Simulation test system and method for development of internal insulation defects of cable terminal

Abstract

The invention discloses a cable terminal internal insulation defect development simulation test system and method, and the system comprises a system voltage control module which is used for applying a processing frequency high voltage to simulate an operation voltage environment; the interface pressure monitoring module is used for applying adjustable pressure and monitoring pressure change in real time; the interface defect detection module is used for simulating an internal insulation defect development process of the cable and collecting defect development image information; and the partial discharge detection module is used for acquiring a partial discharge signal generated in the insulation defect development process. Under the simulated actual working condition, the development process of the insulation defect of the cable terminal can be dynamically reproduced, the influence rule of the interface pressure change on defect evolution is disclosed, the partial discharge characteristic signal in the defect development process is obtained, and support is provided for the research on the insulation degradation mechanism of the vehicle-mounted high-voltage cable terminal and the safe operation of the vehicle-mounted high-voltage cable terminal.

Description

Technical Field

[0001] The present invention relates to the technical field of insulation defect development mechanism and discharge detection, and particularly to a simulation test system and method for the development of internal insulation defects of cable terminals. Background Art

[0002] The on-vehicle high-voltage equipment of the multiple unit plays an important energy transmission function during its operation. Therefore, the operating state of the high-voltage equipment directly affects the operation stability and safety of the high-speed train, and is more related to the operation order of the railway. As a weak link of the high-voltage system and the cable, the insulation state of the high-voltage cable terminal deserves more attention. The insulation state of the internal interface of the cable terminal is an important part of evaluating the insulation performance of the entire cable terminal. The existing test devices cannot simulate the pressure change of the cable internal interface under actual working conditions of the on-vehicle cable terminal, and it is difficult to find out the internal insulation deterioration mechanism and the insulation defect development mechanism of the cable terminal. Therefore, exploring the development characteristics of the internal interface insulation defects of the cable terminal helps to understand the deterioration state of the insulation state of the cable terminal, and has important theoretical significance and engineering value. Summary of the Invention

[0003] In order to solve the problems that the existing test devices cannot simulate the pressure change of the cable internal interface under actual working conditions of the on-vehicle cable terminal, and it is difficult to find out the internal insulation deterioration mechanism and the insulation defect development mechanism of the cable terminal, the present invention provides a simulation test system and method for the development of internal insulation defects of cable terminals to solve the above problems.

[0004] The present application discloses a simulation test system for the development of internal insulation defects of cable terminals, which is characterized by including:

[0005] A system voltage control module for applying power frequency high voltage to simulate the operating voltage environment;

[0006] An interface pressure monitoring module for applying adjustable pressure and real-time monitoring of pressure changes;

[0007] An interface defect detection module for simulating the development process of internal insulation defects of the cable and collecting defect development image information;

[0008] A partial discharge detection module for obtaining the partial discharge signals generated during the development process of insulation defects.

[0009] Preferably, the system voltage control module includes a power supply, the output end of the power supply is connected to the input end of a corona-free transformer, the output end of the corona-free transformer is connected to one end of a protective resistor, and the other end of the protective resistor is connected to the input end of a coupling capacitor.

[0010] Preferably, the interface defect detection module includes a composite insulating material, which includes ethylene propylene diene monomer (EPDM) and low-density polyethylene doped with carbon black arranged opposite to each other up and down. A prefabricated defect area is arranged between the EPDM and the low-density polyethylene doped with carbon black. A high-voltage electrode and a grounding electrode are respectively arranged at both ends of the composite insulating material, and a high-speed camera is arranged above the composite insulating material.

[0011] Preferably, the prefabricated defect area includes air gaps and carbon traces, and the carbon traces are arranged at the bottom of the air gaps.

[0012] Preferably, the interface pressure monitoring module includes a transparent upper acrylic pressing plate and a transparent lower acrylic pressing plate for fixing the composite insulating material. A variable pressure spring assembly, an insulating plate, a variable pressure knob, and an insulating bolt are sequentially arranged from top to bottom below the lower acrylic pressing plate.

[0013] Preferably, the interface pressure monitoring module further includes a pressure sensor and a second workstation. The pressure sensor is embedded between the EPDM and the low-density polyethylene doped with carbon black, and the second workstation is connected to the pressure sensor.

