Inlet air cooling system and inlet air cooling method for gas turbine

An inlet air cooling system used in a gas turbine for supplying power to a refrigerant compressor for compressing refrigerant in a natural gas liquefaction plant, comprising:

• an evaporator for cooling inlet air of the gas turbine by evaporative cooling;
• a chiller for cooling coolant supplied to the evaporator by a refrigeration cycle, the chiller including one or more chiller motors;
• a first variable speed driver for supplying electric power to each of the one or more chiller motors;
• and
• an electric generator driven by the gas turbine,
• wherein the electric generator is electrically connected to the first variable speed driver, and electric power generated by the electric generator is allowed to be supplied to each of the one or more chiller motors from the first variable speed driver without using a main power line of an electric power system,
• wherein the electric generator functions as a starter motor for starting the gas turbine, and
• wherein the gas turbine inlet air cooling system further comprises a second variable speed driver for supplying electric power from the main power line to the electric generator which functions as the starter motor.