Performance comparison of existing AC and DC transmission lines within southern Africa with predictions for lines above 765 KV

Abstract

Transmission line faults caused by lightning, contamination, birds and fires largely determine the performance of AC and DC transmission line within Southern Africa. With the trend towards higher voltages, with specific reference to the Westcor HVDC link, been developed, a comparison of the performance between existing AC and DC lines will give insight not only into how the faults perform relative to each system but also what can be expected for lines exceeding 765 kV. This dissertation compares data for all the 400 kV transmission lines in South Africa and the ±533 kV Cahora-Bassa line, with reference made to the existing 765 kV AC lines in South Africa. Based on this comparison the findings include possible data acquisition inconsistencies, underperforming areas with respect to different fault types and performance predictions for lines exceeding 765 kV.