Importance of Shear in Site Assessment of Wind Turbine Fatigue Loads

2018 ◽  
Vol 140 (4) ◽  
Author(s):  
René M. M. Slot ◽  
Lasse Svenningsen ◽  
John D. Sørensen ◽  
Morten L. Thøgersen
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Structural Reliability ◽  
Turbine Blades ◽  
Structural Response ◽  
Fatigue Loading ◽  
Worst Case ◽  
Shear Model ◽  
Wind Climate

Wind turbines are subjected to fatigue loading during their entire lifetime due to the fluctuating excitation from the wind. To predict the fatigue damage, the design standard IEC 61400-1 describes how to parametrize an on-site specific wind climate using the wind speed, turbulence, wind shear, air density, and flow inclination. In this framework, shear is currently modeled by its mean value, accounting for neither its natural variance nor its wind speed dependence. This very simple model may lead to inaccurate fatigue assessment of wind turbine components, whose structural response is nonlinear with shear. Here we show how this is the case for flapwise bending of blades, where the current shear model leads to inaccurate and in worst case nonconservative fatigue assessments. Based on an optimization study, we suggest modeling shear as a wind speed dependent 60% quantile. Using measurements from almost one hundred sites, we document that the suggested model leads to accurate and consistent fatigue assessments of wind turbine blades, without compromising other main components such as the tower and the shaft. The proposed shear model is intended as a replacement to the mean shear, and should be used alongside the current IEC models for the remaining climate parameters. Given the large number of investigated sites, a basis for evaluating the uncertainty related to using a simplified statistical wind climate is provided. This can be used in further research when assessing the structural reliability of wind turbines by a probabilistic or semiprobabilistic approach.

scholarly journals A Simplified Morphing Blade for Horizontal Axis Wind Turbines

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
Weijun Wang ◽  
Stéphane Caro ◽  
Fouad Bennis ◽  
Oscar Roberto Salinas Mejia
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Energy Production ◽  
Turbine Blades ◽  
Wind Turbine Blades ◽  
Annual Average ◽  
Average Wind Speed ◽  
Pitch Control ◽  
Average Wind

The aim of designing wind turbine blades is to improve the power capture ability. Since rotor control technology is currently limited to controlling rotational speed and blade pitch, an increasing concern has been given to morphing blades. In this paper, a simplified morphing blade is introduced, which has a linear twist distribution along the span and a shape that can be controlled by adjusting the twist of the blade's root and tip. To evaluate the performance of wind turbine blades, a numerical code based on the blade element momentum theory is developed and validated. The blade of the NREL Phase VI wind turbine is taken as a reference blade and has a fixed pitch. The optimization problems associated with the control of the morphing blade and a blade with pitch control are formulated. The optimal results show that the morphing blade gives better results than the blade with pitch control in terms of produced power. Under the assumption that at a given site, the annual average wind speed is known and the wind speed follows a Rayleigh distribution, the annual energy production of wind turbines was evaluated for three types of blade, namely, morphing blade, blade with pitch control and fixed pitch blade. For an annual average wind speed varying between 5 m/s and 15 m/s, it turns out that the annual energy production of the wind turbine containing morphing blades is 24.5% to 69.7% higher than the annual energy production of the wind turbine containing pitch fixed blades. Likewise, the annual energy production of the wind turbine containing blades with pitch control is 22.7% to 66.9% higher than the annual energy production of the wind turbine containing pitch fixed blades.

Application of a Genetic Algorithm to Wind Turbine Design

1996 ◽  
Vol 118 (1) ◽  
pp. 22-28 ◽  
Author(s):  
M. S. Selig ◽  
V. L. Coverstone-Carroll
Keyword(s):  
Genetic Algorithm ◽  
Wind Speed ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Energy Production ◽  
Turbine Blades ◽  
Hybrid Approach ◽  
Optimization Method ◽  
Average Wind Speed ◽  
Average Wind

This paper presents an optimization method for stall-regulated horizontal-axis wind turbines. A hybrid approach is used that combines the advantages of a genetic algorithm with an inverse design method. This method is used to determine the optimum blade pitch and blade chord and twist distributions that maximize the annual energy production. To illustrate the method, a family of 25 wind turbines was designed to examine the sensitivity of annual energy production to changes in the rotor blade length and peak rotor power. Trends are revealed that should aid in the design of new rotors for existing turbines. In the second application, five wind turbines were designed to determine the benefits of specifically tailoring wind turbine blades for the average wind speed at a particular site. The results have important practical implications related to rotors designed for the Midwestern US versus those where the average wind speed may be greater.

