Wide-area current protection for distribution feeders with Distributed Generators

The distribution network changes from simple radial single-source system to complex multi-source one because of the introduction of distributed generators (DGs). Consequently, it brings such new problems to protection of traditional distribution system as false tripping, reduction of sensitivity, loss of selectivity and so on. In order to solve these problems, this paper proposed a novel distribution system (DS) protection scheme based on wide-area communication system and negative sequence current dot product (I₂DP). Protection opening method has an excellent performance in fault feeder selection, but it can´t be used in fault section selection because the capacity of DG is much smaller than that of DS. So I₂DP was proposed to do this job. It can effectively decide the direction of fault section without voltages. Combining the relay current and I₂DP, false tripping of relay will be eliminated. The simulation results proved its effectiveness and practicability of the scheme.