Three-post insulator micro-defect detection device in temperature and pressure stress field and identification method of three-post insulator micro-defect detection device

Abstract

The invention belongs to the technical field of three-post insulator detection, and particularly relates to a three-post insulator microdefect detection device under a temperature and pressure stress field and an identification method thereof, and the three-post insulator microdefect detection device comprises a three-post insulator, an ultrasonic detection unit and a detection unit; wherein the three-post insulator is embedded in the gas-insulated metal-enclosed power transmission line, the ultrasonic detection unit comprises an ultrasonic transmitting probe and an ultrasonic receiving probe, and the detection unit comprises a temperature detection unit and a pressure detection unit on the inner side of the grounding shell; insulating gas with preset pressure intensity is filled in the gas insulated metal-enclosed power transmission line, a high-voltage guide rod in the gas insulated metal-enclosed power transmission line is heated and stretched based on high-voltage direct current, and an ultrasonic guided wave signal with three-post insulator state information is obtained based on an ultrasonic detection unit. The pressure and the temperature obtained by the detection unit are obtained in real time, whether the three-post insulator has micro-defects or not is judged by considering a temperature, pressure and stress scene, and detection of the micro-defects of the three-post insulator in the temperature and pressure stress field is completed.

Description

Technical Field

[0001] The invention belongs to the technical field of three-pillar insulator detection, and in particular relates to a three-pillar insulator micro-defect detection device under a temperature-compression stress field and an identification method thereof. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] Gas-insulated Metal-enclosed Transmission Line (GIL) is an advanced transmission method with insulating gas as the medium and coaxial arrangement of conductor and casing. It has the advantages of large transmission capacity, low energy consumption and long service life. It can effectively meet the needs of rapid development of new energy, overcome the bottlenecks of ultra-high voltage transmission in capacity, reliability and environmental protection, and provide strong support for the development and efficient allocation of clean energy.

[0004] GIL includes conductor, aluminum alloy shell, insulator and insulating gas, etc. According to the number of insulating pillars, insulators can be divided into single-pillar, double-pillar and three-pillar types; among them, three-pillar insulators have significant advantages due to their convenient installation, superior support performance and ability to provide thermal expansion and mechanical strain compensation.

[0005] However, insulators face problems such as interface charge accumulation, interference from metallic foreign matter, and multi-physical field coupling effects in practical applications; three-pillar insulators in particular may develop surface or internal cracks and defects during transportation, installation, and operation, which seriously affect their insulation performance.

[0006] At present, there are two main problems in insulator stress detection:

[0007] On the one hand, common stress detection methods have their own limitations. Lossful stress detection methods such as blind hole method and splitting method are not suitable for in-service equipment and parts, special or expensive materials due to their destructiveness. The most popular non-destructive stress detection method is X-ray diffraction, but it has high requirements for materials (isotropic, homogeneous, fine-grained polycrystalline materials), and has the disadvantages of complex operation, many detection restrictions, and long single-point testing time. It can be said that non-destructive stress detection is still a difficult problem.

[0008] On the other hand, no matter which method is used to manufacture the device, it simply tests the insulators at room temperature and without complex stress, and rarely considers the stress of the insulators under the integrated temperature-pressure coupling field. In fact, during the operation of GIS equipment, changes in temperature and pressure have a great impact on the stress distribution of insulators. Summary of the invention

[0009] To solve the above problems, the present invention proposes a three-pillar insulator micro-defect detection device under a thermal-compressive stress field and an identification method thereof, which are used for the precise detection of micro-nano defects of three-pillar insulators under the action of a thermal-compressive stress field.

