A hybrid islanding detection technique using voltage unbalance and frequency set point

The phenomenon of unintentional islanding occurs when a distributed generator (DG) continues to feed power into the grid when power flow from the central utility source has been interrupted. This phenomenon can result in serious injury to the linemen who are trying to fix the power outage problem. Several techniques have been proposed in the past to avoid such an occurrence. This paper first gives an overview of the dominant islanding detection techniques. Then, the principles of two of the suggested techniques are combined to obtain a new hybrid islanding detection technique for synchronously rotating DGs. Simulation results show that the proposed hybrid technique is more effective than each of the techniques used. Simulation results are given for two testbeds to verify the advantages of the proposed hybrid islanding detection technique.