High-voltage cabinet wall-integrated acoustic-optic-electromagnetic composite sensor and installation method

Abstract

The present invention relates to an integrated acoustic-optic electromagnetic composite sensor for the wall of a high-voltage cabinet and an installation method. The sensor includes a complementary dipole double-patch antenna, a transient earth voltage probe, an ultrasonic probe, and an optical probe. The complementary dipole double-patch antenna includes an insulating cover, as well as an insulating plate and a metal patch assembly. The transient earth voltage probe includes two insulating sheets and two transient earth voltage metal patches. The ultrasonic probe includes a PZT sensor connected to the outer wall of the switch cabinet wall. The optical probe includes a plurality of fluorescent optical fibers symmetrically distributed in a ring around the outside of the insulating cover. Compared with the prior art, the design is simple and convenient for processing, realizing the simultaneous combined measurement of ultra-high frequency, transient earth voltage, ultrasonic, and optical signals generated by electromagnetic waves, ultrasonic waves, and optical pulse signals due to insulation defects in the internal components of high-voltage switch cabinets, achieving live detection / patrol inspection, and can also provide signals for on-line monitoring devices or intensive care systems.

Description

Technical Field

[0001] The present invention relates to the field of partial discharge detection of high-voltage switch cabinets, and in particular to an integrated acoustic-optic-electromagnetic composite sensor for the cabinet wall of a high-voltage cabinet and an installation method thereof. Background Art

[0002] High-voltage switch cabinets are direct devices for the distribution network that supply power to users. Their failures will cause power outages for users, thus bringing huge economic losses to the power grid and causing certain social impacts. In addition, under the current policy of creating a good business environment, ensuring high-quality and reliable power supply is the only way for power grid operation and maintenance. Due to the complex internal structure and small insulation distance of high-voltage switch cabinets, they are more likely to have insulation defects than other electrical equipment in the power grid. Under the conditions of moisture condensation, partial discharge (PD) phenomena such as surface creepage of equipment insulation occur. The long-term existence of PD will ultimately lead to insulation aging or deterioration and even damage of the equipment, and finally develop into an insulation breakdown accident of the high-voltage switch cabinet. Therefore, it is extremely important to judge the insulation status through on-line monitoring and live detection of PD in high-voltage switch cabinets.

[0003] Currently, the methods applied to detect PD signals in high-voltage switch cabinets mainly include ultrasonic (AE) detection method, transient earth voltage (TEV) detection method, and ultra-high frequency (UHF) detection method, etc. The optical pulse (OP) detection method has not been reported. After years of application, the ultrasonic detection method has formed the power industry standard DL / T 1416-2015 "General Technical Conditions for Partial Discharge Tester by Ultrasonic Method". After years of application, the transient earth voltage detection method has formed two power industry standards, namely DL / T 846.10-2016 "General Technical Conditions for High-Voltage Test Equipment Part 10: Partial Discharge Detection by Transient Earth Voltage" and DL / T 195-2018 "Calibration Specification for Partial Discharge Detector Based on Transient Earth Voltage Method". PD inside the switch cabinet will generate electromagnetic waves, which form a skin effect on the metal wall and propagate along the metal surface. At the same time, a transient earth voltage is generated on the metal surface. In the prior art, a special transient earth voltage sensor can be used to achieve signal detection or monitoring. Ultra-high frequency is a new technology developed in recent years. It judges whether PD occurs in the equipment by measuring the electromagnetic waves radiated by insulation hidden dangers of high-voltage equipment under operating voltage. This method can be measured non-contact and is widely used in on-line detection of electrical equipment. For the own characteristics of high-voltage switch cabinet equipment, as shown in Figure 8 (a)-(d), currently there are UHF detection sensors such as metal radiation patches, reconfigurable antennas (square loop microstrip patches), microstrip slot antennas, and snowflake-shaped microstrip antennas.

