Lightning interaction with power substations

This chapter presents the influence of lightning on the insulation performance of substation equipment. First, in Section 2.1, the lightning surge analysis including reliability evaluation is positioned in the insulation coordination procedure. As an introductory section of the following ones, the lightning surge analyses are classified in terms of treatment of statistics and calculation tools. Next, in Section 2.2, as a representative example of a simplified statistical approach, the International Electrotechnical Commission (IEC) method is introduced, which calculates simply a lightning surge overvoltage in shielding failure and in back fl ashovers based on the limit distance, the distance between a surge arrester and protected equipment, the number of connected overhead lines and damping by corona effects. Then, Section 2.3 refers to a detailed lightning surge analysis, taking the ultra -high -voltage (UHV) case carried out by Tokyo Electric Power Company, Inc., Japan, as a decisive approach. Lightning surge analyses for back fl ashover are dealt with especially from the viewpoint of insulation design of electric power facilities considering the special conditions peculiar to the UHV class. Finally, Section 2.4 evaluates the failure rates of gas insulated switchgear and transformers with changing parameter values of the lightning current crest value and the front time. Together with the probability distribution of the lightning current, failure rates caused by back fl ashover are comprehensively evaluated.