Test apparatus for bubble discharge in transformer insulating oil

Abstract

This invention discloses a bubble discharge test device in transformer insulating oil, belonging to the technical field of transformer testing equipment. It includes a test chamber containing insulating oil. Inside the test chamber are simulated heating and discharge components, with the simulated discharge component located above the simulated heating component. Outside the test chamber are an insulating oil filter, a bubble injection component, and an acoustic imaging monitoring component. The simulated discharge component includes a parallel, vertically arranged grounding electrode plate and a high-voltage electrode plate, as well as a distance adjustment mechanism connected to the high-voltage electrode plate. The acoustic imaging monitoring component is located above the simulated discharge component. This invention can accurately and comprehensively simulate the discharge characteristics of bubbles in transformer insulating oil.

Description

Technical Field

[0001] This invention belongs to the technical field of transformer testing equipment, specifically relating to a device for testing bubble discharge in transformer insulating oil. Background Technology

[0002] Transformers are a crucial component of ultra-high voltage (UHV) converter stations, and their safe operation has a significant impact on the power transmission system. One of the most significant factors affecting transformer safety is its insulation performance. Transformers typically employ an oil-paper composite insulation structure, where the insulating oil serves a dual function of insulation and cooling. During operation, factors such as core heating and the properties of the insulating paper can cause air bubbles to form in the insulating oil, thereby reducing its insulation performance and creating safety hazards. However, air bubbles in the insulating oil are unavoidable; therefore, it is necessary to study the extent to which air bubbles affect insulation performance.

[0003] Patent document CN 112345899 A discloses an experimental device for bubble discharge in flowing insulating oil, including a main oil channel, circulation and filtration equipment, and an automatic bubble injection device. This device utilizes gravitational potential energy to drive the flow of insulating oil, avoiding microbubble contamination caused by centrifugal pumps. It can effectively simulate the oil flow state inside a transformer, enabling discharge experiments under different flow rates, bubble numbers, bubble sizes, and electrode spacing conditions. It also features two circulation paths, one with filtration and one without filtration, meeting experimental requirements under various operating conditions. Therefore, this system can provide an experimental platform for studying the discharge mechanism of insulating oil containing bubbles. However, this invention uses a unidirectional flow of insulating oil through a circulation channel for simulation, which does not match the actual movement of insulating oil during transformer operation, leading to inaccurate simulation experiments.

[0004] Patent document CN 114879091 A discloses a device for simulating defects caused by air bubbles in the inter-turn insulation of a transformer. The device includes a main body filled with transformer oil; an incompletely sealed insulating structure is installed within the transformer oil, trapping air bubbles within the insulating structure; and an electrode structure is installed on the outside of the insulating structure. This electrode structure generates an electric field through an external power supply to simulate the discharge characteristics of the air bubbles within the insulating structure. However, this invention only simulates the problem by introducing air bubbles, and cannot control the bubble position. The simulation factors are relatively singular, thus failing to accurately and comprehensively study the impact of air bubbles within the transformer insulating oil on insulation performance. Summary of the Invention

[0005] In view of this, the present invention addresses the shortcomings of the prior art by providing a test device for bubble discharge in transformer insulating oil, which facilitates accurate and comprehensive study of the impact of bubbles in transformer insulating oil on insulation performance.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a bubble discharge test device in transformer insulating oil, comprising a test chamber, wherein insulating oil is placed inside the test chamber, and a simulated heating component and a simulated discharge component are arranged inside the test chamber, wherein the simulated discharge component is located above the simulated heating component, and an insulating oil filtering component, a bubble injection component, and an acoustic imaging monitoring component are arranged outside the test chamber; the simulated discharge component includes a parallel vertically arranged grounding electrode plate and a high-voltage electrode plate, and a distance adjustment mechanism connected to the high-voltage electrode plate; the acoustic imaging monitoring component is located above the simulated discharge component.

[0007] Furthermore, the simulated heating component includes a heating column, a turntable, and a motor. The bottom of the test chamber is provided with a mounting hole, a bearing seat is provided in the mounting hole, a bearing is provided inside the bearing seat, a shaft is provided inside the bearing, the upper end of the shaft is located inside the test chamber, and the turntable is provided at the end of the shaft. Multiple heating columns are provided on the turntable, and the lower end of the shaft is connected to the rotating shaft of the motor through a coupling.

