Method for analyzing electric field of composite post insulator under different contamination forms and risk assessment system

Abstract

This invention belongs to the field of electrical equipment technology and discloses a method for electric field analysis and a risk assessment system for composite post insulators under different pollution conditions. The system identifies the skirts most severely affected by pollution by analyzing the differences in electric field characteristics of insulators under clean, fully covered dry pollution, and fully covered wet pollution conditions. Wet pollution is applied sequentially to the skirt surface with different coverage areas and locations, and its impact on electric field characteristics is analyzed in detail. By calculating the electric field distortion rate, the pollution flashover risk level under different conditions is defined, and corresponding solutions are proposed based on the risk level. This method provides a scientific basis for daily cleaning and maintenance strategies for insulators, especially in the application of live water flushing operations, improving the operation and maintenance efficiency of insulators and reducing the probability of pollution flashover accidents. The quantitative analysis of this invention can help accurately determine the degree of insulator pollution, has broad application prospects, and can significantly improve the safety and operational reliability of power systems.

Description

Technical Field

[0001] This invention belongs to the field of power system technology, and in particular relates to a method for electric field analysis and risk assessment system for composite post insulators under different pollution conditions. Background Technology

[0002] Composite post insulators are easy to install and resistant to flashover due to pollution, and have been widely used in transmission lines in recent years. Their operational stability is crucial to the safety of power system operation. Post insulators, as important electrical equipment, are widely used in transmission lines. Because they are exposed to air, their sheaths easily accumulate dirt. This dirt can cause distortion of the electric field along the insulator surface, leading to insulation aging, flashover, and even power outages. The dirt on the sheaths can be dry or wet, and the coverage area and location of the dirt vary depending on the weather conditions. This dirt, whether dry or wet, causes distortion of the electric field along the insulator surface, resulting in insulation aging, flashover, affecting power supply stability, and even causing serious power outages. Therefore, it is necessary to investigate the effects of different types of dirt on the distribution of the electric field on the insulator surface. In this regard, scholars both domestically and internationally have conducted a series of inventions and achieved certain results.

[0003] Because water droplets easily form on the surface of insulators during foggy weather, accumulating at the tips, Wu Guangning, Shao Mengchun, and others invented a study on the distortion characteristics of the electric field strength along the surface of the insulator during the dripping process of the accumulated water droplets. Li Gang, Li Yanzhe, and others covered the surface of QBG-25 model cantilever insulators with clean snow and dirty snow respectively, and analyzed the changes in the electric field strength along the surface of the insulator during snow accumulation. Bi Maoqiang, Li Kai, and others modified the structure of the ICOG corona ring and invented the effect of different bird droppings parameters on the flashover of insulators with ICOG corona rings. Xia Xin, Dan Shuheng, and others analyzed the electric field of 10kV lightning protection insulators and optimized the parameters of the arc-starting plate to reduce its impact on the electric field of the insulator. Zhang Zhijin, Zhang Hang, and others simulated the natural icing process on three different types of insulators and invented the phenomenon of insulator string icing flashover. Jia Zhidong, Ouyang Xiaogang, and others invented the AC flashover characteristics of insulators when the degree of algae contamination on the insulator surface is different. Zhou Xudong, Lin Xin, and others modified the temperature field of the basin-type insulator and analyzed the changes in the electric field distribution along the insulator surface under different ambient temperatures. Yang Lin, Sun Yijie, and others invented a study on the dynamic deformation of raindrops on the surface of hollow magnetic insulators under extreme rainfall conditions, and also invented a study on the changing trend of the maximum electric field between insulator umbrellas during the dynamic deformation of raindrops. Suhaib Al-Karawi, Aws Al-Taie, and others coated the insulator surface with three hydrophobic materials: Al2O3, RTV-SR, and PTFE. They found that compared with the other two materials, the insulator with PTFE coating had better flashover resistance under pollution conditions. HR Sezavar, N. Fahimi, and others invented a study on the probability of flashover when the insulator is polluted with a dry zone, and proposed a novel risk assessment method for outdoor polluted insulators.

[0004] Significant progress has been made in the research of existing technologies for insulator contamination flashover problems, but the following technical issues still exist in industrial applications:

[0005] 1. Lack of quantitative correlation between pollution accumulation range and flashover risk: Although existing studies have extensively explored the relationship between different pollutants (such as water droplets, snow, bird droppings, algae, etc.) and insulator flashover, most studies focus on phenomenological analysis under specific conditions, lacking quantitative research on the relationship between the pollution accumulation range and location of composite insulators and flashover. This deficiency makes it impossible to accurately assess the flashover risk under different pollution conditions, limiting the reliability prediction in practical applications.

[0006] 2. Insufficient systematic research on the types of contaminants on insulator surfaces and their impact from environmental conditions: While preliminary analyses have been conducted on the effects of various environmental factors, such as temperature, humidity, rainfall, and icing, on the accumulation and deformation of contaminants on insulator surfaces, these studies primarily focus on single contaminants or specific environmental conditions. A systematic study of insulator performance under combined contaminants and complex environmental factors (such as the coexistence of multiple contaminants and extreme weather conditions) is lacking, making it difficult to provide comprehensive guidance for insulator design under different environmental conditions.

