Partial discharge detection test device and control method thereof

Abstract

The present application relates to the field of power equipment state monitoring and high voltage insulation test, in particular to a partial discharge detection test device and a control method thereof; the device comprises a reference support part, a main shaft sensing function part, a self-adaptive coupling function part, a compensation suction function part and a main control machine; the device drives the main shaft through a pneumatic bellows, so that a flexible capsule containing apparent solid-liquid conversion silver-plated alumina microbeads is self-adaptively wrapped on a complex irregular measured surface; the core of the device is to extract vacuum to make the apparent solid-liquid conversion silver-plated alumina microbeads forcedly interlocked to form a consolidated state, eliminate air interlayer to realize high-rigidity acoustic conduction, and simultaneously use negative pressure to make the folded membrane disc generate a counter thrust force, which offsets the traction force generated by the contraction of the flexible capsule, so as to lock the main shaft position; the present application effectively solves the problems of poor adaptability, easy retraction and deviation of the probe on the irregular curved surface, significantly improves the physical adhesion density and reduces the interface loss of the ultrasonic signal.

Description

Technical Field

[0001] This invention relates to the field of power equipment condition monitoring and high-voltage insulation testing, specifically to a partial discharge detection test device and its control method. Background Technology

[0002] In the current environment of condition monitoring and maintenance of high-voltage power equipment, routine partial discharge ultrasonic testing is required to assess the insulation performance of 110kV cable joints and variable cross-section transition sections of gas-insulated switchgear. These tested objects typically exhibit complex irregular structures such as abrupt curvature changes and heat dissipation fins on their outer sheath surfaces. The ultrasonic probes must achieve a tight and stable physical attachment to the equipment's outer surface to acquire and continuously transmit high-frequency partial discharge acoustic signals to the processing module. To effectively receive partial discharge signals, existing solutions generally employ rigid probes supplemented with fluid coupling agents, or use mechanical springs to directly press conventional elastic pads against the equipment's periphery. While this approach has basic advantages in flat and regular surface scenarios... While possessing excellent ultrasonic signal transmission capabilities, the probe is highly dependent on the ideal geometric matching between the probe and the measured surface. Furthermore, conventional polymer coupling materials exhibit significant energy loss within the ultrasonic frequency band, leading to poor deformation adaptation when facing irregularly shaped surfaces with abrupt curvature changes. This results in the formation of microscopic air gaps at the interface and acoustic impedance mismatch. In addition, existing probe structures lack online self-checking and dynamic adjustment mechanisms for the mechanical consolidation state of the internal coupling medium and the acoustic stiffness of the interface. When faced with probe retraction, relative displacement, and local detachment caused by thermal expansion and contraction or mechanical disturbances during long-term operation, severe signal attenuation, low consistency of repeated detections, and complex manual reset operations occur, making it difficult to support the long-term maintenance of detection sensitivity and rapid closed-loop correction of coupling degradation under complex operating conditions.

[0003] Therefore, improving the acoustic coupling adaptive capability of partial discharge detection probes on complex irregular curved surfaces and the accuracy of dynamic online correction of interface conduction state has become an urgent technical problem to be solved. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a partial discharge detection test device and a control method for the same device. Specifically, the technical solution of this invention is as follows: A partial discharge detection test device, comprising: The reference support includes a rigid support flange and a pneumatic bellows. A positive pressure drive chamber is formed inside the pneumatic bellows. An air inlet is provided on the pneumatic bellows. The tail end of the pneumatic bellows is sealed to the periphery of the rigid support flange by an airtight adhesive, and its front end is sealed to a rigid movable collar. The spindle sensing function unit is coaxially inserted through the inner hole of the rigid movable collar, including a central spindle with an internal channel and a piezoelectric sensing chip array fixed to the front end face of the central spindle. The reference support unit drives the spindle sensing unit to move axially. The adaptive coupling function unit is located at the front end of the main spindle sensing function unit. It includes apparent solid-liquid conversion silver-plated alumina microspheres and a flexible capsule that covers the periphery of the piezoelectric sensing chip array and is sealed and fixed along the outer wall of the central main spindle by clamps. The coupling cavity inside is filled with apparent solid-liquid conversion silver-plated alumina microspheres. The compensation suction function unit is located between the main spindle sensing function unit and the flexible capsule. It includes a negative pressure suction tube and an inverted multi-stage folded diaphragm plate connected between the rear end of the central main spindle and the rigid support flange. A compensation air chamber is formed inside the inverted multi-stage folded diaphragm plate. An atmospheric conduction hole is opened on the rigid support flange to connect with the external atmosphere, so that the external atmospheric pressure can always act on the rear surface of the inverted multi-stage folded diaphragm plate facing away from the compensation air chamber. One end of the negative pressure suction tube passes through the internal channel and connects to the coupling cavity, while the other end is connected to the proportional valve; The main control unit connects the control reference support unit, the spindle sensing function unit, the adaptive coupling function unit, and the compensation suction function unit.

[0005] Optionally, the flexible capsule is a sealed encapsulated capsule container made of polyurethane elastomer material.

[0006] Optionally, the proportional valve is connected to an external vacuum pump, and the inner cavity of the compensation gas chamber is directly connected to the negative pressure suction pipe to share a negative pressure source.

[0007] Optionally, the air inlet is connected to an external positive pressure air source, wherein the positive pressure drive chamber receives low-pressure gas and presents a single-chamber corrugated unfolding shape.

[0008] Optionally, the inner surface of the rigid movable collar is machined with a self-lubricating physical coating.

[0009] A partial discharge detection test and a control method for a partial discharge detection test device, comprising: S1. Control the reference support to fill the positive pressure drive chamber with driving gas, and the pneumatic bellows pushes and controls the main shaft sensing function unit and the adaptive coupling function unit to change the enveloping motion trajectory under pressure. S2. Control the compensation suction function to draw a vacuum, the flexible capsule is subjected to negative pressure and shrinks in shape, and the apparent solid-liquid conversion silver-plated alumina microspheres are controlled to be transformed into solid interlocking chains with high elastic modulus due to forced interlocking. S3. Control the negative pressure in the negative pressure suction tube to be synchronously transmitted to the compensation air chamber of the inverted multi-stage folded membrane disc. The external atmospheric pressure overcomes the negative pressure in the compensation air chamber and acts on the rear surface of the inverted multi-stage folded membrane disc, causing the structure to extend and fold forward axially. The inverted multi-stage folded membrane disc provides a forward thrust, which cancels out the backward traction force of the flexible capsule, locking the position of the central main shaft. S4. Control the piezoelectric sensing chip array to emit short-wave ultrasonic guided waves with broadband parameter calibration into the apparent solid-liquid conversion silver-plated alumina microspheres and excite full-segment reflection, and receive the reflected echo. S5. Extract the peak amplitude of the reflected echo and compare it with the attenuation rate of the subsequent reflected echo amplitude to extract the envelope attenuation damping ratio parameter data representing the acoustic reflection impedance boundary. S6. Extract the main wave frequency of the shortwave ultrasonic guided wave and perform a frequency comparison operation with the main wave frequency of the reflected echo to obtain the spectrum shift reference index; S7. Based on the envelope attenuation damping ratio parameter data and the frequency shift reference index, call the pre-calibrated damping and stiffness mapping relationship, perform a difference operation between the pre-stored standard damping ratio and the envelope attenuation damping ratio parameter data to obtain the difference value, multiply it by the pre-calibrated medium porosity correlation conversion coefficient, calculate the current acoustic stiffness reduction ratio, and determine whether the current acoustic stiffness reduction ratio is greater than the pre-set error tolerance boundary. S8. If the current acoustic stiffness decrease ratio is less than or equal to the preset error tolerance boundary, maintain the current negative pressure state; if the current acoustic stiffness decrease ratio is greater than the preset error tolerance boundary, reduce the negative pressure extraction power of the proportional valve, so that the apparent solid-liquid conversion silver-plated alumina microspheres are in a loose fluidized state to reshape the encapsulation position, and perform a secondary pressure recovery action to trigger the airflow replenishment to the pneumatic bellows to increase the pressure of the positive pressure drive chamber. Based on the preset detection cycle, steps S4 to S8 are executed repeatedly until the partial discharge detection operation is completed.

