Modelling aspects on cables in the frequency domain

As renewable energy sources increasingly integrate into the grid, ensuring compliance with power quality standards, particularly regarding harmonic distortion, becomes critical for both users and system operators. This study examines the impact of underground cable modelling on the prediction of harmonic distortion at the point of connection during harmonic assessments. Lumped, distributed, and cascade models were evaluated in both single-phase and three-phase cable configurations, with an emphasis on their influence on resonances observed in harmonic impedance. Cable length was considered as a parameter to quantify the impact of these models. Simulations conducted using DigSILENT PowerFactory® reveal that the distributed parameter model best predicts the first resonance as cable length increases. For cables longer than 6 km, significant discrepancies in harmonic impedance behaviour are observed between models. Moreover, models that include detailed cable construction features demonstrate increased damping of resonances. While model validation is outside the scope of this work, the findings underscore the importance of selecting the appropriate cable model for accurate harmonic analysis in power systems.