...produces a wind turbine that appears...willing to supply a wind turbine for installation...it willing to support a warranty and...throws from the turbine blades. The...from occupied structures, roads, property...The proposed wind turbine...

In optimizing wind turbines it can be of a large help to use information of wind speeds at upwind turbine for the control of downwind turbines, it is, however, problematic to use these measurements directly since they are highly in?uenced by turbulence behind the wind turbine rotor plane. In this paper an orthogonal basis is use to extract the general trends in the wind signal, which are forward to the down wind turbines. This concept controller is designed and simulated on a generic 4.8 MW wind turbine model, which shows the potential of this proposed scheme.

A novel control approach is proposed to optimize the fatigue distribution of wind turbines in a large-scale offshore wind farm on the basis of an intelligent agent theory. In this approach, each wind turbine is considered to be an intelligent agent. The turbine at the farm boundary communicates with...

Due to the stochastic nature of wind, the electric power generated by wind turbines is in general far from constant. The measurement of power fluctuations of wind turbines forms a part of the standard test program of the wind turbine test station of ECN. Here, the need is felt to define a quantity which is a measure of the power fluctuations. This quantity must reflect the properties of the tested turbine in such a way that the various turbines can be compared easily. A quantity is proposed (the power fluctuation coefficient, PFC) which seems suitable for this purpose. PFC's are presented for 8 tested wind turbines. 8 figs., 1 tab.

This proposal of law aims at clarifying and uniformizing the law relative to the layout of wind turbines. Wind turbines can have a bad aesthetical impact on landscapes, and thus the development of wind energy requires a normative framework for the selection of the best projects. Each project will have to fulfill both an impact study and a public inquiry if the wind turbine exceeds 12 m of height. (J.S.)

...appropriate. b. Type of project and structures proposed (total number of...applicable). i. Statement of support from other Government services...generation technologies include: Wind turbines and micro-turbines, micro-hydro power,...

This paper discusses the potential for electricity generation on Hong Kong islands through an analysis of the local weather data and typical wind turbine characteristics. An optimum wind speed, u{sub op}, is proposed to choose an optimal type of wind turbine for different weather conditions. A simulation model has been established to describe the characteristics of a particular wind turbine. A case study investigation allows wind speed and wind power density to be obtained using different hub heights, and the annual power generated by the wind turbine to be simulated. The wind turbine's capacity factor, being the ratio of actual annual power generation to the rated annual power generation, is shown to be 0.353, with the capacity factor in October as high as 0.50. The simulation shows the potential for wind power generation on the islands surrounding Hong Kong. (author)

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.

This paper proposes a reliability model for the electrical subassemblies of geared wind turbine systems with induction generators. The model is derived considering the failure of main subassemblies and their parameters are calculated. A productivity comparison is performed between the selected wind turbine systems including reliability issues. Two methods of modification for variable-speed wind turbines with Doubly Fed Induction Generators (DFIG) to improve their availability are finally suggested.

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.

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.

Recently, the number of outages of wind turbine generator systems has been increasing. For rational lightning protection design, the concept of lightning risk management has been proposed. In this paper, lightning risk assessment of the wind turbine generator systems is carried out and it is compared with field experiences. Furthermore, lightning risk management scheme is discussed.   

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

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)

The INL Wind Farm project proposes to install a 20 MW to 40 MW wind farm on government property, consisting of approximately ten to twenty full-sized (80-meter hub height) towers with 2 MW turbines, and access roads. This includes identifying the optimal turbine locations, building access roads, and pouring the tower foundations in preparation for turbine installation. The project successfully identified a location on INL lands with commercially viable wind resources (i.e., greater than 11 mph sustained winds) for a 20 to 40 MW wind farm. Additionally, the proposed Wind Farm was evaluated against other General Plant Projects, General Purpose Capital Equipment projects, and Line Item Construction Projects at the INL to show the relative importance of the proposed Wind Farm project.

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.

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

This paper proposes a simple criterion for noise limitation of wind turbines: 'The La[sub A50] from a Wind Farm should not exceeding the L[sub A50] 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).

In this article, stabilization methods of wind farms composed of fixed-speed wind turbines and variable-speed wind turbines are analyzed. A current-controlled voltage source converter scheme for a variable-speed wind turbine driving doubly fed induction generator is proposed. The proposed scheme is then compared with two other doubly fed induction generator control schemes to show the effectiveness of the proposed controller. Different types of symmetrical and unsymmetrical faults are analyzed considering wind farm recent grid codes. Though all of the schemes are able to stabilize the wind farms during transient conditions, the proposed current-controlled voltage source converter scheme offers the advantage of less intricacy of controller design, better performance during grid fault, and o...

This paper proposes variable-speed wind generation system using the boost converter. The proposed system has three speed control modes for the wind velocity. The control mode of low wind velocity regulates the armature current of the generator with the boost converter to control the speed of wind turbine. The control mode of middle wind velocity regulates the DC link voltage with the vector controlled inverter to control the speed of wind turbine. The control mode of high wind velocity regulates the pitch angle of the wind turbine with the pitch angle control system to control the speed of wind turbine. The hybrid of three control modes extends the variable-speed range. The proposed system simplifies the maintenance and improves the reliability and reduces the cost in compare with the variable-speed wind generation system using PWM converter. This paper describes the control strategy and modeling for simulation using Matlab Simulink of the proposed system. Also this paper describes the control strategy and modeling of variable-speed wind generation system using PWM converter. The steady state and transient responses for wind velocity changes are simulated using the Matlab Simulink. This paper verifies the fundamental performance of the system using boost converter by discussing the simulation results of the both systems.

Company for NASA and the U.S. Department of Energy. The proposed rotor is .... Structures .............. I I. Development of Wood/Epoxy. Wind Turbine Blades ............. .............. 12 ...... internal reports of the General Electric Company, supporting ...

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

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.

A design is proposed to employ wind towers or Baud-Geers (used for ventilation and passive cooling in Iran and the neighboring countries) as stationary shrouds with wind turbines. The design has all the advantages of diffuser augmented wind turbines. In addition, the entire system is stationary, can accept wind in any direction, and is less noisy than a diffuser system. The design can be made free-standing, or be incorporated in the design of existing or new tall buildings. When incorporated with very tall buildings, it has an additional advantage of accepting wind at increased velocities at higher elevations. Continuity and energy equations were applied to WTAWT, and relations were developed for the system performance. A model of the proposed system was designed and tested in a wind tunnel. The turbine load factor and the augmentation ratio of the model were determined.

Verification of the structural integrity of a wind turbine involves analysis of fatigue loading as well as ultimate loading. With the trend of persistently growing turbines, the ultimate loading seems to become relatively more important. For wind turbines designed according to the wind conditions prescribed in the IEC-61400 code, the ultimate load is often identified as the leading load parameter. Exemplified by the use of an extensive measurement campaign a procedure for evaluation of the extreme flap-wise bending moments, occurring during normal operating of a wind turbine, is presented. The structural measurements are made on a NEG Micon 650 kW wind turbine erected at a complex high wind site in Oak Creek, California. The turbine is located on the top of a ridge. The prevailing wind direction is perpendicular to the ridge, and the annual mean wind speed is 9.5 m/s. The associated wind field measurement, are taken from two instrumented masts erected less than one rotor diameter in front of the turbine in direction of the prevailing wind direction. Both masts are instrumented at different heights in order to gain insight of the 3D-wind speed structure over the entire rotor plane. Extreme distributions, associated with a recurrence period of 10 minutes, conditioned on the mean wind speed and the turbulence intensity are derived. Combined with the wind climate model proposed in the IEC standard, these distributions are used to predict extreme distributions with recurrence periods equal to one and fifty years, respectively. The synthesis of the conditioned PDF`s and the wind climate model is performed by means of Monte Carlo simulation. (au)

...FWS-R9-FHC-2010-N015; 94300-1122-0000-Z2] Wind Turbine Guidelines Advisory Committee; Announcement...Service (Service), will host a Wind Turbine Guidelines Advisory Committee (Committee...habitatconservation/windpower/wind_turbine_advisory_committee.html, by...

This development programme, which will run from December 2004 to September 2006, aims to deliver a condition monitoring system suitable for mass deployment across the UK wind industry that will reduce operating costs and improve design load understanding, operational efficiency, reliability and public safety. The project involves the development of a complete fibre optic structural monitoring system for the wind turbine blades and hub structure. The proposed system will offer significant operational benefits to the developers and users of utility-scale wind turbines. The project's objectives are to: develop a cost-effective strain and temperature sensing system suitable for long-term deployment; carry out functional and environmental stress testing to ensure measurement accuracy (both short and long term); develop a technique to embed the fibre optic sensors in composite wind turbine blades during manufacturing; and develop a technique for retrofitting the sensors to existing wind turbines.