[0014] Preferably, the prefabricated defect area extends in a strip shape from the grounding electrode end to the high-voltage electrode end inside the composite insulating material. There are a total of four pressure sensors, which are distributed at the four corners inside the composite insulating material.

[0015] Preferably, the partial discharge detection module includes a CT coil, a first workstation, a partial discharge detector, an HFCT coil, and an oscilloscope. The input end of the CT coil is connected to the output end of the high-voltage electrode. The output end of the CT coil is respectively connected to the input end of the coupling capacitor and the input end of the oscilloscope. The input end of the partial discharge detector is connected to the grounding end of the coupling capacitor. The output end of the partial discharge detector is connected to the input end of the first workstation. The input end of the HFCT coil is connected to the output end of the grounding electrode. One output end of the HFCT coil is connected to the oscilloscope, and the other output end is grounded.

[0016] This application also discloses a method for simulating the development of internal insulation defects in cable terminals, which is realized based on the above-mentioned system for simulating the development of internal insulation defects in cable terminals, and includes the following steps:

[0017] S1. Adjust and real-time monitor the pressure of the multi-layer insulation composite interface through the interface pressure monitoring module. The multi-layer insulation composite interface includes the composite insulating material, the pressure sensor and the prefabricated defect area embedded therein;

[0018] S2. Apply power frequency high voltage by using the system voltage control module, trigger partial discharge and maintain the applied voltage higher than the discharge initiation voltage;

[0019] S3. Obtain the image data during the evolution of the multi-layer insulation composite interface defects through the interface defect detection module;

[0020] S4. Obtain the discharge signal data through the partial discharge detection module, and conduct correlation analysis with the multi-layer insulation composite interface defect evolution image obtained in S3.

[0021] Preferably, S4 further includes:

[0022] Adopt the partial discharge signal denoising method of wavelet threshold denoising to denoise the discharge signal, so as to effectively remove the noise signals including corona interference.

[0023] Advantages of the present invention:

[0024] (1) Through the ingenious combination of the interface pressure sensor, acrylic pressing plate and variable pressure knob, the present invention innovatively realizes the real-time regulation and accurate recording of the multi-layer insulation composite interface pressure, breaks through the technical bottleneck of uncontrollable and non-quantifiable interface pressure in traditional tests, and reproduces for the first time the physical scenario of the dynamic change of the interface pressure during the actual operation of the vehicle-mounted cable terminal, providing a key experimental platform and data support for the in-depth study of the correlation between the interface pressure change and the evolution of internal insulation defects in the system.

[0025] (2) By artificially prefabricating typical defects (such as air gaps and carbon marks) in the composite insulation interface composed of ethylene propylene diene monomer rubber and low-density polyethylene doped with carbon black, the present invention effectively simulates the typical insulation weak structures that appear during the operation of the cable terminal; combined with the dynamic observation of the high-speed camera system, it reveals the dynamic process of the evolution of insulation defects from the low-voltage end to the high-voltage end under the action of continuous pressure and high-energy electron bombardment, clearly presents for the first time the path and morphological characteristics of the development of the microscopic structure of the interface defects along the electric field direction, and systematically reveals the deterioration mechanism inside the composite insulation material of the cable terminal.

[0026] (3) By deeply coupling the high-speed camera imaging system and the partial discharge signal acquisition device, the present invention can establish the mapping relationship between the evolution morphology of the composite insulation interface defects and the characteristics of the partial discharge signals, realize the synchronous recording and correlation analysis of the partial discharge behavior and the insulation deterioration process, clearly define for the first time the response law between the partial discharge signal parameters and the defect development stage, and provide theoretical support and technical path for the subsequent real-time identification and condition assessment of the internal defects of the cable terminal based on partial discharge detection. Description of the Drawings

[0027] Figure 1 It is a schematic structural diagram of the simulation test system for the development of internal insulation defects of the cable terminal in the embodiment of the present invention.