[0007] 3. Lack of understanding of the relationship between composite insulator structure optimization and flashover performance: Currently, optimization of insulator structures such as corona rings and arc-starting plates has been applied to traditional ceramic or glass insulators. However, due to their unique material and structural characteristics, composite insulators have received less research in areas such as optimizing electric field distribution and reducing the risk of pollution flashover. This results in relatively insufficient pollution flashover protection performance of existing composite insulators in complex environments, hindering their widespread application.

[0008] 4. Insufficient long-term performance evaluation under pollution conditions: Existing technologies have relatively more short-term studies on the pollution deformation, pollution thickness, and insulation performance of insulator surfaces, but lack evaluation of insulator flashover performance under long-term pollution conditions. This deficiency makes it difficult to accurately predict the performance of insulators after long-term operation in practical applications, thus posing safety hazards and affecting the operational stability of the power system.

[0009] 5. Lack of quantitative methods for pollution risk assessment: Although some pollution risk assessment methods have been proposed, such as flashover probability calculation for different types of pollutants, most of these methods are based on laboratory conditions and lack quantitative assessment in real complex environments. Especially in the application of composite insulators, the types of pollutants, environmental conditions and insulator structures are complex and variable, and the reliability and application of assessment models still need to be further improved.

[0010] Overall, existing technologies have not yet fully resolved the quantitative relationship between the location and extent of pollution accumulation and the risk of flashover in composite insulators in industrial applications. The lack of systematic research and long-term evaluation has restricted the reliable operation and widespread application of insulators in complex environments. Summary of the Invention

[0011] To address the problems existing in the prior art, this invention provides a method and system for analyzing the electric field of composite post insulators under different pollution conditions.

[0012] This invention is implemented as follows: a method for analyzing the electric field of composite post insulators under different pollution conditions. A rated voltage of 110 kV is applied to the composite post insulator, and the finite element method is used for calculation and analysis. Specifically, the method includes the following steps:

[0013] Step 1: Analyze the differences in electric field characteristics of composite post insulators when they are clean, fully covered with dry contamination, and fully covered with wet contamination, and identify the skirts most severely affected by contamination.

[0014] First, the electric field intensity distribution along the surface of the composite insulator is calculated under clean conditions. Then, dirt is uniformly covered on all surfaces of the insulator skirts, and the dirt is defined as dry dirt and wet dirt. The electric field intensity distribution along the surface of the insulator under dry dirt and wet dirt conditions is calculated respectively. The electric field intensity distribution is compared with that under clean conditions to find the skirts most severely affected by dirt. Then, the changes in the electric field intensity are calculated and analyzed when the range and position of dirt accumulation on the surface of this skirt change.

[0015] Step 2: Apply wet contaminants with different coverage areas and locations to the upper surface of the sheds of the composite post insulator; analyze the influence of the contaminant coverage area and location on the electric field characteristics of the insulator.

[0016] The insulator surface field strength changes when the upper surface of the umbrella skirt is covered with dirt of the same thickness and state, the upper surface of the umbrella skirt is completely covered with dirt, 2 / 3 of the area is covered with dirt, and 1 / 3 of the area is covered with dirt.

[0017] The changes in the electric field along the surface of the insulator were analyzed when the insulator was covered with dirt of the same extent and condition on the upper surface of the umbrella skirt, respectively, when the dirt covered the front, middle and rear sections of the upper surface of the umbrella skirt.

[0018] Calculate the electric field distortion rate for each condition, and determine the risk level and countermeasures for each pollution condition according to the predefined risk range.

[0019] Furthermore, this composite post insulator has a total of 25 skirts, with one large skirt and two small skirts arranged in sequence, from the high-voltage end to the grounding end, and the skirts are numbered from 1 to 25.

[0020] Furthermore, the composite post insulator's shed material is silicone rubber, with a rated voltage of 110kV; in the simulation calculation, a high potential is applied... The electric potential, with an electric field frequency of 50Hz, is calculated using the current field module in COMSOL.

[0021] Furthermore, under natural conditions, the surface of an insulator is covered with a fine layer of dirt. Therefore, the dirt on the surface of the insulator is designed to be a uniform dirt layer of 1 mm.

[0022] Furthermore, to reflect changes in the electric field, the electric field distortion rate is defined. :

[0023] (1)

[0024] (2)

[0025] in The peak field strength when a certain umbrella skirt is contaminated. The peak field strength when the umbrella skirt is clean. This represents the change in electric field strength due to contamination of the umbrella skirt compared to the clean state.

[0026] Furthermore, four risk levels for insulator flashover are defined here. A field distortion rate greater than 50% is considered dangerous, indicating a significant decrease in insulator insulation performance and a high risk of flashover accidents, requiring immediate live-line water cleaning. A field distortion rate between 50% and 35% is considered high-risk, requiring a cleaning strategy to be developed as soon as possible. A field distortion rate between 35% and 20% is considered medium-risk, indicating generally acceptable insulator safety performance, but cleaning should be considered in situations with high humidity. A field distortion rate between 20% and 10% is considered low-risk, indicating minimal field distortion and a low probability of flashover, generally requiring no cleaning. A field distortion rate less than 10% is defined as low-risk, indicating minimal impact of pollution on insulator insulation performance, with changes in the insulator's electric field remaining within a safe range.

