Academic literature on the topic 'Below and Above rated speed of wind'
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Journal articles on the topic "Below and Above rated speed of wind"
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Sulata, Bhandari* Dr. Tilak Thakur Dr. Jagdish Kumar. "IMPLEMENTING FUZZY CONTROLLER FOR WIND TURBINE CONTROL FOR ALL WIND SPEEDS --WITH REDUCED FUZZY RULE SET." Global Journal of Engineering Science and Research Management 4, no. 9 (2017): 36–41. https://doi.org/10.5281/zenodo.886925.
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To extract maximum power, at below rated speed of wind, the speed of the generator rotor is adjusted for maximum power extraction. But for higher wind speed, however the output power is monitored and controlled at rated power by pitch angle adjustments. In this paper attempt has been made to design and implement a fuzzy controller, which is applicable for both below rated wind speed region as well as above that. It is proposed and shown that how framing control rules using only the desired extremity conditions helps attaining the desired result with a reduced rule set, making it easy for further fine tuning too.
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Rajendran, Saravanakumar, and Debashisha Jena. "Control of Variable Speed Variable Pitch Wind Turbine at Above and Below Rated Wind Speed." Journal of Wind Energy 2014 (October 22, 2014): 1–14. http://dx.doi.org/10.1155/2014/709128.
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The paper presents a nonlinear approach to wind turbine (WT) using two-mass model. The main aim of the controller in the WT is to maximize the energy output at varying wind speed. In this work, a combination of linear and nonlinear controllers is adapted to variable speed variable pitch wind turbines (VSVPWT) system. The major operating regions of the WT are below (region 2) and above rated (region 3) wind speed. In these regions, generator torque control (region 2) and pitch control (region 3) are used. The controllers in WT are tested for below and above rated wind speed for step and vertical wind speed profile. The performances of the controllers are analyzed with nonlinear FAST (Fatigue, Aerodynamics, Structures, and Turbulence) WT dynamic simulation. In this paper, two nonlinear controllers, that is, sliding mode control (SMC) and integral sliding mode control (ISMC), have been applied for region 2, whereas for pitch control in region 3 conventional PI control is used. In ISMC, the sliding manifold makes use of an integral action to show effective qualities of control in terms of the control level reduction and sliding mode switching control minimization.
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Meng, Fanzhong, Wai Hou Lio, and Gunner Chr Larsen. "Wind turbine LIDAR-assisted control: Power improvement, wind coherence and loads reduction." Journal of Physics: Conference Series 2265, no. 2 (2022): 022060. http://dx.doi.org/10.1088/1742-6596/2265/2/022060.
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Abstract This paper aims to firstly review various LIDAR-assisted wind turbine control methods proposed in the past ten years for improving power production in the below rated wind speed region in order to clarify their performance and quantify the potential benefits and drawbacks of LIDAR-assisted control. Secondly, a new LIDAR-assisted control algorithm based on Extremum Seeking Control (ESC) using LIDAR preview information for tracking the optimal power coefficient value is presented and compared to the traditional control strategy. The results show that the newly proposed LIDAR-assisted control strategy is beneficial in the below rated wind speed region when the aerodynamic properties of blades are changed largely compared to the original design. Lastly, the effects of the wind field coherence between the LIDAR measured points and the rotor plane on the LIDAR-assisted control for loads reduction in above rated region is discussed. An important conclusion is that the major benefit of LIDAR-assisted wind turbine control is to improve collective pitch control for reducing fatigue loads in above rated region, when the coherence bandwidth between the LIDAR measured wind speed and the rotor effective wind speed is high.
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Rajendran, Saravanakumar, and Debashisha Jena. "Load Mitigation and Optimal Power Capture for Variable Speed Wind Turbine in Region 2." Journal of Renewable Energy 2015 (2015): 1–10. http://dx.doi.org/10.1155/2015/978216.
