Power plants using incongruent load imbalance response

Patent metadata

Field	Value
Publication number	US-11070064-B2
Application number	US-201716606941-A
Country	US
Kind code	B2
Filing date	Dec 8, 2017
Priority date	Dec 8, 2017
Publication date	Jul 20, 2021
Grant date	Jul 20, 2021

Abstract

A method (110) of controlling an imbalance response in a power plant comprising first and second gas turbine engines and a steam turbine driven by steam generated by exhaust from the first and second gas turbine engines can comprise operating the first gas turbine engine at a first power output (116A), operating the second gas turbine engine at a second power output (116B), monitoring load demand from a power grid operating at a steady state condition (114), detecting a load imbalance on the power grid (120) that causes a deviation from the steady state condition, and adjusting the first power output and the second power output incongruently (128) during the imbalance response to change the first power output and the second power output to match the deviation from the steady state condition depending on contemporaneous efficiency states of the first and second gas turbine engines.

First claim

The claimed invention is:

1. A method of controlling an imbalance response in a power plant comprising a first gas turbine engine, a second gas turbine engine and a steam turbine driven by steam generated by exhaust from the first gas turbine engine and the second gas turbine engine, the method comprising:
operating the first gas turbine engine at a first power output;
operating the second gas turbine engine at a second power output;
monitoring load demand from a power grid operating at a steady state condition;
detecting a load imbalance on the power grid that causes a deviation from the steady state condition; and
adjusting the first power output and the second power output incongruently during the imbalance response to change the first power output and the second power output to match the deviation from the steady state condition, the incongruence depending on contemporaneous efficiency states of the first gas turbine engine and the second gas turbine engine.

2. The method of claim 1 , wherein:
the operating the first gas turbine engine comprises operating the first gas turbine engine at a first speed;
the operating the second gas turbine engine comprises operating the second gas turbine engine at a second speed;
the steady state operating condition comprises a control frequency; and
the first speed and the second speed are configured to operate at the control frequency in the steady state operating condition.

3. The method of claim 2 , wherein the load imbalance comprises a deviation from the control frequency.

4. The method of claim 3 , wherein the imbalance response comprises adjusting the first power output and the second power output to reduce the deviation.

5. The method of claim 4 , wherein the imbalance response lasts for a terminable transition period.

6. The method of claim 4 , wherein the imbalance response comprises either:
reducing the power output on the less efficient of the first gas turbine and the second gas turbine more rapidly in a load down condition; or
increasing the power output on the more efficient of the first gas turbine and the second gas turbine more rapidly in a load up condition.

7. The method of claim 6 , wherein the imbalance response results in a new steady state condition.

8. The method of claim 1 , wherein:
the first gas turbine engine has a first productive efficiency at the contemporaneous efficiency state;
the second gas turbine engine has a second productive efficiency at the steady state condition; and
in response to the first productive efficiency being greater than the second productive efficiency, the first power output is adjusted to provide more of the imbalance response.

9. The method of claim 8 , wherein the productive efficiency comprises use of fuel to produce electrical power.

10. The method of claim 1 , wherein:
the first gas turbine engine has a first economical efficiency;
the second gas turbine engine has a second economical efficiency; and
in response to the first economical efficiency being greater than the second economical efficiency, the first power output is adjusted to provide more of the imbalance response.

11. The method of claim 10 , wherein the economical efficiency comprises expenditure of assets to provide maintenance.

12. A method of controlling power plant operation in response to changing conditions of a power grid, the method comprising:
monitoring an operating frequency of the power grid relative to a control frequency;
operating a first gas turbine and a second gas turbine at the control frequency to provide a total power output to meet the power demand under steady state operating conditions, wherein under steady state operating conditions a first power output of the first gas turbine and a second power output of the second gas turbine are equal;
detecting a load imbalance from the power grid wherein the operating frequency and the control frequency are different; and
operating the first gas turbine and the second gas turbine to provide an imbalance response wherein the first power output and the second power output are incongruent such that the power plant operates to increase an operational efficiency during the load imbalance compared to a congruent imbalance response of the first gas turbine and the second gas turbine during the load imbalance.

13. The method of claim 12 , further comprising operating a heat recovery steam generator with exhaust of the first gas turbine and the second gas turbine.

14. The method of claim 12 , wherein the operational efficiency comprises a mechanical efficiency.

15. The method of claim 14 , wherein the mechanical efficiency comprises conversion of fuel to electrical power.

16. The method of claim 12 , wherein the operational efficiency comprises a financial efficiency.

17. The method of claim 16 , wherein the financial efficiency comprises a maintenance or operating expenditures.

18. The method of claim 12 , wherein the load imbalance comprises a change in load demand from the grid.

19. The method of claim 18 , wherein the imbalance response comprises:
determining a first efficiency of the first gas turbine and the first power output;
determining a second efficiency of the second gas turbine at the second power output; and
in response to the first efficiency being greater than the second efficiency, operating the first gas turbine at a higher output than the second gas turbine.

20. The method of claim 19 , wherein the imbalance response comprises operating the first gas turbine at a higher output level than the second gas turbine until the load imbalance is corrected.

21. The method of claim 12 , wherein the load imbalance comprises an excursion of the operating frequency of the grid from the control frequency.

22. The method of claim 21 , wherein the imbalance response comprises operating a more efficient of the first gas turbine and the second gas turbine at a larger droop response level than a less efficient of the first gas turbine and the second gas turbine until the load imbalance is corrected.

23. A control system for operating a power plant, the control system comprising:
a first engine controller for controlling a first combustion process in a first gas turbine engine powering a first electric generator;
a second engine controller for controlling a second combustion process in a second gas turbine engine powering a second electric generator; and
a power plant controller comprising:
a gas turbine interface for providing control input signals to the first engine controller and the second engine controller to control output of the first electric generator and the second electric generator;
a grid interface for receiving a control frequency at which a power grid is to be operated, a droop response instruction for responding to a load imbalance on the power grid, and a current operating frequency of the power grid; and
memory having stored therein efficiency data for the first gas turbine engine and the second gas turbine engine;
wherein the power plant controller is configured to incongruently provide control input signals to the first engine controller and the second engine controller based on the efficiency data in response to the current operating frequency deviating from the control frequency in order to meet the droop response instruction.

24. The control system of claim 23 , further comprising a steam turbine powered by exhaust gas of the first gas turbine engine and t

Assignees

• Mitsubishi Power Americas Inc
• Mitsubishi Power Ltd

Inventors

• Batsch-Smith Lisa

Classifications

• H02J3/46 Primary

  Controlling the sharing of generated power between the generators, sources or networks · CPC title

• F02C9/00

  Controlling gas-turbine plants; Controlling fuel supply in air- breathing jet-propulsion plants (controlling air intakes F02C7/057; controlling turbines F01D; controlling compressors F04D27/00; controlling in general G05) · CPC title

• F01K23/101

  Regulating means specially adapted therefor (F01K23/105, F01K23/108 take precedence) · CPC title

• F05D2240/40

  Use of a multiplicity of similar components · CPC title

• F01K13/02

  Controlling, e.g. stopping or starting · CPC title