[0027] Furthermore, the electric field distribution along the surface of the insulator is approximately symmetrical. The electric field strength is greater near the sheds of the fittings on both sides, making them prone to flashover. When the surface of the insulator is covered with dirt, the electric field strength of the insulator will increase. The electric field distortion is most severe at the No. 1 shed. Since wet dirt has better conductivity, the electric field distortion caused by wet dirt is greater than that caused by dry dirt.

[0028] Furthermore, at the No. 1 umbrella skirt, the larger the area of ​​dirt covering the upper surface of the umbrella skirt, the greater the field strength distortion along the umbrella skirt edge;

[0029] At the No. 1 umbrella skirt, the closer the dirt covering the upper surface of the umbrella skirt is to the edge of the umbrella skirt, the greater the distortion of the field strength along the umbrella skirt edge; when the dirt covers the back of the umbrella skirt, it has little effect on the field strength of the umbrella skirt.

[0030] Another object of the present invention is to provide a pollution flashover risk assessment system for composite post insulators under different pollution morphologies, comprising:

[0031] The umbrella skirt determination module analyzes the differences in electric field characteristics when the composite post insulator is clean, fully covered with dry pollution, and fully covered with wet pollution, and identifies the umbrella skirt most severely affected by pollution.

[0032] The electric field characteristic analysis module applies wet contaminants with different coverage areas and locations to the upper surface of the sheds of the composite post insulator; and analyzes the influence of the contaminant coverage area and location on the electric field characteristics of the insulator.

[0033] The risk assessment module calculates the electric field distortion rate under different pollution conditions and assigns a risk rating to the occurrence of flashover based on the magnitude of the electric field distortion rate. Under standard atmospheric pressure, the breakdown field strength of air is approximately 30 kV / cm.

[0034] Calculations show that under clean conditions and at rated voltage, the maximum electric field strength of this type of insulator is 22.36 kV / cm. If the air breakdown field strength is reached, the electric field distortion rate is 34.17%. Therefore, when the electric field distortion rate is less than approximately 35%, the insulator's electric field strength is within a relatively safe range. Four insulator flashover risk levels are defined. A field distortion rate greater than 50% indicates a dangerous risk level, where the insulator's insulation performance significantly deteriorates, increasing the risk of flashover accidents. Immediate live-line water cleaning is necessary. A field distortion rate between 35% and 50% indicates a high risk level, requiring a cleaning strategy to be developed as soon as possible. A field distortion rate between 20% and 25% indicates a medium risk level, with generally acceptable insulator safety performance; cleaning should be considered in situations with high humidity. A field distortion rate between 10% and 20% indicates a low risk level, with minimal field distortion and a low probability of flashover; cleaning is generally not required. A field distortion rate less than 10% is defined as low risk, where contamination has almost no impact on the insulator's insulation performance, and changes in the insulator's electric field are within a safe range. By analyzing the field distortion rate, we can intuitively understand the changes in insulation field strength and develop scientific and efficient cleaning strategies based on the risk level.

[0035] Based on the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solution to be protected by this invention are as follows:

[0036] First, this invention uses the FZ-110 / 5 type composite post insulator as the subject of the invention and employs COMSOL finite element analysis software for calculation and analysis. Compared with other inventions, this invention mainly focuses on the quantitative analysis of the changes in the electric field intensity along the insulator surface when the size and location of pollution coverage vary, based on the electric field distortion rate.

[0037] First, the differences in electric field characteristics of insulators under clean, fully dry-contaminated, and fully wet-contaminated conditions were analyzed. The analysis revealed that compared to the clean state, the electric field strength increased when all surfaces of the insulator skirts were uniformly covered with dry contaminants; the electric field strength increased significantly when all surfaces were uniformly covered with wet contaminants, with the most significant changes observed between the first and last skirts. To investigate the impact of the contamination coverage area and location on the insulator's electric field characteristics, wet contaminants with varying coverage areas and locations were applied sequentially to the upper surface of insulator skirt 1. The analysis showed that the larger the contamination coverage area, the higher the electric field strength at the insulator tip, making flashover more likely; when the contamination coverage area was the same, the closer the contaminant was to the insulator tip, the more prone the insulator was to flashover. Inventing the electric field distribution characteristics under different contamination morphologies on the insulator skirt surface is beneficial for determining the flashover risk of insulators, facilitating the scientific formulation of live-line water flushing strategies for insulators, improving the efficiency of daily insulator maintenance, and reducing economic losses caused by flashover.

[0038] Based on finite element simulation, this invention investigates the coverage range and location of contamination on the surface of the sheds of the FZ-110 / 5 type composite post insulator, and draws the following conclusions:

[0039] (1) The electric field distribution along the surface of the insulator is approximately symmetrical. The electric field strength is greater near the sheds of the fittings on both sides, making flashover more likely. When the surface of the insulator is covered with dirt, the electric field strength of the insulator will increase. The electric field distortion is most severe at shed No. 1. Because wet dirt has better conductivity, the electric field distortion caused by wet dirt is greater than that caused by dry dirt.

