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

• US 9,065,295 B2
• Filed: 07/28/2011
• Issued: 06/23/2015
• Est. Priority Date: 08/15/2003
• Status: Active Grant

• Current Assignee: Beacon Power (RGA Labs, Inc.)
• Original Assignee: Beacon Power (RGA Labs, Inc.)
• Inventors: Capp, F. William, Lazarewicz, Matthew L., Arseneaux, A. James, Dresens, Paul, Rojas, Hernan Alex
• Primary Examiner(s): Barnie, Rexford
• Assistant Examiner(s): VU, TOAN T
• Application Number:
  US13/193,319
• Publication Number:
  US 20110278853A1
• Time in Patent Office: 1,426 Days
• Field of Search: 307/44
• US Class Current: 1/1
• 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 to 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. A method for controlling AC frequency of electrical power being distributed to a power distribution grid, wherein the power distribution grid includes a plurality of electrical loads interconnected with a plurality of power generation facilities, and wherein a power generated by at least one of the plurality of power generation facilities is being adjusted, based on a grid parameter, to control the AC frequency, the frequency control method comprising the steps of:

electrically coupling an energy storage subsystem to the power distribution grid, said energy storage sub system comprising a plurality of flywheel energy storage systems;

receiving a signal that depends on the grid parameter, wherein the signal specifies an amount of electrical power to be added to the power distribution grid from the energy storage subsystem or absorbed from the power distribution grid by the energy storage subsystem, the amount being an amount established to regulate the AC frequency of the electrical power on the power distribution; and

controlling, by an array controller and based on the received signal, the plurality of flywheel energy storage systems so the energy storage sub-system adds the amount of electrical power when the received signal indicates that electrical power is to be added to the power distribution grid and absorbs the amount of electrical power when the received signal indicates that electrical power is to be absorbed from the power distribution grid.

2. The method of claim 1, further comprising:

monitoring the grid parameter; and

generating the signal, wherein the signal depends on the grid parameter.

3. The method of claim 1, wherein the grid parameter comprises at least one selected from a group consisting of:

load imposed on the grid, power generated by the plurality of power generation facilities, grid frequency, time error, and area control error.

4. The frequency regulation method of claim 1, wherein said electrically coupling further includes electrically coupling another energy storage sub-system to the power distribution grid comprising another plurality of flywheel energy storage systems controlled by another array controller.

5. The frequency regulation method of claim 1, wherein the plurality of flywheel energy storage systems includes 10 or more flywheel energy storage systems.

6. The AC frequency control method of claim 1, wherein said controlling further includes controlling the operation of the each of the plurality of flywheel energy storage systems so that the amount of electrical power that is specified by the received signal is repeatedly absorbed by, and discharged from, the plurality of flywheel energy storage systems responsive to the received signal.

7. The AC frequency control method of claim 6, wherein the received signal is updated at least once every 2 seconds.

8. The AC frequency control method of claim 6, wherein the received signal is updated at least once every 4 seconds.

9. The frequency control method of claim 1, wherein moment-to-moment fluctuations of loads and unintended fluctuations in generation of electrical power vary continuously and frequently thereby producing a frequently changing excess of power delivery and a short fall of power delivery.

10. The frequency control method of claim 1, wherein the signal is generated at a location that is remote from a site where the plurality of flywheel energy storage systems are electrically coupled to the power distribution grid.

11. The frequency control method of claim 10 wherein the signal is transmitted over a communications link.

12. The frequency control method of claim 11, wherein the communications link is a communications network.

13. The frequency control method of claim 10, wherein the signal is generated by a dispatcher and is transmitted to the array controller.

14. The frequency control method of claim 10, wherein the signal is generated by an agent and is transmitted to the array controller.

15. The frequency control method of claim 10, wherein the signal is generated by a system operator and is transmitted to the array controller.

16. The method for controlling AC frequency of claim 1, wherein the controlling further comprises:

evaluating, by the array controller, a plurality of operating voltages comprising an operating voltage of each of the plurality of flywheel energy storage systems to determine a synchronization state of the plurality of operating voltages;

determining, by the array controller, a corrected voltage signal required to synchronize each of the plurality of flywheel energy storage systems;

outputting, from the array controller, the corrected voltage signal to at least one flywheel energy storage system of the plurality of flywheel energy storage systems to adjust a motor/generator system of the at least one flywheel energy storage system to synchronize the operating voltage of each flywheel of the plurality of flywheel energy storage systems.

