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Dependence Of Wind Turbine Curves On Atmospheric Stability Regimes An Analysis Of A West Coast North American Tall Wind Farm
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Book Synopsis Dependence of Wind Turbine Curves on Atmospheric Stability Regimes - An Analysis of a West Coast North American Tall Wind Farm by :
Download or read book Dependence of Wind Turbine Curves on Atmospheric Stability Regimes - An Analysis of a West Coast North American Tall Wind Farm written by and published by . This book was released on 2009 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt: Tall wind turbines, with hub heights at 80 m or above, can extract large amounts of energy from the atmosphere because they are likely to encounter higher wind speeds, but they face challenges given the complex nature of wind flow in the boundary layer. Depending on whether the boundary layer is stable, convective or neutral, mean wind speed (U) and turbulence ([sigma]{sub U}) may vary greatly across the tall turbine swept area (40 m to 120 m). This variation can cause a single turbine to produce difference amounts of power during time periods of identical hub height wind speeds. The study examines the influence that atmospheric mixing or stability has on power output at a West Coast North American wind farm. They first examine the accuracy and applicability of two, relatively simple stability parameters, the wind shear-exponent, [alpha], and the turbulence intensity, I{sub u}, against the physically-based, Obukhov length, L, to describe the wind speed and turbulence profiles in the rotor area. In general, the on-site stability parameters [alpha] and I{sub u} are in high agreement with the off-site, L stability scale parameter. Next, they divide the measurement period into five stability classes (strongly stable, stable, neutral, convective, and strongly convective) to discern stability-effects on power output. When only the mean wind speed profile is taken into account, the dependency of power output on boundary layer stability is only subtly apparent. When turbulence intensity I{sub u} is considered, the power generated for a given wind speed is twenty percent higher during strongly stable conditions than during strongly convective conditions as observed in the spring and summer seasons at this North American wind farm.
Book Synopsis Atmospheric Stability Impacts on Power Curves of Tall Wind Turbines - An Analysis of a West Coast North American Wind Farm by :
Download or read book Atmospheric Stability Impacts on Power Curves of Tall Wind Turbines - An Analysis of a West Coast North American Wind Farm written by and published by . This book was released on 2010 with total page 75 pages. Available in PDF, EPUB and Kindle. Book excerpt: Tall wind turbines, with hub heights at 80 m or above, can extract large amounts of energy from the atmosphere because they are likely to encounter higher wind speeds, but they face challenges given the complex nature of wind flow and turbulence at these heights in the boundary layer. Depending on whether the boundary layer is stable, neutral, or convective, the mean wind speed, direction, and turbulence properties may vary greatly across the tall turbine swept area (40 to 120 m AGL). This variability can cause tall turbines to produce difference amounts of power during time periods with identical hub height wind speeds. Using meteorological and power generation data from a West Coast North American wind farm over a one-year period, our study synthesizes standard wind park observations, such as wind speed from turbine nacelles and sparse meteorological tower observations, with high-resolution profiles of wind speed and turbulence from a remote sensing platform, to quantify the impact of atmospheric stability on power output. We first compare approaches to defining atmospheric stability. The standard, limited, wind farm operations enable the calculation only of a wind shear exponent ([alpha]) or turbulence intensity (I{sub U}) from cup anemometers, while the presence at this wind farm of a SODAR enables the direct observation of turbulent kinetic energy (TKE) throughout the turbine rotor disk. Additionally, a nearby research meteorological station provided observations of the Obukhov length, L, a direct measure of atmospheric stability. In general, the stability parameters [alpha], I{sub U}, and TKE are in high agreement with the more physically-robust L, with TKE exhibiting the best agreement with L. Using these metrics, data periods are segregated by stability class to investigate power performance dependencies. Power output at this wind farm is highly correlated with atmospheric stability during the spring and summer months, while atmospheric stability exerts little impact on power output during the winter and autumn periods. During the spring and summer seasons, power output for a given wind speed was significantly higher during stable conditions and significantly lower during strongly convective conditions: power output differences approached 20% between stable and convective regimes. The dependency of stability on power output was apparent only when both turbulence and the shape of the wind speed profile were considered. Turbulence is one of the mechanisms by which atmospheric stability affects a turbine's power curve at this particular site, and measurements of turbulence can yield actionable insights into wind turbine behavior.
