Gas turbine control system

• US 20050204745A1
• Filed: 05/12/2005
• Published: 09/22/2005
• Est. Priority Date: 05/20/2002
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Hirayama, Kaiichirou, Kobayashi, Yuka, Kobayashi, Hirokazu, Kobayashi, Tadashi, Mizuno, Takashi, Ootsuki, Yasuhiko, Katauri, Tomoo, Kobayashi, Sayoko
• Granted Patent: US 7,076,940 B2
• Time in Patent Office: Days
• US Class Current: 60/773
• CPC Class Codes: F02C 9/28 Regulating systems responsive to plant or ambient parameters, e.g. temperature, pressure, rotor speed F02C9/30 - F02C9/38, F02C9/44 take precedence
• CPC Class Codes: F02C 9/32 characterised by throttling of fuel F02C9/38 takes precedence
• CPC Class Codes: F02C 9/54 by throttling the working fluid, by adjusting vanes
• CPC Class Codes: F05D 2270/024 to keep rotational speed constant
• CPC Class Codes: F05D 2270/042 by keeping it below damagingly high values
• CPC Class Codes: F05D 2270/06 to match engine to driven device
• CPC Class Codes: F05D 2270/061 in particular the electrical frequency of driven generator
• CPC Class Codes: F05D 2270/091 in particular sudden load loss
• CPC Class Codes: F05D 2270/095 by temporary overriding set control limits
• CPC Class Codes: F05D 2270/303 Temperature
• CPC Class Codes: F05D 2270/304 Spool rotational speed
• CPC Class Codes: F05D 2270/42 passive or reactive, e.g. using large wind vanes
• CPC Class Codes: G05B 23/0291 Switching into safety or degraded mode, e.g. protection and supervision after failure
• CPC Class Codes: Y02T 50/60 Efficient propulsion technologies, e.g. for aircraft

Abstract

A gas turbine control system is disclosed which operates to stabilize the system frequency in a case of transitional variations of the system frequency without making the strength of hot gas path parts of the gas turbine below a maximum stress value of the hot gas path parts. When a system frequency abnormality is detected, the output of the gas turbine is adjusted to recover the system frequency by making a gas turbine combustion gas temperature control inoperative. For this purpose, there are provided a logical circuit operative to make the gas turbine combustion gas temperature control disabled or inoperative in response to an abnormal system frequency detection signal, and a recovery circuit that operates to cancel the inoperative state of the gas turbine combustion gas temperature control. The detection of an abnormal system frequency may be carried out by an outside signal. An abnormality detection unit may be provided in a combined cycle plant.

Claims

1. A gas turbine control system for controlling a gas turbine unit including an air compressor for producing compressed air, said compressor having inlet guide vanes or blades for adjusting an air flow rate into the compressor, a combustor for combusting a fuel mixed with the compressed air from the compressor to produce a combustion gas, a gas turbine receiving the combustion gas from the combustor and driven by the combustion gas to drive the compressor;

and an electric generator connected to an electric power system;

said gas turbine control system comprising;

flow rate into the compressor;

a fuel control valve provided to change flow rate of the fuel into the combustor;

speed-load control means including a speed control means and a load control means, said speed-load control means operating on said fuel control valve to control the flow rate of the fuel so that the gas turbine has a rotational speed coinciding with a set speed value;

combustion gas temperature control means that controls the flow rate of the fuel so that the combustion gas temperature does not exceed a set temperature value;

a system frequency abnormality sensor that operates to detect such a variation of frequency of the electric power system as to cause the power system to go out of normal operation; and

said combustion gas temperature control means having disabling means responsive to operation of said system frequency abnormality sensor to make the combustion gas temperature control means inoperative to thereby have said fuel control valve controlled by the speed-load control means, to restore a system frequency.

2. The gas turbine control system according to claim 1, wherein said disabling means has means to make the combustion gas temperature control means inoperative during a length of time in which the system frequency is expected to recover.

15. The gas turbine control system according to claim 1, wherein said system frequency abnormality sensor operates to detect a system frequency abnormality by comparing an exhaust gas temperature of the gas turbine and an exhaust gas temperature limit value determined on the basis of the system frequency.

16. The gas turbine control system according to claim 1, wherein said system frequency abnormality sensor operates to detect a system frequency abnormality by comparing a combustion gas temperature and a combustion gas temperature limit value determined on the basis of the system frequency.

