The Impact of Wind Shear and Turbulence on the Loads and Performance of Wind Turbines

Abstract

Operating in real-world conditions, modern large capacity wind turbines often experience off-design situations, enduring dynamic loads characterized by complex unsteady aerodynamics. Key among the challenges in predicting these dynamic loads is understanding the effects of wind shear and turbulence, both individually and in their complex interplay. This research aims to shed light on these phenomena, with an emphasis on their impacts on wind turbine fatigue loads and power production.

The research first provides an in-depth analysis of the influence of atmospheric stability on wind shear profile, aiming to extend the wind shear profile beyond the range of LiDAR measurements. Recognizing the limitations of existing power law and logarithmic law extrapolation methods, the study validates the use of multiple stability correction functions for accurate wind speed extrapolation. Subsequently, the research delves into the intricate effects of wind shear and turbulence on fatigue loads at the blade root of wind turbines, leveraging aeroelastic simulations. This research addresses the challenge of assessing wind turbine suitability for sites where one or several wind climate parameters surpass their design class values. It investigates the potential of the Response Surface Methodology (RSM) to estimate site-specific fatigue loads, a process that conventionally requires extensive aeroelastic simulations. This research also extends the scope to include the assessment of site-specific wind turbine power curves, validating the use of the Rotor Equivalent Wind Speed (REWS) and turbulence renormalization methods. Both methods show promise in estimating site-specific wind turbine power curves using a power curve measured under varying wind conditions.

In essence, this study emphasizes the significant impact of wind shear and turbulence on the performance and longevity of wind turbines. By shedding the light on potential improvements, this study hopes to contribute towards accurate power output and fatigue load assessments.