Institutional and governmental support on wind energy sources, together with the wind energy potential and improvement of wind energy conversion technology, has led to a fast development of wind power generation in recent years. The continuous increase of the wind power penetration level brings a result that wind power generation gradually becomes an important component of power generation in the grid, which makes the study on the wind power quality issues and the interaction between the wind turbines and the grid necessary and imperative. The research documented in this thesis examines power quality issues of grid-connected wind turbines and the interaction between wind turbines and the grid. The specific goal of the research has been to investigate flicker emission and mitigation of grid-connected wind turbines with doubly fed induction generators (DFIG) during continuous operation, and voltage recovery of such kind of grid-connected wind turbines after the clearance of a short circuit fault in the grid. As a basis of the research, a model of grid-connected wind turbines with DFIG is developed in the dedicated power system analysis tool PSCAD/EMTDC, which simulates the dynamics of the system from the turbine rotor, where the kinetic wind energy is converted to mechanical energy, to the grid connection point where the electric power is fed into the grid. The complete grid-connected wind turbine model includes the wind speed model, the aerodynamic model of the wind turbine, the mechanical model of the transmission system, models of the electrical components, namely the DFIG, PWM voltage source converters, transformer, capacitor, and the control system. The grid model and the electrical components of the wind turbine are built with standard electrical component models from PSCAD/EMTDC library. The wind model, the aerodynamic model, the mechanical model and the control system are built with custom components developed in PSCAD/EMTDC. Two control schemes are implemented in the developed grid-connectedwind turbine model: speed control and pitch control. The speed control scheme is composed by two vectorcontrol schemes designed respectively for the rotor-side and grid-side PWM voltage source converters. Cascade control is used in the vector-control schemes. Two design methods, poleplacement and internal model control, are applied for designing the PI-controllers in the vector-control schemes. The pitch control scheme is employed to regulate the aerodynamic power from the turbine. The performances of the control schemes, respectively current control loops, power control loops, DC-link voltage control loop and pitch control loop, are illustrated, which meet the design requirements. Simulation results show that the wind turbine is capable of providing satisfactory steady state and dynamic performances, which makes it possible that the wind turbine model can be applied to study the power quality issues of such kind of grid-connected wind turbines and their interaction with the grid. To evaluate the flicker levels produced by grid-connected wind turbines with DFIG, a flickermeter model is developed according to the IEC standard IEC 61000-4-15, which simulates the response of the lamp-eye-brain chain and provides on-line statistical analysis ofthe flicker signal and the final results. Based on the developed model of grid-connected wind turbines with DFIG and the flickermeter model, the flicker emission during continuous operation is studied. The influence factors that affect flicker emission of grid-connected DFIG wind turbines, such as wind characteristics (mean speed, turbulence intensity) and grid conditions (short circuit capacity, grid impedance angle) are analysed. The effects of the influence factors are compared with previous research results related to the fixed speed wind turbine. In particular, the effects of mean wind speed, turbulence intensity and grid impedance angle are different from that in the case of the fixed speed wind turbine. It is possible to regulate the reactive power flow on theconnection line so that the voltage fluctuation caused by the active power flow can be compensated by that caused by the reactive power flow. Based on this principle, two effective measures are proposed to mitigate the flicker levels produced by grid-connected wind turbines with DFIG, respectively by wind turbine output reactive power control and using STATCOM. Simulation results demonstrate that these two measures are effective for flicker mitigation regardless of mean wind speed, turbulence intensity and short circuit capacity ratio. The voltage recovery study is started with grid-connected wind turbines with dynamic slip control, which are simple, cost-effective, partially variable speed wind turbines, for gaining a good understanding of transient responses of induction generators in an external short-circuit situation. The model of a variable speed wind turbine with dynamic slip control in the simulation tool of PSCAD/EMTDC is presented, and the control schemes, respectively dynamic slip control andpitch control, are described. The transient process of grid-connected wind turbines after an external short-circuit fault is analyzed in detail. It is concluded from the analysis that increasing the electromagnetic torque or decreasing the aerodynamic torque helps to recover the voltage after the clearance of an external short-circuit fault. For the wind turbine with dynamic slip control, after the clearance of an external short-circuit fault, the electromagnetic torque may be strengthened by adjusting the generator slip, and the aerodynamic torque may be reduced by regulating the pitch angle, which helped to slow the rotor speed down and re-established the voltage at the wind turbine terminal. Simulation results demonstrate that pitch control, dynamic slip control and combined control are effective measures for voltage recovery of grid-connected wind turbines with dynamic slip control. An emergency pitch regulation scheme is developed and applied in the case of pitch control. Based on the acquired knowledge, the voltage recovery of grid-connected wind turbines with DFIG is studied. Two kinds of situations are studied which depend on whether the rotor protection devices in the DFIG are triggered or not. When the situation after an external short-circuit fault is not serious enough to trigger the rotor protection devices, the control schemes of the DFIG operated as normal and are capable of forcing the rotor speed down and re-establishing the voltage at the wind turbine terminal after the clearance of the short-circuit fault, which are demonstrated by simulation results. The performances of the wind turbine as well as the control schemes are illustrated in detail. If the situation after an external short-circuit fault is serious enough, the protection devices in the rotor circuit will be triggered which yields a result that the generator rotor is shortcircuited and the rotor-side converter is deactivated. In this situation, a control strategy is proposed to re-establish the voltage at the wind turbine terminal and restore the wind turbine's normal operation after the fault clearance, which is verified by simulations results. The control strategy, which takes advantage of the benefits of the rotor circuit protection device and the emergency pitch control scheme, are performed in three steps, respectively protection device activation, voltage recovery assisted by pitch control, and normal operation restoration of the wind turbine with DFIG.

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.

The impact on a utility incorporating wind turbine generation due to wind speed sampling frequency, wind turbine performance model, and wind speed forecasting accuracy is examined. The utility analyzed in the study was the Los Angeles Department of Water and Power and the wind turbine assumed was the MOD-2. The sensitivity of the economic value of wind turbine generation to wind speed sampling frequency and wind turbine modeling technique is examined as well as the impact of wind forecasting accuracy on utility operation and production costs. Wind speed data from San Gorgonio Pass, California during 1979 are used to estimate wind turbine performance using four different simulation methods. (LEW)

A method that includes the essential ingredients for the successful performance predictions of wind turbines in a dense arrangement is under development. With this arrangement, beneficial venturi effects occur between adjacent stations. In the proposed method, the flow field of the wind farm is predicted by solving the steady-state, incompressible, three-dimensional Navier-Stokes equations. The turbines are represented by distributions of momentum sources, and the resulting equations are solved using a three-dimensional Control-Volume Finite Element Method (CVFEM). The progress made and the applicability of the proposed method were demonstrated, along with its capacity to analyze the performance of wind farms. The mathematical model and numerical method described are a two-dimensional axisymmetric formulation applicable to isolated Horizontal-Axis Wind Turbines (HAWTs). Comparisons between the performance predictions obtained with the proposed formulation and those of the momentum-strip theory were presented to illustrate the accuracy of the proposed methodology. 14 refs., 8 figs.

This paper proposes a new stand-alone hybrid power system with a wind turbine generator and photovoltaic modules for a small-scale radio base station. We studied the system characteristics by simulation of operation on Yonaguni Island, where wind speed exceeds 4.0m/s throughout the year, and average annual wind speed is about 7.0m/s. The results of simulation show that, to attain a system operation rate of 100%, the base station equipment requires a wind turbine generator output power of 8kW, a photovoltaic output power of 7.6kW, and 3-day backup storage batteries.   

Wind turbine developments in The Netherlands cover a wide range of technical concepts. The ECN test station for wind turbines plays an important role in these developments. The developments on use of wind energy in The Netherlands, including licensing, certification and standards, are described and information is given on wind turbine manufacturers and the types of wind turbines they produce. 3 figs.

The number of wind turbines in the world grows significantly every year due to politics proposing green energy productions as solutions to mitigate climate change effects. However, this kind of energy is dependent on the weather. This implies that the wind production is irregular at a very short tim...

This paper proposes an optimization algorithm to find the maximum wind installation in a radial distribution network. The algorithm imposes a limit on the amount of wind energy that can be curtailed annually. The algorithm implements the wind turbine reactive power control and wind energy curtailment using sensitivity factors. The optimization is integrated with Monte Carlo simulation to account for the stochastic behavior of load demand and wind power generation. The proposed algorithm is tested on a real 20 kV Danish distribution system in Støvring. It is demonstrated that the algorithm executes reactive compensation and energy curtailment sequentially in an effective and efficient manner.

Wind turbine blade failure is the most prominent and common type of damage occurring in operating wind turbine systems. Conventional nondestructive testing systems are not available for in situ wind turbine blades. We propose a portable long distance ultrasonic propagation imaging (LUPI) system that uses a laser beam targeting and scanning system to excite, from a long distance, acoustic emission sensors installed in the blade. An examination of the beam collimation effect using geometric parameters of a commercial 2MW wind turbine provided Lamb wave amplitude increases of 41.5 and 23.1dB at a distance of 40m for symmetrical and asymmetrical modes, respectively, in a 2mm-thick stainless steel plate. With this improvement in signal-to-noise ratio, a feasibility study of damage detection was...

Currently, there is an increasing trend to connect large MW wind farms to the transmission system. Therefore the power system becomes more vulnerable and dependent on the wind energy production. At the same time requirements that focus on the influence of the farms on the grid stability and power quality, and on the control capabilities of wind farms have already been established. The main trends of modern wind turbines/farms are clearly the variable speed operation and a grid connection through a power electronic interface, especially using doubly-fed induction generators. Using power electronics the control capabilities of these wind turbines/farms are extended and thus the grid requirements are fulfilled.  However, the traditional squirrel-cage generators based wind turbines/wind farms directly connected to the grid does not have such control capabilities. They produce maximum possible power in continuous operation and are becoming disconnected in the case of a grid fault. Moreover, these wind turbines/farms cannot regulate their production and contribute to power system stability. A DC transmission system for connection of the active stall wind farms to the grid can be a solution to these problems. Such a system has special regulating properties e.g. decoupled control of active and reactive power, continuous AC voltage regulation, variable frequency control, black-start capability, etc. This paper focuses on the modeling of such systems and proposes a control method of a voltage source converter based DC transmission system for connecting active stall wind farms to the grid

Currently, there is an increasing trend to connect large MW wind farms to the transmission system. Therefore the power system becomes more vulnerable and dependent on the wind energy production. At the same time requirements that focus on the influence of the farms on the grid stability and power quality, and on the control capabilities of wind farms have already been established. The main trends of modern wind turbines/farms are clearly the variable speed operation and a grid connection through a power electronic interface, especially using doubly-fed induction generators. Using power electronics the control capabilities of these wind turbines/farms are extended and thus the grid requirements are fulfilled. However, the traditional squirrel-cage generators based wind turbines/wind farms directly connected to the grid does not have such control capabilities. They produce maximum possible power in continuous operation and are becoming disconnected in the case of a grid fault. Moreover, these wind turbines/farms cannot regulate their production and contribute to power system stability. A DC transmission system for connection of the active stall wind farms to the grid can be a solution to these problems. Such a system has special regulating properties e.g. decoupled control of active and reactive power, continuous AC voltage regulation, variable frequency control, black-start capability, etc. This paper focuses on the modeling of such systems and proposes a control method of a voltage source converter based DC transmission system for connecting active stall wind farms to the grid.   

