OPTIMIZED CONTROL OF POWER PLANTS HAVING AIR COOLED CONDENSERS

• US 20110066298A1
• Filed: 09/11/2009
• Published: 03/17/2011
• Est. Priority Date: 09/11/2009
• Status: Active Grant

• Current Assignee: Emerson Process Management Power & Water Solutions Incorporated (Emerson Electric Company)
• Original Assignee: Emerson Process Management Power & Water Solutions Incorporated (Emerson Electric Company)
• Inventors: Huff, Frederick C., Foster, David G., Winn, Harry R., Francino, Peter N.
• Granted Patent: US 8,433,450 B2
• Time in Patent Office: Days
• US Class Current: 700/290
• CPC Class Codes: F01K 13/02 Controlling, e.g. stopping or starting
• CPC Class Codes: F01K 9/003 condenser cooling circuits
• CPC Class Codes: G05B 13/041 in which a variable is automatically adjusted to optimise the performance
• CPC Class Codes: Y02E 30/00 Energy generation of nuclear origin

Abstract

An optimization and control system for a utility plant that uses fan based air cooled condensers controls the operation of the power generation system at the plant in conjunction with the operation of the air cooled condensers so as to run the power plant at an optimum operating point associated with minimizing or reducing the cost of each kilowatt-hour of energy or other useful energy produced by the plant. The optimization and control system includes an optimizer having a numerical solver that determines values for a set of control variables associated with an optimal operating point of the plant and an expert system that oversees and modifies the control variable settings prior to providing these settings to a plant controller. The numerical solver uses an objective function and one or more models of plant equipment to determine the operating point of the plant that minimizes the cost per unit of useful energy generated by the plant. As part of determining the optimal plant operating point, the numerical solver may determine the number of fans to run within the air cooled condensers of the plant and/or the speed of the fans to use in the air cooled condensers in conjunction with the amount of fuel to burn in the boiler, the desired temperature of the steam at the input of the steam turbine, etc., all required to produce a given amount of power (load demand) at the particular environmental conditions currently experienced at the plant. The expert system may modify these outputs by determining which fans to actually use at any particular time based on, for example, the availability of or the operational status of the fans, the wear of the fans and fan motors, etc.

Claims

1. A plant optimization system for use in controlling a plant having a steam cycle including a steam generator, a steam consumer and a condenser system coupled between the steam consumer and the steam generator, the plant optimization system comprising:

an optimizer including a calculation unit and an objective function, wherein the calculation unit analyzes each of a plurality of plant operating points associated with operation of the steam cycle to determine an initial plant operating point that best satisfies the objective function, wherein each of the plurality of plant operating points includes a value for each of a set of steam cycle operating variables; and

an expert engine that stores a set of rules and that uses the set of rules to adjust one or more of the values for the steam cycle operating variables associated with the initial plant operating point to determine an optimal plant operating point for use in controlling the plant.

2. The plant optimization system of claim 1, wherein the calculation unit is a mixed integer linear programming optimizer or a mixed integer non-linear programming optimizer.

3. The plant optimization system of claim 1, wherein the optimizer further includes a set of equipment models that model the operation of equipment within the steam cycle of the plant, and wherein the calculation unit uses the equipment models to predict the operation of the steam cycle of the plant at each of the plurality of plant operating points.

4. The plant optimization system of claim 1, wherein the calculation unit receives a set of constraints associated with operating limits of the plant, and wherein the calculation unit determines the plurality of plant operating points as plant operating points that do not violate any of the set of constraints.

5. The plant optimization system of claim 4, wherein the expert engine determines one or more of the set of constraints based on the rules within the expert engine and provides the one or more of the determined set of constraints to the calculation unit.

6. The plant optimization system of claim 1, wherein the optimizer receives a set of constraints associated with operating limits of the plant, a set of environmental conditions associated with operation of the plant and an output requirement of the plant, and wherein the calculation unit determines the plurality of plant operating points as operating points at which the plant operates at the environmental conditions to produce the output requirement without violating any of the set of constraints.

