Showing papers on "Blade pitch published in 2004"

Power system frequency response from fixed speed and doubly fed induction generator-based wind turbines

Abstract: Throughout Europe there is an increasing trend of connecting high penetrations of wind turbines to the transmission networks. This has resulted in transmission system operators revising their grid code documents for the connection of large wind farms. These specifications require large MW capacity wind farms to have the ability to assist in some of the power system control services currently carried out by conventional synchronous generation. These services include voltage and frequency control. It is now recognized that much of this new wind generation plant will use either fixed speed induction generator (FSIG)- or doubly fed induction generator (DFIG)-based wind turbines. The addition of a control loop to synthesize inertia in the DFIG wind turbine using the power electronic control system has been described. The possibility of deloading wind turbines for frequency response using blade pitch angle control is discussed. A pitch control scheme to provide frequency response from FSIG and DFIG wind turbines is also described. A case study of an FSIG wind turbine with frequency response capabilities is investigated. Copyright © 2004 John Wiley & Sons, Ltd.

Method and apparatus for wind turbine rotor load control based on shaft radial displacement

Abstract: Vertical and horizontal wind shears, yaw misalignment and/or turbulence act together to produce asymmetric loading across a wind turbine rotor. The resultant load produces bending moments in the blades that are reacted through the hub and subsequently to the main shaft. As a result, the main shaft may be radially displaced from its at rest positions. The amount of radial displacement is measured using two or more sensors. The output signals from the sensors are used to determine the magnitude and/or the orientation of the resultant rotor load. This information is used to affect the blade pitch change or other action with similar system effect to reduce the asymmetric load and thereby reduce fatigue and loading on various turbine components.

Wind turbine generator, active vibration damping method for the same, and wind turbine tower

Abstract: A wing turbine generator, an active vibration damping method for the generator, and a wind turbine tower, where the reduction in vibration of the wind turbine generator and the wind turbine tower can be achieved at a low cost. Acceleration of vibration of a nacelle (13) is measured by an accelerometer (17) fixed to the nacelle (13). Based on the acceleration measured, an active vibration damping section (20) calculates a wind turbine blade (12) pitch angle that causes the wind turbine blade (12) to produce thrust to cancel vibration of the nacelle (13), and outputs the result as a damping blade pitch angle command δθ*. On the other hand, a pitch angle control section (30) calculates a wind turbine blade (12) pitch angle for setting the output to a specific value and outputs the result as a blade pitch angle command θ* for output control. A subtractor (40) superposes the vibration damping blade pitch angle command δθ* on the output controlling blade pitch angle command θ* and controls the pitch angle of the wind turbine blade based on a superposed blade pitch angle command.

Methods for increasing region 2 power capture on a variable speed hawt

Abstract: β blade pitch (degrees) ψ yaw error (degrees) M adaptive gain (m 5 /rad 3 ) The standard region 2 control scheme for a variable speed wind turbine, τc = kω 2 , has several shortcomings that can result in significant power loss. The first of these is that there is no accurate way to determine the gain k; modeling programs are not accurate enough to represent all of the complex aerodynamics, and these aerodynamics change over time. Furthermore, it is not certain whether the value of k used in the standard control even provides for the maximum energy capture under real-world turbulent conditions. New control ideas are introduced to address these issues. First, it is shown in simulation that using smaller values of k than the standard can result in increased energy capture. Second, an optimally tracking rotor control scheme improves upon the standard scheme by assisting the rotor speed in tracking wind speed fluctuations more rapidly. Finally, an adpative control scheme is proposed that allows for maximum power capture despite parameter uncertainty. n number of steps in adaptation period K∆M positive gain on adaptation law (rad 3 /m 5

Design of Controls to Attenuate Loads in the Controls Advanced Research Turbine

Abstract: Designing wind turbines to maximize energy production and increase fatigue life is a major goal of the wind industry. To achieve this goal, we must design wind turbines to extract maximum energy and reduce component and system loads. This paper applies modern state-space control design methods to a two-bladed teetering-hub upwind machine located at the National Wind Technology Center. The design objective is to regulate turbine speed in region 3 (above rated wind speed) and enhance damping in several lowdamped flexible modes of the turbine. The controls approach is based on the Disturbance Accommodating Control (DAC) method and provides accountability for wind-speed disturbances. First, controls are designed using the single control input rotor collective pitch to stabilize the first drive-train torsion as well as the tower first fore-aft bending modes. Generator torque is then incorporated as an additional control input. This reduces some of the demand placed on the rotor collective pitch control system and enhances first drive train torsion mode damping. Individual blade pitch control is then used to attenuate wind disturbances having spatial variation over the rotor and effectively reduces blade flap deflections caused by wind shear.

