Oil-filled cable terminal oil leakage analysis method and system, medium and product

Abstract

The invention discloses an oil-filled cable terminal oil leakage analysis method and system, a medium and a product, and relates to the field of electric digital data processing. According to the application, the detection system collects the temperature value of each sensor according to the sensor array longitudinally arranged at the inner side of the oil-filled cable terminal closed structure and calculates the temperature difference sequence so as to extract the temperature field characteristic parameters in the closed structure. And the detection system corrects the finite element simulation result by combining the current environment temperature and the current load current to obtain the corresponding relation of the oil leakage temperature under the actual working condition, so that the oil leakage condition under the actual working condition is accurately reflected. According to the oil leakage analysis method based on the corresponding relation between the temperature field characteristic parameters and the actual working condition oil leakage temperature, the limitation that detection only depends on an oil level gauge and a float switch in a traditional detection method is avoided, the slow leakage sensing capacity and quantitative analysis precision are improved, oil leakage hidden dangers can be accurately found in time, accidents are prevented, and the oil leakage detection efficiency is improved. And the accuracy and the reliability of oil leakage detection are improved.

Description

Technical Field

[0001] This application relates to the field of electrical digital data processing, and particularly to an oil-filled cable terminal oil leakage analysis method, system, medium and product. Background Art

[0002] The oil-filled cable terminal is an important connecting device in the power system, and its operation reliability is directly related to the stable power supply of the entire power system. The insulating oil inside the oil-filled cable terminal is the key medium to ensure the normal operation of the charging cable terminal. Once an oil leakage fault occurs, it will seriously affect the insulation performance of the oil-filled cable terminal and may even lead to power system operation accidents.

[0003] Currently, the oil leakage monitoring method for oil-filled cable terminals mainly obtains the internal pressure change through a pressure monitoring device, and indirectly judges whether there is an oil leakage fault. When the internal pressure value is lower than the preset pressure threshold, an alarm signal is sent.

[0004] This traditional detection method has the problem of low detection accuracy. Since the oil leakage of the oil-filled cable terminal often has the characteristic of slow leakage, the change in the oil level is very small, and it is difficult for the oil level gauge and the float switch to detect this subtle change in time, resulting in the inability to guarantee the accuracy and timeliness of the oil leakage detection result. Summary of the Invention

[0005] This application provides an oil-filled cable terminal oil leakage analysis method, system, medium and product, which is used to improve the accuracy of oil leakage detection of oil-filled cable terminals.

[0006] In a first aspect, this application provides an oil-filled cable terminal oil leakage analysis method, which is applied to a detection system. The method includes: collecting the temperature values of each sensor through a sensor array longitudinally arranged along the inner side of the closed structure of the oil-filled cable terminal, and calculating the temperature difference between adjacent sensors to obtain a temperature difference sequence. The sensor array includes a first sensor to an Nth sensor arranged in sequence from top to bottom; determining temperature field characteristic parameters according to the temperature difference sequence, where the temperature field characteristic parameters include the maximum temperature difference value, the maximum temperature difference position, the average temperature difference, the change rate of adjacent temperature differences, and the standard deviation of temperature differences in the temperature difference sequence; calculating an ambient temperature correction coefficient and a load current correction coefficient according to the current ambient temperature, the current load current, the preset reference ambient temperature, and the preset reference load current to correct the finite element simulation result and obtain the actual working condition oil leakage temperature correspondence. The finite element simulation result refers to the different temperature field distributions corresponding to different oil leakage degrees determined by the finite element simulation method under the preset reference ambient temperature and the preset reference load current; determining the current oil leakage degree of the oil-filled cable terminal based on the temperature field characteristic parameters and the actual working condition oil leakage temperature correspondence.

[0007] By adopting the above technical solution, the detection system collects the temperature values of each sensor according to the sensor array longitudinally arranged along the inner side of the closed structure of the oil-filled cable terminal, calculates the temperature difference sequence, and extracts the characteristic parameters of the temperature field in the closed structure. The detection system combines the current ambient temperature and the current load current to correct the finite element simulation results, and obtains the corresponding relationship between the oil leakage temperature under the actual working conditions, so as to accurately reflect the oil leakage situation under the actual working conditions. This oil leakage analysis method based on the characteristic parameters of the temperature field and the corresponding relationship between the oil leakage temperature under the actual working conditions avoids the limitations of only relying on the oil level gauge and the float switch detection in the traditional detection method, improves the perception ability of slow leakage and the quantization analysis accuracy, can timely and accurately detect the oil leakage hidden danger, prevent accidents from occurring, and improves the accuracy and reliability of oil leakage detection.

[0008] Combined with some embodiments of the first aspect, in some embodiments, before the step of calculating the ambient temperature correction coefficient and the load current correction coefficient according to the current ambient temperature, the current load current, the preset reference ambient temperature, and the preset reference load current to correct the finite element simulation results and obtain the corresponding relationship between the oil leakage temperature under the actual working conditions, the method further includes: establishing a three-dimensional model of the oil-filled cable terminal, the three-dimensional model of the oil-filled cable terminal includes a conductor and a closed structure, the closed structure includes an insulating oil chamber and an air domain located above the insulating oil chamber, and a sensor array is longitudinally arranged along the inner side of the closed structure; setting a heat source boundary condition on the surface of the conductor, setting a convective heat transfer boundary condition on the outer surface of the sealing structure, and setting a radiative heat transfer boundary condition on the outer surface of the sealing structure to obtain an oil-filled cable terminal model, the heat source boundary condition is determined by the preset reference load current, and the convective heat transfer boundary condition and the radiative heat transfer boundary condition are determined by the preset reference ambient temperature; performing finite element simulation on the oil-filled cable terminal under different air domain heights to obtain different temperature field distributions corresponding to different oil leakage degrees under the preset reference ambient temperature and the preset reference load current, the air domain height is used to characterize the oil leakage degree, and the higher the air domain height, the more serious the oil leakage degree.

[0009] By adopting the above technical solution, the detection system establishes a three-dimensional model of the oil-filled cable terminal including a conductor and a closed structure, and sets a heat source boundary condition, a convective heat transfer boundary condition, and a radiative heat transfer boundary condition in the three-dimensional model of the oil-filled cable terminal, so as to more realistically simulate the temperature field distribution of the oil-filled cable terminal. The detection system uses the air domain height to characterize the oil leakage degree, obtains different temperature field distributions under different oil leakage degrees through finite element simulation, and establishes the corresponding relationship between the oil leakage degree and the temperature field characteristics. This simulation analysis method based on the physical model provides a reliable theoretical basis for oil leakage detection and improves the scientificity of oil leakage degree judgment.

