Polypropylene insulation power cable temperature resistance performance analysis method and system

Abstract

The invention relates to the technical field of electrical equipment, in particular to a method and a system for analyzing the temperature resistance of a polypropylene insulated power cable. The method comprises the following steps: firstly, acquiring a plurality of polypropylene power cable material samples, and constructing a first polypropylene power cable material sample set; secondly, screening the first polypropylene power cable material sample set through a cable appearance detection model to obtain a second polypropylene power cable material sample set; thirdly, placing the polypropylene power cable material samples in the second polypropylene power cable material sample set in a temperature resistance detection environment, and performing temperature resistance detection on the polypropylene power cable material samples to obtain a temperature resistance detection result; and finally, obtaining a temperature resistance analysis result according to the temperature resistance detection result. According to the method, the temperature resistance of the polypropylene insulation power cable material can be more accurately obtained.

Description

Technical Field

[0001] The invention relates to the technical field of electrical equipment, and in particular to a method and system for analyzing the temperature resistance performance of a polypropylene insulated power cable. Background Art

[0002] In modern power systems, power cables are key power transmission components. Polypropylene (PP), as a cable insulation material, is widely used in power cables due to its superior electrical properties and heat resistance. Polypropylene insulated power cables have low dielectric loss, high dielectric strength, and good mechanical properties, making them excellent in high-voltage power transmission. However, as the operating temperature of the power system continues to increase, higher requirements are placed on the temperature resistance of the cable. The use of cables in high-temperature environments for a long time may cause aging of the insulation material, performance degradation, or even failure, thus affecting the safety and reliability of the power system.

[0003] Existing research on the heat resistance performance analysis of polypropylene insulated power cables is mostly based on the changes in cable tensile properties and resistance under high temperature environments. In fact, changes in the cable's appearance can also reflect the heat resistance performance of polypropylene insulated power cables. Therefore, not combining the cable's appearance will reduce the accuracy of the heat resistance performance analysis of polypropylene insulated power cables.

[0004] Therefore, a method and system for analyzing the temperature resistance performance of polypropylene insulated power cables are proposed. Summary of the invention

[0005] The object of the present invention is to provide a method and system for analyzing the temperature resistance performance of a polypropylene insulated power cable. First, a plurality of polypropylene power cable material samples are obtained to construct a first polypropylene power cable material sample set; secondly, the first polypropylene power cable material sample set is screened through a cable appearance detection model to obtain a second polypropylene power cable material sample set; thirdly, the polypropylene power cable material samples in the second polypropylene power cable material sample set are placed in a temperature resistance performance detection environment, and after T1 hours, the polypropylene power cable material samples are subjected to a temperature resistance performance detection to obtain a temperature resistance performance detection result; finally, a temperature resistance performance analysis result is obtained based on the temperature resistance performance detection result.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A method for analyzing the temperature resistance performance of a polypropylene insulated power cable, comprising:

[0008] A plurality of polypropylene power cable material samples are obtained to construct a first polypropylene power cable material sample set.

[0009] Furthermore, the polypropylene power cable material samples are all from the same polypropylene power cable material; each of the polypropylene power cable material samples has the same size; the size includes length, width and thickness.

[0010] The first polypropylene power cable material sample set is screened to obtain a second polypropylene power cable material sample set.

[0011] Further, collecting cable appearance images of the polypropylene power cable material samples in the first polypropylene power cable material sample set;

[0012] Inputting the cable appearance image into a cable appearance detection model for appearance detection;

[0013] Screen out polypropylene power cable material samples that pass the appearance test to obtain a second polypropylene power cable material sample set;

[0014] The cable appearance detection model includes an input layer, a cable appearance feature map acquisition layer, a cable appearance feature fusion layer and a cable appearance detection result acquisition layer;

[0015] The input layer is used to input the cable appearance image into the cable appearance detection model;

[0016] The cable appearance feature map acquisition layer is used to convolve the cable appearance image to obtain multiple cable appearance feature maps; the cable appearance feature fusion layer is used to perform feature fusion on multiple cable appearance feature maps to obtain cable appearance features; the cable appearance features include the number of cracks, crack area, crack depth, color uniformity, number of bubbles, bubble area and crack area;

[0017] The cable appearance detection result acquisition layer is used to obtain the appearance detection result according to the cable appearance characteristics; the appearance detection result includes a qualified appearance detection and a failed appearance detection.

[0018] The polypropylene power cable material samples in the second polypropylene power cable material sample set are placed in a temperature resistance performance testing environment, and after T1 hours, the polypropylene power cable material samples are tested to obtain temperature resistance performance test results.

[0019] Furthermore, the specific steps include:

[0020] Conducting a cable appearance temperature resistance test on each of the polypropylene power cable material samples;

[0021] When the cable appearance temperature resistance test results of each of the polypropylene power cable material samples are qualified, a cable resistance loss test is performed; when the cable resistance loss test results of each of the polypropylene power cable material samples are qualified, the second polypropylene power cable material sample set is divided to obtain a third polypropylene power cable material sample set, a fourth polypropylene power cable material sample set and a fifth polypropylene power cable material sample set;

[0022] Conducting cable tensile performance testing, cable withstand voltage testing and cable indentation testing on the polypropylene power cable material samples in the third polypropylene power cable material sample set, the fourth polypropylene power cable material sample set and the fifth polypropylene power cable material sample set, respectively;

[0023] The temperature resistance performance test result is obtained based on the cable tensile performance test result, the cable withstand voltage test result and the cable indentation test result.

[0024] Furthermore, the temperature resistance performance testing environment includes: the temperature in the temperature resistance performance testing environment is the upper limit of the use temperature of the polypropylene power cable material sample.

