DE102011116551A1 - Method for measuring deformation of rotor blade of wind-power plant, involves determining frequency range of mechanical natural oscillation of position detection device, and determining deformation of blade based on frequency range - Google Patents

Abstract

The method involves detecting a starting position (6) of a positioning mark (17) at a rotor blade with a position detection device (16), and detecting operating position (7) of the mark at the rotor blade by the detection device. A frequency range of a mechanical natural oscillation of the detection device is determined or detected by a vibration sensor or by rotation rate sensor and used during the determination of deformation of the rotor blade. The frequency rage of the oscillation is determined in a learning phase and/or during operating phase of a wind power plant. Independent claims are also included for the following: (1) a device for measuring deformation of a rotor blade (2) a wind power plant.

Description

The present invention relates to a method for measuring the deformation of a rotor blade according to the preamble of claim 1, a device for measuring the deformation of a rotor blade according to the preamble of claim 10 and a wind turbine according to the preamble of claim 13.

Wind turbines are used to convert wind energy into electrical energy. For this purpose, they have a rotor with a plurality of rotor blades which are fastened to a hub of the rotor. Such rotor blades are subject to high loads due to the wind force acting on them and, to a lesser extent, also the centripetal acceleration acting on them. The rotor blades are generally made of fiber-reinforced plastics and are strongly deformed at high wind speeds. As a result, the mechanical material structure of the rotor blade can be damaged. Furthermore, a bent rotor blade can also hit a tower of the wind turbine, so that the rotor blade breaks or even the whole system is destroyed.

It is therefore known to monitor the deformation, in particular the bending, of the rotor blade in order to be able to reduce the load at too high loads by adjusting the angle of attack of the rotor blade. At high wind speeds, the wind turbine must be switched off. Furthermore, the deformation is also detected as a function of time, so that thereby a mechanical natural vibration of the rotor blade is detected. Such natural oscillations of the rotor blade have a certain characteristic frequency. Mechanical damage to the rotor blade or ice deposits on the outside of the rotor blade lead to a change in the mechanical vibration of the rotor blade, d. H. the frequency range of the mechanical natural vibration of the rotor blade. For this reason, mechanical damage to the rotor blade and ice deposits on the rotor blade can be detected by monitoring the mechanical self-oscillation of the rotor blade. In the case of mechanical damage or ice deposits on the rotor blade, it is generally necessary to switch off the wind turbine for safety reasons or to avert damage.

The DE 10 2006 002 708 B4 shows a device for measuring the deformation of a rotor blade. In this case, in the vicinity of the hub of the rotor blade, a transmitting / receiving unit, consisting of a collimated light source, a laser diode, and a spatially resolving imaging sensor attached. Distanced from the transceiver unit is a retroreflector as a position marker. The retroreflector reflects the light emitted by the transmitter onto the spatially resolving sensor. The transmitter / receiver unit thus represents a position detection device and based on the position of the light spot on the spatially resolving sensor, the deformation of the rotor blade can be determined.

The DE 10 2009 007 938 A1 shows a device for measuring deformations of an elastically deformable object, in particular a rotor blade of a wind turbine. An electronic camera as a position detection device optically detects a marker as a position marker. The electronic camera has an object and a matrix sensor, wherein the lens of the camera is directed to the at least one optically detectable marker, such that the marker is imaged on the matrix sensor. In an image processing apparatus, the image data is processed.

The position detection device, for example the transceiver unit or the electronic camera and the matrix sensor, are generally fastened in the region of the proximal end of the rotor, eg. B. at a so-called bulkhead. The rotor blade is formed predominantly in the form of a sheet structure and has only in the region of the attachment to the hub on a cylindrical cross-sectional shape. This cylindrical portion of the rotor blade is attached to a cylindrical flange of the hub, z. B. screwed. The bulkhead on the rotor blade is intended to prevent larger amounts of water or surrounding parts from penetrating the hub of the rotor causing mechanical damage to the hub.

The measurement of the deformation of the rotor blade is based on detecting an angle change between the position detection device on the bulkhead and the position marking at a sufficient distance from the position detection device within the rotor blade. Due to the forces to be transmitted to the hub by the rotor blade, aerodynamic excitation or transmission of vibrations from the system, mechanical vibrations of the bulkhead occur in a frequency range significantly greater than the rotational frequency. Exemplary here are, for example, natural oscillations of membranes or plates. Such natural vibrations of the bulkhead also lead to natural oscillations of the position detection device, thereby falsifying the measurement results for the operating positions of the position marking, because only an angle change with respect to the position marking is measured. As a result, measurement errors occur that falsify the accuracy of detecting the operating positions of the position marks on the rotor blade. The Position detection device is attached to the bulkhead (also called platform), so that thereby mechanical vibrations of the bulkhead lead to substantially the same mechanical oscillations of the position detection device.

