Rotor blade monitoring system

Abstract

The invention relates to a rotor blade monitoring system. A rotor blade (220, 320, 420, 520, 620, 720) for a wind turbine (760) is described, comprising: at least one camera (101) mounted within the rotor blade and adapted to acquire an image of a portion of an inner surface (219) of the rotor blade (220).

Description

[0001] This application is a divisional application of a Chinese patent application named "Rotor Blade Monitoring System" with an application number of 201980021057.0, filed on September 22, 2020. Technical Field

[0002] The present invention relates to rotor blades for wind turbines, to rotor blade monitoring systems, to wind turbines, and also to a method for monitoring the structural state of the rotor blades of a wind turbine. Background Art

[0003] A wind turbine may include a rotating shaft having a hub, to which a plurality of rotor blades are mounted. The rotating shaft may be mechanically coupled to the rotor of a generator to generate electrical energy when the hub to which the rotor blades are attached rotates. The rotor blades may be subject to wear during operation, such that they deteriorate over a longer operating time.

[0004] Therefore, it is necessary to monitor the structural state or structural integrity of the rotor blades. To avoid severe failure modes of the blade structure, the monitoring of the structural health of wind turbine blades may generally require regular on-site inspections. However, inspecting the blades on a wind turbine on-site is currently expensive and time-consuming. In addition, it may be weather-dependent, and wind turbines are often located in remote areas or at inaccessible locations in offshore facilities, making it difficult to plan and perform inspections. Furthermore, today's rotor blades are relatively large and expensive components of wind turbines. Therefore, long structural repairs involving stopping energy production or blade loss due to structural damage may involve significant drawbacks.

[0005] Maintenance personnel perform routine visual on-site inspections on all wind turbines in a wind farm once a year or every two years. Thereby, the maintenance personnel enter the blade, inspect the surface, and take photos if any suspicious observations are found. Such a monitoring operation can only be completed for one blade at a time, since the blade to be inspected needs to be horizontal, which may in turn place requirements on the weather conditions. The decision as to whether there is damage is made subjectively by a person, and the final result will depend on the expertise and experience of that person.

[0006] Therefore, there may be a need for rotor blades for wind turbines, for rotor blade monitoring systems, for wind turbines, and also for a method for monitoring the structural state of the rotor blades of a wind turbine, wherein the monitoring can be performed in a simplified and reliable manner, especially without the presence of maintenance personnel. Summary of the Invention

[0007] This need can be met by the subject matter of the independent claims. Advantageous embodiments of the invention are described by the dependent claims.

[0008] According to an embodiment of the present invention, there is provided a rotor blade for a wind turbine, comprising: at least one camera mounted within the rotor blade and adapted to acquire an image of a portion of the inner surface of the rotor blade.

[0009] The camera may be adapted to acquire one or more two-dimensional images of the portion of the inner surface of the rotor blade. Thus, the camera may include, for example, a plurality of photosensitive elements arranged in a two-dimensional array. The photosensitive elements may include, for example, CCD or CMOS cells. The (one or more) cameras may also include one or more filters that filter out one or more spectral ranges, such as the visible range, the infrared light range, the ultraviolet range, thereby allowing an image to be formed by acquiring the intensity of a selected (one or more) wavelength range. In addition, one or more lenses or generally objective lenses may be arranged in front of the photosensitive elements to allow focusing. The camera may be permanently mounted within the rotor blade such that when the wind turbine is in normal operation and generating electrical energy while the rotor blade is rotating, the camera is also mounted within the rotor blade. Depending on the extent of the rotor blade and the viewing range (e.g., angle) of the camera, a plurality of cameras may be mounted within the rotor blade and at different positions such that they can substantially acquire an image of the entire inner surface of the rotor blade. Thereby, it is possible to avoid maintenance personnel entering the rotor blade and manually taking pictures of critical areas of the inner surface.