[0004] For the above ultrasonic and transient earth voltage detections, since they are external types, they are vulnerable to external electromagnetic interference, which often makes the testers doubt the obtained detection results and unable to determine whether the ultrasonic signals and electromagnetic signals come from inside the high-voltage switchgear or are generated by interference sources, thus missing the internal discharge signals and leading to serious short-circuit faults caused by insulation breakdown. For the existing UHF technology above, the processing of sensors is relatively complex, inconvenient for promotion and use by equipment manufacturers, and certain special conditions are required for installation, which greatly limits the use of this UHF detection method in the online monitoring and live detection of insulation defects PD of high-voltage switchgear equipment. Summary of the Invention

[0005] The purpose of the present invention is to provide an integrated acoustic-optic-electromagnetic composite sensor for the cabinet wall of a high-voltage cabinet and an installation method to overcome the defects of the above existing technologies.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A wall-integrated acoustic-optic-electromagnetic composite sensor for high-voltage switchgear cabinets, comprising a complementary dipole double-patch antenna, a transient earth voltage probe, an ultrasonic probe, and an optical probe. The complementary dipole double-patch antenna includes an insulating cover, as well as an insulating plate and a metal patch assembly. The metal patch assembly includes the same first metal patch and second metal patch. One side of the insulating plate is connected to the inner wall of the switchgear cabinet wall, and the other side symmetrically connects the first metal patch and the second metal patch. The insulating plate, the first metal patch, and the second metal patch are placed in a first cavity formed between the insulating cover and the inner wall of the switchgear cabinet wall. A gap is formed between the first metal patch and the second metal patch. The insulating plate is provided with a first through hole, and the switchgear cabinet wall is provided with a second through hole. The gap, the first through hole, and the second through hole are coaxial. One end of a first coaxial cable is conductively connected to the first metal patch and the second metal patch respectively, and the other end is conductively connected to a first coaxial cable connector through the gap, the first through hole, and the second through hole in sequence. The transient earth voltage probe includes two insulating sheets and two transient earth voltage metal patches. The insulating sheets and the transient earth voltage metal patches are arranged alternately and connected to each other. One of the insulating sheets is connected to the switchgear cabinet wall. One end of the cable core wire of a second coaxial cable is conductively connected to the outer transient earth voltage metal patch, and the other end is conductively connected to the second coaxial cable connector. The shielding layer of the second coaxial cable is conductively connected to the inner transient earth voltage metal patch and the working side of the inductor. The ultrasonic probe includes a PZT sensor connected to the outer wall of the switchgear cabinet wall. The PZT sensor is located in a third cavity formed by conductive connection between the first metal cover and the outer wall of the switchgear cabinet wall. The PZT sensor is conductively connected to a third coaxial cable connector. The transient earth voltage probe and the ultrasonic probe are located in a second cavity formed between the first metal cover and the outer wall of the switchgear cabinet wall. The second through hole is within the coverage of the first metal cover. The first coaxial cable connector and the third coaxial cable connector are conductively connected to the first metal cover. The second coaxial cable connector is insulated from the first metal cover. The grounding side of the inductor is conductively connected to the first metal cover. The optical probe includes a plurality of fluorescent optical fibers symmetrically distributed in a circular ring outside the insulating cover. The plurality of fluorescent optical fibers are connected to a coupler at the center of the circular ring through corresponding plurality of connectors. A single-mode optical fiber sequentially passes through a third through hole of the insulating cover, the gap, the first through hole, and the second through hole and is conductively connected to an optical fiber connector conductively connected to the first metal cover. The optical fiber connector is conductively connected to the first metal cover.

[0008] The optical probe includes 8 fluorescent optical fibers symmetrically distributed in a circular ring outside the insulating cover. The 8 fluorescent optical fibers are connected to a coupler at the center of the circular ring through corresponding 8 connectors.

[0009] A plurality of fluorescent optical fibers are symmetrically distributed in a circular ring on an organic glass plate. The organic glass plate is fixedly connected to the insulating cover. The insulating plate is a polyethylene insulating plate, and the insulating sheet is a phenolic plastic insulating sheet.

[0010] The second coaxial cable connector is connected to the first metal cover through an insulating washer.

