Influence of frequency characteristics of soil parameters on ground-return transmission line parameters

• The ground return parameters of transmission lines are highly related to the soil parameters. In this paper, the complex return plane method was used to evaluate the ground return parameters of transmission lines. With the frequency characteristics of soil parameters considered, all parameters of overhead transmission lines are different from those under frequency independent soil parameters. The water content and temperature have strong influences on the parameters of transmission lines, while the influence of soil size distribution is relatively small.

Electromagnetic transient processes are strongly related to the parameters of transmission lines. With the ground return parameters considered, the frequency dependent parameters of transmission lines are highly dependent on the soil parameters, which include resistivity and dielectric permittivity. In this paper, with the measurement results of frequency variation of soil parameters, the influence of the frequency dependent soil parameters on the frequency dependent characteristics of the transmission line parameters were studied using the complex return plane method. According to the calculation results, the frequency characteristics of soil parameters have obvious influences on the parameters of overhead transmission lines. The influences of the humidity, temperature and particle size of the soil on the ground-return parameters were also evaluated.