Cable joint overheating fault analysis method and system

Abstract

The invention discloses a cable joint overheating fault analysis method and system, and the method comprises the steps: carrying out the clustering of the target hot-spot temperatures of different cable joints based on each axial temperature change sequence, obtaining at least one target hot-spot temperature set, and carrying out the clustering of cable joints with the same potential risk as much as possible into the same set, the clustering accuracy is improved, overheating risk analysis can be conveniently carried out on each cable joint in the set subsequently, and a two-dimensional coordinate system with the first doubt target hot-spot temperature as a horizontal coordinate and the target temperature change degree corresponding to the first doubt target hot-spot temperature as a vertical coordinate is defined, so that the clustering accuracy is improved. Whether the isolated coordinate point exists or not can be rapidly screened out, and therefore the cable corresponding to the first doubt target hot spot temperature or the second doubt target hot spot temperature corresponding to the isolated coordinate point is determined.

Description

Technical Field

[0001] The invention belongs to the technical field of power cables, and in particular relates to an overheating fault analysis method and system for a cable joint. Background Art

[0002] Power cables are one of the main ways to transmit electric energy in the power system. They are mainly responsible for distributing electric energy from substations to various end users, including residential areas, commercial areas and industrial areas, to ensure the effective distribution of electric energy. Compared with overhead lines, underground cables reduce the possibility of being affected by weather such as wind, rain and snow, avoid line failures caused by weather and climate changes, improve power supply reliability and system stability, and avoid visual and environmental pollution caused by laying wires in the air; they are one of the important components of the urban power supply system.

[0003] The insulation performance of cable joints is one of the decisive factors affecting their transmission of electric energy, and temperature rise is a key factor affecting the insulation performance and safe operation of cable joints. At present, the overheating fault analysis of cable joints often adopts the temperature threshold method. When the measured temperature of the cable joint exceeds the temperature threshold, the cable joint is defined as having an overheating fault. When it does not exceed the temperature threshold, the cable joint is defined as not having an overheating fault. This method often ignores the risk of overheating, resulting in the situation where the temperature of the cable joint gradually rises but does not exceed the limit. Summary of the invention

[0004] The present invention provides a method and system for analyzing overheating faults of a cable joint, which are used to solve the technical problem that it is impossible to perform overheating risk analysis on a cable joint that does not exceed a temperature limit.

[0005] In a first aspect, the present invention provides a method for analyzing an overheating fault of a cable connector, comprising: Obtaining a load current of a cable body and a temperature of at least one surface characteristic point of the cable body, and inputting the load current and the temperature of at least one surface characteristic point into a preset body transient thermal circuit model, solving the body transient thermal circuit model to obtain a characteristic point temperature distribution of a cable conductor in the cable body; According to the characteristic point temperature distribution, a preset cable joint axial fitting function is used to invert and obtain an inverted hot spot temperature of the cable joint connected to the cable body; Obtaining the measured hot spot temperature of the cable joint, and correcting the measured hot spot temperature using a preset temperature correction strategy according to the inverted hot spot temperature to obtain a target hot spot temperature; Determining whether the target hot spot temperature is greater than a first preset temperature threshold; If it is not greater than the first preset temperature threshold, determining the axial temperature change sequence of the cable conductors in the different cable bodies according to the temperature distribution of the characteristic points of the cable conductors in the different cable bodies, and clustering the target hot spot temperatures of the different cable joints based on each axial temperature change sequence to obtain at least one target hot spot temperature set; Selecting a target hotspot temperature from each target hotspot temperature set according to a preset selection rule, defining the target hotspot temperature as a first suspected target hotspot temperature, and comparing each first suspected target hotspot temperature to obtain a first comparison result, and determining whether a first suspected target hotspot temperature is abnormal according to the first comparison result; If a first suspected target hotspot temperature is abnormal, reselect another target hotspot temperature from a target hotspot temperature set where the first suspected target hotspot temperature is located, define the other target hotspot temperature as a second suspected target hotspot temperature, and compare the second suspected target hotspot temperature with other first suspected target hotspot temperatures to obtain a second comparison result, and determine whether the second suspected target hotspot temperature is abnormal according to the second comparison result; If the second suspected target hot spot temperature is abnormal, it is determined that the cable connectors corresponding to the respective target hot spot temperatures in the certain target hot spot temperature set all have overheating risks.

[0006] In a second aspect, the present invention provides an overheating fault analysis system for a cable connector, comprising: A solution module is configured to obtain a load current of a cable body and a temperature of at least one surface characteristic point of the cable body, and input the load current and the temperature of at least one surface characteristic point into a preset body transient thermal circuit model, and solve the body transient thermal circuit model to obtain a characteristic point temperature distribution of a cable conductor in the cable body; An inversion module is configured to obtain an inversion hotspot temperature of a cable joint connected to the cable body by using a preset cable joint axial fitting function according to the characteristic point temperature distribution; A correction module is configured to obtain the measured hot spot temperature of the cable joint, and according to the inverted hot spot temperature, correct the measured hot spot temperature using a preset temperature correction strategy to obtain a target hot spot temperature; A judgment module, configured to judge whether the target hot spot temperature is greater than a first preset temperature threshold; A clustering module is configured to determine the axial temperature change sequence of the cable conductors in different cable bodies according to the temperature distribution of the characteristic points of the cable conductors in different cable bodies if the temperature is not greater than the first preset temperature threshold, and cluster the target hot spot temperatures of different cable joints based on each axial temperature change sequence to obtain at least one target hot spot temperature set; A first comparison module is configured to select a target hotspot temperature from each target hotspot temperature set according to a preset selection rule, define the target hotspot temperature as a first suspected target hotspot temperature, and compare each first suspected target hotspot temperature to obtain a first comparison result, and determine whether a first suspected target hotspot temperature is abnormal according to the first comparison result; A second comparison module is configured to, if a first suspected target hotspot temperature is abnormal, reselect another target hotspot temperature from a target hotspot temperature set where the first suspected target hotspot temperature is located, define the other target hotspot temperature as a second suspected target hotspot temperature, and compare the second suspected target hotspot temperature with other first suspected target hotspot temperatures to obtain a second comparison result, and determine whether the second suspected target hotspot temperature is abnormal according to the second comparison result; The determination module is configured to determine that if the second suspected target hot spot temperature is abnormal, the cable connectors corresponding to the respective target hot spot temperatures in the certain target hot spot temperature set are all at risk of overheating.

