Evaluation the Non-Detection Zone of Anti-Islanding Methods Using Reactive- Power Variation Method and Active-Frequency Drift Method.

Photovoltaic (PV) system has been increased around the world since PV system is becoming widespread as a clean and gentle energy source for earth. In the future, highdensity grid-connected PV systems will be interconnected with distribution network. As a result, the safety and stability of PV systems at islanding condition have become most important issues. To prevent islanding of PV inverter, several methods of islanding prevention has become widely researched and progressed. And especially, the one of method to detect islanding of PV inverter is existed reactive power variation (RPV) method and active frequency drift (AFD) method. However, there are no standardized test procedures for deciding the amount of reactive power variation, chopping fraction of output current in these prevention methods. Therefore, this paper proposes the optimal value of reactive power variation in RPV method and chopping fraction in AFD method to prevent islanding of PV inverter and is thoroughly investigated via simulation using PSIM.