Abstract
Abstract. Renewed interest in yaw control for wind turbine and power plants for wake redirection and load mitigation demands a clear understanding of the effects of running with skewed inflow. In this paper, we investigate the physics of yawed operations, building up the complexity from a simplified analytical treatment to more complex aeroelastic simulations. Results in terms of damage equivalent loads (DELs) and extreme loads under misaligned conditions of operation are compared to data collected from an instrumented, utility-scale wind turbine. The analysis shows that multiple factors are responsible for the DELs of the various components and that airfoil aerodynamics, elastic characteristics of the rotor, and turbulence intensities are the primary drivers. Both fatigue and extreme loads are observed to have relatively complex trends with yaw offsets, which can change depending on the wind-speed regime. Good agreement is found between predicted and measured trends for both fatigue and ultimate loads.
Highlights
Despite numerous studies on the skewed inflow and wake of wind turbines (e.g., Hand et al, 2001; Schepers, 2004, 2012; Schreck and Schepers, 2014; Fleming et al, 2015), uncertainties still remain on the loading effects experienced by their mechanical components under misaligned operation
Our analysis was focused on the General Electric (GE) 1.5sle 1.5 MW wind turbine (GEWT) (Mendoza et al, 2015) installed at the National Wind Technology Center (NWTC), which is owned by the U.S Department of Energy (DOE) and operated by the National Renewable Energy Laboratory (NREL)
The results of models of increasing complexity were presented for the rotor aerodynamics under different yaw misalignments to shed some light on the physics and load predictions
Summary
Despite numerous studies on the skewed inflow and wake of wind turbines (e.g., Hand et al, 2001; Schepers, 2004, 2012; Schreck and Schepers, 2014; Fleming et al, 2015), uncertainties still remain on the loading effects experienced by their mechanical components under misaligned operation. Whereas new interest is directed at maximizing plant power performance via wake steering and yaw control (e.g., Gebraad et al, 2016), understanding and managing their effects on operation and maintenance (O&M) costs are critical for the success of the strategy.
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