Islanding detection assessment of multi-inverter systems with active frequency drifting methods

Islanding is one important concern for grid connected distributed resources due to personnel and equipment safety. Inverter-resident active islanding detection methods (IDMs) inject disturbances into the supply system and detect islanding based on the responses of locally measured parameters. Frequency drifting IDMs are very effective in systems with a single inverter but it is believed that their effectiveness might be reduced in multi-inverter systems due to mutual interferences. This paper discusses the effect of inverters with passive IDM on the islanding detection capabilities of inverters with active frequency drifting IDMs and also interferences between the latter. Non-detection zones (NDZs) of multi-inverter systems in a load parameter space are used as analytical tool. Simulation and experimental results are provided to validate the NDZs of the multi-inverter systems with active frequency drifting IDMs. Index Terms--Distributed generation (DG), inverters, islanding detection, non-detection zones, photovoltaic systems.