Method for providing emergency reserve power using storage techniques for electrical systems applications

• US 5,845,479 A
• Filed: 01/20/1998
• Issued: 12/08/1998
• Est. Priority Date: 01/20/1998
• Status: Expired due to Term

• Current Assignee: Electric Power Research Institute Incorporated, Energy Storage and Power LLC
• Original Assignee: Electric Power Research Institute Incorporated
• Inventors: Nakhamkin, Michael, Schainker, Robert
• Primary Examiner(s): Freay, Charles C.
• Assistant Examiner(s): KIM, TAE JUN
• Application Number:
  US09/009,246
• Time in Patent Office: 322 Days
• Field of Search: 60/39.02, 60/727, 60/659
• US Class Current: 60/777
• CPC Class Codes: F02C 6/16 for storing compressed air
• CPC Class Codes: F05D 2260/211 by intercooling, e.g. during a compression cycle
• CPC Class Codes: F05D 2260/85 Starting
• CPC Class Codes: Y02E 60/16 Mechanical energy storage, e.g. flywheels or pressurised fluids

Abstract

A combustion turbine power generation system includes a modified simple cycle combustion turbine power generation system optimized for a "hot" stand-by reserve mode of operation and having a power shaft assembly including a compressor, an expansion turbine, and a double-ended motor/generator between the compressor and the turbine. The motor/generator has a turbine driving clutch structure on one end thereof and a compressor driving clutch structure on the other end thereof. A combustor feeds the expansion turbine. The power generation system includes an additional system having a boost compressor, an intercooler feeding cooled air to the boost compressor an electric motor for driving the boost compressor, and aftercooler downstream of the boost compressor. A compressed air energy storage is downstream of the aftercooler. The additional system is integrated with the modified simple cycle combustion turbine power generation system to provide (i) a primary mode of operation--a hot stand-by mode, when the plant is ready to deliver an emergency power at full turbine power of specified duration within a few seconds; (ii) a cold start-up mode of operation, when the plant is ready to deliver an emergency power at full turbine power of specified duration within a few minutes, depending on the specifics of the turbine design, (iii) an emergency power supply mode, when the plant provides emergency power at full turbine power of specified duration; (iv) a combustion turbine emergency power supply mode, when the plant provides approximately 50% of full turbine power of unlimited duration during long term interruptions of the power supply; and (v) a storage charging mode of operation to charge the air storage.

Claims

1. A method of providing a power generation system including:

modifying a simple cycle combustion turbine system optimized for a "hot" stand-by reserve mode of operation and having a power shaft assembly including a compressor, an expansion turbine and a generator; and

a combustor feeding said turbine, said modification including (1) separating said compressor and said turbine, (2) replacing said generator with a double-ended motor/generator, and (3) placing said motor/generator between said compressor and said turbine, said motor generator having a turbine driving clutch structure on one end thereof and a compressor driving clutch structure on the other end thereof, said compressor driving clutch structure being operatively associated with said compressor so that said compressor is driven by said motor/generator when said compressor driving clutch structure is engaged and said turbine driving clutch structure being operatively associated with said turbine so that said motor/generator may be driven by said turbine when said turbine driven clutch structure is engaged,

providing an additional compression and compressed air storage system comprising;

a boost compressor,

an intercooler feeding the boost compressor,

an electric motor for driving the boost compressor,

an aftercooler downstream of said boost compressor,

a compressed air storage downstream of said aftercooler,

integrating said modified simple cycle combustion turbine system and said additional system to provide various flow paths through said power generation system with;

flow path structure permitting communication between an outlet of said compressor and an inlet to said intercooler feeding said boost compressor,

connection structure permitting communication between an outlet of said air storage and an inlet to the combustor,

bypass structure having a first end coupled to said flow path structure and a second end coupled to said connection structure, said bypass structure permitting communication between an output of said compressor and an inlet of said combustor, and

valving to selectively control flow through said flow path structure, said connection structure, and said bypass structure,

the integration ensuring the selective provision of one of (i) a "hot" stand-by reserve mode of operation capable of delivering emergency electrical power of specified duration, at full power of said turbine, within seconds (ii) a "cold" stand-by reserve mode of operation to provide emergency power of specified duration, at full power of said turbine, within minutes (iii) an emergency power generation mode of operation capable of providing emergency power of specified duration at full power of said turbine, (iv) a combustion turbine emergency power supply mode to provide emergency power of unlimited duration at a fraction of said full power of said turbine, and (v) a charging mode of operation wherein said air storage is charged with compressed air.