[0025] Furthermore, the cable appearance temperature resistance test includes:

[0026] Obtaining a first volume of the polypropylene power cable material sample before being placed in the temperature resistance performance testing environment;

[0027] Obtaining a second volume of the polypropylene power cable material sample after being placed in the temperature resistance performance testing environment for T1;

[0028] The volume difference between the first volume and the second volume is obtained; when the volume difference is greater than the set volume difference threshold, the output cable appearance temperature resistance test result is unqualified; otherwise, the polypropylene power cable material sample is subjected to appearance inspection; when the appearance inspection result is unqualified, the output cable appearance temperature resistance test result is unqualified; otherwise, the cable appearance temperature resistance test result is qualified.

[0029] Furthermore, the cable tensile performance test includes:

[0030] Apply the same pulling force to each of the polypropylene power cable material samples; detect the first length of each of the polypropylene power cable material samples in the third polypropylene power cable material sample set in the pulling direction before the force is applied;

[0031] After T2 hours of force application, the tension is cancelled; after the tension is cancelled, the polypropylene power cable material sample is subjected to an appearance inspection, and when the appearance inspection result is unqualified, the output cable tensile performance inspection result is unqualified; otherwise, the second length of the polypropylene power cable material sample in the tension direction is detected, and at the same time, after T3 hours of tension is cancelled, the third length of the polypropylene power cable material sample in the tension direction is detected; based on the first length, the second length and the third length, the cable tensile performance inspection result is obtained.

[0032] Furthermore, the cable withstand voltage test includes:

[0033] Conducting a dielectric withstand voltage test on the polypropylene power cable material samples in the fourth polypropylene power cable material sample set by using an insulation withstand voltage tester;

[0034] The test voltage value of the insulation withstand voltage tester is a set fixed value, and the withstand voltage test time is set at the same time;

[0035] Obtaining the leakage current measured by the insulation withstand voltage tester during the withstand voltage test time, and constructing a leakage current curve;

[0036] According to the leakage current curve, the cable withstand voltage test result of the polypropylene power cable material sample is obtained.

[0037] Furthermore, the cable indentation detection includes:

[0038] Selecting N cable indentation detection areas on each of the polypropylene power cable material samples in the fourth polypropylene power cable material sample set;

[0039] Applying pressure to each of the cable indentation detection areas, and removing the pressure after a time T4 of applying the force;

[0040] Detect the thickness change of each cable indentation detection area before and after the force is applied; obtain the cable indentation detection result according to the maximum thickness change, the average thickness change and the thickness change variance of the N cable indentation detection areas.

[0041] The heat resistance performance analysis result is obtained according to the heat resistance performance test result.

[0042] A polypropylene insulated power cable temperature resistance performance analysis system, comprising:

[0043] Polypropylene power cable material sample collection module: used to obtain multiple polypropylene power cable material samples and construct a first polypropylene power cable material sample set;

[0044] Polypropylene power cable material sample screening module: used to screen the first polypropylene power cable material sample set to obtain a second polypropylene power cable material sample set;

[0045] The temperature resistance detection module is used to place the polypropylene power cable material samples in the second polypropylene power cable material sample set in a temperature resistance performance detection environment, and after T1 hours, to detect the polypropylene power cable material samples. The specific steps include: performing a cable appearance temperature resistance test on each of the polypropylene power cable material samples;

[0046] When the cable appearance temperature resistance test results of each of the polypropylene power cable material samples are qualified, a cable resistance loss test is performed; when the cable resistance loss test results of each of the polypropylene power cable material samples are qualified, the second polypropylene power cable material sample set is divided to obtain a third polypropylene power cable material sample set, a fourth polypropylene power cable material sample set and a fifth polypropylene power cable material sample set;

[0047] Conduct cable tensile performance testing, cable withstand voltage testing and cable indentation testing on the polypropylene power cable material samples in the third polypropylene power cable material sample set, the fourth polypropylene power cable material sample set and the fifth polypropylene power cable material sample set, respectively; obtain temperature resistance performance testing results based on the cable tensile performance testing results, the cable withstand voltage testing results and the cable indentation testing results;

[0048] The heat resistance performance analysis result acquisition module is used to obtain the heat resistance performance analysis result according to the heat resistance performance test result.

[0049] Furthermore, the polypropylene power cable material samples are all from the same polypropylene power cable material; each of the polypropylene power cable material samples has the same size; the size includes length, width and thickness.

[0050] Compared with the prior art, the present invention has the following beneficial effects:

[0051] 1. The present invention performs appearance inspection on the collected polypropylene power cable material samples, obtains various defect characteristics of the polypropylene power cable material samples through the cable appearance inspection model, and obtains the appearance inspection results of the polypropylene power cable material samples. This method can eliminate the polypropylene power cable material samples that fail the appearance inspection, and avoid the defects in the appearance of the polypropylene power cable material samples themselves, which will affect the subsequent temperature resistance performance test results.

[0052] 2. The present invention performs cable indentation detection on polypropylene power cable material samples to evaluate the resistance of the insulation layer to mechanical impact. By measuring the thickness change of the polypropylene power cable material sample in each cable indentation detection area before and after the force is applied, the cable indentation detection of the polypropylene power cable material sample can be accurately obtained to ensure that the insulation layer of the cable will not be damaged due to external pressure in actual use.

