Assessment of Distribution System Reliability and Possible Mitigation by Using Reclosers and Disconnectors: The Case of Cotobie Distribution Station

- The distribution system reliability assessment deals with availability and quality of power supply at each customer service entrance. This paper focuses the assessment of power distribution reliability of Addis Ababa city which is connected from Cotebie distribution substation and the possibility of using smart reclosers and disconnectors to mitigate the urgent and pressing power interruption problems. Depending of the assessment result Cotebie distribution substation has reliability indices such as average frequency of interruption is 133.37 interruptions per year per customer and the average interruption duration is 187.31 hours per year per customer. This value shows the substation has greater reliability problems and the substation does not meet the requirements set by the regulatory body that is Ethiopian Electric Authority (EEA). In this paper, the reliability is improved in to 22.27 interruptions per year per customer average frequency of interruption and the average interruption duration is 31.274 hours per year per customer. It can also improve above this value depending of the segment and recloser number. The designed system is simulated using WindMil software that is used to analyze the reliability of the overall system. The simulation of the designed model shows that the application of smart reclosers and disconnector coordination can improve the reliability from 50% up to 83.3%.