Distinguishing method for gas diffusion balance in buffer layer of high-voltage cable and related device

Abstract

The invention provides a method for judging gas diffusion balance in a buffer layer of a high-voltage cable and a related device, and relates to the technical field of power grid fault detection. The method comprises the following steps: in response to a defect of a buffer layer of a high-voltage cable, constructing a first gas diffusion kinetic model corresponding to the buffer layer in the high-voltage cable based on a Fick second law; performing multi-factor correction on the gas diffusion coefficient according to the porosity and tortuosity of the buffer layer to obtain a second gas diffusion kinetic model; constructing a gas diffusion simulation model of the high-voltage cable according to the second gas diffusion kinetic model; through the gas diffusion simulation model, simulating the change conditions of gas concentrations corresponding to a plurality of sampling points on the high-voltage cable along with time; and comparing and analyzing the change conditions of the gas concentrations corresponding to the plurality of sampling points along with the time to obtain a judgment result of whether the gas diffusion of the buffer layer corresponding to the defect is balanced or not. According to the invention, the accuracy of buffer layer gas diffusion balance discrimination can be improved.

Description

Technical Field

[0001] This application relates to the field of power grid fault detection technology, and in particular to a method and related apparatus for determining the gas diffusion balance in the buffer layer of a high-voltage cable. Background Technology

[0002] In recent years, high-voltage cables with cross-linked polyethylene corrugated aluminum sheaths have experienced frequent failures due to defects in the buffer layer, seriously threatening the safe and stable operation of power systems. Extracting and analyzing the gas accumulated inside the buffer layer has proven to be a highly promising method for directly diagnosing buffer layer defects. Studies have shown that when defects such as white spots, erosion, and ablation exist in the buffer layer, the concentrations of characteristic gases produced inside, such as hydrogen (H2) and carbon monoxide (CO), significantly increase, while the oxygen content decreases significantly. The composition and concentration variation patterns of these characteristic gases provide crucial information for accurately determining the type and severity of defects.

[0003] However, the accuracy of characteristic gas component analysis results is highly dependent on two key parameters: the selection of sampling point location and the gas sampling cycle. On the one hand, buffer layers are often complex porous structures with non-uniformity. Differences in tortuosity, porosity, and distance from the defect source at different locations lead to significant spatial variations in gas diffusion rates and path impedance. If the sampling point is far from the defect source or located in an area with poor diffusion paths, the detected characteristic gas concentration may be far lower than the concentration near the actual defect source, or even lower than the detection threshold, resulting in missed detections. On the other hand, the diffusion rate of different types of characteristic gases in the buffer layer and the time required to reach concentration equilibrium—i.e., the gas diffusion equilibrium time—are affected by various factors, such as the structural characteristics of the buffer layer (porosity and tortuosity), ambient temperature, and the physicochemical properties of the gases themselves. If the gas sampling cycle is too short, sampling will be performed before the characteristic gas concentration reaches equilibrium, making it impossible to obtain representative concentration data reflecting the true state of the defect, easily leading to misjudgments.

[0004] Therefore, accurately determining the diffusion state of characteristic gases in the buffer layer of high-voltage cables, especially whether the gas concentration has reached diffusion equilibrium, is a crucial prerequisite for formulating a scientific and reliable gas detection strategy for the buffer layer. Summary of the Invention

[0005] This application provides a method and related apparatus for determining the gas diffusion balance in the buffer layer of a high-voltage cable, so as to accurately determine whether the gas in the buffer layer has reached diffusion balance.

[0006] In a first aspect, embodiments of this application provide a method for determining the gas diffusion balance in the buffer layer of a high-voltage cable, comprising:

[0007] In response to the defect in the buffer layer of the high-voltage cable, based on Fick's second law, and according to the ambient temperature and air pressure of the high-voltage cable, a first gas diffusion dynamics model corresponding to the buffer layer in the high-voltage cable is constructed. In the gas diffusion dynamics model, the rate of change of gas concentration with respect to time is equal to the product of the gas diffusion coefficient and the Laplace operator of the gas concentration.

[0008] Based on the porosity and tortuosity of the buffer layer, the gas diffusion coefficient is corrected by multiple factors to obtain the second gas diffusion dynamics model;

[0009] Based on the structural characteristics of the buffer layer, and according to the second gas diffusion dynamics model, a gas diffusion simulation model for high-voltage cables is constructed. The gas diffusion simulation model is used to simulate the gas diffusion at the sampling points of high-voltage cables.

[0010] The gas diffusion simulation model was used to simulate the changes in gas concentration over time at multiple sampling points on the high-voltage cable.

[0011] By comparing and analyzing the changes in gas concentration over time at multiple sampling points, the determination results of whether the gas diffusion in the buffer layer corresponding to the defect is balanced are obtained.

[0012] In one possible implementation, based on Fick's second law, and according to the ambient temperature and atmospheric pressure of the high-voltage cable, a first gas diffusion dynamics model corresponding to the buffer layer in the high-voltage cable is constructed, including:

[0013] Based on the ambient temperature and air pressure of the high-voltage cable, determine the gas diffusion coefficient of the gas in the buffer layer corresponding to the ambient temperature and air pressure.

[0014] Based on Fick's second law, and according to the gas diffusion coefficient of the gas in the buffer layer corresponding to the ambient temperature and ambient air pressure, a first gas diffusion dynamics model corresponding to the buffer layer in the high-voltage cable is constructed.

[0015] In one possible implementation, the gas diffusion coefficient of the gas in the buffer layer corresponding to the ambient temperature and ambient pressure of the high-voltage cable is determined, including:

[0016] Based on the ambient temperature and air pressure of the high-voltage cable, the gas diffusion coefficient of the gas in the buffer layer corresponding to the ambient temperature and air pressure is determined using the following formula:

[0017]

[0018] Where D is the gas diffusion coefficient of the gas in the buffer layer corresponding to the ambient temperature and ambient pressure, T is the ambient temperature, P is the ambient pressure, and D298.15K The gas diffusion coefficient is given at standard atmospheric pressure and a temperature of 298.15 K.

