Sleeve capacitor core surface charge collection and discharge capability test system and test method

Abstract

The invention relates to a bushing capacitor core surface charge collection and discharge capability test system and method, a corona generation device is arranged close to the outer surface of a capacitor core assembly to be tested, and a non-contact potential measurement device is arranged close to a metal flange cylinder of a bushing capacitor core. An end screen outgoing line in the capacitor core assembly to be measured is connected with a measuring end of the non-contact potential measuring device; the testing process comprises the steps that the corona generating device injects charges into the surface of a capacitor core assembly to be tested and forms surface charge accumulation; the non-contact potential measuring device measures the potential of a metal plate at the position of an end screen outgoing line in real time; by arranging the corona generating device and the non-contact potential measuring device, the surface charge collection and discharge capability test of the bushing capacitor core body can be quickly and effectively realized in the production process of the bushing capacitor core body.

Description

Technical Field

[0001] This invention relates to the field of high voltage technology, and in particular to a testing system and method for testing the charge collection and discharge capacity of a bushing capacitor core. Background Technology

[0002] Currently, converter transformers are crucial for ultra-high voltage direct current (UHVDC) transmission systems. Valve-side bushings are an important component of converter transformers, and the main technical approach for internal insulation is a composite insulation consisting of the capacitor core and SF6 (sulfur hexafluoride) gas. The capacitor core-SF6 gas-solid interface is the weak point in the valve-side bushing insulation. In recent years, several converter transformer valve-side bushings used in DC transmission projects have experienced internal flashover discharge faults. The causes of these faults are still unclear, but it has been found that surface charge has a significant impact on the insulation performance of the capacitor core-SF6 gas-solid interface. According to research, current domestic valve-side bushing production processes do not adequately consider measures to suppress the influence of surface charge, and there is a lack of feasible means to effectively assess the accumulation and dissipation characteristics of surface charge on the capacitor core during the design and production processes. This directly restricts the overall reliability improvement of domestically produced equipment.

[0003] During operation, the bushings on the converter transformer valve side mainly bear DC voltage and DC current. Surface charge easily accumulates on the solid insulating surface in the DC electric field. Surface charge accumulation significantly affects the gas-solid interface insulation performance of high-voltage DC electrical equipment. Therefore, the characteristics of surface charge accumulation and dissipation in solid insulating materials are currently a research hotspot in the field of high-voltage insulation. However, the research methods involved in laboratory studies mostly rely on small-sized samples and customized test chambers. Their measurement methods cannot be directly transferred to the actual production process to achieve the goal of simple and efficient testing and verification of the effectiveness of surface charge control measures for large-sized insulating components.

[0004] Surface charge is essentially charged particles, including electrons and ions, accumulated on the surface of a solid medium. There are three sources of surface charge: migration along the gas-solid interface, conduction from within the solid, and conduction from the gas side. The dissipation pathways of surface charge are the same as these three pathways. The accumulation process of surface charge mainly includes migration and diffusion. Migration refers to the directional migration of charges under the influence of an applied electric field, while diffusion refers to the movement of surface charges under the influence of concentration gradient forces. Because solid surfaces have more microscopic defects, i.e., charge traps, compared to the interior of the solid, a large amount of charge easily accumulates on the surface. This charge accumulation affects the initial electric field distribution on the surface, causing it to deviate from the design value. In severe cases, it can distort the surface electric field distribution and lead to discharge. Simultaneously, a large amount of surface charge can also participate in the formation of discharge channels. Therefore, suppressing the adverse effects of surface charge on the insulation of the gas-solid interface is a key aspect of improving the operational reliability of DC electrical equipment.

[0005] A bus ring is an annular metal strip located on the surface of the bushing capacitor core, connected to the end screen of the core. Engineering bushing capacitor cores are typically designed with bus rings and similar structures to collect the continuously accumulating surface charge and discharge it to ground via a path of bus ring-end screen-end screen tap-voltage divider, preventing excessive surface charge accumulation that could lead to surface electric field distortion and discharge. However, directly measuring surface charge characteristics during production is difficult, primarily due to two factors: firstly, the time required for surface charge accumulation is extremely long; for large-size insulating structures, it can take months to accumulate charge to near a steady state, making it difficult to allocate such a long time for single-characteristic testing in actual production; secondly, the method for measuring surface charge distribution is complex, requiring the use of measuring fixtures compatible with the core to perform point scanning at different locations on the core surface to measure the surface potential and calculate the surface charge density distribution. The required fixtures and methods are difficult to apply in manufacturing, and the measuring fixtures are not universally compatible with different models of bushing cores, making implementation challenging. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the purpose of this invention is to provide a testing system and method for testing the surface charge collection and discharge capability of a bushing capacitor core. Its advantage is that it can quickly and effectively test the surface charge collection and discharge capability of a bushing capacitor core during the production process of the bushing capacitor core.

[0007] The above-mentioned objective of this invention is achieved through the following technical solution: On one hand, this invention provides a system for testing the surface charge collection and discharge capability of a sleeve capacitor core, including a corona generator, a non-contact potential measuring device, and a capacitor core assembly under test. The corona generator is disposed near the outer surface of the capacitor core assembly under test, and the non-contact potential measuring device is disposed near the metal flange of the capacitor core assembly under test. The end-screen lead in the capacitor core assembly under test is connected to the measuring end of the non-contact potential measuring device. The corona generator is used to inject charge into the surface of the capacitor core assembly under test to form surface charge accumulation on the surface of the capacitor core assembly under test, while simultaneously restricting the disordered movement of space charge generated in the air to other locations on the surface of the capacitor core assembly under test. The non-contact potential measuring device is used to measure the potential of the end-screen lead and the capacitor core assembly under test connected to it via a conductor in real time.

