New Approach for Lightning Protection of Substations

Lightning protection of substations is a crucial element of the overall insulation coordination approach used in power systems. IEEE Std. 998 (2012) is the world's leading standard for providing guidance to engineers designing lightning protection for substations. It includes various methods for achieving protection corresponding to the equipment BIL. In this paper, the principles behind one of these methods, the "leader inception theory", are presented. A description is provided of how the method is implemented with a computer program via an example of a real substation. Effective interception of lightning relies not only on the method but also the hardware used. Hence, the paper also discusses the importance of corona minimization from air terminals during the period preceding the descent of the downward leader. The methodology and results of a new series of corona performance testing carried out on a variety of air terminals in a high-voltage laboratory are presented and discussed.