Electromagnetic analysis of lightning surge response of interconnected wind turbine grounding system

IEC TR61400-24 [1] suggests interconnection of the grounding system of wind turbines to achieve low steady-state resistance, however, the transient behavior during a lightning strike to the interconnected wind turbine grounding system remains to be discussed. This paper investigates the influence of interconnection on the lightning surge response of wind turbine grounding system. Two different numerical methods, Numerical Electromagnetics Code (NEC-4) based on Method of Moments (MoM), and Virtual Surge Test Lab (VSTL) based on Finite Difference Time Domain (FDTD) method are used for electromagnetic analysis of lightning surge response of wind turbine grounding system. Comparison of results using NEC-4 and VSTL are made to clarify the usefulness of these methods for transient analysis of a large grounding system. The influences of resistivity of soil and front time of lightning impulse current, on the response of interconnected wind turbine grounding system are analyzed.