X-ray and ultra-high frequency combined GIS insulator defect positioning method

Abstract

The application provides a GIS insulator defect positioning method combined with X-ray and ultra-high frequency, comprising: collecting partial discharge signals by using an ultra-high frequency sensor array, converging a defect range to a target insulator; performing X-ray transmission scanning by translating with a preset axial step and rotating around a central axis with a preset angular step, and recording scanning position information corresponding to each transmission; synchronously collecting ultra-high frequency partial discharge signals during the X-ray transmission scanning process, determining a transmission scanning position corresponding to an abnormal signal based on a synchronous timing relationship between the transmission scanning and the ultra-high frequency signal collection time when the ultra-high frequency partial discharge signal meets a preset abnormal condition, and determining a circumferential direction and a radial position of the defect. The application combines the synchronous collection of the ultra-high frequency partial discharge signals during the X-ray transmission scanning process, and finally directly calculates the circumferential direction and the radial position of the defect based on the transmission index of the position, thereby significantly improving the accuracy and detection efficiency of the defect positioning.

Description

Technical Field

[0001] This invention relates to the field of power equipment condition monitoring and fault diagnosis technology, and more specifically, to a method for locating defects in GIS insulators using a combination of X-ray and ultra-high frequency radiation. Background Technology

[0002] With the large-scale application of ultra-high voltage GIS equipment, internal insulator defects (such as air gaps, impurities, and cracks) have become a significant factor affecting the safe operation of the equipment. Partial discharge, as an important indicator of insulation degradation, is currently the primary detection method. Existing mainstream technologies include: Ultra-high frequency (UHF) detection technology, which uses electromagnetic wave signals generated by partial discharge for detection and location; X-ray imaging detection technology, which visualizes the internal structure through X-ray penetration; and auxiliary methods such as ultrasonic detection and gas composition analysis. Among these, the UHF method is suitable for the detection and location of GIS insulation defects, but its location accuracy is only about 30 centimeters, making it difficult to achieve precise defect location because it cannot determine the severity of the insulation defect. The X-ray method is intuitive and can achieve millimeter-level accurate location of defects, but its identification capability in complex structures is limited, and its imaging accuracy for small insulation defects is insufficient. Furthermore, X-rays can excite partial discharge in insulation defects. This invention aims to combine the advantages of UHF partial discharge detection and X-ray imaging detection to achieve precise location of internal insulation in GIS. Summary of the Invention

[0003] In view of this, the present invention proposes a method for locating defects in GIS insulators by combining X-ray and UHF testing, aiming to solve the problem of insufficient location accuracy of existing single detection methods.

[0004] This invention proposes a method for locating defects in GIS insulators using a combination of X-ray and UHF spectroscopy, comprising: Step 1: Use an ultra-high frequency sensor array to collect partial discharge signals. Based on the arrival time difference of the signals received by multiple sensors in the ultra-high frequency sensor array, perform preliminary location of the partial discharge source and narrow the defect range to the target insulator. Step 2: Take the position corresponding to the center of the detector image when the characteristic part at any end of the target insulator is radiographed as the initial scanning position, translate along the central axis of the target insulator with a preset axial step size, and rotate around the central axis of the target insulator with a preset angular step size to perform X-ray radiographic scanning, and record the scanning position information corresponding to each radiograph. The scanning position information includes at least the circumferential radiographic index and radial radiographic index of the radiograph relative to the initial scanning position. Step 3: During the X-ray radiographic scanning process, ultra-high frequency partial discharge signals are acquired synchronously. When the ultra-high frequency partial discharge signal meets the preset abnormal conditions, the radiographic scanning position corresponding to the abnormal signal is determined based on the synchronous timing relationship between the radiographic scanning and the acquisition time of the ultra-high frequency partial discharge signal, and the circumferential radiographic index and radial radiographic index of the radiographic scanning position are obtained. Step 4: Determine the circumferential orientation and radial position of the defect relative to the initial scanning position based on the circumferential radiographic index and the radial radiographic index.

[0005] Furthermore, in the aforementioned GIS insulator defect location method combining X-ray and UHF spectroscopy, the preliminary location of the partial discharge source based on the arrival time difference of signals received by multiple sensors in the UHF sensor array specifically includes: By using UHF sensor arrays deployed inside and outside the GIS equipment to collect partial discharge signals in real time, the time difference between the wavefronts of partial discharge signals collected by UHF sensors at different locations is obtained. Based on the distance of each UHF sensor along the internal conductor of the GIS, the propagation speed of electromagnetic waves in the GIS medium, and the time difference, the distance between the partial discharge source and each UHF sensor is calculated, and the calculated position of the partial discharge source is mapped to the target insulator.

