Parametric Study of Transient Electromagnetic Fields Due to Overhead Transmission Lines and Buried Cables in the Vicinity of Lossy Ground

In this paper, the problem of calculating transient electromagnetic fields due to frequency-dependent multiconductor overhead transmission lines above lossy ground and underground cables buried in lossy soil is studied by decomposing the transmission line into a number of small segments. A modified finite-difference time-domain technique is applied to find the current passing through each segment of the excited transmission line. The contribution of each segment on the total electric and magnetic fields is calculated using two frequency-domain analytical techniques. The theoretical background and extent of validity of each technique are presented, and the results derived by applying each method are compared with those obtained using a commercial software package. The time-domain solution is then obtained using Fourier and Inverse Fourier transforms. Finally, the effects of different electrical and geometrical parameters, such as conductivity and relative permittivity of the ground and conductor sag of the transmission line, are studied.