[0010] According to some embodiments, a first solution of the present invention provides a three-pillar insulator micro-defect detection device under a temperature-compression stress field, which adopts the following technical solution:

[0011] A three-pillar insulator micro-defect detection device under a temperature and pressure stress field comprises a three-pillar insulator and an ultrasonic detection unit and a detection unit connected to the three-pillar insulator; wherein the three-pillar insulator is embedded in a gas-insulated metal-enclosed transmission line, the ultrasonic detection unit comprises an ultrasonic transmitting probe and an ultrasonic receiving probe arranged on the surface of the three-pillar insulator, and the detection unit comprises a temperature detection unit arranged at the embedding tube of the three-pillar insulator and a pressure detection unit arranged on the inner side of a grounding shell of the gas-insulated metal-enclosed transmission line; an insulating gas with a preset pressure is filled in the gas-insulated metal-enclosed transmission line, a high-voltage guide rod in the gas-insulated metal-enclosed transmission line is heated and expanded based on high-voltage direct current, an ultrasonic guided wave signal with state information of the three-pillar insulator is obtained based on the ultrasonic detection unit, the pressure and temperature obtained by the detection unit are obtained in real time, and whether the three-pillar insulator has micro-defects is judged in consideration of the temperature and pressure stress scene, so as to complete the detection of micro-defects of the three-pillar insulator under the temperature and pressure stress field.

[0012] As a further technical limitation, the ultrasonic transmitting probe and the ultrasonic receiving probe may adopt a dual-crystal probe or a single-crystal probe to transmit pulse waves or penetrating waves. The single-crystal probe is one-transmit-one-receive, while the dual-crystal probe is one-transmit-one-receive.

[0013] As a further technical limitation, the three-pillar insulator micro-defect detection device under the thermal and compressive stress field also includes a data acquisition system connected to the ultrasonic detection unit, and the data acquisition system is used to process the received ultrasonic guided wave signals under different temperature and pressure conditions, obtain the changes in the ultrasonic guided wave signals when micro-defects exist, and realize micro-defect monitoring of the three-pillar insulator.

[0014] Furthermore, the temperature detection unit is electrically connected to the data acquisition system, and the temperature detection unit includes at least two temperature sensors for real-time monitoring of the surface temperature of the three-pillar insulator.

[0015] Furthermore, the pressure detection unit is electrically connected to the data acquisition system, and the pressure detection unit is used to monitor the mechanical stress of the gas-insulated metal-enclosed transmission line.

[0016] Furthermore, the data acquisition system is used to receive and analyze the ultrasonic waveform of the ultrasonic detection unit, and obtain the real-time temperature and mechanical stress of the insulator during operation through the temperature detection unit and the pressure detection unit.

[0017] As a further technical limitation, the gas-insulated metal-enclosed transmission line for transmitting high-voltage AC / DC voltage includes three-pillar insulators, high-voltage conductors and a grounding shell; the three-pillar insulators are used to support the grounding shell, are cast by epoxy resin / alumina composite material, and are fixed on the high-voltage conductors.

[0018] According to some embodiments, the second solution of the present invention provides an identification method of a three-pillar insulator micro-defect detection device under a temperature-compression stress field, using the three-pillar insulator micro-defect detection device under a temperature-compression stress field provided by the first solution, and adopting the following technical solutions:

[0019] A method for identifying a micro-defect detection device for a three-pillar insulator under a temperature-compression stress field, comprising:

[0020] Filling a gas-insulated metal-enclosed transmission line with insulating gas of a preset pressure;

[0021] Based on the fact that high-voltage direct current causes the high-voltage conductors in the gas-insulated metal-enclosed transmission line to heat up and expand, an ultrasonic guided wave signal with status information of the three-pillar insulators is obtained based on an ultrasonic detection unit, and the pressure and temperature obtained by the detection unit are obtained in real time;

[0022] Based on the data acquisition system and the acquired ultrasonic guided wave signals, pressure and temperature, it is determined whether there are micro defects in the three-pillar insulator, and the detection of micro defects in the three-pillar insulator under the thermal-compressive stress field is completed.

[0023] As a further technical limitation, the data acquisition system calculates the defect position of the insulator using the amplitude change rate of the ultrasonic guided wave echo signal under different temperatures and mechanical stresses as a characteristic quantity, that is:

[0024]

[0025] Wherein, d represents the distance between the ultrasonic source and the defect; n represents the number of sampling points; c represents the ultrasonic wave velocity; and f represents the sampling frequency of the ultrasonic detection unit.

