Gas turbine control system

• US 7,076,940 B2
• Filed: 05/12/2005
• Issued: 07/18/2006
• Est. Priority Date: 05/20/2002
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Ootsuki, Yasuhiko, Katauri, Tomoo, Hirayama, Kaiichirou, Mizuno, Takashi
• Primary Examiner(s): Casaregola, Louis J.
• Application Number:
  US11/127,101
• Publication Number:
  US 20050204745A1
• Time in Patent Office: 432 Days
• Field of Search: 60/390.91, 60/392.7, 60/392.81
• US Class Current: 60/39.27
• 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;

an inlet guide blade control mechanism configured to control the inlet guide vanes or blades to change air flow rate into the compressor;

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

a speed-load control mechanism including a speed control mechanism and a load control mechanism, said speed-load control configured to operate 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;

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

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

3. A gas turbine control system according to claim 1, further comprising:

a limiter mechanism configured to limit a response of said speed control mechanism of the speed-load control mechanism in response to operation of said system frequency abnormality sensor, for a length of time within which the system frequency is expected to recover.

4. A gas turbine control system according to claim 1, further comprising:

a limiter mechanism configured to change 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.

5. 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.

6. 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.

7. The gas turbine control system according to claim 1, wherein said system frequency abnormality sensor operates to stop detection of a system frequency abnormality when it detects at least one of a generator voltage reduction and an abrupt increase of a generator current.

8. The gas turbine control system according to claim 1, wherein said system frequency abnormality sensor operates in relation to an endurance determined on the basis of the system frequency and one of an exhaust gas temperature and a combustion gas temperature.

9. The gas turbine control system according to claim 1, wherein said system frequency abnormality sensor operates on the basis of a variation of the system frequency out of a predetermined range of the system frequency and a signal of disconnection of the generator from the electric power system.

10. The gas turbine control system according to claim 1, wherein said system frequency abnormality sensor operates on the basis of a variation of the system frequency out of a predetermined range of the system frequency and a signal of system separation.

11. The gas turbine control system according to claim 1, wherein said system frequency abnormality sensor operates on the basis of a variation of the system frequency out of a predetermined range of the system frequency and a variation in the output of the generator.

12. The gas turbine control system according to claim 1, wherein said system frequency abnormality sensor operates on the basis of a variation of the system frequency out of a predetermined range of the system frequency, a signal of disconnection of the generator from the electric power system and a variation in the output of the generator.