Prediction of Aerodynamic Loadings and Power Productions of Wind Turbines in Wake by Numerical Simulation

2014 ◽  
Author(s):  
Nina Zhou ◽  
Xiangyu Gao ◽  
Jun Chen
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Turbine Blades ◽  
Vertical Direction ◽  
Fatigue Loading ◽  
Lower Velocity ◽  
Velocity Deficit ◽  
Shadow Effect ◽  
Inflow Conditions ◽  
Tower Shadow

In this paper, the Large Eddy Simulation coupled with the Actuator line (LES-AL) method is employed to analyze the performance of the downstream wind turbine under varying inflow conditions. A direct LES, which solves the flow physics around turbine blades using exact three-dimensional blade geometries, is carried out to predict the aerodynamic loadings and output powers of the downstream turbines by prescribing the wake profiles predicted by LES-AL simulation as the inflow boundary conditions. The upstream tower shadow effect is presented in this study by carrying out two simulations with no tower wake and real tower wake inflow conditions. The LES results show that both the power and aerodynamic loading components fluctuate periodically due to the presence of upstream tower. In additional, an additional force component is exerted on the downstream wind turbine in the vertical direction (z direction). The increase in velocity deficit in wake in behind the downstream turbine is due to a sequence of momentum extraction by the wind turbines. The tower shadow effect accumulates and generates lower velocity regions in wake, and the low velocity regions shift due to the rotational motion of wake vortex. The development of the asymmetric and velocity deficit region has the potential to generate more unstable power output and fatigue loading on turbines in further downstream.

scholarly journals Pengaruh Jumlah Sudu Terhadap Kinerja Turbin Savonius

2019 ◽  
Vol 6 (1) ◽  
pp. 64
Author(s):  
Jamal Jamal
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Research Method ◽  
Turbine Blades ◽  
Wind Speeds ◽  
Study Results ◽  
Torque Moment ◽  
Savonius Wind Turbine ◽  
Low Wind Speeds

Savonius wind turbines are wind turbines that canoperate at low wind speeds, this type of turbine is very suitable tobe used in several places in Indonesia. The research aims toimprove the performance of the Savonius wind turbine withvariations in the number of turbine blades as well as variations inthe velocity of wind speed. The research method wasexperimental where wind turbine testing was carried out withvariations in the number of turbine blades with number of 2, 3and 4 blades, other variations carried out were wind speed at 3.5;4,5; 5.5 and 6.5 m/s. The study results show that the 2-bladeturbine produces greater rotation, but the torque moment islower than the 3 and 4 blade turbines, this can be seen in the lowefficiency of the 2 blade turbine at low wind speeds with highloading. At 3.5 m / s wind turbines 2 blade turbines haveefficiency that tends to be the same as 3 and 4 blade turbines upto 0.5 N but at loads of 0.6 - 1.2 N 2 blade turbines have lowerefficiency, while at wind speeds of 4.5 - 6.5 m / s 2 blade turbineshave greater efficiency than turbines 3 and 4 blades up to a loadof 1.2 N but if the load is added then the efficiency of 2-bladeturbines can be smaller than efficiency 3 and 4-blade.

Study of the Textile Composite Adaptive Blade of Small Wind Turbine

2011 ◽  
Vol 332-334 ◽  
pp. 828-832
Author(s):  
Xiao Dong Chen ◽  
Mei Ling Kuang ◽  
Ya Ming Jiang
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Carbon Fibers ◽  
Wind Turbines ◽  
Power Output ◽  
Turbine Blades ◽  
Main Body ◽  
Wind Turbine Blades ◽  
Textile Composite ◽  
Small Wind Turbine

