Ultrasonic scanning and three-dimensional imaging method, device and equipment for extra-high voltage transformer wire outlet device

Abstract

The invention provides an ultrasonic scanning and three-dimensional imaging method, device and equipment for an extra-high voltage transformer wire outlet device, and belongs to the technical field of extra-high voltage transformer ultrasonic detection. A PC (Personal Computer) upper computer accurately controls a scanning device to collect array ultrasonic scanning data of a target area; mapping the acquired ultrasonic echo data into a three-dimensional coordinate of a real structure through a three-dimensional image texture technology, performing color and transparency mapping according to an ultrasonic echo amplitude, and reconstructing a three-dimensional image in the wire outlet device; through linear gain setting in the scanning direction, specific gain is performed on the conical surface area with relatively weak echo amplitude in the wire outlet device, so that the sensitivity at different positions of the scanning area is consistent, and the quality of a three-dimensional image is improved. According to the invention, the internal structure of the extra-high voltage transformer outgoing line device can be rapidly and accurately detected, the three-dimensional structure of the outgoing line device can be reconstructed on site, and the method is of great significance to timely early warning and diagnosis of equipment faults and guarantee of safe and stable operation of power equipment.

Description

Technical Field

[0001] The present invention belongs to the technical field of ultrasonic detection of ultra-high voltage transformers, and specifically relates to an ultrasonic scanning and three-dimensional imaging method, device and equipment for an outlet device of an ultra-high voltage transformer. Background Art

[0002] During service, key connection parts such as the UHV transformer outlet device are prone to structural defects such as lateral displacement, longitudinal sinking, tilting, and equalizing ball falling off. These key parts only rely on the natural cycle of thermal expansion and contraction of insulating oil. Once the above-mentioned structural defects occur in this area, discharge breakdown is very likely to occur, seriously affecting the safety of the UHV power grid.

[0003] At present, the existing monitoring methods for key connection parts such as UHV transformer outlet devices include oil chromatography detection, core grounding current monitoring, core grounding high-frequency partial discharge, etc. This type of traditional detection and monitoring method can only be fed back to the terminal after hidden dangers or faults occur, and cannot effectively monitor the entire process of the transformer's internal state, and lacks internal structure and real-time state monitoring.

[0004] With the development of nondestructive testing technology, array ultrasonic testing technology has been valued for its ability to provide more accurate test results and a wider scanning range, and has been used to detect key connection parts such as UHV transformer outlet devices. However, existing array ultrasonic testing equipment still has deficiencies in automation and detection speed, especially when dealing with large outlet device structures. At the same time, traditional array ultrasonic testing can only display two-dimensional images, which lacks intuitiveness for the detection of large structures. There is a lack of internal structure and real-time status monitoring.

[0005] Therefore, there is an urgent need for a method that can efficiently and accurately perform array ultrasonic scanning and reconstruct the internal three-dimensional structure of a lead-out device, as well as a device for implementing the method, to meet the needs of in-situ three-dimensional imaging detection of UHV transformer lead-out devices. Summary of the invention

[0006] Aiming at the shortcomings of low efficiency, poor accuracy and non-intuitive detection results of ultrasonic detection of the structure of the outlet device of ultra-high voltage transformer at present, a method of array ultrasonic scanning and reconstruction of the internal three-dimensional structure of the outlet device with strong practicality, high efficiency and high accuracy, as well as a device for implementing the method and equipment for controlling the device are provided.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0008] An ultrasonic scanning and three-dimensional imaging method for an ultra-high voltage transformer outlet device, characterized by comprising:

[0009] Step 1: Collect ultrasonic signals from the outlet device of the UHV transformer;

[0010] Step 2: Realize three-dimensional imaging of the UHV transformer outgoing line device based on the acquired ultrasonic signal.

