A method and device for risk assessment of gas leakage of a ring main unit

Abstract

The application provides a risk assessment method and device for gas leakage of a ring main unit, wherein, in the application, when it is determined that the background area of a three-dimensional infrared image includes a low-temperature area, it indicates that the target ring main unit is currently leaking. In order to determine the leakage area of the target ring main unit, the target cluster area with the lowest temperature in the low-temperature area is projected to the surface of the target ring main unit in the direction of the target cluster area, so as to determine the leakage area. Then, the concentration of the insulating gas in the target ring main unit at a future target time is predicted based on the leakage area. Then, the arcing probability and the insulation failure probability are determined according to the concentration, and then the risk assessment result is obtained. Through the above method, the probability of a chain failure (such as arcing and insulation failure) caused by the decrease of the concentration of the insulating gas can be predicted, and a relatively accurate risk assessment result can be obtained.

Description

Technical Field

[0001] This application relates to the field of ring main unit engineering technology, and more specifically, to a risk assessment method and apparatus for gas leakage in ring main units. Background Technology

[0002] Ring main units (RMMs) are critical equipment in power distribution networks, and their interiors are widely filled with gases such as SF6 as insulation and arc-quenching media. Gas leaks in RMMs can lead to a decrease in insulation strength, and in severe cases, may cause insulation failure and internal arcing faults, threatening the safe and stable operation of the power grid.

[0003] In existing technologies, leakage can be determined by monitoring changes in gas pressure or density in ring main units. However, this monitoring method cannot predict the probability of cascading failures (such as arcing or insulation failure) caused by a decrease in the concentration of insulating gas. As a result, accurate risk assessment cannot be obtained, leading to a lack of data support for operation and maintenance decisions. As a result, conservative periodic maintenance or post-event maintenance strategies are often adopted, making it difficult to balance economy and safety. Summary of the Invention

[0004] In view of this, embodiments of this application provide a risk assessment method and apparatus for gas leakage in ring main units, in order to predict the probability of cascading failures (such as arcing and insulation failure) caused by a decrease in insulating gas concentration, and obtain relatively accurate risk assessment results.

[0005] In a first aspect, embodiments of this application provide a risk assessment method for gas leakage in a ring main unit, the method comprising: After acquiring a three-dimensional infrared image of the area where the target ring network cabinet is located using a cooled infrared thermal imager, the low-temperature area in the background area of ​​the three-dimensional infrared image is determined. Based on the temperature corresponding to each pixel in the low-temperature region, the pixels in the low-temperature region are clustered to obtain multiple clustered regions; Based on the temperature of the pixels included in each cluster region, determine the target cluster region with the lowest temperature; The target cluster region is orthographically projected onto the surface of the target ring main unit in the direction of the target cluster region, so that the orthographically projected area of ​​the target cluster region is used as the equivalent leakage area. Based on the equivalent leakage area, determine the concentration of insulating gas in the target ring main unit at the future target time. Based on the concentration, the arc initiation probability and insulation failure probability of the target ring main unit are determined; A risk assessment result is generated based on the concentration, the arc initiation probability, and the insulation failure probability.

[0006] Secondly, embodiments of this application provide a risk assessment device for gas leakage in a ring main unit, the device comprising: The first determining unit is used to determine the low-temperature region in the background area of ​​the three-dimensional infrared image after acquiring a three-dimensional infrared image of the area where the target ring network cabinet is located by a cooled infrared thermal imager. A clustering unit is used to cluster the pixels in the low-temperature region according to the temperature corresponding to each pixel in the low-temperature region, so as to obtain multiple clustered regions; The second determining unit is used to determine the target clustering region with the lowest temperature based on the temperature of the pixels included in each clustering region. The projection unit is used to project the target clustering region onto the surface of the target ring network cabinet in the direction of the target clustering region, so as to use the projected area of ​​the target clustering region as the equivalent leakage area. The third determining unit is used to determine the concentration of insulating gas in the target ring main unit at a future target time based on the equivalent leakage area. The fourth determining unit is used to determine the arc initiation probability and insulation failure probability of the target ring main unit based on the concentration. The generation unit is used to generate a risk assessment result based on the concentration, the arc initiation probability, and the insulation failure probability.

