Reliability iAssessment iand iIts iImprovement iof iPower iDistribution isystems (Case Study of DireDewa Substation I)

Abstract

Most of developing country including Ethiopia distribution systems has received considerably less of the attention to reliability modeling and evaluation than have generating and transmitting systems. Unreliable electric power distribution reduces power consumption, affects daily activity and downers the modern lifestyle. It impacts societal development and individuals’ income. More or less, a power distribution reliability has been a big simulating task in Dire Dawa city. The existing substation has encountered frequent power interruptions problems. The interruptions are caused mainly by the short circuit (SC) and earth fault (EF). There are also planned outages for operation and maintenance purpose. This paper focuses on enhancement of distribution system of Dire Dawa distribution network. Thus, the objective of the study is to assess the reliability of the existing distribution system and suggest solutions for reliability improvement in heuristic techniques. To limit the scope of the study, 15 kV feeder line (F4) of the substation has chosen for reliability improvement measures and also predict the reliability analysis for the future. The reliability assessment has been done on six feeders of 15kV to assess the performance of the existing system and to predict the reliability analysis for the future. The interruption data of two years 2016/17-2018/19 G.C has been used as a base year. Different alternatives have been assessed using heuristic (trial and error) method and the alternative with low SAIDI, SAIFI and EENS with a reasonable cost has been preferred. From different alternative solutions the reliability of Dire Dawa distribution system could be improved by installation of one tie switch, two reclosers and built new substation near to Dire Dawa at reasonable cost has been selected. The reliability of the Dire Dawa distribution system has been enhanced significantly by implementing reliability improvement solutions that are justified economically. The researcher identifies case four as the optimum one as comparing the power reliability improvement and the cost. Even if the uncertainty of the input data is taken into account, SAIFI has been reduced by 86% as compared with the average reliability indices values of the system in the base years. In the similar way SAIDI and EENS have been decreased by 85% and 93% respectively.