Lightning Ground Flash Density and Evaluation of Lightning Risk for Wind Turbines in Coastal Areas of the Sea of Japan

Winter lightning has seriously damaged wind turbines in the coastal areas of the Sea of Japan. We evaluate lightning risk of them using lightning ground flash density obtained from JLDN, the largest LLS in Japan, conforming the IEC62858. As a result, wefound out that there was no correlation between the number of lightning strokes hit to the wind turbines for all seasons and annual lighting ground flash densities of the surrounding areas. However, the distribution of number of lightning strokes hit to the wind turbines was similar to lightning ground flash densities in winter. Therefore, we proposed thatlightning risk for the wind turbines should be evaluated using lightning ground flash density in winter rather than annual one in the coastal areas of the Sea of Japan.