Lightning Surge Analysis in a Multi-Conductor System for Substation Insulation Design

Analysis of back flashover lightning surges coming into a substation is important to understanding of substation insulation co-ordination. These surges are usually analyzed for a single conductor system, but in this paper, they were analyzed with EMTP for a multi-conductor UHV system consisting of two ground wires and six phase conductors. It was clarified that lightning surge voltages on the phase conductor decreased due to negative reflection of the lightning surge at a tower, and the electrical coupling between the ground wire and phase conductor. The multi-conductor system was applied to surge analysis for the line entrance circuit of a gas insulated substation.