Wind turbine and method of operating wind turbine

Abstract

The invention relates to a wind turbine (1) having at least one rotor blade (2) and a hub (3), the hub (3) comprising a blade bearing (4) for each rotor blade (2), each rotor blade (2) comprising a blade root (5) with a front surface (6), the rotor blade (2) being fixed with the blade root (5) to the respective blade bearing (4) by means of a fixing device (8) so as to form a bearing-blade connection (9), the front surface (6) of the blade root (5) contacts the bearing surface (7), and wherein at least one detection device (10) is provided at each bearing-blade-connection (9), and wherein the at least one detection device (10) is connected to the rotor blade (2) and the blade bearing (4) and is configured to detect a gap (G) between the front surface (6) and the bearing surface (7).

Description

Technical Field

[0001] This invention relates to a wind turbine having at least one rotor blade and a hub, the hub including a blade bearing for each rotor blade, wherein each rotor blade includes a blade root having a leading surface, and wherein the rotor blade is fixed to the corresponding blade bearing by means of a fixing device, thereby forming a bearing-blade-connection, the leading surface of the blade root contacting the bearing surface. The invention also relates to a method of operating the wind turbine. Background Technology

[0002] It should be noted that the term "blade root" or "front surface" of the rotor blade, as used in the following description, is generally referred to as the "blade root face" of the rotor blade.

[0003] Wind turbine blades in operation may suffer root damage due to various reasons, such as design, manufacturing, and / or operating conditions. As damage accumulates, the stiffness and strength of the blade root materials and components begin to deteriorate over time and under operating loads. Therefore, the blade root is a critical component, and when damaged, the blade may detach from the turbine, leading to structural failure with a high risk of turbine damage. Monitoring of the blade root is necessary throughout the entire service life of the wind turbine to prevent root damage from reaching critical levels. Many different methods have been described in the prior art for detecting damage to wind turbine blades: Generally, visual inspection is used to assess rotor blade damage, but this method cannot determine the extent of the damage. However, inspecting the blade roots requires shutting down the turbine, resulting in turbine downtime and energy loss. As an alternative, sensors can be used to monitor rotor blade damage.

[0004] US 9194843 B2 describes how damage can be monitored throughout a rotor blade using acoustic signals. An acoustic sensor is positioned at the blade root to receive airborne acoustic signals emitted from anomalies in the rotating blade during cyclic loading.

[0005] US 2021115904 A1 describes another approach using non-contact sensors. Non-contact sensors, such as laser sensors, measure displacement at the blade root and hub to control loads at the blade root and adjust the pitch angle.

[0006] However, non-contact, particularly optical, measurements have drawbacks, such as the potential for environmental contamination from water, grease, or oil leaks to distort the results. Therefore, the object of this invention is to provide an improved method for monitoring blade root damage in wind turbine rotor blades. Summary of the Invention

[0007] This objective is achieved by providing a wind turbine of the type mentioned above, characterized in that at least one detection device is provided at each bearing-blade-connection, wherein the at least one detection device is connected to the rotor blade and the blade bearing and is configured to detect the gap between the front surface and the bearing surface.

[0008] The term "connection" refers to any type of fixed or contact connection. Therefore, the testing device can be secured to one of the two components, preferably to the rotor blades, by means of a strong connection such as a screw connection or adhesive connection. It can additionally contact the other of the two components to achieve measurement of the gap size.

[0009] The size of the gap between the leading surface of the rotor blade root and the bearing surface can be monitored using at least one detection device. In an ideal bearing-blade connection, the leading surface and the bearing surface abut each other in a flat manner. As blade root damage develops, a gap appears between the two surfaces, and the size of the gap will increase. Depending on the degree of blade root damage, the leading surface and the bearing surface may not abut each other in a flat manner, or they may not abut each other at all, which may lead to loosening of the fasteners and / or a loose bearing-blade connection. Therefore, preferably during the operation of the wind turbine, monitoring the gap size allows for the monitoring of blade root damage, particularly the degree of blade root damage.

[0010] Bolts can be used as a fixing device. They can be fixed to the blade root by means of inserts embedded or combined into the laminated structure of the rotor blade or by means of T-bolts.

