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.
As part of the SuedOstLink project, two DC connections will be realised: one of these connection will transport electricity from Wolmirstedt to Isar. It is designated as project no. 5 in the Federal Requirements Plan Act. Another connection transports electricity from the area of Klein Rogahn, west of Schwerin, to Isar. This line should connect with the SuedOstLink in the Börde district. It is designated as project no. 5a in the act.
The project developer who will oversee the northern part of the SuedOstLink is 50Hertz. Transmission system operator TenneT is responsible for the southern part, in Bavaria.
Both connections will each transport 2,000 megawatt at a voltage of 525 kilovolt. Since 2015, the Federal Requirements Plan Act stipulates that underground cables are the standard for HVDC projects. Now, overhead line sections are only used exclusively in strictly limited circumstances.
Project no. 5 within 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 between the Börde district and the Isar site consists of two line connections:
One direct current connection is planned between Wolmirstedt near Magdeburg and the Isar site near Landshut. Since the end of 2015, this line connection has been listed in the Federal Requirements Plan Act as "Project no. 5, Wolmirstedt – Isar, high voltage line, direct current." Earlier project names for Project no. 5 has also been "Gleichstrompassage Sued-Ost" and "Sued-Ost-Passage."
The SuedOstLink also includes the southern part of a direct current connection between the area of Klein Rogahn near Schwerin and the Isar site, which begins at Börde district. This line connection has been designated in the law since February 2021 as "Project no. 5a, Klein Rogahn – Börde district – Isar, high voltage line, direct current." The planning for the northern part between Klein Rogahn and the Börde district is shown on the project website for SuedOstLink+.
As part of the SuedOstLink, two line connections will transport 2,000 megawatts of electricity each. This corresponds to the capacity of around 700 wind turbines operating at full load. Per line connection, two plastic-insulated underground cables are used that are specifically designed to withstand a voltage of 525 kilovolts.
The SuedOstLink 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. For project no. 5 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.
For the line connection of project no. 5a coming from the North and joining the SuedOstLink in the Börde district, converters are needed in the nearer area of Klein Rogahn and Isar. In the Börde district, there will be no other converters for this line.
According to the prognoses from the draft scenario framework of the Federal Network Agency (Bundesnetzagentur, BNetzA), the installed capacity of all renewable generating units will more than double, from 26.6 to 55 GW, between 2019 and 2035 in Mecklenburg-Western Pomerania, Brandenburg and Saxony-Anhalt alone. At the same time, Germany is phasing out nuclear energy, and even the coal-fired power plants are gradually going off the grid. Gas-fired power plants and the distributed development of renewables cannot completely replace this decrease.
In view of this evolution, the SuedOstLink contributes to secure the supply to consumers in South Germany and to guarantee the system stability in the German and European transmission system.
The need for a DC connection between Saxony-Anhalt and Bavaria has been part of the Grid Development Plans of the transmission system operators since 2012.
The Federal Network Agency also continuously verified and confirmed its necessity. Most recently, this confirmation could be found in the Grid Development Plan for 2030, dated December 2019. The need was laid down in the Federal Requirements Plan Act as project no. 5 with the grid connection points Wolmirstedt and Isar.
The transmission system operators calculated the need for additional transmission capacity between the area of Klein Rogahn and Isar in the Grid Development Plans for 2030 of 2017 and 2019 for the respective forward-looking scenarios. The legislator again included the line connection between Klein Rogahn and Isar as project no. 5a in the Federal Requirements Plan Act in February 2021. At the same time, the possibility to also install conduits in the scope of project no. 5 was dropped by the amendment.
The complete text of the Federal Requirements Plan Act
For the two DC connections planned within the SuedOstLink project, the planning team of 50Hertz is looking for a suitable route within a corridor of 1,000 metres wide. This corridor was laid down and made binding by the decision of the Federal Network Agency on federal sectoral planning of 2 April 2020. In this corridor, the line route is determined in the scope of the ongoing approval procedure.
The SuedOstLink corridor starts at Wolmirstedt, runs west of Magdeburg towards the south and follows the A14 highway (Autobahn) 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 about 40 kilometres. North of Eisenberg, the corridor exits the highway (Autobahn) bundling and runs southward west of Gera, through the Thuringian and Saxon Vogtland. Near Gefell, it reaches the Free State of Bavaria.
Map with SuedOstLink corridor route
At the end of the federal sectoral planning, the authority determined a route corridor between Wolmirstedt and Isar 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. 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 no. 5 (Wolmirstedt-Isar)
For project 5a, 50Hertz submitted the applications for the planning approval procedure for SuedOstLink sections A1, A2 and B in the course of 2021. The plan is to install the lines for project 5a along the route that was already developed in the scope of the planning approval procedure for project 5. 50Hertz will ask the Federal Network Agency to couple the planning approval procedures for projects 5 and 5a to ensure that this is successful, to avoid double work and to align the plans in the best possible manner.
You can find an overview of the status of project no. 5a (Klein Rogahn - Landkreis Börde - Isar) on the website of the Federal Network Agency.
No change in corridor width
An important note: looking ahead, it was initially planned to also lay conduits for project no. 5. This is no longer part of the planning. Instead, the underground cables of project 5a can take up their place along the route. 50Hertz does not expect any major changes to the widths of the regular working strips (approx. 40-45 m) and the protecting strips (approx. 21 m).
Overhead line assessing and evaluating still ongoing
Within the guidelines set out in the federal sectoral planning for project no. 5, 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 run from Wolmirstedt to municipality Hohe Börde in the Börde district and from Welsleben to Förderstedt in the Salzland district.
Plan approval applications for project no. 5 (Wolmirstedt – Isar):
Application § 19 NABEG for section A1
Application § 19 NABEG for section A2
Application § 19 NABEG for section B
Plan approval applications for project no. 5a (Landkreis Börde – Isar):
The location of the converter at the Wolmirstedt substation was classified by the Federal Network Agency as likely to be feasible as part of the corridor decision. The exclusion of alternative converter locations was confirmed by the BNetzA. Further planning is therefore based on the Wolmirstedt site.
50Hertz is obtaining approval for the converter independently of the approval procedure for the line connection. The converter is to be approved within the framework of the Federal Immission Control Act, including noise assessments, EMF assessments and compensation and replacement measures. The district of Börde is responsible for this. The approval process is scheduled to begin in 2022.
In the planning and approval process, extensive measures for the involvement of the public are already prescribed by law. But 50Hertz also involves administrations, elected officials, associations and citizens in the planning process beyond the formal procedure.
Even before 50Hertz submitted the applications for federal sectoral planning, the project team discussed the plans in the fall of 2016, collected more than 600 comments and subsequently revised the corridor network. Since then, 50Hertz has been to Saxony-Anhalt, Saxony and Thuringia many times with information markets and the DialogMobil to present the respective plans to the people on site and to gather their opinions and suggestions.
Detailed information on the project’s progress as well as other materials are available on the following pages (in German).
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
Project 5 within the SuedOstLink as a "project of common interest" (PCI) of the European Union is crucial for the further improvement of security of supply and the expansion of renewable energies and receives funding.
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