Device and method for measuring static load spatial deformation trajectory of wind turbine blade

Abstract

The present invention belongs to the technical field of static balance testing of structural components, and specifically relates to a device and method for measuring the static load spatial deformation trajectory of a wind turbine blade, including: a test bench base, a wire rope sensor, a stereo camera, an ultra-wideband ranging system, and a data processing system. The measurement method includes the following steps: S1. Clamping the wind turbine blade; S2. Building the environment; S3. Setting and applying the static force direction; S4. Data acquisition and transmission; S5. Data processing and result display. In three-dimensional measurement, the root mean square error of the blade deflection change in the three directions of the present invention is controlled within the centimeter level, which is significantly better than the traditional method in terms of measurement accuracy and measurement dimension, and has higher measurement accuracy and a wider application range. At the same time, the present invention can restore the deformation trajectory of large blades, and can analyze and optimize the blade structure, thereby improving the safety performance of the blade and its bearing capacity under extreme load conditions.

Description

Technical Field

[0001] The present invention belongs to the technical field of static balance testing of structural components, and particularly relates to a device and method for measuring the static load spatial deformation trajectory of a wind turbine blade. Background Art

[0002] In the field of wind power generation, as a key component for converting wind energy into mechanical energy, the quality and performance of wind turbine blades directly determine the power generation efficiency, stability, and service life of wind turbine generators. The full-scale structural test of wind turbine blades is an essential and indispensable important link to ensure the stable and reliable operation of the blades during a service cycle of up to several years or even decades. Among them, deflection is one of the most important items in the blade displacement data and is also one of the important data for full-scale structural tests.

[0003] Currently, the widely used wire-pulling measurement equipment has obvious shortcomings. On the one hand, the measurement error is large. Due to the accuracy limitation of the wire-pulling sensor itself and the easy influence of external environmental factors during the actual measurement process, there is a large deviation between the finally measured data and the actual deflection of the blade. On the other hand, the measurement dimension of the traditional wire-pulling sensor method is single, and it can only measure the displacement change in a specific direction, unable to comprehensively obtain the three-dimensional deformation information of the blade in space, and it is difficult to meet the test requirements under the complex structure and diverse working conditions of modern wind turbine blades.

[0004] In order to better meet the high-precision and multi-dimensional measurement requirements of the full-scale structural test of wind turbine blades, it is very necessary to study a device and method for measuring the static load spatial deformation trajectory of wind turbine blades that can effectively overcome the large error of the traditional wire-pulling sensor and make up for the single measurement dimension problem. Summary of the Invention

[0005] In view of the above deficiencies in the prior art, the present invention provides a device and method for measuring the static load spatial deformation trajectory of a wind turbine blade to solve the problems of large error and single measurement dimension of the existing wire-pulling sensor method.

[0006] To solve the above technical problems, the present invention adopts the following technical solutions: A device for measuring the static load spatial deformation trajectory of a wind turbine blade includes: a test bench base, a wire-pulling sensor, a stereo camera, an ultra-wideband ranging system, and a data processing system. The ultra-wideband ranging system includes tags and positioning base stations. The tags form a distinct contrast with the surface color of the wind turbine blade and can be clearly recognized by the stereo camera under different lighting conditions. The data processing system is also provided with a human-machine monitoring interface.

[0007] A method for measuring the static load spatial deformation trajectory of a wind turbine blade based on the above device for measuring the static load spatial deformation trajectory of a wind turbine blade is characterized in that it includes the following steps:

[0008] S1. Clamping of the wind turbine blade, fixing the blade to the test bench base, and fixing the positioning base station to the ground through a bracket;

[0009] S2. Environment construction, the measurement environment construction includes the following steps:

[0010] S2-1. Arrangement of labels, uniformly installing labels in the tip region of the wind turbine blade for tracking the movement trajectory of the blade;

[0011] S2-2. Construction of a three-dimensional control field, arranging labels within the test area range and forming a three-dimensional control field with the labels arranged on the blade;

[0012] S2-3. Arrangement of the cable tension sensor, determining the position of the cable tension sensor and connecting the cable tension sensor to the wind turbine blade;

[0013] S2-4. Calibration and arrangement of the stereo camera, calibrating the stereo camera based on the three-dimensional control field and adjusting the attitude of the stereo camera for precise processing of subsequent image data;

[0014] S3. Static direction setting and loading, in the horizontal plane, taking the blade axis as the X direction, the direction perpendicular to the X direction as the Y direction, and the vertical direction as the Z direction, and applying a static load in the Z direction to the blade;

[0015] S4. Data acquisition and transmission, using the ultra-wideband ranging system to acquire the deformation data of the wind turbine blade after static loading, using the stereo camera to acquire the image data of the deformation of the wind turbine blade after static load, and transmitting the acquired data to the data processing system through the USB interface;

[0016] S5. Data processing and result display, after the data processing system receives the transmitted data, performing arithmetic analysis on the deformation trajectory data acquired by the ultra-wideband ranging system through the spatial tetrahedron algorithm, and optimizing and comparing the data with the data of the cable tension sensor to determine the consistency of the deflection change, performing calculation on the image data acquired by the stereo camera to obtain the deformation amount data of the wind turbine blade, and displaying the obtained data through the human-machine monitoring interface.