Book Synopsis Synergistic Effects of Turbine Wakes and Atmospheric Stability on Power Production at an Onshore Wind Farm by :
Download or read book Synergistic Effects of Turbine Wakes and Atmospheric Stability on Power Production at an Onshore Wind Farm written by and published by . This book was released on 2012 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report examines the complex interactions between atmospheric stability and turbine-induced wakes on downwind turbine wind speed and power production at a West Coast North American multi-MW wind farm. Wakes are generated when the upwind flow field is distorted by the mechanical movement of the wind turbine blades. This has two consequences for downwind turbines: (1) the downwind turbine encounters wind flows with reduced velocity and (2) the downwind turbine encounters increased turbulence across multiple length scales via mechanical turbulence production by the upwind turbine. This increase in turbulence on top of ambient levels may increase aerodynamic fatigue loads on the blades and reduce the lifetime of turbine component parts. Furthermore, ambient atmospheric conditions, including atmospheric stability, i.e., thermal stratification in the lower boundary layer, play an important role in wake dissipation. Higher levels of ambient turbulence (i.e., a convective or unstable boundary layer) lead to higher turbulent mixing in the wake and a faster recovery in the velocity flow field downwind of a turbine. Lower levels of ambient turbulence, as in a stable boundary layer, will lead to more persistent wakes. The wake of a wind turbine can be divided into two regions: the near wake and far wake, as illustrated in Figure 1. The near wake is formed when the turbine structure alters the shape of the flow field and usually persists one rotor diameter (D) downstream. The difference between the air inside and outside of the near wake results in a shear layer. This shear layer thickens as it moves downstream and forms turbulent eddies of multiple length scales. As the wake travels downstream, it expands depending on the level of ambient turbulence and meanders (i.e., travels in non-uniform path). Schepers estimates that the wake is fully expanded at a distance of 2.25 D and the far wake region begins at 2-5 D downstream. The actual distance traveled before the wake recovers to its inflow velocity is dependent on the amount ambient turbulence, the amount of wind shear, and topographical and structural effects. The maximum velocity deficit is estimated to occur at 1-2 D but can be longer under low levels of ambient turbulence. Our understanding of turbine wakes comes from wind tunnel experiments, field experiments, numerical simulations, and from studies utilizing both experimental and modeling methods. It is well documented that downwind turbines in multi-Megawatt wind farms often produce less power than upwind turbine rows. These wake-induced power losses have been estimated from 5% to up to 40% depending on the turbine operating settings (e.g., thrust coefficient), number of turbine rows, turbine size (e.g., rotor diameter and hub-height), wind farm terrain, and atmospheric flow conditions (e.g., ambient wind speed, turbulence, and atmospheric stability). Early work by Elliott and Cadogan suggested that power data for different turbulent conditions be segregated to distinguish the effects of turbulence on wind farm power production. This may be especially important for downwind turbines within wind farms, as chaotic and turbulent wake flows increase stress on downstream turbines. Impacts of stability on turbine wakes and power production have been examined for a flat terrain, moderate size (43 turbines) wind farm in Minnesota and for an offshore, 80 turbine wind farm off the coast of Denmark. Conzemius found it difficult to distinguish wakes (i.e., downwind velocity deficits) when the atmosphere was convective as large amounts of scatter were present in the turbine nacelle wind speed data. This suggested that high levels of turbulence broke-up the wake via large buoyancy effects, which are generally on the order of 1 km in size. On the other hand, they found pronounced wake effects when the atmosphere was very stable and turbulence was either suppressed or the length scale was reduced as turbulence in this case was mechanically produced (i.e., friction forces). This led to larger reductions at downwind turbines and maximum velocity (power) deficits reached up to 50% (70%) during strongly stable conditions. At an offshore Danish wind farm, Hansen et al. found a strong negative correlation between power deficit and ambient turbulence intensity (i.e., atmospheric stability). Under convective conditions, when turbulence levels were relatively high, smallest power deficits were observed. Power deficits approaching 35 to 40% were found inside the wind farm during stable conditions.