[0011] Furthermore, an array ultrasonic transducer 10 with an array element number greater than 32 is used to be close to the surface of the transformer housing 1, and a scanner includes a left drive unit 4 and a right drive unit 6. The scanner is used to clamp the array ultrasonic transducer 10 to perform circumferential and axial grid scanning movements;

[0012] The array ultrasonic transducer 10 is connected to the array ultrasonic board 5 to excite and receive ultrasonic signals, and the encoder is connected to the array ultrasonic board 5 to provide position coordinate feedback of the ultrasonic transducer 10;

[0013] The computer is connected to the array ultrasound board 5 for signal acquisition.

[0014] Furthermore, when performing C-scan detection on the UHV transformer outlet device, in order to obtain ultrasonic echoes of non-planar structures such as conical surfaces and vertical surfaces, the angle range is set between ±10°, with a total of 21 angles, that is, the number of channels N for acoustic wave acquisition. c The sampling time t is not less than 500us, the sampling frequency f is not less than 12.5MHz, the scanning axis sampling distance Lx, the sampling spacing dx is set to 1mm, the stepping axis sampling distance Ly, the sampling spacing dy is set to 2mm, and the number of sampling points in the depth direction is N. t =t×f+1, sampling step dz=v / f, where v is the medium sound velocity, and the number of sampling points of the scanning axis is N l =Lx / dx, the number of sampling points of the stepping axis is N θ =Ly / dy.

[0015] Furthermore, in order to convert the original 4D C-scan data into a t ×N l ×N θ Three-dimensional volume data, the echo data of all channels are superimposed along the scanning direction, and the echo amplitude of all sampling points is expressed as:

[0016]

[0017] Where i = 1, 2, ..., N l .

[0018] Furthermore, the computer determines the sampling resolution in each direction of the three-dimensional area according to the set sampling area parameters. First, the "glTexImage3D" function in the OpenGL library is used to create a three-dimensional texture object, and the resolution and internal data format of the texture are set; then, the texture parameters are set to ensure a smooth display effect during the sampling process; then, the three-dimensional echo volume data is loaded into the texture object; finally, the three-dimensional texture is sampled in the fragment shader, and a rectangular block displaying the data is rendered, ultimately realizing the visualization of the three-dimensional echo data in space.

[0019] Furthermore, in order to map the three-dimensional cuboid texture to the cylindrical coordinate system, the following parameters are introduced: mapping radius R, mapping angle α and filtering depth d;

[0020] Let the radius R in the cylindrical coordinate system represent the outer diameter of the cylinder, which is in the range of 0≤r≤R. The mapping angle α is used to define the coverage of the data in the circumferential direction, and the angular resolution is d θ =α / N θ , which depends on the number of cross-sectional slices N θ ;

[0021] Map the 3D cuboid texture to the cylindrical coordinate system, expressed as:

[0022]

[0023] x′=x (4)

[0024] Among them, x, y, z are the original three-dimensional cuboid texture coordinates, r represents the radial distance from the cylinder axis, θ is the circumferential angle, and x′ is the scanning direction coordinate;

[0025] When the mapping coordinate angle is d θ In order to obtain smooth texture mapping in the three-dimensional cylinder, the bilinear interpolation method is used for amplitude mapping, and the amplitude of the corresponding point is expressed as:

[0026] A=(A1(1-Δr)+A2Δr)(1-Δθ)+(A3(1-Δr)+A4Δr)Δθ (5)

[0027] Among them, A 1～4 They represent the amplitudes of the four points closest to the current coordinate point, Δθ is the closest circumferential distance, Δr is the closest radial distance, and the filter depth d sets the amplitudes of all points to 0 within this range;

[0028] Finally, OpenGL is used to render the generated 3D cylinder texture.

