Oil-immersed transformer partial discharge detection method and detection device

Abstract

The present application relates to the technical field of equipment detection, and discloses a kind of oil-immersed transformer partial discharge detection method and detection device, detection method includes the following steps: S 1, with the welding angle of the bottom of the oil tank of transformer as origin establishes coordinate system;S2, according to the projection area of the long side face of the oil tank of transformer determines main measurement surface and auxiliary measurement surface;S3, establish detection strip, the vertical direction center line of detection strip is the route of detection device;Determine the region to be measured and the coordinates of the point to be measured;S4, detection device detects each point to be measured, and the detection result information of main measurement surface is transmitted to control system;S5, control system makes the maximum square closed envelope line for partial discharge abnormal point to be measured;S6, the closed envelope line area on auxiliary measurement surface is detected;S7, partial discharge position marking is carried out.The detection device is used to replace manual ultrasonic wave partial discharge detection, improve the density of ultrasonic wave partial discharge detection, and realize the positioning of discharge fault point.

Description

Technical Field

[0001] This invention relates to the field of equipment testing technology, and in particular to a method and device for detecting partial discharge in an oil-immersed transformer. Background Technology

[0002] When an electrical fault occurs inside an oil-immersed transformer, the transformer oil decomposes and produces acetylene gas. In the early stages of the fault, the acetylene gas dissolves in the transformer oil. When an online oil chromatography monitoring device detects trace amounts (or higher) of acetylene, on-line partial discharge detection needs to be performed to provide important reference for transformer operation strategies.

[0003] Currently, the main methods for detecting partial discharge (PD) in oil-immersed transformers are high-frequency and ultrasonic methods. The high-frequency method uses a high-frequency current sensor to detect PD signals flowing through the grounding lead of the core. However, this method is susceptible to electromagnetic interference, resulting in poor accuracy. Furthermore, the detection results can only provide a qualitative conclusion regarding the presence or absence of PD within the oil-immersed transformer, offering insufficient information for maintenance and requiring comprehensive disassembly, which hinders the reduction of maintenance time. The ultrasonic method has strong anti-interference capabilities and high accuracy, but it requires sufficient detection density to capture PD signals and locate faults in oil-immersed transformers. However, detecting PD in oil-immersed transformers is a high-risk operation, and inspectors typically control the operation time, leading to insufficient detection density and affecting the correct formulation of operating strategies. Therefore, there is a need for a testing device for oil-immersed transformers that can replace manual PD detection and shorten maintenance time. Summary of the Invention

[0004] The purpose of this invention is to provide a partial discharge detection device for oil-immersed transformers, which can replace manual partial discharge detection and reduce maintenance time. This invention also provides a method for partial discharge detection in oil-immersed transformers.

[0005] To achieve the above objectives, the present invention provides a method for detecting partial discharge in an oil-immersed transformer, comprising the following steps: S1. Establish a coordinate system with the bottom welding corner of the transformer tank as the origin, where the vertical upward extension of the bottom of the tank is the Y-axis extension direction, and the direction perpendicular to the Y-axis on the long side of the tank is the X-axis extension direction. S2. Determine the main test surface and auxiliary test surface based on the projected area of ​​the attachments on the long side of the transformer tank. Define the side with the iron core clamp attached on the long side of the tank as surface A and the other side as surface B. Calculate the vertical projected area of ​​the attachments on surface A and surface B on the long side, and take the smaller area as the main test surface and the remaining long side as the auxiliary test surface. S3. Based on the contour information of the main test surface of the fuel tank, the wheel contour spacing of the detection device, and the spacing of the fuel tank accessories on the main test surface, a detection strip is established. The vertical center line of the detection strip is the travel path of the detection device. The electrical parts inside the fuel tank are projected onto the main test surface. The overlapping part between the projected image and the detection strip is corrected into a right-angled quadrilateral. The right-angled quadrilateral is the area to be tested. The sampling level and sampling density of the area to be tested are determined according to the radius of the ultrasonic probe, and the coordinates of the points to be tested are established. S4, the detection device climbs to the main test surface of the oil tank and moves according to the travel route and the coordinates of the test point in step S3. It detects each test point based on the sampling level and sampling density of the test area and transmits the detection result information of the main test surface to the control system. The detection result information includes the test device number, the coordinates of the partial discharge detection point and the partial discharge signal. S5, the control system processes the detection result information, retains the partial discharge signal and coordinate information greater than 0.6mV (millivolt) as the partial discharge abnormal test point, and draws the maximum square closed envelope for the partial discharge abnormal test point; S6. Repeat steps S3 to S4 to perform partial discharge detection on the closed envelope region determined in step S5 on the auxiliary test surface. S7. Based on the amplitude and time difference information of ultrasonic partial discharge from the main and auxiliary test surfaces, and combined with the internal assembly drawing of the oil-immersed transformer, the location of partial discharge is marked.

