Size Of Wind Turbines Research Articles

Aerodynamic and structural optimization of wind turbine blade considering natural of frequencies of vibration

In recent years, wind energy has garnered significant global attention due to its immense energy and environmental potential, leading to a substantial increase in both capacity and size of wind turbines, evolving from a nominal power of 75kW to 7.5MW and a rotor diameter of 17m to over 125m. However, this scaling-up has introduced new challenges related to instability caused by the aeroelastic effect, which stems from the interplay between wind loads and the structural deformation of wind turbine blades. Consequently, an effective model necessitates well-defined aerodynamic and structural components. Yet, the complex geometric shapes of turbines demand extensive computational resources for analysis, particularly given their composite materials and intricate configurations.Various research institutions, including NREL, DTU, and ECN, have developed aeroelastic tools for wind turbine studies, integrating structural and aerodynamic modules. The prevalent approach employs the BEMT (Blade Element Moment Theory) model for aerodynamic simulation and FEM models for structural dynamic analysis. The BEMT model partitions the blade into elements to evaluate aerodynamic loads based on local characteristics. This amalgamation offers an efficient solution for predicting element performance parameters. Additionally, the BEM model provides a computationally economical alternative to more intricate models, making it a cost-effective choice for wind turbine analysis and a cheaper tool compared to robust methods, like CFD.This work proposes an aerodynamic optimization method constrained by the structural model, focusing on the natural vibration frequencies of wind turbine blades. The methodology comprises three phases: defining the aerodynamic model using the CCBlade code in Julia Language, implementing the structural analysis method via FEM for rotating Timoshenko beams in MATLAB, and integrating the aerodynamic and structural models on a multi-objective optimization platform. Evolutionary algorithms were employed to enhance wind turbine energetic efficiency and avoid structural instabilities within this study. By leveraging advancements in modeling and optimization techniques, the aim is to contribute to the development of more efficient and reliable wind turbines, further promoting the transition to clean and sustainable energy sources.

Computational Simulation of a Plane Channel with Spalart-Allmaras Turbulence Model and Fourier Pseudo-Spectral Method

The majority of fluid flows encountered in nature and practical applications are turbulent, characterized primarily by a broad range of scales, from large structures influenced by flow geometry to small structures determined by fluid viscosity. Turbulence is a topic of significant relevance in engineering across various sectors. For instance, airflow over terrestrial surfaces, where roughness varies considerably, is critical for predicting the potential and sizing of wind turbines and wind farms.In this context, this study proposes extending the IMERSPEC methodology to conduct simulations of turbulent flows based on Reynolds-averaged Navier-Stokes equations, utilizing the Spalart-Allmaras turbulence model. The IMERSPEC methodology integrates the Fourier Pseudo-Spectral Method with the Immersed Boundary Method, offering excellent numerical accuracy and computational efficiency compared to other high-order techniques, attributed to the efficient use of Fast Fourier Transform (FFT) and the pressure term projection method in Fourier space.The numerical results obtained through this approach are validated against experimental data and Direct Numerical Simulations (DNS) for flow in a flat channel at a Reynolds number of 40,000. This comparative analysis will facilitate assessing the effectiveness and precision of the proposed method in capturing turbulent flow characteristics, with potential applications in aerodynamic and fluid dynamic engineering studies.

Flow Separation Control and Aeroacoustic Effects of a Leading-Edge Slat over a Wind Turbine Blade

To enable wind energy to surpass fossil fuels, the power-to-cost ratio of wind turbines must be competitive. Increasing installation capacities and wind turbine sizes indicates a strong trend toward clean energy. However, larger rotor diameters, reaching up to 170 m, introduce stability and aeroelasticity concerns and aerodynamic phenomena that cause noise disturbances. These issues hinder performance enhancement and social acceptance of wind turbines. A critical aerodynamic challenge is flow separation on the blade’s suction side, leading to a loss of lift and increased drag, ultimately stalling the blade and reducing turbine performance. Various active and passive flow control techniques have been studied to address these issues, with passive techniques offering the advantage of no external energy requirement. High-lift devices, such as leading-edge slats, are promising in improving aerodynamic performance by controlling flow separation. This study explores the geometric parameters of slats and their effects on wind turbine blades’ aerodynamic and acoustic performance. Using an adequate turbulence model at Re = 106 for angles of attack from 14° to 24°, 77 slat configurations were evaluated. Symmetric slats showed superior performance at high angles of attack, while slat chord length was inversely proportional to aerodynamic improvement. A hybrid method was employed to predict noise, revealing slat-induced modifications in eddy topology and increased low- and high-frequency noise. This study’s main contribution is correlating slat-induced aerodynamic improvements with their acoustic effects. The directivity reveals a 10–15 dB reduction induced by the slat at 1 kHz, while the slat induces higher noise at higher frequencies.