The object of the present invention is therefore to provide a method for measuring the deformation of a rotor blade, a device for measuring the deformation of a rotor blade and a wind turbine, in which the deformation of the rotor blade can be measured with high accuracy.

This object is achieved with a method for measuring the deformation of a rotor blade, in particular a rotor blade of a wind turbine, comprising the steps of: detecting an output position of at least one position marker on the rotor blade with a position detection device; Detecting at least one operating position, preferably a plurality of operating positions, the at least one position mark on the rotor blade with the position detecting means; Determining the deformation of the rotor blade by means of the difference between the output position and the at least one operating position of the at least one position marker, wherein at least one frequency range of a mechanical natural vibration of the position detection device is determined or detected and taken into account in the determination of the deformation of the rotor blade.

Measuring errors of the position detection devices due to a mechanical natural vibration of the position detection device can thereby be substantially reduced, because the mechanical oscillations of the position detection device are taken into account. Thereby, the accuracy of the determination of the deformation of the rotor blade can be increased.

In particular, when determining the deformation of the rotor blade, the falsification of the detection of the at least one operating position of the at least one position marking due to the mechanical self-oscillation of the position detection device is at least partially corrected by at least partially filtering out the at least one frequency range of the mechanical self-oscillation of the position detection device ,

As a result, the resulting measurement error of the position detection device or the device due to a mechanical natural vibration of the position detection device can be at least partially suppressed.

For example, the frequency of the mechanical self-oscillation of the bulkhead in the range between 20 and 500 Hz and the frequency of the relevant mechanical oscillations of the rotor blade between 0.5 and 20 Hz. Detects the position detection device deformations, in particular natural oscillations, with a frequency range between z. B. 20 and 500 Hz, these frequency ranges or this at least one frequency range is filtered out by a computing unit, so that measurement errors due to a mechanical natural vibration of the position detection device can be corrected.

In a further refinement, at least one frequency range of a mechanical natural vibration of the rotor blade is determined or detected in order to determine the natural vibration of the position detection device as a function of the mechanical self-oscillation of the rotor blade and to take it into account when determining the deformation of the rotor blade.

If, on the other hand, only at least one frequency range of the mechanical oscillations of the rotor blade, which has a frequency between 0.5 and 20 Hz, for example, is taken into account in the determination of the deformation of the rotor blade, only mechanical natural oscillations detected by the position detection device will be in the range between 0.5 and 20 Hz used to determine the deformation, d. H. a frequency range greater than 20 Hz is not used to determine deformation. The rotor blade can also have so-called vibration modes as natural oscillations, which is an integer multiple of the frequency range of z. B. 0.5 to 20 Hz is concerned. For example, mechanical self-oscillations of 0.5 to 100 Hz can thereby also occur on the rotor blade. In the case of such superimpositions between the frequency range of the rotor blade (for example 0.5 to 100 Hz) and the bulkhead (eg 20 to 500 Hz), individual ones thereby become individual in this overlapping region (eg 20 to 100 Hz) Harmonic, which affect the frequency of the rotor blade, not taken into account. As a result, a part of the mechanical vibrations of the rotor blade is not taken into account, but the resulting falsification of the measurement results is not essential.

It is also possible to provide a plurality of position detection devices along the longitudinal direction of the rotor blade, with the mechanical natural oscillations of the plurality of position detection devices being determined or detected. The mechanical natural vibrations of the plurality of position detection devices can then turn in an evaluation unit In particular, a comparison of the individual values can be carried out.

In a further preferred embodiment of the method according to the invention, at least one frequency range of a mechanical natural vibration of the position detection device in a learning phase outside the operation of the wind turbine and / or during an operating phase of the wind turbine can be determined or detected.

Outside the operation of the wind turbine, for example, a force is applied to the hub or the rotor blade with a hammer, so that thereby the rotor, in particular the bulkhead, is excited to a mechanical natural vibration and then the frequency of this mechanical natural vibration is measured.

Alternatively or cumulatively, at least one frequency range of a mechanical natural vibration of the rotor blade can be determined or detected in a learning phase outside the operation of the wind turbine and / or during an operating phase of the wind turbine.

