Due to the status of the energy transition, there is a growing demand to effectively transport electricity from the North of Germany, to the South. Due to North Germany’s windier climate, increasingly larger volumes of wind power are being generated, whereas in the South, energy power plants are slowly dying out. A specifically adapted power line using high voltage direct current (HVDC) transmission technology will be used to transport this electricity.
The SuedOstLink is a DC connection that is planned between Saxony-Anhalt and Bavaria. It will connect Wolmirstedt near Magdeburg with the Isar power plant site near Landshut. The project developer who will oversee the operation in the North is 50Hertz. Transmission system operator TenneT is responsible for the southern part, in Bavaria. Stipulations in the Federal Requirements Plan Act (Bundesbedarfsplangesetz) of 31 December 2015 insist on the general use of underground cables for this project; overhead line sections are only possible in exceptional circumstances.
The SuedOstLink has been categorised by the European Union as a project of common interest (PCI). The project is therefore responsible for the ongoing security of energy supply, as well as the evolution and advancement of renewable energy at a European level. The European Union co-finances the project in the scope of its Connecting Europe Facility. More information can be found here: Projects of Common Interest at 50Hertz.
The SuedOstLink aims to transport large volumes of electricity from wind power state Saxony-Anhalt to the south of Germany over a distance of around 540 kilometres. The planned line capacity of 2,000 megawatts corresponds with the capacity of around 700 wind turbines running at full power. Underground cables with plastic insulation will be implemented that are specifically designed to withstand a voltage of 525 kilovolts.
The new line will be established as a high voltage direct current (HVDC) transmission line. This technology is much more tailored to the job at hand compared to the conventional meshed alternating current grid to transmit large electricity volumes across large distances with few losses, optimal control and in a target-oriented manner.
In order to change the alternating current into direct current for further transmission, converters are needed at the grid connection points. 50Hertz aims to construct the converter at the Wolmirstedt substation. This converter will entail a so-called voltage-sourced converter or VSC. In comparison to previously used technology, this VSC will offer greater advantages throughout the entire grid. This will include, for example, the generation of reactive power as well as a restart following a power outage/cut.
Within the ongoing establishing of grid development plans, the Federal Network Agency (Bundesnetzagentur) continuously verifies and insists on the need for a DC link. Most recently, this can be found in the grid development plan for 2030, dated December 2019.
The need for the line was laid down in law by the Federal Requirements Plan Act (Bundesbedarfsplangesetz). The change in the Federal Requirements Plan Act in late 2015 confirmed the need for the project whilst coinciding with the alteration of grid connection points. The line now runs from Wolmirstedt near Magdeburg (Saxony-Anhalt) to Isar near Landshut (Bavaria). Before, the grid connection points were Lauchstädt in Saxony-Anhalt and Meitingen in Bavaria.
The change to the start and end connection points was a direct result of an update and revision of the Renewable Energy Sources Act of 2014. Because of the new subsidy conditions, an imminent regional change is expected in the growth of wind power capacity.
Coupled with the amendment of the Federal Requirements Plan Act, underground cables became the norm for direct current projects at the extra high voltage level. Now, overhead line sections are only to be used in exceptional circumstances.
Planning for the SuedOstLink as an underground cable project started in 2016. To begin, a route corridor grid was determined between Wolmirstedt and Isar. This corridor grid acted as the foundation for the federal sectoral planning (Bundesfachplanung) that was initiated in early 2017. In its decisions regarding the federal sectoral planning, until April 2020 the Federal Network Agency determined a continuous route corridor for further planning.
The SuedOstLink corridor which was established by the Federal Network Agency starts at Wolmirstedt, runs west of Magdeburg towards the south and follows the A14 motorway for about 60 kilometres East of Halle, the corridor branches off from the A14 in southward direction to join the A9 at Bad Dürrenberg and continues to follow in this direction for another 40 or so kilometres. North of Eisenberg, the corridor exits the motorway bundling and runs southward west of Gera, through the Thuringian and Saxon Vogtland. Near Gefell, it reaches the Federal State of Bavaria.
