A Communication-less Protection Strategy to Ensure Protection Coordination of Distribution Networks with Embedded DG.

Distributed Generation (DG) has emerged as best alternative to conventional energy sources in recent times. Decentralization of power generation, improvement in voltage profile and reduction of system losses are some of key benefits of DG integration into the grid. However, introduction of DG changes the radial nature of a distribution network (DN) and may affect both magnitude and direction of fault currents. This phenomenon may have severe repercussions for the reliability and safety of a DN including protection coordination failure. This paper investigates the impact of DG on protection coordination of a typical DN and proposes a scheme to restore the protection coordination in presence of DG. Moreover, impact of different DG sizes and locations on DN's voltage profile and losses has also been analyzed. The sample DN with embedded DG is modelled in ETAP environment and the simulation results presented show the effectiveness of the proposed protection strategy in restoring relay coordination of the network in both isolated and DG connected modes of operation.