Lightning attachment to wind turbine surfaces affected by internal blade conditions

The efficiency of the blade lightning protection system depends to a great extend on the effectiveness of the receptor to intercept the lightning discharge. When the blade is exposed to a high electric field, streamers are mainly initiated from the receptor surface, but lightning attachment on the blade surface instead of the receptor is also possible, with the risk of damages in the composite structure as a consequence. The present paper focuses on electrical fields and streamer activity in connection to conductive components inside a wind turbine blade when a downward leader is approaching the wind turbine. High voltage tests have been carried out to study the development of streamers in conductive components inside a fiberglass structure, and the results have been correlated with the simulations of the electric field performed using Finite Element Method. Finally, potential applications of the results of this study are discussed.