Transient grounding characteristic of wind turbines affecting back-flow lightning current into distribution system

Lightning damages to facilities inside or in the vicinity of wind turbines become remarkably common. Most of the breakdowns and malfunctions of the electrical and control systems inside or in the vicinity of wind turbines are caused by ground potential rise due to lightning current flowing into the grounding system of the turbine and back-flow lightning current due to the ground potential rise. To clarify the transient characteristics of the wind turbine grounding systems and to understand the mechanism of the breakdowns and malfunctions, we have carried out a lot of field tests and simulations. In this paper, transient grounding characteristics of a wind turbines foundation are discussed.