SuedOstLink

As part of the SuedOstLink, two line connections will transport 2,000 megawatts of electricity each. This corresponds to the capacity of around 1,400 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 current intensity is 3,800 amperes.

The new line will be established as an extra high-voltage direct current (HVDC) transmission line. Compared to the conventional meshed alternating current grid, this technology is much better suited for the transmission of large electricity volumes across great distances with low 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 is building a converter at the Wolmirstedt substation. This converter will entail a so-called voltage-sourced converter or VSC.[HA1] 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 the ability to support a grid-restart following a power outage.

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 Klein Rogahn area and at the Isar site. In the Börde district, there will be no other converters for this line.

In the north-east of Germany, the feed-in of renewable energy is constantly increasing, especially from on- and offshore wind farms as well as solar power.

In the south of Germany, on the other hand, the phase-out of the last nuclear power plants in the spring of 2023 as well as the enacted coal exit, there will lead to a systematic supply shortage in the coming years.

Gas-fired power plants and the decentralised development of renewable energy will not be able to fully replace the energy generated by the shut-down nuclear power plant.

The SuedOstLink unlocks the renewables in the north-east for the load regions in southern Germany and, at the same time, supports the coverage of the maximum load and, as such, the security of supply in Bavaria.

See also the project summary in the grid development plan for electricity 2037/2045, version 2023, 2nd draft, page 444 in German

The need for the SuedOstLink is stipulated in the Federal Requirements Plan Act. Both lines of the SuedOstLink are included as Projects no. 5 and 5a.

Federal Requirements Plan Act in German

For the two DC connections planned within the SuedOstLink project, the planning team of 50Hertz is looking for a suitable route within a corridor 1,000 metres wide. The route itself includes a protective strip, which is usually 21 metres wide.

The corridor was laid down in binding form by the Federal Network Agency on 23 October 2019 in its decision on federal sectoral planning for section B in German and on 2 April 2020 in the decision on federal sectoral planning for section A in German. 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 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 follows the motorway 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 Bavaria.

Map with SuedOstLink corridor route

For the further planning, the Federal Network Agency stipulated a continuous corridor of 1,000 metres in width between Wolmirstedt and Isar. The localisation of the exact line route is the object of the currently ongoing planning approval procedure. For practical reasons, the course of the SuedOstLink is divided into sections. 50Hertz is responsible for sections A1 (Saxony-Anhalt North), A2 (Saxony-Anhalt South) and B (Thuringia/Saxony).

Project no. 5 (Wolmirstedt-Isar)

All sections of Project no. 5 are now undergoing the planning approval decision. The applications, all submitted up to the second quarter of 2020, included a so-called route proposal. This is the starting point for the further detailed planning. The survey scopes imposed by the Federal Network Agency specify how project developer 50Hertz shall further detail the planning approval documents.You can find an overview of the state of affairs for the individual sections of Project no. 5 (Wolmirstedt-Isar) that are part of the SuedOstLink on the Federal Network Agency’s website in German.

Project no. 5a (Area Klein Rogahn-Isar)

For Project no. 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 no. 5a along the route that was already developed in the scope of the planning approval procedure for Project no. 5. 50Hertz will ask the Federal Network Agency to couple the planning approval procedures for Projects no. 5 and no. 5a 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-Isar) on the website of the Federal Network Agency in German.

Overhead line examinations

Within the guidelines set out in the federal sectoral planning for Project no. 5, a number of municipalities have requested to examine whether the SuedOstLink can be constructed as an overhead line for their territory. Out of initially seven sections, two promising sections were examined thoroughly. The section from Wolmirstedt to Niederndodeleben in the Börde district showed sensibly executable and is part of the complete application for planning approval of 2023.

Another section, between Welsleben and Förderstedt, in the Salzland district, proved neither technically nor economically sensible and was therefore not applied for.

Complete planning approval applications for Project no. 5 (Wolmirstedt-Isar) and for Project no. 5a (Börde district-Isar) (all following links refer to webpages in German language):

Application under § 21 NABEG for section A1 (Project no. 5a)

Application under § 21 NABEG for section A2 (Project no. 5a)

Application under § 21 NABEG for section B (Project no. 5a)

The Börde district gave 50Hertz the approval for the construction of the converter in October 2022. The installation was approved according tot he Federal Immission Control Act (Bundes-Immissionsschutzgesetz, BImSchG). Among other things, this procedure ensures that the installation will certainly comply with all applicable legal noise and field requirements during later operation. The surrounding greenery in the form of compensatory and replacement measures is now arranged in a binding manner. Construction was started with the ground breaking ceremony in March 2023. The goal is to commission the converter in 2025.

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 many visits to Saxony-Anhalt, Saxony and Thuringia with information fairs and the DialogMobil to present the respective planning to local residents and to gather their opinions and tips.