PHOTOVOLTAIC ENERGY STORAGE SYSTEM AND METHOD FOR DETECTING GROUND INSULATION IMPEDANCE

This application provides a photovoltaic energy storage system and a method for detecting a ground insulation impedance, to improve accuracy of detecting a ground insulation impedance after one or more conversion circuits are connected in parallel. The photovoltaic energy storage system includes one or more conversion circuits and a detection circuit. The detection circuit includes an alternating current signal source and a sampling resistor that are connected in series, a first sampling circuit, and a control circuit. The control circuit is configured to control the alternating current signal source to output harmonic signals of a first frequency and a second frequency. The first sampling circuit is configured to: when the alternating current signal source outputs the harmonic signal of the first frequency, collect a voltage at both terminals of the sampling resistor to obtain a first voltage; when the alternating current signal source outputs the harmonic signal of the second frequency, collect a voltage at both terminals of the sampling resistor to obtain a second voltage; and send the first voltage and the second voltage to the control circuit. The control circuit is further configured to determine, based on the harmonic signals of the first frequency and the second frequency, the first voltage, and the second voltage, a ground insulation impedance obtained after the one or more conversion circuits are connected in parallel.