High-voltage cable buffer layer temperature early warning and discharge ablation defect evaluation system and method

Abstract

The invention relates to a high-voltage cable buffer layer temperature early warning and discharge ablation defect evaluation system and method, and the system comprises a high-voltage cable temperature online monitoring and early warning subsystem which is used for setting a high-voltage cable buffer layer dynamic temperature alarm threshold value and carrying out the online monitoring of the real-time temperature data of a high-voltage cable, judging whether the real-time temperature data exceeds a dynamic temperature alarm threshold value or not, if yes, triggering an alarm, outputting an alarm signal and continuing to carry out monitoring and judging operation, and if not, continuing to carry out monitoring and judging operation; the high-voltage cable buffer layer gas infrared spectroscopic analysis subsystem is used for collecting characteristic gas in the high-voltage cable buffer layer based on the alarm signal, carrying out infrared spectroscopic analysis, comparing infrared spectroscopic analysis results according to a set high-voltage cable buffer layer ablation degree judgment standard, and sending the comparison result to the high-voltage cable buffer layer gas infrared spectroscopic analysis subsystem; and determining the discharge ablation degree of the high-voltage cable buffer layer. Compared with the prior art, the method has the advantages of accurately judging the ablation degree of the cable buffer layer and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of cable fault detection, and in particular to a system and method for evaluating temperature early warning and discharge ablation defects of a high-voltage cable buffer layer. Background Art

[0002] As the power industry develops rapidly, the increase in electrical equipment has made the safety of high-voltage cables a focus of public attention. As a key medium for power transmission, the stability and reliability of high-voltage cables are the cornerstones for ensuring the safe operation of the power grid. However, in the daily operation of high-voltage cables, various factors, including natural aging of materials, physical damage from the outside, and technical defects in the manufacturing process, may cause discharge and ablation problems in the buffer layer of the cable. Such problems will not only cause the temperature of the cable body to rise and shorten its service life, but in extreme cases, they may also trigger cable failures, leading to equipment damage and power outages, posing a great threat to personnel safety.

[0003] Specifically, the discharge ablation defect of the buffer layer of the high-voltage cable is caused by the continuous action of the electric field, thermal stress and mechanical force on the insulation material inside the cable during long-term operation, which leads to the degradation of material performance and the occurrence of discharge in local areas. This discharge phenomenon will further aggravate the damage of the insulation material, forming a vicious cycle, and eventually leading to the complete failure of the cable insulation performance. Once the insulation performance of the cable deteriorates, the cable body will heat up, which will not only reduce the transmission efficiency of the cable, but may also cause a fire due to excessive temperature, causing serious economic losses and social impacts.

[0004] In addition, the failure of high-voltage cables may also lead to the interruption of power supply, affecting industrial production and residents' lives. Especially under extreme weather conditions, such as storms, earthquakes and other natural disasters, the stability and reliability of cables are particularly important. Therefore, in-depth research on the safety performance of high-voltage cables and the adoption of effective monitoring and maintenance measures are of great significance to ensure the stable operation of the power system, extend the service life of cables, reduce power outages and protect personnel safety.

[0005] In summary, the safety of high-voltage cables cannot be ignored. Experts in the power industry and related fields need to work together to improve the safety performance of cables and ensure the reliable operation of power systems through technological innovation and standardized management. Therefore, a scheme for evaluating the ablation defects of high-voltage cable buffer layers is proposed, which is of great significance to the safe operation of high-voltage cables. Summary of the invention

[0006] The purpose of the present invention is to provide a high-voltage cable buffer layer temperature warning and discharge ablation defect assessment system and method that can achieve accurate online monitoring, early warning and ablation degree determination.

[0007] The purpose of the present invention can be achieved by the following technical solutions:

[0008] A high-voltage cable buffer layer temperature early warning and discharge ablation defect assessment system, characterized in that it includes a high-voltage cable temperature online monitoring early warning subsystem and a high-voltage cable buffer layer gas infrared spectrum analysis subsystem connected thereto,

[0009] The high-voltage cable temperature online monitoring and early warning subsystem is used to set the dynamic temperature alarm threshold of the high-voltage cable buffer layer and monitor the real-time temperature data of the high-voltage cable online, and then determine whether the real-time temperature data exceeds the dynamic temperature alarm threshold. If so, trigger an alarm, output an alarm signal, and continue to perform monitoring and judgment operations. If not, continue to perform monitoring and judgment operations;

[0010] The high-voltage cable buffer layer gas infrared spectrum analysis subsystem is used to collect characteristic gases in the high-voltage cable buffer layer based on the alarm signal, perform infrared spectrum analysis, and compare the infrared spectrum analysis results according to the set high-voltage cable buffer layer ablation degree judgment standard to determine the discharge ablation degree of the high-voltage cable buffer layer.

