Transient analysis of grounding systems for wind turbines

The paper deals with transient analysis of grounding systems wind turbines. A typical wind turbine grounding system arrangement based on ring electrode is analyzed. Special attention is focused to the influence of additional vertical and horizontal electrodes, respectively. Influence of grounding wire placed in cable trench on the transient behavior is studied in detail. The mathematical formulation in the frequency domain is based on the thin wire antenna theory and the related set of Pocklington integro-differential equations. The corresponding transient response is obtained by means of the Inverse Fourier Transform (IFT). The set of Pocklington integro-differential equations is solved by the Galerkin-Bubnov Indirect Boundary Element Method (GB-IBEM) featuring the use of isoparametric elements. A number of illustrative computational examples are presented in the paper. ► Transient analysis of realistic wind turbine grounding system. ► The influence of additional vertical and horizontal electrodes is analyzed in detail. ► No significant difference where found between additional horizontal and vertical electrodes. ► Interconnection between WT grounding systems doesn't decrease very early transient impedance. ► Very high values of step voltages can be expected in the case of lightning strike.