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Primary Examiner: Wise, Edward J.
Assistant Examiner:
Attorney: Possessky; E. F.

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Title: System and method for operating a steam turbine with digital computer control having improved automatic startup control features

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Claims: I claim:

1. An electric power generating system comprising:

a. a steam turbine system;

b. a steam generator for providing steam to said steam turbine system;

c. an electric generator rotated by said turbine system, and adapted to be connected to an electric load;

d. means for digitally computing and processing, having a central processor unit and a memory interconnected with said central processor unit;

e. means for converting input signals to digital data, said input converting means connected to said digital computing means;

f. means for converting digital data to output signals, said digital to output converting means connected to said digital computing means;

g. means for sensing the value of predetermined turbine operating parameters, including differential expansion of predetermined parts of said turbine, and for generating input signals representative of said parameters, said sensing means being connected to said input converting means;

h. means for controlling the steam flow to said turbine;

i. means for connecting said output signal converting means to said steam flow control means;

j. said digital computer means being characterized in that it is programmed to perform a plurality of respective functions in accordance with a predetermined priority, said functions including

i. computing turbine control signals which are a function of at least one of said input signals,

ii. comparing said sensed differential expansion signals with respective predetermined limits,

iii. modifying said computed control signals as a function of said comparison; and

k. said computed control signals being converted to output signals by said output converting means for controlling said steam flow control means as a function of said sensed parameters so as to control steam flow as an intermediate variable, and to control turbine speed during startup and turbine load during load operation as end operating variables.

2. The system as described in claim 1, wherein said modifying function comprises adjusting said control signals to hold speed during turbine startup when the differential expansion at the turbine generator end is outside of a predetermined range.

3. The system as described in claim 1, wherein said modifying function comprises adjusting said control signals to accelerate speed during turbine startup when the sensed differential expansion at the turbine governor end is less than a predetermined limit.

4. The system as described in claim 1, wherein said modifying function comprises adjusting said control signals to hold speed when said sensed differential expansion at the governor end is greater than a predetermined limit.

5. An electric power generating system comprising:

a. a steam turbine system;

b. a steam generator for providing steam to said steam turbine system;

c. an electric generator rotated by said turbine system, and adapted to be connected to an electric load;

d. means for digitally computing and processing, having a central processor unit and a memory interconnected with said central processing unit;

e. means for converting input signals to digital data, said input converting means connected to said digital computing means;

f. means for converting digital data to output signals, said digital to output converting means connected to said digital computing means;

g. means for sensing the value of predetemined turbine operating parameters, including differential expansion of predetermined parts of said turbine, and for generating input signals representative of said parameter, said sensing means being connected to said input converting means;

h. means for controlling the steam flow to said turbine;

i. means for connecting said output signal converting means to said steam flow control means;

j. said digital computer means being programmed to perform the functions of

i. carrying out a plurality of respective computing functions in accordance with a programmed priority,

ii. computing turbine control signals which are a function of at least one of said input signals,

iii. comparing said sensed differential expansion signals with respective predetermined limits; and

iv. modifying said computed control signals when one of said sensed differential expansion signals exceeds its respective predetermined limit;

k. said computed control signals being converted to output signals by said output converting means for controlling said steam flow control means as a function of said sensed parameters so as to control steam flow as an intermediate variable, and to control turbine speed during startup and turbine load during load operation as end operating variables.

6. The system as described in claim 5, wherein said digital computer means comprises means for adjusting said control signals to hold speed during turbine startup when the differential expansion at the turbine generator end is outside of a predetermined range.

7. The system as described in claim 5, wherein said digital computer means comprises means for adjusting said control signals to accelerate speed during turbine startup when the sensed differential expansion at the turbine governor end is less than a predetermined limit.

8. The system as described in claim 5, wherein said digital computer means comprises means for adjusting said control signals to hold speed when said sensed differential expansion at the governor end is greater than a predetermined limit.

