A mathematical model for estimating the electric potential at the ground surface of
an earthing system of wind turbines using ring electrode is presented. This model
depends on the induced charge resulting from the injected current in the ring
electrode that is buried in the earthing layers and connecting with turbine body. A
three dimension numerical model to analyse wind turbine earthing systems is
proposed. The proposed technique depends on the determination of the electric
field intensity and the distribution of the injected current into the surrounding soil
around an earthing system of wind turbine. The finite element method is used for
this purpose. The proposed technique is applicable to simple and complex earthing
systems with uniform soil.