Planning the coordination of overcurrent relays for distribution systems considering network reconfiguration and load restoration

Installation of branch switches and tie‐lines in the distribution system provides the flexibility of load restoration during the occurrence of a fault, i.e. N− 1 state. These switches and tie‐lines change the network topology to isolate the fault and restore the unaffected network. As a consequence, the relays may delay or fail to operate for a possible incoming fault, i.e. N− 1−1 state; therefore, this study proposes an optimal relay setting of overcurrent relays subject to N− 1 and N− 1−1 states. Laterally, the proposed model maximises the load restoration such that the network remains radial. Also, it uses a meta‐heuristic algorithm to arrive at an optimal solution. Moreover, the optimal solution is validated using GE Multilin, model‐750/760 overcurrent relay in ETAP (industrial simulation software). The efficacy of the proposed method is examined on 33‐bus and a practical 14‐bus distribution system.