[0028] The reference numerals are as follows:

[0029] 1 - Coupling capacitor, 2 - Protection resistor, 3 - Corona - free transformer, 4 - CT coil, 5 - First workstation, 6 - Upper acrylic pressing plate, 7 - Ethylene propylene diene monomer rubber, 8 - Low - density polyethylene doped with carbon black, 9 - Lower acrylic pressing plate, 10 - Transforming spring assembly, 11 - Insulating plate, 12 - Insulating bolt, 13 - Transforming knob, 14 - Pressure sensor, 15 - Prefabricated defect area, 16 - High - voltage electrode, 17 - Grounding electrode, 18 - High - speed camera, 19 - Second workstation, 20 - Oscilloscope, 21 - HFCT coil, 22 - Partial discharge detector, 23 - Power supply. Detailed implementation mode

[0030] To make the objectives, technical solutions and advantages of this application more clear and understandable, the following takes examples with reference to the attached drawings and further elaborates on this application in detail.

[0031] An embodiment of this application discloses a simulation test system for the development of internal insulation defects in cable terminals, including a system voltage control module, an interface pressure monitoring module, an interface defect detection module, and a partial discharge detection module. The system voltage control module is used to apply power frequency high voltage to the multi - layer insulation composite interface to simulate the operating voltage environment. The interface pressure monitoring module is used to apply adjustable pressure to the multi - layer insulation composite interface and monitor the pressure change in real time. The interface defect detection module is used to simulate the development process of internal insulation defects in the cable and collect defect development image information. The partial discharge detection module is used to obtain the partial discharge signals generated during the development process of insulation defects. The specific structure of the simulation test system for the development of internal insulation defects in cable terminals proposed in this embodiment is as Figure 1 shown.

[0032] The system voltage control module includes a coupling capacitor 1, a protection resistor 2, a corona - free transformer 3, and a power supply 23. The output end of the power supply 23 is connected to the input end of the corona - free transformer 3. The output end of the corona - free transformer 3 is connected to one end of the protection resistor 2, and the other end of the protection resistor 2 is connected to the input end of the coupling capacitor 1. The power supply 23 is used to provide a stable power frequency voltage to establish an electric field environment simulating the actual operating conditions of on - vehicle cable terminals. The corona - free transformer 3 is used to raise the power frequency voltage to the target test voltage, and at the same time, avoid external interference caused by corona effects through optimizing the structure to ensure the accuracy of partial discharge signal acquisition. The protection resistor 2 is used to suppress the surge current that may be generated during partial discharge and breakdown processes, prevent damage to the test device and the sample under test, and improve the safety and stability of system operation. The coupling capacitor 1 is used to effectively couple and extract the high - frequency partial discharge signals generated during the development of internal defects in the composite insulation interface on the premise of ensuring that the high - voltage loading conditions are not damaged, providing an accurate signal source for subsequent defect identification and analysis.

[0033] The interface pressure monitoring module includes a transparent upper acrylic pressing plate 6, a transparent lower acrylic pressing plate 9, a variable pressure spring assembly 10, an insulating plate 11, insulating bolts 12, a variable pressure knob 13, a pressure sensor 14, and a second workstation 19. The transparent upper acrylic pressing plate 6 and the transparent lower acrylic pressing plate 9 are used to fix the composite insulating material. The variable pressure spring assembly 10, the insulating plate 11, the variable pressure knob 13, and the insulating bolts 12 are arranged in sequence from top to bottom below the transparent lower acrylic pressing plate 9. The insulating bolts 12 and the variable pressure spring assembly 10 are used to cooperate with the upper and lower acrylic pressing plates to form an adjustable pressure carrier. The variable pressure knob 13 is used to adjust the multi-layer insulating composite interface pressure. The insulating plate 11 is used to support the test bench. The pressure sensor 14 is embedded between the ethylene propylene diene monomer (EPDM) 7 and the low-density polyethylene (LDPE) 8 doped with carbon black, with a total of 4 pieces, distributed at the four corners, and is used to collect the pressure values of the multi-layer insulating composite interface in real time. The second workstation 19 is connected to the pressure sensor 14 and is used to record, display, and analyze the data of the pressure sensor 14. Through the close cooperation among the transparent upper acrylic pressing plate 6, the transparent lower acrylic pressing plate 9, the variable pressure spring assembly 10, the insulating plate 11, the insulating bolts 12, and the variable pressure knob 13, the adjustment of the multi-layer insulating composite material interface pressure is realized, and the pressure sensor 14 and the second workstation 19 are used to realize the real-time measurement of the interface pressure, providing a basic guarantee for the test.

