Oil paper insulation capacitive bushing performance detection platform

Abstract

The invention relates to the technical field of electrical equipment insulation detection, and discloses an oil paper insulation capacitive bushing performance detection platform, which comprises a central guide rod, a capacitor core, a porcelain bushing, a metal flange arranged in the middle of the porcelain bushing and an oil conservator arranged at the top end of the porcelain bushing, the central guide rod, the capacitor core, the porcelain bushing, the metal flange and the oil conservator are coaxially distributed from inside to outside along the same central line; according to the invention, through combined detection of pressure and ultrahigh frequency signals, various defect types such as internal discharge of a sleeve, discharge of a leading-out wire, overheating, oil missing and leakage and the like can be identified at the same time. Wherein the pressure detection can capture oil pressure changes caused by gas production or leakage due to faults, the ultrahigh frequency detection can identify electromagnetic signals of partial discharge, the combination of the pressure detection and the ultrahigh frequency detection makes up the limitation of a single method, the fault type diagnosis accuracy is improved, and accurate monitoring of the whole fault period of the casing pipe is achieved.

Description

Technical Field

[0001] This invention relates to the field of electrical equipment insulation testing technology, specifically to a performance testing platform for oil-paper insulated capacitive bushings. Background Technology

[0002] Insulation testing of power equipment is a technical means to assess whether the equipment can effectively isolate components at different potentials and prevent leakage and short circuits, thereby ensuring the safe operation of the power system. It mainly includes testing parameters such as insulation resistance and withstand voltage strength, and involves assessing the aging, moisture or damage of insulation materials in equipment such as transformers, instrument transformers, and surge arresters.

[0003] Oil-paper insulated capacitive bushings are key insulation components of transformers, and their operating status directly affects power grid safety. Due to their small size, low oil volume, and lack of explosion-proof devices, internal insulation defects (such as partial discharge and overheating) and oil leakage can easily lead to explosion accidents. Existing detection methods have limitations: dielectric loss and capacitance measurements have low sensitivity to local defects; pulse current methods require modification of the end screen, posing a safety risk; single pressure detection is difficult to distinguish fault types; and ultra-high frequency detection cannot cover non-discharge defects such as overheating. Therefore, it is urgent to build a multi-parameter joint performance testing platform to achieve accurate monitoring of bushings throughout the entire fault cycle. Summary of the Invention

[0004] (a) Technical problems to be solved

[0005] To address the shortcomings of existing technologies, this invention provides a performance testing platform for oil-paper insulated capacitive bushings, which has the advantages of multi-parameter joint testing and full coverage of defect types. It solves the problems of the limitations of single-parameter testing in existing testing methods and the inability to fully identify various fault types such as internal discharge, overheating, and oil leakage in bushings.

[0006] (II) Technical Solution

[0007] To achieve the above objectives, the present invention provides the following technical solution: an oil-paper insulated capacitor bushing, comprising a central guide rod, a capacitor core, a porcelain bushing, a metal flange disposed in the middle of the porcelain bushing, and an oil reservoir disposed at the top of the porcelain bushing, wherein the central guide rod, capacitor core, porcelain bushing, metal flange, and oil reservoir are all coaxially distributed from the inside to the outside along the same center line;

[0008] The central guide rod passes through the central shaft hole of the capacitor core, and the two are kept coaxially separated by a top insulating support.

[0009] The capacitor core is nested inside the porcelain sleeve, and insulating oil is filled between the capacitor core and the porcelain sleeve. The capacitor core is axially fixed to the porcelain sleeve by top and bottom positioning structures.

[0010] The metal flange is radially wrapped around the middle of the ceramic sleeve, and the metal flange is fixedly connected to the outer wall of the ceramic sleeve. The outer wall of the metal flange is symmetrically provided with mounting screw holes, and a silicon pressure sensor is threaded into the mounting screw holes.

[0011] The oil conservator is connected to the top of the porcelain sleeve through an oil circuit interface. The oil conservator is fully connected to the oil gap space between the capacitor core and the porcelain sleeve. The oil conservator is provided with a breathing channel at the bottom and an oil level observation window and an oil injection / drainage valve at the top.

[0012] Preferably, the end support is an insulating washer, the top and bottom positioning structures are insulating brackets, and the metal flange also serves as a grounding terminal, achieving zero-potential connection through a grounding wire.