7. The plant optimization system of claim 1, wherein the objective function specifies a manner of evaluating a plant operating point and the calculation unit uses the objective function to analyze each of the plurality of plant operating points to determine an objective function value for each of the plurality of plant operating points, and selects one of the plurality of plant operating points as the initial plant operating point based on the objective function values determined for the plurality of plant operating points.

8. The plant optimization system of claim 1, wherein the steam consumer produces energy and wherein the objective function is associated with determining the least operating cost of the steam cycle of the plant per unit of energy output by the steam consumer.

9. The plant optimization system of claim 1, wherein the condenser system includes a plurality of electrically driven, air cooled condenser units and wherein at least one of the set of steam cycle operating variables is a condenser system variable defining the operation of the condenser system.

10. The plant optimization system of claim 9, wherein the condenser system variable includes a number of the electrically driven, air cooled condensers units to run.

11. The plant optimization system of claim 9, wherein the condenser system variable includes a speed at which to run a fan of one of the electrically driven, air cooled condenser units.

12. The plant optimization system of claim 9, wherein the condenser system variable includes a power budget to use to run one or more of the electrically driven, air cooled condensers units.

13. A plant control and optimization system for use in controlling a plant having a steam cycle that includes a steam generator and a plurality of electrically driven, air cooled condenser units, the plant control and optimization system comprising:

a plant controller coupled to the steam generator and to the electrically driven air cooled condensers to control the operation of the steam cycle based on a set of plant operating variable targets;

an optimizer that analyzes each of a plurality of plant operating points associated with the operation of the plant to determine an initial optimal plant operating point, wherein each of the plurality of plant operating points includes a value for each of a set of plant operating variables, at least one of the plant operating variables being a condenser variable associated with the operation of the electrically driven, air cooled condenser units within the steam cycle of the plant; and

an expert engine that stores a set of rules and that uses the set of rules and the values of the set of plant operating variables associated with the initial optimal plant operating point to produce the set of plant operating variable targets for use in the plant controller.

14. The plant control and optimization system of claim 13, wherein the optimizer includes a calculation unit and an objective function, wherein the calculation unit analyzes each of the plurality of plant operating points to determine the initial optimal plant operating point as the plant operating point that best satisfies the objective function.

15. The plant control and optimization system of claim 14, wherein the optimizer further includes a set of equipment models that model the operation of equipment within the steam cycle of the plant, and wherein the calculation unit uses the equipment models to predict the operation of the steam cycle of the plant at each of the plurality of plant operating points.

16. The plant control and optimization system of claim 14, wherein the calculation unit receives a set of constraints associated with operating limits of the plant, and wherein the calculation unit determines the plurality of plant operating points as plant operating points that do not violate any of the set of constraints.

17. The plant control and optimization system of claim 16, wherein the expert engine determines one or more of the set of constraints based on rules within the expert engine and provides the one or more of the determined set of constraints to the calculation unit.

18. The plant control and optimization system of claim 14, wherein the optimizer receives a set of constraints associated with operating limits of the plant, a set of environmental conditions associated with operation of the plant and an output requirement of the plant, and wherein the calculation unit determines the plurality of plant operating points as operating points at which the plant operates at the environmental conditions to produce the output requirement without violating any of the set of constraints.

19. The plant control and optimization system of claim 13, wherein one of the plant operating variable targets includes a number of the electrically driven, air cooled condensers units to run.

20. The plant control and optimization system of claim 13, wherein one of the plant operating variable targets includes a speed at which to run a fan of one of the electrically driven, air cooled condenser units.

21. The plant control and optimization system of claim 13, wherein one of the plant operating variable targets includes a power budget to use to run one or more of the electrically driven, air cooled condensers units.