Within this corridor, 50Hertz proposed a routing and local alternatives. These proposal are found in the applications for the planning approval procedure (Planfeststellungsverfahren). The exact course and the development are subject to the ongoing procedure.
Within the guidelines set out in the federal sectoral planning, a number of municipalities have requested to check whether the SuedOstLink can be constructed as an overhead line for their territory. Out of the seven temporary sections, two are subject to ongoing studies. These two partial sections extend from Wolmirstedt to Magdeburg-Olvenstedt in the Börde district and from Welsleben to Förderstedt in the Salzland district.
The individual steps taken within the planning and permit procedure, are set out in the Grid Expansion Acceleration Act (Netzausbaubeschleunigungsgesetz, NABEG). The process is divided into two parts: the federal sectoral planning and the planning approval. The Federal Network Agency located in Bonn is responsible for both. At the end of the federal sectoral planning, the authority determines a route corridor with a continuous width of 1,000 metres for further planning. The subsequent planning approval procedure defines the exact course of the line (the so-called route) within that corridor.
In the meantime, the federal sectoral planning for the SuedOstLink was completed. The project is currently undergoing the planning approval procedure. For practical reasons, the project is divided into separate sections for the permit. 50Hertz is responsible for sections A1 (Wolmirstedt to Könnern), A2 (Könnern to Eisenberg) and B (Eisenberg to the federal state border between Thuringia and Bavaria). Project partner TenneT oversees the other sections on the Bavarian side.
In late December 2019, 50Hertz submitted the application to launch a planning approval procedure for section B (see § 19 NABEG) to the Federal Network Agency. The applications for sections A2 and A1 followed in late April 2020 and mid May 2020.
You can find an overview of the status of the procedures for the individual sections of the SuedOstLink on the website of the Federal Network Agency.
In respect of the converter in the Wolmirstedt substation, the prospective feasibility was set with the corridor decision by the Federal Network Agency. The decision against alternative converter sites was confirmed by the Federal Network Agency. Any future planning is therefore focus at the Wolmirstedt site.
The permit for the converter and those for the line are achieved separately. The converter will be approved within the guidelines of the Federal Immission Control Act (Bundesimmissionsschutzgesetz), incl. the noise expertise, EMF expertise and balance and compensation measures. The relevant competent authority is the district of Börde. The permit procedure is expected to start in 2021.
In the planning and permit procedure, extensive measures to involve the general public are already imposed by the law. Nonetheless, 50Hertz involves administrations, elected officials, associations as well as citizens within the planning, aside of the formal procedure.
Even before 50Hertz submitted the applications for federal sectoral planning, the project team had already discussed the planning in the autumn of 2016, gathered over 600 comments and subsequently revised the corridor grid. Since then, 50Hertz has made a further five visits to Saxony-Anhalt, Saxony and Thuringia with information fairs and the DialogMobil to discuss the planning progress for the SuedOstLink with local residents.
Detailed information on the project’s progress as well as other materials are available on the following pages (in German).
In the current version of the 2025 Grid Development Plan, the project can be found under “DC5I: HVDC connection from Saxony-Anhalt to Bavaria”. In the Federal Requirement Plan Act, amended in December 2015, the project is listed as “Project no. 5, extra high voltage line Wolmirstedt-Isar, direct current”. The designation “Corridor D” is also used in earlier Grid Development Plans as well as in the Federal Network Agency’s current document for the 2014 needs assessment.
Until April 2016, 50Hertz called the project South-East DC Passage or South-East Passage. The project’s current name is “SuedOstLink”.
Federal Requirements Plan Act
Grid Expansion Acceleration Act
Energy Industry Act (EnWG §§11-12)
Scenario and grid planning at the Federal Network Agency
Grid development plan for electricity of the transmission system operators
Line projects from the Federal Requirements Plan Act
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