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This paper proposes the two nonlinear controllers for variable speed wind turbine (VSWT) operating at below rated wind speed. The objective of the controller is to maximize the energy capture from the wind with reduced oscillation on the drive train. The conventional controllers such as aerodynamic torque feedforward (ATF) and indirect speed control (ISC) are adapted initially, which introduce more power loss, and the dynamic aspects of WT are not considered. In order to overcome the above drawbacks, modified nonlinear static state with feedback estimator (MNSSFE) and terminal sliding mode controller (TSMC) based on Modified Newton Raphson (MNR) wind speed estimator are proposed. The proposed controllers are simulated with nonlinear FAST (fatigue, aerodynamics, structures, and turbulence) WT dynamic simulation for different mean wind speeds at below rated wind speed. The frequency analysis of the drive train torque is done by taking the power spectral density (PSD) of low speed shaft torque. From the result, it is found that a trade-off is to be maintained between the transient load on the drive train and maximum power capture.
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McNerney, G. "Unintended Stalling of the USW 56-100 During Optimum Pitch Control Operation." Journal of Solar Energy Engineering 116, no. 3 (1994): 153–57. http://dx.doi.org/10.1115/1.2930075.
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The U.S. Windpower 56-100 is a three-bladed, free yaw wind turbine, using full span blade pitch control for power regulation. It is theoretically possible to increase the energy capture of the 56-100 by adjusting the blade angle to the optimum pitch angle on a continuing basis at below rated speeds. This concept was field tested on the 56-100, but it was found that the optimum pitch control logic opens a pathway for the 56-100 to fall into stall operation when the winds are above the rated wind speed. The 56-100 then operates as a stall-regulated wind turbine with an overall reduction of energy capture and an increase in system loads.
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Yuan, Chenyang, Jing Li, Jianyun Chen, Qiang Xu, and Yunfei Xie. "Study on the Influence of Baseline Control System on the Fragility of Large-Scale Wind Turbine considering Seismic-Aerodynamic Combination." Advances in Civil Engineering 2020 (April 16, 2020): 1–15. http://dx.doi.org/10.1155/2020/8471761.
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The purpose of this paper is to explore the effect of the baseline control system (BCS) on the fragility of large-scale wind turbine when seismic and wind actions are considered simultaneously. The BCS is used to control the power output by regulating rotor speed and blade-pitch angle in real time. In this study, the fragility analysis was performed and compared between two models using different peak ground acceleration, wind speeds, and specified critical levels. The fragility curves with different wind conditions are obtained using the multiple stripe analysis (MSA) method. The calculation results show that the probability of exceedance specified critical level increases as the wind speed increases in model 1 without considering BCS, while does not have an obvious change in the below-rated wind speed range and has a significant decrease in the above-rated wind speed range in model 2 with considering BCS. The comparison depicts that if the BCS is neglected, the fragility of large-scale wind turbine will be underestimated in around the cut-in wind speed range and overestimated in the over-rated wind speed range. It is concluded that the BCS has a great effect on the fragility especially within the operating conditions when the rated wind speed is exceeded, and it should be considered when estimating the fragility of wind turbine subjected to the interaction of seismic and aerodynamic loads.
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Reddy, Yiza-srikanth, and Sung-ho Hur. "Comparison of Optimal Control Designs for a 5 MW Wind Turbine." Applied Sciences 11, no. 18 (2021): 8774. http://dx.doi.org/10.3390/app11188774.
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Optimal controllers, namely Model Predictive Control (MPC), H∞ Control (H∞), and Linear Quadratic Gaussian control (LQG), are designed for a 5 MW horizontal-axis variable-speed wind turbine. The control design models required as part of the optimal control design are obtained by using a high fidelity aeroelastic model (i.e., DNV Bladed). The optimal controllers are eventually designed in three operating modes: below-rated, just below-rated, and above rated-wind speeds, based on linearized control design models. The linearized models are reduced by using a model reduction technique to facilitate the design of optimal controllers. The controllers are analyzed not only in the time domain but also in the frequency domain and on the torque/speed plane. Simulation results demonstrated that optimal controllers perform better than the standard proportional-integral-derivative (PID) controller, particularly for removing oscillation due to the drive-train mode without incorporating a drive-train damper.