Blade-pitch-angle control device and wind power generator

Abstract: A blade-pitch-angle control device includes a memory unit in which predetermined parameters that affect the load fluctuation of blades, azimuth angles, and pitch-angle command values are stored in association with each other; an azimuth-angle detecting unit that detects the azimuth angle of each of the blades; a parameter-detecting unit that detects the predetermined parameters; a command-value receiving unit that receives pitch-angle command values for each of the blades from the memory unit, the pitch-angle command values being selected on the basis of the azimuth angle of each blade detected by the azimuth-angle detecting unit and the predetermined parameters detected by the parameter-detecting unit; and a pitch-angle-control command-value generating unit that generates pitch-angle-control command values for individually controlling the pitch-angle of each blade on the basis of the pitch-angle command values and a common-pitch-angle command value.

Blade pitch angle control device and wind turbine generator

Abstract: A blade-pitch-angle control device includes a memory unit (10) in which predetermined parameters that affect the load fluctuation of blades, azimuth angles, and pitch-angle command values are stored in association with each other; an azimuth-angle detecting unit (11) that detects the azimuth angle of each of the blades; a parameter-detecting unit (12) that detects the predetermined parameters; a command-value receiving unit (13) that receives pitch-angle command values for each of the blades from the memory unit (10), the pitch-angle command values being selected on the basis of the azimuth angle of each blade detected by the azimuth-angle detecting unit (11) and the predetermined parameters detected by the parameter-detecting unit (12); and a pitch-angle-control command-value generating unit (14) that generates pitch-angle-control command values for individually controlling the pitch-angle of each blade on the basis of the pitch-angle command values and a common-pitch-angle command value.

Methods and apparatus for twist bend coupled (TCB) wind turbine blades

Abstract: A method for controlling a wind turbine having twist bend coupled rotor blades on a rotor mechanically coupled to a generator includes determining a speed of a rotor blade tip of the wind turbine, measuring a current twist distribution and current blade loading, and adjusting a torque of a generator to change the speed of the rotor blade tip to thereby increase an energy capture power coefficient of the wind turbine.

Analysis of tower/blade interaction in the cancellation of the tower fore-aft mode via control

Abstract: With the increase in size of wind turbines, there is increasing interest in exploiting the pitch control capability of variable speed turbines to alleviate tower fatigue loads. The most direct method is to modify the blade pitch angle in response to a measurement of tower acceleration. It is shown that the ap mode has a central role in determining whether this approach is effective since there is a strong interaction between the blade ap-wise mode and the tower fore-aft mode. Several different approaches to the design of the controller for the tower speed feedback loop are investigated. It is concluded that a reduction in the tower loads of up to 18% is possible for multi-megawatt sized wind turbines.

Wind turbine having airfoils for blocking and directing wind and rotors with or without a central gap

Abstract: A wind turbine device (100) of increased efficiency is comprised of a set of fixed airfoils (104, 106) that direct wind into a rotor (102) having a plurality of blades (120, 122). The fixed airfoils may extend to the ground to increase the amount of wind directed into the rotor and may be manufactured from concrete. The rotor blades have a vented portion (114) near the axis of rotation that has been found to increase efficiency for certain blade geometries. For other blade geometries, increased efficiency is observed with no gap at the axis of rotation. The rotor may also be manufactured from composite materials to increase strength while decreasing the moment of inertia for the rotor.

