Development of adaptive protection scheme for distribution systems with high penetration of distributed generation

Conventional power distribution system is radial in nature, characterized by a single source feeding a network of down-stream feeders. Protection scheme for distribution system, primarily consisting of fuses and reclosers and in some cases, relays, has traditionally been designed assuming the system to be radial. After connecting distributed generation (DG), part of the system may no longer be radial, which means the coordination might not hold. The effect of DG on coordination will depend on size, type and placement of DG. This paper explores the effect of high DG penetration on protective device coordination and suggests an adaptive protection scheme as a solution to the problems identified. Results of implementation of this scheme on a simulated actual distribution feeder are reported.