Kriegers Flak: Connecting offshore wind farms to onshore grids

11. August 2022

Solution provider

NKT connects a greener world with high-quality power cable technology and takes centre stage as the world moves towards green energy. NKT designs, manufactures, and installs low, medium and high voltage power cable solutions enabling sustainable energy transmission.

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Challenge

Connecting offshore wind farms to onshore grids is essential to enable integration of more renewable energy and pave the way for a sustainable future. In turn, interconnecting grids create opportunities to strengthen energy markets, secure supply and share capacity. As the selected supplier of cable systems and installation work, NKT contributes to the unique Kriegers Flak development in the Baltic Sea. Two national electricity grids are being connected via offshore wind farms. The European power transmission system is evolving towards an infrastructure based on high-voltage cable systems. The Kriegers Flak connection and interconnection showcase this transformation and support the European Union’s goal of reaching a minimum of 32 percent renewable energy by 2030.

Solution

NKT’s solution consists of 220 kV (kilovolt) HVAC (high-voltage alternating current) cable systems between the offshore transformer platforms and connections to shore. The advanced solution enables the integration of 600 MW (megawatt) into the mainland grid, and brings green energy to 600,000 Danish households. Design, testing and production of the submarine cable system were conducted in NKT’s world-class facilities in Karlskrona, Sweden. NKT was also responsible for installation, cable-laying and pull-in operations for the three-core submarine cables. This approach significantly reduces interface risk thanks to NKT’s in-depth understanding of both cable systems and installation methodology.

NKT’s experience and expertise ensure reliable transmission of electrical energy. The offshore cable laying, platform connection and land installation were successfully performed with the state-of-the-art cable-laying vessel NKT Victoria. The vessel is built specifically for handling and laying submarine cables. The performance was excellent, with regards to both speed and accuracy, and the mission was completed within the scheduled time. This grid connection has a total length of about 100 km, of which 11 km is between platforms and 44 km is from each of these platforms to shore, the project was massive and called for smooth execution.

As a supplier of the cable system and installation, NKT provided its expertise throughout the value chain, which enables a safer and more predictable project execution, both in terms of liabilities and costs. The cable system was put into service in 2019.