[0011] Furthermore, the step of setting the dynamic temperature alarm threshold of the high-voltage cable buffer layer includes:

[0012] Retrieve the historical temperature data and load current data of the monitored high-voltage cable, perform parameterized curve fitting, and predict the temperature of the high-voltage cable at the next moment;

[0013] The historical temperature rise data of discharge ablation of the high-voltage cable buffer layer is obtained, and the dynamic temperature alarm threshold of the high-voltage cable buffer layer is calculated in combination with the predicted temperature at the next moment.

[0014] Furthermore, the step of predicting the temperature of the high-voltage cable at the next moment includes:

[0015] 1) Determine the parameterized fitting equation:

[0016] The historical temperature data and load current data are set as multiple data points: (I1 2 , T 01 , T1), (I2 2 , T 02 , T2)...(I i 2 , T 0i , T i )...(I n 2 , T 0n , T n), a polynomial parameterized equation is used as a parameterized fitting equation, wherein the expression of the parameterized fitting equation is:

[0017] T i =a2I i 2 +a1T 0i +a0

[0018] Where, T i is the cable temperature at the i-th moment, a2, a1, a0 are the fitting coefficients of the parameterized fitting equation, T 0i is the ambient temperature outside the cable at the i-th moment, I i 2 is the square value of the cable load current at the i-th moment;

[0019] 2) Determine the fitting coefficient:

[0020] Substituting the multiple data points into the parameterized fitting equation, a matrix formula is obtained:

[0021]

[0022] The matrix formula is calculated to obtain the fitting coefficients of the parameterized fitting equation:

[0023]

[0024] 3) Substitute the fitting coefficient into the parameterized fitting equation, and calculate the square value of the load current I at the time n+1 n+1 2 and the cable external ambient temperature T 0n+1 Calculate the predicted temperature T of the high voltage cable at time n+1 n+1 .

[0025] Furthermore, the step of calculating the dynamic temperature alarm threshold of the high-voltage cable buffer layer includes:

[0026] Determine a temperature rise warning value k based on historical temperature rise data of discharge ablation of the high-voltage cable buffer layer;

[0027] Based on the temperature rise warning value k and the predicted temperature at the next moment, the dynamic temperature alarm threshold of the high-voltage cable buffer layer is calculated. The calculation expression of the dynamic temperature alarm threshold is:

[0028] T m =k+T n+1

[0029] Where, T m is the dynamic temperature alarm threshold, T n+1 is the predicted temperature at the next moment.

[0030] Furthermore, the temperature safety range of the high voltage cable is:

[0031] T∈{T≤(dynamic temperature warning threshold)}

[0032] Where T is the temperature data of the high voltage cable.

[0033] Furthermore, the infrared spectrum analysis result includes the volume fraction of each characteristic gas in the buffer layer of the high-voltage cable.

[0034] Furthermore, the discharge ablation degree of the high-voltage cable buffer layer includes three levels, namely, mild ablation, moderate ablation and severe ablation.

[0035] Furthermore, the step of setting the criterion for determining the degree of ablation of the high-voltage cable buffer layer comprises:

[0036] 1) performing infrared spectroscopy analysis on multiple groups of characteristic gases with different degrees of discharge ablation of high-voltage cable buffer layers to obtain the volume fraction of each characteristic gas in each group, and dividing the multiple groups of characteristic gases with different degrees of discharge ablation of high-voltage cable buffer layers into the three grades;

[0037] 2) The fitting envelope equation is used to calculate the probability of each volume fraction of multiple groups of the same characteristic gas at the same level, and according to the normal distribution probability statistics, the volume fraction interval (μ-3σ, μ+3σ) is selected as the reference range of the volume fraction of the characteristic gas;

[0038] 3) Repeat step 2) multiple times to obtain the reference range of volume fraction of each characteristic gas at three levels under the condition of ablation of the high-voltage cable buffer layer, and use it as the criterion for judging the degree of ablation of the high-voltage cable buffer layer.

