Process control system and power plant process control system

• US 5,305,230 A
• Filed: 11/20/1990
• Issued: 04/19/1994
• Est. Priority Date: 11/22/1989
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Yokoyama, Hiroshi, Hanaoka, Hiroshi, Miyagaki, Hisanori, Matsumoto, Hiroshi, Saito, Tadayoshi, Nomura, Masahide, Kaji, Akira, Shimoda, Makoto, Nigawara, Seiitsu
• Primary Examiner(s): Teska, Kevin J.
• Application Number:
  US07/615,868
• Time in Patent Office: 1,246 Days
• Field of Search: 364/148, 364/149, 364/150, 364/151, 364/494, 364/495, 395/907, 395/906, 395/910, 395/11
• US Class Current: 700/287
• CPC Class Codes: G05B 13/0285 using neural networks and fuzzy logic
• CPC Class Codes: Y10S 706/906 Process plant

Abstract

A process control system controls a large scale plant such as thermal power plant. This process control system includes a target setting unit for setting an operation target, a control unit for receiving a signal indicating the operation target and for outputting a controlled variable to operate the process, an evaluation unit for quantitatively evaluating operation characteristics corresponding to the operation target of the process operated on the basis of a signal indicating the controlled variable supplied from the control unit, a modification unit for extracting an optimum operation process qualitatively squaring or conforming with the evaluated value derived by the evaluation unit out of a modification rule predetermining operation unit in qualitative relation between the operation characteristics and the operation target of the process and for determining the modification rate of the control unit, a storage unit having a model of a neural network for storing a relation between the operation target and the modification rate derived by the modification unit as a connection state within a circuit, and a learning unit for making the model of the neural network learn the relation between the operation target and the modification rate.

Claims

1. A process control system comprising:

target setting means for setting an operation target of a process to be controlled;

control means for receiving a signal indicating an operation target thus set from said target setting means and for outputting a controlled variable to operate said process;

evaluating means for quantitatively evaluating operation characteristics corresponding to said operation target of said process operated on the basis of a signal indicating the controlled variable supplied from said control means and for deriving an evaluated value thereby;

modification means for extracting an optimum operation process, qualitatively squaring or conforming with the evaluated value derived by said evaluation means, from a modification rule predetermining operation means in qualitative relation between the operation characteristics and the operation target of said process and for determining a modification rate of said control means; and

storage means for storing a relation between the modification rate derived by said modification means and said operation target.

2. A process control system comprising:

target setting means for setting an operation target of a process to be controlled;

control means for receiving a signal indicating an operation target thus set from said target setting means and for outputting a controlled variable to operate said process;

storage means for storing a relation between the operation target and a modification rate of said control means on the basis of past operation characteristics;

evaluation means for quantitatively evaluating operation characteristics corresponding to said operation target of said process operated on the basis of a signal indicating the controlled variable supplied from said control means and a signal indicating said relation supplied from said storage means and for deriving an evaluated value thereby; and

modification means for extracting an optimum operation process, qualitatively squaring or conforming with the evaluated value derived by said evaluation means, from a modification rule predetermining operation means in qualitative relation between the operation characteristics and the operation target of said process and for determining said modification rate of said control means.

3. A process control system comprising:

target setting means for setting an operation target of a process to be controlled;

control means for receiving a signal indicating an operation target thus set from said target setting means and for outputting a controlled variable to operate said process;

evaluation means for quantitatively evaluating operation characteristics corresponding to said operation target of said process derived on the basis of a signal indicating the controlled variable supplied from said control means and for deriving an evaluated value thereby;

modification means for extracting an optimum operation process, qualitatively squaring or conforming with the evaluated value derived by said evaluation means, from a modification rule predetermining operation means in qualitative relation between the operation characteristics and the operation target of said process and for determining a modification rate of said control means;

storage means for storing relation between the modification rate derived by said modification means and said operation target; and

said evaluation means comprising means for quantitatively evaluating operation characteristics of said process actually operated on the basis of the signal supplied from said control means.

4. A process control system comprising:

a target setting section for setting an operation target of a process to be controlled;

a control section for receiving a signal indicating an operation target thus set from said target setting section and for outputting a controlled variable to operate said process; and

an optimization section for optimizing the controlled variable of said control section in accordance with operation characteristics corresponding to said operation target of said process operated on the basis of a signal indicating the controlled variable supplied from said control section,

said optimization section comprising;

evaluation means for quantitatively evaluating operation characteristics corresponding to said operation target of said process operated on the basis of a signal indicating the controlled variable supplied from said control means;

a modification rule predetermining operation means in qualitative relation between the operation characteristics and the operation target of said process;

modification means for extracting an optimum operation process, qualitatively squaring or conforming with the evaluated value derived by said evaluation means, from said modification rule and for determining a modification rate of said control section; and

storage means for storing relation between the modification rate derived by said modification means and said operation target.

