525kV cables for SuedOstLink


The SuedOstLink is one of the major German DC interconnection projects that are essential to Germany’s low-carbon energy future by transporting green electricity generated in the north and east of the country – mainly wind power – to the centres of consumption in the south and west. Like the other so-called “Stromautobahnen” (power highways), SuedOstLink is primarily implemented via underground cabling. Its realisation is a joint effort of the two TSCNET shareholders 50Hertz, the transmission system operator (TSO) from northeast Germany, and TenneT, the Dutch-German TSO.

The European Project of Common Interest (PCI) now has reached an important landmark with the award of the contract for around 1000 kilometres of underground cables, the definitive centrepiece of SuedOstLink. The technology to be used for this is a global novelty: plastic-insulated underground cables for a voltage of 525kV. With these cables, the SuedOstLink connection will have a transmission capacity of 2GW. The higher capacity requires fewer cables to transmit the same power. The routing can therefore be designed narrower and the necessary civil engineering work is decreased. This significantly reduces the impact on the public and the environment.

The contracts were assigned to NKT for the northern part of the project in the 50Hertz control area and to Prysmian PowerLink for the section under TenneT’s responsibility. Both companies are internationally represented in numerous connection projects on- and offshore and both have proven the quality of their cables in extensive prequalification tests. The contracts include design, manufacture, delivery, laying of the underground cables, further installation work and the final high-voltage testing of the cable system. SuedOstLink is currently in the planning approval process. It should be completed by the end of 2025.

Dr Frank Golletz, Technical Director at 50Hertz, expects the cables to be laid from 2022 and describes the contract award as “a good signal for the SuedOstLink joint venture project as well as for the energy transition across Germany and Europe”. Tim Meyerjürgens, Managing Director of TenneT, adds: “We will use the innovative, plastic-insulated 525kV underground cables for the first time worldwide and will thus set new standards in technology and the reduction of environmental impact.”

50Hertz and TenneT have assigned the orders for the 525kV underground cables for SuedOstLink (picture: NKT)

> See 50Hertz press release (html)
> See TenneT press release (html)