[0017] Further, when installing the labels in S2-1, install 1 label every 1 ~ 1.5 m in the tip region of the wind turbine blade.

[0018] Further, when calibrating and adjusting the attitude of the stereo camera in S2-4, taking the pixel coordinates in the image data as the image-side coordinates and taking the three-dimensional coordinates of the labels obtained by the positioning base station in the three-dimensional control field as the object-side coordinates for solving the internal orientation elements, external orientation elements, and distortion parameters of each stereo camera.

[0019] Furthermore, after the calibration and attitude adjustment of the stereo camera, each marked point can be captured by at least two stereo cameras.

[0020] Furthermore, in S4, the ultra-wideband ranging system measures by modulating Scholtz's pulsed ultra-wideband signal using the TH-PPM method.

[0021] Even further, the expression of the TH-PPM method is:

[0022] ,

[0023] where ƒ(t) is the waveform of the pulse;

[0024] T ƒ is the pulse frame length;

[0025] C i is the i-th symbol;

[0026] t h is the unit time delay controlled by the time-hopping code;

[0027] t d is the pulse time delay controlled;

[0028] , and is the data symbol index.

[0029] Even further, the expression of Scholtz's pulsed ultra-wideband signal is:

[0030] ,

[0031] where α is the Gaussian pulse shaping factor.

[0032] Even further, in S4, the ultra-wideband ranging system uses the TOA estimation algorithm to obtain high-precision distance data between the base station and the tag in real time, and the expression is:

[0033] ,

[0034] where J represents the number of pulses;

[0035] d j takes ±1;

[0036] T s represents the pulse period;

[0037] n(t) represents Gaussian white noise;

[0038] represents a single pulse period signal, and its expression is:

[0039] ,

[0040] where,L Indicates the number of multipath channels;

[0041] Indicates the gain;

[0042] Indicates the time delay;

[0043] (t) represents the basic pulse waveform.

[0044] Furthermore, the specific steps for resolving the image data in S5 are as follows:

[0045] S5-1, perform circular detection on the acquired image data to determine the area where the center point of the label is located;

[0046] S5-2, adopt a corner detection algorithm to extract the unique center point image plane coordinates from the said area;

[0047] S5-3, further optimize the center point image plane coordinates by using a refined corner function to improve the coordinate accuracy;

[0048] S5-4, through the forward intersection algorithm, convert the optimized center point image plane coordinates into actual three-dimensional coordinates, complete the spatial position resolution, and then perform operation and analysis to obtain the deformation data.

[0049] Compared with the prior art, the present invention has the following beneficial effects:

[0050] 1. A static load spatial deformation trajectory measurement device and method for a wind turbine blade disclosed by the present invention, in terms of three-dimensional measurement, the root mean square error of the blade deflection change in three directions is controlled within the centimeter level, meeting the accuracy requirements of the static test outline of the wind turbine blade, and is significantly superior to the traditional method in terms of measurement accuracy and measurement dimension, with higher measurement accuracy and a wider application range.

[0051] 2. A static load spatial deformation trajectory measurement device and method for a wind turbine blade disclosed by the present invention can restore the deformation trajectory of a large blade. Through this method, the blade structure can be analyzed and optimized, thereby improving the safety performance of the blade and its bearing capacity under extreme load conditions. Description of the Drawings

[0052] Figure 1 It is a structural schematic diagram of a static load spatial deformation trajectory measurement device for a wind turbine blade.

[0053] The reference numerals involved in the drawings are as follows:

[0054] 1. Test bench base; 2. Tension rope sensor, 3. Stereo camera; 5. Data processing system; 41. Label; 42. Positioning base station. Detailed Embodiments

[0055] To enable those skilled in the art to better understand the present invention, the technical solution of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0056] In the description of the present application, it should be noted that for orientation terms, if there are terms such as "center", "horizontal", "longitudinal", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicating the orientation and position relationship is based on the orientation or position relationship shown in the accompanying drawings. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and should not be construed as limiting the specific protection scope of the present application.