[0011] The insulating cover is connected to the cabinet wall of the switchgear through insulating bolts, the first metal cover is connected to the cabinet wall of the switchgear through metal bolts, and the second metal cover is connected to the cabinet wall of the switchgear through metal bolts.

[0012] The first coaxial cable connector is connected to the first metal cover through metal bolts, the second coaxial cable connector is connected to the first metal cover through insulating bolts, the third coaxial cable connector is connected to the first metal cover through metal bolts, and the optical fiber connector is connected to the first metal cover through metal bolts.

[0013] One end of the cable core wire of the first coaxial cable is connected to the second metal patch, and the shielding layer of the first coaxial cable is connected to the first metal patch.

[0014] The insulating plate is adhesively bonded to the first metal patch and the second metal patch respectively, the insulating sheet is adhesively bonded to the transient earth voltage metal patch, one insulating sheet is adhesively bonded to the cabinet wall of the switchgear, and the insulating plate is adhesively bonded to the cabinet wall of the switchgear.

[0015] The first metal patch, the second metal patch and the two transient earth voltage metal patches are all copper patches.

[0016] An installation method for the integrated acoustic-optic electromagnetic composite sensor on the cabinet wall of the high-voltage cabinet, the method comprising the following steps:

[0017] Step S1: One end of the first coaxial cable is conductively connected to the feeding points of the first metal patch and the second metal patch respectively;

[0018] Step S2: The first metal patch and the second metal patch are symmetrically connected to one side of the insulating plate, the other side of the insulating plate is connected to the inner wall of the cabinet wall of the switchgear, and the second through hole, the gap and the first through hole are coaxial;

[0019] Step S3: The insulating cover is connected to the inner wall of the cabinet wall of the switchgear;

[0020] Step S4: The other end of the first coaxial cable is conductively connected to the first coaxial cable connector;

[0021] Step S5: Multiple fluorescent optical fiber symmetric rings are distributed outside the insulating cover and correspondingly connected to multiple connectors, the multiple connectors are connected to a coupler located in the center of the ring, the coupler is connected to a single-mode optical fiber, and the single-mode optical fiber sequentially passes through the third through hole, the gap, the first through hole and the second through hole and is conductively connected to the optical fiber connector;

[0022] Step S6: Two insulating sheets and two transient earth voltage metal patches are alternately arranged and connected, and one insulating sheet is connected to the outer wall of the cabinet wall of the switchgear;

[0023] Step S7: One end of the cable core of the second coaxial cable is conductively connected to the transient earth voltage metal patch on the outside, and the other end is conductively connected to the second coaxial cable connector. The shielding layer of the second coaxial cable is conductively connected to the transient earth voltage metal patch on the inside and the working side of the inductor.

[0024] Step S8: The PZT sensor is connected to the outer wall of the switch cabinet box wall, and the second metal cover is conductively connected to the outer wall of the switch cabinet box wall.

[0025] Step S9: The grounding side of the inductor is conductively connected to the first metal cover. The optical fiber connector, the first coaxial cable connector, and the third coaxial cable connector are conductively connected to the first metal cover. The second coaxial cable connector is insulated from the first metal cover, and the first metal cover is connected to the outer wall of the switch cabinet box wall.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] (1) Using a complementary dipole double-patch antenna, a capacitive voltage divider, a PZT sensor, and a fluorescence fiber enhanced optical detector as the UHF probe, transient earth voltage probe, ultrasonic probe, and optical probe of the acousto-optic-electromagnetic composite sensor respectively, the design is simple and convenient for processing, realizing the UHF, transient earth voltage, ultrasonic, and optical synchronous joint measurement of electromagnetic wave, ultrasonic wave, and optical pulse signals generated by the insulation defect discharge of internal components in the high-voltage switch cabinet.

[0028] (2) The installation (replacement or removal can be referred to) of the acousto-optic-electromagnetic composite sensor is easy and has few steps, greatly expanding its scope of use, and providing a reliable implementation method for the integration, modularization, and standardization of the equipment sensing unit.