5. A process control system according to claim 4, wherein said storage means comprises a model of a neural network for storing the relation between said operation target and said modification rate as a connection state within a circuit.

6. A process control system according to claim 5, wherein said model of neural network comprises a model of a neural network of backpropagation type having a layer network comprising an input layer, a hidden layer and an output layer.

7. A process control system according to claim 4, wherein said modification means extracts an optimum operation process, qualitatively squaring or conforming with the evaluated value derived by said evaluation means, from said modification rule, converts the operation process thus extracted into a quantitative operation process in accordance with fuzzy logic, and determines said modification rate.

8. A process control system according to claim 4, wherein said evaluation means comprises margin calculation means for quantitatively deriving margin of operation characteristics of said process against operational constraint.

9. A process control system according to claim 4, wherein said modification rule has at least two items comprising a condition part and a conclusion part.

10. A process control system according to claim 4, wherein said control means or control section comprises:

basic operation schedule producing means for producing an operation schedule allowing said process to attain the operation target; and

regulating means for modifying said operation schedule on the basis of a signal indicating said relation supplied from said storage means.

11. A process control system comprising:

target setting means for setting an operation target of a process to be controlled;

basis operation schedule producing means for producing an operation schedule allowing said process to attain the operation target given by said target setting means;

storage means for storing relation between a modification rate of the operation schedule and the operation target on the basis of past operation characteristics;

regulating means for receiving a signal indicating said relation from said storage means and for modifying said basic operation schedule;

evaluation means for quantitatively evaluating operation characteristics corresponding to said operation target of said process operated on the basis of a signal indicating a modified basic operation schedule supplied from said regulating means;

modification means for extracting an optimum operation process, qualitatively squaring or conforming with the evaluated value derived by said evaluation means, from a modification rule predetermining operation means in qualitative relation between the operation characteristics and the operation target of said process and for determining a modification rate of said basic operation schedule; and

said storage means storing the relation between the modification rate derived by said modification means and said operation target as said relation.

12. A process control system comprising:

target setting means for setting an operation target of a process to be controlled;

basic operation schedule producing means for producing an operation schedule allowing said process to attain the operation target given by said target setting means;

regulating means for receiving a signal indicating said operation schedule from said basis operation schedule producing means and for modifying at least one of a manipulation rate and manipulation rate of the manipulating parameter;

evaluation means for quantitatively evaluating operation characteristics corresponding to said operation target of said process on the basis of a signal indicating said manipulating value supplied from said regulating means;

modification means for extracting an optimum operation process, qualitatively squaring or conforming with the evaluated value derived by said evaluation means, from a modification rule predetermining operation means in qualitative relation between the operation characteristics and the operation target of said process and for determining a modification rate of at least one of the manipulating parameter and manipulation rate of said manipulating parameter of said regulating means; and

said storage means storing the relation between the modification rate derived by said modification means and said operation target.

13. A process control system comprising:

target setting means for setting an operation target of a process to be controlled;

basic operation schedule producing means for producing an operation schedule allowing said process to attain the operation target given by said target setting means;

storage means for storing a relation between a modification rate of the operation schedule and the operation target on the basis of past operation characteristics;

a path for transmitting a signal indicating said relation for operation schedule modification from said storage means to said basic operation schedule producing means;

evaluation means for quantitatively evaluating operation characteristics corresponding to said operation target of said process operated on the basis of a signal indicating an operation schedule modified on the basis of said signal for operation schedule modification and supplied from said basic operation schedule producing means and for deriving an evaluated value thereby;

modification means for extracting an optimum operation process, qualitatively squaring or conforming with the evaluated value derived by said evaluation means, from a modification rule predetermining operation means in qualitative relation between the operation characteristics and the operation target of said process and for determining the modification rate of said basic operation schedule; and

said storage means storing the relation between the modification rate derived by said modification means and said operation target.

14. A process control system comprising:

target setting means for setting an operation target of a process to be controlled;

control means for receiving a signal indicating an operation target from said target setting means and for outputting a controlled variable to operate said process;

evaluation means for quantitatively evaluating operation characteristics corresponding to said operation target of said process operated on the basis of a signal indicating the controlled variable supplied from said control means and for deriving an evaluated value thereby;

modification means for extracting an optimum operation process, qualitatively squaring or conforming with the evaluated value derived by said evaluation means, from a modification rule predetermining operation means in qualitative relation between the operation characteristics and the operation target of said process and for determining a modification rate of said control means;

storage means having a model of neural network for storing a relation between said operation target and the modification rate derived by said modification means as a connection state within a circuit; and

learning means for making said model of neural network learn the relation between said operation target and said modification rate.

