This study uses Large Eddy Simulation in the ANSYS Fluent software to assess the accuracy of the forced cooling term for the overhead conductor codes, IEEE 738 [1] and CIGRÉ 207 [2], for Real Time Thermal Rating of a wind farm power line. The analysis is done for low wind speed, corresponding to Reynolds Number of 3,000. The primary goal is to calculate Nusselt Number for cylindrical conductors with free-stream turbulence. Calculations showed an increase in convective heat transfer from the low turbulence value by ∼ 30 % at turbulence intensity of 21% and length scale to diameter ratio of 0.4; and an increase of ∼ 19 % at turbulence intensity of 8% and length scale to diameter ratio of 0.4.

This paper proposes a new combined vibration suppressing device, which can be used to suppress the swaying vibration of off-shore floating wind generator under waves. The floating wind power station tower was modeled, the wave force and the torsion force of the tower were analyzed and the FSI numerical simulation was carried out. The calculation results demonstrate that the amplitudes of the tower torsion angle have been attenuated by 8%, 11% and 17% with different vibration suppression devices which are TMD, TLD and new combined device. In this case the new combined device has the best vibration suppression performance. It is validated that compared to the other two single vibration suppression devices, the new combined device has better vibration suppression capacity and a new way is provided to design the vibration suppression device for off shore floating wind power station.

Vertical axis wind turbines present several advantages over the horizontal axis machines that make them suitable to a variety of wind conditions. However due to the complexity of VAWT aerodynamics, available literature on VAWT performance in steady and turbulent wind conditions is limited. This paper aims to numerically predict the performance of a 5kW VAWT under steady wind conditions through computational fluid dynamics modeling by varying turbine configuration parameters. Two dimensional VAWT models using a cambered blade (1.5%) were created with open field boundary extents. Turbine configuration parameters studied include blade mounting position, blade fixing angle, and rotor solidity. Baseline case with peak Cp of 0.31 at tip speed ratio of 4 has the following parameters: mounting position at 0.5c, zero fixing angle, 3 blades (solidity = 0.3). Independent parametric studies were carried out and results show that a blade mounting position of 0.7c from the leading edge produces best performance with maximum Cp = 0.315 while worst case is a mounting position of 0.15c with peak Cp = 0.273. Fixing angle study reveals a toe-out setting of −1° producing the best performance with peak Cp of 0.315 and the worst setting at toe-in of 1.5° with peak Cp of 0.287. The solidity study resulted in a best case of 4 blades (solidity = 0.4) with peak Cp = 0.316 and worst case of 2 blades (solidity = 0.2) with peak Cp = 0.283.

This paper presents an optimization procedure which integrates lightning strike analysis into design reliable and economical composite wind turbine blades. A high-fidelity 5-MW composite wind turbine blade is applied into the lightning strike analysis and the optimization procedure under four different lightning severity levels. The lightning-strike-induced electric field along the wind turbine blade at the top vertical position is calculated using finite element analysis. The dielectric breakdown strength of the composite wind turbine blade is considered as a function of laminate thickness. The lightning safety ratio is then calculated as the ratio between the dielectric breakdown strength and the magnitude of the lightning-strike-induced electric field. Subjected to the lightning constraints and fatigue constraints, the optimization procedure minimizes the total composite material cost by fine-tuning the laminate thickness design variables of the blade model. Both the lightning strike analysis and the optimization results indicate that the blade tip is the most vulnerable region against lightning strike damage. The obtained optimum designs under the four lightning severity levels increase the lightning safety ratio by 36% – 45% and increase the fatigue life more than 15 times compared with the initial blade design.

Improved understanding of wind gust climates may be of great value to the wind energy industry, and is currently hampered by a lack of high-quality in situ data in wind resource rich environments. Thus, we are examining the potential to supplement anemometry with data from seismometers, including those deployed as part of the USArray Transportable Array (TA). Two models of the relationship between gust magnitude and ground motion are evaluated based on their skill at describing the distribution of gust wind speeds over 1 year using seismic data. The approach is illustrated, using observed gust magnitudes obtained from sonic anemometers located at or near the 15 TA seismic stations. One deterministic and one probabilistic wind-seismic model are conditioned using one year of 5-minute resolution data and tested on a second year of independent data. Both models relate the variance of ground acceleration in the frequency range of 0.01 to 0.1 Hz ( P ) to gust speed ( U g ) but differ in their functional form. The probabilistic model is found to perform well in predicting the gust distribution in independent data, and at the 15 sites considered herein has an integrated error across the entire cumulative probability distribution that is only 5% of the mean gust magnitude.

