Modal analysis of three-phase cable systems based on a modified high-frequency model

A modified three-phase cable model, which takes into account the high-frequency characteristics of the cables and the earth, is proposed for high-frequency signal analysis, e.g., the detection and location of partial discharges in cables. Closed-form expressions of the modal propagation constants are derived based on the modal decomposition theory. A global sensitivity analysis of the modal velocities and attenuations is carried out using Sobol's method, which makes it possible to establish the effect of external factors on modal propagation. The results show that the wave propagation characteristics at high frequencies are distinctly different from the case of low frequencies.