Single shaft combined cycle power plant and its operation method

摘要

According to the invention, there is provided a single shaft combined cycle power plant which can quickly switch from single operation of a gas turbine to combined operation of the gas turbine and a steam turbine, and can quickly increase output power, from low power to high power. The single shaft combined cycle power plant includes a means for maintaining the rotation speed of the steam turbine at a speed slower than but near a rated rotation speed when the steam turbine is separated from a coupled unit of a generator and the gas turbine.