Distribution system load estimation and service restoration using a fuzzy set approach

An approach based on fuzzy set theory is developed to estimate the loads in a distribution system and to devise a proper service restoration plan following a fault. To estimate the loads on branching points without real-time meters, typical hourly load patterns for several types of days are established for commercial, industrial, and residential customers. These load patterns are characterized by some linguistic variables using fuzzy set notations. The load of a branching point is estimated through fuzzy set operations. With the estimated loads at hand, a heuristic search method is proposed in order to reach a restoration plan with minimal number of switching operations in a short time. To demonstrate the effectiveness of the proposed fuzzy approach, load estimation and service restoration on a distribution system within the service area of Taipei West District Office of Taiwan Power Company are examined. It is found that, following a fault event, a proper restoration plan can be reached very efficiently. Therefore, the proposed approach can provide valuable information to distribution system operators in reaching a service restoration plan