Reliability assessment for medium voltage electrical network : a case study within Eskom distribution

Abstract: In recent years electricity supply has played a very crucial part in people’s lives. However, just having access to electricity is not sufficient; the reliability of electricity supply is also important. In Africa the serious effect of an unreliable power supply is a prominent concern within electrical distribution networks. Outages in the Eskom distribution network accounted for the significant majority of the total outage duration experienced by Eskom Distribution customers. Distribution network systems constitute the greatest risk to the interruptions of electrical power supply; as it is still liable for more than 80% of the customer reliability issues, with the majority of the faults (70%) occurring on the Medium Voltage (MV) networks. As a result, this research study will identify, define, and quantify factors that lead to poor reliability of distribution networks, and, from the findings, alternative solutions will be proposed and discussed, based on the findings of the study. This is intended to assist electrical utilities effectively to investigate the affected network, and to be able to apply strategic reliability improvement plans to achieve optimal performance. The research methodology used to obtain and analyse the data during the research study consists of literature review and a qualitative approach. In order to conduct a full study of the research, the strategy used was a case study. The research findings within Eskom’s distribution network found that the reliability performance is poor due to defective equipment failures, overhead power line problems, maintenance or construction related failures, fuse failures, unit equipment problems and cable theft. Defective equipment posed the highest risk - particularly the cable network. Several solutions were proposed to improve the reliability of Eskom’s distribution, including investments information technology systems, smart grid technologies, capital, operational and maintenance strategies and reliability improvement strategies for defective equipment, overhead power line, fuse, unit equipment and cable theft was discussed. By applying these mitigation strategies and focusing on limiting the entire 85% impact presented by failure root causes, the power cut can be reduced from 18.747 hours to 2.75 hours. Meaning an 85% reliability improvement within Taunus’ distribution supply area in Eskom’s distribution.M.Phil. (Engineering Management