Challenge
Currently the wind energy industry is designing wind turbines and wind farms based on wind models which were developed some decades ago for much smaller wind turbines than those built today. Large variations (20-30%) are seen in the fatigue loads used for the design of wind turbines and wind farms due to the different methods used for the establishment of the turbulent wind field. Unlike currently available turbulence models, which have limited validation by measurements and have been developed focusing on relatively small wind turbines, the validation of new turbulence models will focus on model validation based on large spatial dimensions and will thus provide a much more reliable basis for the design of wind turbines.
Development
DNV brings wind industry leaders together in a Joint Industry Project “Validation of Turbulence Models” where a new best practice will be developed to improve the design of modern wind turbines and wind farms that will lead to cost reductions.
During the first phase existing wind measurements from over 30 sites were collected and are now analysed. These will be used to validate and improve parameters and models used to describe wind turbulence during design, site assessment and verification of wind turbines or farms. The results will allow consideration of differences between onshore and offshore conditions and the effect of coastal influence. The effect of the turbulence parameters on turbine loading at different sites will be investigated for today’s large wind turbine designs.
The methodology will consider and comply with the requirements as stipulated in the DNV standard DNVGL-ST-0437 “Loads and site conditions wind for turbines”, and in the latest drafts of IEC 61400-1 and IEC 61400-3.
Benefits
The results of the Joint Industry Project will be input to DNV Recommended Practices and DNV Standards with the aim to reduce uncertainties in the character of turbulence and thus fatigue and extreme loading of wind turbines.
