Automatic control system for thermal power plant

Abstract

An automatic control system for a thermal power plant comprises a master controller controlling a turbine in response to an externally applied load command signal, and producing a boiler input command signal by correcting the load command signal on the basis of the detected pressure of main steam generated from a boiler, and a water/steam process controller, a fuel process controller, a combustion process controller and a draft process controller to all of which the boiler input command signal is applied from the master controller. The process controllers apply control signals to equipments controlling a water/steam process, a fuel process, a combustion process and a draft process respectively among the terminal actuating equipments of the various parts of the boiler.

Claims

1. An automatic control system for a thermal power plant including a boiler, a turbine and power generator, comprising means for correcting a load command signal applied to the thermal power plant by comparing the load command signal with a feedback signal indicative of a detected pressure of main steam of the boiler thereby producing a boiler input command signal, and means including a plurality of function generators for generating setting signals of the flow rates of feed water, fuel and air respectively in response to the application of said boiler input command signal, so that the flow rates of feed water, fuel and air are feed-back controlled based on said setting signals.

2. A plant control system as claimed in claim 1, further comprising means including a function generator for generating a setting signal of the temperature of main steam, and means for comparing said setting signal with a feedback signal indicative of the detected temperature of main steam thereby producing a command signal for controlling the flow rate of spray supplied to a desuperheater disposed midway of main steam piping.

3. An automatic control system for a thermal power plant including a boiler, a turbine and a power generator, comprising means for correcting a load command signal applied to the thermal power plant by comparing the load command signal with a feedback signal indicative of a detected pressure of main steam of the boiler thereby producing a boiler input command signal, means including function generators for generating setting signals of the flow rates of feed water and main steam temperature respectively for the purpose of controlling steam produced by the boiler in response to the application of said boiler input command signal, means including a function generator for generating a setting signal of the flow rate of fuel for controlling a fuel supplied to the boiler in response to the application of said boiler input command signal, means including a function generator for generating a setting signal for a total flow rate of air for controlling fuel combustion in the boiler in response to the application of said boiler input command signal, and means including a function generator for generating a setting signal of the flow rate of draft at the outlets of forced draft fans for controlling a draft process of the boiler in response to the application of said boiler input command signal, so that individual terminal actuating equipments can be controlled on the basis of said setting signals.

4. A plant control system as claimed in claim 3, wherein process controllers are disposed to control the steam produced by the boiler, the fuel supplied to the boiler the fuel, combustion process thereof and the draft process respectively, and said means for producing said boiler input command signal on the basis of said load command signal applied to the thermal power plant is disposed in a master controller.

5. A plant control system as claimed in claim 3, further comprising a first function generator generating an air flow-rate command signal in response to the application of said boiler input command signal, a second function generator generating a setting signal of the oxygen concentration of exhaust gases in response to the application of said boiler input command signal, control means for comparing the setting signal generated from said second function generator with a feedback signal indicative of the detected oxygen concentration, and means for producing a corrected air flow-rate command signal on the basis of the output signal of said control means and the output signal of said first function generator and applying said corrected air flow-rate command signal to said combustion process as a total air flow-rate command signal.

7. An automatic control system for an electric power plant comprising:

a master controller responsive to an external load command signal for producing a first command signal indicative of an amount of electric power to be generated by the power plant;

a plurality of subsystems providing individual flows of materials for executing respective processes relating to generation of the electric power by controlling the flows of materials, respectively;

subsystem controllers coupled to the subsystems, respectively, each of said subsystem controllers being solely responsive to said first command signal for determining definitely a second command signal indicative of a set value of given variable of the process executed by the associated subsystem for generating the electric power indicated by said first command signal;

means coupled to each of said subsystem controllers and responsive to the second command signal predetermined definitely by the associated subsystem controller for producing a third command signal for controlling the flow of material in the associated subsystem so that the given variable of the process executed by the associated subsystem assumes the set value indicated by the second command signal; and

means responsive to the third command signal for controlling the flow of material in the associated subsystem based on the third command signal..Iaddend..Iadd.

8. An automatic control system as claimed in claim 7, wherein each of said subsystem controllers includes a function generator having a preset program solely responsive to said first command signal for determining definitely the second command signal as an output thereof..Iaddend..Iadd.9. An automatic control system for an electric power plant comprising:

a master controller responsive to an external load command signal for producing a first command signal indicative of an amount of electric power to be generated by the power plant;

subsystem controllers coupled to a plurality of subsystems providing individual flows of materials for executing respective processes relating to generation of the electric power by controlling the flows of materials, respectively, each of said subsystem controllers being solely responsive to said first command signal for predetermined definitely a second command signal indicative of a target value of given variable of the process executed by the associated subsystem for generating the electric power indicated by said first command signal; and