[0010] Combined with some embodiments of the first aspect, in some embodiments, the heat source boundary condition is: ; where Q is the heat source of the oil-filled cable terminal, P is the heating power of the conductor, is the lateral area of the conductor, I is the preset reference load current flowing through the conductor, is the cross-sectional area of the conductor, ρ is the resistivity of the conductor, l is the length of the conductor; the convective heat transfer boundary condition is: ; where λ is the thermal conductivity of the insulating material in the closed structure, is the temperature gradient, is the surface area of the oil-filled cable terminal, h is the heat transfer coefficient of the outer surface of the oil-filled cable terminal in contact with air, is the surface temperature of the oil-filled cable terminal, is the preset reference ambient temperature; the radiative heat transfer boundary condition is: ; in the formula, is the Stefan-Boltzmann constant, is the surface emissivity.

[0011] By adopting the above technical solution, the detection system details the specific mathematical expressions of the heat source boundary condition, the convective heat transfer boundary condition and the radiative heat transfer boundary condition, and takes into account multiple physical parameters such as the heating power of the conductor, the thermal conductivity of the insulating material in the closed structure, and the heat transfer coefficient of the outer surface of the oil-filled cable terminal in contact with air. The accurate description of these boundary conditions makes the finite element simulation closer to the actual working conditions and improves the accuracy of the temperature field distribution calculation.

[0012] Combined with some embodiments of the first aspect, in some embodiments, according to the current ambient temperature, the current load current, the preset reference ambient temperature and the preset reference load current, the ambient temperature correction coefficient and the load current correction coefficient are calculated to correct the finite element simulation result to obtain the corresponding relationship between the oil leakage temperature under the actual working conditions, specifically including: determining the ratio of the current ambient temperature to the preset reference ambient temperature as the ambient temperature correction coefficient, and determining the square ratio of the current load current to the preset reference load current as the load current correction coefficient; multiplying the temperature field distribution in the finite element simulation result by the products of the ambient temperature correction coefficient and the load current correction coefficient respectively to obtain the corrected temperature field distribution; establishing the corresponding relationship between different oil leakage degrees and different corrected temperature field distributions to obtain the corresponding relationship between the oil leakage temperature under the actual working conditions.

[0013] By adopting the above technical solution, the detection system corrects the finite element simulation result according to the ambient temperature correction coefficient and the load current correction coefficient, takes into account the influence of the ambient temperature and the load current on the temperature field distribution, can convert the simulation result under the standard working conditions into the temperature distribution characteristics under the actual working conditions, so as to establish the corresponding relationship between different oil leakage degrees and different corrected temperature field distributions, accurately evaluate the oil leakage state under the actual operating conditions, and improve the adaptability and accuracy of the oil leakage detection.

[0014] In combination with some embodiments of the first aspect, in some embodiments, after the step of determining the current oil leakage degree of the oil-filled cable terminal based on the temperature field characteristic parameters and the corresponding relationship between the actual working condition oil leakage temperature, the method further includes: within a preset time period, periodically obtaining multiple sets of temperature field characteristic parameters, and determining the ambient temperature, load current, and oil leakage degree corresponding to each of the multiple sets of temperature field characteristic parameters, so as to draw an oil leakage development trend curve; determining the slope of the oil leakage development trend curve as the oil leakage rate to judge the stability of the oil leakage development trend; when the oil leakage development trend is unstable, analyzing the correlation between the temperature field characteristic parameters and the ambient temperature and load current; if the correlation exceeds a preset correlation threshold, adjusting the ambient temperature and load current to a preset standard range; if the correlation is less than or equal to the preset correlation threshold, triggering an emergency alarm.

[0015] By adopting the above technical solution, the detection system draws an oil leakage development trend curve and judges the stability of the oil leakage development trend according to the oil leakage rate. If the oil leakage development trend is unstable, then the detection system analyzes the correlation between the temperature field characteristic parameters and the ambient temperature and load current, so as to effectively identify abnormal situations. When the correlation exceeds the preset correlation threshold, the detection system adjusts the ambient temperature and load current to the preset standard range to eliminate the influence of external factors; when the correlation is less than or equal to the preset correlation threshold, it indicates that there is an abnormality inside the oil-filled cable terminal, and an emergency alarm is triggered in a timely manner. This multi-level analysis and processing mechanism can not only prevent false alarms but also timely detect real oil leakage hidden dangers.

[0016] In combination with some embodiments of the first aspect, in some embodiments, after the step of determining the slope of the oil leakage development trend curve as the oil leakage rate to judge the stability of the oil leakage development trend, the method further includes: when the oil leakage development trend is stable, calculating the remaining time to reach a preset oil leakage degree threshold according to the current oil leakage degree and the oil leakage rate; if the remaining time is less than a preset time threshold, generating a maintenance instruction, and the maintenance instruction includes a recommended maintenance time window.

[0017] By adopting the above technical solution, when the oil leakage development trend is stable, the detection system calculates the remaining time to reach a preset oil leakage degree threshold based on the current oil leakage degree and the oil leakage rate, and generates a maintenance instruction including a recommended maintenance time window according to the remaining time. This predictive maintenance plan can help the operation and maintenance personnel reasonably arrange the maintenance plan, which not only avoids the safety hazards caused by the equipment running with diseases but also prevents the waste of resources caused by over-maintenance.

[0018] In combination with some embodiments of the first aspect, in some embodiments, when the development trend of oil leakage is unstable, the correlation degrees of the temperature field characteristic parameters with the ambient temperature and the load current are analyzed. Specifically, it includes: arranging the temperature field characteristic parameters, the ambient temperature, and the load current in chronological order to obtain a temperature field characteristic parameter sequence, an ambient temperature sequence, and a load current sequence; calculating the Pearson correlation coefficient between the temperature field characteristic parameter sequence and the ambient temperature sequence to obtain the ambient temperature correlation degree; calculating the Pearson correlation coefficient between the temperature field characteristic parameter sequence and the load current sequence to obtain the load current correlation degree; and determining the correlation degrees of the temperature field characteristic parameters with the ambient temperature and the load current according to the ambient temperature correlation degree and the load current correlation degree.

[0019] By adopting the above technical solution, the detection system analyzes the correlation between the temperature field characteristic parameters and the ambient temperature and the load current by using the Pearson correlation coefficient, providing an objective and quantitative evaluation method. Calculating the correlation degrees of the temperature field characteristic parameters with the ambient temperature and the load current can accurately identify whether the change in the temperature field is caused by external environmental factors or by real oil leakage, improving the reliability of oil leakage judgment, reducing the false judgment rate, and providing a scientific basis for subsequent taking appropriate treatment measures.

[0020] In a second aspect, an embodiment of the present application provides a detection system, which includes: one or more processors and a memory; the memory is coupled to the one or more processors, and the memory is used to store computer program code, the computer program code includes computer instructions, and the one or more processors call the computer instructions to enable the detection system to execute the method described in the first aspect and any possible implementation manner in the first aspect.

[0021] In a third aspect, an embodiment of the present application provides a computer program product containing instructions, which when the computer program product runs on the detection system, enables the detection system to execute the method described in the first aspect and any possible implementation manner in the first aspect.

[0022] In a fourth aspect, an embodiment of the present application provides a computer-readable storage medium, including instructions, which when the instructions run on the detection system, enables the detection system to execute the method described in the first aspect and any possible implementation manner in the first aspect.

