Optimising the number and position of reclosers on a medium voltage distribution line to minimise damage on equipment

Abstract

The optimal placement of reclosers on overhead lines in a medium voltage distribution network is known to improve the reliability of a power system. Traditionally, recloser placement studies have not considered the effect of greater numbers of reclosers on network damage during faults or the effect of positioning on protection settings. Recloser positions that enhance the reliability of the system may not necessarily improve other problematic operational aspects, such as the damage to equipment and the risk of incorrect tripping due to the sudden increase in loading. This research seeks to prove the hypothesis that: Recloser placement studies with the additional consideration of protection-related factors such as equipment damage and the risk of false tripping will result in different recloser positions compared to when the priority is only on improving reliability indices and cost. A tool is developed to assess the reliability indices, cost, damage and the risk of false tripping and it determines the best recloser positioning based on the priority given to each factor considered. Using this tool, observations are made on the effect of the added factors of damage and the risk of false tripping on recloser positioning. The addition of the protection-related factors to the objective function is unique in its ability to realise the value of recloser positions that cater for minimizing the damage factor and the possibility of tripping on load. In the absence of these factors, the value of certain recloser positions would not be identified as they would not improve reliability or cost factors. The importance of reliability and cost are not overruled by the addition of the protection-related factors. The consideration of protection-related factors in the planning process of optimising recloser placement ensures that the protection of the overhead line is optimal and is not compromised in any way. This would inherently have a positive effect on the lifespan of the equipment on the feeder and the reliability of the feeder in the long-term.