Partial discharge sensor structure and detection method with interdigital structure

Abstract

The present invention relates to a local discharge sensor structure with an interdigital structure and a detection method, comprising a support frame part (6); a sensor assembly is arranged on the support frame part (6); the sensor assembly comprises an angle-adjustable pulse near magnetic field sensor; the angle-adjustable pulse near magnetic field sensor comprises an electrically connected first wire rod antenna part (1) and a second wire rod antenna (2); the present invention has a reasonable design, a compact structure and is easy to use.

Description

Technical Field

[0001] The present invention relates to a partial discharge sensor structure and a detection method of an interdigital structure. The present invention relates to the field of partial discharge detection technology, and more specifically to a sensor structure and a detection method for accurately locating a discharge source inside a high-voltage bushing type device. Background Art

[0002] High-voltage bushings are widely used in power equipment such as power transformers, open circuit breakers, outdoor lightning arresters, current transformers, and voltage transformers. In recent years, there have been many insulation failures of high-voltage bushings, most of which are caused by partial discharge inside the bushing, which leads to the degradation of the insulation system and even breakdown failures, posing great safety hazards to the operation of the power grid. At present, the partial discharge detection methods for high-voltage bushing equipment mainly include high-frequency method, far-field radio frequency method, and ultrasonic detection method. Actual tests have proved that the high-frequency method is greatly affected by interference on site, and there are actual situations such as the location of the on-site detection point is high and close to the high voltage, the ground bus and the structure are close to the sensor, and it is not easy to install. The on-site use is difficult; the far-field radio frequency method (including the ultra-high frequency detection method) has a certain detection sensitivity, but it is impossible to determine the fault location through a single sensor. If positioning is required, multiple sensors and high-speed oscilloscopes are required to perform multi-point joint calculations and solve equations. The sensor layout requirements are high, the calculations are complex, and the positioning accuracy is poor. In addition, the general detection site has strong electromagnetic interference signals, and the long-distance radio frequency detection method is easily affected by the interference signals of surrounding equipment; the remote ultrasonic method,

[0003] The acoustic imaging method can only detect the corona and creepage energy signals outside the casing, but cannot detect the discharge signals inside the casing.

[0004] Therefore, how to provide a local discharge detection sensor structure and detection method designed according to the characteristics of the bushing structure, which can detect the internal discharge of the high-voltage bushing and accurately locate the discharge position when it is energized on site, is an urgent problem that technicians in this field need to solve. Summary of the invention

[0005] The technical problem to be solved by the present invention is generally to provide a partial discharge sensor structure and detection method of an interdigital structure, which has high sensitivity and more accurate spatial positioning, and does not require the use of high-speed acquisition processing equipment such as oscilloscopes. The sensor is suitable for scanning the equipment to be detected on site, and accurate spatial positioning is achieved by using the sensor's guidance and amplitude difference.

[0006] To solve the above problems, the technical solution adopted by the present invention is:

[0007] A local discharge sensor structure with an interdigital structure comprises a support frame portion; a sensor assembly is arranged on the support frame portion; the sensor assembly comprises an angle-adjustable pulse near magnetic field sensor; the angle-adjustable pulse near magnetic field sensor comprises an electrically connected first wire rod antenna portion and a second wire rod antenna.

[0008] As a further improvement of the above technical solution:

[0009] The first wire rod antenna part and the second wire rod antenna are made of ferrite magnetic rods with enameled wire wound outside.

[0010] The exterior of the wire rod antenna is integrally cast with silicone rubber;

[0011] The head end of the first wire rod antenna part and the end of the second wire rod antenna are connected to the interface of the signal processing unit arranged on the support frame part to output the collected radio frequency electromagnetic wave signal.

[0012] The sensor assembly includes an ultrasonic sensor assembly, which includes an ultrasonic extension probe, which is electrically connected to a partial discharge ultrasonic sensor; the ultrasonic extension probe is connected to the partial discharge ultrasonic sensor unit; the first wire rod antenna part and the second wire rod antenna form a V-shaped, U-shaped or C-shaped opening angle structure, which is used to contact the high-voltage bushing to be tested;

[0013] The ultrasonic extension probe and the receiving end surface of the partial discharge ultrasonic sensor are made of ceramic material.