[0029] Furthermore, the pixel threshold T is set according to the amplitude distribution of the image, and the linear gain function G(r,θ,y) is defined so that the gain is higher in the low amplitude area and remains unchanged in the normal area. The gain function is expressed as:

[0030]

[0031] Where k is a constant used to control the amplitude of the soft gain, and A(r,θ,y) is the pixel amplitude corresponding to the midpoint of the three-dimensional cylinder coordinates;

[0032] Therefore, within the area defined by the cylindrical coordinate system, the corresponding echo amplitude is enhanced according to the gain function, which is expressed as:

[0033] A′(r,θ,y)=A(r,θ,y)×G(r,θ,y). (7)

[0034] An ultrasonic scanning and three-dimensional imaging device for an ultra-high voltage transformer outlet device, comprising: a signal acquisition module and a three-dimensional imaging module;

[0035] Wherein, the signal acquisition module is used to collect ultrasonic signals of the UHV transformer outlet device;

[0036] The signal acquisition module includes a scanning axis 3, a left drive unit 4, an array ultrasonic board 5, the right drive unit 6, the scanning axis drive unit 7, an array ultrasonic probe bracket 8 and an array ultrasonic probe 9. The array ultrasonic probe bracket 8 is used to make the array ultrasonic probe 9 in close contact with the transformer housing 1. The left and right drive units 4 control the scanner to move circumferentially along the housing. The scanning axis drive unit 7 controls the array ultrasonic probe 9 to move circumferentially along the scanning axis 3. All drive units have built-in encoders, which can provide real-time feedback of the position information of the corresponding motor including the scanning distance and the stepping distance.

[0037] The array ultrasonic board 5 is fixed between the left drive unit 4 and the right drive unit 6, and the array ultrasonic probe 9 is fixed on the ultrasonic probe bracket 8. As the scanner moves, the sound waves are synchronously excited / received. The sound waves are transmitted from the transformer housing 1 to the surface of the outlet device 2 through the transformer oil, generating a sound wave reflection signal, which is received by the array ultrasonic probe 9 again to record the scanning data;

[0038] The three-dimensional imaging module is used to realize three-dimensional imaging of the UHV transformer outlet device according to the ultrasonic signal of the UHV transformer outlet device.

[0039] A computer device comprises a PC host computer, wherein the PC host computer stores a program, and when the program is executed by the processor, the ultrasonic scanning method for the UHV transformer outlet device according to any one of claims 1 to 7 is implemented.

[0040] Furthermore, the computer device also includes: an EtherCAT-CAN adapter, a CAN bus and a servo drive, the PC host computer and the EtherCAT-CAN adapter serve as a master station, the servo drive serves as a slave station, the PC host computer sends CAN instructions to the servo drive via the EtherCAT protocol to achieve precise control of the signal acquisition module, and at the same time, the motor position information fed back by the slave station is sent to the master station via the EtherCAT protocol, the process data object communication mode is used to achieve the synchronous movement of the two drive units of the stepping axis through the synchronization frame in the CAN instruction, the service data object communication mode is used to control the movement of the scanning axis 3 through the sending and receiving of motion instructions, thereby improving the stability of the scanning movement, and the encoder feedback is transmitted using the PDO communication mode.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] 1) CAN commands are transmitted through the EtherCAT protocol to achieve precise control of the dual-axis three-motor scanning device by the PC host computer, and to collect array ultrasonic sector scanning C-scan data of the target area;

[0043] 2) Based on the ultrasonic echo data obtained from the actual measurement points, the data is mapped into the three-dimensional coordinates of the real structure through the OpenGL three-dimensional image texture technology in C++, and the color and transparency are mapped according to the ultrasonic echo amplitude to reconstruct the three-dimensional image inside the outlet device;

[0044] 3) Through the linear gain setting in the scanning direction, the specific gain is enhanced for the conical area with weak echo amplitude in the output device, so that the sensitivity at different positions in the scanning area is consistent, thereby improving the quality of the three-dimensional image;

[0045] 4) Realize the internal structure and real-time status monitoring of UHV transformers. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is a schematic diagram of bilinear interpolation of a cylinder in the yz plane according to an embodiment of the present invention;

[0047] Figure 2 A three-dimensional image reconstructed according to an embodiment of the present invention;

[0048] Figure 3 A three-dimensional image reconstructed after linear gain enhancement according to an embodiment of the present invention;

[0049] Figure 4 This is a schematic diagram of an array ultrasonic detection device for a line outlet device according to an embodiment of the present invention;

[0050] Figure 5This is a diagram of the architecture of the signal acquisition module control device according to an embodiment of the present invention.

