Control of islanded inverter interfaced Distributed Generation units for power quality improvement

A load sharing control strategy for operating of a distribution system consisting of multiple inverter interfaced Distributed Generation (DG) unit when isolated from a main utility in order to improve continuity and quality of electricity to important loads is presented and tested in this paper. In the stand-alone network, a Master DG unit exists as voltage and frequency reference and the other units work on synchronize with this unit and produce energy to loads. A supervisory controller defines all Distributed Generation units' reference powers with consideration of system and unit normal rating in order to maintain reliable and high quality power to the loads. Simulation results on IEEE 37 node test system verify that the proposed control scheme is effective for stable working of the stand-alone network.