Impact of the DC cable models on the SVD analysis of a Multi-Terminal HVDC system

High Voltage Direct Current (HVDC) grids are complex Multi-Inputs Multi-Outputs (MIMO) systems whose dynamics are difficult to assess. This paper first describes the modelling of VSC-based Multi-Terminal HVDC systems (MTDC) using different existing cable models. It then recalls the benefits of the Singular Value Decomposition (SVD) approach for the frequency analysis of such systems, and describes how to perform an SVD analysis on a Multi-Terminal HVDC (MTDC) system from its state-space representation. The paper discusses the results of the SVD analysis with regards to the selection of the voltage-droop parameter and the DC voltage constraint of the DC grid. It then emphasises the impact of the choice of the DC cable model on the results of the SVD study and illustrates the cable model influence on the MTDC system through an Electro-Magnetic Transient (EMT) simulation.