A new phase drift anti-islanding method for grid-connected inverter system

Islanding phenomenon of grid-connected photovoltaic (PV) power generation system refer to their independent operation when the utility is disconnected. Since the islanding phenomenon causes significant hazards to personnel and equipment, PV power generation systems are required to detect and prevent the islanding operation. The islanding detection methods can be classified into two categories : passive and active methods. If the power mismatch of real and reactive power of between the load and renewable power generation systems are small, the detecting accuracy of passive methods might be lowered. On the other hand, active methods can allegedly deteriorate power quality. This paper proposes a novel anti-islanding method that enables islanding detection by using current command with phase difference. The proposed method is able to not only reduce the non-detection zone (NDZ) but also minimize power quality deterioration. To confirm the validity of the proposed method, this paper presents simulation results, it was recognized that the whole procedure, from removal of the grid to system shutdown, was completed within 0.5 seconds.