Hybrid islanding detection technique for single-phase grid-connected photovoltaic multi-inverter systems

This study presents the performance of a novel hybrid islanding detection method for multi-single-phase photovoltaic (PV) inverters based on the combination of four active methods and three passive methods. Although islanding detection in PV multi-inverter systems has been widely researched, most islanding studies are focused on three-phase inverters, rather than single-phase ones. In this study, different active and passive methods are used to detect the islanding of four paralleled single-phase PV inverters. By combining those methods synergistically, it reduces their weakness of each method, while combining their advantages. The novelty of the proposed system methodology consists of four paralleled single-phase inverters equipped with four different active methods, namely active frequency drift, Sandia frequency shift (SFS), sliding mode frequency shift, and Sandia voltage shift triggered by a block composed of three passive methods: voltage frequency protection, rate of change of frequency, and DC-link. This novel hybrid system is studied under different detailed scenarios, where it shows its performance and characteristics.