[0023] It can be understood that the detection system provided in the second aspect, the computer program product provided in the third aspect, and the computer storage medium provided in the fourth aspect are all used to execute the method provided in the embodiments of the present application. Therefore, the beneficial effects that can be achieved can refer to the beneficial effects in the corresponding method, and will not be elaborated here.

[0024] One or more technical solutions provided in the embodiments of the present application have at least the following technical effects or advantages: 1. By adopting the above technical solution, the detection system collects the temperature values of each sensor according to the sensor array longitudinally arranged along the inner side of the closed structure of the oil-filled cable terminal, calculates the temperature difference sequence, and extracts the characteristic parameters of the temperature field in the closed structure. The detection system corrects the finite element simulation results by combining the current ambient temperature and the current load current, obtains the corresponding relationship between the oil leakage temperature under the actual working conditions, and thus accurately reflects the oil leakage situation under the actual working conditions. This oil leakage analysis method based on the characteristic parameters of the temperature field and the corresponding relationship between the oil leakage temperature under the actual working conditions avoids the limitations of only relying on the oil level gauge and the float switch detection in the traditional detection method, improves the perception ability and quantitative analysis accuracy of slow leakage, can timely and accurately detect the oil leakage hidden danger, prevent accidents, and improve the accuracy and reliability of oil leakage detection.

[0025] 2. By adopting the above technical solution, the detection system establishes a three-dimensional model of the oil-filled cable terminal including the conductor and the closed structure, and sets the heat source boundary condition, the convective heat transfer boundary condition and the radiative heat transfer boundary condition in the three-dimensional model of the oil-filled cable terminal, so as to more realistically simulate the temperature field distribution of the oil-filled cable terminal. The detection system uses the height of the air domain to characterize the degree of oil leakage, obtains different temperature field distributions under different degrees of oil leakage through finite element simulation, and establishes the corresponding relationship between the degree of oil leakage and the characteristics of the temperature field. This simulation analysis method based on the physical model provides a reliable theoretical basis for oil leakage detection and improves the scientificity of judging the degree of oil leakage.

[0026] 3. By adopting the above technical solution, the detection system corrects the finite element simulation results according to the ambient temperature correction coefficient and the load current correction coefficient, takes into account the influence of the ambient temperature and the load current on the temperature field distribution, can transform the simulation results under the standard working conditions into the temperature distribution characteristics under the actual working conditions, and thus establishes the corresponding relationship between different degrees of oil leakage and different corrected temperature field distributions to accurately evaluate the oil leakage state under the actual operating conditions and improve the adaptability and accuracy of oil leakage detection. Brief Description of the Drawings

[0027] Figure 1 is a schematic flow chart of the oil leakage analysis method for the oil-filled cable terminal in an embodiment of the present application; Figure 2 is another schematic flow chart of the oil leakage analysis method for the oil-filled cable terminal in an embodiment of the present application; Figure 3 is a schematic structural diagram of an entity device of the detection system in an embodiment of the present application. Detailed Embodiment

[0028] The terms used in the following embodiments of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. As used in the specification of this application, the singular forms "a", "an", "the above", "the", and "this" are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used in this application refers to any or all possible combinations including one or more of the listed items.

[0029] Hereinafter, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as implying or suggesting relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the embodiments of this application, unless otherwise specified, the meaning of "a plurality" is two or more.

[0030] The following describes the process of the method provided in this embodiment. Please refer to Figure 1 , which is a schematic flowchart of a method for analyzing oil leakage at the oil-filled cable terminal in the embodiments of this application.

[0031] S101. Collect the temperature values of each sensor through a sensor array longitudinally arranged inside the closed structure of the oil-filled cable terminal, and calculate the temperature difference between adjacent sensors to obtain a temperature difference sequence. The sensor array includes a first sensor to an Nth sensor arranged in sequence from top to bottom; Among them, the oil-filled cable terminal refers to a device for connecting and terminating an oil-filled cable; the closed structure refers to a housing for sealing and protecting the internal components of the oil-filled cable; the sensor array refers to a set of multiple temperature sensors arranged longitudinally; the temperature value refers to the real-time temperature data detected by each sensor; the temperature difference represents the change in temperature between adjacent sensors; the temperature difference sequence refers to a set of temperature difference data arranged in the order of sensor positions; the first sensor to the Nth sensor represent N temperature sensors arranged in sequence from top to bottom, where N is a positive integer greater than 1.

[0032] Specifically, the detection system collects temperature data in real time through a sensor array pre-installed inside the closed structure of the oil-filled cable terminal. The sensors in the sensor array are numbered and evenly distributed in sequence from top to bottom, and each sensor can accurately collect the temperature value at its installation position. After the detection system obtains the temperature values of all sensors, it calculates the temperature difference between each pair of adjacent sensors according to the spatial position order of the sensors. For example, the temperature difference between the second sensor and the first sensor, the temperature difference between the third sensor and the second sensor, and so on until the temperature difference between the Nth sensor and the (N - 1)th sensor, thereby forming a complete temperature difference sequence.

[0033] Suppose that 5 temperature sensors (N = 5) are uniformly installed longitudinally along the inner side of the sealed structure of an oil-filled cable terminal, and are numbered from 1 to 5 from top to bottom. At a certain moment, the temperature values collected by these 5 sensors are as follows: Sensor No. 1 (the uppermost): 45°C; Sensor No. 2: 47°C; Sensor No. 3: 46°C; Sensor No. 4: 48°C; Sensor No. 5 (the lowermost): 47°C; Then the calculated temperature differences are: Difference between No. 2 and No. 1: 47°C - 45°C = +2°C; Difference between No. 3 and No. 2: 46°C - 47°C = -1°C; Difference between No. 4 and No. 3: 48°C - 46°C = +2°C; Difference between No. 5 and No. 4: 47°C - 48°C = -1°C; In this way, a temperature difference sequence is obtained: [+2, -1, +2, -1].

[0034] S102. According to the temperature difference sequence, determine the temperature field characteristic parameters. The temperature field characteristic parameters include the maximum temperature difference value in the temperature difference sequence, the position of the maximum temperature difference, the average temperature difference, the change rate of adjacent temperature differences, and the standard deviation of temperature differences; Among them, the temperature field characteristic parameters refer to a set of key indicators used to describe the distribution characteristics of the temperature field; the maximum temperature difference value refers to the maximum value in the temperature difference sequence; the position of the maximum temperature difference refers to the position where the maximum temperature difference value appears; the average temperature difference refers to the arithmetic mean of the temperature difference sequence; the change rate of adjacent temperature differences refers to the change speed between adjacent values in the temperature difference sequence; the standard deviation of temperature differences refers to a statistic used to characterize the dispersion degree of the temperature difference sequence.

