A comparative study based on objective functions for optimum coordination of overcurrent relays

In the optimum coordination of Directional Overcurrent Relays (DOCRs), operational time of relays is minimized with maintaining coordination criteria between Primary and Backup (P/B) relay pairs. In the literature, a range of Objective Functions (OFs) including constraints with various weightings are developed to obtain the optimum coordination of relays. In this paper, the performance of different OFs is evaluated on IEEE 30-bus system using Sequential quadratic Programming (SQP). The comparative analysis is executed to find the best OF for the coordination problem of DOCRs.