Research on reliability evaluation of the distribution system based on grid asset quality supervision and management system

State Grid Corporation has further strengthened the standardization of the safe grid operation and the building of grid asset quality supervision and management system(GAQS MS) with the proposition of “Twelfth Five Year Plan” and “three sets of five”. The GAQS MS realizes the whole-course supervision and management of planning, designing, construction, production and other aspects of the grid. Among them, the user power supply reliability management system provides both important data for power supply reliability assessment and strong support for further reliability management. Based on the GAQSMS, the overall framework of distribution network reliability assessment and the assessment indexes of component and system levels are proposed in this paper. Using the principles of stratifying based on voltage level and dividing as per power supply mode, the distribution system is divided step by step, and the distribution network reliability assessment involving the substation main wiring is completed. In this paper, the minimal-cut-set method commonly used for distribution network reliability assessment is improved. The improved method can not only solve the branch-node mixed cut sets, but also automatically search out related component lists when bus line, circuit breaker, disconnector or other element in the main wiring fails so that the system influence of the expanding failure of the element in the substation main wiring is considered sufficiently. Finally, based on the GAQSMS, using Fortran and C++, the distribution network reliability assessment is completed, and the accuracy of algorithm and procedure is verified through the calculation of actual distribution network.