[0040] (2) At the No. 1 umbrella skirt, the larger the area of ​​dirt covering the upper surface of the umbrella skirt, the greater the field strength distortion along the umbrella skirt edge.

[0041] (3) At the No. 1 umbrella skirt, the closer the dirt covering the upper surface of the umbrella skirt is to the edge of the umbrella skirt, the greater the distortion of the field strength along the umbrella skirt. When the dirt covers the rear part of the umbrella skirt, it has little effect on the field strength of the umbrella skirt.

[0042] (4) At the No. 1 umbrella skirt, when the upper surface of the umbrella skirt is completely covered by wet dirt, the electric field distortion rate is 61.09%, and the risk level is dangerous. The insulator should be washed with live water immediately. When the wet dirt covers 2 / 3 of the area, the electric field distortion rate is 48.12%, and the risk level is high. The insulator should be cleaned as soon as possible. When the wet dirt covers 1 / 3 of the area, the electric field distortion rate is 21.82%, and the risk level is medium risk, close to low risk. The insulator should be cleaned as needed.

[0043] (5) At the No. 1 umbrella skirt, when the wet dirt covers the front section of the umbrella skirt, the electric field distortion rate is 21.82%, and the risk level is medium risk, which has little impact on the electric field of the insulator; when the wet dirt covers the middle section, the electric field distortion rate is 11.72%, and the risk level is low risk; when the wet dirt covers the rear section, the electric field distortion rate is 5.90%, and the risk level is low risk, so the insulator does not need to be cleaned.

[0044] Second, the expected benefits and commercial value of the technical solution of this invention after transformation are as follows:

[0045] Pollution flashover is most likely to occur at the sheds at both ends of composite post insulators. Analyzing the electric field distribution characteristics under different surface contamination conditions can determine the electric field distortion rate, and the magnitude of the electric field distortion rate can determine the risk level of pollution flashover. Based on the risk level, a scientific strategy for live-line water flushing of insulators can be formulated, providing guidance for on-site equipment operation and maintenance, improving the efficiency of daily insulator operation and maintenance, and has significant practical implications.

[0046] The technical solution of this invention fills a technological gap in the industry both domestically and internationally: currently, there are few inventions that quantitatively address the relationship between the range and location of pollution accumulation and flashover in composite insulators. This invention quantitatively analyzes the risk level of flashover in insulators under different pollution conditions, thereby determining the degree of pollution of the insulator based on the risk level.

[0047] Third, the technical solution of this invention solves the following key problems in the prior art in industrial applications and achieves significant technological progress:

[0048] 1. Existing technical problem: Uneven electric field distribution leads to decreased insulator performance.

[0049] Traditional composite post insulators are prone to electric field imbalance when covered by pollution, especially under different pollution conditions, where the electric field strength on the insulator surface varies significantly, easily leading to partial discharge or flashover and affecting insulation performance. This invention, through electric field analysis of different pollution conditions, identifies the areas of the sheds most severely affected by pollution, effectively identifying and optimizing the insulator structure design to improve its pollution resistance.

[0050] 2. Existing technical problem: The impact of contamination coverage cannot be effectively assessed.

[0051] Traditional electric field analysis methods struggle to accurately assess the impact of pollution coverage and location on electric field distribution, hindering the implementation of targeted countermeasures in insulator design and maintenance. This invention, by introducing the finite element method and combining electric field calculations under various pollution conditions, provides an in-depth analysis of the influence of pollution coverage and location on electric field characteristics. This offers a theoretical basis for the rational design of insulators and solves the problem of inaccurate assessments in existing technologies.

[0052] 3. Existing technical issues: Lack of targeted testing and maintenance measures.

[0053] In existing technologies, the detection and maintenance of insulators under different pollution conditions mainly rely on experience and lack scientific basis. This invention, by simulating and analyzing the electric field changes under different pollution conditions, can accurately identify which areas experience the most severe electric field distortion when covered by pollution. By introducing the electric field distortion rate, it determines the risk level of flashover of the insulator, effectively helping power engineers to clean and maintain insulators in a targeted manner and reducing the risk of insulator failure.

[0054] 4. Significant technological advancements: improving the stability and reliability of insulators.

[0055] This invention not only solves problems such as uneven electric field and inaccurate detection, but also identifies the most vulnerable skirt areas through in-depth analysis of the pollution coverage and location, and proposes an optimized design scheme to improve the electric field distribution. It also proposes an insulator risk assessment scheme, using electric field distortion rate to determine the risk level of insulator flashover, and suggests corresponding insulator maintenance methods. Maintenance personnel can scientifically formulate insulator cleaning strategies based on risk levels, significantly improving the stability and reliability of insulators, and has significant application value in power systems. Attached Figure Description

[0056] Figure 1 This is a structural diagram of the sample provided in an embodiment of the present invention;

[0057] Figure 2 This is a two-dimensional axisymmetric model diagram of an insulator provided in an embodiment of the present invention;

[0058] Figure 3 This is a surface electric field distribution diagram of an insulator when it is clean, provided in an embodiment of the present invention;

[0059] Figure 4 This is a field strength diagram along the surface of the insulator during cleanliness, provided in an embodiment of the present invention.

