Gene evolution algorithm to determine minimum break point set for optimal coordination of directional protection relays in multiloops networks

To determine directional simple loops and minimum break point set in multiloop complex networks is the key step during calculating and setting of direction relays protection values. In order to greatly improve the practicability of algorithm, new concepts of protection dependency dimension and primary/backup protection dependency set are firstly put forward in this paper. Comparing protection dependency dimensions and by depth-first-search of protection dependency set could find out all the directional simple loops. Using the heuristic knowledge of MBPS (minimum break point set), the determination of MBPS is reduced to a 0-1 integer quadratic programming problem. On the basis of the principle of Gene evolution, a new approach to determine MBPS is presented for the fist time. Protection coordination of "T" shape lines and radiate network can be deal with by the method. Many examples have shown that the method is very simple, effective, and greatly reduced the complexity of problem.