[0008] Preferably, the test system for the surface charge collection and discharge capability of a sleeve capacitor core provided by the present invention includes a sleeve capacitor core, a core coiled tube, a bus ring, a voltage divider, and a first voltage source. The core coiled tube is inserted into the sleeve capacitor core, and both ends of the core coiled tube extend to the outside of the sleeve capacitor core along the centerline direction. Each of the two extended ends of the core coiled tube is provided with an equalizing shield, which is at the same potential as the core coiled tube. The first voltage source is connected to the core coiled tube through one of the equalizing shields. The first voltage source is used for... A voltage is provided for the core coiled tube and the conductor connected thereto; the metal flange is sleeved at the middle position of the core coiled tube extending along its centerline; the bus ring is sleeved on the outer surface of the core coiled tube; the bus ring is equipotentially connected to the end screen of the core coiled tube; the end screen of the core coil is simultaneously connected to the voltage divider located outside the metal flange through the end screen lead; the bus ring is equipotentially connected to the end screen lead; an insulating bracket for support and fixation is provided on the outer peripheral wall of the capacitor core assembly under test; the top of the insulating bracket supports the core coiled tube and the metal flange.

[0009] Preferably, in the test system for the surface charge collection and discharge capability of the bushing capacitor core provided by the present invention, the metal flange cylinder is directly grounded.

[0010] Preferably, the test system for the surface charge collection and discharge capability of a bushing capacitor core provided by the present invention includes an insulating support, a space charge generating component, and a second voltage source. The top end of the insulating support is movably connected to the space charge generating component. The space charge generating component can rotate relative to the insulating support and move horizontally and vertically to adjust the angle and position of the space charge generating component. The second voltage source is connected to the space charge generating component and is used to provide a DC high voltage to the space charge generating component.

[0011] Preferably, the space charge generation component of the test system for the surface charge collection and discharge capability of a bushing capacitor core provided by the present invention includes a metal tip array and a metal cover. The metal tip array is disposed inside the metal cover, with its bottom end connected to the inner bottom surface of the metal cover, and its tips extending towards the opening end of the metal cover. The top surface of the metal cover is movably connected to the top end of the insulating support. The metal cover is capable of rotating and moving horizontally and vertically relative to the insulating support. The metal tip array and the metal cover are at the same potential. Under the action of the DC high voltage provided by the second voltage source... This will increase the electric field strength at the tip of the metal needle array, causing a corona discharge in the air near the tip of the metal needle array, ionizing gas molecules, and forming a large number of electrons and ions. The electrons and ions will migrate and diffuse in the gas space as charges. Charges with the same polarity as the DC high voltage provided by the second voltage source will move away from the metal needle array and the metal cover under the action of the electric field force. Charges with the opposite polarity to the DC high voltage provided by the second voltage source will move towards the metal needle array and the metal cover under the action of the electric field force and dissipate on the surface of the metal cover.

[0012] Preferably, in the test system for the surface charge collection and discharge capability of the sleeve capacitor core provided by the present invention, the metal cover is bowl-shaped, the metal cover includes an arc-shaped surrounding plate and an arc-shaped bottom plate, the bottom end of the arc-shaped surrounding plate is connected to the arc-shaped bottom plate, a preset angle is clamped between the arc-shaped surrounding plate and the arc-shaped bottom plate, the arc-shaped bottom plate is connected to the top end of the insulating support, and the arc-shaped bottom plate can rotate and move horizontally and vertically relative to the insulating support; under the action of the DC high voltage provided by the second voltage source, the metal cover will superimpose a DC electric field pointing towards the needle tip direction on the basis of the electric field distribution of the metal needle tip array, and at the same time gather from the periphery of the metal needle tip array towards the center, so as to realize the constrained directional movement of the charge formed by corona ionization in the electric field.

[0013] Preferably, the non-contact potential measurement device provided by the present invention for testing the surface charge collection and discharge capability of a bushing capacitor core includes a metal plate and a measurement component. The metal plate is connected to the end screen lead via a wire. The measurement end of the measurement component is correspondingly arranged with the metal plate, and a gap is left between the measurement end of the measurement component and the metal plate. The measurement component is used to monitor the surface potential of the metal plate in real time to obtain the surface potential of the bus ring on the surface of the bushing capacitor core, the end screen lead, and the equipotential region therewith.

[0014] Preferably, the test system for the surface charge collection and discharge capability of a bushing capacitor core provided by the present invention includes an insulating support frame, a non-contact potential measurement probe, and a data acquisition and processing device. The top end of the insulating support frame is clamped and connected to the non-contact potential measurement probe. The non-contact potential measurement probe can rotate, move horizontally or vertically relative to the insulating support frame to adjust its angle or position. The non-contact potential measurement probe is correspondingly arranged with the metal plate, and a gap is left between the non-contact potential measurement probe and the metal plate. The non-contact potential measurement probe is communicatively connected to the data acquisition and processing device, and transmits the surface potential of the metal plate collected by the non-contact potential measurement probe to the data acquisition and processing device.