[0060] Figure 5 This is a schematic diagram of the dirt layer provided in an embodiment of the present invention;

[0061] Figure 6 This is a field strength diagram along the surface of the insulator during dry contamination, provided in an embodiment of the present invention.

[0062] Figure 7 This is a comparison diagram of the surface electric field strength of the insulator under clean and dry conditions provided in the embodiments of the present invention;

[0063] Figure 8 This is a field strength diagram along the surface of the insulator under wet contamination provided in an embodiment of the present invention;

[0064] Figure 9This is a comparison diagram of the surface electric field strength of the insulator under clean and wet conditions provided in an embodiment of the present invention;

[0065] Figure 10 This is a comparison diagram of the surface electric field strength of clean, dry, and wet insulators provided in the embodiments of the present invention;

[0066] Figure 11 These are model diagrams showing different levels of soil coverage provided in embodiments of the present invention;

[0067] Figure 12 These are electric field distribution diagrams of different coverage areas of umbrella skirt No. 1 provided in the embodiments of the present invention: (a) Electric field distribution along the surface when the upper surface of umbrella skirt No. 1 is fully covered by dirt, (b) Electric field distribution along the surface when the upper surface of umbrella skirt No. 1 is 2 / 3 covered by dirt, and (c) Electric field distribution along the surface when the upper surface of umbrella skirt No. 1 is 1 / 3 covered by dirt.

[0068] Figure 13 This is a comparison diagram of field strength when the pollution coverage area is different, provided in an embodiment of the present invention;

[0069] Figure 14 These are model diagrams showing different locations of soiling coverage provided in embodiments of the present invention;

[0070] Figure 15 The electric field distribution diagrams of the No. 1 umbrella skirt with different coverage positions provided in the embodiments of the present invention are as follows: (1) Electric field distribution along the surface when the dirt covers the front section of the No. 1 umbrella skirt; (2) Electric field distribution along the surface when the dirt covers the middle section of the No. 1 umbrella skirt; (3) Electric field distribution along the surface when the dirt covers the rear section of the No. 1 umbrella skirt.

[0071] Figure 16 This is a comparison diagram of field strength at different locations of soiling coverage provided in an embodiment of the present invention;

[0072] Figure 17 This is a flowchart of the electric field analysis method for composite post insulators under different pollution morphologies provided in this embodiment of the invention;

[0073] Figure 18 This is a structural diagram of the electric field analysis system for composite post insulators under different pollution morphologies provided in this embodiment of the invention. Detailed Implementation

[0074] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0075] The electric field analysis method for composite post insulators under different pollution conditions provided by this invention analyzes their electric field characteristics by applying a 110 kV rated voltage to the insulator and combining it with the finite element method, revealing the influence of pollution coverage on the electric field intensity distribution of the insulator. Its working principle can be divided into the following steps:

[0076] First, under clean conditions, the distribution of the electric field intensity along the surface of the insulator is calculated. Numerical simulation is used to obtain the electric field intensity at various points on the clean insulator skirt surface, serving as a baseline reference value. Then, the entire skirt surface of the insulator is uniformly covered with contaminants, categorized into dry and wet contaminants. The electric field intensity distribution of the insulator under both dry and wet contaminant conditions is calculated separately. By comparing the differences in electric field distribution between the clean and contaminated states, the skirt sections most severely affected by the contamination are identified.

[0077] Next, we focus on analyzing the insulator skirt, which is most severely affected by contamination. When the extent or location of contamination on the skirt's surface changes, the electric field strength also changes. Through finite element analysis, we can accurately calculate the changes in the electric field strength distribution on the skirt surface under different contamination coverage and locations. For example, when contamination is mainly concentrated at the front, middle, or rear of the skirt, the electric field strength distribution will differ. This process helps to understand the degree to which contamination accumulation at different locations affects the insulator's electric field distribution.

[0078] Then, the analysis was conducted for cases with different levels of contamination coverage. When the same level of contamination was applied to the upper surface of the insulator skirt, but the coverage areas were 1 / 3, 2 / 3, and full coverage, the electric field intensity distribution exhibited different trends. Through calculation and analysis of these changes, the influence of contamination coverage on the electric field distribution along the insulator surface could be revealed, and the region with the most severe electric field intensity under a specific coverage area could be identified.

[0079] Finally, the changes in electric field strength were further analyzed when the front, middle, and rear ends of the insulator skirt were covered with contaminants. These analyses revealed the mechanism by which the location of contaminant coverage affects the electric field distribution of the insulator, clarifying how contaminant accumulation at different locations leads to electric field distortion. This analytical method not only provides a basis for contaminant cleaning but also offers a reference for insulator design and maintenance, improving the stability and reliability of power equipment.