[0006] Preferably, in step S1, the sum of the distances from the geometric center of the bushing riser of each voltage level to the midpoint of the long side of the oil tank is calculated. Where F is the sum of distances, The value can be 0 or 1. When the person is facing outwards in the structural diagram, 0 represents the left side of the midpoint of the long side, and 1 represents the right side of the midpoint of the long side. A larger value indicates a more balanced structure. Pointing to small The direction is the extension direction of the X-axis.

[0007] Preferably, based on the external structural diagram of the oil-immersed transformer, each bushing riser is projected along the direction perpendicular to the long side of the oil tank to obtain a projection diagram. The sum of the distances from the geometric center of each voltage level bushing riser to the midpoint of the long side of the oil tank is then calculated using the projection diagram. .

[0008] Preferably, in step S1, before establishing the coordinate system, it is determined that the online oil chromatography monitoring device of the oil-immersed transformer has detected acetylene, and chromatographic analysis is performed again to confirm that the dissolved gas components in the oil contain acetylene.

[0009] Preferably, in step S3, the calculation is performed. The X-axis coordinate range of the main measuring surface oil tank is ( , D is the distance between the outer contours of the wheel of the detection device, and N is the integer value obtained by the tail-removal method; calculate The coordinate range of the projection of the main measuring surface appendage along the Y-axis and X-axis is: ,exist Make and Intersecting, among which , , Let be the coordinate interval of the i-th main measuring surface appendage projected onto the X-axis; if there is no such interval, it is recorded as 0. Remove from sequence Afterwards, recorded as Recalculate This forms i square detection strips, where the coordinates of the four endpoints of detection strip i are... ; According to the internal assembly diagram of the oil-immersed transformer, the projections of the various electrical components inside the oil tank onto the main measuring surface are shown. The electrical components include coils, leads, and shielding tubes; The coordinates of the intersection with the detection strip i are: The Y-axis coordinate range of the main measuring surface oil tank is ( , ), , , , For projection The Y-coordinate of the point where the X-axis closed line intersects with stripe i; make =max( , ), =min( , ), and re-obtain the interval The vertical centerline of the detection strip i is the path of the detection device.

[0010] Preferably, in step S3, the detection device performs detection along the centerline of the vertical direction of the detection strip i, wherein the definition is... This is the second region to be tested. This is the area to be tested. For the three regions to be tested, In the second test zone, one test point is placed at intervals of 2.6R, and the number of tests is [number missing]. The rounded integers are used to determine the test points. In the test zone, one test point is placed at intervals of 1.1R, and the number of tests is... The rounded integers are used to determine the test points. In the three test zones, one test point is placed at a interval of 1.6R, and the number of tests is... The truncated integer, R is the radius of the ultrasonic probe.

[0011] Preferably, the detection device in step S4 consists of [ The coordinates are the initial positions, and each test point is measured for 30 seconds; in step S5, when drawing the largest square closed envelope for the partial discharge anomaly test point, the coordinates of the four corners of the closed envelope are obtained. ,in , , , Let be the coordinate symbol of the closed envelope of the largest square.

[0012] The present invention also provides a partial discharge detection device for an oil-immersed transformer, used to implement the partial discharge detection method for an oil-immersed transformer described in any of the above technical solutions, including a detection vehicle and a lifting platform. The detection vehicle includes a drive motor, a permanent magnet wheel connected to the drive motor via a transmission device, and an integrated controller. An angular velocity sensor is also provided between the transmission device and the permanent magnet wheel, and the angular velocity sensor is used to detect the travel distance of the permanent magnet wheel. The integrated controller includes a signal transmission module, a telescopic device, a magnetic base, and a buffer spring. The upper end of the buffer spring is connected to the telescopic device, and the lower end is connected to the magnetic base. An ultrasonic sensor is installed inside the magnetic base, and a pressure sensor is installed on the outside of the magnetic base. The ultrasonic sensor is used for partial discharge ultrasonic detection, and the pressure sensor is used to detect the pressure between the magnetic base and the surface of the oil tank. Both the ultrasonic sensor and the pressure sensor are electrically connected to the signal transmission module. The lifting platform includes a moving track, a lifting column, and a ladder. The lifting column is guided and mounted on the moving track, and the ladder is arranged at the top of the lifting column. The ladder is provided with a testing compartment for storing the testing vehicle and a movement groove for moving the permanent magnet wheels. One end of the movement groove is connected to the testing compartment, and the other end is used to fit the oil tank to be tested.