[0029] (3) The acousto-optic-electromagnetic composite sensor uses an inductor to block the mutual influence of high-frequency electromagnetic wave signal propagation. The two output electromagnetic wave signals, one optical pulse signal, and the ultrasonic wave signals with a time difference Δt can corroborate each other, which can confirm whether the current detected signal comes from the insulation defect discharge inside the high-voltage switch cabinet, and can avoid missing the internal discharge signal and causing a serious short-circuit fault due to insulation breakdown.

[0030] (4) The formed acousto-optic-electromagnetic composite sensor uses the switch cabinet box body as the grounding plane, and the four signal output terminals can be operated under the live working condition to realize live detection / patrol inspection, and can also provide signals for the on-line monitoring device or the intensive care system. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a schematic structural diagram of the present invention;

[0032] Figure 2 is a sectional view taken along line A-A of the present invention;

[0033] Figure 3 Schematic diagram of the installation structure of the present invention;

[0034] Figure 4 Schematic diagram of the working principle of the transient earth voltage probe of the present invention;

[0035] Figure 5 Schematic diagram of the working principle of the optical probe of the present invention;

[0036] Figure 6 (a)-(i) Schematic diagram of the installation steps of the electromagnetic composite sensor of the present invention;

[0037] Figure 7 (a)-(c) 4-channel single discharge detection time-domain signals of the electromagnetic composite sensor of the present invention under different pressurization conditions;

[0038] Figure 8 (a) Metal radiation patch ultra-high frequency sensor in the prior art;

[0039] Figure 8 (b) Square ring microstrip patch ultra-high frequency sensor in the prior art;

[0040] Figure 8 (c) Microstrip slot antenna ultra-high frequency sensor in the prior art;

[0041] Figure 8 (d) Snowflake-shaped microstrip antenna ultra-high frequency sensor in the prior art;

[0042] Reference numerals:

[0043] 1 is an insulating board; 2 is a first metal patch; 3 is a second metal patch; 4 is an insulating cover; 5 is the cabinet wall of the switchgear; 6 is a first coaxial cable connector; 7 is a feeding point; 8 is a connector with a coaxial cable; 9 is the grounding resistance of the switchgear; 10 is a discharge source; 11 is a first coaxial cable; 12 is a second coaxial cable; 13 is a first through hole; 14 is a second through hole; 15 is a signal acquisition device; 16 is an insulating sheet; 17 is a transient earth voltage metal patch; 18 is an inductor; 19 is a third coaxial cable; 20 is a first metal cover; 21 is a second coaxial cable connector; 22 is an insulating washer; 23 is a third coaxial cable connector; 24 is a second metal cover; 25 is a PZT sensor; 26 is a fluorescent optical fiber; 27 is a coupler; 28 is a coupler; 29 is a third through hole; 30 is an optical fiber connector; 31 is an organic glass plate; 32 is a single-mode optical fiber. Detailed implementation manners

[0044] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented on the premise of the technical solution of the present invention, and detailed implementation manners and specific operation processes are given, but the protection scope of the present invention is not limited to the following embodiments.

[0045] Embodiment

[0046] This embodiment provides a high-voltage switchgear cabinet wall integrated acousto-opto-electromagnetic composite sensor, as Figure 1 shown, including a complementary dipole double-patch antenna for coupling ultra-high frequency electromagnetic wave signals composed of an insulating cover 4, a first metal patch 2, a second metal patch 3, an insulating board 1, a first coaxial cable connector 6 and a high-voltage switchgear cabinet wall 5; a capacitive voltage divider transient earth voltage probe composed of two transient earth voltage metal patches 17, two insulating sheets 16, an inductor 18, a second coaxial cable connector 21, a first metal cover 20 and a high-voltage switchgear cabinet wall 5 for coupling electromagnetic wave signals; a PZT sensor 25, a second metal cover 24, a third coaxial cable connector 23 and a high-voltage switchgear cabinet wall 5 for coupling ultrasonic signals to form an ultrasonic probe; an optical probe arranged on the insulating cover 4 and composed of a plurality of fluorescent optical fibers 26 connected in parallel for detecting optical pulse signals; thereby forming a high-voltage switchgear cabinet wall integrated acousto-opto-electromagnetic composite sensor for realizing the synchronous joint measurement of ultra-high frequency, transient earth voltage, ultrasonic and optical signals generated by insulation defects and discharges of internal components of a high-voltage switchgear cabinet, including electromagnetic waves, ultrasonic waves and optical pulse signals.

