Unified power quality conditioner allocation for reactive power compensation of radial distribution networks

This paper presents an investigative study on unified power quality conditioner (UPQC) allocation for reactive power compensation of radial distribution networks. An UPQC consists of a series and a shunt inverter. The UPQC model based on phase angle control (UPQC-PAC) is used. In UPQC-PAC, the series inverter injects a voltage with controllable phase angle in such a way that the voltage magnitude at load end remains unchanged. Owing to the phase angle shift, the series inverter participates in load reactive power compensation along with the shunt inverter during healthy operating condition. The UPQC-PAC model is suitably modified so as to provide the reactive power compensation of a distribution network. The impact of the UPQC-PAC allocation is studied by placing it at each bus of a network, except the substation bus, one at a time. A load flow algorithm including the UPQC-PAC model is devised and used in the determination of its optimal location in a network. The simulation study shows that the optimal allocation of UPQC-PAC results in significant amount of power loss reduction, under voltage mitigation, and enhancement of voltage stability margin. Better power loss and bus voltage are obtained with UPQC-PAC compared with some existing reactive power compensation approaches.