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Kim, Hyungyu, Kwansu Kim, Carlo Bottasso, Filippo Campagnolo, and Insu Paek. "Wind Turbine Wake Characterization for Improvement of the Ainslie Eddy Viscosity Wake Model." Energies 11, no. 10 (2018): 2823. http://dx.doi.org/10.3390/en11102823.
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This paper presents a modified version of the Ainslie eddy viscosity wake model and its accuracy by comparing it with selected exiting wake models and wind tunnel test results. The wind tunnel test was performed using a 1.9 m rotor diameter wind turbine model operating at a tip speed ratio similar to that of modern megawatt wind turbines. The control algorithms for blade pitch and generator torque used for below and above rated wind speed regions similar to those for multi-MW wind turbines were applied to the scaled wind turbine model. In order to characterize the influence of the wind turbine operating conditions on the wake, the wind turbine model was tested in both below and above rated wind speed regions at which the thrust coefficients of the rotor varied. The correction of the Ainslie eddy viscosity wake model was made by modifying the empirical equation of the original model using the wind tunnel test results with the Nelder-Mead simplex method for function minimization. The wake prediction accuracy of the modified wake model in terms of wind speed deficit was found to be improved by up to 6% compared to that of the original model. Comparisons with other existing wake models are also made in detail.
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Cioni, Stefano, Francesco Papi, Emanuele Cocchi, and Alessandro Bianchini. "UNICO: an open-source controller optimized for stall-regulated wind turbines." Journal of Physics: Conference Series 2767, no. 3 (2024): 032004. http://dx.doi.org/10.1088/1742-6596/2767/3/032004.
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Abstract Stall regulation turbines still represent the preferred solution for small wind turbines. In stall-controlled rotors the controller plays a key role but, differently from pitch-based ones, no open-source controller was available to date. The study presents the UNICO (UNIfi research COntroller) controller, which has been specifically developed for variable speed stall-regulated turbines. The controller has been developed in MATLAB® Simulink® and a dynamic link library (.dll) has been generated, which can be coupled with common simulation codes such as OpenFAST and QBlade using a Bladed-style interface. UNICO includes features that are specifically tailored to variable-speed stall-regulated turbines. For below-rated conditions, the controller employs either the commonly used k-ω2 law or a tracking of the optimal tip speed ratio. For above-rated conditions, a PI controller is used to track a user-imposed reference speed. The reference speed is set to decrease linearly with wind speed, providing a safety margin for turbine operation at higher wind speeds. UNICO has been tested on a 50-kW stall-regulated reference turbine. Preliminary results show how the proposed controller can achieve better overall performance in comparison to the simplified control laws implemented in state-of-the-art codes. Additionally, the rotor speed can be controlled in above-rated conditions, providing an increased run away safety margin.
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Mann, Jakob, Alfredo Peña, Niels Troldborg, and Søren J. Andersen. "How does turbulence change approaching a rotor?" Wind Energy Science 3, no. 1 (2018): 293–300. http://dx.doi.org/10.5194/wes-3-293-2018.
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Abstract. For load calculations on wind turbines it is usually assumed that the turbulence approaching the rotor does not change its statistics as it goes through the induction zone. We investigate this assumption using a nacelle-mounted forward-looking pulsed lidar that measures low-frequency wind fluctuations simultaneously at distances between 0.5 and 3 rotor diameters upstream. The measurements show that below rated wind speed the low-frequency wind variance is reduced by up to 10 % at 0.5 rotor diameters upstream and above rated enhanced by up to 20 %. A quasi-steady model that takes into account the change in thrust coefficient with wind speed explains these variations partly. Large eddy simulations of turbulence approaching an actuator disk model of a rotor support the finding that the slope of the thrust curve influences the low-frequency fluctuations.
Dissertations / Theses on the topic "Below and Above rated speed of wind"
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Gase, Zachary M. "Below-Rated Control of Swept-Blade Wind Turbines." Scholarly Commons, 2016. https://scholarlycommons.pacific.edu/uop_etds/225.