[0010] Optionally, step S2 may include: S0. Wait until the probe surface, composed of the main shaft sensing function unit and the adaptive coupling function unit, is completely attached to and covers the irregular surface of the external device under test, and determine that the deformation tension has reached the preset extreme value upper limit.

[0011] Optionally, the interval between step S3 and step S4 includes: The control acquisition front end is forced to cut off the direct monitoring of partial discharge, and pulse passive detection is performed in the silent gap region where the partial discharge monitoring signal is determined to be lower than the background threshold.

[0012] Optionally, after triggering the secondary pressure recovery action that increases the pressure of the positive pressure drive chamber in step S8, the following steps are included: Before the control test, the real-time envelope attenuation damping ratio parameter data is brought back to within the preset standard window; The pumping performance of the proportional valve is controlled to reach its limit, causing the apparent solid-liquid conversion silver-plated alumina microspheres to solidify.

[0013] The present invention has the following beneficial effects: 1. This invention uses a pneumatic bellows to push and control the main shaft sensing and adaptive coupling functional units under pressure, causing them to adhere to a complex, irregularly shaped test surface. Subsequently, a vacuum is drawn, forcing the apparent solid-liquid conversion silver-plated alumina microspheres to interlock and transform them into a solid interlocking chain with high elastic modulus, eliminating microscopic air gaps and achieving high-rigidity acoustic transmission. Simultaneously, a shared negative pressure source generates a reverse thrust on an inverted multi-stage folded diaphragm disk, which counteracts the traction force of the flexible capsule, locking the central main shaft position. This design effectively solves the problems of poor probe deformation adaptation on irregular curved surfaces and easy retraction and relative displacement, significantly improving the physical adhesion tightness and reducing the interface loss of ultrasonic signals. 2. This invention utilizes a piezoelectric sensing chip array to emit short-wave ultrasonic guided waves with broadband parameter calibration, which enter the apparent solid-liquid conversion silver-plated alumina microspheres and excite full-segment reflection. The reflected echoes are received, and the envelope attenuation damping ratio parameter data and spectral shift reference index of the echoes are extracted. A pre-calibrated damping-stiffness mapping relationship is invoked to determine the current acoustic stiffness reduction ratio in real time. When the current acoustic stiffness reduction ratio is determined to be greater than a pre-set error tolerance boundary, the proportional valve automatically reduces the negative pressure power to cause the apparent solid-liquid conversion silver-plated alumina microspheres to exhibit a loose fluidized state, reshaping the encapsulation position. A secondary pressure recovery action is then performed on the pneumatic bellows to trigger airflow replenishment, increasing the pressure of the positive pressure drive chamber. This fills the gap in existing technologies lacking online self-checking and dynamic adjustment mechanisms, achieving automatic closed-loop correction of coupling degradation and ensuring consistent detection sensitivity under long-term operating conditions. Attached Figure Description

[0014] The following drawings, illustrating embodiments of this application, are incorporated herein by reference and are used to understand this application. The drawings illustrate embodiments of this application and their descriptions, serving to explain the principles of this application. In the drawings, Figure 1 This is a schematic diagram of the overall structure of the device; Figure 2 This is a schematic diagram of the internal structure of the pneumatic bellows of the device; Figure 3 This is a schematic diagram of the overall cross-sectional structure of the device; Figure 4 This is a schematic diagram of the overall structure of the device from another angle; Figure 5 This is a flowchart of the method of the present invention.

[0015] In the diagram: 1. Partial discharge detection test device; 2. Reference support; 3. Rigid support flange; 4. Pneumatic bellows; 5. Positive pressure drive chamber; 6. Rigid movable collar; 7. Spindle sensing function unit; 8. Central spindle; 9. Piezoelectric sensor crystal array; 10. Internal channel; 11. Adaptive coupling function unit; 12. Flexible capsule; 13. Apparent solid-liquid conversion silver-plated alumina microspheres; 14. Coupling inner cavity; 15. Compensation suction function unit; 16. Negative pressure suction tube; 17. Inverted multi-stage folded diaphragm; 18. Compensation gas chamber; 19. Proportional valve; 20. Air inlet; 21. External positive pressure gas source; 22. External vacuum pump. Detailed Implementation

[0016] In the following description, numerous specific details are set forth to provide a more thorough understanding of this application. However, it will be apparent to those skilled in the art that embodiments of this application may be practiced without one or more of these details. In other instances, certain technical features well-known in the art have not been described to avoid confusion with embodiments of this application.

[0017] Example 1:

