Study on Reliability Improvement of Distribution Network Based on Self-healing System

In order to meet the increasing reliability requirements of urban distribution network, based on the typical wiring of urban cable ring network, combined with three typical automated protection modes, this paper uses the analytical method to study the data about power outage caused by faults occurred on outlet circuit breakers, line segments, subsection switches, load switches and distribution transformers (DTs) respectively. Then the corresponding reliability improvements are put forward. The analysis results show that to assure the reliability of class A region, the centralized distribution automation and load switches should be adopted instead of decentralized system and subsection switches. To assure the reliability of class A+ region, the scheme of differential protection plus self-healing should be used, with subsection switches and tie switches replaced by circuit breakers and each circuit breaker in the ring main units (RMUs) enclosed in either Vacuum or SF6 box separately.