Dynamic Cable Systems in Irish Deepwater Floating Offshore Wind
I. Background and Challenges
In the waters off the west coast of Ireland, water depths often exceed 180m and are accompanied by high-energy swells from the North Atlantic. As the industry consensus states:
"The development of FOWF requires simultaneous advancements in several new supporting technologies, such as floating structures for mounting the wind turbines, floating offshore substations as well as dynamic export cables. Dynamic cables are submarine power cables that float in the sea and dynamically follow the movements of the floating equipment such as offshore floating high-voltage substations, as well as of the waves and tides. Unlike conventional transmission cables, which are static and designed to operate in conditions that are very different from those experienced by cables for floating offshore structures in marine renewable energy industries, cables for floating platform wind turbines must run through the water column from the platform base at the water surface to the touchdown point on the seabed. This trajectory exposes the cable to dynamic environmental forces. These cables are subject to greater levels of mechanical and electrical stress due to the platform’s motion and sea conditions. The structure must therefore have excellent resistance to mechanical fatigue caused by repetitive bending. Its design must ensure high durability."
To address these severe physical challenges, Irish pilot projects have adopted highly integrated Ancillary Equipment protection systems.
II. Application of Core Technical Components
1. Bend Stiffeners — Fatigue Buffering at Connection Points
On Irish floating platforms, dynamic cables exit the bottom of the platform through an I-tube. This is the "hard connection" point where stress is most concentrated.
Functionality: Designed for the intense heave and pitch motions of the North Atlantic, the tapered polyurethane Bend Stiffeners provides a progressive stiffness transition from the rigid platform structure to the flexible cable. It effectively distributes stress, preventing fatigue cracking caused by repetitive cyclic loading at the exit point.
2. Bend Restrictors — Rigid Protection at Critical Locations
As the cable transitions from the suspended section to the Touchdown Point (TDP) on the seabed, or crosses uneven seafloor terrain, it is highly susceptible to "kinking" due to current impacts.
Functionality: Once the cable bending reaches a pre-set Minimum Bending Radius (MBR), the interlocking half-shell bend restrictors lock together to form a rigid protective shell. This is particularly crucial in the rocky seabed environments common to Ireland, as it prevents over-bending and protects the cable from direct abrasion against seafloor rocks.
III. Conclusion and Benefit Assessment
By applying this suite of protection systems in the complex waters of Irish projects, the following objectives were achieved:
Enhanced Durability: The use of bend stiffeners extends the design life of the cables to over 25 years, matching the service life of the wind turbines.
Risk Mitigation: Bend restrictors effectively prevent irreversible mechanical damage during storm events (where wave heights exceeding 10m are common in Ireland).
System Flexibility: The synergy between buoyancy and anchoring allows the dynamic cable to "breathe" with the waves without generating excessive tension spikes.
Reach out to learn more about our integrated solutions for bend stiffeners, restrictors, and anchoring systems tailored for the Irish offshore market. [Contact Our Experts]
