WorldWideScience
1

Proposed Wind Turbine Aeroelasticity Studies Using Helicopter Systems Analysis  

Science.gov (United States)

Advanced systems for the analysis of rotary wing aeroelastic structures (helicopters) are being developed at NASA Ames by the Rotorcraft Aeromechanics Branch, ARA. The research has recently been extended to the study of wind turbines, used for electric power generation Wind turbines play an important role in Europe, Japan & many other countries because they are non polluting & use a renewable source of energy. European countries such as Holland, Norway & France have been the world leaders in the design & manufacture of wind turbines due to their historical experience of several centuries, in building complex wind mill structures, which were used in water pumping, grain grinding & for lumbering. Fossil fuel cost in Japan & in Europe is two to three times higher than in the USA due to very high import taxes. High fuel cost combined with substantial governmental subsidies, allow wind generated power to be competitive with the more traditional sources of power generation. In the USA, the use of wind energy has been limited mainly because power production from wind is twice as expensive as from other traditional sources. Studies conducted at the National Renewable Energy Laboratories (NREL) indicate that the main cost in the production of wind turbines is due to the materials & the labor intensive processes used in the construction of turbine structures. Thus, for the US to assume world leadership in wind power generation, new lightweight & consequently very flexible wind turbines, that could be economically mass produced, would have to be developed [4,5]. This effort, if successful, would result in great benefit to the US & the developing nations that suffer from overpopulation & a very high cost of energy.

Ladkany, Samaan G.

1998-01-01

2

Wind turbines  

Energy Technology Data Exchange (ETDEWEB)

This evaluation of wind turbines is part of a series of Technology Evaluations of possible components and subsystems of community energy systems. Wind turbines, ranging in size from 200 W to 10 MW, are discussed as candidates for prime movers in community systems. Estimates of performance characteristics and cost as a function of rated capacity and rated wind speed are presented. Data concerning material requirements, environmental effects, and operating procedures also are given and are represented empirically to aid computer simulation.

Yeoman, J.C. Jr.

1978-12-01

3

Wind turbine  

Energy Technology Data Exchange (ETDEWEB)

A vertical-axis wind turbine is described. The drive rotor of the turbine has a number of oblong blades, the central bent portions of which are of streamline shape. The particular curved shape of the blades ensures that mainly tensile stress will occur in the blade. The turbine is of the self-starting type. This is attained by starter rotors. Each of these rotors has a number of hollow blades which are arranged in opposite directions, the blades partly overlapping each other in S shape. The speed ratio of the turbine has a value of approx. 5 to 7. In practice, turbine plants may be built which consist of a number of drive rotors arranged one above the other on the shaft. Each following drive rotor has a greater diameter than the adjacent lower rotor.

Blackwell, B.F.; Feltz, L.V.; Maydew, R.C.

1976-04-08

4

Wind turbine  

Science.gov (United States)

A wind turbine of the type having an airfoil blade (15) mounted on a flexible beam (20) and a pitch governor (55) which selectively, torsionally twists the flexible beam in response to wind turbine speed thereby setting blade pitch, is provided with a limiter (85) which restricts unwanted pitch change at operating speeds due to torsional creep of the flexible beam. The limiter allows twisting of the beam by the governor under excessive wind velocity conditions to orient the blades in stall pitch positions, thereby preventing overspeed operation of the turbine. In the preferred embodiment, the pitch governor comprises a pendulum (65,70) which responds to changing rotor speed by pivotal movement, the limiter comprising a resilient member (90) which engages an end of the pendulum to restrict further movement thereof, and in turn restrict beam creep and unwanted blade pitch misadjustment.

Cheney, Jr., Marvin C. (Glastonbury, CT)

1982-01-01

5

Wind turbine  

Energy Technology Data Exchange (ETDEWEB)

A wind turbine rotatable about a shaft is described which includes a drive rotor with one or more elongated blades each having a central outwardly curved portion of airfoil shape which produces rotary motion when the blade rotates in wind at a blade tip velocity to wind velocity ratio greater than about three or four. Additional wind rotor means are disposed at both ends of the curved portions of the elongated blade for rotatably accelerating the drive rotor to the desired velocity ratio. (Official Gazette)

Blackwell, B.F.; Feltz, L.V.; Maydew, R.C.

1975-11-11

6

Proposal and Development of Radial Air-gap Coreless Generator Suitable for Small Wind Turbine using in Urban Area  

Science.gov (United States)

Independent distributed generations using small wind turbines are widely spread as increasing of wind power generation. Installation of small wind turbines in densely-populated urban area is not only useful from the viewpoint of digging up wind power source in weak-wind area but also for enlightenment of renewable energy due to closing power supplies to consumptions. From the point of view, the authors proposed “urban wind power generation" using collective system with a number of small vertical wind turbines and have developed a suitable generator for low-speed vertical wind turbines such as Savonius windmill. Standardized on a coreless generator, the proposed generator is designed to let direction of magnetic fluxes radial in order to install the magnets and coils on the outer end of the generator. The change of magnet composition and flux direction gives realization of maximized speed of flux change and output voltage in the limited space. With above composition, the power of the proposed one is independent on the diameter. In this report, we describe evaluated fundamental performance of a prototype of the proposed generator. As the result of the experiments, the maximum output power of 283W was obtained. The obtained starting torque is enough small to begin to rotate at weak wind condition of no more than 1m/s. Therefore, it is clear that the proposed “radial” coreless generator is suitable for self-starting and producing high power at low speed wind.

Takahashi, Toshiyuki; Yasuda, Yoh; Ohmoto, Shingo; Hara, Takehisa

7

Wind turbine noise diagnostics  

International Nuclear Information System (INIS)

This presentation proposed a self-consistent model for broad-band noise emitted from modern wind turbines. The simple source model was consistent with the physics of sound generation and considered the unique features of wind turbines. Although the acoustics of wind turbines are similar to those of conventional propellers, the dimensions of wind turbines pose unique challenges in diagnosing noise emission. The general features of the sound field were deduced. Source motion and source directivity appear to be responsible for amplitude variations. The amplitude modulation is likely to make wind-turbine noise more audible, and may be partly responsible for annoyance that has been reported in the literature. Acoustic array data suggests that broad-band noise is emitted predominantly during the downward sweep of each rotor blade. Source motion and source directivity account for the observed pattern. Rotor-tower interaction effects are of lesser importance. Predicted amplitude modulation ranges from 1 dB to 6dB. 2 refs., 9 figs.

8

Type IV Wind Turbine Model  

DEFF Research Database (Denmark)

This document is created as part of the EaseWind project. The goal of this project is to develop and investigate new control features for primary response provided by wind power plants. New control features as inertial response, synchronising power and power system damping are of interest to EaseWind project to be incorporated in the wind power plant level. This document describes the Type 4 wind turbine simulation model, implemented in the EaseWind project. The implemented wind turbine model is one of the initial necessary steps toward integrating new control services in the wind power plant level. In the project, this wind turbine model will be further incorporated in a wind power plant model together with the implementation in the wind power control level of the new control functionalities (inertial response, synchronising power and power system damping). For this purpose an aggregate wind power plant (WPP) will be considered. The aggregate WPP model, which will be based on the upscaling of the individualwind turbine model on the electrical part, will make use of an equivalent wind speed. The implemented model follows the basic structure of the generic standard Type 4 wind turbine model proposed by the International Electrotechnical Commission (IEC), in the IEC61400-27-1 Committee Draft for electrical simulation models for wind power generation, which is currently under review, [1]. The Type 4 wind turbine model described in this report includes a set of adjustments of the standard Type 4 wind turbine model in order account for the dynamic features of interest to EaseWind project. The document presents a short overview of the overall structure of the wind turbine model. Descriptions of individual submodels as well as some preliminary simulation results are included to illustrate the performance of the model.

Hansen, Anca Daniela; Margaris, Ioannis D.

2014-01-01

9

Small wind turbines  

CERN Document Server

Small Wind Turbines provides a thorough grounding in analysing, designing, building, and installing a small wind turbine. Small turbines are introduced by emphasising their differences from large ones and nearly all the analysis and design examples refer to small turbines.The accompanying software includes MATLAB(R) programs for power production and starting performance, as well as programs for detailed multi-objective optimisation of blade design. A spreadsheet is also given to help readers apply the simple load model of the IEC standard for small wind turbine safety. Small Wind Turbines repr

Wood, David

2011-01-01

10

A proposed metric for assessing the potential of community annoyance from wind turbine low-frequency noise emissions  

Energy Technology Data Exchange (ETDEWEB)

Given our initial experience with the low-frequency, impulsive noise emissions from the MOD-1 wind turbine and their impact on the surrounding community, the ability to assess the potential of interior low-frequency annoyance in homes located near wind turbine installations may be important. Since there are currently no universally accepted metrics or descriptors for low-frequency community annoyance, we performed a limited program using volunteers to see if we could identify a method suitable for wind turbine noise applications. We electronically simulated three interior environments resulting from low-frequency acoustical loads radiated from both individual turbines and groups of upwind and downwind turbines. The written comments of the volunteers exposed to these interior stimuli were correlated with a number of descriptors which have been proposed for predicting low-frequency annoyance. The results are presented in this paper. We discuss our modifications of the highest correlated predictor to include the internal dynamic pressure effects associated with the response of residential structures to low-frequency acoustic loads. Finally, we outline a proposed procedure for establishing both a low-frequency ''figure of merit'' for a particular wind turbine design and, using actual measurements, estimate the potential for annoyance to nearby communities. 10 refs., 13 figs., 7 tabs.

Kelley, N.D.

1987-10-05

11

Wind turbine technology  

CERN Document Server

Presents an introduction to the wind turbine technology, which can generate electrical energy with lower costs and zero greenhouse effects. Highlighting limitations, capabilities, and benefits, this text identifies the critical components of a wind turbine and describes the functional capabilities of each component.

Jha, A R

2010-01-01

12

Noise from wind turbines  

Energy Technology Data Exchange (ETDEWEB)

A rapid growth of installed wind power capacity is expected in the next few years. However, the siting of wind turbines on a large scale raises concerns about their environmental impact, notably with respect to noise. To this end, variable speed wind turbines offer a promising solution for applications in densely populated areas like the European countries, as this design would enable an efficient utilisation of the masking effect due to ambient noise. In rural and recreational areas where wind turbines are sited, the ambient noise originates from the action of wind on the vegetation and about the listener's ear (pseudo-noise). It shows a wind speed dependence similar to that of the noise from a variable speed wind turbine and can therefore mask the latter for a wide range of conditions. However, a problem inherent to the design of these machines is their proclivity to pure tone generation, because of the enhanced difficulty of avoiding structural resonances in the mechanical parts. Pure tones are deemed highly annoying and are severely regulated by most noise policies. In relation to this problem, the vibration transmission of structure-borne sound to the tower of the turbine is investigated, in particular when the tower is stiffened at its upper end. Furthermore, since noise annoyance due to wind turbine is mostly a masking issue, the wind-related sources of ambient noise are studied and their masking potentials assessed. With this aim, prediction models for wind-induced vegetation noise and pseudo-noise have been developed. Finally, closely related to the effect of masking, is the difficulty, regularly encountered by local authorities and wind farm developers, to measure noise immission from wind turbines. A new measurement technique has thus been developed in the course of this work. Through improving the signal-to-noise ratio between wind turbine noise and ambient noise, the new technique yields more accurate measurement results.

Fegeant, Olivier [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Building Sciences

2002-02-01

13

Noise from wind turbines  

International Nuclear Information System (INIS)

Denmark has 3200 wind turbines with an installed maximum capacity of 418MW. The most important Danish research projects into wind turbine noise and the main results are listed. These date from 1983. Two comprehensive studies are currently in progress. The first is an analytical and empirical investigation of aerodynamic noise from wind turbine rotors and has so far dealt mainly with tip noise. The measurement method, using a hard board mounted microphone on the ground near the turbine, is described. Four different tip designs have been tested. Some examples of reference sound power level spectra for three of the designs are presented. During the past two years a computerbased data acquisition system has been used for real-time determination of sound power levels. The second study, which has just commenced, is on annoyance from wind turbine noise. It will include noise measurements, masking calculations and a social survey on the perceived nuisance. (UK)

14

Build a Wind Turbine  

Science.gov (United States)

Learners build a wind turbine and test it to see how much energy is created. Learners can build a variety of wind blades, test a variety of wind speeds and see what effect these have on the energy created. Adult supervision recommended.

Museum of Science and Industry, Chicago

2012-01-01

15

Wind turbines. Fiction and facts  

International Nuclear Information System (INIS)

The author gives a personal impression of factual and fictional data with respect to different aspects of wind turbines: properties, the production or capacity factor, emission of CO2, the consumption of electricity in the Netherlands, performance, cost price and exploitation costs of wind turbines, environmental effects, government policy, energy yield of 442 wind turbines at 36 sites in the Netherlands, wind turbine projects, and the value of a so-called environmental impact report for wind turbines

16

An integrated modeling method for wind turbines  

Science.gov (United States)

To study the interaction of the electrical, mechanical, and aerodynamic aspects of a wind turbine, a detailed model that considers all these aspects must be used. A drawback of many studies in the area of wind turbine simulation is that either a very simple mechanical model is used with a detailed electrical model, or vice versa. Hence the interactions between electrical and mechanical aspects of wind turbine operation are not accurately taken into account. In this research, it will be shown that a combination of different simulation packages, namely TurbSim, FAST, and Simulink can be used to model the aerodynamic, mechanical, and electrical aspects of a wind turbine in detail. In this thesis, after a review of some wind turbine concepts and software tools, a simulation structure is proposed for studying wind turbines that integrates the mechanical and electrical components of a wind energy conversion device. Based on the simulation structure, a comprehensive model for a three-bladed variable speed wind turbine with doubly-fed induction generator is developed. Using the model, the impact of a voltage sag on the wind turbine tower vibration is investigated under various operating conditions such as power system short circuit level, mechanical parameters, and wind turbine operating conditions. It is shown how an electrical disturbance can cause more sustainable tower vibrations under high speed and turbulent wind conditions, which may disrupt the operation of pitch control system. A similar simulation structure is used to model a two-bladed fixed speed wind turbine with an induction generator. An extension of the concept is introduced by adding a diesel generator system. The model is utilized to study the impact of the aeroelastic aspects of wind turbine (i.e. tower shadow, wind shears, yaw error, turbulence, and mechanical vibrations) on the power quality of a stand-alone wind-diesel system. Furthermore, an IEEE standard flickermeter model is implemented in a Simulink environment to study the flicker contribution of the wind turbine in the wind-diesel system. By using a new wind power plant representation method, a large wind farm (consisting of 96 fixed speed wind turbines) is modelled to study the power quality of wind power system. The flicker contribution of wind farm is also studied with different wind turbine numbers, using the flickermeter model. Keywords. Simulink, FAST, TurbSim, AreoDyn, wind energy, doubly-fed induction generator, variable speed wind turbine, voltage sag, tower vibration, power quality, flicker, fixed speed wind turbine, wind shear, tower shadow, and yaw error.

Fadaeinedjad, Roohollah

17

Direct drive wind turbine  

Science.gov (United States)

A wind turbine is provided that minimizes the size of the drive train and nacelle while maintaining the power electronics and transformer at the top of the tower. The turbine includes a direct drive generator having an integrated disk brake positioned radially inside the stator while minimizing the potential for contamination. The turbine further includes a means for mounting a transformer below the nacelle within the tower.

Bywaters, Garrett; Danforth, William; Bevington, Christopher; Jesse, Stowell; Costin, Daniel

2007-02-27

18

Annoyance rating of wind turbine noise  

International Nuclear Information System (INIS)

This paper proposes a simple criterion for noise limitation of wind turbines: 'The LaA50 from a Wind Farm should not exceeding the LA50 of the wind generated background plus 5dB at any place of potential complaint'. This criterion is then examined and developed in the light of experience to date with turbine noise complaint and procedures. (author)

19

Wind Turbine Blade Design  

Science.gov (United States)

Students go through the design process and the scientific method to test the effect of blade design on power output. There is an optional extension to use the data to create an optimal set of wind turbine blades.

Kidwind Project

20

Vertical axis wind turbines  

Science.gov (United States)

A vertical axis wind turbine is described. The wind turbine can include a top ring, a middle ring and a lower ring, wherein a plurality of vertical airfoils are disposed between the rings. For example, three vertical airfoils can be attached between the upper ring and the middle ring. In addition, three more vertical airfoils can be attached between the lower ring and the middle ring. When wind contacts the vertically arranged airfoils the rings begin to spin. By connecting the rings to a center pole which spins an alternator, electricity can be generated from wind.

Krivcov, Vladimir (Miass, RU); Krivospitski, Vladimir (Miass, RU); Maksimov, Vasili (Miass, RU); Halstead, Richard (Rohnert Park, CA); Grahov, Jurij (Miass, RU)

2011-03-08

21

Wind turbines and health  

Energy Technology Data Exchange (ETDEWEB)

This document summarized the potential health hazards associated with wind turbines, such as noise and low frequency sound, vibration and infrasound; electromagnetic fields (EMF); shadow flicker; and ice throw and structural failure. Various symptoms can be attributed to wind turbines, including dizziness, sleep disruption, and headaches. A review of available research regarding potential health affects to residents living in close proximity to wind turbines showed that the sound level associated with wind turbines at common residential setbacks is not sufficient to damage hearing, but may lead to annoyance and sleep disturbance. Research has shown that wind turbines are not a significant source of EMF exposure, and although shadows caused by the blades may be annoying, they are not likely to cause epileptic seizures at normal operational speeds. The risk of injury from ice throw can be minimized with setbacks of 200 to 400 m. Examples of Canadian wind turbine setback guidelines and regulations were also offered. It was concluded that setbacks and operational guidelines can be utilized in combination to address safety hazards, sound levels, land use issues, and impacts on people. 46 refs., 2 tabs., 2 figs.

Rideout, K.; Copes, R.; Bos, C. [National Colaborating Centre for Environmental Health, Vancouver, BC (Canada)

2010-01-15

22

Wind turbines and health  

International Nuclear Information System (INIS)

This document summarized the potential health hazards associated with wind turbines, such as noise and low frequency sound, vibration and infrasound; electromagnetic fields (EMF); shadow flicker; and ice throw and structural failure. Various symptoms can be attributed to wind turbines, including dizziness, sleep disruption, and headaches. A review of available research regarding potential health affects to residents living in close proximity to wind turbines showed that the sound level associated with wind turbines at common residential setbacks is not sufficient to damage hearing, but may lead to annoyance and sleep disturbance. Research has shown that wind turbines are not a significant source of EMF exposure, and although shadows caused by the blades may be annoying, they are not likely to cause epileptic seizures at normal operational speeds. The risk of injury from ice throw can be minimized with setbacks of 200 to 400 m. Examples of Canadian wind turbine setback guidelines and regulations were also offered. It was concluded that setbacks and operational guidelines can be utilized in combination to address safety hazards, sound levels, land use issues, and impacts on people. 46 refs., 2 tabs., 2 figs.

23

Alcoa wind turbines  

Science.gov (United States)

An overview of Alcoa's wind energy program is given with emphasis on the the development of a low cost, reliable Darrieus Vertical Axis Wind Turbine System. The design layouts and drawings for fabrication are now complete, while fabrication and installation to utilize the design are expected to begin shortly.

Ai, D. K.

1979-01-01

24

Wind turbine state estimation  

DEFF Research Database (Denmark)

Dynamic inflow is an effect which is normally not included in the models used for wind turbine control design. Therefore, potential improvement from including this effect exists. The objective in this project is to improve the methods previously developed for this and especially to verify the results using full-scale wind turbine data. The previously developed methods were based on extended Kalman filtering. This method has several drawback compared to unscented Kalman filtering which has therefore been developed. The unscented Kalman filter was first tested on linear and non-linear test cases which was successful. Then the estimation of a wind turbine state including dynamic inflow was tested on a simulated NREL 5MW turbine was performed. This worked perfectly with wind speeds from low to nominal wind speed as the output prediction errors where white. In high wind where the pitch actuator was always active the results where not as convincing because the output prediction errors where not white. Usingreal data it has not been possible to get really good results so far. There remains a number of challenges: verifying turbine parameters and getting the most suitable measurement signals, including the 3P effect in the model and perhaps including the 1P effect. It is obviously difficult to make a final conclusion before the above challenges has been resolved.

Knudsen, Torben

2014-01-01

25

Floating wind turbine system  

Science.gov (United States)

A floating wind turbine system with a tower structure that includes at least one stability arm extending therefrom and that is anchored to the sea floor with a rotatable position retention device that facilitates deep water installations. Variable buoyancy for the wind turbine system is provided by buoyancy chambers that are integral to the tower itself as well as the stability arm. Pumps are included for adjusting the buoyancy as an aid in system transport, installation, repair and removal. The wind turbine rotor is located downwind of the tower structure to allow the wind turbine to follow the wind direction without an active yaw drive system. The support tower and stability arm structure is designed to balance tension in the tether with buoyancy, gravity and wind forces in such a way that the top of the support tower leans downwind, providing a large clearance between the support tower and the rotor blade tips. This large clearance facilitates the use of articulated rotor hubs to reduced damaging structural dynamic loads. Major components of the turbine can be assembled at the shore and transported to an offshore installation site.

Viterna, Larry A. (Inventor)

2009-01-01

26

Wind Turbine Acoustics  

Science.gov (United States)

Wind turbine generators, ranging in size from a few kilowatts to several megawatts, are producing electricity both singly and in wind power stations that encompass hundreds of machines. Many installations are in uninhabited areas far from established residences, and therefore there are no apparent environmental impacts in terms of noise. There is, however, the potential for situations in which the radiated noise can be heard by residents of adjacent neighborhoods, particularly those neighborhoods with low ambient noise levels. A widely publicized incident of this nature occurred with the operation of the experimental Mod-1 2-MW wind turbine, which is described in detail elsewhere. Pioneering studies which were conducted at the Mod-1 site on the causes and remedies of noise from wind turbines form the foundation of much of the technology described in this chapter.

Hubbard, Harvey H.; Shepherd, Kevin P.

2009-01-01

27

Wind turbine optimal control during storms  

Science.gov (United States)

This paper proposes a control algorithm that enables wind turbine operation in high winds. With this objective, an online optimization procedure is formulated that, based on the wind turbine state, estimates those extremal wind speed variations that would produce maximal allowable wind turbine loads. Optimization results are compared to the actual wind speed and, if there is a danger of excessive loading, the wind turbine power reference is adjusted to ensure that loads stay within allowed limits. This way, the machine can operate safely even above the cut-out wind speed, thereby realizing a soft envelope-protecting cut-out. The proposed control strategy is tested and verified using a high-fidelity aeroservoelastic simulation model.

Petrovi?, V.; Bottasso, C. L.

2014-06-01

28

Wind turbines, is it just wind?  

International Nuclear Information System (INIS)

The author first outlines that wind energy is not only random, but almost absent in extreme situations when it would be needed (for example and notably, very cold weather without wind). He suggests the association of a gas turbine to each wind turbine, so that the gas turbine will replace non operating wind turbines. He notices that wind turbines are not proximity energy as they were said to be, and that profitability in fact requires tens of grouped giant wind turbines. He also outlines the high cost of construction of grids for the connection of these wind turbines. Thus, he states that wind energy is far from being profitable in the present conditions of electricity tariffs in France

29

Superconducting wind turbine generators  

DEFF Research Database (Denmark)

A HTS machine could be a way to address some of the technical barriers offshore wind energy is about to face. Due to the superior power density of HTS machines, this technology could become a milestone on which many, including the wind industry, will rely on in the future. The work presented in this thesis is a part of a larger endeavor, the Superwind project that focused on identifying the potentials that HTS machines could offer to the wind industry and addressing some of the challenges in the process. In order to identify these challenges, I have designed and constructed an HTS machine experimental setup which is made to serve as precursor, leading towards an optimized HTS machine concept proposed for wind turbines. In part, the work presented in this thesis will focus on the description of the experimental setup and reasoning behind the choices made during the design. The setup comprises an HTS synchronous machine where a revolv- ing armature winding spins around an open bath liquid nitrogen cryostat, which contains the HTS coils cooled down to 77 K. A significant part of the thesis is allocated to the description of the setup, particularly the torque transfer element and the compact cryostat design, where a concept with 20 W of heat transfer is achieved. Following the setup description, the focus turns to the electromagnetic design of the HTS machine. Particularly, an approach to increase the performance of HTS coils and the influence of the armature reaction to the HTS field winding will be discussed. Two design strategies are proposed, novel in a machine design, in order to reduce the amount of HTS required in a machine whereby the merits of both have been experimentally verified. The first employs a multiple HTS types in the machine design, since each type of the HTS tape has a specific magnetic characteristic with respect to the critical current. I have showed that the potential for the reduction of HTS conductor can be significant, if the coils are placed strategically, whereby the coils wound with BSCCO performed 40% better depending on the placement in the field winding. The 2G coils were less sensitive to the placement which made them particularly useful for high magnetic field regions in the eld winding. The second design approach proposed and tested was to use multiple current supplies which allowed each coil to operate close to its critical current. I have demonstrated that by introducing one additional power supply, an order of 12% higher MMF was generated (or equivalent HTS savings achieved). Increasing in the number of additional power supplies did not show the same potential for HTS reduction. The implications of an armature reaction impact on the HTS field Winding performance were examined and veried throughout a series of Locked Armature experiments. The interaction have been dened in the terms of two (direct and quadrature) axis machine theory (Park transformation), where significant reduction of 20% was observed for the rated armature reaction in the q axis. Building on this observation,a control strategy for the excitation current to improve a partial load eciency of a HTS machine is proposed. Thus, this work has shown that a signicant savings of a the costly HTS tape could be realized indicating that the HTS machine design can still be optimized towards more competitive alternative to conventional machines. Additionally, by constructing the HTS machine setup we went through most of the issues related to the HTS machine design which we managed to address in rather simple manner using everyday materials and therefore proving that HTS machines are close to commercialization.

Mijatovic, Nenad

2014-01-01

30

Operation Design of Wind Turbines in Strong Wind Conditions  

DEFF Research Database (Denmark)

In order to reduce the impact on the electrical grid from the shutdown of MW wind turbines at wind speeds higher than the cut-out wind speed of 25 m/s, we propose in this paper to run the turbines at high wind speeds up to 40 m/s. Two different operation designs are made for both constant speed and variable speed pitch regulated wind turbines. The variable speed design is more suitable for wind turbines to run at very high wind speeds which can help the turbine braking system to stop the turbine at the new "cut-out" wind speed. Reference power, rotational speed and pitch angle have been designed optimally. In order to reduce the possible increased loading, fatigue due to the wind gusts, control strategies have been considered for both constant sped and variable speed pitch regulated wind turbines. The control study shows that the designed controllers can reduce the standard deviations efficiently for wind turbines at some selected wind high speeds.

Shen, Wen Zhong; Montes, Melissa Barroso

2012-01-01

31

Wind conditions for wind turbine design  

Energy Technology Data Exchange (ETDEWEB)

Delegates from Europe and USA attended the meeting and discussed general aspects of wind conditions for wind turbine design. The subjects and the presented papers covered a very broad range of aspects of wind conditions and related influence on the wind turbine. (EHS)

Maribo Pedersen, B.

1999-04-01

32

Noise from wind turbines  

OpenAIRE

A rapid growth of installed wind power capacity is expectedin the next few years. However, the siting of wind turbines ona large scale raises concerns about their environmental impact,notably with respect to noise. To this end, variable speed windturbines offer a promising solution for applications in denselypopulated areas like the European countries, as this designwould enable an efficient utilisation of the masking effect dueto ambient noise. In rural and recreational areas where windturbi...

Fe?geant, Olivier

2001-01-01

33

Vision on Mini Wind Turbines  

International Nuclear Information System (INIS)

This document sketches the vision of the Netherlands Wind Energy Association (NWEA) with respect to the options for implementing small wind turbines in the Netherlands. Next to a description of the characteristics of mini turbines, mini turbines are compared to large wind turbines and solar panels and unique opportunities for mini turbines are described. Next, the market is described as well as the bottlenecks and their solutions. Finally ongoing projects with mini turbines are described, an estimate is provided for the potential for mini turbines and the ambitions are discussed as well as the recommended action plan.

34

Build a Wind Turbine  

Science.gov (United States)

This hands-on project provides step-by-step instructions for building a vertical axis wind turbine in secondary classrooms. The 17-page construction plans may be freely downloaded and are organized for first-time builders. Comprehensive background information on wind energy and renewable energy are provided. Registered teacher-users also have access to supporting lesson plans. All of the materials are readily available in hardware or grocery stores. This resource, which meets multiple national science standards, was developed to spark students' interest in learning more about renewable energy sources and the science and engineering principles that underlie the harnessing of renewable power. Editor's Note: Wind turbines work by using an internal generator to convert the mechanical energy of the spinning turbine shaft into electricity. This particular project is modeled after the Savonius rotor system, which uses uses drag -- not lift -- to capture energy for making electricity. Although it isn't as efficient as a conventional horizontal axis turbine, it is much easier to build.

2007-10-25

35

Rotating transformers in wind turbine applications  

Energy Technology Data Exchange (ETDEWEB)

The power consumption of rotating electrical components is often supplied via slip-rings in wind turbines. Slip-ring equipment is expensive and need maintenance and are prone to malfunction. If the slip-rings could be replaced with contact-less equipment better turbines could be designed. This paper presents the design, some FE calculations and some measurements on a prototype rotating transformer. The proposed transformer consists of a secondary rotating winding and a stationary exciting primary winding. The results indicate that this transformer could be used to replace slip-rings in wind turbines. 4 refs, 3 figs

Hylander, J. [Chalmers Univ. of Technology, Goeteborg (Sweden); Engstroem, S. [Aegir konsult AB, Lidingoe (Sweden)

1996-12-01

36

Optimal control of variable speed wind turbines  

OpenAIRE

This paper proposes a MIMO linear quadratic regulator (LQR) controller designed for a horizontal variable speed wind turbine with focus on the operating range referring to the above rated wind speeds. The operating conditions of wind turbines make them subject to fluctuating loads that create fatigue and lead to damage. Alleviating these loads would reduce the needed materials, and increase the lifespan and the quality of the produced energy. The optimality of the entire system is defined in ...

Pintea, Andreea; Christov, Nicolai; Borne, Pierre; Popescu, Dumitru; Badea, A.

2011-01-01

37

Aeroservoelasticity of Wind Turbines  

DEFF Research Database (Denmark)

This thesis deals with the fundamental aeroelastic interaction between structural motion, Pitch action and control for a wind turbine blade. As wind turbines become larger, the interaction between pitch action, blade motion, aerodynamic forces, and control become even more important to understand and address. The main contribution of this thesis is the development of an aeroelastic blade model which on the one hand includes the important effects of steady state blade deformation, gravity and pitch action, and on the other it is transparent, suitable for analytical analysis and parameter studies, and furthermore linear and therefore suitable for control design. The development of the primary aeroelastic blade model is divided into four steps: 1) Nonlinear partial differential equations (PDEs) of structural blade motion are derived together with equations of pitch action and rotor speed; the individual terms in these equations are discussed and given physical interpretations; 2) Steady state blade deformation and induced velocities are computed by combining the PDEs with a steady state aerodynamic model; 3) Aeroelastic modes of motion are computed by combining the linearized PDEs with a linear unsteady aerodynamic model; this model is used to analyze how blade deformation effects the modes of motion; and 4) the linear aeroelastic blade model is derived by a modal expansion of the linearized PDEs combined with a linear unsteady aerodynamic model. The aeroelastic blade model has many similarities to a 2D blade section model, and it can be used instead of this in many applications, giving a transparent connection to a real wind turbine blade. In this work the aeroelastic blade model is used to analyze interaction between pitch action, blade motion and wind speed variations. Furthermore the model is used to develop a state estimator for estimating the wind speed and wind shear, and to suggest a load reducing controller. The state estimator estimates the wind shear very well and the load reducing controller is capable of reducing flapwise blade motion caused by wind shear with 75 % under ideal conditions. So, a new aeroelastic blade model has been derived, which includes important features of large wind turbines, yet simple enough to be suitable for analytical analysis and control design.

KallesØe, Bjarne Skovmose

2007-01-01

38

Aeroservoelasticity of wind turbines  

Energy Technology Data Exchange (ETDEWEB)

This thesis deals with the fundamental aeroelastic interaction between structural motion, Pitch action and control for a wind turbine blade. As wind turbines become larger, the interaction between pitch action, blade motion, aerodynamic forces, and control become even more important to understand and address. The main contribution of this thesis is the development of an aeroelastic blade model which on the one hand includes the important effects of steady state blade deformation, gravity and pitch action, and on the other it is transparent, suitable for analytical analysis and parameter studies, and furthermore linear and therefore suitable for control design. The development of the primary aeroelastic blade model is divided into four steps: 1) Nonlinear partial differential equations (PDEs) of structural blade motion are derived together with equations of pitch action and rotor speed; the individual terms in these equations are discussed and given physical interpretations; 2) Steady state blade deformation and induced velocities are computed by combining the PDEs with a steady state aerodynamic model; 3) Aeroelastic modes of motion are computed by combining the linearized PDEs with a linear unsteady aerodynamic model; this model is used to analyze how blade deformation effects the modes of motion; and 4) the linear aeroelastic blade model is derived by a modal expansion of the linearized PDEs combined with a linear unsteady aerodynamic model. The aeroelastic blade model has many similarities to a 2D blade section model, and it can be used instead of this in many applications, giving a transparent connection to a real wind turbine blade. In this work the aeroelastic blade model is used to analyze interaction between pitch action, blade motion and wind speed variations. Furthermore the model is used to develop a state estimator for estimating the wind speed and wind shear, and to suggest a load reducing controller. The state estimator estimates the wind shear very well and the load reducing controller is capable of reducing flapwise blade motion caused by wind shear with 75 % under ideal conditions. So, a new aeroelastic blade model has been derived, which includes important features of large wind turbines, yet simple enough to be suitable for analytical analysis and control design. (au)

Skovmose Kallesoee, B.

2007-12-14

39

Wind tower augmentation of wind turbines  

Science.gov (United States)

The operating principle of the 'Baud-Geers' wind towers traditionally used in Iran for ventilation and passive cooling of architectural structures is presently adapted to house a vertical axis wind turbine. Unlike annular diffuser-augmented, horizontal axis wind turbines, the 'wind tower' does not have to be trained into the wind and generates less noise. It may also be either free standing or incorporated into the structure of existing buildings. Attention is given to the continuity and energy equations of this system, and to the results of wind tunnel model testing which ascertained turbine load factor and augmentation ratio.

Bahadori, M. N.

40

Small Wind Turbine Technology Assessment  

International Nuclear Information System (INIS)

The result of the study carried out under the scope of the ATYCA project Test Plant of Wind Systems for Isolated Applications, about the state of art of the small wind turbine technology (wind turbines with swept area smaller than 40 m2) is presented. The study analyzes the collected information on 60 models of wind turbines from 23 manufacturers in the worldwide market. Data from Chinese manufacturers, that have a large participation in the total number of small wind turbines in operation, are not included, due to the unavailability of the technical information. (Author) 15 refs

41

Harmonic Current Predictors for Wind Turbines  

Directory of Open Access Journals (Sweden)

Full Text Available The harmonic impact caused by wind turbines should be carefully investigated before wind turbines are interconnected. However, the harmonic currents of wind turbines are not easily predicted due to the variations of wind speed. If the harmonic current outputs can be predicted accurately, the harmonic impact of wind turbines and wind farms for power grids can be analyzed efficiently. Therefore, this paper analyzes the harmonic current characteristics of wind turbines and investigates the feasibility of developing harmonic current predictors. Field measurement, data sorting, and analysis are conducted for wind turbines. Two harmonic current predictors are proposed based on the measured harmonic data. One is the Auto-Regressive and Moving Average (ARMA-based harmonic current predictor, which can be used for real-time prediction. The other is the stochastic harmonic current predictor considering the probability density distributions of harmonic currents. It uses the measured harmonic data to establish the probability density distributions of harmonic currents at different wind speeds, and then uses them to implement a long-term harmonic current prediction. Test results use the measured data to validate the forecast ability of these two harmonic current predictors. The ARMA-based predictor obtains poor performance on some harmonic orders due to the stochastic characteristics of harmonic current caused by the variations of wind speed. Relatively, the prediction results of stochastic harmonic current predictor show that the harmonic currents of a wind turbine in long-term operation can be effectively analyzed by the established probability density distributions. Therefore, the proposed stochastic harmonic current predictor is helpful in predicting and analyzing the possible harmonic problems during the operation of wind turbines and wind farms.

Shun-Yu Chan

2013-03-01

42

Pitchcontrol of wind turbines using model free adaptivecontrol based on wind turbine code  

DEFF Research Database (Denmark)

As the wind turbine is a nonlinear high-order system, to achieve good pitch control performance, model free adaptive control (MFAC) approach which doesn't need the mathematical model of the wind turbine is adopted in the pitch control system in this paper. A pseudo gradient vector whose estimation value is only based on I/O data of the wind turbine is identified and then the wind turbine system is replaced by a dynamic linear time-varying model. In order to verify the correctness and robustness of the proposed model free adaptive pitch controller, the wind turbine code FAST which can predict the wind turbine loads and response in high accuracy is used. The results show that the controller produces good dynamic performance, good robustness and adaptability.

Zhang, Yunqian; Chen, Zhe

2011-01-01

43

Wind Turbine Blade  

DEFF Research Database (Denmark)

The invention relates to a blade for a wind turbine, particularly to a blade that may be produced by an advanced manufacturing process for producing a blade with high quality structural components. Particularly, the structural components, which are preferably manufactured from fibre reinforced plastic material, will have a high level of stretched fibres as well as a far better controlled resin distribution and content and also a low void content.

Jensen, Find MØlholt Technical University of Denmark,

44

Make Your Own Wind Turbine  

Science.gov (United States)

In this activity, learners create a wind turbine model using a simple pattern, a thumbtack, and a pencil with an eraser. After constructing the model, learners blow on the wind turbine to simulate the wind. Use this activity to introduce alternative energy and electricity generation.

National Museum of American History

2012-06-26

45

Wind Power! Designing a Wind Turbine  

Science.gov (United States)

Students learn how engineers transform wind energy into electrical energy by building their own miniature wind turbines and measuring the electrical current it produces. They explore how design and position affect the electrical energy production.

Integrated Teaching and Learning Program,

46

The VGOT Darrieus wind turbine  

Energy Technology Data Exchange (ETDEWEB)

We present the actual state of development of a non-conventional new vertical-axis wind turbine. The concepts introduced here involve the constructive aspects of variable-geometry oval-trajectory (VGOT) Darrieus wind turbines. The key feature of a VGOT machine is that each blade slides over rails mounted on a wagon instead of rotating around a central vertical axis. Each wagon contains its own electrical generation system coupled to the power-wheels and the electricity is collected by a classical third rail system. The VGOT concept allows increasing the area swept by the blades, and hence the power output of the installation, without the structural problems and the low rotational speed associated with a classical Darrieus rotor of large diameter. We also propose some engineering solutions for the VGOT design and present a brief economic analysis of the feasibility of the project. (author)

Ponta, F.L.; Otero, A.D.; Lago, L. [University of Buenos Aires (Argentina). College of Engineering

2004-07-01

47

Online wind turbine measurement laboratory  

OpenAIRE

As part of the International Master of Science Program in Wind Energy at DTU, a complete interactive wind turbine measurement laboratory has been developed. A 500 kW stall regulated wind turbine has been instrumented with sensors for recording 1) turbine operational parameters, 2) meteorological conditions, 3) electrical quantities and 4) mechanical loads in terms of strain gauge signals. The data acquisition system has been designed and implemented by Risø together with students...

Hansen, K. S.; Helgesen Pedersen, K. O.; Schmidt Paulsen, U.

2012-01-01

48

Wind turbine. Windturbine  

Energy Technology Data Exchange (ETDEWEB)

The purpose of the invention is to simplify the construction of wind turbines and to improve their output. According to the invention this problem is solved by a stator which can be set on the free ends of chimneys or tubular towers, which supports a concentric movable hollow cylindrical support with air blades on the outside and wind rotors fixed in its central opening. The stator is preferably formed from a framework anchored to the chimney by at least one horizontal supporting ring, on which the support sits. The rotor is formed so that there is the simultaneous possibility of using the force of the wind and the chimney effect which is always present in these structures, which is caused by stack gas or hot air, e.g. waste air from greenhouses, to produce rotation.

Knipfer, A.

1981-09-24

49

Methodological proposal for the design of the turbine blades of wind of horizontal axis  

International Nuclear Information System (INIS)

A methodology is developed to estimate the chord distribution airfoil and blade twist along the radius of the blade by using axial and angular moment conservation equations, blade element theory and optimization processes. This methodology takes into account the concept related with getting wind power for different chord blade values and selecting one that facilitates to get the maximum value for wind power. This work is based on project wind energy market in Colombia: operation, risk and expansion possibilities

50

Numerical investigation of wind turbine and wind farm aerodynamics  

Science.gov (United States)

A numerical method based on the solution of Reynolds Averaged Navier Stokes equations and actuator disk representation of turbine rotor is developed and implemented in the OpenFOAM software suite for aerodynamic analysis of horizontal axis wind turbines (HAWT). The method and the implementation are validated against the 1-D momentum theory, the blade element momentum theory and against experimental data. The model is used for analyzing aerodynamics of a novel dual rotor wind turbine concept and wind farms. Horizontal axis wind turbines suffer from aerodynamic inefficiencies in the blade root region (near the hub) due to several non-aerodynamic constraints (e.g., manufacturing, transportation, cost, etc.). A new dual-rotor wind turbine (DRWT) concept is proposed that aims at mitigating these losses. A DRWT is designed using an existing turbine rotor for the main rotor (Risoe turbine and NREL 5 MW turbine), while the secondary rotor is designed using a high lift to drag ratio airfoil (the DU 96 airfoil from TU Delft). The numerical aerodynamic analysis method developed as a part of this thesis is used to optimize the design. The new DRWT design gives an improvement of about 7% in aerodynamic efficiency over the single rotor turbine. Wind turbines are typically deployed in clusters called wind farms. HAWTs also suffer from aerodynamic losses in a wind farm due to interactions with wind turbine wakes. An interesting mesoscale meteorological phenomenon called "surface flow convergence" believed to be caused by wind turbine arrays is investigated using the numerical method developed here. This phenomenon is believed to be caused by the pressure gradient set up by wind turbines operating in close proximity in a farm. A conceptual/hypothetical wind farm simulation validates the hypothesis that a pressure gradient is setup in wind farms due to turbines and that it can cause flow veering of the order of 10 degrees. Simulations of a real wind farm (Story County) are also conducted which give qualitatively correct flow direction change, however quantitative agreement with data is only moderately acceptable.

Selvaraj, Suganthi

51

Equivalent models of wind farms by using aggregated wind turbines and equivalent winds  

International Nuclear Information System (INIS)

As a result of the increasing wind farms penetration on power systems, the wind farms begin to influence power system, and therefore the modeling of wind farms has become an interesting research topic. In this paper, new equivalent models of wind farms equipped with wind turbines based on squirrel-cage induction generators and doubly-fed induction generators are proposed to represent the collective behavior on large power systems simulations, instead of using a complete model of wind farms where all the wind turbines are modeled. The models proposed here are based on aggregating wind turbines into an equivalent wind turbine which receives an equivalent wind of the ones incident on the aggregated wind turbines. The equivalent wind turbine presents re-scaled power capacity and the same complete model as the individual wind turbines, which supposes the main feature of the present equivalent models. Two equivalent winds are evaluated in this work: (1) the average wind from the ones incident on the aggregated wind turbines with similar winds, and (2) an equivalent incoming wind derived from the power curve and the wind incident on each wind turbine. The effectiveness of the equivalent models to represent the collective response of the wind farm at the point of common coupling to grid is demonstrated by comparison with the wind farm response obtained from the detailed model during power system dynamic simulations, such as wind fluctuations and a grid disturbance. The presenuations and a grid disturbance. The present models can be used for grid integration studies of large power system with an important reduction of the model order and the computation time

52

Superconducting wind turbine generators  

Science.gov (United States)

We have examined the potential of 10 MW superconducting direct drive generators to enter the European offshore wind power market and estimated that the production of about 1200 superconducting turbines until 2030 would correspond to 10% of the EU offshore market. The expected properties of future offshore turbines of 8 and 10 MW have been determined from an up-scaling of an existing 5 MW turbine and the necessary properties of the superconducting drive train are discussed. We have found that the absence of the gear box is the main benefit and the reduced weight and size is secondary. However, the main challenge of the superconducting direct drive technology is to prove that the reliability is superior to the alternative drive trains based on gearboxes or permanent magnets. A strategy of successive testing of superconducting direct drive trains in real wind turbines of 10 kW, 100 kW, 1 MW and 10 MW is suggested to secure the accumulation of reliability experience. Finally, the quantities of high temperature superconducting tape needed for a 10 kW and an extreme high field 10 MW generator are found to be 7.5 km and 1500 km, respectively. A more realistic estimate is 200-300 km of tape per 10 MW generator and it is concluded that the present production capacity of coated conductors must be increased by a factor of 36 by 2020, resulting in a ten times lower price of the tape in order to reach a realistic price level for the superconducting drive train.

Abrahamsen, A. B.; Mijatovic, N.; Seiler, E.; Zirngibl, T.; Træholt, C.; Nørgård, P. B.; Pedersen, N. F.; Andersen, N. H.; Østergård, J.

