A Review of the Coordination of Over-current Relay Protection in Sub-transmission Stations Using Computational Optimization Techniques

Adding more power plants and transmission stations to the power system of Nigerian has been influenced by a substantial and rapidly growing nonlinear load demand over the past decade. This has resulted in an exponential increase in fault current due to complexity inherent in the Nigerian power system network. If not properly coordinated, this can lead to undesired tripping of the protection relays. Hence, it is crucial to ensure that relays installed in the grid can effectively detect and isolate fault current from both the upstream and downstream in other to maintain the integrity of the grid. To achieve this, an optimal predictive, analytical and coordination scheme (PACS) for overcurrent relays (OCRs) is introduced into the system. This paper provides a comprehensive examination of various optimization techniques used for achieving PACS in the integrated power networks with review of literature on OCRs. The review emphasizes the features, benefits and drawbacks of the techniques employed to address overcurrent protection coordination issues in a balanced and objective way. Additionally, the paper discusses potential avenues for future research in the field of PACS that could lead to significant advances in the field of optimal OCR coordination.