Safety of wind farm grounding systems under fault and lightning currents

This article discusses the safety issues related to wind farm grounding systems. Two different cases are considered. The first case treats a wind turbine subjected to a single phase to ground fault while the second case treats a wind turbine hit by lightning. In the first case, a detailed analysis of the fault current distribution for various scenarios, is presented. A comparative study of the touch and step voltages has demonstrated that the fault conditions on HV side leads to dangerous touch and step voltages. A focus is made on the human safety regarding lightning surges. In this regard, the transient currents flowing through the legs and body are computed for two different lightning waveforms. A comparative study of these currents for the cases of a single and two turbines reveals the non-validity of one of the design criterion established in international standards.