9. An electric power generating system comprising:

a. a steam turbine system;

b. a steam generator for providing steam to said steam turbine system;

c. an electric generator rotated by said turbine system, and adapted to be connected to an electric load;

d. means for digitally computing and processing, having a central processor unit and a memory interconnected with said central processing unit;

e. means for converting input signals to digital data, said input converting means connected to said digital computing means;

f. means for converting digital data to output signals, said digital to output converting means connected to said digital computing means;

g. meas for sensing the value of predetermined turbine operating parameters and for generating input signals representative of said parameters, said sensing means being connected to said input converting means;

h. means for controlling the steam flow to said turbine

i. means for connecting said output signal converting means to said steam flow control means;

j. said digital computer means being characterized in that it is programmed to perform a plurality of respective functions in accordance with a predetermined priority, said functions including

i. computing turbine control signals which are a function of at least one of said input signals;

ii. computing signals representative of stress in the rotor of said turbine;

iii. comparing said stress signals with predetermined limits and modifying said control signals as a function of said comparison; and

k. said control signals being converted to output signals by said output converting means for controlling said steam flow control means as a function of said sensed parameters so as to control steam flow as an intermediate variable, and to control turbine speed during startup and turbine load during load operation as end operating variables.

10. The system as described in claim 9, wherein said digital computer means is further characterized in that it is programmed to compute signals representative of anticipated rotor stress, to compare said anticipated stress signals with predetermined limits, and to modify said control signals as a function of said comparison of anticipated stress.

11. A steam turbine system comprising:

a. a steam turbine adapted to receive steam from a steam generator;

b. means for determining representations of at least one predetermined thermal condition of the rotor portion of said turbine and of the differential expansion of predetermined parts of said turbine;

c. means for sequentially

i. determining representations of an anticipated value of said at least one predetermined condition, and

ii. generating control signals as a predetermined function of said anticipated thermal condition representations and of said differential expansion representations; and

d. means for controlling the turbine steam control conditions which affect said predetermined thermal condition, in response to said control signals.

12. The steam turbine system as described in claim 11, wherein said at least one predetermined thermal condition is rotor stress.

13. An electric power generating system comprising:

a. a steam turbine system;

b. a steam generator for providing steam to said steam turbine system;

c. an electric generator rotated by said turbine system, and adapted to be connected to an electric load;

d. means for digitally computing and processing, having a central processor unit and a memory interconnected with said central processing unit;

e. means for converting input signals to digital data, said input converting means connected to said digital computing means;

f. means for converting digital data to output signals, said digital to output converting means connected to said digital computing means;

g. means for sensing the value of predetermined turbine operating parameters and for generating input signals representative of said parameters, said sensing means being connected to said input converting means;

h. means for controlling the steam flow to said turbine;

i. means for connecting said output signal converting means to said steam flow control means;

j. said digital computer means being characterized in that it is programmed to periodically

i. compute values of representations of turbine rotor stress,

ii. compute anticipated values of said representations, and

iii. compute control signals in response to the difference between said representations and said anticipated values and at last one reference value for said representations and for said anticipated values; and

k. said control signals being converted to output signals by said output converting means for controlling said steam flow control means as a function of said sensed parameters so as to control steam flow as an intermediate variable, and to control turbine speed during startup and turbine load during load operation as end operating variables.

14. A steam turbine system for providing power to an electric generating system comprising:

a. a steam turbine adapted to receive steam and to drive an electric generator;

b. means for digitally computing and processing, having a central processor unit and a memory interconnected with said central processing unit;

c. means for converting input signals to digital data, said input converting means connected to said digital computing means;

d. means for converting digital data to output signals, said digital to output converting means connected to said digital computing means;

e. means for sensing the value of predetermined turbine operating parameters and for generating input signals representative of said parameter, said sensing means being connected to said input converting means;

f. means for controlling the steam flow to said turbine;

g. means for connecting said output signal converting means to said steam flow control means;

h. said digital computer means being programmed to perform the functions of

i. computing representations of anticipated values of turbine rotor stress;

ii. computing control signals in response to the difference between said representations and at least one reference value for said representations; and

i. said control signals converted to output signals by said output converting means for controlling said steam flow control means as a function of said sensed parameters so as to control steam flow as an intermediate variable, and to control turbine speed during startup and turbine load during load operation as end operating variables.

15. An electric power generating system comprising:

a. a steam turbine system;

b. a steam generator for providing steam to said steam turbine system;

c. an electric generator rotated by said turbine system, and adapted to be connected to an electric load;

d. means for sensing the value of predetermined turbine operating parameters, including first stage turbine metal temperature, and for generating signals representative of said parameters;

e. means connected to said sensing and generating means for performing the functions of

i. generating cold start control signals as a function of said parameter signals, for controlling said turbine system through a cold start startup procedure when said metal temperature is below a predetermined value, and

ii. generating hot start control signals as a function of said parameter signals, for controlling said turbine system through a hot start startup procedure when said metal temperature is above a predetermined value; and

f. means for controlling steam flow through said steam turbine system, said steam control means being connected to said means for performing and responsive to said control signals.

