Blade pitch angle control for wind turbine

0001The invention relates to a wind turbine with a rotor having at least one Rotor blade for converting the flow energy of the wind into mechanical energy, with an adjustment for individual adjustment of at least one The rotor blade, with a generator for converting the mechanical energy of the The rotor into electrical energy and with an operative connection between the rotor and the generator for transmitting the mechanical energy of the rotor to the generator.

0002Such wind turbines are part of the prior art. For example, shows the German reference book "Wind Turbines" by Erich Hau, Springer-Verlag, 2nd ed., 1996, pages 52, 175, 222-242, 269, 320 such wind turbines. at These known wind turbines can be adjusted using a Rotorblatteinstellwinkelregelung the rotor speed and regulate the power output. Furthermore is known Rotorblatteinstellwinkelregelung protection against overspeed the rotor at high wind speeds or during a power failure, in which the generator torque due to unexpected loss. In both cases, it comes, the wind power plant To protect against destruction by too high rotating rotor.

0003There are essentially two ways of using the blade adjustment, a reduction bring the rotor speed: on the one hand allows the blade pitch reduce in the direction of smaller aerodynamic angle, thus the to reduce power consumption of the rotor. On the other hand, it is possible to carry the Adjustment of Rotorblatteinstellwinkels larger adjustment angles the critical aerodynamic angle of attack to achieve the so-called stable state. The latter option has the advantage of a shorter adjustment path brings However, the disadvantage that the flow separation (stall) with high loads is connected to the rotor and the entire wind power plant. Both However, settings in common is that they only have an average, the entire wind turbine acting wind speed or a certain consider limiting the rotor speed as a start signal for the blade angle setting.

0004Both of the aforementioned possibilities of the prior art do not take account, that, particularly in a large rotor diameter uneven to Distribution of wind conditions can occur on the rotor surface. This in turn different loads on individual blades and asymmetric Loads for the drive train of the wind turbine, that is the hub, the drive shaft and the respective bearings. Such different asymmetric Loads occur not only until a certain rotor speed or a certain wind speed, but also constantly find during normal operation of the wind turbine instead. The date of the Prior art blade angle regulation can not therefore on wind speed variations and related load variations in the rotor area react as in the known systems a uniform, synchronous adjustment of Rotor blades takes place.

0005With newer systems (see in particular S. 238 of the above reference book) While on the one hand an individual electrical adjustment of each rotor blade been proposed; but also finds this proposal under the Assuming a mean wind speed rather than that of the wind turbine acts. This and the further assumption that the wind speed with the Height increases, a fixed, circumferential cyclical correction is Rotorblatteinstellwinkels proposed to the changing loads on the increase in wind speed to compensate at least partly with the height. Also, in this Rotorblatteinstelltechnik it is disadvantageous that the pitch of the rotor blades fixed is predetermined and therefore not on local and temporary adjustments to the may wind speed in a portion of the rotor react. Also, in this therefore proposal takes place at about the rotor face seen in local peaks wind speed asymmetric and thus lebensdauerverkürzende load the components instead of the wind turbine.

0006The object of the invention is therefore to avoid the above problems and to provide a wind turbine available in reducing the burden are the result of local and temporary peaks in the Winds may occur in parts of the rotor surface.

0007This object is inventively achieved in that, for a wind power plant of the type mentioned measuring means are provided, which the instantaneous stress a portion of the wind turbine determine, control means are provided are, the at least one desired for the instantaneous loading position determine a rotor blade and the rotor blade using the adjusting device Adjust accordingly and connecting means are provided, the Adjusting and measuring means to the control means connect.

0008Through the wind power plant according to the invention makes it possible, using the Adjusting device for individual adjustment of at least one rotor blade, the Wind turbine on current, locally only on a part of the wind turbine applied stresses, determined by measuring means, by means of the control means vote. Thus, it is advantageously achieved that local peaks in the Load of the rotor blades, the hub, final drive and the bearings used be avoided. This in turn has the consequence that the service life of the wind turbine is increased or not unconsciously shortened because asymmetric and the life shortening loads of parts of the wind turbine are largely avoided.