Definition of a Baseline Rotor Design for a 25MW Floating Offshore Wind Turbine

Abstract Wind turbine sizes have grown rapidly in recent years with machine ratings of 15-16 MW available from multiple manufacturers for offshore wind turbines. While the industry advances large-scale turbine designs, offshore developers have initially focused on siting in shallow waters on bottom-fixed foundations; however, eyes are also on deep-water locations where floating systems are required. The present study presents the definition for an initial baseline rotor design at 25 MW scale, designed for a floating offshore system. The purpose of this paper is to document this 25 MW blade definition for use as a reference design for future floating wind technology development by industrial and academic researchers and developers. As this is an initial reference design, some opportunities (and plans) for further mass or cost reduction are also noted. In summary, the paper documents the initial baseline rotor design including aerodynamic and structural design of the rotor blades, along with key details about the control system and floating system designs for the floating 25 MW wind turbine system.

Simulation of Small-Scale Wind Turbine Performance with Taperless Blade

Utilizing wind turbines typically involves a large-scale project with extremely huge wind turbine sizes. Because of this, the use of wind turbines in Indonesia is not yet very common and widespread among the community. Basically, a wind turbine has blades; the number of blades on a wind turbine can affect the overall performance of the turbine. Large-scale wind turbine projects usually implement tapered blades, while small-scale projects use taperless blades. Therefore, in this research, a horizontal-axis wind turbine with taperless blades will be used as the object of study to find out the optimal number of taperless blades that can achieve the best performance of a small-scale wind turbine category. The method used in this research is to design a horizontal axis wind turbine equipped with taperless blades with varying numbers of blades, namely three blades, four blades, and five blades, and then simulate the turbine's performance with wind speeds of 3 m/s to 6 m/s. The present research found that the greater the number of turbine blades tends to produce greater power. This is proven by research results, where the highest power in a small-scale horizontal axis wind turbine produces a power of 20,30 Watts in a 5-blade turbine variation for the wind speed of 6 m/s.

Standardization of Turbine Design and Installation Vessels to Accelerate the Offshore Wind Industry in the United States

Offshore wind energy has gained attention as a promising renewable energy source with many benefits, including clean, sustainable, and scalable electricity production. Despite the vast potential for offshore wind production in the United States, the country lags in its development. The industry struggles with supply chain challenges related to the complex logistics around the design and construction of many component parts, installation and maintenance vessels, and shipyards that can accommodate the massive turbine components before installation. These challenges are complicated by the rapid increase in size of offshore wind turbines to achieve higher power generation, which are not easily handled by other parts of the supply chain. The US lacks access to wind turbine installation vessels (WTIVs), particularly those that can install very large turbines. To address these issues, we propose policy options to the US Bureau of Ocean Energy Management of the Department of Interior and the US Department of Energy to spearhead standardization in this sector of the economy by exploring standardization of maximum turbine size, investment in WTIVs, or allowance of unrestricted or market-driven offshore wind farm development. These options have great potential to enable growth in the offshore wind energy sector in the US and achieve the federal government's goal of 30 GW of offshore wind energy by 2030.

A new multi-objective-stochastic framework for reconfiguration and wind energy resource allocation in distribution network incorporating improved dandelion optimizer and uncertainty