[0019] In one possible implementation, the gas diffusion coefficient is corrected for multiple factors based on the porosity and tortuosity of the buffer layer to obtain a second gas diffusion kinetic model, including:

[0020] Obtain the porosity and tortuosity of the buffer layer;

[0021] The corrected gas diffusion coefficient is determined by multiplying the ratio of porosity to tortuosity by the gas diffusion coefficient.

[0022] Based on the corrected gas diffusion coefficient and the first gas diffusion kinetic model, the second gas diffusion kinetic model is obtained.

[0023] In one possible implementation, based on the structural characteristics of the buffer layer and according to the second gas diffusion kinetic model, a gas diffusion simulation model for the high-voltage cable is constructed, including:

[0024] Based on the structural characteristics of the buffer layer, and according to the forward difference approximation principle, the rate of change of gas concentration with respect to time at each sampling point is approximated by forward difference to obtain the approximate rate of change of gas concentration.

[0025] Based on the central difference approximation principle, the Laplace operator of the gas concentration is approximated by the central difference to obtain the approximate Laplace operator;

[0026] Substituting the approximate gas concentration change rate and the approximate Laplace operator into the second gas diffusion dynamics model, a gas diffusion simulation model for high-voltage cables is obtained.

[0027] In one possible implementation, the changes in gas concentration over time at multiple sampling points are compared and analyzed to obtain a judgment result on whether the gas diffusion in the buffer layer corresponding to the defect is balanced, including:

[0028] For any two sampling points among multiple sampling points, determine the difference in gas concentration at the same time between the two sampling points;

[0029] If the difference between any two sampling points among multiple sampling points is less than the preset gas concentration difference threshold, then the discrimination result of the gas diffusion balance of the buffer layer corresponding to the defect is obtained.

[0030] If the difference between any two sampling points among multiple sampling points is greater than or equal to the preset gas concentration difference threshold, then the discrimination result of gas diffusion imbalance in the buffer layer corresponding to the defect is obtained.

[0031] In one possible implementation, it also includes:

[0032] The moment when the discrimination result of the gas diffusion balance of the buffer layer corresponding to the defect is obtained is taken as the target moment of the gas diffusion balance of the buffer layer corresponding to the defect.

[0033] Secondly, embodiments of this application provide a device for determining the gas diffusion balance in the buffer layer of a high-voltage cable, comprising:

[0034] The first model construction module is used to respond to defects in high-voltage cables. Based on Fick's second law, and according to the ambient temperature and air pressure of the high-voltage cable, a first gas diffusion dynamics model corresponding to the buffer layer in the high-voltage cable is constructed. In the gas diffusion dynamics model, the rate of change of gas concentration with respect to time is equal to the product of the gas diffusion coefficient and the Laplace operator of the gas concentration.

[0035] The correction module is used to correct the gas diffusion coefficient based on the porosity and tortuosity of the buffer layer, thereby obtaining a second gas diffusion kinetic model.

[0036] The second model building module is used to construct a gas diffusion simulation model of the high-voltage cable based on the structural characteristics of the buffer layer and the second gas diffusion dynamics model. The gas diffusion simulation model is used to simulate the gas diffusion at the sampling points of the high-voltage cable.

[0037] The simulation module is used to simulate the changes in gas concentration over time at multiple sampling points on a high-voltage cable using a gas diffusion simulation model.

[0038] The analysis module is used to compare and analyze the changes in gas concentration over time at multiple sampling points to obtain a judgment result on whether the gas diffusion in the buffer layer corresponding to the defect is balanced.

[0039] Thirdly, embodiments of this application provide a device for determining the gas diffusion balance in the buffer layer of a high-voltage cable, comprising: a memory and a processor;

[0040] The memory stores instructions that the computer executes;

[0041] The processor executes computer execution instructions stored in memory, causing the processor to perform the first aspect and / or various possible implementations of the first aspect as described above.

[0042] Fourthly, embodiments of this application provide a computer-readable storage medium storing computer-executable instructions, which, when executed, are used to implement the first aspect and / or various possible implementations of the first aspect.

[0043] Fifthly, embodiments of this application provide a computer program product, including a computer program, which, when executed, implements the first aspect and / or various possible implementations of the first aspect.

[0044] The method for determining gas diffusion balance in the buffer layer of a high-voltage cable provided in the application embodiment responds to defects in the high-voltage cable. Based on Fick's second law, a first gas diffusion dynamics model is constructed for the buffer layer of the high-voltage cable according to the ambient temperature and air pressure. In the gas diffusion dynamics model, the rate of change of gas concentration with respect to time is equal to the product of the gas diffusion coefficient and the Laplace operator of the gas concentration. A second gas diffusion dynamics model is obtained by correcting the gas diffusion coefficient based on the porosity and tortuosity of the buffer layer using multiple factors. Based on the structural characteristics of the buffer layer, a gas diffusion simulation model of the high-voltage cable is constructed according to the second gas diffusion dynamics model. This simulation model is used to simulate the gas diffusion at sampling points on the high-voltage cable. The gas diffusion simulation model simulates the changes in gas concentration over time at multiple sampling points on the high-voltage cable. By comparing and analyzing the changes in gas concentration over time at multiple sampling points, a determination result is obtained regarding whether the gas diffusion in the buffer layer corresponding to the defect is balanced. This application constructs a gas diffusion model that considers ambient temperature, ambient air pressure, porosity, and tortuosity, and combines it with quantitative analysis through numerical simulation to achieve accurate prediction of the change of gas concentration in the buffer layer over time, which can significantly improve the accuracy and reliability of judging the gas diffusion balance in the buffer layer. Attached Figure Description

[0045] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0046] Figure 1 A flowchart illustrating the method for determining gas diffusion balance in the buffer layer of a high-voltage cable provided in this application embodiment. Figure 1 ;

[0047] Figure 2 This is a schematic diagram of the gas concentration change over time at different sampling points provided in the embodiments of this application;

[0048] Figure 3 A flowchart illustrating the method for determining gas diffusion balance in the buffer layer of a high-voltage cable provided in this application embodiment. Figure 2 ;

[0049] Figure 4 This is a schematic diagram of a cable simulation model provided in an embodiment of this application;

[0050] Figure 5A schematic diagram of the structure of the gas diffusion balance discrimination device in the buffer layer of the high-voltage cable provided in the embodiments of this application;

[0051] Figure 6 A schematic diagram of the structure of the gas diffusion balance discrimination device in the buffer layer of the high-voltage cable provided in the embodiments of this application.