[0007] The technical solution provided in this application includes, but is not limited to, the following beneficial effects: In this application, when the background area of ​​the three-dimensional infrared image is determined to include a low-temperature region, it indicates that the target ring main unit is currently leaking. In order to determine the leakage area of ​​the target ring main unit, the target cluster region with the lowest temperature in the low-temperature region can be projected onto the surface of the target ring main unit in the direction of the target cluster region, thereby determining the leakage area. Then, based on the leakage area, the concentration of insulating gas in the target ring main unit at the future target time is predicted. Then, based on the concentration, the arc initiation probability and insulation failure probability are determined, thereby obtaining the risk assessment result. Through the above method, the probability of cascading failures (such as arc initiation and insulation failure) caused by the decrease in insulating gas concentration can be predicted, and a relatively accurate risk assessment result can be obtained.

[0008] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0009] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0010] Figure 1 A flowchart illustrating a risk assessment method for gas leakage in a ring main unit provided in this application embodiment; Figure 2 A flowchart illustrating another risk assessment method for gas leakage in a ring main unit provided in this application embodiment; Figure 3 A flowchart illustrating another risk assessment method for gas leakage in a ring main unit provided in this application embodiment; Figure 4 This is a schematic diagram of a risk assessment device for gas leakage in a ring main unit, provided as an embodiment of this application. Detailed Implementation

[0011] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0012] Figure 1 A flowchart illustrating a risk assessment method for gas leakage in a ring main unit provided in this application embodiment is shown below. Figure 1 As shown, the method includes the following steps: Step 101: After obtaining a three-dimensional infrared image of the area where the target ring network cabinet is located using a cooled infrared thermal imager, determine the low-temperature area in the background area of ​​the three-dimensional infrared image.

[0013] Step 102: Based on the temperature corresponding to each pixel in the low-temperature region, cluster the pixels in the low-temperature region to obtain multiple clustered regions.

[0014] Step 103: Determine the target cluster region with the lowest temperature based on the temperature of the pixels included in each cluster region.

[0015] Step 104: Project the target clustering region onto the surface of the target ring main unit in the direction of the target clustering region, so as to use the projected area of ​​the target clustering region as the equivalent leakage area.

[0016] Step 105: Determine the concentration of insulating gas in the target ring main unit at the future target time based on the equivalent leakage area.

[0017] Step 106: Determine the arc initiation probability and insulation failure probability of the target ring main unit based on the concentration.

[0018] Step 107: Generate a risk assessment result based on the concentration, the arc initiation probability, and the insulation failure probability.

[0019] Specifically, ring main units are generally filled with insulating gas (also called inert gas) for insulation and arc extinguishing. After a leak, the temperature change of the inert gas depends primarily on whether the leak process approximates adiabatic expansion. According to thermodynamic principles, when a gas expands rapidly and adiabatously, it does work on the surrounding environment, leading to a decrease in internal energy and thus a drop in temperature. In a leak scenario, at the leak point: the inert gas is instantly released from the target ring main unit into a low-pressure environment, a typical adiabatic expansion process. Gas molecules expand rapidly upon ejection, overcoming external pressure and consuming their internal energy, thus significantly reducing the temperature. After ejecting a certain distance: the gas exchanges heat with the surrounding environment, absorbing heat, and the temperature gradually rises. Simultaneously, the gas mixes with air and undergoes turbulent diffusion during ejection, processes that also involve energy exchange and dissipation. Therefore, the temperature at the leak point is usually lower than the temperature after ejection a certain distance.

[0020] Based on the above principle, a cooled infrared thermal imager can be installed around the target ring main unit to capture three-dimensional infrared images of the target ring main unit and its surrounding environment. Alternatively, before maintenance personnel inspect the target ring main unit, they can use a handheld cooled infrared thermal imager to capture three-dimensional infrared images of the target ring main unit and its surrounding environment, so as to analyze the three-dimensional infrared images and provide data support for subsequent steps.

[0021] After obtaining a 3D infrared image, if the target ring main unit leaks, a low-temperature region will appear in the background area of ​​the 3D infrared image. This is caused by the work done by the leaking gas. Therefore, the low-temperature region in the background area can be determined by analyzing the temperature corresponding to each pixel in the 3D infrared image. Then, based on the temperature corresponding to each pixel in the low-temperature region, the pixels in the low-temperature region are clustered to obtain multiple clustered regions. Since the temperature gradually rises along the direction of gas leakage, the low-temperature region along the direction of gas leakage can be divided into multiple regions with different temperatures (i.e., multiple clustered regions). Then, the target clustered region with the lowest temperature is determined. At this time, the clustered region closest to the leak location can be determined. Since the gas has not yet expanded significantly when it is released from the leak, the projected area of ​​the target clustered region onto the surface of the target ring main unit in the direction of the target clustered region is basically equal to the area of ​​the leak. Therefore, the equivalent leakage area of ​​the target ring main unit can be obtained.

