The two transmission system operators, 50Hertz and TenneT, have commissioned Siemens Energy to build two converter systems for the second line of the SuedOstLink and its northern extension, SuedOstLink+. A converter will be built at the starting point in the Klein Rogahn search area west of Schwerin. The second converter is being built at the Isar substation location near Landshut.

Two converter systems are already being prepared for the SuedOstLink at the Isar site and are under construction to the north at the Wolmirstedt substation site near Magdeburg. This project is listed as Project 5 in the Federal Requirements Plan. The two contracts that have now been awarded relate to project 5a, which runs along the same route south of Magdeburg. A separate route north of Magdeburg is required – the so-called SuedOstLink+. Since the two lines form a technical unit, the two network operators commissioned Siemens Energy to build them. This allows synergies in the construction and operation of both SuedOstLink – projects are raised. Siemens Energy will hand over the converters now commissioned to 50Hertz and TenneT on a turnkey basis in 2030.

“Wind energy from the north is urgently needed for the continued secure and sustainable energy supply in Bavaria. Therefore, by awarding the converter pair for Project 5a, we have taken another important step towards long-term security of supply in the south,” says Tim Meyerjürgens, COO of TenneT. “With Siemens Energy, we have a long-standing and experienced partner at our side. This is important because only together as a team will we be able to increase the pace of network expansion and overcome this historic challenge,” adds Meyerjürgens.

50Hertz CEO Stefan Kapferer says: “The transport of renewable electricity over long distances is the basic requirement for achieving climate neutrality in Germany. The SuedOstLink and its northern extension are a high priority for 50Hertz and serve, among other things, to bring electricity from the Baltic and North Seas to Bavaria. We are happy to have gained Siemens Energy as a supplier. But one thing is also clear: Given the need for further network expansion on land and at sea, the procurement of important materials and components for network expansion on a narrow global market is becoming increasingly challenging.”

Tim Holt, member of the board at Siemens Energy: “Just a few years ago, only one or two converter projects per year in Europe were awarded to one of the three major providers. This year, Siemens Energy has already won six projects in Germany alone. By commissioning via both SuedOstLink systems, we can use synergies in terms of design, processes and experience. It is a good example of how we can process projects more efficiently together with customers. Nevertheless, we still need the right regulatory framework so that companies along the value chain can increase their capacities sustainably.”

The high-voltage direct current (HVDC) transmission lines SuedOstLink and SuedOstLink+ will transport electricity from the north of Germany over a length of more than 750 kilometres to the south to the Isar grid junction near Landshut. For SuedOstLink, two lines with a total capacity of 4 gigawatts (GW) will be laid in a route between Wolmirstedt and Isar. The so-called SuedOstLink+ begins further north in the Klein Rogahn search area in Mecklenburg-Western Pomerania and runs parallel to its sister project from Wolmirstedt. 50Hertz is responsible for the construction and operation of the lines in Mecklenburg-Western Pomerania, Saxony-Anhalt, Thuringia and Saxony up to the Bavarian border; TenneT is responsible in Bavaria.

Converters are needed to convert alternating current into direct current and vice versa. In the north, they absorb alternating current and convert it into direct current for low-loss electricity transport over long distances. In the south, the conversion takes place back to alternating current. The new systems awarded to Siemens Energy will be almost identical to the two converters already under construction. Synergies can be used in both construction and operation. The investment costs for the newly awarded converter pair amount to several hundred million euros. Overall, the costs for SuedOstLink and SuedOstLink+ are around 11 billion euros.

Image source: Courtesy of TenneT

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