[0051] Among them, 1-transformer housing, 2-outlet device, 3-scanning axis, 4-left drive unit, 5-array ultrasonic board, 6-right drive unit, 7-scanning axis drive unit, 8-array ultrasonic probe bracket, 9-array ultrasonic probe, 10-array ultrasonic transducer. DETAILED DESCRIPTION

[0052] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0053] Example 1

[0054] See also Figure 1-3 The method for ultrasonic scanning and three-dimensional imaging of a UHV transformer outlet device comprises the following steps:

[0055] 1) Collect ultrasonic signals from the UHV transformer outlet device.

[0056] (1) An array ultrasonic transducer with more than 32 array elements is placed close to the surface of the transformer housing 1, and the scanner includes a left drive unit 4 and a right drive unit 6. The scanner is used to clamp the array ultrasonic transducer 10 to perform circumferential and axial grid scanning movements; the array ultrasonic transducer 10 is connected to an array ultrasonic board 5 to excite and receive ultrasonic signals, an encoder is connected to the array ultrasonic board 5 to provide position coordinate feedback of the ultrasonic transducer 10; and a computer is connected to the array ultrasonic board 5 to perform board control and signal acquisition.

[0057] (2) When performing C-scan detection with array ultrasonic fan scanning, in order to obtain ultrasonic echoes of non-planar structures such as conical surfaces and vertical surfaces, the angle range is set between ±10°, with a total of 21 angles, that is, the number of channels N for acoustic wave acquisition. c is 21. At the same time, in order to ensure that the sound wave can be incident on the output device, and to ensure the data volume and avoid the problem of data loss during the scanning process, the sampling time t is not less than 500us, the sampling frequency f is not less than 12.5MHz, the scanning axis sampling distance Lx, the sampling spacing dx is set to 1mm, the stepping axis sampling distance Ly, the sampling spacing dy is set to 2mm, therefore, the number of sampling points in the depth direction is N t =t×f+1, sampling step dz=v / f, where v is the medium sound velocity, and the number of sampling points of the scanning axis is N l =Lx / dx, the number of sampling points of the stepping axis is Nθ = Ly / dy. In order to convert the original 4D C-scan data into a size of N t ×N l ×N θ Three-dimensional volume data, the echo data of all channels are superimposed along the scanning direction, and the echo amplitude of all sampling points is expressed as:

[0058]

[0059] Where i = 1, 2, ..., N l .

[0060] 2) Realize three-dimensional imaging of the UHV transformer outgoing line device based on the acquired ultrasonic signal.

[0061] (1) The computer determines the sampling resolution in each direction of the three-dimensional area according to the sampling area size, scanning step length, step length and other parameters set in step (2), and establishes a three-dimensional rectangular texture area based on OpenGL. Each pixel point corresponds to a spatial coordinate in the three-dimensional texture area, so that the three-dimensional echo volume data can be accurately mapped to the corresponding spatial position. The specific process is as follows: First, use the "glTexImage3D" function in the OpenGL library to create a three-dimensional texture object, and set the resolution and internal data format of the texture. Subsequently, set the texture parameters, such as the filtering mode and the boundary processing mode, to ensure a smooth display effect during the sampling process. Then, load the three-dimensional echo volume data into the texture object. Finally, sample the three-dimensional texture in the fragment shader and render a rectangular block displaying the data, finally realizing the visualization of the three-dimensional echo data in space.

[0062] (2) In order to map the 3D cuboid texture to the cylindrical coordinate system, some key parameters are introduced: mapping radius R, mapping angle α, and filtering depth d. These parameters are used to define the geometric properties of the final 3D cylinder and the projection range of ultrasound data in order to reconstruct the 3D image more efficiently.

