Estimation of the failure rate of wind turbine electrical systems exposed to lightning strikes

This paper proposes a method for estimate the percentage annual failure rate of wind turbine electrical components due to the exposure to lightning flashes. It is well known that modern wind turbines are exposed to lightning strikes due to their locations and tall structures (in excess of 100 m high). However, the methodology for estimating the failure rate of the electrical components is not well established. The proposed method uses the attractive radii models to determine the lightning incidence on wind turbines. This method was compared with the technique proposed by the IEC 61400-24:2010, which is based on the collection area concept. The proposed method predicts lower failure rates than IEC 61400-24:2010 procedure. The proposed method considers the wind turbines effective height, the keraunic level of their locations, the dependence of lightning current amplitude and the influence of both upward and downward lightning flashes. The results show that the effective height of the wind turbines and keraunic level of their location influence the failure rates significantly.