[0011] The critical clearance size, particularly the vertical distance between the front surface and the bearing surface, can be correlated with the maximum acceptable level of blade root damage and can be used as a threshold. At least one detection device can be used to detect whether the clearance size reaches and / or exceeds the threshold, in which case wind turbine operation can be stopped to minimize the risk of wind turbine damage.

[0012] The at least one detection device can be used to detect the separation of the bearing surface from the rotor blades, as this results in an increased clearance, or vice versa. Therefore, the at least one detection device is preferably configured to detect the linear distance between the respective front surface and the respective bearing surface. This linear distance is preferably perpendicular to both the front surface and the bearing surface to avoid erroneous detection of the tilted distance between the two surfaces, which may be greater than the actual distance or clearance.

[0013] In a preferred embodiment, the at least one detection device is a measuring device configured to measure the size of the gap between the front surface and the bearing surface, particularly the linear distance. By using a measuring device as the detection device, the gap size can be measured or monitored over time. This allows for the detection of when the gap size reaches and / or exceeds a threshold, and also enables the monitoring of the development of blade root damage by monitoring the increase in gap size over time. Therefore, predictions of future blade root damage can be made based on measurement data collected over time using the at least one measuring device. In a particularly preferred embodiment, the at least one measuring device is a linear displacement sensor, particularly a linear variable displacement transducer.

[0014] The at least one measuring device can be fixed to a rotor blade (where it contacts the bearing surface) or to a blade bearing (where it contacts the front surface). Therefore, the measurement results collected by the at least one measuring device are less susceptible to errors caused by contamination of the measurement environment, especially oil or grease.

[0015] The at least one measuring device can be configured to measure the gap size continuously or periodically. Continuous or periodic measurements can improve the safety of wind turbines because the development of blade root damage can be monitored more accurately. The term "periodically" can be understood as measuring, for example, the gap size, particularly the linear distance, between the front surface and the bearing surface every 10 minutes, every 5 minutes, every minute, or even several times per minute.

[0016] Preferably, the at least one detection device is permanently mounted on the wind turbine, more specifically at the bearing-blade connection between each rotor blade and each corresponding blade bearing. This allows the current clearance size to be detected or measured while the wind turbine is operating. However, if the data collected by the at least one detection device cannot be processed or evaluated by means of the wind turbine (e.g., by the wind turbine controller), it may be advantageous to detect or measure the clearance size during wind turbine downtime. To do this, the at least one detection device can be attached to the wind turbine, more precisely to the corresponding bearing-blade connection, before checking the clearance size. After the check, the at least one detection device can be removed from the wind turbine again to avoid unnecessary components that could negatively impact the operation of the wind turbine.

[0017] The at least one measuring device can be a meter, particularly a digital meter. As mentioned above, the meter can be attached to the wind turbine before inspecting blade root damage, particularly clearance size, and can be removed from the wind turbine after the inspection is completed. In the case of temporary attachment, the at least one measuring device can advantageously and easily be attached to and removed from the wind turbine without damaging any components of the wind turbine. In an advantageous embodiment, the attachment and removal of the at least one inspection device does not require special tools. In other words, the at least one inspection device can be easily attached to and removed from the rotor blades and blade bearings without damaging the rotor blades or blade bearings or any other components of the wind turbine. Temporarily providing at least one inspection or measuring device improves the inspection of blade root damage on the rotor blades of a wind turbine that is already in use and is not configured to retrofit permanently attached inspection or measuring devices or process inspection results or measurement data collected by means of those devices.

[0018] In one embodiment, the at least one detection device is attached to either the inner or outer surface of the rotor blade. This is possible regardless of whether the at least one detection device is permanently or temporarily attached to the wind turbine. Because the at least one detection device is attached to the outer surface of the rotor blade, attachment and removal are simplified due to the easy accessibility of the outer surface. On the other hand, because the at least one detection device is attached to the inner surface of the rotor blade, it can be provided more securely and protected from environmental factors such as rain or wind without the need for additional coverings. Of course, the surface of the rotor blade to which the at least one detection device is attached is the surface in the region at the blade root. In an alternative embodiment, the at least one detection device is attached to the inner surface of the rotor blade, and at least one other detection device is attached to the outer surface of the rotor blade.