Improving the reliability and power quality of unbalanced distribution networks is crucial for ensuring consistent and reliable electricity supply. In this research, multi-objective optimization of unbalanced distribution networks reconfiguration integrated with wind turbine allocation (MORWTA) is implemented considering uncertainties of networks load, and also wind power incorporating a stochastic framework. The multi-objective function is defined by the minimization of power loss, voltage sag (VS), total harmonic distortion (THD), voltage unbalance (VU), energy not-supplied (ENS), system average interruption frequency index (SAIFI), system average interruption duration index (SAIDI), and momentary average interruption frequency (MAIFI). A new improved dandelion optimizer (IDO) with adaptive inertia weight is recommended to counteract premature convergence to identify decision variables, including the optimal network configuration through opened switches and the best location and size of wind turbines in the networks. The stochastic problem is modeled using the 2m + 1 point estimate method (PEM) combined with K-means clustering, taking into account the mentioned uncertainties. The proposed stochastic methodology is implemented on three modified 33-bus, and unbalanced 25-, and 37-bus distribution networks. The results demonstrated that the MORWTA enhanced all study objectives in comparison to the base networks. The results also demonstrated that the IDO had superior capability to solve the deterministic- and stochastic-MORWTA in comparison to the conventional DO, grey wolf optimizer (GWO), particle swarm optimization (PSO), and arithmetic optimization algorithm (AOA) in terms of achieving greater objective value. Moreover, the results demonstrated that when the stochastic-MORWTA model is considered, the power loss, VS, THD, VU, ENS, SAIFI, SAIDI, and MAIFI are increased by 18.35%, 9.07%, 10.43%, 12.46%, 11.90%, 9.28%, 12.16% and 14.36%, respectively for 25-bus network, and also these objectives are increased by 12.21%, 10.64%, 12.37%, 9.82%, 14.30%, 12.65%, 12.63% and 13.89%, respectively for 37-bus network compared to the deterministic-MORWTA model, which is related to the defined uncertainty patterns.

Influence of offshore wind turbine size in levelised cost of energy

Offshore wind energy is developing rapidly in recent years. Within the offshore wind energy industry, the main advance that has occurred has been the wind turbine growth. In fact, the offshore turbines have changed from small turbines adapted to the marine environment to turbines that currently range between 16~18 MW. This increase has been done in order to cut down costs and get longer production of wind energy, consequently, reducing the levelized cost of energy. The current mechanisms for assigning marine sites are based on successive auctions organized by government agencies. In some countries, these auctions are carried out through reverse bidding, that is, they are awarded to the promoters who present the lowest sales price for the energy generated or, in the case of other countries, that price marked in the auction has a partial weight of 60%~80% in the final ranking. Other countries organize a second type of reverse auction to award subsidies, which, being limited, are awarded to the promoters who present the lowest energy sales price. In this article, a comparative study developed for evaluation of the value of levelized cost of energy, as a result of bigger nameplate capacity of the offshore wind turbines. The results show that the bigger turbine capacity, the lower the levelized cost of energy is obtained.

Aerodynamic performance and flow field characteristics of wind turbines under shear incoming flow conditions

Abstract With the large size of the units, wind farms are evaluated in order to improve the accuracy of the incoming flow measurement and to improve the unit control strategy. In this paper, the turbulent wind field generated by autoregressive linear filtering using a large eddy simulation turbulence model is used to study the wind speed-induced zone under shear incoming flow conditions. At the same time, the wake and aerodynamic performances of the wind turbine under different incoming flow conditions are investigated, and conclusions are obtained. 1) The larger the shear index is, the larger the amplitude is at the first frequency component of the power and the thrust, and the larger the fatigue load is for the wind turbine. 2) For the wind turbine wake flow in the case of smaller wind turbine size, the wake velocity profiles at different shear indices cross and overlap in the transition and far wake regions. At position 0.5 D, the turbulence profiles with different shear indices basically overlap; the larger the shear index is, the more intense the wake flow exchange is and the greater the turbulence intensity in the wake region will be. 3) For the wind speed-induced region, at position −0.1 D, the incoming flow velocity distribution is subject to the combined effect of induction and shear, and the induction effect of the wind turbine wheel is a little larger. The larger the shear index, the greater the turbulence intensity.

Measurement and quantification of low frequency noise emissions from utility-scale wind turbines

In wind turbine project permit hearings and other proceedings, concerns are often raised regarding low frequency noise (LFN). As the size of utility-scale wind turbines continues to grow, the concern over LFN may only intensify. This paper describes the measurement and quantification of low frequency noise emissions from utility-scale wind turbines, specifically in the 16, 31.5, and 63 Hertz octave bands. Accurate measurement of wind turbine noise emissions, particularly in the 16 Hertz octave band, is challenging due to interference from wind-induced noise. Topics covered include choice of windscreen, the effectiveness of shutdown tests, data filtering techniques, and the comparison of measured levels at multiple wind turbine sites to levels predicted using manufacturer's data and the ISO 9613-2:1996 method.