[0022] After obtaining the equivalent leakage area, the concentration of insulating gas in the target ring main unit at a future time can be calculated. This allows for the prediction of the insulating gas concentration in the target ring main unit at any given time. Since the arc initiation probability and insulation failure probability of the ring main unit are closely related to, and positively correlated with, the arc initiation probability and insulation failure probability of the target ring main unit at a future target time can be determined by the insulating gas concentration in the target ring main unit at that future target time. In other words, the arc initiation probability and insulation failure probability of the target ring main unit at a certain time can be predicted based on the insulating gas concentration in the target ring main unit at that time. Knowing the concentration, arc initiation probability, and insulation failure probability, the risk of the target ring main unit can be assessed, and the risk assessment results can be obtained, thereby providing data support for operation and maintenance decisions.

[0023] In one feasible implementation, when performing the step of determining the low-temperature region in the background region of the three-dimensional infrared image, the difference between the temperature of each pixel in the background region and the current ambient temperature can be calculated first; then, target pixels with a difference greater than a preset difference are determined, and the region formed by the target pixels is taken as the low-temperature region.

[0024] Specifically, since the insulating gas will do work on the surrounding air after leakage, and the temperature will drop, the difference between the temperature of each pixel in the background area and the current ambient temperature can be calculated. The current ambient temperature can be obtained through a temperature sensor. When the difference corresponding to a certain pixel is greater than a preset threshold difference, it means that the temperature of that pixel is low. Therefore, that pixel can be regarded as a pixel in the low temperature region. After obtaining all pixels with a difference greater than the preset threshold difference, the low temperature region in the background area of ​​the three-dimensional infrared image can be determined.

[0025] In a feasible implementation plan Figure 2 A flowchart illustrating another risk assessment method for gas leakage in a ring main unit provided in this application embodiment is shown below. Figure 2 As shown, step 102 can be achieved through the following steps: Step 201: Deduplicatively sort the temperatures corresponding to each pixel in the low-temperature region to obtain a numerical sequence.

[0026] Step 202: Divide the numerical sequence into equal parts according to the preset values ​​to obtain multiple numerical intervals.

[0027] Step 203: For each numerical interval, determine the median value of that interval.

[0028] Step 204: For each intermediate value, select the pixel point corresponding to the intermediate value that is closest to the target ring network cabinet from the low temperature region, and use the selected pixel point as the cluster center.

[0029] Step 205: Based on each cluster center, cluster the pixels in the low-temperature region to obtain multiple cluster regions.

[0030] Specifically, since the temperature gradually rises along the direction of gas leakage, the temperatures corresponding to each pixel in the low-temperature region can be deduplicated and sorted to obtain a numerical sequence. The direction of gas leakage can be determined through this numerical sequence. Then, the numerical sequence is divided equally according to a preset value. For example, when the preset value is 5, the numerical sequence can be divided into 6 parts, and the division points in the numerical sequence are found to obtain 6 numerical intervals. Then, the median value of each numerical interval is determined. However, since a value corresponds to multiple pixels in a numerical interval, or the same value can be contained in different numerical intervals, and since the temperature gradually rises along the direction of gas leakage, after obtaining the median value, the pixel in the low-temperature region closest to the target ring network cabinet can be used as the pixel corresponding to the median value. This can avoid determining an inappropriate pixel. After obtaining the pixel corresponding to the median value, these pixels are used as cluster centers to cluster the pixels in the low-temperature region, resulting in multiple cluster regions, thus completing the division of the cluster regions.

[0031] In one feasible implementation, when performing the step of determining the target cluster region with the lowest temperature based on the temperature corresponding to the pixels included in each cluster region, the highest temperature corresponding to the pixels included in each cluster region can be determined first; then, multiple highest temperatures are compared to determine the lowest temperature among the highest temperatures, so that the cluster region containing the lowest temperature is taken as the target cluster region.

[0032] It should be noted that the lowest or average temperature corresponding to the pixels included in each cluster region can also be used as a comparison standard to determine the target cluster region. The target cluster region is the cluster region in the low temperature region that is closest to the gas leak location.