[0018] Combination Figures 1-4 As shown, a partial discharge detection test device includes: The reference support part 2 includes a rigid support flange 3 and a pneumatic bellows 4. A positive pressure drive chamber 5 is formed inside the pneumatic bellows 4. An air inlet 20 is opened on the pneumatic bellows 4. The tail end of the pneumatic bellows 4 is sealed to the periphery of the rigid support flange 3 by airtight adhesive, and its front end is sealed to the rigid movable collar 6. The spindle sensing function unit 7 is coaxially inserted into the inner hole of the rigid movable collar 6, including a central spindle 8 with an internal channel 10 passing through it and a piezoelectric sensing chip array 9 fixed to the front end face of the central spindle 8. The reference support unit 2 drives the spindle sensing function unit 7 to move axially; The adaptive coupling function unit 11 is located at the front end of the main shaft sensing function unit 7. It includes apparent solid-liquid conversion silver-plated alumina microspheres 13 and a flexible capsule 12 that covers the periphery of the piezoelectric sensing chip array 9 and is sealed and fixed along the outer wall of the central main shaft 8 by clamps. The coupling cavity 14 formed inside is filled with apparent solid-liquid conversion silver-plated alumina microspheres 13. The compensation suction function unit 15 is located between the main spindle sensing function unit 7 and the flexible capsule 12. It includes a negative pressure suction tube 16 and an inverted multi-stage folded diaphragm 17 connected between the rear end of the central main spindle 8 and the rigid support flange 3. A compensation air chamber 18 is formed inside the inverted multi-stage folded diaphragm 17. An atmospheric conduction hole connected to the external atmosphere is opened on the rigid support flange 3, so that the external atmospheric pressure can always act on the rear surface of the inverted multi-stage folded diaphragm 17 facing away from the compensation air chamber 18. One end of the negative pressure suction tube 16 passes through the internal channel 10 and connects to the coupling inner cavity 14, and the other end is connected to the proportional valve 19; The main control unit is connected to the control reference support unit 2, the spindle sensing function unit 7, the adaptive coupling function unit 11, and the compensation suction function unit 15. The object under test is the outer insulation layer of the transition section between the intermediate joint of a 110kV cable and the variable cross-section of the gas-insulated switchgear. The outer surface has abrupt curvature changes and heat dissipation ribs. The rigid support flange 3 uses a stainless steel ring plate with a thickness of 6mm to 12mm as the assembly reference of the whole machine and is screwed to the external fixing frame. The pneumatic bellows 4 adopts a single-chamber axial telescopic structure. Its uninflated length is 30mm to 60mm. After being filled with positive pressure gas of 0.01MPa to 0.05MPa, it can generate an axial displacement of 8mm to 25mm. The axial displacement is transmitted to the central spindle 8 through the rigid movable collar 6. The central spindle 8 is made of hollow titanium alloy rod with an outer diameter of 8mm to 20mm and an internal channel 10 with a hole diameter of 1mm to 4mm. The front end is fixed with conductive adhesive to the piezoelectric sensing chip array 9. The piezoelectric sensing chip array 9 can be arranged in a ring or sector of 4 to 16 pieces for partial discharge ultrasonic reception and self-test guided wave emission. A flexible capsule 12 surrounds the piezoelectric sensing chip array 9 and forms a coupling cavity 14 with a thickness of 1 mm to 5 mm. The coupling cavity 14 is filled with apparent solid-liquid conversion silver-plated alumina microspheres 13, which are in a flowable and attached state when not evacuated, and form a high-rigidity acoustic conductive layer when evacuated. The negative pressure suction tube 16 is connected to the coupling cavity 14 through the internal channel 10 of the central spindle 8, and is connected to a vacuum pump through a proportional valve 19 to maintain the negative pressure of the coupling cavity 14 at -10 kPa to -90 kPa. An inverted multi-stage folded membrane disk 17 is positioned between the rear end of the central spindle 8 and the rigid support flange 3. Its compensation air chamber 18 and negative pressure suction pipe 16 share a negative pressure source. The effective pressure-bearing area of ​​the membrane disk is designed to be 1.05 to 1.50 times the area of ​​the equivalent contraction tension of the flexible capsule 12. This is so that when the flexible capsule 12 absorbs and contracts, the physical pressure difference between the external atmospheric pressure and the negative pressure inside the compensation air chamber 18 is converted into forward mechanical kinetic energy, thereby pushing the central spindle 8 forward and reducing the probability of forming an internal separation layer between the piezoelectric sensing chip array 9 and the apparent solid-liquid conversion silver-plated alumina microspheres 13. In terms of the air circuit connection structure, the positive pressure drive chamber 5 is connected to the external positive pressure air source 21 through the positive pressure air source solenoid valve; in terms of the electrical connection structure, the spindle sensing function unit 7 is connected to the piezoelectric drive acquisition module and the partial discharge signal processing module; the main control unit can be an industrial controller, which is connected to the positive pressure air source solenoid valve, the proportional valve 19, the piezoelectric drive acquisition module and the partial discharge signal processing module respectively, and controls the operation of the whole machine based on the mechanical displacement state, the suction state and the ultrasonic echo state. In this device, the main spindle sensing function unit 7 and its surrounding adaptive coupling function unit 11 together constitute an ultrasonic detection probe for signal transmission and reception. The device provides macroscopic propulsion through the reference support unit 2, completes the conformal coating of irregular surfaces through the adaptive coupling function unit 11, and offsets the internal retraction effect caused by negative pressure through the compensation suction function unit 15, so that the piezoelectric sensing chip array 9 maintains repeatable acoustic conduction position conditions on complex curved surfaces.

[0019] The apparent solid-liquid conversion silver-plated alumina microspheres 13 are silver-plated alumina microspheres with a core material of alumina ceramic and an outer surface coated with a silver layer. The average particle size is 20μm to 150μm, preferably 40μm to 80μm, the sphericity is not less than 0.85, and the bulk density is 1.8g / cm3 to 2.7g / cm3. The alumina core material is used to provide the particle skeleton hardness and resistance to compressive deformation, and the silver layer is used to improve the micro-contact conductivity and acoustic conduction continuity between particles and reduce the internal friction loss generated by the pure polymer coupling medium in the high frequency band. Apparent solid-liquid transformation refers to the change in the collective mechanical state of the microsphere group within the flexible capsule 12, which does not depend on the melting of the material itself, but on the change in the collective mechanical state of the particle group under different pressure differences: under normal pressure or low negative pressure, rearrangement and flow can occur between the microspheres, and the whole exhibits a pseudo-fluid compliant state; in the range of -30 kPa to -90 kPa, the outer wall of the flexible capsule 12 imposes constraints on the particle group, and the frictional interlocking between particles is enhanced, and the whole exhibits a high-stiffness particle solidification state. To improve the stability of repeated use, 1% to 5% by volume of narrow-diameter fine beads can be added to the silver-plated alumina microspheres to fill the pores between the coarse beads and reduce local voids after suction curing. The technical significance of this apparent solid-liquid conversion silver-plated alumina microsphere 13 is that it takes into account both the geometric compliance capability in the bonding stage and the high-frequency conduction capability in the detection stage, and is suitable for transmission in the characteristic frequency band of partial discharge ultrasound.

[0020] The flexible capsule 12 is a sealed encapsulated capsule container made of polyurethane elastomer material; The flexible capsule 12 is made of polyurethane elastomer film integrally molded with a Shore hardness of 70A to 95A, a film thickness of 0.3mm to 1.5mm, a tensile elongation at break of not less than 250%, and an air permeability lower than that of conventional silicone film, so as to reduce pressure difference loss during long-term vacuuming. The front end of the flexible capsule 12 is an attachment working surface. The outer surface can be made into a smooth surface or a shallow textured surface. The shallow texture depth is controlled between 0.05mm and 0.20mm so as to increase the actual contact area when there is a processing texture on the surface of the equipment that meets the preset roughness range. The open end of the flexible capsule 12 is fitted onto the annular positioning groove on the outer wall of the central spindle 8 and is pressed into a seal by metal clamps or high-strength fiber straps. The seal can be supplemented with polyurethane sealant. The specific role of the sealed encapsulated capsule container in this invention is not only to fill particles, but also to provide the boundary constraints required for suction and solidification of the apparent solid-liquid conversion silver-plated alumina microspheres 13 through the elastic recovery force and low gas permeability of its wall material. The effective coverage diameter of the flexible capsule 12 can be set from 20mm to 80mm to accommodate different specifications of cable joints, bushing transition areas, and irregularly shaped insulating parts of gas-insulated switchgear. The reason for using polyurethane elastomer material is that this material can adapt to the curvature of irregular surfaces during the advance contact stage by in-plane stretching and out-of-plane bending, and can maintain the integrity of the capsule wall structure under negative pressure, avoiding rapid fatigue cracks in the material body, thereby ensuring reusability during multiple suction and recovery processes.