2. The method according to claim 1, wherein said valving is provided by a first valve system for controlling air flow in said flow path structure and disposed between said compressor and said intercooler feeding the boost compressor, a second valve system for controlling air flow in said connection structure and disposed between said air storage and said combustor, and a third valve system for controlling air flow in said bypass structure.

3. The method according to claim 2, wherein said "hot" stand-by reserve mode of operation is provided when said turbine driving clutch structure of said power shaft assembly is engaged and said compressor driving clutch structure is disengaged such that said turbine drives said motor/generator with the turbine operating with the motor/generator synchronized with substantially zero power generated to an electric grid, said first and third valve systems are closed and said second valve system is partially open to provide minimal air flow to said combustor to have said turbine driven motor/generator synchronized with an electric grid so as to deliver emergency electric power within seconds upon further opening of said second valve system.

4. The method according to claim 3, wherein during the "hot" stand-by reserve mode of operation, said second valve system is opened enough to provide approximately 2%-3% of maximum compressed air flow to said turbine to maintain operation of said turbine driven motor/generator synchronized with an electric grid.

5. The method according to claim 2, wherein said "cold" stand-by reserve mode of operation is provided when said compressor driving clutch structure is disengaged and said turbine driving clutch structure is engaged such that said turbine is ready to drive the motor/generator, said first, second and third valve systems are closed with said second valve system being ready to be opened to define an air and gas flow path where compressed air stored in said air storage may move to the combustor and gas may move to said turbine for cold start-up thereof for electric power generation within minutes as a function of heating requirements of said turbine.

6. The method according to claim 2, wherein said emergency power generation mode of operation is provided when said compressor driving clutch structure is disengaged and said turbine driving clutch structure is engaged such that said turbine drives the motor generator, said first and third valve systems are closed and said second valve system is open so as to define an air and gas flow path where compressed air from said air storage moves to said combustor and then gas moves to the turbine of the power shaft assembly to produce emergency power.

7. The method according to claim 2, wherein said combustion turbine emergency power generation mode of operation is provided when said first and second valve systems are closed and said third valve system is open, said compressor driving clutch structure and said turbine driving clutch structure each being engaged, and compressed air from said compressor moves through said bypass structure and to said combustor and then gas moves to said turbine to produce power of unlimited duration at a fraction of said full power of said turbine.

8. The method according to claim 2, wherein said charging mode is provided when said turbine driving clutch structure is disengaged and said compressor driving clutch structure is engaged such that said compressor is driven by said motor/generator and said boost compressor is driven by said electric motor, said second and third valve systems are closed and said first valve system is open so as to define an air flow path where compressed air from said compressor moves along said flow path structure and through said intercooler and is then further compressed in said boost compressor and cooled in the aftercooler, the compressed air thereafter is charged into the air storage, said motor/generator and said electric motor being coupled to and powered by an electric grid.

9. The method according to claim 1, wherein said air storage is a man-made structure comprising one of high pressure piping, at least one pressure vessel, and a concrete reinforced structure.

10. The method according to claim 1, wherein said man-made structure is constructed and arranged to have an operating compressed air pressure difference of approximately 1500 psi or greater to minimized a volume of the man-made structure.

11. A method of operating combustion turbine power generation system including (1) a modified simple cycle combustion turbine system optimized for a "hot" stand-by reserve mode of operation and having a power shaft assembly including a compressor, an expansion turbine, and a double-ended motor/generator between said compressor and said turbine, said motor/generator having a turbine driving clutch structure on one end thereof and a compressor driving clutch structure on the other end thereof, said compressor driving clutch structure being operatively associated with said compressor so that said compressor is driven by said motor/generator when said compressor driving clutch structure is engaged and said turbine driving clutch structure being operatively associated with said turbine so that said motor/generator may be driven by said turbine when said turbine driving clutch structure is engaged, and a combustor feeding said expansion turbine, and (2) an additional system having a boost compressor and an intercooler feeding cooled air to said boost compressor with an outlet of the compressor of the power shaft assembly being connected to an inlet of said intercooler via flow path structure, an electric motor for driving said boost compressor, an aftercooler downstream of said boost compressor, a compressed air storage downstream of said aftercooler, connection structure permitting communication between an outlet of said air storage and an inlet to the combustor, bypass structure having a first end coupled to said flow path structure and a second end coupled to said connection structure, said bypass structure permitting communication between an output of said compressor and an inlet of said combustor, a first valve system for controlling air flow in said flow path structure and disposed between said compressor and said intercooler feeding the boost compressor, a second valve system for controlling air flow in said connection structure and disposed between said air storage and said combustor, and a third valve system for controlling air flow in said bypass structure, said system integrating said modified simple cycle combustion turbine system and said additional system, the method including:

controlling said valve systems to permit alternative flow path arrangements and controlling said clutch structures to provide one of

