Effect of Turbulence on Power for Bend-Twist Coupled Blades

The Science of Making Torque from Wind

Stäblein, Alexander R.^1 ; Hansen, Morten H.^1

Technical University of Denmark, Department of Wind Energy, Frederiksborgvej 399, Roskilde

4000, Denmark^1

关键词: Annual energy productions;    Bend-twist coupling;    Controller switching;    Linearized models;    Standard deviation;    Steady-state power;    Weighted average method;    Wind turbine blades;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/753/4/042018/pdf
DOI  :  10.1088/1742-6596/753/4/042018

来源: IOP

【 摘 要 】

Bend-twist coupling of wind turbine blades reduces the structural loads of the turbine but it also results in a decrease of the annual energy production. The main part of the power loss can be mitigated by pretwisting the blade, but some power loss remains and previous studies indicate that it might be related to the dynamic response of bend-twist coupled blades in turbulent flow. This paper contains estimations of the power curve from nonlinear time simulations, a linear frequency domain based method and a normal distribution weighted average method. It is shown that the frequency domain based estimation is highly dependant on the validity of the linearized model, thus estimations are poor for operational points close to rated wind speed. The weighted average method gives good results if an appropriate standard deviation is known a priori. The nonlinear time simulations show that changes in power due to turbulence are similar for coupled and uncoupled blades. Power gains at low wind speeds are related to the curvature of the steady state power curve. Losses around rated wind speed are caused by the effects of controller switching between partial and full power operation.