[0019] The at least one testing device can be directly connected to the surface of the rotor blade by means of at least one bolt fixed to the rotor blade, in particular an insert of the rotor blade. Alternatively, the at least one testing device can be connected to the surface of the rotor blade by means of a support device fixed to the rotor blade, wherein a support device is provided for each testing device. Of course, any suitable method of connecting the device to the laminating component can be used to connect the at least one testing device to the rotor blade.

[0020] The bearing surface is preferably provided by a stiffening plate disposed at the inner race of the blade bearing or by the inner race of the blade bearing. The bearing surface can be understood as a reference surface contacted by at least one detection device. When the blade surface displaces relative to the bearing surface, the at least one detection device can detect the developing clearance and thus the developing blade root damage. The inner race of the bearing can also be referred to as the inner ring of the bearing.

[0021] When the at least one testing device is connected to the outer surface of the rotor blade, the bearing surface can be provided by the inner race or stiffening plate of the bearing. However, when the at least one testing device is connected to the inner surface of the rotor blade, the bearing surface can preferably be provided by a stiffening plate.

[0022] The number of inspection devices provided at each bearing-blade-connection can vary depending on the type and size of the wind turbine. In an embodiment, two or more inspection devices are evenly distributed along the circumference of the blade root. This is advantageous because by using more than one inspection device at each blade root, the accuracy of inspecting the clearance size and therefore blade root damage can be improved. Preferably, the number of inspection devices is even, wherein corresponding two inspection devices are arranged in opposite positions. The corresponding two inspection devices can also be understood as a pair of inspection devices.

[0023] Preferably, the detection device for each bearing-blade-connection is provided at the location where the maximum local blade root damage is expected to occur along the circumference of the corresponding blade root. In other words, the detection device is preferably provided at those locations at the blade root where the highest local blade root damage is predicted to occur. Therefore, it is unnecessary to monitor the clearance size at other locations along the circumference of the blade root. Thus, only the most critical locations related to blade root damage are monitored, where it can be predicted that no blade root damage or less blade root damage will occur at other locations.

[0024] To provide detection equipment at those critical locations, two corresponding detection devices can be arranged in opposite positions along the circumference of the blade root, and: - An angle of 30° to 60°, preferably 45°, relative to the chord of the corresponding rotor blade.

[0025] - Parallel or at least approximately parallel to the chord of the corresponding rotor blade.

[0026] - Perpendicular to, or at least substantially perpendicular to, the chord line of the rotor blades. (Therefore, one of the two detection devices is positioned on the pressure side of the rotor blades, and the other of the two detection devices is positioned on the suction side of the rotor blades.) The chord mentioned above can be understood as the line connecting the leading and trailing edges of the rotor blades.

[0027] In a particularly preferred embodiment, the wind turbine includes a controller configured to control the operation of the wind turbine based on the detection results of the at least one detection device. The controller may be one already provided at the wind turbine and additionally configured to process data from the at least one detection device and use that data to control the operation of the wind turbine. Therefore, no additional controller is required, saving money and space. Alternatively, the controller may be an additional controller. Generally, any type of controller suitable for processing detection results and / or measurement data and controlling the wind turbine can be used.

[0028] The controller can be configured to stop the operation of the wind turbine once the detection result, particularly the gap size detected by at least one detection device (or the measurement result, particularly the gap size measured by at least one measuring device), reaches and / or exceeds a threshold. This prevents wind turbine damage caused by blade root damage from exceeding acceptable levels and thus reaching and / or exceeding the threshold. The threshold can be pre-calculated, for example, based on finite element analysis. Preferably, the threshold is 3.0 mm.

[0029] However, the wind turbine can remain operational if the detection result of the at least one detection device reaches and / or exceeds the threshold once or twice within a time period of, for example, ten minutes. Operation will only cease if the detection result of the at least one detection device continuously reaches and / or exceeds the threshold within that time period. This makes it easier to handle abnormal detection results.

