Methods, systems and apparatus for regulating frequency of generated power using flywheel energy storage systems with varying load and/or power generation

• US 8,008,804 B2
• Filed: 08/16/2004
• Issued: 08/30/2011
• Est. Priority Date: 08/15/2003
• Status: Active Grant

• Current Assignee: Beacon Power (RGA Labs, Inc.)
• Original Assignee: Beacon Power Corporation (RGA Labs, Inc.)
• Inventors: Lazarewicz, Matthew L., Arseneaux, A. James, Capp, F. William, Rojas, Hernan Alex, Dresens, Paul
• Primary Examiner(s): Fureman; Jared J
• Assistant Examiner(s): Parries; Dru M
• Application Number:
  US10/920,146
• Publication Number:
  US 20050077881A1
• Time in Patent Office: 2,570 Days
• Field of Search: 307/80, 307/85, 307/44
• US Class Current: 307/44
• CPC Class Codes: H02J 3/30 using dynamo-electric machines coupled to flywheels
• CPC Class Codes: Y02E 60/16 Mechanical energy storage, e.g. flywheels or pressurised fluids

Abstract

Featured are methods for regulating the AC frequency of the electrical power be supplied on an electrical distribution system or grid. Such a method includes electrically coupling an energy storage sub-system to the electrical distribution network, where the energy storage sub-system includes one or more flywheel energy storage systems. Also featured as devices, systems and apparatuses embodying such methodologies or for use in implementing such methodologies of the present invention.

Claims

1. In the operation of an electrical utility system having a power distribution grid, said power distribution grid including a plurality of electrical generation facilities and a plurality of electrical loads, which power distribution grid operates based on a conventional method, for regulating AC frequency of electrical power being distributed through said power distribution grid, the frequency regulation method comprising:

configuring said power distribution grid to interconnect said plurality of electrical power generation facilities with one another such that power generated from every one of the power generation facilities is combined, through said grid, to provide said electrical power as a total generated power for distribution, through said grid, to said plurality of electrical loads, and each of said loads exhibits an individual load requirement that varies with time, throughout a given day, at least somewhat independently of at least a number of other ones of said loads, such that all of said loads are combined with one another, through said grid, to define a total system load requirement that varies throughout said given day, and the variation of said total system load requirement includes long term variations defining a daily load curve, and short term variations that fluctuate rapidly, as compared with said long term variations, and at least some of the power generation facilities are adjustable for one of increasing and decreasing said power generated thereby, and each of these adjustable generation facilities exhibits a time lag associated with any adjustment of the power generated thereby, and at least a subset of said adjustable power generation facilities are configured to cooperate with one another for providing an adjustment to said total generated power for at least approximately following said daily load curve, and said adjustment of said total generated power, for following the daily load curve, exhibits a response time, based at least in part on the time lags associated with at least a subset of said adjustable power generation facilities, that is sufficiently long, as compared with at least some of said short term variations, so as to limit an ability of the adjustable power generation facilities to follow the short term variations of said total system load such that said power distribution grid is at least frequently challenged with a conventional mismatch that is caused at least in part by a power difference between said total generated power and said total system load requirement, said power difference having a magnitude that exhibits fluctuations that cause said mismatch to exhibit corresponding fluctuations, at least some of said fluctuations of said power difference being caused by combined variations of a multiplicity of said individual electrical loads, and not by the variation of any single one of said electrical loads, and said independence of the time variations of the individual load requirements causes said fluctuations of said mismatch to be at least generally stochastic such that at least some of the fluctuations of said mismatch are at least generally independent of and uncorrelated with respect to the long term variations of said total load requirement, and

repeatedly, throughout said given day, adjusting the total generated power for at least approximately following the long term variations of said total system load, and for attempting to follow said fluctuations of said mismatch, by

(i) monitoring said power distribution grid, at each one of a series of monitoring times throughout said given day, for at least approximately characterizing said mismatch at that time, and

(ii) for at least some of said monitoring times throughout said given day at least partially compensating for said mismatch, responsive to said monitoring thereof, to regulate said AC frequency, in a conventional way, by adjusting the total power generated such that said AC frequency is caused to fall within a conventional range of a desired frequency value at least during an interval of time that is initiated by said adjustment,

a modified method for use in conjunction with said conventional method, said modified method comprising;

providing at least one flywheel energy storage system, said flywheel energy storage system having a power capacity that is at least sufficient for influencing the regulating of said AC frequency of said power distribution grid,

electrically coupling the flywheel energy storage system to said power distribution grid, and for at least a number of said monitoring times controlling said flywheel energy storage system, responsive to said monitoring of said mismatch, to further compensate for said mismatch by a selected one of (a) adding power from the flywheel energy storage system to the power distribution grid, and (b) absorbing power by the flywheel energy storage system and from the power distribution grid, such that said flywheel energy storage system provides supplemental regulating of said AC frequency, in addition to said conventional regulating, and with a faster response as compared with the response time of said subset of adjustable power generation facilities.