[0039] Furthermore, the expression of the fitting envelope equation is:

[0040]

[0041] Where P is the probability of occurrence of each volume fraction value of a characteristic gas in the cable, x is the volume fraction value of a characteristic gas in the cable, and σ and μ are fitting coefficients.

[0042] The present invention also provides a high-voltage cable buffer layer temperature early warning and discharge ablation defect assessment method, comprising the following steps:

[0043] Obtain real-time temperature data of high-voltage cables;

[0044] Determine whether the real-time temperature data exceeds the dynamic temperature alarm threshold, if so, trigger an alarm and output an alarm signal, if not, do not output an alarm signal;

[0045] Based on the alarm signal, characteristic gases in the high-voltage cable buffer layer are collected, infrared spectrum analysis is performed, and the infrared spectrum analysis results are compared according to the set high-voltage cable buffer layer ablation degree judgment standard to determine the discharge ablation degree of the high-voltage cable buffer layer.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] (1) The present invention sets a dynamic temperature alarm threshold in the high-voltage cable temperature online monitoring and early warning subsystem. By comparing the real-time temperature of the high-voltage cable, the ablation defect of the cable buffer layer can be warned in time and an alarm signal can be sent. The high-voltage cable buffer layer gas infrared spectrum analysis subsystem performs infrared spectrum analysis on the gas generated after ablation and compares it with the set ablation degree judgment standard, so as to accurately judge the ablation degree of the cable buffer layer.

[0048] (2) The setting of the dynamic temperature alarm threshold of the present invention takes into account the influence of the cable load current, and the threshold is determined based on a parameterized curve fitted according to the previous temperature data of the cable and the predicted temperature value, which improves the accuracy of the early warning of the high-voltage cable to a certain extent and greatly reduces the operating safety risk of the high-voltage cable.

[0049] (3) The judgment standard for the degree of ablation of the high-voltage cable buffer layer of the present invention is formulated by analyzing the volume fraction of each characteristic gas in multiple groups of cables with different degrees of ablation of the cable buffer layer, and the judgment standard divides the reference range of three different levels of ablation degree, which can accurately judge the specific degree of ablation of the cable buffer layer and provide accurate diagnostic results for determining the maintenance and inspection work plan for ablation of the high-voltage cable buffer layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 It is a schematic diagram of the system structure of the present invention;

[0051] Figure 2 It is a schematic diagram of the method flow of the present invention. DETAILED DESCRIPTION

[0052] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0053] Example 1

[0054] This embodiment provides a high-voltage cable buffer layer temperature early warning and discharge ablation defect assessment system, such as Figure 1As shown, the system includes: a high-voltage cable temperature online monitoring and early warning subsystem 1 and a high-voltage cable buffer layer gas infrared spectrum analysis subsystem 2; the high-voltage cable temperature online monitoring and early warning subsystem 1 has a dynamic temperature alarm threshold; the high-voltage cable buffer layer gas infrared spectrum analysis subsystem 2 has a cable buffer layer ablation degree judgment standard.

[0055] The high-voltage cable temperature online monitoring and early warning subsystem 1 has a dynamic temperature alarm threshold, and specifically includes the following steps:

[0056] S1. Call the previous temperature data and load current data of the monitored cable; perform parameterized curve fitting based on the previous temperature data and load current data of the monitored cable to estimate and predict the temperature of the cable at the next moment.

[0057] Step S1 specifically includes:

[0058] S11. Determine the parameterized fitting equation:

[0059] Set the previous monitoring temperature data of the monitored cable to n data points: (I1 2 , T 01 , T1), (I2 2 , T 02 , T2)...(I i 2 , T 0i , T i )...(I n 2 , T 0n , T n ), where T i is the cable temperature at the i-th moment, T 0i is the ambient temperature outside the cable at the i-th moment, I i 2 is the square value of the cable load current at the i-th moment;

[0060] Therefore, the predicted temperature point can be obtained as the n+1th moment, that is, the predicted temperature data point is (I n+1 2 , T 0n+1 , T n+1 ), a polynomial parameterized equation is used as the parameterized fitting equation, and the parameterized fitting equation is formula (1):

[0061] T i =a2I i 2 +a1T 0i +a0 (1)

[0062] Among them, a2, a1, and a0 are the fitting coefficients of the parameterized fitting equation.