The utilization of a ground-based testing facility for full-size wind turbine drivetrains is growing. Several test benches have been developed to apply torque and non-torque loads. These mechanical loads can be the loads used to design the drivetrain components or loads obtained from field measurements. Irrespective of the reason for testing a drivetrain, the selected test bench should have the capability to impose the loads of interest. The design of these test benches and their capabilities vary, and the loads of interest vary between drivetrain designs. A systematic method to evaluate the capability of a test bench to impose the loads of interest has been developed. This method can be applied to any test bench and drivetrain design. Part I of this paper presents the methodology and recommendations for presenting and interpreting the results. The demonstration of the method is the focus of part II. Overall, this two-part paper aims to establish guidelines for consideration by the IEA task force 35 for ground based testing for wind turbines and their components.

The systematic evaluation of wind turbine drivetrains using hardware-in-the-loop strategies (previously presented in Part I) is demonstrated using a state-of-the-art multi-MW drivetrain design and a 7.5-MW test bench. The test bench has the capability to apply both torque and non-torque loads to the electro-mechanical drivetrain. The proposed method to evaluate the capability of a test bench to impose the loads of interest uses design loads of the drivetrain and the test bench load application unit limits as inputs. The design loads are defined by stochastic time series of the longitudinal, lateral, and vertical forces as well as the yawing and nodding bending moments that the load application unit can concurrently apply to the drivetrain (i.e., combined loading). A total of 14 time series sets are considered to capture the minimum and maximum values of the longitudinal, lateral, vertical, and resultant forces as well as the yawing, nodding, and resultant moments. These time series are processed individually to calculate two metrics: the coverage and the capability ratio of the test bench. The former is a percentage of the time series that be applied by the test bench, and the latter indicates an excess (or deficit) in load application capability as compared with the selected design loads. The results are presented and interpreted using the previously described methodology. The findings suggest a good match between test bench capability and the loads of interest in general, and also points to challenges. These discoveries establish a basis for the experimental verification and the development of compensation methods to enhance test bench capabilities.

The rise of energy prices, concerns over climate change and geopolitical issues have brought special attention to renewable sources of energy and wind energy in particular. Based on NREL projections, the United States has more than 32,000 TWh of onshore and 17,000 TWh of offshore potential for wind power generation, which is far beyond its 11,000 TWh of current annual electricity consumption. However, there are a number of efficiency challenges that must be overcome in order to turn this potential into actual production. One area that can potentially improve the energy production of wind turbines is the correction of yaw error. Yaw error (also referred to as yaw angle or yaw misalignment) is the angle between the turbine’s rotor and the wind direction. A yaw error reduces turbine’s power production at wind speeds below the rated speed. Besides impacting the power producing ability of a turbine, yaw error also affects the reliability of critical subsystems in wind turbines. Variation in yaw error (at any wind speed and not only below the rated speed) affects the loads on the components and the subsequent mechanical stresses. These mechanical stresses change the damage accumulation for components and sub-assemblies, which ultimately affects their reliability. About 17 to 28% of wind project costs attribute to O&M costs, which are directly affected by the reliability. In this study, we investigate the effects of yaw error on the reliability of blades by performing load and stress analysis for various yaw errors. We then use the results of these analyses to adjust the Weibull parameters used for predicting the failure time of blades. Finally, we will use a stochastic cost model to show how correcting the yaw error can avoid maintenance costs in wind farms.