[0013] Preferably, the ladder includes a horizontal part and an arc part, the arc part being a quarter circle, the bottom end of the arc part being tangentially connected to the horizontal part, and the top end being tangentially fitted to the surface to be measured of the oil tank.

[0014] Preferably, there are two sets of pressure sensors, and the two sets of pressure sensors are arranged symmetrically about the center line of the magnetic base.

[0015] Compared with the prior art, the partial discharge detection method and device for oil-immersed transformers of this invention have the following advantages: the travel route of the detection device and the coordinates of the test point are determined based on the contour information of the main and auxiliary test surfaces of the oil tank, the wheel contour distance of the detection device, and the distance of the accessories. The detection device is used to perform ultrasonic detection on the main and auxiliary test surfaces to determine the location of the partial discharge, replacing manual ultrasonic partial discharge detection, increasing the density of ultrasonic partial discharge detection, realizing the location of the discharge fault point, and also improving the correctness of the subsequent operation and maintenance strategy and reducing the disassembly and repair period. Attached Figure Description

[0016] Figure 1 This is a schematic flowchart of the partial discharge detection method for oil-immersed transformers of the present invention; Figure 2 This is a schematic diagram of the structure of the testing vehicle of the partial discharge detection device for oil-immersed transformers of the present invention; Figure 3 yes Figure 2 A schematic diagram of the integrated controller of the testing vehicle; Figure 4 This is a schematic diagram of the lifting platform of the oil-immersed transformer partial discharge detection device of the present invention.

[0017] In the diagram, 1. Drive motor, 2. Transmission device, 3. Battery module, 4. Angular velocity sensor, 5. Permanent magnet wheel, 6. Integrated controller, 21. Signal transmission module, 22. Telescopic device, 23. Buffer spring, 24. Magnetic base, 25. Pressure sensor, 26. Ultrasonic sensor, 31. Detection chamber, 32. Ladder, 33. Lifting column, 34. Moving track. Detailed Implementation

[0018] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0019] A preferred embodiment of the partial discharge detection method for an oil-immersed transformer according to the present invention is as follows: Figure 1 As shown, the partial discharge detection method for oil-immersed transformers includes the following steps: S1. Establish a coordinate system with the bottom welding corner of the transformer tank as the origin, where the vertical upward extension of the bottom of the tank is the Y-axis extension direction, and the direction perpendicular to the Y-axis on the long side of the tank is the X-axis extension direction. S2. Determine the main test surface and auxiliary test surface based on the projected area of ​​the attachments on the long side of the transformer tank. Define the side with the iron core clamp attached on the long side of the tank as surface A and the other side as surface B. Calculate the vertical projected area of ​​the attachments on surface A and surface B on the long side, and take the smaller area as the main test surface and the remaining long side as the auxiliary test surface. S3. Based on the contour information of the main test surface of the fuel tank, the wheel contour spacing of the detection device, and the spacing of the fuel tank accessories on the main test surface, a detection strip is established. The vertical center line of the detection strip is the travel path of the detection device. The electrical parts inside the fuel tank are projected onto the main test surface. The overlapping part between the projected image and the detection strip is corrected into a right-angled quadrilateral. The right-angled quadrilateral is the area to be tested. The sampling level and sampling density of the area to be tested are determined according to the radius of the ultrasonic probe, and the coordinates of the points to be tested are established. S4, the detection device climbs to the main test surface of the oil tank and moves according to the travel route and the coordinates of the test point in step S3. It detects each test point based on the sampling level and sampling density of the test area and transmits the detection result information of the main test surface to the control system. The detection result information includes the test device number, the coordinates of the partial discharge detection point and the partial discharge signal. S5, the control system processes the detection result information, retains the partial discharge signal and coordinate information greater than 0.6mV (millivolt) as the partial discharge abnormal test point, and draws the maximum square closed envelope for the partial discharge abnormal test point; S6. Repeat steps S3 to S4 to perform partial discharge detection on the closed envelope region determined in step S5 on the auxiliary test surface. S7. Based on the amplitude and time difference information of ultrasonic partial discharge from the main and auxiliary test surfaces, and combined with the internal assembly drawing of the oil-immersed transformer, the location of partial discharge is marked.

