A unified power quality conditioner for voltage regulation of critical load bus

The paper discusses the operation and performance of a unified power quality conditioner (UPQC). A UPQC is a versatile device that can be used for various functions. The main aim of the paper is to operate the UPQC in such a way that it tightly regulates the bus voltage of critical loads against unbalance, harmonics, voltage sag/swell and other disturbances occurring in a distribution system. The performance of the UPQC is compared to that of a dynamic voltage restorer (DVR). Both the UPQC and the DVR are operated in the closed-loop state feedback switching control. Through simulation studies using PSCAD/EMTDC it is shown that the UPQC performs significantly better than the DVR.