[0015] Preferably, the test system for the surface charge collection and discharge capability of a bushing capacitor core provided by the present invention includes an insulating support comprising a movable base, a damped vertical telescopic rod, and a telescopic L-shaped rod. The bottom end of the vertical telescopic rod is connected to the top surface of the movable base, the top end of the vertical telescopic rod is connected to one end of the L-shaped rod, and the other end of the L-shaped rod extends toward the capacitor core assembly under test. The space charge generating component is connected to the vertical section of the L-shaped rod, and the horizontal section of the L-shaped rod is telescopic to adjust the position of the space charge generating component. The top end of the space charge generating component is rotatably connected to the bottom end of the vertical section of the L-shaped rod via a pivot to adjust the angle of the space charge generating component.

[0016] On the other hand, the present invention provides a test method for a test system for the charge collection and discharge capability of a bushing capacitor core surface, comprising the following steps:

[0017] The corona generator injects charge onto the surface of the capacitor core assembly under test and forms a surface charge accumulation.

[0018] After injecting a preset charge, the potential at the position of the end screen lead is measured in real time under different conditions using the non-contact potential measuring device.

[0019] In summary, the beneficial technical effects of the present invention are as follows: The test system and method for testing the surface charge collection and discharge capability of a bushing capacitor core provided in this application include a corona generator, a non-contact potential measuring device, and a capacitor core assembly under test. The corona generator is disposed near the outer surface of the capacitor core assembly under test, and the non-contact potential measuring device is disposed near the metal flange of the capacitor core assembly under test. The end screen lead in the capacitor core assembly under test is connected to the measuring end of the non-contact potential measuring device. The corona generator is used to inject charge into the surface of the capacitor core assembly under test to form surface charge accumulation on the surface of the capacitor core assembly under test, while restricting the space charge generated in the air from flowing into the capacitor core under test. The components move randomly at other locations on their surface; a non-contact potential measurement device is used to measure the potential of the lead wire of the end screen and the capacitor core assembly connected to it via a conductor in real time; the test procedure is as follows: the corona generator injects charge on the surface of the capacitor core assembly under test and forms surface charge accumulation - the non-contact potential measurement device measures the potential at the position of the lead wire of the end screen in real time; on the one hand, by setting up the corona generator and the non-contact potential measurement device, the surface charge accumulation and discharge capability test of the sleeve capacitor core can be realized quickly and effectively during the production process of the sleeve capacitor core; on the other hand, by measuring the potential of the lead wire of the end screen through the non-contact potential measurement device, the problem of charge discharge through the measurement circuit during the potential measurement process is avoided, thus avoiding interference with the measurement. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall structure of the test system for the surface charge collection and discharge capability of the bushing capacitor core provided in this embodiment of the invention.

[0021] Figure 2 This is a schematic diagram of the space charge generation component in the test system for the surface charge collection and discharge capability of a bushing capacitor core provided in an embodiment of the present invention.

[0022] Figure 3 This is a schematic diagram of the electric field distribution of the space charge generation component under an applied DC voltage in the test system for the charge collection and discharge capability of the bushing capacitor core surface provided in this embodiment of the invention.

[0023] Figure 4 This is a flowchart of a test method for a test system for testing the charge collection and discharge capability of a bushing capacitor core surface, provided in another embodiment of the present invention.

[0024] In the diagram, 1 is the testing system; 10 is the corona generator; 11 is the insulating support; 111 is the movable base; 112 is the vertical telescopic rod; 113 is the L-shaped rod; 12 is the space charge generating component; 121 is the metal needle tip array; 122 is the metal cover; 13 is the second voltage source; 20 is the non-contact potential measuring device; 21 is the metal plate; 22 is the measuring component; 221 is the insulating support frame; 222 is the non-contact potential measuring probe; 30 is the capacitor core assembly under test; 31 is the sheathed capacitor core; 32 is the core rolled tube; 33 is the bus ring; 34 is the voltage divider; 35 is the first voltage source; 36 is the equalizing cover; 38 is the end screen lead wire; 39 is the metal flange cylinder; and 40 is the insulating bracket. Detailed Implementation

[0025] The present invention will be further described in detail below with reference to the accompanying drawings.

[0026] Reference Figure 1 This invention discloses a test system 1 for testing the surface charge collection and discharge capability of a sleeve capacitor core, comprising a corona generator 10, a non-contact potential measuring device 20, and a capacitor core assembly 30 under test. An insulating support 40 for support and fixation is provided on the outer peripheral wall of the capacitor core assembly 30. The corona generator 10 is positioned close to the outer surface of the capacitor core assembly 30, and the non-contact potential measuring device 20 is positioned close to the metal flange 39 of the capacitor core assembly 30. The end-screen lead 38 in the capacitor core assembly 30 is connected to the measuring end of the non-contact potential measuring device 20. The corona generator 10 and the non-contact potential measuring device 20 are spaced apart. The corona generator 10 is used to generate charge on the surface of the capacitor core assembly 30 under test. Injecting charge forms a surface charge accumulation on the surface of the capacitor core assembly under test, while restricting the disorderly movement of space charge generated in the air to other locations on the surface of the capacitor core assembly 30 under test; the non-contact potential measuring device 20 is used to measure the potential of the end screen lead 38 and the capacitor core assembly under test connected to it by a conductor in real time; on the one hand, by setting up the corona generator 10 and the non-contact potential measuring device 20, the surface charge collection and discharge capability test of the sleeve capacitor core 31 can be realized quickly and effectively during the production process of the sleeve capacitor core 31; on the other hand, by measuring the potential of the end screen lead 38 by the non-contact potential measuring device 20, the problem of charge discharge through the measurement circuit during the potential measurement process is avoided, thus avoiding interference with the measurement.

