DE102016005159A1 - Method and device for measuring wind speed and wind direction on wind turbines with rotor blades flowing around them - Google Patents

Abstract

Method and device for wind speed and wind direction measurement on wind turbines with flow around rotor blades, in which a gondelfeste measuring arrangement of flow sensors (4) in the outflow of the rotor blades (2.1) is arranged, wherein a plurality of spaced apart flow sensors (4.1, 4.2, 4.3) on or are arranged on the nacelle (1), which are coated by the oblique flow generated behind the rotor blades (2.1) in the direction of the nacelle (1).

Description

The invention relates to a method for wind speed and wind direction measurement on wind turbines with flow around rotor blades according to the preamble of patent claim 1, and a device according to the preamble of patent claim 5.

By far the most dominant design is the three-bladed wind turbine with horizontal axis and rotor on the windward side, whose engine house is mounted on a tower and the wind direction is actively tracked.

Such a method is with the subject of the EP 2 876 302 A1 known. A control and monitoring method of a wind turbine is described by means of a wind speed estimation with the aid of a gondola-mounted LIDAR sensor. Likewise, a measuring method for controlling and / or monitoring a wind turbine is described, which is equipped with a LIDAR sensor.

The control and / or monitoring takes place in consideration of an estimate of the wind speed, which is thereby focused by means of an estimation function and a LIDAR sensor, which is arranged behind the rotor and on a line arranged in front of the rotor. The estimation of the prevailing wind before the rotor then takes place on the basis of the LIDAR sensor determined data and the wind propagation model.

A disadvantage of the known control and monitoring method is the complicated use of a radar-based sensor that can only be operated with great effort. He is prone to repair and costly.

With the subject of EP 2 494 192 A1 a wind sensor system has become known with the aid of rotor blade signals.

This document describes a method which aims at a wind yield measurement taking into account the height-dependent wind velocity gradient. It is taken into account that the rotor blade is exposed to different wind speeds and wind directions during one revolution. The sensors mounted on the rotor blade are used for measuring value acquisition. However, the transmission of the measuring signals of the rotating sensors to a gondelfeste detection device is faulty and expensive. Finally, a mean effective wind speed is determined from a complex data set by means of a tabulated wind speed field characteristic and a search device.

According to general understanding, the existing measuring equipment on the wind turbine are used to capture the necessary measurement signals, whereby the advantageous lower cost of the process is justifiable.

It would be only the existing measuring equipment on the wind turbine, without using their own sensors. However, this is associated with the disadvantage that only inaccurate measurements are possible because there are no special sensors for determining wind direction and wind strength.

With the subject of EP 2 048 507 A2 Also, a rotor-side sensor system for a wind turbine has become known.

This document describes a measuring method for measuring at least one wind feature (wind speed, wind direction, and the like) in which the measuring sensors are mounted on the hub of the rotor in such a way that they are in the direction of flow in front of the rotor blade and rotate with it. The sensor system is arranged on the hub of the rotor blade in a forwardly oriented, approximately horizontally oriented dipstick which is intended to detect the inflow field.

Therefore, with such a sensor arrangement only the wind speed and possibly also the wind direction can be determined and requires the use of a relatively long measuring rod, at the front free end of which a sensor is arranged. However, there is the disadvantage that the measuring rod must be aligned in the axis of rotation. It is assumed that there is no imbalance on the hub side, whereby the measurement result would be falsified. The wireless transmission of the measuring signals of the rotating with the rotor measuring device on a gondola-side evaluation is complicated and prone to failure.

In addition, there is a risk that a strong Windanströmung deflects the dipstick, whereby the measurement result is falsified.

With the subject of DE 20 11 43 51 U1 a wind vector determining device has become known.

