Abstract. In order to design vortex generators for modern multi-megawatt wind turbines accurately, the 3D behaviour of the boundary layer has to be considered. Due to the rotation of the blade, the lift-enhancing rotational augmentation has a considerable impact, especially in the inner blade sections. To investigate the interaction of vortex generators and rotational augmentation, high-fidelity computational flow simulations by means of unsteady Reynolds-averaged Navier–Stokes methods are presented for a rotating blade of a generic 2 MW horizontal-axis wind turbine. The inner blade section is analysed with and without vortex generators for two different pitch settings, including one causing largely separated flow. Two ways of placing the vortex generators on the blade with different radial starting positions are investigated in order to find out if the coexistence of the two lift-enhancement methods (i.e. rotational augmentation and vortex generators) is beneficial. All simulations are performed with the flow solver FLOWer, and the vortex generators are modelled by the introduction of source terms into the computational domain through a so-called BAY (Bender–Anderson–Yagle)-type model. For the case without vortex generators, it is found that the strength of rotational augmentation largely depends on the effective angles of attack (i.e. the pitch setting). For the case with lower effective angles of attack, rotational augmentation is a cyclic phenomenon, whereas for the case with higher effective angles of attack, it generates large loads in the inner root section due to a constant centrifugal pumping mechanism in time. The results from the cases with vortex generators display a rather destructive interaction of vortex generators and rotational augmentation on the torque. For low effective angles of attack and thus attached flow conditions, vortex generators exhibit slight losses compared to the case without vortex generators, as they inhibit spanwise flow through rotational augmentation. For high effective angles of attack, the vortex generators placed over 30 % of the blade produce an increase of 3.28 % in torque compared to the case without vortex generators and high centrifugal pumping.
{"title":"Numerical study of the unsteady blade root aerodynamics of a 2 MW wind turbine equipped with vortex generators","authors":"F. Seel, T. Lutz, E. Krämer","doi":"10.5194/wes-8-1369-2023","DOIUrl":"https://doi.org/10.5194/wes-8-1369-2023","url":null,"abstract":"Abstract. In order to design vortex generators for modern multi-megawatt wind turbines accurately, the 3D behaviour of the boundary layer has to be considered. Due to the rotation of the blade, the lift-enhancing rotational augmentation has a considerable impact, especially in the inner blade sections.\u0000To investigate the interaction of vortex generators and rotational augmentation, high-fidelity computational flow simulations by means of unsteady Reynolds-averaged Navier–Stokes methods are presented for a rotating blade of a generic 2 MW horizontal-axis wind turbine.\u0000The inner blade section is analysed with and without vortex generators for two different pitch settings, including one causing largely separated flow. Two ways of placing the vortex generators on the blade with different radial starting positions are investigated in order to find out if the coexistence of the two lift-enhancement methods (i.e. rotational augmentation and vortex generators) is beneficial. All simulations are performed with the flow solver FLOWer, and the vortex generators are modelled by the introduction of source terms into the computational domain through a so-called BAY (Bender–Anderson–Yagle)-type model.\u0000For the case without vortex generators, it is found that the strength of rotational augmentation largely depends on the effective angles of attack (i.e. the pitch setting). For the case with lower effective angles of attack, rotational augmentation is a cyclic phenomenon, whereas for the case with higher effective angles of attack, it generates large loads in the inner root section due to a constant centrifugal pumping mechanism in time.\u0000The results from the cases with vortex generators display a rather destructive interaction of vortex generators and rotational augmentation on the torque. For low effective angles of attack and thus attached flow conditions, vortex generators exhibit slight losses compared to the case without vortex generators, as they inhibit spanwise flow through rotational augmentation. For high effective angles of attack, the vortex generators placed over 30 % of the blade produce an increase of 3.28 % in torque compared to the case without vortex generators and high centrifugal pumping.\u0000","PeriodicalId":46540,"journal":{"name":"Wind Energy Science","volume":null,"pages":null},"PeriodicalIF":4.0,"publicationDate":"2023-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48614656","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Fontanella, Elio Daka, Felipe Novais, M. Belloli
Abstract. Aerodynamic-load calculation in aero-hydro-servo-elastic modeling tools has been recently validated against experiments for low-frequency platform motions but without considering the capability of active wind turbine controls. This work presents a control design framework that allows for including industry-standard wind turbine control functionalities in a model-scale rotor and its application to a 1:100 scaled version of the International Energy Agency (IEA) 15 MW turbine. Wind tunnel tests with a fixed foundation and steady wind show the scaled turbine reproduces the steady-state rotor speed–blade pitch–thrust–torque characteristics of the IEA 15 MW turbine, confirming the controller design method. Tests with a prescribed platform pitch motion are carried out to assess the turbine response and controller modeling in conditions representative of the normal operation of floating wind turbines. The blade element momentum model of OpenFAST is verified against the experiment, showing aerodynamic thrust and torque are predicted with higher accuracy in the below-rated than the above-rated region: in our simulation, the decrease in thrust oscillation amplitude due to blade pitch actuation is underpredicted. This, combined with uncertainty in modeling the blade pitch actuators, complicates the numerical–experimental simulation of the turbine aerodynamic response in above-rated operation.
