Augmenting protection coordination index in interconnected distribution electrical grids: Optimal dual characteristic using numerical relays

Abstract One of the most significant tasks of protection coordination of power networks is the satisfaction of coordination between protective equipment. With growing penetration level of distributed generations)DGs), selectivity issue of overcurrent relays is very imperative in active distribution systems .Therefore, sustainable electricity needs to enhance the protection coordination index (PCI). These enhancement will cause the development of DG penetration in power networks. In this paper, time-current-voltage characteristics and dual-setting directional overcurrent relays (DOCRs) are jointly deployed to improve PCI in interconnected distribution networks where the coordination process seems a complex problem. Dual-setting relays can trip in forward and reverse directions with individual settings in both directions which provide proper flexibility to improve PCI. Also, time–current-voltage characteristics employ the voltage parameter in operation time of relays which can decrease the optimization process to cause higher flexibility in the coordination process. besides, the mentioned protection model is developed by user-defined time–current-voltage characteristics to improve PCI. The suggested scheme is modeled and presented as a nonlinear programming approach that is tackled by the genetic algorithm (GA) and comparing performance with Grey Wolf Optimization (GWO). In this paper, to evaluate the performance and scalability of the proposed method, IEEE 14-bus and 30-bus system is applied. The advantage of the proposed scheme is the ability to implement in numerical relays, in which paper is expressed in the form of protection logic and description of respective logic blocks. Results depict the significant improvement in PCI.