Calculation of Positive-Sequence and Zero-Sequence Impedances of Three-Phase Submarine Cables

This code describes semi-analytical calculation methods for the positive-sequence and zero-sequence impedances of 3-phase armored cables with solid sheaths and a single armor layer. Separate equivalent circuits are defined for these two impedances. Subsequently, circuit component values are calculated based on 2D field equations, with some 3D effects modeled. The existing approach for calculating zero-sequence impedance is corrected and expanded by inclusion of additional inductances due to solenoidal fields and magnetic armor effects. 3D finite-element models of cables with magnetic and non magnetic armor are used to assess the accuracy of our circuit models; discrepancies are less than 3% at frequencies between 50 Hz and 5 kHz. Python code with the implementation of the method is provided for accessibility.