2010-03-01

53

Superconducting wind turbine generators  

International Nuclear Information System (INIS)

We have examined the potential of 10 MW superconducting direct drive generators to enter the European offshore wind power market and estimated that the production of about 1200 superconducting turbines until 2030 would correspond to 10% of the EU offshore market. The expected properties of future offshore turbines of 8 and 10 MW have been determined from an up-scaling of an existing 5 MW turbine and the necessary properties of the superconducting drive train are discussed. We have found that the absence of the gear box is the main benefit and the reduced weight and size is secondary. However, the main challenge of the superconducting direct drive technology is to prove that the reliability is superior to the alternative drive trains based on gearboxes or permanent magnets. A strategy of successive testing of superconducting direct drive trains in real wind turbines of 10 kW, 100 kW, 1 MW and 10 MW is suggested to secure the accumulation of reliability experience. Finally, the quantities of high temperature superconducting tape needed for a 10 kW and an extreme high field 10 MW generator are found to be 7.5 km and 1500 km, respectively. A more realistic estimate is 200-300 km of tape per 10 MW generator and it is concluded that the present production capacity of coated conductors must be increased by a factor of 36 by 2020, resulting in a ten times lower price of the tape in order to reach a realistic price level for the superconducting drive train.onducting drive train.

54

Towers for Offshore Wind Turbines  

Science.gov (United States)

Increasing energy demand coupled with pollution free production of energy has found a viable solution in wind energy. Land based windmills have been utilized for power generation for more than two thousand years. In modern times wind generated power has become popular in many countries. Offshore wind turbines are being used in a number of countries to tap the energy from wind over the oceans and convert to electric energy. The advantages of offshore wind turbines as compared to land are that offshore winds flow at higher speed than onshore winds and the more available space. In some land based settings, for better efficiency, turbines are separated as much as 10 rotor diameters from each other. In offshore applications where only two wind directions are likely to predominate, the distances between the turbines arranged in a line can be shortened to as little as two or four rotor diameters. Today, more than a dozen offshore European wind facilities with turbine ratings of 450 kw to 3.6 MW exist offshore in very shallow waters of 5 to 12 m. Compared to onshore wind turbines, offshore wind turbines are bigger and the tower height in offshore are in the range of 60 to 80 m. The water depths in oceans where offshore turbines can be located are within 30 m. However as the distance from land increases, the costs of building and maintaining the turbines and transmitting the power back to shore also increase sharply. The objective of this paper is to review the parameters of design for the maximum efficiency of offshore wind turbines and to develop types offshore towers to support the wind turbines. The methodology of design of offshore towers to support the wind turbine would be given and the environmental loads for the design of the towers would be calculated for specific cases. The marine corrosion on the towers and the methods to control the corrosion also would be briefly presented. As the wind speeds tend to increase with distance from the shore, turbines build father offshore will be able to capture more wind energy. Currently two types of towers are considered. Cylindrical tubular structures and truss type structures. But truss type structures have less weight and flexibility in design. The construction of the offshore towers to harness the wind energy is also presented. The results will include the calculation of wind and wave forces on the tower and the design details for the tower.

Kurian, V. J.; Narayanan, S. P.; Ganapathy, C.

2010-06-01

55

Effects of Icing on Wind Turbine Fatigue Loads  

International Nuclear Information System (INIS)

The external conditions occurring at cold climate sites will affect wind turbines in different ways. The effects of ice accretion on wind turbines and the influence on the turbine fatigue loads are examined. The amount of icing prior to turbine installation needs to be estimated by using standard measurement data and considering the geometry of the proposed turbine. A procedure to calculate the expected ice accretion on wind turbines out of standard measurement data is explained and the results are discussed. Different parameters to describe the accreted ice on the turbine are examined separately in a fatigue load calculation. The results of the fatigue load calculation are discussed and selected cases are presented

56

Effects of Icing on Wind Turbine Fatigue Loads  

Energy Technology Data Exchange (ETDEWEB)

The external conditions occurring at cold climate sites will affect wind turbines in different ways. The effects of ice accretion on wind turbines and the influence on the turbine fatigue loads are examined. The amount of icing prior to turbine installation needs to be estimated by using standard measurement data and considering the geometry of the proposed turbine. A procedure to calculate the expected ice accretion on wind turbines out of standard measurement data is explained and the results are discussed. Different parameters to describe the accreted ice on the turbine are examined separately in a fatigue load calculation. The results of the fatigue load calculation are discussed and selected cases are presented.

Frohboese, Peter; Anders, Andreas [Germanischer Lloyd Industrial Services GmbH, Business Segment Wind Energy, Projects Department, Steinhoeft 9, 20459 Hamburg (Germany)

2007-07-15

57

Online wind turbine measurement laboratory  

DEFF Research Database (Denmark)

As part of the International Master of Science Program in Wind Energy at DTU, a complete interactive wind turbine measurement laboratory has been developed. A 500 kW stall regulated wind turbine has been instrumented with sensors for recording 1) turbine operational parameters, 2) meteorological conditions, 3) electrical quantities and 4) mechanical loads in terms of strain gauge signals. The data acquisition system has been designed and implemented by Risø together with students and teachers from DTU. It is based on LabVIEW© combined with a MySQL database for data management. The system enables online access for real-time recordings, which are used both for demonstration purposes, in individual [student] exercises and in scientific investigations. Long-term registration of wind turbine loads results in a unique database of noncommercial time series, which are available for practicing fatigue calculations and extreme loads estimation in basic wind turbine courses. Power quality analysis is carried out based on high speed sampled, three-phase voltage and current signals. The wide spectrum of sensors enables a detailed study of the correlation between meteorological, mechanical and electrical quantities. Measurements are acquired by a PC placed at the wind turbine site near Risø National Laboratory. The PC can be remotely controlled from DTU, which gives the students the opportunity to work on an operating wind turbine. Furthermore, measurements are published on WindData.com, which facilitates cooperation with other Universities.

Hansen, K.S.; Helgesen Pedersen, K.O.

2006-01-01

58

Wind Turbines Adaptation to the Variability of the Wind Field  

Science.gov (United States)

WIND TURBINES ADAPTATION TO THE VARIABILITY OF THE WIND FIELD The subject of our scientific research is wind power turbines (WPT) with the horizontal axis which were now common in the world. Efficient wind turbines work is largely determined by non-stationarity of the wind field, expressed in its gustiness, the presence of vertical and horizontal shifts of wind speed and direction. At critical values of the wind parameters WPT has aerodynamic and mechanical overload, leading to breakdowns, premature wear and reduce the life of the wind turbine. To prevent accidents at the peak values of wind speed it is used the regulatory system of windwheels. WPT control systems provide a process orientation of the wind turbine rotor axis in the line of the mean wind. Wind turbines are also equipped with braking device used to protect against breakdowns when a significant increase in the wind. In general, all these methods of regulation are not always effective. Thus, in practice there may be situations when the wind speed is many times greater than the stated limit. For example, if there are microbursts in the atmospheric boundary layer, low-level wind shears caused by its gust front, storms, etc. It is required for a wind power turbine adaptation to intensive short-term wind impulses and considerable vertical wind shifts that the data about them shall be obtained ahead of time. To do this it is necessary to have the information on the real structure of the wind field in the area of the blade sweep for the minimum range against the wind that is determined by the mean speed and the system action time. The implementation of acoustic and laser traditional wind sounding systems is limited by ambient acoustic noise, by heavy rain, snowfall and by fog. There are free of these disadvantages the inclined radioacoustic sounding (IRASS) technique which works for a system of remote detection and control of wind gusts. IRASS technique is realized as low-potential Doppler pulse radar including combined RF-acoustic antenna installed coaxially with the gondola of the wind power turbine. The work of the technique is synchronized with rotation of blades to eliminate their shielding action. Dangerous in terms of dynamic strength is the wind load pulse, the rise time which is comparable with the period of the natural frequency of the wind turbine elements (blade, tower, rotor, etc.). The amplitude decay of resonant vibrations at critical values of the speed of rotation can be realized through the use of mechanical elastic supports with nonlinear artificial dampers. They have a high coefficient of resistance, but may cause self-excited oscillations. We propose the way to deal with raised vibration of wind turbine elements at the expense of short-term increase of damping in the range of critical rotary axis speeds or during impulsive effects of wind loadings (wind gusts). This is possible through the use of non-linear electromagnetic dampers or active magnetic bearings. Their feature is the possibility of varying the mechanical stiffness and damping properties by changing the electrical parameters of electromagnets. The controlling of these parameters is carried out by the control system (CS) with the information feedback on the spatial-temporal structure of the wind field obtained from IRASS. In the composition of the CS can also be included the rotational speed sensor of the WPT rotor. This approach to the adaptation of wind turbines will allow to reduce vibration and to perform early compensation of the load on their components, which arise under the wind gusts. In addition, corrections about the wind field obtained with IRASS, would increase the mean power of WPT.

Ulianov, Yuriy; Martynenko, Gennadii; Misaylov, Vitaliy; Soliannikova, Iuliia

2010-05-01

59

Potential health impact of wind turbines  

Energy Technology Data Exchange (ETDEWEB)

In response to public health concerns about wind turbines, a study was conducted to review the scientific evidence on the potential health effects of wind turbines. Several research questions were examined, including scientific evidence on the potential health impacts of wind turbines; the relationship between wind turbine noise and health; the relationship between low frequency sound, infrasound and health; assessment of exposure to wind turbines; wind turbine health and safety hazards and Ontario wind turbine setbacks; community consultation prior to wind farm construction and data gaps and research needs. The study showed that although some people living near wind turbines reported symptoms such as dizziness, headaches, and sleep disturbance, the scientific evidence available to date does not demonstrate a direct causal link between wind turbine noise and adverse health effects. The sound level from wind turbines at common residential setbacks is not sufficient to cause hearing impairment or other direct health effects, although some people may find it annoying. 41 refs., 1 appendix.

NONE

2010-05-15

60

Potential health impact of wind turbines  

International Nuclear Information System (INIS)

In response to public health concerns about wind turbines, a study was conducted to review the scientific evidence on the potential health effects of wind turbines. Several research questions were examined, including scientific evidence on the potential health impacts of wind turbines; the relationship between wind turbine noise and health; the relationship between low frequency sound, infrasound and health; assessment of exposure to wind turbines; wind turbine health and safety hazards and Ontario wind turbine setbacks; community consultation prior to wind farm construction and data gaps and research needs. The study showed that although some people living near wind turbines reported symptoms such as dizziness, headaches, and sleep disturbance, the scientific evidence available to date does not demonstrate a direct causal link between wind turbine noise and adverse health effects. The sound level from wind turbines at common residential setbacks is not sufficient to cause hearing impairment or other direct health effects, although some people may find it annoying. 41 refs., 1 appendix.

61

Design Tool for Direct Drive Wind Turbine Generators : Proposed solutions for direct drive Darrieus generators 20MW  

DEFF Research Database (Denmark)

The current work offers a comparison of the proposed machine geometries for 6 [MW] direct drive wind generator candidates with the prospective of up scaling to 20MW. The suggestions are based on a design tool especially built for this investigation. The in-built flexibility of the design tool gives the possibility of calculating a large variation of geometries using existing modules. The main goal is to be able to quickly and transparently asses the feasibility of a proposed machine for a set of requirements. As a first step, a set of suitable machine types for the 6 [MW] design were investigated. A comparison of the selected machine types in view of up-scaling to 20 [MW] was performed. As an example fitness criterion, the use of active materials for the generators was considered. Based on this, suggestions for 20 [MW] generators were made. The results are discussed and future work, directions and suggestions for potential improvement were listed. The design is obtained analytically at first; then visualised in 3D CAD (Computer Assisted Design) and evaluated in FEM. An analytical optimisation (Particle Swarm –PSO and Genetic Algorithms -GA) patch is available for improving the design. The tool is destined for engineers that are involved in the design of wind turbine systems. The visualisation of the design in work is important for the overall assessment of the machine concept. The tool provides facilities for reporting on a shaped design: list of geometrical and electromagnetic quantities, pictures of the machine itself (3D particular drawing); FEM (Finite Element Model) electromagnetic profile, dynamic simulation model results and characteristic curves. The structure of the design tool is modular and independent so that new machine types and geometries can be designed by reusing recombining and altering the different calculation modules. The design algorithm is transparent as logging of location and comments is used throughout the program. The purpose of this is to enable further development of the design tool by several contributors. The tool was validated by both software and laboratory tests on a prototype and by comparing results with literature reporting of similar machines.

Leban, Krisztina Monika

2014-01-01

62

Reliability Assessment Of Wind Turbines  

DEFF Research Database (Denmark)

Reduction of cost of energy for wind turbines are very important in order to make wind energy competitive compared to other energy sources. Therefore the turbine components should be designed to have sufficient reliability but also not be too costly (and safe). This paper presents models for uncertainty modeling and reliability assessment of especially the structural components such as tower, blades, substructure and foundation. But since the function of a wind turbine is highly dependent on many electrical and mechanical components as well as a control system also reliability aspects of these components are discussed and it is described how there reliability influences the reliability of the structural components. Two illustrative examples are presented considering uncertainty modeling, reliability assessment and calibration of partial safety factors for structural wind turbine components exposed to extreme loads and fatigue, respectively.

SØrensen, John Dalsgaard

2014-01-01

63

Probabilistic Design of Wind Turbines  

DEFF Research Database (Denmark)

Probabilistic design of wind turbines requires definition of the structural elements to be included in the probabilistic basis: e.g., blades, tower, foundation; identification of important failure modes; careful stochastic modeling of the uncertain parameters; recommendations for target reliability levels and recommendation for consideration of system aspects. The uncertainties are characterized as aleatoric (physical uncertainty) or epistemic (statistical, measurement and model uncertainties). Methods for uncertainty modeling consistent with methods for estimating the reliability are described. It is described how uncertainties in wind turbine design related to computational models, statistical data from test specimens, results from a few full-scale tests and from prototype wind turbines can be accounted for using the Maximum Likelihood Method and a Bayesian approach. Assessment of the optimal reliability level by cost-benefit optimization is illustrated by an offshore wind turbine example. Uncertainty modeling is illustrated by an example where physical, statistical and model uncertainties are estimated.

SØrensen, John Dalsgaard; Toft, H.S.

2010-01-01

64

Wind turbine storage systems  

International Nuclear Information System (INIS)

Electric power is often produced in locations far from the point of utilization which creates a challenge in stabilizing power grids, particularly since electricity cannot be stored. The production of decentralized electricity by renewable energy sources offers a greater security of supply while protecting the environment. Wind power holds the greatest promise in terms of environmental protection, competitiveness and possible applications. It is known that wind energy production is not always in phase with power needs because of the uncertainty of wind. For that reason, energy storage is the key for the widespread integration of wind energy into the power grids. This paper proposed various energy storage methods that can be used in combination with decentralized wind energy production where an imbalance exists between electricity production and consumption. Energy storage can play an essential role in bringing value to wind energy, particularly if electricity is to be delivered during peak hours. Various types of energy storage are already in use or are being developed. This paper identified the main characteristics of various electricity storage techniques and their applications. They include stationary or embarked storage for long or short term applications. A comparison of characteristics made it possible to determine which types of electricity storage are best suited for wind energy. These include gravity energy; thermal energy; compressed air energy; coupled stornergy; compressed air energy; coupled storage with natural gas; coupled storage with liquefied gas; hydrogen storage for fuel cells; chemical energy storage; storage in REDOX batteries; storage by superconductive inductance; storage in supercondensers; and, storage as kinetic energy. 21 refs., 21 figs

65

75 FR 29365 - Job Corps: Final Finding of No Significant Impact (FONSI) for Small Wind Turbine Installation at...  

Science.gov (United States)

...Significant Impact (FONSI) for Small Wind Turbine Installation at the Pine Ridge...Significant Impact (FONSI) for Small Wind Turbine Installation at the Pine Ridge...proposed construction of a small wind turbine at the Pine Ridge Job Corps...

2010-05-25

66

Lightning protection of wind turbines  

Energy Technology Data Exchange (ETDEWEB)

Lightning damage to wind turbines is a serious problem for Danish power companies, who have experienced some cases with very costly lightning damage and a large number of cases with minor damage. The most costly cases include one catastrophic damage to an entire wind turbine, and several cases of destruction of blades, main bearings, generators and control systems. Over the years there have been several hundreds of cases with minor damage - typically damage and interruptions of the control and communication systems, or the power systems. The Danish power companies anticipate that the lightning threat will be even bigger for the large off-shore wind turbine installations that are currently being planned in Denmark. Furthermore, it is known from the off-shore wind turbines at Vindeby in Denmark that the costs of inspection and particularly repair work must be expected to be much higher off-shore as compared to wind turbines on land. These considerations was the background for a two year project concerned with investigation of lighting damages and with the formulation of a DEFU Recommendation for lightning protection of wind turbines, which was published in January 1999. The project was funded by the Danish power companies Elsam, Eltra, Elkraft and by DEFU. (au)

Soerensen, T.; Brask, M.H. [DEFU (Denmark); Jensen, F.V.; Raben, N. [SEAS (Denmark); Saxov, J. [Nordjyllandsvaerket (Denmark); Nielsen, L. [Vestkraft (Denmark); Soerensen, P.E. [Risoe National Lab. (Denmark)

1999-03-01

67

Active robust control of wind turbines  

Science.gov (United States)

The research work conducted in this thesis focuses on robustness of wind energy conversion system with respect to faults in pitch actuator in order to prevent unnecessary emergency shutdown, and keep the turbine operational without significant inefficiency in its overall performance. The objective is to investigate the feasibility of using a fault estimator and a light detection and ranging (LIDAR) system as additional sensors to design a suitable control system for wind turbines. Robust control technique is used to address these issues. Three controllers are proposed in this work that try to address sources of inaccuracy in wind turbine operation: An active fault tolerant controller is first designed using a fault estimator. It is shown that a set of locally robust controllers with respect to the fault, together with a suitable smooth mixing approach, manages to overcome the problem of faults in the pitch actuator. To address the wind-dependent behavior of turbines, a second controller is designed using the LIDAR sensor. In this configuration, LIDAR provides the look ahead wind information and generates a smooth scheduling signal to provide active robustness with respect to the changes in wind speed. Lastly, utilizing both the fault estimator and LIDAR, a 2-dimensional wind-dependent active fault tolerant controller is developed to control the wind turbine in region 3 of operation. The feasibility of the proposed ideas is verified in simulation. For this purpose, the US National Renewable Energy Laboratory's FAST code is used to model the 3-balded controls advanced research turbine. A discussion on practical considerations and ideas for future work are also presented.

Rezaei, Vahid

68

Diffuser augmentation of wind turbines  

Energy Technology Data Exchange (ETDEWEB)

Wind tunnel investigation of models of two diffuser design concepts is directed toward unconventional, very short, cost-effective configurations. One approach uses the energetic external wind to prevent separation of the diffuser's internal boundary layer. Another method used high lift airfoil contours for the diffuser wall shape. Diffuser model tests have indicated almost a doubling of wind power extraction capability for DAWTs compared to conventional turbines. Economic studies of DAWTs have used these test data and recent (1975) cost projections of wind turbines with diameter. The specific power costs ($/kW) for a realistic DAWT configuration are found to be lower than conventional wind turbines for very large size rotors, above 50 meters diameter, and for rotor diameters less than about 20 meters. The cost-to-benefit assessment for intermediate size rotors is affected by the uncertainty band of cost for these rotor sizes.

Foreman, K. M.; Gilbert, B.; Oman, R. A.

1976-01-01

69

Asynchronous Generators for use in Gearless Wind Turbines  

DEFF Research Database (Denmark)

In this presentation the squirrel cage induction generator is proposed for a direct-drive wind turbine. The squirrel cage induction generator is proposed for direct drive wind turbines, because of its simple and rugged construction and because it does not require rare earth elements, which are a key element in permanent magnets and might become difficult to source affordably in the future.

Jensen, Bogi Bech Technical University of Denmark,

2011-01-01

70

LES of wind turbine wakes: Evaluation of turbine parameterizations  

Science.gov (United States)

Large-eddy simulation (LES), coupled with a wind-turbine model, is used to investigate the characteristics of wind turbine wakes in turbulent boundary layers under different thermal stratification conditions. The subgrid-scale (SGS) stress and SGS heat flux are parameterized using scale-dependent Lagrangian dynamic models (Stoll and Porte-Agel, 2006). The turbine-induced lift and drag forces are parameterized using two models: an actuator disk model (ADM) that distributes the force loading on the rotor disk; and an actuator line model (ALM) that distributes the forces on lines that follow the position of the blades. Simulation results are compared to wind-tunnel measurements collected with hot-wire and cold-wire anemometry in the wake of a miniature 3-blade wind turbine at the St. Anthony Falls Laboratory atmospheric boundary layer wind tunnel. In general, the characteristics of the wakes simulated with the proposed LES framework are in good agreement with the measurements. The ALM is better able to capture vortical structures induced by the blades in the near-wake region. Our results also show that the scale-dependent Lagrangian dynamic SGS models are able to account, without tuning, for the effects of local shear and flow anisotropy on the distribution of the SGS model coefficients.

Porte-Agel, Fernando; Wu, Yu-Ting; Chamorro, Leonardo

2009-11-01

71

Nonlinear Dynamics of Wind Turbine Wings  

OpenAIRE

Wind turbines with a nominal effect of 5MW with a rotor diameter of up to 126m are produced today. With the increasing size wind turbines also become more and more optimized with respect to structural dimensions and material usage, without increasing the stiffness proportionally. Consequently, large wind turbines become increasingly flexible and dynamically sensitive. This project focuses on the structural analysis of highly flexible wind turbine wings, and the aerodynamic loading of wind tur...

Larsen, Jesper Winther

2006-01-01

72

Results of a wind turbine FDI competition  

DEFF Research Database (Denmark)

In this paper some newly published methods for fault detection and isolation developed for a wind turbine benchmark model are tested, compared and evaluated. These methods have been presented as a part of an international competition. The tested methods cover different types of fault detection and isolation methods, which include support vector machines, observer based methods, and auto generated methods. All of these methods show interesting potentials for usage in the wind turbine application, but all with different strong and weak sides in relation to the requirements specified in the proposed benchmark model.

Odgaard, Peter Fogh; Stoustrup, Jakob

2012-01-01

73

Fault Behavior of Wind Turbines  

OpenAIRE

Synchronous generators have always been the dominant generation type in the grid. This fact affected both planning and operation of power systems. With the fast increase of wind power share in the grid in the last decade, the situation is changing. In some countries wind power represents already a consistent amount of the total generation. Wind turbines can be classified as non-synchronous generation and they behave differently than synchronous generation under many circumstances. Fault behav...

Sulla, Francesco

2012-01-01

74

Active control: Wind turbine model  

DEFF Research Database (Denmark)

This report is a part of the reporting of the work done in the project 'Active Control of Wind Turbines'. This project aim is to develop a simulation model for design of control systems for turbines with pitch control and to use that model to designcontrollers. This report describes the model developed for controller design and analysis. Emphasis has been put on establishment of simple models describing the dynamic behavior of the wind turbine in adequate details for controller design. This hasbeen done with extensive use of measurements as the basis for selection of model complexity and model validation as well as parameter estimation. The model includes a simple model of the structure of the turbine including tower and flapwise blade bending,a detailed model of the gear box and induction generator, a linearized aerodynamic model including modelling of induction lag and actuator and sensor models. The models are all formulated as linear differential equations. The models are validated throughcomparisons with measurements performed on a Vestas WD 34 400 kW wind turbine. It is shown from a control point of view simple linear models can be used to describe the dynamic behavior of a pitch controlled wind turbine. The model and the measurementscorresponds well in the relevant frequency range. The developed model is therefore applicable for controller design.

Bindner, H.

1999-01-01

75

Extended Kalman Filter based State Estimation of Wind Turbine  

Directory of Open Access Journals (Sweden)

Full Text Available State estimation provides the best possible approximation for the state of the system by processing the available information. In the proposed work, the state estimation technique is used for the state estimation of wind turbine. Modern wind turbines operate in a wide range of wind speeds. To enable wind turbine operation in such a variety of operating conditions, sophisticated control and estimationalgorithms are needed. The theoretical basis of Extended Kalman Filter algorithm is explained in detail and performance is tested with the simulation. A nonlinear state estimator named ExtendedKalman Filter can be used for estimating the states of wind turbine. The Extended Kalman Filter is a recursive estimator that can be decomposed into two phases such as prediction and correction performed at every time instant. The states estimated by usingExtended Kalman Filter for wind turbine application includes rotor speed of turbine, tower top displacement and its velocity.

Kavitha N

2013-11-01

76

DOE/SNL-TTU scaled wind farm technology facility : research opportunities for study of turbine-turbine interaction.  

Energy Technology Data Exchange (ETDEWEB)

The proposed DOE/Sandia Scaled Wind Farm Technology Facility (SWiFT) hosted by Texas Tech University at Reese Technology Center in Lubbock, TX, will provide a facility for experimental study of turbine-turbine interaction and complex wind farm aerodynamics. This document surveys the current status of wind turbine wake and turbine-turbine interaction research, identifying knowledge and data gaps that the proposed test site can potentially fill. A number of turbine layouts is proposed, allowing for up to ten turbines at the site.

Barone, Matthew Franklin; White, Jonathan

2011-09-01

77

Wind energy. From small wind turbines to offshore wind farms  

International Nuclear Information System (INIS)

This bibliographical sheet presents a book in which the authors present and discuss the present and future developments, challenges and problematic of wind energy. They notably focus on offshore wind farms, their technical solutions and current French projects, with their potentials, economic, administrative and environmental aspects, their sizing issue, and so on. They also explain in detail the potential of wind energy and its conversion, present the different subsystems of a wind turbine and their operation, and describe how to build up a wind farm project. They also address the issues related to small wind turbines

78

Vertical axis wind turbine airfoil  

Science.gov (United States)

A vertical axis wind turbine airfoil is described. The wind turbine airfoil can include a leading edge, a trailing edge, an upper curved surface, a lower curved surface, and a centerline running between the upper surface and the lower surface and from the leading edge to the trailing edge. The airfoil can be configured so that the distance between the centerline and the upper surface is the same as the distance between the centerline and the lower surface at all points along the length of the airfoil. A plurality of such airfoils can be included in a vertical axis wind turbine. These airfoils can be vertically disposed and can rotate about a vertical axis.

Krivcov, Vladimir; Krivospitski, Vladimir; Maksimov, Vasili; Halstead, Richard; Grahov, Jurij Vasiljevich

2012-12-18

79

Wind Turbine in Yawed Operation  

OpenAIRE

The task of this project was to investigate the near wake, performance characteristics and yaw moment on a model wind turbine. The test turbine is a horizontal axis three bladed machine with a rotor diameter of 0.9 meter. Initially it is an upwind turbine, but was used for downwind measurements as well by rotating the blades and the entire construction 180^0. For the wake measurements the tip speed ratio was set to be TSR=3, TSR=6 and TSR=9 to describe the different regimes; partly stalled, o...

Loland, Kari Medby

2011-01-01

80

Wind Turbine Control: Robust Model Based Approach  

DEFF Research Database (Denmark)

In the 1970s the oil price crisis encouraged investigation of non-petroleum energy sources of which wind energy was the most promising one. Lately global warming concerns have even intensified the demand for green and sustainable energy resources and opened up several lines of research in this area. Wind turbines are the most common wind energy conversion systems and are hoped to be able to compete economically with fossil fuel power plants in near future. However this demands better technology to reduce the price of electricity production. Control can play an essential part in this context. This is because, on the one hand, control methods can decrease the cost of energy by keeping the turbine close to its maximum efficiency. On the other hand, they can reduce structural fatigue and therefore increase the lifetime of the wind turbine. The power produced by a wind turbine is proportional to the square of its rotor radius, therefore it seems reasonable to increase the size of the wind turbine in order to capture more power. However as the size increases, the mass of the blades increases by cube of the rotor size. This means in order to keep structural feasibility and mass of the whole structure reasonable, the ratio of mass to size should be reduced. This trend results in more flexible structures. Control of the flexible structure of a wind turbine in a wind field with stochastic nature is very challenging. In this thesis we are examining a number of robust model based methods for wind turbine control. Firstly we examine potentials of -synthesis methods and use -tools to analyze robustness of the resulting controllers both in terms of robust stability and robust performance. Afterwards we employ model predictive control (MPC) and show that the way MPC solves control problems suits wind turbine control problems very well, especially when we have preview measurements of wind speed using LIDARs. For the control problem with LIDAR measurements we have proposed a new MPC approach which gives better results than linear MPC while it has almost the same computational complexity. We have also tackled wind turbine control using robust MPC. In general, robust MPC problems are very computationally demanding, however we have shown that with some approximations the resulting robust MPC problem can be specialized with reduced computational complexity. After a short introduction on wind energy and wind turbines in chapter 1, we briefly explain wind turbine modeling in chapter 2. Introductions to different control design methods are given in chapter 3. The goal of this chapter is to show how different control methods are chosen. The next eight chapters comprise the body of the thesis and are scientific papers that are published or going to be published. Control methods which were briefly introduced in chapter 3 are explained in these chapters in details.

Mirzaei, Mahmood

2012-01-01

81

Predicting Faults in Wind Turbines Using SCADA Data  

DEFF Research Database (Denmark)

The cost of operation and maintenance of wind turbines is a significant part of the overall cost of wind turbines. To reduce this cost a method for enabling early fault detection is proposed and tested in this paper. The method is taking advantage of the fact that wind turbines in wind farms are located near similar wind turbines. This is done by generating a model for each turbine, the model is then used to evaluate the performance of that turbine and the nearby turbines. The evaluations from the models are then combined and used as votes to identify the faulty turbines. The method is applied and tested on historical Supervisory Control And Data Acquisition (SCADA) data from nine operational turbines over a testing period of nine months. The performance of the fault detection is found to be acceptable based on the testing period. During the testing period several gear related services were performed, some of these were predicted by the proposed fault detection systems. The advantage of the purposed method isthat it applicable for operational turbines without requiring any extra measurements, since the used SCADA data is available from most modern wind turbines.

Borchersen, Anders Bech; Larsen, Jesper Abildgaard

2013-01-01

82

Power Control Design for Variable-Speed Wind Turbines  

OpenAIRE

This paper considers power generation control in variable-speed variable-pitch horizontal-axis wind turbines operating at high wind speeds. A dynamic chattering torque control and a proportional integral (PI) pitch control strategy are proposed and validated using the National Renewable Energy Laboratory wind turbine simulator FAST (Fatigue, Aerodynamics, Structures, and Turbulence) code. Validation results show that the proposed controllers are effective for power regulation and demonstrate ...

Francesc Pozo; Mauricio Zapateiro; Ningsu Luo; Leonardo Acho; Yolanda Vidal

2010-01-01

83

Analysis of the Environmental Impact on Remanufacturing Wind Turbines  

Science.gov (United States)

To deliver clean energy the use of wind turbines is essential. In June 2011 there was an installed wind capacity equivalent to 211,000MW world-wide (WWEA, 2011). By the end of the year 2009 the U.S. had 35,100MW of wind energy installed capacity to generate electricity (AWEA, 2010). This industry has grown in recent years and is expected to grow even more in the future. The environmental impacts that will arise from the increased number of wind turbines and their end-of-life should be addressed, as large amounts of resources will be required to satisfy the current and future market demands for wind turbines. Since future 10MW wind turbines are expected to be as heavy as 1000 tons each, the study of the environmental response of profitable retirement strategies, such as remanufacturing for these machines, must be considered. Because of the increased number of wind turbines and the materials used, this study provides a comparison between the environmental impacts from remanufacturing the components installed inside the nacelle of multi-megawatt wind turbines and wind turbines manufactured using new components. The study methodology is the following: • Describe the life-cycle and the materials and processes employed for the manufacture and remanufacturing for components inside the nacelle. • Identify remanufacturing alternatives for the components inside the nacelle at the end of the expected life-time service of wind turbines. • Evaluate the environmental impacts from the remanufactured components and compare the results with the impacts of the manufacturing of new components using SimaPro. • Conduct sensitivity analysis over the critical parameters of the life cycle assessment • Propose the most environmentally friendly options for the retirement of each major component of wind turbines. After an analysis of the scenarios the goal of the study is to evaluate remanufacturing as an end-of-life option from an environmental perspective for commercial multi-megawatt wind turbines targeted for secondary wind turbine markets.

Sosa Skrainka, Manuel R.

84

New guidelines for wind turbine gearboxes  

Energy Technology Data Exchange (ETDEWEB)

The American Gear Manufacturers Association in cooperation with the American Wind Energy Association will soon be publishing AGMA/AWEA 921-A97 {open_quotes}Recommended Practices for Design and Specification of Gearboxes for Wind Turbine Generator Systems.{close_quotes} Much has been learned about the unique operation and loading of gearboxes in wind turbine applications since the burgeoning of the modern wind turbine industry in the early 1980`s. AGMA/AWEA 921-A97 documents this experience in a manner that provides valuable information to assist gear manufacturers and wind turbine designers, operators, and manufacturers in developing reliable wind turbine gearboxes. The document provides information on procurement specification development, wind turbine architecture, environmental considerations, and gearbox load determination, as well as the design, manufacturing, quality assurance, lubrication, operation and maintenance of wind turbine gearboxes. This paper presents the salient parts of the practices recommended in AGMA/AWEA 921-A97.

McNiff, B. [McNiff Light Industry, Blue Hill, ME (United States); Errichello, R. [GEARTECH, Townsend, MT (United States)

1997-12-31

85

Wind turbine noise. Primary noise sources  

Energy Technology Data Exchange (ETDEWEB)

Wind is a clean, cheap, and inexhaustible source of energy. However, the noise from wind turbines constitutes an important hindrance for the widespread application of wind energy. As a result, there is considerable interest in wind turbine noise, from a number of angles. As public clamour grows from those living near turbines, and misinformation and disinformation begin to take root, there is a clear need for a scientifically accurate book to give an account of the noise generated, its effects on people, and possible remedies either through technology or legislation or both. The different potential source mechanisms are described and the theoretical characteristics of flowinduced sound from wind turbine blades are explained. The noise sources on wind turbines are characterized experimentally by means of wind tunnel and field experiments. Methods to predict and reduce wind turbine noise are discussed. The dominant noise source for typical modern large wind turbines is broadband trailing edge noise from the outer part of the blades. The swishing character of the sound can be explained by trailing edge noise directivity and convective amplification. A semi-analytical, semi-empirical prediction method can accurately predict the characteristics of wind turbine noise. Wind turbine noise can be halved by means of serrations, without adverse effects on the aerodynamic performance. The book is aimed at people with a personal or professional involvement in wind turbine noise, such as environmental health or public health practitioners, wind farm developers or informed wind farm supporters and objectors.

Oerlemans, S.

2011-04-15

86

Transportation Excellence for Wind Turbine Nacelle  

OpenAIRE

With the growing demand of renewable wind energy, logistics and operations associated with a wind turbine makes for compelling study and analysis. The study entails understanding of transporting a wind turbine nacelle from Denmark till Australia. The methods of transporting the wind turbine nacelle and the modes of transportation that are currently in use have been studied. Factors that are detrimental to efficient shipping have been reviewed with existing literature and analysed for a wind t...

Babu Thennarasu, Ganesh; Kumar Annamalai Muralidharan, Hemanth

2012-01-01

87

Small-Scale Vertical Axis Wind Turbine Design  

OpenAIRE

The thesis focuses on the design of a small vertical axis wind turbine rotor with solid wood as a construction material. The aerodynamic analysis is performed implementing a momentum based model on a mathematical computer program. A three bladed wind turbine is proposed as candidate for further prototype testing after evaluating the effect of several parameters in turbine efficiency, torque and acceleration. The results obtained indicate that wood is a suitable material for rotor cons...

Castillo Tudela, Javier

2011-01-01

88

Mechanical noise from wind turbines  

International Nuclear Information System (INIS)

Community annoyance due to noise from wind turbines is often the result of noise character rather than level. Although the overall contributions from each of the two main classes of noise source, namely aerodynamic and mechanical, are often of a similar order for an untreated turbine, it is usually the mechanical sources which provide the dominant noise characteristics that may lead to annoyance. In this paper, the sources of mechanical noise are identified primarily with reference to horizontal axis wind turbines and then attention is concentrated on the rotor-shaft step-up gearbox, which is normally the top-ranking source. The major gearbox noise mechanisms and transmission paths are discussed and reference made to Noise Specifications and procedures applicable to the gearbox prior to its installation. The reduction of machinery noise is reviewed both at source and by treatment of transmission paths. (author)

89

Health monitoring for wind turbines  

Energy Technology Data Exchange (ETDEWEB)

Condition monitoring is an important component in the predictive maintenance of wind turbines and can allow for the maintenance of equipment before a failure occurs. This poster presentation described the method used by the consulting firm Garrad Hassan to predict potential component failure and to target wind turbines that need predictive maintenance or further inspection. Component temperatures were recorded by the SCADA systems of 400 wind turbines of 5 different types and then analyzed in relation to their generator bearings; slip ring; winding; cooling air; gearbox bearing and oil temperature; main shaft bearings temperature; and hydraulic oil temperatures. Component temperatures were then normalized by calculating the per-turbine linear or log-linear fit to the previous power production record and the nacelle or ambient temperature. The fitted expected temperature was then subtracted from the observed component temperature so that signals with high variability were reduced to flat signals. The normalized signals were then median filtered by day, and the resulting trends were analyzed in order to determine signals that deviated more than 5 degrees C above normal. The correspondence between the deviations and known component failure or downtime was then evaluated. Results of the study showed that some signals can be reasonable or excellent early indicators of component failure. tabs., figs.

Duncan, T. [Garrad Hassan Canada Inc., Ottawa, ON (Canada)

2010-07-01

90

Wind Turbine Siting: Wildlife Concerns  

Science.gov (United States)

The Advanced Technology Environmental and Energy Center (ATEEC) provides this document on wildlife concerns in relation to the siting of wind turbines. The material includes individual student activities and a list of web resources intended to help teachers. Users must download this resource for viewing, which requires a free log-in. There is no cost to download the item.

Everhart, Roger

91

Risk of collision between service vessels and offshore wind turbines  

International Nuclear Information System (INIS)

Offshore wind farms are growing in size and are situated farther and farther away from shore. The demand for service visits to transfer personnel and equipment to the wind turbines is increasing, and safe operation of the vessels is essential. Currently, collisions between service vessels and offshore wind turbines are paid little attention to in the offshore wind energy industry. This paper proposes a risk assessment framework for such collisions and investigates the magnitude of the collision risk and important risk-influencing factors. The paper concludes that collisions between turbines and service vessels even at low speed may cause structural damage to the turbines. There is a need for improved consideration of this kind of collision risk when designing offshore wind turbines and wind farms.

92

Inertial response from wind turbines  

Science.gov (United States)

Wind power is an essential part of the strategy to address challenges facing the energy sector. Operation of the electricity network in 2020 will require higher levels of response and reserve from generation. The provision of inertial response from wind turbines was investigated. A model was developed for the simulation of frequency on the mainland UK system, including a simplified model for a synchronous generator to represent Full Power Converter turbines. Two different methods of inertia response, the step method and the inertia coupling method, were modelled and introduced into the turbine torque speed control. Simulations illustrated the effects on primary frequency control for a high penetration of wind turbines. Results are shown for different demand levels with generation losses of 1320GW and 1800GW. A comparison of the inertia functions is included and the effect of wind speed and the constant speed region of the maximum power extraction curve. For the scenarios modelled only a small change in turbine output was required for inertia response (0.02p.u). Without inertia response a large increase in synchronous plant response was needed. A test rig was constructed consisting of a Full Power Converter bridge and a synchronous generator driven by a dc machine. Power converters were designed and constructed by the candidate. Vector control of both the generator converter and grid converter was implemented on a dedicated control platform. The inertia coupling function was implemented and a test frequency deviation injected to represent a load generation imbalance. Results compared closely to those from the model and demonstrated the capability to closely couple turbine speed to system frequency with adjustment of the response via a filter if desired. The experimental work confirmed the adequacy of the simplified generator model and further confirmed the possibility of using inertia response. The inertia coupling function was considered suitable for use for the UK system.

Moore, Ian F.

93

Design of Wind Turbine Vibration Monitoring System  

Directory of Open Access Journals (Sweden)

Full Text Available In order to ensure safety of wind turbine operation and to reduce the occurrence of faults as well as to improve the reliability of wind turbine operation, a vibration monitoring for wind turbine is developed. In this paper, it analyses the enlargement of all the parts of the structure and the working mechanism, the research method of wind turbine operation vibration is introduced, with the focus being the use of the sensor principle. Finally the hardware design and software of this system is introduced and the main function of this system is described, which realizes condition monitoring of the work state of wind turbines.

Shoubin Wang

2013-04-01

94

Modelling and control of large wind turbine  

OpenAIRE

In order to make the wind energy an economical alternative for energy production, upscaling of turbine to 10 - 15MW may be necessary to reduce the overall cost of energy production. This production target requires a considerable increase in the turbine size and placing the turbines at high wind speed locations. But increase in turbine size also increases the uneven load distribution across the turbine structure. Therefore an efficient load reduction technique is necessary to increase the turb...

Zafar, Syed Hammad

2013-01-01

95

Fault tolerant wind speed estimator used in wind turbine controllers  

DEFF Research Database (Denmark)

Advanced control schemes can be used to optimize energy production and cost of energy in modern wind turbines. These control schemes most often rely on wind speed estimations. These designs of wind speed estimators are, however, not designed to be fault tolerant towards faults in the used sensors. In this paper a fault tolerant wind speed estimator is designed based on a set of unknown input observers, each designed to the different sets of non-faulty sensors. Faults in the rotor, generator and wind speed sensors are considered. The designed wind speed estimator is passive tolerant towards faults in the wind speed sensors, and faults in the generator and rotor speed sensors are accommodated by an active fault tolerant observer scheme in which the faults are detected and identified, and the observer corresponding to the non-faulty sensors are used. The potential of the scheme is shown by applying the proposed wind speed estimator to a simulation model of a wind turbine. Notice that since the faults are accommodated in the observer scheme the actual controller do not need to be adjusted or reconfigured to accommodate the sensor faults.

Odgaard, Peter Fogh; Stoustrup, Jakob

2012-01-01

96

Large, horizontal-axis wind turbines  

Science.gov (United States)

Development of the technology for safe, reliable, environmentally acceptable large wind turbines that have the potential to generate a significant amount of electricity at costs competitive with conventional electric generating systems are presented. In addition, these large wind turbines must be fully compatible with electric utility operations and interface requirements. There are several ongoing large wind system development projects and applied research efforts directed toward meeting the technology requirements for utility applications. Detailed information on these projects is provided. The Mod-O research facility and current applied research effort in aerodynamics, structural dynamics and aeroelasticity, composite and hybrid composite materials, and multiple system interaction are described. A chronology of component research and technology development for large, horizontal axis wind turbines is presented. Wind characteristics, wind turbine economics, and the impact of wind turbines on the environment are reported. The need for continued wind turbine research and technology development is explored. Over 40 references are sited and a bibliography is included.

Linscott, B. S.; Perkins, P.; Dennett, J. T.

1984-01-01

97

RBI Optimization of Offshore Wind Turbines  

DEFF Research Database (Denmark)

Wind turbines for electricity production have increased significantly the last years both in production capability and size. This development is expected to continue also in the coming years. Offshore wind turbines with an electricity production of 5-10 MW are planned. Typically, the wind turbine support structure is a steel structure consisting of a tower and a monopile, tripod or jacket type foundation. This paper considers aspects of inspection and maintenance planning of fatigue prone details in jacket and tripod type of wind turbine support structures. Based on risk-based inspection planning methods for oil & gas installations, a framework for optimal inspection and maintenance planning of offshore wind turbines is presented. Special aspects for offshore wind turbines considered are the fatigue loading characteristics where usually the wind loading are dominating the wave loading, wake effects in wind farms and also the reliability level which is typically significantly lower than for oil & gas installations. An illustrative example is presented.

Ramírez, José G. Rangel; SØrensen, John Dalsgaard

2009-01-01

98

Fluid-Structure Interaction Analysis of Wind Turbines  

Science.gov (United States)

Countries around the world are putting substantial effort into the development of wind energy technologies. The urgent need of renewable energy puts pressure on the wind energy industry research and development to enhance the current wind generation capabilities and decrease the associated costs. Currently most wind turbine aerodynamics and aeroelasticity simulations are performed using low-fidelity methods. These methods are simple to implement and fast to execute; however, the cases involving important features, such as unsteady flow, turbulence, and details of the wind turbine geometry, are beyond their range of applicability. In this dissertation, we introduce a paradigm shift in wind turbine analysis by developing 3D, complex geometry, time-dependent, multi-physics modeling procedures for wind turbine fluid-structure interaction (FSI). The proposed framework consists of a collection of numerical methods combined into a single framework for FSI modeling and simulation of wind turbines at full scale. The use of the Navier-Stokes equations of incompressible flows for wind turbine aerodynamics is validated against experimental data. The structural modeling of the composite blades is based on the Kirchhoff-Love thin shell theory discretized using isogeometric analysis. The coupled FSI formulation is derived using the augmented Lagrangian approach and accommodates non-matching fluid-structure interface discretizations. The challenges of fluid-structural coupling and the handling of computational domains in relative motion are discussed, and the FSI computations of a 5 MW offshore baseline wind turbine are shown.

Hsu, Ming-Chen

99

Dynamic Models for Wind Turbines and Wind Power Plants  

Energy Technology Data Exchange (ETDEWEB)

The primary objective of this report was to develop universal manufacturer-independent wind turbine and wind power plant models that can be shared, used, and improved without any restrictions by project developers, manufacturers, and engineers. Manufacturer-specific models of wind turbines are favored for use in wind power interconnection studies. While they are detailed and accurate, their usages are limited to the terms of the non-disclosure agreement, thus stifling model sharing. The primary objective of the work proposed is to develop universal manufacturer-independent wind power plant models that can be shared, used, and improved without any restrictions by project developers, manufacturers, and engineers. Each of these models includes representations of general turbine aerodynamics, the mechanical drive-train, and the electrical characteristics of the generator and converter, as well as the control systems typically used. To determine how realistic model performance is, the performance of one of the models (doubly-fed induction generator model) has been validated using real-world wind power plant data. This work also documents selected applications of these models.