[0013] Preferably, the capacitor core is made of multiple layers of insulating paper and aluminum foil electrodes rolled alternately, and the insulating oil is 25# transformer oil.

[0014] Preferably, the breathing channel is configured with a capsule structure, and the capsule structure is isolated from the external atmosphere to balance internal pressure changes.

[0015] A performance testing platform for oil-paper insulated capacitive bushings, characterized in that it comprises:

[0016] The experimental model unit includes an equivalent scaled-down oil-paper capacitor-type experimental bushing model and a full-size 72.5kV transformer oil-paper insulating bushing. The equivalent scaled-down model simulates the internal structure of the bushing, and the full-size bushing simulates lead-out defects.

[0017] The defect simulation module is used to construct internal discharge defects, lead wire discharge defects, overheating defects, and oil leakage defects in the experimental model unit.

[0018] The pressure detection module includes a diffused silicon pressure sensor installed at the oil inlet of the casing metal flange, which is used to collect real-time data on oil pressure changes inside the casing.

[0019] The ultra-high frequency detection module includes an elliptical monopole antenna arranged near the metal flange of the bushing, used to receive partial discharge electromagnetic signals in the 300MHz-3GHz frequency band;

[0020] The data acquisition and processing unit connects the pressure detection module and the ultra-high frequency detection module, and is used to filter, extract features, and perform joint diagnosis on the acquired pressure signals and ultra-high frequency signals.

[0021] Preferably, the capacitor core adopts an "equal capacitance, equal step" design, with a maximum radial field strength of 3kV / mm, 5 insulation layers, and upper and lower step dimensions of 5mm and 10mm, respectively.

[0022] Preferably, the elliptical monopole antenna substrate of the high-frequency detection module is made of PI polyimide material, with dimensions of 150mm×140mm×0.28mm, operating frequency band of 300MHz-3GHz, VSWR, and connected to the feeder via an SMA-KE interface.

[0023] Preferably, the data acquisition and processing unit includes:

[0024] The signal preprocessing module uses wavelet denoising algorithm to filter the original signal and extracts effective features through K-means clustering;

[0025] The joint diagnostic module classifies fault types based on a combination of pressure change value ΔP and ultra-high frequency signal status. ΔP > 0.1 kPa is counted as 1, -0.1 kPa < ΔP < 0.1 kPa is counted as 0, ΔP < -0.1 kPa is counted as 2, and the presence of an ultra-high frequency signal is counted as 1, while the absence of a signal is counted as 0.

[0026] The condition assessment module uses a fuzzy hierarchical method to assess the partial discharge state, and uses Euclidean distance to assess overheating and oil leakage states, and outputs a warning level.

[0027] Preferably, the fault type classification rule of the joint diagnostic module is as follows:

[0028] When UHF = 1 and ΔP = 1, the diagnosis is internal discharge of the bushing. The presence of a UHF signal indicates a discharge fault in the bushing. Simultaneously, the pressure inside the bushing increases, indicating that the insulating oil decomposes under the fault and produces fault characteristic gas. Therefore, the diagnosis is internal discharge of the bushing.

[0029] When UHF = 1 and ΔP = 2, the diagnosis is discharge combined with oil leakage. There is a UHF signal, which means that there is partial discharge in the bushing, but the internal pressure is reduced. There may be two situations: ① external discharge and oil leakage on the bushing; ② oil leakage in the bushing leads to a decrease in insulation performance, which causes internal partial discharge.

[0030] When UHF = 1 and ΔP = 0, the diagnosis is lead wire discharge. There is a UHF signal but no pressure change, indicating that the discharge did not affect the insulating oil. The diagnosis is bushing lead wire discharge.

[0031] When UHF = 0 and ΔP = 1, the diagnosis is local overheating. The absence of a UHF signal indicates that there is no discharge fault, but the pressure rise indicates that there is another fault inside the equipment. In this case, the diagnosis is overheating fault.

[0032] When UHF = 0 and ΔP = 2, the problem is diagnosed as oil shortage or leakage. When the pressure drops and there is no UHF signal, the problem is diagnosed as oil leakage.

[0033] When UHF = 0 and ΔP = 0, the diagnosis is normal operation. No UHF signal indicates that there is no discharge fault in the bushing, and the pressure remains unchanged, indicating that there is no internal overheating or oil leakage. Both parameters are in normal condition, and at this time, the diagnosis is normal operation.