[0035] Specifically, the detection system performs multi-dimensional analysis on the temperature difference sequence and extracts five key characteristic parameters: First, find the maximum value in the temperature difference sequence and its corresponding sensor position; then calculate the arithmetic mean of the temperature difference sequence; then calculate the change rate between each pair of adjacent temperature differences, that is, the second-order difference of the temperature difference; finally, calculate the standard deviation of the temperature difference sequence, which is used to characterize the uniformity of the temperature distribution. These characteristic parameters together constitute a temperature field characteristic parameter that comprehensively reflects the distribution characteristics of the temperature field and provides basic data support for subsequent oil leakage analysis.

[0036] Continuing with the temperature difference sequence [+2, -1, +2, -1] in the example of step S101 to calculate these characteristic parameters: (1) Maximum temperature difference value: +2°C; (2) Position of the maximum temperature difference (+2°C appears at two positions): Between Sensor 2 and Sensor 1 (the 1st position); Between Sensor 4 and Sensor 3 (the 3rd position); (3) Average temperature difference: (+2 + (-1) + 2 + (-1)) ÷ 4 = 0.5 °C; (4) Rate of change of adjacent temperature differences (second-order difference): First group: (-1) - (+2) = -3; Second group: (+2) - (-1) = +3; Third group: (-1) - (+2) = -3; Obtain the rate-of-change sequence: [-3, +3, -3]; (5) Standard deviation of temperature difference: √[(2 - 0.5)² + (-1 - 0.5)² + (2 - 0.5)² + (-1 - 0.5)²] / 4√(9 / 4) ≈ 1.5 °C; Temperature field characteristic parameters: Maximum temperature difference value: 2 °C; Position of maximum temperature difference: the 1st position and the 3rd position; Average temperature difference: 0.5 °C; Rate-of-change sequence of adjacent temperature differences: [-3, +3, -3]; Standard deviation of temperature difference: 1.5 °C.

[0037] S103. Calculate the ambient temperature correction factor and the load current correction factor according to the current ambient temperature, the current load current, the preset reference ambient temperature, and the preset reference load current, so as to correct the finite element simulation results and obtain the corresponding relationship between the oil leakage temperature under actual working conditions. The finite element simulation results refer to the different temperature field distributions corresponding to different oil leakage degrees determined by using the finite element simulation method under the preset reference ambient temperature and the preset reference load current; Among them, the current ambient temperature refers to the real-time temperature of the environment where the oil-filled cable terminal is located; the current load current refers to the actual current carried by the oil-filled cable terminal at present; the preset reference ambient temperature refers to the standard ambient temperature set during the finite element simulation; the preset reference load current refers to the standard load current set during the finite element simulation; the ambient temperature correction factor refers to the factor used to correct the influence of the ambient temperature; the load current correction factor refers to the factor used to correct the influence of the load current; the finite element simulation results refer to the temperature field distribution data obtained by simulating using the finite element method; the temperature field distribution refers to the distribution of temperatures at each point in space; the corresponding relationship between the oil leakage temperature under actual working conditions refers to the mapping relationship between the oil leakage degree and the temperature field distribution under actual operating conditions.

[0038] Specifically, the detection system acquires the current ambient temperature and the current load current, and compares them with the preset reference ambient temperature and the preset reference load current. When calculating the ambient temperature correction coefficient, divide the current ambient temperature by the preset reference ambient temperature; when calculating the load current correction coefficient, divide the square value of the current load current by the square value of the preset reference load current. The detection system then multiplies the product of these two correction coefficients by the data on the corresponding relationship between the oil leakage degree and the temperature field distribution under standard working conditions obtained by the finite element method in advance to obtain the data on the corresponding relationship between the oil leakage degree and the temperature field distribution under the actual working conditions, that is, the corresponding relationship between the oil leakage temperature under the actual working conditions.

[0039] Optionally, generally, according to the current ambient temperature, the current load current, the preset reference ambient temperature, and the preset reference load current, calculate the ambient temperature correction coefficient and the load current correction coefficient to correct the finite element simulation results, and the corresponding relationship between the oil leakage temperature under the actual working conditions can be achieved in the following ways (not limited here): determine the ratio of the current ambient temperature to the preset reference ambient temperature as the ambient temperature correction coefficient, and determine the square ratio of the current load current to the preset reference load current as the load current correction coefficient; multiply the temperature field distribution in the finite element simulation results by the products of the ambient temperature correction coefficient and the load current correction coefficient respectively to obtain the corrected temperature field distribution; establish the corresponding relationship between different oil leakage degrees and different corrected temperature field distributions to obtain the corresponding relationship between the oil leakage temperature under the actual working conditions.

[0040] Suppose there are the following initial conditions: Current ambient temperature: 25 °C; Preset reference ambient temperature: 20 °C; Current load current: 800 A; Preset reference load current: 500 A; Calculate the correction coefficients: Ambient temperature correction coefficient = 25 °C ÷ 20 °C = 1.25; Load current correction coefficient = (800 A)² ÷ (500 A)² = 2.56; Suppose the data on the corresponding relationship between the oil leakage degree and the temperature field distribution in the finite element simulation under standard working conditions are as follows: Temperature distribution without oil leakage: [40 °C, 42 °C, 41 °C, 43 °C, 42 °C]; Temperature distribution with slight oil leakage: [42 °C, 45 °C, 43 °C, 46 °C, 44 °C]; Temperature distribution with severe oil leakage: [45 °C, 49 °C, 46 °C, 50 °C, 47 °C]; Calculate the corrected temperature field distribution under the actual working conditions: Total product of correction coefficients = 1.25 × 2.56 = 3.2; Corrected temperature distribution without oil leakage: [40×3.2, 42×3.2, 41×3.2, 43×3.2, 42×3.2] = [128℃, 134.4℃, 131.2℃, 137.6℃, 134.4℃]; Corrected temperature distribution with slight oil leakage: [42×3.2, 45×3.2, 43×3.2, 46×3.2, 44×3.2] = [134.4℃, 144℃, 137.6℃, 147.2℃, 140.8℃]; Corrected temperature distribution with severe oil leakage: [45×3.2, 49×3.2, 46×3.2, 50×3.2, 47×3.2] = [144℃, 156.8℃, 147.2℃, 160℃, 150.4℃]; In this way, the corresponding relationship data between the oil leakage degree and the temperature field distribution under actual working conditions is obtained: No oil leakage: [128℃, 134.4℃, 131.2℃, 137.6℃, 134.4℃]; Slight oil leakage: [134.4℃, 144℃, 137.6℃, 147.2℃, 140.8℃]; Severe oil leakage: [144℃, 156.8℃, 147.2℃, 160℃, 150.4℃].

[0041] S104. Determine the current oil leakage degree of the oil-filled cable terminal based on the temperature field characteristic parameters and the corresponding relationship between the oil leakage temperature under actual working conditions.

[0042] Among them, the corresponding relationship between the oil leakage temperature under actual working conditions refers to the mapping relationship between the oil leakage degree after correction by ambient temperature and load current and the temperature field characteristics; the current oil leakage degree represents the current oil leakage state of the oil-filled cable terminal, which can be divided into multiple levels such as no oil leakage, slight oil leakage, moderate oil leakage, and severe oil leakage.