(a) a "hot" stand-by reserve mode of operation wherein said turbine driving clutch structure of said power shaft assembly is engaged and said compressor driving clutch structure is disengaged such that said turbine drives said motor/generator with the turbine operating with the motor/generator synchronized with substantially zero power generated to an electric grid, said first and third valve systems are closed and said second valve system is partially open to provide minimal air flow to said combustor to have said turbine driven motor/generator synchronized with an electric grid so as to deliver emergency electric power at full turbine power within seconds upon further opening of said second valve system,

(b) a "cold" stand-by reserve mode of operation wherein said compressor driving clutch structure is disengaged and said turbine driving clutch structure is engaged such that said turbine is ready to drive the motor/generator, said first, second and third valve systems are closed with said second valve system ready to be opened to define an air and gas flow path where compressed air stored in said air storage may move to the combustor and gas may move to said turbine for cold start-up thereof to provide electric power at full turbine power of specified duration within minutes, as a function of heating requirements of said turbine,

(c) an emergency power generation mode of operation wherein said compressor driving clutch structure is disengaged and said turbine driving clutch structure is engaged such that said turbine drives the motor generator, said first and third valve systems are closed and said second valve system is open so as to define an air and gas flow path where compressed air from said air storage moves to said combustor and then gas moves to the turbine of the power shaft assembly to produce emergency power at full turbine power of specified duration,

(d) a combustion turbine emergency power generation mode of operation wherein said first and second valve systems are closed and said third valve system is open, said compressor driving clutch structure and said turbine driving clutch structure each being engaged, and compressed air from said compressor moves through said bypass structure and to said combustor and then gas moves to said turbine to produce power of unlimited duration at a fraction of said full power of said turbine, and

(e) a charging mode of operation wherein said turbine driving clutch structure is disengaged and said compressor driving clutch structure of said at least one power shaft assembly is engaged such that said compressor is driven by said motor/generator, said second and third valve systems are closed and said first valve system is open so as to define an air flow path where compressed air from said compressor moves along said flow path structure and through said intercooler and is then further compressed in said boost compressor and cooled in the aftercooler, the compressed air thereafter is charged into the air storage, said motor/generator and said electric motor being coupled to and powered by an electric grid.

12. The method according to claim 11, wherein said air storage is a man-made structure comprising one of high pressure piping, at least one pressure vessel, and a concrete reinforced structure.

13. The method according to claim 12, wherein said man-made structure is constructed and arranged to have an operating compressed air pressure difference of approximately 1500 psi or greater to minimized a volume of the man-made structure.

14. The method according to claim 11, wherein during the "hot" stand-by reserve mode of operation, said second valve system is opened enough to provide approximately 2%-3% of maximum compressed air flow to said turbine to maintain operation of said turbine driven motor/generator synchronized with an electric grid.

15. A combustion turbine power generation system to provide emergency power at an electric substation comprising:

a modified simple cycle combustion turbine power generation system optimized for a "hot" stand-by reserve mode of operation and having a power shaft assembly including a compressor, an expansion turbine, and a double-ended motor/generator between said compressor and said turbine, said motor/generator having a turbine driving clutch structure on one end thereof and a compressor driving clutch structure on the other end thereof, said compressor driving clutch structure being operatively associated with said compressor so that said compressor is driven by said motor/generator when said compressor driving clutch structure is engaged and said turbine driving clutch structure being operatively associated with said turbine so that said motor/generator may be driven by said turbine when said turbine driven clutch structure is engaged, and a combustor feeding said expansion turbine, and

an additional system having a boost compressor, an intercooler feeding cooled air to said boost compressor an electric motor for driving said boost compressor, and aftercooler downstream of said boost compressor, a compressed air energy storage downstream of said aftercooler,

