MODEL-BASED LOAD DEMAND CONTROL

• US 20160040871A1
• Filed: 10/19/2015
• Published: 02/11/2016
• Est. Priority Date: 10/31/2011
• 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: Beveridge, Robert Allen
• Granted Patent: US 10,190,766 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: F01K 13/02 Controlling, e.g. stopping or starting
• CPC Class Codes: F22B 35/00 Control systems for steam boilers for fluidized bed boilers F22B31/0076; regulation or control of steam power plants F01K7/00; for regulating feed-water supply F22D; for controlling superheat temperature F22G5/00; control of combustion F23N; regulating or controlling in general G05
• CPC Class Codes: G05B 11/16 Two-step controllers, e.g. with on/off action
• CPC Class Codes: G05B 11/18 Multi-step controllers
• CPC Class Codes: G05B 11/42 for obtaining a characteristic which is both proportional and time-dependent, e.g. P. I., P. I. D.
• CPC Class Codes: G05B 13/04 involving the use of models or simulators
• CPC Class Codes: G05B 13/041 in which a variable is automatically adjusted to optimise the performance
• CPC Class Codes: G05B 13/042 in which a parameter or coefficient is automatically adjusted to optimise the performance
• CPC Class Codes: G05B 17/02 electric

Abstract

Embodiments of methods and systems for controlling a load generated by a power generating system may include controlling at least a portion of the system using model-based control techniques. The model-based control techniques may include a dynamic matrix controller (DMC) that receives a load demand and a process variable as inputs and generates a control signal based on the inputs and a stored model. The model may be configured based on parametric testing, and may be modifiable. Other inputs may also be used to determine the control signal. In an embodiment, a turbine is controlled by a first DMC and a boiler is controlled by a second DMC, and the control signals generated by the first and the second DMCs are used in conjunction to control the generated load. Techniques to move the power generating system from Proportional-Integral-Derivative based control to model-based control are also disclosed.

Claims

1. A method of controlling a load generated by a power generating system, comprising:

receiving a signal indicative of a target load demand at an input of a dynamic matrix controller;

determining, by the dynamic matrix controller, a value of a control signal by inputting a value of the target load into a model stored in a memory of the dynamic matrix controller, the model being descriptive of a behavior of a process response at various values of load demands;

generating, by the dynamic matrix controller, the control signal; and

controlling the load generated by the power generating system based on the control signal.

2. The method of claim 1:

further comprising receiving a signal indicative of a setpoint of a process variable used in the power generating system and a signal indicative of a current value of the process variable at additional inputs of the dynamic matrix controller; and

wherein determining the value of the control signal is further based on the signal indicative of the setpoint of the process variable and the signal indicative of the current value of the process variable.

3. The method of claim 2, wherein:

the process variable is a first process variable corresponding to a first section of the power generating system, the dynamic matrix controller is a first dynamic matrix controller, the model is a first model, and the control signal is a first control signal; and

the method further comprises;

receiving the signal indicative of the target load demand, a signal indicative of a setpoint of a second process variable corresponding to a second section of the power generating system, and a signal indicative of a current value of the second process variable at inputs of a second dynamic matrix controller;

determining, by the second dynamic matrix controller, a value of a second control signal by inputting a value of the target load into a second model stored in the memory, and using the signal indicative of the setpoint of the second process variable, the signal indicative of the current value of the second process variable, and the second model stored in a memory of the second dynamic matrix controller; and

generating, by the second dynamic matrix controller, the second control signal; and

controlling the load of the power generating system based on the first control signal and on the second control signal.

4. The method of claim 3, wherein the first section of the power generating system corresponds to one of a turbine or a boiler, and wherein the second section of the power generating system corresponds to the other one of the turbine or the boiler.

5. The method of claim 3, wherein one of the first process variable or the second process variable corresponds to a throttle pressure within the power generating system, and the other one of the first process variable or the second process variable corresponds to an amount of fuel delivered to the power generating system.

6. The method of claim 2, wherein determining the value of the control signal is further based on an additional signal that is indicative of a current value of a disturbance variable and that is received at a respective input of the dynamic matrix controller.

7. The method of claim 6, wherein determining the value of the control signal based on the additional signal indicative of the current value of the disturbance variable comprises determining the value of the control signal based on a signal indicative of at least one of:

an amount of soot, a steam temperature, or an amount of burner tilt.

8. The method of claim 1, further comprising:

determining at least a portion of a configuration of the model based on parametric testing of at least a part of the power generating system; and

storing the model in the memory of the dynamic matrix controller.

9. A method of controlling a load of a power generating system, comprising:

generating, by a first dynamic matrix controller, a first control signal using a target load demand within a first model stored in a memory of the first dynamic matrix controller, the first model being descriptive of a behavior of a process response at various values of load demands;

generating, by a second dynamic matrix controller, a second control signal based on the load demand and a second model stored in a memory of the second dynamic matrix controller; and

controlling the load of the power generating system based on the first control signal and on the second control signal.