By way of derogation or in addition to this, a vibration sensor can also be attached to the position detection device or bulkhead, and during the operation of the wind power plant the at least one frequency range of the mechanical natural vibration of the position detection device is measured with the vibration sensor and subsequently taken into account in the evaluation of the measurement results of the position detection device. The mechanical self-oscillation of the rotor blade can be detected either by vibration sensors on the rotor blade or due to measurements of the position detection device, the mechanical natural vibrations, d. H. the at least one frequency range of the rotor blade determined during the operating phase.

A detection of the one frequency range of a mechanical natural vibration of the position detection device and / or the one frequency range of the mechanical natural vibration of the rotor blade can therefore basically be carried out with a vibration sensor and / or yaw rate sensor. The mechanical natural vibration of the position detection device can also be done via the detection of the mechanical vibration of the rotor blade.

In a supplementary embodiment, the mechanical natural vibration of the position detection device may be due to a portion of the rotor blade. Here, the portion of the rotor blade, which causes the mechanical natural vibration of the position detection device, a bulkhead or a hub of the rotor. The position detection device is attached to the bulkhead, so that the position detection device carries out a mechanical self-oscillation of the bulkhead. The mechanical natural frequency of the bulkhead thus substantially corresponds to the mechanical natural frequency of the position detection device.

Suitably, the section of the rotor, in particular the bulkhead, the natural frequency as a vibrating diaphragm and the natural frequency of the portion of the rotor is transmitted directly or indirectly to the position detection device.

Furthermore, the invention provides a device according to the invention for measuring the deformation of a rotor blade, in particular a rotor blade of a wind turbine, comprising:
at least one position marking on the rotor blade, a position detection device for detecting an output position and at least one operating position of the at least one position marking, a means for determining or detecting a frequency range of a mechanical natural vibration of the position detection device and an evaluation unit for determining the deformation of the rotor blade from a Difference between the output position and the at least one operating position of the at least one position marker and the frequency range of the mechanical natural vibration of the position detection device.

In a further embodiment, the device comprises a computing unit. Suitably, the device comprises a memory unit for storing data. The means for determining or detecting a frequency range of a mechanical natural vibration of the position detection device is designed in an advantageous manner as a vibration sensor and / or rotation rate sensor. The evaluation unit can be integrated in the position detection device. Alternatively, the evaluation unit is arranged outside the position detection device.

The invention further provides a wind turbine comprising a rotor with rotor blades and a hub, a bearing for the rotor, a gear, a generator, a device for measuring the deformation of at least one rotor blade, wherein the device is designed as a device described in this patent application and / or a method described by the wind turbine in this patent application is executable.

In this case, the position detection device can be attached directly or indirectly to a bulkhead (the so-called platform and / or a flange and / or a blade bearing and / or a hub of the rotor.

The at least one position marking may be fastened to the at least one rotor blade within the at least one rotor blade and / or at a radial distance to the position detection device with respect to an axis of rotation of the rotor.

The rotor blade expediently consists at least partially, in particular completely, of metal and / or, preferably fiber-reinforced, plastic.

In an additional embodiment, the position detection device, in particular a transmitter or a receiver, has means for wireless and / or wired transmission of measurement signals or data. It is therefore not necessary to provide cables in a wireless transmission from the position detection device to a computing unit.

In an additional embodiment, the device, in particular the position detection device, means for generating electricity to provide itself with energy. For example, these are systems based on the principle of "Energy Harvesting", z. As piezoelectric systems or photoelectric systems with photocells.

In an additional embodiment, the at least one position marking is designed as a light source, which preferably has means for generating electricity.

In the following, an embodiment of the invention will be described in more detail with reference to the accompanying drawings. It shows:

1 Schematic diagram of a device for measuring the deformation of a rotor blade,

2 a partial cross section of a rotor with the device,

3 a greatly simplified partial cross section of the rotor in a region of a bulkhead without deformation of the bulkhead,

4 a greatly simplified partial cross-section according to 3 with a deformation of the bulkhead due to a mechanical oscillation of the bulkhead and 5 a perspective view of a wind turbine.

