Wake redirection at higher axial induction

Cossu, Carlo

doi:10.5194/wes-2020-111

Cited by 2 publications

(1 citation statement)

References 25 publications

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“…Within the limitations of the simulations, these results suggest that operating an upstream turbine at a small derate and maximized thrust could increase the total power of it and a downstream turbine by over 10% of a Baseline, conventional, operation with streamwise turbine spacing of about 4D to at least 6D. While many previous studies have identified minimum thrust as the optimal method (Mirzaei et al, 2015;Pedersen and Larsen, 2020;Schaak, 2006;Vitulli et al, 2019), several have also found that overinduction (increasing thrust) produces higher total power than underinduction Meyers, 2016, 2018;Cossu, 2021;Dilip and Porté-Agel, 2017). The latter studies, however, use very different methods both in the details of the derating and the simulations so it is difficult to compare their results to these.…”

Section: Discussionmentioning

confidence: 94%

Mid-fidelity simulations and comparisons of five techniques for axial induction control of a wind turbine

Houck

Maniaci

Kelley

2021

Preprint

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Abstract. As wind turbines are more frequently placed in arrays, the need to understand and mitigate problems arising from their wakes has increased. When downstream turbines are in the wakes of upstream ones, the downstream turbines produce less power, require more maintenance, and have shorter lifetimes. One wake mitigation technique is known as axial induction control (AIC) and it involves derating (operating suboptimally) upstream turbines such that more energy remains in their wakes for downstream turbines to harvest. While there has been considerable research on this technique, much of it has suffered from a misunderstanding of the most important parameters in optimizing AIC. As such, the research has been largely inconclusive. Herein, we seek to rectify several perceived shortcomings of previous work by using mid-fidelity simulations to compare five different techniques for AIC at three different derate percentages against a baseline case and examining the recovery of the wake. We find that only the case with the lowest derate, 10 %, and using maximum thrust exceeds the baseline when estimating the combined power of the simulated turbine and a virtual turbine five diameters downstream and that it produced 10 % more power. Furthermore, these results help to validate previous work that concluded that the excess energy that is in the wake of a derated turbine will be at the edges of the wake unless the wake can sufficiently recover before the next downstream turbine. Finally, all together this suggests that the precise combination of derate percentage and the method used to derate turbines (i.e., the precise combination of pitch and torque controls), as well as the spacing and arrangement of turbines, must all be considered when optimizing AIC, and that substantial power gains may be possible.

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Section: Discussionmentioning

confidence: 94%

Mid-fidelity simulations and comparisons of five techniques for axial induction control of a wind turbine

Houck

Maniaci

Kelley

2021

Preprint

View full text Add to dashboard Cite

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Review of wake management techniques for wind turbines

Houck

2021

Wind Energy

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Summary The progression of wind turbine technology has led to wind turbines being incredibly optimized machines often approaching their theoretical maximum production capabilities. When placed together in arrays to make wind farms, however, they are subject to wake interference that greatly reduces downstream turbines' power production, increases structural loading and maintenance, reduces their lifetimes, and ultimately increases the levelized cost of energy. Development of techniques to manage wakes and operate larger and larger arrays of turbines more efficiently is now a crucial field of research. Herein, four wake management techniques in various states of development are reviewed. These include axial induction control, wake steering, the latter two combined, and active wake control. Each of these is reviewed in terms of its control strategies and use for power maximization, load reduction, and ancillary services. By evaluating existing research, several directions for future research are suggested.

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Wake redirection at higher axial induction

Cited by 2 publications

References 25 publications

Mid-fidelity simulations and comparisons of five techniques for axial induction control of a wind turbine

Mid-fidelity simulations and comparisons of five techniques for axial induction control of a wind turbine

Review of wake management techniques for wind turbines

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