[0057] It should be noted that the terms "first", "second", etc. in the description and claims of the present application are used to distinguish similar objects and do not necessarily need to describe a specific order or sequence.

[0058] Embodiment 1: A device for measuring the static load spatial deformation trajectory of a wind turbine blade, comprising: a test bench base 1 for fixing the wind turbine blade, a cable tension sensor 2, a stereo camera 3 for collecting image data, an ultra-wideband ranging system for collecting the deformation trajectory data, and a data processing system 5 for processing operations and displaying data.

[0059] The ultra-wideband ranging system includes a tag 41 and a positioning base station 42. It should be noted that the tag 41 forms a distinct contrast with the surface color of the wind turbine blade and can be clearly recognized by the stereo camera 3 under different lighting conditions.

[0060] The data processing system 5 is also provided with a human-machine monitoring interface, and the human-machine monitoring interface can display data in real time.

[0061] Embodiment 2: This embodiment is a method for measuring the static load spatial deformation trajectory of a wind turbine blade based on the device for measuring the static load spatial deformation trajectory of a wind turbine blade in Embodiment 1, comprising the following steps:

[0062] S1. Clamp the wind turbine blade, fix the blade on the test bench base 1, and fix the positioning base station 42 on the ground through a bracket;

[0063] S2. Environment construction, the measurement environment construction includes the following steps:

[0064] S2-1. Arrange the tags 41, evenly install the tags 41 in the tip region of the wind turbine blade for tracking the movement trajectory of the blade. Specifically, in the tip region of the wind turbine blade, every 1 ~Install one tag 41 every 1.5 m. Preferably, install one tag 41 every 1 - 1.5 m. In this embodiment, install 10 tags 41 at intervals of 1.5 m in the tip region of the wind turbine blade. The distances of the tag 41 positions from the blade root are: 58.5 m, 57.0 m, 55.5 m, 54.0 m, 52.5 m, 51.0 m, 49.5 m, 48.0 m, 46.5 m, 45.0 m.

[0065] S2 - 2. Construct a three - dimensional control field. Layout tags 41 within the test area and form a three - dimensional control field with the tags 41 arranged on the blade.

[0066] S2 - 3. Arrange the draw - wire sensor 2. Determine the position of the draw - wire sensor 2 and connect the draw - wire sensor 2 to the wind turbine blade. In this embodiment, the installation positions of the draw - wire sensor 2 are: 58.5 m at the tip, 30.0 m in the middle, and 1.5 m at the root, a total of 3. The sensor range is 0 - 2500 mm, and the linear accuracy is ±0.1% FS.

[0067] S2 - 4. Calibration and arrangement of the stereo camera 3. Calibrate the stereo camera 3 based on the three - dimensional control field and adjust the attitude of the stereo camera 3 for subsequent precise processing of image data. Specifically, take the pixel coordinates in the image data as the image - side coordinates, and take the three - dimensional coordinates of the tag 41 in the three - dimensional control field obtained by the positioning base station 42 as the object - side coordinates to solve the internal orientation elements, external orientation elements, and distortion parameters of each stereo camera 3. S3. Set the static force direction and apply load. In the horizontal plane, take the blade axis as the X - direction, the direction perpendicular to the X - direction as the Y - direction, and the vertical direction as the Z - direction, and apply a static load in the Z - direction to the blade. S4. Data acquisition and transmission. Use the ultra - wideband ranging system to collect the deformation data of the wind turbine blade after static load, use the stereo camera 3 to collect the image data of the deformation of the wind turbine blade after static load, and transmit the collected data to the data processing system 5 through the USB interface.

[0068] In this embodiment:

[0069] TH - PPM modulation parameter: ;

[0070] Scholtz pulse - shaping factor: ;

[0071] TOA multipath suppression ratio: .

[0072] Range - finding error verification

[0073] S5. Data processing and result display. After receiving the transmitted data, the data processing system 5 performs arithmetic analysis on the deformation trajectory data collected by the ultra-wideband ranging system through the spatial tetrahedron algorithm, and optimally compares the data with the data of the draw-wire sensor 2 to determine the consistency of deflection changes. It solves the image data collected by the stereo camera 3 to obtain the deformation amount data of the wind turbine blade, and displays the obtained data through the human-machine monitoring interface.

[0074] It should be noted that the specific steps for solving the image data are as follows:

[0075] S5-1. Perform circular ring detection on the obtained image data to determine the area where the center point of the label 41 is located.