[0034] Preferably, the characteristic parameters of the state assessment module include:

[0035] Discharge defects: UHF current rate of change, UHF surge rate, ΔP maximum value, ΔP surge rate;

[0036] Overheating defects: Change in maximum value of ΔP, average rate of rise of ΔP:

[0037] Missing or defective: ΔP average rate of decline.

[0038] (III) Beneficial Effects

[0039] Compared with the prior art, the present invention provides a performance testing platform for oil-paper insulated capacitive bushings, which has the following advantages:

[0040] 1. This invention, through the combined detection of pressure and ultra-high frequency signals, can simultaneously identify multiple defect types such as internal casing discharge, lead wire discharge, overheating, and oil leakage. Pressure detection captures oil pressure changes caused by gas generation or leakage due to faults, while ultra-high frequency detection identifies electromagnetic signals of partial discharge. The combination of these two methods overcomes the limitations of single methods, improves the accuracy of fault type diagnosis, and achieves precise monitoring of the entire fault cycle of the casing.

[0041] 2. This invention employs a high-precision diffused silicon sensor in its pressure detection module, which can capture pressure fluctuations caused by trace amounts of faulty gas. The ultra-high frequency detection module uses an elliptical monopole antenna operating in the 300MHz-3GHz frequency band, avoiding electromagnetic interference below 200MHz and significantly improving the signal-to-noise ratio. Signal processing algorithms such as wavelet denoising and K-means clustering further reduce the impact of environmental interference, ensuring stable detection of early defects even in complex substation environments.

[0042] 3. This invention employs an experimental system combining an equivalent scaled-down model with a full-size bushing to simulate defects that closely match actual field conditions. The test results can directly guide practical operation and maintenance. Sensor installation requires no modification to the bushing body, avoiding damage to the original insulation structure. Furthermore, the silicon pressure sensor interface includes a PEEK pin structure to ensure sealing and prevent oil leakage. Simultaneously, the severity of defects is assessed using a fuzzy hierarchical method and Euclidean distance, outputting an "early warning" level to provide a clear basis for on-site maintenance and reduce operational risks. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the overall structure of an oil-paper insulated capacitor bushing proposed in this invention;

[0044] Figure 2 This is a schematic diagram of the internal cross-section of an oil-paper insulated capacitor bushing proposed in this invention.

[0045] Figure 3 This is a schematic diagram of the diagnostic process in a performance testing platform for oil-paper insulated capacitor bushings proposed in this invention.

[0046] In the diagram: 100, center guide rod; 200, oil conservator; 300, ceramic sleeve; 400, metal flange; 500, silicon pressure sensor; 600, capacitor core. Detailed Implementation

[0047] 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 embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0048] Example:

[0049] See attached document Figures 1 to 3 As shown, an oil-paper insulated capacitor bushing includes a central guide rod 100, a capacitor core 600, a porcelain sleeve 300, a metal flange 400 disposed in the middle of the porcelain sleeve 300, and an oil conservator 200 disposed at the top of the porcelain sleeve 300. The central guide rod 100, capacitor core 600, porcelain sleeve 300, metal flange 400, and oil conservator 200 are all coaxially distributed from the inside to the outside along the same center line.

[0050] The central guide rod 100 passes through the central shaft hole of the capacitor core 600, and the two are kept coaxially separated by the top insulating support.

[0051] The capacitor core 600 is nested inside the porcelain sleeve 300, and insulating oil is filled between the capacitor core 600 and the porcelain sleeve 300. The capacitor core 600 is axially fixed to the porcelain sleeve 300 through top and bottom positioning structures.

[0052] A metal flange 400 is radially wrapped around the middle of the ceramic sleeve 300, and the metal flange 400 is fixedly connected to the outer wall of the ceramic sleeve 300. The outer wall of the metal flange 400 is symmetrically provided with mounting screw holes, and a silicon pressure sensor 500 is threaded inside the mounting screw holes.

[0053] The oil conservator 200 is connected to the top of the porcelain sleeve 300 through the oil circuit interface. The oil conservator 200 is fully connected to the oil gap space between the capacitor core 600 and the porcelain sleeve 300. The oil conservator 200 is equipped with a breathing channel at the bottom and an oil level observation window and an oil injection / drainage valve at the top.

[0054] It should be noted that: the metal flange 400 has two internal threaded holes, which are used to install the silicon pressure sensor 500 and to conduct a vacuum tightness test, respectively; the oil conservator 200 is designed according to the size of the real high-pressure bushing at 1:1, and the oil level is filled to three-half of the oil conservator 200, and the volume of the gas phase space at the top is consistent with the actual operating conditions.