[0033] In a feasible implementation, after projecting the target clustering region onto the plane of the target ring main unit in the direction of the target clustering region, since the projected position of the orthographic projection basically coincides with the gas leakage position, the position of the orthographic projection of the target clustering region can be taken as the gas leakage position. At this time, the gas leakage position of the target ring main unit can be obtained. When determining the concentration of insulating gas in the target ring main unit at a future target time based on the equivalent leakage area, the equivalent leakage area and the gas leakage position can be input into the CFD (Computational Fluid Dynamics) digital twin library for simulation to obtain the concentration of insulating gas in the target ring main unit at a future target time, so as to determine the concentration of insulating gas in the target ring main unit at a future time through simulation.

[0034] It should be noted that, in actual simulation mode, the initial concentration and pressure of the insulating gas can also be input into the CFD digital twin library to improve the accuracy of the simulation. Other simulation libraries can also be used for simulation, without specific limitations here.

[0035] In a feasible implementation plan Figure 3 A flowchart illustrating another risk assessment method for gas leakage in a ring main unit provided in this application embodiment is shown below. Figure 3 As shown, step 105 can be achieved through the following steps: Step 301: Calculate the leakage mass flow rate : ; in, For emission coefficients, The equivalent leakage area is given. The initial gas pressure of the insulating gas inside the target ring main unit. The thermal insulation index of the insulating gas is given. Let be the gas constant of the insulating gas. This represents the current ambient temperature.

[0036] Step 302: Calculate the difference between the total mass of the insulating gas filling the target ring main unit and the outflow mass, and determine the remaining mass of the insulating gas in the target ring main unit, wherein the outflow mass is the product of the leakage mass flow rate and the target leakage time.

[0037] Step 303: Based on the remaining mass and the volume of the target ring main unit, calculate the concentration of insulating gas in the target ring main unit after the target leakage time, so as to use it as the concentration of insulating gas in the target ring main unit at the future target time.

[0038] Specifically, the initial gas pressure of the insulating gas in a ring main unit is typically 0.4-0.6 MPa, while atmospheric pressure is 0.1 MPa. The initial gas pressure is 4-6 times that of atmospheric pressure. When the insulating gas leaks, it flows at the speed of sound. Therefore, the leakage mass flow rate per unit time (in kg / s) can be calculated using Formula 1. The emission coefficient is typically taken as 0.8. When the insulating gas is SF6, its adiabatic index is taken as 1.09. The gas constant can be obtained by dividing the universal gas constant by the molecular weight of the insulating gas. The universal gas is air, with a gas constant of approximately 8.314 J / (mol·K). The molecular weight of SF6 is 146.06, therefore the gas constant of SF6 is taken as 56.94 J / (kg·K). The initial ambient temperature is typically taken as 20℃. Once the equivalent leakage area and the initial gas pressure of the insulating gas in the target ring main unit are obtained, the leakage mass flow rate can be calculated.

[0039] It should be noted that all calculations are performed using numerical values, i.e., dimensionless calculations.

[0040] Assuming the pressure of the target ring main unit remains constant during gas leakage, the remaining mass of the insulating gas can be calculated by the difference between the total mass of the insulating gas filling the target ring main unit and the outflow mass. Since the outflow mass is related to the leakage time, the remaining mass of the insulating gas at a future moment can be determined. Therefore, the concentration of the insulating gas in the target ring main unit at that future moment can be calculated based on the volume of the target ring main unit.

[0041] In one feasible implementation, when determining the insulation failure probability of the target ring main unit based on the concentration, a first ratio of the concentration to the initial concentration of the insulating gas in the target ring main unit can be calculated, and this first ratio can be used as the insulation strength at the concentration; then, the product of the first breakdown voltage corresponding to the initial concentration and the insulation strength can be calculated to obtain the second breakdown voltage corresponding to the concentration; then, a second ratio of the second breakdown voltage to the peak value of the maximum possible operating phase voltage of the target ring main unit can be calculated, and this second ratio can be used as the current safety factor of the target ring main unit; wherein, when the safety factor is greater than or equal to 1.0, the insulation failure probability P1 is calculated: P1= ,when ; When the safety factor is less than 1.0, the probability of insulation failure is 100%.

