Distributed generation adverse impact on the distribution networks protection and its mitigation.

Abstract

Integration of Distributed Generation (DG) generates problems for the protection of Distribution Networks (DNs) in power systems. When DG is integrated into a power distribution system (DS), the radial nature of the network is altered and the power starts to flow in a reverse direction. In addition to the reverse flow of power, the DG upsurges the fault current level and affects the existing time intermission coordination of the protective overcurrent relay. This study proposes a reverse power relay (RPR) and Fault Current Limiter (FCL) to mitigate the fault current level and reverse power flow in a Distribution Network (DN) by the use of DG. The FCL works only as a unidirectional fault current limiter (UFCL) by restricting the flow of fault current that occurs in the main grid (MG) of the DG. However, FCLs can protect the flow of fault currents from the MG by affecting the operational flexibility and reliability of the DG. To overcome the flow of fault current of the DG, this study proposes RPR to monitor the power flow to the DG. Collectively the study focuses on the protection of radial DS by using RPR and UFCL. The analysis and the modeling were conducted on the 15KV DN of the radial feeder in Debre Markos DN. The 3Φ fault analysis (which is more severe than others) was performed to validate the protection capability of the mitigation techniques which were proposed in this study.