[0020] In step S1, establishing a coordinate system can determine the extension directions of the X and Y axes, which facilitates the determination of the travel path of the detection device, the coordinates of the detection points, etc. in subsequent processes.

[0021] In step S2, the larger the projected area of ​​the appendages on the long side of the transformer tank, the more areas the detection device needs to detect along its path on the tank. By determining the long side with a smaller projected area as the main test surface, the range to be tested can be determined first as a whole, and then the area determined by the closed envelope can be detected on the auxiliary test surface, thereby improving detection efficiency.

[0022] In step S3, the contour information of the main test surface of the fuel tank, the wheel contour spacing of the detection device, and the spacing of the fuel tank accessories on the main test surface will affect the travel path of the detection device and the detection object when traveling. The contour information will affect the obstacles when the detection device travels, the wheel contour spacing will affect the detection center when the detection device travels, and the spacing of the fuel tank accessories on the main test surface will affect the distribution of the travel path. Determining the travel path based on these factors can ensure that the detection device can perform detailed detection on the main test surface, thereby improving detection efficiency and detection density.

[0023] In steps S4 and S5, the detection device transmits the detection result information to the control system in real time, which facilitates the control system to process the detection result information and determine the partial discharge abnormality test point. This makes it easier to repeat the test on the auxiliary test surface only for the partial discharge abnormality test point in step S6, which is highly efficient.

[0024] This partial discharge detection method for oil-immersed transformers determines the travel route of the detection device and the coordinates of the test point based on the contour information of the main and auxiliary test surfaces of the oil tank, the wheel contour distance of the detection device, and the distance of the accessories. The detection device is used to perform ultrasonic detection on the main and auxiliary test surfaces to determine the location of partial discharge, replacing manual ultrasonic partial discharge detection, increasing the density of ultrasonic partial discharge detection, realizing the location of discharge fault points, and also improving the correctness of subsequent operation and maintenance strategies and reducing the disassembly and repair period.

[0025] Preferably, in step S1, the sum of the distances from the geometric center of the bushing riser of each voltage level to the midpoint of the long side of the oil tank is calculated. Where F is the sum of distances, The value can be 0 or 1. When the person is facing outwards in the structural diagram, 0 represents the left side of the midpoint of the long side, and 1 represents the right side of the midpoint of the long side. A larger value indicates a more balanced structure. Pointing to small The direction is the extension direction of the X-axis.

[0026] The distance from the geometric center of each voltage level bushing riser to the midpoint of the long side of the oil tank is determined by using the midpoint of the long side of the oil tank. The larger the sum of these distances, the more dispersed the distribution of bushing risers for each voltage level on the surface. Larger numerical values ​​indicate a more dispersed distribution. Pointing to small The direction is the extension direction of the X-axis, which makes it easy to determine the direction of the X-axis.

[0027] Preferably, based on the external structural diagram of the oil-immersed transformer, each bushing riser is projected along the direction perpendicular to the long side of the oil tank to obtain a projection diagram. The sum of the distances from the geometric center of each voltage level bushing riser to the midpoint of the long side of the oil tank is then calculated using the projection diagram. .

[0028] The sum of the distances from the geometric center of each bushing riser to the midpoint of the long side of the oil tank is determined by obtaining the projection diagram of each bushing riser along the direction perpendicular to the long side of the oil tank. Simplified The determination method can be achieved using drafting software, saving manpower.

[0029] Preferably, in step S1, before establishing the coordinate system, it is determined that the online oil chromatography monitoring device of the oil-immersed transformer has detected acetylene, and chromatographic analysis is performed again to confirm that the dissolved gas components in the oil contain acetylene.

[0030] By confirming the presence of acetylene in the dissolved gas components of the oil through chromatographic analysis, losses caused by false alarms in the online oil chromatography monitoring device can be avoided.