Intelligent optimal sitting and sizing of distributed resources in presence of renewable energy and fuel cells based on reliability and emission factors

As the integration of renewable energy sources—such as wind, solar, and fuel cells—into power systems increases, challenges related to system reliability and cost efficiency become paramount. This paper examines the reliability of a standard power network composed of diverse energy sources including wind turbines, solar panels, fuel cells, batteries, and diesel generators. This paper proposes a novel hybrid optimization approach utilizing a Grey Wolf Optimizer combined with another advanced algorithm to minimize the total cost of energy production, inclusive of emission penalties for CO2, NO2, and SO2. The proposed approach is tested on IEEE 57-bus and IEEE 118-bus systems, demonstrating significant improvements over existing algorithms. Quantitative results show that our method reduces the total cost by up to 18 % and enhances system reliability by reducing voltage deviations in various scenarios by 12 %. The paper also provides insights into the optimal sizing and placement of wind turbines, photovoltaics, diesel generators, and fuel cells under different emission constraints (15000, 25000, and 45000 kg), further emphasizing the flexibility and effectiveness of our method in addressing environmental and economic challenges in modern power systems.

Exploratory Study on the Application of Graphene Platelet-Reinforced Composite to Wind Turbine Blade.

With the growth of the wind energy market and the increase in the size of wind turbines, the demand for advanced composite materials with high strength and low density for wind turbine blades has become imperative. Graphene platelets (GPLs) stand out as highly premising reinforcements due to their exceptional physical properties, resulting in their widespread adoption in the composite industry in recent years. The present study aims to analyze the applicability of a graphene-platelet-reinforced composite (GPLRC) to wind turbine blades in terms of structural performance. A finite element blade model is constructed by referring to the National Renewable Energy Laboratory (NREL) 5 MW wind turbine, and its reliability is verified through a convergence test. The performance of the wind turbine blade is quantitatively examined in terms of the deflection and stress, natural frequencies, and twist angle. The applicability of the GPL-reinforced wind blade is explored through a comparison with wind blades manufactured with glass fiber and carbon nanotubes (CNTs). The comparison indicates that the performance of a wind blade can be remarkably improved by reinforcing with GPLs instead of traditional fillers, and the weight of not only the wind blade itself but also the wind turbine system can be remarkably reduced. The present results can be useful in the development of next-generation high-strength lightweight wind turbine blades.

Investigation of Upward Leader Development Characteristics by Two Kinds of Charge Density Models in Wind Turbines

ABSTRACTThe upward discharge is a significant factor threatening the operation of wind farms. This paper investigates the inception and development of upward leaders of wind turbines' tip, where blade rotation prevents charge accumulation, using charge density models from laboratory discharges and artificially triggered lightning. The results indicate that larger return stroke currents create higher spatial potentials, and slower downward leader speeds allow for longer development time, favoring the development of upward leaders. As wind turbine sizes increase, the rotation of the blade tips resembles artificially triggered lightning, and the long air gap discharge model may underestimate the development of upward leaders. Calculations from the artificially triggered lightning model reveal improved upward leader formation when further laterally away from the downward leader within a certain distance, elucidating why multiple upward leaders are frequently observed around turbines. The striking distance and attractive radius are largely determined by the development of upward leaders. The absence of corona charge shielding at blade tips means upward leader inception is independent of downward leader velocity, emphasizing downward leaders' significant influence on turbines. Thus, the formula for estimating a wind turbine's lightning incidence requires integrating the return stroke current and velocity of the downward leader.

Life Cycle Environmental Impacts of Wind Turbines: A Path to Sustainability with Challenges

This study aims to evaluate in detail the environmental impacts of the turbines used for electricity generation by wind energy, from a life cycle perspective. For this purpose, a comprehensive literature review is conducted and the life cycle environmental impacts of two sizes of wind turbines, namely 3.6 and 4.8 MW, in Turkey are analyzed. Sustainability studies, especially life cycle assessment (LCA) findings, yield healthy results only if the data used are site-specific. The system has been modeled using GaBi software and the Ecoinvent database. The functional unit is defined as 1 kWh of generated electricity. The impacts have been estimated using the CML 2 Baseline 2001 method. The 4.8 MW turbine has lower environmental impacts than the other turbine. The construction of wind turbines has the greatest share of the environmental impacts of all the options considered. Recycling materials at the end of plant life can reduce unwanted environmental impacts by up to 49%. Similar studies based on site-specific data will help to inform electricity producers and policymakers about wind energy’s current impacts and environmental hotspots. Conducting analogous studies is critical to reducing the environmental impacts of wind energy, which will play an important part in the future of the energy sector.