[0053] 3. The present invention places the polypropylene power cable material sample in a temperature resistance testing environment, and then performs cable appearance temperature resistance testing, cable resistance loss testing, cable tensile performance testing, cable withstand voltage testing and cable indentation testing. This method can comprehensively obtain the performance changes of the polypropylene power cable material sample under an extreme high temperature environment, and then comprehensively and accurately obtain the temperature resistance performance test results of the polypropylene power cable material. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 A flow chart of a method for analyzing the temperature resistance of a polypropylene insulated power cable provided in an embodiment of the present invention;

[0055] Figure 2 A structural diagram of a polypropylene insulated power cable temperature resistance performance analysis system provided by an embodiment of the present invention;

[0056] Figure 3 A structural diagram of a temperature resistance performance detection module provided in an embodiment of the present invention;

[0057] Figure 4 A schematic diagram of a process for obtaining temperature resistance performance test results provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0058] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0059] In modern power systems, power cables are key power transmission components. Polypropylene (PP), as a cable insulation material, is widely used in power cables due to its superior electrical properties and heat resistance. Polypropylene insulated power cables have low dielectric loss, high dielectric strength, and good mechanical properties, which enable them to perform well in high-voltage power transmission. However, as the operating temperature of the power system continues to increase, higher requirements are placed on the temperature resistance of the cable. The use of cables in high-temperature environments for a long time may cause aging of the insulation material, performance degradation, or even failure, thus affecting the safety and reliability of the power system. Therefore, it is necessary to analyze the temperature resistance of polypropylene insulated power cables.

[0060] The present invention provides a method for analyzing the heat resistance performance of a polypropylene insulated power cable. The method is applied to a system for analyzing the heat resistance performance of a polypropylene insulated power cable. For a specific method flow chart and system structure chart, refer to Figure 1 and Figure 2 .

[0061] Embodiment 1

[0062] Reference Figure 1 S10 in the figure is applied to a polypropylene power cable material sample collection module of a polypropylene insulated power cable temperature resistance performance analysis system.

[0063] Furthermore, this embodiment collects 30 polypropylene power cable material samples from the same polypropylene power cable material produced by Company A to construct a first polypropylene power cable material sample set; each of the polypropylene power cable material samples has the same size; the size includes length, width and thickness, please refer to Table 1 for details.

[0064] Table 1 Dimensional data table

[0065] size length width thickness Numeric 5cm 3cm 7mm

[0066] In this step of the present embodiment, a plurality of polypropylene power cable material samples of the same size are selected for testing, thereby ensuring that the subsequent temperature resistance performance test results are not affected by the size of the polypropylene power cable material samples.

[0067] Reference Figure 1 S20 in the figure is applied to a polypropylene power cable material sample screening module of a polypropylene insulated power cable temperature resistance performance analysis system.

[0068] Furthermore, the screening step includes:

[0069] Collecting cable appearance images of the polypropylene power cable material samples in the first polypropylene power cable material sample set;

[0070] Inputting the cable appearance image into a cable appearance detection model for appearance detection;

[0071] Screen out polypropylene power cable material samples that pass the appearance test to obtain a second polypropylene power cable material sample set;

[0072] The cable appearance detection model includes an input layer, a cable appearance feature map acquisition layer, a cable appearance feature fusion layer and a cable appearance detection result acquisition layer;

[0073] The input layer is used to input the cable appearance image into the cable appearance detection model;

[0074] The cable appearance feature map acquisition layer is used to convolve the cable appearance image to obtain multiple cable appearance feature maps; the cable appearance feature fusion layer is used to perform feature fusion on multiple cable appearance feature maps to obtain cable appearance features; the cable appearance features include the number of cracks, crack area, crack depth, color uniformity, number of bubbles, bubble area and crack area; the color uniformity is the difference between the grayscale value of each pixel and the average grayscale value after the cable appearance image is grayed, and the calculation formula is:

[0075]

[0076] Wherein, ysjy represents the color uniformity; M represents the number of pixels of the cable appearance image; hdz m Represented as the gray value of the mth pixel; hdz pj It is expressed as the average gray value of M pixels;

[0077] The cable appearance detection result acquisition layer is used to obtain the appearance detection result according to the cable appearance characteristics; the appearance detection result includes a qualified appearance detection and a failed appearance detection.

[0078] Furthermore, the step of obtaining the appearance detection result according to the cable appearance characteristics includes:

[0079] The cable appearance detection value is obtained according to the cable appearance characteristics, and the calculation formula is:

[0080]

[0081] Where dlwg is the cable appearance detection value; lw is the number of cracks in the cable appearance image; lwmj is the i Expressed as the area of ​​the i-th crack; lwsd max It is expressed as the maximum depth of all cracks; qp is expressed as the number of bubbles in the cable appearance image; qpmj jrepresents the bubble area of ​​the jth bubble; glmj represents the crack area in the cable appearance image; α1, α2, α3 and α4 represent the crack influence coefficient, bubble influence coefficient, crack influence coefficient and color influence coefficient respectively; in this embodiment, α1, α2, α3 and α4 are all set to 0.25, which can also be changed according to the specific implementation situation in practical applications; exp() represents an exponential function with a natural constant as the base;

[0082] When the cable appearance detection value is less than the set first cable appearance detection threshold, the appearance detection result corresponding to the polypropylene power cable material sample is qualified; otherwise, the appearance detection result is unqualified; the first cable appearance detection threshold is obtained based on experience. In this embodiment, appearance detection is performed on 30 polypropylene power cable material samples, and the detection results are all qualified in the appearance detection.

[0083] In this step of the present embodiment, the collected polypropylene power cable material samples are subjected to appearance inspection, and various defect characteristics of the polypropylene power cable material samples are obtained through the cable appearance inspection model to obtain the appearance inspection results of the polypropylene power cable material samples. This method can eliminate the polypropylene power cable material samples that fail the appearance inspection, and avoid the defects in the appearance of the polypropylene power cable material samples themselves, which may affect the subsequent temperature resistance performance test results.

[0084] Reference Figure 1 S30 in the above is used in a temperature resistance test module of a polypropylene insulated power cable temperature resistance performance analysis system. Figure 3 The temperature resistance performance detection module includes: a cable appearance temperature resistance detection unit, a cable resistance loss detection unit, a cable tensile performance detection unit, a cable withstand voltage detection unit and a cable indentation detection unit.