[0008] Furthermore, the bubble injection component includes a compressed gas cylinder, a pressure reducing valve, a gas tube, an injection needle, and a position adjustment mechanism. A through hole is provided on the front side of the test chamber, and a rubber pad is fixedly installed in the through hole. The injection needle is inserted into the rubber pad, and the position adjustment mechanism is provided on the outside of the rubber pad. The injection needle is connected to the position adjustment mechanism.

[0009] Furthermore, the distance adjustment mechanism includes a support rod, a telescopic sleeve, and a handle. An opening is provided on one side of the test chamber, and a sleeve is fixedly installed in the opening. One end of the support rod is connected to the high-voltage electrode plate, and the other end passes through the sleeve and is connected to the handle. The telescopic sleeve is sleeved on the support rod, and one end is sealed to the support rod, while the other end is sealed to the inner wall of the test chamber.

[0010] Furthermore, the insulating oil filtration component includes a pump body and an oil filter. The inlet of the pump body is connected to the lower part of the test chamber, the outlet of the pump body is connected to the inlet of the oil filter, and the outlet of the oil filter is connected to the upper part of the test chamber.

[0011] Furthermore, the acoustic imaging monitoring component includes an array of ultrasonic probes, which emit multiple ultrasonic beams. By adjusting the time difference between the different beams, acoustic scanning can be achieved within the observation range. When a discharge bubble passes through the scanning area, it will reflect an echo, providing information on its position, size, and speed of movement, thereby enabling the monitoring of the discharge bubble.

[0012] Furthermore, a mechanical seal is provided at the junction of the shaft and the bearing housing.

[0013] Furthermore, the position adjustment mechanism includes a bracket and a screw sleeve. The bracket is fixed to the front side of the test chamber, and the screw sleeve is rotatably mounted on the bracket. A connecting block is provided at the connection between the injection needle and the trachea. The connecting block is threaded on the outside and threadedly connected to the screw sleeve.

[0014] Furthermore, a protruding strip is provided on the inner side of the sleeve, and a groove is provided on the support rod, with the protruding strip connected to the groove.

[0015] Furthermore, the array ultrasonic probe is disposed on the top of the test chamber, and a heat-insulating solid coupling layer is disposed between the array ultrasonic probe and the test chamber.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0017] 1. This invention provides a test device for bubble discharge in transformer insulating oil. A simulated heating component is installed at the bottom of the test chamber to induce convection in the insulating oil, simulating the convection caused by the heating of the transformer core during operation. The simulated discharge component inside the test chamber adjusts the distance between the high-voltage electrode plate and the grounding electrode plate via a distance adjustment mechanism, simulating the discharge characteristics of bubbles in the insulating oil under different electric field strengths. A bubble injection component outside the test chamber can inject bubbles between the high-voltage electrode plate and the grounding electrode plate, and control the size and position of the bubbles. This application, by simulating multiple factors, can comprehensively and accurately demonstrate the impact of bubbles in transformer insulating oil on insulation performance.

[0018] 2. The present invention provides a test device for bubble discharge in transformer insulating oil. In the simulated heating component, a motor drives a turntable, causing multiple heating columns on it to rotate. On the one hand, this heats the insulating oil in the lower part of the test chamber, forming upper and lower convection. On the other hand, the rotation of the heating columns increases the range and speed of heat flow. Moreover, the discharge of bubbles under different convection conditions can be simulated by adjusting the rotation speed. In addition, the shaft connected to the motor shaft is connected to the bearing seat through a mechanical seal to prevent leakage of insulating oil.

[0019] 3. The present invention provides an acoustic imaging monitoring component above the simulated discharge component, including an array of ultrasonic probes. The probes emit multiple ultrasonic beams, and the time difference between the emission of different beams is adjusted to achieve acoustic scanning within the observation range. When a discharge bubble passes through the scanning area, it will reflect an echo, providing information on its position, size, and speed of movement, thereby enabling the monitoring of the discharge bubble.

[0020] 4. In the bubble injection component of the present invention, a compressed gas cylinder, a pressure reducing valve, a gas pipe, and an injection needle are connected in sequence. A connecting block is provided at the connection between the gas pipe and the injection needle. The connecting block is threadedly connected to a screw sleeve. By turning the screw sleeve, the injection needle and the connecting block can be moved horizontally, thereby stably controlling the length of the injection needle entering the test chamber and adjusting the position of the bubble.