Rotor and aircraft passively stable in hover

Abstract: The present invention discloses a rotor that enables an aircraft to be passively stable in hover The rotor, having a generally fixed geometry is tiltably connected to its rotor shaft The outer part of the rotor blades have a pitch fixed relative to the rotational plane, whereas the inner part of the rotor blades have a pitch fixed relative to a reference plane perpendicular to the rotor shaft

Early Stall Warning Technique for Axial-Flow Compressors

Abstract: This paper proposes a unique stall warning index based on pressure signals by high response transducers on the casing wall at the rotor leading edge location. The aim of the research is to explore the possibility of reducing current excessive stall margin requirement for compressor design based on the worst case scenario. The index is generated by computing correlation degradation of pressure time histories of current and one revolution before over each blade pitch. Tests conducted on a research compressor exhibits that the correlation diminishes significantly with proximity to stall and the proposed technique might have the capability of generating a stall warning signal sufficiently in advance of spike inception. Extensive experiments on a research compressor show that the degree of the index degradation depends on various factors such as flow coefficient, tip clearance and rotor blade incidence. In order to obtain a reliable stall warning signal in practical use, these effects must be carefully examined.Copyright © 2004 by ASME

Wind power generating device, control method for wind power generating device and computer program

Abstract: PROBLEM TO BE SOLVED: To provide technology enabling to detect a gust of wind beforehand and take countermeasure against a gust of wind such as angle change of a blade without requiring an observation tower. SOLUTION: In a wind power generating device provided with a tower erectly provided on the ground, a nacelle fixed on the tower, and a plurality of blades rotatably fixed on the nacelle via a hub, a Doppler anemometer capable of measuring wind speed in front of the same by sending and receiving sound wave or electromagnetic wave and a blade angle control means controlling angle change of the blade including feathering are provided on the nacelle or the hub, the blade angle control means changes angle of the blade when the Doppler anemometer detects wind speed of a predetermined value or greater. COPYRIGHT: (C)2006,JPO&NCIPI

Pitch control for blade in wind powered generator has a servo drive to vary the pitch and with a separate locking system to hold the basic pitch up to a set wind speed

Abstract: A pitch control for a blade in a wind powered generator has the blade shaft (6) mounted in the hub support (1) by a ring bearing (4, 5) and with a servo drive (7) to vary the pitch above a preset wind speed. The basic pitch is fixed by a separate locking system (8) which secures the pitch without play and without any stress on the servo drive.

Wind power generating system

Abstract: In a wind power generating system, a pair of axially spaced turbines are connected to an outer rotor and an inner rotor of a generator, respectively, and are provided with blades having equal but opposite pitch angles so that the inner and outer rotor rotate at a same rotational speed in opposite directions. Because the relative rotational speed between the inner and outer rotors is twice as great as the rotational speed of the inner rotor or outer rotor, the generator system can produce a relatively large electric power even when the wind speed is low. If desired, a pitch varying mechanism for the turbine blades may be done away with so as to reduce the manufacturing and maintenance costs.

Rotor blade for a wind power system

Abstract: The invention pertains to a rotor blade for a wind power system as well as a wind power system. The present invention is based on the objective of disclosing a rotor blade with a rotor blade profile and a corresponding wind power system that make it possible to improve the efficiency in comparison with arrangements known thus far. In the proposed rotor blade for a wind power system, the position of maximum thickness of the rotor blade lies approximately between 15% and 40%, preferably between 23% and 28%, and the maximum profile thickness lies approximately between 20% and 45%, preferably between 32% and 36%.

Influence of Hot Streak Circumferential Length-Scale in Transonic Turbine Stage

Abstract: A computational study is carried out on the influence of turbine inlet temperature distortion (hot streak). The hot streak effects are examined from both aeromechanical (forced blade vibration) and aero-thermal (heat transfer) points of view. Computations are firstly carried out for a transonic HP turbine stage, and the steady and unsteady surface pressure results are compared with the corresponding experimental data. Subsequent analysis is carried out for hot-streaks with variable circumferential wavelength, corresponding to different numbers of combustion burners. The results show that the circumferential wavelength of the temperature distortion can significantly change unsteady forcing as well as the heat-transfer to rotor blades. In particular, when the hot-streak wavelength is the same as the nozzle guide vane (NGV) blade pitch, there is a strong dependence of the preferential heating characteristics on the relative clocking position between hot-streak and NGV blade. However, this clocking dependence is shown to be qualitatively weakened for the cases with fewer hot streaks with longer circumferential wavelengths.Copyright © 2004 by ASME

Compressor rotor blade

Abstract: Compressor blade (1) comprises a blade foot (4), a platform (3), and a solid blade body (2) without an internal cooling system and provided with a blade tip (7), a front edge (5), a rear edge (6) and a pressure side and suction side. The blade body has on its blade tip a recess (8) that extends up to the rear edge. Preferred Features: The blade body has a step-shaped shoulder (9) on its blade tip.

