Hybrid Fuzzy-PI Controller Based MC-UPQC for Power Quality Enhancement.
Power quality problems like voltage sag/swell, flickers, interruptions, voltage distortions and imbalance can have drastic effects on home appliances, industries, processing plants and other applications. In this paper, a novel multi-converter unified power quality conditioner (MC-UPQC) is proposed for simultaneous compensation of voltage and current in multibus/multifeeder distribution systems. A MC-UPQC is a combination of one shunt active power filter (APF) and two or more series APFs. MC-UPQC can be applied to adjacent feeders to compensate for supplyvoltage and load current imperfections on the main feeder and full compensation of supply voltage imperfections on the other feeders. In this paper, a two feeder MC-UPQC is used, which has one shunt APF and two series APFs. All APFs are connected back to back on the DC side and share a common DC link capacitor. As control of this DC link capacitor is very critical for the better performance of MC-UPQC, a novel hybrid fuzzy-PI controller is designed, which is more robust to parameter changes, is non-linear and has a fast dynamic response along with superior steady state response. Through simulation results, it is shown that the hybrid fuzzy-PI controller has performed very well and MC-UPQC is able to compensate supply voltage and load current imperfections on feeder1 and fully protect the sensitive/critical load on feeder2 against distortion, sag/swell, and interruption.