E2 - Extending limits to operation or performance by mitigating extreme actions

A key cost reduction mechanism is the increase of the size of the power generating element of the ORE system, e.g. the turbine size or rated power of a wave device. As these parameters increase, stresses (actions) due to dynamic response can become prohibitive and so development of methods to mitigate and control system dynamics are required. To enable such increase of scale of key ORE design parameters improved understanding is required of the interaction of the environment with both the fundamental structural dynamics and control of the system.

Fundamental challenge is to enable modelling and prediction of peak (extreme) loads or actions accounting for environmental conditions interacting with the underlying system dynamics and control applied.

Designs in which load mitigation by continuous control of dynamic response becomes lower cost and / or larger scale than traditional design approaches.

Significant reduction of design safety factors.

Establish and extend operational limits or performance by better identifying and mitigating extreme loads and aggregated actions vs. operation behaviour at system and component level. Including interaction between environment and system control parameters and to extend operational limits of devices extending turbine size limits and fatigue life, understanding localised environment conditions to inform aggregated effects (e.g. on fatigue); modelling/prediction of extreme environmental loads.

Increased reliability and reduced OPEX of existing designs

New designs with lower CAPEX per MW and / or increased performance

Currently active research

• Morphing-Blades: New-Concept Turbine Blades for Unsteady Load Mitigation
  Lead institution: University of Edinburgh
  

  Within the EPSRC-funded project Morphing Blades, new-concept blades are developed to mitigate the effect of unsteady loadings on wind turbines, and numerical models are developed to accurately predict unsteady loadings experienced by conventional turbines and turbines equipped with morphing blades. The project has demonstrated the potential of morphing blades to cancel or substantially mitigate unsteady load fluctuations without affecting the mean load and the power harvested. Morphing blades can both be used to cancel (/mitigate) high frequency load fluctuations such as those due to, for instance, turbulence, as well as to cap the maximum power at rated flow conditions and replace active pitch control. New numerical codes specifically designed to accurately predict unsteady loadings are developed, including design codes based on blade element momentum theory (BEMT), as well as research tools such as Reynolds-averaged Navier Stokes solvers and Large Eddie Simulations.

• Current EU and NREL projects on large wind turbines
• FLOTANT - Innovative, low cost, low weight and safe floating wind technology optimized for deep water wind sites:The main objective of FLOTANT project is to develop the conceptual and basic engineering, including performance tests of the mooring and anchoring systems and the dynamic cable to improve cost-efficiency, increased flexibility and robustness to a hybrid concrete-plastic floating structure implemented for DWWF.
• Autonomous Robotic Intervention System For Extreme Maritime Environments (ARISE) Stage 2: The Autonomous Robotic Intervention System For Extreme Maritime Environments will apply artificial intelligence to result in safer and more efficient operation, maintenance and inspection of offshore assets.
• Extreme Loading on Floating Offshore Wind Turbines (FOWTs) under Complex Environmental Conditions: This project aims to fill an important gap in the design, manufacturing and testing of emerging FOWT techniques by specifically characterising extreme loading on FOWTs under complex and harsh marine environments. These are typically represented by storm conditions consisting of strong wind, extreme waves, significant current, rising sea level and complex interplay between these elements, through a coordinated campaign of both advanced CFD modelling and physical wave tank tests. This has direct relevance to the current and planned activities in the UK to develop this new technology in offshore wind.
• SURFTEC - SUrvivability and Reliability of Floating Tidal Energy Converters: Identifying and understanding extreme and fatigue loads on tidal energy converters (TEC), understanding environmental extremes (other than main resource), and determining accessibility, serviceability criteria, fault intervals and associated device life cycles, are all important factors that can determine CAPEX and OPEX cost of devices and array deployments. This project will provide a holistic vision for design optimisation to ensure, reliability and survivability for floating TECs (FTECs). Computational modeling and real sea deployment measurements will provide a tool to inform the optimum operational strategy and maximise survivability and reliability for FTEC devices and arrays.