Mitigation of Power Supply Disturbance in Single-phase Loads

Voltage sag, short and long term power failures in single phase loads of a 3-phase system create voltage disturbance, which need to be mitigated immediately to improve the performance of the load. A 3-phase zigzag-winding transformer connected across a 3-phase star-connected load may mitigate the voltage disturbance at any one phase of the load. The phase experiencing the voltage disturbance is disconnected from the supply first. The zigzag transformer immediately rebuilds the voltage across the load of the open phase. Very low value of zero sequence impedance of the zigzag transformer provides a shunt path to the positive sequence current and, thereby, allows the current to flow to the open phase load.