[0021] 5. In the distance adjustment mechanism of the present invention, the support rod passes through the sleeve and is limited by the protrusion and groove, so that it moves horizontally. The part of the support rod inside the test chamber is fitted with a telescopic sleeve, one end of which is sealed to the support rod and the other end of which is sealed to the inner wall of the test chamber, so that the insulating oil will not leak during the movement of the support rod, and the sealing performance is strong. Attached Figure Description

[0022] Figure 1 This is a front view of Embodiment 1 of the present invention;

[0023] Figure 2 This is a cross-sectional view of Embodiment 1 of the present invention;

[0024] Figure 3 This is a top view of the position adjustment mechanism in Embodiment 1 of the present invention;

[0025] Figure 4 This is a cross-sectional view of Embodiment 2 of the present invention;

[0026] Figure 5 This is a cross-sectional view of Embodiment 3 of the present invention;

[0027] In the diagram, 1-test chamber, 2-grounding electrode plate, 3-high voltage electrode plate, 4-heating column, 5-turntable, 6-motor, 7-bearing seat, 8-bearing, 9-shaft, 10-coupling, 11-mechanical seal, 12-compressed gas cylinder, 13-pressure reducing valve, 14-gas tube, 15-injection needle, 16-rubber pad, 17-bracket, 18-threaded sleeve, 19-connecting block, 20-support rod, 21-telescopic sleeve, 22-handle, 23-sleeve, 24-pump body, 25-oil filter, 26-insulating paper layer, 27-fixed rod, 28-guide rod, 29-threaded sleeve, 30-vertical rod, 31-bearing sleeve, 32-first bevel gear, 33-second bevel gear, 34-array ultrasonic probe. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0029] Example 1

[0030] like Figures 1-3As shown, a test device for bubble discharge in transformer insulating oil includes a test chamber 1, which is made of plexiglass for easy observation. Insulating oil is placed inside the test chamber 1. Inside the test chamber 1 are a simulated heating component, a simulated discharge component, and an acoustic imaging monitoring component. The simulated discharge component is located above the simulated heating component. An insulating oil filter component and a bubble injection component are located outside the test chamber 1. The simulated discharge component includes a parallel vertically arranged grounding electrode plate 2 and a high-voltage electrode plate 3, as well as a distance adjustment mechanism connected to the high-voltage electrode plate 3. The acoustic imaging monitoring component is located above the simulated discharge component.

[0031] The simulated heating component includes a heating column 4, a turntable 5, and a motor 6. The bottom of the test chamber 1 is provided with a mounting hole, a bearing seat 7 is provided in the mounting hole, a bearing 8 is provided inside the bearing seat 7, and a shaft 9 is provided inside the bearing 8. The upper end of the shaft 9 is located inside the test chamber 1, and the turntable 5 is provided at the end. Two heating columns 4 are provided on the turntable 5. The lower end of the shaft 9 is connected to the rotating shaft of the motor 6 through a coupling 10. A mechanical seal 11 is provided at the junction of the shaft 9 and the bearing seat 7.

[0032] The bubble injection component includes a compressed gas cylinder 12, a pressure reducing valve 13, a gas tube 14, an injection needle 15, and a position adjustment mechanism. A through hole is provided on the front side of the test chamber 1, and a rubber pad 16 is fixedly installed in the through hole. The injection needle 15 is inserted into the rubber pad 16. The position adjustment mechanism is provided on the outside of the rubber pad 16, and the injection needle 15 is connected to the position adjustment mechanism. The position adjustment mechanism includes a bracket 17 and a screw sleeve 18. The bracket 17 is fixed on the front side of the test chamber 1, and the screw sleeve 18 is rotatably installed on the bracket 17. A connecting block 19 is provided at the connection between the injection needle 15 and the gas tube 14. The connecting block 19 is threaded on the outside, and the connecting block 19 is threadedly connected to the screw sleeve 18.

[0033] The distance adjustment mechanism includes a support rod 20, a telescopic sleeve 21, and a handle 22. The support rod 20 is made of polytetrafluoroethylene (PTFE), which has strong insulation, high voltage resistance, and corrosion resistance. An opening is provided on the right side of the test chamber 1, and a sleeve 23 is fixedly installed in the opening. One end of the support rod 20 is connected to the high-voltage electrode plate 3, and the other end passes through the sleeve 23 and is connected to the handle 22. The telescopic sleeve 21 is sleeved on the support rod 20, and one end is sealed to the support rod 20, while the other end is sealed to the inner wall of the test chamber 1. A protrusion is provided on the inner side of the sleeve 23, and a groove is provided on the support rod 20. The protrusion is connected to the groove.

