A power supply system includes at least one group of power supply modules. The power supply module includes a first string, a first residual current detection circuit, an inverter circuit, and a first controller. The first residual current detection circuit is connected between the first string and an input end of the inverter circuit, and an output end of the inverter circuit is connected to an alternating current power grid. When a first residual current value detected by the first residual current detection circuit is greater than a first preset residual current threshold, the first controller controls the first string to be disconnected from the inverter circuit, or controls the inverter circuit to be disconnected from the alternating current power grid.