A Novel Structure for Three-Phase Four-Wire Distribution System Utilizing Unified Power Quality Conditioner (UPQC)

This paper presents a novel structure for three-phase four-wire (3P4W) distribution system utilizing unified power quality conditioner (UPQC). The 3P4W system is realized from three-phase three-wire (3P3W) system where the neutral of series transformer used in series part UPQC is considered as the fourth wire for 3P4W system. A new control strategy to balance the imbalanced load currents is also presented in this paper. The neutral current that may flow towards transformer neutral point is compensated by using a four-leg voltage source inverter (VSI) topology for shunt part. Thus the series transformer neutral will be at virtual zero potential during all operating conditions. The simulation results based on MATLAB/Simulink are presented to show the effectiveness of proposed UPQC based 3P4W distribution system.