Parameter design and impacts on power quality of a Q-f droop curve based islanding detection method

An islanding detection method for grid-connected inverter based on the reactive power versus frequency (Q-f) characteristic of the distributed generation (DG) and the islanded load is considered in this paper. With proper reactive power perturbation proportional to the deviation of the frequency based on the Q-f droop curve, the DG is able to lose its stable operation and detect the moment of islanding once an islanding condition occurs. Meanwhile, the added reactive power would lower the power factor and degrade power quality. In this paper, parameter design is investigated and the impacts of the method on the power quality are revealed. The studies are performed and verified by simulations in a multi-inverter system in the MATLAB/Simulink environment.