EP4689630A1

EP4689630A1 - Method and system for inspecting an electrically conductive component for a wind turbine blade

Info

Publication number: EP4689630A1
Application number: EP23716808.3A
Authority: EP
Inventors: Aparna Chakrapani Sheila-Vadde; Manoj Kumar Koyithitta Meethal; Mamatha VENUGOPAL; Prasad Thapa; Vikas Kaushik
Original assignee: LM Wind Power AS
Current assignee: LM Wind Power AS
Priority date: 2023-03-30
Filing date: 2023-03-30
Publication date: 2026-02-11
Also published as: CN120958319A; WO2024199662A1

Abstract

An inspection system (200) for use during manufacturing for inspecting a moving electrically conductive component (300) of a blade for a wind turbine (10) is described. The inspection system (200) includes an eddy current array probe device (210) having at least two electromagnetic coils (220) being offset from each other. The inspection system further includes a sensor device for sensing eddy currents induced in the electrically conductive component (300) by the eddy current array probe device (210); and a constant-liftoff mechanism (500) for maintaining a substantial constant liftoff (231) between the eddy current array probe device (210) and the electrically conductive component (300). Further, an inspection method for inspecting an electrically conductive component (300) of a blade for a wind turbine (10) during manufacturing of the blade of the wind turbine is described.

Description

METHOD AND SYSTEM FOR INSPECTING AN ELECTRICALLY CONDUCTIVE

COMPONENT FOR A WIND TURBINE BLADE

FIELD

[0001] The present disclosure generally relates to an inspection system for a part of a wind turbine blade, and more particularly to an inspection system for an electrically conductive part of a wind turbine blade. The present disclosure further relates to a method for inspecting an electrically conductive part of a wind turbine blade.

BACKGROUND

[0002] Wind power is considered one of the cleanest, most environmentally friendly energy sources presently available, and wind turbines have gained increased attention in this regard. A modem wind turbine typically includes a tower, generator, gearbox, nacelle, and one or more rotor blades. The rotor blades capture kinetic energy from wind using known foil principles and transmit the kinetic energy through rotational energy to turn a shaft coupling the rotor blades to a gearbox, or if a gearbox is not used, directly to the generator. The generator then converts the mechanical energy to electrical energy that may be deployed to a utility grid.

[0003] The size of rotor blades contributes to the energy efficiency of wind turbines. In particular, an increase in rotor blade size can increase the energy production of a wind turbine. The economic benefits of increased wind turbine sizes or rotor blade sizes must be weighed against respective costs of manufacturing, transporting, assembly or repair of the wind turbines. For instance, the repair of the blades can be very time-consuming and labor intensive. Often, cranes are needed to grip the blades and lower the blades from a rotor hub of a wind turbine to the ground such that the rotor blades can be replaced, or such that maintenance or repair of the blades can be performed on the ground or at a maintenance station.

[0004] However, avoiding repair itself as well as costs and efforts associated with the repair is still the most sustainable and most cost-efficient way. Having less defects from the beginning, by inspecting parts or components before assembly, helps avoiding the repair and maintenance efforts.

[0005] Accordingly, the present disclosure is directed to an inspection system and an inspection method for an electrically conductive component of a wind turbine blade that can reduce repair efforts and costs for a wind turbine blade, or even avoid the replacement of a wind turbine blade.

BRIEF DESCRIPTION

[0006] Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.

[0007] In one aspect, the present disclosure is directed to an inspection system for use during manufacturing for inspecting a moving electrically conductive component of a blade for a wind turbine, the electrically conductive component moving during manufacturing of the blade of a wind turbine. The inspection system includes an eddy current array probe device having at least two electromagnetic coils, wherein the at least two electromagnetic coils include a first electromagnetic coil and a second electromagnetic coil, wherein the first electromagnetic coil and the second electromagnetic coil are offset from each other. According to embodiments described herein, the eddy current array probe device is adapted to be located with a defined liftoff from the electrically conductive component. The inspection system further includes sensor device for sensing eddy currents induced in the electrically conductive component (300) by the eddy current array probe device; and constantliftoff mechanism (500) for maintaining a substantial constant liftoff (231) between the eddy current array probe device (210) and the electrically conductive component.

[0008] With the inspection system according to embodiments described herein, it is possible to inspect electrically conductive components. The components can be inspected by the inspection system according to embodiments described herein before the component is assembled to a wind turbine blade, or even before the components form stacks in horizontal and vertical direction to form the spar beam, a pin joint, or any other component of a wind turbine blade or a wind turbine blade shell. With the system according to embodiments described herein, the components can be inspected as they move along at a certain speed.

[0009] The inspection system according to embodiments described herein allows for inspecting the area of an electrically conductive component, especially by inspecting the (entire) width of an electrically conductive component, while the electrically conductive component is in motion. Particularly, the inspection system according to embodiments described herein allows for inspecting long sections of the electrically conductive component as it moves by the inspection system by inspecting at any instant, the width (especially the full width) of the electrically conductive component in one shot. The eddy current array probe device according to embodiments described herein includes at least two electromagnetic coils. With an appropriate choice of the frequency used for operating the electromagnetic coils, the eddy currents induced by the eddy current array probe device can penetrate substantially the full thickness of the electrically conductive component and can therefore help in the inspection of both surface and internal defects (i.e. surface and sub-surface defects).

[0010] As described in embodiments herein, the eddy current array probe device is placed with a given liftoff from the electrically conductive component. With a defined liftoff between the eddy current array probe device and the electrically conductive components, the eddy current array probe device does not get worn out while inspecting long distances (e.g. kilometers) of the electrically conductive components (such as a plank for a wind turbine blade). Less wear comes with less replacement or repair of elements of the inspection system and, thus, lower costs for the inspection. As the electrically conductive component is pulled along, there can be vibrations to the plank which can cause changes in the inspection signal. The inspection system according to embodiments described herein includes a constant- lift-off mechanism for maintaining the lift-off between the eddy current array probe device and the electrically conductive component substantially constant. In this way, the vibrations can be balanced, or can be considered when evaluating the signal, and the changes to the signal induced by vibrations of the electrically conductive components can be kept at a low level, or can even be substantially avoided.

