MW Horizontal Axis Wind Turbine Research Articles

Modified Power Curves for Prediction of Power Output of Wind Farms

Power curves are used to model power generation of wind turbines, which in turn is used for wind energy assessment and forecasting total wind farm power output of operating wind farms. Power curves are based on ideal uniform inflow conditions, however, as wind turbines are installed in regions of heterogeneous and complex terrain, the effect of non-ideal operating conditions resulting in variability of the inflow must be considered. We propose an approach to include turbulence, yaw error, air density, wind veer and shear in the prediction of turbine power by using high resolution wind measurements. In this study, two modified power curves using standard ten-minute wind speed and high resolution one-second data along with a derived power surface were tested and compared to the standard operating curve for a 2.5 MW horizontal axis wind turbine. Data from supervisory control and data acquisition (SCADA) system along with wind speed measurements from a nacelle-mounted sonic anemometer and wind speed measurements from a nearby meteorological tower are used in the models. The results show that all of the proposed models perform better than the standard power curve while the power surface results in the most accurate power prediction.

Different functionalized chord and twist distributions in aerodynamic design of HAWTs

In this study, blade element momentum (BEM) theory has been used to calculate power output and performance of 100 kW and 1 MW horizontal axis wind turbine. Riso‐A1‐21 airfoils are considered as utilized section along the blade span. Generally, Riso family of airfoils is appropriate for wind turbine application. In order to improve the accuracy of turbine performance prediction, lots of corrections have been applied on the BEM method. The aim of this research study is proposing a new procedure to introduce the chord and twist distributions by fitting different types of functions on them. Accordingly, 48 functions are selected as possible distributions for chord and twist angle profiles. These functions are selected in such a way that their behavior is close to the trend of their classical distributions. The utilized design method in this study is optimum in terms of performance and also making distribution of chord and twist functional which is more appropriate for manufacturing process. Finally, the effect of using best functions on blade aerodynamic coefficients has been studied. Results show that despite the changing chord and twist distributions from their classical trends, the aerodynamic coefficients are approximately similar to those in the classical design except in some region of blade. © 2019 American Institute of Chemical Engineers Environ Prog, 38:e13108, 2019

Upwind 2MW Horizontal Axis Wind Turbine Tower Design and Analysis

Wind energy is one of the quickest growing renewable energies in the world due to era of wind energy is smooth and non-polluting; it does now not produce any byproducts dangerous to the environment. Large scale machines are in particular nicely appropriate for wind energy. The fee of foundations doesn’t upward push in share to the dimensions of the device, and protection costs are largely impartial of the size of the system. In areas where it is difficult to find sites for more than a single turbine, a large turbine with a tall tower uses the existing wind resource more efficiently. Different subcomponents are designed depend on the purpose of the turbines among these the tower of a wind turbine helps the nacelle and the rotor and affords the necessary elevation of the rotor to hold it clear off the floor and produce it as much as the level where the wind sources are. The towers for large wind turbines are typically made from steel; however concrete towers are every so often used. The tower is normally connected to its helping basis by using a bolted flange connection or a weld. The tower constitutes a low-generation aspect whose layout is easy to optimize, and which therefore for the duration of the layout manner lends itself easily as an item for possible fee discount. This may additionally are available in useful because the fee of a tower typically establishment a sizeable a part of the entire fee of a wind turbine. The design and analysis of the tower focused on large wind turbines. It examines the result of loading on the tower, the optimum tower height and the verification of safety against bending and buckling. The buckling of 2 MW horizontal axis wind turbine tower tube with tower base diameter of 3.9m, top tower diameter of 2m and length of 80m is studied by theoretical analysis and numerical simulation by using ANSYS and MATLAB software. Based on this study the results are calculated based on theoretical and FEM method and their error is shown, buckling modes and vibrational analysis are done, shear and bending diagrams are shown, extreme loading conditions are also shown.

