Gas turbine system and bleed control method thereof

A gas turbine system comprising:

• a gas turbine including a compressor that is configured to compress air, a combustor that is configured to generate combustion gas by combusting fuel in compressed air which is the air compressed by the compressor, and a turbine that is driven by the combustion gas;
• a bleed line through which a part of the compressed air generated by the compressor is bled from the gas turbine as bleed air;
• an exhaust line that branches off from a middle of the bleed line and through which a part of the bleed air which has flowed into the bleed line is exhausted;
• an auxiliary turbine that is connected to the bleed line and driven by the bleed air which has flowed through the bleed line;
• a bleed amount adjustment valve that is provided in the bleed line and that is configured to adjust a bleed amount which is a flow rate of the bleed air bled from the gas turbine;
• an inflow amount adjustment valve that is provided in the bleed line and that is configured to adjust an inflow amount which is a flow rate of the bleed air flowing into the auxiliary turbine;
• and
• an exhaust amount adjustment valve that is provided in the exhaust line and that is configured to adjust an exhaust amount which is a flow rate of the bleed air exhausted from the bleed line.