Abstract
Electricity distribution reliability is a measure of power availability, which is a function of the
frequency
of interruptions, and the duration of such interruptions. Studies have shown that Medium Voltage
(MV) overhead lines are the most significant contributory factors to power outages which lead to
poor performance of electrical distribution networks. The research investigated the basis for the
poor performance of MV overhead lines in a 22 Kilovolt (KV) radial feeder, in order to develop the
most reliable and cost effective optimization approach for switching device placement which has the
potential of improving the performance of MV overhead line distribution networks. A major
requirement in power distribution is to supply customers with reliable electricity without
interruptions. The research explored and identified causes of electricity supply interruptions,
high values of Mega Voltage Ampere (MVA) losses, and the effect of downtimes in terms of number of
customers impacted by outages. The findings informed the design of a robust switching device
placement algorithm, capable of optimizing the performance of a 22KV overhead line, by reducing the
number of customers impacted by interruptions, and minimizing MVA losses accordingly. Optimal
switching device placement strategy improved restoration time of electricity by isolating only
faulty section of network, and minimizing high costs currently associated with scheduled
maintenance on the MV lines. On the occurrence of momentary supply interruption, the reclosers
automatically restore electric power by their auto-reclose feature. System Average Interruption
Duration Index (SAIDI), System Average Interruption Frequency Index (SAIFI), Customer Base Impact
Index (CBII), and Mega Voltage Ampere Base Impact Index (MVABII) were used to measure the
performance outcomes of the line using customer and MVA data obtained from the feeder. Secondary
data comprising information on monthly SAIDI, SAIFI, customers connected per transformer, and MVA
data were obtained from the engineering plant department. A switching device placement technique
was developed and validated using comparative analysis of the old and new data impact obtained
after a pilot implementation phase. The developed technique improved the network performance by
reducing the number of customers affected, and MVA losses
impacted due to electricity supply interruptions by 30.74 and 25.30 % respectively.