[0034] The insulating oil filter component is located on the left side of the test chamber 1 and includes a pump body 24 and an oil filter 25. The inlet of the pump body 24 is connected to the lower part of the test chamber 1, the outlet of the pump body 24 is connected to the inlet of the oil filter 25, and the outlet of the oil filter 25 is connected to the upper part of the test chamber 1.

[0035] The acoustic imaging monitoring component includes an array ultrasonic probe 34, which emits multiple ultrasonic beams. By adjusting the time difference between the different beams, acoustic scanning within the observation range can be achieved. When a discharge bubble passes through the scanning area, it will reflect an echo, providing information on its position, size, and speed of movement, thus enabling the monitoring of the discharge bubble. The array ultrasonic probe 34 is located on the top of the test chamber 1, and a heat-insulating solid coupling layer is provided between the array ultrasonic probe 34 and the test chamber 1. The layer is composed of heat-insulating silicone and has a Shore hardness of no more than 10.

[0036] The transformer insulating oil bubble discharge test device of this invention simulates the heating element by having a motor drive a turntable to rotate two heating columns, simulating convection caused by the heating of the transformer core. Based on this, the bubble injection component is operated, controlling the bubble size and flow rate via a pressure reducing valve. The position adjustment mechanism adjusts the length of the injection needle entering the test chamber, thereby adjusting the bubble position. Specifically, rotating the screw sleeve causes the connecting block to move the injection needle horizontally into the test chamber. The distance adjustment mechanism adjusts the distance between the high-voltage electrode plate and the grounding electrode plate. Specifically, pulling the handle moves the support rod along the bushing. The telescopic sleeve on the outside of the support rod can extend and retract freely, serving a sealing function; an insulating oil filter component is installed on the left side of the test chamber to filter out the carbon ash generated by discharge; the pump body draws the insulating oil from the lower part of the test chamber into a single-bag filter, and after filtration, it is introduced into the upper part of the test chamber; the acoustic imaging monitoring component has 16-64 probe chips, with a width of 1.0±0.6mm, a length of 10mm±5mm, and a spacing of 0.2mm±0.1mm for each chip. By controlling the starting value of the time window for transmitting and receiving signals of each chip, the synthesized main sound beam is deflected, thereby completing the successive scanning of a certain area in the oil.

[0037] Example 2

[0038] like Figure 4 As shown, the transformer insulating oil bubble discharge test device of this invention is a further improvement on embodiment 1, and its difference from embodiment 1 is as follows:

[0039] An insulating paper layer 26 is provided between the grounding electrode plate 2 and the high-voltage electrode plate 3. The insulating paper layer 26 is a folded structure made of insulating paper, with one end connected to the grounding electrode plate 2 and the other end connected to the high-voltage electrode plate 3. When the position of the high-voltage electrode plate 3 moves, the insulating paper layer unfolds accordingly.

[0040] The transformer insulating oil bubble discharge test device of this invention, by setting an insulating paper layer between the grounding electrode plate and the high-voltage electrode plate, can more realistically simulate the internal structure of the transformer, that is, the discharge characteristics of bubbles in the insulating paper layer, thereby further improving the accuracy of the test and providing more accurate data for studying the influence of bubbles in transformer insulating oil on insulation performance.

[0041] Example 3

[0042] like Figure 5 As shown, the transformer insulating oil bubble discharge test device of this invention is a further improvement on embodiment 1, and its difference from embodiment 1 is as follows:

[0043] The distance adjustment mechanism includes a support rod 20, a fixed rod 27, a guide rod 28, a threaded sleeve 29, a vertical rod 30, a handle 22, and a bevel gear. The fixed rod 27 is disposed between the inner walls of the front and rear sides of the test chamber 1. The threaded sleeve 29 is rotatably disposed on the fixed rod 27. A bearing sleeve 31 is disposed at one end of the threaded sleeve 29 and is fixed to the fixed rod 27. The support rod 20 and the guide rod 28 are disposed on the outer side of the high-voltage electrode plate 3. The support rod 20 passes through the threaded sleeve 29 and is threadedly connected to the threaded sleeve 29. The guide rod 28 passes through a through hole in the fixed rod 27. A first bevel gear 32 is disposed on the outer side of the threaded sleeve 29. A bearing is disposed on the top of the test chamber 1. The vertical rod 30 is mounted on the bearing. The handle 22 is disposed at the upper end of the vertical rod 30 and a second bevel gear 33 is disposed at the lower end. The second bevel gear 33 meshes with the first bevel gear 32.