0009Moreover, it allows the wind turbine according to the invention, the instantaneous optimal use of distribution of wind speeds on the rotor surface and, therefore, contribute to an increased power output of the wind power plant, since all blades always with the desired and thus optimum blade angle be driven and therefore the efficiency of each rotor blade towards the efficiency the wind turbines of the prior art increases.

0010It is particularly preferred that the position of the rotor blade or the rotor blades adapted continuously to the current demands of the wind turbine becomes. In this way it can be ensured that the wind turbine is moved continuously within the optimal range, while front load peaks, triggered by locally available in the rotor field peaks in the Wind speed, is protected.

0011In a preferred embodiment of the invention, the measuring means determines the Determination of local stress of a rotor blade a prevailing on the rotor blade Wind speed. To this end, the measuring means preferably comprise a mounted on the rotor blade anemometer on. Characterized in that the anemometer is arranged directly on the rotor blade, is a very precise control of the Angular position of the rotor blade in response to an increased or lower Wind speed possible. Because directly by measuring the wind speed at the location at which there is also an adjustment of the wind power plant, namely directly on to be adjusted rotor blade, is a fast and accurate adjustment the rotor blade angle position to local changes in wind speed possible.

0012A further preferred embodiment is characterized in that the measuring means a predominant part in a portion of the rotor frame mechanical Last determine. In this embodiment, by the direct determination of the in a partial section of the rotor applied mechanical stress to the control means given accurate information, enabling them taking into account the predetermined geometry, load and / or material data a desired position to determine at least one adjustable rotor blade.

0013Particularly advantageous in this embodiment, it is when the measuring means in a the adjustable rotor blade determine prevailing mechanical load. for by the load is determined directly in the rotor blade, can similarly to the above called direct determination of the wind speed at the rotor blade, a very precise Information about the wind speed profile over the rotor surface are obtained. With such accurate information, the control means are then in a position to a to control particularly precise reaction of the adjusting device, so that an existing Peak load are rapidly degraded in a partial section of the rotor can.

0014Another embodiment of the invention having a rotor hub for receiving the Rotor blades includes measuring means that an existing in the rotor hub mechanical measure load. Also in this embodiment allows a fast adaptation make the rotor blades to the changed load situation. The same applies to Embodiments with an axle journal for supporting the rotor, in which the Measuring means determine a prevailing in the journal load and at a Wind power installation having a drive shaft, the rotor and the generator directly or connects via a transmission, wherein the measuring means in a prevailing drive shaft or in the bearings of the drive shaft or the journal Last determine. All of the above embodiments allow accurate Determination of local load conditions in the rotor area and thus an accurate Control of the adjustment means of the control means. It is particularly preferred that the measuring means for measuring the mechanical load stretch marks have, at the respective loaded parts of the wind turbine are attached. That is, the stretch marks on the rotor blade, in the interior of the rotor blade on the rotor hub or within the rotor hub, on which Journals or in the interior of the journal, on the drive shaft or in the interior the drive shaft or be attached to the camps. In all the aforementioned Mounting variants is a simple determination of the existing mechanical Load, and thus the inventive individual adjustment of the rotor blade possible.

0015A further preferred embodiment of the invention comprises measuring means having a at the prevailing to be adjusted rotor blade angle of attack of the wind determine. It is thus advantageously possible to the wind direction of the oncoming Wind relative to determine the to be adjusted rotor blade. Using this Measured value, the control means on a in a portion of the rotor existing Wind Shift react.