In order to avoid that the arranged behind the rotor wind measuring means get into a turbulent flow, 4 Prandtl pitot tubes are arranged on a rotationally symmetrical rod in a common plane and rotatably mounted on the rotating hub. From the rotational speed and the interaction with the dynamic pressure of the acting wind, the wind direction and the wind speed in front of the hub be measured. A disadvantage of this arrangement is the mounting of the measuring lance on the rotating hub, which is rotationally symmetrical to install, in order to avoid errors in measurement due to transverse movements due to eccentricity.

With the subject of EP 1 733 241 B1 For example, another method and apparatus for determining wind speed and direction on a wind turbine has become known.

The document includes the arrangement of ultrasonic measuring sections on a location on the hub of the rotor or on and in a lance in front of the hub of the rotor in order to obtain information about the "true" wind direction and the wind speed. The rotational behavior of the measurement setup with respect to the incoming wind is taken into account. In an arrangement with several ultrasonic measuring sections, the wind speed and the wind direction can be measured in 3 spatial directions.

A disadvantage of this arrangement is that due to the relatively short measuring distance and its rotational movement on the hub a very precise transit time measurement is required, which is reflected significantly in the cost. Another disadvantage is that the "true" wind direction and the associated wind speed as a result of the Vorstaus the rotor and the aerodynamic effect of the hub on which the ultrasonic measuring sections are mounted, already undergo a falsification that can not be corrected or only very expensive.

• • In Bereich der windabgewandten Seite der Rotationsebene, also hinter dem Rotorblatt angeordnete Messeinrichtungen besitzen den Nachteil, dass die Messwerte für die Windgeschwindigkeit und die Windrichtung durch die Wirbelbildung stromabwärts des Rotors Messabweichungen zeigen, die zu einer nicht optimalen Ausrichtung der Windkraftanlage im Wind führt. Charakteristisch ist hier ein durch den Einfluss der Rotordrehung verfälschtes Windrichtungssignal. Die Mittelwertbildung beseitigt zwar in der praktischen Nutzung dynamische Schwankungen im Messsignal, Prinzip bedingt verbleibt aber eine systematische Messabweichung die von der Windgeschwindigkeit abhängig ist und so immer zu einer Fehlausrichtung der Windkraftanlage im Wind führt. Bisherige Messsysteme wie z. B. weit verbreitete Schalenanemometer mit Windfahne oder Ultraschallanemometer sind im Allgemeinen zu träge, um die genannte systematische Messabweichung zu erfassen und schließlich berichtigen zu können.
• • Auf der Nabe des Rotorblattes installierte Windmesseinrichtungen beseitigen zwar das Problem der verwirbelten Windströmung, müssen aber weit vor dem Rotor angeordnet sein, um aus dem Bereich des Vorstaus des Rotors zu gelangen, wie es beim Patent DE20114351 B1 zur Anwendung kommt.
• • Andere technische Ausführungen versuchen es in ähnlicher Weise, wenn man dazu das Patent EP 1733241 in Betracht zieht. Derartige Messsysteme sind im Allgemeinen aufgrund ihrer Anordnung im Rotorsystem der Anlage sehr kostenintensiv, was die Nachrüstung und die Wartung derartiger Messsysteme auf Windenergieanlagen betrifft.
• • Windfeldvermessende Systeme auf Basis der Partikelrückstreuung von Licht oder Ultraschall (wie z. B. LIDAR oder SODAR) wären geeignete Systeme für eine verbesserte Windrichtungsnachführung der Windenergieanlage. Derartige Systeme sind aber technisch komplex und weisen eine sehr kostenintensive Messtechnik auf, die bisher noch keine breite Anwendung gefunden hat.