Wind turbine blade ice accretion: A correlation with nacelle ice accretion

This paper focuses on the meteorological icing phase of typical icing events to determine the factors that affect the ice accretion rate on a wind turbine blade. The linear mass density of ice on the nacelle of a 2 MW horizontal-axis wind turbine is estimated with a camera and is compared to the linear mass density of ice on a blade evaluated by a commercial blade ice detector (e.g. a fos4X ice detector). An automated image analysis software measures the dimension of the ice on a cylindrical tube located on the nacelle and calculates the linear mass density of the ice. The fos4X ice detector estimates the total ice load on the blade by measuring variations in the vibration frequencies of the blade. The total load is then divided by the blade length to obtain the linear density. On-site results were compared to simulations for validation. The ISO 12494 method for theoretical ice accretion on a cylindrical tube was adapted to simulate ice accretion on a rotating wind turbine blade. The main results show that wind speed and turbine rotor RPM directly influence the blade ice accretion rate. A correlation is made between blade and nacelle icing, with on-site results matching the simulation. In summary, for an operating turbine, as wind speed decreases, the rate of ice accretion on the blade increases relative to the ice accretion rate on the nacelle.

Probabilistic Design of Airfoils for Horizontal Axis Wind Turbines

We describe a probabilistic approach to design airfoils for wind energy applications. An analytical expression is derived for the probability of perturbations to the operational blade-section angle of attack. It includes the combined influence of wind shear, yaw-misalignment, and turbulence intensity. The theoretical fluctuations in angle of attack are validated against an aero-structural simulation of a 10 MW horizontal axis wind turbine, operating under different inflow conditions. Finally we incorporate the probabilistic approach into a multi-objective airfoil optimization problem, which is solved with a genetic algorithm. The results illustrate the compromise between airfoil performance for a specific angle of attack and robustness of airfoil performance over a large range of angle of attack fluctuations.

Icing distribution of rotating blade of horizontal axis wind turbine based on Quasi-3D numerical simulation

For researching on the rules of icing distribution on rotating blade of horizontal axis wind turbine, a Quasi-3-D method is proposed to research on icing on rotating blades of horizontal axis wind turbine by numerical simulation. A 2-D and 3-D method of evaluating the irregular shape of ice has been established. The model of rotating blade from a 1.5 MW horizontal axis wind turbine is used to simulate the process and shape of icing on blade. The simulation is carried out under the conditions with four important parameters including ambient temperature, liquid water content, medium volume drop diameter, and icing time. The results reveal that icing mainly happens on 50% ~ 70% of the blade surface along wingspan from tip to root of blade. There are two kinds of icing shapes including horn shape icing and streamline shape icing. The study can provide theoretical basis and numerical reference to development of anti and deicing strategy for wind turbine blades.

Analysis of horizontal axis wind turbine blade using CFD

Blade is very essential part of HAWT (horizontal axis wind turbine). Forces for Lift and drag on the blade has an important role in the wind turbine performance. The main purpose of this work is to perform CFD analysis of a blade and airfoil of wind turbine using k-ω SST model. In this present study NACA 634 -221 airfoil profile is taken for the modeling and then analysis of the blade. The lift and drag forces are calculated for the blade at different AOA (angle of attack). For present work the blade length is taken 38.98 meter, which is a redesigned blade for VESTAS V82-1.65MW horizontal axis wind turbine blade. Results obtained from simulation are compared with the experimental work found in literature.Keywords: Horizontal Axis Wind Turbine, CFD, ANSYS, Airfoil

Multi-Objective Aerodynamic and Structural Optimization of Horizontal-Axis Wind Turbine Blades

A procedure based on MATLAB combined with ANSYS is presented and utilized for the multi-objective aerodynamic and structural optimization of horizontal-axis wind turbine (HAWT) blades. In order to minimize the cost of energy (COE) and improve the overall performance of the blades, materials of carbon fiber reinforced plastic (CFRP) combined with glass fiber reinforced plastic (GFRP) are applied. The maximum annual energy production (AEP), the minimum blade mass and the minimum blade cost are taken as three objectives. Main aerodynamic and structural characteristics of the blades are employed as design variables. Various design requirements including strain, deflection, vibration and buckling limits are taken into account as constraints. To evaluate the aerodynamic performances and the structural behaviors, the blade element momentum (BEM) theory and the finite element method (FEM) are applied in the procedure. Moreover, the non-dominated sorting genetic algorithm (NSGA) II, which constitutes the core of the procedure, is adapted for the multi-objective optimization of the blades. To prove the efficiency and reliability of the procedure, a commercial 1.5 MW HAWT blade is used as a case study, and a set of trade-off solutions is obtained. Compared with the original scheme, the optimization results show great improvements for the overall performance of the blade.