[0011] In another aspect, the present disclosure is directed to an inspection method for inspecting an electrically conductive component (300) of a blade for a wind turbine (10) during manufacturing of the blade of the wind turbine. The inspection method according to embodiments described herein includes inspecting, during movement of the electrically conductive component, the electrically conductive component by an eddy current array probe device of at least two electromagnetic coils. According to embodiments described herein, inspecting includes sensing by a sensor device the eddy current induced by the eddy current array probe device in the electrically conductive component to be inspected; and maintaining a substantial constant liftoff between the eddy current array probe device (210) and the electrically conductive component by a constant-liftoff mechanism.

[0012] The inspection method according to embodiments described herein may offer a high sensitivity for the inspection of an electrically conductive component in that the sensitivity of detecting defects is high, especially compared to known systems. The inspection method as described in embodiments herein may yield a fairly uniform and reliable response. Typically, the uniform and reliable response may be obtained by maintaining the liftoff between the electrically conductive component and the eddy current array probe device substantially constant during operation. Maintaining the distance substantially constant may include considering the vibrations of the electrically conductive component, reducing the vibrations of the electrically conductive component, or adapting the signal obtained by the inspection to the vibrations of the electrically conductive material.

[0013] In another aspect, the present disclosure is directed to the use of an inspection system according to embodiments described herein in a production system producing the electrically conductive component for the wind turbine for enabling in-line inspection.

[0014] These and other features, aspects and advantages of the present invention will be further supported and described with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS [0015] A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which:

[0016] FIG. 1 illustrates a perspective view of a wind turbine;

[0017] FIG. 2 illustrates a simplified, internal view of a nacelle of a wind turbine, particularly illustrating the nacelle during normal operation;

[0018] FIG. 3 illustrates a schematic top view of an inspection system with an eddy current array probe device according to embodiments described herein;

[0019] FIG. 4 illustrates a schematic top view of an eddy current array probe device according to embodiments described herein;

[0020] FIG. 5 illustrates a schematic front view of an inspection system according to embodiments described herein;

[0021] FIGs. 6 and 7 illustrate schematic side views of inspection systems according to embodiments described herein; and,

[0022] FIG. 8 illustrates a schematic flow chart of an inspection method for a wind turbine blade according to embodiments described herein.

DETAILED DESCRIPTION

[0023] Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents. [0024] Referring now to the drawings, FIG. 1 illustrates a perspective view of a wind turbine 10 according to the present disclosure. As shown, the wind turbine 10 generally includes a tower 108 extending from a support surface 14 (herein also referred to as ground), a nacelle 16 mounted on the tower 108, and a rotor 18 coupled to the nacelle 16.

[0025] As shown in FIG. 1, the rotor 18 includes a rotatable rotor hub 20 and at least one rotor blade 22 coupled to and extending outwardly from the rotor hub 20. For example, in the illustrated embodiment, the rotor 18 includes three rotor blades 22. However, in an alternative embodiment, the rotor 18 may include more or less than three rotor blades 22. Each rotor blade 22 may be spaced about the rotor hub 20 to facilitate rotating the rotor 18 to enable kinetic energy to be transferred from the wind into usable mechanical energy, and subsequently, electrical energy. For instance, the rotor hub 20 may be rotatably coupled to an electric generator 24 (FIG. 2) positioned within the nacelle 16 to permit electrical energy to be produced.

[0026] The wind turbine 10 may also include a wind turbine controller 26 centralized within the nacelle 16. However, in other embodiments, the controller 26 may be located within any other component of the wind turbine 10 or at a location outside the wind turbine 10. Further, the controller 26 may be communicatively coupled to any number of the components of the wind turbine 10 in order to control the components. As such, the controller 26 may include a computer or other suitable processing unit. Thus, in several embodiments, the controller 26 may include suitable computer-readable instructions that, when implemented, configure the controller 26 to perform various different functions, such as receiving, transmitting and/or executing wind turbine control signals.

[0027] Referring now to FIG. 2, a simplified, internal view of the nacelle 16 of the wind turbine 10 shown in FIG. 1, particularly illustrating the drivetrain components thereof, is illustrated. More specifically, as shown, the generator 24 may be coupled to the rotor for producing electrical power from the rotational energy generated by the rotor. The rotor may be coupled to the main shaft, which is rotatable via a main bearing (not shown). The main shaft may, in turn, be rotatably coupled to a gearbox output shaft of the generator 24 through a gearbox 30. As is generally understood, the main shaft provides a low speed, high torque input to the gearbox 30 in response to rotation of the rotor blades 22 and the rotor hub 20. Thus, the gearbox 30 converts the low speed, high torque input to a high speed, low torque output to drive the gearbox output shaft and, thus, the generator 24.

[0028] Each rotor blade 22 may also include a pitch adjustment mechanism configured to rotate each rotor blade 22 about its pitch axis 28 via a pitch bearing. Similarly, the wind turbine 10 may include one or more yaw drive mechanisms communicatively coupled to the controller 26, with each yaw drive mechanism(s) being configured to change the angle of the nacelle 16 relative to the wind (e.g., by engaging a yaw bearing of the wind turbine 10).

[0029] Typically, wind turbine blades are composed of several components, such as a shell including core elements and spar elements, reinforcing elements, resin, and the like. According to some embodiments, the spar elements may include electrically conductive components. For obtaining a reliable result of the production of a wind turbine blade, in particular with a repeatable quality meeting the defined standards, the individual components of a wind turbine blade may be monitored before assembly according to some embodiments described herein. In particular, parts of the wind turbine blade, such as electrically conductive components (e.g. planks, especially carbon pultrusion planks) for forming the wind turbine blade may be inspected before assembly. As will be appreciated, several planks may be assembled to form stacks in horizontal and vertical direction to form the spar beam of a wind turbine blade, in particular a wind turbine blade shell.

