Evaluation of the Direct-Stroke Shielding Performance of Substations Through Stochastic Modeling of Lightning Attachment

This article introduces a methodology for assessing the direct-stroke shielding performance of high-voltage substations. The proposed methodology considers both negative and positive lightning polarity and can be employed by any lightning attachment model that follows a probabilistic approach. A stochastic lightning attachment model is used, which considers the lightning discharges probabilistic progression. Stochastic model results on lightning discharge propagation, lightning attachment, and induced electric fields are in satisfactory agreement with field observations; comparisons are also made and discussed with respect to other well-established lightning attachment models. An application of the proposed methodology is performed to estimate the lightning incidence rate and shielding failure flashover rate of a 69 kV substation; the effect of lightning activity at the substation location is elucidated.