On the Use of a Large Database of Simulated Wind Turbine Loads to Aid in Assessing Design Standard Provisions

An opto-mechanical system has been developed to measure the dynamic behaviour of multi-megawatt wind turbines. This portable system is easier and less expensive to use than previously used methods. Thus it is feasible to use the system to develop a large database of the modal damping characteristics of operational full-scale wind turbines for the development of the improved fatigue life prediction tools that are needed in the rapidly growing global wind industry. The opto-mechanical system and a 3D scanning pulsed Doppler LIDAR system are used to make simultaneous measurements of the dynamic response and wind field in three different utility-scale wind farms. The wind farms are located in different types of terrain, ranging from the flat terrain through to highly complex terrain. The measurements are made on five different multi-megawatt wind turbines (1.8MW Vestas V90; 2.0MW Vestas V80; 2.3MW Enercon E70; 3MW Vestas V90; and 3.6MW Siemens SWT). A single-degree-of-freedom dynamic model is used to determine the modal damping parameters from the measured spectra of the tower deflections. It is shown that the aeromechanical damping ratios range from 0.4% to 0.8%. Measurements in the operating and idling phases of a turbine are used to show that the aerodynamic damping, which arises from the interaction between the rotor and wind, is the dominant damping mechanism for an operating wind turbine, and accounts for two-thirds of the overall damping; the material damping accounts for one-third of the overall damping. The 3.6MW Siemens SWT wind turbine has the smallest overall damping, whereas the 3MW Vestas V90 has the largest damping as well as the largest dynamic deflections. However, an assessment of the Goodman diagram shows that in its location of flat terrain, the 3MW Vestas V90 wind turbine may likely meet its 20-year design life. Nevertheless, for other locations, such as in complex terrain, in-situ measurements should be made to verify the suitability of the wind turbine for wind farms in such locations. This work demonstrates the feasibility of using the opto-mechanical system to develop a large database of the modal damping characteristics of operational full-scale wind turbines.

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Wind Climate Parameters for Wind Turbine Fatigue Load Assessment

Journal of Solar Energy Engineering ◽

10.1115/1.4033111 ◽

2016 ◽

Vol 138 (3) ◽

Cited By ~ 9

Author(s):

Henrik Stensgaard Toft ◽

Lasse Svenningsen ◽

Wolfgang Moser ◽

John Dalsgaard Sørensen ◽

Morten Lybech Thøgersen

Keyword(s):

Wind Turbine ◽

Wind Shear ◽

Bending Moment ◽

Site Specific ◽

Design Standard ◽

Climate Parameters ◽

Blade Root ◽

Wind Climate ◽

Fatigue Loads ◽

Turbine Design

Site-specific assessment of wind turbine design requires verification that the individual wind turbine components can survive the site-specific wind climate. The wind turbine design standard, IEC 61400-1 (third edition), describes how this should be done using a simplified, equivalent wind climate established from the on-site distribution functions of the horizontal mean wind speeds, the 90% quantile of turbulence along with average values of vertical wind shear and air density and the maximum flow inclination. This paper investigates the accuracy of fatigue loads estimated using this equivalent wind climate required by the current design standard by comparing damage equivalent fatigue loads estimated based on wind climate parameters for each 10 min time-series with fatigue loads estimated based on the equivalent wind climate parameters. Wind measurements from Boulder, CO, in the United States and Høvsøre in Denmark have been used to estimate the natural variation in the wind conditions between 10 min time periods. The structural wind turbine loads have been simulated using the aero-elastic model FAST. The results show that using a 90% quantile for the turbulence leads to an accurate assessment of the blade root flapwise bending moment and a conservative assessment of the tower bottom for-aft bending moment and low speed shaft torque. Currently, IEC 61400-1 (third edition) neglects the variation in wind shear by using the average value. This may lead to a nonconservative assessment of blade root flapwise fatigue loads, which are sensitive to wind shear. The results in this paper indicate that using a 75% quantile for the wind shear at each wind speed bin leads to an appropriate, but conservative, assessment of the fatigue loads. However, care should be taken when using this approach for components where low or negative wind shears can lead to large fatigue loads. This is the case for some drivetrain components where a lower quantile may be required.

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Simulating Impacts of Real-World Wind Farms on Land Surface Temperature Using the WRF Model: Validation with Observations

Monthly Weather Review ◽

10.1175/mwr-d-16-0401.1 ◽

2017 ◽

Vol 145 (12) ◽

pp. 4813-4836 ◽

Cited By ~ 13

Author(s):

Geng Xia ◽

Matthew C. Cervarich ◽

Somnath Baidya Roy ◽

Liming Zhou ◽

Justin R. Minder ◽

...

