Online monitoring method for mechanical properties of composite insulator core rod

Abstract

The invention provides an on-line monitoring method and system for mechanical properties of a composite insulator core rod, which can monitor the mechanical strength state of an insulator in real time and prevent faults. The method comprises the steps that a tensile machine is used for simulating mechanical stress to generate acoustic emission signals, the signals are collected and analyzed through a K-Means algorithm, and a control group is generated; and constructing an acoustic emission system, collecting acoustic emission event signals generated in the composite insulator in the operation process of the composite insulator, and comparing the acoustic emission event signals with a control group to realize early fault identification and early warning. The system comprises a differential sensor, a pre-amplifier and a data acquisition and processing system, and is used for capturing, amplifying and analyzing acoustic emission signals and dynamically evaluating the state of the insulator. According to the online monitoring method and system, the accuracy and reliability of mechanical property monitoring of the composite insulator core rod are improved, the maintenance cost is reduced, and the online monitoring method and system have important practical value.

Description

Technical Field

[0001] The invention relates to the field of online intelligent monitoring of power equipment, and in particular to an online monitoring method for the mechanical properties of a composite insulator core rod. Background Art

[0002] Composite insulators are key power components that provide mechanical support and electrical insulation. They can ensure that conductors are safely and stably suspended on transmission towers and other equipment, while fixing the position of the conductors and reducing the risk of equipment current leakage and insulation breakdown. Accordingly, composite insulators must withstand mechanical stresses such as tension from the conductors while also withstanding wind force. Therefore, composite insulators also require high mechanical strength and durability. Insulators play a vital role in transmission lines. If an insulator fails, it will inevitably cause a failure of the transmission line, and sometimes even cause a long power outage, causing great harm to the power system and adversely affecting national safety production.

[0003] At present, the detection methods for internal defects of insulators at home and abroad are mainly carried out in the field of optical methods during the inspection stage through optical methods, such as infrared and ultraviolet imaging technology. When defects occur in insulators, they are often accompanied by abnormal heating conditions or discharge signs. Such heating conditions are also accompanied by infrared radiation, and discharge is accompanied by ultraviolet radiation. Therefore, the condition of the insulator can be evaluated by infrared imaging and ultraviolet imaging detection. Specifically, infrared thermal imaging technology uses infrared thermal imaging detection instruments to quickly detect abnormal heating conditions on the surface of the insulator and convert them into infrared thermal images that can be recognized by the naked eye. This infrared thermal image corresponds to the heat distribution field on the surface of the insulator. Therefore, this method can realize online monitoring of electrical equipment. However, if the discharge at the defective part of the insulator is not serious, the temperature change at the discharge point is less obvious, and the infrared thermal imaging method is often not sensitive in this case; at the same time, this method is also greatly limited by the external temperature. If the detection is in a high temperature environment and the ambient temperature is higher than the detection equipment, the infrared thermal imaging method has a poor detection effect. For the ultraviolet imaging method, the beam splitter separates the light source and passes through two channels, ultraviolet light and visible light, respectively. The former is used for corona imaging and the latter is used for imaging the equipment under test. Then, by superimposing these two effects through image fusion technology, the purpose of determining the amount of corona discharge and locating the discharge area can be achieved. However, the UV imaging method reflects the local electric field enhancement phenomenon on the surface of the insulator, and it is difficult to detect internal defects in a timely manner. If the field strength at the defect is less than the discharge threshold, the detection will be invalid.

[0004] There are some other methods for online monitoring of insulators. For example, the detection of leakage current can enable researchers to understand the leakage current situation on the surface of insulators, etc. However, there are currently no effective measures for online monitoring of their mechanical properties.

[0005] In the safe and stable operation of the power grid, once the composite insulator is broken, it will inevitably cause serious accidents. Therefore, it is very important to ensure its good mechanical properties. At present, there is a lack of online monitoring methods for mechanical properties. The existing methods tend to ignore the mechanical properties of insulators while detecting defects. At present, the detection methods of the mechanical properties of insulators are mostly based on destructive experiments. The mechanical properties of insulators are evaluated by equipment such as tensile machines. They are suitable for factory inspection of insulators, but it is difficult to achieve online evaluation of mechanical properties. The adopted insulator mechanical property detection methods have great limitations. The disadvantages such as the inability to detect internal defects and provide detailed location and size information of defects make the mechanical property detection of insulators face great challenges.

