PHOTOVOLTAIC SYSTEM, POWER SUPPLY SYSTEM, AND INSULATION FAULT DETECTION METHOD

A photovoltaic system, a power supply system, and an insulation fault detection method. An insulation impedance detection circuit is connected between a bus and the ground. The bus includes the direct current positive bus, the neutral bus, or the direct current negative bus. The insulation impedance detection circuit includes at least a switch. The direct current negative bus is connected to the neutral bus by using an electrical element or a voltage source. A controller obtains insulation impedance based on voltages to ground of the bus that are separately corresponding to the switch before and after the switch is turned on, and determines, based on the insulation impedance, whether there is an insulation fault in the photovoltaic system, to perform protection in a timely manner.