A framework for investigative analysis of islanding and pre-islanding behaviour of solar PV inverters connected to distribution grids

The commercially available, inverter-resident anti-islanding methods are expected to be challenged by the future scenario of increasing photovoltaic penetration and some have shown limitations presently. A predictive approach for islanding-detection can be a smarter solution than the existing reactive approach. Accordingly a framework having a modified IEEE radial test feeder with a solar photovoltaic inverter has been developed in Matlab-Simulink to investigate the phenomenon and explore possible precursors to it. Islanding behaviour in the region of common coupling was studied to verify the modeling approach. Situations deemed to occur commonly in a high-penetration scenario were simulated and were found to result in anomalous currents that might cause unintentional islanding. Results from RTDS study validated the same. Among other observations, the excessive reactive power in the modified network was found to affect the total harmonic distortion in grid-side current before the simulated islanding and the circuit breaker arcing current after islanding.