Abstract- Several optimal coordination of overcurrent relays have
been done in the past by using linear programming such as simplex, two-phase simplex and dual simplex and also intelligent optimization techniques such as genetic algorithm (GA) techniques. In this paper, a powerful optimal coordination method based on GA is introduced. The objective function (OF) is developed in a such way that in addition to the coordination of overcurrent relays, the coordination of overcurrent and distance relays is also achieved. In other words, the novelty of the paper is the modification of the existing objective function of GA, by adding a new term to OF to fulfill the coordination of both overcurrent and distance relays. The method is applied to two power network systems and from the obtained results it is revealed that the new method is efficient and accurate.