[0014] Apply an appropriate amount of ultrasonic coupling agent between the head and the receiving end surface of the partial discharge ultrasonic sensor and fit them together;

[0015] During the test, apply an appropriate amount of ultrasonic coupling agent to the front end of the ultrasonic extension probe.

[0016] The front end fits tightly with the bushing under test to receive the discharge signal inside the high-voltage bushing.

[0017] The partial discharge ultrasonic sensor comprises a shielding shell; an acoustic-to-electric converter is arranged in the shielding shell.

[0018] A coupling ceramic sheet is provided at the end of the electric converter; a signal lead wire is electrically connected to the acoustic-electric converter.

[0019] A sound-absorbing filler is provided between the shielding shell and the acoustic-electric converter;

[0020] The coupling ceramic plate transmits the ultrasonic signal received by the ultrasonic extension probe to the acoustic-electric converter to convert the pressure wave into a voltage signal;

[0021] The voltage signal is led out to the partial discharge ultrasonic sensor unit through the signal lead-out line; the external interference signal introduced by the shielding shell;

[0022] The partial discharge ultrasonic sensor unit includes an acoustic sensing drive unit, a signal extraction unit and a post-stage output unit; the acoustic-to-electric converter converts the ultrasonic signal into a voltage signal; the acoustic sensing drive unit converts the input signal impedance from a high-resistance state to a low-resistance state;

[0023] The acoustic sensing driver has a fixed 20dB voltage gain;

[0024] The signal extraction unit is used to form a closed-loop system with the main controller in the measured environment, and to perform machine learning to adjust the filter frequency band in the sound perception signal extraction unit to obtain the best SNR;

[0025] The post-stage output unit has a current output capability of 150mA;

[0026] The signal processing unit interface connects the output signals of the adjustable pulse near magnetic field sensor and the ultrasonic sensor unit to the aviation plug, which is used for electrical connection with the detection host and the wireless signal processing module.

[0027] The sensor is equipped with an insulating measuring rod; the insulating measuring rod comprises a rod portion, a fixed connecting portion is arranged at the end of the rod; an extension rod is connected to the fixed connecting portion; and a first supporting frame is connected to the extension rod;

[0028] A first half seat is provided at one end of the first support frame, a rope guide seat is provided at the other end, and a telescopic hinge rod is provided in the middle;

[0029] The middle part of the second movable frame is hinged on the telescopic hinge rod through a hinge joint; a second half seat is arranged at one end of the second movable frame; a reset spring is connected between the second movable frame and the first support frame; a movable coil seat is arranged at the other end of the second movable frame, and the movable coil seat is reset by a motor or a coil spring;

[0030] A bottom coiling seat is provided on the fixed connection portion;

[0031] The movable reel seat is connected to the rope guide seat through a traction rope, and the rope guide seat pulls the traction rope through a motor or a handle;

[0032] Arc sheet spacers are connected in the corresponding process grooves of the first half seat and the second half seat through adjusting springs respectively, so as to embrace the high-voltage bushing.

[0033] The partial discharge ultrasonic sensor unit includes an electrically connected acoustic sensing drive unit, a signal extraction unit and a post-stage output unit.

[0034] The sound sensing drive unit includes resistors R2, R3, R4, R5, R6, R7, R8, R9,

[0035] R10, R11, RP1, capacitor C3 and chip U1;

[0036] The acoustic sensing drive unit changes the input signal impedance from a high impedance state to a low impedance state, which has a fixed 20dB voltage gain.

[0037] R13, R14, R15, R16, R17 and chip U2;

[0038] The signal sensed by the ultrasonic sensor is converted into a voltage signal by connecting the sampling resistor R1 through the connector JP1, and coupled to the sound sensing drive unit (3-1) through the capacitor C1, and then connected to the sound sensing drive unit (3-1) through the diodes D1 and D2.

[0039] Overvoltage protection is performed; the sound perception driving unit (3-1) is connected to the signal extraction unit via the capacitor C4; the resistor RP1 adjusts the amplitude of the sound perception signal within a set range;

[0040] The signal extraction unit extracts and filters the signal and then connects it to the post-stage output unit through capacitor C6. The chip U2 amplifies and drives the signal and connects it to the signal processing unit interface through JP2.

