METHOD FOR OPERATING A WIND POWER INSTALLATION

Abstract

The present invention relates to a method for operating a wind power installation, comprising the steps of: sensing at least one angular velocity of the wind power installation, in particular by use of a rotation rate sensor in a hub of the wind power installation, preferably for the purpose of sensing a tilt of the nacelle; sensing a reference value for the at least one sensed angular velocity; determining at least one state variable of the wind power installation from the at least one angular velocity and the reference value; controlling the wind power installation in dependence on the state variable, in particular such that the state variable becomes smaller.

Claims

1. A method for operating a wind power installation, the method comprising: sensing an angular velocity of the wind power installation; sensing a reference value for the angular velocity; determining a state variable of the wind power installation based on the angular velocity and the reference value; and controlling the wind power installation in dependence on the state variable.

2. The method as claimed in claim 1, wherein the sensing the angular velocity of the wind power installation comprises using a rotation rate sensor in a hub of the wind power installation, wherein the rotation rate sensor is configured to sense a tilt of the nacelle.

3. The method as claimed in claim 1, wherein the controlling causes the state variable to become smaller.

4. The method as claimed in claim 1, wherein the angular velocity is sensed in one direction, the one direction being along an axis of rotation of a rotor of the wind power installation.

5. The method as claimed in claim 1, wherein the axis of rotation is a main axis of rotation.

6. The method as claimed in claim 1, wherein the reference value is a relative rotational speed about an axis of rotation of a rotor of a wind power installation and is sensed by a magnetic tape sensor.

7. The method as claimed in claim 1, wherein the state variable is indicative of a tilt speed of the nacelle of the wind power installation.

8. The method as claimed in claim 1, wherein determining the state variable includes a difference of the angular velocity and the reference value.

9. The method as claimed in claim 8, wherein the state variable is further based on a tilt angle of the axis of rotation of the rotor relative to a horizontal plane.

10. The method as claimed in claim 1, comprising filtering the angular velocity and the reference value before the determining the state variable.

11. The method as claimed in claim 10, wherein the filtering comprises using a bandpass filter to obtain a second tower eigenmode.

12. The method as claimed in claim 1, wherein the controlling of the wind power installation is effected with observation of the state variable.

13. The method as claimed at least in claim 1, further comprising filtering the state variable for controlling the wind power installation.

14. The method as claimed at least in claim 1, wherein the filtering comprises using a low-pass filter.

15. A wind power installation, comprising: a first sensor configured to sense angular velocity of the wind power installation; a second sensor configured to sense a reference value for the angular velocity; and a controller configured to: receive signals indicative of the angular velocity and the reference value; determine a state variable of the wind power installation based on the angular velocity and the reference value; and control the wind power installation in dependence on the state variable.

16. The wind power installation as claimed in claim 15, wherein the first sensor is a rotation rate sensor and the second sensor is a magnetic tape sensor.

17. A method comprising: sensing a second eigenmode of a tower of a wind power installation, the wind power installation including a nacelle on the tower, the sensing comprising: sensing a rate of rotation of the wind power installation; determining a tilt speed of the nacelle from the sensed rate of rotation; filtering the tilt speed of the nacelle to determine the second eigenmode of the tower of the wind power installation; and controlling the wind power installation in dependence on the second eigenmode of the tower of the wind power installation.

18. The method as claimed in claim 17, further comprising: sensing a relative angular velocity between the nacelle and the hub.

19. The method as claimed in claim 17, wherein controlling the wind power installation in dependence on the second eigenmode of the tower of the wind power installation comprises controlling the wind power installation such that the frequency of the second eigenmode decreases.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0081] The present invention is explained in more detail below and with reference to the accompanying figures, with the same references being used for components or assemblies that are the same or similar.

[0082] FIG. 1A shows in schematic form, by way of example, a perspective view of a wind power installation in one embodiment.

[0083] FIG. 1B shows in schematic form, by way of example, the axes of a wind power installation.

[0084] FIG. 2 shows in schematic form, by way of example, a Campbell diagram for a tower of a wind power installation.

[0085] FIG. 3A shows in schematic form, by way of example, an oscillation of a wind power installation, in particular a pitching of a nacelle.

[0086] FIG. 3B shows in schematic form, by way of example, an oscillation of a wind power installation, in particular a rolling of a nacelle.

