Enhancing Wake Mixing in Wind Farms by Multi-Sine Signals in the Helix Approach

Research output: Chapter in Book/Conference proceedings/Edited volumeConference contributionScientificpeer-review


In most current offshore wind farms, the turbines are controlled greedily, neglecting any coupling by wake effects with other turbines. By neglecting these effects of aerodynamic interactions, the power production performance is substantially reduced. Besides the well-known wake steering and dynamic induction control wake control strategies, a novel wind farm flow control strategy called the Helix approach has been recently proposed to mitigate the impacts of wake effects and optimize wind farm performance. The Helix approach adopts the individual pitch control (IPC) technique to dynamically deform the wake into the helical shape, which induces wake instability and thereby stimulates wake recovery. The first results employing a single-harmonic signal have demonstrated promising enhancement in wake recovery effects. However, more complex signals to potentially improve the effectiveness of the Helix approach have never been studied. This paper explores the potential of using higher-harmonic signals in the Helix approach to further enhance wake mixing. The aeroelastic simulator, OpenFAST, with its recently developed free vortex wake codes is adopted to simulate the dynamic wake evolution. A Fourier stability analysis is used to quantitatively identify the wake breakdown position. Results show that in the baseline case where no Helix signals are implemented, the wake breaks down at 3.25 rotor diameter (D) from the rotor. When using the designed multi-sine Helix signals, the wake breaks down at 1.75 D from the rotor, which is a significant improvement over the breakdown distance at 2.50 D using the conventional single-sine Helix. The earlier wake breakdown indicates faster wake recovery and is to be validated by future higher-fidelity simulation studies.
Original languageEnglish
Title of host publicationProceedings 2023 American Control Conference (ACC)
ISBN (Print)979-8-3503-2806-6
Publication statusPublished - 2023
EventAmerican Control Conference, ACC 2023 - San Diego, United States
Duration: 31 May 20232 Jun 2023


ConferenceAmerican Control Conference, ACC 2023
Country/TerritoryUnited States
CitySan Diego

Bibliographical note

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Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.


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