Analysis of overcurrent protective relaying as minimum adopted fault protection for small-scale hydropower plants

In this research, the adoption of minimum fault protection and its coordination between local utility networks and embedded generation systems is analyzed using ETAP software. Overcurrent relay plays a significant role in the protection of the system, but when it comes to small-scale protection systems, the reliability of the system becomes cost-effective. Among the various growing renewable energy technologies, small hydropower is also used as an integrated distributed generation source, but problems related to false tripping usually occur due to interconnection with local utility networks. In this study initially, the load flow studies and short circuit analysis are performed for determining appropriate time and current gradients to suitably match the system's electrical parameters. Afterward, the adopted overcurrent relaying protection scheme is analyzed using protective device coordination analysis for precise tripping of relays in the intended sequential manner under various instigated fault instances over 11 kV utility networks. The proposed system is integrated with small-scale hydropower plants. This research addresses the potential gaps and rationalizes the minimum accepted protection scheme, which not only increases the reliability of the system but also makes it cost efficient which is required for fault clearing in small hydro-based distributed generation systems.