[0030] The term “wind turbine blade shell” as used herein may be understood as the shell of a wind turbine blade. In particular, the shell of the wind turbine blade may be described as the outer covering of a wind turbine blade. According to some embodiments, the outer surface of shell of a wind turbine blade is exposed to wind and other environmental factors, such as the atmospheric/weather conditions. Especially, the shell of the wind turbine blade may have an aerodynamical shape, such that the blade shell enables an efficient energy yield. In some embodiments, the shell of a wind turbine blade may be adapted for withstanding load/forces acting on the wind turbine blade.

[0031] The term “plank” as used herein as an example for an electrically conductive component may be understood as a part of a wind turbine, specifically a part of a wind turbine blade, or even more specifically a part of a wind turbine blade shell. According to some embodiments, a plank as used herein may be a part of the wind turbine during production of the wind turbine and may, typically, form the wind turbine blade (especially the wind turbine blade shell) together with other parts. According to some embodiments, a plank may be a part of a material (especially an electrically conductive material), such as an elongated part of a material, a shelf, a continuous material, or a board. In some embodiments, a plank as described herein may be a pultrusion plank. Typically, a pultrusion plank as referred to herein may be a plank which is produced by pultrusion. Typically, planks may be used to be stacked for forming the spar cap or main spar or other components of a wind turbine blade shell.

[0032] In some embodiments, the electrically conductive material, or the planks (especially pultrusion planks) contain an electrically conductive material according to embodiments described herein. Typically, the electrically conductive material, or the planks (especially pultrusion planks) may include or may be made from carbon. For instance, the planks to be inspected may be carbon pultrusion planks containing a defined amount of carbon.

[0033] According to some embodiments, the component or plank may be pulled along at a certain speed, especially through the manufacturing plant, e.g. from one manufacturing station to another manufacturing station. According to some embodiments described herein, the inspection of the planks may take place during motion of the planks. Especially, the inspection of the component or plank may take place as in-line inspection during production and manufacturing of the wind turbine blade. In particular, the inspection may be performed by an array of eddy current probes.

[0034] The term “inspection” or “inspecting” as used herein may be understood in that an object, which is inspected, or which is subjected to inspection is tested, screened, checked, or scanned. In particular, the object to be inspected may be checked or tested against defined standards during inspection, and especially for deviations from defined standards. A standard against which the inspected object is checked or tested may for instance be a production guideline, a reference value, a reference image, a reference pattern, a defined threshold of values, images, or patterns, a quality standard defining a minimum of quality, and the like. According to some embodiments described herein, the inspection or inspecting may be performed by an inspection system, typically a probe device or probing device, or the like.

[0035] Fig. 3 shows an inspection system 200 for inspecting an electrically conductive component being e.g. a plank 300 used for a wind turbine blade. According to embodiments described herein, the inspection system 200 includes an eddy current array probe device 210. Typically, the eddy current array probe device 210 includes two or more electromagnetic coils acting as an eddy current probe.

[0036] The term “eddy current probe” as used herein may be understood as a probing device using inducing eddy currents in a material for probing. Typically, the eddy current probe may be adapted for probing objects, such as parts of a wind turbine, especially parts of a wind turbine blade, more especially the wind turbine blade shell, such as pultrusion planks, bondlines, or the like.

[0037] An eddy current array probe device as described herein may include at least two electromagnetic coils, especially for generating an electromagnetic field that can in particular be used to inspect the quality of the sample under test. Typically, the generated electromagnetic field induces eddy currents at least at the surface of an electrically conductive component, and especially also within the depth (i.e. subsurface) of an electrically conductive component. The eddy currents are disturbed by the presence of anomalies or defects and the disturbances to the eddy currents are picked up by the sensing devices as variations in the signal. Particularly in the case, the electrically conductive component is quite thin (i.e. the length is several times greater than the thickness, e.g. at a pultrusion plank) and/or the electrical conductivity is low compared to metallic components, the eddy currents induced by the eddy current array probe device may penetrate through the material and, especially, through the entire thickness of the electrically conductive component. Generally, the depth of penetration of the eddy currents into the material depends on the electrical conductivity of the material, the magnetic permeability and the applied excitation frequency.

[0038] According to some embodiments, which may be combined with other embodiments described herein, an eddy current array probe device as described herein may include one or more sensors, sensing devices, and/or detection devices, such as sensors, sensing devices and/or detection devices for sensing and detecting the eddy currents and the change in the electromagnetic field of the eddy current array probe device induced by the eddy currents. In some embodiments, a sensing device as described herein may include the electromagnetic coils of the eddy current array probe device. According to some embodiments, which may be combined with other embodiments described herein, the inspection system may include sensors, detection devices and/or encoders for sensing and detecting position information of the object to be inspected, attribute information of the object to be inspected (such as material information, size information, movement information and the like).

[0039] According to some embodiments, which may be combined with other embodiments described herein, the inspection system as described herein may further include an automated defect detection device including a detection algorithm for recognizing, sizing and classifying defects in the electrically conductive component based on sensed eddy currents. For instance, the detection algorithm may include the steps of detecting (e.g. by the signals of the eddy current array probe device) a defect in a component, sizing the defect (e.g. in x-, y-, or z-direction), and classifying the defect (e.g. what type of defect like wrinkles, cuts, scratches, fuzz balls etc. was detected). In some embodiments, the eddy currents may be sensed by the coils of the eddy current array probe device. Typically, automatic defect detection may be understood as a process of using technology and algorithms to automatically identify defects in the conductive component to be inspected. A variety of techniques may be used, such as computer vision, machine learning, and the like. Typically, the automatic defect detection may improve the quality control before the conductive component is used in a wind turbine blade. Also, especially, the speed and precision of defect detection is increased with automated detection compared to manual or visual inspection.

