An active islanding-detection method for power conditioning subsystem of utility interactive photovoltaic system

Islanding is a scenario where dispersed generators could be severed off from the grid, but continue to operate after the utility supply is disconnected. The occurrence of islanding events may complicate the orderly reconnection of the utility network and pose a hazard to utility personnel. In this paper, a novel active islanding-detection method for utility interactive photovoltaic systems is proposed. In this approach, a control circuit is developed and implemented for producing the designated amount of deviation, which can be reflected appropriately to the output of the photovoltaic system. Then, by coupling with a proposed algorithm, this amount of deviation will be a crucial indicator to detect the islanding. Besides, this method is capable of reactive power control such that system power factor can be better ensured. The proposed approach has been tested through different scenarios. By case studies with numerical simulation, the method was verified with simplicity, feasibility and efficiency for power system protection applications.