Method and apparatus for self-calibration of a coordinated control system for an electric power generating station

• US 6,067,505 A
• Filed: 04/10/1998
• Issued: 05/23/2000
• Est. Priority Date: 04/10/1997
• Status: Expired due to Term

• Current Assignee: Schneider Electric Systems USA, Inc. (Schneider Electric SE)
• Original Assignee: The Foxboro Company (Schneider Electric SE)
• Inventors: Flanagan, Todd J., Bonoyer, John J.
• Primary Examiner(s): Hoff, Marc S.
• Assistant Examiner(s): VO, HIEN XUAN
• Application Number:
  US09/058,502
• Time in Patent Office: 774 Days
• Field of Search: 702/85, 702/184, 364/528.28, 364/138, 706/52, 706/60
• US Class Current: 702/85
• CPC Class Codes: G05B 15/02 electric

Abstract

A method of calibrating a multivariate controller in a coordinated control system of an electric power generating station includes an expert system for collecting data at a plurality of operating parameters of the power generating system and providing that data to a characterizer block. By using the calibration data, which is predictive of the response of the power generating system to an external disturbance, the characterizer block provides a feedforward signal to the multivariate controller before the effect of the external disturbance can propagate throughout the power generating system. In the method of the invention, the expert system is implemented as a spreadsheet with a DDE interface to the power generating system and an automatic script file generator for communicating to the characterizer block.

Claims

1. A method of calibrating a multivariate controller for a coordinated control system of an electric power generating station, the multivariate controller being responsive to a disturbance variable and generating a manipulated variable for controlling a response of the power generating station, the method comprising the steps of

generating, by means of a computer-implemented expert system, calibration data predictive of the response of the power generating station to the disturbance variable,

forming a feedforward signal based upon the disturbance variable and the calibration data, and

updating the coordinated control system based upon the feedforward signal before the disturbance propagates through the power generating station.

2. The method of claim 1 further comprising the step of implementing the expert system as a computer-implemented spreadsheet.

3. The method of claim 1 wherein the step of generating the calibration data comprises the steps of

operating the power generating station at a pre-selected power output with a stable load, and

loading, into the expert system, a plurality of selected data measurements from the electric power generating station operating at the pre-selected power output, thereby forming a load array having a plurality of elements, each of which corresponds to one of the selected data measurements.

4. The method of claim 3 further comprising the steps of

specifying a maximum allowable value for a selected element of the load array, and

normalizing the selected element of the load array by the maximum allowable value.

5. The method of claim 3 wherein the step of loading the plurality of data measurements includes the step of providing a DDE interface between the expert system and the power generating station.

6. The method of claim 3 further comprising the step of selecting the selected data measurements to include a measurement selected from a group consisting of:

a gross megawatt demand,

a throttle pressure,

a first stage throttle pressure,

a turbine valve demand as a percentage of maximum,

a total fuel flow as a percentage of a maximum fuel flow,

a total air flow as a percentage of maximum airflow,

a total feedwater flow rate,

a percentage of oxygen,

an economizer inlet temperature,

a water wall outlet temperature,

a primary superheater outlet temperature,

a desuperheater outlet temperature,

a superheater outlet temperature,

a reheat outlet temperature,

a boiler master demand as a percentage of maximum, and

an LMCC (Load Management Control Center) demand in megawatts.

7. The method of claim 3 wherein the operating and loading steps are repeated at each of a plurality of pre-selected power outputs.

8. The method of claim 3 further comprising the step of selecting the stable load to be a 75% load.

9. The method of claim 8 further comprising the steps of

performing the operating and loading steps at full pressure,

performing the operating and loading steps at full pressure with turbine valves wide open,

performing the operating and loading steps at normal overpressure, and

performing the operating and loading steps at normal reduced pressure.

10. The method of claim 1 wherein the step of forming a feedforward signal comprises the step of communicating the calibration data to the characterizer block, thereby providing the characterizer block with a predictive model of the response of the power generating station to the disturbance variable.

11. The method of claim 10 further comprising the step of providing the expert system with an interface to the characterizer block for communication of the calibration data to the characterizer block.