[0047] Specifically:

[0048] One side of the insulating board 1 is connected to the inner wall of the switchgear cabinet wall 5, and the other side symmetrically connects the first metal patch 2 and the second metal patch 3. The insulating board 1, the first metal patch 2 and the second metal patch 3 are placed in a first cavity formed by the insulating cover 4 and the inner wall of the switchgear cabinet wall 5. A gap is formed between the first metal patch 2 and the second metal patch 3. The insulating board 1 is provided with a first through hole 13, and the switchgear cabinet wall 5 is provided with a second through hole 14. The gap, the first through hole 13 and the second through hole 14 are coaxial. One end of the first coaxial cable 11 is conductively connected to the first metal patch 2 and the second metal patch 3 respectively, and the other end is conductively connected to the first coaxial cable connector 6 through the gap, the first through hole 13 and the second through hole 14 in sequence.

[0049] The insulating sheets 16 and the transient earth voltage metal patches 17 are arranged alternately and connected to each other. One of the insulating sheets 16 is connected to the switchgear cabinet wall 5. One end of the cable core wire of the second coaxial cable 12 is conductively connected to the outer transient earth voltage metal patch 17, and the other end is conductively connected to the second coaxial cable connector 21. The shielding layer of the second coaxial cable 12 is conductively connected to the inner transient earth voltage metal patch 17 and the working side of the inductor 18.

[0050] The PZT sensor 25 is located in the third cavity formed by the conduction connection between the first metal cover 20 and the outer wall of the switchgear cabinet wall 5. The PZT sensor 25 is conductively connected to the third coaxial cable connector 23. The transient earth voltage probe and the ultrasonic probe are located in the second cavity formed by the first metal cover 20 and the outer wall of the switchgear cabinet wall 5. The second through hole 14 is within the coverage of the first metal cover 20. The first coaxial cable connector 6 and the third coaxial cable connector 23 are conductively connected to the first metal cover 20. The second coaxial cable connector 21 is insulated from the first metal cover 20. The grounded side of the inductor 18 is conductively connected to the first metal cover 20.

[0051] The optical probe includes a plurality of fluorescent optical fibers 26 symmetrically distributed in a ring outside the insulating cover 4. The plurality of fluorescent optical fibers 26 are connected to the coupler 28 at the center of the ring through the corresponding plurality of connectors 27. The single-mode optical fiber 32 sequentially passes through the third through hole 29, the gap, the first through hole 13 and the second through hole 14 of the insulating cover 4 and is conductively connected to the optical fiber connector 30 conductively connected to the first metal cover 20.

[0052] The optical probe includes 8 fluorescent optical fibers 26 symmetrically distributed in a ring outside the insulating cover 4. The 8 fluorescent optical fibers 26 are connected to the coupler 28 at the center of the ring through the corresponding 8 connectors 27; a plurality of fluorescent optical fibers 26 are symmetrically distributed in a ring on the plexiglass plate 31. The plexiglass plate 31 is fixedly connected to the insulating cover 4. The insulating plate 1 is a polyethylene insulating plate, and the insulating sheet 16 is a phenolic plastic insulating sheet.

[0053] The second coaxial cable connector 21 is connected to the first metal cover 20 through an insulating washer 22.

[0054] The insulating cover 4 is connected to the switchgear cabinet wall 5 through insulating bolts. The first metal cover 20 is connected to the switchgear cabinet wall 5 through metal bolts. The second metal cover 24 is connected to the switchgear cabinet wall 5 through metal bolts; the first coaxial cable connector 6 is connected to the first metal cover 20 through metal bolts. The second coaxial cable connector 21 is connected to the first metal cover 20 through insulating bolts. The third coaxial cable connector 23 is connected to the first metal cover 20 through metal bolts. The optical fiber connector 30 is connected to the first metal cover 20 through metal bolts.

