Transient Responses on Transmission Lines Located Above Frequency-Dependent Soil with Variable Water Content

This paper investigates the influence of frequency-dependent soil parameters with variable water content in the transient responses of single-circuit three-phase transmission line (TL) subjected to lightning subsequent return stroke. For this purpose, we use the Nakagawa's approach to compute the ground-return impedance and admittance matrices the frequency-dependent soil modeled by Messier is employed. With the Nakagawa's approach, four water contents of 0.90%, 2.57%, 4.04% and 11.57% are selected with results in low-frequency resistivity of 5000, 1000, 500 and 100 Omega.m. The transient responses for single-circuit three-phase line located above soils of 100, 500, 1000, and 5000 Omega.m considering the frequency-constant soil using the Carson's approach are compare. Results demonstrated that the inclusion of frequency dependence of soil leads to an expressive reduction of approximately 19.52% and 60.16% in the generated voltage peaks (first and third) for this TL located above a high-resistive soil of 5000 Omega.m and lower water content W = 0.90%. This work shows the impact of the frequency-dependent soil that must be taken into account for adequate transient in power systems.