[0031] Preferably, in step S3, the calculation is performed. The X-axis coordinate range of the main measuring surface oil tank is ( , D is the distance between the outer contours of the wheel of the detection device, and N is the integer value obtained by the tail-removal method; calculate The coordinate range of the projection of the main measuring surface appendage along the Y-axis and X-axis is: ,exist Make and Intersecting, among which , , Let be the coordinate interval of the i-th main measuring surface appendage projected onto the X-axis; if there is no such interval, it is recorded as 0. Remove from sequence Afterwards, recorded as Recalculate This forms i square detection strips, where the coordinates of the four endpoints of detection strip i are... ; According to the internal assembly diagram of the oil-immersed transformer, the projections of the various electrical components inside the oil tank onto the main measuring surface are shown. The electrical components include coils, leads, and shielding tubes; The coordinates of the intersection with the detection strip i are: The Y-axis coordinate range of the main measuring surface oil tank is ( , ), , , , For projection The Y-coordinate of the point where the X-axis closed line intersects with stripe i; make =max( , ), =min( , ), and re-obtain the interval The vertical centerline of the detection strip i is the path of the detection device.

[0032] In this embodiment, the number of detection strips that the detection device needs to travel can be determined by the X-axis coordinate range of the main test surface oil tank and its relationship with the distance between the main test surface and the wheel profile, which facilitates the accurate division of the travel path during detection.

[0033] The coordinate range of the projection of the main test surface attachment on the X-axis will affect the distribution of the detection strips. Each square detection strip is arranged around the projection range of an attachment, which allows for ultrasonic testing of each attachment.

[0034] The area formed by the intersection of the projection M of the electrical components inside the oil-immersed transformer onto the main test surface and the test strip i is the area where the testing device needs to test the electrical components. Determining the intersection of this area with the X-axis closed line and the Y-axis of the test strip i can determine the specific location of this area, making it easier for the testing device to test it.

[0035] Preferably, in step S3, the detection device performs detection along the centerline of the vertical direction of the detection strip i, wherein the definition is... This is the second region to be tested. This is the area to be tested. For the three regions to be tested, In the second test zone, one test point is placed at intervals of 2.6R, and the number of tests is [number missing]. The rounded integers are used to determine the test points. In the test zone, one test point is placed at intervals of 1.1R, and the number of tests is... The rounded integers are used to determine the test points. In the three test zones, one test point is placed at a interval of 1.6R, and the number of tests is... The truncated integer, R is the radius of the ultrasonic probe.

[0036] In this embodiment, the main test surface is divided into different test areas. The number of electrical devices and the projected area of ​​accessories are different in different test areas. Setting more test points in the test area with more electrical devices and more projected area of ​​accessories can improve the test efficiency.

[0037] Preferably, the detection device in step S4 consists of [ The coordinates are the initial positions, and each test point is measured for 30 seconds; in step S5, when drawing the largest square closed envelope for the partial discharge anomaly test point, the coordinates of the four corners of the closed envelope are obtained. ,in , , , Let be the coordinate symbol of the closed envelope of the largest square.

[0038] A 30-second measurement is performed at each test point; this sufficient detection time ensures the accuracy of the test results. In this embodiment, the pressure value of the pressure sensor is greater than 27N during measurement, which ensures the adhesion between the ultrasonic sensor and the outer surface of the transformer tank, and determines that the contact surface is flat and does not warp.

[0039] The present invention also provides a preferred embodiment of a partial discharge detection device for oil-immersed transformers, such as... Figures 2 to 4 As shown, the partial discharge detection method for oil-immersed transformers used to implement any of the above embodiments includes a detection vehicle and a lifting platform. The detection vehicle is used to move on the surface of the transformer tank and perform ultrasonic detection, and the lifting platform is used to send the detection vehicle to the initial detection position.

[0040] The testing vehicle includes a drive motor 1, a transmission device 2, permanent magnet wheels 5, and an integrated controller 6. The drive motor 1 and the permanent magnet wheels 5 are connected via the transmission device 2, and the drive motor 1, transmission device 2, and permanent magnet wheels 5 are connected via a drive shaft. There are four permanent magnet wheels 5, which are respectively arranged at the four corners of the testing vehicle. The drive motor 1 simultaneously provides power to the four permanent magnets and the test vehicle.

[0041] The transformer casing is made of iron and uses permanent magnet wheels 5 for vertical attraction. These wheels are made of neodymium iron boron powder and rubber, with a magnetic field strength of 1.5-2.3T (Tesla) to ensure effective magnetic attraction. All permanent magnet wheels 5 have a braking function. Angular velocity sensors 4 are installed on the drive shaft between the permanent magnet wheels 5 at the front of the testing vehicle and the transmission device 2. These sensors have integration capabilities and can detect the travel distance of the permanent magnet wheels 5 by measuring their rotational angular velocity.

