Reliability Assessment and Enhancement of Electric Power Distribution: (A Case Study of Ashebeka Distribution System)

Abstract

Electric power distribution reliability is an essential issue that could help to generate key ideas in solving problems related to interruptions, longer time the interruptions last and unavailability of power in a system to benefit electric utilities and electrical consumers at all levels of usage. Because of different power failure factors in electric power distribution system, power interrupts frequently and outage of it takes longer time to be restored the service to its normal state. In power distribution system, which lacks fault detection, isolation and service restoration technology, even the temporary faults became permanent and increase equipment replacement and maintenance costs causing crisis in economy, safety and life of utilizers and also deducts revenue & quality of service delivery of utilities. In Ashebeka distribution system (the case study area), the frequency of interruptions and duration of power outage are too far below the requirements set by EEA and IEEE guides in reliability performance point of view, as SAIFI is 338.4121 interruptions per customer per year and SAIDI is 328.5535 hours per customer per year for the existing system. Hence, the consequence of these power failure difficulties upset utilities & consumers’ daily activities predominantly in continuous production process areas like water treatment plant of drinking water supply, resulting severe interruptions of water in Assela town. Interruptions of water due to these distribution power problems intern causes reduction in revenue on the water supply utility and at the same time decreases the quality of serving the society (customers) due to scarcity of water. These unreliable and extreme power interruptions complications also disturbing power customers of private industrial sectors & mostly troubling economy of electric power utilities. This thesis has conducted assessment & investigations on reliability performance of the proposed distribution system, by identifying the main causes of interruptions and power outage. Different study case scenarios were applied using ETAP 16.0.0 simulation tool to solve the existing problems and as a result of these solution options, the reliability performance of the system has been improved & hence, SAIFI was reduced by 83.63%, SAIDI was reduced by 74.33%, and EENS was also minimized by 76.2% as compared with that of the existing system. The improved system has saved revenue of 884,173.01 ETB per year for Ethiopian electric utility & 542,464.14 ETB per year for a single customer (Assela town water supply).