Modelling and analysis of active islanding detection methods for photovoltaic power conditioning systems

Increasing numbers of photovoltaic arrays are being connected to power utilities through power conditioning systems (PCS). This has raised potential problems of network protection. If, due to the action of the PCS, the local network voltage and frequency remain within regulatory limits when the utility is disconnected, then islanding is said to occur. Representative methods to prevent islanding are described and a model based on PSiM (a simulation package for power electronics and motor control) and analysis of the reactive power variation (RPV) method are presented. A novel phase detector using an all-pass filter and digital phase locked loop (DPLL) is proposed, especially for the single-phase PCS. Finally, the paper provides the simulation and experimental results with a single-phase 3 kW prototype PCS. The islanding test method of IEEE Std 929-2000 was performed for verification.