Cauer Ladder Network Representation of the Earth Return Impedance of Submarine HVDC Cables Based on FEM

Starting from a 2D finite element formulation for the computation of eddy currents in and around a submarine HVDC cable, we describe a procedure for extracting the sea and seabed return impedance parameters to be used in a network description of the system. A model order reduction approach, known as the Cauer Ladder Network method, is applied to extract a network representation of the earth return impedance of an HVDC submarine cable in a realistic scenario. In this work, the proposed method is described in detail, and the obtained numerical results are compared with well-known analytical formulas, showing how the extracted equivalent circuit approximates the reference results within acceptable tolerance.