Device and method for measuring static load space deformation track of wind power blade

Abstract

The invention belongs to the technical field of structural component static balance testing, and particularly relates to a wind power blade static load space deformation track measuring device and method.The wind power blade static load space deformation track measuring device comprises a test bed base, a pull rope sensor, a stereo camera, an ultra wide band distance measuring system and a data processing system, and the measuring method comprises the following steps of S1, wind power blade clamping, S2, environment building and S3, wind power blade static load space deformation track measuring. According to the method, in the aspect of three-dimensional measurement, root-mean-square errors of blade deflection variation in three directions are all controlled within a centimeter-level range, and the measurement precision and the measurement dimension are remarkably superior to those of a traditional method; the method has higher measurement precision and wider application range, can restore the deformation track of the large blade, and can analyze and optimize the blade structure, thereby improving the safety performance of the blade and the bearing capacity of the blade under extreme load conditions.

Description

Technical Field

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

[0002] In the field of wind power generation, wind turbine blades are key components that convert wind energy into mechanical energy. Their quality and performance directly determine the power generation efficiency, stability and service life of wind turbines. Full-scale structural testing of wind turbine blades is an indispensable and important link to ensure that the blades can operate smoothly and reliably during their service life of several years or even decades. Among them, deflection is the most important item in blade displacement data, and it is also one of the important data of full-scale structural testing.

[0003] The widely used draw-wire measuring equipment has obvious shortcomings. On the one hand, the measurement error is large. Due to the accuracy limitation of the draw-wire sensor itself and the susceptibility to the influence of external environmental factors during the actual measurement process, the final measured data has a large deviation from the actual deflection of the blade. On the other hand, the measurement dimension of the traditional draw-wire sensor method is single, and it can only measure the displacement change in a specific direction. It is impossible to fully obtain the three-dimensional deformation information of the blade in space, and it is difficult to meet the test requirements of modern wind turbine blades under complex structures and diversified working conditions.

[0004] In order to better meet the high-precision, multi-dimensional measurement requirements of full-scale structural tests of wind turbine blades, it is 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 errors of traditional pull-wire sensors and make up for the problem of single measurement dimension. Summary of the invention

[0005] In view of the above-mentioned 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, so as to solve the problems of large error and single measurement dimension in the prior art pull-wire sensor method.

[0006] In order 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, comprising: a test bench base, a rope sensor, a stereo camera, an ultra-wideband ranging system, and a data processing system. The ultra-wideband ranging system includes a tag and a positioning base station. The tag forms a clear contrast with the surface color of the wind turbine blade and can be clearly identified 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 space deformation trajectory of a wind turbine blade based on the above-mentioned device for measuring the static load space deformation trajectory of a wind turbine blade is characterized in that it comprises the following steps: S1. Clamp the wind turbine blades, fix the blades to the test bench base, and fix the positioning base station to the ground through the bracket; S2. Environment construction. The measurement environment construction includes the following steps: S2-1. Arrange tags. Tags are evenly installed in the tip area of ​​the wind turbine blades to track the movement trajectory of the blades. S2-2, constructing a three-dimensional control field, placing tags within the test area, and forming a three-dimensional control field with the tags placed on the blades; S2-3, arranging the pull rope sensor, determining the position of the pull rope sensor, and connecting the pull rope sensor to the wind turbine blade; S2-4, calibration and arrangement of stereo cameras, calibrating the stereo cameras based on the three-dimensional control field, adjusting the stereo camera posture 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 the ultra-wideband ranging system to collect the deformation data of the wind turbine blades after static loading, using the stereo camera to collect the image data of the deformation of the wind turbine blades after static loading, and transmitting the collected data to the data processing system through the USB interface; S5. Data processing and result display: After receiving the transmitted data, the data processing system uses the spatial tetrahedron algorithm to perform calculations and analysis on the deformation trajectory data collected by the ultra-wideband ranging system, and optimizes and compares the data with the rope sensor data to determine the consistency of the deflection change. The image data collected by the stereo camera is solved to obtain the deformation data of the wind turbine blade, and the obtained data is displayed through the human-machine monitoring interface.

[0008] Further, when installing tags in S2-1, the tags are installed every 1 ~ One tag is installed for every 1.5m.

[0009] Furthermore, when performing stereo camera calibration and posture adjustment in S2-4, the pixel coordinates in the image data are used as image coordinates, and the three-dimensional coordinates of the labels in the three-dimensional control field obtained by the positioning base station are used as object coordinates, which are used to solve the internal orientation elements, external orientation elements and distortion parameters of each stereo camera.

[0010] Furthermore, after the stereo cameras are calibrated and the postures are adjusted, each marking point can be photographed by at least two stereo cameras.

[0011] Furthermore, the ultra-wideband ranging system in S4 uses the TH-PPM method to modulate the Scholtz pulse ultra-wideband signal for measurement.

[0012] Furthermore, the TH-PPM method is expressed as: ,

[0013] 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.