{"title":"Controller design for model-scale rotors and validation using prescribed motion","authors":"A. Fontanella, Elio Daka, Felipe Novais, M. Belloli","doi":"10.5194/wes-8-1351-2023","DOIUrl":"https://doi.org/10.5194/wes-8-1351-2023","url":null,"abstract":"Abstract. Aerodynamic-load calculation in aero-hydro-servo-elastic modeling tools has been recently validated against experiments for low-frequency platform motions but without considering the capability of active wind turbine controls. This work presents a control design framework that allows for including industry-standard wind turbine control functionalities in a model-scale rotor and its application to a 1:100 scaled version of the International Energy Agency (IEA) 15 MW turbine. Wind tunnel tests with a fixed foundation and steady wind show the scaled turbine reproduces the steady-state rotor speed–blade pitch–thrust–torque characteristics of the IEA 15 MW turbine, confirming the controller design method. Tests with a prescribed platform pitch motion are carried out to assess the turbine response and controller modeling in conditions representative of the normal operation of floating wind turbines. The blade element momentum model of OpenFAST is verified against the experiment, showing aerodynamic thrust and torque are predicted with higher accuracy in the below-rated than the above-rated region: in our simulation, the decrease in thrust oscillation amplitude due to blade pitch actuation is underpredicted. This, combined with uncertainty in modeling the blade pitch actuators, complicates the numerical–experimental simulation of the turbine aerodynamic response in above-rated operation.\u0000","PeriodicalId":46540,"journal":{"name":"Wind Energy Science","volume":null,"pages":null},"PeriodicalIF":4.0,"publicationDate":"2023-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47839325","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract. Layout design and wake steering through wind plant control are important and complex components in the design and operation of modern wind power plants. They are currently optimized separately, but with more and more computational and experimental studies demonstrating the gains possible through wake steering, there is a growing need from industry and regulating bodies to combine the layout and control optimization in a co-design process. However, combining these two optimization problems is currently infeasible due to the excessive number of design variables and large solution space. In this article, we present a method that enables the coupled optimization of wind power plant layout and wake steering with no additional computational expense than a traditional layout optimization. We developed a geometric relationship between wind turbines to find an approximate optimal yaw angle, bypassing the need for either a nested or coupled wind plant control optimization. It also provides a significant and immediate improvement to wind power plant design by enabling the co-design of turbine layout and yaw control for wake steering. A small co-designed plant shown in this article produces 0.8 % more energy than its sequentially designed counterpart. This additional energy production comes with no additional infrastructure, turbine hardware, or control software; it is simply the outcome of optimizing the turbine layout and yaw control together, resulting in millions of dollars of additional revenue for the wind power plants of the future.