[0055] Furthermore, the end support is an insulating washer, the top and bottom positioning structures are insulating brackets, and the metal flange 400 also serves as a grounding terminal, achieving zero potential connection through a grounding wire.

[0056] Furthermore, the capacitor core 600 is made of multiple layers of insulating paper and aluminum foil electrodes rolled alternately, and the insulating oil is 25# transformer oil.

[0057] Furthermore, the breathing channel is equipped with a capsule structure that is isolated from the external atmosphere to balance internal pressure changes.

[0058] A performance testing platform for oil-paper insulated capacitive bushings, characterized in that it comprises:

[0059] The experimental model unit includes an equivalent scaled-down oil-paper capacitor-type experimental bushing model and a full-size 72.5kV transformer oil-paper insulating bushing. The equivalent scaled-down model simulates the internal structure of the bushing, while the full-size bushing simulates lead-out defects.

[0060] The defect simulation module is used to construct internal discharge defects, lead wire discharge defects, overheating defects, and oil leakage defects in the experimental model unit.

[0061] The pressure detection module includes a diffused silicon pressure sensor 500 installed at the oil inlet of the casing metal flange 400, which is used to collect real-time data on oil pressure changes inside the casing.

[0062] It should be noted that the pressure detection module's sensor connects to the sleeve via a dedicated interface. This interface includes a PEEK pin structure, which, during installation, opens the copper ball of the oil tap valve to detect oil pressure while ensuring a tight seal. The pressure detection principle is based on Pascal's law, reflecting the enrichment of characteristic gases at the oil surface by monitoring changes in the pressure at the oil tap. The formula for calculating the oil tap pressure is as follows:

[0063]

[0064] Among them, P gas ρ is the initial pressure of the gas phase, h is the oil level, Δn is the increment of the characteristic gas substance, and V is the gas phase volume.

[0065] The ultra-high frequency detection module includes an elliptical monopole antenna arranged near the bushing metal flange 400 for receiving partial discharge electromagnetic signals in the 300MHz-3GHz frequency band.

[0066] It should be noted that the antenna placement of the UHF detection module is determined based on electromagnetic wave propagation simulation: for discharge defects inside the bushing, the optimal receiving area for the antenna is the top of the bushing and the metal flange 400; for discharge defects of the lead wire, the antenna can be placed near the metal flange 400 to capture the electromagnetic signals gathered at both ends of the upper ceramic sleeve 300, and the signal propagation path includes the coaxial structure inside the bushing and the wall of the ceramic sleeve 300.

[0067] The data acquisition and processing unit connects the pressure detection module and the ultra-high frequency detection module, and is used to filter, extract features, and perform joint diagnosis on the acquired pressure signals and ultra-high frequency signals.

[0068] Furthermore, the capacitor core 600 adopts an "equal capacitance, equal step" design, with a maximum radial field strength of 3kV / mm, 5 insulation layers, and upper and lower step dimensions of 5mm and 10mm, respectively.

[0069] Furthermore, the elliptical monopole antenna substrate of the high-frequency detection module is made of PI polyimide material, with dimensions of 150mm×140mm×0.28mm, operating frequency band of 300MHz-3GHz, VSWR, and connected to the feeder via an SMA-KE interface.

[0070] Furthermore, the data acquisition and processing unit includes:

[0071] The signal preprocessing module uses wavelet denoising algorithm to filter the original signal and extracts effective features through K-means clustering;

[0072] The joint diagnostic module classifies fault types based on a combination of pressure change value ΔP and ultra-high frequency signal status. ΔP > 0.1 kPa is counted as 1, -0.1 kPa < ΔP < 0.1 kPa is counted as 0, ΔP < -0.1 kPa is counted as 2, and the presence of an ultra-high frequency signal is counted as 1, while the absence of a signal is counted as 0.

[0073] The condition assessment module uses a fuzzy hierarchical method to assess the partial discharge state, and uses Euclidean distance to assess overheating and oil leakage states, and outputs a warning level.

[0074] Furthermore, the fault type classification rules of the joint diagnostic module are as follows:

[0075] When UHF = 1 and ΔP = 1, the diagnosis is internal discharge of the bushing. The presence of a UHF signal indicates a discharge fault in the bushing. Simultaneously, the pressure inside the bushing increases, indicating that the insulating oil decomposes under the fault and produces fault characteristic gas. Therefore, the diagnosis is internal discharge of the bushing.