[0026] As a further technical limitation, the ultrasonic transmitting probe excites an ultrasonic guided wave signal in the three-pillar insulator, and the ultrasonic receiving probe is used to receive the ultrasonic guided wave signal.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The present invention fills the gas-insulated metal-enclosed transmission line with insulating gas of a specified pressure, uses a high-voltage DC source to pass a DC voltage into the high-voltage guide rod, causes the guide rod to heat and expand, generates an ultrasonic waveguide signal by using an ultrasonic detection unit, applies the ultrasonic waveguide to the three-pillar insulator via an ultrasonic transmitting probe, and sends the ultrasonic waveguide signal with insulator status information to a data acquisition system via an ultrasonic receiving probe via an ultrasonic detection unit; based on the amplitude change rate of the ultrasonic waveguide echo signal, and using this as a characteristic quantity, and taking the ultrasonic waveguide detection signal of the intact three-pillar insulator as a reference, it is determined whether the insulator to be detected has micro defects, and further calculates the specific location of the micro defects. The detection method takes into account the influence of the temperature and pressure stress field on the three-pillar insulator, improves the sensitivity of ultrasonic waveguide detection of mechanical stress, and has a strong engineering application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The drawings in the specification that constitute a part of this embodiment are used to provide a further understanding of this embodiment. The schematic embodiments of this embodiment and their descriptions are used to explain this embodiment and do not constitute improper limitations on this embodiment.

[0030] Figure 1 It is a structural schematic diagram of a three-pillar insulator micro-defect detection device under a temperature-compression stress field in the first embodiment of the present invention;

[0031] Figure 2 It is a flow chart of the identification method of the three-pillar insulator micro-defect detection device under the temperature and pressure stress field in the second embodiment of the present invention;

[0032] Among them, 1. Ultrasonic detection unit; 2. Data acquisition system; 3. Pressure detection unit; 4. Temperature detection unit; 5. Three-pillar insulator; 6. High-voltage guide rod; 7. Grounding shell; 8. High-voltage DC source; 9. Ultrasonic transmitting probe; 10. Ultrasonic receiving probe; 11. Gas-insulated metal-enclosed transmission line. DETAILED DESCRIPTION

[0033] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0034] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0035] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0036] In the present invention, terms such as "upper", "lower", "left", "right", "front", "back", "vertical", "horizontal", "side", "bottom", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. They are relational words determined only for the convenience of describing the structural relationships of the various parts or elements of the present invention, and do not specifically refer to any part or element in the present invention and should not be understood as limitations on the present invention.

[0037] In the present invention, terms such as "fixed connection", "connected", "connection", etc. should be understood in a broad sense, indicating that it can be fixedly connected, integrally connected or detachably connected; it can be directly connected or indirectly connected through an intermediate medium. For relevant scientific research or technical personnel in this field, the specific meanings of the above terms in the present invention can be determined according to specific circumstances, and they cannot be understood as limitations on the present invention.

[0038] In the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0039] Embodiment 1

[0040] Embodiment 1 of the present invention introduces a device for detecting micro-defects of three-pillar insulators under a temperature-compression stress field.

[0041] like Figure 1 The device shown is a three-pillar insulator micro-defect detection device under a temperature-pressure stress field, comprising an ultrasonic detection unit 1, a data acquisition system 2, a pressure detection unit 3, a temperature detection unit 4, a three-pillar insulator 5, a high-voltage guide rod 6, a grounding shell 7, a high-voltage direct current source 8, an ultrasonic transmitting probe 9, an ultrasonic receiving probe 10 and a gas-insulated metal-enclosed transmission line 11.

[0042] This embodiment uses an ultrasonic guided wave defect detection device to collect normal signals and defect signals of the three-pillar insulator 5; wherein the ultrasonic detection unit 1 includes an ultrasonic transmitting probe 9 and an ultrasonic receiving probe 10 arranged on the surface of the three-pillar insulator 5, and a dual crystal probe or a single crystal probe can be used to emit pulse waves or penetrating waves.