[0030] The controller can be configured to send information to the wind turbine's off-site control system or to provide notifications in the wind turbine's control software when thresholds are reached and / or exceeded.

[0031] It should be noted that the wind turbine preferably comprises three rotor blades and a hub with three blade bearings, wherein each rotor blade is fixed to a corresponding blade bearing, thereby forming a bearing-blade connection. However, the number of rotor blades and blade bearings can vary depending on the type of wind turbine. Therefore, the number of inspection devices provided at each bearing-blade connection may also vary.

[0032] According to another embodiment of the present invention, a method for operating a wind turbine has at least one rotor blade and a hub, the hub including a blade bearing for each rotor blade, wherein each rotor blade includes a blade root having a leading surface, wherein the rotor blade is fixed to the corresponding blade bearing by means of a fixing device at the blade root, thereby forming a bearing-blade connection, the leading surface of the blade root contacting the bearing surface, wherein at least one detection device is provided at each bearing-blade connection, wherein the at least one detection device is connected to the rotor blade and the blade bearing. The method includes the following steps: - The clearance between the bearing surface and the front surface is detected using at least one detection device, wherein a clearance is detected when the linear distance between the front surface and the bearing surface exceeds a threshold. - Based on the detection and evaluation stopping condition for the gap, wherein the condition is satisfied when at least one detection device detects a gap, and - When the wind turbine is in operation and the shutdown conditions are met, stop the operation of the wind turbine.

[0033] This method can be used for wind turbines with any configuration described herein. The aforementioned advantages can also be achieved by the method according to the invention.

[0034] In the first step of this method, at least one detection device is used to detect the gap between the bearing surface and the front surface, wherein the gap is detected based on the distance between the front surface and the bearing surface. To prevent the detection of erroneous distances, particularly tilted distances, the aforementioned distance is preferably detected perpendicular to both the front surface and the bearing surface. A gap is detected once a threshold is reached and / or exceeded. Preferably, a gap size greater than 3.0 mm is used as the threshold. Alternatively, depending on the wind turbine, and more specifically the bearing-blade-connection, the threshold can be in the range of 1 mm to 5 mm.

[0035] In the second step of the method, a stopping condition is evaluated based on the detection of the gap. This condition can be met when the at least one detection device detects a gap. Alternatively, as mentioned above, this condition is met only if the gap is detected continuously, not once or twice, during a time period of, for example, ten minutes.

[0036] In the third step of the method, the operation of the wind turbine is stopped when the stopping condition is met. In a preferred embodiment, the stopping condition is evaluated, and the wind turbine is stopped by means of the wind turbine's controller. The controller may already be part of the wind turbine and may be additionally configured to process and / or evaluate the detection results of the at least one detection device. The controller may have any configuration described above with respect to the wind turbine.

[0037] Preferably, at least one measuring device is used as at least one detection device, wherein the at least one measuring device is used to measure the distance between the bearing surface and the front surface, wherein a stopping condition is evaluated based on the distance measured by each measuring device, wherein the stopping condition is met when at least one measured distance exceeds a threshold. The advantages and possible configurations of such measuring devices have been described above regarding wind turbines. Measurement, rather than detection, has the advantage of allowing more precise monitoring of the accumulation of blade root damage because it allows for the identification of gap size, particularly increases in the measured distance. Based on the identification of this increase, more accurate predictions about blade root damage can be made. For example, blade root damage can be classified as: - When the gap size, especially the measured distance, is in the range of 0 to 0.5 mm, there is no damage. - When the gap size is in the range of 0.5 to 1.5 mm, it is considered moderate damage. - When the measured gap size is in the range of 1.5 to 3.0 mm, high damage, and - Severe damage occurs when the gap size exceeds 3.0 mm.

[0038] The stopping condition can be met when at least one measured distance reaches and / or exceeds a threshold of 3.0 mm. In the case of wind turbine operation, the wind turbine can be stopped to prevent damage. The operation of the wind turbine can be stopped by means of a controller and / or by means of a person receiving a notification of reaching or exceeding the threshold from the controller, which sends information to the wind turbine's control system and / or control software.