[0076] When UHF = 1 and ΔP = 2, the diagnosis is discharge combined with oil leakage. There is a UHF signal, which means that there is partial discharge in the bushing, but the internal pressure is reduced. There may be two situations: ① external discharge and oil leakage on the bushing; ② oil leakage in the bushing leads to a decrease in insulation performance, which causes internal partial discharge.

[0077] When UHF = 1 and ΔP = 0, the diagnosis is lead wire discharge. There is a UHF signal but no pressure change, indicating that the discharge did not affect the insulating oil. The diagnosis is bushing lead wire discharge.

[0078] When UHF = 0 and ΔP = 1, the diagnosis is local overheating. The absence of a UHF signal indicates that there is no discharge fault, but the pressure rise indicates that there is another fault inside the equipment. In this case, the diagnosis is overheating fault.

[0079] When UHF = 0 and ΔP = 2, the problem is diagnosed as oil shortage or leakage. When the pressure drops and there is no UHF signal, the problem is diagnosed as oil leakage.

[0080] When UHF = 0 and ΔP = 0, the diagnosis is normal operation. No UHF signal indicates that there is no discharge fault in the bushing, and the pressure remains unchanged, indicating that there is no internal overheating or oil leakage. Both parameters are in normal condition, and at this time, the diagnosis is normal operation.

[0081] Furthermore, the characteristic parameters of the state assessment module include:

[0082] Discharge defects: UHF current rate of change, UHF surge rate, ΔP maximum value, ΔP surge rate;

[0083] Overheating defects: Change in maximum value of ΔP, average rate of rise of ΔP;

[0084] Missing or defective: ΔP average rate of decline.

[0085] I. Specific Testing Methods

[0086] 1. Defect Simulation and Experimental Preparation

[0087] Experimental model setup:

[0088] An equivalent scaled-down oil-paper capacitor bushing model (simulating internal structure) and a full-size 72.5kV transformer bushing (simulating lead-out defects) are used. The scaled-down model capacitor core 600 adopts an "equal capacitance, equal step" design (radial field strength 3kV / mm, 5 layers of insulation, upper and lower steps 5mm / 10mm) to ensure that the electric field distribution is equivalent to that of the full-size bushing.

[0089] Simulate four typical defects:

[0090] Internal discharge: Embed 5-10mm aluminum foil fragments (impurities) and wrinkled aluminum foil (capacitor screen wrinkles) into the 600 insulating paper of the capacitor core;

[0091] Lead wire discharge: Remove the end screen protective cover (floating discharge), and attach the wire to the surface of the lower ceramic sleeve 300 (surface discharge);

[0092] Overheating: Built-in heating element, temperature control is 100℃ / 200℃ / 400℃;

[0093] Oil leakage: Adjust the oil leakage rate (5 / 10 / 20 drops / min) via the 400 oil valve on the metal flange.

[0094] 2. Signal Acquisition

[0095] Pressure signal acquisition:

[0096] A diffused silicon pressure sensor 500 (range 0-200kPa, accuracy 0.25%FS) is installed at the oil inlet of the metal flange 400 of the casing to monitor the internal oil pressure changes in real time. The sampling rate is 2Hz to capture pressure fluctuations caused by gas generation or oil leakage due to faults.

[0097] Ultra-high frequency signal acquisition:

[0098] An elliptical monopole antenna (PI polyimide substrate, size 150mm×140mm×0.28mm, operating frequency band 300MHz-3GHz) is placed near the metal flange 400 to receive electromagnetic waves radiated by partial discharge, with a sampling rate ≥3.125GS / s, avoiding environmental interference below 200MHz.

[0099] 3. Data Processing and Diagnosis

[0100] Signal preprocessing: Wavelet denoising algorithm is used to filter out interference, and effective features (such as pressure rise slope and UHF signal PRPD spectrum) are extracted by K-means clustering.

[0101] Combined diagnosis: Fault type classification based on a combination of pressure change value (ΔP) and UHF signal status.

[0102] ΔP > 0.1 kPa is recorded as 1 (gas production), -0.1 kPa < ΔP < 0.1 kPa is recorded as 0 (no significant change), and ΔP < -0.1 kPa is recorded as 2 (oil leakage).