0016In particular, in conjunction with the load measuring means mentioned above to receive the Control means a very accurate picture of the current wind conditions on the Rotor area: by the load measuring means, the control means can an absolutely known Load and considered by the measuring means for determining the angle of incidence can moreover also - taking into account the actual position of the rotor blade - Accurate determination of the size of the angle to be adjusted be made. An accurate adjustment in rapidly changing wind conditions is thus defined by the combined use of Anströmwinkelmessung and load measurement in the rotor blades ensures advantageous. It is particularly preferred Inappropriate measuring the angle of attack by the rotor blade make wind vane.

0017A further preferred embodiment of the invention is characterized, that part of a rotor blade section asynchronously to at least one other adjustable Part of another rotor blade adjustable i st. Thus can be reduce, especially for large rotor diameters, the construction cost by preferably, the outer section of the rotor blade, as the power generation the rotor largely focused on the outer wing portion, adjustable is performed.

0018In an advantageous embodiment of the invention can be destined for a instantaneous stress desired position of the rotor blades or pretend through related to the control means input means. In this way Example, the wind power plant according to the invention on site after installation to possibly unforeseen wind conditions or after repair works to modified material thicknesses or be adapted to changing airfoils.

0019Especially advantageous has proven to be the actual value of the rotor blade angle position tap off of an adjusting gear, which together with a variable displacement the adjustment forms. It is particularly advantageous if the Control means the adjustment of the rotor blade substantially simultaneously with the detection of the measured values ​​of the stretch marks, the anemometer or wind vane by comparison with the actual value of the adjusting means of the adjustment make. Such an instantaneous response to load changes Area of ​​the rotor blades is an effective reduction of harmful pollution or weight on one side of the rotor ensures.

0020An advantageous method for adapting a wind energy plant only in a local section of the wind turbine prevailing momentary stresses distinguished by the fact that the means of measuring actual load a part of the wind power installation is detected and a control means for instantaneous stress desired position of at least one of the rotor blades is determined, and that according to the rotor blade by means of the adjusting device is adjusted accordingly, the adjustment and the measuring equipment with the Control means are connected by means of connecting means. This simple The method can be an effective increase of lifetime and efficiency of achieve wind power plant according to the invention.

0021Further advantageous embodiments are described in the subclaims.

0022An embodiment of the invention will be with reference to the accompanying described drawings, in which:<sl><li>Figure 1 is a partial section through a wind power plant according to the invention;</li><li>Figure 2 is a front view of a wind power plant according to the invention; and</li><li>3 shows a block diagram with the control of the adjustable rotor blade represents a preferred embodiment of the invention.</li></sl>

00231 shows a wind turbine 1 in a partial section. The wind power plant 1 rests on a (only partially shown) tower 2. At the upper end the tower 2 is 4 placed on the tower a housing. Below the housing 4 is a attached to the tower maintenance platform 6. The housing 4 has, in its (In the drawing enclosed, right shown) back of a (not shown) generator and a dashed line shown control unit 8. Of the Generator is located behind a bulge 10 of the housing 4 and is connected via connecting elements 12 with his (not shown) rotor on the rotor hub 14 flanged. The rotor hub 14 and the (only partially shown) rotor blades 16 together form the rotor 18. The rotor 18 with its hub 14 via bearings 20 mounted on an axle journal 22nd The journal 22 extends through an in Rotor hub 14 provided opening 24 by the rotor hub 14 therethrough. Of the Journal 22 is tower mutually connected within the housing 4 with the tower. 2 From the substantially vertically drawn up Tower 2 of the axle journal 22 projects relative to the horizontal upwards slightly tilted from. The journal 22 is connected the (not shown) of the generator stator is connected and extends through the rotor of the generator and according to the rotor hub 24 through the opening 14 therethrough and is it emerges from the opening 24 on the side remote from the tower side of the 2 Rotor 18 by an end cap 26 completed.

