Failure rate modeling due to aging and its impact on distribution network reliability: case study: Umeme Distribution Network

Abstract

This project presents a mathematical model that helps to determine the failure rate due to aging of a power distribution feeder and the impact of those failures on the distribution network reliability. Electrical distribution network is composed of feeders formed from many components that become aged with time. Individual component failure rate mathematical models were built considering component failure due to their time of service in the outage data received from UMEME limited. Components considered were distribution conductors, distribution poles and line insulators. Individual component failure rate was there after added to give the entire feeder failure rate. Five UMEME feeders A, B, C, D, and E were studied. Feeders A and B (base case) were relatively new aged 1- 2 years and were in their useful period of operation experiencing minimal numbers of outages. Feeders C, D, and E were old feeders that had been in service since 1970s, with poor performance history and experiencing more numbers of outages on the UMEME network. Data for selected feeders was collected from UMEME limited and there after used to determine the failure rate per year of the entire feeders A, B, C, D, and E. The failure rates per year and annual down times for each feeder were used to run single line simulations in Dig SILENT software 5.0. Reliability indices from the simulation and their respective failure rates per year for each feeder were compared. It was observed that feeders C, D, and E had continuous increase in failure rate and could always be out of service due to their high values of SAIFI, SAIDI, CAIDI, and low values of ASAI. This gave the impact of failure rate due to aging on distribution network reliability.