Reliability evaluation for distribution system with the switch fault

In this paper, a new method based on equivalent network composed of zone-networks (zone-elements) is proposed and applied to reliability evaluation of distribution systems with the switch fault. In the method, the one-line diagram of the system is partitioned into zones with the auto (or non-auto) switch being the boundary; then two equivalent networks are respectively formed by two types of zone-elements (Type A or Type M); a valid proposition is further suggested for the simplification of the equivalent networks; based on that, following effective measures are adopted: (1)the switches are looked as one component of the relevant zone-element, which avoids the sole consideration of the switch fault; (2) the zone-loads and the zone-elements are treated as the basic evaluation object and unit respectively, and a classification evaluation strategy is further designed for the calculation of reliability indexes, which greatly reduces the number of the units needed to be traversed. Test results of the samples demonstrate that the new method is effective and valid.