Skin and proximity effects in the series-impedance of three-phase underground cables

• Series-impedance is evaluated for underground power cables.
• Skin and proximity effects are taken into account for cylindrical conductors.
• The conductor arrangement is completely arbitrary.
• Earth contribution to the series-impedance is taken into account.
• Results are compared with other numerical calculations.

This paper is a contribution to the series-impedance computation of three-phase underground cables. The proximity and skin effects are considered in order to evaluate their influence on the resistance and inductance per unit length matrix elements.The developed analytical methodology is based on the magnetic vector potential formulation where appropriate boundary conditions allow the magnetic field solution to be obtained.Two cases are considered concerning the cable conductive sheath. First, an algorithm to calculate the series-impedance matrix of the perfect sheath case is implemented which is then used for the second case to calculate the series-impedance matrix of underground cables with an imperfect sheath.Numerical results show that both skin and proximity effects lead to an increase in the resistance values and a decrease in the inductance ones.