Steady-State Model for Open Unified Power Quality Conditioner for Power Quality and Energy Efficiency Improvement of Radial Distribution Networks

Abstract

This paper presents a steady-state model for open unified power quality conditioner (UPQC-O) with storage unit to improve the power loss and power quality of radial distribution networks. It consists of two voltage source inverters, i.e., series and shunt inverters without any interconnected DC link. Thus, both the inverters can be placed in different locations in a network. The shunt inverter is used to eliminate the harmonics created by load and to provide reactive power compensation. The series inverter is used for dual-purpose, i.e., for the protection of all its downstream loads from voltage sag, and to provide reactive power compensation during healthy condition. Since both the inverters are connected to DC storage units, they also provide active power compensation at their respective locations. The proposed UPQC-O model is suitably incorporated to the forward-backward sweep load flow algorithm so as to carry out an exhaustive search to examine the effect of its placement. The results show that an appropriate placement of the shunt inverter provides significant power loss reduction, whereas the series inverter placed near to the substation results in better power quality. The rating requirements for UPQC-O and battery are also determined and analyzed.