[0027] like Figure 1 As shown, in this embodiment, there are two insulating supports 40. Of course, there may also be one or three insulating supports 40 or other quantities. In this embodiment, the number of insulating supports 40 is not limited.

[0028] Specifically, the top of the insulating bracket 40 is connected to the outer peripheral wall of the capacitor core assembly 30 under test, and the bottom of the insulating bracket 40 abuts against the ground. By setting the insulating bracket 40, the capacitor core assembly 30 under test is kept at a sufficient insulating distance from the ground and nearby objects.

[0029] It should be noted that the insulating support 40 is electrically insulated from the outer peripheral wall of the capacitor core assembly 30 under test, so as to minimize the influence of the insulating support 40 on the surface insulation state of the capacitor core assembly 30 under test.

[0030] Further, in this embodiment, the capacitor core assembly 30 under test includes a sleeve capacitor core 31, a core winding tube 32, a bus ring 33, a voltage divider 34, and a first voltage source 35. The core winding tube 32 is inserted into the sleeve capacitor core 31, and both ends of the core winding tube 32 extend to the outside of the sleeve capacitor core 31 along the center line direction. Each of the two protruding ends of the core winding tube 32 is provided with an equalizing shield 36, which is at the same potential as the core winding tube 32. The first voltage source 35 is connected to the core winding tube 32 through one of the equalizing shields 36. The first voltage source 35 is used to provide voltage equalization power to the core winding tube 32 and the core winding tube 32. The conductors connected to it provide voltage; a metal flange cylinder 39 is fitted at the middle position of the sleeve capacitor core 31 extending along its center line, and a bus ring 33 is fitted on the outer surface of the sleeve capacitor core 31. The bus ring 33 is equipotentially connected to the end screen of the sleeve capacitor core 31. The end screen of the core is also connected to the voltage divider 34 located outside the metal flange cylinder 39 through the end screen lead 38. The bus ring 33 and the end screen lead 38 are equipotentially connected; the top of the insulating bracket 40 supports the sleeve capacitor core 31 and the metal flange cylinder 39; a voltage equalization cover 36 is provided at both protruding ends of the core coiled tube 32 to prevent discharge from occurring at the end of the core coiled tube 32.

[0031] The first voltage source 35 provides voltage to the core winding tube 32 to simulate the electric field distribution on the surface of the sleeve capacitor core 31 when the internal conductor is energized in actual operation. It should be noted that the core end screen is the outermost aluminum foil screen inside the sleeve capacitor core 31.

[0032] Furthermore, in this embodiment, the metal flange cylinder 39 is directly grounded.

[0033] The metal flange cylinder 39 and the manifold ring 33 are spaced apart.

[0034] It should be noted that the voltage divider 34 is generally provided with a separate grounding point or is grounded together with the metal flange cylinder 39.

[0035] Specifically, such as Figure 1As shown, the corona generator 10 is located between the high-voltage end of the sleeve capacitor core 31 and the bus ring 33. During use, the corona generator 10 injects charge into the area near the surface of the core between the high-voltage end of the sleeve capacitor core 31 and the bus ring 33, forming a surface charge accumulation. At the same time, it restricts the disorderly movement of space charge generated in the air to other positions on the surface of the sleeve capacitor core 31, so as to avoid the large amount of free charge diffused in the air from affecting the measurement results.

[0036] The non-contact potential measuring device 20 is located close to the metal flange cylinder 39. During use, the non-contact potential measuring device 20 measures the potential of the end screen lead 38 in real time to verify the effect of the bus ring 33 on the collection and discharge of surface charge of the bushing capacitor core 31. The non-contact potential measuring device 20 can avoid the influence of the measuring device itself on the discharge process of surface charge of the bushing core.

[0037] It should be noted that the connection position between the insulating support 40 and the bushing capacitor core 31 should be selected from the metal flange cylinder 39 as much as possible, so as to minimize the influence of the insulating support 40 on the surface insulation state of the bushing capacitor core 31. That is, the top of one insulating support 40 is connected to the outer surface of the metal flange cylinder 39, and the top of the other insulating support 40 is insulated from the outer surface of the bushing capacitor core 31.

[0038] Continue to refer to Figures 1 to 3 In this embodiment, the corona generator 10 includes an insulating support 11, a space charge generating component 12, and a second voltage source 13. The top end of the insulating support 11 is movably connected to the space charge generating component 12. The space charge generating component 12 can rotate relative to the insulating support 11 and move horizontally and vertically to adjust the angle and position of the space charge generating component 12. The second voltage source 13 is connected to the space charge generating component 12 and is used to provide a DC high voltage to the space charge generating component 12.

[0039] Specifically, the bottom end of the insulating support 11 abuts against the ground, and the top end of the insulating support 11 extends to the upper part of the sleeve capacitor core 31. That is to say, the space charge generating component 12 is located at the upper part of the sleeve capacitor core 31. During use, the space charge generating component 12 generates space charge in the area near the surface of the sleeve capacitor core 31 and accumulates on the surface of the core, resulting in an increase in the charge density on the surface of the core. Under the action of an external electric field, the charge migrates to the bus ring 33, causing a change in the potential of the bus ring 33 and its connected end screen lead. The potential change caused by the collection and discharge of charge by the bus ring 33 can be characterized by testing the potential change at the position of the end screen lead 38 by the non-contact potential measuring device 20.