[0034] The interface defect detection module includes a composite insulating material, a prefabricated defect area 15, a high-voltage electrode 16, a grounding electrode 17, and a high-speed camera 18 with a maximum shooting speed of 750000 FPS. The composite insulating material includes an ethylene propylene diene monomer (EPDM) 7 with a size of 700 mm × 350 mm × 10 mm and a low-density polyethylene (LDPE) 8 doped with carbon black with a size of 700 mm × 350 mm × 8 mm, which are arranged opposite to each other up and down. The prefabricated defect area 15 is embedded between the ethylene propylene diene monomer (EPDM) 7 and the low-density polyethylene (LDPE) 8 doped with carbon black, and includes artificially prefabricated air gaps and carbon marks. It is set 2 mm away from the grounding electrode 17, with a size of 100 mm × 2 mm × 2 mm, and extends in a strip shape from one end of the grounding electrode 17 to one end of the high-voltage electrode 18. The carbon marks are set at the bottom of the air gap and are used to simulate potential insulation weak points. The high-voltage electrode 16 and the grounding electrode 17 are respectively arranged at both ends of the composite insulating material and are used to apply a power frequency voltage to the composite insulating material containing the prefabricated defect area 15. The high-speed camera 18 is arranged above the composite insulating material and the transparent upper acrylic pressing plate 6 and is used to record the evolution process of the insulation defect morphology, including the expansion of the air gap, the growth of the carbon marks, and the formation of the electrical tree structure.

[0035] The partial discharge detection module includes a CT coil (current transformer) 4, a first workstation 5, an MPD-600 partial discharge detector 22, an HFCT coil (high-frequency current transformer) 21, and an oscilloscope 20. The input end of the CT coil 4 is connected to the output end of the high-voltage electrode 16, which is used to sense and preliminarily detect the low-frequency pulse signal during the discharge triggering process, providing voltage excitation and discharge synchronization reference for the system. The output end of the CT coil 4 is respectively connected to the input end of the coupling capacitor 1 and the input end of the oscilloscope 20. The grounded end of the coupling capacitor 1 is connected to the input end of the MPD-600 partial discharge detector 22 through a shielded wire to extract and filter the high-frequency partial discharge signal, effectively isolating the power frequency interference. The output end of the partial discharge detector 22 is connected to the input end of the first workstation 5. The input end of the HFCT coil 21 is connected to the output end of the grounding electrode 17. One output end of the HFCT coil 21 is connected to the oscilloscope 20, and the other output end is grounded, which is dedicated to detecting the high-frequency pulse current signal released during the discharge process, with high sensitivity and broadband response characteristics, and can improve the detection ability of weak partial discharge signals. The signal collected at the grounded end of the coupling capacitor 1 is synchronously transmitted to the MPD-600 partial discharge detector 22 for spectrum analysis, phase identification, and pulse counting. At the same time, the signal of the HFCT coil 21 at the system grounding end is connected to the oscilloscope 20 for waveform visualization and time-domain dynamic monitoring, facilitating the feature extraction and classification recognition of different discharge types. Through the collaborative action of the above devices, the discharge signal during the development of the interface defect can be accurately captured, and the mapping relationship between the defect evolution and the discharge response can be established, thus providing key data support and technical guarantee for the analysis of the insulation degradation mechanism and the early fault identification of the on-vehicle cable terminal.

[0036] In the simulation test system for the development of internal insulation defects of the cable terminal disclosed in this embodiment, each component cooperates with each other, realizing the accurate simulation of the development of the multi-layer insulation composite interface defect of the cable terminal and the synchronous recording and correlation analysis of the partial discharge behavior and the insulation degradation process. The system reveals the degradation mechanism inside the composite insulation material of the cable terminal.

[0037] Another embodiment of this application also discloses a method for simulating the development of internal insulation defects of a cable terminal. This method is implemented based on the above-mentioned simulation test system for the development of internal insulation defects of a cable terminal, and includes the following steps:

[0038] S1. Adjust and monitor the interface pressure of the multi-layer insulation composite in real time through the interface pressure monitoring module. A composite insulation material (ethylene propylene diene monomer rubber 7 and low-density polyethylene 8 doped with carbon black) equipped with a pressure sensor 14 and containing prefabricated insulation defects 15 (air gaps, carbon traces) forms a composite interface similar to that between the main insulation and the stress control tube inside a high-voltage cable terminal, and it is placed between a transparent upper acrylic pressing plate 6 and a transparent lower acrylic pressing plate 9, and fixed with insulating bolts 12 and a variable pressure spring assembly 10. Adjust the variable pressure knob 13 until the interface pressure shown on the second workstation 19 reaches the required test value of 0.424 MPa.