In summary, the named state of the art can be characterized as follows:

• • In the region of the windward side of the plane of rotation, so arranged behind the rotor blade measuring devices have the disadvantage that the measured values for the wind speed and the wind direction by the vortex formation downstream of the rotor show deviations that leads to a non-optimal orientation of the wind turbine in the wind. Characteristic here is a distorted by the influence of the rotor rotation wind direction signal. Although the averaging eliminates dynamic fluctuations in the measurement signal in practical use, the principle remains a systematic error that depends on the wind speed and thus always leads to a misalignment of the wind turbine in the wind. Previous measuring systems such. B. widespread Anemometer with wind vane or ultrasonic anemometer are generally too slow to detect the aforementioned systematic error and eventually correct.
• Although wind measuring devices installed on the hub of the rotor blade eliminate the problem of swirling wind flow, they must be arranged far in front of the rotor in order to get out of the area of the rotor's pre-jam, as in the patent DE20114351 B1 is used.
• • Other technical versions try it in a similar way, if you add the patent EP 1733241 considers. Such measuring systems are generally very expensive due to their arrangement in the rotor system of the system, which relates to the retrofitting and maintenance of such measurement systems on wind turbines.
• • Wind field measuring systems based on particle backscatter of light or ultrasound (such as LIDAR or SODAR) would be suitable systems for improved wind direction tracking of the wind turbine. However, such systems are technically complex and have a very cost-intensive measurement technology that has not yet found wide application.

The invention is therefore based on the EP 2 876 302 A1 the object of developing a method and a device operating according to the method so that a detection of the wind speed and the wind direction on the side facing away from the wind of the rotor assembly can be done much more accurate and the measuring sensors used for this purpose are cheaper.

To solve the problem, the invention is characterized by the technical teaching of claim 1.

• 1. Die für die Erfassung von Windgeschwindigkeit und Windrichtung erforderlichen hochdynamischen Strömungssensoren sind zueinander in festen Abständen und bezogen auf die Anströmrichtung unmittelbar hinter der Rotationsebene des Rotorblattes der Windkraftanlage angeordnet.
• 2. Der Abstand zwischen der Rotorblattebene und der Anordnung der Strömungssensoren ist so gewählt, dass die Rotationsebene des auf der Nabe befindlichen Rotorblatts diese Anordnung der Strömungssensoren nicht berührt.
• 3. Der Abstand ist weiterhin so gewählt, dass die Wirkung des vorbeilaufenden Rotorblattes auf die Windströmung von den Messaufnehmern zeitgleich erfasst wird und aus dem zeitlichen Verlauf der von den Messaufnehmern erfassten Messsignalen die Windrichtung und die Windgeschwindigkeit bestimmt wird.

According to a first embodiment of the present invention, the following is provided cumulatively or in isolation according to one and / or more of the following features:

• 1. The required for the detection of wind speed and wind direction high-dynamic flow sensors are arranged to each other at fixed intervals and with respect to the direction of flow directly behind the plane of rotation of the rotor blade of the wind turbine.
• 2. The distance between the rotor blade plane and the arrangement of the flow sensors is selected so that the plane of rotation of the rotor blade located on the hub does not touch this arrangement of the flow sensors.
• 3. The distance is further chosen so that the effect of the passing rotor blade is detected at the same time on the wind flow of the sensors and the wind direction and the wind speed is determined from the time course of the measured signals detected by the sensors.

A feature of the invention is therefore that on the windward side of the rotor blade assembly, a plurality of spaced-apart flow sensors are arranged on a gondelfesten measuring plane, which are coated by the generated behind the rotor blade in the direction of the nacelle oblique flow.

The invention makes use of the finding that resulting flows arise in the region of the rotor blade resulting from the superimposition of the direction of flow of the wind and the direction of rotation of the rotor blade, wherein the measuring arrangement according to the invention is arranged in this region of the overlapping flows. The resulting flow region on the leeward side of the rotor assembly is referred to as outflow in the following.

The measuring principle of the present measuring arrangement preferably uses a plurality of flow sensors arranged one behind the other on the same line, wherein this arrangement should preferably be parallel to the plane of rotation of the rotor blades.

This means that if, for example, three flow sensors arranged at a distance from one another are arranged on a nacelle surface of the nacelle, the first flow sensor in the flow direction is flown first, then the middle flow sensor and finally the following further flow sensor.