[0006] Furthermore, in the above-mentioned GIS insulator defect location method combining X-ray and UHF, the step of translating along the central axis of the target insulator with a preset axial step size and rotating around the central axis of the target insulator with a preset angular step size, and performing X-ray radiographic scanning, includes any of the following scanning sequences: At the same circumferential angle, the target insulator is illuminated sequentially along the central axis at the axial step size. After completing all radial illumination at the same circumferential angle, the system switches to the next circumferential angle around the central axis of the target insulator at a preset angular step size. At the same axial position, the target insulator is radiographed sequentially around its central axis at preset angular steps. After completing all circumferential radiographs at that axial position, the system switches to the next axial position along the central axis of the target insulator at preset axial steps.

[0007] Furthermore, in the above-mentioned GIS insulator defect location method combining X-ray and UHF, the preset abnormal conditions include: The average amplitude of the synchronously acquired UHF partial discharge signal is 1.5 to 2 times the average amplitude of the partial discharge signal before X-ray irradiation, and the frequency of occurrence of the synchronously acquired UHF partial discharge signal is more than 3 times that of the frequency of occurrence of the partial discharge signal before X-ray irradiation.

[0008] Furthermore, in the above-mentioned GIS insulator defect location method combining X-ray and UHF, during the X-ray radiographic scanning, the X-ray source and detector remain at each radiographic position for a preset duration to allow the X-ray to fully irradiate the target insulator and generate an excitation signal that meets the detection requirements at that position.

[0009] Furthermore, in the aforementioned GIS insulator defect location method combining X-ray and UHF, the step of determining the radiographic scanning location corresponding to the abnormal signal based on the synchronous temporal relationship between X-ray radiographic scanning and UHF partial discharge signal acquisition includes: The acquisition time of the ultra-high frequency partial discharge signal that meets the preset abnormal conditions is matched with the time window of each radiographic examination. The radiographic scanning position corresponding to the abnormal signal whose acquisition time falls within the time window is determined as the radiographic scanning position corresponding to the abnormal signal.

[0010] Furthermore, in the above-mentioned GIS insulator defect location method combining X-ray and UHF, the scanning location information also includes the radiographic time window and the corresponding acquired image; the circumferential radiographic index and the radial radiographic index allocated for each radiographic exposure are used as radiographic area codes and associated with the radiographic time window and the image to establish the correspondence between the scanning location, the time window and the image.

[0011] Furthermore, in the above-mentioned GIS insulator defect location method combining X-ray and UHF, determining the circumferential orientation and radial position of the defect relative to the initial scanning position includes: Construct a two-dimensional index grid consisting of circumferential and radial light indices; Mapping the radiographic scanning position onto the two-dimensional index grid yields the corresponding circumferential radiographic index. i 0 and radial radiometric index j 0; Based on the two-dimensional index grid, according to i 0 and j 0. Determine the circumferential orientation and radial position corresponding to the defect; in, i 0 characterizes the surface of the target insulator as being composed of The defined circumferential angle range, j0, characterizes the surface of the target insulator as being composed of ( j 0-1) / n 1~ j 0 / n The radial range defined by 1, together with the circumferential angular range, constitutes a two-dimensional positioning reference for the defect relative to the initial scanning position; Δ The preset angle step size, n1 represents the total number of radial radiographs at the same circumferential angle.

[0012] Furthermore, in the aforementioned method for locating defects in GIS insulators using a combination of X-rays and ultra-high frequency radiation, the total number of radial irradiations at the same circumferential angle... n The method for determining 1 is as follows: ; In the formula, R Let Δ be the projected radius of the target insulator on a cross-section perpendicular to its central axis. d To preset the axial step size, θ Δ is the angle between the X-ray beam direction and the central axis of the target insulator. R For two consecutive axial scans along the central axis of the target insulator, the X-rays are at an angle. θ The step size generated radially within the cross-section due to oblique incidence.

[0013] Furthermore, in the aforementioned method for locating defects in GIS insulators using a combination of X-rays and ultra-high frequency radiation, the preset axial step size Δ d satisfy: In the formula, The diameter of the collimated X-ray beam. The angle between the X-ray beam direction and the central axis of the target insulator. k Take a value of 0.5 to 0.7.

[0014] The X-ray and UHF combined GIS insulator defect localization method of this invention uses an UHF sensor array to initially locate partial discharge sources and converge the defect range to the target insulator, achieving precise locking of the detection area. Through an X-ray radiographic scanning method combining axial translation and rotation, and utilizing a time-synchronization mechanism between X-ray radiography and UHF partial discharge signal acquisition, abnormal discharge signals are precisely mapped to corresponding scanning positions. Finally, based on the radiographic index of this position, the circumferential and radial positions of the defect are directly calculated. This effectively solves the technical problem of simultaneously acquiring circumferential and radial spatial information of defects in existing technologies, significantly improving the accuracy and efficiency of defect localization while enhancing the reliability of detection under complex structural conditions and reducing the uncertainty of single detection methods. Attached Figure Description