Offshore wind farms are presently facing numerous technical challenges that are affecting their viability. High failure rates of expensive nacelle-based electronics and gearboxes are particularly problematic. On-going research is investigating the possibility of shifting to a seawater-based hydraulic power transmission, whereby wind turbines pressurise seawater that is transmitted across a high-pressure pipeline network. A 9-turbine hydraulic wind farm with three different configurations is simulated in the present work and a previously developed method for open-loop pressure control of a single turbine has been adapted for this multiple-turbine scenario. A conceptual quasi-constant-pressure accumulator is also included in the model. This system is directly integrated within each hydraulic wind turbine and it allows the output power from the wind farm to be scheduled on an hourly basis. The shift in control methodology when integrating storage is illustrated in the present work. Simulation results indicate a strong relationship between hydraulic performance attributes and the specific wind turbine array layout. The beneficial effects of storage can also be observed, particularly in smoothing the output power and rendering it more useable. Finally, the energy yields from 24-hour simulations of the 9-turbine wind farms are calculated. Integrated storage leads to a slight increase in yield since it eliminates bursts of high flow, which induce higher frictional losses in the pipeline network.

Fossil fuels have been a means of energy source since a long time, and have tended to the needs of the large global population. These conventional sources are bound to deplete in the near future and hence there is a need for producing energy from renewable energy sources like solar, wind, geothermal, tidal etc. Technologies involving renewable energy are a growing subject of concern. Further, the problem is also one of excessive pollution caused by conventional sources of energy and their impact on the environment. In particular, one of the main sources of pollution is harmful gases emitting out of automobiles. Wind energy is one among the renewable energy sources which is implemented in large scale energy production to supplement growing domestic energy needs. Significant amount of research has been done in this field to harness energy to power household and other amenities using wind farms. The aim of this project is to come up with a low cost solution for wind energy harvesting on moving vehicles. The purpose of this study is to consider the use of wind energy along with conventional energy sources to power automobiles. This would help reduce the use of fossil fuels in automobiles and hence reduce the resulting environmental pollution. Also since the turbine adds to the weight of the vehicle the aim also is to minimize the weight of the turbine. Extensive structural analysis is done for this purpose to choose a material which would be both light weight and also be able to withstand the stresses developed. In the current paper the drag force produced in automobiles is harvested by using a convergent divergent nozzle mounted below the chassis of the car. Initially drag analysis is done in order to determine the increase in drag force produced after mounting of the nozzle. It is found from existing literature that the drag increases by 3.4% after the mounting of the nozzle making it possible the mounting of a nozzle beneath the car. Additionally exhaust gases is also allowed to pass through the same duct to increase the mass flow to the turbine and thus generate more energy. This is made to strike the blades of a 2 stage axial flow turbine whose rotation generates energy. The power output from the turbine is the parameter of interest. This energy can also be stored in batteries and be used to run auxiliary equipment of the automobile including the air conditioner. The exhaust gases will be passed through a catalytic converter before striking the blades of the turbine in order to prevent corrosion of the blades. Computational Fluid Dynamics (CFD) is used to validate the concept and also come up with a design that maximizes energy generation by such turbines. Numerical results obtained by simulation are validated by theoretical calculation based on turbines inlet and outlet velocity triangles. The future scope of the project would include the use of multiple nozzles in order to study its performance.

As wind energy is established as a sustainable alternative source of electricity, very large-scale wind farms with hundreds of turbines are becoming increasingly common. For the optimal design of wind farm layouts, the number of decision variables is at least twice the number of turbines (e.g., the Cartesian coordinates of each turbine). As the number of turbines increases, the computational cost incurred by the optimization solver to converge to a satisfactory solution increases as well. This issue represents a serious limitation in the computer-aided design of large wind farms. Moreover, the wind farm domains are typically highly constrained including land-availability and proximity constraints. These non-linear constraints increase the complexity of the optimization problem and decrease the likelihood of obtaining even a feasible solution. Several approaches have been proposed for micrositing of wind turbines, including random searches, mixed-integer programs, and metaheuristics. Each of these methods has its own trade-off between the quality of optimized layouts and the computational cost of obtaining the solution. In this paper, we demonstrate the capability of non-linear mathematical programming for optimizing very large-scale wind farms by leveraging explicit, analytical derivatives for the objective and constraint functions, thus overcoming the aforementioned limitations while also providing convergence and local optimality guarantees. For that purpose, two large farms with hundreds of turbines and significant land-use constraints are solved on a standard personal computer.