{"title":"Enabling control co-design of the next generation of wind power plants","authors":"A. Stanley, C. Bay, P. Fleming","doi":"10.5194/wes-8-1341-2023","DOIUrl":"https://doi.org/10.5194/wes-8-1341-2023","url":null,"abstract":"Abstract. Layout design and wake steering through wind plant control are important and complex components in the design and operation of modern wind power plants. They are currently optimized separately, but with more and more computational and experimental studies demonstrating the gains possible through wake steering, there is a growing need from industry and regulating bodies to combine the layout and control optimization in a co-design process.\u0000However, combining these two optimization problems is currently infeasible due to the excessive number of design variables and large solution space.\u0000In this article, we present a method that enables the coupled optimization of wind power plant layout and wake steering with no additional computational expense than a traditional layout optimization.\u0000We developed a geometric relationship between wind turbines to find an approximate optimal yaw angle, bypassing the need for either a nested or coupled wind plant control optimization.\u0000It also provides a significant and immediate improvement to wind power plant design by enabling the co-design of turbine layout and yaw control for wake steering. A small co-designed plant shown in this article produces 0.8 % more energy than its sequentially designed counterpart.\u0000This additional energy production comes with no additional infrastructure, turbine hardware, or control software; it is simply the outcome of optimizing the turbine layout and yaw control together, resulting in millions of dollars of additional revenue for the wind power plants of the future.\u0000","PeriodicalId":46540,"journal":{"name":"Wind Energy Science","volume":null,"pages":null},"PeriodicalIF":4.0,"publicationDate":"2023-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42250217","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract. We assess the performance of two control strategies on the IEA 15 MW reference floating wind turbine through OpenFAST simulations. The multivariable feedback (MVFB) control tuned by the toolbox of the Reference OpenSource Controller (ROSCO) is considered to be a benchmark for comparison. We then tune the feedback gains for the multivariable control, considering two cases: with and without lidar-assisted feedforward control. The tuning process is performed using OpenFAST simulations, considering realistic offshore turbulence spectral parameters. We reveal that optimally tuned controls are robust to changes in turbulence parameters caused by atmospheric stability variations. The two optimally tuned control strategies are then assessed using the design load case 1.2 specified by the IEC 61400 standard. Compared with the baseline multivariable feedback control, the one with optimal tuning significantly reduced the tower damage equivalent load, leading to a lifetime extension of 19.7 years with the assumption that the lifetime fatigue is only caused by the design load case 1.2. With the assistance of feedforward control realized using a typical four-beam lidar, compared with the optimally tuned MVFB control, the lifetime of the tower can be further extended by 4.6 years.
{"title":"Assessing lidar-assisted feedforward and multivariable feedback controls for large floating wind turbines","authors":"F. Guo, D. Schlipf","doi":"10.5194/wes-8-1299-2023","DOIUrl":"https://doi.org/10.5194/wes-8-1299-2023","url":null,"abstract":"Abstract. We assess the performance of two control strategies on the IEA 15 MW reference floating wind turbine through OpenFAST simulations. The multivariable feedback (MVFB) control tuned by the toolbox of the Reference OpenSource Controller (ROSCO) is considered to be a benchmark for comparison. We then tune the feedback gains for the multivariable control, considering two cases: with and without lidar-assisted feedforward control. The tuning process is performed using OpenFAST simulations, considering realistic offshore turbulence spectral parameters. We reveal that optimally tuned controls are robust to changes in turbulence parameters caused by atmospheric stability variations. The two optimally tuned control strategies are then assessed using the design load case 1.2 specified by the IEC 61400 standard. Compared with the baseline multivariable feedback control, the one with optimal tuning significantly reduced the tower damage equivalent load, leading to a lifetime extension of 19.7 years with the assumption that the lifetime fatigue is only caused by the design load case 1.2. With the assistance of feedforward control realized using a typical four-beam lidar, compared with the optimally tuned MVFB control, the lifetime of the tower can be further extended by 4.6 years.\u0000","PeriodicalId":46540,"journal":{"name":"Wind Energy Science","volume":null,"pages":null},"PeriodicalIF":4.0,"publicationDate":"2023-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42981399","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract. In this paper, the coupled dynamics of the floating platform and the wind turbine rotor are analyzed. In particular, the damping is explicitly derived from the coupled equations of the rotor and floating platform. The analysis of the damping leads to the study of instability phenomena, thus obtaining the explicit conditions that lead to the non-minimum phase zero (NMPZ). Two NMPZs are analyzed, one related to the rotor dynamics and the other one to the platform pitch dynamics. The latter introduces a novelty, and an explicit condition is provided in this work for its verification. In the second part of the paper, from the analysis of the damping of the floating platform, a new strategy for the control of floating offshore wind turbines (FOWTs) is proposed. This strategy allows one to impose on the controller an explicit level of damping in the platform pitch motion that adapts with wind speed and operating conditions without changing the period of platform pitching. Finally the new strategy is compared to one without compensation and one with a non-adapting compensation by performing aero-hydro-servo-elastic numerical simulations of a reference FOWT. Generated power, motions, blade pitch and tower base fatigue are compared, showing that the new control strategy can reduce fatigue in the structure without affecting the power production.