Book Synopsis Wind Turbine Power Production and Annual Energy Production Depend on Atmospheric Stability and Turbulence by :
Download or read book Wind Turbine Power Production and Annual Energy Production Depend on Atmospheric Stability and Turbulence written by and published by . This book was released on 2016 with total page 37 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Simulation of the Atmospheric Boundary Layer for Wind Energy Applications by : Nikola Marjanovic
Download or read book Simulation of the Atmospheric Boundary Layer for Wind Energy Applications written by Nikola Marjanovic and published by . This book was released on 2015 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt: Energy production from wind is an increasingly important component of overall global power generation, and will likely continue to gain an even greater share of electricity production as world governments attempt to mitigate climate change and wind energy production costs decrease. Wind energy generation depends on wind speed, which is greatly influenced by local and synoptic environmental forcings. Synoptic forcing, such as a cold frontal passage, exists on a large spatial scale while local forcing manifests itself on a much smaller scale and could result from topographic effects or land-surface heat fluxes. Synoptic forcing, if strong enough, may suppress the effects of generally weaker local forcing. At the even smaller scale of a wind farm, upstream turbines generate wakes that decrease the wind speed and increase the atmospheric turbulence at the downwind turbines, thereby reducing power production and increasing fatigue loading that may damage turbine components, respectively. Simulation of atmospheric processes that span a considerable range of spatial and temporal scales is essential to improve wind energy forecasting, wind turbine siting, turbine maintenance scheduling, and wind turbine design. Mesoscale atmospheric models predict atmospheric conditions using observed data, for a wide range of meteorological applications across scales from thousands of kilometers to hundreds of meters. Mesoscale models include parameterizations for the major atmospheric physical processes that modulate wind speed and turbulence dynamics, such as cloud evolution and surface-atmosphere interactions. The Weather Research and Forecasting (WRF) model is used in this dissertation to investigate the effects of model parameters on wind energy forecasting. WRF is used for case study simulations at two West Coast North American wind farms, one with simple and one with complex terrain, during both synoptically and locally-driven weather events. The model's performance with different grid nesting configurations, turbulence closures, and grid resolutions is evaluated by comparison to observation data. Improvement to simulation results from the use of more computationally expensive high resolution simulations is only found for the complex terrain simulation during the locally-driven event. Physical parameters, such as soil moisture, have a large effect on locally-forced events, and prognostic turbulence kinetic energy (TKE) schemes are found to perform better than non-local eddy viscosity turbulence closure schemes. Mesoscale models, however, do not resolve turbulence directly, which is important at finer grid resolutions capable of resolving wind turbine components and their interactions with atmospheric turbulence. Large-eddy simulation (LES) is a numerical approach that resolves the largest scales of turbulence directly by separating large-scale, energetically important eddies from smaller scales with the application of a spatial filter. LES allows higher fidelity representation of the wind speed and turbulence intensity at the scale of a wind turbine which parameterizations have difficulty representing. Use of high-resolution LES enables the implementation of more sophisticated wind turbine parameterizations to create a robust model for wind energy applications using grid spacing small enough to resolve individual elements of a turbine such as its rotor blades or rotation area. Generalized actuator disk (GAD) and line (GAL) parameterizations are integrated into WRF to complement its real-world weather modeling capabilities and better represent wind turbine airflow interactions, including wake effects. The GAD parameterization represents the wind turbine as a two-dimensional disk resulting from the rotation of the turbine blades. Forces on the atmosphere are computed along each blade and distributed over rotating, annular rings intersecting the disk. While typical LES