22. A plant control and optimization system for use in controlling a plant having a plant steam cycle with a steam generator, a steam consumer and a condenser system having a plurality of electrically driven, air cooled condenser units coupled between the steam consumer and the steam generator, the plant control and optimization system comprising:

an optimizer that analyzes a plurality of operating points associated with the operation of the steam cycle to determine an optimal operating point of the steam cycle, wherein each of the plurality of operating points includes a different set of values for one or more steam cycle operating variables, the steam cycle operating variables including at least one condenser system operating variable; and

a plant controller coupled to control the steam generator and the electrically driven, air cooled condensers to thereby control the operation of the plant steam cycle, the plant controller further coupled to the optimizer to receive and use the values for the one or more plant steam cycle operating variables associated with the optimal operating point to control the operation of the plant steam cycle.

23. The plant control and optimization system of claim 22, wherein the optimizer includes a calculation unit that determines a set of operational values associated with an initial optimal operating point and an expert engine that stores a set of rules and that uses the set of rules to adjust the set of operational values associated with the initial optimal operating point to determine the steam cycle operating variables values for the optimal operating point.

24. The plant control and optimization system of claim 23, wherein the calculation unit stores and uses an objective function to determine the initial optimal operating point.

25. The plant control and optimization system of claim 24, wherein the steam consumer produces energy and wherein the objective function is associated with determining the least operating cost of the steam cycle per unit of energy output by the steam consumer.

26. The plant control and optimization system of claim 22, wherein the at least one condenser system operating variable includes a number of condenser units to run.

27. The plant control and optimization system of claim 22, wherein the at least one condenser system operating variable includes a speed at which to run one or more fans of one or more of the condenser units.

28. The plant control and optimization system of claim 22, wherein the at least one condenser system operating variable includes a power budget to use to run one or more of the condenser units.

29. A method of optimizing control of a plant having a steam cycle with a steam generator, a steam consumer and a condenser system, the method comprising:

determining a plurality of plant operating points, each of the plurality of plant operating points including one or more operating variables associated with operation of equipment within the steam cycle of the plant;

analyzing each of the plurality of plant operating points using an objective function to determine one of the plurality of plant operating points as an initial optimal operating point that best satisfies an objective function;

determining a particular set of plant control target values to use in controlling the plant based on the initial optimal operating point, the particular set of plant control target values including target values for use in controlling the condenser system of the plant; and

providing the particular set of plant control target values to a process controller for use in controlling the plant.

30. The method of optimizing control of a plant of claim 29, wherein the condenser system includes a plurality of electrically driven, air cooled condenser units coupled between the steam consumer and the steam generator, and wherein determining the particular set of plant control target values includes determining a particular number of condenser units to run within the plant.

31. The method of optimizing control of a plant of claim 29, wherein the condenser system includes a plurality of electrically driven, air cooled condenser units coupled between the steam consumer and the steam generator, and wherein determining the particular set of plant control target values includes using a set of stored rules and the initial optimal operating point to determine an identification of the particular condenser units to run within the plant.

32. The method of optimizing control of a plant of claim 29, wherein the condenser system includes a plurality of electrically driven, air cooled condenser units coupled between the steam consumer and the steam generator, and wherein determining the particular set of plant control target values includes using a set of stored rules and the initial optimal operating point to determine a speed at which to run fans of the condenser units within the plant.

33. The method of optimizing control of a plant of claim 29, wherein the condenser system includes a plurality of electrically driven, air cooled condenser units coupled between the steam consumer and the steam generator, wherein the initial optimal operating point includes a power budget for use in running the condenser system and wherein determining the particular set of plant control target values includes using a set of stored rules and the initial optimal operating point to determine a speed or a number of the condenser units to run within the plant based on a power budget.

34. The method of optimizing control of a plant of claim 29, wherein the condenser system includes a plurality of electrically driven, air cooled condenser units coupled between the steam consumer and the steam generator, wherein the initial optimal operating point includes a range of a number of condenser units to run within the plant and wherein determining the particular set of plant control target values includes determining a particular number of condenser units within the range of the number of condenser units to run within the plant.

35. The method of optimizing control of a plant of claim 34, wherein determining the particular set of plant control target values further includes determining an identity of the condenser units to use as the particular number of condenser units to run within the plant.