[0041] A partial discharge detection method comprises a partial discharge sensor structure with an interdigital structure. During testing, the partial discharge sensor is fixed on a high-voltage insulating rod, and an adjustable pulse near magnetic field sensor and an ultrasonic extension probe are directly pushed to the groove between the sheds of a tested bushing through the insulating rod to receive the discharge signal inside the bushing.

[0042] As a further improvement of the above technical solution:

[0043] When the insulating rod contacts the groove between the sheds of the high-voltage bushing under test, perform the following steps:

[0044] First, adjust the telescopic hinged rod, bind the sensor structure to the end of the insulating rod, and set the rod away from the high-voltage bushing; then, manipulate the rod so that the first half seat and the second half seat are located on both sides of the high-voltage bushing; secondly, manipulate the extension rod and the telescopic hinged rod so that the arc sheet spacer embraces the high-voltage bushing to achieve insulation clamping; thirdly, perform detection;

[0045] When it is necessary to move up and down, start the bottom coil seat and pull the second movable frame, so that the second movable frame swings and opens around the hinge joint, and then moves to the set position, releases the bottom coil seat, and under the action of the restoring force of the reset spring, the arc sheet spacer is clamped and embraced again.

[0046] Compared with the existing spatial radio frequency detection and positioning methods, the near-field radio frequency antenna is used, the positioning is accurate, and external space interference is avoided. There is no need to use multiple sensors and high-speed oscilloscopes. The on-site operation is simple and does not require equation solving and calculation, and the positioning result is more intuitive. The near-field spatial pulse radiation positioning sensor is used, and it is only necessary to scan and detect along the outside of the device to be positioned, and the spatial position of the discharge source can be located according to the changes in amplitude and direction, which has good economy and applicability. The present invention has a reasonable design, low cost, strong and durable, safe and reliable, simple operation, time-saving and labor-saving, money-saving, compact structure and easy use. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0048] Figure 2 Schematic diagram of the partial discharge ultrasonic sensor structure.

[0049] Figure 3 Block diagram of the partial discharge ultrasonic sensor unit.

[0050] Figure 4 Circuit schematic diagram of partial discharge ultrasonic sensor unit.

[0051] Figure 5 It is a schematic diagram of a preferred use structure of the present invention.

[0052] Figure 6 It is a schematic diagram of the high voltage bushing structure of the present invention.

[0053] 1. First wire rod antenna; 2. Second wire rod antenna; 3. Ultrasonic extension probe; 4. Partial discharge ultrasonic

[0054] Acoustic sensor; 5. Partial discharge ultrasonic sensor unit; 6. Support frame; 7. Signal processing unit interface;

[0055] 2-1, coupling ceramic plate; 2-2, acoustic-electric converter; 2-3, signal lead wire; 2-4, shielding shell;

[0056] 2-5, sound absorbing filler; 3-1, sound sensing drive unit; 3-2, signal extraction unit; 3-3, post-stage output unit; 8, fixed connection part; 9, extension rod; 10, first support frame; 11, first half

[0057] seat; 12, second movable frame; 13, second half seat; 14, adjustment spring; 15, process groove;

[0058] 16. Telescopic hinged rod; 17. Hinge head; 18. Movable coil seat; 19. Traction rope; 20. Rope guide seat; 21. Bottom coil seat; 22. Reset spring; 23. Connecting part; 24. Ultrasonic extension probe; 25. Near-field wire rod antenna; 26. High-voltage bushing. DETAILED DESCRIPTION

[0059] like Figure 1-6 The sensor structure of the present invention is designed for the layered structure of the high-voltage bushing, and a forked-finger near-field radio frequency probe and an ultrasonic extension probe are designed to be inserted into the gap of the bushing shed and closely attached to the outer wall of the bushing. The pulsed electromagnetic wave is received by near-field induction, and the local discharge source inside the bushing is spatially geometrically located in combination with the ultrasonic signal.

[0060] The sensor can receive pulsed electromagnetic waves through near-field induction and receive ultrasonic waves through contact

[0061] The ultrasonic signal caused by internal discharge is collected to accurately locate the local discharge source inside the high-voltage bushing. The sensor includes: an angle-adjustable pulse near-magnetic field sensor, a sensor metal shielding bracket, an ultrasonic extension probe, a partial discharge ultrasonic sensor, a partial discharge ultrasonic sensing unit, and a signal processing unit interface.

[0062] Compared with existing far-field RF sensors, it has the advantages of contact detection, high sensitivity and precise positioning.