[0042] Specifically, since insulation strength is positively correlated with insulating gas concentration and breakdown voltage is positively correlated with insulation strength, the insulation strength and the second breakdown voltage can be roughly calculated by using the ratio. This allows for a rough calculation of the current safety factor of the target ring main unit. Through this rough calculation, the approximate safety factor can be quickly determined, reducing the amount of calculation data.

[0043] In a feasible implementation, after obtaining the insulation failure probability, when performing the step of determining the arc initiation probability of the target ring main unit based on the concentration, the arc energy when an arc is generated in the target ring main unit can be calculated first. : = ; Then, the third ratio of the arc energy to the minimum ignition energy of the combustible material in the target ring main unit is calculated, and this third ratio is used as the ignition probability. Finally, the product of the insulation failure probability, the preset probability constant of insulation failure occurring and generating a sustainable burning arc, and the ignition probability is calculated to obtain the arc initiation probability, where... Arc voltage constant, The fault short-circuit current of the target ring main unit is given. The fault clearing time for the protection action of the target ring main unit is given. The preset probability constant for the occurrence of insulation failure and the generation of a continuous burning arc can be taken as 0.5.

[0044] In one feasible implementation, when generating a risk assessment result based on the concentration, the arc initiation probability, and the insulation failure probability, the risk level is first determined by looking up the risk level table using the concentration, the arc initiation probability, and the insulation failure probability, respectively; then, the highest risk level among the risk levels is determined as the risk assessment result.

[0045] Assuming the concentration is greater than or equal to 85%, it corresponds to risk level 1, described as normal, meaning: insulation strength is sufficient and there is no direct risk; when the concentration is greater than or equal to 70% and less than 85%, it corresponds to risk level 2, described as caution, meaning: insulation strength begins to decline and monitoring needs to be strengthened; when the concentration is greater than or equal to 50% and less than 70%, it corresponds to risk level 3, described as warning, meaning: insulation strength has significantly decreased and there is a risk of breakdown; when the concentration is less than 50%, it corresponds to risk level 4, described as dangerous, meaning: insulation is severely insufficient and the risk is extremely high.

[0046] Assuming the probability of insulation failure is less than 0.05, the corresponding risk level is 1, described as extremely low, meaning insulation failure is almost impossible; the probability of insulation failure is greater than or equal to 0.05 and less than 0.2, the corresponding risk level is 2, described as low, meaning it is possible only under extremely unfavorable conditions; the probability of insulation failure is greater than or equal to 0.2 and less than 0.5, the corresponding risk level is 3, described as medium, meaning it may occur under specific operating conditions (such as overvoltage or pollution); and the probability of insulation failure is greater than 0.5, the corresponding risk level is 4, described as high, meaning insulation failure is very likely to occur.

[0047] Assuming the probability of arc initiation is less than 0.01, the corresponding risk level is 1, described as extremely low, meaning the possibility of arc initiation is negligible; when the probability of arc initiation is greater than 0.01 and less than or equal to 0.1, the corresponding risk level is 2, described as low, meaning the possibility of arc initiation is relatively low; when the probability of arc initiation is greater than 0.1 and less than or equal to 0.3, the corresponding risk level is 3, described as moderate, meaning there is a significant risk of arc initiation; when the probability of arc initiation is greater than 0.3, the corresponding risk level is 4, described as high, meaning the possibility of arc initiation is high, requiring immediate intervention.

[0048] Having obtained the concentration, arc initiation probability, and insulation failure probability, the corresponding risk levels can be determined according to the above classification. When the risk level of the concentration is 2, the risk level of the arc initiation probability is 3, and the insulation failure probability is 3, the level descriptions corresponding to the arc initiation probability and the insulation failure probability can be determined as the risk assessment results of this evaluation. When the risk level of the concentration is 2, the risk level of the arc initiation probability is 1, and the insulation failure probability is 3, the level descriptions corresponding to the insulation failure probability can be determined as the risk assessment results of this evaluation. Furthermore, the level of the highest risk item is taken as the overall risk level.