[0006] It should be noted that the information disclosed in the above background technology section is only used for understanding the background of the present application, and therefore may include information that does not constitute prior art known to ordinary technicians in the field. Summary of the invention

[0007] The main purpose of the present invention is to overcome the defects existing in the above-mentioned background technology and provide an online monitoring method for the mechanical properties of a composite insulator core rod.

[0008] To achieve the above object, the present invention adopts the following technical solutions:

[0009] An online monitoring method for mechanical properties of a composite insulator core rod comprises the following steps:

[0010] S1. Use a tensile testing machine to apply a known load to the sample core rod to simulate the mechanical stress that the composite insulator is continuously subjected to during operation to generate an acoustic emission signal;

[0011] S2. The acoustic emission signal generated in step S1 is collected, and the signal characteristic parameters are clustered and analyzed using a K-Means clustering algorithm to identify noise signals and mandrel fracture signals, and generate a control group of acoustic emission signals;

[0012] S3. Fix two probes of the differential sensor at both ends of the core rod of the composite insulator to be tested, and connect them to the differential input preamplifier to construct an acoustic emission system for detecting the state and mechanical properties of the composite insulator during long-term operation;

[0013] S4. The acoustic emission event signals generated inside the composite insulator are collected through the acoustic emission system constructed in step S3, and compared with the control group signals generated in step S2, so as to monitor the mechanical strength status of the composite insulator in real time and realize early identification and early warning of faults.

[0014] An online monitoring system for mechanical properties of a composite insulator core rod, used for an online monitoring method for mechanical properties of the composite insulator core rod, comprising:

[0015] A differential sensor, comprising two probes fixed at both ends of a core rod of a composite insulator to be tested, for detecting a tiny acoustic wave event generated when the core rod of the composite insulator is subjected to mechanical stress, and converting the acoustic wave event into an electrical signal;

[0016] A preamplifier, connected to the two probes of the differential sensor, and used to amplify the electrical signal output by the differential sensor;

[0017] The data acquisition and processing system is connected to the preamplifier to receive and digitize the amplified electrical signal, record the characteristic parameters of the acoustic emission signal, and compare it with the pre-generated control group signal to dynamically evaluate the mechanical properties of the insulator to monitor the mechanical strength status of the composite insulator in real time.

[0018] The present invention has the following beneficial effects:

[0019] The present invention provides an online monitoring method and system for the mechanical properties of a composite insulator core rod based on acoustic emission technology, which can monitor and dynamically evaluate the fiber breakage inside the insulator core rod in real time, detect the micro cracks inside the core rod in time, capture the early characteristics of the fault to discover potential dangers, and effectively prevent the occurrence of composite insulator string break accidents. The present invention designs a dynamic monitoring method based on an acoustic emission event view. The monitoring method of the present invention compares the acoustic emission event view with the pre-generated control group signal, and can define the state of the composite insulator core rod during long-term operation, realize the dynamic evaluation of the mechanical properties of the insulator, and can trigger an alarm in time when potential damage is detected, greatly improving the reliability of operation. Furthermore, by embedding the sensor into the hardware and connecting it to the core rod, the problem of the inability to capture or failure of the acoustic emission signal is effectively eliminated, and the direct and reliable detection of the mechanical properties of the core rod is realized. At the same time, the differential sensor and the differential amplifier are used to eliminate the common mode noise from the environment or electromagnetic interference, improve the signal-to-noise ratio, and the differential sensor has the positioning capability, which can determine the specific location of the acoustic emission source through analysis, and help find the specific problem location area in the material. Compared with traditional technologies, the present invention has high monitoring accuracy, low maintenance cost, can realize real-time monitoring, and has high practical value.