[0063] It has the advantages of high accuracy, no electromagnetic interference from surrounding equipment, and acoustic and electrical complementarity.

[0064] The embodiment of the present invention discloses a partial discharge sensor with an interdigital structure, which can receive pulse electromagnetic waves through near-field induction and accurately locate the local discharge source inside the casing equipment in combination with a contact ultrasonic detection sensor. The sensor includes: an angle-adjustable pulse near-magnetic field sensor, a sensor metal shielding bracket, an ultrasonic extension probe, a partial discharge ultrasonic sensor, a partial discharge ultrasonic sensing unit, and a signal processing unit interface.

[0065] The adjustable pulse near magnetic field sensor is a double-wire rod structure, comprising a first wire rod antenna part 1 and a second wire rod antenna part 2.

[0066] The wire rod antenna 2 is connected to the metal shielding bracket by a flexible gooseneck structure. The angles of the two wire rod antennas can be adjusted within a range of 20-120 degrees, and can fit high-voltage bushing equipment with different diameters.

[0067] The wire rod antenna is made of ferrite rod with enameled wire wound on the outside, and the outside is cast with silicone rubber.

[0068] The first wire rod antenna part 1 and the second wire rod antenna 2 are wound in the same direction, the tail end of the first wire rod antenna part 1 is connected in series with the head end of the second wire rod antenna 2, and the lead wires of the head end of the first wire rod antenna part 1 and the tail end of the second wire rod antenna 2 are led to the interface of the signal processing unit. The wire rod antenna receives a signal at a frequency of

[0069] 1~100MHz, receiving distance is less than 0.5m, and is not affected by far-end interference.

[0070] Ultrasonic detection uses an ultrasonic extension probe 3 to transmit ultrasonic signals to a partial discharge ultrasonic sensor 4.

[0071] The ultrasonic extension probe 3 uses a ceramic rod, the diameter of which is consistent with the coupling ceramic piece receiving the signal at the front end of the partial discharge ultrasonic sensor 4, to ensure full fit, and a proper amount of ultrasonic coupling agent is applied to the contact surface to minimize signal conduction loss. The ultrasonic extension probe 3 can adopt an elastic telescopic structure to ensure reliable contact between the front end of the extension probe and the outer wall of the casing.

[0072] The local discharge ultrasonic sensor unit 5 is as follows Figure 3 As shown, the sound perception driving unit 3-1 and the signal extraction unit

[0073] It is composed of element 3-2 and post-stage output unit 3-3.

[0074] The circuit schematic diagram of the partial discharge ultrasonic sensor unit 5 is as follows: Figure 4 shown.

[0075] Figure 4 R2, R3, R4, R5, R6, R7, R8, R9, R10, R11, RP1, C3, U1 in the sound sensing drive

[0076] The acoustic sensing driving unit 3-1 changes the input signal impedance from a high impedance state to a low impedance state.

[0077] It has a fixed 20dB voltage gain.

[0078] Figure 4 The automatic frequency selection filter U3 in the signal extraction unit 3-2 constitutes the signal extraction unit 3-2. The signal extraction unit 3-2 can form a closed-loop system with the main controller in the measured environment, perform machine learning to adjust the filter frequency band and obtain the best SNR.

[0079] Figure 4 R12, R13, R14, R15, R16, R17, and U2 constitute the rear output unit 3-3 of the driving unit. The rear output unit 3-3 has a current output capability of 150 mA.

[0080] The signal processing flow of the partial discharge ultrasonic sensor unit is as follows:

[0081] The ultrasonic sensor output signal is passed through Figure 4 JP1 in the PCB is connected to the partial discharge ultrasonic sensor unit. Figure 4

[0082] The sampling resistor R1 in the ultrasonic sensor converts the signal sensed by the ultrasonic sensor into a voltage signal. Figure 4 The C1 capacitor is coupled to the acoustic sensing driver, Figure 4D1 and D2 in the circuit are overvoltage protection circuits to prevent the abnormal signal amplitude sensed by the ultrasonic sensor from exceeding the limit voltage of the subsequent unit and damaging the subsequent units. Figure 4 C4 in is connected to the signal extraction unit. Figure 4 RP1 can adjust the amplitude of the acoustic perception signal within a certain range. Figure 4 The signal extraction unit in the Figure 4 C6 is connected to the post-stage output unit, and the post-stage output unit U2 amplifies and drives the signal and is connected to the signal processing unit interface through JP2.

