Research On Complex Distribution System Reliability Evaluation

Distribution system connects the consumer directly, its failure will lead directly to the user's outage. Therefore, the reliability of distribution system has a great influence on consumers. With the economic development and higher requirements of power quality, distribution system scale become progressively larger, the complexity of its structure is growing, and its operation modes are complicated and variable. There are some problems in previous studies on methods of distribution system reliability, such as long calculation time, low calculation accuracy, and only suitable for specific structure of distribution. So they could not well adapt for distribution system development. Aiming at features of distribution system large scale, complex structure and variable operation mode, this paper study on distribution system reliability model, reliability algorithm, and its functions in distribution planning and construction.This paper introduces the basic concepts of power distribution system and its characteristic, summarizes the existing distribution system reliability evaluation methods and points out the advantages and disadvantages of each method. Failure effects analysis method of analytical methods is used as the basic method for the reliability evaluation of distribution system. Common distribution system reliability evaluation indices are also given in this paper. The distribution system components and system reliability model are built in this paper. On this basis, Index-Search algorithm is proposed and used for reliability evaluation of distribution system. This algorithm takes the power component as the enumeration unit, uses search method to simulate switches motion after component fault in order to get the outage status of the loads, and then calculate the reliability indices of loads and distribution system. Index tables record the key distribution system topology, action switches after component fault and action time of switches. Though these index table records, a large number of invalid searches are reduced, the speed of search algorithm and the calculation accuracy of load outage time are improved too. This algorithm takes into account the spare components, planned maintenance, refused action of switches, and multi-power supply, etc. It matches the actual distribution system operation mode.According to Index-Search algorithm, a reliability evaluation of distribution system software which has a visual interface is developed based on C++ Builder 6.0 and Microsoft Access 2003 platform. It can maintain the distribution system data conveniently, view action switches and outage status of loads after components failure, calculate distribution system indices and import them into Microsoft Excel.The tested results from RBTS Bus 6 distribution system and high-speed rail power distribution system show that this algorithm could calculate the reliability indices correctly, quickly, and well adapt for variety of complex structures of distribution system. According to the result of the weak points of distribution system, structural reform program for distribution system is proposed. The reliability indices of transformed distribution system are calculated, and the effectiveness of reform program is verified.