[0039] S2. Apply a power frequency high voltage through the system voltage control module to trigger partial discharge and maintain the applied voltage higher than the discharge inception voltage. Adjust the non-corona transformer 3 to adjust the test voltage to 30 kV to trigger partial discharge.

[0040] S3. Obtain image data during the evolution of insulation defects through the interface defect detection module. According to the image information collected by the high-speed camera, study the speed and shape changes of typical insulation defects (i.e., the prefabricated air gaps and carbon traces) developing from the low-voltage end to the high-voltage end, and obtain their development paths and path morphology characteristics.

[0041] S4. Obtain discharge signal data through the partial discharge detection module, and at the same time establish a mapping relationship between the evolution morphology of the multi-layer insulation composite interface defects obtained in S3 and the characteristics of partial discharge signals, to realize the synchronous recording and correlation analysis of partial discharge behavior and insulation deterioration process, and clarify the response law between partial discharge signal parameters and defect development stages.

[0042] Use the wavelet threshold denoising method for partial discharge signals to denoise the discharge signals such as high-frequency pulse signals and current signals collected by the partial discharge detection module, so as to effectively remove noise signals such as corona interference.

[0043] Subsequently, adjust the variable pressure knob 13 and complete the above S2, S3, and S4 under different interface pressure states to explore the development and evolution laws of typical defects in the multi-layer insulation composite interface inside the cable terminal under different interface pressures, so as to find the optimal control of the interface pressure to achieve the reliable operation of the cable terminal.

[0044] In summary, the present application proposes a simulation test system and method for the development of internal insulation defects in cable terminals. Focusing on the complex working conditions and potential defect evolution problems borne by the multi-layer insulation interface of in-vehicle high-voltage cable terminals during actual operation, a highly integrated test system integrating interface pressure regulation, voltage loading, defect visualization, and partial discharge signal sensing is constructed. Through the coordinated cooperation of the acrylic pressing plate, variable voltage knob, and high-precision pressure sensor, the system realizes the dynamic regulation and precise measurement of the pressure of the multi-layer composite insulation interface for the first time, effectively breaking through the technical bottleneck of uncontrollable and non-quantifiable interface forces in traditional means. In terms of composite material construction, the system selects ethylene propylene diene monomer rubber and low-density polyethylene doped with carbon black to form a multi-layer composite structure. Artificial prefabricated air gaps and carbon trace defects accurately simulate typical insulation weaknesses during cable operation. By introducing a high-speed camera system, the morphological evolution, directional expansion, and electrical tree development path of defects under the dual action of electric field and pressure are dynamically captured, and for the first time, the typical behavioral characteristics of the evolution of insulation defects from the low-voltage end to the high-voltage end can be intuitively demonstrated. In terms of signal acquisition and recognition, through the combination of HFCT, CT coils, and partial discharge detectors in the partial discharge detection module of the system, and in cooperation with high-frequency oscilloscopes and wavelet transform + neural network algorithm processing means, a mapping relationship and response law between partial discharge signal parameters and the development stage of insulation defects are successfully established, realizing real-time tracking, data analysis, and failure warning of the defect evolution process. The solution proposed in the present application not only achieves technological innovation in terms of the structural design of the test device, defect evolution observation, and signal analysis dimensions, but also provides a solid experimental basis and theoretical support for in-depth research on the failure mechanism of the insulation interface of in-vehicle cable terminals and the construction of a partial discharge recognition and condition diagnosis system, with broad engineering application prospects and important promotion value.

[0045] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and the descriptions in the specification only illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and all of these changes and improvements fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A simulation test system for the development of internal insulation defects in cable terminals, characterized in that, Comprising: A system voltage control module for applying a power frequency high voltage to simulate an operating voltage environment; An interface pressure monitoring module for applying an adjustable pressure and real-time monitoring of pressure changes; An interface defect detection module for simulating the development process of internal insulation defects in a cable and collecting defect development image information; A partial discharge detection module for obtaining partial discharge signals generated during the development process of insulation defects.

