Floating offshore wind will play a key role in the transition to clean, green electricity production. With 250 gigawatts (GW) of floating offshore wind set to be brought online globally by 2050, the integrity of the dynamic cables which will transport the generated electricity is paramount – no cable, no power transmission.

A typical 1GW floating offshore wind farm (FOWF) will have over 120 dynamic cables subjected to constant environmental loading. While dynamic subsea cables have been used for many years in the oil and gas industry, the sheer volume of cables required for floating offshore wind provides a unique opportunity to utilise digital twin and machine learning technologies to assist in the integrity management of these cables.

The Whole of Life Subsea Cable Digital Twin is a digital representation of the subsea cable system at a floating offshore wind farm. This is designed to be used as the cable system progresses through its life cycle, from design, into installation, through operation and finally decommissioning. The benefit of this approach is that an integrated, as maintained picture of cable health can be developed, giving the cable owner confidence in the real-time integrity and performance of the cable.

During operation, an array of edge sensors are used to gather data on conditions surrounding the wind farm, including the weather, the motion of floating platforms, and the electrical performance. The digital twin incorporates a 3D model of the FOWF site with actionable cable health indicators and alerts for issues such as mechanical fatigue or electrically induced thermal damage. From here, the user can drill down to a range of dashboards for further information on a particular cable. As the digital twin represents the as-maintained condition of the cable, operators can use the data generated to make informed decisions relating to life-extension or repurposing of their physical assets. While the focus at present is on cable health, this digital twin environment can be extended to include other components of the floating wind farm including mooring, hull and turbine integrity, maintenance and performance.

A digital upgrade

Existing methods for cable fatigue monitoring involve running multiple simulations to represent the environmental loading on the cable. This method can take weeks, or even months, of analysis and engineering time to complete for a single cable, and are typically conducted infrequently, leading to a severely lagging indicator of cable health. Leveraging ‘smart’ digital twining methodologies, we combine proven techniques for global and local cross-section analysis with machine learning for near real-time predictions of accumulated damage for multiple cables. In addition, the digital twin architecture is designed to facilitate the use of emerging and maturing technologies such as digital strain sensing (DSS).

Digital twin technology allows for the adoption of predictive maintenance procedures based on the performance of each cable. This enables planned interventions, which can ultimately reduce the levelised cost of energy (LCOE) associated with floating offshore wind; it is estimated that operational expenditure (OPEX) accounts for approximately 30% of LCOE.

Cable operators invest significant sums in instrumentation and digital systems for their offshore assets. Wood is working closely with key industry partners to significantly bolster the life cycle economics of their floating offshore wind farms. By providing advice and innovative solutions, our clients can maximise their returns on strategic technology investments during the capital expenditure phase to increase the performance and reliability of their assets, and to optimise the operating processes through connected design.