2. The method of claim 1 wherein the short term variations in said total system load cause said fluctuations of said mismatch to include corresponding short term fluctuations and, at least for some of said number of said monitoring times throughout the given day, the limited response time for adjustment of said total generated power correspondingly limits said attempts to follow the short term fluctuations of said mismatch such that based on said conventional regulation of said AC frequency, the mismatch includes a conventional remaining portion that exhibits at least some of said short term fluctuations, and

said stochastic characteristic of said fluctuations in said mismatch causes said short term fluctuations of the conventional remaining portion of said mismatch to exhibit a corresponding stochastic characteristic,

and as part of said modified method, for at least one of said number of monitoring times,

(a) monitoring said power distribution grid includes at least approximately characterizing said conventional remaining portion of said mismatch,

(b) controlling the flywheel energy storage system includes performing said selecting responsive to said characterizing, and

(c) for the selection of adding power, specifying a determined amount of power to be added to said power distribution grid, based at least in part on said characterizing of said conventional remaining mismatch, to at least partially compensate for said conventional remaining mismatch, and at least partially compensating for said conventional remaining mismatch by adding the determined amount of power from the flywheel energy storage system to the power distribution grid, and

(d) for the selection of absorbing power, specifying a determined amount of power to be absorbed from the power distribution grid, based at least in part on said characterizing of said conventional remaining mismatch, to at least partially compensate for said remaining mismatch, and at least a partially compensating for said conventional remaining mismatch by absorbing the determined amount of power from the distribution grid.

3. The method of claim 2 wherein providing said supplemental regulation of said AC frequency includes at least attempting to follow said short term fluctuations of said conventional remaining portion of said mismatch, by performing steps (a)-(d) for each one of said number of monitoring times.

4. The method of claim 3 including providing a set of power correction signals, responsive to said monitoring of said mismatch, for at least some of said monitoring times and based at least in part on said mismatch, such that each one of said power correction signals can at least to some extent control at least a corresponding one of said adjustable power generation facilities, and configuring said power distribution grid includes configuring each one of the subset of adjustable power generation facilities for receiving the corresponding one of said power correction signals, and adjusting the total generated power includes controlling each one of the subset of adjustable power generation facilities, responsive to its corresponding power correction signal, such that at least some of the power generation facilities, in that subset, cooperate with one another for following said long term variations and for attempting to follow said fluctuations of said mismatch, and in said modified method:

responding to said monitoring by determining a requirement for one of the selection of adding and the selection of absorbing and evaluating the determined amount of power for the selected one of said adding and absorbing,

providing said power correction signal includes providing a particular power correction signal, based at least in part on said monitoring at each of said number of monitoring times, and assigning thereto a signal characteristic that can be interpreted for specifying (a) said requirement for one of the selection of adding and the selection of absorbing, and (b) the determined amount of power for the selected one of said adding and said absorbing, and

configuring the flywheel energy storage system includes arranging the flywheel energy storage system for receiving at least the particular one of said power correction signals, wherein

responding to said monitoring further includes interpreting said characteristic of the particular power correction signal as specifying (a) the requirement for the selecting of one of adding and absorbing, and (b) the determined amount of power for the selected one of said adding and said absorbing.

5. The method of claim 4 wherein providing the particular power correction signal includes producing the particular power correction signal as a regulation signal, and assigning includes designating a value for said regulation signal as said characteristic to be interpreted for said specifying of (a) the requirement for the selection of one of said adding and said absorbing, and the (b) determined amount of power for the selected one of said adding and said absorbing, such that the interpretation of a positive value of the regulation signal specifies the requirement for the selection to add power to the power distribution grid, and the interpretation of a negative value of the regulation signal specifies the requirement for the selection to absorb power, and designating the value of the regulation signal includes assigning a magnitude thereto such said interpretation of said magnitude specifies the determined amount of power for the selected one of said adding and said absorbing.

6. The method of claim 4 wherein said modified method includes customizing the particular power correction signal for use as a customized flywheel power correction signal for controlling one or more of said flywheel energy storage systems, and

providing said flywheel energy storage system includes arranging an array of one or more energy storage flywheels in electrical communication with a flywheel array controller and configuring the flywheel array controller for (a) receiving the customized flywheel power correction signal and (b) controlling each of the energy storage flywheels in the array, responsive to said customized flywheel power correction signal, to produce said responsiveness with respect to the monitoring of said mismatch.

