scholarly journals Dynamic Aeroelastic Response of Stall-Controlled Wind Turbine Rotors in Turbulent Wind Conditions

2021 ◽  
Vol 11 (15) ◽  
pp. 6886
Author(s):  
Sara Jalal ◽  
Fernando Ponta ◽  
Apurva Baruah ◽  
Anurag Rajan
Keyword(s):  
Wind Turbines ◽  
Economies Of Scale ◽  
Control Strategies ◽  
Oscillatory System ◽  
Oscillatory Behavior ◽  
Reduced Order ◽  
Operational Conditions ◽  
Wind Speeds ◽  
Wide Range ◽  
Generating Capacity

With the current global trend of the wind turbines to be commissioned, the next generation of state-of-the-art turbines will have a generating capacity of 20 MW with rotor diameters of 250 m or larger. This systematic increase in rotor size is prompted by economies-of-scale factors, thereby resulting in a continuously decreasing cost per kWh generated. However, such large rotors have larger masses associated with them and necessitate studies in order to better understand their dynamics. The present work regarding the aeroelastic behavior of stall-controlled rotors involves the study of the frequency content and time evolution of their oscillatory behavior. A wide range of experiments were conducted to assess the effects of rapid variations on the rotor’s operational conditions. Various gust conditions were tested at different wind speeds, which are represented by pulses of different intensities, occurring suddenly in an otherwise constant wind regime. This allowed us to observe the pure aero-elasto-inertial dynamics of the rotor’s response. A reduced-order characterization of the rotor’s dynamics as an oscillatory system was obtained on the basis of energy-transfer principles. This is of fundamental interest for researchers and engineers working on developing optimized control strategies for wind turbines. It allows for the critical elements of the rotor’s dynamic behavior to be described as a reduced-order model that can be solved in real time, an essential requirement for determining predictive control actions.

scholarly journals Pitch Control of Three Bladed Large Wind Energy Converters—A Review

Energies ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 8083
Author(s):  
Adrian Gambier
Keyword(s):  
Wind Energy ◽  
Wind Turbines ◽  
Control Strategies ◽  
Integrated Control ◽  
Pitch Control ◽  
Wind Speeds ◽  
Damping Control ◽  
Wide Range ◽  
Actuator Control ◽  
Large Wind

Modern multi-megawatt wind turbines are currently designed as pitch-regulated machines, i.e., machines that use the rotation of the blades (pitching) in order to adjust the aerodynamic torque, such that the power is maintained constantly throughout a wide range of wind speeds when they exceed the design value (rated wind speed). Thus, pitch control is essential for optimal performance. However, the pitching activity is not for free. It introduces vibrations to the tower and blades and generates fatigue loads. Hence, pitch control requires a compromise between wind turbine performance and safety. In the past two decades, many approaches have been proposed to achieve different objectives and to overcome the problems of a wind energy converter using pitch control. The present work summarizes control strategies for problem of wind turbines, which are solved by using different approaches of pitch control. The emphasis is placed on the bibliographic information, but the merits and demerits of the approaches are also included in the presentation of the topics. Finally, very large wind turbines have to simultaneously satisfy several control objectives. Thus, approaches like collective and individual pitch control, tower and blade damping control, and pitch actuator control must coexist in an integrated control system.

Economic Prospects for Wind Farming

1983 ◽  
Vol 2 (1) ◽  
pp. 67-79
Author(s):  
Martin T. Katzman
Keyword(s):  
Quantitative Assessment ◽  
Oil And Gas ◽  
Fuel Savings ◽  
Wind Speeds ◽  
Average Wind ◽  
Wide Range ◽  
Generating Capacity ◽  
The Usa ◽  
The Cost ◽  
The Impact

Several American utilities have contracted to purchase electricity from ‘windfarmers’, and many others are beginning to explore this option. The value of conventional fuel and capacity savings will influence the terms under which utilities enter these contracts. A quantitative assessment of these savings is undertaken using computer models that simulate the dispatching of conventional capacity and calculate the reliability of this capacity. These models identify the conventional costs avoided by utilities as a consequence of windfarming. The impact of various levels of windmill penetration is simulated in five sites in the USA, representing a wide range of average wind speeds. The cost of wind energy is less than the value of fuel savings alone for utilities which possess substantial oil- and-gas-fired generating capacity and which serve sites with winds above 12 m.p.h. In such sites, 1kW of conventional capacity is displaced by 2–5 kW windmill capacity. Increased windmill penetration reduces the value of fuel and capacity savings per kW.

