Multiple turbine electric power plant having a coordinated control system with improved flexibility

• US 4,222,229 A
• Filed: 10/18/1978
• Issued: 09/16/1980
• Est. Priority Date: 10/18/1978
• Status: Expired due to Term

• Current Assignee: Siemens Westinghouse Power Corporation
• Original Assignee: Westinghouse Electric Corporation (Paramount Global (f/k/a ViacomCBS Inc.))
• Inventors: Uram, Robert
• Primary Examiner(s): Casaregola, Louis J.
• Application Number:
  US05/952,585
• Time in Patent Office: 699 Days
• Field of Search: 60/39.18 B, 60/39.03, 122/7 R, 122/7 B, 290/40 R, 364/494
• US Class Current: 60/773
• CPC Class Codes: F01K 23/105 Regulating means specially adapted therefor
• CPC Class Codes: Y02E 20/16 Combined cycle power plant [CCPP], or combined cycle gas turbine [CCGT]

Abstract

A combined cycle electric power plant includes gas and steam turbines and a steam generator for recovering the heat in the exhaust gases exited from the gas turbine and for using the recovered heat to produce and supply steam to the steam turbine. Afterburners further heat the exhaust gases from each gas turbine prior to their passage to respective heat recovery sections of the steam generator. The power plant control system provides coordinated plant control or coordinated control of selected turbines and afterburners in both startup and load operations, with load distribution optimized according to the turbines under coordinated control. Transfer between coordinated control and alternate modes of plant control may be done by operator selection or automatically upon sensed conditions.

Claims

1. A combined cycle electric power plant comprising at least one gas turbine and a steam turbine, a heat recovery steam generator connected to deliver steam to said steam turbine, an afterburner connected to deliver heat to said steam generator and connected to receive exhaust gas from said at least one gas turbine and adapted to impart further heat to said exhaust gas, a control system comprising at least an analog portion for operating said plant, said control system having (i) means for controlling the load operation of said steam turbine, (ii) means for controlling the load operation of said at least one gas turbine, and (iii) means for controlling the operation of said afterburner, said control system having coordinating logic means including control mode means for establishing a plurality of mode levels for carrying out respective ones of said load operations at respective different levels of automatic control, and control mode selection means for operatively selecting which of said mode level operations are carried out by said control system on which respective ones of said turbines.

2. The power plant as described in claim 1, comprising two gas turbines, and two afterburners, each afterburner adapted for receiving the exhaust gas of a respective gas turbine, and wherein said control mode means comprises a coordinated control mode and an operator automatic control mode.

3. The power plant as described in claim 2, wherein said steam turbine load controlling means comprises first and second portions, said first portion being carried out only in said coordinated mode, and said second portion being carried out in both said coordinated and operator automatic modes.

4. The power plant as described in claim 3, wherein said gas turbine load controlling means comprises first and second portions, said first portion being carried out only in said coordinated mode, and said second portion being carried out in both said coordinated and operator automatic modes.

5. The power plant as described in claim 4, wherein said control system comprises a programmed digital computer, and said first portions comprise higher level programs and said second portions comprise lower level programs, each respective higher level program being carried out in sequence before its respective lower level program.

6. The power plant as described in claim 5, wherein each of said higher level and lower level programs is continuously run in both the coordinated and operator automatic modes.

7. A combined cycle electric power plant comprising at least one gas turbine and a steam turbine, a heat recovery steam generator connected to deliver steam to said steam turbine, an afterburner connected to deliver heat to said steam generator and connected to receive exhaust gas from said at least one gas turbine and adapted to impart further heat to said exhaust gas, a control system for operating said plant, said control system comprising respective means for controlling said steam turbine, said at least one gas turbine, and said afterburner, means for automatically coordinating the operation of selected ones of said steam turbine, gas turbine and afterburner controlling means, said steam turbine controlling means, gas turbine controlling means and afterburner controlling means each having a plurality of automatic control subsystems operating at different levels of automation and under control of said coordinating means, and means for selecting the configuration of turbine and afterburner controller means coordinated by said automatic coordinating means.

8. The power plant as described in claim 7, comprising two gas turbines and two afterburners, each afterburner connected for receiving the exhaust gas of a respective gas turbine and for delivering heated exhaust gas to said steam generator, and wherein said selecting means comprises operator input means for selecting said coordinated configuration.

9. The power plant as described in claim 8, wherein said automatic coordinating means controls the operation of said afterburners as a function of the temperatures of said gas turbines, and controls said steam turbine controlling means so that the load operation of said steam turbine normally follows the load operation of said gas turbines.

10. The power plant as described in claim 9, wherein said gas turbine controlling means comprises separate portions for each of said gas turbines, and said selecting means provides for selection of the gas turbines under coordinated control.

11. The power plant as described in claim 9, wherein said afterburner controlling means comprises separate portions for each of said afterburners, and said selecting means provides for selection of the afterburners under coordinated control.

