Islanding Detection Method for Distributed Generation Systems

Aiming at the disadvantages of existing methods,a new passive islanding detection algorithm is proposed based on analyzing the basic principle of islanding detection.The value of Δf/ΔVL is regarded as the detection index and the identification of islanding is realized by comparing the evaluated value with the given threshold value.Simulation study with MATLAB is done with considering the impacts of several disturbances such as change of local load and voltage sag of grid on islanding detection.The results show that the algorithm is simple and feasible,fast and reliable,and the non-detection zone is very small.