Circulation Controlled Airfoil Analysis Through 360 Degrees Angle of Attack

2009 ◽  
Author(s):  
Henry Z. Graham ◽  
Meagan Hubbell ◽  
Chad Panther ◽  
Jay Wilhelm ◽  
Gerald M. Angle ◽  
...  
Keyword(s):  
Power Generation ◽  
Wind Turbines ◽  
Electrical Power ◽  
Vertical Axis ◽  
Reynolds Numbers ◽  
Experimental Investigations ◽  
Circulation Control ◽  
Wind Speeds ◽  
Wide Range ◽  
Turbine Shaft

Wind turbines are a source of renewable energy with an endless supply. The most efficient types of wind turbines operate by utilizing the lift force of its blades to create a rotational force. The power capabilities of a wind turbine are tied to the blades’ ability to convert the aerodynamic forces into rotational energy. Vertical axis wind turbines (VAWT), unlike the more common horizontal axis (HAWT) type, do not need to be directed into the wind and can place the transmission and electrical power generation components at the bottom of the turbine shaft, near the ground. Currently VAWTs cannot feather or pitch the blades, in the same fashion as a HAWT, for a lift change to control power generation and/or rotational speed at different or changing wind speeds. A method of increasing the lift of a blade without physically moving the blade is to use circulation control (CC), via a blowing slot over a rounded trailing edge. The CC air flow entrains the air around the blade to create more lift. Adding an actuated valve for the blowing slot allows a CC-VAWT to control the amount of lift generated, as well as the location of the augmentation relative to the wind direction, resulting in augmented power generation. In order to study the performance capabilities of a CC-VAWT, a NACA0018 blade was modified to incorporate circulation control. This modified shape was analyzed using computational fluid dynamics at two Reynolds numbers and a wide range of angles of attack. The lift to drag ratio of the CC-VAWT blade shows benefits at low Reynolds numbers over a NACA0018 blade for post stall angles of attack, but there is a decrease in the lift to drag before stall due to a significant increase in drag of the circulation control models. Further CFD refinement and experimental investigations are recommended to validate the predicted effects circulation control will have on the performance of a VAWT.

Integrated Real-Time Transit Signal Priority Control for High-Frequency Segregated Transit Services

2015 ◽  
Vol 2533 (1) ◽  
pp. 28-38 ◽  
Author(s):  
Felipe Delgado ◽  
Juan Carlos Muñoz ◽  
Ricardo Giesen ◽  
Nigel H. M. Wilson
Keyword(s):  
Real Time ◽  
Control Strategy ◽  
High Frequency ◽  
Control Strategies ◽  
Transit Signal Priority ◽  
Operational Conditions ◽  
Traffic Lights ◽  
Wide Range ◽  
Transit Services ◽  
Capacity Constrained

Bus bunching affects transit operations by increasing passenger waiting time and variability. To tackle this phenomenon, a wide range of control strategies has been proposed. However, none of them have considered station and interstation control together. In this study station and interstation control were tackled to determine the optimal vehicle control strategy for various stops and traffic lights in a single service transit corridor. The strategy minimized the total time that users must devote to making a trip, taking into account delays for transit and general traffic users. Based on a high-frequency, capacity-constrained, and unscheduled service (no timetable) for which real-time information about bus position (GPS) and bus load (automated passenger counter) is available, this study focused on strategies for traffic signal priority in the form of green extension considered together with holding buses at stops and limiting passenger boarding at stops. The decisions on transit signal priority were made according to a rolling horizon scheme in which effects over the whole corridor were considered in every single decision. The proposed strategy was evaluated in a simulated environment under different operational conditions. Results showed that the proposed control strategy achieves reductions in the excess delay for transit users close to 61.4% compared with no control, while general traffic increases only by 1.5%.

Aerodynamic Performance of a Small Horizontal Axis Wind Turbine

2012 ◽  
Vol 134 (2) ◽  
Author(s):  
Maryam Refan ◽  
Horia Hangan
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
High Speed ◽  
Aerodynamic Performance ◽  
Horizontal Axis ◽  
Power Prediction ◽  
Horizontal Axis Wind Turbine ◽  
Wind Speeds ◽  
Wide Range ◽  
Bem Theory

The aerodynamic performance of an upwind, three-bladed, small horizontal axis wind turbine (HAWT) rotor of 2.2 m in diameter was investigated experimentally and theoretically in order to assess the applicability of the blade element momentum (BEM) theory for modeling the rotor performance for the case of small HAWTs. The wind turbine has been tested in the low and high speed sections of the Boundary Layer Wind Tunnel 2 (BLWT2) at the University of Western Ontario (UWO) in order to determine the power curve over a wide range of wind speeds. Afterward, the BEM theory has been implemented to evaluate the rotor performance and to investigate three-dimensionality effects on power prediction by the theory. Comparison between the theoretical and experimental results shows that the overall prediction of the theory is within an acceptable range of accuracy. However, the BEM theory prediction for the case of small wind turbines is not as accurate as the prediction for larger wind turbines.

