抄録
This paper describes a study of grounding system of wind turbine generators in a windfarm. A horizontal grounding conductor is often used to obtain a low steady-state grounding resistance. The grounding resistance of the grounding conductor shows transient characteristics. Effective length of the grounding conductor is an important parameter to estimate peak value of lightning overvoltages on the grounding system. This paper proposes approximate formulas to investigate an influence of such parameters as soil resistivity and boundary condition of the grounding system on the effective length.