Patent ID: 6945030

Claim:
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: 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; normal combustion gas temperature control means that controls the flow rate of the fuel so that the combustion gas temperature does not exceed a normal combustion gas temperature limit value; emergency combustion gas temperature control means that controls the flow rate of the fuel so that the combustion gas temperature does not exceed an emergency combustion gas temperature limit value; and 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; switching means that operates in response to operation of said system frequency abnormality sensor to make said normal combustion gas temperature control means inoperative and make said emergency combustion gas temperature control means operative, whereby output of the gas turbine is controlled to stabilize a system frequency.