[0015] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1A schematic flowchart of the X-ray and UHF combined GIS insulator defect location method provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the arrangement of each high-frequency sensor and X-ray source in the X-ray and ultra-high frequency combined GIS insulator defect location method provided in the embodiments of the present invention; Figure 3 This is a schematic diagram illustrating the principle of mapping the axial scan position to the radial radiographic position after oblique X-ray incidence in an embodiment of the present invention; Figure 4 This is a schematic diagram of the cross-sectional distribution of X-ray oblique imaging points on the surface of a GIS insulator in an embodiment of the present invention; Figure 5 This is a PRPD image of partial discharge of air gap defects in an insulator before X-ray irradiation in an embodiment of the present invention; Figure 6 This is a PRPD image of partial discharge of air gap defects in insulators during X-ray irradiation in an embodiment of the present invention; Figure 7 This is a schematic diagram showing the changes in amplitude and frequency of the partial discharge signal of the air gap defect inside the GIS insulator over time before and during X-ray irradiation, as described in an embodiment of the present invention. Detailed Implementation

[0016] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0017] See Figure 1 The X-ray and UHF combined GIS insulator defect location method of this invention includes: Step S1: Use an ultra-high frequency sensor array to collect partial discharge signals. Based on the arrival time difference of the signals received by multiple sensors in the ultra-high frequency sensor array, perform preliminary location of the partial discharge source and narrow the defect range to the target insulator.

[0018] Specifically, the preliminary location of the partial discharge source based on the time difference of arrival of signals received by multiple sensors in the UHF sensor array includes: Using UHF sensor arrays deployed inside and outside the GIS equipment, partial discharge signals (frequency range of 300~1500MHz) are collected in real time, and the time difference between the wavefronts of partial discharge signals collected by UHF sensors at different locations is obtained. Based on the distance of each UHF sensor along the internal conductor of the GIS, the propagation speed of electromagnetic waves in the GIS medium, and the time difference, the distance between the partial discharge source and each UHF sensor is calculated, and the calculated position of the partial discharge source is mapped to the target insulator.

[0019] Specifically, target insulators refer to insulating components in gas-insulated metal-enclosed switchgear (GIS) used to support conductors or isolate gas chambers, including basin insulators, disc insulators, etc.

[0020] This invention is particularly applicable to basin-type insulators and / or disc-type insulators in ultra-high voltage and extra-high voltage GIS equipment (rated voltage of 330kV and above; operating frequency of ultra-high frequency sensors of 300~1500 MHz).

[0021] It should be noted that the generation of UHF partial discharge signals depends on the discharge behavior of insulation defects under high field strength. Only when the equipment is energized will the defects generate UHF electrical signals that can be captured by the sensor array. Therefore, in this embodiment, the GIS equipment is in a energized operating state, and the UHF sensor array is used to collect partial discharge signals.

[0022] In practice, after a suspected partial discharge anomaly is detected during online monitoring or live-line testing of GIS equipment, an ultra-high frequency partial discharge detection device with a sampling rate of not less than 2GS / s is used to locate the suspected partial discharge source. Built-in or external ultra-high frequency partial discharge sensors are connected to both sides of the suspected partial discharge signal location. The sensors on both sides collect the partial discharge signal, and the time difference between the two partial discharge signal wavefronts is calculated, that is, the time difference between the ultra-high frequency partial discharge signal from the discharge location to the two sensors. The location of the suspected partial discharge source is calculated using the following formula, thereby determining the insulator of the foreign object partial discharge.

[0023] Continue reading Figure 2 The diagram shows four UHF sensors arranged axially on the target insulator: a first UHF sensor 1, a second UHF sensor 2, a third UHF sensor 3, and a fourth UHF sensor 4. The first UHF sensor 1, the third UHF sensor 3, and the fourth UHF sensor 4 are all built-in UHF sensors, while the second UHF sensor 2 is an external UHF sensor.

[0024] During initial positioning, any two adjacent UHF sensors are selected as a positioning unit. Taking the first UHF sensor 1 and the second UHF sensor 2 as an example: Let d be the distance between the two UHF sensors along the internal conductor axis of the GIS; let d1 and d2 represent the distances between the first UHF sensor 1, the second UHF sensor 2, and the partial discharge source along the internal conductor axis of the GIS, respectively; c is the electromagnetic wave propagation speed, which is taken as 3 × 10⁻⁶ in SF₆ gas. 8 m / s; t represents the time difference between the wavefronts of the two partial discharge signals.

[0025] Given d1+d2=d, d1-d2=±ct; We can obtain: d1 = (d ± ct) / 2, d2 = d - d1 When the signal from the first UHF sensor arrives before the signal from the second UHF sensor (i.e., the signal from the first UHF sensor leads), a "+" sign is used; when the signal from the first UHF sensor lags behind the signal from the second UHF sensor, a "-" sign is used.