{"title":"Damping analysis of floating offshore wind turbines (FOWTs): a new control strategy reducing the platform vibrations","authors":"Matteo Capaldo, Paul Mella","doi":"10.5194/wes-8-1319-2023","DOIUrl":"https://doi.org/10.5194/wes-8-1319-2023","url":null,"abstract":"Abstract. In this paper, the coupled dynamics of the floating platform and the wind turbine rotor are analyzed. In particular, the damping is explicitly derived from the coupled equations of the rotor and floating platform. The analysis of the damping leads to the study of instability phenomena, thus obtaining the explicit conditions that lead to the non-minimum phase zero (NMPZ). Two NMPZs are analyzed, one related to the rotor dynamics and the other one to the platform pitch dynamics. The latter introduces a novelty, and an explicit condition is provided in this work for its verification. In the second part of the paper, from the analysis of the damping of the floating platform, a new strategy for the control of floating offshore wind turbines (FOWTs) is proposed. This strategy allows one to impose on the controller an explicit level of damping in the platform pitch motion that adapts with wind speed and operating conditions without changing the period of platform pitching. Finally the new strategy is compared to one without compensation and one with a non-adapting compensation by performing aero-hydro-servo-elastic numerical simulations of a reference FOWT. Generated power, motions, blade pitch and tower base fatigue are compared, showing that the new control strategy can reduce fatigue in the structure without affecting the power production.","PeriodicalId":46540,"journal":{"name":"Wind Energy Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135464722","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract. The two-parameter Weibull distribution has garnered much attention in the assessment of wind energy potential. The estimation of the shape and scale parameters of the distribution has brought forth a successful tool for the wind energy industry. However, it may be inappropriate to use the two-parameter Weibull distribution to assess energy at every location, especially at sites where low wind speeds are frequent, such as in tropical regions. In this work, a robust technique for wind resource assessment using a Bayesian approach for estimating Weibull parameters is first proposed. Secondly, the wind resource assessment techniques using a two-parameter Weibull distribution and a three-parameter Weibull distribution, which is a generalized form of two-parameter Weibull distribution, are compared. Simulation studies confirm that the Bayesian approach seems a more robust technique for accurate estimation of Weibull parameters. The research is conducted using data from seven sites in the tropical region from 1∘ N of the Equator to 21∘ S of the Equator. Results reveal that a three-parameter Weibull distribution with a non-zero shift parameter is a better fit for the wind data with a higher percentage of low wind speeds (0–1 m s−1) and low skewness. However, wind data with a smaller percentage of low wind speeds and high skewness showed better results with a two-parameter distribution that is a special case of the three-parameter Weibull distribution with a zero shift parameter. The proposed distribution can be incorporated into commercial software like WAsP to improve the accuracy of wind resource assessments. The results also demonstrate that the proposed Bayesian approach and application of a three-parameter Weibull distribution are extremely useful for accurate estimation of wind power density.
摘要双参数威布尔分布在风能潜力评价中受到广泛关注。对分布的形状和尺度参数的估计为风能工业提供了一个成功的工具。然而，使用双参数威布尔分布来评估每个地点的能量可能是不合适的，特别是在低风速频繁的地点，如热带地区。在这项工作中，首次提出了一种使用贝叶斯方法估计威布尔参数的风力资源评估技术。其次，比较了双参数威布尔分布和广义的三参数威布尔分布的风力资源评价技术。仿真研究证实，贝叶斯方法对于精确估计威布尔参数似乎是一种更可靠的技术。这项研究使用了从赤道1°N到赤道21°S的热带地区7个地点的数据。结果表明，对于低风速(0-1 m s−1)和低偏度的风数据，具有非零偏移参数的三参数威布尔分布更适合。然而，低风速和高偏度比例较小的风数据在双参数分布中显示出更好的结果，这是具有零移位参数的三参数威布尔分布的特殊情况。提议的分布可以被整合到像WAsP这样的商业软件中，以提高风能资源评估的准确性。结果还表明，所提出的贝叶斯方法和三参数威布尔分布的应用对于准确估计风力密度非常有用。
{"title":"Bayesian method for estimating Weibull parameters for wind resource assessment in a tropical region: a comparison between two-parameter and three-parameter Weibull distributions","authors":"Mohammad G.M. Khan, M. R. Ahmed","doi":"10.5194/wes-8-1277-2023","DOIUrl":"https://doi.org/10.5194/wes-8-1277-2023","url":null,"abstract":"Abstract. The two-parameter Weibull distribution has garnered much attention\u0000in the assessment of wind energy potential. The estimation of the shape and\u0000scale parameters of the distribution has brought forth a successful tool for\u0000the wind energy industry. However, it may be inappropriate to use the\u0000two-parameter Weibull distribution to assess energy at every location,\u0000especially at sites where low wind speeds are frequent, such as in tropical\u0000regions. In this work, a robust technique for wind resource assessment using\u0000a Bayesian approach for estimating Weibull parameters is first proposed.\u0000Secondly, the wind resource assessment techniques using a two-parameter\u0000Weibull distribution and a three-parameter Weibull distribution, which is a\u0000generalized form of two-parameter Weibull distribution, are compared.