Singh, M.; Santoso, S.

2011-10-01

100

Aeroelasticity of Large Wind Turbines  

Energy Technology Data Exchange (ETDEWEB)

The aeroelastic stability of wind turbines can be investigated by simulating models of the turbines under different conditions. Wind condition, pitch angle setting and rotational velocity will influence the aeroelastic stability. This dissertation describes the development and use of one fully nonlinear aeroelastic tool that has been developed especially for large wind turbines, but it can also be used for many other systems with bending and torsional degrees of freedom. This tool is called WOBBE. The calculations are performed using nonlinear dynamics and nonlinear aerodynamics. This is important, because linearising is always a somewhat arbitrary process where experience is used to determine which terms can and cannot be left out of the equations. The importance of performing fully nonlinear calculations will be shown by discussing the differences between the results from linear programmes and WOBBE. The combination of using linearised tools to investigate the possible problem areas and nonlinear tools to zoom in on these possible unstable conditions seems to be a logical approach of the aeroelastic analysis during the design. WOBBE simulates multi-body systems, where the rigid bodies are interconnected with hinges, springs and dampers. The aerodynamic forces acting on this system are calculated by the programme. The blade element momentum method is used for these calculations. The calculations of the motions are performed using Hamilton's generalised momenta and the generalised coordinates as state variables. WOBBE has been developed purely to perform simulations to determine the aeroelastic (in)stability of the system, not to determine the stresses in the components of the turbine. If there are any unknown or unexpected instabilities for the given setting, these will also show up in the simulation, as the method does not focus solely on expected instabilities. Next to the fact that WOBBE performs the simulations fully nonlinear, this is another advantage of the programme. The way to model a wind turbine is very important. If the model is incorrect, the results will never be of any use (garbage in, garbage out). Using so-called superelements, the correct frequencies will show up in the results using only a few elements. This can easily be tested by simulating a beam for which the theoretical eigenfrequencies are known. Using WOBBE, this test has been performed and as a result, superelements have been chosen for the models used in this programme. WOBBE is a useful tool to perform the final check in the design process. Due to the fact that the equations of motion do not need to be derived, it is also a useful tool to investigate the detail necessary to perform reliable simulations. The user can easily change the complexity of the model and perform new simulations without much preparation time. The minimum number of superelements that needs to be used in a model in order to produce reliable results has been investigated, resulting in some guidelines concerning the model. The method used to calculate the stiffnesses of the springs has also been investigated. The structural pitch can also be modelled in several ways. Different methods have been looked at in an attempt to find out which method would be the best method. The programme has been validated. Measurements were performed on an NM-80 wind turbine and the results from these measurements were compared to the results from WOBBE. This validation process is described in the dissertation and is of great importance. Without validation the programme could only be used to signal trends. Being validated, it can actually be used in the determination of the stability of wind turbines. Finally, the possibility of flap-lag-stall flutter occurring on large wind turbines has been investigated using WOBBE. As discussed in the previous section, the upscaling of wind turbines has resulted in the flap frequency coming closer to the lead-lag frequency. Therefore instabilities that concern these two frequencies being close to each other, become realistic possibilities. Chapters 2, 3

Holierhoek, J.G.

2008-11-19

101

On the Fatigue Analysis of Wind Turbines  

Energy Technology Data Exchange (ETDEWEB)

Modern wind turbines are fatigue critical machines that are typically used to produce electrical power from the wind. Operational experiences with these large rotating machines indicated that their components (primarily blades and blade joints) were failing at unexpectedly high rates, which led the wind turbine community to develop fatigue analysis capabilities for wind turbines. Our ability to analyze the fatigue behavior of wind turbine components has matured to the point that the prediction of service lifetime is becoming an essential part of the design process. In this review paper, I summarize the technology and describe the ''best practices'' for the fatigue analysis of a wind turbine component. The paper focuses on U.S. technology, but cites European references that provide important insights into the fatigue analysis of wind turbines.

Sutherland, Herbert J.

1999-06-01

102

A phenomenological model for the dynamic response of wind turbines to turbulent wind  

Energy Technology Data Exchange (ETDEWEB)

To predict the average power output of a wind turbine, a response model is proposed which takes into account: (1) the delayed response to the longitudinal wind speed fluctuations; (2) a response function of the turbine with arbitrary frequency dependence; and (3) wind fields of arbitrary turbulence intensity. In the limit of low turbulence intensity, the dynamical ansatz as proposed in 1992 by Rosen and Sheinman is reproduced. It is shown, how the response function of the turbine can be obtained from simulation experiments of a specific wind turbine. For two idealized situations the dynamic effect of fluctuating wind is estimated at turbulence intensities 0{<=}I{sub u}{<=}0.5. At the special mean wind speed V=8m/s, the turbine response function is determined from simulation data published by Sheinman and Rosen in 1992 and 1994.

Rauh, Alexander; Peinke, Joachim [Institut fur Physik, Universitat Oldenburg, D-26111 Oldenburg (Germany)

2004-02-01

103

New wind turbines of high profitability  

International Nuclear Information System (INIS)

To generate more quantities of electric energy from wind it is necessary to use the new type of wind turbine built in regulable mantle's nozzle, which the free air stream of wind replaces in programmed i.e. regulated and partially concentrated. In this way their efficiency is multiplied. New turbines are getting more power (P = f(v3)) from cube of higher speeds from weaker and medium winds. Short economic analysis evidently indicates that profit achieved by new wind turbines is 5 (five) times higher than that by conventional turbines. (author)

104

Wind Turbine Generator System Acoustic Noise Test Report for the Gaia Wind 11-kW Wind Turbine  

Energy Technology Data Exchange (ETDEWEB)

This report details the acoustic noise test conducted on the Gaia-Wind 11-kW wind turbine at the National Wind Technology Center. The test turbine is a two- bladed, downwind wind turbine with a rated power of 11 kW. The test turbine was tested in accordance with the International Electrotechnical Commission standard, IEC 61400-11 Ed 2.1 2006-11 Wind Turbine Generator Systems -- Part 11 Acoustic Noise Measurement Techniques.

Huskey, A.

2011-11-01

105

Wind Turbine Manufacturing Process Monitoring  

Energy Technology Data Exchange (ETDEWEB)

To develop a practical inline inspection that could be used in combination with automated composite material placement equipment to economically manufacture high performance and reliable carbon composite wind turbine blade spar caps. The approach technical feasibility and cost benefit will be assessed to provide a solid basis for further development and implementation in the wind turbine industry. The program is focused on the following technology development: (1) Develop in-line monitoring methods, using optical metrology and ultrasound inspection, and perform a demonstration in the lab. This includes development of the approach and performing appropriate demonstration in the lab; (2) Develop methods to predict composite strength reduction due to defects; and (3) Develop process models to predict defects from leading indicators found in the uncured composites.

Waseem Faidi; Chris Nafis; Shatil Sinha; Chandra Yerramalli; Anthony Waas; Suresh Advani; John Gangloff; Pavel Simacek

2012-04-26

106

Cooperative investment in wind turbines  

International Nuclear Information System (INIS)

Two fiscal options to invest in wind turbines are available in the Netherlands for enterprises: the EIA (energy investment deduction) and the VAMIL (random debit of environmental investments). Non-profit organizations (in this case, e.g. private persons, foundations, associations) can make use of the subsidy EINP (energy supply in non-profit and other special sectors). Attention is paid to the use of the fore-mentioned legal forms, while there are other, more advantageous forms, that can be used to start a cooperative to set up a wind farm

107

Standards for measurements and testing of wind turbine power quality  

Energy Technology Data Exchange (ETDEWEB)

The present paper describes the work done in power quality sub-task of the project `European Wind Turbine Testing Procedure Developments` funded by the EU SMT program. The objective of the power quality sub-task has been to make analyses and new recommendation(s) for the standardisation of measurement and verification of wind turbine power quality. The work has been organised in three major activities. The first activity has been to propose measurement procedures and to verify existing and new measurement procedures. This activity has also involved a comparison of the measurements and data processing of the participating partners. The second activity has been to investigate the influence of terrain, grid properties and wind farm summation on the power quality of wind turbines with constant rotor speed. The third activity has been to investigate the influence of terrain, grid properties and wind farm summation on the power quality of wind turbines with variable rotor speed. (au)

Soerensen, P. [Risoe National Lab., Roskilde (Denmark); Gerdes, G.; Klosse, R.; Santjer, F. [DEWI, Wilhelmshaven (Germany); Robertson, N.; Davy, W. [NEL, Glasgow (United Kingdom); Koulouvari, M.; Morfiadakis, E. [CRES, Pikermi (Greece); Larsson, Aa. [Chalmers Univ. of Technology, Goeteborg (Sweden)

1999-03-01

108

Wind turbine power tracking using an improved multimodel quadratic approach.  

Science.gov (United States)

In this paper, an improved multimodel optimal quadratic control structure for variable speed, pitch regulated wind turbines (operating at high wind speeds) is proposed in order to integrate high levels of wind power to actively provide a primary reserve for frequency control. On the basis of the nonlinear model of the studied plant, and taking into account the wind speed fluctuations, and the electrical power variation, a multimodel linear description is derived for the wind turbine, and is used for the synthesis of an optimal control law involving a state feedback, an integral action and an output reference model. This new control structure allows a rapid transition of the wind turbine generated power between different desired set values. This electrical power tracking is ensured with a high-performance behavior for all other state variables: turbine and generator rotational speeds and mechanical shaft torque; and smooth and adequate evolution of the control variables. PMID:20434153

Khezami, Nadhira; Benhadj Braiek, Naceur; Guillaud, Xavier

2010-07-01

109

Wind Turbine Noise Modelling Based on Amiet's Theory  

OpenAIRE

Broadband noise generated aerodynamically is the dominant noise source for a modern wind turbine(Brooks et al, 1989; Oerlemans et al, 2007). In this paper, two main broadband noise mechanisms, namely trailing edge noise and turbulent inflow noise, are examined in detail using frequency domain noise prediction models based on Amiet's analytical theory. Improvements are proposed to adapt the original model to wind turbines . First, a wall pressure spectral model proposed recently by Rozenberg, ...

Tian, Yuan; Cotte, Benjamin; Chaigne, Antoine

2013-01-01

110

Numerical Simulations of Wakes of Wind Turbines in Wind Farms  

DEFF Research Database (Denmark)

Wakes of both a stand-alone wind turbine and 3 wind turbines placed in a row is analysed using a numerical method where a three-dimensional Navier Stokes solver is combined with an actuator line technique. The computations on the single turbine indicate the appearance of low frequency fluctuations of the wake similar to what is observed behind a disc. Furthermore, the computations on a row of turbines demonstrate that downstream turbines might experience the distinct tip vortices formed in the wake of upstream turbines. Results also show that placing the turbines too closely can significantly reduce the produced power.

Troldborg, Niels; SØrensen, Jens NØrkær

2006-01-01

111

Report on the safety of wind turbines installations; Rapport sur la securite des installations eoliennes  

Energy Technology Data Exchange (ETDEWEB)

This report aims to study the regulatory framework governing the safety of wind turbines and proposes improvement actions. It concerns the wind turbines risk assessment, the technical bases of the wind turbines safety, the regulation relative to the safety and possible evolutions. (A.L.B.)

Guillet, R.; Leteurtrois, J.P.

2004-07-01

112

Development of Superconducting Wind Turbine Generators  

DEFF Research Database (Denmark)

In this paper the commercial activities in the field of superconducting machines, particularly superconducting wind turbine generators, are reviewed and presented. Superconducting generators have the potential to provide a compact and light weight drive train at high torques and slow rotational speeds, because high magnetic fields can be produced by coils with very little loss. Three different superconducting wind turbine generator topologies have been proposed by three different companies. One is based on low temperature superconductors (LTS); one is based on high temperature superconductors (HTS); and one is a fully superconducting generator based on MgB2. It is concluded that there is large commercial interest in superconducting machines, with an increasing patenting activity. Such generators are however not without their challenges. The superconductors have to be cooled down to somewhere between 4K and 50K, depending on what type of superconductor is employed, which poses a significant challenge both from a construction and operation point of view. The high temperature superconductors can facilitate a higher operation temperature and simplified cooling, but the current price and production volumes prohibit a large scale impact on the wind sector. The low temperature superconductors are readily available, but will need more sophisticated cooling. Eventually the CoE from superconducting wind turbines, with particular emphasis on reliability, will determine if they become feasible or not and for such investigations large-scale demonstrations will be needed.

Jensen, Bogi Bech; Mijatovic, Nenad

2012-01-01

113

Development of superconducting wind turbine generators  

DEFF Research Database (Denmark)

In this paper, the commercial activities in the field of superconducting machines, particularly superconducting wind turbine generators, are reviewed and presented. Superconducting generators have the potential to provide a compact and light weight drive train at high torques and slow rotational speeds, because high magnetic fields can be produced by coils with very little loss. Three different superconducting wind turbine generator topologies have been proposed by three different companies. One is based on low temperature superconductors; one is based on high temperature superconductors; and one is a fully superconducting generator based on MgB2. It is concluded that there is large commercial interest in superconducting machines, with an increasing patenting activity. Such generators are, however, not without their challenges. The superconductors have to be cooled down to somewhere between 4 K and 50 K, depending on what type of superconductor is employed, which poses a significant challenge both from a construction and operation point of view. The high temperature superconductors can facilitate a higher operation temperature and simplified cooling, but the current price and production volumes prohibit a large scale impact on the wind sector. The low temperature superconductors are readily available, but will need more sophisticated cooling. Eventually the Cost of Energy from superconducting wind turbines, with particular emphasis on reliability, will determine if they become feasible or not and for such investigations large-scale demonstrations will be needed. © 2013 AIP Publishing LLC.

Jensen, Bogi Bech; Mijatovic, Nenad

2013-01-01

114

Optimal Structural Reliability of Offshore Wind Turbines  

DEFF Research Database (Denmark)

The main failure modes of modern large wind turbines are fatigue failure of wings, hub, shaft and main tower, local buckling of main tower, and failure of the foundation. This paper considers reliability-based optimal design of wind turbines. Compared to onshore wind turbines and building structures, humans spent little time in the vicinity of offshore wind turbines and the probability of human injury during storm conditions is small. Further environmental pollution will also in general be small in case of failure. One could therefore argue that the reliability level of offshore wind turbines can be lower than for onshore wind turbines and other civil engineering structures and can be assessed by reliability-based cost-optimization. Specifically this paper considers the main tower and foundation. Both fatigue and ultimate strength failure modes are included. Different formulations of the objective function are considered.

SØrensen, John Dalsgaard; Tarp-Johansen, N.J.

2005-01-01

115

Cost optimization of wind turbines for large-scale offshore wind farms  

International Nuclear Information System (INIS)

This report contains a preliminary investigation of site specific design of off-shore wind turbines for a large off-shore wind farm project at Roedsand that is currently being proposed by ELKRAFT/SEAS. The results were found using a design tool for wind turbines that involve numerical optimization and aeroelastic calculations of response. The wind climate was modeled in detail and a cost function was used to estimate costs from manufacture and installation. Cost of energy is higher for off-shore installations. A comparison of an off-shore wind farm site with a typical stand alone on-shore site showed an increase of the annual production of 28% due to the difference in wind climate. Extreme loads and blade fatigue loads were nearly identical, however,fatigue loads on other main components increased significantly. Optimizations were carried out to find the optimum overall off-shore wind turbine design. A wind turbine for the off-shore wind farm should be different compared with a stand-alone on-shore wind turbine. The overall design changed were increased swept area and rated power combined with reduced rotor speed and tower height. Cost was reduced by 12% for the final 5D/14D off-shore wind turbine from 0.306 DKr/kWh to 0.270 DKr/kWh. These figures include capital costs from manufacture and installation but not on-going costs from maintenance. These results make off-shore wind farms more competitive and comparable to the reference on-shore stand-alone wind turbine. A corresponding reduction of cost of energy could not be found for the stand alone on-shore wind turbine. Furthermore the fatigue loads on wind turbines in on-shore wind farms will increase and cost of energy will increase in favor of off-shore wind farms. (au) EFP-95; EU-JOULE-3; 21 tabs., 7 ills., 8 refs

116

Optimization of wind turbine rotors  

Energy Technology Data Exchange (ETDEWEB)

The Constrained Steepest Descent method has been applied to the optimization of wind turbine rotors through the development of a numerical model. The model consists of an optimization kernel, an aerodynamic model, a structural dynamic model of a rotating beam, and a cost model for the wind turbine. The cost of energy is minimized directly by varying the blade design, the rotational speed and the resulting design of the drive-train and tower. The aerodynamic model is a combination of a fast engineering model based on strip-theory and two and three-dimensional Euler solvers. The two-dimensional Euler solver is used for generation of pre-stall airfoil data. Comparisons with experimental data verify that the engineering model effectively approximates non-stalled flow, except at the blade tip. The three-dimensional Euler solver is in good agreement with the experimental data at the tip, and is therefore a useful supplement for corrections of the tip-loss model, and evaluation of an optimized design. The structural dynamic model evaluates stresses and deformations for the blade. It is based on constitutive relations for a slender beam that are solved with the equations of motions using a finite-difference method. The cost model evaluates the design change of the wind turbine and the resulting costs that occur when a change in blade design modifies the blade mass and the overall forces. The cost model is based on engineering design rules for the drive-train and tower. The model was applied using a Danish 600 kW wind turbine as a reference. Two rotors were optimized using traditional NACA airfoils and a new low-lift airfoil family developed specifically for wind turbine purposes. The cost of energy decreased four percent for the NACA rotor, and seven percent for the low-lift rotor. Optimizations with a high number of degrees of freedom show that a designer has considerable flexibility in choosing some primary parameters such as rated power and rotor diameter, if the rest of the parameters are optimized. The model requires modest computer resources, and seems to be well suited for use as an industrial design tool. (author)

Nygaard, Tor Anders

1999-07-01

117

Optimization of Wind Turbine Power Coefficient Parameters using Hybrid Technique  

Science.gov (United States)

Wind turbine is a device that is used for converting kinetic energy from the wind into mechanical energy. The efficiency of wind turbine mainly depends on power coefficient of wind turbine. Maximization of power coefficient is one of the important factors for increasing efficiency in wind turbine. The maximized power coefficient enables high power production at low costs. The power coefficient is maximized by selecting suitable the values of design parameters. In this work a hybrid technique is proposed to optimize the power coefficient parameters of wind turbine blades. The proposed technique is a combination of genetic algorithm and artificial neural network (ANN). Genetic Algorithm is one of the evolutionary programs and it is used to optimize the parameters of power coefficient. The proposed genetic algorithm performs optimization in two phases. Initially, power coefficient parameters are determined for the respective angle of attack and optimized by using genetic algorithm phase I. ANN is used to generate the training data of design parameters of wind turbine. From the training data set, the best power coefficient parameters are optimized by executing phase II of the genetic algorithm. The proposed method is evaluated and its performances are identified.

Rajakumar, S.; Ravindran, D.

2012-06-01

118

Hybrid Optimization for Wind Turbine Thick Airfoils  

Energy Technology Data Exchange (ETDEWEB)

One important element in aerodynamic design of wind turbines is the use of specially tailored airfoils to increase the ratio of energy capture and reduce cost of energy. This work is focused on the design of thick airfoils for wind turbines by using numerical optimization. A hybrid scheme is proposed in which genetic and gradient based algorithms are combined together to improve the accuracy and the reliability of the design. Firstly, the requirements and the constraints for this class of airfoils are described; then, the hybrid approach is presented. The final part of this work is dedicated to illustrate a numerical example regarding the design of a new thick airfoil. The results are discussed and compared to existing airfoils.

Grasso, F. [ECN Wind Energy, Petten (Netherlands)

2012-06-15

119

On System Identification of Wind Turbines  

DEFF Research Database (Denmark)

Recently several methods have been proposed for the system identification of wind turbines which can be considered as a linear time-varying system due to the operating conditions. For the identification of linear wind turbine models, either black-box or grey-box identification can be used. In the case of black-box identification no "physical" model structure is assumed and a large number of parameters have to be defined by the identification techniques. For the identified black-box models, it is difficult to perform model analysis since the internal states are not known to the user. The operational model analysis (OMA) methodology can provide accurate estimates of the natural frequencies, damping ratios and mode shapes of the systems as long as the measurements have a low noise to signal ratio. However, in order to take information about the wind turbine into account a grey-box identification method can be used. This paper reviews proposed system identification methods and the durability and the limitations of the different methods are outlined.

Kirkegaard, Poul Henning; Perisic, Nevena

120

RBI Optimization of Offshore Wind Turbines  

OpenAIRE

Wind turbines for electricity production have increased significantly the last years both in production capability and size. This development is expected to continue also in the coming years. Offshore wind turbines with an electricity production of 5-10 MW are planned. Typically, the wind turbine support structure is a steel structure consisting of a tower and a monopile, tripod or jacket type foundation. This paper considers aspects of inspection and maintenance planning of fatigue prone det...

Rami?rez, Jose? G. Rangel; Sørensen, John Dalsgaard

2009-01-01

121

Dynamic Response of Flexible Wind Turbine Blade  

OpenAIRE

Aiming at the non-stationary and stall flutter problems of wind turbine blade caused by transient load fluctuations, the dynamic properties of wind turbine were studied, the blade was simplify to a cantilever beam in case of the action of shear deformation and cross section rotating effect were considered in this analysis, equations of the blade were established based on D'Alemberts' principle and the principle of virtual displacement. The dynamic response of the wind turbine was solved by us...

Yu-qiao Zheng; Zhao, Rong-zhen; Hong liu

2013-01-01

122

Model Predictive Control of Wind Turbines  

OpenAIRE

Wind turbines play a major role in the transformation from a fossil fuel based energy production to a more sustainable production of energy. Total-cost-of-ownership is an important parameter when investors decide in which energy technology they should place their capital. Modern wind turbines are controlled by pitching the blades and by controlling the electro-magnetic torque of the generator, thus slowing the rotation of the blades. Improved control of wind turbines, leadin...

Henriksen, Lars Christian; Poulsen, Niels Kjølstad; Hansen, Morten Hartvig

2010-01-01

123

Influence of refraction on wind turbine noise  

OpenAIRE

A semi-empirical method is applied to calculate the time-average sound level of wind turbine noise generation and propagation. Both are affected by wind shear refraction. Under upwind conditions the partially ensonified zone separates the fully ensonified zone (close to the turbine) and the shadow zone (far away from the turbine). Refraction is described in terms of the wind speed linear profile fitted to the power law profile. The rotating blades are treated as a two-dimens...

Makarewicz, Rufin

2013-01-01

124

Experimental Research for MW Wind Turbine Blade  

OpenAIRE

The objective of this study was get acquiring dependable results of MW wind turbine blade performance at work condition to design new-style blade. Most of the research study on structural analysis of wind turbine blade by make model test and use the finite element, but there were certain differences from real MW wind turbine blade. Therefore full-scale experiments were employed in the research, the strains, stresses and displacements of all parts were gained. The test results shown that...

He Bin; Song Lin-Hui; Fu Jie, .; Fan Qin-Shan

2013-01-01

125

Small Wind Research Turbine: Final Report  

Energy Technology Data Exchange (ETDEWEB)

The Small Wind Research Turbine (SWRT) project was initiated to provide reliable test data for model validation of furling wind turbines and to help understand small wind turbine loads. This report will familiarize the user with the scope of the SWRT test and support the use of these data. In addition to describing all the testing details and results, the report presents an analysis of the test data and compares the SWRT test data to simulation results from the FAST aeroelastic simulation model.

Corbus, D.; Meadors, M.

2005-10-01

126

Market experiences with small wind turbines  

International Nuclear Information System (INIS)

An overview is given of the marketing experiences of Lagerwey Windturbines with the exploitation of small wind turbines. Attention is paid to the market mechanisms which effect the sale and implementation of small wind turbines: payback of surplus power, provincial and regional subsidies, grid connection costs, energy prices, and flexible solutions for grid connections. Also problems with municipalities with regard to regulations or construction licenses are discussed. Some recommendations are given to stimulate the market for small wind turbines. 1 fig., 1 ref

127

Modeling Smart Structure of Wind Turbine Blade  

Science.gov (United States)

With the increasing size of wind turbine blades, the need for more sophisticated load control techniques has induced the interest for aerodynamic control systems with build-in intelligence on the blades. The paper aims to provide a way for modeling the adaptive wind turbine blades and analyze its ability for vibration suppress. It consists of the modeling of the adaptive wind turbine blades with the wire of piezoelectric material embedded in blade matrix, and smart sandwich structure of wind turbine blade. By using this model, an active vibration method which effectively suppresses the vibrations of the smart blade is designed.

Qiao, Yin-hu; Han, Jiang; Zhang, Chun-yan; Chen, Jie-ping

2012-06-01

128

Wind Turbine Generator System Safety and Function Test Report for the Ventera VT10 Wind Turbine  

Energy Technology Data Exchange (ETDEWEB)

This report summarizes the results of a safety and function test that NREL conducted on the Ventera VT10 wind turbine. This test was conducted in accordance with the International Electrotechnical Commissions' (IEC) standard, Wind Turbine Generator System Part 2: Design requirements for small wind turbines, IEC 61400-2 Ed.2.0, 2006-03.

Smith, J.; Huskey, A.; Jager, D.; Hur, J.

2012-11-01

129

Wind Turbine Generator System Safety and Function Test Report for the Entegrity EW50 Wind Turbine  

Energy Technology Data Exchange (ETDEWEB)

This report summarizes the results of a safety and function test that NREL conducted on the Entegrity EW50 wind turbine. This test was conducted in accordance with the International Electrotechnical Commissions' (IEC) standard, Wind Turbine Generator System Part 2: Design requirements for small wind turbines, IEC 61400-2 Ed.2.0, 2006-03.

Smith, J.; Huskey, A.; Jager, D.; Hur, J.

2012-11-01

130

Large superconducting wind turbine generators  

DEFF Research Database (Denmark)

To realize large (>10 MW) direct-driven off-shore wind turbines, a number of steps are needed to reduce weight and cost compared to on-shore technologies. One of the major challenges is to provide drive trains which can comply with the large torque as the turbine rotor diameter is scaled up and the rotation speed is lowered in order to limit the tip speed of the blades. The ability of superconducting materials to carry high current densities with very small losses might facilitate a new class of generators operating with an air gap flux density considerably higher than conventional generators and thereby having a smaller size and weight [1, 2]. A 5 MW superconducting wind turbine generator forms the basics for the feasibility considerations, particularly for the YBCO and MgB2 superconductors entering the commercial market. Initial results indicate that a 5 MW generator with an active weight of 34 tons, diameter of 4.2 m and length of 1.2 m can be realized using superconductors carrying 300 A/mm2 in a magnetic field of 4 T and an air gap flux density of the order 2.5 T. The results are compared to the performance of available superconductors, as well as the near future forecasted performance.

Abrahamsen, Asger Bech; Magnusson, Niklas

2012-01-01

131

Damage mitigating control for wind turbines  

Science.gov (United States)

In the last few decades the wind industry has made great strides in reducing the cost of energy of utility scale wind turbines. In an attempt to reduce infrastructure costs and improve efficiency, the trend has been to develop larger variations of existing designs. In the past, the wind turbine controller was used primarily for rotor speed control and prevention of catastrophic damage from extreme wind conditions or component failures. The recent trend of wind turbine growing in size has resulted in wind turbines becoming much more flexible, and now the emphasis of wind turbine controls research focuses on how to damp resonances and avoid dangerous excitations that may lead to structural failure. Control of the fatigue loads on the wind turbine structure addresses neglects the fatigue mechanism of the material. The conversion of loads into stresses and those stresses into fatigue damage is a highly nonlinear process and is based on the so-called "cycle-counting" methods. Since the cycle counting methodology is difficult to convert into the time or frequency domains, these components have been generally avoided in controls research. Without modeling the damage dynamics, the wind turbine controller cannot efficiently reduce the fatigue of the structural components. The result is that only small decreases of fatigue damage are realized by current load reduction strategies at the expense of excessive control actuation. This dissertation introduces the concept of Damage Mitigating Control (DMC) as it applies to utility scale Horizontal Axis Wind Turbines (HAWTs). The work presented extends earlier work in damage mitigating and life extending control in several ways and then applies then applies this control strategy to reduce the fatigue damage suffered by wind turbines during operation. By modeling fatigue damage dynamics within the wind turbine controller, the life of the turbine can be extended significantly without sacrificing performance.

Santos, Richard A.

2007-12-01

132

Background sound levels and wind turbine noise  

International Nuclear Information System (INIS)

This paper reviewed the regulators' approach to the challenge of establishing sound level limits in wind turbine arrays that allow for variations in background sound level with wind speed. Wind speed influences the amount of noise produced by wind turbines and also the noise associated with wind passing over terrain and through foliage. New guidelines by Ontario's Ministry of the Environment were discussed along with wind noise as a function of speed in remote locations having a variety of terrain and foliage types. It was concluded that wind induced noise can effectively mask the steady noise of wind turbine generators, especially during high wind conditions. The extent of wind induced noise depends on the local terrain, foliage and wind speed through vegetation. Masking wind turbine noise by wind induced noise in vegetation can be reduced during stable atmospheric conditions which are common at night. The extent of masking by wind induced noise depends on the level and characteristics of wind turbine noise and wind induced noise. 9 refs., 2 tabs., 2 figs

133

Implementation of Pitch Control Of wind Turbine Using Simulink (Matlab  

Directory of Open Access Journals (Sweden)

Full Text Available In this paper, it is shown that how the variable speed wind turbine can be used to generate a fixed value of voltage at the output with the help of a pi controller and it is done by varying the pitch angle of the blades Pitch angle control is the most common means for adjusting the aerodynamic torque of the wind turbine when wind speed is above rated speed and various controlling variables may be chosen, such as wind speed, generator speed and generator power. As conventional pitch control usually use PI controller, the mathematical model of the system should be known well. The block diagram of the proposed speed control system which consists of speed controller, actuator model and the turbine linearized model is simulated by Matlab-Simulink software package. the simulation results show that the controller accurately adjusts the blade pitch angle to set the wind turbine power output to its reference value.

Sachin Khajuria, Jaspreet Kaur

2012-06-01

134

Wind Turbines Support Techniques during Frequency Drops — Energy Utilization Comparison  

Directory of Open Access Journals (Sweden)

Full Text Available The supportive role of wind turbines during frequency drops is still not clear enough, although there are many proposed algorithms. Most of the offered techniques make the wind turbine deviates from optimum power generation operation to special operation modes, to guarantee the availability of reasonable power support, when the system suffers frequency deviations. This paper summarizes the most dominant support algorithms and derives wind turbine power curves for each one. It also conducts a comparison from the point of view of wasted energy, with respect to optimum power generation. The authors insure the advantage of a frequency support algorithm, they previously presented, as it achieved lower amounts of wasted energy. This analysis is performed in two locations that are promising candidates for hosting wind farms in Egypt. Additionally, two different types of wind turbines from two different manufacturers are integrated. Matlab and Simulink are the implemented simulation environments.

Ayman B. Attya

2014-08-01

135

Spatial planning of wind turbines  

Energy Technology Data Exchange (ETDEWEB)

This paper proposes guidelines for spatial planning for wind power, based on experience with spatial planning in Belgium, Denmark, France and the Netherlands. In addition experiences from Germany and Ireland have been used. This guidelines quotes all decisive criteria for successful implementation of wind energy: landscape integration, stakeholders involvement, noise and distance from buildings. (author)

NONE

2004-01-01

136

Robust Utilization of Wind Turbine Flexibility for Grid Stabilization  

OpenAIRE

This work considers the use of wind turbines for stabilizing an electrical grid, by employing temporary overproduction with respect to available power. We present a simple model describing a turbine, and show how the possible period of overproduction, can be maximized through a series of convex problems, where the load is distributed among several turbines in a farm. We then present an optimization scheme that guarantees a lower limit for the overproduction period and subsequently propose an ...

Juelsgaard, Morten; Bendtsen, Jan Dimon; Wisniewski, Rafal

2012-01-01

137

Mechanical noise from wind turbines  

International Nuclear Information System (INIS)

Community annoyance due to noise from wind turbines is often the result of noise character rather than level. Although the overall contributions from each of the two main classes of noise source, namely aerodynamic and mechanical, are often of a similar order for an untreated turbine, it is usually the mechanical sources which provide the dominant noise characteristics that may lead to annoyance. In this paper, the sources of mechanical noise are identified primarily with reference to HAWTs and then attention is concentrated on the rotor-shaft step-up gearbox, which is normally the top-ranking source. The major gearbox noise mechanisms and transmission paths are discussed and reference made to Noise Specifications and procedures applicable to the gearbox prior to its installation. The reduction of machinery noise is reviewed both at source and by treatment of transmission paths. (author)

138

Optimization of wind turbine rotors  

Energy Technology Data Exchange (ETDEWEB)

A computer program for aerodynamic optimization of wind turbine rotors has been written in Fortran with the purpose to maximize the annual energy production. The constraints is the maximum power output from the turbine and maximum and minimum values on the design variables. The design of the rotor is described by the chord- and twist distribution. The chord- and twist distributions are described with Bezier splines which, with a few number of control points, are very flexible. The Bezier control points are the design variables which are optimized by the optimization program. The optimization method used in the program is the Method of Moving Asymptotes, MMA, suggested by Krister Svanberg at the Royal Institute of Technology in Stockholm. MMA is a stable method and it seems suitable for this application. It is also in general easy to implement constraints. It seems like there are many local maximum points and the variations in the annual energy production between the total maximum points are very small, so there are many solutions to choose between and finding the global maximum point can be a problem. The problem could possibly be avoided with smaller wind steps near the rated wind. In future versions of the optimization program the Reynolds number dependents of the aerodynamic coefficients should be taken into consideration. Constraints for the thrust and the aerodynamic noise should also be implemented in the program 8 refs, 8 figs, 13 tabs, 14 appendixes

Holmkvist, Jonas

1998-05-01

139

Mitigation of Wind Power Fluctuation by Active Current Control of Variable Speed Wind Turbines  

DEFF Research Database (Denmark)

Wind shear and tower shadow are the sources of power fluctuation of grid connected wind turbines during continuous operation. This paper presents a simulation model of a MW-level doubly fed induction generator (DFIG) based variable speed wind turbine with a partial-scale back-to-back power converter in Simulink. A simple and effective method of wind power fluctuations mitigation by active current control of DFIG is proposed. It smoothes the generator output active power oscillations by adjusting the active current of the DFIG, such that the power oscillation is stored as the kinetic energy of the wind turbine. The simulations are performed on the NREL 1.5MW upwind reference wind turbine model. The simulation results are presented and discussed to demonstrate the validity of the proposed control method.

Zhang, Yunqian; Chen, Zhe

2013-01-01

140

H-Darrieus Wind Turbine with Blade Pitch Control  

OpenAIRE

A procedure for computing the optimal variation of the blades' pitch angle of an H-Darrieus wind turbine that maximizes its torque at given operational conditions is proposed and presented along with the results obtained on a 7?kW prototype. The CARDAAV code, based on the “Double-Multiple Streamtube” model developed by the first author, is used to determine the performances of the straight-bladed vertical axis wind turbine. This was coupled with a genetic algorithm opti...

Paraschivoiu, I.; Trifu, O.; Saeed, F.

2009-01-01

141

Aerodynamic interference between two Darrieus wind turbines  

Energy Technology Data Exchange (ETDEWEB)

The effect of aerodynamic interference on the performance of two curved bladed Darrieus-type vertical axis wind turbines has been calculated using a vortex/lifting line aerodynamic model. The turbines have a tower-to-tower separation distance of 1.5 turbine diameters, with the line of turbine centers varying with respect to the ambient wind direction. The effects of freestream turbulence were neglected. For the cases examined, the calculations showed that the downwind turbine power decrement (1) was significant only when the line of turbine centers was coincident with the ambient wind direction, (2) increased with increasing tipspeed ratio, and (3) is due more to induced flow angularities downstream than to speed deficits near the downstream turbine.

Schatzle, P.R.; Klimas, P.C.; Spahr, H.R.

1981-04-01

142

Wind turbines fundamentals, technologies, application, economics  

CERN Document Server

"Wind Turbines" addresses all those professionally involved in research, development, manufacture and operation of wind turbines. It provides a cross-disciplinary overview of modern wind turbine technology and an orientation in the associated technical, economic and environmental fields.  In its revised third edition, special emphasis has been given to the latest trends in wind turbine technology and design, such as gearless drive train concepts, as well as on new fields of application, in particular the offshore utilisation of wind energy. The author has gained experience over decades designing wind energy converters with a major industrial manufacturer and, more recently, in technical consulting and in the planning of large wind park installations, with special attention to economics.

Hau, Erich

2013-01-01

143

Aeroelastic stability of wind turbine blades  

Science.gov (United States)

The second degree nonlinear aeroelastic equations for a flexible, twisted, nonuniform wind turbine blade were developed using Hamilton's principle. The derivation of these equations has its basis in the geometric nonlinear theory of elasticity. These equations with periodic coefficients are suitable for determining the aeroelastic stability and response of large wind turbine blades. Methods for solving these equations are discussed.

Kaza, K. R. V.

1928-01-01

144

Dynamic Phase Compensation of wind turbines  

DEFF Research Database (Denmark)

This paper describes a dynamic phase compensation unit for a wind turbine with directly connected induction generators. The compensation unit is based on thyristor switched capacitors, where conventional wind turbine compensations use mechanical contactors to switch the capacitors. The unit modules are tested and simulated, and preliminary studies on the impact on power quality are performed.

Soerensen, P.; Skaarup, J.

2004-01-01

145

Multilevel converters for 10 MW Wind Turbines  

DEFF Research Database (Denmark)

Several promising multi-level converter configurations for 10 MW Wind Turbines both with direct drive and one-stage gear box drive using Permanent Magnet Synchronous Generator (PMSG) are proposed, designed and compared. Reliability is a crucial indicator for large scale wind power converters, therefore the evaluations are mainly focused on the power device thermal performances, which are closely related to the life time and cost of the converter. Simulation results of different converter candidates regarding the loss and junction temperature are presented and analyzed. It is concluded that the three-level and five-level H-bridge converter topologies both have potential to achieve improved thermal performances compared to the three-level Neutral-Point-Clamped converter topology in the wind power application.

Ma, Ke; Blaabjerg, Frede

2011-01-01

146

Virtual inertia for variable speed wind turbines  

DEFF Research Database (Denmark)

Inertia provision for frequency control is among the ancillary services that different national grid codes will likely require to be provided by future wind turbines. The aim of this paper is analysing how the inertia response support from a variable speed wind turbine (VSWT) to the primary frequency control of a power system can be enhanced. Unlike fixed speed wind turbines, VSWTs do not inherently contribute to system inertia, as they are decoupled from the power system through electronic converters. Emphasis in this paper is on how to emulate VSWTs inertia using control of the power electronic converter and on its impact on the primary frequency response of a power system. An additional control for the power electronics is implemented to give VSWTs a virtual inertia, referring to the kinetic energy stored in the rotating masses, which can be released initially to support the system’s inertia. A simple Matlab/Simulink model and control of a VSWT and of a generic power system are developed to analyse the primary frequency response following different generation losses in a system comprising VSWTs provided with virtual inertia. The possibility of substituting a 50% share of conventional power with wind is also assessed and investigated. The intrinsic problems related to the implementation of virtual inertia are illustrated, addressing their origin in the action of pitch and power control. A solution is proposed, which aims at obtaining the same response as for the system with only conventional generation. The range of wind speeds near the power limitation zone seems to be the most critical from a primary response point of view. The theoretical reasons behind this are elucidated in the paper. Copyright © 2012 John Wiley & Sons, Ltd.

Zeni, Lorenzo; Rudolph, Andreas Jakob

2013-01-01

147

Performance assessment of a small wind turbine with crossflow runner by numerical simulations  

Energy Technology Data Exchange (ETDEWEB)

Most of the classical wind turbines are not able to start at wind speeds as low as 2-3 m/s. Other turbines, like Savonius, have a low maximum efficiency, which renders them useless in poor wind conditions. Therefore, new turbine designs are required to harvest wind power even when the wind speed is low. A wind turbine having a crossflow runner, similar to the Banki water turbine, is studied numerically in this work in order to estimate its performance. The results obtained suggest that this turbine has a considerable high starting torque and its maximum power coefficient is comparable to those of horizontal axis wind turbines. Based on the results obtained, some improvements of the design are proposed in order to further increase turbine performance. (author)

Dragomirescu, A. [University Politehnica of Bucharest, Department of Hydraulics, Hydraulic Machinery and Environmental Engineering, Splaiul Independentei 313, 060042 Bucharest (Romania)

2011-03-15

148

Certification testing for small wind turbines  

Energy Technology Data Exchange (ETDEWEB)

This paper describes the testing procedures for obtaining type certification for a small wind turbine. Southwest Windpower (SWWP) is seeking type certification from Underwriters Laboratory (UL) for the AIR 403 wind turbine. UL is the certification body and the National Renewable Energy Laboratory (NREL) is providing technical assistance including conducting the certification testing. This is the first small turbine to be certified in the US, therefore standards must be interpreted and test procedures developed.

Corbus, D.; Link, H.; Butterfield, S.; Stork, C.; Newcomb, C.

1999-10-20

149

Lightning protection system for a wind turbine  

Science.gov (United States)

In a wind turbine (104, 500, 704) having a plurality of blades (132, 404, 516, 744) and a blade rotor hub (120, 712), a lightning protection system (100, 504, 700) for conducting lightning strikes to any one of the blades and the region surrounding the blade hub along a path around the blade hub and critical components of the wind turbine, such as the generator (112, 716), gearbox (708) and main turbine bearings (176, 724).

Costin, Daniel P. (Chelsea, VT); Petter, Jeffrey K. (Williston, VT)

2008-05-27

150

Discord amongst the wind turbine buyers with regard to Dutch wind turbine manufacturers  

International Nuclear Information System (INIS)

In the Netherlands two medium-large manufacturers of wind turbines exist: NedWind (Hollandia Kloos) and Windmaster Nederland (Begemann Groep). Also Lagerwey, which constructs wind turbines for the private market (farmers, cooperatives), is important for the Dutch market and successfull in Germany. There is a tendency amongst the Dutch energy utilities, which cooperate in the foundation WindPlan, to buy wind turbines from foreign manufacturers. Some energy utilities want to take advantage of the most attractive offers, while others want to cooperate in building up a Dutch wind turbine industry. 5 ills

151

MOD-2 wind turbine farm stability study  

Science.gov (United States)

The dynamics of single and multiple 2.5 ME, Boeing MOD-2 wind turbine generators (WTGs) connected to utility power systems were investigated. The analysis was based on digital simulation. Both time response and frequency response methods were used. The dynamics of this type of WTG are characterized by two torsional modes, a low frequency 'shaft' mode below 1 Hz and an 'electrical' mode at 3-5 Hz. High turbine inertia and low torsional stiffness between turbine and generator are inherent features. Turbine control is based on electrical power, not turbine speed as in conventional utility turbine generators. Multi-machine dynamics differ very little from single machine dynamics.

Hinrichsen, E. N.

1980-01-01

152

Superconductivity for Large Scale Wind Turbines  

Energy Technology Data Exchange (ETDEWEB)

A conceptual design has been completed for a 10MW superconducting direct drive wind turbine generator employing low temperature superconductors for the field winding. Key technology building blocks from the GE Wind and GE Healthcare businesses have been transferred across to the design of this concept machine. Wherever possible, conventional technology and production techniques have been used in order to support the case for commercialization of such a machine. Appendices A and B provide further details of the layout of the machine and the complete specification table for the concept design. Phase 1 of the program has allowed us to understand the trade-offs between the various sub-systems of such a generator and its integration with a wind turbine. A Failure Modes and Effects Analysis (FMEA) and a Technology Readiness Level (TRL) analysis have been completed resulting in the identification of high risk components within the design. The design has been analyzed from a commercial and economic point of view and Cost of Energy (COE) calculations have been carried out with the potential to reduce COE by up to 18% when compared with a permanent magnet direct drive 5MW baseline machine, resulting in a potential COE of 0.075 $/kWh. Finally, a top-level commercialization plan has been proposed to enable this technology to be transitioned to full volume production. The main body of this report will present the design processes employed and the main findings and conclusions.

R. Fair; W. Stautner; M. Douglass; R. Rajput-Ghoshal; M. Moscinski; P. Riley; D. Wagner; J. Kim; S. Hou; F. Lopez; K. Haran; J. Bray; T. Laskaris; J. Rochford; R. Duckworth

2012-10-12

153

Aerodynamics of Wind Turbines : second edition  

DEFF Research Database (Denmark)

Aerodynamics of Wind Turbines is the established essential text for the fundamental solutions to efficient wind turbine design. Now in its second edition, it has been entirely updated and substantially extended to reflect advances in technology, research into rotor aerodynamics and the structural response of the wind turbine structure. Topics covered include increasing mass flow through the turbine, performance at low and high wind speeds, assessment of the extreme conditions under which the turbine will perform and the theory for calculating the lifetime of the turbine. The classical Blade Element Momentum method is also covered, as are eigenmodes and the dynamic behavior of a turbine. The new material includes a description of the effects of the dynamics and how this can be modeled in an aeroelastic code, which is widely used in the design and verification of modern wind turbines. Further, the description of how to calculate the vibration of the whole construction as well as the time varying loads has been substantially updated. This is the essential reference for both engineering students and others with a professional or academic interest in the physics and technologies behind horizontal axis wind turbines.