Investigation of the Unsteady Flow Behaviour on a Wind Turbine Using a BEM and a RANSE Method

Analyses of the unsteady flow behaviour of a 5 MW horizontal-axis wind turbine (HAWT) rotor (Case I) and a rotor with tower (Case II) are carried out using a panel method and a RANSE method. The panel method calculations are obtained by applying the in-house boundary element method (BEM) panMARE code, which is based on the potential flow theory. The BEM is a three-dimensional first-order panel method which can be used for investigating various steady and unsteady flow problems. Viscous flow simulations are carried out by using the RANSE solver ANSYS CFX 14.5. The results of Case I allow for the calculation of the global integral values of the torque and the thrust and include detailed information on the local flow field, such as the pressure distribution on the blade sections and the streamlines. The calculated pressure distribution by the BEM is compared with the corresponding values obtained by the RANSE solver. The tower geometry is considered in the simulation in Case II, so the unsteady forces due to the interaction between the tower and the rotor blades can be calculated. The application of viscous and inviscid flow methods to predict the forces on the HAWT allows for the evaluation of the viscous effects on the calculated HAWT flows.

Integrated aero-structural optimization of wind turbines

The present work describes methods for the integrated aero-structural optimization of wind turbines. The goal of the algorithms is to identify the structural and aerodynamic design characteristics that achieve the minimum cost of energy for a given wind turbine configuration. Given the strong couplings that exist between aerodynamic and structural design choices, the methods are formulated so as to address both problems simultaneously in an integrated manner, resulting in tools that may help avoid suboptimal solutions or lengthy design loops. All methods considered herein use the same high fidelity multibody aeroservoelastic simulation environment and operate the design according to standard certification guidelines. The methods, however, differ in the way the optimization is conducted, realizing different tradeoffs amongst computational efficiency, generality, level of automation and overall robustness. The proposed formulations are exercised on the design of a conceptual 10 MW horizontal axis wind turbine, illustrating the main characteristics of the various methods.

Simulation of Damage for Wind Turbine Blades Due to Airborne Particles

A mathematical model and simulation of airborne particle collisions with a 38 m, 1.5 MW horizontal axis wind turbine blade are presented. Two types of particles were analyzed, namely insects and sand grains. Computations were performed using a two-dimensional inviscid flowfield solver coupled with a particle position code. Three locations along the blade were considered and characterized by airfoils of the DU series. The insect simulations estimated the residual debris thickness on the blade, while sand simulations computed the surface erosion rate. Results show that the impact locations along the blade depend on angle of attack, freestream velocity, airfoil shape, and particle mass. Particles were found to collide primarily at the leading edge. The volume of insect debris per unit span was maximum at r/ R = 0.75. The erosion rate due to sand was maximum on the low pressure side of the blade. An erosion rate approximately ten times higher was observed at r/ R = 0.75, as compared with the section at r/ R = 0.35. Near the leading edge, large angles of impact occurred and erosion rate had a minimum, while it reached maximum values slightly downstream where the impact angle was more skewed.

Detection of tip-vortex signatures behind a 2.5 MW wind turbine

The near-field signature of the vortical structures shed from the blade tips behind a 2.5MW horizontal axis wind turbine in a stably-stratified atmospheric boundary layer (ABL) was quantified for the first time. This study utilizes wind velocity measurements from sonic anemometers installed on a meteorological tower, which offers continuous characterization of wind conditions in the field, at elevations coinciding with the bottom, hub and top tip heights of the turbine. Using the stringent criteria on wind speed, direction and steadiness, we are able to subsample the dataset in which the sonic anemometers are positioned near the edge of the turbine wake. The spectral analysis of this dataset shows a distinct peak at the turbine rotational frequency (fT) for hub and top tip height measurements. Based on recent literature, we infer that this peak is the signature of tip-vortices, and the shift of this signature from blade-passing frequency (3fT) to fT is likely to be caused by vortex grouping phenomena. Slight changes of mean wind direction in other data samples result in the absence of the spectral peak, suggesting the very local extent of tip vortices.

