Methodology and implementation of leader inception theory for lightning protection of substations

Traditional methods for shielding substations against direct lightning strokes were first published in IEEE Std. 998 in 1996. Several new methods were added to the ensuing 2012 edition. This paper provides an exposition of the key principles and practical implementation of one of those methods, viz. the “leader inception theory”. A novel software implementation of the method is described and the output is illustrated with a case study. Since the efficient interception of lightning involves not only the method used to position protective air terminals but also the characteristics of the air terminals themselves, the paper addresses the importance of space charge and the necessity for minimizing corona discharges during the pre-stroke phase of a thunderstorm. The results of corona discharge measurements made on sharp and blunt air terminals at a state-of-the-art HV facility are presented and discussed.