Hansen, Martin Otto Laver

2008-01-01

154

Turbulent flow simulation over ice-accreted wind turbine blades  

Energy Technology Data Exchange (ETDEWEB)

This presentation reported on the results of a numerical and experimental research project on the effect of ice accretion on wind turbines. The study involved optimization of de-icing procedures as well as prediction of performance reduction in aerodynamics of iced airfoils. The purpose of the project was to analyze the impact of ice accretion on a wind turbine performance simulating the flow around clean and iced NACA 63-415 airfoils using the commercial package Fluent. The presentation outlined the problems caused by ice accreted over wind turbine blades and de-icing systems. The numerical model and results were also presented. The study proposed the most appropriate turbulence model to be used for airfoils with very large separated regions to determine the aerodynamic performance of iced airfoils and therefore to predict the production loss of a wind turbine during icing events. tabs., figs.

Villalpando, F.; Reggio, M. [Ecole Polytechnique, Montreal, PQ (Canada); Ilinca, A. [Quebec Univ., Rimouski, PQ (Canada). Wind Energy Group

2009-07-01

155

Structural optimization study of composite wind turbine blade  

DEFF Research Database (Denmark)

In this paper the initial layout of a 2. MW composite wind turbine blade is designed first. The new airfoils families are selected to design a 2. MW wind turbine blade. The finite element parametric model for the blade is established. Based on the modified Blade Element Momentum theory, a new one-way fluid-structure interaction method is introduced. A procedure combining finite element analysis and particle swarm algorithm to optimize composite structures of the wind turbine blade is developed. The procedure proposed not only allows thickness variation but also permits the spar cap location variation over the structure. The results show that, compared to the initial blade, the mass of the optimized blades is reduced and especially for the scheme II (the location of blade spar cap is seen as one of the variables) which exhibit more mass saving. This present study has important significance for the structural design and optimization of wind turbine blades. © 2012.

Chen, Jin; Shen, Wen Zhong

2013-01-01

156

Overview of power converter designs feasible for high voltage transformer-less wind turbine  

DEFF Research Database (Denmark)

Many leading wind turbine manufacturers are pushing forward in variable-speed wind turbines, often exceeding 5 MW. Therefore, novel designs and concepts for optimal high power wind turbines appeared. One of the most promising concepts is the high voltage (10-35 kV) transformer-less topology. High voltage design enables low power losses and elimination of bulky step-up transformer from the wind turbine system. However, new challenges appear for such topology, which have to be properly identified and successfully overcome. This paper presents possible concept for transformer-less wind turbine topology along with an overview of most promising candidates for optimal full-scale power converter design. Study is carried with proposed and justified high voltage wind turbine application along with selection of existing and most promising multilevel power converter topologies, which could be successfully proposed for transformer-less wind turbines.

Sztykiel, Michal

2011-01-01

157

Wind turbines - generating noise or electricity?  

International Nuclear Information System (INIS)

Wind turbine technology has made great strides in the past few years. Annual energy output is up by two orders of magnitude and nacelle weight and noise has been halved. Computational fluid dynamics has paid a part in advancing knowledge of air flow and turbulence around wind generators. Current research is focused on how to increase turbine size and improve efficiency. A problem is that while larger wind turbines will produce cheaper electricity, the noise problem will mean that the number of acceptable sites will decrease. The biggest wind generators will need about 800 m clearance from the nearest house. (UK)

158

Urban wind turbines. Guidelines for small wind turbines in the built environment  

International Nuclear Information System (INIS)

The objective of the WINEUR project (Wind Energy Integration in the Urban Environment) is to determine the deployability of small wind turbines in built environments while identifying the current significant constraints and possible solutions. The purpose of this document is to Inform the stakeholders about the state of the development of small wind turbines for the built environment; Provide practical guidelines to actors dealing with installation of small wind turbines in urban areas; and Provide recommendations for future products and for market development

159

Design and development of direct drive generators for wind turbines  

International Nuclear Information System (INIS)

This paper discusses various options for wind generators in modern wind turbines without any gearbox. Various power converter configurations are also discussed. The design of modern and efficient variable speed generators is also proposed. The design of a novel permanent magnet generator is also given. (author)

160

Power Control Design for Variable-Speed Wind Turbines  

Directory of Open Access Journals (Sweden)

Full Text Available This paper considers power generation control in variable-speed variable-pitch horizontal-axis wind turbines operating at high wind speeds. A dynamic chattering torque control and a proportional integral (PI pitch control strategy are proposed and validated using the National Renewable Energy Laboratory wind turbine simulator FAST (Fatigue, Aerodynamics, Structures, and Turbulence code. Validation results show that the proposed controllers are effective for power regulation and demonstrate high-performances for all other state variables (turbine and generator rotational speeds; and smooth and adequate evolution of the control variables for turbulent wind conditions. To highlight the improvements of the provided method, the proposed controllers are compared to relevant previously published studies.

Francesc Pozo

2012-08-01

161

Wind Turbine Converter Control Interaction with Complex Wind Farm Systems  

DEFF Research Database (Denmark)

This study presents wind turbine converter stability analysis of wind farms in frequency domain. The interaction between the wind turbine control system and the wind farm structure in wind farms is deeply investigated. Two wind farms (i.e. Horns Rev II and Karnice) are taken into consideration in this study. It is shown that wind farm components, such as long high-voltage alternating current cables and park transformers, can introduce significant low-frequency series resonances seen from the wind turbine terminals that can affect wind turbine control system operation and overall wind farm stability. The same wind turbine converter control strategy is evaluated in two different wind farms. It is emphasised that the grid-side converter controller should be characterised by sufficient harmonic/noise rejection and adjusted depending on wind farms to which it is connected. Various stability indices such as gain margin, vector gain margin and phase margin are used in order to emphasise the differences between the two wind farms.

Kocewiak, Lukasz Hubert; Hjerrild, Jesper

2013-01-01

162

Meteorological aspects of siting large wind turbines  

Energy Technology Data Exchange (ETDEWEB)

This report, which focuses on the meteorological aspects of siting large wind turbines (turbines with a rated output exceeding 100 kW), has four main goals. The first is to outline the elements of a siting strategy that will identify the most favorable wind energy sites in a region and that will provide sufficient wind data to make responsible economic evaluations of the site wind resource possible. The second is to critique and summarize siting techniques that were studied in the Department of Energy (DOE) Wind Energy Program. The third goal is to educate utility technical personnel, engineering consultants, and meteorological consultants (who may have not yet undertaken wind energy consulting) on meteorological phenomena relevant to wind turbine siting in order to enhance dialogues between these groups. The fourth goal is to minimize the chances of failure of early siting programs due to insufficient understanding of wind behavior.

Hiester, T.R.; Pennell, W.T.

1981-01-01

163

Offshore wind turbines reliability, availability and maintenance  

CERN Document Server

The first book to specifically focus on offshore wind turbine technology and which addresses practically wind turbine reliability and availability. The book draws on the author's experience of power generation reliability and availability and the condition monitoring of that plant to describe the problems facing the developers of offshore wind farms and the solutions available to them to raise availability, reduce cost of energy and improve through life cost.

Tavner, Peter

2012-01-01

164

Direct Driven Generators for Vertical Axis Wind Turbines  

OpenAIRE

Wind power is a renewable energy source that is increasingly used all over the world. Most wind turbines have a horizontal axis of rotation but a few have a vertical axis of rotation. The concept presented in this thesis is a straight-bladed vertical axis wind turbine with a direct driven cable-wound permanent magnet synchronous generator. A comparison of the two different types of wind turbines, vertical axis wind turbines and horizontal axis wind turbines, have been performed considering se...

Eriksson, Sandra

2008-01-01

165

Resonances and Aerodynamic Damping of a Vertical Axis Wind Turbine  

OpenAIRE

The dynamics of a straight-bladed vertical axis wind turbine is investigated with respect to oscillations due to the elasticity of struts and shaft connecting to the hub. In particular, for the three-bladed turbine, a concept is proposed for dimensioning the turbine to maximize the size of the resonance free rpm range for operation. The effect of aerodynamic damping on the struts is also considered. The damping of these types of oscillations for a typical turbine is found to be good.

Ottermo, Fredric; Bernhoff, Hans

2012-01-01

166

Influence of refraction on wind turbine noise  

CERN Document Server

A semi-empirical method is applied to calculate the time-average sound level of wind turbine noise generation and propagation. Both are affected by wind shear refraction. Under upwind conditions the partially ensonified zone separates the fully ensonified zone (close to the turbine) and the shadow zone (far away from the turbine). Refraction is described in terms of the wind speed linear profile fitted to the power law profile. The rotating blades are treated as a two-dimensional circular source in the vertical plane. Inside the partially ensonified zone the effective A-weighted sound power decreases to zero when the receiver moves from the turbine toward the shadow zone. The presented results would be useful in practical applications to give a quick estimate of the effect of refraction on wind turbine noise.

Makarewicz, Rufin

2013-01-01

167

Modelling of a chaotic load of wind turbines drivetrain  

Science.gov (United States)

The purpose of this paper is to present a model of the load of the wind turbine gears for simulation of real, varying operational conditions for modelling of wind turbine vibration. The characteristics of the wind, which generates chaotically varying loads on the drivetrain components generating load in teeth and bearings of gears during torque transfer, are discussed. A generator of variable load of wind turbines drivetrain is proposed. Firstly, the module for generation of wind speed is designed. It is based on the approach in which the wind speed was considered as a time series approximated by the Weierstrass function. Secondly, the rotational speed of the main shaft is proposed as a function of the wind speed value. The function depends on a few parameters that are fitted by using a genetic algorithm. Finally, the model of torque of the main shaft is introduced. This model has been created by using a multi-layer artificial neural network. The results show that the proposed approach yields a very good fit for the experimental data. The fit brings about the proper reproducing of all the aspects of the load that are crucial for causing fatigue and, as a consequence, damaging of gears of the wind turbines.

Bielecki, Andrzej; Barszcz, Tomasz; Wójcik, Mateusz

2015-03-01

168

CFD modeling of wind turbine wake in wind farms  

Science.gov (United States)

Wind energy is one of the most common and preferred renewable energy sources. Accurate predictions of atmospheric boundary layer flow, wind turbine induced wakes and their interaction are essential to maximize wind power output and efficiently harness wind energy. In this dissertation, a computational fluid dynamics (CFD) flow model is developed utilizing a three dimensional weighted essentially non-oscillatory (WENO) high order Finite Volume Model system including Large Eddy Simulation (LES) and the Actuator Line Method (ALM). The developed model system is thus able to accurately capture and simulate wind turbine wakes and their interaction with the atmospheric boundary layer, thereby providing insight into the phenomenon of turbine wake interaction and its effect on the external aerodynamic loads on wind turbines. This enables the wind energy production to be maximized and also minimizes turbine fatigue loading in the evaluation of wind farm layouts. By using LES model to simulate the Atmospheric Boundary Layer flow rather than the Reynolds-Averaged Navier-Stokes (RANS) model, the error introduced by turbulence modeling is reduced. The Actuator Line Model, ALM, is used to model the rotor by replacing the rotor with radially distributed body forces. It is more accurate than the actuator disc method as it captures the influence of the blade tip vortices. It can focus on a larger portion of the wake without resolving the actual wind turbine blades' geometry, thereby reducing computational cost. It is suitable and a promising method for wind turbine wake simulation. Classic non-trivial turbulent benchmark cases are used to validate the high order LES algorithms. Simulation results are compared with available results whenever possible, with good agreement observed. Results for the atmospheric boundary layer under neutral conditions are presented. By using LES coupled with the Actuator Line model, simulation results are obtained for detailed wake flow features around single wind turbine as well as wind turbine arrays.

Sun, Lijian

169

Meteorological Controls on Wind Turbine Wakes  

DEFF Research Database (Denmark)

The primary control on the magnitude of the power losses induced by wind turbine wakes in large wind farms is the hub-height wind speed via its link to the turbine thrust coefficient. Hence, at low to moderate wind speeds (between cut-in and rated turbine wind speeds) when the thrust coefficient is high, wake losses are proportionally larger and decrease to be virtually undetectable at wind speeds above rated wind speeds. Wind direction is also critical. Not only does it determine the effective spacing between turbines but also the wind speed distribution is primarily determined by synoptic forcing and typically has a predominant direction from which wind speeds tend to be higher (from southwest for much of the central United States and northern Europe). Two other interlinked variables, turbulence intensity (TI), and atmospheric stability also dictate wake losses. Quantifying, understanding, modeling, and predicting this complex and interdependent system is therefore critical to understanding and modeling wind farm power losses due to wakes, and to optimizing wind farm layout. This paper quantifies the impact of these variables on the power loss due to wakes using data from the large offshore wind farms located at Horns Rev and Nysted in Denmark.

Barthelmie, Rebecca J. Indiana University

2013-01-01

170

Sandwich materials for wind turbine blades  

Energy Technology Data Exchange (ETDEWEB)

Wind turbine blades are being manufactured using polymer matrix composite materials (PMC), in a combination of monolithic (single skin) and sandwich composites. Present day designs are mainly based on glass fibre reinforced composites (GFRP), but for very large blades carbon fibre reinforced composites (CFRP) are being used increasingly, in addition to GFRP by several manufacturers to reduce the weight. The size of wind turbines have increased significantly over the last 25 years, and this trend is expected to continue in the future. Thus, it is anticipated that wind turbines with a rated power output in the range of 8-10 MW and a rotor diameter about 170-180 m will be developed and installed within the next 10-15 years. The paper presents an overview of current day design principles and materials technology applied for wind turbine blades, and it highlights the limitations and important design issues to be addressed for up-scaling of wind turbine blades from the current maximum length in excess of 61 m to blade lengths in the vicinity of 90 m as envisaged for future very large wind turbines. In particular, the paper discusses the potential advantages and challenges of applying sandwich type construction to a larger extent than is currently being practiced for the load carrying parts of wind turbine blades. (au)

Thybo Thomsen, O. [Aalborg Univ., Dept. of Mechanical Engineering, Aalborg (Denmark)

2006-07-01

171

Optimization and Control of a Variable Speed Wind Turbine with a Permanent Magnet Synchronous Generator  

OpenAIRE

The aim of this paper is to propose a control strategy and also analyse a fairly typical configuration of a wind turbine generating system connected with permanent magnet synchronous generator under varying speed. To reduce output power variations in wind turbine generating system, pitch angle controller of wind turbine has been used broadly. When the wind speed crosses the rated speed pitch angle controller become s active and control the power and speed to their rated values. To obtain this...

Satyam Kumar Upadhyay, Gaurav Srivastava

2013-01-01

172

Estimation of Wind Speed in Connection to a Wind Turbine  

DEFF Research Database (Denmark)

The wind speed varies over the rotor plane of wind turbine making it impossible to determine from a single wind speed measurement taken by an anemometer. However, in this paper the wind speed on the rotor plane will be estimated by using a wind turbine as a wind measuring device. To realize the idea, a knowledge of the system characteristics is required, therefore the fundamental relations and principles of system dynamics will be presented. Several estimation methods such as Newton-Raphson method, Kalman filter method and extended Kalman filter method will be investigated in the paper.

Ma, Xin; Poulsen, Niels KjØlstad

1995-01-01

173

Site specific optimization of wind turbines energy cost: Iterative approach  

International Nuclear Information System (INIS)

Highlights: • Optimization model of wind turbine parameters plus rectangular farm layout is developed. • Results show that levelized cost for single turbine fluctuates between 46.6 and 54.5 $/MW h. • Modeling results for two specific farms reported optimal sizing and farm layout. • Results show that levelized cost of the wind farms fluctuates between 45.8 and 67.2 $/MW h. - Abstract: The present study was aimed at developing a model to optimize the sizing parameters and farm layout of wind turbines according to the wind resource and economic aspects. The proposed model, including aerodynamic, economic and optimization sub-models, is used to achieve minimum levelized cost of electricity. The blade element momentum theory is utilized for aerodynamic modeling of pitch-regulated horizontal axis wind turbines. Also, a comprehensive cost model including capital costs of all turbine components is considered. An iterative approach is used to develop the optimization model. The modeling results are presented for three potential regions in Iran: Khaf, Ahar and Manjil. The optimum configurations and sizing for a single turbine with minimum levelized cost of electricity are presented. The optimal cost of energy for one turbine is calculated about 46.7, 54.5 and 46.6 dollars per MW h in the studied sites, respectively. In addition, optimal size of turbines, annual electricity production, capital cost, and wind farm layout for two different rectangular and square shaped farms in the proposed areas have been recognized. According to the results, optimal system configuration corresponds to minimum levelized cost of electricity about 45.8 to 67.2 dollars per MW h in the studied wind farms

174

European wind turbine standards 2 (EWTS-2)  

Energy Technology Data Exchange (ETDEWEB)

A summary is given of the main results of the European Wind Turbine Standards II project. EWTS-II was completed in 1998 and included investigations on: 1) wind farms-wind field and turbine loading; 2) complex terrain and fatigue loading; 3) extreme wind conditions; 4) quantification of failure probabilities; 5) integration of blade tests in design; 6) power performance in complex terrain; 7) site evaluation. In addition to these scientific evaluations, the EWTS-II participants established an organization of qualified measuring institute in the field of wind energy, the MEASNET organization. MEASNET unified measurement procedures of the participating institutes and guarantees qualified measurements and mutual acceptance among its members. (LN)

Pierik, J.T.G.; Dekker, J.W.M.; Braam, H. [and others

1999-03-01

175

Wind-turbine performance assessment  

Science.gov (United States)

Test data and experiences from funded wind turbine (WT) development and test programs in the United States and Europe are summarized. Summaries of test results for the US Department of Energy (DOE) cluster of three COD-2 2.5-MW/WT's, four MOD-OA 0.2-MW WT's, and three 0.1-MW vertical-axis WT's are presented. Descriptions of the DOE's two MOD-5 WT's, with power ratings of 7.3 and 7.2 MW, are also provided. The US Department of the Interior's Bureau of Reclamation program is updated with status reports on the 4-MW and 2.5-MW system verification units and recent test results from privately funded programs are summarized. A summary of key foreign WT programs, including test results from ongoing Danish machine tests are discussed.

Vachon, W. A.

1983-01-01

176

Effect of precipitation on wind turbine performance  

Science.gov (United States)

The effects of precipitation on wind turbine power output was analyzed. The tests were conducted on the two bladed Mod-0 horizontal axis wind turbine with three different rotor configurations. Experimental data from these tests are presented which clearly indicate that the performance of the Mod-0 wind turbine is affected by rain. Light rainfall degraded performance by as much as 20 percent while heavy rainfall degraded performance by as much as 30 percent. Snow mixed with drizzle degraded performance by as much as 36 percent at low windspeeds. Also presented are the results of an analysis to predict the effect of rain on wind turbine performance. This analysis used a blade element/momentum code with modified airfoil characteristics to account for the effect of rain and predicted a loss in performance of 31 percent in high winds with moderate rainfall rates. These predicted results agreed well with experimental data.

Corrigan, R. D.; Demiglio, R. D.

1985-05-01

177

Active load control techniques for wind turbines.  

Energy Technology Data Exchange (ETDEWEB)

This report provides an overview on the current state of wind turbine control and introduces a number of active techniques that could be potentially used for control of wind turbine blades. The focus is on research regarding active flow control (AFC) as it applies to wind turbine performance and loads. The techniques and concepts described here are often described as 'smart structures' or 'smart rotor control'. This field is rapidly growing and there are numerous concepts currently being investigated around the world; some concepts already are focused on the wind energy industry and others are intended for use in other fields, but have the potential for wind turbine control. An AFC system can be broken into three categories: controls and sensors, actuators and devices, and the flow phenomena. This report focuses on the research involved with the actuators and devices and the generated flow phenomena caused by each device.

van Dam, C.P. (University of California, Davis, CA); Berg, Dale E.; Johnson, Scott J. (University of California, Davis, CA)

2008-07-01

178

Floating offshore wind turbines for shallow waters  

Energy Technology Data Exchange (ETDEWEB)

Bottom mounted Offshore wind turbines seem to have a promising future but they are restricted to shallow waters such as in Northern Europe. Many projects are planned or are in the phase of construction in the North Sea and the Baltic Sea. All projects planned to date are in water depths of up to approximately 25 m. The research project reported in this paper investigated the technical and economical feasibility of floating wind energy systems in deeper waters, of approximately 50 m and deeper. It is assumed that at a certain water depth floating wind turbines will have better economics than bottom mounted wind turbines. Floating wind energy systems seem to have some advantages over bottom mounted wind energy systems, such as: lower cost installation (in a harbour); lower maintenance cost; lower removal cost. But floating wind energy systems have their own technical challenges, such as dynamic interactions between floater and wind turbine; floater conceptual design including mooring system, taking into account restriction w.rt. stability of floater and wind turbine, minimizing wave induced motion, water depth, etc. This paper summarises the activities undertaken within the FloatWind feasibility study carried out during 2001-2002. Full details are to be found in the Final Report, also available from ECN or any of the authors.

Bulder, B.H.; Peeringa, J.M.; Pierik, J.T.G. [ECN Wind Energy, Petten (Netherlands); Henderson, A. [Section Wind Energy, Delft University of Technology, Delft (Netherlands); Huijsmans, R.H.M.; Van Hees, M.Th. [Maritime Research Institute Netherlands, MARIN, Wageningen (Netherlands); Snijders, E.J.B. [Marine Structure Consultants MSC, Schiedam (Netherlands); Wijnants, G.H.; Wolf, M.J. [TNO, Delft (Netherlands)

2003-06-01

179

Model of wind shear conditional on turbulence and its impact on wind turbine loads  

DEFF Research Database (Denmark)

We analyse high-frequency wind velocity measurements from two test stations over a period of several years and at heights ranging from 60 to 200 m, with the objective to validate wind shear predictions as used in load simulations for wind turbine design. A validated wind shear model is thereby proposed for flat terrain and that can significantly decrease the uncertainty associated with fatigue load predictions for wind turbines with large rotors. An essential contribution is the conditioning of wind shear on the 90% quantile of wind turbulence, such that the appropriate magnitude of the design fatigue load is achieved. The proposed wind shear model based on the wind measurements is thereby probabilistic in definition, with shear jointly distributed with wind turbulence. A simplified model for the wind shear exponent is further derived from the full stochastic model. The fatigue loads over different turbine components are evaluated under the full wind measurements, using the developed wind shear model and withstandard wind conditions prescribed in the IEC 61400-1 ed. 3. The results display the effect of the Wöhler exponent and reveal that under moderate turbulence, the effect of wind shear is most pronounced on the blade flap loads. It is further shown that under moderate wind turbulence, the wind shear exponents may be over-specified in the design standards, and a reduction of wind shear exponent based on the present measurements can contribute to reduced fatigue damage equivalent loads on turbine blades. Although the influence of wind shear on extreme loads was found to be negligible, the IEC 61400-1 wind shear definition was found to result in non-conservative estimates of the 50 year extreme blade deflection toward the tower, especially under extreme turbulence conditions. Copyright © 2014 John Wiley & Sons, Ltd.

Dimitrov, Nikolay Krasimirov; Natarajan, Anand

2014-01-01

180

Damage tolerance and structural monitoring for wind turbine blades  

DEFF Research Database (Denmark)

The paper proposes a methodology for reliable design and maintenance of wind turbine rotor blades using a condition monitoring approach and a damage tolerance index coupling the material and structure. By improving the understanding of material properties that control damage propagation it will be possible to combine damage tolerant structural design, monitoring systems, inspection techniques and modelling to manage the life cycle of the structures. This will allow an efficient operation of the wind turbine in terms of load alleviation, limited maintenance and repair leading to a more effective exploitation of offshore wind.

McGugan, Malcolm; Pereira, Gilmar Ferreira

2015-01-01

181

Study on wind turbine arrangement for offshore wind farms  

DEFF Research Database (Denmark)

In this paper, the separation distance between two neighboring offshore wind turbines has been carried out by using the Actuator Line/Navier-Stokes technique developed at the Technical University of Denmark (DTU). Under offshore atmospheric conditions, Large Eddy Simulation has been performed for two Tjæreborg 2 MW wind turbines in tandem with separation distances of 4D, 5D, 6D, 7D, 8D and 10D at the design wind speed of 10 m/s. The power performance of the wake turbine showed to be about 23% of the first turbine at a separation distance of 4D while its performance reached about 50% at 7D due to the turbulence mixing. This study hints that the optimal separation distance between neighboring turbines for offshore wind farms should be 7 rotor diameters.

Shen, Wen Zhong; Mikkelsen, Robert Flemming

2011-01-01

182

Interconnection of direct-drive wind turbines using DC grid  

Energy Technology Data Exchange (ETDEWEB)

This paper presents the concept of a DC grid to interconnect wind turbines in offshore wind farms. The proposed converter topology allows series interconnection of wind turbines with need of neither transformer nor offshore platform at the sending end. Each wind turbine is equipped with a 5MW permanent-magnet synchronous generator and an ac-dc-dc converter. The converter topology is a voltage-source converter (ac-dc) cascaded with a single-switch step-down converter (dC-dc). The ac-dc stage regulates the wind turbine to operate at maximum power extraction. The dc-dc stage allows the current to flow at all times in the dc link with each dc-dc converter contributing to the net dc link voltage. The system is modeled in PSCAD/EMTDC and a 150MW wind farm is simulated. Simulation demonstrates operation of the proposed configuration where each turbine is able to independently perform peak power tracking. (orig.)

Veilleux, Etienne; Lehn, Peter W. [Toronto Univ., ON (Canada). Dept. of Electrical and Computer Engineering

2009-07-01

183

Aeroelastic instability problems for wind turbines  

DEFF Research Database (Denmark)

This paper deals with the aeroelostic instabilities that have occurred and may still occur for modem commercial wind turbines: stall-induced vibrations for stall-turbines, and classical flutter for pitch-regulated turbines. A review of previous works is combined with derivations of analytical stability limits for typical blade sections that show the fundamental mechanisms of these instabilities. The risk of stall-induced vibrations is mainly related to blade airfoil characteristics, effective direction of blade vibrations and structural damping, whereas the blade tip speed, torsional blade stiffness and chordwise position of the center of gravity along the blades are the main parameters for flutter. These instability characteristics are exemplified by aeroelastic stability analyses of different wind turbines. The review of each aeroelastic instability ends with a list of current research issues that represent unsolved aeroelostic instability problems for wind turbines. Copyright (c) 2007 John Wiley & Sons, Ltd.

Hansen, Morten Hartvig

2007-01-01

184

Wind technology development: Large and small turbines  

Science.gov (United States)

Wind technology has developed rapidly over the last decade with the design and development of advanced systems with improved performance, higher reliability, and lower costs. During the past several years, substantial gains have been made in wind turbine designs, lowering costs to an average of $0.05/kWh while further technology development is expected to allow the cost to drop below $0.04/kWh by 2000. As a result, wind is expected to be one of the least expensive forms of new electric generation in the next century. This paper will present the technology developments for both utility-scale wind turbines and remote, small-village wind turbines that are currently available or in development. Technology innovations are being adapted for remote and stand-alone power applications with smaller wind turbines. Hybrid power systems using smaller 1 to 50 (kW) wind turbines are being developed for non-grid-connected electrical generation applications. These village power systems typically use wind energy, photovoltaics, battery storage, and conventional diesel generators to power remote communities. Smaller turbines are being explored for application as distributed generation sources on utility grids to supply power during periods of peak demand, avoiding costly upgrades in distribution equipment. New turbine designs now account for turbulence-induced loads, unsteady aerodynamic stall effects, and complex fatigue loads, making use of new technology developments such as advanced airfoils. The new airfoils increase the energy capture, improve the operating efficiency, and reduce the sensitivity of the airfoils to operation roughness. Electronic controls are allowing variable rotor speed operation; while aerodynamic control devices, such as ailerons and flaps, are used to modulate power or stop the rotor in high-speed conditions. These technology trends and future turbine configurations are being sponsored and explored by the U.S. Department of Energy's Wind Energy Program.

Thresher, R. W.; Hock, S. M.; Loose, R. R.; Goldman, P.

1994-12-01

185

Airfoil characteristics for wind turbines  

DEFF Research Database (Denmark)

Airfoil characteristics for use in the Blade Element Momentum (BEM) method calculating the forces on Horizontal Axis Wind Turbines (HAWT) are derived by use of systematic methods. The investigation and derivation of the airfoil characteristics are basedon four different methods: 1) Inverse momentum theory, 2) Actuator disc theory, 3) Numerical optimisation and 4) Quasi-3D CFD computations. The two former methods are based on 3D CFD computations and wind tunnel measurements on a 41-m full-scale rotorwith LM 19.1 blades. The derived airfoil characteristics show that the lift coefficient in stall at the tip is low and that it is high at the root compared to 2D airfoil characteristics. The use of these characteristics in aeroelastic calculations shows agood agreement in power and flap moments with measurements. Furthermore, a fatigue analysis shows a reduction in the loads of up to 15 % compared to a commonly used set of airfoil characteristics. The numerical optimisation is based on both the 3D CFDcomputationsand measurements on a 41-m rotor with LM 19.1 and LM 19.0 blades, respectively. The method requires power and loads from a turbine and is promising since a set of lift and drag curves is derived that can be used to calculate mean values ofpower and loads. The lift in stall at the tip is low and at the root it is high compared to 2D airfoil characteristics. In particular the power curves were well calculated by use of the optimised airfoil characteristics. In the quasi-3D CFDcomputations, the airfoil characteristics are derived directly. This Navier-Stokes model takes into account rotational and 3D effects. The model enables the study of the rotational effect of a rotor blade at computing costs similar to what is typical for2D airfoil calculations. The depicted results show that the model is capable of determining the correct qualitative behaviour for airfoils subject to rotation. The method shows that lift is high at the root compared to 2D airfoil characteristics. Thedifferent systematic methods show theimportance of rotational and 3D effects on rotors. Furthermore, the methods show high lift coefficients in stall at the inboard part of the blade and low lift coefficients in stall at the outboard part of the bladecompared to 2D wind tunnel measurements.

Bak, C.; Fuglsang, P.

1999-01-01

186

Evaluation of different turbine concepts for wind power  

Energy Technology Data Exchange (ETDEWEB)

Every year the number of installed wind power plants in the world increases. The horizontal axis wind turbine is the most common type of turbine but there exist other types. Here, three different wind turbines are considered; the horizontal axis wind turbine and two different concepts of vertical axis wind turbines; the Darrieus turbine and the H-rotor. This paper aims at making a comparative study of these three different wind turbines from the most important aspects including structural dynamics, control systems, maintenance, manufacturing and electrical equipment. A case study is presented where three different turbines are compared to each other. Furthermore, a study of blade areas for different turbines is presented. The vertical axis wind turbine appears to be advantageous to the horizontal axis wind turbine in several aspects. (author)

Eriksson, Sandra; Bernhoff, Hans; Leijon, Mats [Swedish Centre for Renewable Electric Energy Conversion, Division for Electricity and Lightning Research, Box 534, 751 21 Uppsala (Sweden)

2008-06-15

187

LES investigation of infinite staggered wind-turbine arrays  

Science.gov (United States)

The layouts of turbines affect the turbine wake interactions and thus the wind farm performance. The wake interactions in infinite staggered wind-turbine arrays are investigated and compared with infinite aligned turbine arrays in this paper. From the numerical results we identify three types of wake behaviours, which are significantly different from wakes in aligned wind-turbine arrays. For the first type, each turbine wake interferes with the pair of staggered downstream turbine wakes and the aligned downstream turbine. For the second type, each turbine wake interacts with the first two downstream turbine wakes but does not show significant interference with the second aligned downstream turbine. For the third type, each turbine wake recovers immediately after passing through the gap of the first two downstream turbines and has little interaction with the second downstream turbine wakes The extracted power density and power efficiency are also studied and compared with aligned wind-turbine arrays.

Yang, Xiaolei; Sotiropoulos, Fotis

2014-12-01

188

Dynamic Modeling of Autonomous Wind–Diesel system with Fixed-Speed Wind Turbine  

Directory of Open Access Journals (Sweden)

Full Text Available Wind turbines have often connected to small power systems, operating in parallel to diesel generators, as is typically the case in autonomous wind–diesel installations or small island systems with high wind potential. Hence, the modeling and analysis of the dynamic behavior of wind–diesel power systems in presence of wind power will be important. In this paper, the system under study is modeled by a set of dynamic and algebraic equations (DAE. Dynamic behavior of a wind-diesel system is investigated by the proposed dynamic model. Wind-diesel system consists of wind turbines that are connected to synchronous diesel generator via short transmission line with local load. Dynamic stability of autonomous wind–diesel systems are discussed with emphasis on the eigenvalue analysis and the effective parameters on system stability. In this regards, saddle node bifurcation and hopf bifurcation are also investigated.

Farshad Dastyar

2012-07-01

189

Wind Turbine Drivetrain Condition Monitoring - An Overview  

Energy Technology Data Exchange (ETDEWEB)

This paper provides an overview of wind turbine drivetrain condition monitoring based on presentations from a condition monitoring workshop organized by the National Renewable Energy Laboratory in 2009 and on additional references.

Sheng, S; Veers, P.

2011-10-01

190

Mobile measurement system for wind turbines  

Energy Technology Data Exchange (ETDEWEB)

The aim of this project `Udviklingsafproevning af smaa moellevinger` has been to develop a mobile measurement system for wind turbines. The following report describes the measurement system. The project has been financed by the Danish Ministry of Energy. (au)

Kildemoes Moeller, T.

1997-06-01

191

Stochastic Modeling Of Wind Turbine Drivetrain Components  

DEFF Research Database (Denmark)

Cost reduction is a substantial requirement for wind turbines to become competitive compared to other energy supply techniques. For offshore wind turbines the costs for Operation and Maintenance (OM) are significant. One of the reasons for the high OM costs is unplanned repair, and therefore reliable components are needed for wind turbine. In this paper focus is on reliability of critical components in drivetrain such as bearings and shafts. High failure rates of these components imply a need for more reliable components. To estimate the reliability of these components, stochastic models are needed for initial defects and damage accumulation. In this paper, stochastic models are formulated considering some of the failure modes observed in these components. The models are based on theoretical considerations, manufacturing uncertainties, size effects of different scales. It is illustrated how the stochastic models can be used to obtain estimates of failure rates for wind turbine components.

Rafsanjani, Hesam Mirzaei; SØrensen, John Dalsgaard

2014-01-01

192

Vertical Axis Wind Turbine Foundation parameter study  

Energy Technology Data Exchange (ETDEWEB)

The dynamic failure criterion governing the dimensions of prototype Vertical Axis Wind Turbine Foundations is treated as a variable parameter. The resulting change in foundation dimensions and costs is examined.

Lodde, P.F.

1980-07-01

193

Diffuser for augmenting a wind turbine  

Science.gov (United States)

A diffuser for augmenting a wind turbine having means for energizing the boundary layer at several locations along the diffuser walls is improved by the addition of a short collar extending radially outward from the outlet of the diffuser.

Foreman, Kenneth M. (North Bellmore, NY); Gilbert, Barry L. (Westbury, NY)

1984-01-01

194

Reliability of Wind Turbine Components-Solder Elements Fatigue Failure  

DEFF Research Database (Denmark)

The physics of failure for electrical components due to temperature loading is described. The main focus is on crack propagation in solder joints and damage accumulation models based on the Miner’s rule. Two models are proposed that describe the initial accumulated plastic strain depending on the temperature mean and temperature range. Constant terms and model errors are estimated. The proposed methods are useful to predict damage values for solder joint in power electrical components. Based on the proposed methods it is described how to find the damage level for a given temperature loading profile. The proposed methods are discussed for application in reliability assessment of Wind Turbine’s electrical components considering physical, model and measurement uncertainties. For further research it is proposed to evaluate damage criteria for electrical components due to the operational temperature fluctuations within Wind Turbines

Kostandyan, Erik; SØrensen, John Dalsgaard

2012-01-01

195

Investigation of Wind Turbine Rotor Concepts for Offshore Wind Farms  

Science.gov (United States)

Current plans in offshore wind energy developments call for further reduction of cost of energy. In order to contribute to this goal, several wind turbine rotor concepts have been investigated. Assuming the future offshore wind turbines will operate only in the offshore wind farms, the rotor concepts are not only evaluated for their stand-alone performances and their potential in reducing the loads, but also for their performance in an offshore wind farm. In order to do that, the 10MW reference wind turbine designed in Innwind.EU project is chosen as baseline. Several rotor parameters have been modified and their influences are investigated for offshore wind turbine design purposes. This investigation is carried out as a conceptual parametrical study. All concepts are evaluated numerically with BOT (Blade optimisation tool) software in wind turbine level and with Farmflow software in wind farm level for two wind farm layouts. At the end, all these concepts are compared with each other in terms of their advantages and disadvantages.

Ceyhan, Özlem; Grasso, Francesco

2014-06-01

196

Wind Turbine Safety and Function Test Report for the Gaia-Wind 11-kW Wind Turbine  

Energy Technology Data Exchange (ETDEWEB)

This test was conducted as part of the U.S. Department of Energy's (DOE) Independent Testing project. This project was established to help reduce the barriers to wind energy expansion by providing independent testing results for small wind turbines (SWT). In total, four turbines were tested at the National Wind Technology Center (NWTC) as a part of this project. Safety and function testing is one of up to five tests performed on the turbines, including power performance, duration, noise, and power-quality tests. The results of the testing provide the manufacturers with reports that can be used for small wind turbine certification. The test equipment includes a Gaia-Wind 11-kW wind turbine mounted on an 18-m monopole tower. Gaia-Wind Ltd. manufactured the turbine in Denmark. The system was installed by the NWTC site operations group with guidance and assistance from Gaia-Wind.

Huskey, A.; Bowen, A.; Jager, D.

2010-01-01

197

Wind Turbine Safety and Function Test Report for the Mariah Windspire Wind Turbine  

Energy Technology Data Exchange (ETDEWEB)

This test was conducted as part of the U.S. Department of Energy's (DOE) Independent Testing project. This project was established to help reduce the barriers to wind energy expansion by providing independent testing results for small wind turbines (SWT). In total, five turbines were tested at the National Wind Technology Center (NWTC) as a part of this project. Safety and function testing is one of up to five tests performed on the turbines, including power performance, duration, noise, and power-quality tests. NWTC testing results provide manufacturers with reports that may be used to meet part of small wind turbine certification requirements. The test equipment includes a Mariah Windspire wind turbine mounted on a monopole tower. L&E Machine manufactured the turbine in the United States. The inverter was manufactured separately by Technology Driven Products in the United States. The system was installed by the NWTC site operations group with guidance and assistance from Mariah Power.

Huskey, A.; Bowen, A.; Jager, D.

2010-07-01

198

Aerodynamical noise from wind turbine generators  

International Nuclear Information System (INIS)

Two extensive measurement series of noise from wind turbines have been made during different modifications of their rotors. One series focused on the influence from the tip shape on the noise, while the other series dealt with the influence from the trailing edge. The experimental layout for the two investigations was identical. The total A-weighted noise from the wind turbine was measured in 1/3 octave bands from 50 Hz to 10 kHz in 1-minute periods simultaneously with wind speed measurements. The microphone was mounted on a hard board on the ground about 40 m directly downwind of the wind turbine, and the wind speed meter was placed at the same distance upwind of the wind turbine 10 m above ground. Regression analysis was made between noise and wind speed in each 1/3 octave band to determine the spectrum at 8 m/s. During the measurements care was taken to avoid influence from background noise, and the influence from machinery noise was minimized and corrected for. Thus the results display the aerodynamic rotor noise from the wind turbines. By use of this measurement technique, the uncertainty has been reduced to 1.5 - 2 dB per 1/3 octave band in the relevant frequency range and to about 1 dB on the total A-weighted levels. (au) (10 refs.)

199

Wind turbine dynamic - application to foundations  

OpenAIRE

These latest years, the green energy is highlighted and new technologies appeared. It is the case for wind turbines. The aim of latest developments has been to increase the power output. The use of new material enables the design of wind turbine with an impressive height, more and more flexible, inducing significant dynamic forces. However, several problems have been encountered on the connection between the foundation and the tower, which threaten the entire integrity of the structure. The i...

Bailly, Cyril

2014-01-01

200

Assessment of wind turbine load measurement instrumentation  

Energy Technology Data Exchange (ETDEWEB)

In the framework of Sub-Task3 `Wind turbine load measurement instrumentation` of EU-project `European Wind Turbine Testing Procedure Development`, the load measurement techniques have been assessed by laboratory, full scale and numerical tests. The existing methods have been reviewed with emphasis on the strain gage application techniques on composite materials and recommendations are provided for the optimisation of load measurement techniques. (au) EU. 14 refs.

Morfiadakis, E.; Papadopoulos, K. [CRES (Greece); Borg, N. van der [ECN, Petten (Netherlands); Petersen, S.M. [Risoe, Roskilde (Denmark); Seifert, H. [DEWI, Wilhelmshaven (Germany)

1999-03-01

201

Reliability-Based Optimization of Wind Turbines  

DEFF Research Database (Denmark)

Reliability-based optimization of the main tower and monopile foundation of an offshore wind turbine is considered. Different formulations are considered of the objective function including benefits and building and failure costs of the wind turbine. Also different reconstruction policies in case of failure are considered, including systematic reconstruction and failure of the control system. An example is presented, and as a part of the result the optimal reliability level is obtained.

SØrensen, John Dalsgaard; Tarp-Johansen, N.J.

2004-01-01

202

Atmospheric icing on large wind turbine blades  

OpenAIRE

A numerical study of atmospheric ice accretion on a large horizontal axis ‘NREL 5 MW’ wind turbine blade has been carried out using the computational fluid dynamics based technique. Numerical analyses were carried out at five different sections along the wind turbine blade for both rime and glaze ice conditions. Based upon the flow field calculation and the droplet collision efficiency, the rate and shape of accreted ice was simulated at different atmospheric temperatures. Results indicat...

Muhammad S Virk, Matthew C. Homola

2012-01-01

203

Passively cooled direct drive wind turbine  

Science.gov (United States)

A wind turbine is provided that passively cools an electrical generator. The wind turbine includes a plurality of fins arranged peripherally around a generator house. Each of the fins being oriented at an angle greater than zero degrees to allow parallel flow of air over the fin. The fin is further tapered to allow a constant portion of the fin to extend beyond the air stream boundary layer. Turbulence initiators on the nose cone further enhance heat transfer at the fins.

Costin, Daniel P. (Chelsea, VT)

2008-03-18

204

Vertical-axial component wind turbine with a high coefficient using for wind energy  

International Nuclear Information System (INIS)

The report presents the results of research and development on of promising wind units carousel type with a high ratio utilization of wind energy. This devices use a well-known invention – the wind turbine Darrieus. The rotation of the turbine is due to the action of ascensional power to aerodynamic well-streamlined symmetrical about the chord wing profiles of NASA, which are working wind turbine blades. The shaft rotation can be connected with the working blades of one of two ways: using the “swings” or the way “troposkino”. Darrieus turbine has a ratio utilization of wind energy xmax=045. Despite the fact that this is a good indicator of the efficiency of the turbine working, the proposed option allows us to significantly increase the value of this coefficient. The bases methodology of this research is a method of technical and technological research and development design of prospective wind energy construction (WES). Key words: wind turbine, the blade, coefficient utilization of wind energy

205

Preliminary modelling study of ice accretion on wind turbines  

DEFF Research Database (Denmark)

One of the main challenges associated with cold-climate wind energy is icing on wind turbines and a series of icing-induced problems such as production loss, blade fatigue and safety issues. Because of the difficulties with on-site measurements, simulations are often used to understand and predict icing events. In this paper, a new methodology for prediction of icing-induced production loss is proposed, from which the fundamentals of ice accretion on wind turbines can be better understood and the operational production losses can be more reliably predicted. Computational fluid dynamics (CFD) modelling of ice accretion on wind turbines is also performed for different ice events, resulting in a reliable framework for CFD-based ice accretion modelling which is one of the key elements in the new methodology.

Pedersen, Marie Cecilie; Yin, Chungen

2014-01-01

206

Maximum Output Power Tracking of Wind Turbine Using Intelligent Control  

OpenAIRE

The output power of wind turbine is determined by wind speed. The Output power can be adjusted by controlling the generator speed and pitch angle of wind turbine. When the wind speed below the wind turbine rated, the output power of generator can be maximized by controlling the generator speed at point of maximum power coefficient. When the wind speed above the wind turbine rated, output power of wind turbine will exceed the power generators rated. In this condition, the output power of wind ...

Mauridhi Hery Purnomo; Mochamad Ashari; Muldi Yuhendri

2011-01-01

207

Site-optimization of wind turbine generators  

Energy Technology Data Exchange (ETDEWEB)

The Danish Company Nordtank is one of the pioneers within the wind turbine industry. Since 1981 Nordtank has installed worldwide more than 2500 wind turbine generators with a total name plate capacity that is exceeding 450 MW. The opening up of new and widely divergent markets has demanded an extremely flexible approach towards wind turbine construction. The Nordtank product range has expanded considerable in recent years, with the main objective to develop wind energy conversion machines that can run profitable in any given case. This paper will describe site optimization of Nordtank wind turbines. Nordtank has developed a flexible design concept for its WTGs in the 500/750 kW range, in order to offer the optimal WTG solution for any given site and wind regime. Through this flexible design, the 500/750 turbine line can adjust the rotor diameter, tower height and many other components to optimally fit the turbine to each specific project. This design philosophy will be illustrated with some case histories of recently completed projects.

Wolff, T.J. de; Thillerup, J. [Nordtank Energy Group, Richmond, VA (United States)

1997-12-31

208

Birds and wind turbines: can they co-exist?  