[0085] Furthermore, the polypropylene power cable material samples in the second polypropylene power cable material sample set are placed in a temperature resistance performance test environment, and after T1 hours, the polypropylene power cable material samples are tested to obtain temperature resistance performance test results; the temperature in the temperature resistance performance test environment is the upper limit of the operating temperature of the polypropylene power cable material samples; T1 can be set to 12 hours, 24 hours, 36 hours, etc.

[0086] This step of the present embodiment sets the temperature in the temperature resistance test environment to the upper limit of the operating temperature of the polypropylene power cable material sample, which can measure the temperature resistance test results of the polypropylene power cable material sample under extreme high temperature conditions, and further measure the temperature resistance performance of the polypropylene power cable material sample.

[0087] Further, refer to Figure 4 , the steps for obtaining the temperature resistance test results include:

[0088] Conducting a cable appearance temperature resistance test on each of the polypropylene power cable material samples;

[0089] When the cable appearance temperature resistance test results of each polypropylene power cable material sample are qualified, a cable resistance loss test is performed on each polypropylene power cable material sample; when the cable appearance temperature resistance test results of a polypropylene power cable material sample are unqualified, no subsequent test is performed, and the temperature resistance performance test result is directly output as unqualified;

[0090] When the cable resistance loss test results of each of the polypropylene power cable material samples are qualified, the second polypropylene power cable material sample set is divided to obtain a third polypropylene power cable material sample set, a fourth polypropylene power cable material sample set and a fifth polypropylene power cable material sample set; when the cable resistance loss test result of a polypropylene power cable material sample is unqualified, no subsequent test is performed, and the temperature resistance performance test result is directly output as unqualified;

[0091] Conducting cable tensile performance testing, cable withstand voltage testing and cable indentation testing on the polypropylene power cable material samples in the third polypropylene power cable material sample set, the fourth polypropylene power cable material sample set and the fifth polypropylene power cable material sample set, respectively;

[0092] The temperature resistance performance test result is obtained based on the cable tensile performance test result, the cable withstand voltage test result and the cable indentation test result.

[0093] In this step of the present embodiment, after the polypropylene power cable material sample is placed in a temperature resistance performance test environment, cable appearance temperature resistance test, cable resistance loss test, cable tensile performance test, cable withstand voltage test and cable indentation test are performed. This method can comprehensively obtain the performance changes of the polypropylene power cable material sample under an extreme high temperature environment, and then comprehensively and accurately obtain the temperature resistance performance test results of the polypropylene power cable material sample.

[0094] Furthermore, the cable appearance temperature resistance test includes:

[0095] Obtaining a first volume of the polypropylene power cable material sample before being placed in the temperature resistance performance testing environment;

[0096] Obtaining a second volume of the polypropylene power cable material sample after being placed in the temperature resistance performance testing environment for T1;

[0097] The volume difference between the first volume and the second volume is obtained; when the volume difference is greater than the set volume difference threshold, the output cable appearance temperature resistance test result is unqualified; otherwise, the polypropylene power cable material sample is subjected to appearance inspection; when the appearance inspection result is unqualified, the output cable appearance temperature resistance test result is unqualified; otherwise, the cable appearance temperature resistance test result is qualified.

[0098] Furthermore, the appearance detection is to obtain a cable appearance detection value through a cable appearance detection model; when the cable appearance detection value is less than a set second cable appearance detection threshold, the appearance detection result corresponding to the polypropylene power cable material sample is qualified; otherwise, the appearance detection result is unqualified; the second cable appearance detection threshold is obtained based on experience.

[0099] This step of the present embodiment detects the volume and appearance of the polypropylene power cable material sample after being placed in the temperature resistance performance test environment, and identifies the situation where the polypropylene power cable material sample is over-expanded and has appearance defects in the high temperature environment. This method can accurately obtain the cable appearance temperature resistance test results of the polypropylene power cable material sample, providing a data basis for the subsequent temperature resistance performance analysis.

[0100] Furthermore, the cable resistance loss detection includes:

[0101] S testing areas are selected on each of the polypropylene power cable material samples;

[0102] An insulation resistance tester is used to obtain the resistance value of each detection area; when there is a detection area on the polypropylene power cable material sample whose resistance value is less than the set standard resistance value, the cable resistance loss test result of the polypropylene power cable material sample corresponding to the detection area is unqualified; otherwise, the cable resistance loss test result of the polypropylene power cable material sample is qualified.

[0103] After testing in this embodiment, the cable resistance loss test results of 30 polypropylene power cable material samples are all qualified, so the 30 polypropylene power cable material samples are divided to obtain the third polypropylene power cable material sample set, the fourth polypropylene power cable material sample set and the fifth polypropylene power cable material sample set; the third polypropylene power cable material sample set, the fourth polypropylene power cable material sample set and the fifth polypropylene power cable material sample set each have 10 polypropylene power cable material samples.

