A Study of Voltage Stress On An Offshore Bipolar Vsc-Hvdc Link With Dedicated Metallic Return

This paper investigates transient voltage stresses on a Dedicated Metallic Return (DMR) cable in an offshore ±525 kV bipolar VSC-HVDC system. The submarine DC cable bundle, including both pole and DMR cables, is modeled in detail, providing a full representation of its internal structure. Electromagnetic transient (EMT) simulations are conducted to analyze the impact of neutral bus grounding resistance and proximity effects on DMR cable voltage under DC faults. The performance of the neutral bus surge arrester is also evaluated, along with the influence of key parameters such as MMC arm inductance, transformer reactance, and AC breaker tripping time on arrester energy absorption. The results offer new insights into the transient behavior of DMR cables in bipolar VSC-HVDC links and provide a reference for system design and protection studies.