[0055] One end of the cable core wire of the first coaxial cable 11 is connected to the second metal patch 3, and the shielding layer of the first coaxial cable 11 is connected to the first metal patch 2.

[0056] The insulating plate 1 is bonded to the first metal patch 2 and the second metal patch 3 respectively. The insulating sheet 16 is bonded to the transient earth voltage metal patch 17. One insulating sheet 16 is bonded to the switchgear cabinet wall 5. The insulating plate 1 is bonded to the switchgear cabinet wall 5. The first metal patch 2, the second metal patch 3 and the two transient earth voltage metal patches 17 are all copper patches.

[0057] The cabinet wall 5 of the high-voltage switchgear is grounded through the grounding resistance 9 of the switchgear grounding wire. A power supply 10 is arranged inside the high-voltage switchgear. The electromagnetic-ultrasonic composite sensor is connected to the signal acquisition device 15. One end of the first coaxial cable 11 is connected to the first coaxial cable joint 6 through the joint 8 with a coaxial cable. The joint 8 with a coaxial cable is threadedly connected to the first coaxial cable joint 6. One end of the second coaxial cable 12 is connected to the second coaxial cable joint 21 through the joint 8 with a coaxial cable. The joint 8 with a coaxial cable is threadedly connected to the second coaxial cable joint 21. One end of the third coaxial cable 19 is connected to the third coaxial cable joint 23 through the joint 8 with a coaxial cable. The joint 8 with a coaxial cable is threadedly connected to the third coaxial cable joint 23.

[0058] For the above complementary dipole double-patch antenna, its operating characteristics are determined by the length l, width w, thickness h, gap spacing b of the first metal patch 2 and the second metal patch 3, and the thickness k of the insulating board 1. Since a gap is left between the first metal patch 2 and the second metal patch 3 for symmetric arrangement, according to the dipole theory, the gap impedance (i.e., the UHF sensor impedance) is proportional to the dipole admittance. Then, knowing the performance of the dipole, the performance of its complementary gap can be predicted, making the structure of the dipole and the gap complementary.

[0059] The copper patch and the insulating board 1 of the complementary dipole double-patch antenna can be formed by placing a conductive copper thin sheet on the surface of the dielectric substrate of the bottom lining ground plate, where the bottom lining ground plate is in metallic conduction contact with the cabinet wall 5 of the high-voltage switchgear; or the conductive copper thin sheet can be pasted on the insulating board 1 such as polyethylene for arrangement.

[0060] For the above transient earth voltage probe, its working principle is as Figure 4 shown. The insulating sheet 16 arranged between the transient earth voltage metal patch 17 on the inner side and the switchgear cabinet wall forms a capacitance Cc1. The capacitance Cc2 formed by arranging the insulating sheet 16 between the two transient earth voltage metal patches 17, together with the series capacitors, forms a capacitive voltage-dividing electromagnetic wave coupling transient earth voltage probe. An inductor 18 is connected in series between the shielding layer (grounded) of the second coaxial cable 12 and the switchgear cabinet wall to block high-frequency electromagnetic waves from entering the acquisition device from the grounding side.

[0061] For the above optical probe, its composition and structural principle are as Figure 5 shown. 8 fluorescent optical fibers 26 are arranged in a symmetric circular ring shape on the organic glass plate 31, connected by 8 optical fiber connectors 27 and then sent into an 8×1 coupler 28 through a single-mode optical fiber 32 to form an enhanced optical probe, which is connected to the optical fiber joint 30 through the single-mode optical fiber 32.