Method for mounting rotor blades and rotor blade for a wind turbine

Abstract: The invention relates to a method for mounting rotor blades on a rotor hub, which is connected to a nacelle of a wind turbine. Said method comprises the following steps: rotation of the rotor hub into a predefined first position; mounting of a rotor blade (21); rotation of the rotor hub into a predefined second position with the aid of the mounted rotor blade (21) and mounting of a second rotor blade (22), whereby the rotor hub is rotated in the direction of the gravitational force of the first rotor blade (21) that has already been mounted. A crane, which is sufficient for mounting the rotor hub itself or the nacelle, can also be used to mount rotor blades on wind turbines with a relatively high hub. The invention also relates to a rotor blade that is to be mounted on a wind turbine, said rotor blade having at least one bore.

Blade pitch angle control device and wind turbine generator

Abstract: A blade pitch angle control device comprising a storage unit (10) for storing, mutually associated with each other, specified parameters affecting a variation in blade load, an azimuth angle, and a pitch angle instruction value, an azimuth angle detector (11) for detecting an azimuth angle for each blade, a parameter detector (12) for detecting specified parameters, an instruction value acquiring unit (13) for acquiring, for each blade, a blade-based azimuth angle detected by the azimuth angle detector (11) and a pitch angle instruction value selected by specified parameters detected by the parameter detector (12) respectively from the storage unit (10), and a pitch angle control instruction value generating unit (14) for generating a pitch angle control instruction value that is used to individually control a blade pitch angle based on a pitch angle instruction value and a common pitch angle instruction value.

Intelligent control for large-scale variable speed variable pitch wind turbines

Abstract: Large-scale wind turbine generator systems have strong nonlinear multivariable characteristics with many uncertain factors and disturbances. Automatic control is crucial for the efficiency and reliability of wind turbines. On the basis of simplified and proper model of variable speed variable pitch wind turbines, the effective wind speed is estimated using extended Kaiman filter. Intelligent control schemes proposed in the paper include two loops which operate in synchronism with each other. At below-rated wind speed, the inner loop adopts adaptive fuzzy control based on variable universe for generator torque regulation to realize maximum wind energy capture. At above-rated wind speed, a controller based on least square support vector machine is proposed to adjust pitch angle and keep rated output power. The simulation shows the effectiveness of the intelligent control.

Rotor blade of a wind energy facility

Abstract: The invention relates to a rotor blade of a wind energy facility and to a wind energy facility. The invention aims at providing a rotor blade with a blade profile or a wind energy facility, which has an improved efficiency. To achieve this, several solutions are possible: rotor blade of a wind energy facility, wherein the rotor blade has a position of maximum thickness of approximately 15 % to 40 %, preferably from approximately 23 % to 28 %; the biggest thickness of the profile is approximately 20 % to 45 %, preferably from about 32 % to 36 %; the rotor blade has a two part configuration in the root area; a part of a rotor blade is configured in the outer side of the hub lining; the ratio between the profile depth of a rotor blade and the diameter of the rotor is approximately from 0.04 to 0.1 and the ratio between the depth of the profile of a rotor blade and the diameter of the spinner is between 0.5 and 1.

Control method and control system for a controllable pitch marine propeller

Abstract: A control method and system for a controllable pitch marine propeller including operating modes comprised of a manoeuvering mode and a cruise mode and check modes comprised of an engine check mode and propeller check mode. The cruise mode provides for wide open throttle acceleration and power stop. Smooth transition sub-modes are provided for providing smooth transition between cruise mode and manoeuvering mode and vice versa. The system operates by a lever (28) which controls a pitch control unit (10) which in turn controls engine speed and also the pitch of propeller blades (12) of propeller (14). Thus, dependent on the position of the control lever (28) in either manoeuvering mode or cruise mode, an appropriate engine speed and propeller pitch is selected automatically for driving a watercraft.

