Vulnerability Assessment of Components in a Typical Rural Nigerian Power Distribution System

Abstract

The major aim of any power system is the continuous provision of safe, quality and reliable electric power to the customers. One of the greatest challenges to meeting up with this goal is the failure of components in the system. In this article, the frequency of outages caused by failure of different components in the distribution system was investigated to ascertain the ones that are more susceptible to failure by comparing their proportions in the entire failure events. The outage data obtained from Irrua Transmission Station comprising Ehor, Ubiaja and Uzebba 33kV feeders were analyzed using Microsoft Excel while the hazard rates were measured using the failure rate index. Findings revealed that 93.77% of all the forced outages in the distribution subsystem in the power sector are caused by the high exposure rate of the bare aluminum conductors used in the construction of the various overhead feeders. Subsequently, the yearly failure rates of aluminum conductors, cross arms, relay, insulators, fuses, electric poles, breakers, transformers, isolators, cables lightning surge arresters were found to be 836.0, 17.5, 17.0, 10.3, 4.3, 2.0, 1.5, 1.3, 1.0, 0.5 and 0.3 respectively in the studied network. A comparison between this study and a related work showed that the rural feeders are more prone to faults as compared to the ones in the urban areas. It was therefore recommended that regular tree trimming along the network corridor should be done. Proper conductor size should be used in every subsequent construction and every segment with undersized conductor should be replaced with the appropriate size. This study will help the power system engineers in the design, construction, maintenance and operation of the distribution power system for optimum and improved system performance.