[0083] In some embodiments, the first wire rod antenna part 1 and the second wire rod antenna 2 of the near-field receiving sensor are wound with enameled wires with a diameter of 0.5 mm to 1 mm, with 5 to 15 turns. The diameter of the enameled wire is preferably

[0084] 0.5mm, winding number 12 turns.

[0085] The sensor is equipped with an insulating measuring rod; the insulating measuring rod includes a rod portion, and a fixed

[0086] A fixed connection portion 8; an extension rod 9 is connected to the fixed connection portion 8; a first extension rod 9 is connected to the extension rod

[0087] Support frame 10;

[0088] A first half seat 11 is provided at one end of the first support frame 10, and a rope guide seat is provided at the other end.

[0089] 20, a telescopic hinge rod 16 is provided in the middle;

[0090] The middle part of the second movable frame 12 is hinged on the telescopic hinge rod 16 through the hinge joint 17;

[0091] A second half seat 13 is provided at one end of the movable frame 12; a reset spring 22 is connected between the second movable frame 12 and the first support frame 10; a movable coil seat 18 is provided at the other end of the second movable frame 12, and the movable coil seat 18 is reset by a motor or a coil spring;

[0092] A bottom coiling seat 21 is provided on the fixed connection portion 8;

[0093] The movable coil seat 18 is connected to the rope guide seat 20 through the traction rope 19.

[0094] The traction rope 19 is pulled by a motor or a handle;

[0095] The corresponding process grooves 15 of the first half seat 11 and the process grooves 15 of the second half seat 13 are divided into

[0096] The arc-plate spacer is connected via the adjusting spring 14 to embrace the high-voltage bushing 26 .

[0097] The sensor is tested in a powered state. Since the sensor is in a high voltage field environment,

[0098] The parts close to the frame and the casing are made of insulating materials. In addition, during inspection, the personnel need to be more than two meters away from the casing, and automatic adaptation or remote adjustment is preferred.

[0099] The partial discharge ultrasonic sensor unit 5 includes an acoustic sensing driving unit 3-1, a signal extraction unit 3-2 and a post-stage output unit 3-3 which are electrically connected.

[0100] The acoustic sensing driving unit 3-1 includes resistors R2, R3, R4, R5, R6, R7, R8,

[0101] R9, R10, R11, RP1, capacitor C3 and chip U1;

[0102] The acoustic sensing driving unit 3-1 changes the input signal impedance from a high impedance state to a low impedance state, which has a fixed

[0103] The voltage gain is set to 20dB.

[0104] R13, R14, R15, R16, R17 and chip U2;

[0105] The signal sensed by the ultrasonic sensor is converted into a voltage signal by connecting the sampling resistor R1 through the connector JP1, coupled to the acoustic sensing drive unit 3-1 through the capacitor C1, and overvoltage protection is performed through the diodes D1 and D2; the acoustic sensing drive unit 3-1 is connected to the signal extraction unit 3-2 through the capacitor C4;

[0106] The resistor RP1 adjusts the amplitude of the acoustic perception signal within the set range;

[0107] The signal extraction unit 3-2 extracts and filters the signal and then connects it to the output unit of the next stage through the capacitor C6.

[0108] Element 3-3 is connected, chip U2 amplifies and drives the signal and is connected to the signal processing unit interface through JP2.

[0109] The partial discharge detection method of this embodiment includes a partial discharge sensor structure of an interdigital structure.

[0110] During the test, the partial discharge sensor is fixed on the high-voltage insulating rod, and the adjustable pulse near magnetic field sensor and the ultrasonic extension probe are directly pushed to the groove between the sheds of the tested bushing through the insulating rod to receive the discharge signal inside the bushing.

