Abstract

Recently, the penetration of Distributed Generation (DG) at medium and low voltages in utility networks is increasing in developed countries and takes special place for them worldwide. Due to the DGs advantages, including use of Renewable Energy which do not pollute environment and has endless nature, the application of DGs can potentially reduce the need for traditional system expansion, controlling a potentially huge number of DGs and creates a daunting new challenge for operating and controlling the network safely and efficiently. One problem that was encountered when using DGs, is an unwanted Islanding phenomenon. In this paper, an active technique for inverter based distributed generations using positive feedback of rate of change of negative voltage sequence of voltage in order to detect islanding conditions has been present. The simulation results performed in MATLAB, clearly show improved operation of this method.

Key words: Distributed Generation-Islanding, switching, active technique, rate of change of voltage positive sequences.