International Nuclear Information System (INIS)

The wind farm is situated along an exposed pier at Blyth Harbour and has now been designated as part of a SSI and part of a proposed RAMSAR site. The bird activity within the harbour is high and is also the wintering home of the Purple Sandpiper. An offshore wind farm is proposed for the area, one kilometre from the pier. Two turbines will be erected with the support of the European Commission THERMIE Programme. The bird study at Blyth has been funded by Border Wind, Blyth Harbour Wind Farm Company and the DTI as part of an ETSU funded study. (UK)

209

Flicker Mitigation by Individual Pitch Control of Variable Speed Wind Turbines With DFIG  

DEFF Research Database (Denmark)

Due to the wind speed variation, wind shear and tower shadow effects, grid connected wind turbines are the sources of power fluctuations which may produce flicker during continuous operation. This paper presents a model of an MW-level variable-speed wind turbine with a doubly fed induction generatorto investigate the flicker emission and mitigation issues. An individual pitch control (IPC) strategy is proposed to reduce the flicker emission at different wind speed conditions. The IPC scheme is proposed and the individual pitch controller is designed according to the generator active power and the azimuth angle of the wind turbine. The simulations are performed on the NREL (National Renewable Energy Laboratory) 1.5-MW upwind reference wind turbine model. Simulation results show that damping the generator active power by IPC is an effective means for flicker mitigation of variable speed wind turbines during continuous operation.

Zhang, Yunqian; Chen, Zhe

2014-01-01

210

Wind turbines turbulence effects on cable structures in their vicinity  

OpenAIRE

Actual wind turbines size can be as large as 80 meters diameter (1 MW and over). Behind the wind turbines, mean wind speed is sensibly reduced (approximately 50%) and turbulence severely increased. The spectral density power of disturbed wind can be assumed similar to classical wind but centred on the rotational speed of the motor. Due to classical speed and shape of wind turbine, corresponding key frequency for disturbed wind is close to one Hz. Any structure in the vicinity of wind t...

Lilien, Jean-louis; Keutgen, Renaud; Raimarckers, Nicolas

2001-01-01

211

Behavior of bats at wind turbines.  

Science.gov (United States)

Wind turbines are causing unprecedented numbers of bat fatalities. Many fatalities involve tree-roosting bats, but reasons for this higher susceptibility remain unknown. To better understand behaviors associated with risk, we monitored bats at three experimentally manipulated wind turbines in Indiana, United States, from July 29 to October 1, 2012, using thermal cameras and other methods. We observed bats on 993 occasions and saw many behaviors, including close approaches, flight loops and dives, hovering, and chases. Most bats altered course toward turbines during observation. Based on these new observations, we tested the hypotheses that wind speed and blade rotation speed influenced the way that bats interacted with turbines. We found that bats were detected more frequently at lower wind speeds and typically approached turbines on the leeward (downwind) side. The proportion of leeward approaches increased with wind speed when blades were prevented from turning, yet decreased when blades could turn. Bats were observed more frequently at turbines on moonlit nights. Taken together, these observations suggest that bats may orient toward turbines by sensing air currents and using vision, and that air turbulence caused by fast-moving blades creates conditions that are less attractive to bats passing in close proximity. Tree bats may respond to streams of air flowing downwind from trees at night while searching for roosts, conspecifics, and nocturnal insect prey that could accumulate in such flows. Fatalities of tree bats at turbines may be the consequence of behaviors that evolved to provide selective advantages when elicited by tall trees, but are now maladaptive when elicited by wind turbines. PMID:25267628

Cryan, Paul M; Gorresen, P Marcos; Hein, Cris D; Schirmacher, Michael R; Diehl, Robert H; Huso, Manuela M; Hayman, David T S; Fricker, Paul D; Bonaccorso, Frank J; Johnson, Douglas H; Heist, Kevin; Dalton, David C

2014-10-21

212

Load prediction of stall regulated wind turbines  

Energy Technology Data Exchange (ETDEWEB)

Measurements of blade loads on a turbine situated in a small wind farm shows that the highest blade loads occur during operation close to the peak power i.e. when the turbine operates in the stall region. In this study the extensive experimental data base has been utilised to compare loads in selected campaigns with corresponding load predictions. The predictions are based on time domain simulations of the wind turbine structure, performed by the aeroelastic code VIDYN. In the calculations a model were adopted in order to include the effects of dynamic stall. This paper describes the work carried out so far within the project and key results. 5 refs, 10 figs

Bjoerck, A.; Dahlberg, J.Aa. [Aeronautical Research Inst. of Sweden, Bromma (Sweden); Carlen, I. [Chalmers Univ. of Technology, Goeteborg (Sweden). Div. of Marine Structural Engineering; Ganander, H. [Teknikgruppen AB, Sollentua (Sweden)

1996-12-01

213

Verification of European wind turbine design codes  

Energy Technology Data Exchange (ETDEWEB)

Results of the EU-JOULE project Verification of European Wind Turbine Design Codes, VEWTDC are reported. In this project a verification is performed of eight wind turbine codes from five different European countries Code predictions of mechanical loads (blade loads, rotor loads, tower loads) have been compared with measurements on three different turbines, obtained at different conditions (normal operating conditions and special events). The paper describes the working procedure, a global description of the different codes and a selection of results. Emphasis is put on the problems which have to be faced when trying to translate the differences between calculations and measurement to design inaccuracies.

Schepers, J.G.; Heijdra, J.J. [ECN Wind, Petten (Netherlands); Thomsen, K.; Larsen, T. [Risoe, Roskilde (Denmark); Foussekis, D. [CRES, Attiki (Greece); Rawlinson Smith, R. [Garrad Hassan, Bristol (United Kingdom); Kraan, I.; Visser, B. [Stork Product Engineering SPE, Amsterdam (Netherlands); Oye, S. [DTU, Lyngby (Denmark); Ganander, H.; Carlen, I. [Teknikgruppen AB, Sollentuna (Sweden); Voutsinas, S.; Belessis, M. [National Technical University of Athens, Athens (Greece); Drost, L. [Lagerwey, Barneveld (Netherlands)

2001-09-01

214

Innovative multi rotor wind turbine designs  

Energy Technology Data Exchange (ETDEWEB)

Among the renewable energy sources, today wind energy is the most recognized and cost effective. Developers and researchers in this sector are optimistic and continuously working innovatively to improve the technology. The wind power obtained is proportional to the swept area of wind turbine. The swept area is increased by using a single rotor of large diameter or multi rotors in array. The rotor size is growing continuously with mature technology. Multi rotor technology has a long history and the multi rotor concept persists in a variety of modern innovative systems but the concept has fallen out of consideration in mainstream design from the perception that is complex and unnecessary as very large single rotor units are now technically feasible. This work addresses the evaluation of different multi rotor wind turbine systems. These innovative wind turbines are evaluated on the basis of feasibility, technological advantages, security of expected power performance, cost, reliability, impact of innovative system, comparison with existing wind turbine design. The findings of this work will provide guidelines for the practical and economical ways for further research on the multi rotor wind turbines. (Author)

Kale, S.A.; Sapali, S.N. [College of Engineering. Mechanical Engineering Dept, Pune (India)

2012-07-01

215

Anechoic wind tunnel study of turbulence effects on wind turbine broadband noise  

Science.gov (United States)

This paper describes recent results obtained at MIT on the experimental and theoretical modelling of aerodynamic broadband noise generated by a downwind rotor horizontal axis wind turbine. The aerodynamic broadband noise generated by the wind turbine rotor is attributed to the interaction of ingested turbulence with the rotor blades. The turbulence was generated in the MIT anechoic wind tunnel facility with the aid of biplanar grids of various sizes. The spectra and the intensity of the aerodynamic broadband noise have been studied as a function of parameters which characterize the turbulence and of wind turbine performance parameters. Specifically, the longitudinal integral scale of turbulence, the size scale of turbulence, the number of turbine blades, and free stream velocity were varied. Simultaneous measurements of acoustic and turbulence signals were made. The sound pressure level was found to vary directly with the integral scale of the ingested turbulence but not with its intensity level. A theoretical model based on unsteady aerodynamics is proposed.

Loyd, B.; Harris, W. L.

1995-05-01

216

Anechoic wind tunnel study of turbulence effects on wind turbine broadband noise  

Science.gov (United States)

This paper describes recent results obtained at MIT on the experimental and theoretical modelling of aerodynamic broadband noise generated by a downwind rotor horizontal axis wind turbine. The aerodynamic broadband noise generated by the wind turbine rotor is attributed to the interaction of ingested turbulence with the rotor blades. The turbulence was generated in the MIT anechoic wind tunnel facility with the aid of biplanar grids of various sizes. The spectra and the intensity of the aerodynamic broadband noise have been studied as a function of parameters which characterize the turbulence and of wind turbine performance parameters. Specifically, the longitudinal integral scale of turbulence, the size scale of turbulence, the number of turbine blades, and free stream velocity were varied. Simultaneous measurements of acoustic and turbulence signals were made. The sound pressure level was found to vary directly with the integral scale of the ingested turbulence but not with its intensity level. A theoretical model based on unsteady aerodynamics is proposed.

Loyd, B.; Harris, W. L.

1995-01-01

217

Jet spoiler arrangement for wind turbine  

Science.gov (United States)

An air jet spoiler arrangement is provided for a Darrieus-type vertical axis wind-powered turbine. Air is drawn into hollow turbine blades through air inlets at the end thereof and is ejected in the form of air jets through small holes or openings provided along the lengths of the blades. The air jets create flow separation at the surfaces of the turbine blades, thereby including stal conditions and reducing the output power. A feedback control unit senses the power output of the turbine and controls the amount of air drawn into the air inlets accordingly.

Cyrus, J. D.; Kablec, E. G.; Klimas, P. C.

1983-09-01

218

Voltage Recovery of Grid-Connected Wind Turbines with DFIG After a Short-Circuit Fault  

DEFF Research Database (Denmark)

The fast development of wind power generation brings new requirements for wind turbine integration to the network. After clearance of an external short-circuit fault, the voltage at the wind turbine terminal should be re-established with minimized power losses. This paper concentrates on voltage recovery of variable speed wind turbines with doubly fed induction generators (DFIG). A simulation model of a MW-level variable speed wind turbine with a DFIG developed in PSCAD/EMTDC is presented, and the control and protection schemes are described. A new control strategy is proposed to re-establish the wind turbine terminal voltage after the clearance of an external short-circuit fault, and the restore the normal operation of the variable speed wind turbine with DFIG, which has been demonstrated by simulation results.

Sun, Tao; Chen, Zhe

2004-01-01

219

Power electronics for modern wind turbines  

CERN Document Server

Wind energy is now the world's fastest growing energy source. In the past 10 years, the global wind energy capacity has increased rapidly. The installed global wind power capacity has grown to 47.317 GW from about 3.5 GW in 1994. The global wind power industry installed 7976 MW in 2004, an increase in total installed generating capacity of 20%. The phenomenal growth in the wind energy industry can be attributed to the concerns to the environmental issues, and research and development of innovative cost-reducing technologies.Denmark is a leading producer of wind turbines in the world, with an a

Blaabjerg, Frede

2006-01-01

220

Robust, Gain-Scheduled Control of Wind Turbines  

OpenAIRE

Wind turbines are today large and efficient machines, which are combined into wind farms operating on par with conventional power plants. When looking back, this is significantly different from the status only a few years ago, when wind turbines were sold mainly to private people. This change in turbine owners has resulted in a new focus on operational reliability instead of turbine size. This research deals with investigating model-based gain-scheduling control of wind turbines by use of lin...

Østergaard, Kasper Zinck

2008-01-01

221

Wind power integration: from individual wind turbine to wind park as a power plant:  

OpenAIRE

As power capacities of single wind turbine, single wind park and total wind power installation are continuously increasing, the wind power begins to challenge the safety operation of the power system. This thesis focuses on the grid integration aspects such as the dynamic behaviours of wind power during disturbances, and dynamic behaviours of power system with large wind power integration. The work in this thesis is in a down-up approach, starting with concepts for individual wind turbines, i...

Zhou, Y.

2009-01-01

222

Vertical axis wind turbine control strategy  

Energy Technology Data Exchange (ETDEWEB)

Early expensive in automatic operation of the Sandia 17-m vertical axis research wind turbine (VAWT) has demonstrated the need for a systematic study of control algorithms. To this end, a computer model has been developed that uses actual wind time series and turbine performance data to calculate the power produced by the Sandia 17-m VAWT operating in automatic control. The model has been used to investigate the influence of starting algorithms on annual energy production. The results indicate that, depending on turbine and local wind characteristics, a bad choice of a control algorithm can significantly reduce overall energy production. The model can be used to select control algorithms and threshold parameters that maximize long-term energy production. An attempt has been made to generalize these results from local site and turbine characteristics to obtain general guidelines for control algorithm design.

McNerney, G.M.

1981-08-01

223

Environmental life cycle analyses of wind turbines  

International Nuclear Information System (INIS)

The aim of this investigation is to determine environmental aspects of (1) upscaling of both onshore and offshore turbines and (2) offshore versus onshore placement of turbines. Attention has also been paid to a couple of waste processing options in order to obtain a responsible disposal of dismissed wing blades of wind turbines. Shortcomings of the followed procedure for life cycle assessments are pinpointed in the field of the software package, the inventory and the normalization of effect scores both for classification and evaluation. Upscaling from a 300 kW wind turbine to a 500 kW wind turbine results in a decrease (20-50%) of all environmental impacts considered in this study both for an onshore and an offshore situation. This is caused by the fact that the increase of materials use turns out to be lower than the increase in energy production. However, smaller differences than assumed in this study in electricity production between the two types of wind turbines - depending on wind climate and design - will result in a lower decrease or even an increase in environmental impacts. Offshore placement leads to considerably higher environmental impacts compared to onshore placement (5-180%). However, offshore placement offers important advantages in the field of noise pollution, adverse effect on landscape and level of electricity production. 11 figs., 25 tabs., 41 refs

224

Effects of wind direction and wind farm layout on turbine wakes and power losses in wind farms: An LES study  

Science.gov (United States)

A recently-developed large-eddy simulation (LES) framework is validated and used to investigate the effects of wind direction and wind farm layout on the turbine wakes and power losses in wind farms. The subgrid-scale (SGS) turbulent stress is parameterized using a tuning-free Lagrangian scale-dependent dynamic SGS model. The turbine-induced forces are computed using a dynamic actuator-disk model with rotation (ADM-R), which couples blade-element theory with a turbine-specific relation between the blade angular velocity and the shaft torque to compute simultaneously turbine angular velocity and power output. Here, we choose the Horns Rev offshore wind farm as a case study for model validation. A series of simulations are performed for a wide range of wind direction angles. Results from the simulations are in good agreement with observed power data from the Horns Rev wind farm, and show a strong impact of wind direction on the farm power production and the spatial distribution of turbine-wake characteristics (e.g., velocity deficit and turbulence intensity). This can be explained by the fact that changing the wind angle can be viewed as changing the wind farm layout relative to the incoming wind, while keeping the same wind turbine density. To further investigate the effect of wind farm layout on the flow and the power extracted by the farm, simulations of wind farms with different circular and elliptic layouts are performed to compare with the results of the Horns Rev wind farm simulations. The results show that the proposed layouts not only provide more stable power output with different wind directions, but also enhance the performance of the total farm power production.

Wu, Yu-Ting; Porté-Agel, Fernando

2014-05-01

225

Slotted Blades Savonius Wind Turbine Analysis by CFD  

Directory of Open Access Journals (Sweden)

Full Text Available In this paper a new bucket configuration for a Savonius wind generator is proposed. Numerical analyses are performed to estimate the performances of the proposed configuration by means of the commercial code COMSOL Multiphysics® with respect to Savonius wind turbine with overlap only. Parametric analyses are performed, for a fixed overlap ratio, by varying the slot position; the results show that for slot positioned near the blade root, the Savonius rotor improves performances at low tip speed ratio, evidencing a better starting torque. This circumstance is confirmed by static analyses performed on the slotted blades in order to investigate the starting characteristic of the proposed Savonius wind generator configuration.

Andrea Alaimo

2013-12-01

226

Wind Turbine Test Wind Matic WM 15S  

OpenAIRE

The report describes standard measurements performed on a Wind-Matic WM 15S, 55 kW wind turbine. The measurements carried out and reported here comprises the power output, system efficiency, energy production, transmission efficiency, rotor power, rotor efficiency, air-brakes efficiency, dynamical behaviour of the turbine, loads at cut-in and braking, rotor torque at stopped condition, and noise emission.

Friis Pedersen, Troels

1986-01-01

227

The social acceptability of wind turbines: some resident are ready to pay to keep their wind turbines. Survey on four French wind farms  

International Nuclear Information System (INIS)

The authors report a study which aimed at exploiting and deepening the results of a 2001 survey on visual and sound disturbances caused by wind turbines in Sigean (Aude), at identifying all the attitudes and opinions with respect with wind energy, and at assessing the different characteristics of a wind farm (height, localization, and so on). A survey has been performed on four sites located in different French regions. The authors discuss the social-demographic characteristics of the population samples, the global opinion on wind energy, and the opinion of the people on wind turbines located in their neighbourhood. They propose an estimation of benefits and damages related to the vicinity of wind turbines. By applying a method of choice experiments, they reveal the preferences of residents

228

Field verification program for small wind turbines  

Energy Technology Data Exchange (ETDEWEB)

In 1999 Windward Engineering (Windward) was awarded a Cooperative Agreement under the Field Verification Program with the Department of Energy (DOE) to install two Whisper H40 wind turbines, one at the NREL National Wind Technology Center (NWTC) and one at a test site near Spanish Fork, Utah. After installation, the turbine at the NWTC was to be operated, maintained, and monitored by NREL while the turbine in Spanish Fork was to be administered by Windward. Under this award DOE and Windward defined the primary objectives of the project as follows: (1) Determine and demonstrate the reliability and energy production of a furling wind turbine at a site where furling will be a very frequent event and extreme gusts can be expected during the duration of the tests. (2) Make engineering measurements and conduct limited computer modeling of the furling behavior to improve the industry understanding of the mechanics and nature of furling. We believe the project has achieved these objectives. The turbine has operated for approximately three and a half years. We have collected detailed engineering data approximately 75 percent of that time. Some of these data were used in an ADAMS model validation that highlighted the accuracies and inaccuracies of the computer modeling for a passively furling wind turbine. We also presented three papers at the American Wind Energy Association (AWEA) Windpower conferences in 2001, 2002, and 2003. These papers addressed the following three topics: (a) general overview of the project [1], (b) furling operation during extreme wind events [2], and (c) extrapolation of extreme (design) loads [3]. We believe these papers have given new insight into the mechanics and nature of furling and have set the stage for future research. In this final report we will highlight some of the more interesting aspects of the project as well as summarize the data for the entire project. We will also present information on the installation of the turbines as well as the findings from the post-test inspection of the turbine.

Windward Engineering, LLC

2003-11-30

229

Wind turbines - localisation strategy in Denmark  

International Nuclear Information System (INIS)

Sites for 1500 MW wind power in Denmark by 2005 will be found through a decentralized planning process with public participation. The wind turbines will be sited in parks and clusters in order to secure good economy and satisfactory locations in the landscape. (author)

230

Dynamic Stall Model for Wind Turbine Airfoils  

DEFF Research Database (Denmark)

 A model is presented for aerodynamic lift of wind turbine profiles under dynamic stall. The model combines memory delay effects under attached flow with reduced lift due to flow separation under dynamic stall conditions. The model is based on a backbone curve in the form of the static lift as a function of the angle of attack. The static lift is described by two parameters, the lift at fully attached flow and the degree of attachment. A relationship between these parameters and the static lift is available from a thin plate approximation. Assuming the parameters to be known during static conditions, nonstationary effects are included by three mechanisms: a delay of the lift coefficient of fully attached flow via a second-order filter, a delay of the development of separation represented via a first-order filter, and a lift contribution due to leading edge separation also represented via a first-order filter. The latter is likely to occur during active pitch control of vibrations. It is shown that all included effects can be important when considering wind turbine blades. The proposed model is validated against test data from two load cases, one at fully attached flow conditions and one during dynamic stall conditions. The proposed model is compared with five other dynamic stall models including, among others, the Beddoes-Leishman model and the ONERA model. It is demonstrated that the proposed model performs equally well or even better than more complicated models and that the included nonstationary effects are essential for obtaining satisfactory results. Finally, the influence of camber and thickness distribution on the backbone curve are analysed. It is shown that both of these effects are adequately accounted for via the static input data.

Larsen, Jesper Winther; Nielsen, SØren R.K.

2007-01-01

231

Vortex system studies on small wind turbines  

Energy Technology Data Exchange (ETDEWEB)

The wind tunnel experiment reported included a small wind turbine setup and smoke to visualize the trailing tip vortices for different wind turbine configurations. Several combinations of tunnel wind speeds and tip speed ratios generated a database where the end result functions were radius and pitch, of the tip vortex spirals, versus the downstream coordinate. The Reynolds number in the experiment was very low compared to that of full size turbines. The results should therefore be seen as valid only for low Reynolds numbers. The models were 18 and 25 cm diameter turbines. This is thought to be complementary to the information obtained in similar wind tunnel investigations for much larger models. The database is meant to be a fundamental tool for the construction of practical aerodynamic induction methods. Such methods typically employ the Biot-Savart law has been shown to lead to a flow field, which deviates considerably from that of reality. E.g. concentration into tip vortices does not happen when the flow is simulated with Biot-Savart law only. Thus, a combination of the induction method and its modification, based on investigations such as the one reported, is foreseen to replace the widely used Blade Element Momentum method for wind turbine loads and performance prediction.

Montgomerie, Bjoern; Dahlberg, Jan-Aake [Swedish Defence Research Agency, Stockholm (Sweden). Div. of Aeronautics, FFA

2003-10-01

232

Fatigue Reliability of Offshore Wind Turbine Systems  

DEFF Research Database (Denmark)

Optimization of the design of offshore wind turbine substructures with respect to fatigue loads is an important issue in offshore wind energy. A stochastic model is developed for assessing the fatigue failure reliability. This model can be used for direct probabilistic design and for calibration of appropriate partial safety factors / fatigue design factors (FDF) for steel substructures of offshore wind turbines (OWTs). The fatigue life is modeled by the SN approach. Design and limit state equations are established based on the accumulated fatigue damage. The acceptable reliability level for optimal fatigue design of OWTs is discussed and results for reliability assessment of typical fatigue critical design of offshore steel support structures are presented.

Marquez-Dominguez, Sergio; SØrensen, John Dalsgaard

2012-01-01

233

Variable diameter wind turbine rotor blades  

Science.gov (United States)

A system and method for changing wind turbine rotor diameters to meet changing wind speeds and control system loads is disclosed. The rotor blades on the wind turbine are able to adjust length by extensions nested within or containing the base blade. The blades can have more than one extension in a variety of configurations. A cable winching system, a hydraulic system, a pneumatic system, inflatable or elastic extensions, and a spring-loaded jack knife deployment are some of the methods of adjustment. The extension is also protected from lightning by a grounding system.

Jamieson, Peter McKeich; Hornzee-Jones, Chris; Moroz, Emilian M.; Blakemore, Ralph W.

2005-12-06

234

A wind turbine evaluation model under a multi-criteria decision making environment  

International Nuclear Information System (INIS)

Highlights: ? This paper proposes an evaluation model to select suitable turbines in a wind farm. ? Interpretive structural modeling is used to know the relationship among factors. ? Fuzzy analytic network process is used to calculate the priorities of turbines. ? The results can be references for selecting the most appropriate wind turbines. - Abstract: Due to the impacts of fossil and nuclear energy on the security, economics, and environment in the world, the demand of alternative energy resources is expanding consistently and tremendously in recent years. Wind energy production, with its safe and environmental characteristics, has become the fastest growing renewable energy source in the world. The construction of new wind farms and the installation of new wind turbines are important processes in order to provide a long-term energy production. In this research, a comprehensive evaluation model, which incorporates interpretive structural modeling (ISM) and fuzzy analytic network process (FANP), is constructed to select suitable turbines when developing a wind farm. A case study is carried out in Taiwan in evaluating the expected performance of several potential types of wind turbines, and experts in a wind farm are invited to contribute their expertise in determining the importance of the factors of the wind turbine evaluation and in rating the performance of the turbines with respect to each factor. The most suitable turbines for installation can finally bnes for installation can finally be generated after the calculations. The results can be references for decision makers in selecting the most appropriate wind turbines.

235

Power Electronics for the Next Generation Wind Turbine System  

DEFF Research Database (Denmark)

The wind power generation has been steadily growing both for the total installed capacity and for the individual turbine size. Due to much more significant impacts to the power grid, the power electronics, which can change the behavior of wind turbines from an unregulated power source to an active generation unit, are becoming crucial in the wind turbine system. The objective of this project is to study the power electronics technology used for the next generation wind turbines. Some emerging challenges as well as potentials like the cost of energy and reliability are going to be addressed. First several potential converter topologies and power semiconductor devices for the future wind power application are presented in respect to the advantages/drawbacks. And then the criteria for evaluating the wind power converter are generally discussed, where the importance of thermal stress in the power semiconductors is emphasized and a multidisciplinary approach for the stress analysis is introduced. Based on the proposed criteria and tools, the electrical and thermal behaviors of wind power converters are investigated under both normal and fault conditions, where the factors of wind speeds, grid codes, converter controls and grid conditions are taken into account. In order to relieve the electrical and thermal stress of the converter in wind turbine system, some new control methods and concepts are thereby proposed. In Chapter 4 a thermal control concept which utilizes the reactive power is used to stabilize the thermal excursion under wind gust. In Chapter 5 a series of special modulation methods which can achieve better thermal loading of power devices under grid faults are introduced. Also in Chapter 5 a series of power control strategies utilizing the zero sequence current are presented to achieve better control performance under the unbalanced AC source. It is concluded that power electronics will play more important role and regulate all the generated power in the next generation wind turbine system. In this case, the stress in the converter components becomes more critical because the power conversion is pushed to multi-MW level with high power density requirement. It has also been revealed that thermal stress in the power semiconductors is closely related to many determining factors in the wind power application like the reliability, cost, power density, etc. therefore it is an important performance for the next generation wind power converter. It is found that the thermal behaviors of wind power converter could be rather adverse under some required operating conditions. On the other hand it is also possible to improve the thermal behaviors by many aspects like the smart control, special modulation, advanced modeling, as well as new converter designs.

Ma, Ke

2013-01-01

236

Load attenuating passively adaptive wind turbine blade  

Science.gov (United States)

A method and apparatus for improving wind turbine performance by alleviating loads and controlling the rotor. The invention employs the use of a passively adaptive blade that senses the wind velocity or rotational speed, and accordingly modifies its aerodynamic configuration. The invention exploits the load mitigation prospects of a blade that twists toward feather as it bends. The invention includes passively adaptive wind turbine rotors or blades with currently preferred power control features. The apparatus is a composite fiber horizontal axis wind-turbine blade, in which a substantial majority of fibers in the blade skin are inclined at angles of between 15 and 30 degrees to the axis of the blade, to produces passive adaptive aeroelastic tailoring (bend-twist coupling) to alleviate loading without unduly jeopardizing performance.

Veers, Paul S. (Albuquerque, NM); Lobitz, Donald W. (Albuquerque, NM)

2003-01-01

237

Wind Turbine Micropitting Workshop: A Recap  

Energy Technology Data Exchange (ETDEWEB)

Micropitting is a Hertzian fatigue phenomenon that affects many wind turbine gearboxes, and it affects the reliability of the machines. With the major growth and increasing dependency on renewable energy, mechanical reliability is an extremely important issue. The U.S. Department of Energy has made a commitment to improving wind turbine reliability and the National Renewable Energy Laboratory (NREL) has started a gearbox reliability project. Micropitting as an issue that needed attention came to light through this effort. To understand the background of work that had already been accomplished, and to consolidate some level of collective understanding of the issue by acknowledged experts, NREL hosted a wind turbine micropitting workshop, which was held at the National Wind Technology Center in Boulder, Colorado, on April 15 and 16, 2009.

Sheng, S.

2010-02-01

238

Computer control for remote wind turbine operation  

Energy Technology Data Exchange (ETDEWEB)

Light weight wind turbines located in harsh, remote sites require particularly capable controllers. Based on extensive operation of the original ESI-807 moved to such a location, a much more sophisticated controller than the original one has been developed. This paper describes the design, development and testing of that new controller. The complete control and monitoring system consists of sensor and control inputs, the control computer, control outputs, and additional equipment. The control code was written in Microsoft Visual Basic on a PC type computer. The control code monitors potential faults and allows the turbine to operate in one of eight states: off, start, run, freewheel, low wind shut down, normal wind shutdown, emergency shutdown, and blade parking. The controller also incorporates two {open_quotes}virtual wind turbines,{close_quotes} including a dynamic model of the machine, for code testing. The controller can handle numerous situations for which the original controller was unequipped.

Manwell, J.F.; Rogers, A.L.; Abdulwahid, U.; Driscoll, J. [Univ. of Massachusetts, Amherst, MA (United States)

1997-12-31

239

Vertical Axis Wind Turbines : Electrical System and Experimental Results  

OpenAIRE

The wind power research at the division of Electricity at Uppsala University is aimed towards increased understanding of vertical axis wind turbines. The considered type of wind turbine is an H-rotor with a directly driven synchronous generator operating at variable speed. The experimental work presented in this thesis comprises investigation of three vertical axis wind turbines of different design and size. The electrical, control and measurement systems for the first 12 kW wind turbine have...

Kjellin, Jon

2012-01-01

240

A neuro-fuzzy controlling algorithm for wind turbine  

Energy Technology Data Exchange (ETDEWEB)

The wind turbine control system is stochastic and nonlinear, offering a demanding field for different control methods. An improved and efficient controller will have great impact on the cost-effectiveness of the technology. In this article, a design method for a self-organizing fuzzy controller is discussed, which combines two popular computational intelligence techniques, neural networks and fuzzy logic. Based on acquisited dynamic parameters of the wind, it can effectively predict wind changes in speed and direction. Maximum power can always be extracted from the kinetic energy of the wind. Based on the stimulating experiments applying nonlinear dynamics to a `Variable Speed Fixed Angle` wind turbine, it is demonstrated that the proposed control model 3rd learning algorithm provide a predictable, stable and accurate performance. The robustness of the controller to system parameter variations and measurement disturbances is also discussed. (author)

Li Lin [Tampere Univ. of Technology (Finland); Eriksson, J.T. [Tampere Univ. of Technology (Finland)

1995-12-31

241

Failure Probability Estimation of Wind Turbines by Enhanced Monte Carlo  

DEFF Research Database (Denmark)

This paper discusses the estimation of the failure probability of wind turbines required by codes of practice for designing them. The Standard Monte Carlo (SMC) simulations may be used for this reason conceptually as an alternative to the popular Peaks-Over-Threshold (POT) method. However, estimation of very low failure probabilities with SMC simulations leads to unacceptably high computational costs. In this study, an Enhanced Monte Carlo (EMC) method is proposed that overcomes this obstacle. The method has advantages over both POT and SMC in terms of its low computational cost and accuracy. The method is applied to a low-order numerical model of a 5 MW wind turbine with a pitch controller exposed to a turbulent inflow. Two cases of the wind turbine model are investigated. In the first case, the rotor is running with a constant rotational speed. In the second case, the variable rotational speed is controlled by the pitch controller. This provides a fair framework for comparison of the behavior and failure event of the wind turbine with emphasis on the effect of the pitch controller. The Enhanced Monte Carlo method is then applied to the model and the failure probabilities of the model are estimated to the values related to the required 50-year return period of the wind turbine.

Sichani, Mahdi Teimouri; Nielsen, SØren R.K.

2012-01-01

242

Grid impact of variable-speed wind turbines  

Energy Technology Data Exchange (ETDEWEB)

In this paper the power quality of variable-speed wind turbines equipped with forced-commutated inverters is investigated. Measurements have been taken on the same type of variable-speed wind turbines in Germany and Sweden. The measurements have been analysed according to existing IEC standards. Special attention has been paid to the aggregation of several wind turbines on flicker emission and harmonics. The aggregation has been compared with the summation laws used in the draft IEC 61400-21 `Power Quality Requirements for Grid Connected wind turbines`. The methods for calculating and summing flicker proposed by IEC Standards are reliable. Harmonics and inter-harmonics are treated in IEC 61000-4-7 and IEC 61000-3-6. The methods for summing harmonics and inter-harmonics in IEC 61000-3-6 are applicable to wind turbines. In order to obtain a correct magnitude of the frequency components, the use of a well-defined window width, according to IEC 61000-4-7 Amendment 1 is of a great importance. (au)

Larsson, Aa. [Chalmers Univ. of Technology, Dept. of Electric Power Engineering, Goeteborg (Sweden); Soerensen, P. [Risoe National Lab., Roskilde (Denmark); Santjer, F. [German Wind Energy Inst., DEWI, Wilhelmshaven (Germany)

1999-03-01

243

Study on optimal design of wind turbine blade airfoil and its application  

International Nuclear Information System (INIS)

This study was carried out with two goals. One was the development of a model of a wind turbine blade airfoil and the other was the application of the folding blade. In general, in large sized (MW) wind turbines, damage is prevented in small wind turbines since equipment costs and maintenance costs are high, and therefore, the blade will cause serious damage. The wind turbine proposed in this study does not require maintenance, and the blades do not break during high winds because they are folded in accordance with changes in the wind speed. But generators are not cut out, while maintaining a constant angle will continue to produce. The focus of this study, the wind turbine is continued by folding blade system in strong winds and gusts without stopping production

244

The design of wind turbine for electrical power generation in Malaysian wind characteristics  

International Nuclear Information System (INIS)

The paper describes the study of a wind turbine for electrical power generation in Malaysia wind characteristics. In this research, the wind turbine is designs based on the local wind characteristics and tries to avoid the problems faced in the past (turbine design, access, manpower and technical). The new wind turbine rotor design for a medium speed wind speed turbine utilises the concept of open-close type of horizontal axis (up-wind) wind turbine is intended to widen the optimum performance range for electrical generation in Malaysia wind characteristics. The wind turbine has been designed to cut-in at a lower speed, and to provide the rotation speed that high enough to run a generator. The analysis and design of new low speed wind turbine blades and open-close turbine rotor and prediction of turbine performance are being detailed in this paper. (Author)

245

Aspects in Formulating Mathematical Model of Wind Turbine  

Directory of Open Access Journals (Sweden)

Full Text Available The present paper explores the mathematical molding of the wind turbine and its influence on the subsequent stages. Specifically, the paper investigate the modeling of gear train of the wind turbine and distinguishes the difference in the approaches usually used to establish the mathematical model which is later has a significant impact on the design, characteristic and performance of the modeled system. Mainly two commonly used approached for the gear train systems are analyzed and discussed.  The main well know mechanisms are investigated in term of the most proposed assumptions to deal with the damping, shaft stiffness and inertia effect of the gear. This paper elucidates these concerns??????: ???, ????, ?????, ?? ?????, ?? ????, ????, ????, ????

Waleed Khalil Ahmed

2013-06-01

246

Observer Backstepping Control for Variable Speed Wind Turbine  

DEFF Research Database (Denmark)

This paper presents an observer backstepping controller as feasible solution to variable speed control of wind turbines to maximize wind power capture when operating between cut-in and rated wind speeds. The wind turbine is modeled as a two-mass drive-train system controlled by the generator torque. The nonlinear controller aims at regulating the generator torque such that an optimal tip-speed ratio can be obtained. Simply relying on the measured rotor angular velocity the proposed observer backstepping controller guarantees global asymptotic tracking of the desired trajectory while maintaining a globally uniformly ultimately bounded torsional angle. The proposed controller shows convincing performance when simulated in closed loop within a stochastic environment.

Galeazzi, Roberto; Gryning, Mikkel Peter Sidoroff

2013-01-01

247

Overcoming icing effects on wind turbines  

Energy Technology Data Exchange (ETDEWEB)

Wind turbine blades in the Whitehorse area are often subjected to rime icing. High energy winds on ridges, hilltops and mountains result in cloud and rime ice formation. Reliable models and detectors for rime and glaze icing are needed in order to measure the duration and severity of icing. Currently, there is a limited supply of good models on the market, and they do not appear to cope well with severe rime icing. A two heated anemometer approach appears to be reasonably reliable. This paper describes a wind speed and icing event monitoring study at Haeckel Hill in which the performance of an iced turbine was compared with the performance of an ice-free turbine. Technological advancement in the area of blade icing include: the development of low temperature synthetic lubricants and fluids; heated wind instruments and ultrasonics; after-market blade heating systems and blade coatings; and, reductions in energy losses. The challenges that still need to be addressed include: ice detection for severe conditions; off-the-shelf blade heating systems; further reductions in energy losses; and, adaptations of turbine control algorithms. The paper includes a list of manufacturers who are working on equipment for use in cold/icing environments. The large turbine manufacturers include Vestas, Bonus, NEG Micon, Enercon, and Lagerwey. The small turbine manufacturers include Atlantic Orient, Vergnet, Northern Power Systems, and Bergey. 10 figs.

Maissan, J. [Yukon Energy Corp., Whitehorse, YT (Canada)

2003-07-01

248

Grid integration impacts on wind turbine design and development  

DEFF Research Database (Denmark)

This paper presents an overall perspective on contemporary issues like wind power plants and grid integration. The purpose is to present and discuss the impacts of emerging new grid connection requirements on modern wind turbines. The grid integration issue has caused several new challenges to the wind turbine design and development. The survival of different wind turbine concepts and controls is strongly conditioned by their ability to comply with stringent grid connection requirements, imposed by utility companies. Beside its impact on the mechanical design and control of wind turbines, the grid integration aspect has also an effect on wind turbines' role in the power system, on wind turbine technologies' survival on the market, as well as on the wind turbines' loads. Over the last years, it became obviously, that there it is an increasing need for design and research of wind turbines based on an integrated design and control approach. © 2009 IEEE.

Hansen, Anca D.; Cutululis, Nicolaos Antonio

2009-01-01

249

Atmospheric stability affects wind turbine power collection  

International Nuclear Information System (INIS)

The power generated by a wind turbine largely depends on the wind speed. During time periods with identical hub-height wind speeds but different shapes to the wind profile, a turbine will produce different amounts of power. This variability may be induced by atmospheric stability, which affects profiles of mean wind speed, direction and turbulence across the rotor disk. Our letter examines turbine power generation data, segregated by atmospheric stability, in order to investigate power performance dependences at a West Coast North American wind farm. The dependence of power on stability is clear, regardless of whether time periods are segregated by three-dimensional turbulence, turbulence intensity or wind shear. The power generated at a given wind speed is higher under stable conditions and lower under strongly convective conditions: average power output differences approach 15%. Wind energy resource assessment and day ahead power forecasting could benefit from increased accuracy if atmospheric stability impacts were measured and appropriately incorporated in power forecasts, e.g., through the generation of power curves based on a range of turbulence regimes. (letter)

250

Methods and apparatus for reducing peak wind turbine loads  

Science.gov (United States)

A method for reducing peak loads of wind turbines in a changing wind environment includes measuring or estimating an instantaneous wind speed and direction at the wind turbine and determining a yaw error of the wind turbine relative to the measured instantaneous wind direction. The method further includes comparing the yaw error to a yaw error trigger that has different values at different wind speeds and shutting down the wind turbine when the yaw error exceeds the yaw error trigger corresponding to the measured or estimated instantaneous wind speed.

Moroz, Emilian Mieczyslaw

2007-02-13

251

Assessment and prediction of wind turbine noise  

International Nuclear Information System (INIS)

The significance of basic aerodynamic noise sources for wind turbine noise are assessed, using information on the aero-acoustic mechanisms of other rotors, which have been studied in depth for many years. From the analysis, areas of potential improvement in wind turbine noise prediction are defined. Suggestions are made for approaches to wind turbine noise control which separate the noise problems at cut-in from those at rated power. Some of these offer the possibility of noise reduction without unfavourable effects on performance. Based on this analysis, a new model for prediction of wind turbine noise is presented and comparisons made between prediction and experiment. The model is based on well established aeroacoustic theory and published laboratory data for the two principal sources, inflow turbulence and boundary layer trailing edge interaction. The new method gives good agreement with experiment with the case studied so far. Parametric trends and sensitivities for the model are presented. Comparisons with previous prediction methods are also given. A consequence of the new model is to put more emphasis on boundary layer trailing edge interaction as a noise source. There are prospects for reducing noise from this source detail changes to the wind turbine design. (author)

252

The control of variable-speed wind turbine generators  

Science.gov (United States)

The problem of smooth control of electrical power from a large wind turbine generator to an electrical utility system grid is discussed. A control system is proposed which is applicable to either induction or synchronous machines asynchronously coupled to the grid through a controllable dc current link. A power limiting strategy is developed which spills powers at high wind velocities without recourse to blade pitch control mechanisms.

Lyons, J. P., Jr.; Thomas, R. J.

253

Mitigation of Fatigue Loads Using Individual Pitch Control of Wind Turbines Based on FAST  

DEFF Research Database (Denmark)

With the increase of wind turbine dimension and capacity, the wind turbine structures are subjected to prominent loads and fatigue which would reduce the lifetime of wind turbines. Individual pitch control (IPC) is used in this paper to attenuate the blade root bending moment and the tilt and yaw moments and fatigue. The loading transfer from rotational coordinate system to the fixed coordinate system of the wind turbine is analyzed. In order to make the simulation results more reliable, the wind turbine code FAST is applied to doubly fed induction generator (DFIG) based power system to demonstrate the correctness of individual pitch control strategy. The performance of the proposed control method is tested and compared with that using collective pitch control (CPC), demonstrating the effectiveness of individual pitch control of wind turbines.

Zhang, Yunqian; Chen, Zhe

2011-01-01

254

Wind Turbine Test. Wind Matic WM 17S  

OpenAIRE

The report describes standard measurements performed on a Wind-Matic WM 17S, 75 kW wind turbine. The measurements carried out and reported here comprises the power output, system efficiency, energy production, transmission efficiency, rotor power, rotor efficiency, air-brakes efficiency, structural dynamics, loads at cut-in and braking, rotor torque at stopped condition, and noise emission.

Friis Pedersen, Troels

2011-01-01

255

Wind energy cooperatives and private wind turbines in the Netherlands  

International Nuclear Information System (INIS)

Experience of wind energy cooperatives in establishing and running wind turbines in the Netherlands is reported. The Dutch government provides subsidies of about 35% of the investment cost. Despite that, there are still problems and the paper outlines possible solutions. (UK)

256

Thermal Performance of Wind Turbine Power System's Engine Room  

Science.gov (United States)

Greatly expanded use of wind energy has been proposed to reduce dependence on fossil and nuclear fuels for electricity generation. For wind turbine power generation, as a mature technology in the field of wind power utilization, its large-scale deployment is limited by the cooling technology. Therefore, the temperature distribution of the wind turbine power generation is a key issue for the design of the cooling system. It is because the characteristics of cooling system have a great effect on the performance of the wind turbine power generation. Based on some assumptions and simplifications, a thermal model is developed to describe the heat transfer behavior of wind turbine power system. The numerical calculation method is adopted to solve the governing equation. The heat generation and heat flux are investigated with a given operating boundary. The achieved results can be used to verify whether the cooling system meets the design requirements. Meanwhile, they also can reveal that among the influencing factors, the meteorological conditions, generated output and operation state as well seriously influence its thermal performance. Numerical calculation of the cooling system enables better understanding and results in performance improvement of the system.

Liu, Zhili; Jiang, Yanlong; Zhou, Nianyong; Shi, Hong; Kang, Na; Wang, Yu

257

Operational-Condition-Independent Criteria Dedicated to Monitoring Wind Turbine Generators: Preprint  

Energy Technology Data Exchange (ETDEWEB)

To date the existing wind turbine condition monitoring technologies and commercially available systems have not been fully accepted for improving wind turbine availability and reducing their operation and maintenance costs. One of the main reasons is that wind turbines are subject to constantly varying loads and operate at variable rotational speeds. As a consequence, the influences of turbine faults and the effects of varying load and speed are coupled together in wind turbine condition monitoring signals. So, there is an urgent need to either introduce some operational condition de-coupling procedures into the current wind turbine condition monitoring techniques or develop a new operational condition independent wind turbine condition monitoring technique to maintain high turbine availability and achieve the expected economic benefits from wind. The purpose of this paper is to develop such a technique. In the paper, three operational condition independent criteria are developed dedicated for monitoring the operation and health condition of wind turbine generators. All proposed criteria have been tested through both simulated and practical experiments. The experiments have shown that these criteria provide a solution for detecting both mechanical and electrical faults occurring in wind turbine generators.

Yang, W.; Sheng, S.; Court, R.

2012-08-01

258

Wind Turbine Generator System Duration Test Report for the Mariah Power Windspire Wind Turbine  

Energy Technology Data Exchange (ETDEWEB)

This test was conducted as part of the U.S. Department of Energy's (DOE) Independent Testing project to help reduce the barriers of wind energy expansion by providing independent testing results for small turbines. In total, five turbines are being tested at the National Wind Technology Center (NWTC) as a part of the first round of this project. Duration testing is one of up to five tests that may be performed on the turbines. Other tests include power performance, safety and function, noise, and power quality tests. NWTC testing results provide manufacturers with reports that may be used to meet part of small wind turbine certification requirements. This duration test report focuses on the Mariah Power Windspire wind turbine.

Huskey, A.; Bowen, A.; Jager, D.