[0040] Furthermore, in this embodiment, the space charge generating component 12 includes a metal tip array 121 and a metal cover 122. The metal tip array 121 is disposed inside the metal cover 122. The bottom end of the metal tip array 121 is connected to the inner bottom surface of the metal cover 122. The tip of the metal tip array 121 extends toward the opening end of the metal cover 122. The top surface of the metal cover 122 is movably connected to the top end of the insulating support 11. The metal cover 122 can rotate relative to the insulating support 11 and move horizontally and vertically. The metal tip array 121 and the metal cover 122 are at the same potential.

[0041] The second voltage source 13 is used to provide DC high voltage to the metal needle array 121 and the metal cover 122. The metal needle array 121 is used to form corona discharge at the needle tip and generate a large amount of space charge. The metal cover 122 is used to regulate the electric field distribution, thereby preventing the space charge generated by the metal needle array 121 from moving randomly in the air.

[0042] Specifically, under the action of the DC high voltage provided by the second voltage source 13, the electric field strength at the tip of the metal needle array 121 will increase, and the air near the tip of the metal needle array 121 will form a corona, causing the gas molecules to ionize and form a large number of electrons and ions. The electrons and ions will migrate and diffuse in the gas space as charges. Charges with the same polarity as the DC high voltage provided by the second voltage source 13 will move away from the metal needle array 121 and the metal cover 122 under the action of the electric field force. Charges with the opposite polarity to the DC high voltage provided by the second voltage source 13 will move towards the metal needle array 121 and the metal cover 122 under the action of the electric field force and dissipate on the surface of the metal cover 122.

[0043] like Figure 3 As shown, arrows indicate the electric field direction distribution of the metal needle array 121 and metal cover 122 regions under DC voltage. The bottom is the simulated surface of the sleeve capacitor core 31. It can be seen that the free charges generated at the tip of the metal needle array 121 will move along the electric field direction to the surface of the sleeve capacitor core 31, and will not spread disorderly in the horizontal direction.

[0044] The metal cover 122 is bowl-shaped and includes an arc-shaped surrounding plate and an arc-shaped bottom plate. The bottom end of the arc-shaped surrounding plate is connected to the arc-shaped bottom plate. A preset angle is set between the arc-shaped surrounding plate and the arc-shaped bottom plate. The arc-shaped bottom plate is connected to the top end of the insulating support. The arc-shaped bottom plate can rotate relative to the insulating support and move horizontally and vertically.

[0045] Specifically, the arc of the curved plate bends towards the tip of the metal needle array 121. Both the metal needle array 121 and the metal cover 122 are connected to the second voltage source 13. Under the action of the DC high voltage provided by the second voltage source 13, the metal cover 122 will superimpose a DC electric field pointing towards the needle tip and converging from the periphery of the metal needle array 121 towards the center on the basis of the electric field distribution of the metal needle array 121, so as to realize the constrained directional movement of the charges formed by corona ionization in the electric field.

[0046] The preset angle should be less than 180°, but not too small.

[0047] Furthermore, in this embodiment, the insulating support 11 includes a movable base 111, a damped vertical telescopic rod 112, and a telescopic L-shaped rod 113. The bottom end of the vertical telescopic rod 112 is connected to the top surface of the movable base 111, and the top end of the vertical telescopic rod 112 is connected to one end of the L-shaped rod 113. The other end of the L-shaped rod extends toward the capacitor core assembly 30 to be tested. The space charge generating component 12 is connected to the vertical section of the L-shaped rod 113. The horizontal section of the L-shaped rod 113 can be extended and retracted to adjust the position of the space charge generating component 12. The top end of the space charge generating component 12 is rotatably connected to the bottom end of the vertical section of the L-shaped rod 113 via a pivot to adjust the angle of the space charge generating component 12. With this configuration, the insulating support 11 can support and fix the space charge generating component 12 at any position, angle, and distance on the surface of the sleeve capacitor core 31. The directional injection of charge is achieved by adjusting the position angle of the space charge generating component 12 and the distance between it and the surface of the sleeve capacitor core 31.

[0048] Specifically, the space charge generating component 12 rotates around the center line of the rotating shaft. When the space charge generating component 12 rotates to the preset position, the rotating shaft is locked by fastening bolts to prevent the rotating shaft from driving the space charge generating component 12 to rotate.

[0049] The metal cover 122 is rotatably connected to the bottom end of the vertical section of the L-shaped rod 113 via a pivot.

[0050] During the use of the space charge generating component 12, when the charge generated in the air moves to the surface of the insulating material of the sleeve capacitor core 31, the charge will be trapped by the surface charge trap of the insulating material and become surface charge. These surface charges will accumulate on the surface of the sleeve capacitor core 31 under the action of factors such as electric field. When the surface charge moves to the vicinity of the bus ring 33 on the surface of the sleeve capacitor core 31 and comes into contact with the bus ring 33, the potential of the bus ring 33 will change.

[0051] To achieve the directional movement of surface charges towards the bus ring 33, an external DC electric field needs to be provided for the surface charges. When the bushing capacitor core 31 is energized, leakage current exists on its surface. According to the design principle, the main function of the bus ring 33 is to collect the surface charges that move to the vicinity of the bus ring 33 through the leakage current between the high-voltage end of the bushing capacitor core 31 and the bus ring 33. Therefore, a DC voltage of the same polarity as the space charge generating component 12 needs to be applied to the core winding tube 32 of the bushing capacitor core 31 to simulate the electric field distribution characteristics of the surface of the bushing capacitor core 31 under the operation state, so that the surface charges of the bushing capacitor core 31 move towards the bus ring 33 under the action of this external electric field. Since the bushing capacitor core 31 is placed in the air, the external voltage applied to the core winding tube 32 should not be too high. A voltage equalization shield 36 can be installed at both ends of the core winding tube 32 to prevent discharge from occurring at the end of the core winding tube 32.