[0043] Specifically, the detection system matches and analyzes the currently collected temperature field characteristic parameters with the corresponding relationship table of the oil leakage temperature under actual working conditions: First, calculate the matching degree of the temperature field characteristic parameters with the characteristic parameters under each oil leakage degree in the corresponding relationship between the oil leakage temperature under actual working conditions, and the Euclidean distance or other similarity measurement methods can be used; then, based on the principle of the maximum matching degree, determine the level to which the current oil leakage degree belongs. If the matching degree is lower than the preset matching degree threshold, the detection system will mark the oil leakage degree as the "to be confirmed" state and wait for further verification.

[0044] By adopting the above technical solution, the detection system collects the temperature values of each sensor according to the sensor array longitudinally arranged along the inner side of the closed structure of the oil-filled cable terminal, calculates the temperature difference sequence, and extracts the characteristic parameters of the temperature field in the closed structure. The detection system corrects the finite element simulation results by combining the current ambient temperature and the current load current, obtains the corresponding relationship between the oil leakage temperature under the actual working conditions, and thus accurately reflects the oil leakage situation under the actual working conditions. This oil leakage analysis method based on the characteristic parameters of the temperature field and the corresponding relationship between the oil leakage temperature under the actual working conditions avoids the limitations of only relying on the oil level gauge and the float switch detection in the traditional detection method, improves the perception ability and quantitative analysis accuracy of slow leakage, can timely and accurately detect the oil leakage hidden danger, prevent accidents from occurring, and improves the accuracy and reliability of oil leakage detection.

[0045] The following is a further and more specific process description of the method provided in this embodiment. Please refer to Figure 2 , which is another process schematic diagram of the oil leakage analysis method for the oil-filled cable terminal in the embodiment of the present application.

[0046] S201. Collect the temperature values of each sensor through the sensor array longitudinally arranged along the inner side of the closed structure of the oil-filled cable terminal, and calculate the temperature difference between adjacent sensors to obtain a temperature difference sequence. The sensor array includes the first sensor to the Nth sensor arranged in sequence from top to bottom.

[0047] Specifically, reference can be made to step S101, which will not be elaborated here.

[0048] S202. Determine the characteristic parameters of the temperature field according to the temperature difference sequence. The characteristic parameters of the temperature field include the maximum temperature difference value, the maximum temperature difference position, the average temperature difference, the change rate of adjacent temperature differences, and the standard deviation of temperature differences in the temperature difference sequence.

[0049] Specifically, reference can be made to step S102, which will not be elaborated here.

[0050] S203. Establish a three-dimensional model of the oil-filled cable terminal. The three-dimensional model of the oil-filled cable terminal includes a conductor and a closed structure. The closed structure includes an insulating oil chamber and an air domain located above the insulating oil chamber. A sensor array is longitudinally arranged along the inner side of the closed structure.

[0051] Among them, the three-dimensional model of the oil-filled cable terminal refers to the three-dimensional digital representation used for finite element analysis; the conductor refers to the metal conductor used to transmit current; the closed structure refers to the housing system used to protect and seal the internal components; the insulating oil chamber refers to the sealed space used to accommodate the insulating oil; the air domain refers to the gas space above the insulating oil chamber.

[0052] Specifically, the detection system constructs a three-dimensional model including a conductor, an insulating oil chamber, and an air domain through computer-aided design (CAD) software based on the actual structural dimensions and material parameters of the oil-filled cable terminal. A plurality of temperature sensor nodes are uniformly arranged longitudinally along the inner sides of the insulating oil chamber and the air domain, and the positions and quantities of these temperature sensor nodes are consistent with the actually installed sensor array. Special attention is paid to the interface treatment between the insulating oil chamber and the air domain during modeling to ensure that the position changes of the oil-gas interface under different oil leakage degrees can be accurately reflected.

[0053] S204. Set a heat source boundary condition on the conductor surface, set a convective heat transfer boundary condition on the outer surface of the sealing structure, and set a radiative heat transfer boundary condition on the outer surface of the sealing structure to obtain an oil-filled cable terminal model. The heat source boundary condition is determined by a preset reference load current, and the convective heat transfer boundary condition and the radiative heat transfer boundary condition are determined by a preset reference ambient temperature.

[0054] Among them, the heat source boundary condition refers to a mathematical expression describing the heat generation characteristics of the conductor; the convective heat transfer boundary condition refers to the heat exchange characteristics between the surface of the closed structure and the surrounding air; the radiative heat transfer boundary condition refers to the thermal radiation characteristics of the surface of the closed structure.

[0055] Specifically, after completing the three-dimensional modeling, the detection system needs to set boundary conditions for thermal field analysis: First, apply a heat source boundary condition on the conductor surface, and the size of the heat source is determined by the product of the square of the preset reference load current and the resistance of the conductor; then, set a convective heat transfer boundary condition and a radiative heat transfer boundary condition on the outer surface of the closed structure at the same time. The parameters of these two heat transfer methods depend on the preset reference ambient temperature. The convective heat transfer coefficient is determined according to the specific situations of natural convection and forced convection, and the radiative heat transfer needs to consider the emissivity characteristics of the material. Through the setting of these boundary conditions, a complete thermal field analysis model of the oil-filled cable terminal is formed.

[0056] Optionally, generally, the heat source boundary condition is: ; where Q is the heat source of the oil-filled cable terminal, P is the heat generation power of the conductor, is the lateral area of the conductor, I is the preset reference load current flowing through the conductor, is the cross-sectional area of the conductor, ρ is the resistivity of the conductor, l is the length of the conductor; the convective heat transfer boundary condition is: ; where λ is the thermal conductivity of the insulating material in the closed structure, is the temperature gradient, is the surface area of the oil-filled cable terminal, h is the heat transfer coefficient of the outer surface of the oil-filled cable terminal in contact with the air, is the surface temperature of the oil-filled cable terminal, is the preset reference ambient temperature; the radiative heat transfer boundary condition is: ; where, is the Stefan-Boltzmann constant, is the surface emissivity.

[0057] The heat source of the oil-filled cable terminal is mainly generated by the cable core. When the oil-filled cable terminal is operating, the temperature of the cable core can reach above 70°C. The heat dissipation methods are multiple, including three methods: heat conduction, convection, and radiation. All three methods cannot be ignored in the temperature field simulation of the oil-filled cable terminal, and the heat generation intensity needs to be accurately quantified to simulate the actual temperature rise.

[0058] Regarding the heat source boundary condition, the heat source of the oil-filled cable terminal is set as a generalized source, and its size is obtained according to the size of the cable core and the size of the preset reference load current. In the oil-filled cable terminal model, the cross-sectional area of the cable core is 800 mm 2 , under the condition that the preset reference load current is 800 A, the heat source of the oil-filled cable terminal is 16800 W / m 3 .

[0059] Regarding the convective heat transfer boundary condition, the convective heat flux in the heat flux is selected for setting. In the natural convection state, the heat transfer coefficient of the outer surface of the oil-filled cable terminal in contact with the air is 5.8 W / (m 2 ·K), and the preset reference ambient temperature is set to 20°C.

