Protection of Distribution Systems Integrated with Distributed Generation

Abstract

The integration of Distributed Generation (DG) in electric power systems has brought about the need for the improvement of the existing protective relaying principles used in distribution systems. This is because the integration of DG transforms the conventional single-source radial distribution system to a bidirectional multisource distribution system. Therefore, it is necessary to analyse the new short circuit fault current level, the general requirements for the integration of DG units, the requirement under abnormal conditions, power quality requirements, and the protection requirements. This chapter presents the impact of DG units on the short circuit current level and protective relaying in distribution systems. An overview of protection in conventional distribution system is first described. Afterwards, the impact of DG on the short circuit fault current and the protection of a distribution system integrated with DG are presented. Also, case studies and simulation examples on protective relaying in a distribution system integrated with DG are presented. Furthermore, some emerging technologies that can be applied to improve the protective relaying schemes in a DG-integrated distribution system are highlighted.