[0007] In a third aspect, an electronic device is provided, comprising: at least one processor, and a memory communicatively connected to the at least one processor, wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can perform the steps of the overheating fault analysis method for a cable connector of any embodiment of the present invention.

[0008] In a fourth aspect, the present invention further provides a computer-readable storage medium having a computer program stored thereon, wherein when the program instructions are executed by a processor, the processor executes the steps of the overheating fault analysis method for a cable connector of any embodiment of the present invention.

[0009] The overheating fault analysis method and system of the cable joint of the present application cluster the target hotspot temperatures of different cable joints based on each axial temperature change sequence to obtain at least one target hotspot temperature set, and can cluster cable joints with the same potential risks into the same set as much as possible, thereby improving the accuracy of clustering and facilitating the subsequent overheating risk analysis of each cable joint in the set. By defining a two-dimensional coordinate system with the first suspected target hotspot temperature as the horizontal coordinate and the target temperature change degree corresponding to the first suspected target hotspot temperature as the vertical coordinate, it is possible to quickly screen out whether there are isolated coordinate points, thereby determining the cable corresponding to the first suspected target hotspot temperature or the second suspected target hotspot temperature corresponding to the isolated coordinate point. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0011] Figure 1 A flow chart of a method for analyzing overheating failure of a cable connector provided by an embodiment of the present invention; Figure 2 A location diagram of characteristic temperature points of a specific embodiment is provided for an embodiment of the present invention; Figure 3 A structural block diagram of an overheating fault analysis system for a cable connector provided by an embodiment of the present invention; Figure 4 It is a schematic diagram of the structure of an electronic device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0012] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are 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.

[0013] See also Figure 1 , which shows a flow chart of a cable joint overheating fault analysis method of the present application.

[0014] like Figure 1 As shown, the overheating fault analysis method of the cable connector includes the following steps: Step S101, obtaining the load current of the cable body and the temperature of at least one surface characteristic point of the cable body, and inputting the load current and the temperature of at least one surface characteristic point into a preset body transient thermal circuit model, solving the body transient thermal circuit model to obtain the characteristic point temperature distribution of the cable conductor in the cable body.

[0015] In the step, the transient thermal circuit model can effectively predict the temperature distribution under dynamic load by simplifying the cable heat transfer process into a circuit network.

[0016] The transient thermal circuit model is an equivalent circuit model used to describe the temperature change of cables under dynamic load conditions. It simplifies the heat transfer characteristics of each layer of cable material (such as conductor, insulation layer, filling layer, etc.) into thermal resistance (indicating steady-state heat dissipation capacity) and thermal capacitance (indicating transient absorption / heat dissipation inertia) to construct a circuit-like thermal network model. For example, the transient thermal circuit model of a three-core cable contains the following key parameters: Thermal resistance (R): Characterizes the material's resistance to heat flow, such as insulation layer thermal resistance, air convection thermal resistance, etc.

[0017] Heat Capacity (C): Characterizes the ability of a material to store heat, such as the heat capacity of conductors and insulation layers.

[0018] Heat source (Qs): Joule heat generated by the load current, expressed as (I is the current and R is the conductor resistance).

[0019] Based on the thermal circuit model, write the thermal balance equation according to the law of conservation of energy (similar to KCL in circuits). For example:

[0020] in, is the ambient temperature, is the characteristic point temperature, and t is the time.

[0021] Thermal resistance and heat capacity calculation: Calculate the R and C of each layer through material parameters (thermal conductivity, specific heat capacity, density) and geometric dimensions (thickness, surface area).

[0022] Equivalent thermal contact resistance: Inverse simulation of the effect of joint contact resistance on temperature.

[0023] Numerical methods (such as finite element method and Euler method) are used to solve the thermal differential equations to obtain the temperature variation of each node over time. For example: Use Laplace transform to convert time domain equations into frequency domain equations to simplify calculations.

[0024] The discretized temperature field is solved by iterative methods or matrix operations.

[0025] Step S102: According to the characteristic point temperature distribution, a preset cable joint axial fitting function is used to invert and obtain an inverted hot spot temperature of the cable joint connected to the cable body.

[0026] In this step, the conductor temperature of the first characteristic point and the conductor temperature of the second characteristic point are respectively selected in the characteristic point temperature distribution; the conductor temperature of the first characteristic point and the conductor temperature of the second characteristic point are input into the cable joint axial fitting function to solve the inverse hot spot temperature of the cable joint connected to the cable body.

[0027] It should be noted that in the process of fitting the axial fitting function of the cable joint: the number of characteristic points determines the number of fitting expression items of the axial fitting function of the cable joint. When there is only one characteristic point, it means that the conductor temperature is equal to the hot spot temperature of the cable joint, which is inconsistent with the actual situation, so there are at least two characteristic points. When there are too many characteristic points, there may be overfitting. Considering the actual application, it is a challenge to lay too many temperature sensors on the cable surface. Laying a large number of sensors at the same time will affect the reliability of the overall temperature measurement system.

[0028] The position of the characteristic point from the cable joint determines the coefficient of the term. According to the results of the field survey, a certain distance is left on both sides of the middle joint in the cable trench. Therefore, when determining the distance between the characteristic point and the cable joint, on the one hand, it is necessary to consider that the measuring points should be dispersed as much as possible to reflect the influence of the heat flow of the cable joint and the radial heat flow of the cable body. On the other hand, it is necessary to pay attention to the distance not being too far, which will affect the actual engineering application.

[0029] Goodness of fit It refers to the degree of fit of the regression line to the observed value, that is: , In the formula, y is the value to be fitted, is the mean, is the fitted value, is the number of measuring points. The closer it is to 1, the higher the fitting accuracy. The goodness of fit characterizes the fitting accuracy of the axial fitting function of the cable connector.