[0063] S12. Determine the fitting coefficient:

[0064] n data points (I i 2 , T 0i , T i ) into the equation, we can get the matrix formula (2):

[0065]

[0066] By calculating, the fitting coefficient can be calculated:

[0067]

[0068] Specifically, this embodiment selects a cable line with a core current of 1200A and an average ambient temperature of 30°C for temperature prediction. The measurement time is from 12:00 to 18:00, a total of 6 hours, and the data sampling interval is 10 minutes per sampling. In order to verify the accuracy of the temperature prediction results, this embodiment uses a temperature sensor to measure the cable conductor temperature. The cable temperature predicted by the fitting equation is compared with the temperature data measured by the sensor. Among the 36 sets of predicted temperature data, the absolute error rate is within 3%.

[0069] S2. Set the cable dynamic temperature alarm threshold based on the previous temperature rise data of cable buffer layer discharge ablation.

[0070] Step S2 specifically includes:

[0071] S21, setting a temperature rise warning value k according to the previous temperature rise data of cable buffer layer discharge ablation;

[0072] Specifically, based on the previous temperature rise data of cable buffer layer discharge ablation and taking into account the system prediction error, this embodiment sets the temperature rise warning value k=5°C;

[0073] S22. Calculate the dynamic temperature alarm threshold T of the high-voltage cable under operation status m , the calculation formula is formula (4):

[0074] T m =k+T n+1 (4)

[0075] S3. Determine the cable temperature safety range based on the dynamic temperature alarm threshold. If the actual cable temperature exceeds the safety range, an alarm signal is sent; if the actual cable temperature does not exceed the cable temperature safety range, no alarm signal is sent. If the actual cable temperature is T, the cable temperature safety range is:

[0076] T∈{T≤(dynamic temperature alarm threshold)}.

[0077] The high-voltage cable buffer layer gas infrared spectrum analysis subsystem 2 has a cable buffer layer ablation degree judgment standard, which specifically includes the following steps:

[0078] S01. Determine the criteria for judging the degree of ablation of the cable buffer layer;

[0079] S02, perform gas collection operations. First, remove a certain length of the cable outer sheath to expose the cable aluminum sheath; then, cut a window out of the cable aluminum sheath and use the air inlet of the gas extraction device to block the window; finally, open the gas valve and extract gas to obtain a gas sample;

[0080] S03. Perform infrared spectrum analysis on the collected gas samples to obtain the volume fraction of each characteristic gas in the monitored cable;

[0081] S04. Based on the cable buffer layer ablation degree judgment standard, compare the volume fraction of each characteristic gas in the monitored cable to determine the discharge ablation degree of the cable buffer layer.

[0082] Step S01 specifically includes:

[0083] S011. Perform infrared spectroscopy analysis on multiple groups of gas inside cables with different degrees of discharge ablation of cable buffer layers to obtain the volume fraction of each characteristic gas in each group of data; classify the degree of ablation of cable buffer layers into three levels: mild ablation, moderate ablation and severe ablation, and classify multiple groups of gas inside cables with different degrees of discharge ablation of cable buffer layers according to the above three levels, and the classification is based on the results of cable window inspection;

[0084] S012. Perform statistical analysis on the same characteristic gas in multiple groups of data at the same level, and calculate the probability of occurrence of each volume fraction value of a certain characteristic gas in the cable;

[0085] S013. Determine the fitting envelope equation:

[0086]

[0087] Among them, P is the probability of occurrence of each volume fraction value of a characteristic gas in the cable, x is the volume fraction value of a characteristic gas in the cable, and σ and μ are fitting coefficients.

[0088] Substitute the gas sample data in the cable into formula (5), calculate the fitting coefficient value and substitute it into formula (5), and get the fitting equation;

[0089] S014. According to normal distribution probability statistics, a volume fraction interval (μ-3σ, μ+3σ) is selected as a reference range of the volume fraction of the characteristic gas under the ablation degree of the cable buffer layer;

[0090] S015. Repeat the above operations of S013 and S014 to obtain reference ranges of volume fractions of characteristic gases under three levels of discharge ablation of the cable buffer layer.