[0043] The data acquisition system 2 in this embodiment is connected to the ultrasonic detection unit 1, and is used to perform noise reduction and other processing on the received ultrasonic guided wave signals under different temperature and pressure conditions, so as to obtain the change of the ultrasonic guided wave signals when micro-defects exist, thereby realizing micro-defect detection of insulators.

[0044] The ultrasonic transmitting probe 9 and the ultrasonic receiving probe 10 in this embodiment are connected to the ultrasonic detection unit 1 through wires and are arranged on both sides of the legs of the three-pillar insulator 5 .

[0045] The temperature detection unit 4 in this embodiment is arranged at the embedding part of the three-pillar insulator 5, connected to the data acquisition system 2 through a wire, and includes more than two temperature sensors for monitoring the surface temperature of the insulator.

[0046] The pressure detection unit 3 in this embodiment is disposed inside the grounded casing 7 in the gas-insulated metal-enclosed transmission line, and is connected to the data acquisition system 2 via a wire, so as to monitor the mechanical stress borne by the gas-insulated metal-enclosed transmission line 11 .

[0047] The gas-insulated metal-enclosed transmission line 11 in this embodiment is used to transmit high-voltage AC / DC voltage. The gas-insulated metal-enclosed transmission line 11 includes three-pillar insulators 5, high-voltage conducting rods 6, and a grounding shell 7.

[0048] It should be noted that the three-pillar insulator 5 in this embodiment is cast from epoxy resin / alumina composite material and is fixed on the high-voltage guide rod 6 to play the role of supporting the shell and insulation.

[0049] The high voltage DC source 8 in this embodiment is used to provide a DC voltage to the gas-insulated metal enclosed power transmission line 11 .

[0050] As one or more implementation modes, the ultrasonic transmitting probe 9 and the receiving probe 10 arranged on the surface of the three-pillar insulator 5 are connected to the ultrasonic detection unit 1 through wires. The ultrasonic probe can adopt a dual crystal probe or a single crystal probe to emit pulse waves or penetrating waves. The single crystal probe is one-transmit-one-receive, and the dual crystal probe is single-transmit-single-receive.

[0051] In this embodiment, the ultrasonic detection unit 1 can emit ultrasonic pulse signals or transmission signals, and is connected to the data acquisition system 2, and can output ultrasonic detection waveforms in the system; the data acquisition system 2 can receive the ultrasonic waveform output by the ultrasonic detection unit 1 and perform data analysis, and obtain the real-time temperature and mechanical stress of the insulator through the temperature detection unit 4 and the pressure detection unit 3; the temperature detection unit 4 is arranged at the three-pillar insulator embedding tube, and can realize real-time monitoring when the temperature of the insulator rises due to the pressure of the conductor; the pressure detection unit 3 is arranged on the inner side of the grounded shell 7, and can monitor the mechanical stress of the gas-insulated metal-enclosed transmission line 11 in real time; the gas-insulated metal-enclosed transmission line 11 is used to simulate the operating conditions of the insulator in the real GIL pipeline, and can apply 252kV AC and DC voltages and can withstand 0.5Mpa atmospheric pressure.

[0052] In this embodiment, a DC voltage is passed through a high-voltage direct current source in a high-voltage conductor, the temperature of the three-pillar insulator is measured by a temperature detection unit, the mechanical stress borne by the gas-insulated metal-enclosed transmission line is measured by a pressure detection unit and sent to a data acquisition system; an ultrasonic transmitting probe generates an ultrasonic guided wave signal, and an ultrasonic receiving probe receives the ultrasonic guided wave signal; an ultrasonic detection device collects the ultrasonic guided wave signal generated by the insulator and sends it to the data acquisition system; the ultrasonic guided wave signal under temperature and pressure is processed by the data acquisition system to obtain the corresponding ultrasonic signal when micro-defects exist, thereby realizing defect detection of the insulator.