[0010] The rotor blade may have an (internal) hollow space with at least one shear web. The shear web (or web) may be an internal structural sub-component of the rotor blade. It connects the spar caps present at the pressure side and the suction side and may have the function of transmitting shear loads that exist in the blade due to flapwise bending moments applied to the structure. It may be constituted by or include a composite sandwich panel having a plywood core and a glass fiber reinforced plastic (GFRP) skin.

[0011] The camera may be mounted directly or indirectly at an installation portion of the inner surface, for example, by gluing the mounting surface of the camera or the mounting surface of the frame to which the camera is mounted to the installation portion of the inner surface. The camera may also be bolted within the rotor blade or may be mounted by other means. Thereby, a simple monitoring of the structural state of the blade can be achieved.

[0012] According to an embodiment of the present invention, the rotor blade further includes at least one light source mounted within the rotor blade, adapted to generate illumination light and arranged to illuminate the portion of the inner surface.

[0013] Other embodiments of the present invention may not require a light source because light from the environment may enter the rotor blade, for example when at least part of the rotor blade wall is transparent. However, in order to more precisely control the brightness, the light source can advantageously precisely adjust the brightness of the illuminated portion of the inner surface and / or adjust the image acquisition time of the camera to acquire at least one image. For example, using a control module or the like, at least one light source can be controllable with respect to turning the light source on and off and / or also with respect to adjusting the brightness or intensity of the light source. For example, the control module can be adapted to control the light source to turn on the light source only when at least one image needs to be acquired for monitoring the rotor blade. For example, at least one image can be taken on a regular basis, such as once a day, once every two days, once a week, three times a month, or once a year. During these image acquisition periods, the light source can be controlled to turn on. The illumination light can at least include visible light (e.g., from about 300 nm to about 800 nm) and / or can at least include one or more wavelength ranges within the visible spectrum. Additionally, the illumination light can include or can not include infrared light (or at least some wavelength ranges of the infrared spectrum) and / or ultraviolet light or ultraviolet wavelength ranges. Having appropriate illumination by the light source can improve the image quality.

[0014] According to an embodiment of the present invention, at least one camera and / or at least one light source are mounted at the mounting portion of the inner surface, wherein the at least one camera and / or at least one light source are particularly mounted using an adhesive.

[0015] The inner surface can be the surface of the rotor blade wall that provides an airfoil on the outer side for wind impact. The airfoil is shaped to apply momentum to the rotor blade towards the axis of rotation in order to achieve the rotation of the axis of rotation. When the camera and / or light source are mounted at the mounting portion of the inner surface, it may not be necessary to specifically provide a particular mounting device, but the camera and / or light source can simply be mounted at the inner surface that is not modified compared to the conventional inner surface of the rotor blade.

[0016] When using an adhesive, the shape of the outer surface of the rotor blade (especially the airfoil-forming part) may not be changed or affected. Thus, the aerodynamic properties of the rotor blade can remain unchanged. The adhesive can be or include, for example, a polymer resin that has already hardened, thus forming a cross-linked polymer. Moreover, the rotor blade wall (having an inner surface and an outer airfoil) can be made of a cross-linked polymer. Other manufacturing materials and methods are also possible. Thereby, it is possible to mount the camera and / or light source at the rotor blade material that is conventionally used.

[0017] According to an embodiment of the invention, at least one camera and / or at least one light source are mounted on at least one frame, which is mounted on the inner surface. The frame can enable appropriate adjustment of the orientation of the camera and / or the light source such that the light source illuminates an area of the inner surface that is also within the viewing range of the camera. Additionally, the frame can enable appropriate adjustment of the orientation and positioning of the camera and / or the light source such that the camera does not block the illumination light and is not in the illumination light path. One camera, two cameras, three cameras or even more cameras and one light source, two light sources, three light sources or even more light sources can be mounted on the frame.