\u0000Simulation studies confirm that the Bayesian approach seems a more robust\u0000technique for accurate estimation of Weibull parameters. The research is\u0000conducted using data from seven sites in the tropical region from 1∘ N of\u0000the Equator to 21∘ S of the Equator. Results reveal that a three-parameter\u0000Weibull distribution with a non-zero shift parameter is a better fit for the\u0000wind data with a higher percentage of low wind speeds (0–1 m s−1) and\u0000low skewness. However, wind data with a smaller percentage of low wind\u0000speeds and high skewness showed better results with a two-parameter\u0000distribution that is a special case of the three-parameter Weibull distribution\u0000with a zero shift parameter. The proposed distribution can be incorporated into\u0000commercial software like WAsP to improve the accuracy of wind resource\u0000assessments. The results also demonstrate that the proposed Bayesian\u0000approach and application of a three-parameter Weibull distribution are\u0000extremely useful for accurate estimation of wind power density.\u0000","PeriodicalId":46540,"journal":{"name":"Wind Energy Science","volume":null,"pages":null},"PeriodicalIF":4.0,"publicationDate":"2023-08-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42297393","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. E. Haupt, B. Kosović, L. Berg, C. Kaul, M. Churchfield, J. Mirocha, D. Allaerts, Thomas Brummet, S. Davis, A. Decastro, S. Dettling, C. Draxl, D. Gagne, P. Hawbecker, Pankaj Jha, T. Juliano, W. Lassman, E. Quon, R. Rai, M. Robinson, W. Shaw, Regis Thedin
Abstract. The Mesoscale to Microscale Coupling team, part of the U.S. Department of Energy Atmosphere to Electrons (A2e) initiative, has studied various important challenges related to coupling mesoscale models to microscale models for the use case of wind energy development and operation. Several coupling methods and techniques for generating turbulence at the microscale that is subgrid to the mesoscale have been evaluated for a variety of cases. Case studies included flat-terrain, complex-terrain, and offshore environments. Methods were developed to bridge the terra incognita, which scales from about 100 m through the depth of the boundary layer. The team used wind-relevant metrics and archived code, case information, and assessment tools and is making those widely available. Lessons learned and discerned best practices are described in the context of the cases studied for the purpose of enabling further deployment of wind energy.
{"title":"Lessons learned in coupling atmospheric models across scales for onshore and offshore wind energy","authors":"S. E. Haupt, B. Kosović, L. Berg, C. Kaul, M. Churchfield, J. Mirocha, D. Allaerts, Thomas Brummet, S. Davis, A. Decastro, S. Dettling, C. Draxl, D. Gagne, P. Hawbecker, Pankaj Jha, T. Juliano, W. Lassman, E. Quon, R. Rai, M. Robinson, W. Shaw, Regis Thedin","doi":"10.5194/wes-8-1251-2023","DOIUrl":"https://doi.org/10.5194/wes-8-1251-2023","url":null,"abstract":"Abstract. The Mesoscale to Microscale Coupling team, part of the\u0000U.S. Department of Energy Atmosphere to Electrons (A2e) initiative, has\u0000studied various important challenges related to coupling mesoscale models to\u0000microscale models for the use case of wind energy development and operation.\u0000Several coupling methods and techniques for generating turbulence at the\u0000microscale that is subgrid to the mesoscale have been evaluated for a\u0000variety of cases. Case studies included flat-terrain, complex-terrain, and\u0000offshore environments. Methods were developed to bridge the terra incognita, which scales from\u0000about 100 m through the depth of the boundary layer. The team used\u0000wind-relevant metrics and archived code, case information, and assessment\u0000tools and is making those widely available. Lessons learned and discerned\u0000best practices are described in the context of the cases studied for the\u0000purpose of enabling further deployment of wind energy.\u0000","PeriodicalId":46540,"journal":{"name":"Wind Energy Science","volume":null,"pages":null},"PeriodicalIF":4.0,"publicationDate":"2023-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44149190","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. Quick, P. Réthoré, M. Mølgaard Pedersen, R. V. Rodrigues, M. Friis-Møller
Abstract. It is important to optimize wind turbine positions to mitigate potential wake losses. To perform this optimization, atmospheric conditions, such as the inflow speed and direction, are assigned probability distributions according to measured data, which are propagated through engineering wake models to estimate the annual energy production (AEP). This study presents stochastic gradient descent (SGD) for wind farm optimization, which is an approach that estimates the gradient of the AEP using Monte Carlo simulation, allowing for the consideration of an arbitrarily large number of atmospheric conditions. SGD is demonstrated using wind farms with square and circular boundaries, considering cases with 100, 144, 225, and 325 turbines, and the results are compared to a deterministic optimization approach. It is shown that SGD finds a larger optimal AEP in substantially less time than the deterministic counterpart as the number of wind turbines is increased.
