Proposal of lightning damage classification to wind turbine blades

Lightning damage to wind turbine blades is of great concern to wind power installations. We investigated various issues arising from lightning damage and assessed causes through actual lightning observations, and high-voltage and large-current experiments. Although installing lightning receptors and down conductors provides a good countermeasure, blade damage caused by lightning still occurs. Additional countermeasures may be necessary to protect blades from lightning; these countermeasures may include not only better performance and layout of receptors, but also independent lightning towers and new types of blade materials. This report provides a classification of blade damage sustained in winter lightning, ranked in severity by analysing the many incidents of damage that have actually occurred in Japan. Moreover, a list of possible causes of damage and relative countermeasures are also presented.