[0018] According to an embodiment of the invention, the frame has a mounting surface that is shaped to fit, in particular complementary to the shape of the mounting portion of the inner surface. When the mounting surface of the frame is complementary to the shape of the mounting portion of the inner surface, the mounting surface can be glued to the mounting portion of the inner surface in a simple manner, thus simplifying the mounting of the frame into the rotor blade. Providing the frame can allow the use of conventionally available cameras and light sources without the cameras and light sources having particularly shaped mounting surfaces, since the frame can act as an adapter. Thereby, costs can be reduced. The frame can be made of any material, such as polymers, metals, wood, any plastics, any thermosetting materials, etc. In particular, frames with different shapes regarding their mounting surfaces can be utilized, which have corresponding mounting surfaces complementary to different mounting portions of the inner surface, for example along the longitudinal direction of the rotor blade.

[0019] According to an embodiment of the invention, at least one camera includes a plurality of cameras, which are mounted within the rotor blade and are adapted to acquire a plurality of images of a plurality of portions of the inner surface of the rotor blade, in particular a plurality of partially overlapping portions, and / or wherein the light source includes a plurality of light sources, which are mounted within the rotor blade and are arranged to illuminate a plurality of portions of the inner surface.

[0020] Having a plurality of cameras and / or a plurality of light sources can enable substantially monitoring of the entire inner surface of the rotor blade.

[0021] In other embodiments, at least one camera includes exactly one camera, in particular having a large viewing angle covering 180°.

[0022] According to an embodiment of the invention, at least one image acquisition unit is formed by a component of at least one camera (in particular three cameras) and at least one light source, all mounted on one frame, wherein the rotor blade particularly includes a plurality of image acquisition units, and further particularly a plurality of sets of image acquisition units arranged to face each other.

[0023] Providing at least one image acquisition unit can simplify the construction and reduce costs. Inside the rotor blade, one image acquisition unit can be mounted, for example, on the back side of the windward outer surface of the rotor blade, and another image acquisition unit can be relatively mounted inside the rotor blade at the back side of the leeward outer surface of the rotor blade. Thereby, a set of acquisition units is formed. Several sets of image acquisition units can be mounted inside the rotor blade, for example, spaced apart along the longitudinal direction of the rotor blade.

[0024] According to an embodiment of the invention, the cameras on one image acquisition unit: are oriented to have viewing directions that differ by at least 20°, particularly between 25° and 70°, and more particularly between 35° and 40°, and / or are mounted close to each other so as to be able to acquire images from the entire surface of interest.

[0025] In particular, on one image acquisition unit, three or for example six cameras with different viewing directions can be provided. The three cameras can acquire the corresponding images simultaneously or successively, and the images can be stitched together, thereby producing a combined image including information of substantially 180° or the entire back side of the leeward outer side or the windward outer side of the rotor blade. In other embodiments, there can be only one camera in the image acquisition unit, which has a viewing angle, for example, between 170° and 180°.

[0026] According to an embodiment of the invention, the mounting part of the inner surface is the back surface of the airfoil part of the blade. The airfoil part can be a part of the leeward side or the windward side of the rotor blade.

[0027] According to an embodiment of the invention, multiple parts of the inner surface substantially cover the entire longitudinal extension of the blade. Thereby, comprehensive monitoring of the rotor blade can be achieved.

[0028] According to an embodiment of the invention, at least one camera is sensitive to at least a part of visible light and / or to at least a part of infrared light and / or to at least a part of ultraviolet light.

[0029] Moreover, the light source can be adapted to generate visible light and / or can be adapted to generate at least a part of ultraviolet light and / or a part of infrared light. Depending on the type of damage to be identified, it may be advantageous to use different wavelength ranges.

[0030] According to an embodiment of the invention, the rotor blade further includes a wireless or wired communication interface for transmitting control signals and / or image data between at least one camera and / or at least one light source and a control module outside the rotor blade. In addition, electrical energy can be supplied to the blade monitoring system from outside the rotor blade.

[0031] For example, using control signals from an external (or internal) control module, the camera and / or light source can be controlled to turn on or off, or can be configured with respect to the generated light intensity or brightness or with respect to image acquisition time, focusing, applying filters, etc. The camera (or a processing module in the rotor blade) can be enabled to perform some preprocessing, such as performing averaging, filtering, feature extraction, etc. A wired-based communication interface can be suitable for cables and / or optical cables.