[0053] In this embodiment, insulating gas of a specified pressure is filled into the gas-insulated metal-enclosed transmission line, and a high-voltage DC source is used to pass a DC voltage to the high-voltage guide rod to make the guide rod heat up and expand and contract. An ultrasonic detection unit is used to generate an ultrasonic guided wave signal, and the ultrasonic transmitting probe acts on the three-pillar insulator. The ultrasonic receiving probe sends the ultrasonic guided wave signal with the insulator status information to the data acquisition system through the ultrasonic detection unit; based on the amplitude change rate of the ultrasonic guided wave echo signal, and using this as a characteristic quantity, and taking the ultrasonic guided wave detection signal of the intact three-pillar insulator as a reference, it is judged whether the insulator to be detected has micro defects, and the specific location of the micro defects is further calculated. This detection method takes into account the influence of the temperature and pressure stress field on the three-pillar insulator, improves the sensitivity of ultrasonic guided waves in detecting mechanical stress, and has a strong engineering application value.

[0054] Embodiment 2

[0055] Embodiment 2 of the present invention introduces a method for identifying a micro-defect detection device for three-pillar insulators under a temperature-compression stress field.

[0056] like Figure 2 The identification method of the three-pillar insulator micro-defect detection device under the temperature and pressure stress field comprises:

[0057] Filling a gas-insulated metal-enclosed transmission line with insulating gas of a preset pressure;

[0058] Based on the fact that high-voltage direct current causes the high-voltage conductors in the gas-insulated metal-enclosed transmission line to heat up and expand, an ultrasonic guided wave signal with status information of the three-pillar insulators is obtained based on an ultrasonic detection unit, and the pressure and temperature obtained by the detection unit are obtained in real time;

[0059] Based on the data acquisition system and the acquired ultrasonic guided wave signals, pressure and temperature, it is determined whether there are micro defects in the three-pillar insulator, and the detection of micro defects in the three-pillar insulator under the thermal-compressive stress field is completed.

[0060] In this embodiment, SF6 gas is used as the insulating gas; a DC voltage is passed through the high-voltage conductor through a high-voltage DC source, the temperature of the three-pillar insulator is measured by a temperature detection unit, and the pressure detection unit measures the mechanical stress borne by the gas-insulated metal-enclosed transmission line and sends it to a data acquisition system; an ultrasonic transmitting probe generates an ultrasonic guided wave signal, and an ultrasonic receiving probe receives the ultrasonic guided wave signal; an ultrasonic detection device collects the ultrasonic guided wave signal generated by the insulator and sends it to the data acquisition system; the ultrasonic guided wave signal under temperature and pressure is processed by the data acquisition system to obtain the corresponding ultrasonic signal when micro-defects exist, thereby realizing defect detection of the insulator.

[0061] As one or more implementation modes, the data acquisition system calculates the defect position of the insulator using the amplitude change rate of the ultrasonic guided wave echo signal under different temperatures and mechanical stresses as a characteristic quantity, that is:

[0062]

[0063] Wherein, d represents the distance between the ultrasonic source and the defect; n represents the number of sampling points; c represents the ultrasonic wave velocity; and f represents the sampling frequency of the ultrasonic detection unit.

[0064] As one or more implementation modes, the ultrasonic transmitting probe excites the ultrasonic guided wave signal in the three-pillar insulator, and the ultrasonic receiving probe is used to receive the ultrasonic guided wave signal.

[0065] This embodiment builds a three-pillar insulator micro-defect detection device under a temperature and pressure stress field, and identifies micro-defects through the built detection device. Specifically:

[0066] (1) Build the experimental device framework to ensure that all components are firmly connected. A three-pillar insulator model is established in the COMSOL simulation software to perform temperature and pressure stress field simulation calculations, focusing on analyzing the field distribution on the insulator surface under the action of temperature and mechanical stress, providing a theoretical basis for subsequent experiments. Parameters should be adjusted in the simulation to ensure consistency with the actual test environment, such as simulating gas composition, pressure, and temperature conditions.