2010-05-01

259

Evaluating the impact of electrical grid connection on the wind turbine performance for Hofa wind farm scheme in Jordan  

International Nuclear Information System (INIS)

The growth of wind energy is attributed to the development of turbine size and the increase in number of units in each wind farm. The current modern design of large wind turbines (WT) is directed towards producing efficient, sensitive and reliable units. To achieve this goal, modern turbines are equipped with several devices which are operated with highly advanced electronic circuits. Sensing instruments, measuring devices and control processes of major systems and subsystems are based on various types of electronic apparatus and boards. These boards are very sensitive to the voltage variations caused by abnormal conditions in both the turbine itself and the electric grid to which the wind farm is connected. This paper evaluates wind farm records and proposes a number of methods to overcome such obstacles associated with the design of large wind turbines. Several cases of grid abnormality such as sudden feeder interruption due to the short circuit, network disconnection, voltage variation and circuit breaker opening affecting wind turbines operation and availability are classified and presented. The weight of such impact is determined for each type of disturbances associated with electronic problems in the wind turbine. Wind turbine performance at Hofa wind farm scheme in Jordan is taken as a case study

260

Evaluating the impact of electrical grid connection on the wind turbine performance for Hofa wind farm scheme in Jordan  

Energy Technology Data Exchange (ETDEWEB)

The growth of wind energy is attributed to the development of turbine size and the increase in number of units in each wind farm. The current modern design of large wind turbines (WT) is directed towards producing efficient, sensitive and reliable units. To achieve this goal, modern turbines are equipped with several devices which are operated with highly advanced electronic circuits. Sensing instruments, measuring devices and control processes of major systems and subsystems are based on various types of electronic apparatus and boards. These boards are very sensitive to the voltage variations caused by abnormal conditions in both the turbine itself and the electric grid to which the wind farm is connected. This paper evaluates wind farm records and proposes a number of methods to overcome such obstacles associated with the design of large wind turbines. Several cases of grid abnormality such as sudden feeder interruption due to the short circuit, network disconnection, voltage variation and circuit breaker opening affecting wind turbines operation and availability are classified and presented. The weight of such impact is determined for each type of disturbances associated with electronic problems in the wind turbine. Wind turbine performance at Hofa wind farm scheme in Jordan is taken as a case study. (author)

Abderrazzaq, M.H. [Faculty of Engineering Technology, Yarmouk University, Irbid (Jordan); Aloquili, O. [Faculty of Engineering, Electrical Department, Hashemite University, Amman, Zarqa P.O. Box 150459, Jordan 113115 (Jordan)

2008-11-15

261

Stochastic wind turbine control in multiblade coordinates  

DEFF Research Database (Denmark)

In this paper we consider wind turbine load attenuation through model based control. Asymmetric loads caused by the wind field can be reduced by pitching the blades individually. To this end we investigate the use of stochastic models of the wind which can be included in a model based individual pitch controller design. In this way the variability of the wind can be estimated and compensated for by the controller. The wind turbine model is in general time-variant due to its rotational nature. For this reason the modeling and control is carried out in so-called multiblade coordinates. A controller based on the H2 methodology is designed and tested in simulations.

Thomsen, Sven Creutz; Niemann, Hans Henrik

2010-01-01

262

Evaluating the impact of grid connection on wind turbine performance for Hofa farm scheme in Jordan  

Energy Technology Data Exchange (ETDEWEB)

The growth of wind energy is due to the development of turbine size and the increase in number of units in each wind farm. The current modern design of large wind turbines is directed towards producing efficient, sensitive and reliable units. To achieve this goal, modern turbines are equipped with several devices which are operated with highly advanced electronic circuits. Sensing instruments, measuring devices and control processes of major systems and subsystems are based on different types of electronic apparatus and boards which are extremely sensitive to the voltage variations caused by abnormal conditions in both the turbine itself and the electric grid to which the wind farm is connected. This paper evaluated wind farm records and proposed several methods to overcome obstacles associated with the design of large wind turbines. A case study was presented using the wind turbine (WT) performance of Hofa wind farm scheme in Jordan. The paper also presented and classified a number of cases of grid abnormality affecting wind turbines operation and availability. The degree and weight of such impact was determined for each type of disturbances associated with electronic problems in the wind turbine. The paper provided a description of the Hofa wind farm and discussed the general causes and consequences of turbine faults. The main categories of turbine standstill were studied according to the actual number of hours, during which the turbine was inoperative. Daily records were employed to specify the fault duration, maintenance hours, network outage periods and normal down time hours of the wind turbines. The paper focused on the periods during which the turbine was stopped due to network-initiated faults, and classified the component failures, the causes and frequency of occurrences of these failures. 15 refs., 10 figs.

Abderrazzaq, M.H.; Al Zou' bi, Q. [Yarmouk Univ., Irbid (Jordan). Hajjawi for Engineering Technology; Aloquili, O. [Hashemite Univ., Zarqa (Jordan). Dept. of Electrical Engineering

2007-07-01

263

Wind resource estimation and siting of wind turbines  

DEFF Research Database (Denmark)

Detailed knowledge of the characteristics of the natural wind is necessary for the design, planning and operational aspect of wind energy systems. Here, we shall only be concerned with those meteorological aspects of wind energy planning that are termed wind resource estimation. The estimation of the wind resource ranges from the overall estimation of the mean energy content of the wind over a large area - called regional assessment - to the prediction of the average yearly energy production of a specific wind turbine at a specific location - called siting. A regional assessment will most often lead to a so-called wind atlas. A precise prediction of the wind speed at a given site is essential because for aerodynamic reasons the power output of a wind turbine is proportional to the third power of the wind speed, hence even small errors in prediction of wind speed may result in large deviations in the anticipated power production and thereby lead to considerable uncertainty in the assessment of the economic benefits of installing wind power.

Lundtang Petersen, Erik; Mortensen, N.G.

1994-01-01

264

Wind tunnel tests of a free yawing downwind wind turbine  

Science.gov (United States)

This research paper presents preliminary results on a behavioural study of a free yawing downwind wind turbine. A series of wind tunnel tests was performed at the TU Delft Open Jet Facility with a three bladed downwind wind turbine and a rotor radius of 0.8 meters. The setup includes an off the shelf three bladed hub, nacelle and generator on which relatively flexible blades are mounted. The tower support structure has free yawing capabilities provided at the base. A short overview on the technical details of the experiment is given as well as a brief summary of the design process. The discussed test cases show that the turbine is stable while operating in free yawing conditions. Further, the effect of the tower shadow passage on the blade flapwise strain measurement is evaluated. Finally, data from the experiment is compared with preliminary simulations using DTU Wind Energy's aeroelastic simulation program HAWC2.

Verelst, D. R. S.; Larsen, T. J.; van Wingerden, J. W.

2014-12-01

265

Feasibility of monitoring large wind turbines using photogrammetry  

Energy Technology Data Exchange (ETDEWEB)

Photogrammetry, which is a proven measurement technique based on determination of the 3D coordinates of the points on an object by using two or more images taken from different positions, is proposed to be a promising and cost efficient alternative for monitoring the dynamic behavior of wind turbines. The pros and cons of utilizing this measurement technique for several applications such as dynamic testing or health monitoring of large wind turbines are discussed by presenting the results of the infield tests performed on a 2.5 MW - 80 m diameter - wind turbine. Within the scope of the work, the 3D dynamic response of the rotor is captured at 33 different locations simultaneously by using 4 CCD (charge coupled device) cameras while the turbine is rotating. Initial results show that the deformations on the turbine can be measured with an average accuracy of {+-}25 mm from a measurement distance of 220 m. Preliminary analyses of the measurements also show that some of the important turbine modes can be identified from photogrammetric measurement data. (author)

Ozbek, Muammer; Rixen, Daniel J. [Delft University of Technology, Faculty of Mechanical Engineering, Mekelweg 2, 2628CD Delft (Netherlands); Erne, Oliver; Sanow, Gunter [GOM mbH (Optical Measuring Techniques), Mittelweg 7-8, 38106 Braunschweig (Germany)

2010-12-15

266

Modeling of wind turbines for power system studies  

Energy Technology Data Exchange (ETDEWEB)

When wind turbines are installed into the electric grid, the power quality is affected. Today, strict installation recommendations often prevail due to a lack of knowledge on this subject. Consequently, it is important to predict the impact of wind turbines on the electric grid before the turbines are installed. The thesis describes relevant power quality issues, discusses different configurations of wind turbines with respect to power quality and draw requirements regarding wind turbine modeling. A model of a stall-regulated, fixed-speed wind turbine system is introduced and its power quality impact on the electric grid is evaluated. The model is verified with field measurements.

Petru, T.

2001-05-01

267

The Darrieus wind turbine for electrical power generation  

Science.gov (United States)

Aspects of wind as an energy source and the momentum theory of wind turbines are briefly examined. Types of Darrieus wind turbine are described; attention is given to a turbine with airfoil blades curved in troposkein form, and a turbine with straight blades of fixed or variable pitch. The Darrieus vertical-axis wind turbine is then considered with regard to aerodynamics, annual energy output, structures, control systems, and energy storage. Brief reviews of selected Darrieus wind turbine projects are given, including those at Magdalen Islands, Canada, Sandia Laboratories, Reading University, and Australia and New Zealand.

Robinson, M. L.

1981-06-01

268

A ?-Synthesis Approach to Robust Control of a Wind Turbine  

OpenAIRE

The problem of robust control of a wind turbine is considered in this paper. A set of controllers are designed based on a 2 degrees of freedom linearized model of a wind turbine. An extended Kalman filter is used to estimate effective wind speed and the estimated wind speed is used to find the operating point of the wind turbine. Due to imprecise wind speed estimation, uncertainty in the obtained linear model is considered. Uncertainties in the drivetrain stiffness and ...

Mirzaei, Mahmood; Niemann, Hans Henrik; Poulsen, Niels Kjølstad

2011-01-01

269

Performance of spanish wind turbines  

International Nuclear Information System (INIS)

In this document we can find a statistical evaluation for the wind energy generation from each spanish wind farm referred to 1994, going on with the work that has been carried out since 1992, by initiative of the Wind Energy Division from Renewable Energy Institute. The purpose of this work is to contribute with interesting information for the wind environment and offer a global view from monthly performances of different wind farms. (Author)

270

Resonant vibration control of wind turbine blades  

DEFF Research Database (Denmark)

The paper deals with introduction of damping to specific vibration modes of wind turbine blades, using a resonant controller with acceleration feedback. The wind turbine blade is represented by three-dimensional, two-node finite elements in a local, rotating frame of reference. The element formulation accounts for arbitrary mass density distributions, general elastic crosssection properties and geometric stiffness effects due to internal stresses. A compact, linear formulation for aerodynamic forces with associated stiffness and damping terms is established and added to the structural model. The efficiency of the resonant controller is demonstrated for a representative turbine blade exposed to turbulent wind loading. It is found that the present explicit tuning procedure yields close to optimal tuning, with very limited modal spill-over and effective reduction of the vibration amplitudes.

Svendsen, Martin Nymann Technical University of Denmark,

2010-01-01

271

Electromagnetic Interference on Large Wind Turbines  

Directory of Open Access Journals (Sweden)

Full Text Available Electromagnetic interference (EMI can both affect and be transmitted by mega-watt wind turbines. This paper provides a general overview on EMI with respect to mega-watt wind turbines. Possibilities of measuring all types of electromagnetic interference are shown. Electromagnetic fields resulting from a GSM transmitter mounted on a mega-watt wind turbine will be analyzed in detail. This cellular system operates as a real-time communication link. The method-of-moments is used to analytically describe the electro-magnetic fields. The electromagnetic interference will be analyzed under the given boundary condition with a commercial simulation tool. Different transmitter positions are judged on the basis of their radiation patterns. The principal EMI mechanisms are described and taken into consideration.

Florian Krug

2009-11-01

272

Methods of making wind turbine rotor blades  

Science.gov (United States)

A method of manufacturing a root portion of a wind turbine blade includes, in an exemplary embodiment, providing an outer layer of reinforcing fibers including at least two woven mats of reinforcing fibers, providing an inner layer of reinforcing fibers including at least two woven mats of reinforcing fibers, and positioning at least two bands of reinforcing fibers between the inner and outer layers, with each band of reinforcing fibers including at least two woven mats of reinforcing fibers. The method further includes positioning a mat of randomly arranged reinforcing fibers between each pair of adjacent bands of reinforcing fibers, introducing a polymeric resin into the root potion of the wind turbine blade, infusing the resin through the outer layer, the inner layer, each band of reinforcing fibers, and each mat of random reinforcing fibers, and curing the resin to form the root portion of the wind turbine blade.

Livingston, Jamie T. (Pensacola, FL); Burke, Arthur H. E. (Gulf Breeze, FL); Bakhuis, Jan Willem (Nijverdal, NL); Van Breugel, Sjef (Enschede, NL); Billen, Andrew (Daarlerveen, NL)

2008-04-01

273

OUT Success Stories: Advanced Airfoils for Wind Turbines  

International Nuclear Information System (INIS)

New airfoils have substantially increased the aerodynamic efficiency of wind turbines. It is clear that these new airfoils substantially increased energy output from wind turbines. Virtually all new blades built in this country today use these advanced airfoil designs

274

Study on transient stability of wind turbine with induction generator based on variable pitch control strategy  

DEFF Research Database (Denmark)

In order to enhance and improve the transient stability of a grid-connected wind turbine generator system under the power grid fault, based on typical pitch control strategy of wind turbine, considering the wind turbine system oscillation caused by the drive-train shaft flexibility, Based on Matlab/Simulink, electromagnetic transient state models of the wind tubine generator system and the pitch control models were presented, and the transient behaviors of the wind turbine genarator system using the typical and the proposed pitch control strategies were analyzed and compared when the power grid was subjected to a three-phase short-circuit fault. Also the results were compared with using reactive compensation device. The simulation results show that the proposed pitch control strategy can effectively improve the transient stability of wind turbine generator system.

Zhao, B.; Li, H.

2011-01-01

275

Comparative Study of Voltage Recovery Behaviors of Grid-Connected Wind Turbines  

DEFF Research Database (Denmark)

The fast development of wind power generation brings new requirements for wind turbine integration to the network. After the clearance of an external short-circuit fault, the voltage at the wind turbine terminal should be re-established with minimized power losses. This paper concentrates on voltage recovery of variable speed wind turbines. The models of two different kinds of variable speed wind turbines, respectively with slip control and with doubly fed induction generator (DFIG), are developed in PSCAD/EMTDC. In both wind power generation systems, control strategies are proposed to re-establish the wind turbine terminal voltage after the clearance of an external short-circuit fault, which have been demonstrated by simulation results.

Sun, Tao; Chen, Zhe

2004-01-01

276

An investigation of the levels of electromagnetic radiation generated by wind turbines  

International Nuclear Information System (INIS)

The issue of electromagnetic interference is arising with some regularity as various wind energy projects throughout the UK reach the stage where local authority planning approval is sought. To many of the parties involved, wind turbines represent an unknown quantity and hence objections to their siting must be expected. Wind turbines may cause electromagnetic interference through two quite distinct processes. The first occurs when the wind turbine scatters electromagnetic signals passing through the area of the site and essentially, provides a second path between the transmitter and receiver of the signal. The second source of interference arises when signals generated within the wind turbine itself affect communications equipment or, indeed, any electronic circuitry. A case in point is a wind farm project under development by Bonython Estates of Cornwall. The aim of this project was to investigate the emissions from the wind turbines proposed for the Bonython development. This was achieved by means of field measurements on existing installations. (author)

277

Design and Development of a Wind Turbine Simulator Using a Separately Excited DC Motor  

Directory of Open Access Journals (Sweden)

Full Text Available Over the course of the past decade, power generation based on wind energy has become a significant component in modern power systems, which has caused substantial increase in the wind power based research. As it is complicated to use a real wind turbine for laboratory purposes, development of a replica of a real wind turbine that can be connected and used indoors is imperative. This paper presents the design and development of a wind turbine simulator that operates on the typical power-speed characteristics of a wind turbine. First, the mathematical model of the wind turbine simulator is developed and the corresponding CAD simulations are carried out. Proposed hardware implementations involve a DC motor-DC generator set, a variable load and a control system based on PI controllers. It is a simple, low power and low cost design that can be easily connected to an AC system through an inverter.

K. K. M. S. Kariyawasam

2013-06-01

278

Optimization of wind farm turbines layout using an evolutive algorithm  

Energy Technology Data Exchange (ETDEWEB)

The optimum wind farm configuration problem is discussed in this paper and an evolutive algorithm to optimize the wind farm layout is proposed. The algorithm's optimization process is based on a global wind farm cost model using the initial investment and the present value of the yearly net cash flow during the entire wind-farm life span. The proposed algorithm calculates the yearly income due to the sale of the net generated energy taking into account the individual wind turbine loss of production due to wake decay effects and it can deal with areas or terrains with non-uniform load-bearing capacity soil and different roughness length for every wind direction or restrictions such as forbidden areas or limitations in the number of wind turbines or the investment. The results are first favorably compared with those previously published and a second collection of test cases is used to proof the performance and suitability of the proposed evolutive algorithm to find the optimum wind farm configuration. (author)

Gonzalez, Javier Serrano; Santos, Jesus Riquelme; Payan, Manuel Burgos [Department of Electrical Engineering, Av. de los Descubrimientos, University of Sevilla, Sevilla (Spain); Gonzalez Rodriguez, Angel G. [Department of Electronic Engineering and Automatic, University of Jaen, Jaen (Spain); Mora, Jose Castro [Persan S.A., Sevilla (Spain)

2010-08-15

279

Optimization of wind farm turbines layout using an evolutive algorithm  

International Nuclear Information System (INIS)

The optimum wind farm configuration problem is discussed in this paper and an evolutive algorithm to optimize the wind farm layout is proposed. The algorithm's optimization process is based on a global wind farm cost model using the initial investment and the present value of the yearly net cash flow during the entire wind-farm life span. The proposed algorithm calculates the yearly income due to the sale of the net generated energy taking into account the individual wind turbine loss of production due to wake decay effects and it can deal with areas or terrains with non-uniform load-bearing capacity soil and different roughness length for every wind direction or restrictions such as forbidden areas or limitations in the number of wind turbines or the investment. The results are first favorably compared with those previously published and a second collection of test cases is used to proof the performance and suitability of the proposed evolutive algorithm to find the optimum wind farm configuration. (author)

280

Design and aero-acoustic analysis of a counter-rotating wind turbine  

Science.gov (United States)

Wind turbines have become an integral part of the energy business because they are one of the most economical and reliable sources of renewable energy. Conventional wind turbines are capable of capturing less than half of the energy present in the wind. Hence, to make the wind turbines more efficient, it is important to increase their performance. A horizontal axis wind turbine with multiple rotors is one concept that can achieve a higher power conversion rate. Also, a concern for wind energy is the noise generated by wind turbines. Hence, an investigation into the acoustic behavior of a multi-rotor horizontal axis wind turbine is required. In response to the need of a wind turbine design with higher power coefficient, a unique design of a counter-rotating horizontal axis wind turbine (CR-HAWT) is proposed. The Blade Element Momentum (BEM) theory is used to aerodynamically design the blades of the two rotors. Modifications are made to the BEM theory to accommodate the interaction of the two rotors. The tower effect on the noise generation of the downwind rotor is investigated. Predictions are made for the total noise generated by the wind turbine at its design operating conditions. A total power coefficient of 65.2% is predicted for the proposed CR-HAWT design. A low tip speed ratio is chosen to minimize the noise generation. The aeroacoustic analysis of the CR-HAWT shows that the noise generated at its design operating conditions is within an acceptable range. Thus, the CR-HAWT is predicted to be a quiet wind turbine with a high power coefficient, making it highly desirable for small wind turbine applications.

Agrawal, Vineesh V.

281

Analysis and estimation of transient stability for a grid-connected wind turbine with induction generator  

DEFF Research Database (Denmark)

Increasing levels of wind energy in modern electrical power system is initiating a need for accurate analysis and estimation of transient stability of wind turbine generation systems. This paper investigates the transient behaviors and possible direct methods for transient stability evaluation of a grid-connected wind turbine with squirrel cage induction generator (SCIG). Firstly, by using an equivalent lump mass method, a three-mass wind turbine equivalent model is proposed considering both the blades and the shaft flexibility of the wind turbine drive train system. Combined with the detailed electromagnetic transient models of a SCIG, the transient behaviors of the wind turbine generation system during a three-phase fault are simulated and compared with the traditional models. Secondly, in order to quickly estimate the transient stability limit of the wind turbine generation system, a direct method based on normal form theory is proposed. The transient models of the wind turbine generation system including the flexible drive train model are derived based on the direct transient stability estimation method. A method of critical clearing time (CCT) calculation is developed for the transient stability estimation of the wind turbine generation system. Finally, the CCT at various initial mechanical torques for different dynamical models are calculated and compared with the trial and error method by simulation, when the SCIG stator terminal is subjected to a three-phase short-circuit fault. The results have shown the proposed method and models are correct and valid.

Li, H.; Zhao, B.

2011-01-01

282

Wind Turbine Gearbox Condition Monitoring with AAKR and Moving Window Statistic Methods  

OpenAIRE

Condition Monitoring (CM) of wind turbines can greatly reduce the maintenance costs for wind farms, especially for offshore wind farms. A new condition monitoring method for a wind turbine gearbox using temperature trend analysis is proposed. Autoassociative Kernel Regression (AAKR) is used to construct the normal behavior model of the gearbox temperature. With a proper construction of the memory matrix, the AAKR model can cover the normal working space for the gearbox. When the gearbox has a...

Peng Guo; Nan Bai

2011-01-01

283

Wind Turbine Noise and Natural Sounds : Masking, Propagation and Modeling  

OpenAIRE

Wind turbines are an environmentally friendly and sustainable power source. Unfortunately, the noise impact can cause deteriorated living conditions for nearby residents. The audibility of wind turbine sound is influenced by ambient sound. This thesis deals with some aspects of noise from wind turbines. Ambient sounds influence the audibility of wind turbine noise. Models for assessing two commonly occurring natural ambient sounds namely vegetation sound and sound from breaking waves are pres...

Bolin, Karl

2009-01-01

284

High Power Density Power Electronic Converters for Large Wind Turbines  

OpenAIRE

In large wind turbines (in MW and multi-MW ranges), which are extensively utilized in wind power plants, full-scale medium voltage (MV) multi-level (ML) voltage source converters (VSCs) are being more preferably employed nowadays for interfacing these wind turbines with electricity grids. For these VSCs, high power density is required due to limited turbine nacelle space. Also, high reliability is required since maintenance cost of these remotely located wind turbines is quite high and these ...

Senturk, Osman Selcuk

2011-01-01

285

Power Electronics for the Next Generation Wind Turbine System  

OpenAIRE

The wind power generation has been steadily growing both for the total installed capacity and for the individual turbine size. Due to much more significant impacts to the power grid, the power electronics, which can change the behavior of wind turbines from an unregulated power source to an active generation unit, are becoming crucial in the wind turbine system. The objective of this project is to study the power electronics technology used for the next generation wind turbines. Some emerging...

Ma, Ke

2013-01-01

286

Aero-acoustic Computations of Wind Turbines  

DEFF Research Database (Denmark)

A numerical algorithm for acoustic noise generation is extended to 3D flows. The approach involves two parts comprising a viscous incompressible flow part and an inviscid acoustic part. In order to simulate noise generated from a wind turbine, the incompressible and acoustic equations are written in polar coordinates. The developed algorithm is combined with a so-called actuator-line technique in which the loading is distributed along lines representing the blade forces. Computations are carried out for the 500kW Nordtank wind turbine equipped with three LM19 blades. ©2001 The American Institute of Aeronautics and Astronautics, Inc. and ASME

Shen, Wen Zhong; Michelsen, Jess

2002-01-01

287

Aerodynamic performance prediction of horizontal axis wind turbines  

Science.gov (United States)

A new method for calculating the aerodynamic performance of horizontal axis wind turbines is described. The method, entitled the helical vortex method, directly calculates the local induced velocity due to helical vortices that originate at the rotor blade. Furthermore, the method does not require a specified circulation distribution. Results of the method are compared to similar results obtained from Wilson PROP code methods as well as to existing experimental data taken from a Mod-O wind turbine. It is shown that results of the proposed method agree well with experimental values of the power output both near cut-in and at rated wind speeds. Further, it is found that the method does not experience some of the numerical difficulties encountered by the PROP code when run at low wind velocities.

Jeng, D. R.; Keith, T. G.; Aliakbarkhanafjeh, A.

1981-05-01

288

Two LQRI based Blade Pitch Controls for Wind Turbines  

Directory of Open Access Journals (Sweden)

Full Text Available As the wind turbine size has been increasing and their mechanical components are built lighter, the reduction of the structural loads becomes a very important task of wind turbine control in addition to maximum wind power capture. In this paper, we present a separate set of collective and individual pitch control algorithms. Both pitch control algorithms use the LQR control technique with integral action (LQRI, and utilize Kalman filters to estimate system states and wind speed. Compared to previous works in this area, our pitch control algorithms can control rotor speed and blade bending moments at the same time to improve the trade-off between rotor speed regulation and load reduction, while both collective and individual pitch controls can be designed separately. Simulation results show that the proposed collective and individual pitch controllers achieve very good rotor speed regulation and significant reduction of blade bending moments.

Yoonsu Nam

2012-06-01

289

Amplitude modulation of wind turbine noise  

CERN Document Server

Due to swish and thump amplitude modulation, the noise of wind turbines cause more annoyance than other environmental noise of the same average level. The wind shear accounts for the thump modulation (van den Berg effect). Making use of the wind speed measurements at the hub height, as well as at the top and the bottom of the rotor disc (Fig.1), the non-standard wind profile is applied. It causes variations in the A-weighted sound pressure level, LpA. The difference between the maximum and minimum of LpA characterizes thump modulation (Fig.2).

Makarewicz, Rufin

2013-01-01

290

Amplitude modulation of wind turbine noise  

OpenAIRE

Due to swish and thump amplitude modulation, the noise of wind turbines cause more annoyance than other environmental noise of the same average level. The wind shear accounts for the thump modulation (van den Berg effect). Making use of the wind speed measurements at the hub height, as well as at the top and the bottom of the rotor disc (Fig.1), the non-standard wind profile is applied. It causes variations in the A-weighted sound pressure level, LpA. The difference between ...

Makarewicz, Rufin; Golebiewski, Roman

2013-01-01

291

Wind Turbine Contingency Control Through Generator De-Rating  

Science.gov (United States)

Maximizing turbine up-time and reducing maintenance costs are key technology drivers for wind turbine operators. Components within wind turbines are subject to considerable stresses due to unpredictable environmental conditions resulting from rapidly changing local dynamics. In that context, systems health management has the aim to assess the state-of-health of components within a wind turbine, to estimate remaining life, and to aid in autonomous decision-making to minimize damage to the turbine. Advanced contingency control is one way to enable autonomous decision-making by providing the mechanism to enable safe and efficient turbine operation. The work reported herein explores the integration of condition monitoring of wind turbines with contingency control to balance the trade-offs between maintaining system health and energy capture. The contingency control involves de-rating the generator operating point to achieve reduced loads on the wind turbine. Results are demonstrated using a high fidelity simulator of a utility-scale wind turbine.

Frost, Susan; Goebel, Kai; Balas, Mark

2013-01-01

292

Duration Test Report for the Entegrity EW50 Wind Turbine  

Energy Technology Data Exchange (ETDEWEB)

This report summarizes the results of a duration test that NREL conducted on the Entegrity EW50 wind turbine. This test was conducted in accordance with the International Electrotechnical Commissions' (IEC) standard, Wind Turbine Generator System Part 2: Design requirements for small wind turbines, IEC 61400-2 Ed.2.0, 2006-03.

Smith, J.; Huskey, A.; Jager, D.; Hur, J.

2012-12-01

293

Experiments with a diffuser augmented model wind turbine  

Energy Technology Data Exchange (ETDEWEB)

The initial stages of the experimental development of the diffuser augmented wind turbine (DAWT) employed various screen meshes to simulate the energy extraction mechanisms of a wind turbine. In this investigation in a 2 x 3 m (and x 10 ft) wind tunnel, a three bladed constant chord, untwisted turbine model was incorporated into a DAWT model. 8 refs.

Gilbert, B.L.; Foreman, K.M.

1982-03-01

294

Structured Linear Parameter Varying Control of Wind Turbines  

DEFF Research Database (Denmark)

High performance and reliability are required for wind turbines to be competitive within the energy market. To capture their nonlinear behavior, wind turbines are often modeled using parameter-varying models. In this chapter, a framework for modelling and controller design of wind turbines is presented. We specifically consider variable-speed, variable-pitch wind turbines with faults on actuators and sensors. Linear parameter-varying (LPV) controllers can be designed by a proposed method that allows the inclusion of faults in the LPV controller design. Moreover, the controller structure can be arbitrarily chosen: static output feedback, dynamic (reduced order) output feedback, decentralized, among others. The controllers are scheduled on an estimated wind speed to manage the parametervarying nature of the model and on information from a fault diagnosis system. The optimization problems involved in the controller synthesis are solved by an iterative LMI-based algorithm. The resulting controllers can also be easily implemented in practice due to low data storage and simple math operations. The performance of the LPV controllers is assessed by nonlinear simulations results.

Adegas, Fabiano Daher; Sloth, Christoffer

2012-01-01

295

Wind Turbine Generator System Duration Test Report for the ARE 442 Wind Turbine  

Energy Technology Data Exchange (ETDEWEB)

This test is being conducted as part of the U.S. Department of Energy's (DOE) Independent Testing project. This project was established to help reduce the barriers of wind energy expansion by providing independent testing results for small turbines. In total, four turbines are being tested at the NWTC as a part of this project. Duration testing is one of up to 5 tests that may be performed on the turbines, including power performance, safety and function, noise, and power quality tests. The results of the testing provide manufacturers with reports that may be used for small wind turbine certification. The test equipment includes a grid connected ARE 442 wind turbine mounted on a 30.5 meter (100 ft) lattice tower manufactured by Abundant Renewable Energy. The system was installed by the NWTC Site Operations group with guidance and assistance from Abundant Renewable Energy.

van Dam, J.; Baker, D.; Jager, D.

2010-05-01

296

Wind Turbine Control Impact on Stability of Wind Farms Based on Real-Life Systems Analysis  

OpenAIRE

This paper presents stability analysis of wind farms in frequency domain. The interaction between the wind turbine control system and the wind farm structure in wind farms is deeply investigated. Two wind farms (i.e. Horns Rev II and Karnice) are taken in to consideration in the study. It is shown that wind farm components such as long HVAC cables and park transformers can introduce significant low-frequency series resonances seen form the wind turbine terminals which can affect wind turbine ...

Kocewiak, Lukasz Hubert; Hjerrild, Jesper; Bak, Claus Leth

2012-01-01

297

Power Electronics Converters for Wind Turbine Systems  

DEFF Research Database (Denmark)

The steady growth of installed wind power together with the upscaling of the single wind turbine power capability has pushed the research and development of power converters toward full-scale power conversion, lowered cost pr kW, increased power density, and also the need for higher reliability. In this paper, power converter technologies are reviewed with focus on existing ones and on those that have potential for higher power but which have not been yet adopted due to the important risk associated with the high-power industry. The power converters are classified into single- and multicell topologies, in the latter case with attention to series connection and parallel connection either electrical or magnetic ones (multiphase/windings machines/transformers). It is concluded that as the power level increases in wind turbines, medium-voltage power converters will be a dominant power converter configuration, but continuously cost and reliability are important issues to be addressed.

Blaabjerg, Frede; Liserre, Marco

2012-01-01

298

The power fluctuations of a wind turbine  

Energy Technology Data Exchange (ETDEWEB)

At the beginning of the paper the power fluctuations in the case of a sinusoidal gust are investigated. A quasi-steady model is derived. Then this model is corrected to account for the dynamic characteristics of the turbine. The correction is introduced using a special correction function which is obtained after running a complete dynamic model of the wind turbine. It is shown that for each value of average wind speed there is, for practical purposes, a linear relation between the intensity of power fluctuations and the product of the intensity of turbulence and the above-mentioned correction function. The derivation for a sinusoidal gust is the basis for the analysis of the power fluctuations in the case of a `real` wind. The model for `real` wind is validated by comparing its results with field measurements

Rosen, A; Sheinman, Y [Faculty of Aerospace Engineering, Technion - Israel Institute of Technology, Haifa (Israel)

1996-01-01

299

Integrated analysis of wind turbines - The impact of power systems on wind turbine design  

DEFF Research Database (Denmark)

Megawatt-size wind turbines nowadays operate in very complex environmental conditions, and increasingly demanding power system requirements. Pursuing a cost-effective and reliable wind turbine design is a multidisciplinary task. However nowadays, wind turbine design and research areas such as aeroelastic and mechanical, electrical and control, and grid integration, make use of simulation tools dedicated to specific areas. Practical experience shows there is a need to bridge the expertise from different design areas. The focus of this Ph.D. study is on the integrated dynamic analysis of operating conditions that stem from disturbances in the power system. An integrated simulation environment, wind turbine models, and power system models are developed in order to take an integral perspective that considers the most important aeroelastic, structural, electrical, and control dynamics. Applications of the integrated simulation environment are presented. The analysis of an asynchronous machine, and numerical simulations of a fixedspeed wind turbine in the integrated simulation environment, demonstrate the effects on structural loads of including the generator rotor fluxes dynamics in aeroelastic studies. Power system frequency control studies of variable-speed wind turbines with the integrated simulation environment, show that is possible to make a sensible estimation of the contribution of a wind farm to power system frequency control, while studying the impact on wind turbine structural loads. Finally, studies of the impact that voltage faults have on wind turbine loads are presented. The case of unbalanced faults is addressed, the possibilities and drawbacks for reduction of structural loads using electrical control actions is investigated. Load reduction using resonant damping control is proven and quantified.

Barahona Garzón, Braulio

2012-01-01

300

Wind Turbine Generator System Power Quality Test Report for the Gaia Wind 11-kW Wind Turbine  

Energy Technology Data Exchange (ETDEWEB)

This report details the power quality test on the Gaia Wind 11-kW Wind Turbine as part of the U.S. Department of Energy's Independent Testing Project. In total five turbines are being tested as part of the project. Power quality testing is one of up to five test that may be performed on the turbines including power performance, safety and function, noise, and duration tests. The results of the testing provide manufacturers with reports that may be used for small wind turbine certification.

Curtis, A.; Gevorgian, V.

2011-07-01

301

Design optimization of small wind turbines for low wind regimes  

Science.gov (United States)

Attention is given to two examples illustrating the design optimization process for small wind turbines, which is concerned with machine parameters and the wind characteristics and electrical loads of the intended operating environment. The optimization process emphasizes the importance of rated wind speed, rotor rpm, generator size, and rotor blade characteristics. Wind turbines are noted to have been designed for excessively high wind speeds and generator capacities in the past; machines intended for residential use should instead be scaled to closely match the expected load and should be rated at a windspeed close to the value of the greatest energy contribution. Simplicity of design is noted to yield reduced costs and lower maintenance requirements while increasing reliability.

Cromack, D. E.; Oscar, D.

1984-08-01

302

European wind turbine testing procedure developments. Task 1: Measurement method to verify wind turbine performance characteristics  

Energy Technology Data Exchange (ETDEWEB)

There is currently significant standardisation work ongoing in the context of wind farm energy yield warranty assessment and wind turbine power performance testing. A standards maintenance team is revising the current IEC (EN) 61400-12 Ed 1 standard for wind turbine power performance testing. The standard is being divided into four documents. Two of them are drafted for evaluation and verification of complete wind farms and of individual wind turbines within wind farms. This document, and the project it describes, has been designed to help provide a solid technical foundation for this revised standard. The work was wide ranging and addressed 'grey' areas of knowledge, regarding existing methodologies or to carry out basic research in support of fundamentally new procedures. The work has given rise to recommendations in all areas of the work, including site calibration procedures, nacelle anemometry, multi-variate regression analysis and density normalisation. (au)

Hunter, R.; Friis Pedersen, T.; Dunbabin, P.; Antoniou, I.; Frandsen, S.; Klug, H.; Albers, A.; Lee, W.K.

2001-01-01

303

Electrical Aspects of Wind Turbines  

DEFF Research Database (Denmark)

This is the most authoritative single volume on offshore wind power yet published. Distinguished experts, mainly from Europe's leading universities, have contributed a collection of peer reviewed papers on the interfaces between wind power technology and marine engineering. The range of issues covered by the book include: wind as a resource; wind power generation; connection to the grid; the marine environment and engineering issues particular to it. This book is essential for academic departments of mechanical engineering/energy engineering/ renewable energy. Offshore wind power generation will be the driver of the offshore industry for the foreseeable future: all organisations involved in offshore engineering should have this book.

Chen, Zhe; Blaabjerg, Frede

2009-01-01

304

Damping Wind and Wave Loads on a Floating Wind Turbine  

DEFF Research Database (Denmark)

Offshore wind energy capitalizes on the higher and less turbulent wind speeds at sea. To enable deployment of wind turbines in deep-water locations, structures are being explored, where wind turbines are placed on a floating platform. This combined structure presents a new control problem, due to the partly unconstrained movement of the platform and ocean wave excitation. If this additional complexity is not dealt with properly, this may lead to a significant increase in the structural loads and, potentially, instability of the controlled system. In this paper, the wave excitation is investigated, and we show the influence that both wind speed, wave frequencies and misalignment between wind and waves have on the system dynamics. A new control model is derived that extends standard turbine models to include the hydrodynamics, additional platform degrees of freedom, the platform mooring system and tower side-side motion, including gyroscopic effects. The models support a model-based design that includes estimators for wind speed and wave frequency. The design is applied to a number of examples representing different wind and wave conditions and successfully demonstrates a reduction in the structural oscillations, while improving power performance.

Christiansen, SØren; Bak, Thomas

2013-01-01

305

Floating axis wind turbines for offshore power generation—a conceptual study  

International Nuclear Information System (INIS)

The cost of energy produced by offshore wind turbines is considered to be higher than land based ones because of the difficulties in construction, operation and maintenance on offshore sites. To solve the problem, we propose a concept of a wind turbine that is specially designed for an offshore environment. In the proposed concept, a floater of revolutionary shape supports the load of the wind turbine axis. The floater rotates with the turbine and the turbine axis tilts to balance the turbine thrust, buoyancy and gravity. The tilt angle is passively adjustable to wind force. The angle is 30° at rated power. The simplicity of the system leads to further cost reduction of offshore power generation.

306

A geographic analysis of wind turbine placement in Northern California  

International Nuclear Information System (INIS)

The development of new wind energy projects requires a significant consideration of land use issues. An analytic framework using a Geographic Information System (GIS) was developed to evaluate site suitability for wind turbines and to predict the locations and extent of land available for feasible wind power development. The framework uses rule-based spatial analysis to evaluate different scenarios. The suitability criteria include physical requirements as well as environmental and human impact factors. By including socio-political concerns, this technique can assist in forecasting the acceptance level of wind farms by the public. The analysis was used to evaluate the nine-county region of the Greater San Francisco Bay Area. The model accurately depicts areas where large-scale wind farms have been developed or proposed. It also shows that there are many locations available in the Bay Area for the placement of smaller-scale wind turbines. The framework has application to other regions where future wind farm development is proposed. This information can be used by energy planners to predict the extent that wind energy can be developed based on land availability and public perception

307

Transient stability of DFIG wind turbines at an external short-circuit fault  

Science.gov (United States)

The fast development of wind power generation brings new requirements for wind turbine integration into the network. After clearance of an external short-circuit fault, grid-connected wind turbines should restore their normal operation without power loss caused by disconnections. This article concentrates on the transient stability of variable speed wind turbines with doubly fed induction generators (DFIGs) at an external short-circuit fault. A simulation model of a MW-level variable speed wind turbine with a DFIG developed in PSCAD/EMTDC is presented and the control and protection schemes are described in detail. The transient process of grid-connected wind turbines with DFIGs at an external short-circuit fault is analysed, and in critical post-fault situations a measure is proposed for the voltage recovery of DFIG wind turbines after fault clearance. Simulation results demonstrate that in uncritical post-fault situations the control schemes are able to restore the wind turbine's normal operation without disconnections. It is also proved that the proposed measure is effective in re-establishing the voltage at the wind turbine terminal in critical post-fault situations. Copyright

Sun, Tao; Chen, Zhe; Blaabjerg, Frede

2005-07-01

308

PowerJet Wind Turbine Project  

Energy Technology Data Exchange (ETDEWEB)

PROJECT OBJECTIVE The PowerJet wind turbine overcomes problems characteristic of the small wind turbines that are on the market today by providing reliable output at a wide range of wind speeds, durability, silent operation at all wind speeds, and bird-safe operation. Prime Energy�s objective for this project was to design and integrate a generator with an electrical controller and mechanical controls to maximize the generation of electricity by its wind turbine. The scope of this project was to design, construct and test a mechanical back plate to control rotational speed in high winds, and an electronic controller to maximize power output and to assist the base plate in controlling rotational speed in high winds. The test model will continue to operate beyond the time frame of the project, with the ultimate goal of manufacturing and marketing the PowerJet worldwide. Increased Understanding of Electronic & Mechanical Controls Integrated With Electricity Generator The PowerJet back plate begins to open as wind speed exceeds 13.5 mps. The pressure inside the turbine and the turbine rotational speed are held constant. Once the back plate has fully opened at approximately 29 mps, the controller begins pulsing back to the generator to limit the rotational speed of the turbine. At a wind speed in excess of 29 mps, the controller shorts the generator and brings the turbine to a complete stop. As the wind speed subsides, the controller releases the turbine and it resumes producing electricity. Data collection and instrumentation problems prevented identification of the exact speeds at which these events occur. However, the turbine, controller and generator survived winds in excess of 36 mps, confirming that the two over-speed controls accomplished their purpose. Technical Effectiveness & Economic Feasibility Maximum Electrical Output The output of electricity is maximized by the integration of an electronic controller and mechanical over-speed controls designed and tested during the course of this project. The output exceeds that of the PowerJet�s 3-bladed counterparts (see Appendix). Durability All components of the PowerJet turbine assembly�including the electronic and mechanical controls designed, manufactured and field tested during the course of this project�proved to be durable through severe weather conditions, with constant operation and no interruption in energy production. Low Cost Materials for the turbine, generator, tower, charge controllers and ancillary parts are available at reasonable prices. Fabrication of these parts is also readily available worldwide. The cost of assembling and installing the turbine is reduced because it has fewer parts and requires less labor to manufacture and assemble, making it competitively priced compared with turbines of similar output manufactured in the U.S. and Europe. The electronic controller is the unique part to be included in the turbine package. The controllers can be manufactured in reasonably-sized production runs to keep the cost below $250 each. The data logger and 24 sensors are for research only and will be unnecessary for the commercial product. Benefit To Public The PowerJet wind-electric system is designed for distributed wind generation in 3 and 4 class winds. This wind turbine meets DOE�s requirements for a quiet, durable, bird-safe turbine that eventually can be deployed as a grid-connected generator in urban and suburban settings. Results As described more fully below and illustrated in the Appendices, the goals and objectives outlined in 2060 SOPO were fully met. Electronic and mechanical controls were successfully designed, manufactured and integrated with the generator. The turbine, tower, controllers and generators operated without incident throughout the test period, surviving severe winter and summer weather conditions such as extreme temperatures, ice and sustained high winds. The electronic controls were contained in weather-proof electrical boxes and the electrical wires were fully contained inside

Bartlett, Raymond J

2008-11-30

309

Wind turbine pitch control using ICPSO-PID algorithm  

DEFF Research Database (Denmark)

For the traditional simplified first-order pitch-control system model, it is difficult to describe a real dynamic characteristic of a variable pitch action system, thus a complete high order mathematical model has to be developed for the pitch control of wind turbine generation (WTG). In the paper, a pitch controller was designed based on power and wind speed and by considering the inertia and delay characteristics of a pitch-control system to achieve a constant power output when a wind speed was beyond the rated one. A novel ICPSO-PID control algorithm was proposed based on a combination of improved cooperative particle swarm optimization (ICPSO) and PID, subsequently, it was used to tune the pitch controller parameters; thus the difficulty in PID tuning was removed when a wind speed was above the rated speed. It was indicated that the proposed optimization algorithm can tune the pitch controller parameters quickly; and the feed-forward controller for wind speed can improve dynamics of a pitch-control system; additionally the power controller can allow a wind turbine to have a constant power output as a wind speed is over the rated one. Compared with a conventional PID, the controller with ICPSO-PID algorithm has a smaller overshoot, a shorter tuning time and better robustness. The design method proposed in the paper can be applied in a practical electro-hydraulic pitch control system for WTG.

Xu, Chang; Tian, Qiangqiang

2013-01-01

310

Grid fault and design-basis for wind turbines. Final report  

Energy Technology Data Exchange (ETDEWEB)

This is the final report of a Danish research project 'Grid fault and design-basis for wind turbines'. The objective of this project has been to assess and analyze the consequences of the new grid connection requirements for the fatigue and ultimate structural loads of wind turbines. The fulfillment of the grid connection requirements poses challenges for the design of both the electrical system and the mechanical structure of wind turbines. The development of wind turbine models and novel control strategies to fulfill the TSO's requirements are of vital importance in this design. Dynamic models and different fault ride-through control strategies have been developed and assessed in this project for three different wind turbine concepts (active stall wind turbine, variable speed doublyfed induction generator wind turbine, variable speed multipole permanent magnet wind turbine). A computer approach for the quantification of the wind turbines structural loads caused by the fault ride-through grid requirement, has been proposed and exemplified for the case of an active stall wind turbine. This approach relies on the combination of knowledge from complimentary simulation tools, which have expertise in different specialized design areas for wind turbines. In order to quantify the impact of the grid faults and grid requirements fulfillment on wind turbines structural loads and thus on their lifetime, a rainflow and a statistical analysis for fatigue and ultimate structural loads, respectively, have been performed and compared for two cases, i.e. one when the turbine is immediately disconnected from the grid when a grid fault occurs and one when the turbine is equipped with a fault ride-through controller and therefore it is able to remain connected to the grid during the grid fault. Different storm control strategies, that enable variable speed wind turbines to produce power at wind speeds higher than 25m/s and up to 50m/s without substantially increasing the structural loads, have also been proposed and investigated during the project. Statistics in terms of mean value and standard deviation have been analysed and rainflow calculations have been performed to estimate the impact over the lifetime of a variable speed wind turbine. (author)

Hansen, A.D.; Cutululis, N.A.; Markou, H.; Soerensen, Poul; Iov, F.