[0026] The resulting d1 and d2 represent the axial distances from the partial discharge source along the internal conductor of the GIS to the first and second UHF sensors, respectively. The smaller of the two axial distances (the one corresponding to the UHF sensor that first receives the signal) is taken as the axial distance from the partial discharge source to the nearest UHF sensor. By comparing this distance with the known installation positions of each insulator along the conductor axis from that side end of the GIS, the target insulator number where the partial discharge source is located can be determined.

[0027] Step S2: Take the position corresponding to the center of the detector image when the characteristic part at any end of the target insulator is radiographed as the initial scanning position, translate along the central axis of the target insulator with a preset axial step size, and rotate around the central axis of the target insulator with a preset angular step size to perform X-ray radiographic scanning, and record the scanning position information corresponding to each radiograph. The scanning position information includes at least the circumferential radiographic index and radial radiographic index of the radiograph relative to the initial scanning position.

[0028] In this embodiment, the feature parts refer to the structural features at both ends of the insulator that can be used for imaging and positioning, including the axial section where the low-voltage side flange connects to the insulator and the axial section where the high-voltage side center conductor connects to the insulator.

[0029] Specifically, after obtaining the target insulator area, an X-ray detection device is arranged outside the area. The X-ray detection device includes an X-ray source 5, a detector (not shown in the figure), and two annular rotating bodies. The annular rotating bodies have a clamp-like structure and are detachably fitted around the outer periphery of the GIS cylinder and located on both sides of the target insulator in the axial direction. Both can rotate circumferentially around the axis of the GIS cylinder and can move along the axial direction of the GIS cylinder. The X-ray beam from the X-ray source is limited by a collimator to form a directional excitation beam with a preset divergence angle.

[0030] The X-ray source is mounted on one of the annular rotating bodies, and the detector is mounted on the other. Before scanning, the circumferential phase difference between the X-ray source and the detector is adjusted to 180°. Then, the two annular rotating bodies are synchronously rotated through a mechanical linkage mechanism (such as a rigid connecting rod), so that the X-ray source 5 and the detector always maintain a 180° opposing relationship during the scanning process. During the scanning process, the two annular rotating bodies are moved axially to the preset radiographic position, and then driven to rotate synchronously around the axis of the GIS cylinder, so that the X-ray source 5 and the detector always maintain a radially opposing state and perform circumferential scanning around the target insulator. During the entire axial movement and circumferential rotation, the relative distance and angle between the X-ray source and the detector remain unchanged to ensure the integrity of data acquisition.

[0031] When the image of any characteristic part of the target insulator 6 (the flange face of the low-voltage side or the center conductor of the high-voltage side) is located at the center of the detector image, this position is set as the initial scanning position. At this time, the axial position is recorded as 0 and the circumferential angle is recorded as 0°. During the scanning process, the annular rotating body can adopt a stepping motion mode, stopping and staying for a preset duration after reaching a preset illumination position. The preset duration is 1 to 2 minutes, so that the X-rays can fully irradiate the target insulator and generate an excitation signal that meets the detection requirements at that position. During the dwell period, the X-ray source continues to expose, and the single exposure time is consistent with the dwell time. The X-ray source tube voltage does not exceed 300kV and the tube current does not exceed 5mA. Under these parameter conditions, the target insulator can generate an excitation signal that meets the detection requirements without causing insulation degradation.

[0032] After completing a single radiograph and data acquisition during the dwell period, the device moves to the next position according to a preset step size. Preferably, adjacent radiograph areas maintain an overlap rate of 30% to 50% in both the circumferential and axial directions, which ensures the continuity of defect tracking across images while also taking into account scanning efficiency.

[0033] In this embodiment, X-ray radiographic scanning is performed by translating along the central axis of the target insulator with a preset axial step size and rotating around the central axis of the target insulator with a preset angular step size, including any of the following scanning sequences: At the same circumferential angle, radiographs are sequentially taken along the central axis of the target insulator at the axial step size. After completing all radial radiographs at the same circumferential angle, the radiographs are switched to the next circumferential angle around the central axis of the target insulator at a preset angular step size. At the same axial position, radiographs are sequentially taken along the central axis of the target insulator at a preset angular step size. After completing all circumferential radiographs at the same axial position, the radiographs are switched to the next axial position along the central axis of the target insulator at a preset axial step size.

[0034] In this embodiment, the X-ray source moves along the axial direction, and the X-ray beam is incident at an angle, so that the penetration points corresponding to each axial scanning position are distributed radially along the projection surface of the target insulator, that is, radial illumination is achieved by axial movement.

