The Design and Field Test of a Shunt Unified Power Quality Controller for Mitigating Voltage Sags

A shunt unified power quality controller (S-UPQC) is developed and has been tested in the field in order to confirm its performance at mitigating voltage sags for sensitive power consumers. The S-UPQC keeps the magnitude of the voltage supply for power consumers constant by acting as a voltage source when voltage sags occur in the power grid. In this paper, a smooth switching strategy is designed to smooth the voltage disturbance of power consumers when the power supply switches between the S-UPQC and the grid. Simulation results are presented to show its high performance. A prototype of S-UPQC is developed and a field test has been conducted. During its operation, the performance of the SUPQC at mitigating voltage sags within actual power systems is confirmed.