Measurements of transient grounding impedance of a wind turbine at the Mont-Crosin wind park

In this paper, we report the results of wind turbine grounding system impedance measurements performed at the Mont-Crosin wind park in Switzerland. Experiments were carried out twice: (1) when only the construction of the wind turbine foundation had been completed, and (2) once the installation of the rest of the wind turbine was finished: tower, nacelle and blades. The transient grounding impedance was evaluated directly in the time domain by solving Duhamel's integral equation. The influence of the presence of the wind turbine is found to be negligible on the grounding impedance at low frequencies. However, at frequencies beyond 150 kHz or so, the measurement of the grounding impedance is significantly affected by the presence of the wind turbine.