A study on optimal coordination of definite-time relay based on genetic algorithm

Relay optimal coordination is of great significance in bringing the role of the protection device into full play, improving the integral performance and ensuring the best integral effect of the protection system. In view of the problems existing in optimal coordination of definite-time relay, this paper presents a new method based on the genetic algorithm. In this method, a new coding technique, called constraint interval coding, is adopted to enhancing the efficiency and precision of optimization. The result of an example shows that the new method is effective for optimal coordination of definite-time relay. The application of the new method in the multi-loop network and the mixed protection system with inverse-time relay and definite-time relay is discussed further.