Three-phase voltage sag compensator for smart grid and infrastructure

In this paper, a 10kW three-phase voltage sag compensator and control algorithms are proposed. Three-phase voltage sag compensator is able to compensate for input voltage sag or interruption and provides a secured electric power to the critical loads such as computers, automation equipment, and communications equipment. The compensator detects a voltage sag or interruption within 2-msec and provides the rated voltage from supercapacitor bank to load. To provide clean sinusoidal voltage even in the nonlinear load, selective harmonic elimination method for voltage control is proposed and added to the synchronous reference frame PI control. By using the method, THD less than 5% is achieved in the linear and nonlinear load. The feasibility of the proposed methods is verified through simulation and experiments with a 10kW prototype of three-phase voltage sag compensator.