[0063] First, let the mapping radius R in the cylindrical coordinate system represent the outer diameter of the cylinder, which ranges from 0 ≤ r ≤ R and the mapping angle α is used to define the coverage of the data in the circumferential direction, with an angular resolution of d θ =α / N θ , which depends on the number of cross-sectional slices N θ Then, the 3D cuboid texture is mapped to the cylindrical coordinate system, expressed as:

[0064]

[0065] x′=x (4)

[0066] Among them, x, y, z are the original three-dimensional cuboid texture coordinates, r represents the radial distance from the cylinder axis, θ is the circumferential angle, and x′ is the scanning direction coordinate.

[0067] Next, when the mapping coordinate angle is d θ In order to obtain smooth texture mapping in the three-dimensional cylinder, the bilinear interpolation method is used for amplitude mapping, as shown in the figure. The amplitude of the corresponding point is expressed as:

[0068] A=(A1(1-Δr)+A2Δr)(1-Δθ)+(A3(1-Δr)+A4Δr)Δθ (5)

[0069] Among them, A 1～4 They represent the amplitudes of the four points closest to the current coordinate point, Δθ is the closest circumferential distance, and Δr is the closest radial distance. At the same time, in order to avoid the influence of multiple reflections of sound waves from the shell, it is necessary to set the filter depth d, and set the amplitudes of all points within this range to 0. Finally, OpenGL is used to render the generated three-dimensional cylindrical texture, and dynamic adjustment is supported. Users can observe the cylindrical texture image from different angles through operations such as rotation and scaling to fully understand the internal structure of the outlet device. Figure 2 (a) and Figure 2 (b) are the original three-dimensional rectangular texture image and the mapped three-dimensional cylindrical texture image reconstructed by array ultrasonic detection of UHV transformer outgoing line devices.

[0070] (3) Based on the three-dimensional cylindrical texture image obtained in step (2), we can further process the image to identify low-amplitude regions of specific structures and enhance the echo signals of interest, thereby reconstructing a three-dimensional image with high precision, high resolution, and high consistency.

[0071] (4) The pixel threshold T is set according to the amplitude distribution of the image. Its value can be dynamically adjusted according to different scanning positions to distinguish between low-amplitude and normal-amplitude areas. The low-amplitude area is detected along the scanning axis and depth direction. After the low-amplitude area is identified, the surface equation is generated using data fitting technology to describe the shape of the defect area or target structure. Polynomial fitting, spline curve or surface fitting methods can be used to approximate the contour or boundary of the area. A linear gain function G(r,θ,y) is defined so that the gain is higher in the low-amplitude area and remains unchanged in the normal area. The gain function can be expressed as:

[0072]

[0073] Among them, k is a constant used to control the amplitude of the soft gain, and A(r,θ,y) is the pixel amplitude of the corresponding midpoint of the three-dimensional cylindrical coordinate system. Therefore, within the area defined by the cylindrical coordinate system, the corresponding echo amplitude is enhanced according to the gain function, which is expressed as:

[0074] A′(r,θ,y)=A(r,θ,y)×G(r,θ,y) (7)

[0075] After the above enhancement process, the enhanced echo amplitude data is remapped to the 3D cylindrical texture image. The reconstructed 3D image is rendered and visualized using OpenGL image rendering technology. Finally, users can observe the reconstructed 3D image from different angles, and can more clearly understand the internal structure and potential defect areas of the UHV transformer and reactor, and realize detailed diagnosis of the equipment structure.