[0032] According to one embodiment, there is provided a rotor blade monitoring system, comprising: a rotor blade according to any one of the foregoing embodiments; and an analysis module comprising image processing capabilities to process the image to identify features in the image indicative of damage to the inner surface.

[0033] The analysis module can access a reference image library, which can be compared with images acquired by a camera inside the rotor blade or within the rotor blade in order to detect faults or damage. Any electronic device (e.g., included in the analysis module) can be enclosed in a suitable housing for protecting the electronic device, the housing providing a specific IP rating, for example.

[0034] According to an embodiment of the present invention, there is provided a wind turbine, comprising: a rotating shaft; and a rotor blade according to any one of the foregoing embodiments or a rotor blade monitoring system according to the foregoing embodiment, wherein the rotor blade is mounted at the rotating shaft.

[0035] It should be understood that, according to embodiments of the present invention, features disclosed, described or explained individually or in any combination in the context of a rotor blade or a rotor blade monitoring system or a wind turbine can also be applied individually or in any combination to a method for monitoring the structural state of a rotor blade of a wind turbine, and vice versa.

[0036] According to an embodiment of the present invention, there is provided a method for monitoring the structural state of a rotor blade of a wind turbine, the method comprising: using at least one camera mounted inside the rotor blade to acquire at least one image of a portion of the inner surface of the rotor blade; and analyzing the image to determine the structural state of the rotor blade.

[0037] The above and other aspects of the present invention are apparent from and will be explained with reference to the examples of embodiments to be described hereinafter. The present invention will be described in more detail hereinafter with reference to the examples of embodiments, but the present invention is not limited to these examples of embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 Schematically shows an image acquisition unit that can be installed in a rotor blade according to an embodiment of the present invention;

[0039] Figure 2 Schematically shows the viewing angle of a camera of an image acquisition unit configured according to an embodiment of the present invention;

[0040] Figure 3 Schematically shows in perspective the arrangement of two image acquisition units within a rotor blade according to an embodiment of the present invention;

[0041] Figure 4 、 Figure 5 and Figure 6 Schematically shows a further arrangement of an image acquisition unit within a rotor blade according to an embodiment of the present invention;

[0042] Figure 7 Shows a method scheme of a method for monitoring a rotor blade according to an embodiment of the present invention; and

[0043] Figure 8 Schematically shows a wind turbine according to an embodiment of the present invention. Detailed Description

[0044] The illustrations in the drawings are in schematic form. Note that in different figures, similar or identical elements are provided with the same reference numerals or reference numerals that differ only in the first digit from the corresponding reference numerals.

[0045] According to an embodiment of the present invention, a plurality of permanently installed camera sensors periodically (e.g., at regular time intervals) take pictures covering the entire inner surface of the rotor blade from the root to the tip where the web starts. The camera sensors can be collected in a unit together with a light source, e.g., as Figure 1 shown in schematic form in

[0046] Thereby, Figure 1 shows an image acquisition unit 100 that can be installed within a rotor blade according to an embodiment of the present invention. Thereby, the image acquisition unit 100 includes a component of at least one camera 101, at least one light source 103, and a mounting frame 105, and the camera 101 and the light source 103 are mounted at the mounting frame 105. In addition, the mounting frame or frame 105 includes a mounting plate 107 having a mounting surface 109, which can be directly attached to the inner surface of the rotor blade, for example, by gluing.

[0047] The image acquisition unit 100 can include more than one camera 101, e.g., two cameras, three cameras, or even more cameras, which can be oriented to direct their respective viewing ranges in different angular ranges. The camera 101 can include, for example, imaging optics (optionally including one or more spectral filters) and an array of photosensitive elements, e.g., a two-dimensional CCD array or a CMOS array.

[0048] The mounting frame 105 includes a component mounting area 111 which includes threaded holes where components such as the camera 101 and the light source 103 can be bolted. The mounting plate 107 can be made of wood, thermosetting materials, polymers, metals, etc. The mounting surface 109 can be shaped to be complementary to the shape of the inner surface or a part of the inner surface of the rotor blade. The image acquisition assembly 100 also includes a control board and / or a communication interface 113 which can perform to control the camera 101 and / or the light source and which can also perform some data processing, such as the image data acquired by the camera 101.

