Utilization of Line Surge Arrestors to Improve Overhead HV AC Line Performance under Lightning Conditions

In geographical terrains with high occurrence of lightning, lightning strokes influences the performance of overhead HV AC lines negatively. A single stroke can lead to back flashovers and the resultant surge on the conductor results in the protective devices operating to extinguish that power surge. This operation of the protective devices leads to consumer interruptions on that network, thus leading to a loss of production and negatively impacting the economy. Line Surge Arrestors are devices that can drain the power surge to ground, if placed adequately and in sufficient numbers. This paper determines the relationship between the magnitude of the lightning stroke, the tower top voltage and hence the back-flashover voltage that would appear on the line, which would lead to power interruptions. Surge arrestors were modelled, using the MATLAB software, and the required number of surge arrestors per phase is thus determined that is required to drain the surge current down to earth and prevent power interruptions.