[0067] (2) Before the test begins, use anhydrous ethanol to thoroughly clean the surface of the three-pillar insulator to remove dust and contaminants that may affect the measurement. After cleaning, place the insulator in a drying oven at 70°C for 12 hours to minimize the interference of humidity on the experimental results. After drying, slowly cool the insulator to room temperature to avoid changes in surface stress caused by excessive temperature differences.

[0068] (3) Install the three-pillar insulator inside the gas-insulated metal-enclosed transmission line to ensure that it is accurately positioned and firmly fixed. Then, seal the test chamber, evacuate it to remove impurities in the air, and then slowly fill it with SF6 insulating gas of a specified concentration to a specified pressure value. Test the sealing performance of the chamber to ensure that there is no gas leakage. Start the DC high-voltage power supply and apply a gradually increasing DC voltage to the high-voltage guide rod. At the same time, monitor the temperature distribution on the surface of the insulator in real time through the temperature detection unit. Start the stress loading device and gradually load the mechanical stress according to the set stress value. Monitor the stress changes in real time through the pressure detection unit to simulate the crack generation process to ensure that the experimental conditions are consistent with the simulation results.

[0069] (4) After the experiment begins, start the ultrasonic detection device and select the probe type that suits the detection needs. If a dual-crystal probe is used, the pulse reflection method is used to detect the crack area on the surface of the insulator; if a single-crystal probe is used, the internal structural defect information is obtained through the ultrasonic penetration method. During the detection process, in order to improve the efficiency of sound wave propagation, evenly apply coupling gel to the detection surface to ensure that there is no gap between the probe and the insulator surface. According to different detection positions and directions, data is collected point by point to ensure that the positioning results of cracks and defects have sufficient accuracy and repeatability. Finally, the measurement results are compared with the simulation data to analyze the crack expansion law and defect characteristics.

[0070] (5) Control variables and repeat the experiment.

[0071] In this embodiment, insulating gas of a specified pressure is filled into the gas-insulated metal-enclosed transmission line, and a high-voltage DC source is used to pass a DC voltage to the high-voltage guide rod to make the guide rod heat up and expand and contract. An ultrasonic detection unit is used to generate an ultrasonic guided wave signal, and the ultrasonic transmitting probe acts on the three-pillar insulator. The ultrasonic receiving probe sends the ultrasonic guided wave signal with the insulator status information to the data acquisition system through the ultrasonic detection unit; based on the amplitude change rate of the ultrasonic guided wave echo signal, and using this as a characteristic quantity, and taking the ultrasonic guided wave detection signal of the intact three-pillar insulator as a reference, it is judged whether the insulator to be detected has micro defects, and the specific location of the micro defects is further calculated. This detection method takes into account the influence of the temperature and pressure stress field on the three-pillar insulator, improves the sensitivity of ultrasonic guided waves in detecting mechanical stress, and has a strong engineering application value.

[0072] The detailed steps are the same as the working principle of the three-pillar insulator micro-defect detection device under the temperature and pressure stress field provided in Example 1, and will not be repeated here.

[0073] The above description is only a preferred embodiment of the present embodiment and is not intended to limit the present embodiment. For those skilled in the art, the present embodiment may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present embodiment shall be included in the protection scope of the present embodiment.

Claims

1. A three-pillar insulator micro-defect detection device under a temperature and pressure stress field, characterized in that: The invention comprises a three-pillar insulator and an ultrasonic detection unit and a detection unit connected to the three-pillar insulator; wherein the three-pillar insulator is embedded in a gas-insulated metal-enclosed transmission line, the ultrasonic detection unit comprises an ultrasonic transmitting probe and an ultrasonic receiving probe arranged on the surface of the three-pillar insulator, and the detection unit comprises a temperature detection unit arranged at the embedding tube of the three-pillar insulator and a pressure detection unit arranged on the inner side of the grounding shell of the gas-insulated metal-enclosed transmission line; an insulating gas with a preset pressure is filled in the gas-insulated metal-enclosed transmission line, a high-voltage guide rod in the gas-insulated metal-enclosed transmission line is heated and expanded based on high-voltage direct current, an ultrasonic guided wave signal with status information of the three-pillar insulator is obtained based on the ultrasonic detection unit, the pressure and temperature obtained by the detection unit are obtained in real time, and whether there are micro defects in the three-pillar insulator is judged in consideration of the temperature-pressure stress scene, so as to complete the detection of micro defects of the three-pillar insulator under the temperature-pressure stress field.