[0049] A single image acquisition unit having multiple sensors or cameras can cover different angles and can ensure that at least or greater than 180° will be covered. In Figure 2 a cross-section viewed along the longitudinal direction 215 of the rotor blade schematically shows a diagram of the viewing ranges of three cameras. In this figure, a part of the rotor blade wall 217 is schematically shown as having an inner surface 219 and an outer surface 221, and the outer surface 221 can be the airfoil of the rotor blade 220. The image acquisition unit 200 is mounted at a part of the inner surface 219 of the rotor blade and includes three cameras in the illustrated example, and the three cameras have three overlapping viewing ranges 223a, 223b, 223c. The viewing ranges 223a, 223b, 223c are each 36° in the illustrated example. As can be seen from Figure 2 it, the three cameras are oriented to have viewing directions 225a, 225b, 225c with a difference of 32°. Since their respective viewing angles are 36°, the images acquired by the three cameras will overlap within an angular range of 4°, and the overlap is indicated by the reference numeral 227. In other embodiments, the combined viewing range can cover 180°.

[0050] Figure 3 A perspective view schematically shows a part of a rotor blade 320 according to an embodiment of the present invention, in which two acquisition units 300a and 300b are installed, and each acquisition unit includes three cameras and one or more light sources. The rotor blade is schematically shown in a partially cut-away form as having a rotor blade wall 317 which has an inner surface 319 and an outer surface 321. In the illustrated example, each of the two cameras installed in the image acquisition unit 300a has a viewing range of 49.2°. The two cameras are oriented such that an overlap of 30° is achieved.

[0051] According to an embodiment of the present invention, a monitoring system may include an image sensor covering 180° (e.g., including a lens / objective lens). In principle, this can be done with a single image sensor (e.g., having a lens), but the quality may be too poor.

[0052] When using more image sensors (e.g., having lenses) to cover 180°, it is important that there is an overlap (margin) between the observation ranges of the individual image sensors.

[0053] The second image acquisition unit 300b orients its two or three cameras such that their observation areas 302b (composed of the observation areas 330b1, 330b2 of the two cameras) partially overlap with the observation area 302a of the first image acquisition unit 300a (composed of the observation areas 330a1, 330a2 of the two cameras). According to an embodiment of the present invention, within the observation areas 302a, 302b, additional image acquisition units may be installed, which can then monitor the opposite side, that is, the inner surface where the image acquisition units 300a and 300b are installed.

[0054] Figure 4 A front view is schematically shown, in which the longitudinal direction 415 of the rotor blade is in the horizontal direction. The first image acquisition unit 400a and the second image acquisition unit 400b are installed within the rotor blade and are spaced apart by a distance l in the longitudinal direction 415. Each of the image acquisition units 400a, 400b includes three cameras. The first camera has an observation range 231al, another camera has an observation range 231a2, and the third camera has an observation range 231a3. The first camera of the second image acquisition unit 400b has an observation range 231bl, the second camera has an observation range 231b2, and the third camera has an observation range 231b3. Thus, all the observation ranges 231al to 231b3 together substantially cover the entire inner surface of one side of the rotor blade.

[0055] Figure 5 A perspective view of another rotor blade 520 according to an embodiment of the present invention is schematically shown, which has image acquisition units 500a, 500b arranged within the rotor blade at different positions spaced apart along the longitudinal direction 515. Thus, each of the image acquisition units 500a, 500b includes two cameras with different observation ranges, which are observation ranges 530a1, 530a2 for the first image acquisition unit 500a. In addition, the two cameras of the second image acquisition unit 500b have observation ranges 530b1 and 530b2 that overlap by several degrees.

[0056] Figure 6Schematically shown is a rotor blade 620 according to another embodiment of the present invention, which has a number of image acquisition units 600a, 600b. The image acquisition units 600a, 600b are installed within the rotor blade and each has two cameras that monitor overlapping observation ranges.