[0103] UHF signals are denoted as 1 when there is a signal and 0 when there is no signal.

[0104] Diagnostic rules: If "UHF=1 and ΔP=1" it is determined to be internal discharge, and "UHF=0 and ΔP=2" it is determined to be oil leak.

[0105] Status assessment:

[0106] Discharge defects: The severity is assessed using a fuzzy hierarchical method based on parameters such as UHF change rate and maximum ΔP value.

[0107] Overheating / oil leakage defects: Based on the comparison of measured characteristics and cluster centers with Euclidean distance (e.g., 400℃ overheating corresponds to a pressure increment of 5.1kPa), the "early warning" level is output.

[0108] II. Detection Principle

[0109] 1. Pressure Detection Principle

[0110] Faults (discharge / overheating) cause the insulating oil to decompose, producing characteristic gases such as H2 and CH4, leading to an increase in the pressure in the gas phase space; oil leakage causes a drop in oil level, resulting in a decrease in pressure. According to Pascal's law, pressure changes can be transmitted in real time through the oil inlet sensor, as shown in the formula:

[0111]

[0112] Among them, P gas ρ is the initial pressure of the gas phase, h is the oil level, Δn is the increment of the characteristic gas substance, and V is the gas phase volume.

[0113] 2. UHF Detection Principle

[0114] During partial discharge, the instantaneous transfer of charge generates high-frequency electromagnetic waves (300MHz-3GHz), which radiate outward through the coaxial structure of the sleeve (central guide rod 100, capacitor screen) and the ceramic sleeve 300. After the external antenna captures the signal, the defect type is identified by combining the PRPD spectrum characteristics (such as the internal discharge showing an "inverted T-shaped" distribution). Its anti-interference ability stems from avoiding low-frequency environmental noise.

[0115] 3. Joint Detection Logic

[0116] Single parameters have limitations (e.g., pressure cannot identify early discharge, and UHF is not sensitive to overheating). Combined detection covers all fault types through the combination of "pressure + UHF".

[0117] Discharge defects: UHF signal verifies the presence of discharge, and pressure change reflects the intensity of gas production;

[0118] Overheating defect: No UHF signal but pressure rises (gas expansion);

[0119] Oil leakage defect: pressure drop and no UHF signal, or accompanied by discharge (caused by insulation deterioration).

[0120] Joint diagnostic regulations for fault types

[0121] UHF signal ΔP state Diagnostic results 1 1 Internal discharge 1 2 Discharge and oil leakage 1 0 Lead wire discharge 0 1 Local overheating 0 2 Oil leak 0 0 Normal operation

[0122] It should be noted that the term "comprising" or any other variation thereof is 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.

[0123] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An oil-paper insulated capacitive bushing, characterized by It comprises a center guide rod (100), a capacitor core (600), a porcelain sleeve (300), a metal flange (400) arranged in the middle of the porcelain sleeve (300) and an oil pillow (200) arranged at the top end of the porcelain sleeve (300), and the center guide rod (100), the capacitor core (600), the porcelain sleeve (300), the metal flange (400) and the oil pillow (200) are coaxially arranged along the same center line from inside to outside. The center guide rod (100) is arranged in the center axis hole of the capacitor core (600), and the coaxial gap is maintained between the two through the top insulation support; The capacitor core (600) is nested in the inside of the porcelain sleeve (300), and the capacitor core (600) and the porcelain sleeve (300) are filled with insulating oil, and the capacitor core (600) is axially fixed with the porcelain sleeve (300) through the top and bottom positioning structures; The metal flange (400) is radially surrounded in the middle of the porcelain sleeve (300), and the metal flange (400) is fixedly connected with the outer wall of the porcelain sleeve (300), and a plurality of mounting screw holes are symmetrically formed in the outer wall of the metal flange (400), and a silicon pressure sensor (500) is screwed in the mounting screw hole; The oil pillow (200) is communicated with the top of the porcelain sleeve (300) through the oil way interface, and the oil gap space between the capacitor core (600) and the porcelain sleeve (300) is completely communicated in the oil pillow (200), and the oil pillow (200) is communicated with the top of the porcelain sleeve (300) through the oil way interface, and the oil gap space between the capacitor core (600) and the porcelain sleeve (300) is completely communicated in the oil pillow (200), and the bottom of the oil pillow (200) is provided with a breathing channel, and the top of the oil pillow (200) is provided with an oil level observation window and an oil injection valve.

