the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 07 Jul 2021
Dynamic robust active wake control
Abstract. Active Wake Control (AWC) is a strategy for operating wind farms in a way to maximize the overall power production and/or reduce structural loading on the wind turbines. Many recent studies indicate that this technology, and more specifically the so-called wake redirection approach to AWC, have a significant potential for increasing the annual energy production by up to a few percentage points. The current state-of-the-art approach is to optimize AWC for a range of static wind conditions, which is expected to perform sub-optimally in real-life due to the continuous variations of the wind resource and the very slow yaw dynamics of the turbines. Recent work has addressed this variability in a robust design setting with the focus on maximizing the energy capture (robust AWC). This paper continues on this line of research, and develops a dynamic robust AWC strategy that aims to optimize the balance between maximum power production (requiring increased level of yawing) and minimum loads on the yaw drive (requiring limited yaw motion). It is shown with a realistic case study that the developed dynamic robust AWC can result in a large reduction of the loading on the yaw drive while at the same time improving the overall power gain, as compared to the conventional nominal AWC.
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Interactive discussion
Status: closed
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RC1: 'Comment on wes-2021-71', Bart M. Doekemeijer, 21 Jul 2021
Dear authors,
Firstly, I want to say that I very much enjoyed reading your publication. You tackle a very important topic and present multiple valuable contributions to the literature. Specifically, this paper innovates by presenting a dynamic variant of their in-house FarmFlow model, the authors present a sensitivity analysis concluding that four parameters (wind direction, wind speed, yaw error and turbulence intensity) are the most important parameters to consider in robust optimization, the authors present various guidelines for the inclusion of dynamics in wind farm controllers, and finally present a simulation study using the OWEZ offshore wind farm. Moreover, I specifically enjoyed the strong literature review, I appreciate the concept of presenting wind direction variability as being directly correlated with turbulence intensity, and very much enjoyed the strong analysis on pages 22-24. I think the scientific significance and quality are both excellent.
The feedback I have on your manuscript is limited to two major comments and then a larger number of minor comments. Not all these comments necessarily require action. Also, I am known to be direct in my reviews, so please keep in mind that these comments are purely meant to further increase the clarity and relevance of the manuscript. I hope these find you well.
Â
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RC2: 'Comment on wes-2021-71', Anonymous Referee #2, 23 Aug 2021
This was an excellent paper providing useful contributions in an area of very high interest. The paper is practical and well though through, and the case studies provide very helpful exploration of the results.
General Comments:
Section 2.1: Do I understand that wind directions variations occur in the range of 30min - 24hr, and that faster frequencies are uncorrelated spatially? If we expect a wind turbine to yaw something like several times every 10 minutes does this match?ÂCould you provide a definition of stochastic programming in general and how it is used in this work?ÂSpecific comments:ÂPage 2:Â"This conclusion is implicitly confirmed by the fact that the industry starts to develop this technology into commercial products (Siemens Gamesa Renewable Energy, 2019)."ÂCould also be that the loads are higher but not importantly so?ÂÂPage 3:ÂIn a different work, the same author demonstrates that a centralized yaw control strategy, in which information from surrounding wind turbines is used in the yaw control algorithm, can lead to a drastic reduction in the yaw duty and increase the power capture at the same time (Bossanyi, 2019).ÂThis could also be related to the concept of consensus control:Annoni, J., Bay, C., Johnson, K., Dall'Anese, E., Quon, E., Kemper, T., and Fleming, P.: Wind direction estimation using SCADA data with consensus-based optimization, Wind Energ. Sci., 4, 355–368, https://doi.org/10.5194/wes-4-355-2019, 2019.ÂThis sentence:This Kaimal spectrum is used for frequencies above 10−3 150 Hz, i.e. time scales of 30 minutes and slowerIf the range is above a frequency, do you mean lower and not slower?ÂPage 6:The parameter c(αrs) is the decay factorÂDecay of what?ÂPage 10: Recommend to explain figure 2 in more detail in the captionÂPage 13: Don't need to revise the paper, but wanted to note I think some recent papers might point to a distribution for yaw loss exponent centered somewhat higher, or even dependent on wind speed:Simley, E., Fleming, P., Girard, N., Alloin, L., Godefroy, E., and Duc, T.: Results from a Wake Steering Experiment at a Commercial Wind Plant: Investigating the Wind Speed Dependence of Wake Steering Performance, Wind Energ. Sci. Discuss. [preprint], https://doi.org/10.5194/wes-2021-61, in review, 2021.ÂPage 15Variations in the thrust curve and the yaw-induced power loss exponent have generally limited impact on the optimal yaw set-points, which suggests that they could be left out from the robust optimization.ÂThis is surprising, at least for the power curve exponent, it would seem that at some loss level it would start to have a strong impact,?ÂPage 19:ÂThe yaw set-points for the remaining turbines in the row are linearly decreased between the second turbine and the last one, which has zero yaw misalignment set-pointÂThis is a great idea! Is this novel to this paper or has it the concept been used elsewhere?ÂPage 21:ÂMetrics are really useful, the power gain per unit yaw travel increase is very interesting, is this also a novelty of this paper or something used in other papers or other contextsÂPage 23:ÂResults for hysteresis are very promising. If 4 deg is both the highest value tested and the best overall, does it suggest 5 deg or more should be considered?ÂPage 24:Having significantly less start/stop events in the reference case than with AWC might first seem couter-intuitive, but does happenDid this sentence mean to say the reverse (49% reduction)?ÂPage 28:Recommend to cite paper mentioned above on consensus controlÂÂ
Citation: https://doi.org/10.5194/wes-2021-71-RC2 -
AC1: 'Response to referee comments on wes-2021-71', Stoyan Kanev, 25 Aug 2021
Dear referees,
Many thanks for the generally positive feedback about our manuscript, and the many valuable comments and suggestions to improve the quality and clarity of the paper. Your feedback is really appreciated. We have carefully considered all your comments and, where necessary, have made changes to the manuscript accordingly.