2010-01-15

311

Friction drive 2 MW wind turbine  

Energy Technology Data Exchange (ETDEWEB)

Details of a friction drive 2 MW wind turbine were presented. The friction drive (FD) concept was comprised of a 3-blade horizontal axis with variable speed operation and no gearbox. The system used multiple small generators with independent load paths in order to provide the potential for higher-rated powers than conventional wind turbines. The FD system was designed for use with lighter nacelle weights in turbines rated at over 4 MW. The FD 65 kW was designed to have a measured friction drive efficiency ranging between 95 to 98 per cent. The electrical generators were synchronized, and a slipping mechanism was used to protect generators at high wind gusts. The protection mechanism only allowed the pre-set torque to be transmitted to power generation components. A slipping device was used when the control system was not able to react quickly enough to sudden or localized wind gusts. Results of simulation studies showed that the system is capable of compensating for extreme wind gusts. Shop tire testing results also showed that the tire materials used in the FD were scalable to 2 MW range with an estimated tire life of between 3 to 5 years. Specifications and wind curves were also included. tabs., figs.

Nayef, N. [CWind Inc., Owen Sound, ON (Canada)

2008-07-01

312

Built-Environment Wind Turbine Roadmap  

Energy Technology Data Exchange (ETDEWEB)

Although only a small contributor to total electricity production needs, built-environment wind turbines (BWTs) nonetheless have the potential to influence the public's consideration of renewable energy, and wind energy in particular. Higher population concentrations in urban environments offer greater opportunities for project visibility and an opportunity to acquaint large numbers of people to the advantages of wind projects on a larger scale. However, turbine failures will be equally visible and could have a negative effect on public perception of wind technology. This roadmap provides a framework for achieving the vision set forth by the attendees of the Built-Environment Wind Turbine Workshop on August 11 - 12, 2010, at the U.S. Department of Energy's National Renewable Energy Laboratory. The BWT roadmap outlines the stakeholder actions that could be taken to overcome the barriers identified. The actions are categorized as near-term (0 - 3 years), medium-term (4 - 7 years), and both near- and medium-term (requiring immediate to medium-term effort). To accomplish these actions, a strategic approach was developed that identifies two focus areas: understanding the built-environment wind resource and developing testing and design standards. The authors summarize the expertise and resources required in these areas.

Smith, J.; Forsyth, T.; Sinclair, K.; Oteri, F.

2012-11-01

313

Small Wind Turbine Applications: Current Practice in Colorado  

International Nuclear Information System (INIS)

Numerous small wind turbines are being used by homeowners in Colorado. Some of these installations are quite recent while others date back to the federal tax-credit era of the early 1980s. Through visits with small wind turbine owners in Colorado, I have developed case studies of six small wind energy applications focusing on the wind turbine technology, wind turbine siting, the power systems and electric loads, regulatory issues, and motivations about wind energy. These case studies offer a glimpse into the current state-of-the-art of small-scale wind energy and provide some insight into issues affecting development of a wider market

314

Dynamic Response Analysis of an Offshore Wind Turbine  

OpenAIRE

The offshore wind power is an attractive renewable energy resource. To improve the wind power generation capacity, there is a strong desire for offshore wind turbine to go to deep waters. For offshore fixed wind turbine, stronger foundation like jacket structure has a good applicability for deeper water depth. A 70-meters jacket substructure for offshore wind turbine is designed. This thesis focuses on the dynamic structural response analysis of this jacket substructure, with a particular foc...

Li, Yu

2011-01-01

315

Low Cost Small Wind Turbine Generators for Developing Countries:  

OpenAIRE

Wind energy accounts for an increasing percentage of the energy supplied to the electricity network. Electricity generation from wind is now cheaper than other renewables and almost cost competitive with other conventional sources of electricity generation. However, this impressive growth is largely due to advances in large wind turbines, particularly off-shore wind turbines. Small wind turbines on the other hand have not been developing at such an impressive rate. In the past few years, an a...

Ani, S. O.

2013-01-01

316

Wind Turbines on CO2 Neutral Luminaries in Urban Areas  

DEFF Research Database (Denmark)

In the present work, an overview of three different wind turbines used in hybrid luminaries is presented. The turbines are: vertical-axis twisted Savonius, three-blade horizontal-axis, and vertical-axis three-blade helical H-rotor. The considered luminaries are also equipped with photovoltaic panels and batteries, detailed investigation of which is outside the scope of the present manuscript. Analysis of the turbines’ performance based on producer-supplied power curves is presented together with an estimation of the wind climate in Copenhagen district comprising 1-2 story single family buildings. A new vertical-axis twisted Savonius rotor is proposed for a luminary being designed for such a district within the “Development of CO2 neutral urban luminary” project.

Skrzypinski, Witold Robert; Bak, Christian

2013-01-01

317

Control of Next Generation Aircraft and Wind Turbines  

Science.gov (United States)

The first part of this talk will describe some of the exciting new next generation aircraft that NASA is proposing for the future. These aircraft are being designed to reduce aircraft fuel consumption and environmental impact. Reducing the aircraft weight is one approach that will be used to achieve these goals. A new control framework will be presented that enables lighter, more flexible aircraft to maintain aircraft handling qualities, while preventing the aircraft from exceeding structural load limits. The second part of the talk will give an overview of utility-scale wind turbines and their control. Results of collaboration with Dr. Balas will be presented, including new theory to adaptively control the turbine in the presence of structural modes, with the focus on the application of this theory to a high-fidelity simulation of a wind turbine.

Frost, Susan

2010-01-01

318

Latest achievements in wind turbine development  

Energy Technology Data Exchange (ETDEWEB)

During the last few years we have witnessed in Europe the development of a new generation of wind turbines ranging from 1000-1500 kW size. They are presently being tested and they are scheduled to reach the market in late 1996 early 1997. The European Commission has played a key role by funding the research leading to the development of these turbines. The most visible initiative at present is the WEGA programme - the development, together with Europe`s leading wind players of a new generation of turbines in the MW range. By the year 1997 different European manufacturers will have introduced almost a dozen new MW machine-types to the international market, half of them rated at 1.5 MW. (author)

Zervos, A. [National Technical University of Athens (Greece)

1996-12-31

319

Infrasound from Wind Turbines Could Affect Humans  

Science.gov (United States)

Wind turbines generate low-frequency sounds that affect the ear. The ear is superficially similar to a microphone, converting mechanical sound waves into electrical signals, but does this by complex physiologic processes. Serious misconceptions about low-frequency sound and the ear have resulted from a failure to consider in detail how the ear…

Salt, Alec N.; Kaltenbach, James A.

2011-01-01

320

Evaluation of airfoils for small wind turbines  

Science.gov (United States)

A new set of blades have been designed, fabricated, and tested at the United States Department of Agriculture-Agricultural Research Service-Conservation and Production Research Laboratory in Bushland, Texas in an attempt to improve the overall performance of small (1-10 kilowatt) wind turbines. The ...

321

Certification and type approval of wind turbines  

International Nuclear Information System (INIS)

Information is given on the certification and type approval of wind turbines in Europe and on the following certification bodies: CIWI-Holland (Arnhem), Det Norske Veritas (Copenhagen Denmark), The Test Station at Risoe National Laboratory (Roskilde, Denmark), and Germanischer Lloyd (Hamburg, Germany). (AB)

322

Perceptions of environmental impacts of wind turbines  

International Nuclear Information System (INIS)

Local wind turbine planning often stresses noise and visual impacts, without considering the externalities of central energy supply options. This situation calls for a coordination between national and local planning procedures, as well as for a program of information and education directed at the planning profession. (author)

323

Dynamic Response of Flexible Wind Turbine Blade  

Directory of Open Access Journals (Sweden)

Full Text Available Aiming at the non-stationary and stall flutter problems of wind turbine blade caused by transient load fluctuations, the dynamic properties of wind turbine were studied, the blade was simplify to a cantilever beam in case of the action of shear deformation and cross section rotating effect were considered in this analysis, equations of the blade were established based on D'Alemberts' principle and the principle of virtual displacement. The dynamic response of the wind turbine was solved by using the finite element method under the transient load environment. A 29.2 m rotor blade, previously reported in specialized literature, was chosen as a case study to validate dynamic behaviour predicted by a Timoshenko beam model. It is concluded that despite its simplicity, The cross-sectional shear-deformation  has great influence on  dynamic response of the blade.Dynamic model is sufficiently accurate to serve as a design tool for the recursive analyses required during design and optimization stages of wind turbines using only readily available computational tools.

Yu-qiao Zheng

2013-07-01

324

Wooden wind turbine blade manufacturing process  

Science.gov (United States)

A wooden wind turbine blade is formed by laminating wood veneer in a compression mold having the exact curvature needed for one side of the blade, following which the other side of the blade is ground flat along its length but twisted with respect to the blade axis.

Coleman, Clint (Warren, VT)

1986-01-01

325

Wind Turbine Blade with Angled Girders  

DEFF Research Database (Denmark)

The present invention relates to a reinforced blade for a wind turbine, particularly to a blade having a new arrangement of two or more girders in the blade, wherein each of the girders is connected to the upper part and the lower part of the shell and forms an angle with another girder thereby strengthening the shell against transverse shear distortion.

Jensen, Find MØlholt Technical University of Denmark,

326

Flutter of Darrieus wind turbine blades  

Science.gov (United States)

The testing of Darrieus wind turbines has indicated that under certain conditions, serious vibrations of the blades can occur, involving flatwise bending, torsion, and chordwise bending. A theoretical method of predicting the aeroelastic stability of the coupled bending and torsional motion of such blades with a view to determining the cause of these vibrations, and a means of suppressing them was developed.

Ham, N. D.

1978-01-01

327

Applied modal analysis of wind turbine blades  

Energy Technology Data Exchange (ETDEWEB)

In this project modal analysis has been used to determine the natural frequencies, damping and the mode shapes for wind turbine blades. Different methods to measure the position and adjust the direction of the measuring points are discussed. Different equipment for mounting the accelerometers are investigated and the most suitable are chosen. Different excitation techniques are tried during experimental campaigns. After a discussion the pendulum hammer were chosen, and a new improved hammer was manufactured. Some measurement errors are investigated. The ability to repeat the measured results is investigated by repeated measurement on the same wind turbine blade. Furthermore the flexibility of the test set-up is investigated, by use of accelerometers mounted on the flexible adapter plate during the measurement campaign. One experimental campaign investigated the results obtained from a loaded and unloaded wind turbine blade. During this campaign the modal analysis are performed on a blade mounted in a horizontal and a vertical position respectively. Finally the results obtained from modal analysis carried out on a wind turbine blade are compared with results obtained from the Stig Oeyes blade{sub E}V1 program. (au)

Broen Pedersen, H.; Dahl Kristensen, O.J.

2003-02-01

328

Compensation of Flicker Emitted by Wind Turbines.  

Czech Academy of Sciences Publication Activity Database

Sydney : The University of Newcastle Australia, 2004, s. 429-432. [Symposium IFAC (International Federation of Automatic Control) on Mechatronic Systems /3./. Sydney (AU), 06.09.2004-08.09.2004] R&D Projects: GA AV ?R IAA2057102 Keywords : wind turbines * flicker * induction generators Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

Chomát, Miroslav; Bendl, Ji?í; Schreier, Lud?k

329

Applied modal analysis of wind turbine blades  

DEFF Research Database (Denmark)

In this project modal analysis has been used to determine the natural frequencies, damping and the mode shapes for wind turbine blades. Different methods to measure the position and adjust the direction of the measuring points are discussed. Differentequipment for mounting the accelerometers are investigated and the most suitable are chosen. Different excitation techniques are tried during experimental campaigns. After a discussion the pendulum hammer were chosen, and a new improved hammer wasmanufactured. Some measurement errors are investigated. The ability to repeat the measured results is investigated by repeated measurement on the same wind turbine blade. Furthermore the flexibility of the test set-up is investigated, by use ofaccelerometers mounted on the flexible adapter plate during the measurement campaign. One experimental campaign investigated the results obtained from a loaded and unloaded wind turbine blade. During this campaign the modal analysis are performed on ablade mounted in a horizontal and a vertical position respectively. Finally the results obtained from modal analysis carried out on a wind turbine blade are compared with results obtained from the Stig Øyes blade_EV1 program.

Pedersen, H.B.; Kristensen, O.J.D.

2003-01-01

330

Multidisciplinary Constrained Optimization of Power Quality in Doubly Fed Wind Turbine Induction Generator  

Directory of Open Access Journals (Sweden)

Full Text Available Shape optimization of turbine blade to maximize the output power usually changes the power factor due to compensate Repower in a wind turbine. This article presents a multidisciplinary optimization technique to maximize the output power in Doubly Fed Induction Generator (DFIG wind turbine. The most common parameters when operating the turbine, namely, active power, reactive power and power factor, are considered as the problem constraints and the pitch angle grid side variable frequency converter of the turbine blades are optimized to maximize the output power. Numerical simulation has been illustrated to present the performance of the proposed design approach.

Abolghasem Zabihollah

2013-05-01

331

Detection of Wind Turbine Power Performance Abnormalities Using Eigenvalue Analysis  

DEFF Research Database (Denmark)

Condition monitoring of wind turbines is a field of continu- ous research and development as new turbine configurations enter into the market and new failure modes appear. Systems utilising well established techniques from the energy and in- dustry sector, such as vibration analysis, are commercially available and functioning successfully in fixed speed and vari- able speed turbines. Power performance analysis is a method specifically applicable to wind turbines for the detection of power generation changes due to external factors, such as ic- ing, internal factors, such as controller malfunction, or delib- erate actions, such as power de-rating. In this paper, power performance analysis is performed by sliding a time-power window and calculating the two eigenvalues corresponding to the two dimensional wind speed - power generation dis- tribution. The power is classified into five bins in order to achieve better resolution and thus identify the most proba- ble root cause of the power deviation. An important aspect of the proposed technique is its independence of the power curve provided by the turbine manufacturer. It is shown that by detecting any changes of the two eigenvalues trends in the five power bins, power generation anomalies are consistently identified

Skrimpas, Georgios Alexandros; Sweeney, Christian Walsted

2014-01-01

332

Development of the Risø wind turbine airfoils  

Science.gov (United States)

This paper presents the wind turbine airfoil development at Risø. The design method is described together with our target characteristics for wind turbine airfoils. The use of the CFD code Ellipsys2D for prediction of final target characteristics is described together with the VELUX wind tunnel testing setup. Three airfoil families were developed; Risø-A1, Risø-P and Risø-B1. The Risø-A1 airfoil family was developed for rotors of 600 kW and larger. Wind tunnel testing and field testing showed that this airfoil family is well suited for stall and active stall control. However, sensitivity to roughness was higher than expected. Field tests of a 600 kW active stall wind turbine showed an estimated reduction in blade fatigue loading of up to 15% at the same annual energy yield and at the same time reduced blade weight and blade solidity. The Risø-P airfoils were developed to replace the Risø-A1 airfoils for use on pitch controlled wind turbines. Improved design objectives should reduce the sensitivity to roughness, but measurements are not yet available. The Risø-B1 airfoil family was developed for variable speed operation with pitch control of large megawatt sized rotors. Wind tunnel testing verified the high maximum lift for these airfoils, and the airfoils were found to be very insensitive to leading edge roughness. Performance with vortex generators and Gurney flaps in combination was found to be attractive for the blade root part. Field testing of a 1.5 MW rotor is in progress. Copyright

Fuglsang, Peter; Bak, Christian

2004-04-01

333

Optimization and Reliability Problems in Structural Design of Wind Turbines  

DEFF Research Database (Denmark)

Reliability-based cost-benefit optimization formulations for wind turbines are presented. Some of the improtant aspects for stochastic modeling of loads, strengths and models uncertainties for wind turbines are described. Single wind turbines and wind turbines in wind farms with wake effects are discussed. Limit state equations are presented for fatigue limit states and for ultimate limit states with extreme wind load, and illustrated by bending failure. Illustrative examples are presented, and as a part of the results optimal reliability levels are obtained which corresponds to an annual reliability index equal to 3. An example with fatigue failure indicates that the reliability level is almost the same for single wind turbines and for wind turbines in wind farms if the wake effects are modeled equivalently in the design equation and the limit state equation.

SØrensen, John Dalsgaard

2007-01-01

334

European wind turbine standards II. Project results  

Energy Technology Data Exchange (ETDEWEB)

The number of installed wind turbines, world wide as well as in Europe, is increasing rapidly. At the end of 1997, the total amount of wind power had reached 7600 MW, of which almost 4800 MW is installed in Europe. Wind energy has realized a substantial improvement in system reliability as well as a considerable reduction in costs over recent years. The electricity production in regions with high average wind speeds is now competitive with conventional production methods. The increase in industrial activity in wind energy in turn generates a demand for standardized methods of design, testing and certification of wind turbines. This demand is partly covered by the activities of standardization bodies (CEN/CEGELEC, IEC), however a number of bottlenecks in knowledge and technical harmonization still exists. It was the objective of the European Wind Turbine Standards project (EWTS), the predecessor of the current project, to remove some of the constraints and bottlenecks and contribute to harmonization. EWTS was completed in the beginning of 1996, but during its execution a number of technical items evolved that still required further investigation. Therefore, a continuation of the project was defined: EWTS-II, to address items that could not be completed. These items were: (1) load spectra and extreme wind conditions; (2) quantification of failure probabilities; (3) integration of blade tests in design; (4) power performance in complex terrain; and (5) site evaluation. This report presents the results of these investigations. Furthermore, the previous EWTS project started to establish an organisation of qualified measurement institutes in the field of wind energy, the MEASNET organisation. MEASNET unifies measurement procedures of the participating institutes and guarantees qualified measurements and mutual acceptance among its members. MEASNET was formally established during EWTS-II. A summary on its results is included in the executive summary. More details on the structure of MEASNET, its in-house measurement procedures and the rules for acceptance are presented in a separate report. refs.

Dekker, J.; Pierik, J. [eds.] [ECN Solar and Wind, Petten (Netherlands)

1998-06-01

335

Laminar-Turbulent transition on Wind Turbines  

DEFF Research Database (Denmark)

The present thesis deals with the study of the rotational effects on the laminar-turbulent transition on wind turbine blades. Linear stability theory is used to formulate the stability equations that include the effect of rotation. The mean flow required as an input to stability computations is obtained by a similarity transformation technique. This approach allows to transform the boundary layer equations that have included the effect of the Coriolis and centrifugal forces into a set of couple partial differential equations, that are more convenient to solve numerically. The solution have been parametrized and adapted to an wind turbine rotor geometry. The blade is resolved in radial sections along which calculations are performed. The obtained mean flow is classified according to the parameters used on the rotating configuration, geometry and operational conditions. The stability diagrams have been obtained by solving the stability equations as an eigenvalue problem. The Keller boxScheme that is second order accurate was used as a numerical method. Have found to be stable and effective in terms of computing time. The solution of the eigenvalue problem provide connection between the parameters used to define the resultant wave magnitude and direction. The propagation of disturbances in the boundary layers in three dimensional flows is relatively a complicated phenomena. The report discusses the available methods and techniques used to predict the transition location. Some common wind turbine airfoils are selected to performe parametrical studies with rotational effects. Finally a wind turbine rotor is used for comparison with transition experiments. The relative motion between the flow and the blade geometry defines the response of the flow to disturbances. Have been found that flow on the suction side of the blade has a stabilizating effect, while on the region from the stagnation point to the rotor plane has a destabilizating effect on the boundary layer. The tendency is that rotational effect stabilize the boundary layer on the wind turbine blade.

Martinez Hernandez, Gabriel Gerardo

2012-01-01

336

European wind turbine testing procedure developments. Task 1: Measurement method to verify wind turbine performance characteristics  

DEFF Research Database (Denmark)

There is currently significant standardisation work ongoing in the context of wind farm energy yield warranty assessment and wind turbine power performance testing. A standards maintenance team is revising the current IEC (EN) 61400-12 Ed 1 standard forwind turbine power performance testing. The standard is being divided into four documents. Two of them are drafted for evaluation and verification of complete wind farms and of individual wind turbines within wind farms. This document, and the project itdescribes, has been designed to help provide a solid technical foundation for this revised standard. The work was wide ranging and addressed 'grey' areas of knowledge, regarding existing methodologies or to carry out basic research in support offundamentally new procedures. The work has given rise to recommendations in all areas of the work, including site calibration procedures, nacelle anemometry, multi-variate regression analysis and density normalisation.

Hunter, R.; Friis Pedersen, Troels

2001-01-01

337

Dust Effect on the Performance of Wind Turbine Airfoils  

Directory of Open Access Journals (Sweden)

Full Text Available The full two-dimensional Navier-Stokes algorithm and the SST k-? turbulence model were used to investigate incom-pressible viscous flow past the wind turbine two-dimensional airfoil under clean and roughness surface conditions. The NACA 63-430 airfoil is chosen to be the subject, which is widely used in wind turbine airfoil and generally located at mid-span of the blade with thickness to chord length ratio of about 0.3. The numerical simulation of the airfoil under clean surface condition has been done. As a result, the numerical results had a good consistency with the experimental data. The wind turbine blade surface dust accumulation according to the operational periods in natural environment has been taken into consideration. Then, the lift coefficients and the drag coefficients of NACA 63-430 airfoil have been computed under different roughness heights, different roughness areas and different roughness locations. The role that roughness plays in promoting premature transition to turbulence and flow separation has been verified by the numeri-cal results. The trends of the lift coefficients and the drag coefficients with the roughness height and roughness area increasing have been obtained. What’s more, the critical values of roughness height, roughness area, and roughness location have been proposed. Furthermore, the performance of the airfoil under different operational periods has been simulated, and an advice for the period of cleaning wind turbine blades is proposed. As a result, the numerical simula-tion method has been verified to be economically available for investigation of the dust effect on wind turbine airfoils.

Jinping Ou

2009-06-01

338

Integrating Structural Health Management with Contingency Control for Wind Turbines  

OpenAIRE

Maximizing turbine up-time and reducing maintenance costs are key technology drivers for wind turbine operators. Components within wind turbines are subject to considerable stresses due to unpredictable environmental conditions resulting from rapidly changing local dynamics. In that context, systems health management has the aim to assess the state-of-health of components within a wind turbine, to estimate remaining life, and to aid in autonomous decision-making to minimize damage to the turb...

Kai Goebel; Frost, Susan A.; Léo Obrecht

2013-01-01

339

Dynamic Behavior of DFIG Wind Turbine Under Grid Fault Conditions  

OpenAIRE

The use of doubly fed induction generators (DFIGs) in wind turbines has become quite common over the last few years. These machines provide variable speed and are driven with a power converter which is sized for a small percentage of the turbine-rated power. This paper presents a detailed model of induction generator coupled to wind turbine system. Modeling and simulation of induction machine using vector control computing technique is done. DFIG wind turbine is an integrated part of distribu...

Omer Elfaki Elbashir; Wang Zezhong; Liu Qihui

2014-01-01

340

The Mod-2 wind turbine development project  

Science.gov (United States)

A major phase of the Federal Wind Energy Program, the Mod-2 wind turbine, a second-generation machine developed by the Boeing Engineering and Construction Co. for the U.S. Department of Energy and the Lewis Research Center of the National Aeronautics and Space Administration, is described. The Mod-2 is a large (2.5-MW power rating) horizontal-axis wind turbine designed for the generation of electrical power on utility networks. Three machines were built and are located in a cluster at Goodnoe Hills, Washington. All technical aspects of the project are described: design approach, significant innovation features, the mechanical system, the electrical power system, the control system, and the safety system.

Linscott, B. S.; Dennett, J. T.; Gordon, L. H.

1981-01-01

341

Mod-2 wind turbine development project  

Energy Technology Data Exchange (ETDEWEB)

A major phase of the Federal Wind Energy Program, the Mod-2 wind turbine, a second-generation machine developed by the Boeing Engineering and Construction Co. for the US Department of Energy and the Lewis Research Center of the National Aeronautics and Space Administration, is described. The Mod-2 is a larger (2.5-MW power rating) horizontal-axis wind turbine designed for the generation of electrical power on utility networks. Three machines have been built and are located in a cluster at Goodnoe Hills, Washington. All technical aspects of the project are described: design approach, significant innovation features, the mechanical system, the electrical power system, the control system, and the safety system.

Linscott, B.S.; Dennett, J.T.; Gordon, L.H.

1981-07-01

342

A Shrouded Wind Turbine Generating High Output Power with Wind-lens Technology  

OpenAIRE

We have developed a new wind turbine system that consists of a diffuser shroud with a broad-ring brim at the exit periphery and a wind turbine inside it. The shrouded wind turbine with a brimmed diffuser has demonstrated power augmentation by a factor of about 2–5 compared with a bare wind turbine, for a given turbine diameter and wind speed. This is because a low-pressure region, due to a strong vortex formation behind the broad brim, draws more mass flow to the wind turbine inside the dif...

Yuji Ohya; Takashi Karasudani

2010-01-01

343

Large mills attract the wind. Wind and noise measurements of high wind turbines  

International Nuclear Information System (INIS)

It appears that under specific weather conditions wind turbines produce more noise than expected, according to the theory that wind speed increases with height on a logarithmic scale. However, from the results of the project on the title subject it appears that this correlation between wind speed and height is not correct for a stabile atmosphere: in that case wind speed increases more with height and subsequently the turbine will produce more noise

344

Design Optimization of a Cost-Effective Micro Wind Turbine  

OpenAIRE

The aim of this paper is to investigate the performance of a specially designed micro wind turbine for urban environment where the wind speed is usually low. Differing from the traditional wind turbine that can be connected directly to the grid, the micro wind turbine is linked to a small generator and mainly used for local applications. The advantage of the micro wind turbine is that, apart from its low cost, it can be propelled by a wind speed as low as 2 m/s. In this paper, the performance...

Leung, D. Y. C.; Deng, Y.; Leung, M. K. H.

2010-01-01

345

A ``Cyber Wind Facility'' for HPC Wind Turbine Field Experiments  

Science.gov (United States)

The Penn State ``Cyber Wind Facility'' (CWF) is a high-fidelity multi-scale high performance computing (HPC) environment in which ``cyber field experiments'' are designed and ``cyber data'' collected from wind turbines operating within the atmospheric boundary layer (ABL) environment. Conceptually the ``facility'' is akin to a high-tech wind tunnel with controlled physical environment, but unlike a wind tunnel it replicates commercial-scale wind turbines operating in the field and forced by true atmospheric turbulence with controlled stability state. The CWF is created from state-of-the-art high-accuracy technology geometry and grid design and numerical methods, and with high-resolution simulation strategies that blend unsteady RANS near the surface with high fidelity large-eddy simulation (LES) in separated boundary layer, blade and rotor wake regions, embedded within high-resolution LES of the ABL. CWF experiments complement physical field facility experiments that can capture wider ranges of meteorological events, but with minimal control over the environment and with very small numbers of sensors at low spatial resolution. I shall report on the first CWF experiments aimed at dynamical interactions between ABL turbulence and space-time wind turbine loadings. Supported by DOE and NSF.

Brasseur, James; Paterson, Eric; Schmitz, Sven; Campbell, Robert; Vijayakumar, Ganesh; Lavely, Adam; Jayaraman, Balaji; Nandi, Tarak; Jha, Pankaj; Dunbar, Alex; Motta-Mena, Javier; Craven, Brent; Haupt, Sue

2013-03-01

346

Modern control design for flexible wind turbines  

Science.gov (United States)

Control can improve energy capture and reduce dynamic loads in wind turbines. In the 1970s and 1980s wind turbines used classical control designs to regulate power and speed. The methods used, however, were not always successful. These systems often had bandwidths large enough to destabilize low-damped flexible modes leading to high dynamic load fatigue failures. Modern turbines are larger, mounted on taller towers, and are more dynamically active than their predecessors. Control systems to regulate turbine power and maintain stable closed-loop behavior in the presence of turbulent wind inflow will be critical for these designs. New advanced control approaches and paradigms must account for low-damped flexible modes in order to reduce structural dynamic loading and achieve the 20--25 year operational life required of today's machines. This thesis applies modern state-space control design methods to a two-bladed teetering hub upwind machine located at the National Wind Technology Center. The design objective is to regulate turbine speed and enhance damping in several low-damped flexible modes of the turbine. Starting with simple control algorithms based on linear models, complexity is added incrementally until the desired performance is firmly established. The controls approach is based on the Disturbance Accommodating Control (DAC) method and provides accountability for wind-speed fluctuations. First, controls are designed using the single control input rotor collective pitch to stabilize the 1st drive-train torsion as well as the tower 1st fore-aft bending modes. Generator torque is then incorporated as an additional control input. This reduces some of the demand placed on the rotor collective pitch control system and enhances 1st drive train torsion mode damping. Individual blade pitch control is then used to attenuate wind disturbances having spatial variation over the rotor and effectively reduces blade flap deflections due to wind shear. Finally, results from these modern controls are compared to results from simpler classical controls in order to assess modern controller performance. These modern controls are shown to more effectively mitigate tower fore-aft motion, drive-train shaft torsion moments, and blade root flap bending moments when compared to the classical control approaches.

Wright, Alan Duane

347

A New Structure Based on Cascaded Multilevel Converter for Variable Speed Wind Turbine  

DEFF Research Database (Denmark)

An alternative structure for variable speed wind turbine, using multiple permanent magnet synchronous generators (PMSGs) drive-train configuration and cascaded multilevel converter is proposed in this paper. This study presents a power electronic solution for the wind turbine. A transformer-less cascaded multilevel converter interface based on PMSGs is developed to synthesize a desired high ac sinusoidal output voltage. The benefits of high power and high ac voltage make this structure possible to be applied in the wind power generation. In addition, the bulky transformer could be omitted. A simulation model of 10 MW variable speed wind turbine based on PMSGs developed in PSCAD/EMTDC is presented. The dynamic performance of grid-connected wind turbine is analyzed. Simulation results shows that the proposed structure may be attractive in wind power generation.

Deng, Fujin; Chen, Zhe

2010-01-01

348

Minimum Thrust Load Control for Floating Wind Turbine  

DEFF Research Database (Denmark)

— Offshore wind energy capitalizes on the higher and less turbulent wind at sea. Shallow water sites are pro?table for deployment of monopile wind turbines at water depths of up to 30 meters. Beyond 30 meters, the wind is even stronger and less turbulent. At these depths, ?oating wind turbines become pro?table, capable of accessing unexploited wind resources while reaching regions of new consumers. However, ?oating wind turbines are subject to reduced structural stiffness which results in instabilities when standard wind turbine control systems are applied. Based on optimal control, this paper presents a new minimum thrust control strategy capable of stabilizing a ?oating wind turbine. The new control strategy explores the freedom of variable generator speed above rated wind speed. A comparison to the traditional constant speed strategy, shows improvements in structural fore-aft oscillations and power stability when using the new control strategy.

Christiansen, SØren; Bak, Thomas

2012-01-01

349

A new generation of wind turbines; Une nouvelle generation d'eoliennes  

Energy Technology Data Exchange (ETDEWEB)

Although homeowners have expressed a desire to use wind energy to supply their electricity needs, many technical barriers have stood in the way of installing wind turbines in urban settings. This was due in part to three-bladed vertical axis turbines, high technical costs, limited performances in urban settings and questionable aesthetics. Tesnic has considered these issues and proposed a completely different turbine that uses a different method for extracting energy from the wind. The first approved 3.6 kW model should appear by the end of 2009. This new turbine is based on the same principal of the steam turbine patented in 1913 by Nikola Tesla. Instead of having blades, the Tesla turbine used closely spaced parallel disks and was recognized as being very robust with a high efficiency rating. Tesnic's new wind powered turbine is a vertical axis turbine with a series of valves that directs the wind on a rotor assembly of disk space. A series of blades on its circumference redirects the wind through the assembly of discs and accelerates the rotation of the rotor. The turbine extracts the wind energy in several ways, including conventional drag and lift, adherence and the vortex effect. This gives a 50 per cent added value of efficiency compared to other wind powered turbines. The global market for small wind powered energy is in full expansion. It has been projected that small turbines with 1 kW capacity will be abundant by 2020. It was noted that for household wind powered energy, the market must consider issues of cost, low maintenance, noise pollution, visual aesthetics, durability and safety. Wind energy can also be used in several industries, including plastics, composites, light metals, textiles and electronics. 2 figs.

Nica, H. [Tesnic, Laval, PQ (Canada)

2008-06-15

350

Generators of Modern Wind Turbines  

OpenAIRE

In this paper, various types of wind generator configurations, including power electronic grid interfaces, drive trains, are described The performance in power systems is briefed. Then the optimization of generator system is presented. Some investigation results are presented and discussed.

Chen, Zhe

2008-01-01

351

Reduction of Wind Turbine Torque Fluctuation Using Individual Pitch Control Based on Edgewise Moment  

Directory of Open Access Journals (Sweden)

Full Text Available In order to eliminate the nonuniform force on the wind rotor caused by wind shear, tower shadow and turbulence and smooth the torque fluctuation of the wind turbine and the unbalanced loads on the wind turbine, a new individual pitch control strategy based on edgewise moment using single neuron PID controller is proposed. That is, the presented control strategy directly controls the blade edgewise moment generated by aerodynamic force. At the same time, to simulate the wind turbine loads, a dynamic model of three-bladed upwind horizontal axis wind turbine is built. Thus, the influence rules of the wind turbine torque fluctuation are deduced at length. Finally, to verify the effectiveness of the proposed individual pitch control system with the single neuron PID controller, the 2MW wind turbine generator system is modeled and simulated. The performance of the controller is illustrated its capability of not only reducing the wind turbine fluctuation, but also smoothing the fluctuation of the flapwise moment, the yaw moment and the tilt moment.

Zhibin Ling

2013-05-01

352

Semiconductor Laser Lidar Wind Velocity Sensor for Turbine Control  

DEFF Research Database (Denmark)

A dual line-of-sight CW lidar that measures both wind speed and direction is presented . The wind lidar employs a semiconductor laser, which allows for inexpensive remote sensors geared towards enhanced control of wind turbines .

Rodrigo, Peter John; Hu, Qi

2014-01-01

353

Database on wind characteristics - Analyses of wind turbine design loads  

Energy Technology Data Exchange (ETDEWEB)

The main objective of IEA R and D Wind Annex XVII - Database on Wind Characteristics - has been to provide wind energy planners, designers and researchers, as well as the international wind engineering community in general, with a source of actual wind field data (time series and resource data) observed in a wide range of different wind climates and terrain types. Connected to an extension of the initial Annex period, the scope for the continuation was widened to include also support to the international wind turbine standardisation efforts.. The project partners are Sweden, Norway, U.S.A., The Netherlands and Denmark, with Denmark as the Operating Agent. The reporting of the continuation of Annex XVII falls in two separate parts. Part one accounts in details for the available data in the established database bank, and part two describes various data analyses performed with the overall purpose of improving the design load cases with relevance for to wind turbine structures. The present report constitutes the second part of the Annex XVII reporting. Both fatigue and extreme load aspects are dealt with, however, with the main emphasis on the latter. The work has been supported by The Ministry of Environment and Energy, Danish Energy Agency, The Netherlands Agency for Energy and the Environment (NOVEM), The Norwegian Water Resources and Energy Administration (NVE), The Swedish National Energy Administration (STEM) and The Government of the United States of America. (au)

Larsen, G.C.; Hansen, K.S.

2004-06-01

354

Integrating Structural Health Management with Contingency Control for Wind Turbines  

Directory of Open Access Journals (Sweden)

Full Text Available Maximizing turbine up-time and reducing maintenance costs are key technology drivers for wind turbine operators. Components within wind turbines are subject to considerable stresses due to unpredictable environmental conditions resulting from rapidly changing local dynamics. In that context, systems health management has the aim to assess the state-of-health of components within a wind turbine, to estimate remaining life, and to aid in autonomous decision-making to minimize damage to the turbine. Advanced contingency control is one way to enable autonomous decision-making by providing the mechanism to enable safe and efficient turbine operation. The work reported herein explores the integration of condition monitoring of wind turbine blades with contingency control to balance the trade-offs between maintaining system health and energy capture. Results are demonstrated using a high fidelity simulator of a utility-scale wind turbine.

Kai Goebel

2013-01-01

355

On Using Wind Speed Preview to Reduce Wind Turbine Tower Oscillations  

OpenAIRE

We investigate the potential of using previewed wind speed measurements for damping wind turbine fore-aft tower oscillations. Using recent results on continuous-time H2 preview control, we develop a numerically efficient framework for the feedforward controller synthesis. One of the major benefits of the proposed framework is that it allows us to account for measurement distortion. This results in a controller that is tailored to the quality of the previewed data. A simple yet meaningful para...

Kristalny, Maxim; Madjidian, Daria; Knudsen, Torben

2013-01-01

356

Inertial response of variable speed wind turbines  

Energy Technology Data Exchange (ETDEWEB)

The increasing penetration of variable speed wind turbines in the electricity grid will result in a reduction of the number of connected conventional power plants. This will lead to a reduction of inertia in the grid, as the rotational speed of a variable speed turbine and the grid are decoupled by a power electronic converter. A lower system inertia will result in larger and faster frequency deviations after occurrence of abrupt variations in generation and load. It is possible to implement an additional control loop in the power electronic converter of the turbine, which connects the turbine inertia directly to the grid. It is even possible, by control, to make a 'virtual inertia' that is larger than the real inertia. During a frequency drop additional power can be released to the grid with this control. This behaviour will be called inertial response. The additional power is obtained from the kinetic energy that is stored in the rotating mass of the turbine. In this contribution two different control strategies are investigated and compared with each other. A type of control that is equal to the primary frequency control of large power plants shows the best results, both with respect to the power that is needed to limit the frequency drop and with respect to electrical and mechanical stress of the turbine. (author)

Morren, Johan; de Haan, Sjoerd W.H. [Electrical Power Processing, Delft University of Technology, P.O. Box 5031, 2600 GA, Delft (Netherlands); Pierik, Jan [Energy Research Centre of the Netherlands (ECN), Section Wind Energy, Petten (Netherlands)

2006-07-15

357

SUSTAINABLE CONCRETE FOR WIND TURBINE FOUNDATIONS.  

Energy Technology Data Exchange (ETDEWEB)

The use of wind power to generate electricity continues to grow, especially given commitments by various countries throughout the world to ensure that a significant percentage of energy comes from renewable sources. In order to meet such objectives, increasingly larger turbines with higher capacity are being developed. The engineering aspects of larger turbine development tend to focus on design and materials for blades and towers. However, foundations are also a critical component of large wind turbines and represent a significant cost of wind energy projects. Ongoing wind research at BNL is examining two areas: (a) structural response analysis of wind turbine-tower-foundation systems and (b) materials engineering of foundations. This work is investigating the dynamic interactions in wind turbine systems, which in turn assists the wind industry in achieving improved reliability and more cost efficient foundation designs. The results reported herein cover initial studies of concrete mix designs for large wind turbine foundations and how these may be tailored to reduce cost and incorporate sustainability and life cycle concepts. The approach taken was to investigate material substitutions so that the environmental, energy and CO{sub 2}-impact of concrete could be reduced. The use of high volumes of ''waste'' materials in concrete was examined. These materials included fly ash, blast furnace slag and recycled concrete aggregate. In addition, the use of steel fiber reinforcement as a means to improve mechanical properties and potentially reduce the amount of bar reinforcement in concrete foundations was studied. Four basic mixes were considered. These were: (1) conventional mix with no material substitutions, (2) 50% replacement of cement with fly ash, (3) 50% replacement of cement with blast furnace slag and (4) 25% replacement of cement with fly ash and 25% replacement with blast furnace slag. Variations on these mixes included the addition of 1% by volume steel fibers. The use of recycled concrete aggregate in the conventional and 50% slag mixes was also studied. Properties investigated included compressive and tensile strengths, elastic modulus, coefficient of permeability, thermal conductivity and durability in seawater and sulfate solutions. It was determined that the mixes containing 50% slag gave the best overall performance. Slag was particularly beneficial for concrete that used recycled aggregate and could reduce strength losses. Initial durability results indicated that corrosion of fibers in the different concrete mixes when exposed to seawater was minimal. Future research needs to include more detailed studies of mix design and properties of concrete for wind turbine foundations. Emphasis on slag-modified mixes with natural and recycled concrete aggregate is recommended. The proportion of slag that can be incorporated in the concrete needs to be optimized, as does the grading of recycled aggregate. The potential for using silica fume in conjunction with slag is worth exploring as this may further enhance strength and durability. Longer-term durability studies are necessary and other pertinent properties of concrete that require investigation include damping characteristics, pullout strength, fatigue strength and risk of thermal cracking. The properties of sustainable concrete mixes need to be integrated with studies on the structural behavior of wind turbine foundations in order to determine the optimal mix design and to examine means of reducing conservatism and cost of foundations.

BERNDT,M.L.

2004-06-01

358

Wind turbine control and model predictive control for uncertain systems  

OpenAIRE

This thesis presents both an applied study and a theoretical study within the field of control theory. Control theory is an interdisciplinary branch between mathematics and engineering dealing with the manipulation of systems to produce a desired output. The applied study deals with wind turbine control. Wind turbines are controlled to optimize energy extraction from the wind. This must be done while respecting physical restrictions and ensuring that loads on the wind turbin...

Thomsen, Sven Creutz; Poulsen, Niels Kjølstad; Niemann, Hans Henrik

2010-01-01

359

Condition Parameter Modeling for Anomaly Detection in Wind Turbines  

OpenAIRE

Data collected from the supervisory control and data acquisition (SCADA) system, used widely in wind farms to obtain operational and condition information about wind turbines (WTs), is of important significance for anomaly detection in wind turbines. The paper presents a novel model for wind turbine anomaly detection mainly based on SCADA data and a back-propagation neural network (BPNN) for automatic selection of the condition parameters. The SCADA data sets are determined through analysis o...

Yonglong Yan; Jian Li; David Wenzhong Gao

2014-01-01

360

Grid integration impacts on wind turbine design and development  

OpenAIRE

This paper presents an overall perspective on contemporary issues like wind power plants and grid integration. The purpose is to present and discuss the impacts of emerging new grid connection requirements on modern wind turbines. The grid integration issue has caused several new challenges to the wind turbine design and development. The survival of different wind turbine concepts and controls is strongly conditioned by their ability to comply with stringent grid connection requirements, impo...

Hansen, Anca Daniela; Cutululis, Nicolaos Antonio; Sørensen, Poul Ejnar; Iov, F.

2009-01-01

361

Noise Pollution Prevention in Wind Turbines: Status and Recent Advances  

OpenAIRE

The global push towards sustainability has led to increased interest in alternative power sources other than coal and fossil fuels. One of these sustainable sources is to harness energy from the wind through wind turbines. However, a significant hindrance preventing the widespread use of wind turbines is the noise they produce. This study reviews recent advances in the area of noise pollution from wind turbines. To date, there have been many different noise control studies. While there are ma...

Greg Naterer; Rosen, Marc A.; Ofelia Jianu

2012-01-01

362

Modeling and Operational Testing of an Isolated Variable Speed PMSG Wind Turbine with Battery Energy Storage  

OpenAIRE

This paper presents the modeling and operational testing of an isolated permanent magnet synchronous generator (PMSG), driven by a small wind turbine with a battery energy storage system during wind speed and load variations. The whole system is initially modeled, including the PMSG, the boost converter and the storage system. The required power for the connected loads can be effectively delivered and supplied by the proposed wind turbine and energy storage systems, subject to an appropri...

Barote, L.; Marinescu, C.

2012-01-01

363

Wind turbine angular frequency analysis by means of computer vision techniques  

Energy Technology Data Exchange (ETDEWEB)

The turbine synchronization phenomenon is of great interest in order to estimate the flicker produced by a wind farm. This paper proposes an initial approach to analyze the appearance of this phenomenon by the use of various image processing techniques: a method to automatically calculate the angular frequency of an unknown number of wind turbines from a video. The recorded video images were obtained at the Manzanal wind farm, province of Leon (Spain). (author)

Lopez, Carlos; Blanes, Jorge [Department of Electrical and Automatic Engineering, University of Leon, Campus de Vegazana s/n, 24071 Leon (Spain); Gonzalez, Raquel; Sanchez, Lidia [Department of Mechanical, Computing and Aerospace Engineering, University of Leon, Campus de Vegazana s/n, 24071 Leon (Spain)

2010-12-15

364

Advanced CFD methods for wind turbine analysis  

Science.gov (United States)

Horizontal-axis wind turbines operate in a complex, inherently unsteady aerodynamic environment. Even when the rotor is not stalled, the flow over the blades is dominated by three-dimensional (3-D) effects. Stall is accompanied by massive flow separation and vortex shedding over the suction surface of the blades. Under yawed conditions, dynamic stall may be present as well. In all operating conditions, there is bluff-body shedding from the turbine nacelle and support structure which interacts with the rotor wake. In addition, the high aspect ratios of wind turbine blades make them very flexible, leading to substantial aeroelastic deformation of the blades, altering the aerodynamics. Finally, when situated in a wind farm, turbines must operate in the unsteady wake of upstream neighbors. Though computational fluid dynamics (CFD) has made significant inroads as a research tool, simple, inexpensive methods, such as blade element momentum (BEM) theory, are still the workhorses in wind turbine design and aeroelasticity applications. These methods generally assume a quasi-steady flowfield and use two-dimensional aerodynamic approximations with very limited empirical 3-D corrections. As a result, they are unable to accurately predict rotor loads near the edges of the operating envelope. CFD methods make very few limiting assumptions about the flowfield, and thus have much greater potential for predicting these flows. In this work, a range of unstructured grid CFD techniques for predicting wind turbine loads and aeroelasticity has been developed and applied to a wind turbine configuration of interest. First, a nearest neighbor search algorithm based on a k-dimensional tree data structure was used to improve the computational efficiency of an approximate unsteady actuator blade method. This method was then shown to predict root and tip vortex locations and strengths similar to an overset method on the same background mesh, but without the computational expense of modeling the blade surfaces. A hybrid Reynolds-averaged Navier-Stokes / Large Eddy Simulation (HRLES) turbulence model, previously developed for structured grids, was extended to an unstructured framework. It was demonstrated to improve predictions of unsteady loading and shedding frequency in massively separated cases. The sensitivity of the model to highly stretched grid topologies was also explored. For aeroelastic predictions, a methodology for tight coupling between an unstructured CFD solver and a computational structural dynamics tool was developed. Due to the lack of experimental data pertaining to a flexible turbine, the coupling algorithm was validated for a helicopter rotor, but the method is sufficiently general that it can be immediately applied to a wind turbine when suitable correlation data becomes available in the future. Finally, time-accurate overset rotor simulations of a complete turbine---blades, nacelle, and tower---were conducted using both RANS and HRLES turbulence models. The HRLES model was able to accurately predict rotor loads when stalled. In yawed flow, excellent correlations of mean blade loads with experimental data were obtained across the span, and wake asymmetry and unsteadiness were also well-predicted.