17. The method of claim 16, wherein the motor/generator system is configured to act as either an electric motor or an electric generator depending on a sign of the received signal.

18. The method of claim 1, wherein the controlling the plurality of flywheel energy storage systems based on the received signal comprises:

generating the amount of electrical power that is to be added to the power distribution grid by;

converting to DC a plurality of AC flywheel operating powers;

combining the plurality of converted AC flywheel operating powers on a common DC bus to generate a common DC operating power; and

outputting the common DC operating power to a power conditioning module;

converting, by the power conditioning module, the common DC operating power to an output AC operating power that corresponds to the amount of electrical power that is added to the grid.

19. The frequency control method of claim 1, wherein the signal is generated at a different location from the energy storage sub-system.

20. The frequency control method of claim 1, wherein the signal is generated at a control location.

21. The method of claim 1, further comprising:

obtaining an operational parameter associated with the plurality of flywheel energy storage systems and transmitting the operational parameter to a party that generates the signal.

22. The method of claim 21, wherein the operational parameter is obtained by the array controller before it is transmitted.

23. The method of claim 21, wherein the array controller accumulates a plurality of operational parameters before transmitting.

24. The method of claim 21, wherein the operational parameter is transmitted to the party from each flywheel energy storage system of the plurality of flywheel energy storage systems.

25. The method of claim 1, wherein

when the signal is greater than zero, electrical power is to be added to the power distribution grid;

and

when the signal is less than zero, electrical power is to be absorbed from the power distribution grid.

26. The method of claim 1, wherein the signal depends on a set point that depends on a maximum amount of energy that the energy storage subsystem can absorb from, or add to, the power distribution grid.

27. The method of claim 1, wherein the grid parameter comprises load imposed on the grid and power generated by the plurality of power generation facilities.

28. The method of claim 1, wherein the grid parameter comprises grid frequency.

29. The method of claim 1, wherein the controlling the plurality of flywheel energy storage systems based on the received signal comprises:

generating the amount of electrical power that is to be added to the power distribution grid by;

combining a plurality of AC flywheel operating powers on a common AC bus to generate a common output AC operating power that corresponds to the amount of electrical power that is added to the grid.

30. The frequency control method of claim 1, further comprising:

receiving, by the array controller and from a plurality of flywheel controllers, output signals representative of monitored operational parameters of each of the plurality of flywheel energy storage systems; and

communicating the received output signals to a remotely located monitoring site.

31. A method for controlling AC frequency of electrical power being distributed via a power distribution grid, wherein the power distribution grid includes a plurality of electrical loads interconnected with a plurality of power generation facilities and wherein time varying fluctuations of the plurality of electrical loads and the plurality of power generation facilities cause time varying power short falls and power excesses on the power distribution grid, the frequency control method comprising the steps of:

monitoring a grid parameter;

generating, based on the monitored grid parameter, a signal for controlling operation of a plurality of flywheel energy storage systems, wherein the signal specifies an amount of power that is to be selectively delivered to, or absorbed from, the power distribution grid, the amount being established so that when the amount is delivered to or absorbed from the power distribution grid, the AC frequency of the electrical power on the power distribution grid is regulated; and

causing, based on the signal, each of the flywheel energy storage systems to deliver the amount of electrical power to the power distribution grid when the signal is a control signal to deliver electrical power to the power distribution grid and causing each of the flywheel energy storage systems to absorb the amount of electrical power from the power distribution grid when the signal is a control signal to absorb electrical power from the power distribution grid.

32. The frequency control method of claim 31, wherein said causing further includes causing the plurality of flywheel energy storage systems to repeatedly absorb and discharge the amount of electrical power responsive to the received signal.

33. The frequency control method of claim 32, wherein the received signal is updated at least once every 2 seconds.

34. The frequency control method of claim 32, wherein the received signal is updated at least once every 4 seconds.

35. The frequency control method of claim 31, further comprising transmitting the signal over a communications link.

36. The frequency control method of claim 35, wherein the communications link is a communications network.

37. The method of claim 31, further comprising receiving an operational parameter associated with the plurality of flywheel energy storage systems and generating the signal based on the operational parameter.

