Lightning performance of wind turbine grounding systems considering typical brazilian soil conditions

This paper assess the lightning response of grounding systems of wind turbines, considering typical Brazilian soil conditions. In particular, the impact of the frequency dependence of soil electrical parameters on the lightning response of a typical grounding arrangement of wind turbine systems is assessed. It was found that the frequency dependence of soil parameters is responsible for decreasing the grounding potential rise developed by the grounding system and, thus, its impulse impedance This effect is more pronounced with increasing soil resistivity and for typical currents of subsequent strokes. It is also shown that, for wind turbine grounding arrangements of typical dimensions, their impulse impedance is expected to be lower than the low-frequency grounding resistance, considering lightning currents representative of first and subsequent strokes.