Erdkabel auf Rolle

Cable planning for SuedOstLink

Key grid expansion project for the energy transition

The SuedOstLink will bring electricity generated from renewable sources in the north of Germany to the south of the country. To do so, it connects Wolmirstedt near Magdeburg (Saxony-Anhalt) with the former Isar power plant site near Landshut (Bavaria) with high-voltage direct current underground cables.

Erdkabel im Querschntt
©50Hertz Transmission GmbH/Jan Pauls

In 2013, the SuedOstLink was legally anchored in the “Bundesbedarfsplan” (plan, in which the German legislator lists all the required grid projects in binding form) as Project 5. Planning for this connection, which is primarily planned as an underground cable, has been underway with the project developer 50Hertz since 2016.

AFRY has been supporting the project in cable planning since 2019. During the tendering phase for the extra-high-voltage cables, the focus was on the technical evaluation of the bids. This was followed by the approval planning of all route sections with the following main topics in the cable planning:

  • Cable logistics
  • Typicals
  • Area planning
  • Technical support for expert opinions
  • Routing - cable planning
  • Method descriptions
  • Initial section length planning

The approval planning has now been completed. On this basis, production planning began for the underground cables, which are being manufactured specifically for the SuedOstLink high-voltage direct current connections.

Cable factsheet

  • Voltage: 525 KV
  • Diameter: approx. 140 mm
  • Copper cross-section: 3,000 mm2, with plastic insulation
  • Weight: approx. 40 kg/m
  • Length of a cable section: max. 2 km
  • Route length for the SuedOstLink (part 50Hertz): approx. 270 km
  • Connection of the cable sections along the route with a total of approx. 620 joints

Due to the enormous scope of work, AFRY has been supporting the SuedOstLink project since mid-2022 with two specialist project managers for cable planning: Felix Hamann is responsible for the southernmost section, while his colleague Kevin Reimers is responsible for the middle of the three sections under the responsibility of 50Hertz.

©50Hertz Transmission GmbH/Jan Pauls
Erdkabel auf Rolle
©50 Hertz Transmission GmbH/Jan Pauls

Highly complex project

The biggest challenge is the complexity of the SuedOstLink project. There are numerous interfaces between the service providers involved, whose activities often interlock and influence each other. In iterative processes, changes and revisions have to be made again and again. With cable planning, AFRY has a particularly large number of interfaces with other specialist trades, such as civil engineering, stations and approval, but also operational preparation and asset management.

"My experience really helps me to evaluate things and keep an overview on all these tasks. Coordination with the other parties involved is also essential." – Felix Hamann

Infrastructure crossing agreement

One of the tasks of the AFRY cable planning project managers is to obtain crossing agreements. If the SuedOstLink route crosses other infrastructure, such as roads or power lines, it must be clarified how this structure may be crossed. Sometimes the planners have to maintain clearances, take protective measures or obtain impact assessments in advance. All aspects are ultimately regulated in a crossing agreement.

AFRY's specialist project managers also coordinate the interfaces with regards to right of way and construction process, taking logistics into account, and manage the installation and execution planning of the contractor cable as well as the final section planning.

"My range of tasks is quite varied," says Felix Hamann, describing his activities at SuedOstLink.


Areas of expertise in project management for cable planning:

  • Implementation planning for civil engineering with regards to cable issues (preparation for the awarding of civil engineering services)
  • Site-specific cable planning (logistics, installation)
  • Negotiation of crossing agreements
  • Tendering, awarding and management of external experts for electromagnetic interference
  • Support for construction scheduling
  • Final section length planning
  • Updating cable logistics, taking into account road construction and right of way aspects
  • Preparation of change requests
  • Supervision of inspection processes
  • Interface coordination with our subjects such as approval, stations, properties, etc.

Contact Niels Hornig

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