Aeroelastic Response of Variable-Speed Stall-Controlled Wind Turbine Rotors

2019 ◽  
Author(s):  
Sarah Jalal ◽  
Fernando Ponta ◽  
Apurva Baruah
Keyword(s):  
Wind Turbine ◽  
Control Method ◽  
Variable Speed ◽  
Operational Conditions ◽  
Precise Control ◽  
Wind Speeds ◽  
Wide Range ◽  
Turbine Rotors ◽  
Promising Perspective ◽  
Stall Control

Abstract In this paper, we focus on the Variable-Speed (VS) stall control method, a relatively new idea, which offers a promising perspective for future applications. As with the classical Fixed-Speed (FS) stall method, the elimination of the pitch mechanism, lowers the capital cost and reduces maintenance expenses, while at the same time, allows for a more efficient and precise control of power production. We present an analysis focused on the aeroe-lastic dynamic response of wind turbine rotors operating on the Variable-Speed stall control method. We conducted a wide range of experiments to assess the effects of rapid variations on the rotor’s operational conditions, like sudden gusts. Various gust conditions were tested for different wind speeds, represented by pulses of different intensity, occurring suddenly in an otherwise constant wind regime. Results for the aeroelastic dynamics of the rotor’s response, and the frequency content of its vibrations, are reported and analyzed.

Wind-Wave Misalignment Effects on Floating Wind Turbines: Motions and Tower Load Effects

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
Erin E. Bachynski ◽  
Marit I. Kvittem ◽  
Chenyu Luan ◽  
Torgeir Moan
Keyword(s):  
Fatigue Damage ◽  
Wind Turbines ◽  
Dynamic Responses ◽  
Wave Direction ◽  
Short Term ◽  
Operational Conditions ◽  
First Order ◽  
Wind Speeds ◽  
Load Effects ◽  
Low Wind Speeds

The dynamic responses of a spar, tension leg platform (TLP), and two semisubmersible floating wind turbines (FWTs) in selected misaligned wind and wave conditions are investigated using numerical simulation with an aero-hydro-servo-elastic computational tool. For a range of representative operational conditions, the platform motions and short-term fatigue damage in the tower base and tower top are examined. Although some misalignment conditions result in increased motions both parallel and perpendicular to the wave direction, aligned wind and waves cause the largest short-term tower base fatigue damage for the studied platforms and conditions. Several factors which lead to larger fatigue damage for certain platforms in particular conditions are identified, such as tower resonance due to the 3p blade passing frequency in low wind speeds; surge and pitch motions, particularly in the wave frequency range; and the variations in first-order hydrodynamic loads due to wave direction. A semisubmersible platform with large displacement suffers the least damage at the base of the tower.

EXPERIMENTAL AND ANALYTICAL STUDIES OF VERTICAL AXIS WIND TURBINES

2018 ◽  
pp. 51-58
Author(s):  
B. P. Khozyainov
Keyword(s):  
Wind Turbine ◽  
Flow Velocity ◽  
Wind Power ◽  
Wind Turbines ◽  
Power Efficiency ◽  
Air Flow ◽  
Geometrical Parameters ◽  
Wind Speeds ◽  
Analytical Studies ◽  
Air Flow Velocity

The article carries out the experimental and analytical studies of three-blade wind power installation and gives the technique for measurements of angular rate of wind turbine rotation depending on the wind speeds, the rotating moment and its power. We have made the comparison of the calculation results according to the formulas offered with the indicators of the wind turbine tests executed in natural conditions. The tests were carried out at wind speeds from 0.709 m/s to 6.427 m/s. The wind power efficiency (WPE) for ideal traditional installation is known to be 0.45. According to the analytical calculations, wind power efficiency of the wind turbine with 3-bladed and 6 wind guide screens at wind speedsfrom 0.709 to 6.427 is equal to 0.317, and in the range of speed from 0.709 to 4.5 m/s – 0.351, but the experimental coefficient is much higher. The analysis of WPE variations shows that the work with the wind guide screens at insignificant average air flow velocity during the set period of time appears to be more effective, than the work without them. If the air flow velocity increases, the wind power efficiency gradually decreases. Such a good fit between experimental data and analytical calculations is confirmed by comparison of F-test design criterion with its tabular values. In the design of wind turbines, it allows determining the wind turbine power, setting the geometrical parameters and mass of all details for their efficient performance.

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.

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