| Abstract |
The structural change in energy generation and distribution, especially with renewable power sources and their volatile and demand independent generation behavior in areas with low load or at the periphery of the AC grid brings various challenges. Amongst others the need to transport high amounts of power over long distances between generation and load centers brings an AC grid to its limits. Therefore High Voltage Direct Current (HVDC) power transmission is the preferable choice for that task, since compared to High Voltage AC transmission, there are no stability issues and the transmission losses are much lower. However, components like HVDC-DC converters and a protection concept for DC line faults present challenges, which 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 [1–5]* it is possible to directly link two DC lines with different voltage levels. In this paper it is shown, that this topology is also able to securely prevent high DC fault currents and to isolate a faulty DC line at the interconnection point of different HVDC voltage levels. This ability and the resulting topological
efforts are compared to the state of the art topology of linking two DC lines with different voltage levels via an AC connection. |