16. A steam turbine system for providing power to an electric generating system comprising:

a. a steam turbine adapted to receive steam and drive an electric generator;

b. means for generating representations of a plurality of turbine operating parameters, including the temperature of a predetermined portion of said turbine;

c. means connected to said generating means for performing the functions of

i. selecting one of a predetermined plurality of startup procedures as a function of said temperature representation, and

ii. generaing startup control signals as a function of said parameter representation for operating said turbine through said selected startup procedure; and

d. means for controlling steam flow through said steam turbine system, said steam control means being connected to said function performing means and responsive to said control signals.

17. The system as described in claim 16, wherein said startup procedures comprise a cold start startup procedure and a hot start startup procedure.

18. The system as described in claim 11, wherein said predetermined portion is first stage metal temperature.

19. The system as described in claim 18, wherein said means for controlling steam flow comprises valve means for controlling the flow of steam through said steam turbine, said valve means including valves operable to limit said flow of steam, and wherein said generating means generates a representation of first stage metal temperature before opening valves.

20. An electric power generating system comprising:

a. a steam turbine system;

b. a steam generator for providing steam to said steam turbine system;

c. an electric generator rotated by said turbine system, and adapted to be connected to an electric load;

d. means for digitally computing the processing, having a central processor unit and a memory interconnected with said central processing unit;

e. means for converting input signals to digital data, said input converting means connected to said digital computing means;

f. means for converting digital data to output signals, said digital to output converting means connected to said digital computing means;

g. means for sensing the value of predetermined turbine operating parameters and for generating input signals representative of said parameters, said sensing means being connected to said input converting means;

h. means for controlling the steam flow to said turbine;

i. means for connecting said output signal converting means to said steam flow control means;

j. said digital computer means being programmed to perform the functions of

i. comparing first stage metal temperature before opening valves with a predetermined value;

ii. generating control signals for taking said turbine system through a cold start startup procedure when said metal temperature is below said predetermined value; and

iii. generating control signals for taking said turbine system through a hot start starting procedure when said metal temperature is above a predetermined value.

21. In an electric power generating system having a steam turbine with means for controlling steam flow therethrough, a steam generator, and an electric generator rotated by said turbine for delivering load to a power system, a method of operating said power generating system comprising:

a. sensing the values of predetermined turbine operating parameters, including differential expansion of predetermined parts of said turbine, and generating input signals representative of said parameters;

b. converting said input signals to digital data and inputting said digital data to a digital computer having a central processing unit and a memory interconnected with said central processing unit;

c. comparing in said digital computer said sensed differential expansion signals with respective predetermined limits;

d. computing in said digital computer turbine control signals which are a function of at least one of said input signals and of said comparison;

e. performing in said digital computer a plurality of respective computing and processing functions in accordance with a predetermined priority, said functions including said control signal computing and said comparing;

f. converting said control signals to output signals adapted to operate said turbine steam flow control means; and

g. controlling the operation of said turbine by using said control signals to operate said turbine steam flow control means during turbine startup.

22. The method as described in claim 21, comprising adjusting said control signals to hold speed during turbine startup when the differential expansion at the turbine generator end is outside of a predetermined range.

23. The method as described in claim 21, comprising adjusting said control signals to accelerate speed during turbine startup when the sensed differential expansion at the turbine governor end is less than a first one of said predetermined limits.

24. The method as described in claim 21, comprising adjusting said control signals to hold speed when said sensed differential expansion at the governor end is greater than a second one of said predetermined limits.

25. In an electric power generating system having a steam turbine system with means for controlling steam flow therethrough, a steam generator, and an electric generator rotated by said turbine system for delivering load to a power system, a method utilizing a digital computer for operating said power generating system, comprising:

a. concurrently sensing predetermined conditions in the region of the rotor of said turbine and differential expansion of predetermined rotor parts, generating signals representative of said rotor conditions and differential expansion, and inputting said representative signals to said digital computer;

b. computing, in said digital computer, signals derived from said condition signals and representative of stress in the rotor of said turbine system;

c. comparing, in said digital computer, said stress signals with predetermined limits;

d. performing, in said digital computer, a plurality of respective functions in accordance with a predetermined priority, said functions including computing control signals as a function of said stress comparison and of said differential expansion signals; and

e. controlling the steam flow from said steam generator to said steam turbine with said control signals, so as to control turbine speed during turbine startup and turbine load during load operation.