A comparison between the dynamics of horizontal and vertical axis offshore floating wind turbines.

The need to further exploit offshore wind resources in deeper waters has led to a re-emerging interest in vertical axis wind turbines (VAWTs) for floating foundation applications. However, there has been little effort to systematically compare VAWTs to the more conventional horizontal axis wind turbine (HAWT). This article initiates this comparison based on prime principles, focusing on the turbine aerodynamic forces and their impact on the floating wind turbine static and dynamic responses. VAWTs generate substantially different aerodynamic forces on the support structure, in particular, a potentially lower inclining moment and a substantially higher torque than HAWTs. Considering the static stability requirements, the advantages of a lower inclining moment, a lower wind turbine mass and a lower centre of gravity are illustrated, all of which are exploitable to have a less costly support structure. Floating VAWTs experience increased motion in the frequency range surrounding the turbine [number of blades]×[rotational speed] frequency. For very large VAWTs with slower rotational speeds, this frequency range may significantly overlap with the range of wave excitation forces. Quantitative considerations are undertaken comparing the reference NREL 5 MW HAWT with the NOVA 5 MW VAWT.

LPV control for the full region operation of a wind turbine integrated with synchronous generator.

Wind turbine conversion systems require feedback control to achieve reliable wind turbine operation and stable current supply. A robust linear parameter varying (LPV) controller is proposed to reduce the structural loads and improve the power extraction of a horizontal axis wind turbine operating in both the partial load and the full load regions. The LPV model is derived from the wind turbine state space models extracted by FAST (fatigue, aerodynamics, structural, and turbulence) code linearization at different operating points. In order to assure a smooth transition between the two regions, appropriate frequency-dependent varying scaling parametric weighting functions are designed in the LPV control structure. The solution of a set of linear matrix inequalities (LMIs) leads to the LPV controller. A synchronous generator model is connected with the closed LPV control loop for examining the electrical subsystem performance obtained by an inner speed control loop. Simulation results of a 1.5 MW horizontal axis wind turbine model on the FAST platform illustrates the benefit of the LPV control and demonstrates the advantages of this proposed LPV controller, when compared with a traditional gain scheduling PI control and prior LPV control configurations. Enhanced structural load mitigation, improved power extraction, and good current performance were obtained from the proposed LPV control.

Multi-Objective Structural Optimization Design of Horizontal-Axis Wind Turbine Blades Using the Non-Dominated Sorting Genetic Algorithm II and Finite Element Method

A multi-objective optimization method for the structural design of horizontal-axis wind turbine (HAWT) blades is presented. The main goal is to minimize the weight and cost of the blade which uses glass fiber reinforced plastic (GFRP) coupled with carbon fiber reinforced plastic (CFRP) materials. The number and the location of layers in the spar cap, the width of the spar cap and the position of the shear webs are employed as the design variables, while the strain limit, blade/tower clearance limit and vibration limit are taken into account as the constraint conditions. The optimization of the design of a commercial 1.5 MW HAWT blade is carried out by combining FEM analysis and a multi-objective evolutionary algorithm under ultimate (extreme) flap-wise load and edge-wise load conditions. The best solutions are described and the comparison of the obtained results with the original design is performed to prove the efficiency and applicability of the method.

Design and Experimentation of a 1 MW Horizontal Axis Wind Turbine

In this work was carried out the aerodynamics design of a 1 MW horizontal axis wind turbine by using blade element momentum theory (BEM). The generated design was scaled and built for testing purposes in the discharge of an axial flow fan of 80 cm in diameter. Strip theory was used for the aerodynamic performance evaluation. In the numerical calculations was conducted a comparative analysis of the performance curves adding increasingly correction factors to the original equation of ideal flow to reduce the error regarding real operating values got by the experimental tests. Correction factors introduced in the ideal flow equation were the tip loss factor and drag coefficient. BEM results showed good approximation using experimental data for the tip speed ratio less than design. The best approximation of the power coefficient calculation was for tip speed ratio less than 6. BEM method is a tool for practical calculation and can be used for the design and evaluation of wind turbines when the flow rate is not too turbulent and radial velocity components are negligible.

