Print Email Facebook Twitter Enhancing Wake Mixing in Wind Farms by Multi-Sine Signals in the Helix Approach Title Enhancing Wake Mixing in Wind Farms by Multi-Sine Signals in the Helix Approach Author Huang, Louis (TU Delft Electrical Engineering, Mathematics and Computer Science) Contributor van Wingerden, J.W. (mentor) Mulders, S.P. (mentor) Bierbooms, W.A.A.M. (graduation committee) Viré, A.C. (graduation committee) Taschner, E. (graduation committee) Degree granting institution Delft University of Technology Programme Mechanical Engineering | Systems and Control Date 2022-07-08 Abstract The development of offshore wind technology has progressed rapidly since the first offshore wind farm came to birth in 1991. During the last three decades, offshore wind has become an economically attractive option of renewable energy source for many countries to fulfill their commitment to combat the climate crisis. However, an open challenge remains in offshore wind, namely the aerodynamic interactions between multiple turbines, referred to as wake effects. When the upstream turbines extract energy from wind, they generate the wake with low velocity and high turbulence level on the downstream turbines, which substantially reduces the overall wind farm performance. The annual power production loss due to wake effects is generally 10 - 40%, which limits the reduction of the levelized cost of electricity for offshore wind energy.Therefore, developing effective wind farm control strategies which could mitigate the wake effect has become an emerging research area in the past decade. Recently, a novel wind farm control strategy called the Helix approach is proposed. The Helix approach adopts the individual pitch control technique to dynamically deform the wake into the helical shape, which induces wake instability and thereby stimulates wake recovery. This control strategy has demonstrated promising potential to mitigate the wake effect and to enhance the wind farm performance. To date, the Helix approach employs single harmonic pitch signals. However, more complex and higher-harmonic signals to potentially improve the effectiveness of the Helix approach have never been explored. Therefore, the purpose of this master thesis is to explore the potential of using multi-sine pitch profiles to further enhance the wake mixing.The high-fidelity aeroelastic simulator OpenFAST with its recent free vortex wake code is adopted to simulate the dynamic wake evolution. A Fourrier stability analysis is used to quantitatively identify the wake breakdown position. According to the simulation results for the multi-sine pitch profiles, the wake breaks down at 1.75 D, which is earlier than the one at 2.50 D for the original single-sine Helix strategy. The earlier wake breakdown indicates the potential of faster wake recovery, which is required to be validated by the higher-fidelity model in the future studies. Subject wind farm controlwake effectswind energy To reference this document use: http://resolver.tudelft.nl/uuid:80a5ffcd-a32a-4a0f-bbae-b91659f168d6 Part of collection Student theses Document type master thesis Rights © 2022 Louis Huang Files PDF MScThesis_LJ_Huang_Final.pdf 17.61 MB Close viewer /islandora/object/uuid:80a5ffcd-a32a-4a0f-bbae-b91659f168d6/datastream/OBJ/view