Wave Propagation Characteristics and Model Uncertainties for HVDC Power Cables

This paper presents a stable and efficient full-wave cable model and a detailed study of the related model uncertainties regarding the wave propagation characteristics of very long HVDC power cables at low frequencies. The model can be used to predict the dispersion characteristics of the cable with respect to its electromagnetic parameters, or as an inverse problem to estimate some parameters of the cable (armor permeability, metal-layer conductivities, temperature, length, etc.) based on measurements. The electromagnetic model is based on a magnetic frill generator that can be calibrated to the current measured at the input of the cable, and a layer-recursive computation of the axial-symmetric fields. Measurements of pulse propagation on an 82-km-long HVDC power cable over a bandwidth of 100 kHz have been used to validate the model. The main conclusion of the study is that the conductivity (and, thus, the temperature) of the conductor and the lead sheath are of utmost importance to achieve an accurate model. At the same time, some parameters are, in principle, insignificant regarding the dispersion characteristics in the low-frequency regime, such as the permittivity and the conductivity of the semiconducting screens. This paper contains an investigation and a discussion on the electromagnetic properties of all layers of a typical HVDC power cable.