[0042] The testing vehicle is also equipped with a battery module 3, which consists of three independent battery packs. One of the three battery packs powers all moving parts, one powers the ultrasonic sensor 26, and one powers the angular velocity sensor 4 and the integrated controller 6. The three battery packs operate independently and power different structures, reducing mutual interference and especially avoiding the influence of electromagnetic waves from the rotating motor, thus ensuring data validity. In this embodiment, all three battery packs are ternary lithium batteries. The battery pack powering all moving parts preferably has a capacity of 6000-8500 mAh, the battery pack powering the ultrasonic sensor 26 preferably has a capacity of 3000-5500 mAh, and the battery pack powering the angular velocity sensor 4 and the integrated controller 6 preferably has a capacity of 2700-3500 mAh.

[0043] The integrated controller 6 includes a signal transmission module 21, a telescopic device 22, a magnetic base 24, and a buffer spring 23. The upper end of the buffer spring 23 is connected to the telescopic device 22, and the lower end is connected to the magnetic base 24. The telescopic device 22 is an electric telescopic device, and the buffer spring 23 is welded to its extended lower end. The magnetic base 24 has a concave structure with a downward groove in the middle. The lower end of the buffer spring 23 is welded to the protruding part around the groove of the magnetic base 24.

[0044] An ultrasonic sensor 26 is also installed inside the concave cavity of the magnetic base 24. The ultrasonic sensor 26 is fixed by screw rotation and is used for partial discharge ultrasonic detection of the transformer. A pressure sensor 25 is installed on the outside of the magnetic base 24. The pressure sensor 25 is fixedly connected to the magnetic base 24 by adhesive and is used to detect the pressure between the magnetic base 24 and the surface of the oil tank.

[0045] Both the ultrasonic sensor 26 and the pressure sensor 25 are electrically connected to the signal transmission module 21 to transmit the detected pressure signal and detection result information to the signal transmission module 21 for calculation and analysis by the integrated controller 6. In this embodiment, the ultrasonic sensor 26 and the pressure sensor 25 are connected to the integrated controller 6 via signal lines. Their power supply and signal lines are wrapped in fiberglass tubing to improve service life, reduce external interference, and ensure accurate results.

[0046] The lifting platform includes a moving track 34, a lifting column 33, and a ladder 32. The lifting column 33 is guided and mounted on the moving track 34, allowing it to move flexibly within the track along its extension direction. In this embodiment, the length of the moving track 34 is 35-39cm. The ladder 32 is fixedly arranged at the top of the lifting column 33. The lifting column 33 can move flexibly in the vertical direction, with a vertical movement range of 0-35cm, to adjust the height of the ladder 32.

[0047] The ladder 32 is equipped with a testing chamber 31 and a movement trough. The testing chamber 31 is located at one end of the ladder 32 and is used to store the testing vehicle. The testing chamber 31 has a charging interface to charge the testing vehicle and extend its working time. The movement trough is arranged along the extension direction of the ladder 32. One end of the movement trough is connected to the testing chamber 31, and the other end is used to attach to the fuel tank to be tested. The testing vehicle can climb up the movement trough from the testing chamber 31 to the upper level.

[0048] In this embodiment, the ladder 32 is made of Q235 carbon steel and coated with anti-corrosion paint. A movement groove is provided on each of the left and right sides of the ladder 32, matching the wheels on both sides of the inspection vehicle. In this embodiment, the width of the movement groove is 1.03 times the width of a single permanent magnet wheel 5, and the depth is 0.37 times the radius of 55 permanent magnet wheels. Along the extension direction of the movement grooves, the left and right movement grooves on the ladder 32 are welded together every 3 cm using Q235 carbon steel, improving the structural strength of the ladder 32.

[0049] Preferably, the ladder 32 includes a horizontal part and an arc part. The arc part is a quarter circle. The bottom end of the arc part is tangentially connected to the horizontal part, and the top end is used to tangentially fit with the surface to be measured of the oil tank.

[0050] The horizontal portion of the ladder 32 is tangent to the arc portion, and its top is tangent to the surface of the fuel tank to be tested, ensuring the stability of the inspection vehicle's movement. In this embodiment, the horizontal portion is 1.9 times the length of the inspection vehicle, and the radius of the arc portion is 2.7 times the height of the inspection vehicle. The vertical distance from the apex of the arc portion to the horizontal portion is 16-17 cm.