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Modelling studies have shown that 1.5 and 3.0 MW wind turbines with blade sweep have an increased annual energy production (AEP) of approximately 5% when compared to straight-blade wind turbines. The objective of the research was to further increase below-rated, variable speed, power capture when using swept-blades. When operating in the variable speed region, the turbine’s torque is proportional to the square of the generator speed, and k is the proportionality constant (T = kΩ 2 ). Initial studies indicated that the value of k needed to be lowered from the original value to increase AEP. This proved to be slightly beneficial for the 3.0 MW turbine but not for the 1.5 MW turbine. The optimal tip speed ratio was too high for both turbines and limited the ability to increase AEP. Original swept-blade chords were designed to fit a linear pattern for manufacturing purposes, but it is believed this is no longer a necessary constraint. The blades were redesigned to have a non-linear chord distribution, which is based on the Betz optimal design method, and the resultant increase in solidity proved to be the solution for slowing down the blades’ rotational speed. The change in chord design proved to be beneficial for both 1.5 and 3.0 MW wind turbines and had immediate, measurable increases to AEP. An effort to further increase AEP was then conducted by using an alternative torque-speed controller, which used a different equation to relate speed and torque. This method only resulted in an increase of AEP for the 1.5 MW turbine. In conclusion, the highest recorded AEP increases from straight-blade values were 6.9% and 8.9% for the 1.5 and 3.0 MW turbines, respectively. The 1.5 MW turbine benefited from the custom controller and redesigned chords, whereas the 3.0 MW turbine only benefited from redesigned chords.
Book chapters on the topic "Below and Above rated speed of wind"
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Schulte, Horst, and Nico Goldschmidt. "Fault-Tolerant Fast Power Tracking Control for Wind Turbines Above Rated Wind Speed." In Advanced, Contemporary Control. Springer Nature Switzerland, 2023. http://dx.doi.org/10.1007/978-3-031-35170-9_22.
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Aboutalebi, Payam, Fares M’zoughi, Irfan Ahmad, Aitor J. Garrido, and Izaskun Garrido. "A Control Approach on Hybrid Floating Offshore Wind Turbines for Platform and Generated Power Oscillations Reduction at Below-rated Wind Speed." In Lecture Notes in Networks and Systems. Springer Nature Switzerland, 2022. http://dx.doi.org/10.1007/978-3-031-18050-7_49.
Full textConference papers on the topic "Below and Above rated speed of wind"
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Li, Jiaqi, and Hua Geng. "Stability Analysis and Improvment of Floating Offshore Wind Turbine in Above Rated Wind Speed Region." In 2024 IEEE Power & Energy Society General Meeting (PESGM). IEEE, 2024. http://dx.doi.org/10.1109/pesgm51994.2024.10688854.
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Das, Tuhin, Greg Semrau, and Sigitas Rimkus. "Nonlinear Control of Variable Speed Wind Turbines With Switching Across Operating Regimes." In ASME 2011 Dynamic Systems and Control Conference and Bath/ASME Symposium on Fluid Power and Motion Control. ASMEDC, 2011. http://dx.doi.org/10.1115/dscc2011-6142.
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One of the key control problems associated with variable speed wind turbine systems is maximization of energy extraction when operating below the rated wind speed and power regulation when operating above the rated wind speed. In this paper, we approach these problems from a nonlinear systems perspective. For below rated wind speeds we adopt existing work appearing in the literature and provide further insight into the characteristics of the resulting equilibrium points of the closed-loop system. For above rated wind speeds, we propose a nonlinear controller and analyze the stability property of the resulting equilibria. We also propose a method for switching between the two operating regimes that ensures continuity of control input at the transition point. The control laws are verified using a wind turbine model with a standard turbulent wind speed profile that spans both operating regimes.
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Eggers, A. J., P. Moriarty, K. Chaney, R. Digumarthi, and W. E. Holley. "Influence of Transition Modes and Gravity Loads on Rotor Fatigue and Power Control." In ASME 2002 Wind Energy Symposium. ASMEDC, 2002. http://dx.doi.org/10.1115/wind2002-46.