[0044] In this embodiment of the invention, when it is necessary to adjust the distance between the high-voltage electrode plate and the grounding electrode plate, the handle is turned to rotate the threaded sleeve. Under the limiting action of the guide rod, the high-voltage electrode plate moves horizontally with the support rod.

[0045] Since the distance adjustment mechanism in Embodiment 1 uses a telescopic sleeve, the material of the telescopic sleeve may produce air bubbles, and the folds of the telescopic sleeve can easily hide air bubbles, affecting the test. Therefore, the present invention adopts such a structure to solve this problem. In addition, the handle is set at the top of the test chamber, that is, the opening is at the top, so there is no need to consider the problem of oil leakage at this point.

[0046] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A device for testing a bubble discharge in transformer insulating oil, comprising a test tank in which insulating oil is provided, characterized in that: The test box is internally provided with a simulated heating component and a simulated discharge component, the simulated discharge component is located at the upper part of the simulated heating component, the test box is externally provided with an insulating oil filtering component, a bubble injection component and an acoustic imaging monitoring component; the simulated discharge component comprises a parallelly vertically arranged grounding electrode plate and a high-voltage electrode plate, and a distance adjusting mechanism connected with the high-voltage electrode plate; the acoustic imaging monitoring component is located above the simulated discharge component; The simulated heating component comprises a heating column, a rotating disc and a motor, the bottom of the test box is provided with a mounting hole, the mounting hole is internally provided with a bearing seat, the bearing seat is internally provided with a bearing, the bearing is internally provided with a shaft rod, the upper end of the shaft rod is located in the test box, and the end part is provided with the rotating disc, a plurality of the heating columns are arranged on the rotating disc, and the lower end of the shaft rod is connected with the rotating shaft of the motor through a shaft coupling; a mechanical seal is arranged at the junction of the shaft rod and the bearing seat; The insulating oil filtering component comprises a pump body and an oil filter, the inlet of the pump body is communicated with the lower part of the test box, the outlet of the pump body is communicated with the inlet of the oil filter, and the outlet of the oil filter is communicated with the upper part of the test box; The bubble injection component comprises a compressed gas cylinder, a pressure reducing valve, an air pipe, a syringe needle and a position adjusting mechanism, the front side of the test box is provided with a through hole, a rubber pad is fixedly arranged in the through hole, the syringe needle is inserted into the rubber pad, the position adjusting mechanism is arranged outside the rubber pad, and the syringe needle is connected with the position adjusting mechanism; the position adjusting mechanism comprises a support and a screw sleeve, the support is fixed on the front side of the test box, the screw sleeve is rotatably arranged on the support, a connecting block is arranged at the connection part of the syringe needle and the air pipe, a screw thread is arranged outside the connecting block, and the connecting block is screw-connected with the screw sleeve; The acoustic imaging monitoring component comprises an array ultrasonic probe, the array ultrasonic probe emits a plurality of ultrasonic beams, adjusts the time difference of different beam emission, realizes acoustic scanning in the observation range, and when a discharge bubble passes through the scanning area, reflects a back wave to provide position, size and moving speed information, thereby realizing monitoring of the discharge bubble.

2. The transformer insulating oil bubble discharge test device according to claim 1, characterized by: The distance adjusting mechanism comprises a supporting rod, a telescopic sleeve and a handle, one side of the test box is provided with an opening, a sleeve is fixedly arranged in the opening, one end of the supporting rod is connected with the high-voltage electrode plate, the other end passes through the sleeve, and the end part is connected with the handle; the telescopic sleeve is sleeved on the supporting rod, one end of the telescopic sleeve is sealingly connected with the supporting rod, and the other end is sealingly connected with the inner wall of the test box.

3. The transformer insulating oil bubble discharge test device according to claim 2, characterized by: A convex strip is arranged on the inner side of the sleeve, a groove is arranged on the supporting rod, and the convex strip is connected with the groove.

4. The transformer insulating oil bubble discharge test device according to claim 1, characterized by: The array ultrasonic probe is arranged on the top of the test box, and a heat insulation solid coupling layer is arranged between the array ultrasonic probe and the test box.

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