[0035] In specific implementation, in this embodiment, the method for finely locating the partial discharge abnormal area of ​​the GIS basin insulator is achieved by constructing a two-dimensional index grid. This coordinate system is implemented using circumferential perspective indexing. i and radial radiometric index j Using the coordinate axes, each radiographic location is uniquely represented as a radiographic area code. Transmissive area code The index is defined as follows: j This is the radial radiographic index, with a starting value of 1 and an ending value of 1. n 1; i This is the circumferential perspective index, with a starting value of 1 and an ending value of 1. n 2. Among them, n 1 represents the total number of radiographic exposures along the axial direction under a single circumferential angle; n 2 represents the total number of circumferential radiographic scans around the central axis of the target insulator at a single axial position, used to ensure complete coverage of the radiographic imaging within a 360° circumferential range of the insulator at the current axial position. During data acquisition, the radial radiographic index... j The circumferential radiographic index corresponds one-to-one with the image sequence number scanned according to a preset axial step size when the circumferential angle is fixed. i When the axial position is fixed, the image sequence numbers are scanned one by one according to the preset circumferential angle step size.

[0036] Regardless of the scanning order used n 1. All satisfy the following condition: When the X-ray source and detector are in a single radial radiographic sequence, when j = n At time 1, the target end feature of the insulator should appear exactly in the center region of the detector; the target end feature is determined according to the scanning direction. When scanning from the low-voltage side to the high-voltage side, the target end feature is the center conductor of the high-voltage side; when scanning from the high-voltage side to the low-voltage side, the target end feature is the flange end face of the low-voltage side. To achieve a complete scan of the insulator, at each axial position, it is necessary to complete...n One radial radiograph and n Two circumferential radiographs; the order of execution for the two types of radiographs can be determined according to actual needs.

[0037] Both scanning sequences are executed by the scanning control device, which automatically increments the assigned radiographic area code before each radiographic session begins. After completing a full-circumferential or full-axial scan, the corresponding dimensional index is automatically reset. It should be noted that the scanning control device drives the X-ray source and detector to move and rotate along a set path, controls the start and stop of each radiograph, and assigns an area code to each radiograph. The host computer or embedded control software is not limited in this embodiment.

[0038] Combination Figure 4 When using an axial scan followed by a circumferential scan sequence, the scan control device first fixes the current circumferential index. i The corresponding circumferential angle drives the annular rotating body to sequentially complete the radiography of all axial positions along the central axis of the target insulator at a preset axial step length. The scanning direction is from the low-voltage side flange to the high-voltage side center conductor or from the high-voltage side center conductor to the low-voltage side flange.

[0039] In this embodiment, the scanning process of sequentially radiographing along the axial direction at the same circumferential angle and completing all radial radiographs at that angle constitutes one axial scan sequence. Within this single axial scan sequence (radial radiographs generated by the X-ray source moving along the axial direction), the radial radiograph index... j Increasing from 1 to n 1, and when j = n At time 1, the target end feature is located in the central region of the detector. After reaching a preset illumination position, the X-rays remain stationary for a preset duration (e.g., 1-2 minutes) to ensure sufficient X-ray penetration of the target insulator's local area. This allows potential partial discharge defects within the area to generate stable discharge signals, ensuring the UHF sensor can reliably acquire partial discharge signals at that location for subsequent defect location determination. Once this axial scanning sequence is complete... j Automatically reset to 1. i Increment the angle to the next circumferential angle and repeat the axial scanning process described above until... i = n Complete full circumferential coverage in 2 hours. For example: the position of the first circumferential radiograph ( i The radiographic regions with =1 are designated as Z(1,1), Z(1,2), ..., Z(1,1), Z(1,2), ... Z (1, n 1); No. n 2 circumferential radiograph positions ( i = n2) The radiographic area codes are Z( n 2,1), Z( n 2,2), ...,Z ( n 2, n 1).

[0040] When using a sequence of circumferential scanning followed by axial scanning, the scanning control device first fixes the current radial radiographic index. j At the corresponding axial scanning position, the ring-shaped rotating body is driven to rotate around the central axis of the target insulator in preset angular steps. Δ Gradually switch the incident direction of the ray beam to complete a 360° full-circumferential radiograph at the current axial position.

[0041] In this embodiment, the scanning process of sequentially radiographing along the circumferential direction at the same axial position according to angular steps and completing all circumferential radiographs at that axial position constitutes one circumferential radiograph sequence. Within this single circumferential radiograph sequence, i Increasing from 1 to n 2. After the circumferential radiography sequence is completed i Automatically reset to 1. j Incrementally switch to the next axial scan position and repeat the above circumferential scan process. The scan direction is also from the low-pressure side flange to the high-pressure side center conductor, or from the high-pressure side center conductor to the low-pressure side flange, until... j = n The entire scan was completed within 1 hour. Each radiographic position also underwent a radiographic stay of the preset duration to ensure reliable acquisition of partial discharge signals. For example: the first radial radiographic position ( j The radiographic regions with =1 are designated as Z(1,1), Z(2,1), ..., Z(...). n 2,1); No. n 1st radial radiography position ( j = n 1) The radiographic region codes are Z(1, n 1) Z(2, n 1), ..., Z( n 2, n 1).

[0042] all The array forms a full-coverage illumination matrix on the outer surface of the target insulator.

[0043] It should be noted that the radial radiographic index j The correspondence between the X-ray beam and the axial scanning position is achieved through the characteristic of the X-ray beam being incident at an angle.

