It is expected that lines totalling 7500 km in the German transmission network will need to be optimised, strengthened, or newly built over the next few years. HVDC links are playing a key role. One example is SuedLink, a new 2 GW, 700 km line to enable low-loss energy transport over long distances from wind farms in the German North Sea and North, and solar power from the South of Germany, to integrate with the transmission grid.

The contract for the converter technology for the section between the grid interconnection points of Brunsbüttel in Schleswig-Holstein and Leingarten/Großgartach in Baden-Württemberg was signed on 23 August. Siemens Energy will supply the converters and carry out the detailed and site-specific planning of the facilities in the coming months together with the project owners, the transmission grid operators TenneT and TransnetBW, and further project members.

“With the award of the contract, we have taken a decisive step closer to realising SuedLink. Now the planning can be further worked out in concrete terms at two start and end points, and the preparatory construction measures already underway at the southern end point in Leingarten, Baden-Württemberg, can be driven forward,” said Dr Werner Götz, md of TransnetBW

After Ultranet and SuedOstLink, SuedLink is the third high-voltage direct current corridor project in Germany to be implemented with HVDC systems from Siemens Energy. It is one of the largest energy infrastructure projects in Europe. The converters will be designed as self-commutated voltage-sourced converters in a modular multilevel converter (MMC) arrangement with a rated DC voltage of ±525 kV. In addition to active power, the systems can also independently control reactive power. This allows them to respond flexibly to fluctuations in generation and consumption in the grid and enables the low-loss transport of up to 2 GW in both directions.