[0087] FIG. 4A shows in schematic form, by way of example, a method for operating a wind power installation according to one embodiment, in particular for a pitching of a nacelle.

[0088] FIG. 4B shows in schematic form, by way of example, a method for operating a wind power installation according to one embodiment, in particular for a rolling of a nacelle.

[0089] FIG. 5 shows in schematic form, by way of example, a possibility for determining a tilt speed for a second tower eigenmode.

DETAILED DESCRIPTION

[0090] FIG. 1A shows a perspective view of a wind power installation 100.

[0091] The wind power installation 100 is embodied as a horizontal rotor and comprises a tower 102 and a nacelle 104.

[0092] Located on a hub 110 on the nacelle 104 there is an aerodynamic rotor 106 that has three rotor blades 108.

[0093] When in operation, the aerodynamic rotor 106 is caused by the wind to execute a rotatory motion about an axis of rotation mounted substantially horizontally on the tower, and thereby drives a generator in the nacelle.

[0094] The generator thereby produces a current to be fed in, which is fed into an electrical supply grid by means of a converter arrangement.

[0095] There is also a rotation rate sensor 120 located in the rotor 106, in particular in the hub 110, and preferably to execute a method described above or below.

[0096] FIG. 1B shows in schematic form, by way of example, the axes of a wind power installation 100.

[0097] The wind power installation 100 comprises a tower 102, a nacelle 104, a rotor 106 and rotor blades 108.

[0098] The orientation of the tower 102 can be described by means of the axes x.sub.TOW, y.sub.TOW, z.sub.TOW. The orientation of the nacelle 104 can be described by means of the axes x.sub.NAC, y.sub.NAC, z.sub.NAC. The nacelle 104 is also preferably arranged perpendicularly to the tower 102. In particular, this results in the axes x.sub.TOW, y.sub.TOW, z.sub.TOW of the tower 102 and the axes x.sub.NAC, y.sub.NAC, z.sub.NAC of the nacelle being parallel to each other.

[0099] The aerodynamic rotor 106 is further arranged such that it is tilted at an angle Θ, the so-called tilt angle, on the nacelle 104 and in particular tilted about an axis, in particular y.sub.Nac.

[0100] The aerodynamic rotor 106 can be described by means of the axes x.sub.ROT, y.sub.ROT, z.sub.ROT.

[0101] If the rotation rate sensor, in particular the gyroscope, is located in the hub, i.e., within the aerodynamic rotor 106, the axes x.sub.GYRO, y.sub.GYRO, z.sub.GYRO of the rotation rate sensor and of the aerodynamic rotor 106 coincide.

[0102] Since the rotor 106 is arranged such that it is tilted on the nacelle, the rotation rate sensor is also tilted relative to the nacelle and thus also arranged such that it is tilted relative to the main axis of rotation x.sub.NAC of the wind power installation, in particular by the angle Θ.

[0103] In addition, the rotor 106 is rotated by an angle γ, preferably a time-varying angle γ(t), along an axis x.sub.Nac,tilt with respect to the nacelle.

[0104] FIG. 2 shows in schematic form, by way of example, a Campbell diagram 200 for a tower of a wind power installation.

[0105] The Campbell diagram 200 is realized as a Cartesian coordinate system, with the rotational speed of the rotor of the wind power installation being plotted on the abscissa 210, in revolutions per minute, and the eigenfrequency of the wind power installation, in particular of the tower, being plotted on the ordinate 220, in Hertz.

[0106] Wind power installations are usually constructed and designed for a particular operating range AB, for example for a particular nominal rotational speed n.sub.nenn. The nominal rotational speed n.sub.nenn is, for example, 12 revolutions per minute. In order to attain the operating range AB, it is necessary, for example, for the wind power installation to be started up or deactivated.

[0107] In addition, the tower of the wind power installation has at least one first eigenfrequency f.sub.R1.

[0108] In the case of a stiff-stiff tower, the first eigenfrequency f.sub.R1, i.e., the lowest resonance frequency, of the tower in the operating range AB is above three times the nominal rotational speed (3p).

[0109] In the case of a soft-stiff tower, the first eigenfrequency f.sub.R1, i.e., the lowest resonance frequency, of the tower in the operating range AB is below three times the nominal rotational speed (3p) and above one times the nominal rotational speed (1p).