One of the major challenges of the wind energy sector is to accurately predict the wind potential. This task is especially difficult in mountainous terrains where the topography can imply complex relief-induced flows. Wind tunnel testing is one of the possibilities to simulate and predict the wind for wind turbine micro-siting. Most advanced quantitative measurement techniques can be used in the wind tunnel, however, measuring the whole terrain to find the highest wind potential zones is very time-consuming. This paper proposes to use a very simple, quick and cheap technique to detect and evaluate the high wind speed areas over an entire model. Commonly used for pedestrian wind comfort assessment, the sand erosion technique is here applied to wind resource assessment. The technique can pro...

Wind turbine system reliability is a critical factor in the success of a wind energy project. Poor reliability directly affects both the project's revenue stream through increased operation and maintenance (O&M) costs and reduced availability to generate power due to turbine downtime. Indirectly, the acceptance of wind-generated power by the financial and developer communities as a viable enterprise is influenced by the risk associated with the capital equipment reliability; increased risk, or at least the perception of increased risk, is generally accompanied by increased financing fees or interest rates. This paper outlines the issues relevant to wind turbine reliability for wind turbine power generation projects. The first sections describe the current state of the industry, identify the cost elements associated with wind farm O&M and availability and discuss the causes of uncertainty in estimating wind turbine component reliability. The latter sections discuss the means for reducing O&M costs and propose O&M related research and development efforts that could be pursued by the wind energy research community to reduce cost of energy.

The penetration of wind power has increased greatly over the last decade in the United States and across the world. The U.S. wind power industry installed 1,118 MW of new capacity in the first quarter of 2011 alone and entered the second quarter with another 5,600 MW under construction. By 2030, wind energy is expected to provide 20% of the U.S. electricity needs. As the number of wind turbines continues to grow, the need for effective condition monitoring and fault detection (CMFD) systems becomes increasingly important [3]. Online CMFD is an effective means of not only improving the reliability, capacity factor, and lifetime, but it also reduces the downtime, energy loss, and operation and maintenance (O&M) of wind turbines. The goal of this project is to develop novel online nonintrusive CMFD technologies for wind turbines. The proposed technologies use only the current measurements that have been used by the control and protection system of a wind turbine generator (WTG); no additional sensors or data acquisition devices are needed. Current signals are reliable and easily accessible from the ground without intruding on the wind turbine generators (WTGs) that are situated on high towers and installed in remote areas. Therefore, current-based CMFD techniques have great economic benefits and the potential to be adopted by the wind energy industry. Specifically, the following objectives and results have been achieved in this project: (1) Analyzed the effects of faults in a WTG on the generator currents of the WTG operating at variable rotating speed conditions from the perspective of amplitude and frequency modulations of the current measurements; (2) Developed effective amplitude and frequency demodulation methods for appropriate signal conditioning of the current measurements to improve the accuracy and reliability of wind turbine CMFD; (3) Developed a 1P-invariant power spectrum density (PSD) method for effective signature extraction of wind turbine faults with characteristic frequencies in the current or current demodulated signals, where 1P stands for the shaft rotating frequency of a WTG; (4) Developed a wavelet filter for effective signature extraction of wind turbine faults without characteristic frequencies in the current or current demodulated signals; (5) Developed an effective adaptive noise cancellation method as an alternative to the wavelet filter method for signature extraction of wind turbine faults without characteristic frequencies in the current or current demodulated signals; (6) Developed a statistical analysis-based impulse detection method for effective fault signature extraction and evaluation of WTGs based on the 1P-invariant PSD of the current or current demodulated signals; (7) Validated the proposed current-based wind turbine CMFD technologies through extensive computer simulations and experiments for small direct-drive WTGs without gearboxes; and (8) Showed, through extensive experiments for small direct-drive WTGs, that the performance of the proposed current-based wind turbine CMFD technologies is comparable to traditional vibration-based methods. The proposed technologies have been successfully applied for detection of major failures in blades, shafts, bearings, and generators of small direct-drive WTGs. The proposed technologies can be easily integrated into existing wind turbine control, protection, and monitoring systems and can be implemented remotely from the wind turbines being monitored. The proposed technologies provide an alternative to vibration-sensor-based CMFD. This will reduce the cost and hardware complexity of wind turbine CMFD systems. The proposed technologies can also be combined with vibration-sensor-based methods to improve the accuracy and reliability of wind turbine CMFD systems. When there are problems with sensors, the proposed technologies will ensure proper CMFD for the wind turbines, including their sensing systems. In conclusion, the proposed technologies offer an effective means to achieve condition-based smart maintenance for wind turbines and have a great potential to be adopted by the wind energy industry due to their almost no-cost, nonintrusive features. Although only validated for small direct-drive wind turbines without gearboxes, the proposed technologies are also applicable for CMFD of large-size wind turbines with and without gearboxes. However, additional investigations are recommended in order to apply the proposed technologies to those large-size wind turbines.

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 presented in paper A and B. A sound propagation algorithm has been compared to long range measurements of sound propagation in paper C. Psycho-acoustic tests evaluating the threshold and partial loudness of wind turbine noise when mixed with natural ambient sounds have been performed. These are accounted for in paper D. The main scientific contributions are the following.Paper A: A semi-empiric prediction model for vegetation sound is proposed. This model uses up-to-date simulations of wind profiles and turbulent wind fields to estimate sound from vegetation. The fluctuations due to turbulence are satisfactory estimated by the model. Predictions of vegetation sound also show good agreement to measured spectra. Paper B: A set of measurements of air-borne sound from breaking waves are reported. From these measurements a prediction method of sound from breaking waves is proposed. Third octave spectra from breaking waves are shown to depend on breaker type. Satisfactory agreement between predictions and measurements has been achieved. Paper C: Long range sound propagation over a sea surface was investigated. Measurements of sound transmission were coordinated with local meteorological measurements. A sound propagation algorithm has been compared to the measured sound transmission. Satisfactory agreement between measurements and predictions were achieved when turbulence were taken into consideration in the computations. Paper D: The paper investigates the interaction between wind turbine noise and natural ambient noise. Two loudness models overestimate the masking from two psychoacoustic tests. The wind turbine noise is completely concealed when the ambient sound level (A-weighed) is around 10 dB higher than the wind turbine noise level. Wind turbine noise and ambient noise were presented simultaneously at the same A-weighed sound level. The subjects then perceived the loudness of the wind turbine noise as 5 dB lower than if heard alone

This paper presented the results of a public inquiry into the environmental impact of Northland Power's proposed $270 million wind turbine array at Saint-Ulric, Saint-Leandre and Saint-Damase in the province of Quebec. It provided information on the project proponent along with the human toll of the project in terms of visual impacts and influence on public health, property values, agricultural activity, forestry and economic activity. Northland has completed a supply agreement with General Electric to provide 100 GE 1.5 MW high-technology turbines for the project. The turbine towers will be 80 metres high and their rotors will be 77 metres in diameter. Northland is working with experts on the analysis of wind data, design of the wind farm, and assessment of the potential environmental impacts of the proposed project. This study evaluated the impact of the proposed wind turbine array on birds and bats. It was recommended that the proponent pay attention to the visual impact of the wind farm on tourism in the area. The responsibilities of the proponent with respect to addressing public concerns were addressed with respect to implementing emergency plans, dismantling measures, land reclamation and social acceptance. Northland is committed to working with expert consultants and local stakeholders to ensure that the project conforms to regulatory requirements, minimizes impacts on the environment, and brings economic benefits to surrounding communities. It was recommended that the promoter collaborate with farmers to ensure that the wind turbine array will not impede agricultural activities. refs., tabs.

Small signal stability analysis for power systems with wind farm interaction is presented. Power systems oscillation modes can be excited by disturbance or fault in the grid. Variable speed wind turbines can be regulated to reduce these oscillations, stabilising the power system. A power system stabiliser (PSS) control loop for wind power is designed in order to increase the damping of the oscillation modes. The proposed power system stabiliser controller is evaluated by small signal analysis.

In the planning and financing stage of a wind farm project a risk assessment is required quantifying all risks related to the wind farm financing (due diligence). Banks, owners or investors contract independent experts, who analyse all aspects of the wind farm planning and their related financial risks. Such risks are site assessment including wind speed measurements, wind farm layout, load spectra and lifetime of the components (related to the distances between the turbines), the foundation requirements, the electrical losses, noise limits, experience with the planned type of turbines and the contractual issues dealing with energy production warranties. The risks will be identified, quantified and minimised. The fact that most wind energy projects run very well should not cause financiers to underestimate the financial risks. The costs for a wind speed measurement at 80 m height according to the IEA recommendations with MEASNET calibrated anemometers, alternatively a wind speed measurement at 50 m height in combination with a SODAR measurement campaign in order to determine the wind profile up to a height of 150 m, are in the range of 0.1 percent of the total investment cost of a medium sized wind farm. At DEWI the whole power performance measurement report is reviewed in order to quantify the uncertainties of the power curve measurement and the possible deviation of the measurement to the relevant standards. Site specific influences on the power curve like air density, icing, and turbulence intensity are considered as well. A crucial point for the economy of a wind farm are the contractual issues dealing with energy production warranties. These performance warranties guarantee that the turbines produce the energy expected from the existing wind conditions. In terms of risk management or risk assessment the difficulty lies in the split of the risk 'wind conditions' normally taken by the owner and the risk 'wind farm performance' or 'individual turbine performance' normally taken by the manufacturer. Another difficulty is which measurement procedure can be used for the verification of the guaranteed performance and which terms of payment can be agreed upon if the verification shows that the turbines don't pass the acceptance test. An IEC working group is working on a standard in which the wind farm will be treated as a single power station and a method is proposed for testing the performance of a complete wind farm in relation to a reference point (location of a met mast) or several reference points. This warranty covers in a simple way the verification of the performance testing of individual wind turbines, micro siting, wind farm efficiency and availability of the turbines. (orig.)

