An Adaptive Protection Scheme for Distribution Networks with Distributed Generation Sources in Various Operational Modes

Distributed Generation (DG) is a common technology in today’s distribution networks due to its exclusive benefits. However, DG units introduce a series of new issues to distribution network beside their benefits. Adding a DG unit to the network can change the direction and magnitude of the power flow and fault currents through branches. It may cause the failure of the original protection system or false tripping of some existing relays. In this paper, a new adaptive approach is introduced for classification of different DG topologies in distribution network using the existing setting groups in over current relays. This method determines those settings such that maximum number of the possible scenarios for different operations in distribution system are covered including grid-connected mode, autonomous mode, and DGs capacity changes. In order to verify the performance of the new method, two simulation studies are performed on 14-node and IEEE 33-node distribution network test systems. DIgSILENT software has been employed to simulate the network in various operational modes.