0024Again, perpendicular to the axis of the journal 22 extending the rotor blades 16 outwards. The rotor blades 16 pass through openings 28 in the front housing 30 therethrough. The front housing 30 is movable relative to the fixed to the Tower 2 connected housing 4 and fixed to the hub 14th

0025The rotor blades 16 are rotatable via a flange to the rotor hub 14 connected around its longitudinal axis. A servomotor 34 is attached to the flange 32 mounted and adjusted via an adjusting gear 36, the rotor blade 16. The Adjusting motor 34 and the adjusting gear 36 are (as shown in FIG. 3) via electrical Connections 50 and 46 connected to the control device eighth The front housing 30 encloses the rotor hub 14 with the bearings 20, the flange 32, the servomotor 34 and the adjusting mechanism 36 weathertight. The front housing 30 has a cross-sectionally substantially semi-spherical shape.

0026to stretch marks are located on the axle journal 22 is 38. At the rotor hub 14 to stretch marks 40. The stretch marks 38 are connected via an electrical Connection 42 is connected to the control unit eighth The stretch marks 40 are (Shown in FIG. 3), an electrical connection 48 to the control device 8 connected.

00272 shows parts of the wind turbine 1 of 1 from the rotor side seen. Figure 2 shows the tower 2 with the rotor hub attached to its tip 14. From the rotor hub 14 in a star-shaped rotor blades of three 16th The rotor blades 16 are connected via the flange 32 to the rotor hub fourteenth to Clarity of illustration are the front housing 30, the adjusting motor 34, the Variator 36, the journal 22, the opening 24 and the end cap 26 not shown in FIG. 1.

0028At the rotor blades 16 are wind vanes 44 for measuring the angle of incidence of the mounted on the rotor blades 16 impinging wind. The wind vanes 44 are (In Figure 3 shown) electrical connection 52 to the control unit 8 (Fig. 1) connected.

0029On the basis of the block diagram of Figure 3 will in the following the operation of the Wind power installation according to the invention described.

0030During operation of the wind turbine 1, the rotor 18 rotates about the axis of the axle journal 22. In this case, the rotor blades 16 in a specific, with the aid of Control unit 8, the adjusting motor 34 and the variable speed 36 preset Angle position relative to the plane in which to rotate the rotor blades 16, the rotor plane on. The instantaneous angle α_currently of the rotor blades 16 relative to the rotor plane the control unit 8 of the adjusting mechanism 16 as the actual value of the current position of the rotor blade 16 transmitted via an electrical connection 46th simultaneously is replaced by the control unit 8 of the strain gauges 38 on the journal 22 are fixed, readings about the current load on the axle journal 22 on line 42 ( "load signal journal" of Figure 3). Also simultaneously with the Transmission of the instantaneous position angle of the rotor blades 16 is replaced by the control unit 8 of the stretch marks 40 on the rotor hub via line 48 readings on the current load on the rotor hub 14 ( "load signal hub" of Figure 3). provides the control unit 8 by means of the elongation strips 38, 40 a one-sided load of the Rotor set, so outputs the control device 8 taking account of the instantaneous Setting angle α_currently the rotor blades 36 and the current, from the wind vane 44 determined angle of attack β a signal α_new via line 50 to the servomotor 34 α for adjusting the corresponding blade 16 by the difference_new - α_currently,

0031Characterized that the control unit 8 continuously measuring the values ​​of the stretch marks 38 and 40 receives and almost instantaneously considering the also constantly via line 52 transmitted to the control unit 8 inflow angle β the operation command the adjustment motor 34 for setting a new angle of the rotor blades 16 out there, found on-line with a change in the load conditions in the region of Rotor to adapt the position of the rotor blades 16 instead and thus an online compensation unbalanced loads of the rotor 18th

0032As an alternative to the measurement of the instantaneous load on the wind turbine by stretch marks on the rotor hub and axle pin is also a load measurement possible directly on the rotor blades by corresponding stretch marks.

0033Finally, it should be noted that the various signals (ie "load signal Hub "40," Last Signal journals "38," Current angle α_currently"46 and "Angle of attack β" 53) used to determine the ideal blade angle be, either can be used together or alternatively.