Mitigation of Inrush Current of Transformer using Voltage Sag Compensator

In the power system voltage sag become the important issue for industries. According to the survey 92% of the interruptions at industrial installations are voltage sag related. In various companies voltage sag may affect many manufactures and introduce sufficient losses in the power system. The voltage sag compensator, based on a transformer coupled series connected voltage source inverter, is among the most cost-effective solution against voltage sags. A transformer inrush may occur at the start of sag compensator. This over current may damage the inrush protection of the series connected inverter and the transformer output voltage is greatly reduced due the magnetic saturation. When the compensator restores the load voltage, the flux linkage will be driven to the level of magnetic saturation and severe inrush current occurs. This paper proposes a new technique for mitigating the inrush of the coupling transformer and preserving the output voltage for effective