The present contribution proposes and describes a promising way towards performance prediction of an arbitrary array of turbines. It is based on the solution of the time-averaged, steady-state, incompressible Navier-Stokes equations with an appropriate turbulence closure model. The turbines are represented by distributions of momentum sources in the Navier-Stokes equations. In this paper, the applicability and viability of the proposed methodology is demonstrated using an axisymmetric implementation. The k-{epsilon} model has been chosen for the closure of the time-averaged, turbulent flow equations and the properties of the incident flow correspond to those of a neutral atmospheric boundary layer. The proposed mathematical model is solved using a Control-Volume Finite Element Method (CVFEM). Detailed results have been obtained using the proposed method for an isolated wind turbine and for two turbines one behind another. In the case of an isolated turbine, accurate wake velocity deficit predictions are obtained and an increase in power due to atmospheric turbulence is found in agreement with measurements. In the case of two turbines, the proposed methodology provides an appropriate modelling of the wind-turbine wake and a realistic prediction of the performance degradation of the downstream turbine.

During the operation of a 45 kVA wind turbine vibrations were observed in the tower. A failure in the electrical part of the turbine was the cause of these vibrations. The measurements performed at the wind turbine are described.

This paper investigated the integration of a proposed 100 MW wind farm located near Cape Town, South Africa. Abundant wind resources are located in the region. Computerized simulations were conducted in order to determine potential power quality issues related to the wind farm's integration with the electricity grid. The network was subjected to variable wind power output. The rated output power each wind turbine was considered in relation to an infinite bus system. The wind farm was connected to a 33 kv/132 kV substation connected to the electricity grid with a double line circuit. The wind turbines were connected as squirrel cage and doubly-fed induction generators. The interactions between the wind power plant, reactive power, and the electricity grid were then analyzed in order to determine voltage variations caused by the varying output power from the wind turbines. Results of the study showed that reactive power compensation was facilitated by the turbine capacitor banks, and the effect of voltage fluctuation were minimized. 11 refs., 2 tabs., 8 figs.

In the context of the increasing application of remote sensing techniques in wind energy, the feasibility of upwind observations via a spinner-mounted wind lidar was tested during the SpinnerEx 2009 experiment. The objective was to install a QinetiQ (Natural Power) ZephIR lidar in the rotating spinner of a MW-sized wind turbine, and investigate the approaching wind fields from this vantage point. Time series of wind speed measurements from the lidar with 50 Hz sampling rate were successfully obtained for approximately 60 days, during the measurement campaign lasting from April to August 2009. In this report, information is given regarding the experimental setup and the lidar's operation parameters. The geometrical model used for the reconstruction of the scanning pattern of the lidar is described. This model takes into account the lidar's pointing direction, the spinner axis's vertical tilt and the wind turbine's yaw relative to the mean wind speed direction. The data analysis processes are documented. A methodology for the calculation of the yaw misalignment of the wind turbine relative to the wind direction, as a function of various averaging times, is proposed, using the lidar's instantaneous line-of-sight radial wind speed measurements. Two different setups have been investigated in which the approaching wind field was measured at distances of 0.58 OE and 1.24 OE rotor diameters upwind, respectively. For both setups, the instantaneous yaw misalignment of the turbine has been estimated from the lidar measurements. Data from an adjacent meteorological mast as well as data logged within the wind turbine's control system were used to evaluate the results. (author)

This paper deals with structured control of linear parameter varying systems (LPV) with application to wind turbines. Instead of attempting to reduce the problem to linear matrix inequalities (LMI), we propose to design the controllers via an LMI-based iterative algorithm. The proposed algorithm can synthesize structured controllers like decentralized, static output and reduced order output feedback for discrete-time LPV systems. Based on a coordinate decent, it relies on a sufficient matrix inequality condition extended with slack variables to an upper bound on the induced L2-norm of the closed-loop system. Algorithms for the computation of feasible as well as optimal controllers are presented. The general case where no restrictions are imposed on the parameter dependence is treated here due to its suitability for modeling wind turbines. A comprehensive numerical example of a gain-scheduled LPV controller design with prescribed pattern for wind turbines illustrate the utilization of the proposed algorithm.

Summary 1.-Wind farms generate little or no pollution. However, one of their main adverse impacts is bird mortality through collisions with turbine rotors. 2.-Environmental impact assessment (EIA) studies have been based on observations of birds before the construction of wind farms. We analysed data from 53 EIAs in relation to the actual recorded bird mortalities at 20 fully installed wind farms to determine whether this method is accurate in predicting the risk of new wind farm installations. 3.-Bird data from EIAs were compared with bird collisions per turbine and year at functional post-constructed wind farms to identify any relationship between pre- and post-construction studies. 4.-Significant differences in birds recorded flying among the 53 proposed wind farms were found by the EIA...

...development; wind energy development...changes in forest structure and insect distribution...the petitioner supports the petitioner's...status reviews. Wind Energy Development...mortality from turbine operation (Petition...watts (MW)) wind turbines, with the...

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Several international groups, such as International Electrotechnical Commission (IEC) Electrical Models of Wind Turbines and Wind Farms group, are working to standardize models to be used by TSO's in power system dynamic simulations to analyze the safety of the grid. This paper presents a simple model of generic wind turbine generator, based on REE model and adapted to real machines. To test the model, stability analyses during symmetric three-phase faults have been done. The proposed model can be used to reproduce the behaviour of most of the current wind turbine technologies like DFIG, by tuning its parameters. To do this, it is necessary to collect extensive data series to manage with its high nonlinearity behaviour. (orig.)

This work was motivated by the increasing awareness of the need for enhancing water supplies schemes in arid and coastal areas featuring an appropriate technology for wind energy use. The development of this technology at small scale might be the most economical solution for providing potable water to remote and coastal communities where the electric grid and the proper infrastructure are lacking. The present article analyzes theoretically a wind turbine generator to improve the efficiency of an autonomous desalination unit. Three climatic zones in coastal Egypt—Mediterranean Sea coast and the Red Sea coast have been evaluated and the acoustic noise analysis and calculation from the proposed wind turbine are presented. The mechanical coupling of wind turbine and helical shaft to bre...

This paper concentrates on the design and control of a three-level grid side converter (GSC) for direct drive high power wind turbines. The three-level, neutral point clamped (NPC) topology was investigated. The proposed control scheme, based on vector current control, offers very satisfying performances regarding to structure stability and grid connection requirements (GCR). In order to have an accurate evaluation of grid voltage source, two grid synchronization methods are developed and their performances are compared. The GSC performances are evaluated under both normal and grid fault conditions. Simulation results show that stability is maintained during voltage dips and that the proposed direct drive wind turbine satisfies completely GCR.

Wind turbine system reliability is a critical factor in the success of a wind energy project. Poor reliability directly affects both the project's revenue stream through increased operation and maintenance (O&M) costs and reduced availability to generate power due to turbine downtime. Indirectly, the acceptance of wind-generated power by the financial and developer communities as a viable enterprise is influenced by the risk associated with the capital equipment reliability; increased risk, or at least the perception of increased risk, is generally accompanied by increased financing fees or interest rates. Cost of energy (COE) is a key project evaluation metric, both in commercial applications and in the U.S. federal wind energy program. To reflect this commercial reality, the wind energy research community has adopted COE as a decision-making and technology evaluation metric. The COE metric accounts for the effects of reliability through levelized replacement cost and unscheduled maintenance cost parameters. However, unlike the other cost contributors, such as initial capital investment and scheduled maintenance and operating expenses, costs associated with component failures are necessarily speculative. They are based on assumptions about the reliability of components that in many cases have not been operated for a complete life cycle. Due to the logistical and practical difficulty of replacing major components in a wind turbine, unanticipated failures (especially serial failures) can have a large impact on the economics of a project. The uncertainty associated with long-term component reliability has direct bearing on the confidence level associated with COE projections. In addition, wind turbine technology is evolving. New materials and designs are being incorporated in contemporary wind turbines with the ultimate goal of reducing weight, controlling loads, and improving energy capture. While the goal of these innovations is reduction in the COE, there is a potential impact on reliability whenever new technologies are introduced. While some of these innovations may ultimately improve reliability, in the short term, the technology risks and the perception of risk will increase. The COE metric used by researchers to evaluate technologies does not address this issue. This paper outlines the issues relevant to wind turbine reliability for wind turbine power generation projects. The first sections describe the current state of the industry, identify the cost elements associated with wind farm O&M and availability and discuss the causes of uncertainty in estimating wind turbine component reliability. The latter sections discuss the means for reducing O&M costs and propose O&M related research and development efforts that could be pursued by the wind energy research community to reduce COE.

In this thesis it has been investigated if LQG control could be used to mitigate torsional oscillations in a variable speed, fixed pitch wind turbine. The wind turbine is a vertical axis wind turbine with a 40 m tall axis that is connected to a generator. The power extracted by the turbine is delive...

The offshore wind farm with installed back-to-back power converter in wind turbines is studied. As an example the Burbo Bank offshore wind farm with Siemens Wind Power wind turbines is taken into consideration. The wind farm is simulated in DIgSILENT Power Factory software in order to determine and ...

The energy infrastructure of rural Alaska was described and proposed wind energy projects were highlighted with particular reference to one small community 30 miles north of the Arctic Circle. Kotzebue, with a population of 3,705, is a hub community for 10 surrounding communities. In 1991, the Kotzebue Electric Association began looking at wind as a potential energy source for the community. An investment of $250 K was made in 1994 into a wind development project involving 10 15/50 turbines with a rated turbine capacity of 66 kW continuous rating. One of the main objective was to reduce diesel consumption. This presentation documented the operations and maintenance costs of the project, including the establishment of a cold weather technology center. As the cost of wind projects decreases, wind development is being viewed as a positive example of rural economic development and a viable source of energy for rural Alaska. figs.

We introduce a novel scheme for small wind turbines that gives dynamic estimation of wind speed from rotor angular velocity measurements. The estimation proceeds in two different dynamic observers, one giving a valid estimate for higher Tip Speed Ratios (TSRs) and which we call the Upper Wind Estimator (UWE) and the other called the Lower Wind Estimator (LWE) valid for lower TSRs. The meaning of "higher" and "lower", and the precise regions of validity, are quantified. We further propose a coordinated control scheme using the UWE. Simulations are presented showing closed-loop performance of the turbine and the estimators both in the optimal TSR regulation condition, and the dynamic power-shedding condition caused by a wind gust. An analytic analysis of closed-loop stability and of the conv...

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)

with making wind turbines a safe and reliable energy source. Although several wind turbine ... generating equipment protection, ..... wind it is important to have a reliable turbine. Providing lightning protection will make wind ...... originally developed and evaluated for devices operating at reverse bias and subjected to pulse ...