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Two classes of transition modes are examined. The first class involves rotor start-up and shut-down in turbulent winds with rapidly varying mean wind speeds. In the start-up mode, coupling can occur between the mean and cyclic pitch control systems which leads to large peaks in blade flatwise moments. These peaks can substantially increase overall fatigue damage. They can be reduced by controlling blade pitch solely with the closed loop control system. Allowing the rotor to freely rotate at wind speeds below start-up eliminates blade moment peaks in the transition to low speed operation, with the result that closed loop control further increases blade fatigue life. These control alterations reduce power fluctuations but appear to have no significant effect on overall energy capture. Blade pitch control in the shutdown transition mode is restricted solely to mean pitch angle and no control coupling problems are encountered. The second class of transition modes studied is operation from below to above rated wind speed. This transition was previously idealized as an abrupt change from variable to constant rotor speed operation with mean blade pitch angle increased rapidly to hold mean power constant up to rotor shut down. This causes a very sharp peaking of mean moment at rated wind speed which increases blade fatigue damage. This peaking is reduced by smoothing the controlled variation of mean blade pitch angle over a range of wind speeds from below to above rated. As a result, rotor blade fatigue life is substantially increased, and energy capture is somewhat reduced in both open and closed loop operation. Thus there is a trade-off between energy capture and fatigue life which is examined. The comparative effects on blade fatigue life and weight of turbulence induced and 1P gravity loads are examined for large scale rotor blades. The bending strength of each blade in the out-of-plane and in-plane directions at the critical root location was assumed to be the same for full span pitch control requiring a cylindrical cross-section at the root. It is indicated that turbulence induced fatigue damage dominates over that due to gravity for rotor radii up to about 40m and near 2 MW rated power, depending on the number of rotor blades. This open loop result is unaltered in closed loop operation if blade weight is reduced to maintain the same fatigue life. Tradeoffs between rotor blade weight and energy capture in open and closed loop control operation are examined.
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Mohr, Eric, Biswaranjan Mohanty, and Kim A. Stelson. "Short-Term Energy Storage System for Hydraulic Hybrid Wind Turbine Transmission." In BATH/ASME 2020 Symposium on Fluid Power and Motion Control. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/fpmc2020-2777.
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Abstract A Hydrostatic Transmission (HST) offers a variable ratio transmission for wind turbines that has a higher power to weight ratio than traditional gearboxes, and requires less maintenance. In a conventional turbine, when the wind speed increases above the rated speed, the blade pitch is controlled to dissipate excess energy and regulate the turbine at rated power. An energy storage system allows the turbine to temporarily operate above rated power, and capture the traditionally dissipated energy in an accumulator. When the wind speed drops below the rated speed, the energy in the accumulator is released, increasing the delivered power This paper presents a high-fidelity mathematical model of the hydraulic hybrid wind turbine transmission. Simulation results for a series of step changes and for turbulent wind speed are investigated for a 60 kW turbine. Using a realistic turbulent wind data sample, energy production increased by 4% with a 52 liter accumulator with significantly smoother output power to the grid.
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Nielsen, Finn Gunnar, Tor David Hanson, and Bjo̸rn Skaare. "Integrated Dynamic Analysis of Floating Offshore Wind Turbines." In 25th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2006. http://dx.doi.org/10.1115/omae2006-92291.
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Two different simulation models for integrated dynamic analysis of floating offshore wind turbines are described and compared with model scale experiments for the Hywind concept for floating offshore wind turbines. A variety of both environmental conditions and wind turbine control schemes are tested. A maximum power control strategy is applied for wind velocities below the rated wind speed for the wind turbine, while a constant power control strategy is achieved by controlling the rotor blade pitch for wind velocities above rated wind speed. Conventional rotor blade pitch control for wind velocities above rated wind speed introduces negative damping of the tower motion. This results in excitation of the natural frequency in pitch for the tower and may lead to unacceptable tower motions. Active damping of the undesirable tower motions is obtained by an additional pitch control algorithm based on measurement of the tower velocity.
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Srikanth Reddy, Yiza, and Sung-ho Hur. "Wind Turbine Gust Control Using LIDAR-Assisted Model Predictive Control." In ASME 2023 5th International Offshore Wind Technical Conference. American Society of Mechanical Engineers, 2023. http://dx.doi.org/10.1115/iowtc2023-119579.