Of course, the invention is not limited to the arrangement of three sensors arranged at a distance from one another, which also need not necessarily be arranged on a straight line one behind the other.

They can also be arranged on a curved line or even on a circle segment with a fixed radius, i. H. be arranged on the circumference of a measuring disk. Such a measuring disc can be attached as a separate part and subsequently on the gondola.

In a preferred embodiment of the invention it is provided that such a measuring arrangement is arranged on the upper side (cover side) of the nacelle near the rotor blade.

This is essential because the incoming flow directly in the plane of rotation of the rotor blades changes their wind direction and wind speed with increasing distance from the rotor plane, so that at the rear part of the nacelle for the measurement process unfavorable measuring conditions exist, so that care should be taken that the flow sensors as close as possible are arranged on the front end of the nacelle.

The close arrangement of the flow sensors behind the rotor blade allows to determine both the wind direction and the wind speed.

A characteristic of the measuring method is that it uses the aerodynamic effect of the rotor blade passing by by the incoming wind before and after the passage and in particular the outflow during the passage of the rotor blade by means of flow sensors, for example, arranged along a line immediately behind the rotor are recorded in their amplitude and their time course, so as to infer the oncoming "true" wind.

According to a feature of the invention, it is provided that the advantageously three flow sensors arranged at a distance from each other separately measure the amplitude of the wind speed.

A feature of the invention is that the detected amplitude profiles of the wind speeds at each flow sensor depend on the wind speed of the incoming wind and the outflow.

From the differences in the detected amplitude curves of the individual flow sensors, the angle of attack and the flow velocity in the plane of rotation can be determined.

The temporal offset between the detected amplitude curves of the flow sensors is also a measure of the wind speed and its direction.

Depending on the arrangement of the flow sensors to the plane of rotation of the time offset .DELTA.t is thus a measure of the resulting angle of attack, which occupies the effluent from the rotor blades in the direction of the measuring arrangement wind flow.

With a linear arrangement of the flow sensors perpendicular to the direction of flow in a homogeneous wind field, all sensors measure the same signal. With an additional rotational movement of the rotor, the direction of flow of the sensors changes. The changed angle of attack leads to different signal characteristics at the sensors. The invention is relatively free in the arrangement of the flow sensors.

In a first embodiment of the invention it is provided that the flow sensors a line lying on a flat and approximately horizontal top surface of the nacelle are arranged.

If the top surface of the nacelle bent, it may also be possible that the sensors are arranged on a curved surface in the direction of a horizontal plane, wherein the radius of this line, which goes through all measuring sensors should correspond approximately to the curvature of the top surface.

In a third embodiment it can be provided that the flow sensors are arranged on the vertical end face of the nacelle in the hub region of the rotor assembly and in a fourth embodiment it can be provided that the flow sensors with spacer rods uniformly on the circumference of the nacelle over an angle of 180 ° are arranged, wherein the flow sensors are arranged at the front free end of each rod-shaped spacers.

These spacers have the purpose of bringing the flow sensors as far as possible from the relatively windless region out of the hub of the rotor blades radially outward into the outflow region of the rotor blade arrangement.

A cheap length for such spacers is z. B. a measure of z. B. 2 m or the like.

Of course, instead of the individual, consisting of rods spacers and other arrangement elements may be used, such. B. triangular or even circular elements, on the circumference of which said flow sensors are arranged.

In a fifth embodiment, it can be provided that the flow sensors are arranged on the circumference of a measuring disk, wherein this measuring disk is arranged flat on the top surface of the nacelle and has moved as close as possible to the hub region of the rotor blade assembly.

The subject of the present invention results not only from the subject matter of the individual claims, but also from the combination of the individual claims with each other.

All information and features disclosed in the documents, including the abstract, in particular the spatial design shown in the drawings, are claimed to be essential to the invention insofar as they are novel individually or in combination with respect to the prior art.