The performance of Savonius wind turbine can be improved by increasing the effective wind velocity. One of the methods of improving the effective wind velocity is using directional augmentation technique, which actually affects the Omnidirectional capability of the Savonius rotor. This paper works on this method by using convergent nozzle at the outlet of the rotor. The whole work is based on Metamodeling based optimization and numerical simulation. Reynolds averaged Navier-stokes equation (RANS) based turbulence model has been used for simulations, such as static simulation and dynamic simulation. The CFD simulations are validated against previously published experimental data. The optimization procedure is performed by integrating the Design of Experiment (DOE), Computational Fluid Dynamics (CFD), Response Surface Model (RSM) and analysis of variance (ANOVA). The meta-model is able to identify significant design variable and the interactions. The proposed optimal nozzle is shown to improve the coefficient of the moment from 0.3 to 0.44.

An optimization method that changes the control strategy of the Horizontal Axis Wind Turbine (HAWT) from passive- to active-pitch has been developed. The method aims to keep the rated power constant by adjusting the blade pitch angle while matching the rotor and the drive torques. The method is applied to an optimized wind turbine model. Further, numerical simulations were performed to validate the developed method and for further investigations of the flow behavior over the blades.

WINDGRABBER™ (WG) is a novel new roof or pole top mounted wind turbine system proposed for product commercialization up to 50 kWe. WG is projected to be cost-attractive in an environmentally friendly manner. The WG system uses the available energy in the wind via (1) a passively yawed air impact inlet air scoop, (2) a flow tube, (3) an air turbine and (4) a multiphased air inlet with an air impact - drag type outlet section. The WG wind turbine system preferentially utilizes a combination enclosed - radial out-flow, cross-flow, reaction-impulse air turbine of squirrel cage configuration, using either a single or double axial flow inlet of centrifugal fan design with backwardly curved, air foil air blades mounted on the discharge end of a flow tube. The WG wind turbine design is based on the air power instead of the wind power equations, combined with duct resistance, wind impact and wind drag calculations, to determine system wind energy conversion effectiveness with respect to the Betz limit, as well as overall system efficiency. Low pressure drop screens may be provided at the various inlets and outlets to protect birds and small mammals from being drawn into rotating components. A currently proposed Phase I – CAE modeling for conceptual design verification, system optimization and 300 watt pilot plant test program, followed by a Phase II – design improvement and scale up to 3,000 watt prototype demonstration program and followed by a Phase III cost reduction, product improvement and scale up to a 5,000 watt commercial demonstration program is currently being considered by BCK Consulting, L.L.C. (BCK) and West Texas A & M University (WTAMU). The history of WG , up to and including its latest developmental status, will be discussed in this paper with projections offered regarding its future product commercialization prospects. Please see ASME paper ES2010-90062 presented previously [Ref.1].

Acoustic noises emitted from wind turbine blades should be reduced to an acceptable level for the uptake of wind energy in buildings and in the urban environment. This paper reports on effectiveness of, Owl-wing-serrations (OWS), two-dimensional trip-wires, and Active-noise-cancellation (ANC) in minimization of aerodynamic noises in a micro model turbine. The OWS and trip wires were attached to the blade leading edges and trailing edges in the wind turbine. The model was operated in the fan mode as a single row. Combined effects of OWS and ANC were also tested in a counter rotating double-row Fan. Air velocity (m/s), shaft-revolution (rpm); electric-power (W), amplitude of acoustic noise (dB) and its Centre frequency (CF in Hz) were measured at a reference location, for a number of spacing. Experimental results were plotted in the forms of dB vs. Tip Speed Ratio (TSR), dB vs. CF, and Efficiency or Coefficients of Performance COP vs. TSR. It was noticed that • In the single row operations, 3mm trip wires and OWS attached to blades have influenced on the emitted aerodynamic noises. OWS reduced dB and increased Cf more than the trip-wires. For example, at a fixed TSR, amplitude of noise (dB) decreased with trip wires or OWS with the lowest dB occurring with the OWS alone. At a fixed dB, Centre frequency (Cf) increased with the highest frequency Cf occurring with OWS alone. Minor changes in efficiency (COP) were noticed with the trip wires or Owl-wing serrations. It may suggest that larger eddies are converted into small turbulences with lower amplitudes and higher frequencies. • Active-noise-cancellation (ANC) in the double row operation affected acoustic noises as spacing/gap between the counter-rotating rows changed. At a fixed TSR, dB decreased in the double row operations in comparison with the single-row operations, the reduction in dB increased at higher TSR. At a fixed dB, Centre frequency (Cf) increased by 100% with the highest frequency Cf occurring at the spacing of 50mm. Efficiency or COP decreased by 50% when ANC was implemented with a minor change due to spacing between rows. • Combined effects of OWS and ANC were moderate comparing to ANC alone, reducing both dB and COP by around 35% while doubling Cf as compared to the single raw fan conditions. The minimum dB and maximum Cf occurred at the gap/spacing of 50mm. No significant change was noticed at COP with combined OWS and ANC.

