Study On The Break Point Sets Calculation Method For Directional Back-up Protection Setting Coordinal In Multiloop Network

For the coordination problem appears from the setting computation of directional back-up relays in multiloop network, this paper studies a conventional method, which resolves the coordination problem of back-up relays based on graph theory, and point out the defect of this method. A new application of graph theory for determination all of the break point sets is put forward, and then the sequence of setting coordination of back-up relays in network and the relationship of the main/back-up protection are obtained. A practical network is put up using EMTP/ATP and the work of setting computation for tree zone interphase distance protection is done, which presents the whole process from establishing new simple algorithm to make it into practice. The optimum BPS with engineering significance is determined. This algorithm and ideas have preferable utility value in three zone setting computation of protections in electric power system.