An in 5 illustrated wind turbine 23 is used to convert wind energy into electrical energy. This is rotatable on a tower 28 a gondola 27 attached. At the gondola 27 is a rotor by means of a bearing, not shown 30 arranged or stored. The rotor 30 includes a hub 13 and three at the hub 13 attached rotor blades 2 , From the hub 13 is by means of a wave 26 a torque on a gearbox 24 and from the transmission 24 by means of another wave 26 on a generator 25 transfer. The from the wave 26 on the generator 25 transmitted mechanical energy is in the generator 25 converted into electrical energy. An arithmetic unit 29 with a memory for storing data is used for controlling and / or regulating the wind turbine 23 , With the arithmetic unit 29 For example, an angle of attack of the rotor blades 2 changed and thereby the loads of the rotor blades 2 z. B. can be reduced or it can be the wind turbine 23 also be switched off completely.

Thus the arithmetic unit 29 For example, a change in the angle of attack of the rotor blades 2 or switching off the wind turbine 23 it is necessary with a device 1 (shown in 1 ) the deformation, in particular a mechanical natural vibration of the rotor blades 2 , capture.

In 1 is simplified a schematic diagram of the device 1 shown. A position detection device 16 as part of the facility 1 includes a transmitter 3 , which is in the form of one or more light-emitting diode and a receiver 4 in the form of a CCD or CMOS receiver 4 is trained. From the transmitter 3 light is radiated and arrives at a retroreflector 5 trained reflector, which thus a position marker 17 represents. The retroreflectors 5 are inside the rotor blade 2 at a sufficient distance from the transmitter 3 and the receiver 4 arranged and on the rotor blade 2 attached, leaving the retroreflector 5 a movement of the rotor blade 2 with carries out. That from the transmitter 3 emitted light is at the retroreflector 5 reflected and the reflected light is transmitted through a lens 9 passed and then passes to the recipient 4 , A starting position 6 of the retroreflector 5 is a position of the retroreflector 5 in an unloaded state of the rotor blade 2 ie, for example, if on the rotor blade 2 no wind energy is acting. In an operating position 7 acts on the rotor blade 2 a force, in particular a wind force on the outside of the rotor blade 2 , thereby causing deformation of the rotor blade 2 and thereby a corresponding co-deformation of the retroreflector 5 comes as this on the rotor blade 2 is attached. This leads to a deviation the position between the starting position 6 and the operating position 7 of the retroreflector 5 ,

In 1 is a position 10 the picture of the retroreflector 5 in the starting position 6 and a position 11 the picture of the retroreflector 5 in the operating position 7 , At a deformation of the rotor blade 2 thus migrates from the lens 9 on the receiver 4 projected light spot from the position 10 to the position 11 , This can be a reflection angle 8th be determined. Based on this reflection angle 8th and the known distance of the retroreflector 5 to the lens 9 , the distance of the lens 9 from the recipient 4 (referred to as the cut width) and the pixel size of the receiver 4 can the deformation of the rotor blade 2 or the change in position of the retroreflector 5 be calculated. Notwithstanding this (not shown), the transmitter 3 also in the place of the retroreflector 5 be arranged so that the transmitter 3 the position marker 17 represents.

In 2 is a schematic section in a part of the rotor 3 shown. At the hub 13 is a cylindrical flange 18 educated. The rotor blade 2 has predominantly a leaf structure and only near the hub 13 is the rotor blade 2 , which consists essentially of fiber-reinforced plastic, cylindrical in cross-section. This cylindrical portion or part of the rotor blade 2 is on the flange 18 postponed. By way of example, a screw, not shown, the rotor blade 2 on the flange 18 the hub 13 attached. To avoid the water or objects inside the rotor blade 2 to the hub 13 arrive, has the rotor blade 2 a bulkhead 14 on. At the bulkhead 14 is the position detection device 16 ie the transmitter 3 and the receiver 4 , attached. Furthermore, the position detection device 16 another vibration sensor 22 on. In addition to the vibration sensor 22 a yaw rate sensor may be provided (not shown). The vibration sensor 22 is for measuring the lateral vibrations of the position detection device 16 provided, wherein the rotation rate sensor, the rotational vibrations of the position detection device 16 detected. That from the transmitter 3 radiated light is thus at the retroreflector 5 to the recipient 4 reflected. The retro reflector 5 may be formed for example in the form of a triple mirror. The measuring range 12 the transmitter 3 is through a cone of light 12 in 2 shown.

