Time-Domain Modeling of a Subsea Buried Cable

Traditionally, electromagnetic transient (EMT) programs in time-domain cannot deal with submarine cables buried in the seabed, as available routines demands one medium to be lossless to derive per unit length impedance and admittance matrices. This paper proposes a suitable approach for modelling of HVDC submarine cables, i.e., single-pole, single-core cable with thick armors, in EMT-type programs in order to allow an accurate representation of the seabed buried cables. The expressions for calculation of pul parameters are based on a quasi-transverse electromagnetic (quasi-TEM) approximation of a full-wave formulation. Two distinct approaches are considered for time-domain modeling. The first one is based on the Method of Characteristics (MoC) and relies on the main structure of the so-called universal line model (ULM) harnessing its implementation in the EMT software. The second approach is based on the rational fitting of the cable nodal admittance matrix using the Folded Line Equivalent (FLE). The time responses of both approaches are compared with the one obtained using the Numerical Laplace Transform (NLT) and a very good agreement was found.