[0030] Defining Sensitivity Factors is the maximum absolute value of each coefficient in the axial fitting function of the cable connector, that is: , In the formula, is the coefficient of the axial inversion function; The input of the cable joint axial inversion is the conductor temperature at several points, and the output is the hot spot temperature. There are inevitably errors in the calculation of the thermal circuit model. Substituting it into the axial inversion formula will increase the error. The increase is the absolute value of each coefficient of the inversion function. Obviously, the larger the coefficient, the worse the anti-interference ability and the smaller the robustness of the model. Therefore, the sensitivity coefficient The robustness of the inversion function is characterized.

[0031] The total length of the cable joint is 1.4m. Beyond 2m from the center of the cable joint, the axial heat flow at the joint has little effect on the cable body. Therefore, 5 points at different positions on the conductor axis are selected for optimization. The distances from each point to the end of the joint are 0.1m, 0.3m, 0.6m, 1.2m and 2.0m, respectively, which are called characteristic points. These points maintain several principles: 1) they are all on the cable body; 2) the conductor temperature value increases; 3) from far to near the joint, some near points are affected by the joint heat flow, and far points are basically only affected by the radial heat flow of the cable body.

[0032] Ignoring the changes in conductor material parameters and structural parameters due to temperature, the ambient temperature remains unchanged at 25°C, and the steady-state temperature field simulation calculation of the cable joint is performed. Five characteristic points and joint hotspot temperatures are extracted each time, for a total of 25 groups of samples. 2, 3, 4, and 5 characteristic points are selected for permutation and combination, with the input being the characteristic point temperature and the output being the hotspot temperature. Function fitting is performed in sequence, and a total of 26 combinations are obtained. The calculation results are and As shown in Table 1.

[0033] Table 1 Goodness of fit of each training sample and sensitivity coefficient

[0034] , Analyze goodness of fit It can be seen that the minimum value is 0.9352, which appears in the combination of feature points 4 and 5. These two points are farthest from the middle joint and have the weakest relationship with the heat flow of the joint. Although they are on the main heat flow path, these two points cannot fully reflect the influence of the main heat flow of the joint. In other combinations, the goodness of fit is greater than 0.97, indicating that most combinations can meet the requirements of the axial inversion function. The structure of the fitting accuracy shows that some combinations are unreasonable, but the best feature point combination cannot be selected. Therefore, the difference in sensitivity coefficients will be analyzed next.

[0035] First, the sensitivity coefficients under the 26 combinations are all different, with the maximum being 175.8717 and the minimum being 2.7163. Since the sensitivity coefficient reflects the robustness of the model and will increase the temperature error caused by the thermal circuit model calculation, it is necessary to select a combination with a smaller coefficient. Secondly, with the increase in the number of feature points, the overall sensitivity coefficient also increases, and the sensitivity coefficient of selecting 5 feature points is the largest. However, too many points cause the model to overfit. Although the fitting effect is excellent at this time, there are redundant signal values ​​implied in the model, and the information of the characteristic values ​​cannot be captured, so the generalization ability is weak. According to the above table, it can be seen that it is more appropriate to select two temperature measurement points, and the farther the distance between the two points, the smaller the sensitivity coefficient. Considering the goodness of fit and the sensitivity coefficient, it is determined that the combination of points 1-5 is the best. As Figure 2 As shown in the figure, the former is 0.1 m away from the end of the middle joint, which directly reflects the influence of the joint heat flow, and the latter is 2.0 m away from the end of the middle joint, which contains the effective information of the radial heat flow of the body.

[0036] After analyzing the training samples and the fitting effects under various combinations, the number and coefficients of the conductor axial inversion function terms were finally determined. The expression of the cable joint axial fitting function is: , In the formula, is the inverted hot spot temperature of the jth cable joint, is the conductor temperature of the first characteristic point, which is 0.1 m away from the end of the jth cable connector. is the conductor temperature of the second characteristic point, and the second characteristic point is 2.0 m away from the end of the j-th cable joint.

[0037] Step S103, obtaining the measured hot spot temperature of the cable joint, and correcting the measured hot spot temperature using a preset temperature correction strategy according to the inverted hot spot temperature to obtain a target hot spot temperature.

[0038] In this step, the temperature difference between the inverted hotspot temperature and the measured hotspot temperature is calculated; it is determined whether the absolute value of the temperature difference is greater than a second preset temperature threshold; if it is not greater than the second preset temperature threshold, the inverted hotspot temperature and the measured hotspot temperature are averaged to obtain a target hotspot temperature; if it is greater than the second preset temperature threshold, the inverted hotspot temperature is corrected according to the temperature difference and the second preset temperature threshold to obtain a target hotspot temperature, wherein the expression for correcting the inverted hotspot temperature according to the temperature difference and the second preset temperature threshold is: , In the formula, is the target hot spot temperature, To invert the hotspot temperature, is the temperature difference between the inverted hotspot temperature and the measured hotspot temperature, is the second preset temperature threshold.

[0039] For example, the inverted hotspot temperature is 50°C and the measured hotspot temperature is 45°C, then the temperature difference is 5°C. Assuming that the second preset temperature threshold is set to 3°C, then It is 50℃-(5℃-3℃)=48℃.

[0040] In this embodiment, if it is not greater than the second preset temperature threshold, the inverted hotspot temperature and the measured hotspot temperature are averaged to obtain the target hotspot temperature, which can minimize the impact of the fitting error. If it is greater than the second preset temperature threshold, it means that the current measured hotspot temperature may have a large measurement error when the measuring instrument is collecting the temperature. However, even if there is a large measurement error, it may still have a certain reference value. Therefore, the temperature difference is subtracted from the second preset temperature threshold, and the measurement error is reduced as much as possible based on the subtraction result. The inverted hotspot temperature is corrected by the difference between the temperature difference and the second preset temperature threshold. Compared with not correcting the inverted hotspot temperature, the inversion error can be offset as much as possible, thereby maximizing the accuracy of the target hotspot temperature.

[0041] Step S104, determining whether the target hotspot temperature is greater than a first preset temperature threshold.

[0042] In a specific embodiment, after determining whether the target hotspot temperature is greater than a preset temperature threshold, if it is greater than the preset temperature threshold, it means that the target hotspot temperature exceeds the limit, and it is directly determined that the cable connector corresponding to the target hotspot temperature has an overheating fault.