Wind turbine installation is increasing rapidly. In some networks, wind power penetration is significantly high and the performance of wind turbine plays an important role in power system operation and control. Especially, the behavior of wind turbines during a power system disturbance would affect ...

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 ...

A cross-flow wind turbine has a high torque coefficient at a low tip speed ratio. Therefore, it is a good candidate for use as a self-starting turbine. Furthermore, it has low noise and excellent stability; therefore, it has attracted attention from the viewpoint of applications as a small wind turbine for an urban district. However, its maximum power coefficient is extremely low (10 %) as compared to that of other small wind turbines. In order to improve the performance and the flow condition of the cross-flow rotor, symmetrical casings with a nozzle and a diffuser are proposed and experimental research with two types of symmetrical casings is conducted. The maximum power coefficient is obtained as Cpmax = 0.17 for casing 2 and Cpmax=0.098 for casing 1. In the present study, power characteristics of the cross-flow rotor and those of the symmetrical casings with the nozzle and the diffuser are investigated. Then, the performance and internal flow patterns of the cross-flow wind turbine with the symmetrical casings are clarified. After that, the effect of the symmetrical casings on the performance of the turbine is discussed on the basis of the analysis results.   

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)

This paper describes a doubly fed induction generator (DFIG) control for wind energy generation. The DFIG model is established and the adopted control strategies for machine side and grid side converters are described. Flicker phenomenon is defined and its emission of variable speed wind turbine with DFIG during continuous operation is studied. Calculation of flicker severity is evaluated using flickermeter. Appropriate vector power control of the machine side converter is proposed and applied to achieve flicker mitigation.

Environmental monitoring at wind turbine arrays is needed before, during and after project development. Pesca Environmental evaluates the impact of proposed wind turbine arrays on birds and chiroptera by examining their migration patterns through visual and auditory observations during the springtime reproductive and nesting season as well as in the autumn. In order to complete a feasibility study, spring migration patterns of birds and chiroptera must be documented and characterized. In addition to building an inventory of birds and chiroptera, Pesca examines bird behaviour and flight patterns and nesting locations. figs.

Parallel converters in wind turbine give a number advantages, such as fault tolerance due to the redundant converters. However, it might be difficult to isolate gain faults in one of the converters if only a combined power measurement is available. In this paper a scheme using orthogonal power references to the converters is proposed. Simulations on a wind turbine with 5 parallel converters show a clear potential of this scheme for isolation of this gain fault to the correct converter in which the fault occurs.

This paper shows a model of a doubly fed induction generator (DFIG) including a simplified model of a wind turbine for the purpose of transient stability analysis of large-scale power systems with great wind farms penetration. The wind turbine model and the DFIG model are systematically deducted in this paper. Specially, the improved model of rotor-side converter and the simplified grid-side converter model are considered in our work. The corresponding machine-network interface solution based on the synchronously rotating common x-y reference frame is elaborately issued in this paper. Furthermore, a method is proposed to calculate the DFIG initial conditions as well. A simplified model of the turbine is used excluding among other components the pitch control. Copyright Copyright 2007 John ...

In this work the problem of individual pitch control of a variable-speed variable-pitch wind turbine in the full load region is considered. Model predictive control (MPC) is used to solve the problem. However as the plant is nonlinear and time varying, a new approach is proposed to simplify the optimization problem. Nonlinear dynamics of the wind turbine is derived by combining blade element momentum (BEM) theory and first principle modeling of the flexible structure. Then the nonlinear model of the system is linearized using Taylor series expansion around its operating points and a family of linear models are obtained. The operating points are determined by LIDAR measurements both for the current and predicted future operating points. The obtained controller is applied on a full complexity, high fidelity wind turbine model. Finally simulation results show improved load reduction on out-of-plane blade root bending moments and a better transient response compared to a benchmark PI individual pitch controller.

This book presents the papers given at the Sixth Biennial Wind Energy Conference and Workshop held in Minneapolis/St. Paul in 1983. Topics considered include the US wind energy program (e.g., the vertical axis wind turbine program, the SERI program), international wind energy programs (e.g., Netherlands, UK, Norway), large wind systems (e.g. Mod-2 wind turbine development), small wind systems (e.g. wind powered heating systems), vertical axis wind systems (e.g. advanced Darrieus wind turbines), advanced concepts (e.g. giromill rotors), community and wind farm applications (e.g. utility-owned wind turbines), aerodynamics and wakes, wind characteristics, wind turbine performance and testing, safety and environment, stand-alone systems, dynamic analysis, utility interconnection, and other applications and considerations such as the double output induction generator.

This work considers the use of wind turbines for aiding up-regulation of 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 by solving a series of convex problems, where the load is distributed among several turbines in a farm. Thereafter, we present an optimization scheme that guarantees a lower limit for the overproduction period and subsequently propose an adaptive implementation that is robust against parameter uncertainties.

In the present study, the hub-height wind speed ratios for 16 individual wind directional groups were estimated by the RIAM-COMPACT for Noma Wind Park, Kagoshima Prefecture. The validity of the proposed estimation technique for the actual wind was examined. For this procedure, field observational data from the one year period between April, 2004 and March, 2005 were studied. In this case, the relative error on the prediction accuracy was less than 10% and less than 5% for the monthly and annual average wind speeds, respectively. Similar to the results for the annual average wind speed, the difference in the selected reference points (Wind Turbines #4 and #6) had little difference in the relative error on the prediction accuracy of the annual energy output. For both reference points, the relative error was within 10%.   

The present work proposes a start-up procedure for a doubly-fed induction generator (DFIG) driven by a wind turbine. In the DFIG topology the stator is connected direct to the grid while the rotor is connected to a back-to-back converter. This structure requires some care during grid synchronization...

HyWind, Hydro's wind power concept for floating offshore wind turbines is briefly described. Hydro sees offshore wind power as an area of growth for the future. Technical drawings and data are presented from model experiments (ml)

Offshore installations of wind turbines are promising for higher wind energy availability, and for less severe environmental and social constraints, than on the mainland. In this paper a semi-submersible moored structure for supporting wind turbines in depths ranging from 30 to 100 m is presented and discussed. The proposed structure consists of a toroidal body connected, by means of three columns, with a platform located above the maximum wave crest, where the supporting tower of a standard wind turbine is placed. The toroidal body is held in submersion at a depth of about 10 m by mooring cables anchored to the sea bottom; this reduces the wave action on the structure and achieves suitable stability and stiffness of the whole system. With reference to a given site, with known wind and wave climate, and to a medium size wind turbine, some alternatives for the supporting structure are developed. The movements of the structures and the cable forces have been evaluated by means of model tests carried out in a laboratory wave flume. (author)

A new system is proposed in order to prevent over-rotation of a small horizontal axis wind turbine in a strong-wind condition. The system consists of a mandrel bar and a fiber-reinforced rubber pipe in which the metal fiber is arranged with oblique angle. This is installed at the root of each blade respectively. When the rubber pipe is subjected to the centrifugal force due to the rotation of the blade, the fibers are forced to be straight in the loading direction. This yields the torsional deformation of the pipe, and achieves the change of the pitch-angle of the blade corresponding to the revolution of the turbine passively. The tensile tests are performed to examine the fundamental elastic behavior of the fiber-reinforced rubber pipe. To investigate the performance of the electric power generation by the wind turbine with the present system, the wind tunnel tests are carried out. It is confirmed that the present system enables to avoid the over-rotation of wind turbine and realizes the stable power generation even in the strong-wind condition.   

Offshore wind turbines for electricity production placed in wind farms are expected to be of one of the major future contributors for sustainable energy production. In this article, some of the problems associated with optimal planning and design of wind turbine parks are addressed. The number of wind turbines in a park is usually restricted to be placed within a fixed, limited geographical area. Behind a wind turbine, a wake is formed where the mean wind speed decreases and the turbulence intensity increases. The distance between the turbines is among other things dependent on the recovery of wind energy behind the neighboring turbines and the increased wind load. Models for the mean wind speed and turbulence intensity in wind turbine parks are considered with emphasis on modeling the spa...

Wind turbine blade failure is the most prominent and common type of damage occurring in operating wind turbine systems. Conventional nondestructive testing systems are not available for in situ wind turbine blades. We propose a portable long distance ultrasonic propagation imaging (LUPI) system that uses a laser beam targeting and scanning system to excite, from a long distance, acoustic emission sensors installed in the blade. An examination of the beam collimation effect using geometric parameters of a commercial 2 MW wind turbine provided Lamb wave amplitude increases of 41.5 and 23.1 dB at a distance of 40 m for symmetrical and asymmetrical modes, respectively, in a 2 mm-thick stainless steel plate. With this improvement in signal-to-noise ratio, a feasibility study of damage detection was conducted with a 5 mm-thick composite leading edge specimen. To develop a reliable damage evaluation system, the excitation/sensing technology and the associated damage visualization algorithm are equally important. Hence, our results provide a new platform based on anomalous wave propagation imaging (AWPI) methods with adjacent wave subtraction, reference wave subtraction, reference image subtraction, and the variable time window amplitude mapping method. The advantages and disadvantages of AWPI algorithms are reported in terms of reference data requirements, signal-to-noise ratios, and damage evaluation accuracy. The compactness and portability of the proposed UPI system are also important for in-field applications at wind farms.

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.

Wind energy, increasing its share in the generation mix, is intended to replace fossil fuel plants in order to reduce green house gas emissions. However, the replacement of conventional synchronous units by wind generators reduces the number of online Power Systems Stabilizers (PSS) and may therefore deteriorate the damping of critical swing modes, leading to a reduction of the power transfer capacity in transmission corridors. Several reports indicate that angular instability, due to insufficient damping and inadequate tuning or disabling of power system stabilizers, is one of the major events that lead and/or contributed to wide area blackouts. Variable speed wind turbine generators are capable of fast decoupled real and reactive power control. A damping torque can be generated by modulating a fraction of the real and reactive power output of the wind farm. Supplementary active and reactive power control loops are designed and integrated in the wind turbine controls. Operating limits are added to restrict the kinetic energy exchange of the supplementary control loop within a specified turbine speed. An analytical method is developed in order to assess the effectiveness of real and reactive power modulation in damping inter-area oscillations and to justify the use and commissioning of wind based PSS. A wide area measurement based power system stabilizer suitable for wind farms is designed and integrated in the global and local controls of wind turbines. Feedback signals are selected based on an observability index of the selected mode(s). The proposed stabilizer transfer function is derived via a constrained Hinfinity optimization. The controller is tested in time domain simulations using a two area four generators benchmark suffering from interarea oscillatory mode within the range of 0.4-0.6Hz. Testing scenarios show the resiliency and effectiveness of the wind based PSS in damping angular oscillations and stabilizing the power system. The damping contribution of the wind stabilizer is found to be comparable to two conventional PSS.