[0021] The proportional valve 19 is connected to the external vacuum pump 22, and the inner cavity of the compensation gas chamber 18 is directly connected to the negative pressure suction pipe 16 to share a negative pressure source. The proportional valve 19 is an adjustable opening electrically controlled vacuum proportional valve 19. The control signal is 0V to 10V or 4mA to 20mA. After connecting to the external vacuum pump 22, it outputs a stable adjustable negative pressure. The negative pressure suction tube 16 is equipped with a three-way structure before entering the internal channel 10 of the central spindle 8. One way is connected to the coupling inner cavity 14 of the flexible capsule 12, and the other way is directly connected to the compensation gas chamber 18 of the inverted multi-stage folded diaphragm 17, thus forming a synchronous suction structure with a shared negative pressure source. The vacuum pump can be a diaphragm vacuum pump or a rotary vane vacuum pump with a limit negative pressure of no more than -95 kPa, and the steady-state pumping flow rate is 5 L / min to 30 L / min; the compensation chamber 18 and the coupling inner cavity 14 are connected in parallel rather than in series, in order to shorten the pressure build-up time difference and keep the contraction process of the flexible capsule 12 and the forward push process of the inverted multi-stage folded diaphragm 17 within the same control cycle; To reduce the impact of pipeline pulsation, a buffer tank with a volume of 5mL to 30mL is installed between the proportional valve 19 and the tee, and a flow-limiting orifice plate with an orifice diameter of 0.3mm to 1.0mm is installed in the branch of the compensation gas chamber 18 to make the diaphragm displacement change more stable. By adopting a shared negative pressure source structure, the main controller only needs to adjust one proportional valve 19 to simultaneously change the suction intensity of the coupling inner cavity 14 and the pressure state of the compensation gas chamber 18, thereby reducing the number of controlled objects and ensuring that the internal geometric changes caused by the negative pressure have corresponding consistency.

[0022] The air inlet 20 is connected to an external positive pressure air source 21, wherein the positive pressure drive chamber 5 receives low-pressure gas and presents a single-chamber corrugated unfolding shape; The pneumatic bellows 4 is made of polytetrafluoroethylene or fluororubber reinforced material, with an outer diameter of 20mm to 70mm, a wall thickness of 0.4mm to 1.2mm, and 3 to 10 axial crests; the air inlet 20 is located on the side near the rigid support flange 3, with a diameter of 1mm to 3mm, and is connected to the external positive pressure air source 21 through a pressure-resistant hose; The external positive pressure air source 21 can be a compressed air source, which outputs low-pressure gas of 0.005MPa to 0.05MPa after passing through the pressure reducing valve, so that the positive pressure drive chamber 5 can push the central spindle 8 forward without causing impact contact. The single-chamber corrugated deployment pattern refers to the fact that the interior of the pneumatic bellows 4 is a continuous single air chamber without intermediate partitions. After inflation, each corrugated section unfolds synchronously, avoiding the front end ring from swaying when the pressure of different chambers is inconsistent in the multi-chamber structure. In order to adapt to the approach process of irregular surfaces, the main controller can limit the pressure rise rate of the positive pressure drive chamber 5 to 0.5 kPa / s to 5 kPa / s, so that the flexible capsule 12 maintains slow advancement when approaching the device under test. The specific rate control mechanism is as follows: the main controller uses a built-in closed-loop proportional-integral-derivative control algorithm to collect the feedback value of the pressure sensor in the positive pressure drive chamber 5 in real time and calculate the current actual pressure rise slope. Based on the deviation between the actual slope and the set slope, the main controller outputs a pulse width modulation control signal with a frequency of 100Hz to 500Hz to adjust the duty cycle of the intake solenoid valve, or directly outputs an analog voltage to adjust the opening of the electric proportional pressure reducing valve, thereby achieving smooth linear boosting. Compared to rigid spring compression, this propulsion method can provide more uniform distributed contact pressure at locations with rapidly changing curvature, reducing air gaps formed by localized point contacts.

[0023] The inner surface of the rigid movable collar 6 is machined with a self-lubricating physical coating; The rigid movable collar 6 is made of stainless steel, aluminum alloy or engineering ceramics, and the radial clearance between the inner hole and the central spindle 8 is controlled between 0.01 mm and 0.08 mm. The inner hole surface is machined with a self-lubricating physical coating, which can be a polytetrafluoroethylene composite coating, a molybdenum disulfide dry film coating or a diamond-like low friction coating. The coating thickness is 5 μm to 30 μm and the coefficient of friction is controlled between 0.05 and 0.20. The purpose of using a self-lubricating physical coating is to enable the central spindle 8 to maintain low-resistance linear sliding when pushed by the pneumatic bellows 4 and compensated by the inverted multi-stage folded diaphragm disk 17, thereby reducing the impact of mechanical jamming on the attitude of the piezoelectric sensing chip array 9. Specifically, when the pneumatic bellows 4 extends forward, it abuts against the force-bearing protrusion on the outer wall of the central spindle 8 through the end face of the rigid movable collar 6, thereby transmitting the forward mechanical thrust to the central spindle 8 to complete the initial attachment of the irregular surface. During the compensation suction stage, the central spindle 8 compensates for axial displacement by relying on the counter-thrust generated by the inverted multi-stage folded diaphragm disk 17 and maintaining a small amount of low-resistance linear sliding in the inner hole of the rigid movable collar 6 with the help of the self-lubricating coating. To ensure coaxiality, guide sections can be set at both ends of the inner hole of the rigid movable collar 6, and a chip storage groove or micro air storage groove can be set in the middle to accommodate the small amount of wear particles after multiple reciprocating motions. After actual assembly, the lateral swing of the central spindle 8 in the entire stroke range can be limited to within 0.05mm, thereby reducing the relative offset between the piezoelectric sensing chip array 9 and the particle layer inside the flexible capsule 12.

[0024] Example 2:

[0025] Combination Figure 5 As shown, a control method for a partial discharge detection test device includes: S1. The control reference support 2 fills the positive pressure drive chamber 5 with driving gas, and the pneumatic bellows 4 is pushed and controlled by the pressure to change the enveloping motion trajectory of the spindle sensing function unit 7 and the adaptive coupling function unit 11. S2, the control compensation suction function 15 draws a vacuum, the flexible capsule 12 is subjected to negative pressure and shrinks in shape, and the control apparent solid-liquid conversion silver-plated alumina microspheres 13 are forced to interlock and become solid interlocked chains with high elastic modulus. S3. The negative pressure in the negative pressure suction tube 16 is synchronously transmitted to the compensation air chamber 18 of the inverted multi-stage folded membrane disc 17. The external atmospheric pressure overcomes the negative pressure in the compensation air chamber 18 and acts on the rear surface of the inverted multi-stage folded membrane disc 17, causing the structure to extend and fold forward axially. The inverted multi-stage folded membrane disc 17 provides a forward thrust, which cancels out the backward traction force of the flexible capsule 12 and locks the position of the central main shaft 8. S4. Control the piezoelectric sensing chip array 9 to emit short-wave ultrasonic guided waves with broadband parameter calibration into the apparent solid-liquid conversion silver-plated alumina microspheres 13 and excite full-segment reflection, and receive the reflected echo. S5. Extract the peak amplitude of the reflected echo and compare it with the attenuation rate of the subsequent reflected echo amplitude to extract the envelope attenuation damping ratio parameter data representing the acoustic reflection impedance boundary. S6. Extract the main wave frequency of the shortwave ultrasonic guided wave and perform a frequency comparison operation with the main wave frequency of the reflected echo to obtain the frequency shift reference index. S7. Based on the envelope attenuation damping ratio parameter data and the frequency shift reference index, call the pre-calibrated damping and stiffness mapping relationship, perform a difference operation on the pre-stored standard damping ratio and envelope attenuation damping ratio parameter data to obtain the difference value, multiply it by the pre-calibrated medium porosity correlation conversion coefficient, calculate the current acoustic stiffness reduction ratio, and determine whether the current acoustic stiffness reduction ratio is greater than the pre-set error tolerance boundary. S8. If the current acoustic stiffness decrease ratio is less than or equal to the preset error tolerance boundary, maintain the current negative pressure state; if the current acoustic stiffness decrease ratio is greater than the preset error tolerance boundary, reduce the negative pressure extraction power of the proportional valve 19, so that the apparent solid-liquid conversion silver-plated alumina microspheres 13 are in a loose fluidized state to reshape the wrapping position, and perform a secondary pressing recovery action to trigger the airflow replenishment to the pneumatic bellows 4 to increase the pressure of the positive pressure drive chamber. Based on the preset detection cycle, steps S4 to S8 are executed repeatedly until the partial discharge detection operation is completed. The control method is executed by the main control unit, which includes a pneumatic control module, an ultrasonic excitation acquisition module, and a feature calculation module. In step S1, the main controller applies a set low-pressure gas to the positive pressure drive chamber 5, causing the pneumatic bellows 4 to push the central spindle 8 and the flexible capsule 12 toward the irregular insulating surface to be tested. The advancing speed can be controlled between 0.5 mm / s and 5 mm / s, and the contact pressure is between 5 kPa and 30 kPa, so that the uncured apparent solid-liquid conversion silver-plated alumina microspheres 13 rearrange with the flexible capsule 12 and fill the undulations of the curved surface. In step S2, the main controller adjusts the proportional valve 19 to reduce the negative pressure in the coupling cavity 14 from normal pressure to -30kPa to -85kPa. Under the action of pressure difference, the flexible capsule 12 tightly wraps the apparent solid-liquid conversion silver-plated alumina microspheres 13, and the particle group changes from a flowable dynamic state to an interlocked solidified state, forming a continuous conductive layer between the piezoelectric sensing chip array 9 and the measured surface. Here, the solid interlocking chain is used to characterize the continuous force transmission skeleton formed by the particle group under negative pressure constraint. It does not refer to the actual crystal phase transformation of the microsphere material, but rather to the chain-like interlocking path formed at the particle contact point along the main force direction. This path determines the continuity of ultrasonic energy propagation and the interface stiffness. In step S3, since the compensation air chamber 18 and the coupling inner cavity 14 share the same negative pressure source, the inverted multi-stage folded diaphragm 17 extends forward synchronously, forming an axial thrust opposite to the contraction traction direction of the flexible capsule 12. The main controller does not need to set up an independent actuator. It can control the axial displacement residual of the central spindle 8 within 0.02mm to 0.10mm through the area difference design. In this embodiment, the counterforce cancellation refers to the mutual cancellation of opposing forces along the axis of the central main shaft 8. Its physical essence is one-dimensional axial force balance, rather than the superposition of force vectors in any spatial direction. Because the flexible capsule 12 will generate backward traction on the main shaft after suction, the forward thrust provided by the compensation film disk can reduce the retraction of the main shaft and maintain the bonding continuity between the piezoelectric sensing chip array 9 and the particle conduction layer. In step S4, the main controller controls the piezoelectric sensing chip array 9 to emit broadband short-wave ultrasonic guided waves during the partial discharge signal silence period. The center frequency can be set from 100kHz to 2MHz, the pulse width is from 1μs to 20μs, and the excitation voltage is from 5V to 60V. After the emission ends, the same array switches to the receiving state to collect the echo signal. In this embodiment, the processing flow of steps S4 to S7 can be executed in the following order: acquire a transmission reference waveform and at least one reflected echo waveform, and record the corresponding sampling time sequence; perform bandpass filtering and time window truncation on the echo waveform to filter out low-frequency interference caused by the action of proportional valve 19, gas path pulsation and environmental mechanical vibration; Envelope extraction and spectrum analysis are then performed on the truncated echo sequence to generate time-domain attenuation features and frequency-domain offset features, respectively. These two types of features are then fed into a pre-calibrated mapping table to obtain the equivalent acoustic stiffness state of the current coupling layer. In step S5, the main control unit extracts the envelope of the echo sequence. The envelope can be obtained by rectification and low-pass filtering or Hilbert transform. The first main echo peak A1 and the subsequent n decaying oscillation peaks are recorded. The envelope attenuation damping ratio is calculated based on the logarithmic attenuation relationship. The specific calculation rule is as follows: the main controller extracts the amplitudes of two adjacent peak values ​​and calculates the natural logarithm of their ratio as the single-cycle attenuation logarithmic reduction. The specific calculation formula is:

[0026] in, This represents the logarithmic reduction in decay over a single period; Indicates the first The amplitude of each echo peak; Indicates the first The amplitude of each echo peak, Indices are positive integers; The symbol represents the natural logarithm operation; the single-cycle damping ratio is calculated based on the approximate relationship under weak damping conditions, using the following formula:

[0027] in, Indicates the single-cycle damping ratio; π is a constant; to eliminate single measurement error, the main control computer performs a sliding window averaging operation on the extracted first n peak values, that is, the arithmetic average of each adjacent peak value with the calculated damping ratio is performed, and finally the smoothed envelope attenuation damping ratio parameter data is output. The physical meaning of the envelope attenuation damping ratio parameter data is to reflect the degree of interface loss when ultrasonic energy propagates between the apparent solid-liquid conversion silver-plated alumina microspheres 13, the flexible capsule 12 wall, and the outer surface layer under test; an increase in its value usually indicates an increase in additional energy consumption caused by internal pores, local detachment, or discontinuous particle contact. In step S6, the main control unit performs spectrum analysis on the transmitted signal and the reflected echo, and extracts the main frequency of the shortwave ultrasonic guided wave. With the main frequency of the reflected echo The difference between the two serves as a reference index for spectral shift. The physical meaning of the spectral shift reference index is to characterize the degree of relative attenuation of high-frequency components and change of the dominant propagation mode in the propagation path. When the particles are fully consolidated and the interface is stable, the frequency shift is small. When the particles loosen again and local air gaps or internal separation layers are formed, the main frequency will shift to a lower frequency band. In step S7, the main control unit calls the pre-calibrated damping and stiffness mapping relationship. The mapping mechanism consists of the corresponding relationship between the envelope attenuation damping ratio, the frequency shift reference index, and the acoustic stiffness reduction ratio under different negative pressure and different fitting conditions. The purpose of this mapping mechanism is to indirectly determine whether the current coupling interface is still in a stable conduction state suitable for ultrasonic detection of partial discharge, by utilizing the characteristics of ultrasonic echoes that can be acquired online, when it is impossible to directly measure the consolidation quality of particles inside the flexible capsule 12 and the real-time stiffness of the coupling layer. The mapping mechanism logically comprises an input layer, a comparison layer, and an output layer: the input layer receives the current negative pressure value, the current envelope attenuation damping ratio, and the current frequency shift reference index; the comparison layer first calls the corresponding standard damping ratio and reference frequency shift range according to the negative pressure level, and then judges the degree of deviation of the current feature; the output layer provides the acoustic stiffness reduction ratio. Based on this, control commands are generated to maintain, release rearrangement, or restore secondary pressure. Overall, it represents the causal relationship between the degree of negative pressure constraint, particle interlocking state, interface conduction continuity, and return attenuation and frequency shift characteristics; the main control computer calculates the difference between the standard damping ratio and the real-time damping ratio, that is:

[0028] in, This represents the difference between the standard damping ratio and the real-time damping ratio. Indicates the preset standard damping ratio; This represents the currently calculated real-time single-cycle damping ratio; The absolute value operator; Multiply by the medium porosity correlation conversion factor The current acoustic stiffness reduction ratio is obtained. The calculation formula is as follows:

[0029] in, This indicates the current percentage decrease in acoustic stiffness; This represents the difference between the standard damping ratio and the real-time damping ratio. Indicates the conversion factor related to the porosity of the medium; The damping ratio can be pre-calibrated to 0.5 to 3.0 based on the particle size distribution of the microbeads used and the geometric dimensions of the flexible capsule 12. The preset standard damping ratio refers to the reference damping ratio obtained by pre-calibrating the prototype under the target installation position, target negative pressure working value, and qualified bonding condition. It can be the average value of the damping ratio measured by multiple repeated bonding, or the design center value near the average value; its function is to serve as an online comparison benchmark. Medium porosity correlation conversion factor This method converts the change in damping into a percentage decrease in acoustic stiffness. It is derived from factory calibration data: while keeping the probe structure unchanged, different porosities or different fit relaxation states are artificially set, and the correlation between the change in damping and the actual decrease in acoustic conductivity is recorded. Based on this, a suitable microsphere particle size and capsule size are selected. value; The mapping relationship and conversion coefficients Specifically, the apparent solid-liquid conversion silver-plated alumina microspheres under test can be pressure-calibrated in advance using a standard acoustic impedance measuring instrument under different negative pressure porosities. The corresponding data form containing damping ratio, frequency shift and stiffness reduction ratio can be generated and pre-stored in the non-volatile memory of the main controller. The current acoustic stiffness reduction ratio is a dimensionless state quantity used to quantify the degree of attenuation of the conduction capacity of the current coupling layer relative to the standard consolidation state; its role in the control logic is to serve as a direct criterion for determining whether a secondary pressure recovery needs to be triggered. The preset error tolerance boundary Rb is the maximum allowable percentage decrease in coupling performance of the system. It indicates that within this threshold, the sensitivity, repeatability, and positioning error of partial discharge ultrasonic detection are still within an acceptable range; if it exceeds this threshold, the coupling interface is considered to have deviated from a stable working state. To make the judgment process clearer, the main control unit can execute the following steps: First, read the current negative pressure value, the current echo envelope attenuation damping ratio, and the current frequency shift reference index; then, read the standard damping ratio and corresponding values ​​from the calibration table for the corresponding negative pressure range. value; Then calculate And compare with Rb; if If the voltage is less than or equal to Rb, the coupling state is considered acceptable and the current negative voltage is maintained. If the value is greater than Rb, the coupling state is determined to be degraded and the process proceeds to step S8. In a specific quantitative simulation example: assuming that under the current negative pressure range, the preset standard damping ratio output by the calibration table is 0.05, and the current envelope attenuation damping ratio calculated in real time by the main control computer is 0.08, then the difference is obtained by performing a subtraction operation. The value is 0.03; if the system's pre-calibrated medium porosity correlation conversion factor is... If the value is 2.0, the main control unit will calculate the current acoustic stiffness reduction ratio. It is 0.06; If the preset error tolerance boundary Rb set by the system is 10%, since 6% is less than 10%, the main controller determines that the current acoustic stiffness reduction ratio is less than or equal to the preset error tolerance boundary, and thus outputs a command to maintain the current negative pressure state. In step S8, the main control unit will Compared with a preset error tolerance boundary Rb, where Rb can be set to 5% to 15%; when Maintain the current negative pressure state as long as the limit is not exceeded. When the boundary is exceeded, the opening of the proportional valve 19 is increased, causing the negative pressure in the coupling cavity 14 to rise briefly to the preset first negative pressure range, for example, from -75kPa to -20kPa to -40kPa, to release the particle interlock. At the same time, a pressure pulse of 2kPa to 10kPa is added to the positive pressure drive cavity 5 for 0.2s to 3s, causing the flexible capsule 12 to undergo secondary pressing. After that, the negative pressure is restored to the working value and re-solidified. Here, the loose fluidization state refers to the particle group transitioning from a highly constrained interlocked state to a pseudo-fluid dynamic state where local rearrangement is possible after a portion of the negative pressure is released, not to thermal melting or material melting. To reduce the probability of misjudgment based on a single feature, step S8 is preferably performed in the following sequence: initial judgment of damping deviation—verification of frequency shift index—execution of recovery. When the damping ratio shows coupling degradation and the frequency shift reference index deviates synchronously from the allowable range under the corresponding negative pressure level, the main controller will first determine that the actual coupling is loose; if the damping changes abnormally but the frequency shift is basically stable, an additional retest can be performed before deciding whether to perform recovery. Steps S4 to S8 are repeated at a set period, which can be from 5s to 300s, to track minute coupling changes caused by thermal expansion and contraction over a long period of time. This method allows for the determination of coupling conduction status and online correction without removing the probe. To facilitate engineering implementation, the mapping mechanism is preferably implemented using a lookup table or segmented interval determination method: first, the corresponding reference data is retrieved according to the interval where the current negative pressure is located; then, an acoustic stiffness reduction level is output according to the interval where the damping ratio deviation and frequency shift deviation are located; and finally, this level is converted into... The value is used for closed-loop control, thereby avoiding misjudgments based on a single signal.

[0030] Step S2 includes: S0. Wait until the probe surface, composed of the spindle sensing function unit 7 and the adaptive coupling function unit 11, is completely attached to and covers the irregular surface of the external device under test, and determine that the deformation tension has reached the preset extreme value upper limit. Before performing vacuum curing, step S0 is set to confirm that the flexible capsule 12 has completed geometric compliance; after the main control machine completes the propulsion in step S1, it stops pressurizing and maintains the positive pressure drive chamber 5 at the current pressure value and waits for 0.5s to 10s to allow the flexible capsule 12 and the apparent solid-liquid conversion silver-plated alumina microspheres 13 to fully rearrange on the external irregular surface. The deformation tension threshold can be determined in two ways: One method is mechanical quantity determination. The pressure sensor on the air supply branch of the pneumatic bellows 4 is used to monitor the steady-state pressure change rate. When the pressure change rate per unit time is lower than the set threshold, such as lower than 0.2 kPa / s, and continues for a set duration, it is determined that the shape change of the flexible capsule 12 tends to be stable. Secondly, displacement determination is achieved by using an axial displacement sensor on the central spindle to monitor the displacement change rate. When the displacement change rate is less than 0.02 mm / s and continues for a set duration, it is determined that the probe surface has been completely attached to and covered the irregular surface of the device under test. To avoid transient pulse interference errors in the calculation of the rate of change caused by high-frequency noise from the sensor, the main controller uses a set time interval for discrete sampling when calculating the pressure and displacement rates of change. First, it performs moving average filtering and smoothing on 10 consecutive sampling points, then uses a first-order forward difference algorithm to calculate the smoothed rate of change at the current moment, and finally compares it with a set threshold. When the deformation tension reaches the preset extreme limit, it means that the geometric unfolding degree between the flexible capsule 12 and the irregular surface has reached the set limit under the current propulsion force. Continuing to propel will mainly increase the contact stress rather than increase the coverage area. Therefore, the main controller executes step S2 at this time to reduce the curing deviation caused by premature vacuuming when the surface is not fully attached. In terms of control logic, the stress reaching the preset extreme upper limit does not refer to a single absolute force value, but rather to the state quantity that characterizes the attachment and unfolding process after the probe continues to be compressed, which has changed from rapid change to a plateau region. The main controller can prioritize either the pressure change rate or the displacement change rate as the primary criterion, or it can use a combination of both as a strict criterion: when the pressure change rate is continuously lower than the set value and the displacement change rate is continuously lower than the set value, it is determined that the shape of the flexible capsule 12 has basically completed adaptive unfolding; if only one criterion is met, it continues to wait until the timeout or both criteria are met; the set time is preferably 0.2s to 2s, which is used to filter out transient misjudgments caused by short-term mechanical vibration, air pressure fluctuations and local particle rearrangement; For flexible capsules 12 of different sizes and irregular surfaces under test with different curvatures, the main control unit can read the corresponding process parameter table before installation and automatically give the pressure change rate threshold, displacement change rate threshold and the longest waiting time at that position, so that this step has a clear basis for determination rather than pure experience waiting. If the above criteria are not met even after the longest waiting time is reached, the main controller can maintain the safe contact pressure and prompt for repositioning or re-execution of step S1 to avoid directly entering the vacuum solidification state when the adhesion is insufficient. The technical purpose of step S0 is to distinguish between the completion of propulsion contact and the completion of geometric compliance: the former only indicates that the flexible capsule 12 has contacted the measured irregular surface, while the latter indicates that the particle group has completed the main rearrangement within the capsule and the shape coverage tends to be stable. Only after step S0 confirms entry into the platform area and then step S2 is executed will the subsequent negative pressure primarily serve to lock the existing shape, rather than forcibly tightening the capsule before it is fully spread, thereby reducing the probability of local suspension, edge curing, or the formation of an internal separation layer.