{"title":"Stochastic gradient descent for wind farm optimization","authors":"J. Quick, P. Réthoré, M. Mølgaard Pedersen, R. V. Rodrigues, M. Friis-Møller","doi":"10.5194/wes-8-1235-2023","DOIUrl":"https://doi.org/10.5194/wes-8-1235-2023","url":null,"abstract":"Abstract. It is important to optimize wind turbine positions to mitigate potential wake losses. To perform this optimization, atmospheric conditions, such as the inflow speed and direction, are assigned probability distributions according to measured data, which are propagated through engineering wake models to estimate the annual energy production (AEP). This study presents stochastic gradient descent (SGD) for wind farm optimization, which is an approach that estimates the gradient of the AEP using Monte Carlo simulation, allowing for the consideration of an arbitrarily large number of atmospheric conditions. SGD is demonstrated using wind farms with square and circular boundaries, considering cases with 100, 144, 225, and 325 turbines, and the results are compared to a deterministic optimization approach. It is shown that SGD finds a larger optimal AEP in substantially less time than the deterministic counterpart as the number of wind turbines is increased.\u0000","PeriodicalId":46540,"journal":{"name":"Wind Energy Science","volume":null,"pages":null},"PeriodicalIF":4.0,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47895083","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Maaike Sickler, B. Ummels, M. Zaaijer, R. Schmehl, K. Dykes
Abstract. Layout optimisation is essential for improving the overall performance of offshore wind farms. During the past 15 years, the use of yield optimisation algorithms has resulted in a transition from regular to more irregular farm layouts. However, since the layout affects many factors, yield optimisation alone may not maximise the overall performance. In this paper, a comparative case study is presented to quantify the effect of the wind farm layout on the overall performance of offshore wind farms. The case study was performed to investigate two performance indicators: power performance, using yield calculations with windPRO, and wake-induced tower fatigue, using the Frandsen model. It is observed that irregular wind farm layouts have a higher annual energy production compared to regular layouts. Their power production is also more persistent and less sensitive to wind direction, improving predictability and thus the market value of power output. However, one turbine location in the irregular layout has a 24 % higher effective turbulence level, leading to additional tower fatigue. As a result, fatigue-driven tower designs would require increased wall thicknesses, which would result in higher capital costs for all turbine locations. It is demonstrated in this study that layout optimisation using minimum inter-turbine spacing effectively resolves the induced wake issue while maintaining high-yield performance.