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Abstract Light Detection and Ranging (LIDAR)-based wind measurement system, positioned forward-facing, can gather information about the approaching wind. It proactively enables the wind turbine to adjust its operation via the feedforward (FF) loop. LIDAR technology can enhance wind turbine performance throughout its entire operational range. It can assist in torque control when wind speeds are below the rated level and in pitch control when wind speeds exceed the rated level. In this study, Model Predictive Control (MPC) is utilized. Within the field of wind turbine research, MPC has garnered significant interest in recent years due to its capability to handle both input and output constraints and leverage advanced on disturbances caused by the incoming wind, measured by the LIDAR. In this study, an FF-MPC is designed and compared with a more standard feedback (FB) MPC. A comparison is conducted in realistic gust wind conditions, considering below and above-rated wind ranges. These comparisons are performed in a realistic, high-fidelity aeroelastic simulation environment, i.e., DNV BLADED. Both controllers are designed for the DNV BLADED Supergen 5 MW wind turbine model. The control algorithm is implemented in C++, compiled into a dynamic link library (DLL), and integrated as an external controller within the DNV BLADED to enable accurate, high-fidelity simulations. Simulation results are presented to demonstrate the superiority of FF-MPC over the standard FB-MPC.
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Popko, Wojciech, Amy Robertson, Jason Jonkman, et al. "Validation of Numerical Models of the Offshore Wind Turbine From the Alpha Ventus Wind Farm Against Full-Scale Measurements Within OC5 Phase III." In ASME 2019 38th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/omae2019-95429.
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Abstract The main objective of the Offshore Code Comparison Collaboration Continuation, with Correlation (OC5) project is validation of aero-hydro-servo-elastic simulation tools for offshore wind turbines (OWTs) through comparison of simulated results to the response data of physical systems. Phase III of the OC5 project validates OWT models against the measurements recorded on a Senvion 5M wind turbine supported by the OWEC Quattropod from the alpha ventus offshore wind farm. The following operating conditions of the wind turbine were chosen for the validation: (1) Idling below the cut-in wind speed; (2) Rotor-nacelle assembly (RNA) rotation maneuver below the cut-in wind speed; (3) Power production below and above the rated wind speed; and (4) Shutdown. A number of validation load cases were defined based on these operating conditions. The following measurements were used for validation: (1) Strains and accelerations recorded on the support structure; (2) Pitch, yaw, and azimuth angles, generator speed, and electrical power recorded from the RNA. Strains were not directly available from the majority of the OWT simulation tools. Therefore, strains were calculated based on out-of-plane bending moments, axial forces, and cross-sectional properties of the structural members. Also, a number of issues arose during the validation: (1) The need for a thorough quality check of sensor measurements; (2) The sensitivity of the turbine loads to the controller and airfoil properties, which were only approximated in the modeling approach; (3) The importance of estimating and applying an appropriate damping value for the structure; and (4) The importance of wind characteristics beyond turbulence on the loads. The simulation results and measurements were compared in terms of time series, discrete Fourier transforms, power spectral densities, probability density functions of strains and accelerometers. A good match was achieved between the measurements and models set up by OC5 Phase III participants.
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Firpo, Agnese, Andrea G. Sanvito, Vincenzo Dossena, and Giacomo Persico. "Aerodynamic Study of a Horizontal Axis Wind Turbine in Surge Motion Under Angular Speed and Blade Pitch Controls." In ASME Turbo Expo 2024: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2024. http://dx.doi.org/10.1115/gt2024-129321.
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Abstract Floating offshore wind turbines experience dynamic conditions due to platform motion, requiring specific control strategies to mitigate loads and promote the wake diffusion improving overall wind farm efficiency. These problems can be appropriately modelled by medium-fidelity solvers, which rely on a CFD resolution of the flow while avoiding its detailed resolution around the blades, preserving high-fidelity in simulating the wake at an acceptable computational cost. This work adopts a medium-fidelity Actuator Line Model, implemented in the OpenFOAM environment, previously validated against experiments and multi-fidelity models in the frame of the OC6 Phase III project. The study analyses several operating conditions during surge motion: a variable angular speed in below-rated condition, conceived to maximise the turbine efficiency, and a collective blade pitch control employable in above-rated conditions to limit surge-induced loads fluctuations. The effect of each control strategy is assessed individually through a systematic comparison with the baseline case with constant angular speed and blade pitch. Results indicate that the angular speed control succeeds in increasing the turbine power, and reduces the spanwise variability of the induction factor amplitudes. Conversely, the pitch angle control reduces the force amplitude but does not alter the spanwise trend of the induction factor amplitude.