7. The method of claim 6 wherein customizing the particular power correction signal includes producing the customized flywheel power correction signal as a regulation signal for regulating said flywheel energy storage system, and assigning includes designating a signal value to said customized flywheel regulation signal, as said signal characteristic that is interpretable for said specifying of (a) said requirement for the selection of one of adding and absorbing, and (b) the determined amount of power for the selected one of said adding and said absorbing, such that the interpretation of a positive signal value specifies the requirement for said selection to add power to the power distribution grid, and the interpretation of a negative signal value specifies the requirement for said selection to absorb power, and said designating further includes assigning a magnitude to said signal value such that the interpretation of the magnitude specifies the determined amount of power for the selected one of said addition and said absorption.

8. The method of claim 7 including configuring said flywheel energy storage system for multimode operation such that said power capacity thereof can be provided by (a) operation in a power generating mode, for said adding of power from said flywheel energy storage system to said power distribution grid, within a first predetermined range of power levels up to a maximum addable electrical power that can be added to said grid by said flywheel energy storage system, (b) operation in a charging mode, for said absorbing of power from said power distribution grid, within a second predetermined range of power levels up to a maximum absorbable electrical power that can be absorbed by the flywheel energy storage system, and at any given time during at least a portion of said given day, said flywheel energy storage system stores an amount of energy, and configuring includes arranging the flywheel energy storage system such that operation in said power generating mode causes the amount of stored energy to decrease and operation in said charging mode causes the amount of stored energy to increase, and said flywheel energy storage system exhibits an energy storage capacity as a maximum amount of stored energy that is sufficient for providing said power capacity by handling, at least throughout each interval of time after at least some of said monitoring times, said maximum amount of electrical power for the selected one of said adding and said absorbing during that interval of time,

wherein assigning the signal value of said customized flywheel regulation signal includes designating the signal value to fall within a range that is delimited by an upper, positive limit and a lower, negative limit, such that the interpretation of a signal value corresponding to the upper positive limit specifies the requirement for the selection to add a predetermined percentage of the maximum addable power as the determined amount of power to be added, and the interpretation of a signal value corresponding to the lowest negative limit specifies the requirement for the selection to absorb a predetermined percentage of the maximum absorbable power as the determined amount of absorbed power.

9. The method of claim 4 wherein configuring the power distribution grid includes (i) locating different ones of the power generation facilities apart from one another at different generator locations in a regional control area, (ii) locating different ones of the loads apart from one another and apart from the power generation facilities, at different load locations within the regional control area, and (iii) providing a network of power lines, as part of said grid, and arranging all of the power lines to cooperate with one another for delivering said total generated power, from said generator locations to said load locations, through the network of power lines, each one of which power lines exhibits an associated line loss, and providing the particular power correction signal includes producing the particular power correction signal, based on said monitoring of said mismatch, at a regional dispatching center having a dispatch location within said electrical power distribution grid, and configuring the power distribution grid includes arranging at least some of said power lines to define a plurality of nodes such that each node serves as an interconnection point for two or more of said power lines and each node is located at a node location, and as part of said modified method, electrically coupling includes locating the flywheel energy storage system at a particular storage system location that at least generally corresponds to a specific one of the node locations and electrically coupling the flywheel energy storage system with that specific node, and wherein the specific node location is sufficiently remote from said dispatch center with one or more of said nodes connectably disposed therebetween, such that no single power line directly connects said dispatch center with said flywheel energy storage system.

10. The method of claim 9 wherein said monitoring includes measuring electrical data, at each of said monitoring times at one or more of said nodes, and electrically communicating said electrical data to said regional dispatch center for reception thereby, and processing said electrical data at said regional dispatching center for producing the particular power correction signal responsive to said electrical data such that said electrical data influences the responsiveness of the flywheel energy storage system.

11. The method of claim 10 wherein processing said electrical data at each of said monitoring times includes evaluating an ACE score associated with the operation of said power distribution grid and providing the particular power correction signal includes basing the particular power correction signal, at least in part, on said ACE score.

12. The method of claim 11 wherein for each of said monitoring times evaluating the ACE score includes designating a scheduled net interchange for said power distribution grid, and said monitoring includes interpreting said electrical data for at least approximately characterizing an actual net interchange, and evaluating the ACE score further includes basing the ACE score at least in part on a comparison between the scheduled net interchange and the actual net interchange.