[0080] This invention takes the FZ-110 / 5 type composite post insulator as the analysis object, applies a rated voltage of 110 kV to the insulator, and uses the finite element algorithm for calculation and analysis.

[0081] like Figure 17As shown, the differences in electric field characteristics of insulators under clean, fully dry-soil-covered, and fully wet-soil-covered conditions are first analyzed. The analysis reveals that compared to the clean state, the electric field strength is increased when all surfaces of the insulator skirts are uniformly covered with dry-soil; the electric field strength is significantly increased when all surfaces are uniformly covered with wet-soil, with the most significant changes in electric field strength observed between the first and last insulator skirts.

[0082] To analyze the impact of the extent and location of contamination on the upper surface of the insulator skirts on the electric field characteristics of the insulator, wet contaminants with varying coverage areas and locations were sequentially applied to the upper surface of insulator skirt No. 1. Analysis revealed that a larger contamination area on the upper surface resulted in a higher electric field strength at the insulator tip, making flashover more likely. When the contamination coverage area was the same, the closer the contaminant was to the insulator tip, the more prone the insulator was to flashover. This discovery of the electric field distribution characteristics under different contamination morphologies on the insulator skirt surface is beneficial for scientifically developing live-line water flushing strategies for insulators and improving the efficiency of daily insulator maintenance.

[0083] 1. Calculation Model and Parameters

[0084] 1.1 Insulator Model and Parameters

[0085] This invention uses the FZ-110 / 5 type post composite insulator as the subject of the invention. The structural diagram and modeling diagram of the prototype are as follows: Figure 1 As shown in Table 1, the structural parameters of the sample are as follows. The sample has a total of 25 skirts, with one large skirt and two small skirts arranged sequentially. For ease of discussion later, the skirts are numbered 1 to 25 from the high-voltage end to the grounding end.

[0086] Table 1 Sample structural parameters

[0087]

[0088] The insulator in this test sample has an axisymmetric shape. To simplify calculations, a two-dimensional axisymmetric model is established for the insulator, including a circular air region with a radius of 2.3m near the insulator. Figure 2 As shown. This simulation only focuses on the insulator itself, calculating the electric field distribution within the insulator and its relatively small surrounding area, ignoring the influence of the pantograph and contact wire.

[0089] 1.2 Condition Settings and Material Parameters

[0090] The composite post insulator tested was made of silicone rubber with a rated voltage of 110kV. In the simulation, a high potential was applied with an electric field frequency of 50Hz, and the calculations were performed using the current field module in COMSOL. The relative permittivity of the composite post insulator material and the pollution are shown in Table 2.

[0091] Table 2 Material Parameters

[0092]

[0093] Insulator surfaces are often covered with a thin, fine layer of dust; therefore, in subsequent inventions, the contamination on the insulator surface is set to a uniform 1mm contamination layer. There are two states of contamination: normally, the contamination is dry; in light rain, the contamination is thoroughly moistened to form wet contamination. The relative permittivity of dry contamination is set to 2.8, and the relative permittivity of wet contamination is set to 35. The specific analysis method is as follows:

[0094] (1) First, calculate the electric field intensity distribution along the surface of the composite insulator under clean conditions. Then, uniformly cover all surfaces of the insulator skirts with dirt, defining the dirt as dry dirt and wet dirt respectively, and calculate the electric field intensity distribution along the surface of the insulator under dry dirt and wet dirt conditions. Compare with the electric field intensity distribution under clean conditions to find the skirt most severely affected by dirt. Then, focus on calculating and analyzing the changes in the magnitude of the electric field when the range and location of dirt accumulation on the surface of this skirt change.

[0095] (2) Under natural conditions, the upper surface of the large umbrella skirt is most prone to accumulating dirt. In order to simulate the actual situation, dirt was only covered on the upper surface of the umbrella skirt. In order to investigate the effect of different dirt coverage areas on the electric field strength along the insulator surface, dirt of the same thickness and state was covered on the upper surface of the umbrella skirt. The changes in the electric field strength along the insulator surface when the upper surface of the umbrella skirt was completely covered with dirt, 2 / 3 of the area was covered with dirt, and 1 / 3 of the area was covered with dirt were invented.

[0096] (3) In order to analyze the influence of different pollution locations on the electric field strength along the surface of the insulator, the electric field along the surface of the insulator was changed when the pollution covered the upper surface of the above-mentioned shed with the same range and the same state, respectively covering the front end, middle end and rear end of the upper surface of the shed.

[0097] Define electric field distortion rate .

[0098] (1)

[0099] (2)

[0100] in The peak field strength when a certain umbrella skirt is contaminated. The peak field strength when the umbrella skirt is clean. This represents the change in electric field strength due to contamination of the umbrella skirt compared to the clean state.

[0101] like Figure 18 As shown, the electric field analysis system for composite post insulators under different pollution conditions provided in this embodiment of the invention includes:

[0102] The umbrella skirt determination module analyzes the differences in electric field characteristics when the composite post insulator is clean, fully covered with dry pollution, and fully covered with wet pollution, and identifies the umbrella skirt most severely affected by pollution.

