System and method for operating a steam turbine with digital computer control and with improved monitoring

• US 4,687,946 A
• Filed: 04/26/1972
• Issued: 08/18/1987
• Est. Priority Date: 04/26/1972
• Status: Expired due to Term

• Current Assignee: Siemens Westinghouse Power Corporation
• Original Assignee: Westinghouse Electric Corporation (Paramount Global (f/k/a ViacomCBS Inc.))
• Inventors: Jones, Donald J.
• Primary Examiner(s): Shoop, Jr., William M.
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US06/247,600
• Time in Patent Office: 5,592 Days
• Field of Search: 290/2, 290/40, 364/138, 364/148, 364/200, 364/494
• US Class Current: 290/40.00R
• CPC Class Codes: F01D 17/20 Devices dealing with sensing elements or final actuators or transmitting means between them, e.g. power-assisted sensing elements alone F01D17/02; final actuators alone F01D17/10

Abstract

A steam generator in an electric power generating system is controlled by controlling turbine steam flow with control signals generated by a programmed digital computer system during startup, synchronization and load operation. The digital computer control signals are generated as a function of monitored turbine system conditions and parameters, the digital computer having means for interrupting the normal computing of the control signals when predetermined operating conditions are monitored. Turbine system parameter signals are periodically scanned and operated on so as to condition them for use in generating the control signals.

Claims

1. An electric power generating system having a steam turbine powered by a steam generator, and adapted to drive an electric generator, said system comprising:

a. means for digitally computing speed control signals through a startup range extending from a predetermined speed to synchronous speed, having a central processor unit and a memory interconnected with said central processing unit;

b. means for converting input signals to digital data, and for transmitting said digital data to said digital computing means throughout said startup range;

c. means for converting digital data to output signals, said digital to output converting means connected to said digital computing means and adapted to transmit said output signals throughout said startup range;

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

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

f. said output signal converting means connected to said steam flow control means;

g. means for sensing predetermined turbine startup conditions and for connecting startup condition status signals to said digital computing means;

h. said digital computer means being characterized in that it is programmed to compute said speed control signals as a function of at least one of said input signals for controlling said steam flow control means, and to monitor said predetermined startup condition signals and interrupt the computing of said control signals when predetermined changes of said startup conditions are monitored;

i. said computed control signals being converted to output signals by said output converting means for controlling said steam flow control means.

2. The electric power generating system as described in claim 1 wherein said digital computer means is programmed to generate interrupt signals within a predetermined time period when said predetermined changes of said startup condition signals are monitored, and contains means for performing predetermined interrupt-initiated functions in response to said interrupt signals.

3. The electric power generating system as described in claim 2, wherein said digital computer means is programmed to compute load control signals during a load mode of operation, so as to control turbine load during load operation.

4. The electric power generating system as described in claim 2, wherein said digital computer means is programmed to compute steam flow control signals during a load mode of operation and during a startup mode of operation, so as to control turbine load during load operation and turbine speed during startup operation.

5. The electric power generating system as described in claim 1, wherein said condition sensing means comprises a plurality of input means having at least two states, and said digital computer means contains a sequence program which is activated when any one of said plurality of input means changes state, said sequence program causing scanning by said digital computer means of said plurality of input means.

6. The electric power generating system as described in claim 1, wherein said condition sensing means includes a plurality of input means having at least two states, and said digital computer means is programmed to scan said plurality of input means on a demand basis.

7. The electric power generating system as described in claim 6, wherein said digital computer means is programmed to perform interrupt-initiated functions when an interruption occurs.

8. The electric power generating system as described in claim 1 wherein said digital computing means is programmed to periodically bid digital data from said input converting means, said bid data providing said input signals for computing said control signals during the startup mode.

9. The electric power generating system as described in claim 1, wherein said digital computing means is programmed to operate with said input signal converting means to (a) periodically scan, (b) convert to predetermined units, (c) and check against predetermined limits, said input signals.

10. An electric power generating system having a controllable steam turbine, a steam generator for providing steam to said turbine, and a generator rotated by said turbine for providing an electric load, said system comprising:

a. means for sensing predetermined operating conditions of said turbine and for generating signals which are a predetermined function of said conditions;

b. means for generating control signals for controlling the operation of said turbine;

c. means for monitoring said condition signals and determining predetermined changes in said signals;

d. means for interrupting said control signal generating means when said predetermined changes are determined; and

e. means for performing interrupt-initiated functions to generate signals representative of the turbine condition status and for modifying said generated control signals as a function of said condition status signals.

11. 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 magnitude of predetermined turbine operating parameters, 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. computing in said digital computer speed control signals as a function of at least one of said input signals;

d. monitoring turbine operating conditions and interrupting the computing of said speed control signals within a predetermined time period following a change in one of said operating conditions;

e. converting said speed control signals to output signals adapted to operate said turbine steam flow control means throughout the turbine startup period; and

f. controlling the operation of said turbine by directly connecting said control signals to said turbine steam flow control means during startup.

12. An electric power generating system having a steam turbine, a steam generator, and an electric generator rotated by said turbine, said system comprising:

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

b. means for converting input signals to digital data, and for transmitting said digital data to said digital computing means;

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

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

e. means directly connecting said digital computing means to said steam flow means, for converting digital data to output signals adapted for operating said steam flow control means throughout a predetermined range of turbine startup;

f. means for generating turbine condition signals representative of predetermined turbine operating conditions;

g. said computer means further containing

(i) means for computing speed control signals throughout a predetermined range of turbine startup as a function of at least one of said input signals, which speed control signals control said steam flow control means; and

(ii) means for monitoring said condition signals and for interrupting the computing of said speed control signals upon monitoring a change in one of said condition signals; and

h. said computer means combining with said directly connecting output means to alter the operation of said steam flow control means as a function of said changed condition signal within a predetermined time period following said monitored change.

13. A turbine generating system, comprising:

a. a steam turbine powered by a source of steam, and adapted to drive an electric generator;

b. means for digitally computing speed control signals for controlling the speed of said steam turbine through a speed range extending from a predetermined speed to synchronous speed;

c. means for sensing predetermined turbine startup conditions, and for generating through said speed range condition status signals representative of said startup conditions;

d. means for generating analog input signals representative of predetermined turbine startup operating parameters, and for converting said analog signals to digital data, said means operative through said speed range;

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

f. said digital computer means being further characterized in that it is programmed

(i) to generate speed reference signals at a predetermined frequency as a function of said input digital data, and to compute said speed control signals as a function of said speed reference signals;

(ii) to monitor said startup condition signals on a demand basis throughout said speed range and to interrupt the computing of said speed control signals within a predetermined time period upon finding one of a given set of predetermined speed conditions;

g. means for connecting said startup condition signals and said input digital data to said digital computer means at all times during turbine operation within said speed range;

h. means for converting said digital speed control signals to output signals, said converting means being interfaced directly between said digital computing means and said steam flow control means, and adapted to transmit speed control signals at said frequency from said computing means directly to said control means, throughout said speed range; and

i. said computed speed control signals being adapted for controlling said steam flow control means so as to control turbine speed continuously throughout said speed range subject to the occurrence of said predetermined condition signals.