means coupled to each of said subsystem controllers and responsive to said second command signal determined definitely by the associated subsystem controller for controlling the flow of material in the associated subsystem so that the given variable of the process executed by the associated subsystem assumes the target value indicated by said second command signal..Iaddend..Iadd.10. An automatic control system as claimed in claim 9, wherein each of said subsystem controllers includes a function generator having a preset program solely responsive to said first command signal for determining definitely the second command signal as an output thereof..Iadd.11. An automatic control system for an electric power plant comprising:

a master controller responsive to an external load command signal for producing a main command signal indicative of an amount of electric power to be generated by the Power plant;

subsystem controllers coupled to a plurality of subsystems providing individual flows of at least fuel, air and water for executing respective processes relating to generation of the electric power by controlling the flows of the fuel, air and water, respectively, and solely responsive to said main command signal for determining definitely a fuel command, air command and water command, respectively, indicative of target values relating to the flows of the fuel, air and water to enable the subsystems to execute the respective processes for generating the electric power indicated by said main command signal; and

means coupled to said subsystem controllers and responsive to the fuel command, the air command and the water command, respectively, determined definitely by said respective subsystem controllers for controlling the respective flows of the fuel, air and water in execution of the processes by the subsystems so that the respective flows in the subsystems assume the target values indicated by the respective commands..Iaddend..Iadd.12. An automatic control system as claimed in claim 11, wherein said respective subsystem controllers each include a function generator having a preset program responsive solely to said main command signal for determining definitely the respective command..Iaddend..Iadd.13. An automatic control system of an electric power plant for generating electric power according to a main command signal externally applied thereto, said system comprising:

a plurality of driving means coupled to a plurality of subsystems, providing flows of different materials, respectively, which cooperate with each other for controlling generation of the electric power by said power plant, each of said plurality of driving means controllably driving a flow of material in the associated subsystem; and

plurality of driving means controllers coupled to said subsystems, respectively, each of said controllers being responsive to the main command signal and independent of signals applied to others of said subsystem controllers for providing a non-intermediate output signal solely controlling said driving means in the associated subsystem thereby controlling the generation of the electric power according to the main

command signal..Iaddend..Iadd.14. An automatic control system as claimed in claim 13, wherein each of said subsystem controllers being responsive to the main command signal includes a function generator having a preset program solely responsive to the main command signal for providing the non-intermediate output signal for controlling said driving means in the associated subsystem..Iaddend..Iadd.15. An automatic control system for an electric power plant comprising:

means responsive to an externally applied load command for producing a main command signal indicative of an amount of electric power to be generated by said power plant; and

subsystem controllers coupled to subsystems providing flows of different materials relating to generation of electric power, said flows of different materials cooperating with each other for generating electric power by said power plant, respectively, each of said controllers including first means solely responsive to the main command signal for determining definitely a target signal indicative of a target value relating to the flow of the material solely in the associated subsystem according to the main command signal and second means for controlling the flow of the material in the associated subsystem according to the target

signal determined definitely by said first means..Iaddend..Iadd.16. An automatic control system as claimed in claim 15, wherein said first means includes a function generator having a preset program responsive solely to the main command signal for providing the target signal determined

definitely..Iaddend..Iadd.17. An automatic control system of an electric power plant for generating electric power according to a main command signal externally applied thereto, said system comprising:

a plurality of driving means coupled to a plurality of subsystems providing flows of different materials, respectively, which cooperate with each other for controlling generation of the electric power by said power plant each of said plurality of driving means controllably driving the flow of material in the associated subsystem; and

a plurality of subsystem controllers coupled to said plurality of driving means, respectively, a respective one of said plurality of subsystem controllers being responsive to the main command signal and independent of signals applied to others of said subsystem controllers for providing a non-intermediate output signal controlling said driving means in the associated subsystem without controlling said driving means associated with another one of said subsystem controllers, thereby controlling the generation of the electric power according to the main command signal.

.Iaddend..Iadd.18. An automatic control system of an electric power plant for generating electric power according to a main command signal externally applied thereto, said system comprising:

a plurality of driving means coupled to a plurality of subsystems, respectively, each for controllably driving a flow of material in the associated subsystem; and

a plurality of subsystem controllers coupled to said plurality of driving means, respectively, a respective one of said plurality of subsystem controllers being responsive to the main command signal for providing a non-intermediate output signal controlling said driving means in the associated subsystem without controlling said driving means associated with another one of said subsystem controllers, thereby controlling a parameter according to the main command signal;

a plurality of driving means coupled to a plurality of subsystems, respectively, each for controllably driving a flow of material in the associated subsystem; and

subsystem controllers coupled to said plurality of driving means, respectively, each of said subsystem controllers being responsive to the main command signal for providing a non-intermediate output signal solely controlling said driving means in the associated subsystem thereby controlling a parameter according to the main command signal;