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

Wide-band cable models for the prediction of electromagnetic tran-sients in power systems require the accurate calculation of the cable series impedance as function of frequency. A surface current approach was re-cently proposed for systems of round solid conductors, with inclusion of skin and proximity effects. In this paper we extend the approach to in-clude 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 pro-posed technique computes the required 120 frequency samples in only six seconds of CPU time.