13. The method of claim 11 wherein for each of said monitoring times evaluating the ACE score includes designating a scheduled AC frequency for electrical power that is to be distributed at least throughout portions of said power distribution grid, and said monitoring includes interpreting said electrical data for at least approximately characterizing an actual AC frequency for electrical power that is distributed throughout said portions of the power distribution grid, and evaluating the ACE score further includes basing the ACE score at least in part on a comparison between the scheduled time error and the actual time error.

14. The method of claim 11 wherein for each of said monitoring times evaluating the ACE score includes designating a scheduled time error for said power distribution grid, and said monitoring includes interpreting said electrical data for at least approximately characterizing an actual time error, and evaluating the ACE score further includes basing the ACE score at least in part on a comparison between the scheduled time error and the actual time error.

15. The method of claim 11 wherein evaluating said ACE score includes designating a manual error adjustment and basing said ACE score at least in part on said manual error adjustment.

16. The method of claim 10 wherein for each of said monitoring times producing the particular power correction signal includes designating a scheduled net interchange for said power distribution grid, and said monitoring includes interpreting said electrical data for at least approximately characterizing an actual net interchange, and producing the particular power correction signal further includes basing the particular power correction signal at least in part on a comparison between the scheduled net interchange and the actual net interchange.

17. The method of claim 10 wherein for each of said monitoring times producing the particular power correction signal includes designating a scheduled AC frequency for electrical power that is to be distributed at least throughout portions of said power distribution grid, and said monitoring includes at interpreting said electrical data for least approximately characterizing an actual AC frequency for electrical power that is distributed throughout said portions of the power distribution grid and producing the particular power correction signal further includes basing the particular power correction signal at least in part on a comparison between the scheduled net interchange and the actual net interchange.

18. The method of claim 10 wherein for each of said monitoring times producing the particular power correction signal includes designating a scheduled time error for said power distribution grid, and said monitoring includes interpreting said electrical data for at least approximately characterizing an actual time error, and producing the particular power correction signal further includes basing the particular power correction signal at least in part on a comparison between the scheduled time error and the actual time error.

19. The method of claim 1 including configuring said flywheel energy storage system for multimode operation such that said power capacity thereof can be provided by (a) operation in a power generating mode, for said adding of power from said flywheel energy storage system to said power distribution grid, within a first predetermined range of power levels up to a maximum addable electrical power that can be added to said grid by said flywheel energy storage system, (b) operation in a charging mode, for said absorbing of power from said power distribution grid, within a second predetermined range of power levels up to a maximum absorbable electrical power that can be absorbed by the flywheel energy storage system, and at any given time during at least a portion of said given day, said flywheel energy storage system stores an amount of energy, and configuring includes arranging the flywheel energy storage system such that operation in said power generating mode causes the amount of stored energy to decrease and operation in said charging mode causes the amount of stored energy to increase, and said flywheel energy storage system exhibits an energy storage capacity as a maximum amount of stored energy that is sufficient for providing said power capacity by handling, at least throughout each interval of time after at least some of said monitoring times, the maximum amount of electrical power for the selected one of said adding and said absorbing during that interval of time.

20. The method of claim 19 wherein configuring said flywheel energy storage system for multimode operation further includes configuring the flywheel energy storage system for operation in a standby mode, in which standby mode said flywheel energy storage system performs neither one of said adding and said absorbing, at least to within an approximation, and at other ones of said monitoring times, during which other times neither one of said adding and said absorbing is selected, controlling said flywheel energy storage system responsive to said monitoring of said mismatch includes operating said flywheel energy storage system in said standby mode.

21. The method of claim 1 including providing a set of power correction signals, responsive to said monitoring of said mismatch, for at least some of said monitoring times and based at least in part on said mismatch, such that each one of said power correction signals can at least to some extent control at least a corresponding one of said adjustable power generation facilities, and configuring said power distribution grid includes configuring each one of the subset of adjustable power generation facilities for receiving the corresponding one of said power correction signals, and adjusting the total generated power includes controlling each one of the subset of adjustable power generation facilities, responsive to its corresponding power correction signal, such that at least some of the power generation facilities, in that subset, cooperate with one another for following said long term variations and for attempting to follow said fluctuations of said mismatch, and as part of said modified method:

providing said power correction signals further includes providing a particular power correction signal, based at least in part on said monitoring at each of said number of monitoring times, and providing the flywheel energy storage system includes configuring the flywheel energy storage system to receive at least the particular power correction signal, and to respond to the particular power correction signal to produce said responsiveness with respect to the monitoring of said mismatch.