[0060] Regarding the radiative heat transfer boundary condition, the surface radiation to the environment is selected for setting. Among them, the surface emissivity of silicone rubber is 0.8, the surface emissivity of aluminum alloy is 0.1, and the preset reference ambient temperature is set to 20°C.

[0061] S205. The oil-filled cable terminals with different air domain heights are subjected to finite element simulation to obtain the different temperature field distributions corresponding to different oil leakage degrees under the preset reference ambient temperature and the preset reference load current. The air domain height is used to characterize the oil leakage degree. The higher the air domain height, the more serious the oil leakage degree.

[0062] Among them, the finite element simulation refers to a method of discretizing a continuous physical field into a finite number of grid cells for numerical calculation; the air domain height represents the vertical distance of the gas space above the insulating oil chamber; the oil leakage degree refers to the severity of the insulating oil loss; the temperature field distribution represents the temperature state in the closed structure.

[0063] Specifically, first, the detection system divides the three-dimensional model of the oil-filled cable terminal into tetrahedral mesh elements, and the mesh size is appropriately densified in areas with large temperature gradients. Then, the detection system sets different air domain heights, for example, increasing the air domain height by 5 mm each time from the initial value until the preset maximum height is reached. For each air domain height, under the conditions of the preset reference ambient temperature (such as 20 °C) and the preset reference load current (such as 500 A), the detection system sets the above heat source boundary conditions, convective heat transfer boundary conditions, and radiative heat transfer boundary conditions in the COMSOL finite element simulation software, and then solves through the solver to obtain the overall temperature field distribution of the oil-filled cable terminal. The detection system establishes the mapping relationship between the air domain height (i.e., the degree of oil leakage) and the temperature field distribution to obtain the finite element simulation results.

[0064] S206. Calculate the ambient temperature correction coefficient and the load current correction coefficient according to the current ambient temperature, the current load current, the preset reference ambient temperature, and the preset reference load current, so as to correct the finite element simulation results and obtain the corresponding relationship between the oil leakage temperature under actual working conditions. The finite element simulation results refer to the different temperature field distributions corresponding to different degrees of oil leakage determined by the finite element simulation method under the preset reference ambient temperature and the preset reference load current.

[0065] Specifically, reference can be made to step S103, which will not be elaborated here.

[0066] S207. Determine the current degree of oil leakage of the oil-filled cable terminal based on the temperature field characteristic parameters and the corresponding relationship between the oil leakage temperature under actual working conditions.

[0067] Specifically, reference can be made to step S104, which will not be elaborated here.

[0068] S208. Periodically acquire multiple sets of temperature field characteristic parameters within a preset time period, and determine the ambient temperature, the load current, and the degree of oil leakage corresponding to each set of temperature field characteristic parameters, so as to draw the oil leakage development trend curve.

[0069] Among them, the preset time period refers to the pre-set data acquisition period; the oil leakage development trend curve refers to the graphical representation of the oil leakage state changing with time.

[0070] Specifically, the detection system periodically collects data at a preset sampling time interval (such as every 30 minutes). Each collection includes the temperature field characteristic parameters, the corresponding ambient temperature, and the load current. For each set of collected temperature field characteristic parameters, the detection system will calculate the corresponding degree of oil leakage. The detection system arranges them in chronological order to form a multi-dimensional time series, and then through data visualization technology, draws the change of the degree of oil leakage with time into an oil leakage development trend curve to visually display the development process of the oil leakage state.

[0071] S209. Determine the slope of the oil leakage development trend curve as the oil leakage rate to judge the stability of the oil leakage development trend.

[0072] Among them, the slope refers to the change rate of the oil leakage development trend curve at each time point; the oil leakage rate represents how fast the degree of oil leakage changes with time; the stability of the oil leakage development trend refers to the fluctuation degree of the oil leakage development process.

[0073] Specifically, the detection system uses the numerical differentiation method to calculate the slope of the oil leakage development trend curve at each time point, and the central difference formula can be used: slope at the current moment = (oil leakage degree at the next moment - oil leakage degree at the previous moment) / (2 × preset sampling time interval). Then, the detection system calculates the average value of the slopes within a period of time and uses it as a quantitative index of the oil leakage rate. The detection system compares the oil leakage rate with the preset rate threshold and analyzes the fluctuation of the slope to judge whether the oil leakage development trend is stable.

[0074] S210. When the oil leakage development trend is unstable, analyze the correlation between the temperature field characteristic parameters, the ambient temperature, and the load current.

[0075] Among them, the correlation refers to the linear correlation degree between two variables, and its value range is between -1 and 1.

[0076] Specifically, when the detection system finds that the oil leakage development trend is unstable, it is necessary to analyze whether this instability is caused by external factors (ambient temperature and load current) or equipment itself failures. The detection system collects historical data of the temperature field characteristic parameters, the ambient temperature, and the load current within a period of time (usually 24 hours to 7 days), and then preprocesses the historical data, including removing outliers caused by measurement errors, signal interference, etc., and standardizing the data with different dimensions through the z-score or min-max method. The detection system calculates the Pearson correlation coefficients between the standardized temperature field characteristic parameters and the ambient temperature, and the load current respectively, that is, the correlation. During the calculation process, first, the detection system obtains the mean and standard deviation of each variable, then calculates the covariance between the variables, and finally obtains the correlation. The detection system can judge whether the change of the temperature field is caused by the ambient temperature and the load current (the correlation is relatively large, such as greater than 0.8), or caused by the equipment oil leakage failure (the correlation is relatively small, such as less than 0.5) according to the magnitude of the correlation.

[0077] Optionally, generally, when the development trend of oil leakage is unstable, the correlation between the characteristic parameters of the temperature field and the ambient temperature and load current can be achieved in the following ways, which are not limited herein: Arrange the characteristic parameters of the temperature field, the ambient temperature, and the load current in chronological order to obtain a sequence of characteristic parameters of the temperature field, a sequence of ambient temperatures, and a sequence of load currents; calculate the Pearson correlation coefficient between the sequence of characteristic parameters of the temperature field and the sequence of ambient temperatures to obtain the ambient temperature correlation; calculate the Pearson correlation coefficient between the sequence of characteristic parameters of the temperature field and the sequence of load currents to obtain the load current correlation; determine the correlation between the characteristic parameters of the temperature field and the ambient temperature and load current based on the ambient temperature correlation and the load current correlation.

[0078] Among them, the sequence of characteristic parameters of the temperature field refers to the characteristic parameters of the temperature field arranged in chronological order; the sequence of ambient temperatures refers to the ambient temperatures arranged in chronological order; the sequence of load currents refers to the load currents arranged in chronological order.

