Improvement of Power Quality in Distribution System with Grid Connected RES

Abstract: With the help of power electronic Converters/Inverters renewable energy resources (RES) are being increasingly connected in distribution systems. In this paper, Photo Voltaic (PV) system is integrated to a three phase four wire distribution system. The non-linear loads and use of power electronics based equipments at PCC generate harmonic currents, which may deteriorate the power quality. This paper suggests a new method that consists of a four leg inverter i.e. capable of simultaneously compensating problems like current imbalance and current harmonics, and also of injecting the power generated by renewable energy power sources. The fourth leg of inverter is used to compensate the neutral current of load. The grid interfacing inverter can be utilized as power converter to inject power generated from RES to the grid, and shunt APF to compensate current unbalance, load current harmonics and load reactive power demand. The inverter is actively controlled in such a way that it draws/supplies fundamental active power from/to the grid. All of these functions may be accomplished either individually or simultaneously.

Keywords: Active power filters (APF), distributed generation (DG), power quality (PQ), renewable energy (RE) and Voltage source Inverter (VSI).