Power Distribution System Reliability Assessment and Improvement by Placement of Auto Reclosers and Fuses based on Fuzzy Logic (A case Study of Weliso Town)

Abstract

Electric power supply reliability is very crucial factor for economic, political and technology development of the country. Currently, there is a rapid growth of industrial, commercial, residential and other service supplying institutions. All of these institutions need reliable power supply. A power system is reliable if it serves customers at load end without interruption. Increasing distribution system reliability is a necessity in order to reduce interruption events. In this thesis, Weliso Town are taken as a case study. As Weliso Town 15 Kilo Volt(KV) feeder has very important institution (Banks, Telecom, Hospital and University) and residential customers are facing a big challenge in their business and services due to frequent interruption and utility has taken long time to restore it. Major causes of interruptions are due to earth fault, short circuit and planned outage. The existing System Average Interruption Frequency Index (SAIFI) of Weliso is 272 interruptions per customer per year and System Average Interruption Duration Index (SAIDI) is 232 hoursper customer per year respectively. These distribution systems are not reliable as Ethiopian Electric Agency standard directives which set SAIDI is below or Equal to 25 and SAIFI is below or equal to 20). The objective of the study is to assess the reliability of the current distribution system and propose solutions of reliability improvement by placement of Auto Reclosers and Fuses to mitigate the identified power reliability problems by making a detailreliability analysis. These analyses is modeled and evaluated using Electrical Transient Analysis Program (ETAP) tool to Simulate SAIFI, SAIDI and Expected Energy not Supplied (EENS ). Optimal placement and coordination of Auto Reclosers and Fuses is determined by the Fuzzy Logic optimization technique using Mat lab software. After optimally placement of Recloses and Fuses at the needed location, the SAIFI, SAIDI and EENS are improved by 93.36 %, 87.07% and 87.65% respectively. The proposed solution has been saved 1656303 ETB per year from the unsold energy of one feeder only with 2.67 years?��? payback period investment.