Influence analysis of DG penetration levels and grid-connected positions on traditional current protection

With the introduction of distributed generation (DG), the electric distribution system would be converted from a single-source network into a multi-source network. This changed network conditions due to DG pose new challenges to the protection system on distribution level. On the basis of introducing traditional overcurrent protection configuration of distribution system feeds, this paper discusses the various impacts of DG on relay protection of distribution network under different interconnection positions and different DG capacities. The impacts of these two variables on system protection can in principle be treated in two different aspects, the impacts of DG capacity with fixed interconnection position and the impacts of different interconnection positions with fixed DG capacity. All of these analyses may provide some theoretical basis for future´s relay protection algorithm research on distribution level.