2. The oil-paper insulation capacitor bushing performance detection platform according to claim 1, characterized in that: The end support is an insulating washer, the top and bottom positioning structures are insulating supports, the metal flange (400) serves as a grounding terminal, and zero potential connection is realized through a grounding wire.

3. The oil-paper insulation capacitor bushing performance detection platform according to claim 1, characterized in that: The capacitor core (600) is made of multiple layers of insulating paper and aluminum foil electrodes, and the insulating oil is 25# transformer oil.

4. The oil-paper insulation capacitor bushing performance detection platform according to claim 1, characterized in that: The breathing channel is provided with a capsule structure, and the capsule structure is isolated from the atmosphere to balance the internal pressure change.

5. A performance detection platform for oil-paper insulated capacitive bushing applications according to any of claims 1-4, characterized in that, It comprises: An experimental model unit comprising an equivalent scaled oil-paper capacitor type experimental bushing model and a true type 72.5kV transformer oil-paper insulation bushing, wherein the equivalent scaled model simulates the internal structure of the bushing, and the true type bushing simulates the lead defect; A defect simulation module for constructing internal discharge defects, lead discharge defects, overheating defects and oil leakage defects in the experimental model unit; A pressure detection module comprising a diffused silicon pressure sensor (500) installed on the oil outlet of the bushing metal flange (400) for real-time acquisition of internal oil pressure change data of the bushing; A UHF detection module comprising an elliptical monopole antenna arranged near the bushing metal flange (400) for receiving 300MHz-3GHz frequency band local discharge electromagnetic signals; A UHF detection module comprising an elliptical monopole antenna arranged near the bushing metal flange (400) for receiving 300MHz-3GHz frequency band local discharge electromagnetic signals; A data acquisition and processing unit is connected with the pressure detection module and the ultra-high frequency detection module, and is used for filtering, feature extraction and joint diagnosis of the collected pressure signal and ultra-high frequency signal.

6. The oil-paper insulation capacitor bushing performance detection platform according to claim 5, characterized in that: The capacitor core (600) adopts an "equal-capacitance and equal-step" design, the maximum radial field strength is 3 kV / mm, the number of insulation layers is 5, and the upper and lower step sizes are 5 mm and 10 mm respectively.

7. The oil-paper insulation capacitor bushing performance detection platform according to claim 5, characterized in that: The high-frequency detection module has an elliptical monopole antenna base made of PI polyimide material, with a size of 150 mm*140 mm*0.28 mm, a working frequency band of 300 MHz-3 GHz, and a VSWR.

8. The oil-paper insulation capacitor bushing performance detection platform according to claim 5, characterized in that: The data acquisition and processing unit comprises: A signal preprocessing module filters the original signal by using a wavelet denoising algorithm and extracts effective features by K-means clustering; A joint diagnosis module divides the fault type based on the combination logic of the pressure change value ΔP and the ultra-high frequency signal state, wherein ΔP>0.1 kPa is counted as 1, -0.1 kPa<ΔP<0.1 kPa is counted as 0, ΔP<-0.1 kPa is counted as 2, and the presence of an ultra-high frequency signal is counted as 1 and the absence of an ultra-high frequency signal is counted as 0; A state evaluation module evaluates the partial discharge state by using a fuzzy hierarchy method, evaluates the overheat and oil leakage state based on the Euclidean distance, and outputs a warning level.

9. The oil-paper insulation capacitor bushing performance detection platform according to claim 8, characterized in that, The fault type division rule of the joint diagnosis module is as follows: When UHF=1 and ΔP=1, the diagnosis is internal discharge of the bushing; When UHF=1 and ΔP=2, the diagnosis is discharge and oil leakage; When UHF=1 and ΔP=0, the diagnosis is discharge of the lead-out wire; When UHF=0 and ΔP=1, the diagnosis is local overheat; When UHF=0 and ΔP=2, the diagnosis is oil leakage problem; When UHF=0 and ΔP=0, the diagnosis is normal operation.

10. The oil-paper insulation capacitor bushing performance detection platform according to claim 8, characterized in that, The characteristic parameters of the state evaluation module include: Discharge defect: current change rate of UHF, sudden increase rate of UHF, maximum value of ΔP, sudden increase rate of ΔP; Overheat defect: change amount of the maximum value of ΔP, average rising rate of ΔP; Oil leakage defect: average falling rate of ΔP.

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