[0039] The above method can be implemented while the wind turbine is in operation. Alternatively, the method can be implemented during wind turbine downtime. Therefore, a testing device can be used as the at least one testing device that is permanently attached to the rotor blades and blade bearings, or that can be attached to and removed from the rotor blades and blade bearings. In the latter case, the at least one testing device can be attached to the rotor blades and blade bearings before checking the clearance between the front surface and the bearing surface. After the inspection, it can be removed again.

[0040] To inspect clearance and thus blade root damage during wind turbine downtime, detachable measuring devices, such as gauges, particularly digital gauges, can be used. Preferably, the attachment and removal of such measuring devices can be easily performed without special tools and without damaging the wind turbine, particularly the rotor blades and blade bearings. Therefore, blade root damage can be inspected even when suitable inspection equipment is not provided or cannot be provided at the wind turbine and / or when it is not possible to process and / or evaluate the inspection results in the wind turbine, for example, by means of the aforementioned controller.

[0041] As described above, measuring devices, particularly sensors, configured to detect and / or measure the linear distance between the front surface and the bearing surface can be used to monitor the clearance size during wind turbine operation. Such measuring devices can be permanently attached to the rotor blades or blade bearings at the bearing-blade connection. Attached Figure Description

[0042] Other objects and features of the invention will become apparent from the following specific embodiments considered in conjunction with the accompanying drawings. However, these drawings are merely schematic diagrams designed for illustrative purposes only and do not limit the invention. The drawings show: Figure 1 This is a schematic diagram illustrating an embodiment of a wind turbine according to the present invention. Figure 2 For illustration Figure 1 The diagram shows a schematic cross-sectional view of the bearing-blade-connection of a wind turbine. Figure 3 The illustration shows a device with testing equipment. Figure 1 and Figure 2 A schematic diagram of the bearing-blade-connection. Figure 4 This is a schematic diagram illustrating a bearing-blade connection of a detection device having an outer surface connected to the root of the blade. Figure 5 A sketch of the circumference of the leaf root, with the inspection equipment positioned in relation to the inspection of leaf root damage. Figure 6 This is a schematic diagram of a method for operating a wind turbine. Detailed Implementation

[0043] Figure 1 An example of a wind turbine 1 is schematically shown, having three rotor blades 2 and a hub 3. The hub 3 includes three blade bearings 4, one for each rotor blade 2. Each rotor blade 2 is fixed to the corresponding blade bearing 4 at its blade root 5 by means of a fastening device 8, thereby forming a bearing-blade-connection 9, wherein the front surface 6 contacts the bearing surface 7. Surfaces 6 and 7 are... Figure 2 and Figure 3 As can be seen in the text. Figure 1 The diagram shows two detection devices 10 (dashed lines) at each bearing-blade-connection 9, wherein the detection devices 10 are configured to detect the clearance G between the leading surface 6 of the corresponding blade bearing 4 and the bearing surface 7 of the blade root 5 (see Figure 10). Figure 2 and Figure 3 ).

[0044] For clarity, note again that the “front surface” 6 of the rotor blade 2 or blade root 5 can generally be referred to as the “blade root surface” 6.

[0045] Figure 2 Illustration Figure 1 A cross-sectional view of one of the bearing-blade-connection 9 of the wind turbine 1. The fastening device 8 includes bolts 11 fixed to the blade bearing 4 and inserts 12 of a laminated structure fixed to the blade root 5. Alternatively, it may be provided in the form of a T-bolt connection. During the operation of the wind turbine 1, blade root damage develops, resulting in an increase in the linear distance D between the leading surface 6 and the bearing surface 7, and thus an increase in the clearance G (it should be noted that in Figure 2 and Figure 3 (The size of the clearance G is greatly exaggerated). As a result, the leading surface 6 of the blade root 5 no longer contacts the bearing surface 7 of the corresponding blade bearing 4, and the bearing-blade-connection 9 becomes loose. This can lead to damage to the wind turbine.

