Proximity-Aware Calculation of Cable Series Impedance for Systems of Solid and Hollow Conductors

Wideband cable models for the prediction of electromagnetic transients in power systems require an accurate calculation of the cable series impedance as a function of frequency. A surface current approach was recently proposed for systems of round solid conductors, with the inclusion of skin and proximity effects. In this paper, we extend the approach to include tubular conductors, allowing to model realistic cables with tubular sheaths, armors, and pipes. We also include the effect of a lossy ground. A noteworthy feature of the proposed technique is the accurate prediction of proximity effects, which can be of major importance in three-phase, pipe-type, and closely packed single-core cables. The new approach is highly efficient compared to finite elements. In the case of a cross-bonded cable system featuring three-phase conductors and three screens, the proposed technique computes the required 120 frequency samples in only six seconds of CPU time.