[0040] According to some embodiments, which may be combined with other embodiments described herein, the automated defect detection device including a detection algorithm is adapted to use a relative signal strength coming from the eddy current array probe device for recognizing/detecting, sizing and classifying defects in the electrically conductive component. Typically, the relative signal strength is relative compared to the background related signals from the component. For instance, the relative signal strength is relative compared to the signal strength coming from the component material without any defects. According to some embodiments, which may be combined with other embodiments described herein, the automated defect detection device including a detection algorithm is adapted to use physical attributes of the defect (such as length, width, depth, location within the component to be inspected, kind of material, but also physical attributes like cracks or wrinkles in the component to be inspected, fuzz elements or fuzz balls on the component to be inspected, and/or dents on the component to be inspected) for recognizing/detecting, sizing and classifying defects in the electrically conductive component. In some embodiments, the automated defect detection algorithm is adapted to use correlating eddy current images with visual images of the defects in the case of surface defects. According to some embodiments, an eddy current image may be an image generated based on the signals obtained by the single coils of the eddy current array probe device. For instance, each coil delivers a signal and from all signals taken together, an image of the inspected component section can be generated eventually showing the defects present. In some embodiments, images generated based on the sensed eddy currents on the component to be inspected may be compared and correlated to a visual image (taken e.g. by a camera or the like). Typically, the correlation may yield additional information of conformity, (mis- )alignment, missed defects or the like by a comparison between the images. In some embodiments, which may be combined with other embodiments described herein, the automated defect detection algorithm is adapted to use a Deep Learning (DL) model that has been trained with images generated from raw data and corresponding information on the defect type. .. Typically, the automated defect detection device including a detection algorithm may perform classification based on images and deep learning (DL) model trained with previous defects found in a test scenario, or even in a real probing situation. According to some embodiments, the automated defect detection device including a detection algorithm is adapted to use a machine learning algorithm based on training data, e.g. with real defects. In some embodiments, using training data based on real defects may include classifying real defects (either by a user or an algorithm), and linking or correlating the classified defect to the signal obtained for the defect from the eddy current array probe device. For instance, the pattern of the signal may be linked to the type of classified defect for training the algorithm. The next time, this special pattern appears, the algorithm can use the linked data for faster classifying the defect. According to some embodiments, an instrument device 400 and/or a computing device 401 (referred to in detail below) may include the machine learning algorithm for classifying the detected defects. Based on these defect classifications, threshold limits can be set as per production acceptance criterion to enhance production quality.

[0041] According to some embodiments described herein, an array probe device of at least two electromagnetic coils (also denoted as array of electromagnetic coils herein) may be understood as an arrangement of two or more electromagnetic coils. The array of electromagnetic coils may be arranged in any arbitrary shape, such as a row, a line, a set, arranged in a quadrangular shape, a triangular shape, a round shape, a polygonal shape, arranged in an irregular manner or the like. In particular, each of the electromagnetic coils in the array of electromagnetic coils may have a defined place for operation within the probe array for probing a defined probing area.

[0042] According to some embodiments, the arrangement of an array of at least two electromagnetic coils as referred to herein will depend on the width of the plank to be inspected so as to cover the width in one go and may specifically include between 2 and 100, more specifically between 2 and 80, and even more specifically between 3 and 60electromagnetic coils. In one embodiment, the number of electromagnetic coils in an array is more than 60.

[0043] Referring back to Fig. 3, the eddy current array probe device 210 of electromagnetic coils may be an array as shown in Fig. 4 in some embodiments. According to some embodiments, the probing area of the eddy current array probe device 210 may have an extension in the width direction 311 and the length direction 310 of the plank 300. According to some embodiments described herein, the probing areas of the eddy current array probe device 210 cover the (particularly entire) width 304 of the plank.

[0044] Specifically, the width 304 of the plank may be measured in a width direction 311, running substantially perpendicular to the length direction 310 of the plank. In Fig. 3, the length of a conductive component or a plank may be measured in the moving direction 305, as can be seen in the coordinate system of Fig. 3.

[0045] Fig. 4 shows an eddy current array probe device 210 having at least a first electromagnetic coil 221 and a second electromagnetic coil 222. Typically, further similar coils 220 are provided in the eddy current array probe device 210 and shown in the example of Fig. 4. In the embodiment shown in Fig. 4, the eddy current array probe device includes two rows of electromagnetic coils, in particular a first row 211 and a second row 212. According to some embodiments, which may be combined with other embodiments described herein, each single coil may have an electrical connection 240 from the coil to a control unit, especially the instrument device 400 (referred to in detail below). Typically, the electromagnetic coils of the eddy current array probe device 210 may be offset to each other in the length direction 310. For instance, two adjacent coils are shown in Fig. 4 having a length distance 232 between them. In particular, a gap 233 appears between two adjacent coils, and/or between the rows of coils being offset to each other. In some embodiments, the electromagnetic coils of the eddy current array probe device 210 may be offset to each other in the width direction 311. For instance, two adjacent coils are shown in Fig. 4 having a width distance 230 to each other. According to some embodiment, the electromagnetic coils of the eddy current array probe device 210 may be offset to each other in the width direction 311 and in the length direction 310. Typically, a probing area of an electromagnetic coil being offset to a probing area of another electromagnetic coil, respectively, may be understood in that the location of the probing area or the electromagnetic coil is shifted in one or more direction(s) with respect to the other probing area or the other electromagnetic coil (such as shifted in length direction 310, in width direction 311, or both).