[0046] To prevent the risk of structural failure caused by damage to the leaf roots, detection equipment 10 is used. Figure 3 Show Figure 2 The bearing-blade-connection 9 is illustrated, where the detection device 10 is shown in two possible configurations: the bearing surface 7 can be provided by the inner race 13 of the blade bearing 4, also referred to as the "inner ring," or by a stiffening plate 14 arranged at the inner race 13 of the blade bearing 4. The detection device 10 is configured to detect the distance D between the corresponding front surface 6 and the corresponding bearing surface 7, and therefore the size of the clearance G. To do this, it is connected to the rotor blade 2 and the bearing surface 7 provided by the stiffening plate 14, or connected to the rotor blade 2 and the bearing surface 7 provided by the inner race 13 of the blade bearing 4 (dashed line). The linear distance D is detected perpendicular to both the front surface 6 and the bearing surface 7.

[0047] In this example, two detection devices 10 are provided, each of which is connected to the rotor blade 2 (more specifically, the blade root 5) and the blade bearing 4. Exemplarily, one of the detection devices 10 is connected to the outer surface 15 of the rotor blade 2, while the other of the two detection devices 10 is connected to the inner surface 16 of the rotor blade 2. Preferably, the detection device 10 is provided at either the outer surface 15 or the inner surface 16. The two detection devices 10 are connected to the rotor blade 2 by means of fastening devices (not shown) or adhesives, such as bolts and inserts. Figure 4 In the alternative shown, the detection device 10 can be connected to the outer surface 15 of the rotor blade 2 by means of a support device 17. The detection device 10 is fixedly connected to the rotor blade 2 and only touches the bearing surface 7 with its detection tip. When the bearing surface 7 detaches from the front surface 6, or vice versa, the needle of each detection device 10 is pushed against the bearing surface 7 to maintain contact in order to detect the linear distance D.

[0048] Once the distance D exceeds a threshold of 3.0 mm, the gap G is detected by means of the detection device 10. However, in this example, the detection device 10 is a measuring device 18, specifically a linear variable displacement transducer, configured to measure the size of the gap G, particularly the linear distance D. It should be noted that both the detection device 10 and / or the measuring device 18 can be used. Both types of devices 10 and 18 can detect the gap G, with the use of the measuring device 18 enabling more precise monitoring of the size of the gap G. It can detect the gap G not only when the distance D exceeds the threshold but also continuously measure the distance D during the operation of the wind turbine 1. Therefore, the increase and decrease in the size of the gap G can be precisely monitored over time. Based on data collected over time, better predictions can be made, for example, when a critical level of blade root damage or the threshold of distance D is about to be reached. Alternatively, the detection device 10 can be configured to periodically detect (or measure, since it is the measuring device 18) the size of the gap G, thus once or several times within a time period.

[0049] Several inspection devices 10 can be used at each bearing-blade-connection 9. The concept is to provide inspection devices 10 along the circumference C of the blade root 5 at locations P1-P3 where the highest localized blade root damage is most likely to occur during the operation of the wind turbine 1 (see [reference]). Figure 5Therefore, the size of the gap G is monitored at the most critical locations P1-P3, where it can be expected that all other locations along the circumference C of the blade root 5 will show minor blade root damage or no blade root damage, and therefore no inspection is required. It should be noted that the detection device 10 can provide monitoring at other critical locations at the blade root 5, such as locations that may become critical due to the production or transport of the rotor blade 2. Therefore, the critical locations P1-P3 mentioned in the following description are merely exemplary locations, where additional critical locations may be added.

[0050] like Figure 5 As illustrated, eight inspection devices 10 are evenly distributed along the circumference C of the blade root 5. The number of inspection devices 10 provided at the bearing-blade-connection 9 is even, and corresponding two inspection devices 10 are arranged in opposite positions along the circumference C. However, the number of inspection devices 10 can vary.

[0051] according to Figure 5 The two corresponding detection devices 10 are provided at the most critical positions P1-P3 along the circumference C of the leaf root 5: - Position P1 forms an angle A of 45° with respect to the chord 19 (dashed line) of rotor blade 2. - Position P2 is parallel to or at least approximately parallel to chord 19, and - Position P3 is perpendicular or at least approximately perpendicular to chord 19.

