A Study ofModified Three-Phase Four-Wire UPQC Topology Mamatha

Abstract

The unified power quality conditioner (UPQC) is a custom power device, which mitigatesvoltage and current-related PQ issues in the power distribution systems. In this paper, a UPQC topologyforapplications with non-stiff source is proposed. The proposed topology enables UPQC to have areduced dc-link voltage without compromising its compensation capability. This proposed topology alsohelps to match the dc-link voltage requirement of the shunt and series active filters of the UPQC. Thetopology uses a capacitor in series with the interfacing inductor of the shunt active filter, and the systemneutral is connected to the negative terminal of the dc-link voltage to avoid the requirement of the fourthleg in the voltage source inverter (VSI) of the shunt active filter. The average switching frequency of theswitches in the VSI also reduces; consequently the switching losses in the inverters reduce. Detaileddesign aspects of the series capacitor and VSI parameters have been discussed in the paper.