TenneT awards contract for BorWin6 HVDC connector in the North Sea
McDermott International said it has been awarded its largest-ever renewable energy contract from German transmission grid operator TenneT for BorWin6, an innovative 980-MW High-Voltage, Direct Current (HVDC) project.
Additional project partners include Global Energy Interconnection Research Institute and C-EPRI Electric Power Engineering Co. (GEIRI / C-EPRI).
BorWin6
BorWin6 is the fifth offshore grid connection for offshore wind farms in the German North Sea that has been constructed under the direction of TenneT. Scheduled for delivery and commissioning in 2027, the system will transmit 980 megawatts of wind power. It will include 235 kilometers (146 miles) of lines divided between land and sea: about 190 km (118 miles) of sea cables and 45 km (27 miles) of land cables. The wind power produced at sea will be converted into direct current at a converter station, transported to the shore and converted back into three-phase current at a land-based converter in Büttel (Schleswig-Holstein) and fed into the extra-high voltage grid.
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TenneT said the system uses an innovative 66-kV direct connection, whereby the wind turbines are connected directly to the offshore platform via 66-kilovolt three-phase cables. This means that a separate — and costly — wind farm transformer station is no longer required.
McDermott’s role
McDermott will provide engineering, procurement, construction, installation and commissioning (EPCIC) services for the platform, located 190 kilometers (118 miles) off the German coast on the Platform North Sea Cluster 7 in a water depth up to 131 feet (40 meters).
Electricity generated from offshore wind farms (to be commissioned at a later date) will be converted into direct current and transported to an onshore converter station located 28 miles (45 kilometers) onshore near Büttel, Germany.
McDermott will lead the consortium with its main focus on the converter stations. GEIRI / C-EPRI will provide the electrical engineering work. McDermott will fabricate the topside in Qingdao, China, and the jacket in Indonesia.
According to Tim Meyerjürgens, COO of TenneT, the project is an example of the ongoing cost reductions in offshore wind grid connection systems. “We are also applying the smart platform concept by installing particularly low-maintenance technology on the offshore platform. This enables us to reduce the maintenance effort and ultimately the operating costs of the asset,” he said in a press release.
Next steps
The contract for the production and laying of the cables will be awarded before the end of this year, said TenneT. In addition, construction of the land station in Büttel has been planned and will begin in 2024. Construction of the topside, i.e. the actual converter station at sea, which will be built in Qing-dao (China), is expected to start in mid-2023. Construction of the jacket in Batam (Indonesia) will also start at the end of 2023. The jacket will form the substructure on which the platform will be placed, probably in mid-2026, said TenneT.
In 2023, horizontal drillings are also planned to underpass the land protection dike (near Büsum) and the Kiel Canal; the land cable will be laid in 2024 and 2025, and the subsea cable in 2025 and 2026.
Originally published by Jennifer Runyon on power-grid.com
