Lightning detection and lightning protection of power systems in Japan

Lightning occurrence data have been collected with the lightning location systems operated by electric power companies in Japan. Seasonal variations and annual variations of lightning occurrence have been clarified from the seasonal and annual lightning stroke frequency maps made by the above data. These data were compared with the faults on transmission lines. The number of faults is almost proportional to the lightning stroke frequency. Related to lightning protection for electric power systems, over 30 years winter lightning on the Japan Sea Coast has been investigated and novel findings have been acquired by the extensive research. Active research has been carried out for the establishment of the protection design of the electric power system against winter lightning. Also, the results concerning the lightning phenomena around power distribution lines using still cameras are shown.