[0052] Continue to refer to Figure 1 In this embodiment, the non-contact potential measurement device 20 includes a metal plate 21 and a measurement component 22. The metal plate 21 is connected to the end screen lead 38 via a wire. The measurement end of the measurement component 22 is correspondingly arranged with the metal plate 21, and a gap is left between the measurement end of the measurement component 22 and the metal plate 21. The measurement component 22 is used to monitor the surface potential of the metal plate 21 in real time to obtain the surface potential of the bus ring on the surface of the sleeve capacitor core, the end screen lead, and the area with the same potential. This arrangement avoids the problem of charge leakage through the measurement circuit during the potential measurement process, which would interfere with the measurement. At the same time, it avoids the measurement component 22 being too close to the bus ring 33 and the surface of the sleeve capacitor core 31, which would affect the charge movement and collection process.

[0053] Specifically, the connection point between the metal plate 21 and the end screen lead 38 can be located inside the voltage divider 34 or outside the voltage divider 34.

[0054] The metal plate 21 is used to provide feasible potential measurement conditions for the measuring component 22. The measuring component 22 can obtain the surface potential of the bus ring 33, the end screen lead and the equipotential region on the surface of the sleeve capacitor core 31 by real-time monitoring of the surface potential of the metal plate 21.

[0055] Since the bus ring 33 is connected to the end screen of the core, and the voltage divider 34 is connected to the end screen via the end screen lead 38, the potential at the connection point between the end screen lead 38 and the voltage divider 34 is the potential of the bus ring 33. By extending the wiring at this connection point and connecting it to a metal plate 21, the surface potential of the metal plate 21, i.e., the potential of the bus ring 33, can be measured using a non-contact measurement method. By observing the fluctuation of the potential of the bus ring 33, it is possible to determine whether the surface charge of the sleeve capacitor core 31 is collected by the bus ring 33 and the degree of collection.

[0056] Furthermore, in this embodiment, the measuring component 22 includes an insulating support frame 221, a non-contact potential measuring probe 222, and a data acquisition and processing device. The top end of the insulating support frame 221 is clamped and connected to the non-contact potential measuring probe 222. The non-contact potential measuring probe 222 can rotate, move horizontally or vertically relative to the insulating support frame 221 to adjust its angle or position. The non-contact potential measuring probe 222 is correspondingly arranged with the metal plate 21, and a gap is left between the non-contact potential measuring probe 222 and the metal plate 21. It should be noted that the structure of the insulating support frame 221 is basically the same as the structure of the insulating support 11. The connection structure between the insulating support frame 221 and the non-contact potential measuring probe 222 is basically the same as the connection structure between the insulating support 11 and the space charge generating component 12. Therefore, the structure of the insulating support frame 221 and the connection structure between the insulating support frame 221 and the non-contact potential measuring probe 222 will not be described in detail here.

[0057] For example, the non-contact potential measurement probe 222 can be an electrostatic voltmeter. Of course, the non-contact potential measurement probe 222 can also be a voltmeter, as long as it can achieve non-contact measurement of the potential of the bus ring 33.

[0058] In the feasible implementation of the non-contact potential measurement probe 222 using an electrostatic voltmeter, the electrostatic voltmeter measures the surface potential of the metal plate 21 through the principle of electrostatic induction, thereby obtaining the surface potential at the connection between the end screen lead 38 and the voltage divider 34, and thus the surface potential of the bus ring 33. Compared with the traditional contact potential measurement method, this method minimizes the interference of the measurement component 22 itself on the charge collection process of the bus ring 33. During the measurement process, a portable electrostatic voltmeter can be used for handheld readings, or an insulating support frame 221 can be used to fix the portable electrostatic voltmeter near the metal plate 21 for continuous readings. Compared with the high-precision surface potential measurement devices based on high-voltage measurement probes commonly used in laboratories, this method is simpler to operate and more suitable for verification studies in environments such as processing plant workshops.

[0059] The working principle of the test system 1 for the surface charge collection and discharge capability of the sleeve capacitor core provided in this embodiment is as follows: First, a DC voltage is applied to the corona generator 10 through the second voltage source 13 to inject surface charges of the same polarity onto the surface of the sleeve capacitor core 31; after sufficient charge is injected, a DC voltage of the same polarity is applied to the core winding tube 32 through the first voltage source 35 to simulate the surface electric field distribution of the sleeve capacitor core 31 under the operating conditions of the sleeve capacitor core 31, so that the surface charges move toward the bus ring 33 under this electric field distribution; the change characteristics of the potential of the bus ring 33 can reflect the differences in the process of surface charges moving on the surface of the sleeve capacitor core 31, being collected by the bus ring 33, and being discharged through the voltage divider 34. The potential change of the surface of the metal plate 21 (with the same potential as the bus ring 33) is continuously observed, and the characteristic quantities such as the starting time of potential change, the rate of change, the peak potential, and the rate of decrease are statistically analyzed. By comparing the differences of the above characteristic quantities under different influencing factors, the charge collection effect and charge discharge effect of the bus ring 33 can be compared and evaluated.

[0060] Continue to refer to Figure 4 Another embodiment provides a test method for the test system 1 for testing the charge collection and discharge capability of the sleeve capacitor core surface as described above, including the following steps:

[0061] S101, The corona generator 10 injects charge on the surface of the capacitor core assembly 30 under test and forms surface charge accumulation.

