Analyzing the impact of other independent distribution networks on Umeme system reliability

Abstract

This paper presents an analysis that helps to determine how other independent distribution networks affect Umeme system reliability as well as measures to improve the reliability while at the same time minimizing the total system costs. This analysis is done in DIgSILENT software. The reliability assessment analysis runs a search on the entire feeder topology, looking at failure rate and number of customers at every loading point and gives results of SAIDI (System Average Interruption Duration Index), ENS (Energy Not Served) and SAIFI (System Average Interruption Frequency Index)

The feeder under study is Lira-Masindi (LRA-MSD/33/1) which is part of Umeme limited, the largest electricity distributor in Uganda. It was chosen as case study feeder because of its history of poor performance, in terms of having very long outage hours.

Data of Geographical Information System (GIS) of the selected feeder is used to determine distance of the distribution feeder sections (Umeme network and UEDCL T-offs), as well as the locations of the load points and number of customers at each load point. A single line diagram is modelled in DIgSILENT software and the base case (with UEDCL T-offs) of the feeder is simulated and the SAIDI, SAIFI and ENS of the network are computed.

The results are analysed and the proposed solutions are implemented in the model and new results of SAIDI, SAIFI and ENS are obtained. These new results are compared to the results of the base case. The values of SAIDI, SAIFI and ENS are observed to reduce which indicates an improvement in reliability.

The cost benefit analysis is carried out to choose the more financially feasible solution in order to improve the Umeme system reliability.