The ever increasing demand for renewable energy, combined with limited areas suitable for large wind farms, has put focus on the development of floating wind turbines. In this thesis the dynamic response of a floating wind turbine, subjected to forces from wind and waves, is analyzed. The wind turbi...

Vertical axis wind turbines (VAWT) transform up to 45 percent of the wind power to electricity, whereas the more common horizontal axis wind turbines (HAWT) are able to make use of 25-40 percent of the wind power. The expanding commercial wind power market is now starting to invest in the VAWT technology.

The global production of electricity from wind power has increased significantly in recent years. As part of Hydro-Quebec's plans to increase wind power production, Cartier Wind Power plans to install 61 wind turbines at Baie-des-Sables on Quebec's Gaspe Peninsula where wind energy is abundant. This study evaluated the impact of the proposed wind turbine array on birds and their habitat and migration patterns. In particular, it characterized the migratory passage of birds in the area through 900 hours of visual and auditory observation beginning with spring migration, spring nesting to autumnal migration. The behavior of different migratory birds as well as local species was studied and the results of the ornithological inventory were revealed in terms of species abundance and diversity; distribution and use of the territory by birds; migratory activities; period and importance of migration; characterization of displacement; height of flight; direction of migration; and, use of the territory by the avifauna. The inventory identified 121 species of birds including 14 species of raptors which moved mainly along the river and flew very high. The study revealed that although the bird habitats at Baie-des-Sables were already strongly disturbed by agricultural activities, it is unlikely that the turbines will not have any impact on the avifauna. However, most of the wind turbines will be installed in farmers fields, and as such, will not exert additional pressure on the forest medium. The factors that influence the rate of bird collisions with wind turbines were discussed. In order to lessen the impact on birds, it was suggested that installation work should occur outside of the nesting season and that the electrical supply networks should be hidden to limit the harmful effects posed by power lines. 16 refs., 9 tabs., 4 figs., 11 maps, 9 appendices.

Information is presented on the development of various types of windmills or wind turbines and their applications. American-made wind turbines are reviewed for their design, specifications, and capabilities.

Jun 12, 2008 ... DETERMINE RAYLEIGH LASER FILTER CONVOLUTION. 41. ACCESS ...... turbines and towers, up to and including collapse. mapping wind ..... several ranges of a cone 724 ahead of the wind turbine 702. 6. The method of ...

In this paper, we investigate three design options to minimize cogging torque: uniformity of air gap, pole width, and skewing. Although the design improvement is intended for small wind turbines, it is also applicable to larger wind turbines.

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.

...disturbance from offshore wind development, and...from off-shore wind development (Oham...effects of hydropower turbines, most of which were...files continues to support the escapement figures...work will inform turbine operations and the...bar racks, bypass structures, etc.)...

...existing small-scale wind energy facilities, such as single-turbine demonstration projects...large, multi-turbine commercial wind facilities. Covered...used as a decision support tool for the selection...species''. MSHCP Structure In 2009, the...

Glenn constructed its initial experimental 100-kilowatt (kW) wind turbine at the ... and cost of turbine structures, they developed steel tube towers that replaced .... in the advancement of wind energy; Glenn, for example, is supporting the plans ...

This site has step-by-step instructions on how to build a wind turbine with parts you can purchase from the hardware store and e-bay. The website includes photographs and text which illustrate how to build the wind turbine.

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.

There is an increased international interest in electrical simulation models of wind turbines for stability analysis and interconnection studies. So-called ''generic'' models, with a model structure that is publicly available, have been required in the USA by many utilities. A working group of the Western Electricity Coordinating Council (WECC) and IEEE has developed models for different types of generators, among others for wind turbines using doubly fed induction generators (DFIG) and full size converters (FSC). Those models were so far mainly used in the USA, and the models were able to represent wind turbines with respect to common US grid code requirements. Due to an increased international interest in generic models, there is a need for updating existing models in order to improve the accuracy of the models since validation requirements in many countries now require a comparison with measurements (and not to more detailed simulation models only). It can be shown that the proposed model allows for an improved representation of the aerodynamic effects during grid faults compared to existing model approaches based on cp {lambda}-tables while still requiring far less parameters. The results of simulations using the proposed generator model are compared to measurements during voltage dips of a 2MW and 6MW wind turbine. The new generic aerodynamic model will be proposed as extension for the WECC/IEEE aerodynamic models as well as basis for the draft of the IEC TC88 working group 27 (61400-27) on modelling and model validation. (orig.)

It is a known fact that the power produced by wind turbines operating inside an array decreases due to the wake effects of the upstream turbines. It has been proposed previously to use the yaw mechanism as a potential means to steer the upstream wake away from downstream turbines, however such a mechanism introduces control complications due to changing wind directions. Deflecting the wake in the vertical direction using tilt, on the other hand, overcomes this challenge. In this paper, the feasibility of steering wake is explored in a simple uniform inflow case. This is done by trying to model the wake deflection as a function of the yaw/tilt angle and the rotor thrust, initially using the momentum and vortex theories. Thereafter, a relatively more promising empirical model based on a set of actuator disc CFD computations is proposed. Finally, comments are made on the feasibility of wake control using yaw/tilt.

This paper addresses the optimal operation of an offshore wind farms (OWF), consisting of 120 wind turbines with doubly fed induction generators (DFIG) and a high voltage dc (HVdc) connection with the grid, using line commutated converters (LCC). For an optimal operation of the OWF, the distribution of the reactive power set points throughout the wind turbine generators must be optimal, in order to achieve minimum losses within the wind farm and the HVdc transmission system and therefore obtain the maximum production output. To accomplish this objective, an optimization formulation has been proposed which includes a complete model of the OWF and the LCC-HVdc, and the study of two different configurations. Simulation results show the advantages of using the reactive capability of the DFIG t...

Frequency regulation in a generation mix having large wind power penetration is a critical issue, as wind units isolate from the grid during disturbances with advanced power electronics controllers and reduce equivalent system inertia. Thus, it is important that wind turbines also contribute to system frequency control. This paper examines the dynamic contribution of doubly fed induction generator (DFIG)-based wind turbine in system frequency regulation. The modified inertial support scheme is proposed which helps the DFIG to provide the short term transient active power support to the grid during transients and arrests the fall in frequency. The frequency deviation is considered by the controller to provide the inertial control. An additional reference power output is used which helps the...

...including collisions with wind turbines and associated infrastructure...degradation of habitat from turbines and infrastructure; fragmentation...designs usually include a single turbine associated with existing...helicopter; equipment needed for acoustic, telemetry, or radar...

The aims of this thesis were to describe and gain an understanding of how people who live in the vicinity of wind turbines are affected by wind turbine noise, and how individual, situational and visual factors, as well as sound properties, moderate the response. Methods A cross-sectional study was carried out in a flat, mainly rural area in Sweden, with the objective to estimate the prevalence of noise annoyance and to examine the dose-response relationship between A-weighted sound pressure levels (SPLs) and perception of and annoyance with wind turbine noise. Subjective responses were obtained through a questionnaire (n = 513; response rate: 68%) and outdoor, A-weighted SPLs were calculated for each respondent. To gain a deeper understanding of the observed noise annoyance, 15 people living in an area were interviewed using open-ended questions. The interviews were analysed using the comparative method of Grounded Theory (GT). An additional cross-sectional study, mainly exploring the influence of individual and situational factors, was carried out in seven areas in Sweden that differed with regard to terrain (flat or complex) and degree of urbanization (n = 765; response rate: 58%). To further explore the impact of visual factors, data from the two cross-sectional studies were tested with structural equation modelling. A proposed model of the influence of visual attitude on noise annoyance, also comprising the influence of noise level and general attitude, was tested among respondents who could see wind turbines versus respondents who could not see wind turbines from their dwelling, and respondents living in flat versus complex terrain. Dose-response relationships were found both for perception of noise and for noise annoyance in relation to A-weighted SPLs. The risk of annoyance was enhanced among respondents who could see at least one turbine from their dwelling and among those living in a rural in comparison with a suburban area. Noise from wind turbines was appraised as an intrusion of privacy among people who expected quiet and peace in their living environment. Negative experiences that led to feelings of inferiority added to the distress. Sound characteristics describing the amplitude modulated aerodynamic sound were appraised as the most annoying (swishing, whistling and pulsating/throbbing). Wind turbines were judged as environmentally friendly, efficient and necessary, but also as ugly and unnatural. Being negative towards the visual impact of the wind turbines on the landscape scenery, rather than towards wind turbines as such, was strongly associated with annoyance. Self-reported health impairment was not correlated to SPL, while decreased well-being was associated with noise annoyance. Indications of possible hindrance to psycho-physiological restoration were observed. Wind turbine noise is easily perceived and is annoying even at low A-weighted SPLs. This could be due to perceived incongruence between the characteristics of wind turbine noise and the background sound. Wind turbines are furthermore prominent objects whose rotational movement attracts the eye. Multimodal sensory effects or negative aesthetic response could enhance the risk of noise annoyance. Adverse reactions could possibly lead to stress-related symptoms due to prolonged physiological arousal and hindrance to psychophysiological restoration. The observed differences in prevalence of noise annoyance between living environments make it necessary to assess separate dose-response relationships for different types of landscapes.