[0043] Step S105, if it is not greater than the first preset temperature threshold, the axial temperature change sequence of the cable conductors in different cable bodies is determined according to the temperature distribution of the characteristic points of the cable conductors in different cable bodies, and the target hotspot temperatures of different cable joints are clustered based on each axial temperature change sequence to obtain at least one target hotspot temperature set.

[0044] In this step, the positions of the characteristic points of the cable conductor in the cable body along the cable axis direction are determined to obtain a characteristic point position sequence, wherein the position spacing between two adjacent characteristic points in the characteristic point position sequence is the same; According to the dynamic sliding step, a preset first sliding window is used to slide on the feature point position sequence, and each time the sliding occurs, the feature point in the first sliding window is defined as the target feature point, wherein the window size of the first sliding window is the same as the size of a target feature point, and the dynamic sliding step increases with the number of sliding times; Acquire the temperature value of each target feature point, and make a difference between the temperature values ​​of two adjacent target feature points to obtain at least one axial temperature change value, and sort the at least one axial temperature change value based on the position sequence of the feature points to obtain an axial temperature change sequence; According to the preset temperature weight, the temperature variation between the first axial temperature variation sequence and the second axial temperature variation sequence is calculated, and it is determined whether the temperature variation is greater than a preset threshold value, wherein the first axial temperature variation sequence and the second axial temperature variation sequence are any two axial temperature variation sequences, and the expression for calculating the temperature variation is: , In the formula, is the temperature variation between the first axial temperature variation sequence and the second axial temperature variation sequence, is the first axial temperature change value in the first axial temperature change sequence, is the first second axial temperature change value in the second axial temperature change sequence, is the second first axial temperature change value in the first axial temperature change sequence, is the second second axial temperature change value in the second axial temperature change sequence, is the Nth first axial temperature change value in the first axial temperature change sequence, is the Nth second axial temperature change value in the second axial temperature change sequence, for The temperature weight, for The temperature weight, for The temperature weight, ,and , , …, Increasing in an arithmetic progression; If the temperature variation is greater than a preset threshold, the first target hotspot temperature corresponding to the first axial temperature variation sequence and the second target hotspot temperature corresponding to the second axial temperature variation sequence are not classified into the same target hotspot temperature set; If the temperature variation is not greater than a preset threshold, the first target hotspot temperature corresponding to the first axial temperature variation sequence and the second target hotspot temperature corresponding to the second axial temperature variation sequence are classified into the same target hotspot temperature set.

[0045] In this embodiment, by obtaining the temperature value of each target feature point and subtracting the temperature values ​​of two adjacent target feature points, at least one axial temperature change value is obtained, and at least one axial temperature change value is sorted based on the position order of the feature points to obtain an axial temperature change sequence, so that the axial temperature change of the cable conductor connected to the cable joint can be obtained. And by calculating the temperature change degree of the two axial temperature change sequences, the cable conductors with the same temperature change or similar temperature change can be clustered as much as possible. Since the temperature change of the cable conductor is also affected by the temperature of the cable joint, after the cable conductors with the same temperature change or similar temperature change are clustered, the temperature clustering of the cable joint can be achieved as much as possible.

[0046] And because the temperature of the characteristic point of the cable conductor that is closer to the cable joint is more affected, by setting an arithmetically increasing temperature weight in the expression of temperature change, the proportion of the temperature influence of the cable joint on the cable conductor can be increased, thereby further improving the accuracy of the target hot spot temperature clustering of the cable joint.

[0047] For example, in the first axial temperature change sequence, the first axial temperatures along the direction away from the cable joint are 50°C, 48°C, 46°C and 42°C respectively; in the second axial temperature change sequence, the first axial temperatures along the direction away from the cable joint are 50°C, 45°C, 43°C and 40°C respectively; the temperature weights are 0.1, 0.2, 0.3 and 0.4 respectively.

[0048] The temperature variation degrees of the first axial temperature variation sequence and the second axial temperature variation sequence are calculated to be (50-50) / 0.1+(48-45) / 0.2+(46-43) / 0.3+(42-40) / 0.4=30.

[0049] For another example, in the first axial temperature change sequence, the first axial temperature along the direction away from the cable connector is 50°C, 48°C, 46°C and 42°C respectively; in the second axial temperature change sequence, the first axial temperature along the direction away from the cable connector is 50°C, 48°C, 43°C and 40°C respectively; the temperature weights are 0.1, 0.2, 0.3 and 0.4 respectively.

[0050] The temperature variation degrees of the first axial temperature variation sequence and the second axial temperature variation sequence are calculated to be (50-50) / 0.1+(48-48) / 0.2+(46-43) / 0.3+(42-40) / 0.4=15.

[0051] Step S106, select a target hotspot temperature from each target hotspot temperature set according to a preset selection rule, define the target hotspot temperature as a first suspected target hotspot temperature, and compare each first suspected target hotspot temperature to obtain a first comparison result, and determine whether a first suspected target hotspot temperature is abnormal based on the first comparison result.

[0052] In this step, the temperature variation degree between the axial temperature variation sequences corresponding to any two target hotspot temperatures in a certain target hotspot temperature set is calculated to obtain a temperature variation degree set, wherein one target hotspot temperature corresponds to one axial temperature variation sequence; the target temperature variation degree with the smallest value is selected in the temperature variation degree set, and the first target hotspot temperature and the second target hotspot temperature corresponding to the target temperature variation degree are determined; the first target hotspot temperature is defined as the first suspected target hotspot temperature, that is, different first suspected target hotspot temperatures of different target hotspot temperature sets are obtained, wherein the value of the first target hotspot temperature is less than the value of the second target hotspot temperature; a two-dimensional coordinate system is constructed with the first suspected target hotspot temperature as the horizontal coordinate and the target temperature variation degree corresponding to the first suspected target hotspot temperature as the vertical coordinate, and each first suspected target hotspot temperature is set in the two-dimensional coordinate system to obtain each first coordinate point, wherein one first coordinate point corresponds to one first suspected target hotspot temperature; it is determined whether a certain coordinate point is a first isolated coordinate point in the two-dimensional coordinate system, wherein a coordinate point whose distance from the first central coordinate point is greater than a preset distance threshold is defined as a first isolated coordinate point, and the first central coordinate point is obtained by clustering all the first coordinate points in the coordinate system.