[0052] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0053] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0054] With the growth of transmission load and system aging, defects such as white spots and ablation in the buffer layer of high-voltage cables occur frequently, posing serious threats to the safe operation of the power grid. Therefore, a comprehensive condition assessment of the buffer layer of high-voltage cables is urgently needed. Compared with traditional visual inspection or partial dissection, extracting gas from the buffer layer and using precise analysis techniques such as gas chromatography can non-destructively obtain gas markers of early defect generation, becoming a fast and reliable online diagnostic method. However, the accuracy of gas detection results is highly dependent on the location and distribution of sampling points and the reasonable setting of the gas sampling cycle: sampling points that are too concentrated or improperly spaced can easily miss local defects, while gas sampling cycles that are too short or too long may cause early signal loss or redundant results. The special structure of the buffer layer of high-voltage cables means that the gas generated by defects needs time to diffuse evenly. Detection before diffusion equilibrium is reached is greatly affected by the location of the sampling points. For example, extremely high local concentrations can misleadly overestimate defects, while undetectable gas in some areas can lead to missed detections. Waiting for diffusion equilibrium is to allow the gas concentration to distribute relatively evenly within the buffer layer space. Only at this point can the detected concentration value truly represent the overall gas production level of internal defects in the cable, thus providing accurate, reliable information that can be used to diagnose the health status of the cable insulation. This is a crucial prerequisite for ensuring the effectiveness and diagnostic accuracy of defect gas detection technology. Therefore, accurately determining whether gas diffusion in the buffer layer of a high-voltage cable has reached equilibrium is an important prerequisite for accurately diagnosing defects in the high-voltage cable buffer layer.

[0055] To address the aforementioned technical issues, this application provides a gas diffusion dynamics mathematical model based on Fick's second law and other theoretical foundations. This model comprehensively considers the environment and structural characteristics of the buffer layer, such as ambient temperature, ambient air pressure, tortuosity, and porosity. Furthermore, it constructs a gas diffusion simulation model for the buffer layer, systematically simulating and analyzing the changes in the concentration distribution of various gases in the air gap of the buffer layer over time under different diffusion conditions, such as different temperatures, air pressures, porosities, tortuosities, and defect locations. This model quantitatively predicts the diffusion equilibrium state and the time required to reach the diffusion equilibrium state.

[0056] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0057] Figure 1 A flowchart illustrating the method for determining gas diffusion balance in the buffer layer of a high-voltage cable provided in this application embodiment. Figure 1 In some implementations, the method for determining the buffer layer gas diffusion equilibrium time provided in this application is executed by a processor with data processing capabilities. For example... Figure 1 As shown, the method includes:

[0058] S101. In response to the defect in the buffer layer of the high-voltage cable, based on Fick's second law, and according to the ambient temperature and air pressure of the high-voltage cable, a first gas diffusion dynamics model corresponding to the buffer layer in the high-voltage cable is constructed. In the gas diffusion dynamics model, the rate of change of gas concentration with respect to time is equal to the product of the gas diffusion coefficient and the Laplace operator of the gas concentration.

[0059] In some implementations, the state of the buffer layer of the high-voltage cable can be monitored by a sensor installed on the cable. When a defect is detected in the buffer layer of the high-voltage cable, information indicating that the buffer layer of the high-voltage cable has a defect is sent to the processor. In response to the defect in the buffer layer of the high-voltage cable, the processor determines the gas diffusion balance of the buffer layer.

[0060] The first gas diffusion dynamics model based on Fick's second law is shown in the following equation:

[0061]

[0062] In the above formula, c represents the gas concentration, with units of mol / m³. 3t represents diffusion time in seconds; D represents the effective diffusion coefficient of the gas, which is related to the diffusion coefficient of the gas at standard atmospheric pressure and temperature, the ambient temperature and pressure of the high-voltage cable, and the structural characteristics of the buffer layer, and is expressed in meters. 2 / s; For the Laplace operator.

[0063] S102. Based on the porosity and tortuosity of the buffer layer, the gas diffusion coefficient is corrected by multiple factors to obtain the second gas diffusion dynamics model.

[0064] The buffer layer of high-voltage cables has a spiral characteristic due to its internal air gap, and the polyester fiber buffer layer is a porous material. This will affect the diffusion path and diffusion rate of gas after it is generated in the buffer layer. Therefore, based on the first gas diffusion model, the gas diffusion coefficient is modified by considering the porosity and tortuosity of the buffer layer, so as to obtain a second gas diffusion kinetic model that better reflects the internal structure of the buffer layer of high-voltage cables.

[0065] S103. Based on the structural characteristics of the buffer layer, and according to the second gas diffusion dynamics model, a gas diffusion simulation model for high-voltage cables is constructed. The gas diffusion simulation model is used to simulate the gas diffusion at the sampling points of the high-voltage cables.

[0066] Typically, the buffer layer of a high-voltage cable can be abstracted as a one-dimensional structure. Multiple sampling points are set on the high-voltage cable, and by observing the gas concentration at these sampling points, it can be determined whether the gas has diffused into equilibrium within the buffer layer. Based on the second gas diffusion kinetic model, a gas diffusion simulation model representing the gas diffusion at the sampling points on the one-dimensional structure is constructed to obtain simulation data of the gas concentration at different sampling points in the buffer layer of the high-voltage cable.

[0067] S104. Using a gas diffusion simulation model, simulate the changes in gas concentration over time at multiple sampling points on the high-voltage cable.

[0068] Figure 2 This is a schematic diagram illustrating the gas concentration variation over time at different sampling points provided in this application embodiment. For example, multiple curves are obtained based on the gas concentration variations over time at multiple sampling points, such as... Figure 2 As shown, the horizontal axis represents the location of the sampling point, and the vertical axis represents the relative concentration of the gas. Taking hydrogen as the diffusing gas and a high-voltage cable with a porosity and tortuosity of 1,500 meters as an example, the specific quantitative relationship between gas concentration and diffusion time can be analyzed from the curves in the figure. Figure 2 As can be seen, after one day, the relative concentration of gas at the gas source has become about 10% of the initial concentration. Subsequently, due to the decrease in concentration, the diffusion process gradually slows down. After a week of diffusion, the overall gas concentration of the cable buffer layer has become consistent.

