Reliability improvement of power distribution system using protection devices: case study of Bedele power distribution system

Abstract

The majority of outage events experienced by customers are due to electrical distribution failures. Increasing distribution network reliability is a necessity in order to reduce interruption events. Unreliable power distribution reduces user power consumption, affects daily activity and drags modern life style. Basically, Power Distribution Reliability has been a major challenge in Bedele city. It has incurred cost on customers and lowered product quality. In Bedele city and surround, Customers have faced frequent interruption and utility has taken long time to alleviate it. Hence, it has to get amicable solution. Thus, the objective of the study is to assess the reliability of the current distribution system and suggest solutions of reliability improvement. Bedelepower distribution system of south west region, which has high rate of interruption, is selected as case study area. Bedele city and surrounds feeder lines reliability is assessed based on two years datafrom Ethiopian electric power (EEP) of south west region. To limit the scope of the study, Bedele city and Brewery Factory line from Bedele substation is chosen for reliability improvement measures. Bedele cityFeeder has SAIDI of 710 hour per customer per year and SAIFI of 617 Interruption per customer per year. And Bedele Brewery factory has SAIDI of 320 hour per customer per year and SAIFI of 272 Interruption per customer per year. The reliability index values of both feeders are not within the ranges of bench marks of best practices and Ethiopia‟s reliability requirement. Therefore, the appropriate components of Distribution system reliability improvement protection devices are selected. Different power distribution system cases are analyzed by considering feeder segmentation and auto restoration improves distribution reliability. Each cases payback period and reliability performance of distribution system evaluated. The reliability assessment of power distribution system with protection device is simulated using the ETAP software. The simulation of the power distribution models shows that the application of reclosers can improve the reliability of the overall system from 47% to 83%. Finally, best scenario is selected and proposed as a solution to improve Distribution reliability of the two feeders for implementation