[0049] Figure 4 This is a schematic diagram of the structure of a risk assessment device for gas leakage in a ring main unit, as provided in an embodiment of this application. Figure 4 As shown, the device includes: The first determining unit 41 is used to determine the low-temperature region in the background area of ​​the three-dimensional infrared image after acquiring a three-dimensional infrared image of the area where the target ring network cabinet is located by a cooled infrared thermal imager. Clustering unit 42 is used to cluster the pixels in the low-temperature region according to the temperature corresponding to each pixel in the low-temperature region to obtain multiple clustered regions; The second determining unit 43 is used to determine the target clustering region with the lowest temperature based on the temperature of the pixels included in each clustering region. Projection unit 44 is used to project the target clustering region onto the surface of the target ring network cabinet in the direction of the target clustering region, so as to use the projected area of ​​the target clustering region as the equivalent leakage area. The third determining unit 45 is used to determine the concentration of insulating gas in the target ring main unit at a future target time based on the equivalent leakage area. The fourth determining unit 46 is used to determine the arc initiation probability and insulation failure probability of the target ring main unit based on the concentration. The generation unit 47 is used to generate a risk assessment result based on the concentration, the arc initiation probability, and the insulation failure probability.

[0050] In one feasible implementation, when the first determining unit determines a low-temperature region in the background region of the three-dimensional infrared image, it includes: Calculate the temperature difference between each pixel in the background region and the current ambient temperature; Target pixels whose difference is greater than a preset difference are identified, and the region formed by the target pixels is designated as the low-temperature region.

[0051] In one feasible implementation, the clustering unit is used to cluster pixels in the low-temperature region according to the temperature corresponding to each pixel in the low-temperature region, and when multiple clustered regions are obtained, the following is included: The temperatures corresponding to each pixel in the low-temperature region are sorted by removing duplicates to obtain a numerical sequence; The numerical sequence is divided into multiple numerical intervals based on a preset value. For each range of values, determine the median value of that range. For each intermediate value, select the pixel point corresponding to the intermediate value that is closest to the target ring network cabinet from the low temperature region, and use the selected pixel point as the cluster center; Based on each cluster center, the pixels in the low-temperature region are clustered to obtain multiple cluster regions.

[0052] In one feasible implementation, when the second determining unit determines the target clustering region with the lowest temperature based on the temperature corresponding to the pixels included in each clustering region, it includes: Determine the highest temperature corresponding to the pixels included in each cluster region; Multiple highest temperatures are compared to determine the lowest temperature among the highest temperatures, and the cluster region containing the lowest temperature is taken as the target cluster region.

[0053] In one feasible implementation, the projection unit is further configured to use the orthographic projection location of the target clustering region as the gas leak location, and the third determining unit, when determining the concentration of insulating gas in the target ring main unit at a future target time based on the equivalent leak area, includes: The equivalent leakage area and the gas leakage location are input into the CFD digital twin library for simulation to obtain the concentration of insulating gas in the target ring main unit at the future target time.

[0054] In one feasible implementation, when the third determining unit determines the concentration of insulating gas in the target ring main unit at a future target time based on the equivalent leakage area, it includes: Calculate the leakage mass flow rate : ; in, For emission coefficients, The equivalent leakage area is given. The initial gas pressure of the insulating gas inside the target ring main unit. The thermal insulation index of the insulating gas is given. Let be the gas constant of the insulating gas. The initial ambient temperature; Calculate the difference between the total mass of the insulating gas filling the target ring main unit and the outflow mass to determine the remaining mass of the insulating gas in the target ring main unit, wherein the outflow mass is the product of the leakage mass flow rate and the target leakage duration; Based on the remaining mass and the volume of the target ring main unit, the concentration of insulating gas in the target ring main unit after the target leakage time is calculated, so as to be the concentration of insulating gas in the target ring main unit at the future target time.

[0055] In one feasible implementation, when the fourth determining unit determines the insulation failure probability of the target ring main unit based on the concentration, it includes: Calculate a first ratio between the concentration and the initial concentration of the insulating gas in the target ring main unit, and use the first ratio as the insulation strength at the concentration. The product of the first breakdown voltage at the initial concentration and the insulation strength is calculated to obtain the second breakdown voltage at the concentration. Calculate the second ratio between the second breakdown voltage and the peak value of the maximum possible operating phase voltage of the target ring main unit, and use the second ratio as the current safety factor of the target ring main unit; When the safety factor is greater than or equal to 1.0, calculate the insulation failure probability P1: P1= ,when ; When the safety factor is less than 1.0, the probability of insulation failure is 100%.

[0056] In one feasible implementation, when the fourth determining unit determines the arc initiation probability of the target ring main unit based on the concentration, it includes: Calculate the arc energy when an electric arc is generated inside the target ring main unit. : = ; in, Arc voltage constant, The fault short-circuit current of the target ring main unit is given. The fault clearing time for the protection action of the target ring main unit; Calculate the third ratio between the electric arc energy and the minimum ignition energy of the combustible material in the target ring network cabinet, and use the third ratio as the ignition probability; The arc initiation probability is obtained by multiplying the insulation failure probability, the preset insulation failure occurrence, the probability constant of generating a sustainable burning arc, and the ignition probability.

