Analytical Studies of Lightning Over-voltages at Grounding System of Small Wind Turbine

Due to lack of manufacturing and construction facilities, many countries and locations are favorable for small and medium size wind turbine. Transient behavior of a small size wind turbine grounding is studied with the help of Finite Difference Time Domain (FDTD) Method. Generally, steady-state grounding resistance is emphasize for the designing of grounding system, which may be applicable at high resistivity soil, however, at low resistivity soil the transient grounding impedance is higher than the steady-state grounding resistance depending on the stiffness of the injection current which is analyzed and discussed in this paper. The need for electromagnetic analysis for the proper designing of grounding system at low resistivity soil is discussed. Touch voltage and step voltage at a wind farm may cause injury or death of human being or cattle which is also analyzed and discussed. The influence of several parameters such as soil resistivity, stiffness of injection current on lightning transient earth potential rise and step voltages is discussed.