[0104] Furthermore, the cable tensile performance test includes:

[0105] Applying the same pulling force to each of the polypropylene power cable material samples, wherein the same pulling force includes the same pulling force magnitude and pulling force direction; detecting a first length of each of the polypropylene power cable material samples in the third polypropylene power cable material sample set in the pulling force direction before the force is applied;

[0106] After T2 hours of force application, the tension is cancelled, and T2 can be set to 30 minutes, 60 minutes, etc.; after the tension is cancelled, the polypropylene power cable material sample is subjected to an appearance inspection to obtain a cable appearance inspection value; when the cable appearance inspection value is less than the set third cable appearance inspection threshold, the appearance inspection result corresponding to the polypropylene power cable material sample is qualified; otherwise, the appearance inspection result is unqualified; the third cable appearance inspection threshold is obtained based on experience; when the appearance inspection result is unqualified, the output cable tensile performance inspection result is unqualified; otherwise, the second length of the polypropylene power cable material sample in the tension direction is detected, and at the same time, the third length of the polypropylene power cable material sample in the tension direction is detected after T3 hours of tension cancellation, and T3 can be set to 30 minutes, 60 minutes, etc.; based on the first length, the second length and the third length, the cable tensile performance inspection value is obtained, and the calculation formula is:

[0107]

[0108] Among them, lsjc represents the cable tensile performance test value; dycd represents the first length; decd represents the second length; dscd represents the third length; β1 and β2 represent the tensile length coefficient and elastic coefficient respectively; β1 and β2 are both set to 0.5, and can also be changed according to the specific implementation situation in practical applications; exp() represents an exponential function with a natural constant as the base;

[0109] When the cable tensile performance test value is greater than a set tensile test threshold, the cable tensile performance test result is that the tensile performance test fails; otherwise, the cable tensile performance test result is that the tensile performance test passes; the tensile test threshold is obtained based on experience.

[0110] In this step of the present embodiment, the length of the polypropylene power cable material sample after force is applied is detected, and the cable tensile performance test value is obtained. This method can obtain the elongation and resilience of the polypropylene cable in a high temperature environment, and thus accurately obtain the cable tensile performance test result.

[0111] Furthermore, the cable withstand voltage test includes:

[0112] Conducting a dielectric withstand voltage test on the polypropylene power cable material samples in the fourth polypropylene power cable material sample set by using an insulation withstand voltage tester;

[0113] The test voltage value of the insulation withstand voltage tester is a set fixed value, and the withstand voltage test time is set at the same time;

[0114] Obtaining the leakage current measured by the insulation withstand voltage tester during the withstand voltage test time, and constructing a leakage current curve;

[0115] According to the leakage current curve, it is determined whether the leakage current curve reaches a steady state before the withstand voltage test time is reached; when the leakage current curve does not reach a steady state, the cable withstand voltage test result is output as unqualified; otherwise, the initial leakage current value, the time when the curve reaches a steady state value, and the leakage current value when the steady state is reached are obtained, and the cable withstand voltage test value is obtained, and the calculation formula is:

[0116]

[0117] Wherein, nyjc represents the cable withstand voltage test value; csxl represents the initial leakage current value; wtxl represents the leakage current value when reaching steady state; T wt It is expressed as the time when the curve reaches the steady-state value; η1 and η2 are respectively expressed as the leakage current reduction rate coefficient and the steady-state leakage current coefficient; η1 and η2 are both set to 0.5, and can also be changed according to the specific implementation situation in practical applications; exp() is expressed as an exponential function with a natural constant as the base;

[0118] When the cable withstand voltage test value is less than the set cable withstand voltage test standard value, the cable withstand voltage test result is output as unqualified; otherwise, the cable withstand voltage test result is output as qualified; the cable withstand voltage test standard value is obtained based on experience.

[0119] This step of the present embodiment performs a cable withstand voltage test on the polypropylene power cable material sample placed in a temperature resistance performance test environment, obtains the leakage current of the polypropylene power cable material sample through the insulation withstand voltage tester, and then obtains the cable withstand voltage test result. This method can accurately evaluate the electrical performance of the polypropylene power cable material in a high temperature environment, thereby more accurately obtaining the overall withstand voltage test result of the polypropylene power cable material sample in a high temperature environment.

[0120] Furthermore, the cable indentation detection includes:

[0121] Selecting N cable indentation detection areas on each of the polypropylene power cable material samples in the fourth polypropylene power cable material sample set;

[0122] Apply pressure to each of the cable indentation detection areas, and remove the pressure after a time T4 of applying the force. T4 can be set to 30 minutes, 60 minutes, etc. The pressure is set according to the area of ​​the cable indentation detection area to ensure that the pressure on each of the cable indentation detection areas is the same;

[0123] Detect the thickness change of each cable indentation detection area before and after the force is applied; the thickness change is the average thickness of the cable indentation detection area before the force is applied minus the average thickness of the cable indentation detection area after the force is applied; in this embodiment, 5 cable indentation detection areas are selected on each polypropylene power cable material sample, and the thickness changes of 10 polypropylene power cable material samples before and after the force is applied in the 5 cable indentation detection areas are obtained. For specific values, refer to Table 2.

[0124] Table 2 Thickness change before and after force application

[0125]

[0126] According to the maximum value of thickness change, the average value of thickness change and the variance of thickness change in the N cable indentation detection areas, the cable indentation detection value is obtained, and the calculation formula is:

[0127] dlyh=exp(χ1*hdbh max +χ2*hdpj+χ3*hdfc);

[0128] Among them, dlyh represents the cable indentation detection value; hdbh max is represented by the maximum value of the thickness change; hdpj is represented by the average value of the thickness change; hdfc is represented by the variance of the thickness change; χ1, χ2 and χ3 are represented by the maximum value coefficient of the thickness change, the average value coefficient of the thickness change and the variance coefficient of the thickness change respectively; χ1, χ2 and χ3 are all set to In practical applications, it can also be changed according to the specific implementation situation; exp() represents an exponential function with a natural constant as the base;

[0129] When the cable indentation detection value is greater than a set indentation detection threshold, the cable indentation detection result is that the cable indentation detection fails; otherwise, the cable indentation detection result is that the cable indentation detection passes; the indentation detection threshold is obtained based on experience.

[0130] This step of the present embodiment performs cable indentation detection on the polypropylene power cable material sample, and can evaluate the resistance of the insulation layer to mechanical impact. By measuring the thickness change of the polypropylene power cable material sample in each cable indentation detection area before and after the force is applied, the cable indentation detection of the polypropylene power cable material sample can be accurately obtained, ensuring that the insulation layer of the cable will not be damaged due to external pressure in actual use.

