AN IMPROVED SANDIA FREQUENCY SHIFT METHOD FOR ISLANDING DETECTION OF GRID CONNECTED PHOTOVOLTAIC INVERTERS
Islanding detection schemes have been widely studied recently due to the expected high penetration of distributed generations (DGs) in future distribution networks. It is important for grid – connected inverter based DGs to be equipped with a reliable islanding detection method that allows efficient disconnection of DGs when an islanding condition is detected. In this paper, an improved Sandia Frequency Shift (SFS) method for islanding detection of grid connected photovoltaic (PV) inverters is proposed. The proposed technique through reducing chopping fraction cf0 and adjusting the feedback gain K increase exponentially to reduce the total harmonic distortion (THD) of the current waveform. To evaluate the performance
of the proposed technique, various islanding events have been implemented using a grid-connected PV system modeled in a Matlab/ Simulink, which are based on the IEEE 929-2000 and IEC 62116 standards. The simulation results show that the proposed method results in more accurate detection of the islanding phenomenon in the shortest possible time.
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