[0069] S105. Compare and analyze the changes in gas concentration over time at multiple sampling points to obtain the judgment result on whether the gas diffusion of the buffer layer corresponding to the defect is balanced.

[0070] In one implementation, when the difference in gas concentration values ​​between any two sampling points is less than a preset concentration difference threshold, the gas diffusion in the buffer layer is considered to have reached equilibrium. For example, the concentration difference threshold is 5%.

[0071] The method for determining gas diffusion equilibrium in the buffer layer of high-voltage cables provided in this application embodiment is based on Fick's second law. It comprehensively considers the ambient temperature and air pressure of the high-voltage cable to construct a first gas diffusion dynamics model corresponding to the buffer layer. Further, considering the internal structural characteristics of the buffer layer, porosity and tortuosity are used to modify the first gas diffusion dynamics model, resulting in a second gas diffusion dynamics model that reflects the diffusion characteristics of gas in the high-voltage cable buffer layer. Based on the second diffusion dynamics model, a gas diffusion simulation model is constructed to simulate the gas diffusion at multiple sampling points on the cable. By comparing the gas diffusion at multiple sampling points, the diffusion equilibrium state of the gas in the buffer layer is determined, achieving accurate determination of the gas diffusion state in the buffer layer of the high-voltage cable, particularly the effect of achieving diffusion equilibrium in gas concentration.

[0072] In one possible implementation, based on Fick's second law, and according to the ambient temperature and atmospheric pressure of the high-voltage cable, a first gas diffusion dynamics model corresponding to the buffer layer in the high-voltage cable is constructed, including:

[0073] Based on the ambient temperature and pressure of the high-voltage cable, the gas diffusion coefficient of the gas in the buffer layer corresponding to the ambient temperature and pressure is determined. Based on Fick's second law, a first gas diffusion dynamics model corresponding to the buffer layer in the high-voltage cable is constructed according to the gas diffusion coefficient of the gas in the buffer layer corresponding to the ambient temperature and pressure.

[0074] The diffusion coefficient of a gas reflects the ability of gas molecules to diffuse in free space, and its value is affected by the type of gas, temperature, and pressure. Generally, the diffusion coefficient increases with increasing temperature. However, for the same type of gas, the diffusion coefficient will differ under different temperatures and pressures.

[0075] In one embodiment, Table 1 shows the standard diffusion coefficients of methane (CH4), hydrogen (H2), carbon monoxide (CO), and carbon dioxide (CO2) at standard atmospheric pressure and 25°C (corresponding to a Kelvin temperature of 298.15K). These standard diffusion coefficients can be obtained in advance, and the standard diffusion coefficients can be adjusted according to the relationship between diffusion coefficients and gas pressure and temperature to obtain the gas diffusion coefficients at the ambient temperature and ambient air pressure.

[0076] Table 1 Standard diffusion coefficients of gases at standard atmospheric pressure and 25°C (×10⁻¹⁰) -5 m 2 / s)

[0077] gas <![CDATA[CH4]]> <![CDATA[H2]]> CO <![CDATA[CO2]]> diffusion coefficient 2.2 7.8 2.3 1.8

[0078] The method for determining gas diffusion equilibrium in the buffer layer of high-voltage cables provided in this application first determines the diffusion coefficient of the gas at the corresponding ambient temperature and ambient pressure based on the ambient temperature and ambient pressure. Then, based on Fick's second law, a first gas diffusion dynamics model corresponding to the buffer layer in the high-voltage cable is constructed according to the gas diffusion coefficient of the gas in the buffer layer at the corresponding ambient temperature and ambient pressure. This model can fully reflect the influence of ambient temperature and pressure on gas diffusion and improve the accuracy of the gas diffusion dynamics model.

[0079] In one possible implementation, the gas diffusion coefficient of the gas in the buffer layer corresponding to the ambient temperature and ambient pressure of the high-voltage cable is determined, including:

[0080] Based on the ambient temperature and air pressure of the high-voltage cable, the gas diffusion coefficient of the gas in the buffer layer corresponding to the ambient temperature and air pressure is determined using the following formula:

[0081]

[0082] In the above formula, D is the gas diffusion coefficient of the gas in the buffer layer corresponding to the ambient temperature and ambient air pressure, with units of m³. 2 / s;D 298.15K The gas diffusion coefficient is given at standard atmospheric pressure and 298.15 K, in meters. 2 / s; T is the ambient temperature in K; P is the ambient air pressure in kPa, which is set to standard atmospheric pressure, i.e., 101.325 kPa, during the calculation.

[0083] For example, measuring a 1.5m long, single-core 110kV, 500mm wire. 2The changes in conductor shield temperature, metallic sheath temperature, and cable surface temperature of a cross-section cable under an applied current of 2200A were investigated. The steady-state metallic sheath temperature was measured to be approximately 49℃. Therefore, an ambient temperature of 50℃ was assumed for approximate calculations. Based on the aforementioned formula, the diffusion coefficients of methane, hydrogen, carbon monoxide, and carbon dioxide at 50℃ were calculated to be 2.51 × 10⁻⁶. -5 m 2 / s, 9.16×10 -5 m 2 / s, 2.70×10 - 5 m 2 / s and 2.11×10 -5 m 2 / s.

[0084] The method for determining gas diffusion equilibrium in the buffer layer of high-voltage cables provided in this application determines the gas diffusion coefficient based on the temperature and pressure at the gas diffusion site, providing a basis for establishing an accurate and effective gas diffusion dynamics model.

[0085] In one possible implementation, the gas diffusion coefficient is corrected for multiple factors based on the porosity and tortuosity of the buffer layer to obtain a second gas diffusion kinetic model, including:

[0086] Obtain the porosity and tortuosity of the buffer layer; determine the corrected gas diffusion coefficient by multiplying the ratio of porosity and tortuosity by the gas diffusion coefficient; and obtain the second gas diffusion kinetic model based on the corrected gas diffusion coefficient and the first gas diffusion kinetic model.

