Novel application of dual-output four-leg converter for unified power quality conditioner

This paper proposes a novel UPQC system based on dual-output four-leg converter. The proposed system completely fulfils the main functions of the conventional UPQC system. It is also capable of compensating any unbalance characteristics at load side (parallel side) or grid side (series side) such that the drawn currents from the grid and the voltage of the load are balanced and sinusoidal, regardless of the load or utility voltage characteristics. Another advantage of the proposed system is that despite the conventional type in which series convertor is underutilized due to its low modulation index, the proposed system is fully utilized at both series and parallel sides. Moreover, the number of semiconductor devices is reduced compared to counterpart topologies. The validity of operation of the proposed UPQC is verified via simulation.