Keyword(s):

Surface Temperature ◽

Wind Turbine ◽

Land Surface Temperature ◽

Real World ◽

Land Surface ◽

Wind Farm ◽

Wrf Model ◽

Wind Farms ◽

Satellite Observations ◽

Simulated Wind

This study simulates the impacts of real-world wind farms on land surface temperature (LST) using the Weather Research and Forecasting (WRF) Model driven by realistic initial and boundary conditions. The simulated wind farm impacts are compared with the observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the first Wind Forecast Improvement Project (WFIP) field campaign. Simulations are performed over west-central Texas for the month of July throughout 7 years (2003–04 and 2010–14). Two groups of experiments are conducted: 1) direct validations of the simulated LST changes between the preturbine period (2003–04) and postturbine period (2010–14) validated against the MODIS observations; and 2) a model sensitivity test of LST to the wind turbine parameterization by examining LST differences with and without the wind turbines for the postturbine period. Overall, the WRF Model is moderately successful at reproducing the observed spatiotemporal variations of the background LST but has difficulties in reproducing such variations for the turbine-induced LST change signals at pixel levels. However, the model is still able to reproduce coherent and consistent responses of the observed LST changes at regional scales. The simulated wind farm–induced LST warming signals agree well with the satellite observations in terms of their spatial coupling with the wind farm layout. Moreover, the simulated areal mean warming signal (0.20°–0.26°C) is about a tenth of a degree smaller than that from MODIS (0.33°C). However, these results suggest that the current wind turbine parameterization tends to induce a cooling effect behind the wind farm region at nighttime, which has not been confirmed by previous field campaigns and satellite observations.

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Robust Control Examples Applied to a Wind Turbine Simulated Model

10.20944/preprints201709.0089.v1 ◽

2017 ◽

Author(s):

Silvio Simani ◽

Paolo Castaldi

Keyword(s):

Robust Control ◽

Wind Turbine ◽

Measurement Errors ◽

Performance Metrics ◽

Control Strategies ◽

Turbine Plant ◽

Stochastic Inputs ◽

And Control ◽

Simulated Wind ◽

Proper Performance

Wind turbine plants are complex dynamic and uncertain processes driven by stochastic inputs and disturbances, as well as different loads represented by gyroscopic, centrifugal, and gravitational forces. Moreover, as their aerodynamic models are nonlinear, both modelling and control become challenging problems. On one hand, high-fidelity simulators should contain different parameters and variables in order to accurately describe the main dynamic system behaviour. Therefore, the development of modelling and control for wind turbine systems should consider these complexity aspects. On the other hand, these control solutions have to include the main wind turbine dynamic characteristics without becoming too complicated. The main point of this paper is thus to provide two practical examples of development of robust control strategies when applied to a simulated wind turbine plant. Experiments with the wind turbine simulator and the Monte–Carlo tools represent the instruments for assessing the robustness and reliability aspects of the developed control methodologies when the model-reality mismatch and measurement errors are also considered. Advantages and drawbacks of these regulation methods are also highlighted with respect to different control strategies via proper performance metrics.

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A Study of Raindrop Impacts on a Wind Turbine Material: Velocity and Impact Angle Effects on Erosion MAPS at Various Exposure Times

Lubricants ◽

10.3390/lubricants9060060 ◽

2021 ◽

Vol 9 (6) ◽

pp. 60

Author(s):

Samuel Groucott ◽

Kieran Pugh ◽

Iasonas Zekos ◽

Margaret M Stack

Keyword(s):

Power Generation ◽

Renewable Energy ◽

Wind Energy ◽

Mass Loss ◽

Wind Turbine ◽

Power Output ◽

Turbine Blades ◽

Impact Angle ◽

Simulated Wind ◽

Rain Erosion

Within renewable energy, challenging climates can impose great limitations on power generation. In wind energy, rain erosion on turbine blades can create major disruptions to air flow over the aerofoil, reducing the efficiency of the blade and immediately affecting the power output of the turbine. The defects in the materials that cause these inefficiencies are known and can be observed on turbines that have been in operation for extended periods. This work explores the transitions between different wear states for G10 Epoxy Glass under laboratory simulated wind turbine conditions in operation and measures the wear periodically to identify a progression of erosion. Mass loss data and micrographic analysis revealed samples at 45° and 60° displayed increasing erosion when examining erosion performance for angles between 15° and 90° over various exposure and velocities. Erosion maps were constructed, showing the variation of wastage and identifying the performance window of conditions where degradation is minimised.

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