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An increase of 10,000 megawatts

TenneT installs two new offshore converters - 10 GW transmission capacity reached in the North Sea

10.06.2025

Source: E & M powernews

Tennet has installed two converter platforms in the German North Sea. The grid operator has thus increased its transmission capacity to around 10,000 MW.

Transmission system operator Tennet has installed two more offshore converter platforms in the German North Sea: "BorWin epsilon" and "DolWin epsilon". Both platforms are part of the Borwin 5 and Dolwin 5 grid connection systems and will each transport 900 MW of renewable electricity from offshore wind farms to land. This will increase Tennet's transmission capacity in the German North Sea to almost 10 GW, Tennet announced on June 10.

Both platforms convert the electricity generated by offshore wind turbines from 66 kilovolt three-phase current into 320 kilovolt direct current and thus transport it to the mainland with as little loss as possible. The electricity from Borwin Epsilon is transported to the Garrel/Ost converter station via a cable route around 230 kilometers long. Dolwin Epsilon is connected to the Emden/Ost converter station via a cable route around 130 kilometers long.

With the Dolwin 5 grid connection, Tennet is breaking new ground for the first time (we have reported on this several times): A 66-kilovolt direct connection was used for the first time. In contrast to previous projects, a wind farm transformer station is no longer required. Instead, the wind power generated off the coast of Lower Saxony will be transmitted directly to the converter platform as three-phase current. "Borkum Riffgrund 3" is therefore the first offshore wind farm to be built by Orsted without an offshore substation (OSS): The connection concept provides for a direct connection of the wind turbines to the Dolwin Epsilon offshore converter platform.

The Borwin Epsilon converter platform and the Borwin 5 submarine cable will connect the North Sea wind farm "He Dreiht" (East Frisian for "He turns") with a capacity of 960 MW to the power grid. "He Dreiht" also transmits its alternating current directly - without its own transformer platform - to the converter platform at a voltage level of 66 kV. "With Dolwin 5 and Borwin 5, we will be commissioning two high-performance offshore grid connections this year, which will bring us very close to the 10-gigawatt mark," said Tennet CEO Tim Meyerjürgens.

Author: Heidi Roider