The aim of this protocol of agreement is to propose to wind turbine fitters some models of contracts allowing the setting up of wind turbines on agricultural lots. These documents, which make an indissociable ensemble, apply to both phases of development of a wind power project: the feasibility study phase, for a duration comprised between 2 and 5 years (studies, administrative procedures, precise definition of the project), and the construction, exploitation and dismantling phase. These documents will serve as common guidelines for both the farmers and the wind turbine designers. Both parties agree to meet together in the future to propose some modifications of these texts if necessary. The four models of contracts are attached to the document: contract for the feasibility study phase, first contract between the landlord and the farmer for the cancellation of the rural lease, second contract between the landlord and the wind power exploitation company for the common right lease, and the third contract between the farmer and the wind power company for the indemnification convention. (J.S.)

The purpose of this paper is to gain a greater understanding of the performance of practical wind turbine generating systems with differing output power controllers and controlling means for wind turbine speed. Subjected wind turbines, both equipped with an asynchronous power generator, are located at two sites and are defined as wind turbine A and wind turbine B in this study, respectively. Their performance differences are examined by measuring wind speed and electric parameters. The study suggests that both wind turbines have a clear linkage between current and output power fluctuations. Comparison of the fluctuations to wind speed fluctuation, although they are triggered primarily by wind speed fluctuation, clearly indicates the specific behaviors inherent to the respective turbine control mechanisms.   

The first multi-wind turbine is being built on the Maasvlakte (near Rotterdam). Total installed capacity will be 450 kW, which will be generated by six wind turbines on one shaft. Construction and performance testing will demonstrate if this alternative way of scaling-up will result in a cost-effective wind turbine for generation of electric power. For this application a two-blade Lagerwey wind turbine, rotor diameter: 15 m, has been chosen. 4 refs.

The cup anemometers commonly used for wind energy applications are fairly robust, but suffer from several drawbacks like their limited temporal resolution, a systematic overestimation of the wind speed in turbulent flows and the inability to measure the wind direction. While sonic anemometers can measure the wind vector at a higher temporal resolution, they are more fragile and significantly more expensive. Therefore, we propose the sphere anemometer as a robust and highly-resolving alternative to standard anemometers. Designed without wearing parts, the sphere anemometer provides simultaneous wind speed and direction measurements as needed for wind turbine operation especially under challenging conditions such as offshore installation. In our contribution, we introduce the setup of the sphere anemometer which is based on the velocity-dependent deflection of a flexible tube with a sphere mounted atop. The deflection is measured in two dimensions using a light pointer, which allows for the simultaneous determination of wind speed and direction via calibration. Experimental results from wind tunnel measurements with sonic anemometer and sphere anemometer are presented, as well as first comparative measurements from the operation on the nacelle of a near-shore wind turbine.

Emerging technologies for marine current turbines are mainly related to works that have been carried out on wind turbines and ship propellers. It is then obvious that many electric generator topologies could be used for marine current turbines. As in the wind turbine context, doubly-fed induction ge...

Large numbers of wind farms have been and will be built in tropical cyclone zones. However historical events of wind turbine failures in typhoon or hurricane activities have illuminated that there is some defect in wind turbine design, due to not giving enough consideration on the effects of cyclone activity on wind turbine operating. Using observation data of meteorological wind towers, this study analyzes the variations of wind speed, turbulence and wind direction of super typhoon Saomai, when it was passing through Hedingshan wind farm of Zhejiang province in 2006. The reasons for wind turbine failures in the typhoon activity are clarified. The violent wind, drastic turbulence and sudden change of wind direction are major factors of wind turbine failures, in which exposes the design def...

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.

The development associated with large wind turbine systems is briefly described. The scope of this activity includes the development of several large wind turbines ranging in size from 100 kW to several megawatt levels. A description of the wind turbine systems, their programmatic status and a summary of their potential costs is included.

...Impact (FONSI) for Small Vertical Wind Turbine and Solar Installation at the Paul Simon...construction of a small vertical axis wind turbine and solar cells at the Paul Simon Job...Impact (FONSI) for Small Vertical Wind Turbine and Solar Installation at the Paul...

Feb 13, 2009 ... Abstract: Wind turbine generators, ranging in size from a few kilowatts to ... Mod-1 2-MW wind turbine, which is described in detail elsewhere. ... and remedies of noise from wind turbines form the foundation of much of the ...

Damping of low frequency power oscillations is one of essential aspects of maintaining power system stability. In literature can be found publications on damping capability of Doubly Fed Induction Generator based wind turbines. This paper extends discussion on Wind Power Plant damping capability to Full-Scale Converter based type. Moreover resemblance of such Wind Power Plant to modern FACTS devices is recognized and exploited. Paper discusses many aspect of damping controller design, including feedback signal selection and control effectiveness with respect to wind farm location. Analysis and design is based on modal analysis, therefore matching modeling approach for wind power plant is proposed. Finally, performance of Wind Power Plant damping control is compared to a regular power system stabilizer installed on a synchronous generator.

Canadian federal and provincial governments have launched programs and policies to promote wind energy technology. The wind energy capacity in Canada has recently surpassed 1000 MW. In addition, numerous proposals for industrial expansion have surfaced in most provinces and territories. It is anticipated that a minimum of 8000 MW of wind energy may be installed in Canada by 2015. There are several micro-, small- and large-scale wind power companies that can provide the goods and services needed to develop a project. The wind industry is composed of component manufacturers, project developers, distributors, installers, suppliers, consulting firms and public utilities. This directory of businesses in the Canadian wind power industry is compiled alphabetically by company names. For each listing, the inventory includes a world wide web address and information on whether the company manufactures components, equipment, towers or turbines. The inventory tags each company according to the services they provide, such as engineering, construction, maintenance, financial, consulting, environmental, equipment sales, or project development.

Power system deregulation, shortage of transmission capacities and needing to reduce green house gas have led to increase interesting in distributed generations (DGs) especially renewable sources. This study developed a complete model able to analysis and simulates in details the transient dynamic performance of the Micro-Grid (MG) during and subsequent islanding process. Wind speed fluctuations cause high fluctuations in output power of wind turbine which lead to fluctuations of frequency and voltages of the MG during the islanding mode. In this paper a new fuzzy logic pitch angle controller is proposed to smooth the output power of wind turbine to reduce MG frequency and voltage fluctuations during the islanding mode. The proposed fuzzy logic pitch controller is compared with the convent...

In this paper, a network power flux control of a variable speed wind generator is investigated. The wind generator system consists of a doubly fed induction generator (DFIG) connected to the network associated to a flywheel energy storage system (FESS). The dynamic behaviour of a wind generator, including the models of the wind turbine, the doubly fed induction generator, the back-to-back AC/AC converter, the converter control and the power control of this system, is studied. Is also investigated a control method of the FESS system which consists of the classical squirrel-cage induction machine (IM) supplied off the variable speed wind generator (VSWG). In order to verify the validity of the proposed method, a dynamic model of the proposed system has been simulated, for different operating...

In this paper, a contribution to improvement of the performances for wind energy conversions systems (WECS) is investigated. This paper introduces, on one hand, a direct AC-AC matrix converter system as an alternative to the conventional AC-DC-AC converter configuration for the WECS and the two-quadrant operated mode of the DFIG, on the other one. The WECS considered is based to the wind turbine (aerodynamic), doubly-fed induction generator (DFIG), the AC/AC direct converter and the flywheel energy storage system (FESS). Simulation results obtained on the basis of the dynamic models of the wind generator are presented, for different operating points, to demonstrate the performance of the proposed system.

With increasing wind power penetration, transient responses of doubly-fed-induction-generator (DFIG) based wind turbines gain attentive focus. Accurate prediction of transient performance of DFIG under grid faults is required with increasing wind power penetration. Taking into account the main flux saturation and deep-bar effect, this paper concentrates on transient responses and stability of the DFIG system under symmetrical grid faults. Their roles played in the enhancement of system transient stability are clarified. The analyses proposed contribute greatly to proper selection, design and coordination of protection devices and control strategies as well as stability studies.

The power curve of a wind turbine is the primary characteristic of the machine as it is the basis of the warranty for it power production. The current IEC standard for power performance measurement only requires the measurement of the wind speed at hub height and the air density to characterise the wind field in front of the turbine. However, with the growing size of the turbine rotors during the last years, the effect of the variations of the wind speed within the swept rotor area, and therefore of the power output, cannot be ignored any longer. Primary effects on the power performance are from the vertical wind shear and the turbulence intensity. The work presented in this thesis consists of the description and the investigation of a simple method to account for the wind speed shear in the power performance measurement. Ignoring this effect was shown to result in a power curve dependant on the shear condition, therefore on the season and the site. It was then proposed to use an equivalent wind speed accounting for the whole speed profile in front of the turbine. The method was first tested with aerodynamic simulations of a multi-megawatt wind turbine which demonstrated the decrease of the scatter in the power curve. A power curve defined in terms of this equivalent wind speed would be less dependant on the shear than the standard power curve. The equivalent wind speed method was then experimentally validated with lidar measurements. Two equivalent wind speed definitions were considered both resulting in the reduction of the scatter in the power curve. As a lidar wind profiler can measure the wind speed at several heights within the rotor span, the wind speed profile is described with more accuracy than with the power law model. The equivalent wind speed derived from measurements, including at least one measurement above hub height, resulted in a smaller scatter in the power curve than the equivalent wind speed derived from profiles extrapolated from measurements at hub height and below only. It is well established that the turbulence intensity also influences the power performance of a wind turbine. Two ways of accounting for the turbulence were tested with the experimental data: an adaptation of the equivalent wind speed so that it also accounts for the turbulence intensity and the combination of the equivalent wind speed accounting for the wind shear only with the turbulence normalising method for turbulence intensity suggested by Albers. The second method was found to be more suitable for normalising the power curve for the turbulence intensity. Using the equivalent wind speed accounting for the wind shear in the power performance measurement was shown to result in a more repeatable power curve than the standard power curve and hence, in a better annual energy production estimation. Furthermore, the decrease of the scatter in the power curve corresponds to a decrease of the category A uncertainty in power, resulting in a smaller uncertainty in estimated AEP. (author)

Modern wind turbines are predominantly variable speed wind turbines with power electronic interface. Emphasis in this paper is therefore on the modelling and control issues of these wind turbine concepts and especially on their impact on the power system. The models and control are developed and implemented in the power system simulation tool DIgSILENT. Important issues like the fault ride-through and grid support capabilities of these wind turbine concepts are addressed. The paper reveals that advanced control of variable speed wind turbines can improve power system stability. Finally, it will be shown in the paper that wind parks consisting of variable speed wind turbines can help nearby connected fixed speed wind turbines to ride-through grid faults. Copyright © 2009 John Wiley & Sons, Ltd.

