Comparison of Different Driving Modes for the Wind Turbine Wake in Wind Tunnels

Bingzheng Dou,Pan Zeng,Michele Guala,Zhanpei Yang,Timing Qu,Liping Lei

doi:10.3390/en13081915

Abstract

The wake of upstream wind turbine is known to affect the operation of downstream turbines and the overall efficiency of the wind farm. Wind tunnel experiments provide relevant information for understanding and modeling the wake and its dependency on the turbine operating conditions. There are always two main driving modes to operate turbines in a wake experiment: (1) the turbine rotor is driven and controlled by a motor, defined active driving mode; (2) the rotor is driven by the incoming wind and subject to a drag torque, defined passive driving mode. The effect of the varying driving mode on the turbine wake is explored in this study. The mean wake velocities, turbulence intensities, skewness and kurtosis of the velocity time-series estimated from hot-wire anemometry data, were obtained at various downstream locations, in a uniform incoming flow wind tunnel and in an atmospheric boundary layer wind tunnel. The results show that there is not a significant difference in the mean wake velocity between these two driving modes. An acceptable agreement is observed in the comparison of wake turbulence intensity and higher-order statistics in the two wind tunnels.

Highlights

Wake effects of wind turbines can cause a significant reduction in the power output of downstream turbines [1,2,3,4,5]
A wind turbine model was employed in the uniform incoming flow (UIF) and the atmospheric boundary layer (ABL) wind tunnel, respectively, In this wind turbineunder modelvarying was employed in the(the and and the ABL
active driving mode (ADM), the rotortowas controlled by aflow servostatistics motor that ensured thedriving angularmodes speed(the reacted fast and passive driving mode (PDM)).InInthe thePDM, ADM, rotor was controlled by aadjusted servo motor ensured the angular speed reacted stably

Summary

Introduction

Wake effects of wind turbines can cause a significant reduction in the power output of downstream turbines [1,2,3,4,5]. Due to the complexity of the wake turbulence, a large number of reduced-order models [12,13,14,15] and numerical simulations [16,17] have been proposed to improve wind power plant siting and operative strategy. As a source of validation and comparison for numerical simulations, wind tunnel experiments have been performed to cover a wide range of scales and atmospheric stability conditions [18]. In a wind tunnel experiment, in order to accurately control the operating conditions, two kinds of driving mode are mostly used. The PDM is the same driving mode governing utility-scale wind turbines, but it is not ideal for a rigorous comparison with numerical simulations due to the undefined tip velocity as a boundary condition

Methods

Results

Conclusion