Javad Gholinezhad - Electrical Engineering Department, Zanjan University, Iran
Kazem Mazlumi
Peyman Farhang

Achieving to minimum operation time and coordination among all relays is vital issue, hence relay settings must be adjusted to satisfy these subjects. For optimal coordination of overcurrent relays, linear programming (LP) techniques such as simplex, two-phase simplex, dual simplex and mixed integer nonlinear programming (MINLP) have been used. In MINLP technique, current setting and time multiplier setting have unknown values and must be calculated with consideration their constraints. Heuristic techniques are best solutions to solve these problems. In this paper, The MINLP technique is applied to solve the relay coordination problem based on PSO algorithm, which is one of the capable heuristic techniques to solve constrained optimization problems

Optimal coordination; Relay settings; Directional Overcurrent relays; PSO algorithm; MINLP technique