Boosting prairie dog optimizer for optimal planning of multiple wind turbine and photovoltaic distributed generators in distribution networks considering different dynamic load models

Deploying distributed generators (DGs) supplied by renewable energy resources poses a significant challenge for efficient power grid operation. The proper sizing and placement of DGs, specifically photovoltaics (PVs) and wind turbines (WTs), remain crucial due to the uncertain characteristics of renewable energy. To overcome these challenges, this study explores an enhanced version of a meta-heuristic technique called the prairie dog optimizer (PDO). The modified prairie dogs optimizer (mPDO) incorporates a novel exploration phase inspired by the slime mold algorithm (SMA) food approach. The mPDO algorithm is proposed to analyze the substantial effects of different dynamic load characteristics on the performance of the distribution networks and the designing of the PV-based and WT-based DGs. The optimization problem incorporates various operational constraints to mitigate energy loss in the distribution networks. Further, the study addresses uncertainties related to the random characteristics of PV and WT power outputs by employing appropriate probability distributions. The mPDO algorithm is evaluated using cec2020 benchmark suit test functions and rigorous statistical analysis to mathematically measure its success rate and efficacy while considering different type of optimization problems. The developed mPDO algorithm is applied to incorporate both PV and WT units, individually and simultaneously, into the IEEE 69-bus distribution network. This is achieved considering residential, commercial, industrial, and mixed time-varying voltage-dependent load demands. The efficacy of the modified algorithm is demonstrated using the standard benchmark functions, and a comparative analysis is conducted with the original PDO and other well-known algorithms, utilizing various statistical metrics. The numerical findings emphasize the significant influence of load type and time-varying generation in DG planning. Moreover, the mPDO algorithm beats the alternatives and improves distributed generators' technical advantages across all examined scenarios.

Analysis and evaluation of two reference LiDAR-assisted control designs for wind turbines

LiDAR-assisted wind turbine control holds promise in reducing structural loads and enhancing rotor speed regulation. However, a research gap exists in the practicality and limitations of commercially available fixed-beam LiDARs for large turbines and evaluating commonly employed LiDAR-assisted feedforward approaches. This study addresses these gaps by examining the implications of utilizing fixed-beam LiDARs in two wind turbine sizes and two reference LiDAR-assisted control strategies. A comprehensive evaluation considers coherence variations, uncertainties related to inaccurate pitch angle mapping with the upcoming wind speed, and their combined impact on load reduction. Numerical simulations reveal that an excessively low cut-off frequency in the low-pass filter can compromise preview time compensation. This is problematic in larger turbines, where coherence with limited LiDAR beams is inferior compared to smaller wind turbines, which deteriorates the effectiveness of the LiDAR-assisted control. Among the reference LiDAR-assisted control methods, the evaluation indicates the Schlipf approach has greater load reduction independence, while Bossanyi’s approach, which uses measurement of current blade pitch, yields positive results with fine-tuned baseline controllers. However, allowing baseline controller-induced frequencies to propagate into the controller may increase system excitation at certain frequencies due to the use of the actual pitch angle for feedforward pitch rate calculation.

Determination of annual energy production loss due to erosion on wind turbine blades

Increasing size of the modern wind turbines amplifies the issues of leading-edge erosion, especially on the outboard sections of the blades, impacting both their structural integrity and aerodynamic efficiency. Predicting and detection of the aerodynamic losses which occurs before a noticeable structural degradation on the blade can be crucial for operational predictive maintenance strategies to avoid significant loss production. This paper presents the results from the collaborative study between DTU and CENER in order to investigate the influence of leading-edge erosion on wind turbine aerodynamic performance. For this purpose, three distinct erosion scenarios are analyzed by means of computational fluid dynamics (CFD), both 2D and 3D, blade-element momentum theory (BEM) based solver (OpenFAST) and a Simplified Aerodynamic Loss Tool (SALT). The results from previous studies are used as an input for these tools, with outputs from each tool complementing and reinforcing one another. Furthermore, annual energy production (AEP) reductions due to leading-edge erosion across these tools are compared and validation of the SALT tool is presented. It is observed that the thrust and power losses from both CFD and OpenFAST exhibit comparable results and for a severe erosion case, spanning the last third of the blade, results in a 4.3 % reduction in the annual energy production.