Because of the rotor blade 2 on the hub 13 forces to be transmitted occur at the bulkhead 14 to mechanical vibrations of the bulkhead 14 , Such mechanical vibrations of the bulkhead 14 be on the position detection device 16 transmit, so that the position detection device 16 performs these mechanical natural vibrations with. The deformation of the rotor blade 2 is due to an angle change, ie the reflection angle 8th (shown in 1 ), from the arithmetic unit 29 calculated. Due to this mechanical natural vibration of the position detection device 16 become thereby the measurement results of the device 1 falsified. For this reason, the vibration sensor detects 22 the mechanical natural vibrations of the position detection device 16 and the arithmetic unit 29 filters from the device 1 determined mechanical natural oscillations of the rotor blade 2 or the retroreflector 5 in a frequency range which is the mechanical natural vibration of the position detection device 16 corresponds, out. Notwithstanding this, the mechanical natural vibration, ie at least one frequency range of the mechanical natural vibration of the position detection device 16 , even outside the operation of the wind turbine 23 be determined in a learning phase. For this purpose, the rotor 30 or the hub 13 , For example, by means of a hammer, excited to a natural vibration and then a frequency range of the mechanical natural vibration of the bulkhead 14 measured.

In 3 and 4 are greatly simplified part of the rotor 30 in the area of the hub 13 shown. In 3 points the bulkhead 14 no mechanical self-oscillation, ie there is no deformation on the bulkhead 14 on. In 4 occurs a mechanical self-oscillation of the bulkhead 14 on, z. B. during operation of the wind turbine 23 , thereby causing a deformation of the bulkhead 14 and thereby also causes a rotation of the position detection device 16 opposite to the illustration in 3 occurs with the result that an angular rotation 15 represented by the arrow 15 from the transmitter 3 emitted light beam occurs. However, such a falsification of the measurement result, as described, with the arithmetic unit 29 ( 2 ) are filtered out. The arithmetic unit 29 may also be part of the position detection device 16 be (not shown).

Furthermore, the mechanical natural vibration of the rotor blade 2 be determined. For this purpose, for example, during operation of the wind turbines unique vibration sensors 22 on the rotor blades 2 attached and thereby at least one frequency range of the mechanical natural vibration of the rotor blade 2 for a type of wind turbine 23 certainly. By means of this uniquely determined at least one frequency range of the mechanical natural vibration of the rotor blades 2 can from the arithmetic unit 29 at by the institution 1 determined mechanical natural oscillations only this at least one frequency range of the mechanical natural vibration of rotor blade 2 be taken into account, so that thereby mechanical vibrations of the bulkhead 14 or the position detection device 16 which outside of this frequency range or at least one frequency range of the rotor blade 2 are not taken into account. The device 1 can when measuring the mechanical natural vibration or in the device 1 measured results do not distinguish whether the natural oscillations due to a mechanical self-oscillation of the bulkhead 14 occur or by the institution 1 measured natural vibrations due to a mechanical vibration of the rotor blade 2 or the retroreflector 5 occur. By means of the arithmetic unit 29 and the method described can, however, the measurement results of the device 1 be corrected so that due to a natural vibration of the bulkhead 14 or the position detection device 16 from the institution 1 measured natural vibrations are essentially not taken into account and thereby the measurement results of the device 1 essentially not be falsified. Thus, the accuracy of the device 1 be greatly improved.

Overall, with the method according to the invention for measuring the deformation of the rotor blade 2 significant benefits. The mechanical vibrations of the bulkhead 14 or the position detection device 16 be with the vibration sensor 22 recorded and then can from the arithmetic unit 29 from the institution 1 measured natural oscillations in those frequency ranges or in that frequency range are not taken into account, which of the vibration sensor 22 was measured. As a result, almost no falsification of the measurement results of the device occurs in an advantageous manner 1 due to a mechanical natural vibration of the position detection device 16 at the bulkhead 14 on.

LIST OF REFERENCE NUMBERS

1

Device for measuring the deformation of a rotor blade

2

rotor blade

3

transmitter

4

receiver

5

retroreflector

6

Output position of the reflector

7

Operating position of the reflector

8th

angle of reflection

9

lens

10

Position of the image of the retroreflector in the home position

11

Position of the image of the retroreflector in the operating position

12

Measuring range, light cone

13

hub

14

bulkhead

15

Arrow, angular rotation

16

Position detection device

17

location marker

18

flange

19

Rotation axis of the rotor

20

Section of the rotor at a greater distance from the axis of rotation

21

Section of the rotor with a smaller or equal distance to the rotation axis (numbering!)