[0087] The internal air gap of the buffer layer in high-voltage cables has a helical characteristic, and the polyester fiber buffer layer is a porous material. This affects the diffusion path and diffusion rate of gas after generation in the buffer layer. Therefore, the gas diffusion kinetics model considers the porosity and tortuosity of the buffer layer and corrects the gas diffusion coefficient. The correction formula is shown in the following equation:

[0088]

[0089] Among them, D e The corrected gas diffusion coefficient is given by τ, where D is the gas diffusion coefficient determined based on ambient temperature and ambient pressure, with units of m² / s; τ is the tortuosity, dimensionless; and ε is the porosity, dimensionless.

[0090] Tortivity describes the degree of curvature of the actual diffusion path of gas molecules in a buffer layer relative to a straight path. Under ideal conditions, where the diffusion channels in a cable buffer layer are directly connected, the tortivity is close to 1. However, in real buffer layers, the gas diffusion channels are typically helical and curved. Defective gases travel along these curved paths during diffusion, leading to an increase in the actual diffusion path length and thus reducing the diffusion rate.

[0091] To calculate the tortuosity of the buffer layer between the insulated core and the aluminum sheath under fully compressed conditions, it is first necessary to determine the helix equation, which can be described by the parameterized equation shown below:

[0092]

[0093] In the above formula, r is the radius of the helix, in mm; p is the helix pitch, i.e., the thread pitch, which is the change in height in the z-direction for every 2π radians of rotation, in mm; θ is a parameter representing the angle of rotation, in rad.

[0094] When the buffer layer is in close contact with the metal sheath, the gas diffuses into a helical air gap. The tortuosity at this point can be defined as the total length of the helix divided by its height. Let the total length of the helix be L and the helix height be H, then the total length L can be calculated as:

[0095]

[0096] Where ds is the differential arc length, and the calculation formula is shown below:

[0097]

[0098] To calculate ds, we first need to calculate the derivatives of x, y, and z with respect to the variable θ:

[0099]

[0100] The differential arc length ds can be calculated:

[0101]

[0102] The helix length L can be obtained when the height is H and the pitch is p:

[0103]

[0104] Furthermore, the tortuosity τ can be calculated:

[0105]

[0106] Porosity characterizes the proportion of air gap volume to the total volume in a buffer layer. A high porosity means a large air gap space, allowing gas molecules more channels to diffuse. Conversely, a low porosity restricts gas molecule diffusion; a porosity of 1 indicates no obstruction. To calculate the porosity of the air gap in a cable buffer layer, we first need to calculate the volume V of the spiral air gap enclosed by the corrugated aluminum sheath. g and buffer band volume V b .

[0107] To calculate the volume of the spiral air gap, it is first necessary to calculate the air gap cross-section. The calculation method is shown in the following formula:

[0108]

[0109] In the above formula, h is the groove depth of the aluminum sheath during cable manufacturing, in mm; p is the groove pitch of the aluminum sheath, in mm. Therefore, at one pitch p, the area S enclosed by this function is... g It can be calculated using the following formula:

[0110]

[0111] After simplification, we get:

[0112]

[0113] Given the helix length L as shown in equation (11), the air gap volume V surrounded by the corrugated aluminum sheath can be calculated. g :

[0114]

[0115] The volume and thickness of the buffer strip are related to the outer diameter of the insulating outer shield. When the buffer strip is in close contact with the metal sheath, its volume is calculated as follows:

[0116] V b =π(r) 2 -(rt b ) 2 )H

[0117] In the above formula, r is the trough radius; t b H represents the thickness of the buffer layer after compression, typically 1-4 mm; H is the height of the corrugated aluminum sheath. Therefore, according to the definition, the porosity ε of the buffer layer is calculated using the following formula:

[0118]

[0119] The method for determining the gas diffusion balance in the buffer layer of high-voltage cables provided in this application uses the porosity and tortuosity of the buffer layer to correct the gas diffusion coefficient, accurately describing the combined influence of porous fibers and spiral channel structure on the gas diffusion coefficient, thereby obtaining a gas diffusion dynamics model that can accurately describe the gas diffusion in the buffer layer.

[0120] Figure 3 A flowchart illustrating the method for determining gas diffusion balance in the buffer layer of a high-voltage cable provided in this application embodiment. Figure 2 .like Figure 3 As shown, in one possible implementation, based on the structural characteristics of the buffer layer and according to the second gas diffusion kinetic model, a gas diffusion simulation model for high-voltage cables is constructed, including:

[0121] S301. Based on the structural characteristics of the buffer layer, and according to the forward difference approximation principle, the rate of change of gas concentration with respect to time at each sampling point is approximated by forward difference to obtain the approximate rate of change of gas concentration.

[0122] To investigate the gas diffusion along the entire length of a high-voltage cable buffer layer after gas generation due to defects, a simulation model of gas diffusion in the buffer layer of a high-voltage cable was established. The buffer layer of a high-voltage cable is typically a one-dimensional structure. Considering that each segment of high-voltage cable in the power grid is approximately 500m long, for ease of calculation, the gas diffusion in the buffer layer is simplified to a one-dimensional problem. Figure 4 This is a schematic diagram of a cable simulation model provided in an embodiment of this application. Figure 4 The interval between each gas source that generates gas is 50m, and there are 2000 sampling points, which means the distance between each sampling point is 0.25m.

[0123] To determine the gas concentration at each sampling point, the second gas diffusion kinetic model must first be converted into a difference expression, and then discretized in time and space. In one-dimensional space, the length x of the high-voltage cable is divided into equidistant sampling points x. j =jΔx, where j = 0, 1, 2, ..., N, and Δx is the spatial step size. In time, t is divided into equidistant time points ti. n = nΔt, where n = 0, 1, 2, ..., M, and Δt is the time step.

[0124] Using the forward difference approximation on the time derivative, we obtain:

[0125]

[0126] in, Let be the rate of change of gas concentration at the j-th sampling point at time n with respect to time. Let J be the gas concentration at time n+1 of the j-th sampling point. Let Δt be the gas concentration at time n of the j-th sampling point, and Δt be the time step.