resolution (10-20 m) is normally sufficient to resolve the GAD, the GAL parameterization requires significantly higher resolution (1-3 m) as it does not distribute the forces from the blades over annular elements, but applies them along lines representing individual blades. In this dissertation, the GAL is implemented into WRF and evaluated against the GAD parameterization from two field campaigns that measured the inflow and near-wake regions of a single turbine. The data-sets are chosen to allow validation under the weakly convective and weakly stable conditions characterizing most turbine operations. The parameterizations are evaluated with respect to their ability to represent wake wind speed, variance, and vorticity by comparing fine-resolution GAD and GAL simulations along with coarse-resolution GAD simulations. Coarse-resolution GAD simulations produce aggregated wake characteristics similar to both GAD and GAL simulations (saving on computational cost), while the GAL parameterization enables resolution of near wake physics (such as vorticity shedding and wake expansion) for high fidelity applications. For the first time, to our knowledge, this dissertation combines the capabilities of a mesoscale weather prediction model, LES, and high-resolution wind turbine parameterizations into one model capable of simulating a real array of wind turbines at a wind farm. WRF is used due to its sophisticated environmental physics models, frequent use in the atmospheric modeling community, and grid nesting with LES capabilities. Grid nesting is feeding lateral boundary condition data from a coarse resolution simulation to a finer resolution simulation contained within the coarse resolution simulation's domain. WRF allows the development of a grid nesting strategy from synoptic-scale to microscale LES relevant for wind farm simulations; this is done by building on the results from the investigation of model parameters for wind energy forecasting and the implementation of the GAD and GAL wind turbine parameterizations. The nesting strategy is coupled with a GAD parameterization to model the effects of wind turbine wakes on downstream turbines at a utility-scale Oklahoma wind farm. Simulation results are compared to dual-Doppler measurements that provide three-dimensional fields of horizontal wind speed and direction. The nesting strategy is able to produce realistic turbine wake effects, while differences with the measurements can mostly be attributed to the quality of the available weather input data.
Download or read book The Economics of Wind Energy written by and published by EWEA. This book was released on 2009 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Wind Energy Explained by : James F. Manwell
Download or read book Wind Energy Explained written by James F. Manwell and published by John Wiley & Sons. This book was released on 2010-09-14 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wind energy’s bestselling textbook- fully revised. This must-have second edition includes up-to-date data, diagrams, illustrations and thorough new material on: the fundamentals of wind turbine aerodynamics; wind turbine testing and modelling; wind turbine design standards; offshore wind energy; special purpose applications, such as energy storage and fuel production. Fifty additional homework problems and a new appendix on data processing make this comprehensive edition perfect for engineering students. This book offers a complete examination of one of the most promising sources of renewable energy and is a great introduction to this cross-disciplinary field for practising engineers. “provides a wealth of information and is an excellent reference book for people interested in the subject of wind energy.” (IEEE Power & Energy Magazine, November/December 2003) “deserves a place in the library of every university and college where renewable energy is taught.” (The International Journal of Electrical Engineering Education, Vol.41, No.2 April 2004) “a very comprehensive and well-organized treatment of the current status of wind power.” (Choice, Vol. 40, No. 4, December 2002)
Book Synopsis Probing the Atmospheric Boundary Layer by : Donald H. Lenschow
Download or read book Probing the Atmospheric Boundary Layer written by Donald H. Lenschow and published by . This book was released on 1986 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Turbulence Statistics for Design of Wind Turbine Generators by : J. C. Kaimal