12. The method of claim 11 wherein the step of providing the expert system with an interface to the characterizer block comprises the step of writing an interfacing file to a disk accessible to the characterizer block, the interfacing file including the calibration data.

13. The method of claim 11 further comprising the step of selecting a characterizer block with which to communicate the calibration data.

14. The method of claim 1 further comprising the step of plotting the calibration data.

15. An apparatus for calibrating a multivariate controller in a coordinated control system of an electric power generating station subject to an external disturbance, the apparatus comprising

a multivariate controller,

a computer-implemented expert system for generating calibration data predictive of the response of the electric power generating station to the external disturbance, and

a characterizer block coupled to the expert system and to the coordinated control system, the characterizer block generating a feedforward signal based upon the external disturbance and providing the feedforward signal to the multivariate controller such that the multivariate controller reacts to the external disturbance before the disturbance propagates through the electric power generating station.

16. The apparatus of claim 15 wherein the expert system is implemented as a computer-implemented spreadsheet.

17. The apparatus of claim 15 wherein the expert system comprises

operating means for operating the power generating station at a pre-selected power output with a stable load, and

loading means for acquiring a plurality of selected data measurements from the electric power generating station operating at the pre-selected power output, thereby forming a load array having a plurality of elements, each of which corresponds to one of the selected data measurements.

18. The apparatus of claim 17 further comprising

ranging means for specifying a maximum allowable value for a selected element of the load array, and

scaling means for normalizing the selected element of the load array by the maximum allowable value.

19. The apparatus of claim 17 wherein the loading means comprises a DDE interface between the expert system and the power generating station.

20. The apparatus of claim 17 wherein the loading means comprises measurement means for selecting the selected data measurements to include a measurement selected from a group consisting of:

a gross megawatt demand,

a throttle pressure,

a first stage throttle pressure,

a turbine valve demand as a percentage of maximum,

a total fuel flow as a percentage of a maximum fuel flow,

a total air flow as a percentage of maximum airflow,

a total feedwater flow rate,

a percentage of oxygen,

an economizer inlet temperature,

a water wall outlet temperature,

a primary superheater outlet temperature,

a desuperheater outlet temperature,

a superheater outlet temperature,

a reheat outlet temperature,

a boiler master demand as a percentage of maximum, and

an LMCC (Load Management Control Center) demand in megawatts.

21. The apparatus of claim 17 wherein the operating and loading means are configured to operate the power generating system and acquire data at each of a plurality of pre-selected power outputs.

22. The apparatus of claim 17 wherein the operating means if configured to operate with a stable 75% load.

23. The apparatus of claim 22 further comprising

means for performing the operating and loading steps at full pressure,

means for performing the operating and loading steps at full pressure with turbine valves wide open,

means for performing the operating and loading steps at normal overpressure, and

means for performing the operating and loading steps at normal reduced pressure.

24. The apparatus of claim 15 further comprising communication means for communicating the calibration data from the expert system to the characterizer block, thereby providing the characterizer block with a predictive model of the response of the power generating station to the disturbance variable.

25. The apparatus of claim 24 wherein the communication means comprises a software interface to the characterizer block for communication of the calibration data to the characterizer block.

26. The apparatus of claim 25 further comprising script generating means for writing an interfacing file to a disk accessible to the characterizer block, the interfacing file including the calibration data.

27. The apparatus of claim 25 further means for selecting a characterizer block with which to communicate the calibration data.

28. The apparatus of claim 15 further comprising graphics means for plotting the calibration data.

29. A computer-readable medium having, encoded thereon, software for calibrating a multivariate controller for a coordinated control system of an electric power generating station, the multivariate controller being responsive to a disturbance variable and generating a manipulated variable for controlling a response of the power generating station, the software comprising instructions for executing the steps of

generating, by means of a computer-implemented expert system, calibration data predictive of the response of the power generating station to the disturbance variable,

forming a feedforward signal based upon the disturbance variable and the calibration data, and

updating the coordinated control system based upon the feedforward signal before the disturbance propagates through the power generating station.