[0127] S302. Based on the central difference approximation principle, the Laplace operator of the gas concentration is approximated by the central difference to obtain the approximate Laplace operator.

[0128] Using the central difference approximation on the second derivative in one-dimensional space, we obtain:

[0129]

[0130] in, Let Laplace operator be the gas concentration at time n for the j-th sampling point. Let the gas concentration at time n be the (j+1)th sampling point. Let be the gas concentration at time n for the j-th sampling point. Let Δx be the gas concentration at time n of the (j-1)th sampling point, and Δx be the spatial step size.

[0131] S303. Substitute the approximate gas concentration change rate and the approximate Laplace operator into the second gas diffusion dynamics model to obtain the gas diffusion simulation model of the high-voltage cable.

[0132] Substituting the above difference approximation scheme into the second gas diffusion dynamics model yields the gas diffusion simulation model for high-voltage cables:

[0133]

[0134] Among them, D e The gas diffusion coefficient is corrected for porosity and tortuosity; the meanings of the other parameters are the same as above.

[0135] After discretization, the original partial differential equations are reduced to a set of interconnected ordinary differential equations, and then the gas diffusion simulation model is solved using the explicit Runge-Kutta method.

[0136] In one example, the simulation model of gas diffusion in the buffer layer of a high-voltage cable was calculated using a Python program written in the py-pde library. Regarding the boundary conditions, methane and hydrogen gases were generated at 50m intervals, with a gas source length of 1m and an initial concentration of 1 mol / cm³. 3 In terms of mesh generation, the 500m long buffer layer air gap is divided into 2000 uniform meshes, and the solution time step is 180s.

[0137] The method for determining gas diffusion balance in the buffer layer of high-voltage cables provided in this application uses the forward difference approximation principle and the central difference approximation principle to transform the second gas diffusion dynamics model into a difference form that better conforms to the one-dimensional structure of the high-voltage cable. Then, by deforming the difference form of the second gas diffusion dynamics model, a gas diffusion simulation model of the high-voltage cable can be obtained, thereby realizing the simulation of gas concentration changes at each sampling point of the high-voltage cable.

[0138] In one possible implementation, the changes in gas concentration over time at multiple sampling points are compared and analyzed to obtain a judgment result on whether the gas diffusion in the buffer layer corresponding to the defect is balanced, including:

[0139] For any two sampling points among multiple sampling points, determine the difference in gas concentration between the two sampling points at the same time. If the difference between any two sampling points is less than a preset gas concentration difference threshold, the judgment result of gas diffusion balance in the buffer layer corresponding to the defect is obtained. If the difference between any two sampling points is greater than or equal to the preset gas concentration difference threshold, the judgment result of gas diffusion imbalance in the buffer layer corresponding to the defect is obtained.

[0140] Gas diffusion equilibrium in a buffer layer refers to the uniform concentration of gas in the gaps between the buffer layers. Therefore, the relationship between the gas concentration difference at different sampling points and the gas concentration difference threshold can be used to determine whether the gas in the buffer layer has reached diffusion equilibrium.

[0141] For details, please refer to Figure 2 Multiple curves were obtained showing the changes in gas concentration over time at various sampling points. It can be seen that the gas concentration is higher near the gas source and lower in areas far from the gas source in the early stage of gas diffusion. Therefore, the difference in gas concentration between sampling points near the gas source and sampling points far from the gas source is large and exceeds the preset gas concentration difference threshold. In this case, it is determined that the gas has not reached the diffusion equilibrium state.

[0142] Over time, gas diffusion causes the gas concentration at different sampling points to tend to be uniform, for example... Figure 2 The gas concentration curves over 7 days show that if the gas concentration difference between different sampling points is less than a preset gas concentration difference threshold, it can be determined that the gas has reached diffusion equilibrium. For example, the gas concentration difference threshold is 5%.

[0143] The method for determining gas diffusion balance in the buffer layer of high-voltage cables provided in this application objectively and accurately determines the gas diffusion situation in the buffer layer based on the quantitative relationship between the gas concentration difference at the sampling point and the gas concentration difference threshold, providing a reliable basis for the diagnosis of buffer layer defects.

[0144] In one possible implementation, it also includes:

[0145] The moment when the discrimination result of the gas diffusion balance of the buffer layer corresponding to the defect is obtained is taken as the target moment of the gas diffusion balance of the buffer layer corresponding to the defect.

[0146] For example, refer to Figure 2 When the diffusion time is 7 days, the difference between any two sampling points among multiple sampling points is less than the preset gas concentration difference threshold. The discrimination result of gas diffusion balance in the buffer layer corresponding to the defect is obtained, and 7 days is determined as the time when gas diffusion balance in the buffer layer of the high-voltage cable is achieved.

[0147] The method for determining gas diffusion equilibrium in the buffer layer of high-voltage cables provided in this application systematically simulates and analyzes the changes in the concentration distribution of various defective gases in the air gap of the buffer layer over time under different diffusion conditions, and quantitatively predicts their diffusion equilibrium time. This provides solid theoretical support and experimental basis for gas detection practice in the buffer layer of operating high-voltage cables, guiding technicians to rationally select gas sampling locations and scientifically determine gas sampling cycles, thereby significantly improving the accuracy and effectiveness of gas detection technology in the diagnosis of buffer layer defects.

[0148] Figure 5 This is a schematic diagram of the structure of the gas diffusion balance discrimination device in the buffer layer of the high-voltage cable provided in the embodiments of this application, as shown below. Figure 5 As shown, the gas diffusion balance determination device 50 in the buffer layer of the high-voltage cable provided in this embodiment:

[0149] The first model construction module 501 is used to respond to defects in high-voltage cables. Based on Fick's second law, it constructs a first gas diffusion dynamics model corresponding to the buffer layer in the high-voltage cable according to the ambient temperature and air pressure of the high-voltage cable. In the gas diffusion dynamics model, the rate of change of gas concentration with respect to time is equal to the product of the gas diffusion coefficient and the Laplace operator of the gas concentration.

[0150] The correction module 502 is used to perform multi-factor correction on the gas diffusion coefficient based on the porosity and tortuosity of the buffer layer to obtain the second gas diffusion dynamics model.