You can find our response to each of your comments, as well as the changes made, in the supplement.Â
- EC1: 'Comment on wes-2021-71', Katherine Dykes, 26 Aug 2021
- AC2: 'Added response to EC1 on wes-2021-71', Stoyan Kanev, 27 Aug 2021
Interactive discussion
Status: closed
-
RC1: 'Comment on wes-2021-71', Bart M. Doekemeijer, 21 Jul 2021
Dear authors,
Firstly, I want to say that I very much enjoyed reading your publication. You tackle a very important topic and present multiple valuable contributions to the literature. Specifically, this paper innovates by presenting a dynamic variant of their in-house FarmFlow model, the authors present a sensitivity analysis concluding that four parameters (wind direction, wind speed, yaw error and turbulence intensity) are the most important parameters to consider in robust optimization, the authors present various guidelines for the inclusion of dynamics in wind farm controllers, and finally present a simulation study using the OWEZ offshore wind farm. Moreover, I specifically enjoyed the strong literature review, I appreciate the concept of presenting wind direction variability as being directly correlated with turbulence intensity, and very much enjoyed the strong analysis on pages 22-24. I think the scientific significance and quality are both excellent.
The feedback I have on your manuscript is limited to two major comments and then a larger number of minor comments. Not all these comments necessarily require action. Also, I am known to be direct in my reviews, so please keep in mind that these comments are purely meant to further increase the clarity and relevance of the manuscript. I hope these find you well.
Â
Â
-
RC2: 'Comment on wes-2021-71', Anonymous Referee #2, 23 Aug 2021
This was an excellent paper providing useful contributions in an area of very high interest. The paper is practical and well though through, and the case studies provide very helpful exploration of the results.
General Comments:
Section 2.1: Do I understand that wind directions variations occur in the range of 30min - 24hr, and that faster frequencies are uncorrelated spatially? If we expect a wind turbine to yaw something like several times every 10 minutes does this match?ÂCould you provide a definition of stochastic programming in general and how it is used in this work?ÂSpecific comments:ÂPage 2:Â"This conclusion is implicitly confirmed by the fact that the industry starts to develop this technology into commercial products (Siemens Gamesa Renewable Energy, 2019)."ÂCould also be that the loads are higher but not importantly so?ÂÂPage 3:ÂIn a different work, the same author demonstrates that a centralized yaw control strategy, in which information from surrounding wind turbines is used in the yaw control algorithm, can lead to a drastic reduction in the yaw duty and increase the power capture at the same time (Bossanyi, 2019).ÂThis could also be related to the concept of consensus control:Annoni, J., Bay, C., Johnson, K., Dall'Anese, E., Quon, E., Kemper, T., and Fleming, P.: Wind direction estimation using SCADA data with consensus-based optimization, Wind Energ. Sci., 4, 355–368, https://doi.org/10.5194/wes-4-355-2019, 2019.ÂThis sentence:This Kaimal spectrum is used for frequencies above 10−3 150 Hz, i.e. time scales of 30 minutes and slowerIf the range is above a frequency, do you mean lower and not slower?ÂPage 6:The parameter c(αrs) is the decay factorÂDecay of what?ÂPage 10: Recommend to explain figure 2 in more detail in the captionÂPage 13: Don't need to revise the paper, but wanted to note I think some recent papers might point to a distribution for yaw loss exponent centered somewhat higher, or even dependent on wind speed:Simley, E., Fleming, P., Girard, N., Alloin, L., Godefroy, E., and Duc, T.: Results from a Wake Steering Experiment at a Commercial Wind Plant: Investigating the Wind Speed Dependence of Wake Steering Performance, Wind Energ. Sci. Discuss. [preprint], https://doi.org/10.5194/wes-2021-61, in review, 2021.ÂPage 15Variations in the thrust curve and the yaw-induced power loss exponent have generally limited impact on the optimal yaw set-points, which suggests that they could be left out from the robust optimization.ÂThis is surprising, at least for the power curve exponent, it would seem that at some loss level it would start to have a strong impact,?ÂPage 19:ÂThe yaw set-points for the remaining turbines in the row are linearly decreased between the second turbine and the last one, which has zero yaw misalignment set-pointÂThis is a great idea! Is this novel to this paper or has it the concept been used elsewhere?ÂPage 21:ÂMetrics are really useful, the power gain per unit yaw travel increase is very interesting, is this also a novelty of this paper or something used in other papers or other contextsÂPage 23:ÂResults for hysteresis are very promising. If 4 deg is both the highest value tested and the best overall, does it suggest 5 deg or more should be considered?ÂPage 24:Having significantly less start/stop events in the reference case than with AWC might first seem couter-intuitive, but does happenDid this sentence mean to say the reverse (49% reduction)?ÂPage 28:Recommend to cite paper mentioned above on consensus controlÂÂ
Citation: https://doi.org/10.5194/wes-2021-71-RC2 -
AC1: 'Response to referee comments on wes-2021-71', Stoyan Kanev, 25 Aug 2021
Dear referees,
Many thanks for the generally positive feedback about our manuscript, and the many valuable comments and suggestions to improve the quality and clarity of the paper. Your feedback is really appreciated. We have carefully considered all your comments and, where necessary, have made changes to the manuscript accordingly.
You can find our response to each of your comments, as well as the changes made, in the supplement.Â
- EC1: 'Comment on wes-2021-71', Katherine Dykes, 26 Aug 2021
- AC2: 'Added response to EC1 on wes-2021-71', Stoyan Kanev, 27 Aug 2021
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