[0057] Figure 7 A method diagram of a method 740 for monitoring the structural state of a rotor blade of a wind turbine according to an embodiment of the present invention is schematically shown. Thus, the method uses at least one camera installed within the rotor blade to acquire at least one image of a part of the inner surface of the rotor blade. In addition, the image is analyzed to determine the structural state of the rotor blade.

[0058] According to Figure 7 the embodiment shown in, in method step 741, photos are taken, for example, on a daily basis. In decision block 743, it is checked whether the operation is acceptable and whether the image quality is sufficient. If the result of decision block 743 is "yes", then proceed to method step 745, where feature extraction and / or data processing is performed. In decision block 747, it is checked whether the data processing results in a value less than or greater than a threshold. If the value is not less than the threshold, then proceed to method block 749, where a counter is incremented, and the counter counts the number of warnings. In decision block 751, it is checked whether the number of warnings is less than a threshold. If this is not the case, then proceed to method step 753, where an alarm is issued.

[0059] If the number of warnings is less than the threshold, then loop back to the first method step 741.

[0060] If decision block 743 finds that the operation and quality are unacceptable, then proceed to method block 755, where no action is taken and loop back to the first method step 741.

[0061] If decision block 747 finds that the value is less than the threshold, then proceed to method step 757, where no further action is taken and loop back to the first method step 741.

[0062] As can be seen from Figure 2 it, three cameras cover a range of 180°, i.e., one side of the inner surface of the rotor blade. The remaining 180° can be covered by similar acquisition units located on the opposite side of the inner surface. Two units placed opposite each other can be collectively referred to as a set of image acquisition units. To cover the entire length of interest of the blade, multiple sets of image acquisition units can be placed along the blade, as Figure 3 shown.

[0063] According to an embodiment of the present invention, images or photos obtained by different cameras can be transmitted to a diagnostic center or a control module or a processing module, where they can be analyzed in an automated manner to detect damage to the blades. If damage is identified, an alarm can be issued, as shown in method step 753 of Figure 7 The analysis can include feature extraction and can be based on image processing, particularly image segmentation, such as background subtraction. The images can be compared with known healthy (baseline) images or reference images of the inner rotor blades, and if a threshold is reached, for example, the difference between the acquired image and the reference image shows distinct image features, an alarm can be issued. The diagnostic center can be on-site (real-time / online) at the turbine stage or on a remote server (offline). Figure 7 The method shown in

[0064] An embodiment of the present invention can provide several advantages:

[0065] - Images of the inner surface of the rotor blades can be obtained remotely. This can result in a significant reduction in costs, as the same operation would require at least two trained maintenance personnel and regular transportation to the site;

[0066] - The option to automatically analyze the photos and activate an alarm when potential damage is detected;

[0067] - An automated procedure using image processing can be objective in its detection and makes the detection of damage independent of the expertise and experience of experts;

[0068] - A rotor blade according to an embodiment of the present invention can include a permanently internally mounted unit that contains a plurality of camera units and at least one light source. The same pictures can be taken regularly, so that the same viewing angle and light conditions can be applied. Embodiments of the present invention can allow a higher likelihood of detecting damage at an early stage, thus providing lower repair costs and reducing the risk of fatal failures.

[0069] Figure 8 A wind turbine 760 according to an embodiment of the present invention is schematically shown. The wind turbine includes a wind turbine tower 761, and a nacelle 763 is mounted at the tower 761. The nacelle houses a generator 765 having a rotating shaft 767 that is coupled to a hub 769, at which a plurality of rotor blades 720 are mounted, such as Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6For one of the rotor blades shown, an analysis module 771 is arranged within the nacelle 763 and includes image processing capabilities to process images taken by a camera within the rotor blade 720 to identify features in the images indicative of damage to the inner surface of the rotor blade 720.