[0062] Figure 6 Shown is the installation method of the integrated acoustic-optic-electromagnetic composite sensor on the cabinet wall of the high-voltage switchgear, which mainly includes 9 steps, specifically as follows (replacement or removal can also refer to):

[0063] Step 1, the cable core wire and the shielding layer (grounded) of the first coaxial cable 11 are respectively welded with good conductivity to the feeding points 7 of the second metal patch 3 and the first metal patch 2;

[0064] Step 2, the first metal patch 2 and the second metal patch 3 are symmetrically and firmly pasted on one side of the insulating board 1;

[0065] Step 3, the other side of the insulating board 1 is firmly pasted on the inner wall of the switchgear cabinet wall 5, and the second through hole 14, the gap and the first through hole 13 are coaxial;

[0066] Step 4, an insulating cover 4 with a suitable size seals and reliably connects the components formed in Step 3 by using 4 insulating bolts, realizing the installation of the complementary dipole double-patch antenna and the switchgear cabinet wall 5;

[0067] Step 5, multiple fluorescent optical fibers 26 are connected to the coupler 28 in the center of the ring through corresponding multiple connectors 27, and the single-mode optical fiber 32 sequentially passes through the third through hole 29, the gap, the first through hole 13 and the second through hole 14 of the insulating cover 4 and is conductively connected to the optical fiber connector 30 conductively connected to the first metal cover 20;

[0068] Step 6, two insulating sheets 16 and two transient earth voltage metal patches 17 are alternately stacked and bonded, and one side of one insulating sheet 16 is firmly pasted on the outer wall of the switchgear cabinet wall 5;

[0069] Step 7, the cable core wire and the shielding layer (grounded) of the second coaxial cable 12 are respectively welded with good conductivity to the two transient earth voltage metal patches 17. The cable core wire is welded to the outer transient earth voltage metal patch 17, and the shielding layer is welded to the inner transient earth voltage metal patch 17 and the working side of the inductor 18;

[0070] Step 8, the PZT sensor 25 is closely attached to the switchgear cabinet wall, and vaseline is applied at the attachment to enhance the ultrasonic signal coupling, and 4 metal bolts are used to connect the second metal cover 24 to the switchgear cabinet wall 5 to realize the reliable installation of the PZT sensor 25;

[0071] Step 9, after the grounding side of the inductor 18 is conductively welded to the first metal cover 20; then, after the second coaxial cable connector 21 is threadedly connected to the connector 8 with a coaxial cable, 4 insulating bolts and insulating washers 22 are used to reliably install the coaxial cable connector and the metal cover in an insulating manner, completing the fixed installation of the electromagnetic wave signal output interface of the transient earth voltage probe; after the first coaxial cable connector 6 is threadedly connected to the connector 8 with a coaxial cable, 4 metal bolts are used to reliably install the first coaxial cable connector 6 and the first metal cover 20 in a conductive manner, completing the fixed installation of the UHF electromagnetic wave signal output interface of the complementary dipole double patch antenna; the fiber optic connector 30 is threadedly connected to the first metal cover 20, completing the fixed installation of the optical pulse signal output interface of the enhanced optical probe composed of the fluorescent optical fiber 26; after the third coaxial cable connector 23 is threadedly connected to the connector 8 with a coaxial cable, 4 metal bolts are used to reliably install the third coaxial cable connector 23 and the first metal cover 20 in a conductive manner, completing the fixed installation of the ultrasonic signal output interface of the ultrasonic probe based on the PZT sensor 25; then, the first metal cover 20 is reliably installed on the outer wall of the high-voltage switchgear cabinet wall 5 using 4 metal bolts.

[0072] Figure 7 It is the output time-domain waveform diagram of the integrated acousto-optic electromagnetic composite sensor on the high-voltage switchgear cabinet wall. The measured dimensional parameters of the complementary dipole double patch antenna after processing are as follows: the lengths of the first metal patch 2 and the second metal patch 3 are 5 cm, the widths are 10 cm, the thicknesses are 5 mm, the gap spacing is 1 cm, and the thickness of the insulating board 1 (polyethylene) is 1 cm; the measured dimensional parameters of the capacitive electromagnetic wave coupling transient earth voltage probe after processing are as follows: the lengths of the two transient earth voltage metal patches 17 are 5 cm, the widths are 5 cm, the thicknesses are 2 mm, the two insulating sheets 16 are made of insulating wood (phenolic plastic), and the lengths are 5 cm, the widths are 5 cm, and the thicknesses are 2 mm; the inductance 18 L = 1100 nh; the main parameters of the selected PZT sensor 25 are: the resonant frequency is 150 kHz, and the peak sensitivity in the frequency band of 30 kHz to 200 kHz is 75 dB; the fluorescent optical fiber 26 uses the fluorescent optical fiber 26 doped with Rhodamine 6G, the working frequency band is 500 nm - 1000 nm, and the single length of the fluorescent optical fiber 26 is 8 cm.