[0020] Other beneficial effects of the embodiments of the present invention will be further described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 1 is a flow chart of an online monitoring method for the mechanical properties of a composite insulator core rod according to an embodiment of the present invention, wherein (a) is a process of generating a control group, and (b) is a process of real-time monitoring.

[0022] Figure 2Schematic diagram of the structure of an online monitoring system according to an embodiment of the present invention.

[0023] Figure 3 It is a side cross-sectional view of the composite insulator end structure in the online monitoring system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0024] The following is a detailed description of the embodiments of the present invention. It should be emphasized that the following description is only exemplary and is not intended to limit the scope and application of the present invention.

[0025] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element. In addition, connection can be used for fixing as well as for coupling or communication.

[0026] It should be understood that the orientation or position relationship indicated by terms such as "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0027] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0028] See also Figures 1 to 3 The embodiment of the present invention provides an online monitoring method for the mechanical properties of a composite insulator core rod, comprising the following steps:

[0029] Step S1. Loading the sample core rod: using a tensile testing machine to apply a known load to the sample core rod to simulate the mechanical stress that the composite insulator is continuously subjected to during operation, so as to generate an acoustic emission signal;

[0030] Step S2. Acoustic emission signal collection and analysis: The acoustic emission signals generated in step S1 are collected, and the signal characteristic parameters are clustered and analyzed using a K-Means clustering algorithm to identify noise signals and core rod fracture signals, and generate a control group of acoustic emission signals;

[0031] Step S3. Acoustic emission system device construction: fix two probes 2 of the differential sensor to the two ends of the core rod 8 of the composite insulator 1 to be tested, and connect them to the differential input preamplifier 5 through the signal line 3, so as to construct an acoustic emission system for detecting the state and mechanical properties of the composite insulator during long-term operation; specifically, it can be installed during the manufacturing process of the composite insulator or on the composite insulator in service;

[0032] Step S4. Real-time monitoring and fault diagnosis: The acoustic emission event signal generated inside the composite insulator 1 is collected through the acoustic emission system constructed in step S3, and compared with the control group signal generated in step S2, so as to monitor the mechanical strength state of the composite insulator 1 in real time, and trigger an alarm when an acoustic emission signal highly similar to the signal before the sample breaks is detected, so as to realize early identification and early warning of faults.

[0033] In some embodiments, the characteristic parameters of the acoustic emission signal include one or more of amplitude, ringing count, peak frequency, energy count, duration, and arrival time.

[0034] See also Figure 1 In a preferred embodiment, in step S2, the collection and analysis of the acoustic emission signal specifically includes: collecting characteristic parameters such as ring count, amplitude, peak frequency, etc. of the acoustic emission signal generated by the sample core rod in the process of applying load in step S1; clustering the collected characteristic parameters using the K-Means clustering algorithm to distinguish between noise signals and core rod fracture signals; filtering specific signals according to the clustering results to identify and distinguish between noise signals and core rod fracture signals to improve the accuracy of signal analysis; based on the results of clustering analysis and signal filtering, generating a control group of acoustic emission signals for comparison and analysis with the acoustic emission signals generated by the composite insulator in actual operation in subsequent real-time monitoring.

[0035] See also Figure 1 In a preferred embodiment, step S2 specifically includes: collecting acoustic emission events of the sample core rod during the stretching process, constructing an acoustic emission event graph; analyzing the relationship between the acoustic emission event rate and the increase in tensile stress, and determining the representation of the core rod in the acoustic emission event graph at different stages from brand new to broken; generating an acoustic emission event comparison graph based on the above analysis for reference in the subsequent real-time monitoring process. Step S4 specifically includes: collecting acoustic emission event signals generated inside the composite insulator during long-term operation; comparing and analyzing the collected signal view with the control group view generated in step S2; and evaluating the current mechanical strength state of the composite insulator based on the signal view comparison results.