[0046] According to some embodiments described herein, the eddy current array probe device 210 may be adapted for inspecting a conductive component (such as a pultrusion plank) 300 having a width 304 suitable for wind turbine components, in particular any wind turbine component having an electrically conductive component to be inspected with an eddy current array probe device. In some embodiments, the inspection system may be adapted for a conductive component or pultrusion plank having a thickness suitable for a component of a wind turbine. In some embodiments, two or more eddy current array probe devices may be used for covering the full width of a conductive component of a wind turbine. In some embodiments, the full width of a conductive component of a wind turbine may be inspected stepwise, e.g. by only one eddy current array probe device. For instance, the number of electromagnetic coils, the offset of the electromagnetic coils with respect to each other, the size of the electromagnetic coils, the kind of the electromagnetic coils, and the like may be adapted to the width or thickness of a conductive component or pultrusion plank of a wind turbine to be inspected.

[0047] According to some embodiments, which may be combined with other embodiments described herein, the eddy current array probe device may be adapted for inspecting a conductive component or a pultrusion plank including or containing carbon. In some embodiments, the eddy current array probe device may be adapted for inspecting a conductive component or a pultrusion plank including or containing a conductive material different from carbon.

[0048] According to some embodiments described herein, a control unit may be provided in the inspection system 200. The control unit may for instance include a data processing element, an image processing element, a signal-producing element, a clock element, a data storing element, and the like. In particular, the control unit may include an instrument device 400 and a computing device 401 (being e.g. a laptop or display device). Typically, the instrument device 400 may include instrument elements for driving the electromagnetic coils, for controlling operation of the electromagnetic coils, for sensing electromagnetic fields, for sensing changes in an electromagnetic field, for measuring electromagnetic fields, for measuring changes in an electromagnetic field, for detecting errors and defects in the electrically conductive component to be inspected, and the like. According to some embodiments, the instrument device 400 may be linked to the computing device 401 and may exchange information with the computing device 401. Exchanging information may relate to controlling information, operational information, processed information or data based on the sensed or measured data and the like.

[0049] According to some embodiments, with an appropriate choice of the frequency used for the eddy current array probe device, the induced eddy currents can penetrate the (especially full) thickness of the conductive component or pultrusion plank and can therefore help in the inspection of front surface and internal defects and defects on the back surface. The data obtained from sensing devices that sense changes in the eddy currents of the conductive component may be analyzed near real-time to report the length, width and depth of the defect (and classify the defects) to make a decision on whether to use the plank or scrap it. Typically, the inspection system according to embodiments described herein is able to inspect fuzz ball, splicing defects, foreign object, wrinkles, cracks and other similar defects in conductive components (such as components used for building up a wind turbine blade), e.g. carbon pultrusion planks.

[0050] Fig. 5 shows a front view of the inspection system according to embodiments described herein. Fig. 5 shows the conductive component 300 having a width 304. In some embodiments described herein, the eddy current array probe device 210 covers or is able to inspect the width 304 of the conductive component 300. Typically, the width of the array can be chosen to give complete coverage of the width of the conductive component or pultrusion plank. Fig. 5 further shows an eddy current array probe device 210 according to some embodiments. A distance 231 in height direction 312 (see coordinate system at the side of Fig. 5) is shown in Fig. 5. Typically, the distance 231 is measured from the surface of the conductive component to the nearest point or surface of the eddy current array probe device 210. The distance between the eddy current array probe device 210 and the conductive component 300 is denoted as liftoff of the eddy current array probe device to the electrically conductive component.

[0051] Typically, the eddy current array probe device may be placed with a given liftoff so as to not get worn out while inspecting the conductive component, which may, in some embodiments, mean inspecting several kilometers of the conductive component, or in heavy duty operations, such as a plank, especially at a production site.

[0052] Fig. 6 shows an embodiment of a constant-liftoff mechanism 500 of the inspection system according to embodiments described herein. Typically, the constant-liftoff mechanism 500 is adapted for maintaining a substantial constant liftoff 231 between the eddy current array probe device 210 and the electrically conductive component 300. For instance, maintaining a substantial constant liftoff may be understood that the liftoff remains or is actively kept within a defined range.

[0053] The term “substantially” or “substantial” as used herein may be understood in that there may be a deviation from the attribute denoted with “substantially.” In one example, a distance or liftoff is kept substantial constant. This may be understood in that the distance or liftoff may be within a range of typically about 15% more typically 10%, and even more typically 5% of the extension of the distance. This may mean that the deviation of the length of the distance is not greater than typically about 15% more typically 10%, and even more typically 5% of the extension of the distance. In another example, the term “substantially perpendicular” may include a deviation up to 15° from the perpendicular direction, more particularly up to 10° from the perpendicular direction, and even more particularly up to 5° from the perpendicular direction.

[0054] Generally, the constant-liftoff mechanism is adapted to reduce vibrations influencing the generation and sensing of the eddy currents in the electrically conductive component. For instance, vibrations may originate from the travel of the component to be inspected. In particular, the inspection system according to embodiments described herein may be adapted and used within a production site of a wind turbine blade during manufacturing of a blade of a wind turbine. In some embodiments, the inspection system as described herein may be used for enabling inline inspection during production and manufacturing of the wind turbine blade, or parts thereof.

[0055] According to some embodiments, which may be combined with other embodiments described herein, the inspection system 200 may be adapted to be coupled to a pultrusion plank production system. The inspection system may be used for an in-line inspection of the pultrusion plank 300 in some embodiments. Typically, the in-line inspection may for instance mean that the inspection system may be placed between two production stations or manufacturing stations at the manufacturing plant of a wind turbine blade. According to some embodiments, the inspection system as described herein may be movable for having flexibility of placing the inspection system within a manufacturing plant of a wind turbine blade. Typically, the inspection system, or at least the eddy current array probe device may be coupled to the production system of the wind turbine blade in the manufacturing plant, e.g. by being connected to the plant network or the like.