[0062] Specifically, a DC voltage is applied to the corona generator 10 through the second voltage source 13. Under the action of the DC high voltage provided by the second voltage source 13, the electric field strength at the tip of the metal needle array 121 will increase, and the air near the tip of the metal needle array 121 will form a corona, causing the gas molecules to ionize and form a large number of electrons and ions. The electrons and ions will migrate and diffuse in the gas space as charges. Charges with the same polarity as the DC high voltage provided by the second voltage source 13 will move away from the metal needle array 121 and the metal cover 122 under the action of the electric field force. Charges with the opposite polarity to the DC high voltage provided by the second voltage source 13 will move towards the metal needle array 121 and the metal cover 122 under the action of the electric field force and dissipate on the surface of the metal cover 122, so that a large number of surface charges accumulate on the surface of the sleeve capacitor core 31.

[0063] S102. After injecting a preset charge, the potential at the position of the end screen lead 38 is measured in real time under different conditions (including core winding tube voltage, external gas environment, temperature and humidity, etc.) through a non-contact potential measuring device 20.

[0064] Specifically, a DC voltage of the same polarity as the space charge generating component 12 is applied to the core winding tube 32 by the first voltage source 35 to simulate the surface electric field distribution of the sleeve capacitor core 31 under operating conditions, causing the surface charge to move towards the bus ring 33 under this electric field distribution. The change characteristics of the potential of the bus ring 33 can reflect the differences in the process of surface charge moving on the surface of the sleeve capacitor core 31, being collected by the bus ring 33, and being discharged through the voltage divider 34. By continuously observing the potential change on the surface of the metal plate 21 (with the same potential as the bus ring 33) with an electrostatic voltmeter, and statistically analyzing characteristic quantities such as the start time, rate of change, peak potential, and rate of decrease of potential change, the effect of the bus ring 33 on the collection and discharge of surface charge of the sleeve capacitor core 31 can be verified. By comparing the differences of the above characteristic quantities under different influencing factors, the differences in the effect of the bus ring 33 on the collection and discharge of surface charge of the sleeve capacitor core 31 under different influencing factors can be obtained.

[0065] This application provides a test system 1 and test method for testing the surface charge collection and discharge capability of a sleeve capacitor core. The test system 1 includes a corona generator 10, a non-contact potential measuring device 20, and a capacitor core assembly 30 under test. The corona generator 10 is disposed near the outer surface of the capacitor core assembly 30 under test, and the non-contact potential measuring device 20 is disposed near the metal flange of the capacitor core assembly 30 under test. The end screen lead 38 in the capacitor core assembly 30 under test is connected to the measuring end of the non-contact potential measuring device 20. The corona generator 10 and the non-contact potential measuring device 20 are spaced apart. The corona generator 10 is used to inject charge into the surface of the capacitor core assembly 30 under test to form surface charge accumulation on the surface of the capacitor core assembly under test, while restricting the space charge generated in the air from entering the capacitor core assembly 30 under test. The surface of 0 moves randomly to other positions; the non-contact potential measuring device 20 is used to measure the potential of the end screen lead 38 and the capacitor core assembly under test connected to it through a conductor in real time; the test process is as follows: the corona generator 10 injects charge on the surface of the capacitor core assembly under test 30 and forms surface charge accumulation - the non-contact potential measuring device 20 measures the potential at the position of the end screen lead 38 in real time; on the one hand, by setting the corona generator 10 and the non-contact potential measuring device 20, the surface charge accumulation and discharge capability test of the sleeve capacitor core 31 can be realized quickly and effectively during the production process of the sleeve capacitor core 31; on the other hand, by measuring the potential of the end screen lead 38 through the non-contact potential measuring device 20, the problem of charge discharge through the measurement circuit during the potential measurement process is avoided, which would interfere with the measurement.

[0066] The test system 1 for the charge collection and discharge capability of the sleeve capacitor core surface provided by the present invention has the following advantages: the device has a simple structure, is easy to manufacture, and is convenient to operate.

[0067] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0068] Finally, it should be noted that the above embodiments are merely examples for clearly illustrating the present invention and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A system for testing the charge collection and discharge capability of a bushing capacitor core, characterized in that: It includes a corona generator, a non-contact potential measuring device, and the capacitor core assembly under test; The corona generator is positioned close to the outer surface of the capacitor core assembly under test, and the non-contact potential measuring device is positioned close to the metal flange of the capacitor core assembly under test. The lead wire of the end screen in the capacitor core assembly under test is connected to the measuring end of the non-contact potential measuring device. The corona generator is used to inject charge into the surface of the capacitor core assembly under test to form surface charge accumulation on the surface of the capacitor core assembly under test, while restricting the disorderly movement of space charge generated in the air to other positions on the surface of the capacitor core assembly under test. The non-contact potential measurement device is used to measure the potential of the end screen lead wire and the capacitor core assembly to be tested connected to it through a conductor in real time.

2. The test system for the charge collection and discharge capability of the sleeve capacitor core surface according to claim 1, characterized in that: The capacitor core assembly under test includes a sleeve capacitor core, a core coiled tube, a bus ring, a voltage divider, and a first voltage source. The core coiled tube is inserted into the sleeve capacitor core, and both ends of the core coiled tube extend to the outside of the sleeve capacitor core along the centerline direction. Each of the two protruding ends of the core coiled tube is provided with a voltage equalization shield, which is at the same potential as the core coiled tube. The first voltage source is connected to the core coiled tube through one of the voltage equalization shields. The first voltage source is used to provide voltage to the core coiled tube and the conductors connected to it. The metal flange is sleeved at the middle position of the sleeve capacitor core extending along its center line. The bus ring is sleeved on the outer surface of the sleeve capacitor core. The bus ring is equipotentially connected to the end screen of the sleeve capacitor core. The end screen of the core is also connected to the voltage divider located outside the metal flange through the end screen lead line. The bus ring is equipotentially connected to the end screen lead line. An insulating bracket for support and fixation is provided on the outer peripheral wall of the capacitor core assembly under test. The top of the insulating bracket supports the sleeve capacitor core and the metal flange cylinder.