[0053] It should be noted that the target temperature variation is the temperature variation with the smallest value selected from the temperature variation set. By constructing a two-dimensional coordinate system with the first suspected target hotspot temperature as the horizontal coordinate and the target temperature variation corresponding to the first suspected target hotspot temperature as the vertical coordinate, and converting the first suspected target hotspot temperature and the target temperature variation corresponding to the first suspected target hotspot temperature into coordinate points, isolated coordinate points can be determined more intuitively. When isolated coordinate points exist, it may be that the first suspected target hotspot temperature is significantly different from other suspected target hotspot temperatures, and the target temperature variation corresponding to the first suspected target hotspot temperature is also different from the target temperature variation corresponding to other suspected target hotspot temperatures, thus generating the isolated coordinate point.

[0054] In a specific embodiment, if the temperature of a first suspected target hotspot is not abnormal, it is determined that the cable joint corresponding to the second suspected target hotspot temperature may not have an overheating risk.

[0055] Step S107, if a certain first suspected target hotspot temperature is abnormal, then reselect another target hotspot temperature from a certain target hotspot temperature set where the certain first suspected target hotspot temperature is located, define the other target hotspot temperature as a second suspected target hotspot temperature, and compare the second suspected target hotspot temperature with other first suspected target hotspot temperatures to obtain a second comparison result, and determine whether the second suspected target hotspot temperature is abnormal based on the second comparison result.

[0056] In this step, the second target hotspot temperature is defined as the second doubtful target hotspot temperature; the second doubtful target hotspot temperature is set in the two-dimensional coordinate system to obtain a second coordinate point; it is determined whether the second coordinate point is a second isolated coordinate point in the two-dimensional coordinate system, wherein a coordinate point whose distance from the second central coordinate point is greater than a preset distance threshold is defined as an isolated coordinate point, and the second central coordinate point is obtained by clustering the second central coordinate point and all the first coordinate points in the coordinate system. For example, the second central coordinate point can be clustered by an existing clustering method to obtain a cluster center, such as a K-Means clustering method.

[0057] In a specific embodiment, if the second suspected target hotspot temperature is not abnormal, it is determined that the cable joint corresponding to the second suspected target hotspot temperature may not have an overheating risk.

[0058] Step S108: if the second suspected target hot spot temperature is abnormal, it is determined that the cable connectors corresponding to the respective target hot spot temperatures in the target hot spot temperature set are all at risk of overheating.

[0059] In this step, when the first target hotspot temperature and the second target hotspot temperature corresponding to the target temperature variation degree with the smallest numerical value are both abnormal, then the target hotspot temperatures corresponding to other temperature variation degrees with larger numerical values ​​than the target temperature variation degree are more likely to be abnormal. Therefore, it is directly determined that the cable joints corresponding to each target hotspot temperature in a certain target hotspot temperature set may have overheating risks, which can effectively improve the troubleshooting efficiency while ensuring the accuracy of the overheating risk analysis as much as possible.

[0060] In summary, compared with the prior art method of directly clustering different cable joints within the same target hotspot temperature range (for example, multiple cable joints that are affected by different ambient temperatures but have similar target hotspot temperatures are simply clustered into the same set), the method of the present application clusters the target hotspot temperatures of different cable joints based on each axial temperature change sequence to obtain at least one target hotspot temperature set, and can cluster cable joints with the same potential risks into the same set as much as possible, thereby improving the accuracy of clustering and facilitating the subsequent overheating risk analysis of each cable joint in the set. In addition, by defining a two-dimensional coordinate system with the first suspected target hotspot temperature as the horizontal coordinate and the target temperature change degree corresponding to the first suspected target hotspot temperature as the vertical coordinate, it is possible to quickly screen out whether there are isolated coordinate points, thereby determining that the cable joint corresponding to the first suspected target hotspot temperature or the second suspected target hotspot temperature corresponding to the isolated coordinate point may have an overheating risk, thereby effectively improving the efficiency of overheating risk analysis.

[0061] See also Figure 3 , which shows a structural block diagram of an overheating fault analysis system for a cable connector of the present application.

[0062] like Figure 3 As shown, the overheating fault analysis system 200 includes a solution module 210 , an inversion module 220 , a correction module 230 , a judgment module 240 , a clustering module 250 , a first comparison module 260 , a second comparison module 270 and a determination module 280 .

[0063] Among them, the solution module 210 is configured to obtain the load current of the cable body and the temperature of at least one surface feature point of the cable body, and input the load current and the temperature of at least one surface feature point into a preset body transient thermal circuit model, solve the body transient thermal circuit model to obtain the characteristic point temperature distribution of the cable conductor in the cable body; the inversion module 220 is configured to obtain the inversion hotspot temperature of the cable joint connected to the cable body by using a preset cable joint axial fitting function according to the characteristic point temperature distribution; the correction module 230 is configured to obtain the measured hotspot temperature of the cable joint, and according to the inversion hotspot temperature, use a preset temperature correction strategy to correct the measured hotspot temperature to obtain the target hotspot temperature; the judgment module 240 is configured to judge whether the target hotspot temperature is greater than a first preset temperature threshold; the clustering module 250 is configured to determine the axial temperature change sequence of the cable conductor in different cable bodies according to the characteristic point temperature distribution of the cable conductor in different cable bodies if it is not greater than the first preset temperature threshold, and cluster the target hotspot temperatures of different cable joints based on each axial temperature change sequence. The first comparison module 260 is configured to select a target hotspot temperature from each target hotspot temperature set according to a preset selection rule, define the target hotspot temperature as a first suspected target hotspot temperature, and compare each first suspected target hotspot temperature to obtain a first comparison result, and determine whether a first suspected target hotspot temperature is abnormal according to the first comparison result; the second comparison module 270 is configured to reselect another target hotspot temperature from a target hotspot temperature set where the first suspected target hotspot temperature is located if the first suspected target hotspot temperature is abnormal, define the other target hotspot temperature as a second suspected target hotspot temperature, and compare the second suspected target hotspot temperature with other first suspected target hotspot temperatures to obtain a second comparison result, and determine whether the second suspected target hotspot temperature is abnormal according to the second comparison result; the determination module 280 is configured to determine that if the second suspected target hotspot temperature is abnormal, the cable joints corresponding to each target hotspot temperature in the target hotspot temperature set are all at risk of overheating.