[0044] Combination Figure 2 and Figure 3 Specifically, X-ray beaml 1. At an angle of inclination θ Incident on the surface of the insulator (schematic outline of the insulator) l The two rotating surfaces ensure that the actual ray penetration points corresponding to each illumination position within a single axial scanning cycle are perpendicular to the central axis of the target insulator. l The projection on the cross section of 3 is l 4. This projection l 4. Distributed sequentially along the normal direction of the surface at the corresponding point. Based on this projection distribution, although the scanning action is performed along the axis, at the data level, the scanning positions of each axis (corresponding to the radial radiographic index) are... j A one-to-one mapping to radially distributed illumination points enables radial illumination indexing. j Characterization of axial scanning action.

[0045] In this embodiment, the scanning location information also includes a radiography time window and the corresponding acquired image. The circumferential radiography index and the radial radiography index allocated for each radiography session are used as radiography area codes, and are associated with the radiography time window and the image to establish a correspondence between the scanning location, time window, and image. The radiography time window is determined by the start and end times of a single radiography session. The association markers employ conventional data binding methods in the art, ensuring a searchable one-to-one correspondence between the radiography area code, the radiography time window, and the corresponding image.

[0046] Step S3: During the X-ray radiography scan, ultra-high frequency partial discharge signals are acquired synchronously. When the ultra-high frequency partial discharge signal meets the preset abnormal conditions, the radiography scan position corresponding to the abnormal signal is determined based on the synchronous timing relationship between the X-ray radiography scan and the acquisition time of the ultra-high frequency partial discharge signal, and the circumferential radiography index and radial radiography index of the radiography scan position are obtained.

[0047] See appendix Figures 4 to 6 In this embodiment, the preset abnormal conditions include: the average amplitude of the synchronously acquired UHF partial discharge signal is 1.5 to 2 times the average amplitude of the partial discharge signal before X-ray irradiation, and the frequency of occurrence of the synchronously acquired UHF partial discharge signal is more than 3 times the frequency of occurrence of the partial discharge signal before X-ray irradiation.

[0048] Depend on Figure 5 and Figure 6 The comparison of PRPD images of partial discharges in insulator air gap defects before and during X-ray irradiation shows that the number of partial discharges increases during X-ray irradiation, and the number of high-amplitude partial discharges also increases.

[0049] Depend on Figure 7It can be seen that, compared with before X-ray irradiation, the average amplitude of partial discharge of insulators increased during irradiation, which was about 1.5 to 2 times the average amplitude of partial discharge before X-ray irradiation. At the same time, the frequency of partial discharge increased significantly, which was more than 3 times that before irradiation.

[0050] Furthermore, determining the radiographic scanning location corresponding to the abnormal signal based on the synchronous timing relationship between the radiographic scanning and the acquisition time of the UHF partial discharge signal includes: The acquisition time of the ultra-high frequency partial discharge signal that meets the preset abnormal conditions is matched with the time window of each radiographic examination. The radiographic scanning position corresponding to the abnormal signal whose acquisition time falls within the time window is determined as the radiographic scanning position corresponding to the abnormal signal.

[0051] Specifically, the synchronization timing between radiographic scanning and UHF partial discharge signal acquisition is executed by the scanning control device, which assigns circumferential radiographic indices to each radiographic scan according to a preset sequence. i Radial radiometric index j This index combination will be used as the radiographic area code. It is bound to and stored with the images acquired by the detector, and the corresponding dimensional index is automatically reset after a full circumferential or full axial scan is completed. Simultaneously, the code for each radiographic region is recorded. Corresponding radiography start time With end time This allows for the determination of each radiotherapy time window. Furthermore, after confirming that the annular rotating body has reached the preset position and stabilized, the scanning control device triggers a synchronous start command for the X-ray source beam emission and the acquisition of ultra-high frequency partial discharge signals, synchronously acquiring ultra-high frequency partial discharge signals and marking the timestamp T. m Then the timestamp T m Located in a certain radiographic time window The partial discharge signal within is correlated with the corresponding irradiated area. This completes the precise mapping between abnormal signals and scanning positions.

[0052] Step S4: Determine the circumferential orientation and radial position of the defect relative to the initial scan position based on the circumferential radiographic index and the radial radiographic index.

[0053] Specifically, determining the circumferential and axial positions of the defect relative to the initial scanning position includes: (1) Construct a two-dimensional index grid composed of circumferential and radial light indices; each cell in the two-dimensional index grid in this embodiment ( i , j A fan-shaped area corresponds to the surface of the target insulator. Each unit is spliced ​​together along the circumferential and radial directions to cover the outer surface of the target insulator.