3. The test system for the charge collection and discharge capability of the sleeve capacitor core surface according to claim 2, characterized in that: The metal flange is directly grounded.

4. The test system for the charge collection and discharge capability of the sleeve capacitor core surface according to claim 1, characterized in that: The corona generator includes an insulating support, a space charge generating component, and a second voltage source. The top end of the insulating support is movably connected to the space charge generating component. The space charge generating component can rotate and move horizontally and vertically relative to the insulating support to adjust the angle and position of the space charge generating component. The second voltage source is connected to the space charge generating component and is used to provide a DC high voltage to the space charge generating component.

5. The test system for the charge collection and discharge capability of the sleeve capacitor core surface according to claim 4, characterized in that: The space charge generating component includes a metal tip array and a metal cover. The metal tip array is disposed inside the metal cover. The bottom end of the metal tip array is connected to the inner bottom surface of the metal cover. The tips of the metal tip array extend toward the opening end of the metal cover. The top surface of the metal cover is movably connected to the top end of the insulating support. The metal cover can rotate and move horizontally and vertically relative to the insulating support. The metal tip array and the metal cover are at the same potential. Under the action of the DC high voltage provided by the second voltage source, the electric field strength at the tip of the metal needle array will increase, and the air near the tip of the metal needle array will form a corona, causing the gas molecules to ionize and obtain a large number of electrons and ions. The electrons and ions will migrate and diffuse in the gas space as charges. Charges with the same polarity as the DC high voltage provided by the second voltage source will move away from the metal needle array and the metal cover under the action of the electric field force. Charges with the opposite polarity to the DC high voltage provided by the second voltage source will move towards the metal needle array and the metal cover under the action of the electric field force and dissipate on the surface of the metal cover.

6. The test system for the charge collection and discharge capability of the sleeve capacitor core surface according to claim 5, characterized in that: The metal cover is bowl-shaped and includes an arc-shaped surrounding plate and an arc-shaped bottom plate. The bottom end of the arc-shaped surrounding plate is connected to the arc-shaped bottom plate. A preset angle is provided between the arc-shaped surrounding plate and the arc-shaped bottom plate. The arc-shaped bottom plate is connected to the top end of the insulating support. The arc-shaped bottom plate can rotate and move horizontally and vertically relative to the insulating support. Under the action of the DC high voltage provided by the second voltage source, the metal cover will superimpose a DC electric field pointing towards the needle tip and converging from the periphery of the metal needle tip array towards the center on the basis of the electric field distribution of the metal needle tip array, so as to realize the constrained directional movement of the charges formed by corona ionization in the electric field.

7. The test system for the charge collection and discharge capability of the sleeve capacitor core surface according to claim 2, characterized in that: The non-contact potential measurement device includes a metal plate and a measurement component. The metal plate is connected to the lead wire of the end screen via a wire. The measurement end of the measurement component is correspondingly arranged with the metal plate, and a gap is left between the measurement end of the measurement component and the metal plate. The measuring component is used to monitor the surface potential of the metal plate in real time to obtain the surface potential of the bus ring on the surface of the sleeve capacitor core, the lead wire of the end screen, and the area with the same potential as them.

8. The test system for the charge collection and discharge capability of the sleeve capacitor core surface according to claim 7, characterized in that: The measuring assembly includes an insulating support frame, a non-contact potential measuring probe, and a data acquisition and processing device. The top of the insulating support frame is clamped and connected to the non-contact potential measuring probe. The non-contact potential measuring probe can rotate, move horizontally or vertically relative to the insulating support frame to adjust the angle or position of the non-contact potential measuring probe. The non-contact potential measuring probe is correspondingly arranged with the metal plate, and a gap is left between the non-contact potential measuring probe and the metal plate. The non-contact potential measurement probe is communicatively connected to the data acquisition and processing device, and the non-contact potential measurement probe transmits the surface potential of the metal plate it collects to the data acquisition and processing device.

9. The test system for the charge collection and discharge capability of the sleeve capacitor core surface according to claim 4, characterized in that: The insulating support includes a movable base, a damped vertical telescopic rod, and a telescopic L-shaped rod. The bottom end of the vertical telescopic rod is connected to the top surface of the movable base, and the top end of the vertical telescopic rod is connected to one end of the L-shaped rod. The other end of the L-shaped rod extends towards the capacitor core assembly under test. The space charge generating assembly is connected to the vertical section of the L-shaped rod. The horizontal section of the L-shaped rod is telescopic to adjust the position of the space charge generating assembly. The top end of the space charge generating assembly is rotatably connected to the bottom end of the vertical section of the L-shaped rod via a pivot to adjust the angle of the space charge generating assembly.

10. A test method for a test system for testing the charge collection and discharge capability of a bushing capacitor core surface as described in any one of claims 1 to 9, characterized in that: Includes the following steps: The corona generator injects charge onto the surface of the capacitor core assembly under test and forms a surface charge accumulation. After injecting a preset charge, the potential at the position of the end screen lead is measured in real time under different conditions using the non-contact potential measuring device.

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