[0079] Specifically, first, the detection system performs data preprocessing on the collected sequence of characteristic parameters of the temperature field and the sequence of ambient temperatures, including removing outliers, filling in missing values, and data standardization. Then, the detection system calculates the mean values of the two sequences, and subtracts their respective mean values to obtain the deviation values. Next, the detection system calculates the product sum of the deviation values of the two sequences, and divides it by the product sum of the standard deviations of the two sequences and the product of the number of samples minus one, and finally obtains the Pearson correlation coefficient. The detection system uses this Pearson correlation coefficient as a quantitative index for the ambient temperature correlation to be used for subsequent judgment whether the change in the temperature field is mainly affected by the ambient temperature. For example, if the calculated Pearson correlation coefficient is 0.85, it indicates that there is a strong positive correlation between the characteristic parameters of the temperature field and the ambient temperature, indicating that the change in the ambient temperature may be one of the main reasons for the change in the temperature field. The processing method for the sequence of characteristic parameters of the temperature field and the sequence of load currents is the same and will not be elaborated here.

[0080] S211. If the correlation exceeds the preset correlation threshold, adjust the ambient temperature and the load current to the preset standard range.

[0081] Among them, the preset correlation threshold refers to the critical value used to judge the significance of the correlation; the preset standard range refers to the normal working range of the ambient temperature and the load current; the adjustment of the ambient temperature refers to changing the surrounding temperature through an environmental control device; the adjustment of the load current refers to changing the magnitude of the current through load transfer or power control.

[0082] Specifically, when the detection system finds that the correlation between characteristic temperature field parameters and external factors exceeds a preset correlation threshold, it indicates that the temperature field anomaly is primarily caused by external factors. The detection system generates operating condition adjustment instructions to determine whether the ambient temperature and load current are within the preset standard range (e.g., ambient temperature 15-35°C, load current 300-700A). If the ambient temperature and load current exceed the preset standard range, the detection system will activate environmental control equipment (such as air conditioning and ventilation systems) to adjust the ambient temperature. Simultaneously, the power distribution automation system will adjust the load distribution to bring the load current back within the preset standard range.

[0083] S212: If the correlation is less than or equal to the preset correlation threshold, trigger an emergency alarm.

[0084] Specifically, when the correlation between characteristic temperature field parameters and external factors is lower than or equal to a preset correlation threshold, the abnormal temperature field may be caused by a device fault. The detection system immediately triggers an emergency alarm: first, an alarm message containing the device number, fault type, and severity is sent to the monitoring center; a text message or app notification is also sent to relevant maintenance personnel; and the detection system automatically generates a detailed report containing historical data analysis, fault diagnosis results, and recommended actions.

[0085] S213. When the oil leakage development trend is stable, calculate the remaining time to reach the preset oil leakage threshold based on the current oil leakage level and leakage rate; if the remaining time is less than the preset time threshold, generate a maintenance instruction, which includes a recommended maintenance time window.

[0086] Among them, the remaining time refers to the estimated time required to reach the preset oil leakage threshold; the preset oil leakage threshold refers to the critical oil leakage level that requires maintenance; the preset time threshold refers to the time threshold that triggers the maintenance recommendation; the maintenance instruction refers to the maintenance command issued by the detection system; the recommended maintenance time window indicates the recommended maintenance execution period.

[0087] Specifically, the detection system uses a linear extrapolation method to calculate the remaining time required to reach a preset leakage threshold (such as 40%) based on the current leakage level (such as 20%) and the leakage rate (such as an increase of 0.5% per day). If the calculated remaining time is less than the preset time threshold (such as 7 days), the detection system will generate a maintenance instruction. This maintenance instruction includes: basic equipment information, current leakage status data, predicted remaining time, recommended maintenance time window (selecting a low-peak period considering the load curve), a list of required maintenance materials, etc. For example, if the current leakage level of an oil-filled cable terminal is 35%, the leakage rate is 0.8% per day, and the preset leakage threshold is 40%, then the remaining time is approximately 6.25 days, and the detection system will recommend completing the maintenance within 5 days.

[0088] The detection system in the embodiments of the present invention application will be described from the perspective of hardware processing. Please refer to Figure 3 , which is a schematic structural diagram of an entity device of the detection system in the embodiments of the present application.

[0089] It should be noted that Figure 3 the structure of the detection system shown is only an example and should not impose any limitations on the functions and usage scope of the embodiments of the present invention.

[0090] As Figure 3 shown, the detection system includes a CPU 301, which can perform various appropriate actions and processes according to the program stored in the read-only memory ROM 302 or the program loaded from the storage section 308 into the random access memory RAM 303, such as executing the method described in the above embodiments. In the RAM 303, various programs and data required for system operation are also stored. The CPU 301, ROM 302, and RAM 303 are connected to each other via a bus 304. The I / O interface 305 is also connected to the bus 304.

[0091] The following components are connected to the I / O interface 305: an input section 306 including an audio input device, a button switch, etc.; an output section 307 including a liquid crystal display (LCD), an audio output device, an indicator light, etc.; a storage section 308 including a hard disk, etc.; and a communication section 309 including a network interface card such as a LAN (Local Area Network) card, a modem, etc. The communication section 309 performs communication processing via a network such as the Internet. A driver 310 is also connected to the I / O interface 305 as needed. A removable medium 311, such as a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory, etc., is installed on the driver 310 as needed so that a computer program read from it can be installed into the storage section 308 as needed.

[0092] Specifically, according to the embodiments of the present invention, the process described above with reference to the flowchart can be implemented as a computer software program. For example, the embodiments of the present invention include a computer program product, which includes a computer program carried on a computer-readable medium, and the computer program includes a computer program for executing the method shown in the flowchart. In such an embodiment, the computer program can be downloaded and installed from the network through the communication section 309 and / or installed from the removable medium 311. When the computer program is executed by the CPU 301, various functions defined in the present invention are executed.

[0093] It should be noted that specific examples of computer-readable storage media may include, but are not limited to: electrical connections with one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM), flash memory, optical fibers, portable compact disc read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the above. In the present invention, a computer-readable storage medium can be any tangible medium that contains or stores a program, and this program can be used by or in conjunction with an instruction execution system, apparatus, or device.

[0094] The flowcharts and block diagrams in the accompanying drawings illustrate the possible architectures, functions, and operations of systems, methods, and computer program products according to various embodiments of the present invention. Among them, each block in the flowchart or block diagram may represent a module, a program segment, or a part of code, and the above-mentioned module, program segment, or part of code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order from that marked in the accompanying drawings.

[0095] Specifically, the detection system of this embodiment includes a processor and a memory, and a computer program is stored on the memory. When the computer program is executed by the processor, the oil-filled cable terminal oil leakage analysis method provided in the above embodiment is implemented.

[0096] On the other hand, the present invention also provides a computer-readable storage medium, which can be included in the detection system described in the above embodiment; or it can exist separately and not be assembled into the detection system. The above storage medium carries one or more computer programs. When the above one or more computer programs are executed by a processor of the detection system, the detection system is enabled to implement the oil-filled cable terminal oil leakage analysis method provided in the above embodiment.

[0097] As described above, the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application 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 recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the various embodiments of the present application.