2. A three-pillar insulator micro-defect detection device under a temperature and pressure stress field as described in claim 1, characterized in that: The ultrasonic transmitting probe and the ultrasonic receiving probe may adopt a dual-crystal probe or a single-crystal probe to transmit pulse waves or penetrating waves. The single-crystal probe has one transmission and one reception, while the dual-crystal probe has one transmission and one reception.

3. A three-pillar insulator micro-defect detection device under a temperature and pressure stress field as described in claim 1, characterized in that: It also includes a data acquisition system for the ultrasonic detection unit, which is used to process the received ultrasonic guided wave signals under different temperature and pressure conditions, obtain the changes in the ultrasonic guided wave signals when micro-defects exist, and realize micro-defect monitoring of three-pillar insulators.

4. A three-pillar insulator micro-defect detection device under a temperature and pressure stress field as described in claim 3, characterized in that: The temperature detection unit is electrically connected to the data acquisition system, and the temperature detection unit includes at least two temperature sensors for real-time monitoring of the surface temperature of the three-pillar insulator.

5. A three-pillar insulator micro-defect detection device under a temperature and pressure stress field as claimed in claim 3, characterized in that: The pressure detection unit is electrically connected to the data acquisition system, and the pressure detection unit is used to monitor the mechanical stress of the gas-insulated metal-enclosed transmission line.

6. A three-pillar insulator micro-defect detection device under a temperature and pressure stress field as claimed in claim 3, characterized in that: The data acquisition system is used to receive and analyze the ultrasonic waveform of the ultrasonic detection unit, and obtain the real-time temperature and mechanical stress of the insulator during operation through the temperature detection unit and the pressure detection unit.

7. A three-pillar insulator micro-defect detection device under a temperature and pressure stress field as claimed in claim 1, characterized in that: The gas-insulated metal-enclosed transmission line for transmitting high-voltage AC / DC voltage includes three-pillar insulators, a high-voltage conductor and a grounding shell; the three-pillar insulator is used to support the grounding shell, is cast by epoxy resin / alumina composite material, and is fixed on the high-voltage conductor.

8. A method for identifying micro-defect detection devices of three-pillar insulators under temperature and pressure stress fields, characterized in that: include: Filling a gas-insulated metal-enclosed transmission line with insulating gas of a preset pressure; Based on the fact that high-voltage direct current causes the high-voltage conductors in the gas-insulated metal-enclosed transmission line to heat up and expand, an ultrasonic guided wave signal with status information of the three-pillar insulators is obtained based on an ultrasonic detection unit, and the pressure and temperature obtained by the detection unit are obtained in real time; Based on the data acquisition system and the acquired ultrasonic guided wave signals, pressure and temperature, it is determined whether there are micro defects in the three-pillar insulator, and the detection of micro defects in the three-pillar insulator under the thermal-compressive stress field is completed.

9. The identification method of the three-pillar insulator micro-defect detection device under the temperature and pressure stress field as claimed in claim 8, characterized in that: The data acquisition system uses the amplitude change rate of the ultrasonic guided wave echo signal under different temperatures and mechanical stresses as a characteristic quantity to calculate the defect position of the insulator, that is: Wherein, d represents the distance between the ultrasonic source and the defect; n represents the number of sampling points; c represents the ultrasonic wave velocity; and f represents the sampling frequency of the ultrasonic detection unit.

10. The identification method of the three-pillar insulator micro-defect detection device under the temperature and pressure stress field as claimed in claim 8, characterized in that: The ultrasonic transmitting probe excites the ultrasonic guided wave signal in the three-pillar insulator, and the ultrasonic receiving probe is used to receive the ultrasonic guided wave signal.

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