[0076] The detection method uses the improved Hough transform method to achieve the circular ring positioning of the label 41 through the edge gradient direction and the circular parameter space voting. The improved Hough transform method is an existing technology and will not be elaborated here. In this embodiment, the minimum circle radius is 10 pixels, the maximum circle radius is 30 pixels, the gradient threshold is 100, and the accumulator resolution is 2.

[0077] S5-2. Adopt the corner detection algorithm to extract the unique center point image coordinate from the said area.

[0078] Specifically, its expression is:

[0079] ,

[0080] where, , are the eigenvalues of the gray covariance matrix of the local image window.

[0081] S5-3. Use the refined corner function to further optimize the center point image coordinate to improve the coordinate accuracy.

[0082] Specifically, use the bilinear interpolation method to perform sub-pixel level optimization on the candidate corner neighborhood, and its objective function is:

[0083] ,

[0084] where, I is the actual image gray level, T is the ideal corner template.

[0085] It should be noted that in this embodiment, the maximum number of iterations is 10 times, and the displacement convergence threshold is 0.01 pixel. When the displacement difference between two consecutive iterations is less than this value, it terminates.

[0086] S5-4. Through the forward intersection algorithm, convert the optimized center point image coordinate into the actual three-dimensional coordinate, complete the spatial position solution, and then perform arithmetic analysis to obtain the deformation amount data.

[0087] Specifically, let the projection matrices of the two stereo cameras 3 be , , and its internal parameter matrix K . The external parameter rotation matrix R and translation vector T have been obtained through calibration.

[0088] For the optimized image-side coordinates and , construct a homogeneous equation:

[0089] ,

[0090] Solve the object-side coordinates by the least squares method. It should be noted that after the stereo camera 3 is calibrated and its attitude is adjusted, each marker point can be captured by at least two stereo cameras 3.

[0091] In this embodiment, for the comparison of the consistency of the deformation amount

[0092] It should be noted that in S4, the ultra-wideband ranging system measures by modulating the Scholtz's pulsed ultra-wideband signal in the TH-PPM mode.

[0093] Specifically, the expression of the TH-PPM mode is:

[0094] ,

[0095] where ƒ(t) is the waveform of the pulse;

[0096] T ƒ is the pulse frame length;

[0097] C i is the i-th symbol;

[0098] t h is the unit time delay controlled by the time-hopping code;

[0099] t d is the pulse time delay controlled by;

[0100] , and is the data symbol index.

[0101] Specifically, the expression of the Scholtz's pulsed ultra-wideband signal is:

[0102] ,

[0103] where α is the Gaussian pulse shaping factor.

[0104] It should be noted that the ultra-wideband ranging system in S4 uses the TOA estimation algorithm to obtain high-precision distance data between the positioning base station 42 and the tag 41 in real time. The expression is as follows:

[0105] ,

[0106] where J represents the number of pulses;

[0107] d j takes ±1;

[0108] T s represents the pulse period;

[0109] n(t) represents Gaussian white noise;

[0110] represents a single pulse period signal, and its expression is:

[0111]

[0112] where L represents the number of multipath channels;

[0113] represents the gain;

[0114] represents the time delay;

[0115] (t) represents the basic pulse waveform.

[0116] The above are only the embodiments of the present invention. Common knowledge such as specific structures and characteristics in the solution is not described in detail here. Those of ordinary skill in the art know all the common general technical knowledge in the technical field to which the invention belongs before the application date or the priority date, can know all the existing technologies in this field, and have the ability to apply the conventional experimental means before this date. Those of ordinary skill in the art can, under the inspiration given in this application, combine their own abilities to improve and implement this solution. Some typical well-known structures or well-known methods should not become an obstacle for those of ordinary skill in the art to implement this application. It should be pointed out that for those skilled in the art, without departing from the structure of the present invention, several deformations and improvements can still be made, and these should also be regarded as the protection scope of the present invention, and these will not affect the implementation effect of the present invention and the practicality of the patent.

