Compensation of voltage sags and swells using a single-phase AC-AC converter

In this paper, a topology to compensate voltage sags and swells simultaneously in critical loads is proposed. It consists in a single-phase AC-AC converter in a matrix arrangement, which keeps a continuous regulation in the output voltage. The proposed scheme has the capability to compensate up to 25% voltage sags and 50% voltage swells. The AC-AC converter does not require energy storage devices and it is connected between the AC mains and the load by using a series transformer. One of the advantages of this topology is that taps for the coupling transformer are no necessary to change the polarity of the compensation voltage. A four step switching technique is used to drive the AC-AC converter switches, executing snubberless operation. The reference signal is generated using single-phase d-q theory, obtaining a fast response time and high regulation. Simulation and experimental results of a 5 kW capacity, 127 V, 60 Hz equipment are presented.