26. The method as described in claim 25, comprising computing, as a function of said computed stress signals, signals representative of anticipated rotor stress, and computing said control signals as a function of said anticipated rotor stress signals.

27. The method as described in claim 26, wherein said step of computing anticipated rotor stress signals comprises extrapolating anticipated stress signals from said computed stress signals.

28. A method of operating an electric power generating system having a steam turbine with means for controlling steam flow therethrough, a steam generator for providing steam, and an electric generator rotated by said turbine for delivering load to a power system, comprising:

a. periodically generating a representation of turbine rotor metal temperature;

b. periodically generating a representation of at least one anticipated thermal condition of said turbine rotor as a function of the difference between said determined metal temperature; and

c. controlling the turbine steam condition in the region of said rotor as a predetermined function of said generated anticipated thermal condition representations and at least one reference undue, said controlling step including generating control signals with a programmed digital computer and controlling said steam control means therewith.

29. The method as described in claim 28, wherein said representation of at least one anticipated thermal condition is a representation of anticipated rotor stress.

30. The method as described in claim 29, comprising the step of periodically comparing said anticipated rotor stress with a predetermined limit, and controlling said turbine steam condition as a function of said comparison.

31. The method as described in claim 30, wherein said step of generating anticipated rotor stress representations comprises extrapolating anticipated rotor stress from present rotor stress.

32. In an electric power generating system having a steam turbine system with means for controlling steam flow therethrough, a steam generator, and an electric generator rotated by said turbine system for delivering load to a power system, a method utilizing a digital computer for operating said power generating system, comprising:

a. sensing predetermined conditions in the region of the rotor of said turbine, generating signals representative of said rotor conditions, and inputting said rotor condition signals to said digital computer;

b. computing, in said digital computer, signals derived from said condition signals and representative of stress in the rotor of said turbine system;

c. computing, in said digital computer, as a function of said computed stress signals, signals representative of anticipated rotor stress, and computing in said digital computer control signals as a function of said anticipated rotor stress signals; and

d. controlling the steam flow from said steam generator to said steam turbine with said control signals, so as to control turbine speed during turbine startup and turbine load during load operation.

33. The method as described in claim 32, wherein said step of computing anticipated rotor stress signals comprises extrapolating anticipated stress signals from said computed stress signals.

34. A method of operating an electric power generating system having a steam turbine with means for controlling steam flow therethrough, a steam generator for providing steam, and an electric generator rotated by said turbine for delivering load to a power system, comprising:

a. determining a representation of the temperature of a predetermined portion of said turbine system;

b. selecting one of a plurality of respective startup procedures as a function of said temperature representation, and operating said turbine system through said selected startup procedure;

c. generating a representation of at least one predetermined thermal condition of the rotor portion of said turbine system;

d. generating a representation of an anticipated value of said thermal condition; and

e. said step of operating said turbine system through a selected startup procedure including controlling steam conditions which affect said predetermined rotor thermal condition.
Other info:

Inventors: Tanco, Juan J. (Buenos Aires, AR, US)

Application Number: 247598
Filing Date: 1972-04-26
Publication_date: 1976-05-25
Assignee: Westinghouse Electric Corporation (Pittsburgh, PA)
Primary Class(es): 700/290 290/40R
Other Classes:
US Patent Ref:

3552872	Jan, 1971	Giras et al.	415/17.
3555251	Jan, 1971	Shavit	235/151.
3561216	Feb, 1971	Moor, Jr.	60/73.
3564273	Feb, 1971	Cockrell	415/17.
3588265	Jun, 1971	Berry	415/17.

Other Refs: Other References: application of the Prodac 50 System to Direct Digital Control, J. C. Belz, G. J. Kirk, & P. S. Radcliffe, IEEE Intl. Conv. Rec. Part 3, 1965, pp. 102-122.
Monitoring and Automatic Control in Steam Power Stations by Process Computer, E. Doetsch & G. Hirschberg, Siemens Review XXXV(1968), No. 12, pp. 471-476.