38. The method of claim 37, wherein the operational parameter is obtained by an array controller before it is transmitted.

39. The method of claim 38, wherein the array controller accumulates a plurality of operational parameters before transmitting.

40. The method of claim 37, wherein the operational parameter is transmitted by each flywheel of the plurality of flywheel energy storage systems.

41. The method of claim 31, wherein the grid parameter comprises at least one selected from a group consisting of load imposed on the grid, power generated by the plurality of power generation facilities, grid frequency, time error, and area control error.

42. An AC frequency regulation system for regulating AC frequency of electrical power being distributed to a power distribution grid that includes a plurality of electrical loads interconnected with a plurality of power generation facilities, wherein time varying fluctuations of the plurality of electrical loads and the plurality of power generation facilities cause time varying power short falls and power excesses on the power distribution grid, said system comprising:

a plurality of flywheel energy storage systems, the plurality of flywheel energy storage systems being electrically coupled to the power distribution grid; and

an array controller being operably coupled to each one of the plurality of flywheel energy storage systems and configured to receive a signal that depends on a grid parameter, the array controller being configured and arranged so as to control each of the plurality of flywheel energy storage systems responsive to the signal,

wherein the signal specifies an amount of electrical power to be selectively added to or absorbed from the power distribution grid, the amount of electrical power being an amount established to regulate the AC frequency of the electrical power on the power distribution grid, and

wherein the array controller controls each of the plurality of flywheel energy storage systems so that the plurality of flywheel energy storage systems adds the amount of electrical power when the received signal indicates that electrical power is to be added to the power distribution grid, and absorbs the amount of electrical power when the received signal indicates that electrical power is to be absorbed from the power distribution grid.

43. The AC frequency regulation system of claim 42, wherein the grid parameter comprises at least one selected from a group consisting of:

load imposed on the grid, power generated by the plurality of power generation facilities, grid frequency, time error, and area control error.

44. The AC frequency regulation system of claim 42, wherein the plurality of flywheel energy storage systems are arranged so as to form a plurality of arrays, each of the plurality arrays including a plurality of flywheel energy storage systems.

45. The AC frequency regulation system of claim 44, wherein the system comprises 40 arrays of flywheel energy storage systems.

46. The AC frequency regulation system of claim 42, wherein the plurality of flywheel energy storage systems comprises 4 or more flywheel energy storage systems.

47. The AC frequency regulation system of claim 42, wherein the plurality of flywheel energy storage systems comprises 7 or more flywheel energy storage systems.

48. The AC frequency regulation system of claim 42, wherein the plurality of flywheel energy storage systems comprises 10 flywheel energy storage systems.

49. The AC frequency regulation system of claim 42, wherein the array controller further controls the operation of the plurality of flywheel energy storage systems so that the amount of electrical power that is specified by the received signal is repeatedly absorbed by, and discharged from, the plurality of flywheel energy storage systems responsive to the received signal.

50. The AC frequency regulation system of claim 49, wherein the received signal is updated at least once every 2 seconds.

51. The AC frequency regulation system of claim 50, wherein the received signal is updated at least once every 4 seconds.

52. The system of claim 42, wherein the array controller is configured to:

evaluate a plurality of operating voltages comprising an operating voltage of each of the plurality of flywheel energy storage systems to determine a synchronization state of the plurality of operating voltages;

determine a corrected voltage signal required to synchronize the operating voltage of each of the plurality flywheel energy storage systems;

output the corrected voltage signal to at least one flywheel energy storage system of the plurality of flywheel energy storage systems to adjust a motor/generator system of the at least one flywheel energy storage system to synchronize the operating voltage of each of the plurality of flywheel energy storage systems.

53. The system of claim 52, wherein the motor/generator system is configured to act as either an electric motor or an electric generator depending on a sign of the received signal.

54. The system of claim 42, wherein the plurality of flywheel energy storage systems comprises a plurality of flywheels, the system further comprising:

a plurality of bi-directional inverters, one for each of the plurality of flywheels, configured to convert a plurality of AC flywheel operating powers to a common DC operating power on a common DC bus,

wherein the common DC bus is electrically connected to a DC output side of the plurality of bi-directional inverters; and

a power conditioning module that is electrically connected to the common DC bus and is configured to convert the common DC operating power to an output AC operating power that corresponds to the amount of electrical power that is added to the grid.