Lynch, C. Eric

2011-12-01

365

Control of large wind turbine generators connected to utility networks  

Science.gov (United States)

This is an investigation of the control requirements for variable pitch wind turbine generators connected to electric power systems. The requirements include operation in very small as well as very large power systems. Control systems are developed for wind turbines with synchronous, induction, and doubly fed generators. Simulation results are presented. It is shown how wind turbines and power system controls can be integrated. A clear distinction is made between fast control of turbine torque, which is a peculiarity of wind turbines, and slow control of electric power, which is a traditional power system requirement.

Hinrichsen, E. N.

1983-01-01

366

Power optimization of wind turbines with data mining and evolutionary computation  

Energy Technology Data Exchange (ETDEWEB)

A data-driven approach for maximization of the power produced by wind turbines is presented. The power optimization objective is accomplished by computing optimal control settings of wind turbines using data mining and evolutionary strategy algorithms. Data mining algorithms identify a functional mapping between the power output and controllable and non-controllable variables of a wind turbine. An evolutionary strategy algorithm is applied to determine control settings maximizing the power output of a turbine based on the identified model. Computational studies have demonstrated meaningful opportunities to improve the turbine power output by optimizing blade pitch and yaw angle. It is shown that the pitch angle is an important variable in maximizing energy captured from the wind. Power output can be increased by optimization of the pitch angle. The concepts proposed in this paper are illustrated with industrial wind farm data. (author)

Kusiak, Andrew; Zheng, Haiyang; Song, Zhe [Department of Mechanical and Industrial Engineering, The University of Iowa, 3131 Seamans Center, Iowa City, IA 52242-1527 (United States)

2010-03-15

367

Calculation of transient potential rise on the wind turbine struck by lightning.  

Science.gov (United States)

A circuit model is proposed in this paper for calculating the transient potential rise on the wind turbine struck by lightning. The model integrates the blade, sliding contact site, and tower and grounding system of the wind turbine into an equivalent circuit. The lightning current path from the attachment point to the ground can be fully described by the equivalent circuit. The transient potential responses are obtained in the different positions on the wind turbine by solving the circuit equations. In order to check the validity of the model, the laboratory measurement is made with a reduced-scale wind turbine. The measured potential waveform is compared with the calculated one and a better agreement is shown between them. The practical applicability of the model is also examined by a numerical example of a 2 MW Chinese-built wind turbine. PMID:25254231

Xiaoqing, Zhang

2014-01-01

368

Detecting salt deposition on a wind turbine blade using laser induced breakdown spectroscopy technique  

Science.gov (United States)

The study of pollution performance on a wind turbine blade due to lightning is important, as it can cause major damage to wind turbine blades. In the present work, optical emission spectroscopy (OES) technique is used to understand the influence of pollutant deposited on a wind turbine blade in an off-shore environment. A methodical experimental study was carried out by adopting IEC 60507 standards, and it was observed that the lightning discharge propagates at the interface between the pollutant and the glass fiber reinforced plastic (Material used in manufacturing of wind turbine blades). In addition, as a diagnostic condition monitoring technique, laser-induced breakdown spectroscopy (LIBS) is proposed and demonstrated to rank the severity of pollutant on the wind turbine blades from a remote area. Optical emission spectra observed during surface discharge process induced by lightning impulse voltage is in agreement with the spectra observed during LIBS.

Sathiesh Kumar, V.; Vasa, Nilesh J.; Sarathi, R.

2013-07-01

369

Offshore Wind Turbines - Estimated Noise from Offshore Wind Turbine, Monhegan Island, Maine: Environmental Effects of Offshore Wind Energy Development  

Energy Technology Data Exchange (ETDEWEB)

Deep C Wind, a consortium headed by the University of Maine will test the first U.S. offshore wind platforms in 2012. In advance of final siting and permitting of the test turbines off Monhegan Island, residents of the island off Maine require reassurance that the noise levels from the test turbines will not disturb them. Pacific Northwest National Laboratory, at the request of the University of Maine, and with the support of the U.S. Department of Energy Wind Program, modeled the acoustic output of the planned test turbines.

Aker, Pamela M.; Jones, Anthony M.; Copping, Andrea E.

2010-11-23

370

Wavelet Transformation for Damage Identication in Wind Turbine Blades  

DEFF Research Database (Denmark)

The present paper documents a proposed modal and wavelet analysis-based structural health monitoring (SHM) method for damage identification in wind turbine blades. A finite element (FE) model of a full-scale wind turbine blade is developed and introduced to a transverse surface crack. Hereby, post-damage mode shapes are derived through modal analysis and subsequently analyzed with continuous two-dimensional wavelet transformation for damage identification, namely detection, localization and assessment. It is found that valid damage identification is obtained even when utilizing the mode shape of the first structural blade mode. However, due to the nature of the proposed method, it is also found that the accuracy of the damage assessment highly depends on the number of employed measurement points.

Ulriksen, Martin Dalgaard; Skov, Jonas falk

2014-01-01

371

Braking System for Wind Turbines  

Science.gov (United States)

Operating turbine stopped smoothly by fail-safe mechanism. Windturbine braking systems improved by system consisting of two large steel-alloy disks mounted on high-speed shaft of gear box, and brakepad assembly mounted on bracket fastened to top of gear box. Lever arms (with brake pads) actuated by spring-powered, pneumatic cylinders connected to these arms. Springs give specific spring-loading constant and exert predetermined load onto brake pads through lever arms. Pneumatic cylinders actuated positively to compress springs and disengage brake pads from disks. During power failure, brakes automatically lock onto disks, producing highly reliable, fail-safe stops. System doubles as stopping brake and "parking" brake.

Krysiak, J. E.; Webb, F. E.

1987-01-01

372

Methods of resynchronizing wind turbine generators  

Science.gov (United States)

A method is described for resynchronizing wind turbine generators (WTG) which reduces the time for reestablishing normal operation following an electrical disturbance. The WTG studied has a blade speed of 17.55 rpm geared to a four-pole, 2.5 MW synchronous generator; the blades are upwind, horizontal axis propeller type, each 150 ft long with 45 ft of controllable tip length. Load rejection is used as the electrical disturbance. Several methods of reclosing are discussed, and arbitrary reclosing is discouraged. Reclosing when the voltage phase difference between WTG and the network is within prescribed limits is found to be acceptable, despite its requirements for high speed switching equipment with a complex control system. The safest approach is one which involves bringing the hub speed to a constant value and then reverting to the normal pitch control immediately following reclosing. Reclosing the WTG with sufficent damping of the soft shaft mode can be accomplished more smoothly than for a WTG in which the mode is lightly damped. It is also shown that satisfactory reclosing and reloading of a WTG is practical by modifying the proposed pitch control to include hub speed damping in both the high and low modes.

Krause, P. C.; Wasynczuk, O.

1981-10-01

373

Aerodynamic models for a Darrieus wind turbine  

Science.gov (United States)

Various models proposed for the aerodynamics of Darrieus wind turbines are reviewed. The magnitude of the L/D ratio for a Darrieus rotor blade is dependent on the profile, the Re, boundary layer characteristics, and the three-dimensional flow effects. The aerodynamic efficiency is theoretically the Betz limit, and the interference of one blade with another is constrained by the drag force integrated over all points on the actuator disk. A single streamtube model can predict the power available in a Darrieus, but the model lacks definition of the flow structure and the cyclic stresses. Techniques for calculating the velocity profiles and the consequent induced velocity at the blades are presented. The multiple streamtube theory has been devised to account for the repartition of the velocity in the rotor interior. The model has been expanded as the double multiple streamtube theory at Sandia Laboratories. Futher work is necessary, however, to include the effects of dynamic decoupling at high rotation speeds and to accurately describe blade behavior.

Fraunie, P.; Beguier, C.; Paraschivoiu, I.; Delclaux, F.

1982-11-01

374

Wind shear for large wind turbine generators at selected tall tower sites  

Energy Technology Data Exchange (ETDEWEB)

The objective of the study described in this report is to examine the nature of wind shear profiles and their variability over the height of large horizontal-axis wind turbines and to provide information on wind shear relevant to the design and opertion of large wind turbines. Wind turbine fatigue life and power quality are related through the forcing functions on the blade to the shapes of the wind shear profiles and their fluctuations over the disk of rotation.

Elliott, D.L.

1984-04-01

375

Highway damage due to movement of wind turbine components  

OpenAIRE

This paper proposes a methodology for assessing the damage imposed by the movement of wind turbine components on Texas’s highway infrastructure. The pavement damage associated with traffic resulting from site preparation was omitted from the scope of this study because reliable data characterizing the construction traffic were not available. The damage to the pavement structure was estimated using three primary distresses: rutting, longitudinal, and alligator cracking. In addition, the impa...

Banerjee, A.; Prozzi, J. A.; Prozzi, Jolanda

2012-01-01

376

Mapping of grid faults and grid codes[Wind turbines  

Energy Technology Data Exchange (ETDEWEB)

The objective of this project is to investigate into the consequences of the new grid connection requirements for the fatigue and extreme loads of wind turbines. The goal is also to clarify and define possible new directions in the certification process of power plant wind turbines, namely wind turbines, which participate actively in the stabilisation of power systems. Practical experience shows that there is a need for such investigations. The grid connection requirements for wind turbines have increased significantly during the last 5-10 years. Especially the requirements for wind turbines to stay connected to the grid during and after voltage sags, imply potential challenges in the design of wind turbines. These requirements pose challenges for the design of both the electrical system and the mechanical structure of wind turbines. An overview over the frequency of grid faults and the grid connection requirements in different relevant countries is done in this report. The most relevant study cases for the quantification of the loads' impact on the wind turbines' lifetime are defined. The goal of this report is to present a mapping of different grid fault types and their frequency in different countries. The report provides also a detailed overview of the Low Voltage Ride-Through Capabilities for wind turbines in different relevant countries. The most relevant study cases for the quantification of the loads' impact on the wind turbines' lifetime are defined. (au)

Iov, F. [Aalborg Univ., Inst. of Energy Technology (Denmark); Hansen, Anca D.; Soerensen, Poul; Cutululis, N.A. [Risoe National Lab. - DTU, Wind Enegy Dept., Roskilde (Denmark)

2007-06-15

377

Structural Robustness Evaluation of Offshore Wind Turbines  

DEFF Research Database (Denmark)

Wind turbines are complex structures that should deal with adverse weather conditions, are exposed to impacts or ship collisions and, due to the strategic roles in the energetic supplying, can be the goal of military or malevolent attacks. Even if a structure cannot be design to resist any unforeseeable critical event or arbitrarily high accidental action, this kind of systems should be able to maintain integrity and a certain level of functionality also under accidental circumstances, which are not contemplated or cannot be considered in the usual design verification. According to a performance-based design view, the entity of actions to be resisted and the services levels to be maintained are the design objectives, which should be defined by the stakeholders and by the designer in respect of the regulation in force. For what said above, the structural integrity of wind turbines is a central issue in the framework of a safe design: it depends on different factors, like exposure, vulnerability and robustness.Particularly, the requirement of structural vulnerability and robustness are discussed in this paper and a numerical application is presented, in order to evaluate the effects of a ship collision on the structural system of an offshore wind turbine. The investigation resorts nonlinear dynamic analyses performed on the finite element model of the turbine and considers three different scenarios for the ship collision. The review of the investigation results allows for an evaluation of the turbine structural integrity after the impact and permits to identify some characteristics of the system, which are intrinsic to the chosen organization of the elements within the structure.

Giuliani, Luisa; Bontempi, Franco

2010-01-01

378

Enhanced wind turbine noise prediction tool SILANT  

International Nuclear Information System (INIS)

Wind turbine noise often is quantified in terms of time averaged overall sound power levels, whilst annoyance due to noise level fluctuations in mid- to high-range frequencies ('swish') are not taken into account. Recent experimental research on wind turbine noise has revealed the major causes of the swishing noise to be due to the directivity of the noise sources and convective amplification effects of the moving turbine blades. The findings have been incorporated in the noise prediction tool SILANT which in addition to sound power levels gives sound pressure level predictions for specified observer positions. The noise sources that are taken into account are trailing edge, inflow and tip noise, using the models of Brooks, Pope and Marcolini (BPM) and Amiet and Lowson. The blade is divided into a number of independent elements for which effective inflow velocity and angle of attack information is a necessary input. A distinction is made between the various profiles along the blade span by including their boundary layer displacement thicknesses at the trailing edge in a profile database. The propagation model includes directivity, convective amplification, Doppler shift and atmospheric absorption. The effect of the retarded time is taken into account individually for the separate elements along the blade span using the time dependent rotor azimuth position. A simple empirical model is applied to quantify meteorological effects influencing refraction and ground effects influencing refraction and ground effects. Prediction results are compared to SIROCCO project measurements from microphones positioned in a circle around a turbine. The high spatial and temporal resolution of the SILANT simulations gives new insights in the variation of wind turbine inflow and trailing edge noise as a function of observer position, rotor azimuth angle and frequency band. The influence of directivity is illustrated for the dominant noise sources.

379

Wind turbines in your environment? Wind turbines and energy context  

International Nuclear Information System (INIS)

Renewable energy sources allow to anticipate the depletion of fossil energy reserves and to limit the use of fissile resources. Moreover, their use avoids the emission of enormous amounts of pollutants and greenhouse gases in the atmosphere. This document presents the French energy context (national resources, electricity production and uses); the international political commitments (Kyoto protocol); the position of nuclear power in France and the development of renewable energy sources; and the evolution of the share of wind power with respect to other energy sources in France, in Europe and in the rest of the world. (J.S.)

380

Effect of Rotor Current Control for Wound Rotor Induction Generator on the Wind Turbine Performance  

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents the effect of rotor current control of wound rotor induction generator driven by wind turbine during different operation modes when varying the rotor resistance. The studied modes are wind speed variation, starting especially at high wind speed. Moreover, the effect of the proposed control on short circuit and critical fault clearing time is investigated.

Mahmoud Rabie Barakat

2012-03-01

381

Aeroelastic optimization of MW wind turbines  

Energy Technology Data Exchange (ETDEWEB)

This report contains the results from the Energy Development and Demonstration Project ''Aeroelastic Optimization of MW wind turbine'' (AeroOpt). The project has had the following five Work Packages: 1. Geometric non-linear, anisotropic beam element for HAWC2. 2. Closed-loop eigenvalue analysis of controlled wind turbines. 3. Resonant wave excitation of lateral tower bending modes. 4. Development of next generation aerodynamic design tools. 5. Advanced design and verification of airfoils. The purposes of these Work Packages are briefly described in the Preface and a summary of the results are given in Section 2. Thereafter, the results from each Work Package are described in eight subsequent chapters. (Author)

Hartvig Hansen, M.; Zahle, F.

2011-12-15

382

Wind farm layout optimization using genetic algorithm with different hub height wind turbines  

International Nuclear Information System (INIS)

Highlights: ? Introducing wind farm layout optimization with different hub height wind turbines. ? Considering both maximum power output and minimum cost/power as objective functions. ? Using both nested and real code genetic algorithms. ? Using both single and multi-objective optimizations. - Abstract: Layout optimization is one of the methods to increase wind farm’s utilization rate and power output. Previous researches have revealed that different hub height wind turbines may increase wind farm’s power output. However, few researches focus on optimizing a wind farm’s layout in a two-dimensional area using different hub height wind turbines. In this paper, the authors first investigate the effect of using different hub height wind turbines in a small wind farm on power output. Three different wind conditions are analyzed using nested genetic algorithm, where the results show that power output of the wind farm using different hub height wind turbines will be increased even when the total numbers of wind turbines are same. Different cost models are also taken into account in the analysis, and results show that different hub height wind turbines can also improve cost per unit power of a wind farm. At last, a large wind farm with commercial wind turbines is analyzed to further examine the benefits of using different hub height wind turbines in more realistic conditions

383

Wind Turbine Generator System Duration Test Report for the Gaia-Wind 11 kW Wind Turbine  

Energy Technology Data Exchange (ETDEWEB)

This test was conducted as part of the U.S. Department of Energy's (DOE) Independent Testing project. This project was established to help reduce the barriers of wind energy expansion by providing independent testing results for small turbines. In total, five turbines are being tested at the National Renewable Energy Laboratory's (NRELs) National Wind Technology Center (NWTC) as a part of this project. Duration testing is one of up to five tests that may be performed on the turbines, including power performance, safety and function, noise, and power quality tests. The results of the testing will provide the manufacturers with reports that may be used for small wind turbine certification. The test equipment includes a Gaia-Wind 11 kW wind turbine mounted on an 18 m monopole tower. Gaia-Wind Ltd. manufactured the turbine in Denmark, although the company is based in Scotland. The system was installed by the NWTC Site Operations group with guidance and assistance from Gaia-Wind.

Huskey, A.; Bowen, A.; Jager, D.

2010-09-01

384

Wear Analysis of Wind Turbine Gearbox Bearings  

Energy Technology Data Exchange (ETDEWEB)

The objective of this effort was to investigate and characterize the nature of surface damage and wear to wind turbine gearbox bearings returned from service in the field. Bearings were supplied for examination by S. Butterfield and J. Johnson of the National Wind Technology Center (NREL), Boulder, Colorado. Studies consisted of visual examination, optical and electron microscopy, dimensional measurements of wear-induced macro-scale and micro-scale features, measurements of macro- and micro-scale hardness, 3D imaging of surface damage, studies of elemental distributions on fracture surfaces, and examinations of polished cross-sections of surfaces under various etched and non-etched conditions.

Blau, Peter Julian [ORNL; Walker, Larry R [ORNL; Xu, Hanbing [ORNL; Parten, Randy J [ORNL; Qu, Jun [ORNL; Geer, Tom [ORNL

2010-04-01

385

A novel converter for VSCF wind turbines  

Energy Technology Data Exchange (ETDEWEB)

Positive advantages result from the variable speed operation of wind turbines connected to a power utility. Conventionally thyristor based power interfaces have been used to achieve this and more recently IGBT based converters have shown advantages of improved power quality to the network. This paper describes novel IGBT converter designed built and tested through collaborative research on the European Commission JOULE programme on Renewable Energy. (author)

Smith, G.A. [Leicester Univ. (United Kingdom)

1996-09-01

386

Active system monitoring applied on wind turbines  

DEFF Research Database (Denmark)

A concept for active system monitoring (ASM) applied on wind turbines is presented in this paper. The concept is based on an injection of a small periodic auxiliary signal in the system. An investigation of the signature from the auxiliary input in residual (error) signals can then be applied for an online monitoring of central parameters/elements of the system. Statistical tests are applied on the residual signals for obtaining a correct monitoring.

Niemann, Hans Henrik; Poulsen, Niels KjØlstad

2009-01-01

387

The Federal Advanced Wind Turbine Program  

Science.gov (United States)

The development of technologically advanced, higher efficiency wind turbines has been identified as a high priority activity by the U.S. wind industry. The Department of Energy's Wind Energy Program has begun a multi-year development program aimed at assisting the wind industry with the design, development, and testing of advanced wind turbine systems that can compete with conventional electric generation for $0.05/kWh at 13 mph sites by the mid-1990s and with fossil-fuel-based generators for $0.04/kWh at 13 mph sites by the year 2000. The development plan consists of four phases: (1) Conceptual Design Studies; (2) Near-Term Product Development; (3) Next Generation Technology Integration and Design; and (4) Next-Generation Technology Development and Testing. The Conceptual Design Studies were begun in late 1990, and are scheduled for completion in the Spring of 1992. Preliminary results from these analyses are very promising and indicate that the goals stated above are technically feasible. This paper includes a brief summary of the Conceptual Design Studies and presents initial plans for the follow-on activities.

Hock, S. M.; Thresher, R. W.; Goldman, P. R.

1991-12-01

388

Flow separation on wind turbines blades  

Science.gov (United States)

In the year 2000, 15GW of wind power was installed throughout the world, producing 100PJ of energy annually. This contributes to the total electricity demand by only 0.2%. Both the installed power and the generated energy are increasing by 30% per year world-wide. If the airflow over wind turbine blades could be controlled fully, the generation efficiency and thus the energy production would increase by 9%. Power Control To avoid damage to wind turbines, they are cut out above 10 Beaufort (25 m/s) on the wind speed scale. A turbine could be designed in such a way that it converts as much power as possible in all wind speeds, but then it would have to be to heavy. The high costs of such a design would not be compensated by the extra production in high winds, since such winds are rare. Therefore turbines usually reach maximum power at a much lower wind speed: the rated wind speed, which occurs at about 6 Beaufort (12.5 m/s). Above this rated speed, the power intake is kept constant by a control mechanism. Two different mechanisms are commonly used. Active pitch control, where the blades pitch to vane if the turbine maximum is exceeded or, passive stall control, where the power control is an implicit property of the rotor. Stall Control The flow over airfoils is called "attached" when it flows over the surface from the leading edge to the trailing edge. However, when the angle of attack of the flow exceeds a certain critical angle, the flow does not reach the trailing edge, but leaves the surface at the separation line. Beyond this line the flow direction is reversed, i.e. it flows from the trailing edge backward to the separation line. A blade section extracts much less energy from the flow when it separates. This property is used for stall control. Stall controlled rotors always operate at a constant rotation speed. The angle of attack of the flow incident to the blades is determined by the blade speed and the wind speed. Since the latter is variable, it determines the angle of attack. The art of designing stall rotors is to make the separated area on the blades extend in such a way, that the extracted power remains precisely constant, independent of the wind speed, while the power in the wind at cut-out exceeds the maximum power of the turbine by a factor of 8. Since the stall behaviour is influenced by many parameters, this demand cannot be easily met. However, if it can be met, the advantage of stall control is its passive operation, which is reliable and cheap. Problem Definition In practical application, stall control is not very accurate and many stall-controlled turbines do not meet their specifications. Deviations of the design-power in the order of tens of percent are regular. In the nineties, the aerodynamic research on these deviations focussed on: profile aerodynamics, computational fluid dynamics, rotational effects on separation and pressure measurements on test turbines. However, this did not adequately solve the actual problems with stall turbines. In this thesis, we therefore formulated the following as the essential question: "Does the separated blade area really extend with the wind speed, as we predict?" To find the answer a measurement technique was required, which 1) was applicable on large commercial wind turbines, 2) could follow the dynamic changes of the stall pattern, 3) was not influenced by the centrifugal force and 4) did not disturb the flow. Such a technique was not available, therefore we decided to develop it. Stall Flag Method For this method, a few hundred indicators are fixed to the rotor blades in a special pattern. These indicators, called "stall flags" are patented by the Netherlands Energy Research Foundation (ECN). They have a retro-reflective area which, depending on the flow direction, is or is not covered. A powerful light source in the field up to 500m behind the turbine illuminates the swept rotor area. The uncovered reflectors reflect the light to the source, where a digital video camera records the dynamic stall patterns. The images are analyse

Corten, G. P.

2001-01-01

389

12MW: final report; Wind turbines  

Energy Technology Data Exchange (ETDEWEB)

'12MW: final report' is for the project with the full title '12 MW wind turbines: the scientific basis for their operation at 70 to 270 m height offshore' that had the goal to experimentally investigate the wind and turbulence characteristics between 70 and 270 m above sea level and thereby establish the scientific basis relevant for the next generation of huge 12 MW wind turbines operating offshore. The project started 1st October 2005 and ended 31st March 2009. Firstly was conducted a 6-month experiment at the Horns Rev offshore wind farm deploying a lidar and a sodar on the transformer platform. The observed data were successfully compared to offshore mast data and the wind profile was extended 100 m above previous levels observed in this offshore environment. The wind and turbulence was observed up to 160m above mean sea level. A new normalization was introduced to group the wind profiles into stability groups with variable roughness. Secondly two experiments were conducted at Hoevsoere at the North Sea coast in Jutland. Again the wind profile was extended far beyond previous observed levels, up to 300 m above ground. The analysis showed that the profiles extended far beyond the surface layer and therefore surface layer scale alone could not described the profiles well. In addition the boundary layer height has to be used for the scaling. The boundary layer height was observed by an aerosol lidar at Hoevsoere. The results are published widely, please see the list of publications. (au)

Hasager, C.; Pena, A.; Mikkelsen, T.; Gryning, S.-E.; Courtney, M.; Soerensen, Paul B. (DONG energy)

2009-06-15

390

Optimization of wind turbine energy and power factor with an evolutionary computation algorithm  

Energy Technology Data Exchange (ETDEWEB)

An evolutionary computation approach for optimization of power factor and power output of wind turbines is discussed. Data-mining algorithms capture the relationships among the power output, power factor, and controllable and non-controllable variables of a 1.5 MW wind turbine. An evolutionary strategy algorithm solves the data-derived optimization model and determines optimal control settings. Computational experience has demonstrated opportunities to improve the power factor and the power output by optimizing set points of blade pitch angle and generator torque. It is shown that the pitch angle and the generator torque can be controlled to maximize the energy capture from the wind and enhance the quality of the power produced by the wind turbine with a DFIG generator. These improvements are in the presence of reactive power remedies used in modern wind turbines. The concepts proposed in this paper are illustrated with the data collected at an industrial wind farm. (author)

Kusiak, Andrew; Zheng, Haiyang [Department of Mechanical and Industrial Engineering, 3131 Seamans Center, The University of Iowa, Iowa City, IA 52242-1527 (United States)

2010-03-15

391

Actuator Control of Edgewise Vibrations in Wind Turbine Blades  

DEFF Research Database (Denmark)

Edgewise vibrations with low aerodynamic damping are of particular concern in modern multi-megawatt wind turbines, as large amplitude cyclic oscillations may signi?cantly shorten the life-time of wind turbine components, and even lead to structural damages or failures. In this paper, a new blade design with active controllers is proposed for controlling edgewise vibrations. The control is based on a pair of actuators/active tendons mounted inside each blade, allowing a variable control force to be applied in the edgewise direction. The control forces are appropriately manipulated according to a prescribed control law. A mathematical model of the wind turbine equipped with active controllers has been formulated using an Euler–Lagrangian approach. The model describes the dynamics of edgewise vibrations considering the aerodynamic properties of the blade, variable mass and stiffness per unit length and taking into account the effect of centrifugal stiffening, gravity and the interaction between the blades and the tower. Aerodynamic loads corresponding to a combination of steady wind including the wind shear and the effect of turbulence are computed by applying the modi?ed Blade Element Momentum (BEM) theory. Multi-Blade Coordinate (MBC) transformation is applied to an edgewise reduced order model, leading to a linear time-invariant (LTI) representation of the dynamic model. The LTI description obtained is used for the design of the active control algorithm. Linear Quadratic (LQ) regulator designed for the MBC transformed system is compared with the control synthesis performed directly on an assumed nominal representation of the timevarying system. The LQ regulator is also compared against vibration control performance using Direct Velocity Feedback (DVF). Numerical simulations have been carried out using data from a 5-MW three-bladed Horizontal-Axis Wind Turbine (HAWT) model in order to study the effectiveness of the proposed active controlled blade design in reducing edgewise vibrations. Results show that the useof the proposed control scheme signi?cantly improves the response of the blade and promising performances can be achieved. Furthermore, under the conditions considered in this study quantitative comparisons of the LQ-based control strategies reveal that there is a marginal improvement in the performances obtained by applying the MBC transformation on the time-varying edgewise vibration model of the wind turbine.

Staino, A.; Basu, B.

2012-01-01

392

Atmospheric icing on large wind turbine blades  

Energy Technology Data Exchange (ETDEWEB)

A numerical study of atmospheric ice accretion on a large horizontal axis 'NREL 5 MW' wind turbine blade has been carried out using the computational fluid dynamics based technique. Numerical analyses were carried out at five different sections along the wind turbine blade for both rime and glaze ice conditions. Based upon the flow field calculation and the droplet collision efficiency, the rate and shape of accreted ice was simulated at different atmospheric temperatures. Results indicate that the icing is less severe near the blade root sections, where the blade profiles are larger and thicker, both in terms of local ice mass and accreted ice thickness. Change in accreted ice growth with the atmospheric temperature is significant along the blade sections from centre to tip. The research work also highlighted that the ice accretion on wind turbine blades can also be controlled by optimizing its geometric design features instead of only using the energy consuming anti icing and de-icing systems.

Virk, Muhammad S.; Nicklasson, Per J. [Department of Technology, Barvik University College, 8505 Narvik (Norway); Homola, Matthew C. [Nordkraft Produksjon, Narvik (Norway)

2012-07-01

393

Atmospheric icing on large wind turbine blades  

Directory of Open Access Journals (Sweden)

Full Text Available A numerical study of atmospheric ice accretion on a large horizontal axis ‘NREL 5 MW’ wind turbine blade has been carried out using the computational fluid dynamics based technique. Numerical analyses were carried out at five different sections along the wind turbine blade for both rime and glaze ice conditions. Based upon the flow field calculation and the droplet collision efficiency, the rate and shape of accreted ice was simulated at different atmospheric temperatures. Results indicate that the icing is less severe near the blade root sections, where the blade profiles are larger and thicker, both in terms of local ice mass and accreted ice thickness. Change in accreted ice growth with the atmospheric temperature is significant along the blade sections from centre to tip. The research work also highlighted that the ice accretion on wind turbine blades can also be controlled by optimizing its geometric design features instead of only using the energy consuming anti icing and de-icing systems.

Muhammad S. Virk, Matthew C. Homola, Per J. Nicklasson

2012-01-01

394

Shape Optimization of Wind Turbine Blades  

DEFF Research Database (Denmark)

This paper presents a design tool for optimizing wind turbine blades. The design model is based on an aerodynamic/aero-elastic code that includes the structural dynamics of the blades and the Blade Element Momentum (BEM) theory. To model the main aero-elastic behaviour of a real wind turbine, the code employs 11 basic degrees of freedom corresponding to I I elastic structural equations. In the BEM theory, a refined tip loss correction model is used. The objective of the optimization model is to minimize the cost of energy which is calculated from the annual energy production and the cost of the rotor. The design variables used in the current study are the blade shape parameters, including chord, twist and relative thickness. To validate the implementation of the aerodynamic/aero-elastic model, the computed aerodynamic results are compared to experimental data for the experimental rotor used in the European Commision-sponsored project Model Experiments in Controlled Conditions, (MEXICO) and the computed aero-elastic results are examined against the FLEX code for flow post the Tjereborg 2 MW rotor. To illustrate the optimization technique, three wind turbine rotors of different sizes (the MEXICO 25 kW experimental rotor, the Tjareborg 2 MW rotor and the NREL 5 MW virtual rotor) are applied. The results show that the optimization model can reduce the cost of energy of the original rotors, especially for the investigated 2 MW and 5 MW rotors. Copyright (C) 2009 John Wiley & Sons, Ltd.

Wang, Xudong; Shen, Wen Zhong

2009-01-01

395

Genetic Algorithms in Wind Turbine Airfoil Design  

Energy Technology Data Exchange (ETDEWEB)

One key element in the aerodynamic design of wind turbines is the use of specially tailored airfoils to increase the ratio of energy capture to the loading and thereby to reduce cost of energy. This work is focused on the design of a wind turbine airfoil by using numerical optimization. Firstly, the optimization approach is presented; a genetic algorithm is used, coupled with RFOIL solver and a composite Bezier geometrical parameterization. A particularly sensitive point is the choice and implementation of constraints; in order to formalize in the most complete and effective way the design requirements, the effects of activating specific constraints are discussed. A numerical example regarding the design of a high efficiency airfoil for the outer part of a blade by using genetic algorithms is illustrated and the results are compared with existing wind turbine airfoils. Finally a new hybrid design strategy is illustrated and discussed, in which the genetic algorithms are used at the beginning of the design process to explore a wide domain. Then, the gradient based algorithms are used in order to improve the first stage optimum.

Grasso, F. [ECN Wind Energy, Petten (Netherlands); Bizzarrini, N.; Coiro, D.P. [Department of Aerospace Engineering, University of Napoli ' Federico II' , Napoli (Italy)

2011-03-15

396

Wind turbine blade tip comparison using CFD  

International Nuclear Information System (INIS)

The effect of wind turbine blade tip geometry is numerically analysed using Computational Fluid Dynamics (CFD). Three different rotating blade tips are compared for attached flow conditions and the flow physics around the geometries are analysed. To this end, the pressure coefficient (Cp) is defined based on the stagnation pressure rather than on the inflow dynamic pressure. The tip geometry locally modifies the angles of attack (AOA) and the inflow dynamic pressure at each of the studied sections. However not all 3D effects could be reduced to a change of these two variables. An increase in loadings (particularly the normal force) towards the tip seem to be associated to a spanwise flow component present for the swept-back analysed tip. Integrated loads are ranked to asses wind turbine tip overall performance. It results from the comparison that a better tip shape that produced better torque to thrust ratios in both forces and moments is a geometry that has the end tip at the pitch axis. The work here presented shows that CFD may prove to be useful to complement 2D based methods on the design of new wind turbine blade tips

397

Experiments with a diffuser augmented model wind turbine  

Science.gov (United States)

The initial stages of the experimental development of the diffuser augmented wind turbine (DAWT) employed various screen meshes to simulate the energy extraction mechanisms of a wind turbine. In this investigation in a 2 x 3 m (7 x 10 ft) wind tunnel, a three bladed constant chord, untwisted turbine model was incorporated into a DAWT model. The objectives were to add real turbine characteristics such as swirl, and centerbodies effects, to the flow. Although this turbine model was not well matched to the diffuser, the model DAWT system increased the power output by more than four times that of the model turbine operating as conventional wind energy conversion systems. More than 3.4 times the power potential of an ideal wind turbine was measured

Gilbert, B. L.; Foreman, K. M.

1982-03-01

398

Wind turbine improvements by wind-lidar-based preview and control  

DEFF Research Database (Denmark)

Wind turbines equipped with laser prevision hold potential for up to 6+ years lifetime extension. Forward looking wind lidars integrated within operational wind turbines providing feed-forward control can reduce the daily operation loads. The turbine lifetime may in this way be extended by up to 30 percent.

Mikkelsen, Torben

2014-01-01

399

New turbine could offer low cost wind power  

Energy Technology Data Exchange (ETDEWEB)

The first commercial diffuser augmented wind turbine (DAWT) has just begun a two year test programme in New Zealand. If the developer`s expectations are met, this new design of wind turbine could lead to a major reduction in the cost of wind power. (Author)

Cole, B.

1997-08-01

400

High Voltage Power Converter for Large Wind Turbine  

DEFF Research Database (Denmark)

The increasing penetration of the wind energy has resulted in newly planned installations of offshore wind turbines. In order to minimize installation, material and transportation costs of the offshore wind power plants, large multi-MW wind turbine systems are being preferably employed and developed, which allow high power generation of each single unit. Nevertheless, further increase in the power ratings of the newly emerging turbines becomes a major concern related to the operating voltage level. In order to accommodate larger powers, presently employed low voltage (690 V) systems already require multi-parallel converter and filter modules, which increase the overall complexity. In this thesis, a concept for the medium voltage wind turbine is examined and evaluated, where voltage increase is dictated by the removal of the step-up transformer. As a result, an entire wind turbine electrical system operates at 20 kV level - identical as for the collector distribution network. Medium voltage operation allows the converter unit along with the filter to be installed on the base platform inside the tower. In this manner, more space in the nacelle can be flexibly accommodated by the mechanical parts. Due to limited voltage level of the generator insulation system (15 kV) along with the increasing grid integration requirements, special care has been made over the search for optimal full-scale power converter circuitry, which additionally has to compensate voltage differences between the generator-side and a grid-side. Three converter topologies with different conversion philosophies have been introduced (A, B and C), their performance examined and eventually compared with the conventional low voltage system. System A is a back-to-back MMC converter, which is commonly used in HVDC application. System B consists of the generator-side 2-level converter, DC/DC boost unit and a grid-side NPC-3L converter. System C is made of a seriesconnected full-bridge cells on the generator-side, and a grid-side NPC-5L converter. The performance of the proposed topologies is analyzed both under the normal and fault operation. In normal operation, medium and low voltage converter topologies are compared with regard to the efficiency and the required amount of silicon material in the semiconductor switches. In fault operation, maximum temporary ratings of the collector feeder components are compared also for different grounding schemes, which impact is the result of the removed step-up transformer. Finally, the ground fault detection scheme for feeder cable system is proposed - with the usage of current differential relay. Due to lack of the galvanic separation between the wind turbines and the feeder cable sections, careful investigation for the relay selective operation has been made, which distinguishes ground faults located at the wind turbine terminals from faults within the protected cables. The obtained results from the computer simulations in EMTDC/PSCAD software show, that the best performance has been achieved by the transformer-less turbine with a back-to-back modular multilevel converter (MMC) topology, which is single grounded only through its DC link common-mode point. It has also occurred that the results derived from losses and short circuit analyses have become advantageous over the equivalent conventional system consisting of low voltage wind turbines equipped with the step up transformer.

Sztykiel, Michal

2014-01-01

401

Optimization of power generation from shrouded wind turbines  

OpenAIRE

In past several years, several studies have shown that the shrouded wind turbines can generate greater power compared to bare turbines. The objective of this study is to determine the potential of shrouded wind turbines for increased power generation by conducting numerical simulations. An analytical/computational study is performed by employing the well-known commercial Computational Fluid Dynamics (CFD) software FLUENT. An actuator disc model is used to model the turbine. The incompressible...

Tudor Foote, Ramesh Agarwal

2013-01-01

402

Constant Power Control Of 15 DFIG Wind Turbines With Superconducting Magnetic Energy Storage System  

Directory of Open Access Journals (Sweden)

Full Text Available With the increasing penetration of wind power into electric power grids, energy storage devices will be required to dynamically match the intermittency of wind energy. This paper proposes a novel two-layer constant power control scheme for a wind farm equipped with doubly fed induction generator (DFIG wind turbines. Each DFIG wind turbine is equipped with a superconducting magnetic energy storage system (ESS and is controlled by the low-layer wind turbine generator (WTG controllers and coordinated by a high-layer wind farm supervisory controller (WFSC. The WFSC generates the active power references for the low-layer WTG controllers according to the active power demand from or generation commitment to the grid operator; the low-layer WTG controllers then regulate each DFIG wind turbine to generate the desired amount of active power, where the deviations between the available wind energy input and desired active power output are compensated by the ESS. Simulation studies are carried out in MATLAB/SIMULINK on a wind farm equipped with 15 DFIG wind turbines to verify the effectiveness of the proposed control scheme.

V.Krishnamurthy 1 , Ch.Rajesh Kumar

2013-09-01

403

High power horizontal axis wind turbines dynamic behaviour modeling  

International Nuclear Information System (INIS)

Facing to a very competing market, the manufacturers have to propose increasingly reliable and powerful turbines, at lower cost, with greater and greater rotor diameter. In this context, it proves to be crucial to have tools able to quickly calculate the loads, in order to be able to design them correctly. The wind turbines are complex mechanical systems composed of rigid or flexible bodies. The major part of the current codes treat correctly only the part relating to the aerodynamic loads, and lie on assumptions which can be too simplified with regard to the calculation of the dynamic loads, especially when the size of the rotor increases. Consequently, the aim of this work was then to model the wind turbine dynamic behaviour avoiding drastic simplifications, which could affect the precision of the results. To do this, the Kane's formalism was employed, as well as the description of the kinematic chain through a topological tree-like structure, which allows a recursive and purely numerical building of equations of motion, facilitating its algorithmic treatment, without any simplification. The method developed for the most general case makes possible to model any type of wind turbine, thanks to the improvements made to the basic formalism. It takes into account the behaviour of the rigid bodies (nacelle) as well as flexible ones (blades), for which the flexibility was introduced through a modal representation basis. A computer code was written and validated on some simple cases, by comparison with exact analytical solutions. The calculation of the aerodynamic loads was then coupled to model the mechanical behaviour of an wind turbine starting from realistic data. (author)

404

Applying Value Sensitive Design (VSD) to Wind Turbines and Wind Parks: An Exploration.  

Science.gov (United States)

Community acceptance still remains a challenge for wind energy projects. The most popular explanation for local opposition, the Not in My Backyard effect, has received fierce criticism in the past decade. Critics argue that opposition is not merely a matter of selfishness or ignorance, but that moral, ecological and aesthetic values play an important role. In order to better take such values into account, a more bottom-up, participatory decision process is usually proposed. Research on this topic focusses on either stakeholder motivations/attitudes, or their behavior during project implementation. This paper proposes a third research focus, namely the 'objects' which elicit certain behavioral responses and attitudes-the wind turbine and parks. More concretely, this paper explores Value Sensitive Design (VSD) as way to arrive at wind turbines and parks that better embed or reflect key values. After a critical discussion of the notion of acceptance versus acceptability and support, the paper discusses existing literature on ecology and aesthetics in relation to wind turbine/park design, which could serve as 'building blocks' of a more integral VSD approach of the topic. It also discusses the challenge of demarcating wind park projects as VSD projects. A further challenge is that VSD has been applied mainly at the level of technical artifacts, whereas wind parks can best be conceptualized as socio-technical system. This new application would therefore expand the current practice of VSD, and may as a consequence also lead to interesting new insights for the VSD community. The paper concludes that such an outcome-oriented approach of wind turbines and park is worth exploring further, as a supplement to rather than a replacement of the process-oriented approach that is promoted by the current literature on community acceptance of wind parks. PMID:24744115

Oosterlaken, Ilse

2015-04-01

405

VSC-HVDC link to support voltage and frequency fluctuations for variable speed wind turbines for grid connection  

OpenAIRE

This paper presents the use of induction generator turbine machines with simplified frequency control as a direct drive solution for wind energy conversion. An offshore wind farm system is proposed utilising a VSC-HVDC connection. The wind farm will contain variable speed wind turbines driving Squirrel Cage Induction Generators (SCIG). The study will look at the electrical performance of the generators with real wind data and the design control implications with a VSC-HVDC link. The performan...

Meere, Ronan; O Malley, Mark; Keane, Andrew

2012-01-01

406

Failure Analysis of Wind Turbines by Probability Density Evolution Method  

DEFF Research Database (Denmark)

The aim of this study is to present an efficient and accurate method for estimation of the failure probability of wind turbine structures which work under turbulent wind load. The classical method for this is to fit one of the extreme value probability distribution functions to the extracted maxima of the response of wind turbine. However this approach may contain high amount of uncertainty due to the arbitrariness of the data and the distributions chosen. Therefore less uncertain methods are meaningful in this direction. The most natural approach in this respect is Monte Carlo (MC) simulation. This is not practical due to its excessive computational load. This problem can alternatively be tackled if the evolution of the probability density function (PDF) of the response process can be realized. The evolutionary PDF can then be integrated on the boundaries of the problem. For this reason we propose to use the Probability Density Evolution Method (PDEM). PDEM can alternatively be used to obtain the distribution of the extreme values of the response process by simulation. This approach requires less computational effort than integrating the evolution of the PDF; but may be less accurate. In this paper we present the results of failure probability estimation using PDEM. The results will then be compared to extrapolated values obtained from extreme value distribution fits to the sample response values. The results approve the feasibility of this approach for reliability analysis of wind turbines however they convey the potential for improving accuracy of the method in low probability areas

Sichani, Mahdi Teimouri; Nielsen, SØren R.K.

2013-01-01

407

Radar-cross-section reduction of wind turbines. part 1.  

Energy Technology Data Exchange (ETDEWEB)

In recent years, increasing deployment of large wind-turbine farms has become an issue of growing concern for the radar community. The large radar cross section (RCS) presented by wind turbines interferes with radar operation, and the Doppler shift caused by blade rotation causes problems identifying and tracking moving targets. Each new wind-turbine farm installation must be carefully evaluated for potential disruption of radar operation for air defense, air traffic control, weather sensing, and other applications. Several approaches currently exist to minimize conflict between wind-turbine farms and radar installations, including procedural adjustments, radar upgrades, and proper choice of low-impact wind-farm sites, but each has problems with limited effectiveness or prohibitive cost. An alternative approach, heretofore not technically feasible, is to reduce the RCS of wind turbines to the extent that they can be installed near existing radar installations. This report summarizes efforts to reduce wind-turbine RCS, with a particular emphasis on the blades. The report begins with a survey of the wind-turbine RCS-reduction literature to establish a baseline for comparison. The following topics are then addressed: electromagnetic model development and validation, novel material development, integration into wind-turbine fabrication processes, integrated-absorber design, and wind-turbine RCS modeling. Related topics of interest, including alternative mitigation techniques (procedural, at-the-radar, etc.), an introduction to RCS and electromagnetic scattering, and RCS-reduction modeling techniques, can be found in a previous report.

Brock, Billy C.; Loui, Hung; McDonald, Jacob J.; Paquette, Joshua A.; Calkins, David A.; Miller, William K.; Allen, Steven E.; Clem, Paul Gilbert; Patitz, Ward E.

2012-03-05