[0054] (2) Map the radiographic scanning position onto the two-dimensional index grid to obtain the corresponding circumferential radiographic index. i 0 and radial radiometric index j 0; (3) Based on the two-dimensional index grid, according to i 0 and j 0. Determine the circumferential orientation and radial position corresponding to the defect; in, i 0 characterizes the surface of the target insulator as being composed of The defined circumferential angle range, j0, characterizes the surface of the target insulator as being composed of ( j 0-1) / n 1~ j 0 / n The radial range defined by 1, together with the circumferential angular range, constitutes a two-dimensional positioning reference for the defect relative to the initial scanning position; Δ The preset angle step size, n 1 represents the total number of radial radiographs at the same circumferential angle.

[0055] Specifically, the total number of radial radiographs at the same circumferential angle n The method for determining 1 is as follows: ; In the formula, R Let Δ be the projected radius of the target insulator on a cross-section perpendicular to its own central axis. R For two consecutive axial scans along the central axis of the target insulator, the X-rays are at an angle. θ The step size generated radially within the cross-section due to oblique incidence; Δd The preset axial step size, θ Let be the angle between the X-ray beam direction and the central axis of the target insulator, where θ For acute angles, ensuring tanθ A positive value establishes a definite linear relationship between the axial movement of X-rays and radial illumination, thereby achieving efficient and comprehensive detection of the insulator surface.

[0056] Furthermore, the preset axial step size Δd satisfy: In the formula, The diameter of the collimated X-ray beam. The angle between the X-ray beam direction and the central axis of the target insulator. k Use a value of 0.5 to 0.7 to ensure that adjacent scanned areas overlap.

[0057] ,in, The diameter of the collimated X-ray beam; The perimeter of the target insulator (e.g., a basin insulator).

[0058] In this embodiment, the total number of circumferential radiographs at the same axial position .

[0059] It should be noted that the radial range is used to characterize the actual radial position of the defect region on the insulator surface. In specific implementations, this radial range can be determined by relating it to the insulator's projected radius. R Multiplication to actual radial range ( j 0-1) / n 1 R ~ j 0 / n 1 R The projection radius R When X-rays are obliquely transmitted, the equivalent radial projection scale of the effective detection area of ​​the target insulator on the detector imaging plane is determined by the transmission angle and the geometric dimensions of the insulator.

[0060] It is evident from the above that the X-ray and UHF combined GIS insulator defect localization method provided in this embodiment achieves precise locking of the detection area by initially locating the partial discharge source and converging the defect range to the target insulator through an UHF sensor array. By combining axial translation and rotational X-ray scanning, and utilizing the time synchronization mechanism of X-ray imaging and UHF partial discharge signal acquisition, the abnormal discharge signal is precisely mapped to the corresponding scanning position. Finally, the circumferential and radial positions of the defect are directly calculated based on the imaging index of that position. This effectively solves the technical problem of simultaneously acquiring circumferential and radial spatial information of defects in existing technologies, significantly improving the accuracy and efficiency of defect localization while enhancing the reliability of detection under complex structural conditions and reducing the uncertainty of single detection methods.

[0061] In summary, the present invention has the following beneficial effects: 1. Significantly improved positioning accuracy: From initially locating the defect range using UHF radiofrequency and constructing a two-dimensional index grid by combining circumferential and radial radiographic indexes from X-ray imaging, to accurately mapping the abnormal signal to the scanning position through time synchronization, the defect positioning has been improved from coarse positioning of the insulator section to two-dimensional positioning in both the circumferential and radial directions. 2. Improved detection reliability: By simultaneously acquiring ultra-high frequency partial discharge signals during X-ray irradiation and using X-ray excitation to enhance the partial discharge response, the detection capability of weak defects is improved; 3. Strong adaptability to complex structures: By combining axial translation and rotation scanning with multi-position radiographic imaging, the problem of single X-ray imaging blockage is avoided, ensuring the complete acquisition of defect information under complex structures; 4. Improved detection efficiency: Based on ultra-high frequency coarse positioning to lock onto the target insulator for directional scanning, the ineffective X-ray irradiation is greatly reduced.