Wind energy has been identified as an important source of renewable energy. In this study, several wind turbine designs have been analyzed and optimized designs have been proposed for low wind speed areas around the world mainly for domestic energy consumption. The wind speed range of 4–12 mph is considered, which is selected based on the average wind speeds in the Atlanta, GA and surrounding areas. These areas have relatively low average wind speeds compared to various other parts of the United States. Traditionally wind energy utilization is limited to areas with higher wind speeds. In reality a lot of areas in the world have low average wind speeds and demand high energy consumption. In most cases, wind turbines are installed in remote offshore or away from habitat high wind locations, causing heavy investment in installation and maintenance, and loss of energy transfer over long distance. A few more advantages of small scale wind turbines include reduced visibility, less noise and reduced detrimental environmental effects such as killing of birds, when compared to traditional large turbines. With the latest development in wind turbine technology it is now possible to employ small scale wind turbines that have much smaller foot print and can generate enough energy for small businesses or residential applications. The low speed wind turbines are typically located near residential areas, and are much smaller in sizes compared to the large out of habitat wind turbines. In this study, several designs of vertical and horizontal axes wind turbines are modeled using SolidWorks e.g. no-airfoil theme, airfoil blade, Savonius rotor etc. Virtual aerodynamic analysis is performed using SolidWorks Flow simulation software, and then optimization of the designs is performed based on maximizing the starting rotational torque and ultimate power generation capacity. From flow simulations, forces on the wind turbine blades and structures are calculated, and used in subsequent stress analysis to confirm structural integrity. Critical insight into low wind speed turbines is obtained using various configurations, and optimized designs have been proposed. The study will help in the practical and effective utilization of wind energy for the areas around the globe having low average wind speeds.

This paper presents a new approach allowing Numerical Weather Prediction (NWP) grid model forecasting to be applied to a desired “sub-grid” location. It permits observations from a NWP model using a novel bank of 24 Kalman Filters (KFs) operating simultaneously to accurately predict the wind speed ( Z t ) 24 hours ahead for a campus based wind turbine at Cork Institute of Technology (CIT) at 20m above sea level (asl) at sub grid location. The NWP model outputs wind speed predictions ( m t ) for Cork Airport at 152m asl (2.5km distant from CIT) at grid level. The Kalman Filter (KF), acting as a post processing tool with a moving time averaging window, derives a 24 hour ahead predicted wind speed schedule for CIT by applying a wind speed bias model polynomial to map and filter the wind speed bias offset between the two locations. To ensure a robust model, with good modelling and error noise disturbance rejection capabilities inclusive of model offsets [1], the accuracy of the model has been investigated using a particularly turbulent wind data set for December 2013 [2]. It is shown that a 4th order polynomial adaptive wind speed model bias remover is the optimum choice to employ in conjunction with the KF which uses a 3 point a priori moving window averager to adequately eliminate systematic error. The application of a KF to wind speed prediction is implemented in MATLAB software and results are provided in this paper to demonstrate the accuracy and fidelity of the procedure. Hypothesis testing along with statistical analysis has returned wind velocity prediction estimates that demonstrate the accuracy of the KF estimator. This also provides confidence enhancement of the polynomial model choice as a suitable wind velocity bias eliminator. The accuracy of the hourly wind velocity estimate are of strategic importance in wind power prediction where installed wind turbine scheduling is an issue for cost effective electrical network operation with a consequent beneficial economic return on wind generator capital investment.

