LOW VOLTAGE RIDE THROUGH DETECTION DEVICE FOR GRID-CONNECTED PHOTOVOLTAIC INVERTER

The present invention relates to a low voltage ride through detecting device of grid-connected photovoltaic inverter, it comprises a current limiting reactor, short circuit reactors and a combination earth switch; Said current limiting reactor, said intermediate reactor-breaker unit, short circuit reactors and the combination earth switch are connected one by one in series; Said current limiting reactor is connected to 10/35kV grid; Said intermediate reactor-breaker unit and the combination earth switch are connected to the neutral point of high voltage side of reducing transformer respectively. The reducing transformer is inserted to grid-connected photovoltaic inverter. Under the circumstance that short circuit capacity remains unchanged, the device can satisfy the requirement of implementation of voltage sag with multiple amplitudes using a fewer reactors by changing the ratio of current limiting reactor and short circuit reactance via different switch modes of several circuit breakers, which make it qualified to detect the capability of Low voltage ride through of grid-connected photovoltaic inverter.