Claims

1. A method for measuring the static load spatial deformation trajectory of a wind turbine blade, characterized in that: The method is based on a device for measuring the static load spatial deformation trajectory of a wind turbine blade. The device comprises: a test bench base (1), a pull rope sensor (2), a stereo camera (3), an ultra-wideband distance measurement system, and a data processing system (5). The ultra-wideband distance measurement system comprises a tag (41) and a positioning base station (42). The tag (41) forms a clear contrast with the color of the surface of the wind turbine blade and can be clearly identified by the stereo camera (3) under different lighting conditions. The data processing system (5) is also provided with a human-machine monitoring interface. The method comprises the following steps: S1, clamping a wind turbine blade, fixing the blade to a test bench base (1), and fixing a positioning base station (42) to the ground via a bracket; S2. Environment construction. The measurement environment construction includes the following steps: S2-1, arranging tags (41), tags (41) are evenly installed in the tip area of ​​the wind turbine blade to track the movement trajectory of the blade; S2-2, constructing a three-dimensional control field, placing tags (41) within the test area, and forming a three-dimensional control field with the tags (41) placed on the blades; S2-3, arranging the pull rope sensor (2), determining the position of the pull rope sensor (2), and connecting the pull rope sensor to the wind turbine blade; S2-4, calibration and arrangement of the stereo camera (3), calibrating the stereo camera (3) based on the three-dimensional control field, adjusting the posture of the stereo camera (3) for subsequent accurate processing of image data; S3, static force direction setting and loading, in the horizontal plane, with the blade axis as the X direction, the perpendicular direction to the X direction as the Y direction, and the vertical direction as the Z direction, the blade is subjected to Z-direction static loading; S4, data collection and transmission, using an ultra-wideband ranging system to collect deformation trajectory data of the wind turbine blade after static loading, using a stereo camera (3) to collect image data of the wind turbine blade deformation after static loading, and transmitting the collected data to a data processing system (5) via a USB interface; S5. Data processing and result display. After receiving the transmitted data, the data processing system (5) performs calculation and analysis on the deformation trajectory data collected by the ultra-wideband ranging system through the spatial tetrahedron algorithm, optimizes and compares the data with the data of the pull-wire sensor (2) to determine the consistency of the deflection change, and solves the image data collected by the stereo camera (3) to obtain the deformation data of the wind turbine blade, and displays the obtained data through the human-machine monitoring interface.

2. The method for measuring the static load spatial deformation trajectory of a wind turbine blade according to claim 1, characterized in that: When the tag (41) is installed in S2-1, the tag (41) is installed at the tip of the wind turbine blade every 1 ~ 1 label (41) is installed for every 1.5m.

3. The method for measuring the static load spatial deformation trajectory of a wind turbine blade according to claim 1, characterized in that: In the S2-4, when the stereo camera (3) is calibrated and the posture is adjusted, the pixel coordinates in the image data are used as the image coordinates, and the three-dimensional coordinates of the tag (41) in the three-dimensional control field obtained by the positioning base station (42) are used as the object coordinates, which are used to solve the internal orientation elements, external orientation elements and distortion parameters of each stereo camera (3).

4. A method for measuring the static load spatial deformation trajectory of a wind turbine blade according to claim 3, characterized in that: After the stereo cameras (3) are calibrated and their postures are adjusted, each marking point can be photographed by at least two stereo cameras (3).

5. The method for measuring the static load spatial deformation trajectory of a wind turbine blade according to claim 1, characterized in that: The ultra-wideband ranging system in S4 uses the TH-PPM method to modulate the Scholtz pulse ultra-wideband signal for measurement.

6. A method for measuring the static load spatial deformation trajectory of a wind turbine blade according to claim 5, characterized in that: The TH-PPM method is expressed as: ， Where ƒ(t) is the waveform of the pulse; T ƒ is the pulse frame length; C i is the i-th code element; t h is the unit delay controlled by time-hopping code; t d for Controlled pulse delay; , is the data symbol index.

7. A method for measuring the static load spatial deformation trajectory of a wind turbine blade according to claim 6, characterized in that: The Scholtz pulse ultra-wideband signal expression is: ， Where α is the Gaussian pulse shaping factor.

8. The method for measuring the static load spatial deformation trajectory of a wind turbine blade according to claim 7, characterized in that: The ultra-wideband ranging system in S4 uses a TOA estimation algorithm to obtain high-precision distance data between the base station and the tag (41) in real time, and the expression is: ， Where, J represents the number of pulses; d j Take ±1; T s represents the pulse period; n(t) represents Gaussian white noise; w (t) represents a single pulse period signal, and its expression is: ， in, L Indicates the number of multipath channels; Indicates gain; Indicates delay; (t) represents the basic pulse waveform.

9. The method for measuring the static load spatial deformation trajectory of a wind turbine blade according to claim 1, characterized in that: The specific steps of calculating the image data in S5 are: S5-1, performing a ring detection on the acquired image data to determine the area where the center point of the tag (41) is located; S5-2, using a corner detection algorithm to extract the image coordinates of a unique center point from the region; S5-3, further optimizing the image-side coordinates of the center point using a refined corner point function to improve coordinate accuracy; S5-4, through the forward intersection algorithm, the optimized center point image coordinates are converted into actual three-dimensional coordinates, the spatial position is solved, and then the deformation data is obtained by calculation and analysis.

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