[0057] In one feasible implementation, the generation unit, when generating a risk assessment result based on the concentration, the arc initiation probability, and the insulation failure probability, includes: Using the concentration, the arc initiation probability, and the insulation failure probability, a risk level lookup table is performed to determine the risk level corresponding to the concentration, the risk level corresponding to the arc initiation probability, and the risk level corresponding to the insulation failure probability, respectively. The highest risk level in the risk hierarchy is determined as the result of the risk assessment.

[0058] about Figure 4 For explanations of the principles behind the relevant content, please refer to... Figures 1-3 The relevant content is detailed and will not be elaborated upon here.

[0059] In the embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. The apparatus embodiments described above are merely illustrative. For example, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. Furthermore, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Additionally, the displayed or discussed mutual couplings, direct couplings, or communication connections may be through some communication interfaces; indirect couplings or communication connections between devices or units may be electrical, mechanical, or other forms.

[0060] 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.

[0061] In addition, the functional units in the embodiments provided in this application 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.

[0062] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion 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 described in the various embodiments of this application. 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.

[0063] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. In addition, the terms "first", "second", "third", etc. are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0064] Finally, it should be noted that the above-described embodiments are merely specific implementations of this application, used to illustrate the technical solutions of this application, and not to limit them. The protection scope of this application is not limited thereto. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features, within the scope of the technology disclosed in this application; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application. All should be covered within the protection scope of this application. Therefore, the protection scope of this application should be determined by the protection scope of the claims.

Claims

1. A method for risk assessment of gas leakage of a ring main unit, characterized in that, The method includes: After acquiring a three-dimensional infrared image of the area where the target ring network cabinet is located using a cooled infrared thermal imager, the low-temperature area in the background area of ​​the three-dimensional infrared image is determined. The temperatures corresponding to each pixel in the low-temperature region are sorted by removing duplicates to obtain a numerical sequence; The numerical sequence is divided into multiple numerical intervals according to a preset value. When the preset value is N, the numerical sequence is divided into N+1 parts. For each range of values, determine the median value of that range. For each intermediate value, select the pixel point corresponding to the intermediate value that is closest to the target ring network cabinet from the low temperature region, and use the selected pixel point as the cluster center; Based on each cluster center, the pixels in the low-temperature region are clustered to obtain multiple clustered regions; Determine the highest temperature corresponding to the pixels included in each cluster region; By comparing multiple highest temperatures, the lowest temperature among the highest temperatures is determined, and the cluster region containing the lowest temperature is used as the target cluster region. The target cluster region is orthographically projected onto the surface of the target ring main unit in the direction of the target cluster region, so that the orthographically projected area of ​​the target cluster region is used as the equivalent leakage area. Based on the equivalent leakage area, determine the concentration of insulating gas in the target ring main unit at the future target time. Based on the concentration, the arc initiation probability and insulation failure probability of the target ring main unit are determined; A risk assessment result is generated based on the concentration, the arc initiation probability, and the insulation failure probability.

2. The risk assessment method of claim 1, wherein, Determining the low-temperature region in the background area of ​​the three-dimensional infrared image includes: Calculate the temperature difference between each pixel in the background region and the current ambient temperature; Target pixels whose difference is greater than a preset difference are identified, and the region formed by the target pixels is designated as the low-temperature region.

3. The risk assessment method of claim 1, wherein, The location of the orthographic projection of the target cluster region is taken as the gas leakage location. The determination of the concentration of insulating gas in the target ring main unit at a future target time based on the equivalent leakage area includes: The equivalent leakage area and the gas leakage location are input into the CFD digital twin library for simulation to obtain the concentration of insulating gas in the target ring main unit at the future target time.

4. The risk assessment method of claim 1, wherein, The step of determining the concentration of insulating gas in the target ring main unit at a future target time based on the equivalent leakage area includes: Computing a leak mass flow : ； wherein, is the emission coefficient, is the equivalent leakage area, is the initial gas pressure of the insulation gas in the target ring main unit, is the adiabatic exponent of the insulation gas, is the gas constant of the insulation gas, is the initial ambient temperature; Calculate the difference between the total mass of the insulating gas filling the target ring main unit and the outflow mass to determine the remaining mass of the insulating gas in the target ring main unit, wherein the outflow mass is the product of the leakage mass flow rate and the target leakage duration; Based on the remaining mass and the volume of the target ring main unit, the concentration of insulating gas in the target ring main unit after the target leakage time is calculated, so as to be the concentration of insulating gas in the target ring main unit at the future target time.