[0131] Furthermore, based on the cable tensile performance test result, the cable withstand voltage test result and the cable indentation test result, obtaining the temperature resistance performance test result includes: when the cable tensile performance test results of the polypropylene power cable material samples in the third polypropylene power cable material sample set are all qualified, the cable withstand voltage test results of the polypropylene power cable material samples in the fourth polypropylene power cable material sample set are all qualified, and the cable indentation test results of the polypropylene power cable material samples in the fifth polypropylene power cable material sample set are all qualified, the corresponding temperature resistance performance test result of the polypropylene power cable material is qualified; otherwise, the temperature resistance performance test result of the polypropylene power cable material is unqualified.

[0132] Reference Figure 1 S40 in the invention is applied to a temperature resistance performance analysis result acquisition module of a polypropylene insulated power cable temperature resistance performance analysis system.

[0133] Further, when the temperature resistance test result is unqualified, the temperature resistance analysis is not performed; otherwise, based on the obtained cable temperature resistance value, the calculation formula is:

[0134]

[0135] Among them, NWXN represents the cable temperature resistance performance value; lsjc d It is represented by the cable tensile performance test value of the dth polypropylene power cable material sample in the third polypropylene power cable material sample set; xldl b It is represented by the leakage current of the bth polypropylene power cable material sample in the fourth polypropylene power cable material sample set; dlyh c It is represented as the cable indentation detection value of the cth polypropylene power cable material sample in the fifth polypropylene power cable material sample set; and They are respectively expressed as cable tensile coefficient, cable withstand voltage coefficient and cable indentation coefficient; and All are set to In practical applications, it can also be changed according to the specific implementation situation; exp() represents an exponential function with a natural constant as the base.

[0136] Furthermore, the temperature resistance performance level threshold set nwyz={yz1,yz2,…,yz s-1 ,yz s}, when the cable temperature resistance value of the polypropylene power cable material is less than yz1, the corresponding temperature resistance level is level 1; when the cable temperature resistance value of the polypropylene power cable material belongs to the interval [yz1, yz2), the corresponding temperature resistance level is level 2; and so on, when the cable temperature resistance value of the polypropylene power cable material belongs to the interval [yz s-1 ,yzs ), the corresponding temperature resistance grade is s grade; when the cable temperature resistance value of the polypropylene power cable material is greater than or equal to yz s The corresponding temperature resistance level is s+1.

[0137] Embodiment 2

[0138] In Example 1, the method of the present invention is combined with the system to realize the temperature resistance performance detection of polypropylene power cable material; the method of the present invention will be described again in the embodiment of this application, and the specific implementation process includes:

[0139] A plurality of polypropylene power cable material samples are obtained to construct a first polypropylene power cable material sample set.

[0140] Furthermore, the polypropylene power cable material samples are all from the same polypropylene power cable material; each of the polypropylene power cable material samples has the same size; the size includes length, width and thickness.

[0141] The first polypropylene power cable material sample set is screened to obtain a second polypropylene power cable material sample set.

[0142] Further, collecting cable appearance images of the polypropylene power cable material samples in the first polypropylene power cable material sample set;

[0143] Inputting the cable appearance image into a cable appearance detection model for appearance detection;

[0144] Screen out polypropylene power cable material samples that pass the appearance test to obtain a second polypropylene power cable material sample set;

[0145] The cable appearance detection model includes an input layer, a cable appearance feature map acquisition layer, a cable appearance feature fusion layer and a cable appearance detection result acquisition layer;

[0146] The input layer is used to input the cable appearance image into the cable appearance detection model;

[0147] The cable appearance feature map acquisition layer is used to convolve the cable appearance image to obtain multiple cable appearance feature maps; the cable appearance feature fusion layer is used to perform feature fusion on multiple cable appearance feature maps to obtain cable appearance features; the cable appearance features include the number of cracks, crack area, crack depth, color uniformity, number of bubbles, bubble area and crack area;

[0148] The cable appearance detection result acquisition layer is used to obtain the appearance detection result according to the cable appearance characteristics; the appearance detection result includes a qualified appearance detection and a failed appearance detection.

[0149] The polypropylene power cable material samples in the second polypropylene power cable material sample set are placed in a temperature resistance performance testing environment, and after T1 hours, the polypropylene power cable material samples are tested to obtain temperature resistance performance test results.

[0150] Furthermore, the specific steps include:

[0151] Conducting a cable appearance temperature resistance test on each of the polypropylene power cable material samples;

[0152] When the cable appearance temperature resistance test results of each of the polypropylene power cable material samples are qualified, a cable resistance loss test is performed; when the cable resistance loss test results of each of the polypropylene power cable material samples are qualified, the second polypropylene power cable material sample set is divided to obtain a third polypropylene power cable material sample set, a fourth polypropylene power cable material sample set and a fifth polypropylene power cable material sample set;

[0153] Conducting cable tensile performance testing, cable withstand voltage testing and cable indentation testing on the polypropylene power cable material samples in the third polypropylene power cable material sample set, the fourth polypropylene power cable material sample set and the fifth polypropylene power cable material sample set, respectively;

[0154] The temperature resistance performance test result is obtained based on the cable tensile performance test result, the cable withstand voltage test result and the cable indentation test result.

[0155] Furthermore, the temperature resistance performance testing environment includes: the temperature in the temperature resistance performance testing environment is the upper limit of the use temperature of the polypropylene power cable material sample.

