Sag & Swell Detection by Phase Voltage Compensation in 3-Phase Unbalanced Grid

3상 불평형 계통에서의 상 전압 보상을 통한 Sag 및 Swell 검출

Load connection or disconnection makes instantaneous sag & swell in 3-phase grid. When unbalance state occurs, between sensed phase voltage and actual phase voltage may have discrepancy. It makes difficult to detect accurate sag & swell, so it is hard to satisfy the standard for switching ESS system to UPS mode. In this paper, we analyzed unbalanced 3-phase voltage, and compensated the actual sag & swell magnitude.