Modal propagation characteristics and transient analysis of multiconductor cable systems buried in lossy dispersive soils

Abstract In surge analysis, an important issue is the influence of the imperfect earth on the propagation characteristics of the conductors. In this paper, the wave propagation characteristics and the transient performance of underground multiconductor cable systems in flat, vertical and trefoil arrangement are investigated. The Longmire and Smith frequency-dependent (FD) soil model as well as a generalized earth formulation are considered, taking into account in the analysis the impact of earth conduction effects on both the series impedance and shunt admittance of the cable conductors and sheaths. Comparisons are carried out with approximate earth formulations, neglecting the influence of imperfect earth on shunt admittances. Finally, resonance frequency analysis and transient simulations are performed for the different cable arrangements to evaluate the importance of FD soil modeling and earth formulation per cable arrangement.