{"title":"Offshore wind farm optimisation: a comparison of performance between regular and irregular wind turbine layouts","authors":"Maaike Sickler, B. Ummels, M. Zaaijer, R. Schmehl, K. Dykes","doi":"10.5194/wes-8-1225-2023","DOIUrl":"https://doi.org/10.5194/wes-8-1225-2023","url":null,"abstract":"Abstract. Layout optimisation is essential for improving the overall performance of offshore wind farms. During the past 15 years, the use of yield optimisation algorithms has resulted in a transition from regular to more irregular farm layouts. However, since the layout affects many factors, yield optimisation alone may not maximise the overall performance. In this paper, a comparative case study is presented to quantify the effect of the wind farm layout on the overall performance of offshore wind farms. The case study was performed to investigate two performance indicators: power performance, using yield calculations with windPRO, and wake-induced tower fatigue, using the Frandsen model. It is observed that irregular wind farm layouts have a higher annual energy production compared to regular layouts. Their power production is also more persistent and less sensitive to wind direction, improving predictability and thus the market value of power output. However, one turbine location in the irregular layout has a 24 % higher effective turbulence level, leading to additional tower fatigue. As a result, fatigue-driven tower designs would require increased wall thicknesses, which would result in higher capital costs for all turbine locations. It is demonstrated in this study that layout optimisation using minimum inter-turbine spacing effectively resolves the induced wake issue while maintaining high-yield performance.\u0000","PeriodicalId":46540,"journal":{"name":"Wind Energy Science","volume":null,"pages":null},"PeriodicalIF":4.0,"publicationDate":"2023-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43675939","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract. For rotor design applications, such as wind turbine rotors or urban air mobility (UAM) rotorcraft and flying-car design, there is a significant challenge in quickly and accurately modeling rotors operating in complex, turbulent flow fields. One potential path for deriving reasonably accurate but low-cost rotor performance predictions is available through the application of data-driven surrogate modeling. In this study, an initial investigation is undertaken to apply a proper orthogonal decomposition (POD)-based reduced-order model (ROM) for predicting rotor distributed loads. The POD ROM was derived based on computational fluid dynamics (CFD) results and utilized to produce distributed-pressure predictions on rotor blades subjected to topology change due to variations in the twist and taper ratio. Rotor twist, θ, was varied between 0, 10, 20, and 30∘, while the taper ratio, λ, was varied as 1.0, 0.9, 0.8, and 0.7. For a demonstration of the approach, all rotors consisted of a single blade. The POD ROM was validated for three operation cases: a high-pitch or a high-thrust rotor in hover, a low-pitch or a low-thrust rotor in hover, and a rotor in forward flight at a low speed resembling wind turbine operation with wind shear. Results showed that reasonably accurate distributed-load predictions could be achieved and the resulting surrogate model can predict loads at a minimal computational cost. The computational cost for the hovering blade surface pressure prediction was reduced from 12 h on 440 cores required for CFD to a fraction of a second on a single core required for POD. For rotors in forward flight, cost was reduced from 20 h on 440 cores to less than a second on a single core. The POD ROM was used to carry out a design optimization of the rotor such that the figure of merit was maximized for hovering-rotor cases and the lift-to-drag effective ratio was maximized in forward flight.
{"title":"A data-driven reduced-order model for rotor optimization","authors":"N. Peters, Christopher J. Silva, J. Ekaterinaris","doi":"10.5194/wes-8-1201-2023","DOIUrl":"https://doi.org/10.5194/wes-8-1201-2023","url":null,"abstract":"Abstract. For rotor design applications, such as wind turbine rotors or urban air mobility (UAM) rotorcraft and flying-car design, there is a significant challenge in quickly and accurately modeling rotors operating in complex, turbulent flow fields. One potential path for deriving reasonably accurate but low-cost rotor performance predictions is available through the application of data-driven surrogate modeling. In this study, an initial investigation is undertaken to apply a proper orthogonal decomposition (POD)-based reduced-order model (ROM) for predicting rotor distributed loads. The POD ROM was derived based on computational fluid dynamics (CFD) results and utilized to produce distributed-pressure predictions on rotor blades subjected to topology change due to variations in the twist and taper ratio. Rotor twist, θ, was varied between 0, 10, 20, and 30∘, while the taper ratio, λ, was varied as 1.0, 0.9, 0.8, and 0.7. For a demonstration of the approach, all rotors consisted of a single blade. The POD ROM was validated for three operation cases: a high-pitch or a high-thrust rotor in hover, a low-pitch or a low-thrust rotor in hover, and a rotor in forward flight at a low speed resembling wind turbine operation with wind shear. Results showed that reasonably accurate distributed-load predictions could be achieved and the resulting surrogate model can predict loads at a minimal computational cost. The computational cost for the hovering blade surface pressure prediction was reduced from 12 h on 440 cores required for CFD to a fraction of a second on a single core required for POD. For rotors in forward flight, cost was reduced from 20 h on 440 cores to less than a second on a single core. The POD ROM was used to carry out a design optimization of the rotor such that the figure of merit was maximized for hovering-rotor cases and the lift-to-drag effective ratio was maximized in forward flight.\u0000","PeriodicalId":46540,"journal":{"name":"Wind Energy Science","volume":null,"pages":null},"PeriodicalIF":4.0,"publicationDate":"2023-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48178778","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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