[0051] Preferably, there are two sets of pressure sensors 25, and the two sets of pressure sensors 25 are arranged symmetrically about the center line of the magnetic base 24.

[0052] Two sets of pressure sensors 25 can detect the pressure on both sides of the magnetic base 24 respectively. By comparing the pressure on both sides, the magnetic base 24 can be prevented from warping, ensuring the fit between the magnetic base 24, the ultrasonic sensor 26 and the outer surface of the transformer tank.

[0053] Preferably, the ladder 32 is carried by a carrier, which has a perimeter perception function consisting of visible light and lidar, stores detailed coordinate map information of the plant, can navigate autonomously, and can interact with encrypted information from the outside through the Internet of Things.

[0054] In summary, this invention provides a method and device for detecting partial discharge in an oil-immersed transformer. It determines the travel route and coordinates of the test point based on the contour information of the main and auxiliary test surfaces of the oil tank, the wheel profile distance of the detection device, and the distance between accessories. The detection device performs ultrasonic testing on the main and auxiliary test surfaces to determine the location of the partial discharge, replacing manual ultrasonic partial discharge detection. This increases the density of ultrasonic partial discharge detection, enables the localization of discharge fault points, improves the accuracy of subsequent maintenance strategies, and reduces the disassembly and repair period.

[0055] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A method for detecting partial discharge in an oil-immersed transformer, characterized in that, Includes the following steps: S1. Establish a coordinate system with the bottom welding corner of the transformer tank as the origin, where the vertical upward extension of the bottom of the tank is the Y-axis extension direction, and the direction perpendicular to the Y-axis on the long side of the tank is the X-axis extension direction. S2. Determine the main test surface and auxiliary test surface based on the projected area of ​​the attachments on the long side of the transformer tank. Define the side with the iron core clamp attached on the long side of the tank as surface A and the other side as surface B. Calculate the vertical projected area of ​​the attachments on surface A and surface B on the long side, and take the smaller area as the main test surface and the remaining long side as the auxiliary test surface. S3. Based on the contour information of the main test surface of the fuel tank, the wheel contour spacing of the detection device, and the spacing of the fuel tank accessories on the main test surface, a detection strip is established. The vertical center line of the detection strip is the travel path of the detection device. The electrical parts inside the fuel tank are projected onto the main test surface. The overlapping part between the projected image and the detection strip is corrected into a right-angled quadrilateral. The right-angled quadrilateral is the area to be tested. The sampling level and sampling density of the area to be tested are determined according to the radius of the ultrasonic probe, and the coordinates of the points to be tested are established. S4, the detection device climbs to the main test surface of the oil tank and moves according to the travel route and the coordinates of the test point in step S3. It detects each test point based on the sampling level and sampling density of the test area and transmits the detection result information of the main test surface to the control system. The detection result information includes the test device number, the coordinates of the partial discharge detection point and the partial discharge signal. S5, the control system processes the detection result information, retains the partial discharge signal and coordinate information greater than 0.6mV (millivolt) as the partial discharge abnormal test point, and draws the maximum square closed envelope for the partial discharge abnormal test point; S6. Repeat steps S3 to S4 to perform partial discharge detection on the closed envelope region determined in step S5 on the auxiliary test surface. S7. Based on the amplitude and time difference information of ultrasonic partial discharge from the main and auxiliary test surfaces, and combined with the internal assembly drawing of the oil-immersed transformer, the location of partial discharge is marked.

2. The method for detecting partial discharge in an oil-immersed transformer according to claim 1, characterized in that, In step S1, the sum of the distances from the geometric center of the bushing riser of each voltage level to the midpoint of the long side of the oil tank is calculated. Where F is the sum of distances, The value can be 0 or 1. When the person is facing outwards in the structural diagram, 0 represents the left side of the midpoint of the long side, and 1 represents the right side of the midpoint of the long side. A larger value indicates a more balanced structure. Pointing to small The direction is the extension direction of the X-axis.

3. The method for detecting partial discharge in an oil-immersed transformer according to claim 2, characterized in that, Based on the external structural diagram of the oil-immersed transformer, project each bushing riser onto the direction perpendicular to the long side of the oil tank to obtain a projection diagram. Use the projection diagram to calculate the sum of the distances from the geometric center of each voltage level bushing riser to the midpoint of the long side of the oil tank. .