As far as individual items are referred to as "essential to the invention" or "important", this does not mean that these items necessarily have to form the subject of an independent claim. This is determined solely by the current version of the independent claim.

In the following the invention will be explained in more detail with reference to drawings showing only one embodiment. Here are from the drawings and their description further features essential to the invention and advantages of the invention.

Show it:

1 : Schematically a plan view of a nacelle with a rotor blade assembly

2 : Schematically an oblique view of a nacelle from the front with several ways of arranging flow sensors

3 : Schematically another arrangement of flow sensors on the nacelle of a wind turbine

4 : End view of the outflow area behind the rotor blade arrangement

5 : schematized a rotor blade with representation of the various, associated there profiled shapes

6 : further embodiment for the arrangement of the flow sensors

7 : schematizes the representation of the flow of a rotor blade and the oblique outflow generated behind the rotor blade

8th : schematizes the measurement signals of the three flow sensors arranged in a line

9 : Calculation circuit for determining the wind direction and the wind speed

The high-dynamic sensors required for the detection of wind speed and wind direction 4.1 . 4.2 and 4.3 become for example in fixed equidistant intervals 4.6 parallel to the plane of rotation of the rotor blade 3.2 and orthogonal to the alignment axis of the nacelle 4.4 on the nacelle of the wind turbine 1 arranged.

The distance between the plane of rotation of the rotor blades 3.2 and the arrangement line of the flow sensors 4.5 is chosen so that the distortion 2.2 at the hub 2 attached rotor blade 2.1 regardless of the angle of attack 5 the arrangement line of the flow sensors 4.5 not touched.

The distance is further selected so that the effect of the passing rotor blade 2.1 on the wind flow from the sensors 4.1 . 4.2 . 4.3 is recorded at the same time and from the time course of the of the sensors 4.1 . 4.2 . 4.3 detected measurement signals, the wind direction and the wind speed are determined.

In 1 is also shown that the Windanströmrichtung 6 taken from the front and on the leeward side of the rotor blade 2.1 an oblique outflow is created, which is at the top 7 the nacelle arranged flow sensors 4.1 . 4.1 . 4.3 meets.

The flow sensors 4.1 . 4.2 . 4.3 lie in the embodiment shown preferably on a straight array line 4.5 because it is assumed that the top 7 the gondola 1 is also formed straight in the profile.

Is the top 7 The gondola curved, she would according to 2 on a curved arrangement line 4.5 lie.

You should have as far as possible an equidistant distance to simplify the calculation circuit.

However, this is not necessary for the solution, because they can also have different distances, but this increases the effort in the evaluation of the measurement signals.

As stated, the distance should be 4.6 be as equal as possible. But it can also be different.

The 2 shows as another embodiment, the possibility that the flow sensors 4.1 - 4.3 on the vertical front 8th the gondola 1 can be arranged, but as far as possible from the rotor shaft 9 should be removed, in the embodiment shown, for example, in the direction of arrow 10 rotates.

The 3 shows as a further embodiment, that it is advantageous if the flow sensors 4.1 - 4.3 at the free ends of spacers 13 are arranged so as to be a distance 11 from the surface of the gondola 1 to provide.

This has the advantage that the flow sensors 4.1 - 4.3 in the outflow area 15 directly on the windward side of the rotor blade 2.1 be moved and the greater the distance 11 is, the cheaper the flow of the flow sensors 4.1 - 4.3 ,

However, they should be in their measurement plane based on the front page 8th as close as possible to the plane of rotation of the rotor blades 3.2 be laid, but without the rotor blade 2.1 to collide.

In 3 is also schematized that the gondola 1 in a conventional manner on the upper tower segment 14 is arranged.

The 4 schematically shows the structure of a resulting on the windward side of the rotor blades flow, which does not necessarily have to be centric, but it can be directed obliquely downwards, as shown by 7 will be explained.