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Lin, Z., A. Stetco, J. Carmona-Sanchez, et al. "Progress on the Development of a Holistic Coupled Model of Dynamics for Offshore Wind Farms: Phase II — Study on a Data-Driven Based Reduced-Order Model for a Single Wind Turbine." In ASME 2019 38th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/omae2019-95542.
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Abstract At present, over 1500 offshore wind turbines (OWTs) are operating in the UK with a capacity of 5.4GW. Until now, the research has mainly focused on how to minimise the CAPEX, but Operation and Maintenance (O&M) can represent up to 39% of the lifetime costs of an offshore wind farm, mainly due to the assets’ high cost and the harsh environment in which they operate. Focusing on O&M, the HOME Offshore research project (www.homeoffshore.org) aims to derive an advanced interpretation of the fault mechanisms through holistic multiphysics modelling of the wind farm. With the present work, an advanced model of dynamics for a single wind turbine is developed, able to identify the couplings between aero-hydro-servo-elastic (AHSE) dynamics and drive train dynamics. The wind turbine mechanical components, modelled using an AHSE dynamic model, are coupled with a detailed representation of a variable-speed direct-drive 5MW permanent magnet synchronous generator (PMSG) and its fully rated voltage source converters (VSCs). Using the developed model for the wind turbine, several case studies are carried out for above and below rated operating conditions. Firstly, the response time histories of wind turbine degrees of freedom (DOFs) are modelled using a full-order coupled analysis. Subsequently, regression analysis is applied in order to correlate DOFs and generated rotor torque (target degree of freedom for the failure mode in analysis), quantifying the level of inherent coupling effects. Finally, the reduced-order multiphysics models for a single offshore wind turbine are derived based on the strength of the correlation coefficients. The accuracy of the proposed reduced-order models is discussed, comparing it against the full-order coupled model in terms of statistical data and spectrum. In terms of statistical results, all the reduced-order models have a good agreement with the full-order results. In terms of spectrum, all the reduced-order models have a good agreement with the full-order results if the frequencies of interest are below 0.75Hz.
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Kress, Christian, Ndaona Chokani, and Reza S. Abhari. "Design Considerations of Rotor Cone Angle for Downwind Wind Turbines." In ASME Turbo Expo 2015: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/gt2015-42335.
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Due to their potential to use light, flexible blades, downwind turbines are well suited for offshore floating platforms, for which there is a need to substantially lower the cost of wind-generated electricity. However, downwind rotors must operate in the presence of the tower’s wakes with which are associated strong changes in flow incidence, and thus high fatigue loads. In order to guide the development of design rules for multi-megawatt downwind turbines, a comprehensive experimental study has been conducted to better understand the characteristics of the unsteady rotor torque on downwind turbines. High frequency measurements of the unsteady rotor torque on a model turbine that can be configured with rotors of different cone angles, and operated either downwind or upwind in well-controlled flow conditions are conducted. The measurements show that in the case of the downwind turbine, the blade’s passage through the tower’s wake accounts for 56% to 61% of the variance of the rotor torque; the proportion of this unsteadiness is independent of the cone angle. For non-optimum tip speed ratios, the increase in unsteadiness is consistently less for downwind configurations than for upwind configurations. For the 5°-cone downwind configuration, the increase in rotor torque unsteadiness is 13%–18% of the increase observed for the 5°-cone upwind configuration for non-optimum tip speed ratios. Thus from a design perspective, downwind rotor configurations offer above or below rated wind speed, a smaller increase in unsteadiness of the rotor torque compared to upwind turbine configurations. These characteristics differ from upwind turbines, on which broadband vortex shedding from the blade is the primary source of the unsteadiness, which may be reduced by increasing the rotor-tower clearance. It is suggested that given the strong periodic character of the blade’s passage through the tower’s wake, the turbine control system may be designed to reduce fatigue loads and there is a broader design space on downwind turbines that can be exploited for peak load mitigation by moderately adjusting the blade’s stiffness.
