Methods and systems for enhancing control of power plant generating units

• US 9,957,843 B2
• Filed: 11/26/2014
• Issued: 05/01/2018
• Est. Priority Date: 12/31/2013
• Status: Active Grant

• Current Assignee: GE Infrastructure Technology, LLC (General Electric Company)
• Original Assignee: General Electric Company
• Inventors: Wichmann, Lisa Anne, Raczynski, Chrstopher Michael
• Primary Examiner(s): HARTMAN JR, RONALD D
• Application Number:
  US14/555,196
• Publication Number:
  US 20150184550A1
• Time in Patent Office: 1,252 Days
• CPC Class Codes: F01K 13/02 Controlling, e.g. stopping or starting
• CPC Class Codes: G05B 13/04 involving the use of models or simulators

Abstract

A control method for optimizing a turndown operation for a power plant having a plurality of generating units. The plurality of generating units each may include either an on-condition or an off-condition during a selected operating period. The method may include: defining competing operating modes, wherein the competing operating modes include different possible combinations regarding which of the plurality of generating units have the on-condition and which have the off-condition during the selected operating period; defining multiple cases for each of the competing operating modes, wherein the multiple cases include varying a value of an operating parameter; receiving performance objectives that include a cost function; receiving an ambient conditions forecast; for the multiple cases of the competing operating modes, simulating the turndown operation with a power plant model given the value of the operating parameter and the ambient conditions forecast; evaluating a simulation result pursuant to the cost function so to select therefrom a preferred case.

Claims

1. A computer-implemented control method for optimizing a turndown operation for a power plant having a plurality of generating units for a selected operating period, wherein the plurality of generating units each comprises either an on-condition or an off-condition during the selected operating period, the method including a controller having a processor that performs the steps of:

defining competing operating modes, wherein the competing operating modes comprise different possible combinations regarding which of the plurality of generating units comprise the on-condition and which comprise the off-condition during the selected operating period;

defining multiple cases for each of the competing operating modes, wherein the multiple cases include varying a value of an operating parameter over a range;

receiving performance objectives that include a cost function for evaluating the turndown operation during the selected operating period;

receiving an ambient conditions forecast for the selected operating period;

for each of the multiple cases of the competing operating modes, simulating the turndown operation of the power plant for the selected operating period with a power plant model given the value of the operating parameter and the ambient conditions forecast;

evaluating a simulation result from each of the simulations pursuant to the cost function so to select therefrom a preferred case from the multiple cases for each of the competing operating modes; and

controlling the power plant pursuant to the preferred case.

2. The computer implemented control method of claim 1, wherein the plurality of the generating units comprises a plurality of gas turbines;

wherein step of defining the competing operating modes includes;

permutating the plurality of gas turbines so to configure an on/off permutation matrix in which permutations describe each unique combination regarding which of the plurality of gas turbines comprise the on-condition and which comprise the off-condition during the selected operating period;

wherein each of the permutations of the permutation matrix is defined as one of the competing operating modes for the selected operating period; and

wherein the step of controlling the power plant pursuant to the preferred case comprises controlling the plurality of gas turbines in accordance with the on-condition and the off-condition defined for each of the plurality of gas turbines within the on/off permutation matrix of the competing operating mode that results in the preferred case.

3. The computer-implemented control method according to claim 2, wherein the step of defining multiple cases for each of the competing operating modes includes varying a value for a first operating parameter over a first range and a value for a second operating parameter over a second range.

4. The computer-implemented control method according to claim 3, wherein the step of simulating with the power plant model each of the multiple cases of the competing operating modes includes generating proposed parameter sets for each particular multiple case of the multiple cases;

and

wherein, for each particular multiple case of the multiple cases, the proposed parameter set includes;

the value within the first range for the first operating parameter and the value within the second range for the second operating parameter for the particular multiple case;

the on-condition and the off-condition for the plurality of gas turbines for the competing operating mode to which the particular multiple case corresponds; and

data regarding the ambient conditions forecast for the selected operating period.

5. The computer-implemented control method according to claim 4, wherein the step of simulating with the power plant model the multiple cases includes performing a simulation run with the power plant model for each of the proposed parameter sets, the simulation run configured to simulate turndown operation during the selected operating period according to input data defined by the proposed parameter sets;

wherein the performance objectives further comprise operability constraints; and

wherein the step of evaluating the simulation result from each of the simulation runs comprises determining which, if any, of the simulation results violate any of the operability constraints.

6. The computer-implemented control method according to claim 3, comprising the step of subdividing the selected operating period into regularly repeating intervals;

wherein the step of receiving the ambient conditions forecast comprises receiving an ambient conditions forecast for each of the intervals; and

wherein the step of permutating the plurality of gas turbines comprises permutating the plurality of gas turbines for each of the intervals so to configure the permutation matrix for each interval, wherein the permutation matrix for each interval is configure such that, for an entirety of any of the intervals, each of the plurality of gas turbines comprises just one of the on-condition and the off-condition to the exclusion of the other.

