Two-shaft gas turbine

A two-shaft gas turbine system comprising:

• a compressor having an intake equipped with an inlet guide vane;
• a combustor having a plurality of fuel systems configured to be supplied with fuel independently of one another and to generate combustion gas by combusting the fuel from the fuel systems and air compressed by the compressor;
• a high-pressure turbine coupled coaxially with the compressor and rotated by the combustion gas from the combustor to drive the compressor;
• a low-pressure turbine having a shaft structure independent of the high-pressure turbine and rotated by exhaust gas from the high-pressure turbine to drive a load;
• an air extraction channel configured to extract the air compressed by the compressor;
• external equipment configured to take the air through the air extraction channel, process the air in a predetermined manner, and discharge the processed air;
• an injection flow channel for configured to feed the air discharged from the external equipment back to the combustor;
• and
• a controller configured to control a flow rate of the fuel supplied to each of the fuel systems based on an air flow rate of the compressor, a flow rate of the fuel supplied to the combustor, and a temperature of the air in the injection flow channel,
• wherein the controller, at a time of start-up of the gas turbine, is further configured to:
• control a timing when the fuel is newly added among the fuel systems based on the air flow rate of the compressor, the flow rate of the fuel supplied to the combustor, and the temperature of the air in the injection flow channel, and
• when the temperature of the air in the injection flow channel is lower than a predetermined value, increase the flow rate of the fuel supplied to each of the fuel systems currently supplied with the fuel among the fuel systems.