[0056] However, the in-line inspection method incorporating constant lift-off mechanism will be helpful to reduce vibrations in the conductive component arising from the motion of the component, which may in turn influence the eddy currents used for detecting errors and defects within the conductive component to be inspected. The influence of vibrations on the eddy currents may cause errors in the signal produced based on the eddy currents and may yield wrong information.

[0057] The constant-liftoff mechanism according to embodiments described herein is especially adapted to reduce vibrations originating from the movement of the electrically conductive component within the production plant. For instance, conductive components such as planks may move with a speed of about 300mm/s in the assembly line within the production plant.

[0058] According to some embodiments, which may be combined with other embodiments described herein, the constant-liftoff mechanism 500 may include at least two elements, wherein at least one of the elements of the constant- liftoff mechanism has elastic properties. In some embodiments, the elastic properties may be provided by including one or more elastic materials in the respective element, by the geometry of the element, or by a bearing of the respective element. In Fig. 6, three elements of the constant-liftoff mechanism 500 are shown. In the example of Fig. 6, the constant-liftoff mechanism 500 includes a fixture 502, a touching device 501 and an elastic element 503.

[0059] Typically, the fixture 502 is a fixture device, a support device or a holding device for the eddy current array probe device 210. As can be seen in Fig. 6, the eddy current array probe device 210 is fixed to and held by the fixture 502. The touching device 501 may especially be adapted for touching the electrically conductive component 300, especially the electrically conductive component 300 and the fixture 502 (or, in some embodiments, the eddy current array probe device 210). In some embodiments, the touching element 501 may be able to transmit vibrations (especially from the conductive component to be inspected) to the eddy current array probe device 201 and/or to the fixture 502 of the eddy current array probe device 210, e.g. by touching it. In some embodiments, the touching device 501 may include at least two rollers, beneath which the electrically conductive component 300 is passed during inspection. In Fig. 6, the conductive component 300 to be inspected passes beneath two rollers in length direction 310.

[0060] According to some embodiments, which may be combined with other embodiments described herein, the elastic element 503 may be linked to the fixture 502, or may, in some embodiments, be a part of the fixture. Typically, the elastic element 503 may be a spring. More typically, the fixture 502 may be a spring loaded fixture for the eddy current array probe device 210. In some embodiments, the elastic element 503 of the constant-liftoff mechanism may be an element that stores mechanical energy, e.g. by a respective geometry (like a coil spring), by a respectively chosen material, by applying a pre-tension to the elastic element, and the like.

[0061] Fig. 7 shows the elastic element 503 including two springs, especially coil springs. The remaining features of Fig. 7 may be similar or equal to the features shown in Fig. 6.

[0062] Vibrations of the conductive component, which can cause changes in the signal, can be avoided by locally passing the planks between rollers which are spring loaded or otherwise in order to keep constant liftoff of the probes with respect to the sample according to some embodiments described herein. Changes in the probing signal may lead to an unreliable result in the defect detection of the probing. According to some embodiments, the inspection system includes a spring- loaded roller mechanism, or another mechanism providing a defined load to the rollers, typically to keep a substantially constant liftoff of the probes with respect to the sample. Keeping the substantial constant distance between the eddy current array probe device and the sample may lead to a reliable probing and reliable probing results, which may be used for secure error detection according to some embodiments.

[0063] In some embodiments, which may be combined with other embodiments, the eddy current array probe device may be mounted on the front or top side of the plank, especially for inspecting surface and internal defects of the conductive component.

[0064] Fig. 8 shows a schematic flow chart of an inspection method 600 for inspecting an electrically conductive component of a blade for a wind turbine 10 during manufacturing. According to some embodiments described herein, which may be combined with other embodiments described herein, the electrically conductive component may move during performing the inspection method 600 according to embodiments described herein during manufacturing of the blade of a wind turbine.

[0065] According to some embodiments, which may be combined with other embodiments described herein, the inspection method may include an eddy current array probe device 210 placed in the path of the plank while it is moving from one point in the manufacturing plant to another. In some embodiments, the eddy current array probe device may be an eddy current array probe device as described in embodiments herein. For instance, the eddy current array probe device may be placed in a manufacturing plant or a production system for wind turbine blades and may especially be integrated into the production line. Typically, the inspection system may be statically placed for operation at a location, where the conductive component to be inspected passes (anyway) during the production process of the wind turbine blade. According to embodiments described herein, the inspection method as described herein may be denoted as an in-line inspection method, in particular due to its location in a production line. Typically, the inspection method according to embodiments described herein enables an inspection of the conductive components, such as a pultrusion plank, with substantially no addition to current cycle time.

[0066] In block 601, the inspection method according to embodiments described herein includes inspecting the electrically conductive component 300 by an eddy current array probe device 210 of at least two electromagnetic coils. According to some embodiments, the inspection method 600 may be performed with an inspection system according to embodiments described herein.

[0067] In block 602, the inspecting of the conductive component includes sensing by a sensor the eddy current induced by the eddy current array probe device 210 in the electrically conductive component 300 to be inspected. For instance, coils of the eddy current array probe device may be used as sensing devices for sensing the induced eddy currents, or for sensing changes in the induced eddy currents. In other embodiments, other magnetic field sensing devices like magneto resistive sensors or tunneling magneto resistive sensors (for instance a giant magneto resistive sensor) can also be used to sense the fields from the eddy currents.

[0068] In block 603, the inspecting further includes maintaining a substantial constant liftoff 231 between the eddy current array probe device 210 and the electrically conductive component 300 by a constant-liftoff mechanism 500. Especially, the constant-liftoff mechanism may be a constant-liftoff mechanism as described in embodiments above. In some embodiments, the inspection method may further include reducing vibrations influencing the generation and sensing of the eddy currents in the electrically conductive component 300 by the probe attached to the constant-liftoff mechanism 500. According to some embodiments, which may be combined with other embodiments described herein, the method includes reducing vibrations originating from the movement of the electrically conductive component 500 (e.g. within a production line).