This paper is mainly to design the small wind turbine blades to make the wind turbines have automatic braking ability. This study has two main aspects, including choosing the reinforced materials and designing the structure of the blades. According to the fiber hybrid principle, carbon fibers are employed in the main stress area of the blades and other area using glass fiber. At the same time, Aramid fibers are mixed in every area of the blade in order to enhance the tenacity of the blade. The other work is designing the structure of the blade with big main body and small abdomen which twists easily. At the designed wind speed, the power output reaches its rated capacity. Above this wind speed, turbine blades twist to adapt to wind speed and make the rotor solidity of wind turbine declined. While the wind speed changes and becomes small, the torsion of wind turbines’ blades turns back. Thus the wind turbines’ rotor solidity becomes greater and power output increases. So at a certain speed ( 36m/s), the wind turbine can adjusts itself to control the power output keeps on a certain level. And then it brakes by itself.

scholarly journals Power and Wind Shear Implications of Large Wind Turbine Scenarios in the US Central Plains

Energies ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 4269 ◽  
Author(s):  
Rebecca J. Barthelmie ◽  
Tristan J. Shepherd ◽  
Jeanie A. Aird ◽  
Sara C. Pryor
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Wind Shear ◽  
International Energy Agency ◽  
Fatigue Loading ◽  
Vertical Shear ◽  
Central Plains ◽  
Energy Agency ◽  
Wind Speeds

Continued growth of wind turbine physical dimensions is examined in terms of the implications for wind speed, power and shear across the rotor plane. High-resolution simulations with the Weather Research and Forecasting model are used to generate statistics of wind speed profiles for scenarios of current and future wind turbines. The nine-month simulations, focused on the eastern Central Plains, show that the power scales broadly as expected with the increase in rotor diameter (D) and wind speeds at hub-height (H). Increasing wind turbine dimensions from current values (approximately H = 100 m, D = 100 m) to those of the new International Energy Agency reference wind turbine (H = 150 m, D = 240 m), the power across the rotor plane increases 7.1 times. The mean domain-wide wind shear exponent (α) decreases from 0.21 (H = 100 m, D = 100 m) to 0.19 for the largest wind turbine scenario considered (H = 168 m, D = 248 m) and the frequency of extreme positive shear (α > 0.2) declines from 48% to 38% of 10-min periods. Thus, deployment of larger wind turbines potentially yields considerable net benefits for both the wind resource and reductions in fatigue loading related to vertical shear.

SHAPING OF AN AUTONOMOUS POWER SYSTEM FOR GUARANTEED POWER SUPPLY WITH THE PREDOMINANCE WIND ENERGY

2018 ◽  
pp. 28-50
Author(s):  
S. G. Ignatiev ◽  
S. V. Kiseleva
Keyword(s):  
Energy Storage ◽  
Wind Speed ◽  
Wind Energy ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Energy Demand ◽  
Diesel Generator ◽  
Average Wind Speed ◽  
Wind Speeds ◽  
Average Wind

Optimization of the autonomous wind-diesel plants composition and of their power for guaranteed energy supply, despite the long history of research, the diversity of approaches and methods, is an urgent problem. In this paper, a detailed analysis of the wind energy characteristics is proposed to shape an autonomous power system for a guaranteed power supply with predominance wind energy. The analysis was carried out on the basis of wind speed measurements in the south of the European part of Russia during 8 months at different heights with a discreteness of 10 minutes. As a result, we have obtained a sequence of average daily wind speeds and the sequences constructed by arbitrary variations in the distribution of average daily wind speeds in this interval. These sequences have been used to calculate energy balances in systems (wind turbines + diesel generator + consumer with constant and limited daily energy demand) and (wind turbines + diesel generator + consumer with constant and limited daily energy demand + energy storage). In order to maximize the use of wind energy, the wind turbine integrally for the period in question is assumed to produce the required amount of energy. For the generality of consideration, we have introduced the relative values of the required energy, relative energy produced by the wind turbine and the diesel generator and relative storage capacity by normalizing them to the swept area of the wind wheel. The paper shows the effect of the average wind speed over the period on the energy characteristics of the system (wind turbine + diesel generator + consumer). It was found that the wind turbine energy produced, wind turbine energy used by the consumer, fuel consumption, and fuel economy depend (close to cubic dependence) upon the specified average wind speed. It was found that, for the same system with a limited amount of required energy and high average wind speed over the period, the wind turbines with lower generator power and smaller wind wheel radius use wind energy more efficiently than the wind turbines with higher generator power and larger wind wheel radius at less average wind speed. For the system (wind turbine + diesel generator + energy storage + consumer) with increasing average speed for a given amount of energy required, which in general is covered by the energy production of wind turbines for the period, the maximum size capacity of the storage device decreases. With decreasing the energy storage capacity, the influence of the random nature of the change in wind speed decreases, and at some values of the relative capacity, it can be neglected.