[0151] The second model construction module 503 is used to construct a gas diffusion simulation model of the high-voltage cable based on the structural characteristics of the buffer layer and the second gas diffusion dynamics model. The gas diffusion simulation model is used to simulate the gas diffusion at the sampling point of the high-voltage cable.

[0152] Simulation module 504 is used to simulate the change of gas concentration over time at multiple sampling points on a high-voltage cable using a gas diffusion simulation model.

[0153] Analysis module 505 is used to compare and analyze the changes in gas concentration over time at multiple sampling points to obtain a judgment result on whether the gas diffusion in the buffer layer corresponding to the defect is balanced.

[0154] In one possible implementation, the first model building module 501 is specifically used for:

[0155] Based on the ambient temperature and air pressure of the high-voltage cable, determine the gas diffusion coefficient of the gas in the buffer layer corresponding to the ambient temperature and air pressure.

[0156] Based on Fick's second law, and according to the gas diffusion coefficient of the gas in the buffer layer corresponding to the ambient temperature and ambient air pressure, a first gas diffusion dynamics model corresponding to the buffer layer in the high-voltage cable is constructed.

[0157] In one possible implementation, the first model building module 501 is further configured to:

[0158] Based on the ambient temperature and air pressure of the high-voltage cable, the gas diffusion coefficient of the gas in the buffer layer corresponding to the ambient temperature and air pressure is determined using the following formula:

[0159]

[0160] Where D is the gas diffusion coefficient of the gas in the buffer layer corresponding to the ambient temperature and ambient pressure, T is the ambient temperature, P is the ambient pressure, and D 298.15K The gas diffusion coefficient is given at 298.15 K.

[0161] In one possible implementation, the correction module 502 is specifically used for:

[0162] Obtain the porosity and tortuosity of the buffer layer;

[0163] The corrected gas diffusion coefficient is determined by multiplying the ratio of porosity to tortuosity by the gas diffusion coefficient.

[0164] Based on the corrected gas diffusion coefficient and the first gas diffusion kinetic model, the second gas diffusion kinetic model is obtained.

[0165] In one possible implementation, the second model building module 503 is specifically used for:

[0166] Based on the forward difference approximation principle, the rate of change of gas concentration with respect to time at each sampling point is approximated by forward difference to obtain the approximate rate of change of gas concentration.

[0167] Based on the central difference approximation principle, the Laplace operator of the gas concentration is approximated by the central difference to obtain the approximate Laplace operator;

[0168] Substituting the approximate gas concentration change rate and the approximate Laplace operator into the second gas diffusion dynamics model, a gas diffusion simulation model for high-voltage cables is obtained.

[0169] In one possible implementation, the analysis module 505 is specifically used for:

[0170] For any two sampling points among multiple sampling points, determine the difference in gas concentration at the same time between the two sampling points;

[0171] If the difference between any two sampling points among multiple sampling points is less than the preset gas concentration difference threshold, then the discrimination result of the gas diffusion balance of the buffer layer corresponding to the defect is obtained.

[0172] If the difference between any two sampling points among multiple sampling points is greater than or equal to the preset gas concentration difference threshold, then the discrimination result of gas diffusion imbalance in the buffer layer corresponding to the defect is obtained.

[0173] In one possible implementation, the analysis module 505 is further configured to:

[0174] The moment when the discrimination result of the gas diffusion balance of the buffer layer corresponding to the defect is obtained is taken as the target moment of the gas diffusion balance of the buffer layer corresponding to the defect.

[0175] The gas diffusion balance discrimination device in the buffer layer of the high-voltage cable provided in this embodiment can execute the method provided in the above method embodiment. Its implementation principle and technical effect are similar, and will not be described in detail here.

[0176] Figure 6 This is a schematic diagram of the structure of a device for determining gas diffusion balance in the buffer layer of a high-voltage cable, provided in an embodiment of this application. Figure 6 As shown, the gas diffusion balance discrimination device 60 in the buffer layer of the high-voltage cable provided in this embodiment includes at least one processor 601 and a memory 602. Optionally, the device 60 further includes a communication interface 603. The processor 601, memory 602, and communication interface 603 are connected via a communication bus 604.

[0177] In a specific implementation, at least one processor 601 executes computer execution instructions stored in memory 602, causing at least one processor 601 to perform the above-described method.

[0178] The specific implementation process of processor 601 can be found in the above method embodiments, and its implementation principle and technical effect are similar. It will not be repeated here.

[0179] In the above embodiments, it should be understood that the processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), etc. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the method disclosed in this invention can be directly implemented by a hardware processor, or implemented by a combination of hardware and software modules within the processor.

[0180] The memory may include random access memory (RAM) and may also include non-volatile memory (NVM), such as at least one disk storage device.

[0181] The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. Buses can be categorized as address buses, data buses, control buses, etc. For ease of illustration, the buses shown in the accompanying drawings are not limited to a single bus or a single type of bus.

[0182] This application also provides a computer program product, including a computer program that, when executed, implements the above-described method.

[0183] This application also provides a computer-readable storage medium storing computer-executable instructions, which, when executed, implement the above-described method.

[0184] The aforementioned readable storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk. The readable storage medium can be any available medium accessible to a general-purpose or special-purpose computer.

[0185] An exemplary readable storage medium is coupled to a processor, enabling the processor to read information from and write information to the readable storage medium. Of course, the readable storage medium can also be a component of the processor. The processor and the readable storage medium can reside in an application-specific integrated circuit (ASIC). Alternatively, the processor and the readable storage medium can exist as discrete components in the device.

[0186] The division of units is merely a logical functional division; in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be indirect coupling or communication connection through some interfaces, devices, or units, and may be electrical, mechanical, or other forms.

[0187] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0188] In addition, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0189] If a function is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0190] Those skilled in the art will understand that all or part of the steps of the above-described method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When executed, the program performs the steps of the above-described method embodiments; and the aforementioned storage medium includes various media capable of storing program code, such as ROM, RAM, magnetic disks, or optical disks.