5. The risk assessment method as described in claim 1, characterized in that, Determining the insulation failure probability of the target ring main unit based on the concentration includes: Calculate a first ratio between the concentration and the initial concentration of the insulating gas in the target ring main unit, and use the first ratio as the insulation strength at the concentration. The product of the first breakdown voltage at the initial concentration and the insulation strength is calculated to obtain the second breakdown voltage at the concentration. Calculate the second ratio between the second breakdown voltage and the maximum operating phase voltage of the target ring main unit, and use the second ratio as the current safety factor of the target ring main unit; When the safety factor is greater than or equal to 1.0, calculate the insulation failure probability P1: P1= ,when ; When the safety factor is less than 1.0, the probability of insulation failure is 100%.

6. The risk assessment method as described in claim 5, characterized in that, Determining the arc initiation probability of the target ring main unit based on the concentration includes: Calculate the arc energy when an electric arc is generated inside the target ring main unit. : = ； in, Arc voltage constant, The fault short-circuit current of the target ring main unit is given. The fault clearing time for the protection action of the target ring main unit; Calculate the third ratio between the electric arc energy and the minimum ignition energy of the combustible material in the target ring network cabinet, and use the third ratio as the ignition probability; The arc initiation probability is obtained by multiplying the insulation failure probability, the preset insulation failure occurrence, the probability constant of generating a sustainable burning arc, and the ignition probability.

7. The risk assessment method as described in claim 1, characterized in that, The process of generating a risk assessment result based on the concentration, the arc initiation probability, and the insulation failure probability includes: Using the concentration, the arc initiation probability, and the insulation failure probability, a risk level lookup table is performed to determine the risk level corresponding to the concentration, the risk level corresponding to the arc initiation probability, and the risk level corresponding to the insulation failure probability, respectively. The highest risk level in the risk hierarchy is determined as the result of the risk assessment.

8. A risk assessment device for gas leakage in a ring main unit, characterized in that, The device includes: The first determining unit is used to determine the low-temperature region in the background area of ​​the three-dimensional infrared image after acquiring a three-dimensional infrared image of the area where the target ring network cabinet is located by a cooled infrared thermal imager. A clustering unit is used to cluster the pixels in the low-temperature region according to the temperature corresponding to each pixel in the low-temperature region, so as to obtain multiple clustered regions; The second determining unit is used to determine the target clustering region with the lowest temperature based on the temperature of the pixels included in each clustering region. The projection unit is used to project the target clustering region onto the surface of the target ring network cabinet in the direction of the target clustering region, so as to use the projected area of ​​the target clustering region as the equivalent leakage area. The third determining unit is used to determine the concentration of insulating gas in the target ring main unit at a future target time based on the equivalent leakage area. The fourth determining unit is used to determine the arc initiation probability and insulation failure probability of the target ring main unit based on the concentration. The generation unit is used to generate a risk assessment result based on the concentration, the arc initiation probability, and the insulation failure probability. Wherein, the clustering unit is used to cluster the pixels in the low-temperature region according to the temperature corresponding to each pixel in the low-temperature region, and when multiple clustered regions are obtained, it includes: The temperatures corresponding to each pixel in the low-temperature region are sorted by removing duplicates to obtain a numerical sequence; The numerical sequence is divided into multiple numerical intervals according to a preset value. When the preset value is N, the numerical sequence is divided into N+1 parts. For each range of values, determine the median value of that range. For each intermediate value, select the pixel point corresponding to the intermediate value that is closest to the target ring network cabinet from the low temperature region, and use the selected pixel point as the cluster center; Based on each cluster center, the pixels in the low-temperature region are clustered to obtain multiple clustered regions; When the second determining unit determines the target clustering region with the lowest temperature based on the temperature corresponding to the pixels included in each clustering region, it includes: Determine the highest temperature corresponding to the pixels included in each cluster region; Multiple highest temperatures are compared to determine the lowest temperature among the highest temperatures, and the cluster region containing the lowest temperature is taken as the target cluster region.

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