[0076] Embodiment 2

[0077] See also Figure 4 ,This embodiment is applicable to the ultrasonic scanning and three-dimensional imaging of the outlet device of the ultra-high voltage transformer. The device can be implemented in software and / or hardware. The device can be integrated in any equipment that provides the ultrasonic scanning and three-dimensional imaging functions of the outlet device of the ultra-high voltage transformer. The object to be detected is an ultra-high voltage transformer, including a transformer housing 1 and an internal outlet device 2, both of which present a coaxial cylindrical structure. The outlet device 2 is prone to structural defects during transportation, assembly, and operation, such as axial movement, eccentricity, longitudinal sinking, tilting, typical insulation parts falling off, and other structural defects of the outlet device 2. The device for ultrasonic scanning and three-dimensional imaging of the outlet device of the ultra-high voltage transformer specifically includes: a signal acquisition module and a three-dimensional imaging module.

[0078] Among them, the signal acquisition module is used to collect ultrasonic signals from the UHV transformer outlet device.

[0079] Specifically, the signal acquisition module includes a scanning axis 3, a left drive unit 4, an array ultrasonic board 5, the right drive unit 6, the scanning axis drive unit 7, an array ultrasonic probe bracket 8 and an array ultrasonic probe 9. The array ultrasonic probe bracket 8 is used to make the array ultrasonic probe 9 in close contact with the transformer housing 1, the left and right drive units 4 control the scanner to move circumferentially along the housing, and the scanning axis drive unit 7 controls the array ultrasonic probe 9 to move circumferentially along the scanning axis 3. All drive units have built-in encoders, which can provide real-time feedback on the position information of the corresponding motor including the scanning distance and the stepping distance.

[0080] The array ultrasonic board 5 is fixed between the left drive unit 4 and the right drive unit 6. If the array ultrasonic board 5 is not fixed to the scanner, the ultrasonic probe cable will inevitably be too long, resulting in attenuation loss of the acoustic signal, affecting the detection accuracy. The array ultrasonic probe 9 is fixed on the ultrasonic probe bracket 8, and excites / receives sound waves synchronously with the movement of the scanner. The sound waves are transmitted from the transformer housing 1 to the surface of the outlet device 2 through the transformer oil, generating a sound wave reflection signal, which is received by the array ultrasonic probe 9 again to record the scanning data.

[0081] The three-dimensional imaging module is used to realize three-dimensional imaging of the UHV transformer outlet device according to the ultrasonic signal of the UHV transformer outlet device.

[0082] The above-mentioned product can execute the method provided by any embodiment of the present invention, and has the corresponding functional modules and beneficial effects of the execution method.

[0083] Embodiment 3

[0084] Figure 5 This is a schematic diagram of the structure of a computer device in Embodiment 3 of the present invention. This structure is only an example and should not bring any limitation to the functions and scope of use of the embodiment of the present invention.

[0085] Specifically, the device is composed of a PC host computer, an EtherCAT-CAN adapter, a CAN bus and a servo driver. The PC host computer stores one or more programs to implement the ultrasonic scanning and three-dimensional imaging method of the UHV transformer outlet device provided in the embodiment of the present application. The PC host computer and the EtherCAT-CAN adapter are used as the master station, and the servo driver is used as the slave station. The PC host computer sends CAN instructions to the servo driver through the EtherCAT protocol to achieve precise control of the signal acquisition module. At the same time, the motor position information fed back by the slave station is sent to the master station through the EtherCAT protocol to control the ultrasonic pulse excitation. Among them, the stepper shaft drive motor needs to start and stop synchronously, and the process data object (Process Data Object, PDO) communication mode is adopted. The synchronous movement of the two drive units of the stepper shaft is realized through the synchronization frame in the CAN instruction, while the scanning shaft drive motor does not need to move synchronously. The service data object (Service Data Object, SDO) communication mode is used to control the movement of the scanning shaft 3 through the sending and receiving of the motion instruction, thereby improving the stability of the scanning movement. Since all encoder feedback information needs to be transmitted in real time, the encoder feedback is transmitted in the PDO communication mode.