[0064] It should be understood that Figure 3 Modules and references documented in Figure 1 Therefore, the operations and features described above for the method and the corresponding technical effects are also applicable to Figure 3 The modules in it will not be described in detail here.

[0065] In some other embodiments, the embodiments of the present invention further provide a computer-readable storage medium having a computer program stored thereon, wherein when the program instructions are executed by a processor, the processor is caused to execute the overheating fault analysis method of a cable connector in any of the above method embodiments; As an implementation mode, the computer-readable storage medium of the present invention stores computer-executable instructions, and the computer-executable instructions are configured as follows: Obtaining a load current of a cable body and a temperature of at least one surface characteristic point of the cable body, and inputting the load current and the temperature of at least one surface characteristic point into a preset body transient thermal circuit model, solving the body transient thermal circuit model to obtain a characteristic point temperature distribution of a cable conductor in the cable body; According to the characteristic point temperature distribution, a preset cable joint axial fitting function is used to invert and obtain an inverted hot spot temperature of the cable joint connected to the cable body; Obtaining the measured hot spot temperature of the cable joint, and correcting the measured hot spot temperature using a preset temperature correction strategy according to the inverted hot spot temperature to obtain a target hot spot temperature; Determining whether the target hot spot temperature is greater than a first preset temperature threshold; If it is not greater than the first preset temperature threshold, determining the axial temperature change sequence of the cable conductors in the different cable bodies according to the temperature distribution of the characteristic points of the cable conductors in the different cable bodies, and clustering the target hot spot temperatures of the different cable joints based on each axial temperature change sequence to obtain at least one target hot spot temperature set; Selecting a target hotspot temperature from each target hotspot temperature set according to a preset selection rule, defining the target hotspot temperature as a first suspected target hotspot temperature, and comparing each first suspected target hotspot temperature to obtain a first comparison result, and determining whether a first suspected target hotspot temperature is abnormal according to the first comparison result; If a first suspected target hotspot temperature is abnormal, reselect another target hotspot temperature from a target hotspot temperature set where the first suspected target hotspot temperature is located, define the other target hotspot temperature as a second suspected target hotspot temperature, and compare the second suspected target hotspot temperature with other first suspected target hotspot temperatures to obtain a second comparison result, and determine whether the second suspected target hotspot temperature is abnormal according to the second comparison result; If the second suspected target hot spot temperature is abnormal, it is determined that the cable connectors corresponding to the respective target hot spot temperatures in the certain target hot spot temperature set all have overheating risks.

[0066] The computer-readable storage medium may include a program storage area and a data storage area, wherein the program storage area may store an operating system and an application required by at least one function; the data storage area may store data created according to the use of the overheating fault analysis system of the cable connector, etc. In addition, the computer-readable storage medium may include a high-speed random access memory, and may also include a memory, such as at least one disk storage device, a flash memory device, or other non-volatile solid-state storage device. In some embodiments, the computer-readable storage medium may optionally include a memory remotely arranged relative to the processor, and these remote memories may be connected to the overheating fault analysis system of the cable connector via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0067] Figure 4 is a schematic diagram of the structure of an electronic device provided by an embodiment of the present invention, such as Figure 4 As shown, the device includes: a processor 310 and a memory 320. The electronic device may also include: an input device 330 and an output device 340. The processor 310, the memory 320, the input device 330 and the output device 340 may be connected via a bus or other means. Figure 4 In the example, the bus connection is used. The memory 320 is the computer-readable storage medium mentioned above. The processor 310 executes various functional applications and data processing of the server by running the non-volatile software programs, instructions and modules stored in the memory 320, that is, the overheating fault analysis method of the cable connector in the above method embodiment is realized. The input device 330 can receive input digital or character information, and generate key signal input related to user settings and function control of the overheating fault analysis system of the cable connector. The output device 340 may include display devices such as a display screen.

[0068] The electronic device can execute the method provided by the embodiment of the present invention, and has the functional modules and beneficial effects corresponding to the execution method. For technical details not described in detail in this embodiment, please refer to the method provided by the embodiment of the present invention.

[0069] As an implementation mode, the electronic device is applied to an overheating fault analysis system of a cable connector, and is used for a client, and includes: at least one processor; and a memory connected to the at least one processor in communication; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can: Obtaining a load current of a cable body and a temperature of at least one surface characteristic point of the cable body, and inputting the load current and the temperature of at least one surface characteristic point into a preset body transient thermal circuit model, solving the body transient thermal circuit model to obtain a characteristic point temperature distribution of a cable conductor in the cable body; According to the characteristic point temperature distribution, a preset cable joint axial fitting function is used to invert and obtain an inverted hot spot temperature of the cable joint connected to the cable body; Obtaining the measured hot spot temperature of the cable joint, and correcting the measured hot spot temperature using a preset temperature correction strategy according to the inverted hot spot temperature to obtain a target hot spot temperature; Determining whether the target hot spot temperature is greater than a first preset temperature threshold; If it is not greater than the first preset temperature threshold, determining the axial temperature change sequence of the cable conductors in the different cable bodies according to the temperature distribution of the characteristic points of the cable conductors in the different cable bodies, and clustering the target hot spot temperatures of the different cable joints based on each axial temperature change sequence to obtain at least one target hot spot temperature set; Selecting a target hotspot temperature from each target hotspot temperature set according to a preset selection rule, defining the target hotspot temperature as a first suspected target hotspot temperature, and comparing each first suspected target hotspot temperature to obtain a first comparison result, and determining whether a first suspected target hotspot temperature is abnormal according to the first comparison result; If a first suspected target hotspot temperature is abnormal, reselect another target hotspot temperature from a target hotspot temperature set where the first suspected target hotspot temperature is located, define the other target hotspot temperature as a second suspected target hotspot temperature, and compare the second suspected target hotspot temperature with other first suspected target hotspot temperatures to obtain a second comparison result, and determine whether the second suspected target hotspot temperature is abnormal according to the second comparison result; If the second suspected target hot spot temperature is abnormal, it is determined that the cable connectors corresponding to the respective target hot spot temperatures in the certain target hot spot temperature set all have overheating risks.