[0036] See also Figure 2 and Figure 3In a preferred embodiment, in step S3, the construction of the acoustic emission system device includes first installing two probes 2 of the differential sensor on both ends of the core rod 8 of the composite insulator 1, and then crimping the plastic hardware 7 and the brittle core rod 8 through a pressure device to form an interference fit, embedding the sensor probe 2 into the hardware 7, and leading the signal line 3 from the hardware 7 to the preamplifier 5. Since the outer material of the core rod has a high acoustic impedance, placing the sensor probe on the sheath or the hardware may cause the acoustic emission signal to be unable to be captured or fail. The preferred design of the present invention is to directly embed the sensor into the hardware and connect it to the core rod during the crimping process of the composite insulator, which can effectively prevent the occurrence of this problem and realize direct and reliable detection of the mechanical properties of the core rod.

[0037] See also Figure 2 The embodiment of the present invention also provides an online monitoring system for the mechanical properties of a composite insulator core rod, which is used for the online monitoring method of the mechanical properties of the composite insulator core rod, and includes a differential sensor, a preamplifier 5, and a data acquisition and processing system 4. The differential sensor includes two probes 2 fixed at both ends of the core rod 8 of the composite insulator 1 to be tested, which are used to detect the tiny acoustic wave events generated by the composite insulator core rod 8 when subjected to mechanical stress, and convert the acoustic wave events into electrical signals. The preamplifier 5 is connected to the two probes 2 of the differential sensor, and is used to amplify the electrical signal output by the differential sensor. The data acquisition and processing system 4 is connected to the preamplifier 5, and is used to receive and digitize the amplified electrical signal, record the characteristic parameters of the acoustic emission signal, and compare it with the pre-generated control group signal, so as to dynamically evaluate the mechanical properties of the composite insulator 1, so as to monitor the mechanical strength state of the composite insulator 1 in real time.

[0038] See also Figure 2 In a preferred embodiment, the online monitoring system also includes an alarm device 6, which is connected to the data acquisition and processing system 4 and is used to trigger an alarm when the monitored acoustic emission signal matches the preset fault characteristic signal, so as to prompt the maintenance personnel to take corresponding maintenance measures.

[0039] See also Figure 3 In a preferred embodiment, the two probes 2 of the differential sensor are embedded in the hardware 7 at both ends of the composite insulator 1, the hardware 7 made of plastic material is crimped with the core rod 8 of the composite insulator 1 to form an interference fit, and the signal line connected to the probe 2 is led out from the hardware 7 and connected to the preamplifier 5.

[0040] The online monitoring method and system provided by the present invention can monitor the mechanical properties of the composite insulator core rod in real time to ensure the safe and stable operation of the power system. By using acoustic emission technology, differential sensors are installed at both ends of the composite insulator core rod to directly capture tiny acoustic wave events caused by mechanical stress, and convert these acoustic waves into electrical signals. The present invention designs a dynamic monitoring method based on the acoustic emission event view. By comparing with the pre-generated control group signal, it can dynamically evaluate the mechanical properties of the insulator and trigger an alarm in time when potential damage is detected, thereby realizing early identification and early warning of faults. It not only improves the accuracy of monitoring, but also reduces maintenance costs. It has high practical value and broad application prospects.

[0041] The present invention can monitor fiber breakage and micro cracks inside the core rod in real time, accurately locate defective parts, and increase the reliability of decision-making. Through the use of differential sensors and differential amplifiers, the signal-to-noise ratio is effectively improved, environmental and electromagnetic interference is eliminated, and the anti-interference ability of the system is enhanced.

[0042] The specific embodiments of the present invention are further described below.

[0043] The online monitoring system for the mechanical properties of composite insulator core rods includes a differential sensor, a preamplifier 5, a data acquisition and processing system 4, and an alarm device 6. Different from the sensor fixing method of the traditional acoustic emission detection method, the present invention realizes the integration of the composite insulator 1 and the sensor to perform the detection task of the state and mechanical properties of the composite insulator 1 during its long-term operation. At the same time, the influence of on-site noise is effectively eliminated by the arrangement of the differential sensor. The subsequent data acquisition and processing system 4 can dynamically evaluate the mechanical properties of the insulator based on the collected data.

