Control of an Offshore Bipole with AC Interlink Under Dedicated Metallic Return Fault to Improve Energy Availability

The power system in northern Europe supports a high degree of penetration of wind energy-based HVDC connections. Most of the modern HVDC connections will have Bipole with a dedicated metallic return (DMR) configuration. This paper presents a basic guideline to decrease the levelized cost of energy of Bipole HVDC links by attaching the offshore poles to the point of common coupling and by designing suitable control strategies. The simulations are performed in the PSCAD software. These simulation models are designed to observe large AC/DC transients and the control scheme dynamics. The results show that the studied control strategies can be applied under various real-life scenarios where the system dynamics, e.g. over-voltages, are found within the acceptable application range.