[0091] Specifically, this embodiment collects gas in the buffer layer of 15 sections of cable lines with three levels of ablation, including light, moderate and severe, with a total of 285 sets of gas data, to determine the standard for determining the degree of ablation of the cable buffer layer.

[0092] By analyzing the data, this embodiment selects H2, CH4, and CO as characteristic gases for determination. Through envelope equation fitting calculation, the cable buffer layer ablation degree determination standard determined in this embodiment is shown in Table 1 below.

[0093] According to the determined cable buffer layer ablation degree judgment standard, this embodiment selects 3 cable lines (6 sampling points in each line) with a total of 18 gas sampling points for detection, and performs window inspection on the cable, and compares the results of the window inspection with the judgment results of the high-voltage cable buffer layer gas infrared spectrum analysis subsystem 2. Among them, the judgment results of 17 sampling points are consistent with the window inspection results, and the judgment accuracy rate reaches 94.4%.

[0094] Table 1 Determination criteria for cable buffer layer ablation degree

[0095] Ablation degree <![CDATA[H2 volume fraction]]> <![CDATA[CH4 volume fraction]]> CO volume fraction Mild <10％ >13％ <1.5％ Moderate 10％～20％ 8％～13％ 1.5％～3％ serious >20％ <8％ >3％

[0096] Example 2

[0097] This embodiment provides a high-voltage cable buffer layer temperature early warning and discharge ablation defect assessment method, based on the system implementation of the embodiment, such as Figure 2 As shown, the method comprises the following steps:

[0098] Step 1: Use the high-voltage cable temperature online monitoring and early warning subsystem 1 to obtain the real-time temperature data of the high-voltage cable;

[0099] Step 2: The high-voltage cable temperature online monitoring and early warning subsystem 1 determines whether the real-time temperature data exceeds the dynamic temperature alarm threshold. If so, an alarm is triggered and an alarm signal is output. Otherwise, no alarm signal is output.

[0100] Step 3, the high-voltage cable buffer layer gas infrared spectrum analysis subsystem 2 collects characteristic gases in the high-voltage cable buffer layer based on the alarm signal, performs infrared spectrum analysis, and compares the infrared spectrum analysis results according to the set high-voltage cable buffer layer ablation degree judgment standard to determine the discharge ablation degree of the high-voltage cable buffer layer.

[0101] The rest is the same as in Example 1.

[0102] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0103] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A high-voltage cable buffer layer temperature warning and discharge ablation defect assessment system, characterized in that: It comprises a high-voltage cable temperature online monitoring and early warning subsystem (1) and a high-voltage cable buffer layer gas infrared spectrum analysis subsystem (2) connected thereto, The high-voltage cable temperature online monitoring and early warning subsystem (1) is used to set the dynamic temperature alarm threshold of the high-voltage cable buffer layer and monitor the real-time temperature data of the high-voltage cable online, and then determine whether the real-time temperature data exceeds the dynamic temperature alarm threshold. If so, trigger an alarm, output an alarm signal, and continue the monitoring and judgment operation. If not, continue the monitoring and judgment operation. The high-voltage cable buffer layer gas infrared spectrum analysis subsystem (2) is used to collect characteristic gases in the high-voltage cable buffer layer based on the alarm signal, perform infrared spectrum analysis, and compare the infrared spectrum analysis results according to the set high-voltage cable buffer layer ablation degree judgment standard to determine the discharge ablation degree of the high-voltage cable buffer layer.

2. A high-voltage cable buffer layer temperature early warning and discharge ablation defect assessment system according to claim 1, characterized in that: The step of setting the dynamic temperature alarm threshold of the high-voltage cable buffer layer comprises: Retrieve the historical temperature data and load current data of the monitored high-voltage cable, perform parameterized curve fitting, and predict the temperature of the high-voltage cable at the next moment; The historical temperature rise data of discharge ablation of the high-voltage cable buffer layer is obtained, and the dynamic temperature alarm threshold of the high-voltage cable buffer layer is calculated in combination with the predicted temperature at the next moment.