said additional system being integrated with said modified simple cycle combustion turbine power generation system by flow path structure permitting communication between an outlet of said compressor and an inlet to said intercooler feeding said boost compressor and connection structure permitting communication between an outlet of said air storage and an inlet to the combustor,

said system further including;

bypass structure having a first end coupled to said flow path structure and a second end coupled to said connection structure, said bypass structure permitting communication between an output of said compressor and an inlet of said combustor

a first valve system for controlling air flow in said flow path structure and disposed between said compressor and an inlet to said intercooler feeding said boost compressor,

a second valve system for controlling air flow in said connection structure and disposed between said air storage and said combustor, and

a third valve system for controlling air flow in said bypass structure,

said valve systems being controllable to provide various flow paths through said system and said turbine driving clutch structure and said compressor driving clutch being controllable so as to selectively provide (i) a "hot" stand-by reserve mode of operation capable of delivering emergency electrical power of specified duration, at full power of said turbine, within seconds (ii) a "cold" stand-by reserve mode of operation to provide emergency power of specified duration, at full power of said turbine, within minutes (iii) an emergency power generation mode of operation capable of providing emergency power of specified duration at full power of said turbine, (iv) a combustion turbine emergency power supply mode to provide emergency power of unlimited duration at a fraction of said full power of said turbine, and (v) a charging mode of operation wherein said air storage is charged with compressed air.

16. The system according to claim 15, wherein said system is constructed and arranged to provide said "hot" stand-by reserve mode of operation when said turbine driving clutch structure of said power shaft assembly is engaged and said compressor driving clutch structure is disengaged such that said turbine drives said motor/generator with the turbine operating with the motor/generator synchronized with substantially zero power generated to an electric grid, said first and third valve systems are closed and said second valve system is partially open to provide minimal air flow to said combustor to have said turbine driven motor/generator synchronized with an electric grid so as to deliver emergency electric power within seconds upon further opening of said second valve system.

17. The system according to claim 15, wherein said system is constructed and arranged to provide said "cold" stand-by reserve mode of operation when said compressor driving clutch structure is disengaged and said turbine driving clutch structure is engaged such that said turbine is ready to drive the motor/generator, said first, second and third valve systems are closed with said second valve system being ready to be opened to define an air and gas flow path where compressed air stored in said air storage may move to the combustor and gas may move to said turbine for cold start-up thereof for electric power generation within minutes as a function of heating requirements of said turbine.

18. The system according to claim 15, wherein said system is constructed and arranged to provide said emergency power generation mode of operation when said compressor driving clutch structure is disengaged and said turbine driving clutch structure is engaged such that said turbine drives the motor generator, said first and third valve systems are closed and said second valve system is open so as to define an air and gas flow path where compressed air from said air storage moves to said combustor and then gas moves to the turbine of the power shaft assembly to produce emergency power.

19. The system according to claim 15, wherein said system is constructed and arranged to provide said combustion turbine emergency power generation mode of operation when said first and second valve systems are closed and said third valve system is open, said compressor driving clutch structure and said turbine driving clutch structure each being engaged, and compressed air from said compressor moves through said bypass structure and to said combustor and then gas moves to said turbine to produce power of unlimited duration at a fraction of said full power of said turbine.

20. The system according to claim 15, wherein said system is constructed and arranged to provide said charging mode said turbine driving clutch structure is disengaged and said compressor driving clutch structure of said at least one power shaft assembly is engaged such that said compressor is driven by said motor/generator, said second and third valve systems are closed and said first valve system is open so as to define an air flow path where compressed air from said compressor moves along said flow path structure and through said intercooler and is then further compressed in said boost compressor and cooled in the aftercooler, the compressed air thereafter is charged into the air storage, said motor/generator and said electric motor being coupled to and powered by an electric grid.

21. The system according to claim 15, wherein said air storage is one of high pressure piping, at least one pressure vessel, and a concrete reinforced structure.

22. The system according to claim 15, wherein said man-made structure is constructed and arranged to have an operating compressed air pressure difference of approximately 1500 psi or greater to minimized a volume of the man-made structure.

23. The system according to claim 15, wherein during the "hot" stand-by reserve mode of operation, said second valve system is constructed and arranged to be opened enough to provide approximately 2%-3% of maximum compressed air flow to said turbine to maintain operation of said turbine driven motor generator synchronized with an electric grid.