[0044] The differential sensor is used to detect and record tiny acoustic wave events occurring in the composite insulator 1, that is, it can sense and capture the sound fluctuations generated by changes such as cracks inside the material, and then convert them into electrical signals for further analysis and processing. The present invention fits the sensor to the end of the core rod 8 for detection to avoid the problem of high acoustic impedance of the silicone rubber material outside the composite insulator 1. The two probes 2 of the differential sensor are respectively placed at both ends of the core rod 8, and the common mode noise is offset by differential measurement. At the same time, with the help of the positioning capability of the differential sensor, the specific location of the acoustic emission event is determined, which helps to determine the problem area in the material.

[0045] The structure of the composite insulator 1 includes a core rod 8, an shed sheath 9 and a hardware 7. The core rod 8 is the main supporting part of the composite insulator 1 and also the part that provides the mechanical strength of the insulator; the shed sheath 9 plays the role of protecting the core rod 8, and there is an interface between the two as an adhesive layer; the hardware 7 is located at both ends of the composite insulator 1 and is used to connect the insulator to the tower hardware 7, etc. In the manufacturing process of the composite insulator 1, the connection between the end metal accessories and the core rod 8 is crucial. The connection between the two is formed by the interference fit formed by the hardware 7 of the plastic material and the core rod 8 of the brittle material after the static friction is generated by crimping. The hardware 7 is generally a cylindrical column with a cavity. It is put on the core rod 8 and pressurized by a pressure device to make the hardware 7 plastically deform and sleeve the end of the core rod 8 to achieve the connection between the two. In the preferred embodiment of the present invention, before the core rod is crimped with the hardware, the two probes 2 of the differential sensor are installed at both ends of the core rod 8, so that it is directly embedded in the threaded hardware 7 through crimping, and the signal line 3 is led out from the hardware 7 to connect the preamplifier 5.

[0046] The preamplifier 5 is used to amplify the weak signal output by the sensor and enhance the signal strength for better analysis and processing. In order to match the differential sensor, the present invention uses a differential input preamplifier 5, which has two input channels corresponding to the forward input and reverse input of the signal, respectively. By differentially amplifying the two input signals, the purpose of improving the signal-to-noise ratio and eliminating common-mode noise is achieved, and the anti-interference ability of the signal is enhanced.

[0047] The data acquisition and processing system 4 is used to convert the amplified signal into digital form and record the characteristic parameters of the acoustic emission signal, such as amplitude, ring count, energy count, duration, arrival time, etc., and then analyze and process the fiber breakage of the composite insulator 1 to perform graded analysis, and then evaluate the mechanical properties of the insulator. Through the arrangement of multiple sensors and corresponding algorithm calculation and analysis (for example, the time difference between the two sensors collecting the acoustic signal), the problem area in the composite insulator 1 is identified and located.

[0048] Before the online monitoring system of the mechanical properties of the composite insulator core rod is put into use, the core rod 8 is first selected to perform a cluster analysis on the mechanical stress damage it bears. Cluster analysis is an unsupervised learning algorithm that divides the research objects into different groups based on similar characteristics. The K-Means clustering algorithm is widely used due to its high efficiency and simplicity. The present invention uses the K-Means clustering algorithm to perform cluster analysis on the acoustic emission signals generated during the stretching process of the core rod 8 specimen, and divides the acoustic emission signals during the stretching process into different categories. Different acoustic signals such as noise and fracture can be effectively identified through analysis. The signal is collected from the core rod specimen, and a control group is generated. The information of the control group is entered into the data acquisition and processing system. Through the algorithm setting in the system, the internal acoustic signal of the composite insulator core rod and the acoustic signal of the control group are compared in real time, and finally the real-time mechanical state of the composite insulator core rod is obtained.

[0049] The monitoring method proposed in the present invention is tested by the following steps, which are divided into an early stage and a real-time monitoring stage:

[0050] Step 1: During the preliminary preparation, a tensile testing machine is used to apply a load to the sample core rod to simulate the mechanical stress that the composite insulator 1 is continuously subjected to during operation.

[0051] Step 2: K-Means clustering is performed on the characteristic parameters of the acoustic emission signal during the stretching process, such as ring count, amplitude, peak frequency, etc., as the main features, and the signal during the stretching process is analyzed to identify different acoustic emission signals such as noise signals and core rod fracture signals. In the analysis process, specific signals can be filtered according to relevant features.