[0014] Furthermore, the Scholtz pulse ultra-wideband signal expression is: ,

[0015] Where α is the Gaussian pulse shaping factor.

[0016] Furthermore, 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 in real time, and the expression is: ,

[0017] Where, J represents the number of pulses; d j Take ±1; T s represents the pulse period; n(t) represents Gaussian white noise; Represents a single pulse periodic signal, and its expression is: ,

[0018] in, L Indicates the number of multipath channels; Indicates gain; Indicates delay; (t) represents the basic pulse waveform.

[0019] Furthermore, the specific steps of calculating the image data in S5 are: S5-1, performing a circle detection on the acquired image data to determine the area where the center point of the label 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.

[0020] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention discloses a device and method for measuring the static load spatial deformation trajectory of a wind turbine blade. In terms of three-dimensional measurement, the root mean square error of the blade deflection change in three directions is controlled within the centimeter range, which meets the accuracy requirements of the wind turbine blade static test outline. It is significantly superior to traditional methods in terms of measurement accuracy and measurement dimension, and has higher measurement accuracy and a wider range of applications.

[0021] 2. The present invention discloses a device and method for measuring the static load spatial deformation trajectory of a wind turbine blade, which 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 load-bearing capacity under extreme load conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of the structure of a device for measuring the static load spatial deformation trajectory of a wind turbine blade.

[0023] The reference numerals involved in the accompanying drawings are: 1. Test bench base; 2. Rope sensor; 3. Stereo camera; 5. Data processing system; 41. Tag; 42. Positioning base station. DETAILED DESCRIPTION

[0024] In order to enable those skilled in the art to better understand the present invention, the technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0025] In the description of the present application, it should be noted that directional words, such as the terms "center", "lateral", "longitudinal", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", etc., indicating directions and positional relationships are based on the directions or positional relationships shown in the accompanying drawings, which are only for the convenience of narrating the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and cannot be understood as limiting the specific scope of protection of the present application.

[0026] 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 are not necessarily used to describe a specific order or sequence.

[0027] Embodiment 1: A device for measuring the static load spatial deformation trajectory of a wind turbine blade comprises: a test bench base 1 for fixing the wind turbine blade, a pull rope sensor 2, a stereo camera 3 for collecting image data, an ultra-wideband ranging system for collecting deformation trajectory data, and a data processing system 5 for processing calculations and displaying data.

[0028] 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 clear contrast with the surface color of the wind turbine blade and can be clearly identified by the stereo camera 3 under different lighting conditions.

[0029] The data processing system 5 is also provided with a human-machine monitoring interface, which can display data in real time.

[0030] Embodiment 2: This embodiment is a method for measuring the static load space deformation trajectory of a wind turbine blade based on the device for measuring the static load space deformation trajectory of a wind turbine blade in Embodiment 1, and comprises the following steps: S1. Clamp the wind turbine blades, fix the blades to the test bench base 1, and fix the positioning base station 42 to the ground through a bracket; S2. Environment construction. The measurement environment construction includes the following steps: S2-1, arranging tags 41, the blade tip area of ​​the wind turbine blade is evenly installed with tags 41, so as to track the movement trajectory of the blade. Specifically, every 1 ~ One tag 41 is installed every 1.5 m, and preferably, one tag 41 is installed every 1-1.5 m. In this embodiment, 10 tags 41 are installed at a spacing of 1.5 m in the tip area of ​​the wind turbine blade, and the distances of the tags 41 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, and 45.0 m.

[0031] 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.

[0032] S2-3, layout of the pull-wire sensor 2, determine the position of the pull-wire sensor 2, and connect the pull-wire sensor 2 to the wind turbine blade. In this embodiment, the pull-wire sensor 2 is installed at three locations: blade tip 58.5 m, middle 30.0 m, blade root 1.5 m, sensor range: 0~2500 mm, linear accuracy ±0.1% FS.

[0033] S2-4, calibration and arrangement of stereo camera 3, calibrate stereo camera 3 based on three-dimensional control field, adjust the posture of stereo camera 3 for subsequent precise processing of image data, specifically, use pixel coordinates in image data as image coordinates, and use positioning base station 42 to obtain three-dimensional coordinates of tag 41 in three-dimensional control field as object coordinates, which are used to solve the internal orientation elements, external orientation elements and distortion parameters of each stereo camera 3. S3, static direction setting and loading, in the horizontal plane, take the blade axis as X direction, perpendicular to X direction as Y direction, and vertical direction as Z direction, and perform Z-direction static loading on the blade. S4, data acquisition and transmission, use ultra-wideband ranging system to collect deformation data of wind turbine blade after static loading, use stereo camera 3 to collect image data of deformation of wind turbine blade after static load, and transmit the collected data to data processing system 5 through USB interface.

[0034] In this embodiment: TH-PPM modulation parameters: ; Scholtz pulse shaping factor: ; TOA multipath suppression ratio: .

