Dual feasible direction-finding nonlinear programming combined with metaheuristic approaches for exact overcurrent relay coordination

In the present paper, dual usable feasible direction-finding nonlinear programming associated with metaheuristic approaches is applied to directional overcurrent relay coordination. Rosen's gradient projection and Zoutendijk's method are selected as nonlinear programming techniques, and the electro-search algorithm combined with Cuckoo optimization are chosen as the metaheuristic part. These algorithms are combined in a suitable manner based on their capabilities. First, all miscoordinations are removed by combining the metaheuristic part with a proposed simple manual manner. After eliminating all violations, the metaheuristic part is cooperated by Rosen's gradient projection technique. This loop is repeated until no change can be observed for a predefined number of iterations. Then, Zoutendijk's method is applied to the results obtained by the previous algorithms. The proposed method is tested on both 8- and 30-bus test systems. Then, it is shown that the total primary operating times obtained, even for non-communication coordination scheme using relays with normally inverse characteristics, are considerably lower than those obtained by dual setting approaches.