POWER SUPPLY SYSTEM AND POWER SUPPLY METHOD

Provided is a power supply system that contributes to stabilization of a power system, and the like. A power supply system includes a control unit that uses at least a part of generated power of a photovoltaic power plant and a wind power plant that generate power with asynchronous power supplies as in-plant power to be used for a motor and another load during normal operation of a nuclear power plant that generates power with a main generator that is a synchronous power supply. The control unit uses at least a part of the generated power of the photovoltaic power plant and the wind power plant as the in-plant power during the normal operation of the nuclear power plant to reduce an in-plant ratio in the nuclear power plant.