Islanding Detection of Inverter based Grid Tied Photovoltaic System in Microgrid using Maximum Power point Tracking Method

Integration of DGs into the electrical network has risen significantly in the past decade and gridconnected PV systems (GCPVS) being the most popular, due to its environmental sustainability and economic efficiency. However, the connection of the renewable energy sources poses many issues related to Islanding condition. Detection of islanding condition in the DG system is a major issue that needs to be addressed. This work proposes a simple yet accurate islanding detection method (IDM) for the GCPVS by injecting a known deviation in step-size in the conventional maximum power point tracking (MPPT) algorithm. Due to this injection of disturbance, the absolute deviation of the output voltage may exceed the pre-set limit. This shifts the operating point of the system from its maximum power point which results to a drastic active power output reduction and subsequently a significant dip in the voltage in the islanded mode. Also, the DG is restored back into operating at maximum power condition after islanding classification. This makes the IDM suitable for microgrids where critical loads are catered. An intentional delay of few cycles has also been provided to overcome false-tripping in non-islanding scenarios. The presented scheme is therefore fast, accurate, does not compromise with the power quality, simple and inexpensive.