[0156] Furthermore, the cable appearance temperature resistance test includes:

[0157] Obtaining a first volume of the polypropylene power cable material sample before being placed in the temperature resistance performance testing environment;

[0158] Obtaining a second volume of the polypropylene power cable material sample after being placed in the temperature resistance performance testing environment for T1;

[0159] The volume difference between the first volume and the second volume is obtained; when the volume difference is greater than the set volume difference threshold, the output cable appearance temperature resistance test result is unqualified; otherwise, the polypropylene power cable material sample is subjected to appearance inspection; when the appearance inspection result is unqualified, the output cable appearance temperature resistance test result is unqualified; otherwise, the cable appearance temperature resistance test result is qualified.

[0160] Furthermore, the cable tensile performance test includes:

[0161] Apply the same pulling force to each of the polypropylene power cable material samples; detect the first length of each of the polypropylene power cable material samples in the third polypropylene power cable material sample set in the pulling direction before the force is applied;

[0162] After T2 hours of force application, the tension is cancelled; after the tension is cancelled, the polypropylene power cable material sample is subjected to an appearance inspection, and when the appearance inspection result is unqualified, the output cable tensile performance inspection result is unqualified; otherwise, the second length of the polypropylene power cable material sample in the tension direction is detected, and at the same time, after T3 hours of tension is cancelled, the third length of the polypropylene power cable material sample in the tension direction is detected; based on the first length, the second length and the third length, the cable tensile performance inspection result is obtained.

[0163] Furthermore, the cable withstand voltage test includes:

[0164] Conducting a dielectric withstand voltage test on the polypropylene power cable material samples in the fourth polypropylene power cable material sample set by using an insulation withstand voltage tester;

[0165] The test voltage value of the insulation withstand voltage tester is a set fixed value, and the withstand voltage test time is set at the same time;

[0166] Obtaining the leakage current measured by the insulation withstand voltage tester during the withstand voltage test time, and constructing a leakage current curve;

[0167] According to the leakage current curve, the cable withstand voltage test result of the polypropylene power cable material sample is obtained.

[0168] Furthermore, the cable indentation detection includes:

[0169] Selecting N cable indentation detection areas on each of the polypropylene power cable material samples in the fourth polypropylene power cable material sample set;

[0170] Applying pressure to each of the cable indentation detection areas, and removing the pressure after a time T4 of applying the force;

[0171] Detect the thickness change of each cable indentation detection area before and after the force is applied; obtain the cable indentation detection result according to the maximum thickness change, the average thickness change and the thickness change variance of the N cable indentation detection areas.

[0172] The heat resistance performance analysis result is obtained according to the heat resistance performance test result.

[0173] In this embodiment, the appearance of the collected polypropylene power cable material samples is inspected, and the various defect characteristics of the polypropylene power cable material samples are obtained through the cable appearance inspection model, and the appearance inspection results of the polypropylene power cable material samples are obtained. This method can eliminate the polypropylene power cable material samples that fail the appearance inspection, so as to avoid the subsequent temperature resistance performance test results being affected by the defects in the appearance of the polypropylene power cable material samples themselves. In this embodiment, the cable indentation detection is performed on the polypropylene power cable material samples, and the resistance of the insulation layer to mechanical impact can be evaluated. By measuring the thickness change of the polypropylene power cable material samples in each cable indentation detection area before and after the force is applied, the cable indentation detection of the polypropylene power cable material samples can be accurately obtained to ensure that the insulation layer of the cable will not be damaged due to external pressure in actual use. In this embodiment, after the polypropylene power cable material samples are placed in the temperature resistance performance test environment, the cable appearance temperature resistance test, cable resistance loss test, cable tensile performance test, cable withstand voltage test and cable indentation test are performed. This method can comprehensively obtain the various performance changes of the polypropylene power cable material samples under extreme high temperature environments, and then comprehensively and accurately obtain the temperature resistance performance test results of the polypropylene power cable material samples.

[0174] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for analyzing the heat resistance performance of polypropylene insulated power cables, characterized in that: include: Acquire multiple polypropylene power cable material samples to construct a first polypropylene power cable material sample set; Screening the first polypropylene power cable material sample set to obtain a second polypropylene power cable material sample set; The polypropylene power cable material samples in the second polypropylene power cable material sample set are placed in a temperature resistance performance testing environment, and after T1 hours, the polypropylene power cable material samples are tested, and the specific steps include: Conducting a cable appearance temperature resistance test on each of the polypropylene power cable material samples; When the cable appearance temperature resistance test results of each of the polypropylene power cable material samples are qualified, a cable resistance loss test is performed; when the cable resistance loss test results of each of the polypropylene power cable material samples are qualified, the second polypropylene power cable material sample set is divided to obtain a third polypropylene power cable material sample set, a fourth polypropylene power cable material sample set and a fifth polypropylene power cable material sample set; Conducting cable tensile performance testing, cable withstand voltage testing and cable indentation testing on the polypropylene power cable material samples in the third polypropylene power cable material sample set, the fourth polypropylene power cable material sample set and the fifth polypropylene power cable material sample set, respectively; Obtaining a temperature resistance performance test result based on the cable tensile performance test result, the cable withstand voltage test result and the cable indentation test result; The heat resistance performance analysis result is obtained according to the heat resistance performance test result.

2. A method for analyzing the heat resistance performance of a polypropylene insulated power cable according to claim 1, characterized in that: The obtaining of a plurality of polypropylene power cable material samples and constructing a first polypropylene power cable material sample set comprises: the polypropylene power cable material samples are all from the same polypropylene power cable material; each of the polypropylene power cable material samples has the same size; the size comprises length, width and thickness.