Wind turbine generator with a low voltage ride-through controller and a method for controlling wind turbine components

Abstract: A wind turbine. The wind turbine includes a blade pitch control system to vary a pitch of one or more blades and a turbine controller coupled with the blade pitch control system. A first power source is coupled with the turbine controller and with the blade pitch control system to provide power during a first mode of operation. Uninterruptible power supplies coupled to the turbine controller and with the blade pitch control system to provide power during a second mode of operation. The turbine controller detects a transition from the first mode of operation to the second mode of operation and causes the blade pitch control system to vary the pitch of the one or more blades in response to the transition.

Design and Fabrication of a Collective and Cyclic Pitch Propeller

Abstract: Autonomous underwater vehicle propulsion has been primarily driven by conventional thruster arrangements and control fins. The development of a collective and cyclic pitch propeller system provides a highly maneuverable alternative to these conventional designs. Therefore, a computer controlled and fully actuated collective and cyclic pitch propeller was designed and fabricated to fulfill this need. -- The new propeller was designed using a helicopter like linkage system. The swash plates mounted inside of the propeller housing, as opposed to propeller hub like a helicopter. Locating the linkages in the housing provided a more maintainable system of linkages, due to space limitations in the propeller hub. The swash plate was positioned using three ball screw electric actuators using absolute positioning feedback. The swash plate position was transmitted to the propeller hub by a set of four control rods, one for each blade. Four blades were chosen for the propeller to reduce pulsing of the propeller when operating in cyclic mode. -- Initial testing of the prototype demonstrates the propeller's potential ability to control the underwater vehicle at little or no forward speed. While operating in the 50% ahead, 100% to port condition, a thrust value of 26.7 N (6 lbf) with a turning moment of 18.9 Nm (168 in-lb) was measured. The turning moment generated at a forward speed of 1 .6 m/s was sufficient to turn the C-SCOUT vehicle in 38% of the present required turning circle using a conventional thruster and control fins.

Pitch and torque control of variable speed wind turbines

Abstract: In this thesis the torque, speed and pitch angle control of variable speed wind turbine is investigated. In particular, it concentrates on the extraction of maximum available energy, reduction of torque and output power variations, which gives stresses in the gearbox and mechanical structure. The control concentrates on separate wind speed internals as well as on whole wind speed region. It is found that the control structures varies substantially between the wind speed regions. Finally the result are compared with measurement made on 2 variable speed turbines.

Horizontal shaft windmill and its standby method

Abstract: PROBLEM TO BE SOLVED: To provide a horizontal shaft windmill capable of reducing a design load acting on blades in a standby state in a storm. SOLUTION: This horizontal shaft windmill 1 comprises a rotor 5 having a hub 7 and at least two or more blades 6, a nacelle 3 for journaling the rotor 5 via a rotary shaft 4 connected to the hub 7, a tower 2 for supporting the nacelle 3, and an independent pitch control means capable of respectively and independently driving and controlling a pitch angle of the blades 6. The independent pitch control means controls the pitch angle so that the whole blades 6 become a full feather state in a wind speed not less than an operable wind speed value, and afterwards, controls so that the pitch angle of the respective blades 6 is successively reversed one by one, and further afterwards, controls so as to stand by in a whole blade reversal full feather state of reversing the pitch angle of the whole blades 6. COPYRIGHT: (C)2006,JPO&NCIPI

Pitch lock and lag positioner for a rotor blade folding system

Abstract: A rotor blade folding system includes a blade lock assembly, a rotary actuator and a blade fold controller to selectively position each rotor blade assembly in a particular predetermined folded position. The blade lock assembly positions each blade yoke in a predetermined lead/lag and pitch position to minimize strain upon an elastomeric bearing between the blade yoke and the rotor hub. The rotor blade is then folded relative to the blade yoke to a predetermined blade fold angle.