3. A high-voltage cable buffer layer temperature early warning and discharge ablation defect assessment system according to claim 2, characterized in that: The step of predicting the temperature of the high-voltage cable at the next moment comprises: 1) Determine the parameterized fitting equation: The historical temperature data and load current data are set as multiple data points: (I1 2 , T 01 , T1), (I2 2 , T 02 , T2)...(I i 2 , T 0i , T i )...(I n 2 , T 0n , T n ), a polynomial parameterized equation is used as a parameterized fitting equation, wherein the expression of the parameterized fitting equation is: T i =a2I i 2 +a1T 0i +a0 Where, T i is the cable temperature at the i-th moment, a2, a1, a0 are the fitting coefficients of the parameterized fitting equation, T 0i is the ambient temperature outside the cable at the i-th moment, I i 2 is the square value of the cable load current at the i-th moment; 2) Determine the fitting coefficient: Substituting the multiple data points into the parameterized fitting equation, a matrix formula is obtained: The matrix formula is calculated to obtain the fitting coefficients of the parameterized fitting equation: 3) Substitute the fitting coefficient into the parameterized fitting equation, and calculate the square value of the load current I at the time n+1 n+1 2 and the cable external ambient temperature T 0n+1 Calculate the predicted temperature T of the high voltage cable at time n+1 n+1 .

4. A high-voltage cable buffer layer temperature early warning and discharge ablation defect assessment system according to claim 2, characterized in that: The step of calculating the dynamic temperature alarm threshold of the high-voltage cable buffer layer comprises: Determine a temperature rise warning value k based on historical temperature rise data of discharge ablation of the high-voltage cable buffer layer; Based on the temperature rise warning value k and the predicted temperature at the next moment, the dynamic temperature alarm threshold of the high-voltage cable buffer layer is calculated. The calculation expression of the dynamic temperature alarm threshold is: T m =k+T n+1 Where, T m is the dynamic temperature alarm threshold, T n+1 is the predicted temperature at the next moment.

5. A high-voltage cable buffer layer temperature early warning and discharge ablation defect assessment system according to claim 1, characterized in that: The temperature safety range of the high voltage cable is: T∈{T≤(dynamic temperature warning threshold)} Where T is the temperature data of the high voltage cable.

6. A high-voltage cable buffer layer temperature early warning and discharge ablation defect assessment system according to claim 1, characterized in that: The infrared spectrum analysis result includes the volume fraction of each characteristic gas in the buffer layer of the high-voltage cable.

7. A high-voltage cable buffer layer temperature early warning and discharge ablation defect assessment system according to claim 1, characterized in that: The discharge ablation degree of the high-voltage cable buffer layer includes three levels, namely, light ablation, moderate ablation and severe ablation.

8. A high-voltage cable buffer layer temperature early warning and discharge ablation defect assessment system according to claim 7, characterized in that: The steps for setting the judgment standard of the ablation degree of the high-voltage cable buffer layer include: 1) performing infrared spectroscopy analysis on multiple groups of characteristic gases with different degrees of discharge ablation of high-voltage cable buffer layers to obtain the volume fraction of each characteristic gas in each group, and dividing the multiple groups of characteristic gases with different degrees of discharge ablation of high-voltage cable buffer layers into the three grades; 2) The fitting envelope equation is used to calculate the probability of each volume fraction of multiple groups of the same characteristic gas at the same level, and according to the normal distribution probability statistics, the volume fraction interval (μ-3σ, μ+3σ) is selected as the reference range of the volume fraction of the characteristic gas; 3) Repeat step 2) multiple times to obtain the reference range of volume fraction of each characteristic gas at three levels under the condition of ablation of the high-voltage cable buffer layer, and use it as the criterion for judging the degree of ablation of the high-voltage cable buffer layer.

9. A high-voltage cable buffer layer temperature early warning and discharge ablation defect assessment system according to claim 8, characterized in that: The expression of the fitting envelope equation is: Where P is the probability of occurrence of each volume fraction value of a characteristic gas in the cable, x is the volume fraction value of a characteristic gas in the cable, and σ and μ are fitting coefficients.

10. A method for temperature warning and discharge ablation defect assessment of a high-voltage cable buffer layer, characterized in that: The following steps are involved: Obtain real-time temperature data of high-voltage cables; Determine whether the real-time temperature data exceeds the dynamic temperature alarm threshold, if so, trigger an alarm and output an alarm signal, if not, do not output an alarm signal; Based on the alarm signal, characteristic gases in the high-voltage cable buffer layer are collected, infrared spectrum analysis is performed, and the infrared spectrum analysis results are compared according to the set high-voltage cable buffer layer ablation degree judgment standard to determine the discharge ablation degree of the high-voltage cable buffer layer.

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