55. The frequency control system of claim 42, wherein the signal is generated at a location that is remote from a site where the plurality of flywheel energy storage systems are electrically coupled to the power distribution grid.

56. The frequency control system of claim 55, wherein the signal is transmitted over a communications link.

57. The frequency control system of claim 56, wherein the communications link is a communications network.

58. The frequency control method of claims 55, wherein the signal is generated by a dispatcher and is transmitted to the array controller.

59. The frequency control system of claim 55, wherein the signal is generated by an agent and is transmitted to the array controller.

60. The frequency control system of claim 55, wherein the signal is generated by a system operator and is transmitted to the array controller.

61. The frequency control system of claim 42, wherein the signal is generated at a different location from the energy storage sub-system.

62. The frequency control system of claim 42, wherein the signal is generated at a control location.

63. The system of claim 42, further comprising a switching mechanism, wherein one end of the switching mechanism is connected to an output of a flywheel energy storage system and another end of the switching mechanism is connected to the power distribution grid.

64. The system of claim 63, further comprising a power conversion module disposed between an output end of the switching mechanism and the power distribution grid.

65. The system of claim 64, further comprising a step-up transformer disposed between an output end of the power conversion module and the power distribution grid.

66. The system of claim 65, wherein the step-up transformer converts an output voltage of the power conversion module to a voltage that is greater than or equal to 35 kV and less than or equal to 115 kV.

67. The system of claim 43, further comprising a plurality of flywheel controllers wherein each one of the flywheel controllers is operatively connected to a corresponding one of the plurality of flywheel energy storage systems.

68. The system of claim 67, wherein the array controller is operatively connected to the plurality of flywheel controllers.

69. The system of claim 67, wherein each of the plurality of flywheel controllers is configured to:

monitor a rotational speed operational parameter of a respective flywheel energy storage system of the plurality of energy storage systems;

cause the respective flywheel to not add electrical power to the grid when the rotational speed operational parameter is lower than a predetermined low threshold; and

cause the respective flywheel to not absorb electrical power from the electrical distribution grid when the rotational speed operational parameter is higher than a predetermined high threshold.

70. The system of claim 67, wherein, independently of the received signal, each of the plurality of flywheel controllers is configured to:

monitor a rotational speed operational parameter of a respective flywheel energy storage system; and

reduce a rotational speed of the respective flywheel energy storage system when the rotational speed operational parameter is above a predetermined level.

71. The system of claim 67, wherein, independently of the received signal, each of the plurality of flywheel controllers is configured to:

monitor an operational parameter of a respective flywheel energy storage system; and

stop rotation of any of the plurality of flywheel energy storage systems based on a state of the operational parameter.

72. The system of claim 42, wherein the plurality of flywheel energy storage systems has a power capacity that is sufficient for causing regulating of the AC frequency of the electrical power being distributed to the power distribution grid.

73. The system of claim 72, wherein the plurality of flywheel energy storage systems has a power capacity of greater than or equal to 50 kWh.

74. The system of claim 42, wherein the plurality of flywheel energy storage systems are capable of being loaded and unloaded at a rate that is greater than a rate of adjustment of the power generated by the power generation facility.

75. The system of claim 74, wherein rate of adjustment of the power generated by the power generation facility is greater than or equal to 5 minutes per adjustment cycle.

76. The system of claim 42, wherein each flywheel of the plurality of flywheels is adapted to be cyclically loaded and unloaded in less than 5 minutes per load/unload cycle.

77. The system of claim 42, wherein a power generated by at least one of the plurality of power generation facilities is being adjusted, based on the grid parameter, to control the AC frequency.

78. The system of claim 42, wherein the grid parameter comprises load imposed on the grid and power generated by the plurality of power generation facilities.

79. The system of claim 42, wherein the grid parameter comprises grid frequency.

80. The system of claim 42, wherein the plurality of flywheel energy storage systems comprises a plurality of flywheels, the system further comprising:

a common AC bus configured to combine a plurality of AC flywheel operating powers to generate a common output AC operating power that corresponds to the amount of electrical power that is added to the grid.

81. The system of claim 42, wherein the array controller is configured to:

receive, from a plurality of flywheel controllers, output signals representative of monitored operational parameters of each of the plurality of flywheel energy storage systems; and

communicate the received output signals to a remotely located monitoring site.