22

vibration sensor

23

Wind turbine

24

transmission

25

generator

26

wave

27

gondola

28

tower

29

computer unit

30

rotor

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 10200600270854 [0004]
• DE 102009007938 A1 [0005]

Claims (12)

Method for measuring the deformation of a rotor blade ( 2 ), in particular a rotor blade ( 2 ) of a wind turbine ( 23 ), with the steps: detecting an initial position ( 6 ) at least one position marker ( 17 ) on the rotor blade ( 2 ) with a position detection device ( 16 ), Detecting at least one operating position ( 7 ), preferably several operating positions ( 7 ) containing at least one position marker ( 17 ) on the rotor blade ( 2 ) with the position detection device ( 16 ), Determining the deformation of the rotor blade ( 2 ) by means of the difference between the initial position ( 6 ) and the at least one operating position ( 7 ) of the at least one position marker ( 17 ), characterized in that at least one frequency range of a mechanical natural vibration of the position detection device ( 16 ) is determined or detected and when determining the deformation of the rotor blade ( 2 ) is taken into account A method according to claim 1, characterized in that in determining the deformation of the rotor blade ( 2 ) due to the mechanical inherent shrinkage of the position detecting device ( 16 ) occurring falsification of the detection of at least one operating position ( 7 ) of the at least one position marker ( 17 ) is at least partially corrected by the at least one frequency range of the mechanical natural vibration of the position detection device ( 16 ) is at least partially filtered out. Method according to one or more of the preceding claims, characterized in that at least one frequency range of a mechanical natural vibration of the rotor blade ( 2 ) is determined or detected in order to determine the natural oscillation of the position detection device ( 16 ) depending on the mechanical vibration of the rotor blade ( 2 ) and in determining the deformation of the rotor blade ( 2 ). Method according to one or more of the preceding claims, characterized in that a plurality of position detecting means along the longitudinal direction of the rotor blade ( 2 ) are provided, wherein the mechanical natural vibration of the plurality of position detection device ( 16 ) are determined or recorded. Method according to one of the preceding claims, characterized in that at least one frequency range of a mechanical natural vibration of the position detection device ( 16 ) in a learning phase outside the operation of the wind turbine ( 23 ) and / or during an operating phase of the wind turbine ( 23 ) is determined or recorded. Method according to one of the preceding claims, characterized in that at least one frequency range of a mechanical natural vibration of the rotor blade ( 2 ) in a learning phase outside the operation of the wind turbine ( 23 ) and / or during an operating phase of the wind turbine ( 23 ) is determined or recorded. Method according to one of the preceding claims, characterized in that the frequency range of a mechanical natural vibration of the position detection device ( 16 ) and / or a frequency range of a mechanical natural vibration of the rotor blade ( 2 ) from a vibration sensor ( 22 ) and / or rotation rate sensor is detected. Facility ( 1 ) for measuring the deformation of a rotor blade ( 2 ), in particular a rotor blade ( 2 ) of a wind turbine ( 23 ), comprising: at least one position marker ( 17 ) on the rotor blade ( 2 ), a position detection device ( 16 ) for detecting an initial position ( 6 ) and at least one operating position ( 7 ) of the at least one position marker ( 17 ), a means ( 22 ) for determining or detecting a frequency range of a mechanical natural vibration of the position detection device ( 16 ) and an evaluation unit for determining the deformation of the rotor blade ( 2 ) from a difference between the initial position ( 6 ) and the at least one operating position ( 7 ) of the at least one position marker ( 17 ) and the frequency range of the mechanical natural vibration of the position detection device ( 16 ). Device according to claim 8, characterized in that the means ( 22 ) for determining or detecting a frequency range of a mechanical natural vibration of the position detection device ( 16 ) as a vibration sensor ( 22 ) and / or rotation rate sensor is executed. Device according to one of claims 8 or 9, characterized in that the evaluation unit in the position detection device ( 16 ) is integrated. Wind turbine with a device according to one or more of claims 8 to 10, characterized in that the position detection device ( 16 ) directly or indirectly at a bulkhead ( 14 ) and / or a flange and / or a blade bearing and / or a hub ( 13 ) of the rotor ( 30 ) is attached. Wind turbine according to claim 11, characterized in that the at least one position marker ( 17 ), in particular within the at least one rotor blade ( 2 ) and / or at a radial distance to the position detection device ( 16 ) outwardly with respect to a rotation axis ( 19 ) of the rotor ( 30 ), on which at least one rotor blade ( 2 ) is attached.

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