The wide-area protection system has strict requirements on the real-time and reliability of communication. Currently

the optimal routing algorithm of wide-area protection communication system is based on the requirements of delay and reliability

without taking into account the standby problem after the failure of the main path. To solve this problem

this paper proposes a multi-path routing algorithm based on the ant colony algorithm to improve the reliability of wide-area protection communication. The main and standby paths which satisfy the requirement of wide-area protection communication are calculated through the proposed routing algorithm. The basic ant colony algorithm is improved on pheromones based on time delay and the availability of a link. By the improved ant colony algorithm

multiple paths of different qualities from the source node to the destination node can be found. The experimental results show that the proposed method can meet the requirements of real-time performance and reliability of the wide-area protection communication system. This work is supported by National Basic Research Program of China(973 Program)(No. 2012-CB215200)

Hebei Provincial Natural Science Foundation of China(No. E2013502267)and Fundamental Research Funds for the Central Universities(No. 13MS68).