10. The method of claim 9, wherein controlling the load of the power generating system based on the first control signal and on the second control signal comprises:

controlling one of a throttle pressure within the power generating system or an amount of fuel delivered to the power generating system based on the first control signal, and

controlling the other one of the throttle pressure within the power generating system or the amount of fuel delivered to the power generating system based on the second control signal.

11. The method of claim 9, wherein:

generating the first control signal is further based on a first variable corresponding to a first section of the power generating system; and

generating the second control signal is further based on a second variable corresponding to a second section of the power generating system.

12. The method of claim 11, wherein:

generating the first control signal based on the first variable corresponding to the first section of the power generating system comprises generating the first control signal based on the first variable corresponding to one of a turbine or a boiler of the power generating system; and

generating the second control signal based on the second variable corresponding to the second section of the power generating system comprises generating the second control signal based on the second variable corresponding to the other one of the turbine or the boiler of the power generating system.

13. The method of claim 11,

further comprising initiating a cessation of a PID (Proportional-Integral-Derivative) control routine within the power generating system, wherein the PID control routine is based on the first variable;

and

wherein generating, by the first dynamic matrix controller, the first control signal based on the first variable occurs after the cessation of the PID control routine based on the first variable has been initiated.

14. The method of claim 11, further comprising:

receiving a signal indicative of a current value of the first variable and a signal indicative of a desired value of the first variable at the first dynamic matrix controller, and

receiving a signal indicative of a current value of the second variable and a signal indicative of a desired value of the second variable at the second dynamic matrix controller; and

wherein;

generating the first control signal further based on the first variable comprises generating the first control signal based on the signal indicative of the current value of the first variable and the signal indicative of the desired value of the first variable in conjunction with the target load demand and the first model, and

generating the second control signal further based on the second variable comprises generating the second control signal based on the signal indicative of the current value and the signal indicative of the desired value of the second variable in conjunction with the target load demand and the second model.

15. The method of claim 14, wherein the first variable is a first process variable, the second variable is a second process variable, and at least one of:

generating the first control signal is further based on a signal indicative of a current value of a first disturbance variable received at the first dynamic matrix controller;

generating the first control signal is further based on a signal indicative of a current value of a first manipulated variable received at the first dynamic matrix controller;

generating the second control signal is further based on a signal indicative of a current value of a second disturbance variable received at the second dynamic matrix controller;

or

generating the second control signal is further based on a signal indicative of a current value of a second manipulated variable received at the second dynamic matrix controller.

16. A power generating system, comprising:

a dynamic matrix controller including;

an input to receive a signal indicative of a target load demand for the power generating system,

a memory storing a model, wherein the model is descriptive of a behavior of a process response at various values of load demands,

a dynamic matrix control routine configured to determine a value of a control signal based on the model and a value of the target load demand, and

an output to provide the control signal to control a load generated by the power generating system.

17. The power generating system of claim 16, wherein:

the input is a first input;

the dynamic matrix controller further includes a second input to receive a signal indicative of a current value of a process variable used in the power generating system and a third input to receive a desired value of the process variable; and

the dynamic matrix control routine is configured to determine the value of the control signal based on the model, the value of the target load demand, the current value of the process variable, and the desired value of the process variable.

18. The power generating system of claim 17, wherein the dynamic matrix control routine is configured to determine the value of the control signal based on the model, the value of the target load demand, the current value of the process variable, the desired value of the process variable, and a current value of a disturbance variable used in the power generating system.

19. The power generating system of claim 18, wherein the current value of the disturbance variable corresponds to at least one of:

an amount of soot blowing, a steam temperature, or an amount of burner tilt.

20. The power generating system of claim 17,

wherein the dynamic matrix controller is a first dynamic matrix controller, the process variable is a first process variable, the dynamic matrix control routine is a first dynamic matrix control routine, and the control signal is a first control signal;

and

wherein the power generating system further comprises a second dynamic matrix controller, the second dynamic matrix controller including;

a first input to receive a signal indicative of a current value of a second process variable used in the power generating system,

a second input to receive a signal indicative of a desired value of the second process variable,

a third input to receive the signal indicative of the target load demand,

a memory storing a second model,

a second dynamic matrix control routine configured to determine a value of a second control signal based on the second model, the value of the target load demand, the current value of the second process variable, and the desired value of the second process variable, and

an output to provide the second control signal to control the load of the power generating system in conjunction with the first control signal.

21. The power generating system of claim 20, wherein the first dynamic matrix controller and the second dynamic matrix controller are sequentially activated.

22. The power generating system of claim 16, wherein the model stored in the memory of the dynamic matrix controller is modifiable in real-time.