Multiscale-simulation method for the wear behaviour of planetary journal bearings in wind turbine gearboxes

Wind energy is one of the most important renewable energy sources. To maintain competitiveness wind energy needs to be cost effective. Increasing the performance of wind turbines can help to reduce the total cost of wind energy. The power output can be increased by an increase in turbine rotor size since the power increases disproportionately with the rotor diameter. The increase in rotor size inherently comes with an increase in overall wind turbine size to cope with the increasing loads. Since the nacelle weight cannot be increased without limitation, e.g. due to the effect on the tower and costs, an increase in power density is necessary. The usage of journal bearings instead of rolling bearings for the application in planetary gearboxes in wind turbines is one way to increase the power density and reliability of the drivetrain. When designed and operated correctly, journal bearings have a longer service lifetime than rolling bearings. Wear simulations aid in the design of journal bearings. This work presents a simulation method for the wear prediction of planetary journal bearings in wind turbine gearboxes. The method is validated with measurements on a component test rig. The transfer to the wind turbine gearbox is shown by means of simulation.

Decarbonizing airport using solar and wind farm: A case of Biratnagar, Nepal

Airports strive for a greener energy transition to minimize their carbon footprint and greenhouse gas emissions. The installation of solar or wind turbines is gaining significance among stakeholders working in sustainable airports. This study focuses on developing Biratnagar airport as a completely greener airport by identifying suitable sites for installing Solar and wind farms within the premises without compromising on safety aspects, including glare occurrence and environmental and electrical safety. PVSYST V6.8.7 and HOMER V2.81 software are used to simulate the performance of PV and wind turbine power plants. Three sizes of Vertical axis wind turbines (VAWT) of EOLO 15 kW, Tree tree-shaped wind Turbine (TSWT) 58.5 kW and TSWT 585 kW have been used for the Simulation. A sensitivity analysis of various parameters, including interest rates, wind speed, and wind turbine types, has been carried out to study the cost of energy generation in grid-connected mode. According to the study, a 157 kWp solar PV power plant is sufficient for Biratnagar Airport to become Nepal's first fully green-powered airport. The project's Levelized Cost of Electricity (LCOE) equals 0.141 $/kWh if wind energy is used to supply part of the electricity with the annual wind electricity production of 23,184 kWh. The combined 15 kW wind turbine-grid scenario is superior to the grid scenario for wind speeds of more than nine m/s and interest rates of less than 10 %. These findings increase airport authorities' and stakeholders' confidence in the investment in greener airports.

Characterization of Oscillatory Response of Light-Weight Wind Turbine Rotors under Controlled Gust Pulses

Given the industry-wide trend of continual increases in the size of utility-scale wind turbines, a point will come where reductions will need to be made in terms of the weight of the turbine’s blades to ensure they can be as long as needed without sacrificing structural stability. One such technique that may be considered is to decrease the material used for the shell and spar cap. While this will solve the weight issue, it creates a new one entirely—less material for the shell and spar cap will in turn create blades that are more flexible than what is currently used. This article aims to investigate how the oscillatory response of light-weight wind turbine rotors is affected by these flexibility changes. The object of our study is the Sandia National Lab National Rotor Testbed (SNL-NRT) wind turbine, which the authors investigated in the course of a research project supported by SNL. Using a reduced-order characterization (ROC) technique based on controlled gust pulses, introduced by the authors in a previous work, the aeroelastic dynamics of the NRT’s original baseline blade design and several of its flexible variations were studied via numerical simulations employing the CODEF multiphysics suite. Results for this characterization are presented and analyzed, including a generalization of the ROC of the SNL-NRT oscillatory dynamics to larger machines with geometrical similarity. The latter will prove to be valuable in terms of extrapolating results from the present investigation and other ongoing studies to the scale of current and future commercial machines.