[0070] Through the description of the above implementation modes, those skilled in the art can clearly understand that each implementation mode can be implemented by means of software plus a necessary general hardware platform, or of course by hardware. Based on such an understanding, the above technical solution can essentially or in other words be embodied in the form of a software product that contributes to the prior art. The computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a magnetic disk, an optical disk, etc., and includes a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods of each embodiment or some parts of the embodiment.

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for analyzing overheating failure of a cable joint, characterized in that: include: Obtaining a load current of a cable body and a temperature of at least one surface characteristic point of the cable body, and inputting the load current and the temperature of at least one surface characteristic point into a preset body transient thermal circuit model, solving the body transient thermal circuit model to obtain a characteristic point temperature distribution of a cable conductor in the cable body; According to the characteristic point temperature distribution, a preset cable joint axial fitting function is used to invert and obtain an inverted hot spot temperature of the cable joint connected to the cable body; Obtaining the measured hot spot temperature of the cable joint, and correcting the measured hot spot temperature using a preset temperature correction strategy according to the inverted hot spot temperature to obtain a target hot spot temperature; Determining whether the target hot spot temperature is greater than a first preset temperature threshold; If it is not greater than the first preset temperature threshold, determining the axial temperature change sequence of the cable conductors in the different cable bodies according to the temperature distribution of the characteristic points of the cable conductors in the different cable bodies, and clustering the target hot spot temperatures of the different cable joints based on each axial temperature change sequence to obtain at least one target hot spot temperature set; Selecting a target hotspot temperature from each target hotspot temperature set according to a preset selection rule, defining the target hotspot temperature as a first suspected target hotspot temperature, and comparing each first suspected target hotspot temperature to obtain a first comparison result, and determining whether a first suspected target hotspot temperature is abnormal according to the first comparison result; If a first suspected target hotspot temperature is abnormal, reselect another target hotspot temperature from a target hotspot temperature set where the first suspected target hotspot temperature is located, define the other target hotspot temperature as a second suspected target hotspot temperature, and compare the second suspected target hotspot temperature with other first suspected target hotspot temperatures to obtain a second comparison result, and determine whether the second suspected target hotspot temperature is abnormal according to the second comparison result; If the second suspected target hot spot temperature is abnormal, it is determined that the cable connectors corresponding to the respective target hot spot temperatures in the certain target hot spot temperature set all have overheating risks.

2. The overheating fault analysis method of a cable joint according to claim 1, characterized in that: The expression of the cable joint axial fitting function is: ， In the formula, is the inverted hot spot temperature of the jth cable joint, is the conductor temperature of the first characteristic point, which is 0.1 m away from the end of the jth cable connector. is the conductor temperature of the second characteristic point, and the second characteristic point is 2.0 m away from the end of the j-th cable connector; The method of obtaining the inverted hot spot temperature of the cable joint connected to the cable body by inverting the temperature distribution of the characteristic point using a preset cable joint axial fitting function comprises: Selecting the conductor temperature of the first characteristic point and the conductor temperature of the second characteristic point in the characteristic point temperature distribution respectively; The conductor temperature of the first characteristic point and the conductor temperature of the second characteristic point are input into the cable joint axial fitting function to solve and obtain the inverse hot spot temperature of the cable joint connected to the cable body.

3. The overheating fault analysis method of a cable joint according to claim 1, characterized in that: The method of correcting the measured hotspot temperature using a preset temperature correction strategy according to the inverted hotspot temperature to obtain a target hotspot temperature includes: Calculating the temperature difference between the inverted hotspot temperature and the measured hotspot temperature; Determining whether the absolute value of the temperature difference is greater than a second preset temperature threshold; If it is not greater than a second preset temperature threshold, taking an average of the inverted hotspot temperature and the measured hotspot temperature to obtain a target hotspot temperature; If it is greater than the second preset temperature threshold, the inversion hotspot temperature is corrected according to the temperature difference and the second preset temperature threshold to obtain the target hotspot temperature, wherein the expression for correcting the inversion hotspot temperature according to the temperature difference and the second preset temperature threshold is: ， In the formula, is the target hot spot temperature, To invert the hotspot temperature, is the temperature difference between the inverted hotspot temperature and the measured hotspot temperature, is the second preset temperature threshold.

4. The overheating fault analysis method of a cable joint according to claim 1, characterized in that: After determining whether the target hotspot temperature is greater than a preset temperature threshold, the method further includes: If it is greater than a preset temperature threshold, it is directly determined that the cable connector corresponding to the target hot spot temperature has an overheating fault.