[0052] Step 3, during the stretching process, the acoustic emission event graph of the sample mandrel is collected to obtain the relationship between its acoustic emission event rate and the increase in tensile stress, and to obtain the representation of the different stages of the mandrel from new to broken in the graph. This graph is used as a reference in the real-time monitoring process.

[0053] Step 4: When the composite insulator 1 is manufactured, the two probes 2 of the differential sensor are directly fixed to the two ends of the core rod 8 during the end crimping process.

[0054] Step 5 , the signal lines 3 drawn from the two sensor probes 2 are respectively connected to the two channels of the differential input preamplifier 5 , and the amplified signals are output to the data acquisition and processing system 4 .

[0055] Step 6, collecting acoustic emission event signals generated inside the composite insulator 1 during long-term operation, and comparing the collected signal view with the control group view obtained in step 3, so as to obtain the current mechanical strength state of the composite insulator 1.

[0056] Step 7, setting the alarm device 6. When it is detected that the acoustic emission signal inside the composite insulator 1 is highly similar to the signal before the sample breaks, the system alarms.

[0057] Compared with the prior art, the advantages of the embodiments of the present invention include:

[0058] (1) The present invention proposes a new method for monitoring the mechanical properties of composite insulator core rods. The method is based on acoustic emission technology and uses the fact that when the core rod is subjected to mechanical stress, it will generate tiny sound waves. These sound waves can be captured by sensors and converted into electrical signals. Through analysis, various problems such as tiny cracks and deformation inside the core rod can be detected. Through this method, the mechanical state of the composite insulator can be monitored in real time, and the early characteristics of possible faults can be captured to discover potential dangers, thereby reducing maintenance costs.

[0059] (2) The present invention can realize dynamic monitoring of the core rod mechanical strength based on the acoustic emission signal within a time period, and compare it with the core rod acoustic emission event view. It can define the state of the composite insulator core rod during long-term operation, and the investment in alarm equipment also greatly improves the operation reliability.

[0060] (3) Since the outer material of the core rod has a high acoustic impedance, whether the sensor probe is placed on the sheath or the hardware, it is possible that the acoustic emission signal cannot be captured or fails. The preferred design of the present invention is to directly embed the sensor into the hardware and connect it to the core rod during the composite insulator crimping process, which can effectively prevent the occurrence of this problem and realize direct and reliable detection of the mechanical properties of the core rod.

[0061] (4) Using differential sensors and differential amplifiers, the common mode noise from the environment or electromagnetic interference can be effectively eliminated by obtaining the difference in the measured signals on the two input channels, thereby improving the signal-to-noise ratio. In addition, differential sensors have positioning capabilities, and can determine the specific location of the acoustic emission source through analysis to help find the specific problem location area in the material.

[0062] The above content is a further detailed description of the present invention in combination with specific / preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, without departing from the concept of the present invention, it can also make several substitutions or modifications to these described embodiments, and these substitutions or modifications should be regarded as belonging to the protection scope of the present invention. In the description of this specification, the description of the reference terms "an embodiment", "some embodiments", "preferred embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in combination with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily target the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In the absence of mutual contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples. Although the embodiments of the present invention and their advantages have been described in detail, it should be understood that various changes, substitutions and modifications can be made herein without departing from the scope of protection of the patent application.

Claims

1. An online monitoring method for the mechanical properties of a composite insulator core rod, characterized in that: The following steps are involved: S1. Use a tensile testing machine to apply a known load to the sample core rod to simulate the mechanical stress that the composite insulator is continuously subjected to during operation to generate an acoustic emission signal; S2. The acoustic emission signal generated in step S1 is collected, and the signal characteristic parameters are clustered and analyzed using a K-Means clustering algorithm to identify noise signals and mandrel fracture signals, and generate a control group of acoustic emission signals; S3. Fix two probes of the differential sensor at both ends of the core rod of the composite insulator to be tested, and connect them to the differential input preamplifier to construct an acoustic emission system for detecting the state and mechanical properties of the composite insulator during long-term operation; S4. The acoustic emission event signals generated inside the composite insulator are collected through the acoustic emission system constructed in step S3, and compared with the control group signals generated in step S2, so as to monitor the mechanical strength status of the composite insulator in real time and realize early identification and early warning of faults.