[0111] When the insulating rod contacts the groove between the sheds of the high-voltage bushing 26 to be tested, the following steps are performed:

[0112] First, the sensor structure is tied to the end of the insulating rod, and the rod is set away from the high-voltage bushing 26; then, the rod is manipulated to adjust the telescopic hinge rod 16 so that the first half seat 11 and the second half seat 13 are located on both sides of the high-voltage bushing 26; secondly, the extension rod 9 and the telescopic hinge rod 16 are manipulated so that the arc sheet spacer embraces the high-voltage bushing 26 to achieve insulation clamping; and finally, detection is performed;

[0113] When it is necessary to move up and down, the bottom coil seat 21 is started to pull the second movable frame 12, so that the second movable frame 12 swings around the hinge head 17 and opens, and then moves to the set position, releases the bottom coil seat 21, and under the action of the restoring force of the reset spring 22, the arc sheet spacer is clamped and embraced again.

[0114] The sensor can be tied or bolted to the insulating rod, which can achieve the fit of the casing.

[0115] Thereby, straightening is achieved. The length and position are adjusted by controlling the extension rod 9, and the half seat is adjusted according to different sleeves by the telescopic hinged rod 16. It can be pre-adjusted, and the hinged opening and closing of the half seat is achieved by ropes to achieve the engagement of the sleeve, and resetting is achieved by a spring. Micro-adjustment and adaptation are achieved by adjusting the spring. It is compatible, simple and portable, easy to operate, and has strong versatility.

[0116] The present invention is fully described for a clearer disclosure, and the prior art is not listed one by one.

[0117] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention, and are not intended to

