Method for starting gas turbine

A method for starting a gas turbine, comprising:

• selecting either a normal start mode or a hot start mode, as a start mode, based on a state of a gas turbine;
• increasing gradually a rotational speed of the gas turbine by starting a startup control based on the start mode;
• maintaining, in a low rotational speed region with the rotational speed of the gas turbine less than a first rotational speed,
• an opening degree of an inlet guide vane provided in a compressor of the gas turbine at a first opening degree, and
• an opening degree of a bleed valve provided downstream of the inlet guide vane in the compressor at a second opening degree;
• and
• controlling, in a high rotational speed region with the rotational speed including a second rotational speed higher than the first rotational speed,
• the opening degree of the inlet guide vane to a first intermediate opening degree greater than the first opening degree, and
• the opening degree of the bleed valve to a second intermediate opening degree less than the second opening degree, wherein
• the first intermediate opening degree when the hot start mode is selected as the start mode is set greater than the first intermediate opening degree when the normal start mode is selected as the start mode, and
• the second intermediate opening degree when the hot start mode is selected as the start mode is set greater than the second intermediate opening degree when the normal start mode is selected as the start mode.