[0086] Finally, it should be noted that the above embodiments are only preferred embodiments of the present invention, which are only used to illustrate the technical solution of the present invention rather than to limit it. Any modification, improvement, other modification or equivalent replacement made to the technical solution of the present invention by ordinary technicians in this field, as long as they do not depart from the spirit and scope of the technical solution of the present invention, should be included in the protection scope of the present invention.

Claims

1. An ultrasonic scanning and three-dimensional imaging method for a UHV transformer outlet device, characterized in that: include: Step 1: Collect ultrasonic signals from the outlet device of the UHV transformer; Step 2: Realize three-dimensional imaging of the UHV transformer outgoing line device based on the acquired ultrasonic signal.

2. The ultrasonic scanning and three-dimensional imaging method of the UHV transformer outlet device according to claim 1 is characterized in that: An array ultrasonic transducer (10) having an array element number greater than 32 is placed in close contact with the surface of a transformer housing (1); a scanner comprises a left drive unit (4) and a right drive unit (6); and the scanner is used to clamp the array ultrasonic transducer (10) to perform circumferential and axial grid scanning movements; The array ultrasonic transducer (10) is connected to the array ultrasonic board (5) to excite and receive ultrasonic signals, and the encoder is connected to the array ultrasonic board (5) to provide position coordinate feedback of the ultrasonic transducer (10); The computer is connected to the array ultrasound board (5) to collect signals.

3. The ultrasonic scanning and three-dimensional imaging method of the UHV transformer outlet device according to claim 2 is characterized in that: When performing C-scan detection on the UHV transformer outlet device, in order to obtain ultrasonic echoes of non-planar structures such as conical surfaces and vertical surfaces, the angle range is set between ±10°, with a total of 21 angles, that is, the number of channels N for acoustic wave acquisition. ch The sampling time t is not less than 500us, the sampling frequency f is not less than 12.5MHz, the scanning axis sampling distance Lx, the sampling spacing dx is set to 1mm, the stepping axis sampling distance Ly, the sampling spacing dy is set to 2mm, and the number of sampling points in the depth direction is N. t =t×f+1, sampling step dz=v / f, where v is the medium sound velocity, and the number of sampling points of the scanning axis is N l =Lx / dx, the number of sampling points of the stepping axis is N θ =Ly / dy.

4. The ultrasonic scanning and three-dimensional imaging method of the UHV transformer outlet device according to claim 3 is characterized in that: In order to convert the original 4D C-scan data into a t ×N l ×N θ Three-dimensional volume data, the echo data of all channels are superimposed along the scanning direction, and the echo amplitude of all sampling points is expressed as: Where i = 1, 2, ..., N l .

5. The ultrasonic scanning and three-dimensional imaging method of the UHV transformer outlet device according to claim 4 is characterized in that: The computer determines the sampling resolution in each direction of the three-dimensional area based on the set sampling area parameters. First, the "glTexImage3D" function in the OpenGL library is used to create a three-dimensional texture object and set the texture resolution and internal data format. Subsequently, the texture parameters are set to ensure a smooth display effect during the sampling process. Then, the three-dimensional echo volume data is loaded into the texture object. Finally, the three-dimensional texture is sampled in the fragment shader and a rectangular block displaying the data is rendered, ultimately achieving a visual presentation of the three-dimensional echo data in space.

6. The ultrasonic scanning and three-dimensional imaging method of the UHV transformer outlet device according to claim 4 is characterized in that: In order to map the three-dimensional cuboid texture to the cylindrical coordinate system, the parameters are introduced: mapping radius R, mapping angle α and filtering depth d; Let the radius R in the cylindrical coordinate system represent the outer diameter of the cylinder, which is in the range of 0≤r≤R. The mapping angle α is used to define the coverage of the data in the circumferential direction, and the angular resolution is d θ =α / N θ , which depends on the number of cross-sectional slices N θ ; Map the 3D cuboid texture to the cylindrical coordinate system, expressed as: x′=x (4) Among them, x, y, z are the original three-dimensional cuboid texture coordinates, r represents the radial distance from the cylinder axis, θ is the circumferential angle, and x′ is the scanning direction coordinate; When the mapping coordinate angle is d θ In order to obtain smooth texture mapping in the three-dimensional cylinder, the bilinear interpolation method is used for amplitude mapping, and the amplitude of the corresponding point is expressed as: A=(A1(1-Δr)+A2Δr)(1-Δθ)+(A3(1-Δr)+A4Δr)Δθ (5) Among them, A 1～4 They represent the amplitudes of the four points closest to the current coordinate point, Δθ is the closest circumferential distance, Δr is the closest radial distance, and the filter depth d sets the amplitudes of all points to 0 within this range; Finally, OpenGL is used to render the generated 3D cylinder texture.

