Directional relays for distribution networks with Distributed Generation

Due to its current limitation, Inverter-interfaced Distributed Generation (IIDG) is supposed to have little impact on protection system of distribution networks. However, in case of high power IIDG, the situation could be changed. This paper aims to show situations in which IIDG could provoke false tripping to overcurrent protections along distribution feeders. Proposed solution is to provide directional function to these protections. This function is based on local algorithms and does not require voltage sensors (to reduce the cost). Another part of this work is to implement the method of symmetrical components in grid with presence of IIDG.