[0069] In some embodiments, the constant-liftoff mechanism used in the inspection method according to some embodiments described herein may include at least two elements. The method may further include maintaining a substantial constant liftoff by using elastic properties of at least one of the elements of the constant- liftoff mechanism, such as the elements 501, 502, 503 of the constant- liftoff mechanism as described in embodiments above.

[0070] In some embodiments described herein, the inspection method further includes fixing the eddy current array probe device by a fixture (e.g. fixture 502 as described above). The inspection method using a fixture may further include bringing the electrically conductive component 500 in touching condition with a touching device (e.g. touching device 501 as described in embodiments above). Typically, the touching device (501) is able to transmit vibrations to the fixture of the eddy current array probe device. In some embodiments, the touching device may include one or more rollers being placed between the fixture and the conductive component to be inspected. In this way, the rollers as touching device touch both the conductive component and the fixture, and enable a relation or conjunction between the fixture for the eddy current array probe device and the component to be inspected. According to some embodiments, the inspection method further includes passing or guiding the conductive component to be inspected between at least two rollers or under at least two rollers (forming the touching device) during inspection.

[0071] According to some embodiments, which may be combined with other embodiments described herein, the inspection method as described herein may be a method to characterize the defects on or within the conductive component with length, width and depth of the defects and determine the quality of the part for deciding to let the respective part of the component pass or scrap, especially within the assembly line at a production site.

[0072] According to some embodiments, which may be combined with other embodiments described herein, the inspection method further includes automatically detecting a defect in the conductive component by recognizing, sizing and classifying a defect. Typically, the automatic defect detection may improve the quality control before the conductive component is used in a wind turbine blade. Also, especially, the speed of defect detection is increased with automated detection compared to manual or visual inspection.

[0073] In some embodiments, automatically detecting may be performed by an automated defect detection device including a detection algorithm, as for instance described in detail above. Typically, automatically detecting may include using physical attributes of the defect (such as length, width, depth, location, surface, kind of material, or the like), correlating images based on the eddy current measurement with images of visual detection (e.g. taken by a camera), especially with surface defects, classifying based on images and a trained DL model, using a machine learning algorithm based on training data or real data (e.g. performed by a machine learning tool, especially implemented on the computing device).

[0074] In some embodiments, the inspection method includes mounting the eddy current array device 210 in a production system producing the electrically conductive component 300 for the wind turbine 10 for enabling in-line inspection.

[0075] The inspection system and the inspection method according to embodiments described herein allows for a better, faster, and more robust inspection system and inspection method that may reduce costs and improve detectability of defects at the same time. The inspection method and the inspection system as described in embodiments herein is typically contactless, so that there is no liquid coupling or the like used compared to some known techniques, which makes the inspection system and inspection method according to embodiments described herein even more robust and reliable. By inspecting a component by an inspection system according to embodiments described herein or by the inspection method according to embodiments described herein, the quality of the components (such as a pultrusion plank) used for a wind turbine can be improved. The quality of the component, such as a pultrusion plank for a wind turbine blade affects the quality of the spar caps of the wind turbine blade, which ultimately affects the blade health. Current solutions often offer visual inspection, which cannot detect defects within a component. The method and system as described in embodiments herein help avoiding this problem.

[0076] Exemplary embodiments of an inspection system and an inspection method are described above in detail. The systems and methods are not limited to the specific embodiments described herein, but rather, elements of the systems and/or steps of the methods may be utilized independently and separately from other elements and/or steps described herein.

[0077] Although specific features of various embodiments of the invention may be shown in some drawings and not in others, this is for convenience only. In accordance with the principles of the invention, any feature of a drawing may be referenced and/or claimed in combination with any feature of any other drawing.

[0078] Embodiments of the present invention have been described above with reference to block diagrams and flowchart illustrations of system and methods. It will be understood that each block of the block diagrams and flowchart illustrations, and combinations of blocks in the block diagrams and flowchart illustrations, respectively, can be implemented by various means including computer program instructions. These computer program instructions may be loaded onto a general- purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions which execute on the computer or other programmable data processing apparatus create a means for implementing the functions specified in the flowchart block or blocks.

[0079] These computer program instructions may also be stored in a non- transitory computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including computer-readable instructions for implementing the function specified in the flowchart block or blocks. The computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions that execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks.

[0080] Accordingly, blocks of the block diagrams and flowchart illustrations support combinations of means for performing the specified functions, combinations of steps for performing the specified functions and program instruction means for performing the specified functions. It will also be understood that each block of the block diagrams and flowchart illustrations, and combinations of blocks in the block diagrams and flowchart illustrations, can be implemented by special purpose hardware-based computer systems that perform the specified functions or steps, or combinations of special purpose hardware and computer instructions.

[0081] Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim does not actually recite an order to be followed by its steps or it is not otherwise specifically stated in the claims or descriptions that the steps are to be limited to a specific order, it is no way intended that an order be inferred, in any respect. This holds for any possible non-express basis for interpretation, including: matters of logic with respect to arrangement of steps or operational flow; plain meaning derived from grammatical organization or punctuation; the number or type of embodiments described in the specification.

[0082] This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. While various specific embodiments have been disclosed in the foregoing, those skilled in the art will recognize that the spirit and scope of the claims allows for equally effective modifications. Especially, mutually nonexclusive features of the embodiments described above may be combined with each other. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art.

