Comparison in Lightning Performance between the Poles of the Cahora-Bassa ±533kV HVDC Lines

This paper compares the lightning performance between the positive and negative poles of the 517km South African portion of the 1414km HVDC scheme between “Songo” hydro power station in Mozambique, and “Apollo” converter station north of Johannesburg, South Africa. This scheme is unique in that the positive and negative poles are constructed as two independent lines, separated by several kilometres. The separation between the lines is sufficient to distinguish between strokes to either line with high accuracy, whilst the lines are assumed to experience similar average weather conditions, and thus exposure to lightning. The available fault data for 7 years was analysed in order to compare the relative performance of the two poles in respect of lightning related faults.