DEVICE AND METHOD FOR DETECTING INSULATION IMPEDANCE OF POWER GRID CONNECTED WITH PHOTOVOLTAIC INVERTER AGAINST GROUND

摘要

A detection device for detecting insulation impedance of a power grid connected with a photovoltaic inverter against ground is provided. The power grid includes a first live line (R), a second live line (S), a third live line (T) and a zero line (N). The detection device includes: a first resistor (R1), where a first end of the first resistor is connected to a ground wire (PE) of the photovoltaic inverter, and a second end of the first resistor is connected to the first live line; a second resistor (R2), where a first end of the second resistor is connected to the ground wire, and a second end of the second resistor is connected to the zero line; and a first series branch including a third resistor (R3) and a first switch device (Q1) connected in series, where a first end of the first series branch is connected to the ground wire, and a second end of the first series branch is connected to the zero line or the first live line. The detection device and the detection method can detect the resistance of the power grid relative to ground and detect the insulation of the power gird against ground.