A novel algorithm to determine minimum break point set for optimum cooperation of directional protection relays in multiloop networks

Determining minimum break point set (MBPS) is necessary before setting distance protection relays or zero-sequence protection relays in multiloop extremely high voltage power networks. Determining directional simple loops (DSLs) and relative sequence groups (RSGs) is the prerequisite of traditional algorithms which are used to determine MBPS. In order to reduce the CPU time and complexity of calculating MBPS, a new concept named as protection relay dependency dimension (PRDD) is presented for the first time in this paper. By comparison of PRDD in a multiloop network, the MBPS can be determined, and the process of comparisons will not stop until the MBPS of the multiloop networks is discovered. In the meantime, the RSG could be easily determined by means of judging whether the primary protection relay set of a protection relay is null or not. The new algorithm leaves out those laborious steps, such as determining all of the DSLs and RSGs. Some examples are given to illuminate the novel algorithm presented in the paper to be simple and effective.