In any case, it is favorable, the flow sensors 4.1 - 4.3 in the outflow area 15 to lay as far as possible from the hub area of the rotor blade 2.1 moved radially outwards.

At this outflow area 15 closes a radially inward lying intermediate area 16 on, in which not so favorable flow conditions exist as in the outflow area 15 and then a hub region closes radially inwardly 17 in which the flow conditions also unfavorable for the arrangement of the flow sensors 4.1 - 4.3 are. However, the invention is not based on the arrangement of the flow sensors 4.1 - 4.3 in the radially outer outflow area 15 limited. The flow sensors 4.1 - 4.3 could also be in the intermediate area 16 and in the hub area 17 be arranged, in which case the arithmetic circuit must be adjusted accordingly.

The favorable for the measuring arrangement outflow area 15 is located in the aerodynamic profile area 19b of the rotor blade, as based on the 5 is explained.

Each rotor blade consists essentially of a blade root 18 with which the rotor blade 2.1 at the hub 2 is attached and the leaf root 18 usually has a cylindrical area 19a ,

To the cylindrical area 19a closes the aerodynamic profile area 19b on, extending to the tip of the blade 19c extends.

It is therefore convenient, the flow sensors 4.1 - 4.3 from about position 25 ie between the cylindrical area 19a and the blade tip 19c in the outflow area 15 position the rotor blade, the area of the blade root 18 and in particular the cylindrical region 19a for the positioning of the flow sensors 4.1 - 4.3 Not is excluded. It is therefore the entire length 26 the rotor blade is available, it being preferred that the flow sensors 4.1 - 4.3 in the aerodynamic profile area 19b as close as possible to the cylindrical area 19a relocate.

The 6 shows as a further embodiment, the disc-shaped arrangement of the flow sensors 4.1 - 4.3 on a measuring disk 23 , where the flow sensors 4 evenly spaced around the circumference of a circle 21 are arranged and the measuring disc 23 for example as a foil disc on the top 7 the gondola is glued on.

The in the outflow area 15 located measuring disc 23 is in the direction of flow 22 coming from the direction of movement of the rotor blade 3.1 and the Windanströmrichtung 6 results, streamed, as in 7 shown.

The direction of flow 22 thus arises from the vectorial superposition of Windanströmrichtung 6 and the direction of movement of the rotor blade 3.1 ,

In this area is the measurement level 24 the flow sensors 4.1 - 4.3 arranged.

The 8th schematically shows signals of the flow sensors 4.1 - 4.3 with mutually temporally shifted amplitude curves, as they are due to an oblique flow of the flow sensors in the direction of flow 22 arise.

This results in different time offsets Δt1, Δt2 and Δt3, which are a measure of the wind direction and the wind speed.

Similarly, the amplitudes A1, A2 and A3 of the signals are included in the measurement result, so that with an arithmetic circuit 20 , in the 9 is shown, from the three signals of the flow sensors 4.1 . 4.2 . 4.3 be generated by mathematical algorithms of a digital arithmetic circuit, the wind direction wR and the wind speed wG as a digital measurement signal.

This is an algorithm that is capable of taking into account the time offsets and amplitudes of the various flow sensor measurement signals 4.1 - 4.3 to form a measurement result for the wind direction and wind speed.

Overall, with the measuring device according to the invention, which consists of a simple measuring arrangement of several flow sensors and uses the aerodynamic outflow, a cost-effective measuring device can be created that dispenses with complex procedures such as LIDAR and SODAR and essentially from highly dynamic flow sensors or other highly dynamic sensors such , As hot wire anemometers, pressure sensors or heated thermistors consists.