Download or read book Turbulence Statistics for Design of Wind Turbine Generators written by J. C. Kaimal and published by . This book was released on 1981 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Characterization of Wake Turbulence in a Wind Turbine Array Submerged in Atmospheric Boundary Layer Flow by : Pankaj Jha
Download or read book Characterization of Wake Turbulence in a Wind Turbine Array Submerged in Atmospheric Boundary Layer Flow written by Pankaj Jha and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Wind energy is becoming one of the most significant sources of renewable energy. With its growing use, and social and political awareness, efforts are being made to harness it in the most efficient manner. However, a number of challenges preclude efficient and optimum operation of wind farms. Wind resource forecasting over a long operation window of a wind farm, development of wind farms over a complex terrain on-shore, and air/wave interaction off-shore all pose difficulties in materializing the goal of the efficient harnessing of wind energy. These difficulties are further amplified when wind turbine wakes interact directly with turbines located downstream and in adjacent rows in a turbulent atmospheric boundary layer (ABL). In the present study, an ABL solver is used to simulate different atmospheric stability states over a diurnal cycle. The effect of the turbines is modeled by using actuator methods, in particular the state-of-the-art actuator line method (ALM) and an improved ALM are used for the simulation of the turbine arrays. The two ALM approaches are used either with uniform inflow or are coupled with the ABL solver. In the latter case, a precursor simulation is first obtained and data saved at the inflow planes for the duration the turbines are anticipated to be simulated. The coupled ABL-ALM solver is then used to simulate the turbine arrays operating in atmospheric turbulence.A detailed accuracy assessment of the state-of-the-art ALM is performed by applying it to different rotors. A discrepancy regarding over-prediction of tip loads and an artificial tip correction is identified. A new proposed ALM* is developed and validated for the NREL Phase VI rotor. This is also applied to the NREL 5-MW turbine, and guidelines to obtain consistent results with ALM* are developed.Both the ALM approaches are then applied to study a turbine-turbine interaction problem consisting of two NREL 5-MW turbines. The simulations are performed for two ABL stability states. The effect of ABL stability as well the ALM approaches on the blade loads, turbulence statistics, unsteadiness, wake profile etc., is quantified. It is found that ALM and ALM* yield a noticeable difference in most of the parameters quantified. The ALM* also senses small-scale blade motions better. However, the ABL state dominates the wake recovery pattern. The ALM* is then applied to a mini wind farm comprising five NREL 5-MW turbines in two rows and in a staggered configuration. A detailed wake recovery study is performed using a unique wake-plane analysis technique. An actuator curve embedding (ACE) method is developed to model a general-shaped lifting surface. This method is validated for the NREL Phase VI rotor and applied to the NREL 5-MW turbine. This method has the potential for application to aero-elasticity problems of utility-scale wind turbines.
Book Synopsis Remote Sensing of Atmospheric Conditions for Wind Energy Applications by : Charlotte Bay Hasager
Download or read book Remote Sensing of Atmospheric Conditions for Wind Energy Applications written by Charlotte Bay Hasager and published by MDPI. This book was released on 2019-05-24 with total page 290 pages. Available in PDF, EPUB and Kindle. Book excerpt: This Special Issue “Atmospheric Conditions for Wind Energy Applications” hosts papers on aspects of remote sensing for atmospheric conditions for wind energy applications. Wind lidar technology is presented from a theoretical view on the coherent focused Doppler lidar principles. Furthermore, wind lidar for applied use for wind turbine control, wind farm wake, and gust characterizations is presented, as well as methods to reduce uncertainty when using lidar in complex terrain. Wind lidar observations are used to validate numerical model results. Wind Doppler lidar mounted on aircraft used for observing winds in hurricane conditions and Doppler radar on the ground used for very short-term wind forecasting are presented. For the offshore environment, floating lidar data processing is presented as well as an experiment with wind-profiling lidar on a ferry for model validation. Assessments of wind resources in the coastal zone using wind-profiling lidar and global wind maps using satellite data are presented.
