A study of lightning protection for wind turbine blade by using creeping discharge characteristics

A great number of onshore wind power plants are constructed and planned. And many large-scale offshore wind power plants are constructed and planned for the past some years. Almost large wind turbine blades have the receptor on the blade for the lightning protection, and down conductors are connected to receptor inside the blade. However, the wind turbine blades have been damaged by lightning. So, it is need to develop new lightning protection method for the blade with receptor. The authors thought that it is possible to lead the lightning discharge to the receptor smoothly on the blade by using the backside electrode. In addition, the authors also thought that it is easy to discharge on the blade when the surrounding seawater was sprayed on the blades of offshore wind turbine. The paper shows two experimental results. The lightning impulse discharge on the test model blade was found to lead to the receptor smoothly by using the backside electrode. However, other problem was emerged. The flashover voltage was decreased on a blade peace and glass fiber reinforced plastics (GFRP) board piece when the surfaces of the test pieces were sprayed with salty moisture.