Consortium to build first AC/DC converter system in Baltic Sea

German TSO 50Hertz has appointed a consortium of tech company GE Vernova and offshore services provider Drydocks World to construct a converter system in the Baltic Sea.

The converter system will consist of offshore and onshore converters for the Ostwind 4 grid connection project, which will involve the construction of grid connections for offshore wind farms located to the northeast of the German island of Rügen.

The EPCI contract that 50Hertz has signed with the consortium covers all engineering services, the procurement of the necessary components, and the construction, transport and installation of the systems at sea and on land.

The high-tech components for the converters will be exclusively manufactured at the European production sites of GE Vernova. GE Vernova will also construct the onshore converter, which will be accommodated in a hall.

The main component of the offshore platform, its ‘topside’, will be built at the Drydocks World shipyard in Dubai. Drydock World is also responsible for the substructure (or ‘jacket’), on which the offshore converter will be anchored to the seabed.

The converters will be configured in accordance with the 2GW/525kV standard agreed upon by the German TSOs TenneT, Amprion and 50Hertz.

According to 50Hertz in a release, this marks the first time that the state-owned port and shipyard company of the United Arab Emirates has received an order for converters in line with this standard.

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Ostwind 4 grid connection project

The wind farm concession area in which the converter system will be located was purchased during an auction by Total Energies. The area is located on the edge of the German Exclusive Economic Zone (EEZ).

A subsea cable that will be approximately 110km long is due to run from the offshore converter, through the Greifswald Bodden, to Lubmin near Vierow.

An underground cable that will be approximately 4km long will run from Lubmin to the planned substation with the counter-converter in the municipality of Brünzow in the district of Vorpommern-Greifswald. It is here, that the DC will be converted back into AC and fed into the 50Hertz extra-high-voltage transmission grid.

The contract for the production and installation of the subsea and underground cables was awarded to the Danish company NKT in 2023.

Commenting on the converter system consortium in a release was Stefan Kapferer, CEO of 50Hertz: “The awarding of the contract to GE Vernova and Drydock World marks the beginning of a new chapter in the use of wind energy in the Baltic Sea.

“50Hertz is the first transmission system operator to deploy 2GW/525kV technology in this sea area. This is pioneering work. We want to ensure that the entirety of the technically and economically viable offshore wind energy potential in the Baltic Sea is exploited, primarily with the help of direct current technology.

“To do this, we need to think and act in an even more networked way across national borders. One prerequisite for this is the creation of legal and regulatory conditions that enable wind farms in the waters of other EU states to be connected to the German transmission grid.”

Added Philippe Piron, CEO of GE Vernova's Electrification Business: “Ostwind 4 represents a crucial milestone in our mission to electrify and decarbonise with the energy to change the world. By leveraging our advanced HVDC technology, this key infrastructure project underscores the essential role of offshore wind to ensure European energy security and to accelerate the global energy transition.

“This order also highlights the rapid growth in GE Vernova's Electrification segment, our fastest growing business, as our customers invest in the grid. We are very proud to collaborate with 50Hertz and Drydocks World to advance Germany’s renewable energy goals and set a new standard for a resilient and sustainable grid infrastructure.”

Said Sultan Ahmed Bin Sulayem, Group chairman and chief executive officer of DP World: “Drydocks World’s pivotal role in the Ostwind 4 Project underscores its technical excellence and commitment to advancing sustainable infrastructure.

“This award reflects DP World’s broader mission to drive clean energy transitions and economic growth. As the global energy landscape evolves, we remain dedicated to leveraging our expertise and innovative capabilities to support initiatives that drive clean energy transitions and economic development.”

Signatories of the contract have agreed not to disclose the order volume or any details about the contract.