A new HVDC-DC converter with inherent fault clearing capability

For the upcoming need to transfer bulk power over long onshore distances, HVDC power transmission is the preferred choice. However, components like HVDC-DC converters and a protection concept for DC line faults present challenges, that still have to be solved. As up today, the sections of a segmented DC transmission corridor would still be linked via an AC connection, leading to high transformation losses, and high investment costs. With the newly presented HVDC-DC auto transformer it is possible to directly link two DC lines with different voltage levels. In this paper the ability of this HVDC-DC converter to interrupt DC faults is investigated and compared to the state of the art topology of linking two DC lines via an AC connection.