[0110] In the case of a soft-soft tower, the first eigenfrequency f.sub.R1, i.e., the lowest resonance frequency, of the tower in the operating range is below one times the nominal rotational speed (1p).

[0111] The method described herein is preferably used for wind power installations that have a soft-soft tower.

[0112] FIG. 3A shows in schematic form, by way of example, an oscillation 300 of a wind power installation as shown in FIGS. 1A and 1B.

[0113] The oscillation 300 is composed substantially of an oscillating deflection of the tower 310 in the x-direction, i.e., along the main axis of the wind power installation, and an associated forward-backward motion 320 of the nacelle along the main axis of rotation, or about the y-axis, the so-called pitching of the nacelle.

[0114] The cause of this oscillation 300 is the second tower eigenmode.

[0115] FIG. 3B shows in schematic form, by way of example, an oscillation 300 of a wind power installation as shown in FIGS. 1A and 1B.

[0116] The oscillation 300 is composed substantially of an oscillating deflection 312 of the tower 100 in the y-direction, i.e., about the main axis of the wind power installation 100, and an associated sideways motion 322 of the nacelle about the main axis of rotation, or along the y-axis, the so-called rolling of the nacelle.

[0117] The cause of this oscillation 300 is the second tower eigenmode of the tower 102 of the wind power installation 100.

[0118] In order to sense this oscillation 300, there is at least one magnetic tape sensor 130 located on the main axis, for example on the shaft of the rotor, and a reader head 132 for the magnetic sensor tape 130 located in the nacelle 104.

[0119] FIG. 4A shows in schematic form, by way of example, a method 400 for operating a wind power installation according to one embodiment, in particular for a pitching of a nacelle.

[0120] In a first step 410, the angular velocities ω.sub.GYRO,x, ω.sub.GYRO,y, ω.sub.GYRO,z of the wind power installation 100 are sensed, in particular the angular velocities ω.sub.GYRO,x, ω.sub.GYRO,y, ω.sub.GYRO,z of the nacelle, for example by means of a rotation rate sensor in the hub of the wind power installation.

[0121] Preferably, in a next step 420, the angular velocities ω.sub.GYRO,x, ω.sub.GYRO,y, ω.sub.GYRO,z sensed in this way are filtered, in particular for frequencies caused by the second tower eigenmodes. The filtering is preferably effected by means of a bandpass filter.

[0122] In addition, in a further step 430, a reference value γ for the angular velocities ω.sub.GYRO,x, ω.sub.GYRO,y, ω.sub.GYRO,z is sensed, in particular the rotor position in the form of a relative angle of rotation, in particular of the hub relative to the nacelle.

[0123] In a further step 450, a state variable is determined, for example the tilt speed ω.sub.Nac.y of the nacelle about the y-axis is determined, the so-called pitching.

[0124] Preferably, the state variable is also filtered in a further step 460, for example by means of a low-pass filter.

[0125] Finally, in a further step 480, the wind power installation is controlled in dependence on the state variable, for example by means of control signals F.

[0126] FIG. 4B shows in schematic form, by way of example, a method 400 for operating a wind power installation according to one embodiment, in particular for a pitching of a nacelle.

[0127] In a first step 410, the angular velocities ω.sub.GYRO,x of the wind power installation 100 are sensed, in particular the angular velocities ω.sub.GYRO,x of the nacelle about the main axis (x), for example by means of a rotation rate sensor in the hub of the wind power installation.

[0128] Preferably, in a next step 420 the angular velocity ω.sub.GYRO,x sensed in this way is filtered, in particular for frequencies caused by the second tower eigenmodes. The filtering is preferably effected by means of a bandpass filter.

[0129] In addition, in a further step 430, a reference value ω.sub.REF for the angular velocities ω.sub.GYRO,x is sensed, in particular the relative rotational speed of the rotor of the wind power installation, for example by means of a magnetic tape sensor 130.

[0130] Preferably, in a next step 440, the reference value ω.sub.REF sensed in this way is likewise filtered by means of a bandpass filter.

[0131] In a further step 450, a state variable is determined, for example the tilt speed ω.sub.Nac.x of the nacelle about the x-axis, the so-called rolling. For this it may be necessary, for example, to take into consideration a tilt angle Θ described above or below, for example because the rotation rate sensor is tilted by this angle Θ relative to the main axis of rotation.