[0191] Finally, it should be noted that other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A method for determining gas diffusion equilibrium in the buffer layer of a high-voltage cable, characterized in that, include: In response to a defect in the buffer layer of the high-voltage cable, based on Fick's second law and according to the ambient temperature and air pressure of the high-voltage cable, a first gas diffusion dynamics model corresponding to the buffer layer in the high-voltage cable is constructed. In the gas diffusion dynamics model, the rate of change of gas concentration with respect to time is equal to the product of the gas diffusion coefficient and the Laplace operator of the gas concentration. Based on the porosity and tortuosity of the buffer layer, the gas diffusion coefficient is corrected by multiple factors to obtain a second gas diffusion kinetic model; Based on the structural characteristics of the buffer layer, and according to the second gas diffusion dynamics model, a gas diffusion simulation model for high-voltage cables is constructed. The gas diffusion simulation model is used to simulate the gas diffusion at the sampling points of the high-voltage cables. The gas diffusion simulation model was used to simulate the changes in gas concentration over time at multiple sampling points on the high-voltage cable. By comparing and analyzing the changes in gas concentration over time at the various sampling points, a judgment result on whether the gas diffusion in the buffer layer corresponding to the defect is balanced is obtained.

2. The discrimination method according to claim 1, characterized in that, Based on Fick's second law, and according to the ambient temperature and air pressure of the high-voltage cable, a first gas diffusion dynamics model corresponding to the buffer layer in the high-voltage cable is constructed, including: Based on the ambient temperature and ambient air pressure of the high-voltage cable, determine the gas diffusion coefficient of the gas in the buffer layer corresponding to the ambient temperature and ambient air pressure. Based on Fick's second law, and according to the gas diffusion coefficient of the gas in the buffer layer corresponding to the ambient temperature and ambient pressure, a first gas diffusion dynamics model corresponding to the buffer layer in the high-voltage cable is constructed.

3. The discrimination method according to claim 2, characterized in that, The step of determining the gas diffusion coefficient of the gas in the buffer layer corresponding to the ambient temperature and ambient pressure of the high-voltage cable includes: Based on the ambient temperature and atmospheric pressure of the high-voltage cable, the gas diffusion coefficient of the gas in the buffer layer corresponding to the ambient temperature and atmospheric pressure is determined by the following formula: Wherein, D is the gas diffusion coefficient of the gas in the buffer layer corresponding to the ambient temperature and the ambient pressure, T is the ambient temperature, P is the ambient pressure, and D 298.15K The gas diffusion coefficient is given at standard atmospheric pressure and a temperature of 298.15 K.

4. The discrimination method according to any one of claims 1 to 3, characterized in that, The process of correcting the gas diffusion coefficient based on the porosity and tortuosity of the buffer layer using multiple factors to obtain a second gas diffusion kinetic model includes: The porosity and tortuosity of the buffer layer are obtained; The corrected gas diffusion coefficient is determined by multiplying the ratio of porosity to tortuosity by the gas diffusion coefficient. Based on the corrected gas diffusion coefficient and the first gas diffusion kinetic model, a second gas diffusion kinetic model is obtained.

5. The discrimination method according to any one of claims 1 to 3, characterized in that, Based on the structural characteristics of the buffer layer, and according to the second gas diffusion dynamics model, a gas diffusion simulation model for high-voltage cables is constructed, including: Based on the structural characteristics of the buffer layer, and according to the forward difference approximation principle, the rate of change of gas concentration with respect to time at each sampling point is approximated by forward difference to obtain the approximate rate of change of gas concentration. Based on the central difference approximation principle, the Laplace operator of gas concentration is approximated by the central difference to obtain the approximate Laplace operator; Substituting the approximate gas concentration change rate and the approximate Laplace operator into the second gas diffusion dynamics model, a gas diffusion simulation model for high-voltage cables is obtained.

6. The discrimination method according to any one of claims 1 to 3, characterized in that, The comparative analysis of the changes in gas concentration over time at the multiple sampling points to obtain a judgment result on whether the gas diffusion in the buffer layer corresponding to the defect is balanced includes: For any two sampling points among the multiple sampling points, determine the difference in gas concentration at the same time between the two sampling points; If the difference between any two sampling points among the multiple sampling points is less than the preset gas concentration difference threshold, then the discrimination result of the gas diffusion balance of the buffer layer corresponding to the defect is obtained. If the difference between any two sampling points among the multiple sampling points is greater than or equal to a preset gas concentration difference threshold, then the discrimination result of gas diffusion imbalance in the buffer layer corresponding to the defect is obtained.

7. The discrimination method according to any one of claims 1 to 3, characterized in that, Also includes: The moment when the discrimination result indicating the gas diffusion balance of the buffer layer corresponding to the defect is obtained is taken as the target moment for the gas diffusion balance of the buffer layer corresponding to the defect.

8. A device for determining gas diffusion balance in the buffer layer of a high-voltage cable, characterized in that, include: The first model construction module is used to respond to defects in high-voltage cables. Based on Fick's second law, and according to the ambient temperature and air pressure of the high-voltage cable, it constructs a first gas diffusion dynamics model corresponding to the buffer layer in the high-voltage cable. In the gas diffusion dynamics model, the rate of change of gas concentration with respect to time is equal to the product of the gas diffusion coefficient and the Laplace operator of the gas concentration. The correction module is used to perform multi-factor correction on the gas diffusion coefficient based on the porosity and tortuosity of the buffer layer to obtain a second gas diffusion kinetic model. The second model building module is used to build a gas diffusion simulation model of the high-voltage cable based on the structural characteristics of the buffer layer and the second gas diffusion dynamics model. The gas diffusion simulation model is used to simulate the gas diffusion at the sampling point of the high-voltage cable. The simulation module is used to simulate the changes in gas concentration over time at multiple sampling points on the high-voltage cable using the gas diffusion simulation model. The analysis module is used to compare and analyze the changes in gas concentration over time at the multiple sampling points to obtain a judgment result on whether the gas diffusion of the buffer layer corresponding to the defect is balanced.

9. A device for determining gas diffusion balance in the buffer layer of a high-voltage cable, characterized in that, include: Memory, processor; The memory stores computer-executed instructions; The processor executes computer execution instructions stored in the memory, causing the processor to perform the method as described in any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable instructions, which, when executed, are used to implement the method as described in any one of claims 1-7.

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