[0052] Chord 19 connects the leading edge LE and trailing edge TE of rotor blade 2. In other embodiments, angle A can vary from 30° to 60°.

[0053] The wind turbine 1 also includes a controller 20 (shown in...) Figure 1 and Figure 3 In the case of a measuring device 18, the controller 20 is configured to control the operation of the wind turbine 1 based on the detection results (or measurement data) of the detection device 10. If the wind turbine 1 is operating and one of the detection devices 10 detects a distance D exceeding a threshold of 3.0 mm, the operation of the wind turbine 1 is stopped. Alternatively, the operation of the wind turbine 1 is only stopped if the detected distance D exceeds the threshold consecutively or exceeds the threshold a certain number of times within a time period (e.g., more than three times within ten minutes). Therefore, damage to the wind turbine 1 caused by blade root damage can be prevented. The controller 20 is also configured to send information such as detection results or measurement data to the off-site control system 21 of the wind turbine 1, and to provide a notification in the control software 22 of the wind turbine 1 when the threshold is exceeded (see [link to relevant documentation]). Figure 1 ).

[0054] The aforementioned method of monitoring the size of the gap G can be implemented during the operation of the wind turbine 1. Therefore, the inspection device 10 is permanently mounted at the blade root 5 of the rotor blade 2, thus contacting the bearing surface 7. However, it can be provided in an attachable and detachable manner at the corresponding bearing-blade-connection 9. This allows the inspection device 10 (or measuring device 18) to be temporarily attached during downtime of the wind turbine 1 to inspect the blade root 5, particularly for damage to the blade root 5. Such an inspection device 10 can be attached to the rotor blade 2 before inspection, preferably to the outer surface 15 of the rotor blade 2, and then removed after inspection. Therefore, the operation of the wind turbine 1 is not negatively affected by unnecessary equipment fixed to the rotor blade 2. However, the operation of the wind turbine 1 must be stopped for inspection. In this case, a meter, particularly a digital meter, can be used as the measuring device 18 or the inspection device 10.

[0055] Figure 6 Showing the operation Figure 1 The diagram shows a schematic flowchart of a method for operating a wind turbine 1. This method can be applied to operating a wind turbine 1 having any of the specifications described above.

[0056] In the first step S1, the detection device 10 is used to detect the gap G between the bearing surface 7 and the front surface 6 (see...). Figure 2 and Figure 3 As described above, a gap G is detected when the linear distance D between the current surface 6 and the bearing surface 7 exceeds a threshold of 3.0 mm. In the second step S2, a stopping condition is evaluated based on the detection of the gap G. The stopping condition is met when at least one detection device 10 detects the gap G. In the final step S3, if the wind turbine 1 is operating and the stopping condition is met, the operation of the wind turbine 1 will be stopped.

[0057] Of course, this method can be implemented using a detection device 10 (which is a measuring device 18), as described above. In this case, the stopping condition is evaluated based on measurement data between the bearing surface 7 and the front surface 6 of each bearing-blade-connection 9, particularly the measured linear distance D. The stopping condition is met when at least one measuring device 18 measures a linear distance D that exceeds a threshold. Alternatively, the stopping condition is met only when the measured distance D exceeds the threshold several times or consecutively during a time period.

[0058] To perform steps S2 and S3, the wind turbine 1 may include a controller 20 having any of the specifications described above (see Figure 1 and Figure 3This method can be implemented using a detection device 10, which is permanently connected to the rotor blades 2 and the blade bearings 4, or can be attached to and removed from the rotor blades 2 and the blade bearings. Preferably, attachment and removal can be easily performed without special tools and without damaging the wind turbine.

[0059] Although the present invention has been described in detail with reference to preferred embodiments, the present invention is not limited to the disclosed examples, and those skilled in the art can derive other modifications based on the disclosed examples without departing from the scope of the present invention.

[0060] Regardless of grammatical usage, individuals with masculine, feminine, or other gender identities are included in this term.