List of reference signs

10 wind turbine 233 gap

14 support surface 240 electrical connection

16 nacelle 300 conductive component

18 rotor 304 width of component

20 rotor hub 305 moving direction of

22 rotor blade component

24 electrical generator 310 length direction

26 controller of wind turbine 311 width direction

28 pitch axis 312 height direction

30 gearbox 400 instrument device

200 inspection system 401 computing device

210 eddy current array probe 420;430 further elements of device inspection system

211 1^st row of electromagnetic 500 constant-liftoff mechanism coils 501 touching device

212 2^nd row of electromagnetic 502 fixture coils 503 elastic element

220, 221, 222 eddy current probe 600 method

230 distance in width direction 601-603 blocks

231 liftoff

232 distance in length direction

Claims

CLAIMS:

1. An inspection system (200) for use during manufacturing for inspecting a moving electrically conductive component (300) of a blade for a wind turbine (10), the electrically conductive component moving during manufacturing of the blade of a wind turbine (10), the inspection system (200) comprising: an eddy current array probe device (210) having at least two electromagnetic coils

(220), wherein the at least two electromagnetic coils (220) comprise a first electromagnetic coil (221) and a second electromagnetic coil (222), wherein the first electromagnetic coil

(221) and the second electromagnetic coil (222) are offset from each other; wherein the eddy current array probe device (210) is adapted to be located with a defined liftoff (231) from the electrically conductive component (300); a sensor device for sensing eddy currents induced in the electrically conductive component (300) by the eddy current array probe device (210); and, a constant-liftoff mechanism (500) for maintaining a substantial constant liftoff (231) between the eddy current array probe device (210) and the electrically conductive component (300).

2. The inspection system of claim 1, wherein the constant- liftoff mechanism (500) is adapted to reduce vibrations influencing the generation and sensing of the eddy currents in the electrically conductive component (300), especially reduce vibrations originating from the movement of the electrically conductive component (300).

3. The inspection system according to any of the preceding claims, wherein the constant-liftoff mechanism (500) comprises at least two elements (501; 502; 503) and wherein at least one of the at least two elements (501; 502; 503) of the constant-liftoff mechanism (500) has elastic properties.

4. The inspection system according to any of the preceding claims, wherein the constant liftoff mechanism (500) comprises a fixture (502) for the eddy current array probe device (210) and a touching device (501) adapted for touching the electrically conductive component (300), wherein the touching device (501) is able to transmit vibrations to the fixture (502) of the eddy current array probe device (210).

5. The inspection system according to claim 4, wherein the touching device (501) comprises at least two rollers, under which the electrically conductive component (300) is passed during inspection; and/or wherein the fixture (502) is a spring loaded fixture (502; 503) for the eddy current array probe device (210).

6. The inspection system according to any of the preceding claims, wherein the inspection system (200) is adapted to be coupled to a production system for electrically conductive components for an in-line inspection of the electrically conductive component (300).

7. The inspection system according to any of the preceding claims, wherein the first electromagnetic coil (221) and the second electromagnetic coil (222) are offset to each other in the width direction (311) of the electrically conductive component (300) to be inspected, and/or wherein the first electromagnetic coil (221) and the electromagnetic coil (222) are offset to each other in the length direction (310) of the electrically conductive component (300) to be inspected.

8. The inspection system according to any of the preceding claims, wherein the inspection system further comprises an automated defect detection device including a detection algorithm for recognizing, sizing and classifying defects in the electrically conductive component based on the sensed eddy currents in and on the electrically conductive component.

9. The inspection system according to claim 8, wherein the automated defect detection device is adapted to use at least one of the following for detecting, sizing and classifying defects in the electrically conductive component:

- a relative signal strength of the eddy current array probe device compared to the background related signals from the component;

- physical attributes of the defect;

- correlating eddy current images with visual images of the defects in the case of surface defects;

- training a deep learning (DL) model for classifying defects in images generated from data received from the eddy current array probe device; and

- a machine learning algorithm based on training data with real defects.

10. An inspection method (600) for inspecting an electrically conductive component (300) of a blade for a wind turbine (10) during manufacturing of the blade of the wind turbine, the inspection method (600) comprising: inspecting (601), especially during movement of the electrically conductive component (300), the electrically conductive component (300) by an eddy current array probe device (210) of at least two electromagnetic coils (220; 221; 222), wherein inspecting comprises: sensing (602) by a sensor device the eddy current induced by the eddy current array probe device (210) in the electrically conductive component (300) to be inspected; and, maintaining (603) a substantial constant liftoff (231) between the eddy current array probe device (210) and the electrically conductive component (300) by a constant-liftoff mechanism (500). 1

11. The inspection method according to claim 10, further comprising reducing vibrations influencing the generation and sensing of the eddy currents in the electrically conductive component (300) by the constant-liftoff-mechanism (500), especially reducing vibrations originating from the movement of the electrically conductive component (500).

12. The inspection method according to any of claims 10 to 11, wherein the constantliftoff mechanism (500) comprises at least two elements (501; 502; 503), and wherein maintaining a substantial constant liftoff (231) comprises using elastic properties of at least one of the elements of the constant-liftoff mechanism (500).

13. The inspection method according to claim 12, further comprising: fixing the eddy current array probe device (210) by a fixture (502) being one of the at least two elements (501; 502; 503) of the constant-liftoff mechanism (500); and bringing the electrically conductive component (500) in touching condition with a touching device (501) being one of the at least two elements (501; 502; 503) of the constantliftoff mechanism (500), wherein the touching device (501) is able to transmit vibrations to the fixture (502) of the eddy current array probe device (210), in particular wherein the touching device (502) comprises at least two rollers, wherein the inspection method further comprises: passing the electrically conductive component (300) between the at least two rollers during inspection.

14. The inspection method according to any of claims 10 to 13, further comprising automatically detecting a defect in the conductive component by recognizing, sizing and classifying a defect, wherein detecting a defect in particular comprises at least one of the following:

Using physical attributes of the defect; Correlating Eddy current images with visual images of the defects in the case that the defect is on the surface of the conductive component;

Classifying the defect based on images and a trained deep learning (DL) model; and Using a machine learning algorithm based on training data.

15. Use of an inspection system according to any of claims 1 to 9 in a production system producing the electrically conductive component (300) for the wind turbine (10) for enabling in-line inspection.