Book Synopsis Wind Resource Assessment by : Michael Brower
Download or read book Wind Resource Assessment written by Michael Brower and published by John Wiley & Sons. This book was released on 2012-06-19 with total page 298 pages. Available in PDF, EPUB and Kindle. Book excerpt: A practical, authoritative guide to the assessment of wind resources for utility-scale wind projects authored by a team of experts from a leading renewable energy consultancy The successful development of wind energy projects depends on an accurate assessment of where, how often, and how strongly the wind blows. A mistake in this stage of evaluation can cause severe financial losses and missed opportunities for developers, lenders, and investors. Wind Resource Assessment: A Practical Guide to Developing a Wind Project shows readers how to achieve a high standard of resource assessment, reduce the uncertainty associated with long-term energy performance, and maximize the value of their project assets. Beginning with the siting, installation, and operation of a high-quality wind monitoring program, this book continues with methods of data quality control and validation, extrapolating measurements from anemometer height to turbine height, adjusting short-term observations for historical climate conditions, and wind flow modeling to account for terrain and surface conditions. In addition, Wind Resource Assessment addresses special topics such as: Worker safety Data security Remote sensing technology (sodar and lidar) Offshore resource assessment Impacts of climate change Uncertainty estimation Plant design and energy production estimatio Filled with important information ranging from basic fundamentals of wind to cutting-edge research topics, and accompanied by helpful references and discussion questions, this comprehensive text designed for an international audience is a vital reference that promotes consistent standards for wind assessment across the industry.
Book Synopsis Studying the Impact of Atmospheric Stability and Turbulence on Wind Turbine Wakes at the Vindeby Wind Farm, Denmark by : Catherine Brabant
Download or read book Studying the Impact of Atmospheric Stability and Turbulence on Wind Turbine Wakes at the Vindeby Wind Farm, Denmark written by Catherine Brabant and published by . This book was released on 2010 with total page 262 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Advances in Wind Energy Conversion Technology by : Mathew Sathyajith
Download or read book Advances in Wind Energy Conversion Technology written by Mathew Sathyajith and published by Springer Science & Business Media. This book was released on 2011-04-29 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt: With an annual growth rate of over 35%, wind is the fastest growing energy source in the world today. As a result of intensive research and developmental efforts, the technology of generating energy from wind has significantly changed during the past five years. The book brings together all the latest aspects of wind energy conversion technology - right from the wind resource analysis to grid integration of the wind generated electricity. The chapters are contributed by academic and industrial experts having vast experience in these areas. Each chapter begins with an introduction explaining the current status of the technology and proceeds further to the advanced lever to cater for the needs of readers from different subject backgrounds. Extensive bibliography/references appended to each chapter give further guidance to the interested readers.
Book Synopsis Wind Farm Dynamics and Power Optimization in Realistic Atmospheric Boundary Layer Conditions by : Michael Frederick Howland
Download or read book Wind Farm Dynamics and Power Optimization in Realistic Atmospheric Boundary Layer Conditions written by Michael Frederick Howland and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The study of wind farms within realistic atmospheric boundary layer (ABL) conditions is critical to understand the governing physics of the system and to design optimal operational protocols. Aerodynamic wake interactions between individual wind turbines typically reduce total wind farm energy production 10-20% and increase the cost of electricity for this resource. Further, in large wind farms, the collective farm efficiency is in part dictated by the interaction between the wind farm and the turbulent ABL and, correspondingly, the vertical transport of kinetic energy into the turbine array. Coriolis forces, arising from the projection of Earth's rotation into a non-inertial rotating Earth-fixed frame, modify the interaction of a wind farm with the ABL. The traditional approximation made in typical ABL simulations assumes that the horizontal component of Earth's rotation is negligible in the atmospheric boundary layer. When including the horizontal component of Earth's rotation, the boundary layer and wind farm physics are a function of the geostrophic wind direction. The influence of the geostrophic wind direction on a wind farm atmospheric boundary layer was characterized using conventionally neutral and stable boundary layer large eddy simulations (LES). In the Northern hemisphere, geostrophic winds from west-to-east establish the horizontal component of Earth's rotation as a sink term in the shear Reynolds stress budget whereas the horizontal component manifests as a source term for east-to-west geostrophic winds. As a result, the magnitude of entrainment of mean kinetic energy into a wind turbine array is modified by the direction of the geostrophic wind, and correspondingly, the boundary layer height and wind speed and