4. The method for detecting partial discharge in an oil-immersed transformer according to any one of claims 1-3, characterized in that, In step S1, before establishing the coordinate system, it is determined that the online oil chromatography monitoring device of the oil-immersed transformer has detected acetylene, and chromatographic analysis is performed again to confirm that the dissolved gas components in the oil contain acetylene.

5. The method for detecting partial discharge in an oil-immersed transformer according to any one of claims 1-3, characterized in that, In step S3, calculate The X-axis coordinate range of the main measuring surface oil tank is ( , D is the distance between the outer contours of the wheel of the detection device, and N is the integer value obtained by the tail-removal method; calculate The coordinate range of the projection of the main measuring surface appendage along the Y-axis and X-axis is: ,exist Make and Intersecting, among which , , Let be the coordinate interval of the i-th main measuring surface appendage projected onto the X-axis; if there is no such interval, it is recorded as 0. Remove from sequence Afterwards, recorded as Recalculate This forms i square detection strips, where the coordinates of the four endpoints of detection strip i are... ; According to the internal assembly diagram of the oil-immersed transformer, the projections of the various electrical components inside the oil tank onto the main measuring surface are shown. The electrical components include coils, leads, and shielding tubes; The coordinates of the intersection with the detection strip i are: The Y-axis coordinate range of the main measuring surface oil tank is ( , ), , , , For projection The Y-coordinate of the point where the X-axis closed line intersects with stripe i; make =max( , ), =min( , ), and re-obtain the interval The vertical centerline of the detection strip i is the path of the detection device.

6. The method for detecting partial discharge in an oil-immersed transformer according to claim 5, characterized in that, In step S3, the detection device performs detection along the centerline of the vertical direction of the detection strip i, where defined... This is the second region to be tested. This is the area to be tested. For the three regions to be tested, In the second test zone, one test point is placed at intervals of 2.6R, and the number of tests is [number missing]. The rounded integers are used to determine the test points. In the test zone, one test point is placed at intervals of 1.1R, and the number of tests is... The rounded integers are used to determine the test points. In the three test zones, one test point is placed at a interval of 1.6R, and the number of tests is... The truncated integer, R is the radius of the ultrasonic probe.

7. The method for detecting partial discharge in an oil-immersed transformer according to claim 6, characterized in that, In step S4, the detection device consists of [ The coordinates are the initial positions, and each test point is measured for 30 seconds; in step S5, when drawing the largest square closed envelope for the partial discharge anomaly test point, the coordinates of the four corners of the closed envelope are obtained. ,in , , , Let be the coordinate symbol of the closed envelope of the largest square.

8. A partial discharge detection device for an oil-immersed transformer, used to implement the partial discharge detection method for an oil-immersed transformer according to any one of claims 1-7, characterized in that, The system includes a testing vehicle and a lifting platform. The testing vehicle includes a drive motor, a permanent magnet wheel connected to the drive motor via a transmission device, and an integrated controller. An angular velocity sensor is also installed between the transmission device and the permanent magnet wheel. The angular velocity sensor is used to detect the travel distance of the permanent magnet wheel. The integrated controller includes a signal transmission module, a telescopic device, a magnetic base, and a buffer spring. The upper end of the buffer spring is connected to the telescopic device, and the lower end is connected to the magnetic base. An ultrasonic sensor is installed inside the magnetic base, and a pressure sensor is installed on the outside of the magnetic base. The ultrasonic sensor is used for partial discharge ultrasonic detection, and the pressure sensor is used to detect the pressure between the magnetic base and the surface of the oil tank. Both the ultrasonic sensor and the pressure sensor are electrically connected to the signal transmission module. The lifting platform includes a moving track, a lifting column, and a ladder. The lifting column is guided and mounted on the moving track, and the ladder is arranged at the top of the lifting column. The ladder is provided with a testing compartment for storing the testing vehicle and a movement groove for moving the permanent magnet wheels. One end of the movement groove is connected to the testing compartment, and the other end is used to fit the oil tank to be tested.

9. The partial discharge detection device for an oil-immersed transformer according to claim 8, characterized in that, The ladder includes a horizontal section and an arc section. The arc section is a quarter circle. The bottom end of the arc section is tangentially connected to the horizontal section, and the top end is used to tangentially fit with the surface to be measured of the oil tank.

10. The partial discharge detection device for an oil-immersed transformer according to claim 8, characterized in that, There are two sets of pressure sensors, which are arranged symmetrically about the center line of the magnetic base.

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