Transient Plane Wave Coupling to Overhead Line above a Multi-Layer Soil

摘要

Considering the displacement current in the multi-layer soil, the formulas of the ground return impedance and the Fresnel reflection coefficients are derived in frequency domain. These expressions are valid for discretional soil conductivities and the whole range of frequencies. For the convenience of transient analysis, the vector fitting method is adopted to expand the time-domain forms of the ground return impedance and the Fresnel reflection coefficients into the sum of finite exponential functions which are easy to be treated. Based on the recursive algorithm for the time-domain convolution, the finite difference time-domain (FDTD) method improved by the authors is used for the transient analysis of the external excited overhead line. Compared with the existing method applicable for homogeneous soil, the proposed method is demonstrated to be correct.