15. A process control system according to claim 14, wherein said model of neural network comprises a model of neural network of backpropagation type having a layer network comprising an input layer, a hidden layer and an output layer, and said learning means determines the circuit connection state so that a predetermined modification rate can be outputted when the operation target is inputted to said model of neural network.

16. A process control system comprising:

target setting means for setting an operation target of a process to be controlled;

control means for receiving a signal indicating an operation target from said target setting means and for outputting a controlled variable to operate said process;

a model of a neural network for storing a relation between the operation target and an optimum operation process stored beforehand on the basis of past operation characteristics; and

regulating means for regulating the controlled variable of said control means on the basis of an output signal appearing in an output section of said model of neural network in response to an input signal corresponding to said operation target supplied to an input section of said model of neural network.

17. A process control system comprising:

target setting means for setting a plurality of operation targets of a process to be controlled;

control means for receiving a signal indicating an operation target from said target setting means and for outputting a controlled variable to operate said process;

a model of a neural network storing relations between the operation targets and an optimum operation process stored beforehand as connection states within a circuit; and

regulating means for regulating the controlled variable of said control means on the basis of an output signal appearing in an output section in response to input signals corresponding to a plurality of said operation targets supplied to an input section of said model of a neural network.

18. A process control system for power plant, said power plant comprising:

a boiler for generating steam by using heat generated by combustion of fuel;

a steam turbine for converting heat energy of generated steam into mechanical energy; and

a generator for converting said mechanical energy resulting from conversion into electrical energy;

said process control system comprising;

target setting means for setting an operation target of said process;

control means for receiving a signal indicating an operation target from said target setting means and for outputting a controlled variable to operate said process;

evaluation means for quantitatively evaluating operation characteristics corresponding to said operation target of said process operated on the basis of a signal indicating the controlled variable supplied from said control means and for deriving an evaluated value thereby;

modification means for extracting an optimum operation process, qualitatively squaring or conforming with the evaluated value derived by said evaluation means, from a modification rule predetermining operation means in qualitative relation between the operation characteristics and the operation target of said process and for determining a modification rate of said control means; and

storage means for storing a relation between the modification rate derived by said modification means and said operation target.

19. A process control system for power plant, said power plant comprising:

a boiler for generating steam by using heat generated by combustion of fuel;

a steam turbine for converting heat energy of generated steam into mechanical energy; and

a generator for converting said mechanical energy resulting from conversion into electrical energy,

said process control system comprising;

target setting means for setting an operation target of said process;

control means for receiving a signal indicating an operation target from said target setting means and for outputting a controlled variable to operate said process;

storage means for storing a relation between the operation target and a modification rate of said control means on the basis of past operation characteristics;

evaluation means for quantitatively evaluating operation characteristics corresponding to said operation target of said process operated on the basis of a signal indicating the controlled variable supplied from said control means and a signal indicating said relation supplied from said storage means; and

modification means for extracting an optimum operation process, qualitatively squaring or conforming with the evaluated value derived by said evaluation means, from a modification rule predetermining operation means in qualitative relation between the operation characteristics and the operation target of said process and for determining a modification rate of said control means.

20. A process control system for power plant, said power plant comprising:

a boiler for generating steam by using heat generated by combustion of fuel;

a steam turbine for converting heat energy of generated steam into mechanical energy; and

a generator for converting said mechanical energy resulting from conversion into electrical energy;

said process control system comprising;

target setting means for setting an operation target of said process;

basis operation schedule producing means for receiving a signal indicating the operation target supplied from said target setting means and for producing an operation schedule;

evaluation means for quantitatively evaluating operation characteristics of said process operated along said basic operation schedule;

modification means for extracting an optimum operation process, qualitatively squaring or conforming with the evaluated value, from a modification rule predetermining operation means in qualitative relation between operation characteristics and corresponding operation target of said process and for determining a modification rate of the operation schedule;

storage means for storing a relation between the modification rate derived by said modification means and said operation target; and

regulating means for regulating the operation schedule of said process in response to a signal indicating said relation supplied from said storage means.

21. A process control system comprising:

a fuzzy reasoning unit for determining a desired operational value based on at least one process response characteristics and a fuzzy rule, and outputting said desired operational value;

a neural network for receiving said desired operational value from said fuzzy reasoning unit as learning data, learning and storing said desired operational value, and outputting modification values for modifying parameters for controlling a process based on an operation target and said desired operational value;

a modification unit for receiving said modification values from said neural network, and modifying said parameters based on said modification values; and

a control unit for controlling said process based on said modified parameters.

22. A process control method comprising the steps of:

determining a desired operational value based on at least one process response characteristic and a fuzzy rule;

inputting said desired operational value to a neural network as learning data;

learning and storing said desired operational value with said neural network;

obtaining modification values for modifying parameters for controlling a process based on an operation target and said desired operational parameter with said neural network;

modifying said parameters based on said modification values; and

controlling said process based on said modified parameters.