The medium voltage direct current (MVDC) electric networks are emerging in power distribution and collection, following the expansion of the high voltage direct current (HVDC) in power transmission. The benefits of MVDC can be analyzed in terms of energy efficiency, power dispatch, power capacity, power supply range, raw material consumption, CO2 emissions, network resilience and ancillary services to the AC grid. The emergence of MVDC systems relies on the development of electric components including power electronic converters, DC switchgear and DC cables. The requirement for these components depends on the MVDC system architecture, control and protection. Adequate electromagnetic transient simulation models are necessary to establish some of the requirements.
This paper explores how choice of the cable system model may impact the simulated electromagnetic transient response of a MVDC system under fault situations. Simulations are carried out in Matlab/Simulink environment, allowing for a detailed AC-DC converter model, necessary for accurate transient analysis. A state-of-the-art review of the existing and relevant cable models is presented. Three models are chosen to be implemented: the PI model, the constant parameters (CP) and the universal line model (ULM) also known as the wide band (WB) model. The WB model is the most general and considers the full frequency dependency of line parameters and work directly in the phase domain. The simulation results present the transient overvoltage and current responses including the cable screen current. Illustrative results are provided to show the importance of transmission line model choice.
Amjad Mouhaidali, Silvain Marache, Leo Dalmar, Piotr Dworakowski, Martin Henriksen
Presented at Jicable’23