A new islanding detection technique for distributed generation

Abstract

The phenomenon of unintentional islanding, which occurs when a distributed generator (DG) continues to feed power into the grid when power flow from the central utility source has been interrupted, can result in serious injury to the linemen who are trying to fix the line. Several strategies have been proposed in the past to avoid such an occurrence. Of the existing islanding detection propositions two schemes one of which is an active technique (the positive feedback technique) and the other one a passive technique (the VU and THD technique) are found by the author to be very effective but not without drawbacks. The principles of these strategies 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 above schemes. Simulation results are given for two testbeds to verify the advantages of the proposed hybrid islanding detection technique.