Evaluation of the influence of wind speed and angle of attack on the aerodynamic effect of wind turbine blades

2017 ◽  
Author(s):  
Salete Alves ◽  
Luiz Guilherme Vieira Meira de Souza ◽  
Edália Azevedo de Faria ◽  
Maria Thereza dos Santos Silva ◽  
Ranaildo Silva
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Turbine Blades ◽  
Angle Of Attack ◽  
Wind Turbine Blades ◽  
Aerodynamic Effect

scholarly journals Novel Application and Validation of a Method to Assess Visual Impacts of Rotating Wind Turbine Blades Within Woodland Areas

2021 ◽  
Vol 89 (1) ◽  
pp. 1-14
Author(s):  
U. Nopp-Mayr ◽  
F. Kunz ◽  
F. Suppan ◽  
E. Schöll ◽  
J. Coppes
Keyword(s):  
Environmental Impact ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Power Plants ◽  
Laser Scanning ◽  
Forest Canopy ◽  
Turbine Blades ◽  
Wind Turbine Blades ◽  
Environmental Impact Assessments ◽  
Independent Field

AbstractIncreasing numbers of wind power plants (WPP) are constructed across the globe to reduce the anthropogenic contribution to global warming. There are, however, concerns on the effects of WPP on human health as well as related effects on wildlife. To address potential effects of WPP in environmental impact assessments, existing models accounting for shadow flickering and noise are widely applied. However, a standardized, yet simple and widely applicable proxy for the visibility of rotating wind turbines in woodland areas was largely lacking up to date. We combined land cover information of forest canopy extracted from orthophotos and airborne laser scanning (LiDAR) data to represent the visibility of rotating wind turbines in five woodland study sites with a high spatial resolution. Performing an in-situ validation in five study areas across Europe which resulted in a unique sample of 1738 independent field observations, we show that our approach adequately predicts from where rotating wind turbine blades are visible within woodlands or not. We thus provide strong evidence, that our approach yields a valuable proxy of the visibility of moving rotor blades with high resolution which in turn can be applied in environmental impact assessments of WPP within woodlands worldwide.

scholarly journals Analysis of Wind Turbine Aging through Operation Data Calibrated by LiDAR Measurement

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2319
Author(s):  
Hyun-Goo Kim ◽  
Jin-Young Kim
Keyword(s):  
Power Generation ◽  
Wind Speed ◽  
Wind Turbine ◽  
Wind Farm ◽  
Free Stream ◽  
Turbine Blades ◽  
Wind Farms ◽  
Lidar Measurement ◽  
Wind Turbine Blades ◽  
Wake Effect

This study analyzed the performance decline of wind turbine with age using the SCADA (Supervisory Control And Data Acquisition) data and the short-term in situ LiDAR (Light Detection and Ranging) measurements taken at the Shinan wind farm located on the coast of Bigeumdo Island in the southwestern sea of South Korea. Existing methods have generally attempted to estimate performance aging through long-term trend analysis of a normalized capacity factor in which wind speed variability is calibrated. However, this study proposes a new method using SCADA data for wind farms whose total operation period is short (less than a decade). That is, the trend of power output deficit between predicted and actual power generation was analyzed in order to estimate performance aging, wherein a theoretically predicted level of power generation was calculated by substituting a free stream wind speed projecting to a wind turbine into its power curve. To calibrate a distorted wind speed measurement in a nacelle anemometer caused by the wake effect resulting from the rotation of wind-turbine blades and the shape of the nacelle, the free stream wind speed was measured using LiDAR remote sensing as the reference data; and the nacelle transfer function, which converts nacelle wind speed into free stream wind speed, was derived. A four-year analysis of the Shinan wind farm showed that the rate of performance aging of the wind turbines was estimated to be −0.52%p/year.

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