Reliability analysis of the fatigue life of wind turbines under a non-Gaussian wind field with a full-direction inflow

Using the Hermite moment model, three types of wind fields with different probability characteristics, namely the Gaussian, hardening non-Gaussian, and softening non-Gaussian processes, were generated via the Kaimal spectrum for a typical wind turbine under operational conditions. Reliability analysis of the fatigue life of the wind turbine was performed by taking tower base connections as an example with consideration of the joint probability density distribution of the wind direction and mean wind speed. The dynamic response was calculated by an aerodynamic model of the blade and multi-body dynamics, and the time-and frequency-domain characteristics of the response were analyzed. Using linear damage accumulation theory and the Paris equation, the fatigue crack initiation life and crack growth life of the turbine were discussed in detail. Fatigue estimation shows that the crack initiation life of the turbine is more sensitive to non-Gaussian winds, whereas its crack propagation life is less sensitive to the non-Gaussian characteristics of wind load. The influence of the non-Gaussian characteristics of wind load on the fatigue damage of the wind turbine should be considered. In terms of the full-direction inflow, the failure positions of the crack initiation and propagation stages are identical and in the dominant wind direction.