An experimental field study of the grounding system response of tall wind turbines to impulse surges

In this work, an experimental investigation of the grounding system behavior of tall wind turbines in both time and frequency domains is presented. Two scenarios were considered: in the first one, measurements were carried out on the grounding system embedded in the wind turbine foundation, before assembly of the wind turbine itself; in the second one, the complete wind turbine (tower, nacelle and blades) was included. The study also presents an enhanced signal processing technique for noise cancelation in a harsh electromagnetic environment. In the analysis, the frequency dependence of the grounding impedance was evaluated and a numerical simulation in steady state was performed. The simulation model leads to a satisfactory representation of the studied system. Preliminary results show that the evaluated grounding impedance is not significantly affected by the presence of the complete wind turbine at the evaluated frequencies.