7. The ultrasonic scanning and three-dimensional imaging method of the UHV transformer outlet device according to claim 6 is characterized in that: The pixel threshold T is set according to the amplitude distribution of the image, and the linear gain function G(r,θ,y) is defined so that the gain is higher in the low amplitude area and remains unchanged in the normal area. The gain function is expressed as: Where k is a constant used to control the amplitude of the soft gain, and A(r,θ,y) is the pixel amplitude corresponding to the midpoint of the three-dimensional cylinder coordinates; Therefore, within the area defined by the cylindrical coordinate system, the corresponding echo amplitude is enhanced according to the gain function, which is expressed as: A′(r,θ,y)=A(r,θ,y)×G(r,θ,y). (7) 8. An ultrasonic scanning and three-dimensional imaging device for an ultra-high voltage transformer outlet device, characterized in that: include: Signal acquisition module and three-dimensional imaging module; Wherein, the signal acquisition module is used to collect ultrasonic signals of the UHV transformer outlet device; The signal acquisition module comprises a scanning axis (3), a left drive unit (4), an array ultrasonic board (5), the right drive unit (6), the scanning axis drive unit (7), an array ultrasonic probe bracket (8) and an array ultrasonic probe (9); the array ultrasonic probe bracket (8) is used to make the array ultrasonic probe (9) in close contact with the transformer housing (1); the left and right drive units (4) control the scanner to move circumferentially along the housing; the scanning axis drive unit (7) controls the array ultrasonic probe (9) to move circumferentially along the scanning axis (3); all drive units have built-in encoders, which can provide real-time feedback of position information of the corresponding motor including scanning distance and stepping distance; The array ultrasonic board (5) is fixed between the left drive unit (4) and the right drive unit (6), and the array ultrasonic probe 9 is fixed on the ultrasonic probe bracket (8). As the scanner moves, the sound waves are synchronously excited / received. The sound waves are transmitted from the transformer housing (1) to the surface of the outlet device (2) through the transformer oil, generating a sound wave reflection signal, which is then received by the array ultrasonic probe (9) to record the scanning data. The three-dimensional imaging module is used to realize three-dimensional imaging of the UHV transformer outlet device according to the ultrasonic signal of the UHV transformer outlet device.

9. A computer device, comprising a PC host computer, wherein the PC host computer stores a program, characterized in that: When the program is executed by the processor, the ultrasonic scanning method for the UHV transformer outlet device according to any one of claims 1 to 7 is implemented.

10. The computer device according to claim 9, characterized in that The computer device also includes: an EtherCAT-CAN adapter, a CAN bus and a servo drive. The PC host computer and the EtherCAT-CAN adapter serve as a master station, and the servo drive serves as a slave station. The PC host computer sends CAN instructions to the servo drive through the EtherCAT protocol to achieve precise control of the signal acquisition module. At the same time, the motor position information fed back by the slave station is sent to the master station through the EtherCAT protocol. The process data object communication mode is used to achieve synchronous movement of two drive units of the stepping axis through the synchronization frame in the CAN instruction. The service data object communication mode is used to control the movement of the scanning axis (3) through the sending and receiving of movement instructions, thereby improving the stability of the scanning movement. Encoder feedback is transmitted using the PDO communication mode.

Images