Technical loss reduction on the MV distribution network through load switching

Abstract

This project presents load switching as a way of further reducing technical losses on the MV distribution network. These losses are majorly due to heat dissipation as 𝐼 2𝑅 in the network equipment such as conductors and transformers. The project undertook the Lugogo substation 11KV feeders that are interlinked but operated radially as a case study. Data collected from UMEME using ArcGIS as a major tool was used to model the case study in DIgSILENT PowerFactory. These modelled feeders have different loading, line length and conductor sizes. Therefore, by transferring loads from a longer feeder to a shorter one or from a heavily loaded feeder to a lightly loaded feeder or from a feeder with a conductor of smaller cross-sectional to one with a larger cross-sectional area, technical losses were reduced. This was achieved by using a tie open point optimization that closes a tie switch between the interlinked feeders which is followed by opening a sectionalizing switch along the relief feeder that leads to minimal losses in the network using the existing switching devices. Technical losses were further reduced by performing a tie open point optimization after placing switches at appropriate positions. Load switching enabled loss reduction by 13.57% using already existing switches while a further loss reduction of 24.76% was achieved with switches placed at appropriate positions. This meant an annual energy saving of 1.96 GWh and improvement of voltage profiles from 0.9 p.u to 0.94 p.u. This means that load switching is not only technically viable but also economically viable since its payback period is less than a year.