SAFETY DETECTION DEVICE AND METHOD OF GRID-CONNECTED INVERTER

摘要

Provided is a safety detection device of a grid-connected inverter, applied in a photovoltaic inverter system and comprising a voltage detection circuit, a filter circuit, a comparison circuit and a controller; the voltage detection circuit is used to detect a voltage between a detection N point and the ground, or between the ground and a first terminal in any phase of a three-phase power grid; the filter circuit is used to filter out an alternating current component of the voltage detected by the voltage detection circuit and to retain a direct current component of the voltage; the comparison circuit is used to compare the voltage having the direct current component with a preset voltage value, and transmit a comparison result to the controller; and the controller is used to determine, according to the comparison result, that an alternating current side of an inverter output end has normal insulation, otherwise, determine that the alternating current side of the inverter output end has abnormal insulation. The present invention can determine whether the alternating current side has normal insulation via the voltage detection circuit, the filter circuit, the comparison circuit and the controller used on a hardware for detection, and the hardware and the present invention are easy to realize. Via the detection of voltages between the ground and r, s, t and N, the insulation of the alternating current side from the ground can be determined to be good or not.