22. The method of claim 21 wherein said monitoring includes at least approximately evaluating operation of the power distribution grid, at each of said monitoring times, based on a specific one of three operating states including a state of over generation wherein the total generated power exceeds the total system load, a state of under generation wherein the total system load exceeds the total generated power, and a balanced state wherein the total generated power and the total system load are at least approximately balanced;

and

(a) at least for said number of said monitoring times, providing the particular power correction signal includes generating the particular power correction signal based at least in part on said approximate evaluating, such that

(i) for each one of a first subset of said number of monitoring times established by evaluating that grid operation at that monitoring time is in the state of over generation, assigning to the particular power correction signal a signal characteristic that can be interpreted for specifying a determined amount of excess generated power to be absorbed from the power distribution grid, by the flywheel energy storage system, for providing said flywheel frequency regulating, and

(ii) for each one of a second subset of said number of monitoring times established by evaluating that grid operation at that monitoring time is the state of under generation, assigning to the particular power correction signal a signal characteristic that can be interpreted for specifying a determined amount of excess load power to be added to the power distribution grid, by the flywheel energy storage system, for providing said flywheel frequency regulating, and

(b) as part of controlling the flywheel energy storage system, for each one of the number of monitoring times, responding to the particular power correction signal includes basing the absorbed power and the added power on the particular power correction signal such that

(i) for at least one of the first subset of monitoring times, each corresponding to evaluating that grid operation at that monitoring time is in the state of over generation, controlling the flywheel energy storage system includes responding to the particular power correction signal by interpreting the signal characteristic to specify the determined amount of power to be absorbed from the power distribution grid, and performing said absorbing through operating the flywheel energy system in a charging mode, associated with the state of over generation, in which mode said flywheel energy storage system absorbs approximately the determined amount of excess power, from said grid during at least part of a corresponding one of the intervals after each monitoring time of said first subset of monitoring times,

(ii) for at least one of the second subset of the number of monitoring times, each corresponding to evaluating that grid operation at that monitoring time is the state of under generation, controlling the flywheel energy storage system includes responding to the particular power correction signal by interpreting the signal characteristic to specify the determined amount of power to be added to the grid, and performing said adding through operating said flywheel in a power generation mode, associated with the state of under generation, in which mode said flywheel energy storage system adds approximately the determined amount of excess load power, to said grid, during at least part of a corresponding one of the intervals after each monitoring time of said second subset of monitoring times.

23. The method of claim 22 wherein controlling the flywheel energy storage system for the balanced state of operation includes operating the flywheel energy storage system, responsive to the particular power correction signal, in a standby mode, associated with the balanced state.

24. The method of claim 22 wherein providing said supplemental regulation of said AC frequency includes following said fluctuations of said mismatch by performing steps (a) and (b) for each one of said number of monitoring times.

25. The method of claim 24 wherein, at a current one of the number of monitoring times, the power distribution grid is in a current one of the three states, at least based on the approximate evaluation, and the power distribution grid remains in said current state for a finite length of time, and after that finite length of time, the mismatch causes operation of the distribution grid to change from the current state to a new state that is a different one of the three states, and

the stochastic characteristic of said fluctuations of said mismatch causes a sufficient degree of randomness with respect to the state of the power distribution grid such that said finite length of time is at least generally unpredictable and at least in some cases of said change, from the current state to the new state, that are caused by an associated one of said fluctuations of said mismatch, the new state is at least generally unpredictable, and

providing the particular power correction signal includes (a) at an additional monitoring time after said finite length of time, performing an additional evaluation of the state of operation of the power distribution grid for determining that the state of operation of the power distribution grid has changed in said unpredictable way, responsive to a particular fluctuation of said mismatch, to said new state and (b) responsive to the additional evaluation of the new state of operation of the power distribution grid, modifying said signal characteristic of said particular power correction signal for providing an additional particular power correction signal having a new signal characteristic assigned thereto based on the additional evaluation of the new state of said power distribution grid,

wherein for the change in the state of operation of the power distribution grid, caused by the associated fluctuation of said mismatch, said modified method further comprises additionally responding to the additional evaluation for providing additional flywheel regulating of said AC frequency by operating the flywheel energy storage system for following the associated fluctuation of the mismatch responsive to the modification of the particular power correction signal in part by correspondingly modifying the mode of operation of the flywheel energy storage system, from the flywheel system operating mode associated with said current state, to a new flywheel system operating mode that is associated with the new state such that for an additional interval of time, after the additional monitoring time, such that the flywheel energy storage system operates in the new flywheel system operating mode.

26. The method of claim 25 including following said fluctuations of said mismatch by repeatedly performing said additional monitoring and repeatedly changing said signal characteristic of the particular power correction signal responsive thereto, and repeatedly responding to each change in said characteristic of said power correction signal.