Effectiveness investigation of wind farm earthing system

Wind turbines are tall structures with heights that can exceed 80m. Their installation is usually done at high altitude and isolated areas causing these vulnerable to lightning strikes considering their total hub height and blade radius. The sites that wind farms are installed are usually of high lightning activity. Furthermore, in these areas the soil resistivity is high, leading to the design and construction of a reliable earthing system that shall ensure both lightning and earth fault current dissipation. Step and touch voltages shall be compatible with the safety limits as these are defined in IEEE80-2000. The earthing system is the main part of the wind turbine lightning protection system apart from the receptors and down conductors. It leads the lightning and the earth fault currents to the earth in a safe way both for the infrastructure and for the human beings. The earthing system of a wind turbine and thus the wind farm shall be designed on project specific conditions, considering the ground conditions, short-circuit analysis of the power plant collector system, international standards and also national requirements of the country that it shall operate if such exist. In the current paper will be discussed the effectiveness of a wind farm earthing system regarding the current dissipation. The evaluation will be executed based on project specific soil conditions which have been measured during a dry season and foundation earthing system of each wind turbine. The transient analysis will be performed via simulations in EMTP-ATP. The extracted results will be useful for other wind farms that are installed in similar soil and/or electrical conditions in order to reduce the project execution time by using a proven earthing solution.