[0098] Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above-described embodiments can be completed by hardware instructed by a computer program. This program can be stored in a computer-readable storage medium. When the program is executed, it can include the processes of the above-described method embodiments. The foregoing storage medium includes: various media such as ROM, random access memory (RAM), magnetic disks, or optical discs that can store program codes.

Claims

1. A method for analyzing oil leakage in an oil-filled cable terminal, characterized in that, Applied to a detection system, the method includes: Collecting temperature values of each sensor through a sensor array longitudinally arranged along the inner side of the oil-filled cable terminal's closed structure, and calculating the temperature difference between adjacent sensors to obtain a temperature difference sequence. The sensor array includes a first sensor to an Nth sensor arranged successively from top to bottom; Determining temperature field characteristic parameters according to the temperature difference sequence. The temperature field characteristic parameters include the maximum temperature difference value, the position of the maximum temperature difference, the average temperature difference, the change rate of adjacent temperature differences, and the standard deviation of temperature differences in the temperature difference sequence; Calculating an ambient temperature correction coefficient and a load current correction coefficient according to the current ambient temperature, the current load current, a preset reference ambient temperature, and a preset reference load current to correct the finite element simulation results and obtain the corresponding relationship between the oil leakage temperature under actual working conditions. The finite element simulation results refer to the different temperature field distributions corresponding to different oil leakage degrees determined by the finite element simulation method under the preset reference ambient temperature and the preset reference load current; Determining the current oil leakage degree of the oil-filled cable terminal based on the temperature field characteristic parameters and the corresponding relationship between the oil leakage temperature under actual working conditions.

2. The method according to claim 1, wherein Before the step of calculating the ambient temperature correction coefficient and the load current correction coefficient according to the current ambient temperature, the current load current, the preset reference ambient temperature, and the preset reference load current to correct the finite element simulation results and obtain the corresponding relationship between the oil leakage temperature under actual working conditions, the method further includes: Establishing a three-dimensional model of the oil-filled cable terminal, which includes a conductor and a closed structure. The closed structure includes an insulating oil chamber and an air domain above the insulating oil chamber. A sensor array is longitudinally arranged along the inner side of the closed structure; Setting a heat source boundary condition on the surface of the conductor, setting a convective heat transfer boundary condition on the outer surface of the sealing structure, and setting a radiative heat transfer boundary condition on the outer surface of the sealing structure to obtain an oil-filled cable terminal model. The heat source boundary condition is determined by the preset reference load current, and the convective heat transfer boundary condition and the radiative heat transfer boundary condition are determined by the preset reference ambient temperature; Performing finite element simulation on the oil-filled cable terminal at different air domain heights to obtain different temperature field distributions corresponding to different oil leakage degrees under the preset reference ambient temperature and the preset reference load current. The air domain height is used to characterize the oil leakage degree, and the higher the air domain height, the more serious the oil leakage degree.

3. The method according to claim 2, wherein The heat source boundary condition is as follows: ; Among them, Q is the heat source of the oil-filled cable terminal, and P is the heating power of the conductor. is the lateral area of the conductor, and I is the preset reference load current flowing through the conductor. is the cross-sectional area of the conductor, ρ is the resistivity of the conductor, and l is the length of the conductor. The convective heat transfer boundary condition is as follows: ; where λ is the thermal conductivity of the insulating material in the closed structure, is the temperature gradient, is the surface area of the oil-filled cable terminal, h is the heat transfer coefficient of the outer surface of the oil-filled cable terminal in contact with air, is the surface temperature of the oil-filled cable terminal, is the preset reference ambient temperature; The radiation heat transfer boundary condition is as follows: ; In the formula, is the Stefan-Boltzmann constant, is the surface emissivity.

4. The method according to claim 1, wherein The step of calculating the ambient temperature correction coefficient and the load current correction coefficient according to the current ambient temperature, the current load current, the preset reference ambient temperature, and the preset reference load current to correct the finite element simulation results and obtain the corresponding relationship between the oil leakage temperature under actual working conditions specifically includes: Determining the ratio of the current ambient temperature to the preset reference ambient temperature as the ambient temperature correction coefficient, and determining the square ratio of the current load current to the preset reference load current as the load current correction coefficient; Multiply the temperature field distribution in the finite element simulation results by the product of the ambient temperature correction coefficient and the load current correction coefficient respectively to obtain the corrected temperature field distribution; Establish the correspondence between different degrees of oil leakage and different corrected temperature field distributions to obtain the correspondence between the oil leakage temperature under the actual working conditions; 5. The method according to claim 1, wherein After the step of determining the current degree of oil leakage of the oil-filled cable terminal based on the temperature field characteristic parameters and the correspondence between the oil leakage temperature under the actual working conditions, the method further includes: Within a preset time period, periodically obtain multiple sets of temperature field characteristic parameters, and determine the ambient temperature, load current, and degree of oil leakage corresponding to each of the multiple sets of temperature field characteristic parameters to draw a curve of the development trend of oil leakage; Determine the slope of the oil leakage development trend curve as the oil leakage rate to judge the stability of the oil leakage development trend; When the oil leakage development trend is unstable, analyze the correlation between the temperature field characteristic parameters and the ambient temperature and load current; If the correlation exceeds the preset correlation threshold, adjust the ambient temperature and load current to the preset standard range; If the correlation is less than or equal to the preset correlation threshold, trigger an emergency alarm.

6. The method according to claim 5, characterized in that, After the step of determining the slope of the oil leakage development trend curve as the oil leakage rate to judge the stability of the oil leakage development trend, the method further includes: When the oil leakage development trend is stable, calculate the remaining time to reach the preset oil leakage degree threshold according to the current oil leakage degree and the oil leakage rate; If the remaining time is less than the preset time threshold, generate a maintenance instruction, and the maintenance instruction includes a recommended maintenance time window.

7. The method according to claim 5, wherein The step of analyzing the correlation between the temperature field characteristic parameters and the ambient temperature and load current when the oil leakage development trend is unstable specifically includes: Arrange the temperature field characteristic parameters, ambient temperature, and load current in chronological order to obtain a temperature field characteristic parameter sequence, an ambient temperature sequence, and a load current sequence; Calculate the Pearson correlation coefficient between the temperature field characteristic parameter sequence and the ambient temperature sequence to obtain the ambient temperature correlation; Calculate the Pearson correlation coefficient between the temperature field characteristic parameter sequence and the load current sequence to obtain the load current correlation; Determine the correlation between the temperature field characteristic parameters and the ambient temperature and load current according to the ambient temperature correlation and the load current correlation.

8. A detection system, characterized in that, The detection system includes: one or more processors and a memory; the memory is coupled to the one or more processors, the memory is used to store computer program code, the computer program code includes computer instructions, and the one or more processors call the computer instructions to enable the detection system to execute the method according to any one of claims 1-7.

9. A computer-readable storage medium, comprising instructions, characterized in that, When the instruction runs on the detection system, enable the detection system to execute the method according to any one of claims 1-7.

10. A computer program product, characterized in that, When the computer program product runs on the detection system, enable the detection system to execute the method according to any one of claims 1-7.

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