De-risking floating wind: Technology & Deployment

Session

PH15: DNV Multipartner Joint Industry Project on Floating Substations

In recent years, the wind industry has increasingly turned towards floating wind. Initially focusing on the challenges involved with one or a few turbines, substations come as a next step when considering scaling-up to wind farms. The substation is a key structure for an offshore wind farm as it unlocks transmission of energy to the consumer.

For foreseen remote and deep-water floating wind farms, the design of substations is at present an unsolved challenge, although different concepts are under development. To help the wind industry address one of its bottle-necks for future scaling of floating wind, DNV has initiated a JIP, that will define design and qualification requirements and a standard for floating substations and will present the progress in addressing the technical challenges involved.

Floating substation design involves pushing technology limits. For example, dynamic export cables are typically of a higher specification than array cables. Robust methods are required for avoiding e.g. fatigue failures and associated risk for loss of production. For the substation power components onboard the floater, the combination of performance requirements and exposure to marine motions represent new technology. The JIP maps out the potential consequences involved and addresses how to qualify this technology and whether it sets limitations to floater and mooring design.

Wind farm developers, suppliers and TSO’s and DNV are behind the JIP results, which will be applicable industry-wide and captured in standards to drive standardization, lower project risk and cost and provide basis for future certification.

PH28: DNV + RWE: Extending life of offshore wind assets

Lifetime extension of onshore windfarms has received significant attention in recent years. On the technical side, the use of generic aero-elastic models of onshore wind turbines allows quick assessment of fatigue loading from site-specific conditions. For offshore wind farms, life extension is becoming increasingly important as first generation farms approach their design lives. Offshore wind presents new challenges due to the large number of simulations required, considering both wind and met-ocean conditions, and the site-specific nature and variations of support structure design.

DNV and RWE worked together to assess the condition of the Scroby Sands offshore wind farm with a view on extending the life of the wind turbine foundations. Detailed review of the data collected over the life of the wind farm from condition reports and SCADA data, along with refinement in modelling and understanding of driven monopile foundations enabled updates to technical assumptions that influence the overall fatigue life of steel structures. DNV made further refinements to the load calculations by completing a fully integrated time history analysis in Bladed, with an aero-elastic model developed by DNV, as the original OEM WTG model was not available. DNV were able to give RWE confidence in reaching the planned extension to life enabling RWE to plan targeted future maintenance works optimizing the OPEX budget for the final years of windfarm operation.

In this joint RWE-DNV paper, an overview of fleet management and operation of ageing assets will be provided along with technical process required to support that.