2. The simulation test system for the development of internal insulation defects of a cable terminal according to claim 1, characterized in that The system voltage control module includes a power supply (23), the output end of the power supply (23) is connected to the input end of a corona-free transformer (3), the output end of the corona-free transformer (3) is connected to one end of a protective resistor (2), and the other end of the protective resistor (2) is connected to the input end of a coupling capacitor (1).

3. The simulation test system for the development of internal insulation defects of a cable terminal according to claim 2, wherein, The interface defect detection module includes a composite insulation material, the composite insulation material includes ethylene propylene diene monomer rubber (7) and low-density polyethylene doped with carbon black (8) arranged opposite to each other up and down, a prefabricated defect area (15) is arranged between the ethylene propylene diene monomer rubber (7) and the low-density polyethylene doped with carbon black (8), high-voltage electrodes (16) and grounding electrodes (17) are respectively arranged at both ends of the composite insulation material, and a high-speed camera (18) is arranged above the composite insulation material.

4. The simulation test system for the development of internal insulation defects of cable terminals according to claim 3, characterized in that, The prefabricated defect area (15) includes air gaps and carbon traces, and the carbon traces are arranged at the bottom of the air gaps.

5. The simulation test system for the development of internal insulation defects of a cable terminal according to claim 4, characterized in that, The interface pressure monitoring module includes a transparent upper acrylic pressing plate (6) and a transparent lower acrylic pressing plate (9) for fixing the composite insulation material, a variable pressure spring assembly (10), an insulating plate (11), a variable pressure knob (13) and an insulating bolt (12) are sequentially arranged from top to bottom below the lower acrylic pressing plate (9).

6. The simulation test system for the development of internal insulation defects of a cable terminal according to claim 5, characterized in that, The interface pressure monitoring module further includes a pressure sensor (14) and a second workstation (19), the pressure sensor (14) is embedded between the ethylene propylene diene monomer rubber (7) and the low-density polyethylene doped with carbon black (8), and the second workstation (19) is connected to the pressure sensor (14).

7. The simulation test system for the development of internal insulation defects of a cable terminal according to claim 6, characterized in that, The prefabricated defect area (15) extends in a strip shape from one end of the grounding electrode (17) to one end of the high-voltage electrode (16) inside the composite insulation material, and there are a total of four pressure sensors (14), which are distributed at the four corners inside the composite insulation material.

8. The simulation test system for the development of internal insulation defects of a cable terminal according to claim 7, characterized in that, The partial discharge detection module includes a CT coil (4), a first workstation (5), a partial discharge detector (22), an HFCT coil (21) and an oscilloscope (20), the input end of the CT coil (4) is connected to the output end of the high-voltage electrode (16), the output end of the CT coil (4) is respectively connected to the input end of the coupling capacitor (1) and the input end of the oscilloscope (20), the input end of the partial discharge detector (22) is connected to the grounding end of the coupling capacitor (1), the output end of the partial discharge detector (22) is connected to the input end of the first workstation (5), the input end of the HFCT coil (21) is connected to the output end of the grounding electrode (17), and one output end of the HFCT coil (21) is connected to the oscilloscope (20), and the other output end is grounded.

9. A simulation test method for the development of internal insulation defects in cable terminals, characterized in that, Implemented based on the simulation test system for the development of internal insulation defects in cable terminals according to any one of claims 1-8, including the following steps: S1. Adjust and real-time monitor the interface pressure of the multi-layer insulation composite interface through the interface pressure monitoring module. The multi-layer insulation composite interface includes a composite insulation material and a pressure sensor (14) and a prefabricated defect area (15) embedded therein; S2. Apply a power frequency high voltage by using the system voltage control module to trigger partial discharge and maintain the applied voltage higher than the discharge inception voltage; S3. Obtain image data during the defect evolution process of the multi-layer insulation composite interface through the interface defect detection module; S4. Obtain discharge signal data through the partial discharge detection module and perform correlation analysis with the multi-layer insulation composite interface defect evolution image obtained in S3.

10. The method for simulating the development of internal insulation defects of a cable terminal according to claim 9, characterized in that, S4 further includes: Adopt the wavelet threshold denoising method to denoise the discharge signal to effectively remove noise signals including corona interference.

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