Interphase AC–AC Topology for Voltage Sag Supporter

A new topology is proposed in this paper to compensate voltage sags in power distribution systems. Voltage sag is one of the major power quality problems encountered by industries. The traditional voltage sag compensator, which is a dynamic voltage restorer based on energy storage device with a series-connected voltage-source inverter, is not adequate for compensating deep and long-duration voltage sags. As per the sensitive load concern, deep and long-duration sags are more vulnerable than shallow and short-duration sags. To compensate the voltage sag, a new interphase ac-ac topology is proposed that needs no storage device. The compensator of each phase is connected on the other two phases and the power is tapped from them. A single-phase compensator is realized with two ac chopper circuits and two transformers. By controlling the duty cycle of each ac chopper, the required voltage is realized to compensate the voltage sag. Analysis, simulation, and experimental results are presented to demonstrate the proposed concept.