The German transmission system operator Amprion has awarded the contract to Siemens for two converter systems, each forming a grid connection capable of carrying 2GW, in what will be the world's first order for a 2 GW grid connection at sea. In total, up to four GW of green electricity from several offshore wind farms in the German North Sea could be transported to shore. The contract is worth a total of more than €4 billion including maintenance for ten years. The converter systems are being provided by Siemens Energy and Spanish company Dragados Offshore. For Siemens Energy it is the largest offshore grid connection order the company has received to date.
With the Wind Energy at Sea Act, the German government set the framework for further expansion of offshore wind energy in Germany: installed capacity is to increase to at least 30 GW by 2030 and as much as 70 GW by 2045. This will require more than just new wind farms – more powerful high-voltage direct-current transmission systems must be built to transport electricity over the long distances involved.
The increase in transmission capacity to two GW is said to represent a decisive technological leap, as more wind farms can now be connected to the grid via the new systems. Siemens Energy used a bipolar configuration design to create the 2 GW systems, meaning they can effectively operate at twice the voltage and transmit twice the power. The new projects are among the world's first offshore grid connections of this type.
Siemens Energy's scope of supply consists of two converter platforms at sea and two associated stations on land. Each to the two converter stations on land is connected to the source via a DC cable of 390 km (242 miles). They are being built near Wehrendorf in Lower Saxony and Westerkappeln in northern North Rhine-Westphalia.
Siemens Energy will manufacture all major high-voltage equipment for the two connection systems, such as converter technology, transformers, and switchgear, in Germany and will assume the systems’ complete maintenance for a period of 10 years. This includes services to ensure cyber security and transport logistics, such as the provision of service ships and helicopters. The Spanish consortium partner, Dragados Offshore, is responsible for the construction and offshore installation of the associated platforms. Construction will take place at the company's shipyard in Cadiz, Spain.
In addition, the systems are designed to be integrated into multi-terminal-systems in the future. Instead of pure point-to-point connections, several direct current connections could converge in one station. The converter systems will then act as electricity hubs at the grid nodes that transmit the electricity according to the demand situation.
The connection systems are expected to transmit power by 2029 and 2030.
Image: The first of two grid connection systems from Amprion for German North Sea wind power is scheduled to go into operation in 2029 (courtesy of Amprion Offshore GmbH)