5. The overheating fault analysis method of a cable joint according to claim 1, characterized in that: The step of determining the axial temperature variation sequence of the cable conductors in different cable bodies according to the temperature distribution of the characteristic points of the cable conductors in different cable bodies, and clustering the target hotspot temperatures of different cable joints based on each axial temperature variation sequence to obtain at least one target hotspot temperature set includes: Determine the position of each characteristic point of the cable conductor in the cable body along the cable axis direction to obtain a characteristic point position sequence, wherein the position spacing between two adjacent characteristic points in the characteristic point position sequence is the same; According to the dynamic sliding step length, a preset first sliding window is used to slide on the feature point position sequence, and each time the sliding occurs, the feature point in the first sliding window is defined as a target feature point, wherein the window size of the first sliding window is the same as the size of a target feature point, and the dynamic sliding step length increases with the number of sliding times; Acquire the temperature value of each target feature point, and make a difference between the temperature values ​​of two adjacent target feature points to obtain at least one axial temperature change value, and sort the at least one axial temperature change value based on the position sequence of the feature points to obtain an axial temperature change sequence; According to the preset temperature weight, the temperature variation degree between the first axial temperature variation sequence and the second axial temperature variation sequence is calculated, and it is determined whether the temperature variation degree is greater than a preset threshold value, wherein the first axial temperature variation sequence and the second axial temperature variation sequence are any two axial temperature variation sequences, and the expression for calculating the temperature variation degree is: ， In the formula, is the temperature variation between the first axial temperature variation sequence and the second axial temperature variation sequence, is the first axial temperature change value in the first axial temperature change sequence, is the first second axial temperature change value in the second axial temperature change sequence, is the second first axial temperature change value in the first axial temperature change sequence, is the second second axial temperature change value in the second axial temperature change sequence, is the Nth first axial temperature change value in the first axial temperature change sequence, is the Nth second axial temperature change value in the second axial temperature change sequence, for The temperature weight, for The temperature weight, for The temperature weight, ,and , , …, Increasing in an arithmetic progression; If the temperature variation is greater than a preset threshold, the first target hotspot temperature corresponding to the first axial temperature variation sequence and the second target hotspot temperature corresponding to the second axial temperature variation sequence are not classified into the same target hotspot temperature set; If the temperature variation is not greater than a preset threshold, the first target hotspot temperature corresponding to the first axial temperature variation sequence and the second target hotspot temperature corresponding to the second axial temperature variation sequence are classified into the same target hotspot temperature set.

6. A cable joint overheating fault analysis method according to claim 5, characterized in that: The step of selecting a target hotspot temperature from each target hotspot temperature set according to a preset selection rule, defining the target hotspot temperature as a first suspected target hotspot temperature, and comparing each first suspected target hotspot temperature to obtain a first comparison result, and determining whether a first suspected target hotspot temperature is abnormal according to the first comparison result includes: Calculate the temperature variation between the axial temperature variation sequences corresponding to any two target hot spot temperatures in a certain target hot spot temperature set to obtain a temperature variation set, wherein one target hot spot temperature corresponds to one axial temperature variation sequence; Selecting a target temperature variation degree with the smallest value in the temperature variation degree set, and determining a first target hotspot temperature and a second target hotspot temperature corresponding to the target temperature variation degree; The first target hotspot temperature is defined as the first doubtful target hotspot temperature, that is, different first doubtful target hotspot temperatures of different target hotspot temperature sets are obtained, wherein the value of the first target hotspot temperature is less than the value of the second target hotspot temperature; A two-dimensional coordinate system is constructed with the first doubtful target hotspot temperature as the abscissa and the target temperature change degree corresponding to the first doubtful target hotspot temperature as the ordinate, and each first doubtful target hotspot temperature is set in the two-dimensional coordinate system to obtain each first coordinate point, wherein one first coordinate point corresponds to one first doubtful target hotspot temperature; Determine whether a certain coordinate point is a first isolated coordinate point in the two-dimensional coordinate system, wherein a coordinate point whose distance from a first central coordinate point is greater than a preset distance threshold is defined as a first isolated coordinate point, and the first central coordinate point is obtained by clustering all first coordinate points in the coordinate system.

7. A cable joint overheating fault analysis method according to claim 6, characterized in that: The step of reselecting another target hotspot temperature from a target hotspot temperature set where the first questionable target hotspot temperature is located, defining the another target hotspot temperature as a second questionable target hotspot temperature, and comparing the second questionable target hotspot temperature with other first questionable target hotspot temperatures to obtain a second comparison result, and determining whether the second questionable target hotspot temperature is abnormal according to the second comparison result includes: defining the second target hot spot temperature as a second questionable target hot spot temperature; Setting the second questionable target hot spot temperature in the two-dimensional coordinate system to obtain a second coordinate point; Determine whether the second coordinate point is a second isolated coordinate point in the two-dimensional coordinate system, wherein a coordinate point whose distance from the second center coordinate point is greater than a preset distance threshold is defined as an isolated coordinate point, and the second center coordinate point is obtained by clustering the second center coordinate point and all the first coordinate points in the coordinate system.

8. A cable joint overheating fault analysis system, characterized in that: include: A solution module is configured to obtain a load current of a cable body and a temperature of at least one surface characteristic point of the cable body, and input the load current and the temperature of at least one surface characteristic point into a preset body transient thermal circuit model, and solve the body transient thermal circuit model to obtain a characteristic point temperature distribution of a cable conductor in the cable body; An inversion module is configured to obtain an inversion hotspot temperature of a cable joint connected to the cable body by using a preset cable joint axial fitting function according to the characteristic point temperature distribution; A correction module is configured to obtain the measured hot spot temperature of the cable joint, and according to the inverted hot spot temperature, correct the measured hot spot temperature using a preset temperature correction strategy to obtain a target hot spot temperature; A judgment module, configured to judge whether the target hot spot temperature is greater than a first preset temperature threshold; A clustering module is configured to determine the axial temperature change sequence of the cable conductors in different cable bodies according to the temperature distribution of the characteristic points of the cable conductors in different cable bodies if the temperature is not greater than the first preset temperature threshold, and cluster the target hot spot temperatures of different cable joints based on each axial temperature change sequence to obtain at least one target hot spot temperature set; A first comparison module is configured to select a target hotspot temperature from each target hotspot temperature set according to a preset selection rule, define the target hotspot temperature as a first suspected target hotspot temperature, and compare each first suspected target hotspot temperature to obtain a first comparison result, and determine whether a first suspected target hotspot temperature is abnormal according to the first comparison result; A second comparison module is configured to, if a first suspected target hotspot temperature is abnormal, reselect another target hotspot temperature from a target hotspot temperature set where the first suspected target hotspot temperature is located, define the other target hotspot temperature as a second suspected target hotspot temperature, and compare the second suspected target hotspot temperature with other first suspected target hotspot temperatures to obtain a second comparison result, and determine whether the second suspected target hotspot temperature is abnormal according to the second comparison result; The determination module is configured to determine that if the second suspected target hot spot temperature is abnormal, the cable connectors corresponding to the respective target hot spot temperatures in the certain target hot spot temperature set are all at risk of overheating.

9. An electronic device, characterized in that: include: At least one processor, and a memory communicatively connected to the at least one processor, wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to execute the method described in any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the method according to any one of claims 1 to 7 is implemented.

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