Industry-First Dynamic Cable System Solution at 245 kV

Submarine power cables are critical for offshore wind, especially as projects move into deeper waters and adopt floating technologies. Unlike fixed-bottom farms, floating turbines experience continuous motions from waves, currents, and wind, creating complex mechanical and thermal stresses that conventional static cables cannot withstand. Dynamic subsea cables are therefore essential. While 72.5 kV dynamic cables have been deployed in pilot projects, enabling largescale offshore wind farms (>250 MW) requires the development of transmission systems with significantly higher capacity. This means increasing both the voltage rating and the conductor cross-section to handle greater power flows over long distances in demanding subsea environments.

In this context, the focus of this paper is to present the development and qualification of a 245 kV HVAC dynamic cable system, which represents a major breakthrough in the industrial landscape. The cable features dry insulation and a longitudinally welded metallic sheath that provides both short-circuit current conduction and water barrier protection. A complete accessory suite was developed, including a rigid transition joint between dynamic and static sections, ensuring mechanical robustness and compatibility with offshore installation practices.

A comprehensive finite element analysis framework assessed extreme loads and fatigue over the system’s lifetime, both on the entire systems (Global Analysis) and on cable components

(Local Analysis).

Once the case study was defined, a testing protocol aligned with international standards and

CIGRE guidelines was drafted, and rigorous mechanical, thermal and electrical tests validated long-term reliability of all system components, ensuring their reliability throughout their service life and beyond.

These developments mark a significant step toward scalable, resilient high-voltage transmission for next-generation floating wind farms.