Probability of Lightning Discharges in Overhead Lines – New approaches

Published in 2015

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Summary

Evaluated lightning amplitudes are mainly used for numerical simulation programs in insulation coordination studies to analyse transient overvoltages caused by direct lightning discharges. For the evaluation of the maximum amplitude of the lightning current, the rolling sphere method can be used. Depending on the evaluated radius of the sphere, the maximum lighting current can be calculated by the use of empirical formulas. With the proposed method a correlation between the amplitude of the lightning currents, the local lightning density and angle-dependency of the ground can be developed to evaluate the lightning probability for a high voltage structure, used for electrical transmission. The evaluated probabilities show on the one side the lightning probability to a given high voltage geometrical structure and on the other side the number of possible lightning strokes to the object. Especially, the implementation of an angel dependent ground is useful for the evaluation of the lightning probability for alpine overhead lines.