Most of the literatures dealing with time domain simulation of grounding system response to lightning surges use an electrostatic approach. In this approach frequency dependence of soil electrical parameters and plane-wave propagation constant are not included. In this paper, based on Hybrid Electromagnetic Method and simplification of it, a new method is developed to include frequency dependent parameters of soil in time domain simulation. Since only one convolution is used, the simulation time is significantly reduced. The consistency of the developed formulation while the plane-wave propagation constant is ignored is investigated through comparisons with experimental results and precise frequency domain approaches. Simulations results show ignoring both effects simultaneously can lead to high levels of error (140%), whereas the error significantly reduces when frequency dependence of soil parameters is considered. The developed model exhibits errors of about 2% to 25% compared to the results of models that
