A simulation study demonstrating the importance of large-scale trailing vortices in wake steering

Abstract. In this paper, we investigate the role of flow structures generated in wind farm control through yaw misalignment. A pair of counter-rotating vortices is shown to be important in deforming the shape of the wake and in explaining the asymmetry of wake steering in oppositely signed yaw angles. We also demonstrate that vortices generated by an upstream turbine that is performing wake steering can deflect wakes of downstream turbines, even if they are themselves aligned. We encourage the development of improvements to control-oriented engineering models of wind farm control, to include the effects of these large-scale flow structures. Such a new model would improve the predictability of control-oriented models. Further, we demonstrate that the vortex structures created in wake steering can lead to greater impact on power generation than currently modeled in control-oriented models. We propose that wind farm controllers can be made more effective if designed to take advantage of these effects.

[1]  Stefano Leonardi,et al.  Large eddy simulations of the flow past wind turbines: actuator line and disk modeling , 2015 .

[2]  Jennifer Annoni,et al.  Analysis of control-oriented wake modeling tools using lidar field results , 2018, Wind Energy Science.

[3]  L. Machielse,et al.  Controlling Wind in ECN`s Scaled Wind Farm , 2012 .

[4]  Ewan Machefaux,et al.  Multiple Turbine Wakes , 2015 .

[5]  Jan-Åke Dahlberg,et al.  Potential improvement of wind turbine array efficiency by active wake control (AWC) , 2003 .

[6]  Stefano Leonardi,et al.  A large-eddy simulation of wind-plant aerodynamics , 2012 .

[7]  Davide Trabucchi,et al.  3-D shear-layer model for the simulation of multiple wind turbine wakes: description and first assessment , 2017 .

[8]  Jason R. Marden,et al.  Wind plant power optimization through yaw control using a parametric model for wake effects—a CFD simulation study , 2016 .

[9]  Jennifer Annoni,et al.  Analysis of axial‐induction‐based wind plant control using an engineering and a high‐order wind plant model , 2016 .

[10]  Michael Hölling,et al.  Comparative study on the wake deflection behind yawed wind turbine models , 2017 .

[11]  F. Porté-Agel,et al.  Experimental and theoretical study of wind turbine wakes in yawed conditions , 2016, Journal of Fluid Mechanics.

[12]  Martin Kühn,et al.  Estimating the wake deflection downstream of a wind turbine in different atmospheric stabilities: an LES study , 2016 .

[13]  Jennifer Annoni,et al.  Field test of wake steering at an offshore wind farm , 2017 .

[14]  Johan Meyers,et al.  Wake structure in actuator disk models of wind turbines in yaw under uniform inflow conditions , 2016 .

[15]  F. Porté-Agel,et al.  A new analytical model for wind-turbine wakes , 2013 .

[16]  Jan Bartl,et al.  Experimental testing of wind turbine wake control methods , 2018 .

[17]  Fernando Porté-Agel,et al.  Large-eddy simulation of atmospheric boundary layer flow through wind turbines and wind farms , 2011 .

[18]  J. Højstrup,et al.  A Simple Model for Cluster Efficiency , 1987 .

[19]  J. Jonkman,et al.  Definition of a 5-MW Reference Wind Turbine for Offshore System Development , 2009 .

[20]  Fernando Porté-Agel,et al.  A new analytical model for wind farm power prediction , 2015 .

[21]  N. Jensen.  A note on wind generator interaction , 1983 .

[22]  E. Migoya,et al.  Application of a LES technique to characterize the wake deflection of a wind turbine in yaw , 2009 .

[23]  Andrew Ning,et al.  Maximization of the annual energy production of wind power plants by optimization of layout and yaw‐based wake control , 2017 .

[24]  Henrik Alfredsson,et al.  Measurements on a wind turbine wake: 3D effects and bluff body vortex shedding , 2006 .

[25]  Kathryn E. Johnson,et al.  Simulation comparison of wake mitigation control strategies for a two‐turbine case , 2015 .

[26]  Jennifer Annoni,et al.  Full-Scale Field Test of Wake Steering , 2017 .