Claims

1. Wind turbine (1) having at least one rotor blade (2) and a hub (3), the hub (3) comprising for each rotor blade (2) one blade bearing (4), wherein Each rotor blade (2) comprises a blade root (5) having a front surface (6), wherein the rotor blade (2) is fixed with the blade root (5) to a respective blade bearing (4) by means of a fastening device (8) so as to form a bearing-blade-connection (9), the front surface (6) of the blade root (5) contacting a bearing surface (7), characterized in that at each bearing-blade-connection (9) at least one detection device (10) is provided, wherein the at least one detection device (10) is connected to the rotor blade (2) and the blade bearing (4) and is configured to detect a gap (G) between the front surface (6) and the bearing surface (7).

2. Wind turbine (1) according to claim 1, characterized in that The at least one detection device (10) is configured to detect a linear distance (D) between the respective front surface (6) and the respective bearing surface (7).

3. Wind turbine (1) according to claim 1 or 2, characterized in that The at least one detection device (10) is a measuring device (18) configured to measure a gap size, in particular the linear distance (D), between the front surface (6) and the bearing surface (7).

4. Wind turbine (1) according to claim 3, characterized in that The at least one measuring device (18) is a linear displacement sensor, in particular a linear variable displacement transducer.

5. Wind turbine (1) according to claim 3 or 4, characterized in that The at least one measuring device (18) is configured to measure the gap size continuously or periodically.

6. A wind turbine (1) according to claim 3, characterised in that The at least one measuring device (18) is a gauge, in particular a digital gauge.

7. Wind turbine according to one of the preceding claims, characterized in that The at least one detection device is connected to an inner or outer surface of the rotor blade.

8. Wind turbine (1) according to one of the preceding claims, characterized in that The bearing surface (7) is provided by a stiffener (14) arranged at an inner race (13) of the blade bearing (4) or by the inner race (13) of the blade bearing.

9. Wind turbine (1) according to one of the preceding claims, characterized in that Two or more detection devices (10) are evenly distributed along a circumference (C) of the blade root (5).

10. Wind turbine (1) according to claim 9, characterized in that The number of detection devices (10) is even, wherein respective two detection devices (10) are arranged at opposite positions.

11. Wind turbine (1) according to one of the preceding claims, characterized in that The wind turbine (1) comprises a controller (20) configured to control an operation of the wind turbine (1) depending on a detection result of the at least one detection device (10).

12. A method for operating a wind turbine (1) having at least one rotor blade (2) and a hub (3) comprising one blade bearing (4) for each rotor blade (2), wherein Each rotor blade (2) comprises a blade root (5) having a front surface (6), wherein the rotor blade (2) is fixed with the blade root (5) to a respective blade bearing (4) by means of a fastening device (8) so as to form a bearing-blade-connection (9), the front surface (6) of the blade root (5) contacting a bearing surface (7), wherein at each bearing-blade-connection (9) at least one detection device (10) is provided, wherein the at least one detection device (10) is connected to the rotor blade (2) and the blade bearing (4), wherein the method comprises the following steps: detecting a gap (G) between the bearing surface (7) and the front surface (6) using the at least one detection device (10), wherein a gap (G) is detected when a linear distance (D) between the front surface (6) and the bearing surface (7) exceeds a threshold value, evaluating a stop condition based on the detection of the gap (G), wherein the condition is fulfilled when the at least one detection device (10) detects the gap (G), and stopping the operation of the wind turbine (1) when the wind turbine (1) is in operation and the stop condition is fulfilled.

13. The method of claim 12, wherein, using at least one measuring device (18) as the at least one detection device (10), wherein the at least one measuring device (18) is used to measure the distance (D) between the bearing surface (7) and the front surface (6), wherein the stop condition is evaluated based on the measured distance of each measuring device (18), wherein the stop condition is fulfilled when at least one measured distance exceeds a threshold value, wherein preferably a gap size of more than 3.0 mm is used as the threshold value.

14. The method of claim 12 or 13, wherein, using a detection device as the at least one detection device (10) which is permanently connected to the rotor blade (2) and the blade bearing (4) or which can be attached to and removed from the rotor blade (2) and the blade bearing (4).

15. The method of claims 12-14, wherein, evaluating the stop condition and stopping the wind turbine (1) by means of a controller (20) of the wind turbine (1).

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