[0031] Between steps S3 and S4, the following steps are included: controlling the acquisition front end to forcibly cut off the direct monitoring of partial discharge, and performing pulse passive detection in the silent gap region where the partial discharge monitoring signal is determined to be lower than the background threshold. Since the piezoelectric sensing chip array 9 has both partial discharge ultrasonic reception and self-test ultrasonic guided wave transmission functions, the main control unit adds a working mode switching process between steps S3 and S4; the main control unit reads the current data stream of the partial discharge monitoring channel, and when the device under test is in the partial discharge silence gap or the main control unit determines that the current received signal is lower than the background threshold, it sends a mode switching command to the acquisition front end. Furthermore, the main controller is equipped with a sliding time window judgment logic: after the partial discharge signal is converted from analog to digital, it enters the buffer of the main controller. The main controller calculates the effective value of the signal according to the set time window. When the effective value of three consecutive time windows is lower than the preset background noise threshold, the main controller triggers a hardware interrupt and sends a high-level hardware switching command to the acquisition front end through the general input / output interface to temporarily stop the direct monitoring of partial discharge, cut off the high-gain passive receiving channel, and switch the piezoelectric sensing chip array 9 to the pulse passive detection mode. Pulse passive detection refers to the process of emitting low-energy ultrasonic pulses to the apparent solid-liquid conversion silver-plated alumina microspheres 13 and the outer surface of the device without applying electrical excitation to the high-voltage device under test, and collecting the reflected echoes generated by the structural interface; the mode switching time can be controlled from 1ms to 50ms, and the detection window duration can be controlled from 5ms to 200ms, thereby reducing the time occupied for listening to normal partial discharge; After the detection window ends, the main control unit resumes the direct monitoring of partial discharge and stores the echo characteristic parameters obtained from this detection in the buffer for use in steps S5 to S8. This switching method can avoid the superposition of self-test pulses and original ultrasonic events of partial discharge, so that the echo analysis results can more directly reflect the acoustic state of the coupling interface.

[0032] After triggering the secondary pressure recovery action of increasing the positive pressure drive chamber pressure in step S8, the following steps are included: controlling the real-time envelope attenuation damping ratio parameter data before detection to rise back to the preset standard window; controlling the lifting proportional valve 19 to reach the limit of the air pumping performance, causing the apparent solid-liquid conversion silver-plated alumina microspheres 13 to solidify. After step S8 has triggered the secondary bonding recovery action, the main control unit continues to execute the recovery confirmation and re-curing process; within 0.1s to 3s after the secondary bonding is completed, the main control unit calls the piezoelectric sensor chip array 9 again to emit detection pulses and recalculates the current real-time envelope attenuation damping ratio. The preset standard window can be pre-calibrated according to the probe installation position and the type of material being tested. For example, the lower limit of the standard window is ζmin and the upper limit is ζmax, where ζmin corresponds to the lowest value of the acceptable transmission state and ζmax corresponds to the upper limit of the good fit state. When the current real-time envelope attenuation damping ratio enters this window, the main controller determines that the shape of the coupling cavity 14 has been restored to a state that can continue to be detected. Subsequently, the main controller controls the proportional valve 19 to gradually improve the pumping performance, so that the negative pressure of the coupling inner cavity 14 and the compensation air chamber 18 returns to the upper limit of the working setting, preferably -60kPa to -90kPa, so that the apparent solid-liquid conversion silver-plated alumina microspheres 13 re-enter the solidified state. To reduce shape deviation during re-curing, the proportional valve 19 can be increased at a slope of 0.5 kPa / s to 10 kPa / s, rather than being pulled to the limit instantaneously. If the current real-time envelope attenuation damping ratio is detected to be still not within the preset standard window, the main controller can repeat the secondary pressing recovery action once or multiple times. To clarify the control decision flow here, the main controller has built-in state machine logic: if the damping ratio does not enter the window, the main controller will increment the current retry counter by 1 and trigger the incremental correction logic, that is, when the air replenishment action is executed next time, the amplitude of the air replenishment pressure pulse will be increased by a preset step size to strengthen the reshaping force. The number of repetitions can be set from 1 to 5. When the retry counter fails to rise after exceeding the set number of times, the main controller determines that the physical bonding has failed, outputs a maintenance alarm, and maintains a safe negative pressure. By adding damping ratio recovery confirmation and degassing and re-curing process after recovery action, the secondary pressing can not only change the shape of the flexible capsule 12, but also bring the apparent solid-liquid conversion silver-plated alumina microspheres 13 back to a stable working state suitable for high frequency conduction. The preset standard window can be determined as follows: under the target installation position, target negative pressure level and qualified fit condition, collect multiple echo damping ratio data continuously, and take the allowable fluctuation range near the mean value as ζmin to ζmax; when the material, surface curvature or capsule specification of the object being tested is different, the main control computer calls the independent window parameters under the corresponding working condition. The significance of returning to the preset standard window is to confirm that the coupling interface has recovered from an abnormally loose or partially detached state to an acceptable state, rather than directly assuming that the fit has been successfully restored based solely on the recovery of the negative pressure value. To avoid misjudgment caused by random fluctuations in a single measurement, the main control unit can require that the test results fall within the preset standard window for 2 to 5 consecutive times before performing the subsequent re-curing action; if any of them exceeds the window, the recovery state will continue or the second pressing step will be repeated. Controlling the lifting performance of the proportional valve 19 to its limit means gradually increasing the output of the proportional valve 19 to the upper limit of the current structure's working setting or the upper limit of the preset target negative pressure, rather than necessarily reaching the physical limit negative pressure of the vacuum pump. Its physical purpose is to enable the apparent solid-liquid conversion silver-plated alumina microspheres 13 to regain sufficient constraint stress and form a stable conductive skeleton, while avoiding local stress concentration in the capsule due to excessive suction. The main control unit preferably executes the following sequence: whether the damping ratio has returned to the window, staged pressure increase and suction after returning to the window, and then re-verification of the damping ratio, so that the recovery confirmation, re-curing and stability verification form a continuous closed loop; In the re-curing stage, the envelope attenuation damping ratio is preferred as the main verification quantity, and the frequency shift reference index is preferred as the auxiliary verification quantity: when the damping ratio has returned to the preset standard window and the frequency shift index has returned to the allowable range of the corresponding working condition, it is determined that the restored particle conduction layer has both sufficient fit and high-frequency propagation characteristics consistent with the standard state. If the frequency shift is still below the preset frequency shift reference lower limit after the damping ratio returns to the window, it indicates that the local high-frequency propagation link has not been fully restored. At this time, the main controller can slow down the pumping slope and extend the recovery state holding time before retesting. This allows the determination of successful recovery to cover both the time domain energy consumption state and the frequency domain propagation state, avoiding premature triggering of the re-solidification action based solely on a single damping parameter.