2. The method for online monitoring of mechanical properties of composite insulator core rods according to claim 1, characterized in that: The characteristic parameters of the acoustic emission signal include one or more of amplitude, ringing count, peak frequency, energy count, duration, and arrival time.

3. The method for online monitoring of mechanical properties of composite insulator core rods according to claim 1 or 2, characterized in that: In step S2, the collection and analysis of the acoustic emission signal specifically includes: Collect characteristic parameters such as ring count, amplitude, peak frequency, etc. of the acoustic emission signal generated by the sample core rod during the load application process in step S1; The K-Means clustering algorithm is used to cluster the collected characteristic parameters to distinguish between noise signals and core rod fracture signals; According to the clustering results, specific signals are filtered to identify and distinguish noise signals from core rod fracture signals, thus improving the accuracy of signal analysis; Based on the results of cluster analysis and signal filtering, a control group of acoustic emission signals was generated for comparative analysis with the acoustic emission signals generated by composite insulators in actual operation in subsequent real-time monitoring.

4. The method for online monitoring of mechanical properties of composite insulator core rods according to any one of claims 1 to 3, characterized in that: Step S2 specifically includes: Acoustic emission events of the sample mandrel are collected during the stretching process, and an acoustic emission event map is constructed; Analyze the relationship between the acoustic emission event rate and the increase in tensile stress, and determine how the different stages of the core rod from new to fracture are represented in the acoustic emission event map; Based on the above analysis, an acoustic emission event comparison chart is generated for reference in the subsequent real-time monitoring process; Step S4 specifically includes: Collect acoustic emission event signals generated inside composite insulators during long-term operation; Compare and analyze the collected signal view with the control group view generated in step S2; Evaluate the current mechanical strength status of the composite insulator based on the signal view comparison results.

5. The method for online monitoring of mechanical properties of composite insulator core rods according to any one of claims 1 to 4, characterized in that: In step S3, the construction of the acoustic emission system device includes first installing two probes of the differential sensor on both ends of the core rod, and then using a pressure device to crimp the plastic hardware and the brittle core rod to form an interference fit, embedding the sensor probe into the hardware, and leading the signal line out of the hardware and connecting it to the preamplifier.

6. The method for online monitoring of mechanical properties of composite insulator core rods according to any one of claims 1 to 5, characterized in that: In step S4, an alarm is also triggered when an acoustic emission signal highly similar to the signal before the sample breaks is detected.

7. An online monitoring system for mechanical properties of composite insulator core rods, used in the online monitoring method for mechanical properties of composite insulator core rods as claimed in any one of claims 1 to 6, characterized in that: include: A differential sensor, comprising two probes fixed at both ends of a core rod of a composite insulator to be tested, for detecting a tiny acoustic wave event generated when the core rod of the composite insulator is subjected to mechanical stress, and converting the acoustic wave event into an electrical signal; A preamplifier, connected to the two probes of the differential sensor, and used to amplify the electrical signal output by the differential sensor; The data acquisition and processing system is connected to the preamplifier to receive and digitize the amplified electrical signal, record the characteristic parameters of the acoustic emission signal, and compare it with the pre-generated control group signal to dynamically evaluate the mechanical properties of the insulator to monitor the mechanical strength status of the composite insulator in real time.

8. The online monitoring system according to claim 7, characterized in that: It also includes an alarm device, which is connected to the data acquisition and processing system and is used to trigger an alarm when the monitored acoustic emission signal matches the preset fault characteristic signal.

9. The online monitoring system according to claim 7 or 8, characterized in that: The two probes of the differential sensor are embedded in the hardware at both ends of the composite insulator. The hardware made of plastic material is crimped with the core rod of the composite insulator to form an interference fit. The signal line connecting the probe is led out from the hardware and connected to the preamplifier.

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