525kV technology for Germany’s “power highways”

04.12.2019

SuedLink, SuedOstLink and A-Nord are large-scale DC connection projects that are essential for Germany’s low-carbon energy future, since these so-called “Stromautobahnen” (power highways) will transport green electricity generated in the north and east of the country to the consumption centres in the south and west. The three power lines will be implemented predominantly via underground cabling and are collaborative efforts of the four German transmission system operators (TSOs). TenneT and TransnetBW cooperate on SuedLink, 50Hertz and TenneT join forces on SuedOstLink and A-Nord is carried out by Amprion. Together with Ultranet, a joint project with TransnetBW, A-Nord forms the Korridor A.

The four TSCNET shareholders intend to install innovative plastic-insulated DC cables with a voltage level of 525kV in these projects. So far, 320kV cables have been used for comparable DC connections in Germany. As a matter of fact, it will be the first use of 525kV underground cables worldwide, which underlines the pilot character of the three high-performance connections. The decision by the TSOs was preceded by an extensive test phase on the technical suitability of the 525kV cables. The pre-qualification tests according to international standards of the Council on Large Electric Systems (CIGRE) were successful and proved that the 525kV cables are reliable and safe.

A higher voltage level of the cables translates into more transmission capacity. This has two possible effects for the planned DC lines, assuming technical feasibility for the entire system: On the one hand, more electricity can be transmitted in a certain corridor with the same number of cables. On the other hand, fewer cables are required to transmit the same power compared to 320kV cable systems. This allows the routing to be designed narrower, which reduces excavation work and environmental impact.

The four German TSOs opt for innovative 525kV solution for power highways with underground cabling (picture: TenneT)

Linkup
> See 50Hertz press release, in German (html)
> See Amprion press release, in German (html)
> See TransnetBW press release, in German (html)