Reports on the topic "Below and Above rated speed of wind"
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Carpenter, Grace. Shenandoah National Park: Acoustic monitoring report, 2016?2017. National Park Service, 2023. http://dx.doi.org/10.36967/2300465.
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This report presents acoustical data gathered by the Natural Sounds and Night Skies Division (NSNSD) at Shenandoah National Park (SHEN) in August?September of 2016 and January?March of 2017. Data were collected at four sites (Figure 1) to provide park managers with information about the acoustical environment, sources of noise , and the existing ambient sound levels within the park. In these deployments, sound pressure level (SPL) was measured continuously every second by a calibrated sound level meter. Other equipment included an anemometer to collect wind speed and a digital audio recorder collecting continuous recordings to document sound sources. In this document, ?sound pressure level? refers to broadband (12.5 Hz?20 kHz), A-weighted, 1-second time averaged sound level (LAeq, 1s), and hereafter referred to as ?sound level.? Sound levels are measured on a logarithmic scale relative to the reference sound pressure for atmospheric sources, 20 ?Pa. The logarithmic scale is a useful way to express the wide range of sound pressures perceived by the human ear. Sound levels are reported in decibels (dB). A-weighting is applied to sound levels to account for the response of the human ear (Harris, 1998). To approximate human hearing sensitivity, A-weighting discounts sounds below 1 kHz and above 6 kHz.
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Job, Jacob. Mesa Verde National Park: Acoustic monitoring report. National Park Service, 2021. http://dx.doi.org/10.36967/nrr-2286703.
Full textAbstract:
In 2015, the Natural Sounds and Night Skies Division (NSNSD) received a request to collect baseline acoustical data at Mesa Verde National Park (MEVE). Between July and August 2015, as well as February and March 2016, three acoustical monitoring systems were deployed throughout the park, however one site (MEVE002) stopped recording after a couple days during the summer due to wildlife interference. The goal of the study was to establish a baseline soundscape inventory of backcountry and frontcountry sites within the park. This inventory will be used to establish indicators and thresholds of soundscape quality that will support the park and NSNSD in developing a comprehensive approach to protecting the acoustic environment through soundscape management planning. Additionally, results of this study will help the park identify major sources of noise within the park, as well as provide a baseline understanding of the acoustical environment as a whole for use in potential future comparative studies. In this deployment, sound pressure level (SPL) was measured continuously every second by a calibrated sound level meter. Other equipment included an anemometer to collect wind speed and a digital audio recorder collecting continuous recordings to document sound sources. In this document, “sound pressure level” refers to broadband (12.5 Hz–20 kHz), A-weighted, 1-second time averaged sound level (LAeq, 1s), and hereafter referred to as “sound level.” Sound levels are measured on a logarithmic scale relative to the reference sound pressure for atmospheric sources, 20 μPa. The logarithmic scale is a useful way to express the wide range of sound pressures perceived by the human ear. Sound levels are reported in decibels (dB). A-weighting is applied to sound levels in order to account for the response of the human ear (Harris, 1998). To approximate human hearing sensitivity, A-weighting discounts sounds below 1 kHz and above 6 kHz. Trained technicians calculated time audible metrics after monitoring was complete. See Methods section for protocol details, equipment specifications, and metric calculations. Median existing (LA50) and natural ambient (LAnat) metrics are also reported for daytime (7:00–19:00) and nighttime (19:00–7:00). Prominent noise sources at the two backcountry sites (MEVE001 and MEVE002) included vehicles and aircraft, while building and vehicle predominated at the frontcountry site (MEVE003). Table 1 displays time audible values for each of these noise sources during the monitoring period, as well as ambient sound levels. In determining the current conditions of an acoustical environment, it is informative to examine how often sound levels exceed certain values. Table 2 reports the percent of time that measured levels at the three monitoring locations were above four key values.