Structural optimization procedure of a composite wind turbine blade for reducing both material cost and blade weight

A composite blade structure for a 2 MW horizontal axis wind turbine is optimally designed. Design requirements are simultaneously minimizing material cost and blade weight while satisfying the constraints on stress ratio, tip deflection, fatigue life and laminate layup requirements. The stress ratio and tip deflection under extreme gust loads and the fatigue life under a stochastic normal wind load are evaluated. A blade element wind load model is proposed to explain the wind pressure difference due to blade height change during rotor rotation. For fatigue life evaluation, the stress result of an implicit nonlinear dynamic analysis under a time-varying fluctuating wind is converted to the histograms of mean and amplitude of maximum stress ratio using the rainflow counting algorithm Miner's rule is employed to predict the fatigue life. After integrating and automating the whole analysis procedure an evolutionary algorithm is used to solve the discrete optimization problem.

Numerical Simulation on the Dynamic Stall of the Horizontal-Axis Wind Turbine

With the variation of the unsteady incoming flow and impeller rotation, when attack angles of the incoming flow is bigger than the critical angle of attack, there are unsteady separation and dynamic stall on the pressure surface of the impeller. Dynamic stalls are of common occurrence during wind turbines operation. And the aerodynamic characteristics and efficiency of wind turbine are largely affected by the dynamic stall.Therefore,the study of dynamic stall has a great significance over the optimization design of the wind turbine. The paper performs numerical simulation in the dynamic stalls of the 1.2MW horizontal-axis wind turbine, comparing the stalling difference between two-dimensional static and rotating condition. Besides, it also contrasts the stalling condition surface pressure coefficient along the different blade spanwise sections in rotating condition of the same attack angle. And the finding is that the attack angles in rotating condition is bigger than that in the two-dimensional static condition; the surface pressure coefficient is almost equivalent in static and rotating condition when attack angle is smaller than stalling angle; the peak of negative pressure at the leading edge of blade in rotating condition is far bigger than the peak of negative pressure in static condition when attack angle is smaller than static stalling angle. Airflow stall delay occurs when near the blade root. Stall delay phenomenon gradually weakened along the direction of blade radius.

Modal Analysis of Wind Turbine Blades Based on ANSYS Modeling

The modal analysis is an approximate method to study the dynamic characteristics of the structure, the modal is the natural vibration characteristics of the structure, each modal has a specific natural frequency, damping ratios and mode shapes. This thesis will take 1.2MW horizontal axis wind turbine blade for example, and use parametric language APDL of ANSYS for directly modeling, then set the basic parameters of the material, mesh and discuss modal analysis, lastly conduct a detailed analysis of the results.

The Analysis of the Aerodynamic Character and Structural Response of Large-Scale Wind Turbine Blades

A process of detailed CFD and structural numerical simulations of the 1.5 MW horizontal axis wind turbine (HAWT) blade is present. The main goal is to help advance the use of computer-aided simulation methods in the field of design and development of HAWT-blades. After an in-depth study of the aerodynamic configuration and materials of the blade, 3-D mapping software is utilized to reconstruct the high fidelity geometry, and then the geometry is imported into CFD and structure finite element analysis (FEA) software for completely simulation calculation. This research process shows that the CFD results compare well with the professional wind turbine design and certification software, GH-Bladed. Also, the modal analysis with finite element method (FEM) predicts well compared with experiment tests on a stationary blade. For extreme wind loads case that by considering a 50-year extreme gust simulated in CFD are unidirectional coupled to the FE-model, the results indicate that the maximum deflection of the blade tip is less than the distance between the blade tip (the point of maximum deflection) and the tower, the material of the blade provides enough resistance to the peak stresses the occur at the conjunction of shear webs and center spar cap. Buckling analysis is also included in the study.