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 control system operation and overall wind farm stability. The same wind turbine converter control strategy is evaluated in two different wind farms. It is emphasized that the grid-side converter controller should be characterized 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 emphasize differences between the two wind farms.

The objectives of the study were to investigate the feasibility of modifying civil and military radars to mitigate the effects from wind turbines, to provide costings for implementing changes to the radar and to produce guidelines for planning wind farms in the vicinity of radars. The effect of wind turbines on radar signals, assessed through computer modelling, is summarised. The key aspects of turbine design that can be modified to minimise these effects are described. A key issue is the fact that no two radar installations are alike, with settings being customised for local requirements. As a consequence, a detailed understanding of the design and features of each individual radar would be required in order to assess the impact of a wind farm proposal. The costs of a programme of modifications to the civil ATC (air traffic control) radar base will depend on many factors. An estimate of costs is provided, based on the assumption that only 30 of the UK radars would need modification and that a range of modifications from very simple to very complex will be required. A number of other approaches, outside of modification of the radar system, may require investigation during a windfarm planning application, such as layout and location of the wind farm or changing air traffic routes in the vicinity of the wind farm.

Larger percentages of wind power penetration translate into more demanding requirements from the grid codes; for example voltage support at the point of connection has been introduced recently by several grid codes from around the world, making it important to analyze this control when applied to wind power plants. This paper proposes two different VAr reserve control strategies for a wind power plant. The amount of dynamic VAr available most of the operation time, makes the wind power plant (WPP) a good candidate to include a VAr reserve management system. Two different ways of implementing a VAr management system are proposed and analyzed. Such a reactive power reserve may be provided by the wind power plant since the amount of reactive power installed for most active power working points exceeds the demand required by the grid operator. Basically, this overrated reactive power capacity is a consequence of sizing wind turbine facilities for maximum active power level. The reactive power losses, due to active power transportation inside the plant (normally two transformers), and P-Q wind turbine characteristics define the P-Q reserve chart. By utilizing the intrinsic overrated reactive power capacity, additional devices, such as for example SVCs and STATCOMs, can be avoided in other locations of the grid.

In order to increase our efficiency of energy capture in wind farms, optimize turbine arrangements, and adapt wind-turbine technology to optimal performance in common atmospheric conditions such as low level jets (LLJ), it is critical to understand the dynamic interactions between turbulence and multiple wind turbines. Ambient atmospheric turbulence interacts with spinning turbines producing the critical mechanism for the recovery of the wind field behind a wind turbine. This turbine-influenced turbulent wind field creates the environment surrounding downstream turbines in a wind farm, thus controlling the amount of wind energy available for harvesting as well as the nature of the wear and tear that downwind turbines endure. The strength of the turbulent structures and their length-scales evolve downstream. Thus, the conditions to which downstream turbines are exposed, their productivity, and potentially their lifespan is a function of their position within the turbulent wake of upstream turbines. A numerical technique, WindBlade, has been developed for characterizing the interaction of spinning wind turbines and unsteady/heterogeneous atmospheric boundary layers at length scales ranging from blade-chord-scale (meters) to turbine-array-scale (multiple kilometers). This implementation of this technique combines an R&D100 winning numerical tool, HIGRAD/FIRETEC, a fully-compressible atmospheric hydrodynamics model with novel techniques to capture forces exchanged between the atmosphere and turbine as it rotates. The blade-induced forces on the wind field over the along the span of spinning turbine blades interacts with any oncoming atmospheric turbulence or shear, thus producing turbine wakes which are functions of turbine blade geometry and pitch, rotation speed, topographic and vegetation influences, and of course ambient wind speed, direction, shear, and turbulence. TurbSim, which creates vertical planes of three-dimensional turbulent wind fields based on empirical data from various sites, is used to initialize the turbulence in the domain initially and then the produce dynamically evolving turbulent wind inflow conditions. WindBlade simulations have been performed to study the integrated impact of blade chord-scale force exchange between atmosphere and turbines on downstream wakes in conditions ranging from idealized laminar winds to empirically-based TurbSim turbulent LLJ conditions. This series of simulations reveal that the dynamic interaction between turbines and ambient turbulence has drastic effects on the wake structure and recovery. Functional relationships between downstream-turbine conditions and separation distance are strongly influenced by the ambient turbulence. These simulations explicitly illustrate evolution of length scales in the turbine wake and suggest optimal separation distance for turbines in a wind farm is likely a balance between available wind energy for harvesting and optimizing the nature of the turbulence that the turbine must continuously endure.

By utilizing condition monitoring information collected from wind turbine components, condition based maintenance (CBM) strategy can be used to reduce the operation and maintenance costs of wind power generation systems. The existing CBM methods for wind power generation systems deal with wind turbine components separately, that is, maintenance decisions are made on individual components, rather than the whole system. However, a wind farm generally consists of multiple wind turbines, and each wind turbine has multiple components including main bearing, gearbox, generator, etc. There are economic dependencies among wind turbines and their components. That is, once a maintenance team is sent to the wind farm, it may be more economical to take the opportunity to maintain multiple turbines, an...

This report summarizes the results of a power performance test that NREL conducted on the ARE 442 wind turbine. This test was conducted in accordance with the International Electrotechnical Commission's (IEC) standard, Wind Turbine Generator Systems Part 12: Power Performance Measurements of Electricity Producing Wind Turbines, IEC 61400-12-1 Ed.1.0, 2005-12. However, because the ARE 442 is a small turbine as defined by IEC, NREL also followed Annex H that applies to small wind turbines. In these summary results, wind speed is normalized to sea-level air density.

Due to years of growth in installed wind power, new sites for wind turbines are in constant demand. With increased use of ever more complex sites, local wind phenomena can be expected to greatly increase the load on wind turbines. This work describes how Large-Eddy Simulation (LES) can be used to es...

Offshore wind is an attractive source of renewable energy. In order to harvest this abundant energy source wind turbine farms are needed. In order to extend the application of offshore fixed wind turbine (OFWT) in deep water where winds are stronger and steadier, there are research works on fi...

BPA has been asked by PPM Energy, Inc. to interconnect 300 megawatts (MW) of electricity generated from the proposed Klondike III Wind Project to the Federal Columbia River Transmission System. Orion Energy LLC has also asked BPA to interconnect 400 MW of electricity from its proposed Biglow Canyon Wind Farm, located north and east of the proposed Klondike III Wind Project. (Portland General Electric recently bought the rights to develop the proposed Biglow Canyon Wind Farm from Orion Energy, LLC.) Both wind projects received Site Certificates from the Oregon Energy Facility Siting Council on June 30, 2006. To interconnect these projects, BPA would need to build and operate a 230-kV double-circuit transmission line about 12 miles long, expand one substation and build one new substation. The wind projects would require wind turbines, substation(s), access roads, and other facilities. Two routes for the transmission line are being considered. Both begin at PPM's Klondike Schoolhouse Substation then travel north (Proposed Action) or north and westerly (Middle Alternative) to a new BPA 230-kV substation next to BPA's existing John Day 500-kV Substation. BPA is also considering a No Action Alternative in which BPA would not build the transmission line and would not interconnect the wind projects. The proposed BPA and wind projects would be located on private land, mainly used for agriculture. If BPA decides to interconnect the wind projects, construction of the BPA transmission line and substation(s) could commence as early as the winter of 2006-07. Both wind projects would operate for much of each year for at least 20 years. The proposed projects would generally create no or low impacts. Wildlife resources and local visual resources are the only resources to receive an impact rating other than ''none'' or ''low''. The low to moderate impacts to wildlife are from the expected bird and bat mortality and the cumulative impact of this project on wildlife when combined with other proposed wind projects in the region. The low to high impacts to visual resources reflect the effect that the transmission line and the turbine strings from both wind projects would have on viewers in the local area, but this impact diminishes with distance from the project.

Offshore wind turbines for electricity production placed in wind farms are expected to be of one of the major future contributors for sustainable energy production. In this paper some of the problems associated with optimal planning and design of wind turbine parks are addressed. The number of wind turbines in a park is usually restricted to be placed within a fixed, limited geographical area. Behind a wind turbine a wake is formed where the mean wind speed decreases and the turbulence intensity increases. The distance between the turbines is among other things dependent on the recovery of wind energy behind the neighboring turbines and the increased wind load. Models for the mean wind speed and turbulence intensity in wind turbine parks are considered with emphasis on modeling the spatial correlation. Representative limit state equations for structural failure of wind turbine towers are formulated. The probability of failure is determined taking into account that wind turbines are parked for wind speeds larger than 25 m/s resulting in reduced wind loads. An illustrative example is presented where illustrative models for the spatial correlation is taken into account.

The paper analyses the wind input to a cup-anemometer and to a wind turbine to evaluate the definition of the ``measured`` wind speed relative to the ``measured`` power and mean loads. The analysis is based on an artificial 3D wind of 8m/s and 0%, 10% and 20% turbulence intensity, respectively, and theoretical models of a cup-anemometer and a wind turbine. A 3D dynamic response code is used to calculate the ``measured`` wind speed by the cup-anemometer and a 3D aeroelastic code is used to ``measure`` the power and flapwise root bending moment of one blade on the wind turbine. Flow distortion effects due to topography, mast, boom, clamps, etc. are not considered, and full correlation between the wind speed at the cup-anomometer and the wind speed at the hub of the wind turbine is assumed. The ``measured`` data are compared to the well-described artificial wind under different definitions of the wind speed. (Author)

A group of students at UMB in Aas (Norway) are working to make it cheaper to produce energy from ocean wind. With a new floating ocean wind, they outclassed Hywind and compete with fixed wind turbines. (AG)

...be focused solely on offshore wind energy projects. Applications...stand-alone or combined with offshore wind turbine support structures, will not be accepted. DOE may...execution of innovative offshore wind energy projects and...

This work examines the distribution of changes in wind power for different time scales in the regulation time frame as well as the correlation of changes in power output for individual wind turbines in a wind plant.