Load and response analysis of the IEA 22 MW monopile wind turbine considering marine atmospheric turbulence characteristics

Since 2020, offshore wind turbine prototypes have experienced a substantial increase in size. At the same time, wind turbine design standards have not specified requirements for marine atmospheric turbulence. The impact of marine atmospheric turbulence characteristics on the load and response (LaR) of large wind turbines has not been fully studied. This paper compares and evaluates the LaR of the IEA 22 MW bottom-fixed turbine under three turbulence conditions: the marine atmospheric turbulence model by Syed and Mann, with turbulence intensity statistics from the FINO1 platform; the IEC-recommended Mann turbulence spectra with FINO1 platform turbulence intensity; and the Mann turbulence spectra with IEC class C turbulence intensity. The latter configuration is widely used by manufacturers for offshore turbines. We derive and analyze the blade-averaged and rotor-averaged wind speeds, accounting for rotational effects. We then perform statistical, fatigue, and spectral analyses at different mean wind speeds using OpenFAST with the BeamDyn module. We observe that the differences in LaR spectra are consistent with the differences in the blade-averaged and rotor-averaged wind speed spectra. For the same turbulence intensity, the Syed–Mann turbulence model leads to a significant increase in the damage-equivalent fatigue loads of the low-speed shaft below rated wind speeds, by more than 20%. The results obtained using the IEC class C standard are noticeably higher due to its conservatively higher turbulence intensity level.