Abstract: Distributed Power generation Systems (DPGSs) integrate different power plants in to a unit. DPGSs based on renewable energy sources experience a large development worldwide. The excessive use of power electronics and nonlinear loads lead to power quality problems. Effects of poor power quality like sag, swell, distortion in waveform, harmonics, reactive power generation has affected both grid as well as utility sectors. The control of distributed generation systems should be improved to meet the requirements for grid interconnection. In this thesis, Photo Voltaic (PV) panel, Fuel Stack & Wind Energy system are integrated to the three phase four wire distribution system. Renewable energy resources (RES) are connected to the grid through a grid interfacing inverter for power quality improvement. Here the control is done by the grid interfacing inverter using PI controller and PWM technique. The grid interfacing inverter can act as an active shunt filter where it can transfer active power to the grid and can mitigate the load current harmonics and supply the load reactive power demand. The source side power factor is improved and voltage sag is eliminated. Total Harmonic Distortion of the grid connected system is analysed. The analysis is used to predict the behaviour of grid connected distributed power generation systems.

Keywords: Distributed Generation (DG), Pulse Width Modulation (PWM), Point of Common Coupling (PCC), Power Quality (PQ). Renewable Energy Sources (RES).