[0118] Limitation: Although the present invention is described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments can still be modified, or some of the technical features can be replaced by equivalents; it is obvious for a person skilled in the art to combine multiple technical solutions of the present invention. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A partial discharge detection method, characterized in that: A partial discharge sensor structure including an interdigitated structure; A partial discharge sensor structure comprises a support frame portion (6); a sensor assembly is disposed on the support frame portion (6); the sensor assembly comprises an angle-adjustable pulse near magnetic field sensor; the angle-adjustable pulse near magnetic field sensor comprises an electrically connected first wire rod antenna portion (1) and a second wire rod antenna (2); The first wire rod antenna part (1) and the second wire rod antenna (2) are made of enameled wire wound around the outside of a ferrite magnetic rod, and the outside of the wire rod antenna is integrally cast with silicone rubber; The head end of the first wire rod antenna part (1) and the end end of the second wire rod antenna (2) are connected to a signal processing unit interface (7) arranged on the support frame part (6) to output the collected radio frequency electromagnetic wave signal; The sensor assembly also includes an ultrasonic sensor assembly, which includes an ultrasonic extension probe (3), the ultrasonic extension probe (3) being electrically connected to a partial discharge ultrasonic sensor (4); the ultrasonic extension probe (3) being connected to a partial discharge ultrasonic sensor unit (5); the first wire rod antenna portion (1) and the second wire rod antenna (2) forming a V-shaped, U-shaped or C-shaped opening angle structure, and being used to contact the high-voltage bushing (26) to be tested; The ultrasonic extension probe (3) and the receiving end surface of the partial discharge ultrasonic sensor (4) are made of ceramic material, and an appropriate amount of ultrasonic coupling agent is applied between the ultrasonic extension probe (3) and the receiving end surface of the partial discharge ultrasonic sensor (4) and the two are bonded together; During the test, a proper amount of ultrasonic coupling agent is applied to the front end of the ultrasonic extension probe (3), and the front end of the ultrasonic extension probe (3) is tightly fitted to the bushing to be tested to receive the internal discharge signal of the high-voltage bushing (26); The partial discharge ultrasonic sensor (4) comprises a shielding shell (2-4); an acoustic-electric converter (2-2) is arranged in the shielding shell (2-4); a coupling ceramic sheet (2-1) is arranged at the end of the acoustic-electric converter (2-2); a signal lead wire (2-3) is electrically connected to the acoustic-electric converter (2-2); and a sound-absorbing filler (2-5) is arranged between the shielding shell (2-4) and the acoustic-electric converter (2-2); The coupling ceramic sheet (2-1) transmits the ultrasonic signal received by the ultrasonic extension probe (3) to the acoustic-electric converter to convert the pressure wave into a voltage signal; The voltage signal is led out to the partial discharge ultrasonic sensor unit (5) via a signal lead-out line (2-3); The partial discharge ultrasonic sensor unit (5) comprises an acoustic sensing drive unit, a signal extraction unit and a post-stage output unit; the acoustic-to-electric converter converts the ultrasonic signal into a voltage signal; the acoustic sensing drive unit converts the input signal impedance from a high-resistance state to a low-resistance state; The acoustic sensing driver has a fixed 20dB voltage gain; The signal extraction unit is used to form a closed-loop system with the main controller in the measured environment, and to perform machine learning to adjust the filter frequency band in the signal extraction unit to obtain the best SNR; The post-stage output unit has a current output capability of 150mA; The signal processing unit interface (7) connects the output signals of the adjustable pulse near magnetic field sensor and the ultrasonic sensor unit to the aviation plug, and is used for electrical connection with the detection host and the wireless signal processing module; The sensor is equipped with an insulating measuring rod; the insulating measuring rod comprises a rod portion, and a fixed connecting portion (8) is arranged at the end of the rod; an extension rod (9) is connected to the fixed connecting portion (8); and a first support frame (10) is connected to the extension rod (9); A first half seat (11) is provided at one end of the first support frame (10), a rope guide seat (20) is provided at the other end, and a telescopic hinge rod (16) is provided in the middle; A middle portion of a second movable frame (12) is hingedly connected to the telescopic hinge rod (16) via a hinge joint (17); a second half seat (13) is arranged at one end of the second movable frame (12); a return spring (22) is connected between the second movable frame (12) and the first support frame (10); a movable coil seat (18) is arranged at the other end of the second movable frame (12), and the movable coil seat (18) is returned by a motor or a coil spring; A bottom coiling seat (21) is provided on the fixed connection portion (8); The movable coil seat (18) is connected to the rope guide seat (20) via a traction rope (19), and the rope guide seat (20) pulls the traction rope (19) via a motor or a handle; Arc-plate spacers are connected to the corresponding process grooves (15) of the first half seat (11) and the process grooves (15) of the second half seat (13) through adjustment springs (14) respectively, and are used to embrace the high-voltage bushing (26); The partial discharge ultrasonic sensor unit (5) comprises an acoustic sensing drive unit (3-1), a signal extraction unit (3-2) and a post-stage output unit (3-3) which are electrically connected; The sound sensing driving unit (3-1) includes resistors R2, R3, R4, R5, R6, R7, R8, R9, R10, R11, RP1, a capacitor C3 and a chip U1; The sound sensing driving unit (3-1) changes the input signal impedance from a high impedance state to a low impedance state, and has a fixed 20 dB voltage gain; The signal extraction unit (3-2) includes an automatic frequency selection filter U3; The post-stage output unit (3-3) includes resistors R12, R13, R14, R15, R16, R17 and a chip U2; The signal sensed by the ultrasonic sensor is converted into a voltage signal by connecting the sampling resistor R1 through the connector JP1, coupled to the sound sensing drive unit (3-1) through the capacitor C1, and overvoltage protection is performed through the diodes D1 and D2; the sound sensing drive unit (3-1) is connected to the signal extraction unit (3-2) through the capacitor C4; the resistor RP1 adjusts the amplitude of the sound sensing signal within a set range; The signal extraction unit (3-2) extracts and filters the signal and then connects it to the post-stage output unit (3-3) through the capacitor C6. The chip U2 amplifies and drives the signal and connects it to the signal processing unit interface through JP2. During the test, the partial discharge sensor is fixed on the insulating measuring rod, and the adjustable pulse near magnetic field sensor and the ultrasonic extension probe are directly pushed to the groove between the sheds of the measured bushing through the insulating measuring rod to receive the discharge signal inside the bushing.

2. The partial discharge detection method according to claim 1, characterized in that: When the insulating measuring rod contacts the groove between the sheds of the high-voltage bushing (26) to be measured, the following steps are performed; First, adjust the telescopic hinged rod (16), bind the sensor structure to the end of the insulating measuring rod, and set the rod part away from the high-voltage bushing (26); then, manipulate the rod part so that the first half seat (11) and the second half seat (13) are located on both sides of the high-voltage bushing (26); secondly, manipulate the extension rod (9) and the telescopic hinged rod (16) so that the arc sheet spacer embraces the high-voltage bushing (26) to achieve insulation clamping; and thirdly, perform detection; When it is necessary to move up and down, the bottom coil seat (21) is started to pull the second movable frame (12), so that the second movable frame (12) swings around the hinge joint (17) and opens, and then moves to the set position, releases the bottom coil seat (21), and under the action of the restoring force of the return spring (22), the arc sheet spacer is clamped and embraced again.

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