[0035] Ranging error verification S5. Data processing and result display. After receiving the transmitted data, the data processing system 5 uses the spatial tetrahedron algorithm to perform calculations and analysis on the deformation trajectory data collected by the ultra-wideband ranging system, and optimizes and compares the data with the data of the rope sensor 2 to determine the consistency of the deflection change. The image data collected by the stereo camera 3 is solved to obtain the deformation data of the wind turbine blade, and the obtained data is displayed through the human-machine monitoring interface.

[0036] It should be noted that the specific steps of calculating the image data are: S5-1, performing a circle detection on the acquired image data to determine the area where the center point of the tag 41 is located.

[0037] The detection method adopts the improved Hough transform method, and realizes the circular ring positioning of the label 41 by voting the edge gradient direction and the circle parameter space. The improved Hough transform method is a prior art and will not be described in detail 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.

[0038] S5-2, using a corner detection algorithm to extract the image-side coordinates of a unique center point from the region.

[0039] Specifically, the expression is: ,

[0040] in, , is the eigenvalue of the grayscale covariance matrix of the local window of the image.

[0041] S5-3, further optimizing the image-side coordinates of the center point using a refined corner point function to improve coordinate accuracy.

[0042] Specifically, the bilinear interpolation method is used to perform sub-pixel optimization on the neighborhood of the candidate corner points, and its objective function is: ,

[0043] in, I is the actual image grayscale, T It is an ideal corner template.

[0044] It should be noted that, in this embodiment, the maximum number of iterations is 10, the displacement convergence threshold is 0.01 pixel, and the process is terminated when the displacement difference between two consecutive iterations is less than this value.

[0045] 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.

[0046] Specifically, suppose the projection matrices of the two stereo cameras 3 are , , its internal parameter matrix K , the extrinsic rotation matrix R and translation vector T have been obtained through calibration.

[0047] The optimized image coordinates and , construct the homogeneous equation: ,

[0048] Solve the object coordinates by the least squares method It should be noted that, after the stereo cameras 3 are calibrated and the posture is adjusted, each marking point can be photographed by at least two stereo cameras 3 .

[0049] In this embodiment, the deformation consistency comparison It should be noted that the ultra-wideband ranging system in S4 uses the TH-PPM method to modulate the Scholtz pulse ultra-wideband signal for measurement.

[0050] Specifically, the TH-PPM method is expressed as: ,

[0051] Where ƒ(t) is the waveform of the pulse; Tƒ 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.

[0052] Specifically, the Scholtz pulse ultra-wideband signal expression is: ,

[0053] Where α is the Gaussian pulse shaping factor.

[0054] It should be noted that the ultra-wideband ranging system in S4 uses a TOA estimation algorithm to obtain high-precision distance data between the positioning base station 42 and the tag 41 in real time, and the expression is: ,

[0055] Where, J represents the number of pulses; d j Take ±1; T s represents the pulse period; n(t) represents Gaussian white noise; Represents a single pulse periodic signal, and its expression is:

[0056] in, L Indicates the number of multipath channels; Indicates gain; Indicates delay; (t) represents the basic pulse waveform.

[0057] The above is only an embodiment of the present invention. The common sense such as the known specific structure and characteristics in the scheme is not described in detail here. The ordinary technicians in the relevant field are aware of all the common technical knowledge in the technical field of the invention before the application date or priority date, can obtain all the existing technologies in the field, and have the ability to apply the conventional experimental means before that date. The ordinary technicians in the relevant field can improve and implement the scheme in combination with their own abilities under the enlightenment given by this application. Some typical known structures or known methods should not become obstacles for the ordinary technicians in the relevant field to implement this application. It should be pointed out that for the technicians in this field, without departing from the structure of the present invention, several deformations and improvements can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent.

Claims

1. A device for measuring the static load spatial deformation trajectory of a wind turbine blade, characterized in that: include: 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 includes 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.

2. A method for measuring the static load space deformation trajectory of a wind turbine blade based on the device for measuring the static load space deformation trajectory of a wind turbine blade according to claim 1, characterized in that: The following steps are involved: 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.

3. The method for measuring the static load spatial deformation trajectory of a wind turbine blade according to claim 2, 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.

4. The method for measuring the static load spatial deformation trajectory of a wind turbine blade according to claim 2, 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).

5. The method for measuring the static load spatial deformation trajectory of a wind turbine blade according to claim 4, 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).

6. A method for measuring the static load spatial deformation trajectory of a wind turbine blade according to claim 2, 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.

7. A method for measuring the static load spatial deformation trajectory of a wind turbine blade according to claim 6, 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.

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

9. A method for measuring the static load spatial deformation trajectory of a wind turbine blade according to claim 8, 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; Represents a single pulse periodic signal, and its expression is: ， in, L Indicates the number of multipath channels; Indicates gain; Indicates delay; (t) represents the basic pulse waveform.

10. The method for measuring the static load spatial deformation trajectory of a wind turbine blade according to claim 2, 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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