LIST OF REFERENCE NUMBERS

1

gondola

2

hub

2.1

rotor blade

2.2

Verdrehebene of the rotor blade

3.1

Direction of movement of the rotor blades

3.2

Rotation plane (the rotor blades)

4

flow sensors

4.1

first flow sensor

4.2

second flow sensor

4.3

third flow sensor

4.4

Longitudinal axis of the gondola

4.5

assembly line

4.6

distance

5

angle of attack

6

Windanströmrichtung

7

Top (from 1 )

8th

Front side (from 1 )

9

rotor shaft

10

arrow

11

distance

13

spacer

14

Upper tower segment

15

outflow region

16

intermediate area

17

hub area

18

blade root

19.a

cylindrical area

19.b

aerodynamic profile area

19.c

blade tip

20

computing circuit

21

circumference

22

flow direction

23

measuring disk

24

measuring plane

25

position

26

length

wR

wind direction

wG

wind speed

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

• EP 2876302 A1 [0003, 0020]
• EP 2494192 A1 [0006]
• EP 2048507 A2 [0010]
• DE 20114351 U1 [0014]
• EP 1733241 B1 [0016]
• DE 20114351 B1 [0019]
• EP 1733241 [0019]

Claims (10)

Method for measuring wind speed and wind direction on wind power plants with rotor blades flowing around, in which a gondelfeste measuring arrangement in the outflow region of the rotor blades ( 2.1 ) is arranged, characterized in that the aerodynamic effect of the rotor blade passing in the wind is used by the incoming wind before and after the passage and in particular the outflow during the passage of the rotor blade by means of flow sensors, for example, arranged along a line immediately behind the rotor are recorded in their amplitude and their time course, so as to infer the oncoming "true" wind. Method according to claim 1, characterized in that the distance between the flow sensors ( 4 ) is selected so that the effect of the passing rotor blade ( 2.1 ) on the wind flow from the flow sensors ( 4 ) is detected at the same time and from the time course of the flow sensors ( 4 ) recorded measurement signals, the wind direction and the wind speed is determined. Method according to one of claims 1 to 2, characterized in that the spaced apart flow sensors ( 4 ) separately detect the amplitude of the flow velocity separately. Method according to one of claims 1 to 3, characterized in that the spaced apart flow sensors ( 4 ) detect the amplitude curves of the flow velocity offset in time. Device for measuring wind speed and wind direction on wind power plants with rotor blades flowing around, in which a gondelfeste measuring arrangement in the outflow region of the rotor blades ( 2.1 ) is arranged, characterized in that a plurality of spaced apart flow sensors ( 4 ) on or at the gondola ( 1 ) are arranged from the behind the rotor blades ( 2.1 ) in the direction of the gondola ( 1 ) oblique flow are coated. Apparatus according to claim 5 for carrying out the method according to one of claims 1 to 4, characterized in that the flow sensors ( 4 ) at fixed distances from each other parallel to the plane of rotation ( 3.2 ) of the rotor blade ( 2.1 ) and orthogonal to the longitudinal axis of the nacelle ( 4.4 ) at the gondola ( 1 ) of the wind turbine are arranged. Device according to one of claims 5 or 6 for carrying out the method according to one of claims 1 to 4, characterized in that the distance between the plane of rotation ( 3.2 ) and the arrangement line ( 4.5 ) of the flow sensors ( 4 ) is chosen so that the Verdrehebene ( 2.2 ) of the hub ( 2 ) located rotor blade ( 2.1 ) the arrangement line ( 4.5 ) of the flow sensors is not touched. Device according to one of claims 5 to 7, characterized in that at least two spaced apart flow sensors ( 4 ) on a gondelfest surface ( 7 . 8th ) of the nacelle ( 1 ), and that first the upstream flow sensor ( 4.1 ), then the subsequent flow sensor ( 4.2 ) and finally further arranged flow sensors. Device according to one of claims 5 to 8, characterized in that the measuring arrangement of the flow sensors ( 4 ) on the top ( 7 ) of the nacelle ( 1 ) is arranged near the rotor blade. Device according to one of claims 5 to 9, characterized in that the flow sensors ( 4 ) at the free ends of spacer rods evenly around the circumference of the nacelle ( 1 ) are arranged over a circumferential angle of 180 °.

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