7. The computer-implemented control method according to claim 6, wherein the step of defining competing operating modes includes defining as one of the competing operating modes each of the permutations for each of the permutation matrices for each of the intervals.

8. The computer-implemented control method according to claim 7, wherein the step of evaluating the simulation result from each of the simulations comprises selecting a preferred case from the multiple cases for each of the competing operating modes for each of the intervals.

9. The computer-implemented control method according to claim 8, wherein the step of simulating with the power plant model each of the multiple cases of the competing operating modes includes generating proposed parameter sets for each particular multiple case of the multiple cases,

wherein, for each particular multiple case, the proposed parameter set includes:

the value within the first range for the first operating parameter and the value within the second range for the second operating parameter for the particular multiple case;

the on-condition and the off-condition for the plurality of gas turbines for the competing operating mode to which the particular multiple case corresponds; and

data regarding the ambient conditions forecast for the interval to which the particular multiple case corresponds.

10. The computer-implemented control method according to claim 9, wherein the step of simulating with the power plant model each of the multiple cases includes performing a simulation run with the power plant model for each of the proposed parameter sets, the simulation run configured to simulate turndown operation during the selected operating period according to input data defined by the proposed parameter sets;

and

wherein the performance objectives further comprise operability constraints; and

wherein the step of evaluating the simulation results from the simulation runs comprises determining which, if any, of the simulation results violate any of the operability constraints and disqualifying for consideration as one of the preferred cases any of the multiple cases that produced the simulation results that violated the operability constraints.

11. The computer-implemented control method according to claim 9, wherein the on/off permutation matrix comprises all of the unique combinations regarding which of the plurality of gas turbines comprise the on-condition and which comprise the off-condition during one of the intervals of the selected operating period, wherein the on-condition comprises an indication of an operating condition for a particular one of the plurality of gas turbines during one of the intervals, and the off-condition comprises a shutdown condition for a particular one of the plurality of gas turbines during one of the intervals.

12. The computer-implemented control method, according to claim 9, further comprising the steps of tuning the power plant model using the processor of the controller before performing the simulation runs, wherein the tuning includes:

defining a first operating period that is previous to the selected operating period;

defining a plurality of the operating parameters;

defining a performance indicator, wherein the performance indicator comprises a criteria of performance regarding the operation of the power plant over a defined operating period, and wherein the performance indicator is defined so to, at least in part, depend upon a selected operating parameter chosen from the plurality of operating parameters;

sensing measured values for the plurality of the operating parameters during the first operating period;

from the measured values, calculating a measured value for the performance indicator;

with the power plant model, simulating the operation of the power plant over the first operating period using input data, wherein the input data for the simulation comprises a subset of the measured values for the plurality of operating parameters and wherein, as output data, the simulation is configured to predict a simulated value for the selected operating parameter;

with the simulated value for the selected operating parameter, calculating a predicted value for the performance indicator;

comparing the measured value against the predicted value of the performance indicator so to determine a differential therebetween; and

using the differential to tune the power plant model.

13. The computer-implemented control method according to claim 12, wherein the power plant model comprises a plurality of logic statements in which performance multipliers correlate process inputs to process outputs from the operation of the power plant;

and

wherein the step of using the differential to tune the power plant model comprises an iterative process of making an adjustment to one or more of the performance multipliers within the power plant model and then recalculating the predicted value for the performance indicator so to determine an affect the adjustment to the one or more performance multipliers on the calculation of the differential until the predicted value for performance indicator substantially equals the measured value for the performance indicator.

14. The computer-implemented control method according to claim 9, wherein the first operating parameter comprises an inlet guide vane setting, and the second operating parameter comprises a turbine exhaust temperature.

15. The computer-implemented control method according to claim 14, wherein the cost function comprises a total fuel consumption by the plurality of gas turbines, and the step of determining the preferred case for the competing operating modes comprises determining which of the simulation results minimizes the total fuel consumption.

16. The computer-implemented control method according to claim 14, wherein the cost function comprises a generating output level for the plurality of gas turbines, and the step of determining the preferred case for the competing operating modes comprises determining which of the simulation results minimizes the generating output level during the interval.

17. The computer-implemented control method according to claim 14, wherein the performance objectives comprise operability constraints;

and

wherein the step of evaluating each of the simulation results of the simulation runs includes determining whether any of the simulation runs violate any of the operability constraints so to disqualifying any such simulation run from consideration as the optimized simulation run.

18. The computer-implemented control method according to claim 17, wherein the operability constraints comprise at least one of:

a combustion boundary;

maintenance of a vacuum seal on a condenser of the power plant; and

a minimum steam temperature in a defined portion of a steam turbine.

19. The computer-implemented control method according to claim 2, wherein the cost function comprises at least one of a total fuel consumption and a generating output level for the plurality of gas turbines.

20. The computer-implemented control method according to claim 19, further comprising the step of using the processor of the controller to electronically communicate an output reporting the preferred case for each of the competing operating modes, wherein the output includes at least one of the total fuel consumption and the generating output level for the plurality of gas turbines for each of the preferred cases.