METHOD OF OPERATING AND CONTROL SYSTEM FOR COMBINED CYCLE PLANTS

• US 3,762,162 A
• Filed: 05/16/1972
• Issued: 10/02/1973
• Est. Priority Date: 05/16/1972
• Status: Expired due to Term

• Current Assignee: Kiyoshi Miura, Koichi Kawatake, Yoshiyuki Nakano
• Original Assignee: Kiyoshi Miura, Koichi Kawatake, Yoshiyuki Nakano
• Inventors: Miura, Kiyoshi, Nakano, Yoshiyuki, Kawatake, Koichi
• Primary Examiner(s): Schwadron, Martin P.
• Assistant Examiner(s): Ostrager, Allen M.
• Application Number:
  US05/253,836
• Time in Patent Office: 504 Days
• Field of Search: 60/39.18R,39.18A,39.18B,39.18C,6,38,49,105 290/2,4,40
• US Class Current: 60/711
• CPC Class Codes: F01K 23/00 Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids
• CPC Class Codes: Y02E 20/16 Combined cycle power plant [CCPP], or combined cycle gas turbine [CCGT]

Abstract

In order to improve the efficiency of a heat power plant there are proposed combined cycle plants combining a gas turbine plant and a steam turbine plant as a couple. To improve transient response characteristics and ensure steady normal operation of such combined cycle plants, quick response of the gas turbine plant is effectively utilized. The output capacity of gas turbine plants, though it has been increased in recent years, is still far small compared to steam turbine plants. However, the response of gas turbines to a change of load command is far superior to the steam turbines. Accordingly, when the load command changes a gas turbine plant is adapted to off-set the delay in response of steam turbine plant and the shares are subsequently corrected, thereby improving transient response characteristic and ensuring steady normal operation of the whole combined cycle plant.

Claims

1. A method of controlling a combined cycle power plant consisting of at least two subplants of different types, at least one of said sub-plants being operated by a control signal produced from a first output command signal obtained in a predetermined proportion to a power demand signal and a second output command signal obtained from a signal representing the actual output signal of another one of said sub-plants and said power command signal.

2. A system for controlling a combined cycle power plant consisting of at least two subplants of different types, which comprises:

input means to introduce a power demand signal specifying the output of said combined cycle plant;

a plurality of percentage coefficient multiplier means to multiply said power demand signal by respective predetermined percentage coefficients for producing first output command signals for the individual sub-plants;

output command signal correction means to produce a second output command signal by multiplying the difference between the first output command signal for a sub-plant having a large characteristic time constant of transient response and a signal representing the actual output of said last-mentioned sub-plant by a predetermined coefficient; and

adder means to add the output of the coefficient multiplier means for said last-mentioned sub-plant and the output of said output command signal correction means;

the output of said coefficient multiplier means for said last-mentioned sub-plant being used to control said last-mentioned sub-plant, and the output of said adder means being used to control a sub-plant having a small characteristic transient response time constant.

3. The system for controlling a combined cycle power plant according to claim 2, which further comprises output command signal correction means for the sub-plant having a large characteristic transient response time constant, the output of said last-mentioned output command signal correction means constituting an input to adder means providing an output used to control the sub-plant having a large characteristic transient response time constant.

4. The system for controlling a combined cycle power plant according to claim 3, wherein said output command signal correction means for the small characteristic time constant sub-plant receives the output of the adder means for controlling the large characteristic time constant sub-plant in place of the pertinent first output command signal.

5. A method of controlling a combined cycle power plant consisting of at least two sub-plants of different types, each of sub-plants being operated by a control signal produced from a first output command signal obtained in a predetermined proportion to a power demand signal and a second output command signal obtained from an integrating circuit having a sufficiently large time constant, said integrating circuit receiving the difference between a signal representing the actual output of one of said sub-plants and a signal obtained by multiplying said power demand signal by a predetermined factor.

6. A system for controlling a combined cycle power plant consisting of at least two sub-plants of different types, which comprises:

input means to introduce a power demand signal specifying the output of said combined cycle plant;

a plurality of percentage coefficient multiplier means to multiply said power demand signal by respective predetermined percentage coefficients for producing first output command signals for the individual sub-plants;

a multiplier means to multiply said power demand signal by a predetermined factor;

an adder meaNs to derive the difference between a signal representing the actual output of a sub-plant having a small characteristic transient response time constant and the output of said multiplier means;

an output command signal correction means receiving the output or said adder means and consisting of an integrating circuit having a time constant at least as large as the time constant of a large characteristic transient response time constant sub-plant; and

correction adder means to derive second output command signals from the output of said respective percentage coefficient multipliers and the output of said output command signal correction means;

the output of said individual sub-plants being substantially determined by the output of the respective percentage coefficient multiplier means at an initial stage of change in the power demand signal and being adapted to change in course of time in accordance with the output of said output command signal correction means.

7. The system for controlling a combined cycle power plant according to claim 6, which further comprises a signal generating means to produce a third constant output command signal for use in place of the output of said multiplier means to multiply said power demand signal by a predetermined factor.

8. The system for controlling a combined cycle power plant according to claim 7, wherein said multiplier means and said signal generating means are adapted to be selectively used.

9. The system for controlling a combined cycle power plant according to Claim 6, which further comprises a second adder means to derive the difference between a signal representing the actual output of a sub-plant having a large characteristic transient response time constant and the output of the adder means for controlling said last-mentioned sub-plant, a second multiplier means to multiply the output of said second adder means by a predetermined factor, and a third adder means to derive the sum of the first output comand signal for a sub-plant having a small characteristic transient response time constant and the output of said second mutliplier means.

10. The system for controlling a combined cycle power plant according to claim 2, which further comprises an input adjuster means having an integrating function, said input adjuster means receiving the difference between said power demand signal and a signal representing the output of said combined cycle plant, the output of said input adjuster means being supplied to said input means.

11. The system for controlling a combined cycle power plant according to claim 6, which furthere comprises an input adjuster means having an integrating function, said input adjuster means receiving the difference between said power demand signal and a signal representing the output of said combined cycle plant, the output of said input adjuster means being supplied to said input means.