[0062] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for locating defects in GIS insulators using a combination of X-ray and ultra-high frequency radiation, characterized in that, include: Step 1: Use an ultra-high frequency sensor array to collect partial discharge signals. Based on the arrival time difference of the signals received by multiple sensors in the ultra-high frequency sensor array, perform preliminary location of the partial discharge source and narrow the defect range to the target insulator. Step 2: Using the position corresponding to the center of the detector image during radiographic imaging of any characteristic part at one end of the target insulator as the initial scanning position, the detector translates along the central axis of the target insulator with a preset axial step size and rotates around the central axis of the target insulator with a preset angular step size, performing X-ray radiographic scanning. The scanning position information corresponding to each radiographic scan is recorded. This scanning position information includes at least the circumferential radiographic index and radial radiographic index of the radiographic scan relative to the initial scanning position. The correspondence between the radial radiographic index and the axial scanning position is achieved through the characteristic of the X-ray beam being incident at an angle. The X-ray source moves axially, and with the X-ray beam incident at an angle, the penetration points corresponding to each axial scanning position are radially distributed along the projection surface of the target insulator, thereby representing the axial scanning action at the data level using the radial radiographic index. Step 3: During the X-ray radiography scan, ultra-high frequency (UHF) partial discharge signals are simultaneously acquired. When the UHF partial discharge signal meets preset abnormal conditions, based on the synchronous timing relationship between the X-ray radiography scan and the acquisition time of the UHF partial discharge signal, the radiography scan position corresponding to the abnormal signal is determined, and the circumferential radiography index and radial radiography index of the radiography scan position are obtained. The synchronous timing relationship includes: matching the acquisition time of the UHF partial discharge signal that meets the preset abnormal conditions with the time window of each radiography scan; determining the radiography scan position corresponding to the abnormal signal whose acquisition time falls within the time window as the radiography scan position corresponding to the abnormal signal. The preset abnormal conditions include: the average amplitude of the synchronously acquired UHF partial discharge signal is 1.5 to 2 times the average amplitude of the partial discharge signal before X-ray radiography, and the frequency of occurrence of the synchronously acquired UHF partial discharge signal is more than 3 times the frequency of occurrence of the partial discharge signal before X-ray radiography. Step 4: Construct a two-dimensional index grid consisting of a circumferential light transmission index and a radial light transmission index; map the light transmission scan position onto the two-dimensional index grid to obtain the corresponding circumferential light transmission index i0 and radial light transmission index j0; based on the two-dimensional index grid, determine the circumferential orientation and radial position of the defect according to i0 and j0; wherein, i0 represents that the surface of the target insulator is composed of (i0-1)•Δ ~ i0•Δ The defined circumferential angle range, j0, characterizes the radial range on the surface of the target insulator defined by (j0-1) / n1 ~ j0 / n1. The circumferential angle range and the radial range together constitute a two-dimensional positioning reference for the defect relative to the initial scanning position; Δ The preset angle step size is n1, where n1 is the total number of radial radiographs at the same circumferential angle.

2. The GIS insulator defect location method combining X-ray and UHF spectroscopy according to claim 1, characterized in that, The preliminary location of the partial discharge source based on the time difference of arrival of signals received by multiple sensors in the UHF sensor array specifically includes: By using UHF sensor arrays deployed inside and outside the GIS equipment to collect partial discharge signals in real time, the time difference between the wavefronts of partial discharge signals collected by UHF sensors at different locations is obtained. Based on the distance of each UHF sensor along the internal conductor of the GIS, the propagation speed of electromagnetic waves in the GIS medium, and the time difference, the distance between the partial discharge source and each UHF sensor is calculated, and the calculated position of the partial discharge source is mapped to the target insulator.

3. The GIS insulator defect location method combining X-ray and UHF spectroscopy according to claim 1, characterized in that, The X-ray radiographic scanning process, which involves translating along the central axis of the target insulator with a preset axial step size and rotating around the central axis of the target insulator with a preset angular step size, includes any of the following scanning sequences: At the same circumferential angle, the target insulator is illuminated sequentially along the central axis at the axial step size. After completing all radial illumination at the same circumferential angle, the system switches to the next circumferential angle around the central axis of the target insulator at a preset angular step size. At the same axial position, the target insulator is radiographed sequentially around its central axis at preset angular steps. After completing all circumferential radiographs at that axial position, the system switches to the next axial position along the central axis of the target insulator at preset axial steps.

4. The GIS insulator defect location method combining X-ray and UHF spectroscopy according to claim 1, characterized in that, During the X-ray radiographic scanning, the X-ray source and detector remain at each radiographic position for a preset duration to allow the X-rays to fully penetrate the target insulator and generate an excitation signal that meets the detection requirements at that position.

5. The GIS insulator defect location method combining X-ray and UHF spectroscopy according to claim 1, characterized in that, The scanning position information also includes the radiographic time window and the corresponding acquired image; the circumferential radiographic index and the radial radiographic index are used as radiographic area codes and associated with the radiographic time window and the image to establish the correspondence between the scanning position, time window and image.

6. The GIS insulator defect location method combining X-ray and UHF spectroscopy according to claim 1, characterized in that, The total number of radial radiographs under the same circumferential angle n The method for determining 1 is as follows: ； In the formula, R Let Δ be the projected radius of the target insulator on a cross-section perpendicular to its central axis. d To preset the axial step size, θ Δ is the angle between the X-ray beam direction and the central axis of the target insulator. R For two consecutive axial scans along the central axis of the target insulator, the X-rays are at an angle. θ The step size generated radially within the cross-section due to oblique incidence.

7. The GIS insulator defect location method combining X-ray and UHF spectroscopy according to claim 1, characterized in that, The preset axial step size Δ d satisfy: k · / In the formula, The diameter of the collimated X-ray beam. θ The angle between the X-ray beam direction and the central axis of the target insulator. k Take a value of 0.5 to 0.7.

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