3-9. -9. (canceled)

10. A gas turbine control system for controlling a gas turbine unit including an air compressor for producing compressed air, said compressor having inlet guide vanes or blades for adjusting an air flow rate into the compressor, a combustor for combusting a fuel mixed with the compressed air from the compressor to produce a combustion gas, a gas turbine receiving the combustion gas from the combustor and driven by the combustion gas to drive the compressor;

and an electric generator driven by gas turbine unit and connected to an electric power system;

said gas turbine control system comprising;

inlet guide blade control means that controls the inlet guide vanes or blades to change the air flow rate into the compressor, said inlet guide blade control means being changeable between a normal inlet guide blade control mode and an emergency inlet guide blade control mode;

a fuel control valve provided to control flow rate of the fuel into the combustor;

speed-load control means including a speed control means and a load control means, said speed-load control means operating on said fuel control valve to control the flow rate of the fuel so that the gas turbine has a rotational speed coinciding with a set speed value;

combustion gas temperature control means that controls the flow rate of the fuel so that the combustion gas temperature does not exceed a combustion gas temperature limit value;

a system frequency abnormality sensor that operates to detect such a variation of frequency of the electric power system as to cause the power system to go out of normal operation; and

changeover means that operates in response to operation of said system frequency abnormality sensor to change over the inlet guide blade control means from said normal inlet guide blade control mode to said emergency inlet guide blade control mode, whereby output of the gas turbine is controlled to stabilize a system frequency.

11. The gas turbine control system according to claim 10, wherein said inlet guide blade control means in said normal inlet guide blade control mode has an upper limit angle of the inlet guide vanes or blades, at which the value of compressor efficiency takes a maximum value, and said inlet guide blade control means in said emergency inlet guide blade control mode has an upper limit angle of the inlet guide vanes or blades, at which the value of compressor air flow rate takes a maximum value.

12. The gas turbine control system according to claim 10, wherein said changeover means is operative to change over the inlet guide blade control means from said normal inlet guide blade control mode to said emergency inlet guide blade control mode, for a length of time within which the system frequency is expected to recover.

13. A gas turbine control system for controlling a gas turbine unit including an air compressor for producing compressed air, said compressor having inlet guide vanes or blades for adjusting an air flow rate into the compressor, a combustor for combusting a fuel mixed with the compressed air from the compressor to produce a combustion gas, a gas turbine receiving the combustion gas from the combustor and driven by the combustion gas to drive the compressor;

and an electric generator driven by the gas turbine unit and connected to an electric power system;

said gas turbine control system comprising;

inlet guide blade control means that controls the inlet guide vanes or blades to change the air flow rate into the compressor;

a fuel control valve provided to change flow rate of the fuel into the combustor;

speed-load control means including a speed control means and a load control means, said speed-load control means operating on said fuel control valve to control the flow rate of the fuel so that the gas turbine has a rotational speed coinciding with a set speed value;

combustion gas temperature control means that controls the flow rate of the fuel so that the combustion gas temperature does not exceed a set temperature value;

a system frequency abnormality sensor that operates to detect such a variation of frequency of the electric power system as to cause the power system to go out of normal operation; and

limiter means for limiting a response of said speed control means of the speed-load control means in response to operation of said system frequency abnormality sensor, for a

length of time within which the system frequency is expected to recover.

14. A gas turbine control system for controlling a gas turbine unit including an air compressor for producing compressed air, said compressor having inlet guide vanes or blades for adjusting an air flow rate into the compressor, a combustor for combusting a fuel mixed with the compressed air from the compressor to produce a combustion gas, a gas turbine receiving the combustion gas from the combustor and driven by the combustion gas to drive the compressor;

and an electric generator driven by the gas turbine unit and connected to an electric power system;

said gas turbine control system comprising;

inlet guide blade control means that controls the inlet guide vanes or blades to change the air flow rate into the compressor;

a fuel control valve provided to change flow rate of the fuel into the combustor;

speed-load control means including a speed control means and a load control means, said speed-load control means operating on said fuel control valve to control the flow rate of the fuel so that the gas turbine has a rotational speed coinciding with a set speed value;

combustion gas temperature control means that controls the flow rate of the fuel so that the combustion gas temperature does not exceed a set temperature value;

a system frequency abnormality sensor that operates to detect such a variation of frequency of the electric power system as to cause the power system to go out of normal operation; and

limiter means for changing a control constant for use in control of the flow rate of the fuel in response to an increase of the system frequency as detected by said system frequency abnormality sensor, to prevent loss of flame of the turbine.