[0103] The electric field characteristic analysis module applies wet contaminants with different coverage areas and locations to the upper surface of the sheds of the composite post insulator; and analyzes the influence of the contaminant coverage area and location on the electric field characteristics of the insulator.

[0104] The risk assessment module calculates the electric field distortion rate under different pollution conditions and assigns a risk rating to the occurrence of flashover based on the magnitude of the electric field distortion rate. Four insulator flashover risk levels are defined: a risk level greater than 50% is considered dangerous; a risk level between 50% and 35% is considered high risk; a risk level between 35% and 20% is considered medium risk; a risk level between 20% and 10% is considered low risk; and a risk level less than 10% is defined as low risk.

[0105] This invention addresses the change in electric field strength when the surface of an FZ-110 / 5 type post composite insulator is covered with contaminants, proposing a risk assessment method based on electric field distortion rate. Compared to other inventions, this invention analyzes different types of contamination and quantitatively analyzes the changes in electric field strength caused by contamination. The electric field distortion rate can intuitively determine the degree of insulator contamination and the risk of flashover.

[0106] This invention belongs to the field of power system technology and is applicable to determining the degree of contamination and the risk level of flashover in FZ-110 / 5 type post composite insulators. The concept of this invention is also applicable to similar composite post insulators. It provides a basis for formulating routine cleaning and maintenance plans for insulators and has excellent application prospects.

[0107] By drawing an electric field intensity model diagram, the electric field intensity distribution of the insulator can be preliminarily determined. The surface electric field distribution of the insulator when it is clean is as follows: Figure 3 As shown.

[0108] exist Figure 3 In the diagram, it can be clearly seen that the electric field strength is higher at both ends of the fittings, the electric field strength is greater near the fittings, and the electric field strength is relatively lower in the middle of the skirt. Within the same skirt, the electric field strength is greater at the edges.

[0109] To more intuitively illustrate the changing trend of the electric field value, a diagram showing the distribution of the electric field intensity along the surface of the insulator when it is clean is drawn, as follows: Figure 4 As shown.

[0110] It can be seen that under clean conditions, the electric field strength of the first shed is the largest, reaching an extreme value of 22.36 kV / cm; the electric field strength near the shed of number 13, located in the middle region of the insulator, is relatively small; the electric field strength of sheds 13 to 25 generally shows an increasing trend; the overall electric field strength is approximately symmetrically distributed. This indicates that sheds near the high-voltage end and the grounding end are prone to surface discharge.

[0111] 2.1.2 Electric field distribution along the surface when insulators are covered with dry contaminants

[0112] A 1mm thick layer of dirt is evenly covered along the edge of the insulator skirt, such as... Figure 5 As shown in Table 2. First, assume the dirt is dry dirt, and its specific parameters are shown in Table 2.

[0113] Observe the electric field distribution along the umbrella skirt when the dirt layer is dry dirt, as shown in the diagram. Figure 6 As shown, the electric field strength is highest at skirt number 1, reaching a maximum of 29.05 kV / cm, with an electric field distortion rate of 29.92%, indicating a medium risk. The closer to the ends, the more severe the impact of contamination on the insulator's electric field strength.

[0114] Compared to when the insulator is clean, such as Figure 7 As shown.

[0115] As can be seen, in the dry and polluted state, the overall electric field distribution of the insulator is similar to that in the clean state, exhibiting an approximately symmetrical distribution with high values ​​at both ends and low values ​​in the middle.

[0116] 2.1.3 Electric field distribution along the surface when insulators are covered with wet pollution

[0117] Assuming the dirt is wet, specific parameters are shown in Table 2. The calculation results are as follows: Figure 8 As shown.

[0118] Compared to when the insulator is clean, such as Figure 9 As shown.

[0119] As can be seen, when the surface is covered with wet dirt, the maximum electric field strength still appears at the tip of the first umbrella skirt, reaching 36.06 kV / cm. Compared with the maximum electric field strength when it is clean, it has increased by 13.70 kV / cm, and the electric field distortion rate is 61.27%. At this time, the risk level is dangerous, and the electrical insulator needs to be cleaned immediately.

[0120] 2.1.4 Comparative Analysis of Field Strength of Insulators Under Clean, Dry-Soiled, and Wet-Soiled Conditions

[0121] To more intuitively compare the changes in electric field strength along the insulator surface when it is clean, covered with dry contaminants, and covered with wet contaminants, the electric field strength along the insulator surface under these conditions is compared side-by-side. Figure 10 As shown. Observe the change in the electric field strength of umbrella skirt No. 1.

[0122] The maximum electric field intensity of a portion of the umbrella skirts was used as a comparison to calculate the change in field intensity. See Table 3 for details.

[0123] Table 3 Comparison of Maximum Field Intensities for Some Umbrella Skirts

[0124]

[0125] As can be seen, the electric field intensity change is greatest at skirt number 1 when the surface is covered with dirt. At skirt number 1, when the insulator surface is covered with dry dirt, the electric field distortion rate is 29.92%; when the insulator surface is covered with wet dirt,

[0126] The electric field distortion rate reached 61.27%.