[0033] This application has been described through the above embodiments; however, it should be understood that the above embodiments are for illustrative purposes only and are not intended to limit this application to the described embodiments. Those skilled in the art will understand that many more variations and modifications can be made based on the teachings of this application, and all such variations and modifications fall within the scope of protection claimed in this application.

Claims

1. A partial discharge detection test device, characterized in that, include: The reference support part (2) includes a rigid support flange (3) and a pneumatic bellows (4). A positive pressure drive chamber (5) is formed inside the pneumatic bellows (4). An air inlet (20) is opened on the pneumatic bellows (4). The tail end of the pneumatic bellows (4) is sealed to the periphery of the rigid support flange (3) by airtight adhesive, and its front end is sealed to a rigid movable collar (6). The spindle sensing function unit (7) is coaxially inserted through the inner hole of the rigid movable collar (6), including a central spindle (8) with an internal channel (10) and a piezoelectric sensing chip array (9) fixed to the front end face of the central spindle (8); The reference support unit (2) drives the spindle sensing function unit (7) to move axially; The adaptive coupling function unit (11) is located at the front end of the main shaft sensing function unit (7). It includes apparent solid-liquid conversion silver-plated alumina microspheres (13) and a flexible capsule (12) that covers the periphery of the piezoelectric sensing chip array (9) and is sealed and fixed by clamps along the outer wall of the central main shaft (8). The coupling cavity (14) inside is filled with apparent solid-liquid conversion silver-plated alumina microspheres (13). The compensation suction function unit (15) is located between the main shaft sensing function unit (7) and the flexible capsule (12), including a negative pressure suction tube (16) and an inverted multi-stage folded diaphragm plate (17) connected between the rear end of the central main shaft (8) and the rigid support flange (3). The inverted multi-stage folded diaphragm plate (17) has a compensation air chamber (18) inside. The rigid support flange (3) has an atmospheric conduction hole that connects to the external atmosphere, so that the external atmospheric pressure can always act on the rear surface of the inverted multi-stage folded diaphragm plate (17) facing away from the compensation air chamber (18). One end of the negative pressure suction tube (16) passes through the internal channel (10) and connects to the coupling inner cavity (14), and the other end is connected to the proportional valve (19); The main control unit is connected to the control reference support unit (2), the spindle sensing function unit (7), the adaptive coupling function unit (11), and the compensation suction function unit (15).

2. The partial discharge detection test apparatus according to claim 1, characterized in that, The flexible capsule (12) is a sealed encapsulated capsule container made of polyurethane elastomer material.

3. The partial discharge detection test apparatus according to claim 1, characterized in that, The proportional valve (19) is connected to an external vacuum pump (22), and the inner cavity of the compensation gas chamber (18) is directly connected to the negative pressure suction pipe (16) to share a negative pressure source.

4. The partial discharge detection test apparatus according to claim 1, characterized in that, The air inlet (20) is connected to an external positive pressure air source (21), wherein the positive pressure drive chamber (5) receives low-pressure gas and presents a single-chamber corrugated unfolding shape.

5. The partial discharge detection test apparatus according to claim 1, characterized in that, The inner surface of the rigid movable collar (6) is machined with a self-lubricating physical coating.

6. A control method for a partial discharge detection test device, applied to the partial discharge detection test device according to claim 1, characterized in that, include: S1. Control the reference support (2) to fill the positive pressure drive chamber (5) with driving gas, and the pneumatic bellows (4) pushes and controls the spindle sensing function (7) and the adaptive coupling function (11) to change the enveloping motion trajectory under pressure. S2. Control the compensation suction function (15) to draw a vacuum, the flexible capsule (12) is subjected to negative pressure and shrinks in shape, and the apparent solid-liquid conversion silver-plated alumina microspheres (13) are controlled to be converted into solid interlocking chains with high elastic modulus due to forced interlocking. S3. Control the negative pressure in the negative pressure suction tube (16) to be synchronously transmitted to the compensation air chamber (18) of the inverted multi-stage folded membrane disc (17). The external atmospheric pressure overcomes the negative pressure in the compensation air chamber (18) and acts on the rear surface of the inverted multi-stage folded membrane disc (17), causing the structure to extend and fold forward axially. The inverted multi-stage folded membrane disc (17) provides a forward thrust, which cancels out the backward traction force of the flexible capsule (12) and locks the position of the central main shaft (8). S4. Control the piezoelectric sensing chip array (9) to emit short-wave ultrasonic guided waves with broadband parameter calibration into the apparent solid-liquid conversion silver-plated alumina microspheres (13) and excite full-segment reflection, and receive the reflected echo; S5. Extract the peak amplitude of the reflected echo and compare it with the attenuation rate of the subsequent reflected echo amplitude to extract the envelope attenuation damping ratio parameter data representing the acoustic reflection impedance boundary. S6. Extract the main wave frequency of the shortwave ultrasonic guided wave and perform a frequency comparison operation with the main wave frequency of the reflected echo to obtain the spectrum shift reference index; S7. Based on the envelope attenuation damping ratio parameter data and the frequency shift reference index, call the pre-calibrated damping and stiffness mapping relationship, perform a difference operation between the pre-stored standard damping ratio and the envelope attenuation damping ratio parameter data to obtain the difference value, multiply it by the pre-calibrated medium porosity correlation conversion coefficient, calculate the current acoustic stiffness reduction ratio, and determine whether the current acoustic stiffness reduction ratio is greater than the pre-set error tolerance boundary. S8. If the current acoustic stiffness decrease ratio is less than or equal to the preset error tolerance boundary, maintain the current negative pressure state; if the current acoustic stiffness decrease ratio is greater than the preset error tolerance boundary, reduce the negative pressure extraction power of the proportional valve (19), so that the apparent solid-liquid conversion silver-plated alumina microspheres (13) present a loose fluidized state to reshape the wrapping position, and perform a secondary pressure recovery action to increase the pressure of the positive pressure drive chamber by airflow replenishment triggering to the pneumatic bellows (4); Based on the preset detection cycle, steps S4 to S8 are executed repeatedly until the partial discharge detection operation is completed.

7. The control method for a partial discharge detection test device according to claim 6, characterized in that, Step S2 includes: S0. Wait until the probe surface morphology composed of the main shaft sensing function unit (7) and the adaptive coupling function unit (11) is completely attached to and covers the irregular surface of the external device under test, and determine that the deformation tension has reached the preset extreme value upper limit.

8. The control method of the partial discharge detection test device according to claim 6, characterized in that, Between steps S3 and S4, the following steps are included: controlling the acquisition front end to forcibly cut off the direct monitoring of partial discharge, and performing pulse passive detection in the silent gap region where the partial discharge monitoring signal is determined to be lower than the background threshold.

9. The control method for a partial discharge detection test device according to claim 6, characterized in that, After triggering the secondary pressure recovery action to increase the pressure of the positive pressure drive chamber in step S8, the following steps are included: controlling the real-time envelope attenuation damping ratio parameter data before detection to rise back to the preset standard window; controlling the pumping performance of the proportional valve (19) to reach the limit, causing the apparent solid-liquid conversion silver-plated alumina microspheres (13) to solidify.

Images