3. A method for analyzing the heat resistance performance of a polypropylene insulated power cable according to claim 1, characterized in that: Screening the first polypropylene power cable material sample set to obtain a second polypropylene power cable material sample set includes: Collecting cable appearance images of the polypropylene power cable material samples in the first polypropylene power cable material sample set; Inputting the cable appearance image into a cable appearance detection model for appearance detection; Screen out polypropylene power cable material samples that pass the appearance test to obtain a second polypropylene power cable material sample set; The cable appearance detection model includes an input layer, a cable appearance feature map acquisition layer, a cable appearance feature fusion layer and a cable appearance detection result acquisition layer; The input layer is used to input the cable appearance image into the cable appearance detection model; The cable appearance feature map acquisition layer is used to convolve the cable appearance image to obtain multiple cable appearance feature maps; the cable appearance feature fusion layer is used to perform feature fusion on multiple cable appearance feature maps to obtain cable appearance features; the cable appearance features include the number of cracks, crack area, crack depth, color uniformity, number of bubbles, bubble area and crack area; The cable appearance detection result acquisition layer is used to obtain the appearance detection result according to the cable appearance characteristics; the appearance detection result includes a qualified appearance detection and a failed appearance detection.

4. A method for analyzing the heat resistance performance of a polypropylene insulated power cable according to claim 1, characterized in that: The temperature resistance performance testing environment includes: the temperature in the temperature resistance performance testing environment is the upper limit of the use temperature of the polypropylene power cable material sample.

5. A method for analyzing the heat resistance performance of a polypropylene insulated power cable according to claim 1, characterized in that: The cable appearance temperature resistance test includes: Obtaining a first volume of the polypropylene power cable material sample before being placed in the temperature resistance performance testing environment; Obtaining a second volume of the polypropylene power cable material sample after being placed in the temperature resistance performance testing environment for T1; The volume difference between the first volume and the second volume is obtained; when the volume difference is greater than the set volume difference threshold, the output cable appearance temperature resistance test result is unqualified; otherwise, the polypropylene power cable material sample is subjected to appearance inspection; when the appearance inspection result is unqualified, the output cable appearance temperature resistance test result is unqualified; otherwise, the cable appearance temperature resistance test result is qualified.

6. A method for analyzing the heat resistance performance of a polypropylene insulated power cable according to claim 1, characterized in that: The cable tensile performance test includes: Apply the same pulling force to each of the polypropylene power cable material samples; detect the first length of each of the polypropylene power cable material samples in the third polypropylene power cable material sample set in the pulling direction before the force is applied; After T2 hours of force application, the tension is cancelled; after the tension is cancelled, the polypropylene power cable material sample is subjected to an appearance inspection, and when the appearance inspection result is unqualified, the output cable tensile performance inspection result is unqualified; otherwise, the second length of the polypropylene power cable material sample in the tension direction is detected, and at the same time, after T3 hours of tension is cancelled, the third length of the polypropylene power cable material sample in the tension direction is detected; based on the first length, the second length and the third length, the cable tensile performance inspection result is obtained.

7. A method for analyzing the heat resistance performance of a polypropylene insulated power cable according to claim 1, characterized in that: The cable withstand voltage test includes: Conducting a dielectric withstand voltage test on the polypropylene power cable material samples in the fourth polypropylene power cable material sample set by using an insulation withstand voltage tester; The test voltage value of the insulation withstand voltage tester is a set fixed value, and the withstand voltage test time is set at the same time; Obtaining the leakage current measured by the insulation withstand voltage tester during the withstand voltage test time, and constructing a leakage current curve; According to the leakage current curve, the cable withstand voltage test result of the polypropylene power cable material sample is obtained.

8. A method for analyzing the heat resistance performance of a polypropylene insulated power cable according to claim 1, characterized in that: The cable indentation detection comprises: Selecting N cable indentation detection areas on each of the polypropylene power cable material samples in the fourth polypropylene power cable material sample set; Applying pressure to each of the cable indentation detection areas, and removing the pressure after the force is applied at time T4; detecting the thickness change of each of the cable indentation detection areas before and after the force is applied; The cable indentation detection result is obtained according to the maximum value of the thickness change, the average value of the thickness change and the variance of the thickness change of the N cable indentation detection areas.

9. A polypropylene insulated power cable temperature resistance performance analysis system, characterized in that: include: Polypropylene power cable material sample collection module: used to obtain multiple polypropylene power cable material samples and construct a first polypropylene power cable material sample set; Polypropylene power cable material sample screening module: used to screen the first polypropylene power cable material sample set to obtain a second polypropylene power cable material sample set; The temperature resistance detection module is used to place the polypropylene power cable material samples in the second polypropylene power cable material sample set in a temperature resistance performance detection environment, and to detect the polypropylene power cable material samples. The specific steps include: performing a cable appearance temperature resistance test on each of the polypropylene power cable material samples; When the cable appearance temperature resistance test results of each of the polypropylene power cable material samples are qualified, a cable resistance loss test is performed; when the cable resistance loss test results of each of the polypropylene power cable material samples are qualified, the second polypropylene power cable material sample set is divided to obtain a third polypropylene power cable material sample set, a fourth polypropylene power cable material sample set and a fifth polypropylene power cable material sample set; Conduct cable tensile performance testing, cable withstand voltage testing and cable indentation testing on the polypropylene power cable material samples in the third polypropylene power cable material sample set, the fourth polypropylene power cable material sample set and the fifth polypropylene power cable material sample set, respectively; obtain temperature resistance performance testing results based on the cable tensile performance testing results, the cable withstand voltage testing results and the cable indentation testing results; The heat resistance performance analysis result acquisition module is used to obtain the heat resistance performance analysis result according to the heat resistance performance test result.

10. A polypropylene insulated power cable temperature resistance analysis system according to claim 9, characterized in that: The polypropylene power cable material samples are all from the same polypropylene power cable material; each of the polypropylene power cable material samples has the same size; the size includes length, width and thickness.

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