[0132] Finally, in a further step 460, the wind power installation is controlled in dependence on the state variable, for example by means of control signals F.

[0133] FIG. 5 shows in schematic form, by way of example, a possibility for determining a tilt speed for a second tower eigenmode, in particular by means of a model of a wind power installation 500, preferably of low order.

[0134] The wind power installation 100, for example as shown in FIG. 1A or 1B, is linearized for this purpose. This is effected below using the example of a pitching of the wind power installation, for example as shown in FIG. 3.

[0135] The tilt α of the nacelle with respect to the normal state is as follows

[00003]$\sin \alpha =\frac{x_{\mathrm{Midtower}}}{l_{2\mathrm{TEF},\mathrm{eff}}},$

wherein
x.sub.Midtower is the deflection of the tower in the middle of the tower, and l.sub.2TEF,eff is the effective length of the tower for the second tower eigenmode.

[0136] Using the equation of motion:

[00004]${\omega }_{\mathrm{Nac},\max }=\frac{d\alpha }{\mathrm{dt}}$

this gives:

[00005]${\omega }_{\mathrm{Nac},\max }=2\pi f_{2\mathrm{TEF}}\frac{{\hat{x}}_{\mathrm{Midtower}}}{l_{2\mathrm{TEF},\mathrm{eff}}},$

wherein
{circumflex over (x)}.sub.Midtower describes the maximum deflection of the tower, and f.sub.2TEF describes the frequency of the second tower eigenmode.

[0137] The corresponding linearization 500′ is depicted alongside only wind power installation 100.

LIST OF REFERENCES

[0138] 100 wind power installation [0139] 102 tower, in particular of the wind power installation [0140] 104 nacelle, in particular of the wind power installation [0141] 106 aerodynamic rotor, in particular of the wind power installation [0142] 108 rotor blade, in particular of the wind power installation [0143] 110 spinner, in particular of the wind power installation [0144] 120 rotation rate sensor, in particular of the wind power installation [0145] 130 magnetic sensor tape [0146] 132 reader head, in particular for the magnetic sensor tape [0147] 200 Campbell diagram [0148] 300 oscillating of a wind power installation, in particular pitching of the nacelle [0149] 310 oscillating deflection of the tower [0150] 312 oscillating deflection of the tower [0151] 320 forward-backward motion of the nacelle [0152] 322 sideways motion of the nacelle [0153] 400 method for operating a wind power installation [0154] 410, 420, . . . method steps [0155] AB (rotational speed) operating range, in particular of the wind power installation [0156] F control signal [0157] n rotational speed, in particular of the rotor of the wind power installation [0158] n.sub.nenn nominal rotational speed, in particular of the rotor of the wind power installation [0159] 1p one times nominal rotational speed, in particular of the rotor of the wind power installation [0160] 2p two times nominal rotational speed, in particular of the rotor of the wind power installation [0161] 3p three times nominal rotational speed, in particular of the rotor of the wind power installation [0162] X.sub.HUB x-axis of the hub [0163] x.sub.NAC x-axis of the nacelle [0164] x.sub.TOW x-axis of the tower [0165] y.sub.HUB y-axis of the hub [0166] y.sub.NAC y-axis of the nacelle [0167] y.sub.TOW y-axis of the tower [0168] z.sub.HUB z-axis of the hub [0169] z.sub.NAC z-axis of the nacelle [0170] z.sub.TOW z-axis of the tower [0171] ω.sub.GYRO,x angular velocity of the rotation rate sensor, in particular about the x-axis [0172] ω.sub.GYRO,y angular velocity of the rotation rate sensor, in particular about the y-axis [0173] ω.sub.GYRO,z angular velocity of the rotation rate sensor, in particular about the z-axis [0174] ω.sub.REF reference value, in particular rotational speed of the rotor [0175] α tilt of the nacelle [0176] x.sub.Midtower deflection of the tower, in particular in the middle of the tower [0177] l.sub.2TEF,eff: the effective length of the tower, in particular for the second tower eigenmode [0178] γ reference value, in particular rotor position [0179] Θ tilt angle

[0180] The various embodiments described above can be combined to provide further embodiments. These and other changes can be made to the embodiments in light of the above-detailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled. Accordingly, the claims are not limited by the disclosure.