Claims

1. An integrated acoustic-optic electromagnetic composite sensor for the wall of a high-voltage cabinet, characterized in that, It includes a complementary dipole double-patch antenna, a transient earth voltage probe, an ultrasonic probe, and an optical probe. The complementary dipole double-patch antenna includes an insulating cover (4), an insulating board (1), and a metal patch assembly. The metal patch assembly includes the same first metal patch (2) and second metal patch (3). One side of the insulating board (1) is connected to the inner wall of the switchgear cabinet wall (5), and the other side symmetrically connects the first metal patch (2) and the second metal patch (3). The insulating board (1), the first metal patch (2), and the second metal patch (3) are placed in the first cavity formed by the insulating cover (4) and the inner wall of the switchgear cabinet wall (5). A gap is formed between the first metal patch (2) and the second metal patch (3). The insulating board (1) is provided with a first through hole (13), and the switchgear cabinet wall (5) is provided with a second through hole (14). The gap, the first through hole (13), and the second through hole (14) are coaxial. One end of the first coaxial cable (11) is conductively connected to the first metal patch (2) and the second metal patch (3) respectively, and the other end is conductively connected to the first coaxial cable connector (6) through the gap, the first through hole (13), and the second through hole (14) in sequence. The transient earth voltage probe includes two insulating sheets (16) and two transient earth voltage metal patches (17). The insulating sheets (16) and the transient earth voltage metal patches (17) are arranged alternately and connected to each other. One of the insulating sheets (16) is connected to the switchgear cabinet wall (5). One end of the cable core wire of the second coaxial cable (12) is conductively connected to the outer transient earth voltage metal patch (17), and the other end is conductively connected to the second coaxial cable connector (21). The shielding layer of the second coaxial cable (12) is conductively connected to the inner transient earth voltage metal patch (17) and the working side of the inductor (18). The ultrasonic probe includes a second metal cover (24) and a PZT sensor (25) connected to the outer wall of the switchgear cabinet wall (5). The PZT sensor (25) is located in the third cavity formed by the conductive connection between the second metal cover (24) and the outer wall of the switchgear cabinet wall (5). The PZT sensor (25) is conductively connected to the third coaxial cable connector (23). The transient earth voltage probe and the ultrasonic probe are located in the second cavity formed by the first metal cover (20) and the outer wall of the switchgear cabinet wall (5). The second through hole (14) is within the coverage of the first metal cover (20). The first coaxial cable connector (6) and the third coaxial cable connector (23) are conductively connected to the first metal cover (20). The second coaxial cable connector (21) is insulated from the first metal cover (20). The grounding side of the inductor (18) is conductively connected to the first metal cover (20). The optical probe includes a plurality of fluorescent optical fibers (26) symmetrically distributed in a ring outside the insulating cover (4). The plurality of fluorescent optical fibers (26) are connected to a coupler (28) in the center of the ring through a corresponding plurality of connectors (27).The single-mode optical fiber (32) sequentially passes through the third through-hole (29), the gap, the first through-hole (13) and the second through-hole (14) of the insulating cover (4) to conductively connect to the optical fiber connector (30) that is conductively connected to the first metal cover (20), and the optical fiber connector (30) is conductively connected to the first metal cover (20); The optical probe includes 8 fluorescent optical fibers (26) symmetrically distributed in a circular ring outside the insulating cover (4), and the 8 fluorescent optical fibers (26) are connected to a coupler (28) in the center of the circular ring through corresponding 8 connectors (27); A plurality of fluorescent optical fibers (26) are symmetrically distributed in a circular ring on a plexiglass plate (31), the plexiglass plate (31) is fixedly connected to the insulating cover (4), the insulating plate (1) is a polyethylene insulating plate, and the insulating sheet (16) is a phenolic plastic insulating sheet.

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