Parallel voltage sag compensator without an injection transformer

A parallel voltage sag compensator (PVSC) is a power electronics device to compensate the voltage sag and interruption. The conventional PVSC uses an energy storage device and a bidirectional inverter with an injection transformer. However, the injection transformer reduces the power efficiency with high power losses. This paper proposes a PVSC without the injection transformer. The proposed PVSC has a bidirectional DC–DC converter to transfer the electrical power between the energy storage device and the bidirectional inverter. It uses the common-mode filter capacitors for the AC-side filter in the bidirectional inverter. The ground leakage current can be effectively suppressed between the energy storage device and the AC voltage. The proposed system has high power efficiency and low ground leakage current. Experimental results are discussed to evaluate the performance of the proposed system.