy storage device; and
generating a regulation signal for causing the bi-directional charging system to discharge the energy storage device, the regulation signal being based at least in part on the selected discharging rate.

2. The method of claim 1 , wherein the first data includes frequency data representing an instantaneous frequency measurement of the electrical power distribution system.

3. The method of claim 2 , further comprising computing an average frequency from the frequency data.

4. The method of claim 1 , further comprising generating a regulation signal for causing the bi-directional charging system to charge the energy storage device, the regulation signal being based at least in part on the selected discharging rate.

5. The method of claim 1 , wherein the first data includes frequency data representing an instantaneous frequency of the electrical power distribution system and an average frequency of the electrical power distribution system.

6. The method of claim 1 , further comprising receiving the second data representing the status of the energy storage device.

7. The method of claim 6 , wherein the second data includes data representing a state-of-charge of the energy storage device.

8. The method of claim 1 , further comprising receiving third data representing a desired final charging time, and wherein the selecting is further based, at least in part, on the third data.

9. The method of claim 1 , further comprising receiving an upper frequency parameter defining an over-frequency event of the electrical power distribution system, a lower frequency parameter defining an under-frequency event of the electrical power distribution system, and wherein the selecting is based at least in part on one or more of the upper frequency parameter or the lower frequency parameter.

10. The method of claim 1 , wherein the second data includes data representing an actual charging or discharging rate of the energy storage device.

11. The method of claim 1 , further comprising discharging the energy storage device responsive to the regulation signal, thereby transmitting power to the electrical power distribution system.

12. The method of claim 1 , wherein the energy storage device comprises a battery in an electric vehicle or a plug-in hybrid electric vehicle.

13. The method of claim 1 , wherein the energy storage device comprises a stationary power source, pumped water storage, a flywheel, or a battery-supplemented photovoltaic power system.

14. The method of claim 1 , wherein the first data includes voltage data representing an operating voltage of the electrical power distribution system.

15. The method of claim 1 , further comprising clamping the discharging rate below a first selected charging rate or above a second selected charging rate, wherein the first and second selected charging rates are selected in response to a pre-determined or user-selected completion time for charging the energy storage device.

16. One or more non-transitory computer-readable storage media storing computer-readable instructions that when executed by a computer cause the computer to perform a method, the method comprising:
selecting an upper charge rate limit and a lower charge rate limit based on an actual charging rate of an energy storage device coupled to discharge electrical power to an electrical power distribution system via a bi-directional charging system;
selecting a discharging rate from a range of two or more discharging rates between the selected upper charge rate limit and the selected lower charge rate limit based on first data representing one or more electrical characteristics of an alternating current (AC) electrical power distribution system; and
generating a regulation signal for causing the bi-directional charging system to discharge the energy storage device, the regulation signal being based at least in part on the selected discharging rate.

17. The computer-readable storage media of claim 16 , wherein the first data includes frequency data representing an instantaneous frequency of the electrical power distribution system.

18. The computer-readable storage media of claim 17 , wherein the selecting comprises computing a difference between the instantaneous frequency and an average of previously received instantaneous frequency data.

19. The computer-readable storage media of claim 16 , wherein the selecting comprises:
computing an average of previously received data representing one or more electrical characteristics;
computing a difference between the received data and the average;
if the difference indicates that the electrical power distribution system has excess energy, selecting a charging rate to charge the energy storage device; and
if the difference indicates that the electrical power distribution system has a shortage of energy, selecting the discharging rate to discharge the energy storage device.

20. The computer-readable storage media of claim 16 , wherein the method further comprises generating a regulation signal for causing the bi-directional charging system to charge the energy storage device, the regulation signal being based at least in part on the selected discharging rate.

21. The computer-readable storage media of claim 16 , wherein the selecting is based, at least in part, on a state-of-charge of the energy storage device.

22. The computer-readable storage media of claim 16 , wherein the selecting is based, at least in part, on a desired final charging time for the energy storage device.

23. The computer-readable storage media of claim 16 , wherein the method further comprises receiving an upper frequency parameter defining an over-frequency event of the electrical power distribution system, a lower frequency parameter defining an under-frequency event of the electrical power distribution system, and wherein the selecting is based at least in part on one or more of the upper frequency parameter and the lower frequency parameter.

24. The computer-readable storage media of claim 16 , wherein the method further comprises discharging the energy storage device responsive to the regulation signal, thereby transmitting power to the electrical power distribution system.

25. The computer-readable storage media of claim 16 , wherein the method further comprises clamping the discharging rate above a selected discharging rate, wherein the selected charging rate is selected in response to a pre-determined or user-selected completion time for charging the energy storage device.

Assignees

• Battelle Memorial Institute

Inventors

• Pratt Richard M
• Hammerstrom Donald J
• Kintner-Meyer Michael C W
• Tuffner Francis K

Classifications

• H02J13/00

  Circuit arrangements for providing remote monitoring or remote control of equipment in a power distribution network · CPC title

• B60L53/56

  Mechanical storage means, e.g. fly wheels · CPC title

• B60L53/53

  Batteries · CPC title

• B60L55/00

  Arrangements for supplying energy stored within a vehicle to a power network, i.e. vehicle-to-grid [V2G] arrangements · CPC title

• B60L53/63

  in response to network capacity · CPC title