World is facing a big problems for fossil fuel as it deals with the issues like availability, environmental effect like global warming etc, which forces us to explore new renewable sources of energy like solar, tidal, geothermal, wind etc. Among all the energies wind energy is the effective form of energy. As evaluated from the research, main cause for reduction of energy output in wind farm is the positioning of the wind turbine, as it is a function of wake loss. Present paper investigates an effective meta-heuristics optimization method known as Teaching–Learning-Based Optimization (TLBO), to optimize the positioning of the wind turbine in a wind farm. Two different scenarios of wind speed and its direction distribution across the wind site is considered like, (a) uniform wind speed of 12 m/s with uniform direction and (b) uniform wind speed of 12 m/s with variable wind direction. The results show that the implementation of TLBO is effective then other existing strategy, in terms of maximized expected power output and minimum wake effect of turbines by each other.

The understanding of atmospheric flows is crucial in the analysis of dispersion of a contaminant or pollutant, wind energy and air-quality assessment to name a few. Additionally, the effects of complex terrain and associated orographic forcing are crucial in wind energy production. Furthermore, the use of the Reynolds-averaged Navier-Stokes (RANS) equations in the analysis of complex terrain is still considered the “workhorse” since millions of mesh points are required to accurately capture the details of the surface. On the other hand, solving the same problem by means of the instantaneous governing equations of the flow (i.e., in a suite of DNS or LES) would imply almost prohibitive computational resources. In this study, numerical predictions of atmospheric boundary layers are performed over a complex topography located in Nygårdsfjell, Norway. The Nygårdsfjell wind farm is located in a valley at approximately 420 meters above sea level surrounded by mountains in the north and south near the Swedish border. Majority of the winds are believed to be originated from Torneträsk lake in the east which is covered with ice during the winter time. The air closest to the surface on surrounding mountains gets colder and denser. The air then slides down the hill and accumulates over the lake. Later, the air spills out westward towards Ofotfjord through the broader channel that directs and transforms it into highly accelerated winds. Consequently, one of the objectives of the present article is to study the influence of local terrain on shaping these winds over the wind farm. It is worth mentioning that we are not considering any wind turbine model in the present investigation, being the main purpose to understand the influence of the local surface topography and roughness on the wind flow. Nevertheless, future research will include modeling the presence of a wind turbine and will be published elsewhere. The governing equations of the flow are solved by using a RANS approach and by considering three different two-equation turbulence models: k-omega ( k –ω), k-epsilon ( k –ε) and shear stress transport ( SST ). Furthermore, the real topographical characteristics of the terrain have been modeled by extracting the required area from the larger digital elevation model (DEM) spanning over 100 km square. The geometry is then extruded using Rhino and meshed in ANSYS Fluent. The terrain dimensions are approximately 2000×1000 meter square.

A wind turbine blade performance depends on various parameters of which the shape of the blade is one of the most important one. In this work the shape of the tip of original NREL Phase-VI blade (S809 airfoil) has been modified to determine the changes in the blade aerodynamic performance. The chord length of new blade is kept similar to the original NREL blade up to 90% of the span. Last 10% was modified to a pointed tip at the pitch axis. This paper presents a comparative study of the effect of pointed tip on aerodynamic loads. CFD simulations were performed on both original NREL shape and pointed tip shape blades. The simulation results of pointed tip blade were compared with both experimental and simulation results of original blade. Ansys geometry modeler was used to draw the geometry and to generate the grids. Ansys CFX solver and post processor were used for simulation and calculation of the results. To predict the near wall transitional effect SST Gamma Theta turbulence model was used. Results of pressure coefficient along the chord at various blade sections of the pointed tip blade were found to be almost similar to the original NREL blade CFD results. Tangential and normal force along the span of pointed tip blade at different wind speeds showed some similarity in results compared with CFD results of original NREL blade. From the velocity contour the separation of flow with the increase of wind speed can clearly be observed. Thrust and torque effects are also observed at various wind speeds. The torque values for the pointed tip blade were found to be higher in the pre-stall and stall region but slightly lower in post-stall region. But compared to the torque values the difference in thrust at the same region is found to be negligible. Pointed tip thrust values are in better agreement at high wind speeds with respect to the experimental data. The flow separation at high wind speed is also found to be less with pointed tip blade compared to the original blade.