12. A combined cycle electric power plant, having at least one subplant comprised of two gas turbines, a steam turbine, a heat recovery steam generator connected to deliver steam to said steam turbine, and two afterburners, each connected to receive exhaust gas from a respective one of said gas turbines and deliver heated exhaust gas to said steam generator, a control system for operating said plant, said control system comprising a digital control portion and an analog control portion, said control system having control level means for providing a plurality of control modes of respective levels of automation, input means for inputting plant operation signals to said control system and output means for outputting generated control signals to said turbines and afterburners, said control level means comprising means for:

a. performing a first priority level sequence of functions;

b. performing a second priority level sequence of functions, said second sequence being adapted to perform operations depending upon performed first sequence functions, and to generate signals for controlling said steam turbine;

c. performing a third priority level sequence of functions, said third sequence being adapted to perform operations depending upon performed first sequence functions, and to generate signals for controlling said gas turbines;

d. said first sequence of functions including generating signals suitable for controlling said afterburners, and for coordinating the generating of said steam turbine, gas turbine and afterburner control signals; and

e. selecting the configuration of which of said steam turbine, gas turbine and afterburner control signals are coordinated.

13. The power plant as described in claim 12, wherein said control system comprises separate means for controlling each of said gas turbines, and wherein said means for selecting includes means for adjusting said separate gas turbine control means in accordance with said selected configuration.

14. The power plant as described in claim 12, wherein said control system comprises separate means for controlling each of said afterburns, and wherein said means for selecting includes means for adjusting said separate afterburner control means in accordance with said selected configuration.

15. The power plant as described in claim 12, wherein said analog control portion contains means for generating control signals for controlling said turbines and said afterburners, and said digital control portion contains means for tracking said analog control signals when said control system is in analog control.

16. The power plant as described in claim 12, wherein said digital control portion comprises means for carrying out a select operating mode function at each of said levels.

17. The power plant as described in claim 16, wherein said digital control portion comprises means for modifying the functions carried out at each of said levels as a function of determined operating mode.

18. The power plant as described in claim 12, wherein the function of coordinating the generating of control signals includes determining a plant load error signal, and modifying the controlling of said gas turbines and afterburners as a function of said load error signal.

19. A combined cycle electric power plant, having at least one subplant comprised of two gas turbines, a steam turbine, a heat recovery steam generator connected to deliver steam to said steam turbine, and two afterburners, each connected to receive exhaust gas from a respective one of said gas turbines and deliver heated exhaust gas to said steam generator, a control system for operating said plant, said control system comprising a programmed digital computer control and an analog control, said controls providing a plurality of control modes of respective levels of automation, input means for inputting plant operation signals to said control system and output means for outputting generated control signals to said turbines and afterburners, said digital computer control comprising:

a. means for generating signals for controlling said steam turbine, which means performs selectable respective operations at first and second program levels;

b. means for generating signals for controlling each of said gas turbines, which means performs selectable respective operations at first and second program levels;

c. means for generating signals for controlling each of said afterburners;

d. means for coordinating the generation of said gas turbine control signals, said steam turbine control signals, and said afterburner control signals, said coordinating means further performing the function of determining which of said selectable operations are performed; and

e. means for selecting the configuration of said gas turbine, steam turbine and afterburner control signals which are coordinated.

20. The power plant as described in claim 19, wherein said digital computer control comprises means for periodically performing said operations at said levels in a predetermined sequence, and wherein said selecting means comprises means for interrupting said predetermined sequence to change said coordinated configuration.

21. The power plant as described in claim 20, wherein said selecting means comprises means for periodically examining, at each of said levels, to determine the selected operating mode of respective turbines and afterburners.

22. The power plant as described in claim 21, wherein said selecting means comprises an operator input panel with selection pushbuttons for establishing mode logic signals.

23. The power plant as described in claim 22, wherein said selecting means comprises routines for periodically monitoring said mode logic signals at each of said levels, and for modifying the performance at each of said program levels as a function of said monitored mode logic signals.

24. A method for operating a combined cycle electric power plant having at least one gas turbine, a steam turbine, a heat recovery steam generator connected to deliver steam to said steam turbine, and at least one afterburner connected to receive exhaust gas from said gas turbine and deliver heated exhaust gas to said steam generator, comprising generating control signals and selectively controlling therewith said gas turbine, steam turbine and afterburner, said generating comprising:

a. periodically generating steam turbine load distribution signals, as a function of plant load demand, said steam load distribution signals being generated at a first priority level;

b. periodically generating gas turbine load distribution signals, at said first priority level;

c. periodically generating afterburner control signals as a function of sensed gas exhaust temperature, at said first priority level;

d. periodically generating, at a second priority level, gas turbine control signals;

e. periodically generating, at said second priority level, steam turbine control signals; and

f. coordinating the generating of said afterburner, steam turbine and gas turbine control signals, said coordinating step including generating said gas turbine control signals as a function of said gas turbine load distribution signals and generating said steam turbine control signals as a function of said steam turbine load distribution signals.

25. The method as described in claim 24, comprising the step of selecting a configuration of said afterburner, steam turbine and gas turbine, and controlling said selected configuration with said coordinated generated control signals.

26. The method as described in claim 24, wherein said afterburner control signals and said gas turbine control signals are generated as a function of a common signal representative of plant load operation.

27. The method as described in claim 24, wherein said plant has two gas turbines and two afterburners, and said step of generating gas turbine control signals comprises generating said signals for each of said gas turbines.

28. The method as described in claim 27, wherein a first one of said gas turbine control signals is generated as a function of said gas turbine load distribution signals, and a second one of said gas turbine control signals is generated independently of said gas turbine load distribution signals.

29. The method as described in claim 28, wherein both of said gas turbine control signals are generated independently of said gas turbine load distribution signals.

30. The method as described in claim 27, wherein said step of generating afterburner control signals includes generating said signals for each of said afterburners.