direction profiles depend on the geostrophic wind direction. Historically, wind farm control protocols have optimized the performance of individual wind turbines which results in aerodynamic wake interactions and a reduction in wind farm efficiency. Considering the wind farm as a collective, a physics- and data-driven wake steering control method to increase the power production of wind farms is developed. Upwind turbines, which generate turbulent energy-deficit wake regions which impinge on downwind generates, are intentionally yaw misaligned with respect to the incident ABL wind. While the yaw misaligned turbine may produce less power than in yaw aligned operation, the downwind generators may significantly enhance their production, increasing the collective power for the farm. The wake steering method developed combines a physics-based engineering wake model with state estimation techniques based on the assimilation of the wind farm power production data, which is readily available for control decisions at operational wind farms. Analytic gradients are derived from the wake model and leveraged for efficient yaw misalignment set-point optimization. The open-loop wake steering control methodology was tested in a multi-turbine array at a utility-scale operational wind farm, where it statistically significantly increased the power production over standard operation. The analytic gradient-based wind farm power optimization methodology developed can optimize the yaw misalignment angles for large wind farms on the order of seconds, enabling online real-time control. The dynamics of the ABL range from microscale features on the order of meters to mesoscale meteorological scales on the order of hundreds of kilometers. As a result of the broad range of scales and diversity of competing forces, the wind farm interaction with the turbulent ABL is a complex dynamical system, necessitating closed-loop control which is able to dynamically adapt to the evolving wind conditions. In order to rapidly design and improve dynamic closed-loop wind farm controllers, we developed wind farm LES capabilities which incorporate Coriolis and stratification effects and which permit the experimentation of real-time control strategies. Dynamic, closed-loop wake steering controllers are tested in simulations with full Coriolis effects and, altogether, the results indicate that closed-loop wake steering control can significantly increase wind farm power production over greedy operation provided that site-specific wind farm data is assimilated into the optimal control model.
Download or read book Wind Energy written by Mathew Sathyajith and published by Springer Science & Business Media. This book was released on 2006-03-14 with total page 253 pages. Available in PDF, EPUB and Kindle. Book excerpt: Growing energy demand and environmental consciousness have re-evoked human interest in wind energy. As a result, wind is the fastest growing energy source in the world today. Policy frame works and action plans have already been for- lated at various corners for meeting at least 20 per cent of the global energy - mand with new-renewables by 2010, among which wind is going to be the major player. In view of the rapid growth of wind industry, Universities, all around the world, have given due emphasis to wind energy technology in their undergraduate and graduate curriculum. These academic programmes attract students from diver- fied backgrounds, ranging from social science to engineering and technology. Fundamentals of wind energy conversion, which is discussed in the preliminary chapters of this book, have these students as the target group. Advanced resource analysis tools derived and applied are beneficial to academics and researchers working in this area. The Wind Energy Resource Analysis (WERA) software, provided with the book, is an effective tool for wind energy practitioners for - sessing the energy potential and simulating turbine performance at prospective sites.
Book Synopsis Wind Energy Statistics for Large Arrays of Wind Turbines (Great Lakes and Pacific Coast Regions) by : C.G. Justus
Download or read book Wind Energy Statistics for Large Arrays of Wind Turbines (Great Lakes and Pacific Coast Regions) written by C.G. Justus and published by . This book was released on 1977 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In an earlier study the wind and wind power statistics of large arrays of wind turbines in the New England and Central U.S. Regions were examined. This report examines arrays of simulated 0.5 MW, 1.5 MW and2.0 MW wind turbines in the Great Lakes and Pacific Coast Regions. As with the earlier study, the parameters analyzed are: basic wind statistics, time and spatial correlations, mean wind power output, wind power frequency (availability without storage), and run duration of windspeed and array power (probabilities of wind and power lulls of various duration, without storage). New aspects of the present study include evaluation of diurnal as well as seasonal variations of wind and wind power, inclusion of density, wind shear, wind gusts and other factors in the model power output curve simulation, study of the possible relation between wind speed and degree days (known to affect a portion of utility demand), and development and verification of a simplified array simulation model. The basic results are similar to the earlier study, except that the Pacific Coast array had much lower spatial correlation because of terrain influence. No relationship between winds and degree days was observed although wind and temperature are related by virtue of a common diurnal variation pattern.