[0070] It should be noted that the term "comprising" does not exclude other elements or steps, and "a" or "an" does not exclude a plurality. Moreover, elements associated with different embodiments may be combined. It should also be noted that reference signs in the claims should not be construed as limiting the scope of the claims.

Claims

1. Rotor blades (220, 320, 420, 520, 620, 720) for a wind turbine (760), comprising: At least one camera (101), the at least one camera (101) being mounted within the rotor blade and adapted to acquire an image of a portion of the inner surface (219) of the rotor blade (220); At least one light source (103), the at least one light source (103) being mounted within the rotor blade, adapted to generate illumination light and arranged to illuminate the portion of the inner surface (219); And At least one frame (105), Characterized in that The at least one camera (101) and the at least one light source (103) are mounted on the at least one frame (105), and the at least one frame (105) is mounted on the inner surface (219).

2. The rotor blade according to claim 1, wherein, The frame (105) has a mounting surface (109), and the mounting surface (109) is in shape fit with the mounting portion of the inner surface (219).

3. The rotor blade according to claim 2, wherein, The mounting surface (109) of the frame (105) is complementary in shape to the mounting portion of the inner surface (219).

4. The rotor blade according to any one of claims 2 and 3, wherein, The mounting surface of the frame is mounted at the mounting portion of the inner surface using an adhesive.

5. The rotor blade according to any one of the preceding claims, wherein, The at least one camera includes a plurality of cameras, the plurality of cameras being mounted within the rotor blade and adapted to acquire a plurality of images of a plurality of portions (330a1, 330a2, 330b1, 330b2) of the inner surface of the rotor blade, in particular a plurality of images of partially overlapping plurality of portions, Wherein, the light source (101) includes a plurality of light sources, the plurality of light sources being mounted within the rotor blade and arranged to illuminate the plurality of portions of the inner surface.

6. The rotor blade according to any one of the preceding claims, wherein, At least one image acquisition unit (100, 200, 300a, 300b, 400a, 400b, 500a, 500b, 600a, 600b) is formed by a component of at least one camera, in particular three cameras, at least one light source all mounted on one frame, Wherein, the rotor blade particularly includes a plurality of image acquisition units, and the plurality of image acquisition units are further particularly arranged as multiple groups of image acquisition units mounted facing each other.

7. The rotor blade according to any one of the preceding claims, wherein, The cameras on one image acquisition unit: Are oriented to have viewing directions (225a, 225b, 225c) with a phase difference of at least 20°, particularly between 25° and 70°, and further particularly between 35° and 40°, and / or are mounted close to each other.

8. The rotor blade according to any one of the preceding claims, wherein, The mounting portion of the inner surface (219) is the back surface of the airfoil portion (221) of the rotor blade (220).

9. The rotor blade according to any one of the preceding claims, wherein, The plurality of portions of the inner surface substantially cover the entire longitudinal extension of the rotor blade.

10. The rotor blade according to any one of the preceding claims, wherein, The at least one camera (101) is sensitive to at least a portion of visible light and / or at least a portion of infrared light and / or at least a portion of ultraviolet light.

11. The rotor blade according to any one of the preceding claims, further comprising: Based on a wireless or wired communication interface (113), the communication interface (113) is used to transmit control signals and / or image data between the at least one camera and / or the at least one light source and a control module outside the rotor blade.

12. A rotor blade monitoring system, comprising: A rotor blade (720) according to any one of the preceding claims; and an analysis module (771) comprising image processing capabilities to process the image to identify features in the image indicative of damage to the inner surface.

13. A wind turbine (760), comprising: a rotating shaft (767); and a rotor blade (720) according to any one of claims 1 to 11 or a rotor blade monitoring system according to claim 12, wherein the rotor blade (720) is mounted at the rotating shaft (767).

14. A method for monitoring the structural state of a rotor blade of a wind turbine, the method comprising: Use a rotor blade (220) according to any one of claims 1 to 11; Obtain (741) at least one image of at least a portion of the inner surface (219) of the rotor blade (220) using at least one camera mounted within the rotor blade; and Analyze (743, 745, 747) the image to determine the structural state of the rotor blade.

Images