[0127] 2.2 Field Intensity Analysis of Wet Stains on the Upper Surface of Umbrella Skirt No. 1 under Different Conditions

[0128] As shown in section 2.1, under the condition of skirt contamination, the electric field distortion is greater closer to the two-end fittings, especially closer to the high-voltage end, and the contamination has the greatest impact on skirt No. 1. Moreover, the electric field distortion of skirt No. 1 is greater when it is wetly contaminated than when it is dry. To simulate the most stringent conditions in actual operation, the subsequent analysis will focus on the case of wet contamination on the upper surface of skirt No. 1, and compare and analyze the changes and patterns of electric field distribution when the contamination coverage range and location are different.

[0129] 2.2.1 Analysis of Different Coverage Ranges of Wet Sewage

[0130] Cover the upper surface of umbrella skirt #1 with a 1mm thick layer of wet dirt. Set the dirt coverage to full, 2 / 3 coverage, and 1 / 3 coverage respectively, as shown in the model diagram. Figure 11 As shown.

[0131] Calculate the changes in the electric field along the skirt of umbrella No. 1 under the three conditions.

[0132] The electric field intensity distribution diagrams for the three cases are as follows: Figure 12 As shown.

[0133] To more intuitively compare the changes in electric field intensity along the edge of umbrella skirt 1 when it is contaminated with full coverage, 2 / 3 coverage, and 1 / 3 coverage. For example... Figure 13 As shown, the electric field intensity distribution diagrams for the three cases are compared and analyzed together.

[0134] As can be seen, when the surface of insulator skirt No. 1 is completely covered with dirt, the maximum electric field strength is 36.02 kV / cm; when dirt covers 2 / 3 of the area, the maximum electric field strength is 33.12 kV / cm; and when dirt covers 1 / 3 of the area, the maximum electric field strength is 27.24 kV / cm. As stated in section 3.1.1, the maximum electric field strength of insulator skirt No. 1 when clean is 22.36 kV / cm.

[0135] Table 4 shows the changes in electric field strength when the insulator surface is clean, with the No. 1 skirt fully covered by dirt, with dirt covering 2 / 3 of the area, and with dirt covering 1 / 3 of the area.

[0136] Table 4 Comparison of maximum field strength when coverage area is different

[0137]

[0138] As can be seen, the greater the area of ​​contamination on the upper surface of the insulator skirt, the greater the change in electric field strength. Compared to the clean state, when the contamination covers the entire surface, the electric field distortion rate is 61.09%, which is a dangerous level, and the insulator should be immediately washed with energized water. When the contamination covers 2 / 3 of the surface, the electric field distortion rate is 48.12%, which is a high-risk level, and the insulator should be cleaned as soon as possible. When the contamination covers 1 / 3 of the surface, the electric field distortion rate is 21.82%, which is a medium-risk level, close to low-risk, and the insulator should be cleaned according to maintenance needs.

[0139] Table 5 provides a more intuitive representation of the electric field distortion rate and corresponding risk level under different pollution coverage areas:

[0140] Table 5. Electric field distortion rate and corresponding risk level for different coverage areas

[0141]

[0142] 2.2.2 Analysis of Different Locations of Wet Stain Covering

[0143] On the upper surface of umbrella skirt No. 1, apply a 1mm thick, equally covering wet stain to the front, middle, and rear sections of the skirt. (Model diagram shown below.) Figure 14 As shown.

[0144] For the three models described above, the electric field intensity distribution curves along the surface of umbrella skirt No. 1 were calculated under each of the three pollution coverage conditions. The field intensity distribution is shown in [Figure showing distribution curves]. Figure 15 As shown.

[0145] To more intuitively observe the changing trend of the electric field intensity along the front, middle, and rear sections of the upper surface of umbrella skirt No. 1 when dirt covers it, the electric field intensity distribution diagrams at different dirt-covered locations are compared side-by-side, such as... Figure 16 As shown.

[0146] As can be seen, when the contaminant covers the front section of the upper surface of umbrella skirt No. 1, the maximum electric field strength is 27.24 kV / cm; when the contaminant covers the middle section, the maximum electric field strength is 24.98 kV / cm; and when the contaminant covers the rear section, the maximum electric field strength is 23.68 kV / cm. Table 6 shows the changes in electric field strength when the contaminant fully covers the front, middle, and rear sections compared to the clean state.

[0147] Table 6 Comparison of maximum field strength at different coverage locations.

[0148]

[0149] Compared to a clean state, when contamination covers the initial section, the electric field distortion rate is 21.82%, indicating a medium risk level with minimal impact on the insulator's electric field. When contamination covers the middle section, the electric field distortion rate is 11.72%, indicating a low risk level. When contamination covers the final section, the electric field distortion rate is 5.90%, also indicating a low risk level, meaning cleaning of the insulator is unnecessary. It can be seen that the closer the contamination is to the edge of the shed, the greater the electric field distortion. When the contamination is in the final section, its impact on the insulator's electric field is minimal.

[0150] Table 7 provides a more intuitive representation of the electric field distortion rate and corresponding risk level under different pollution coverage areas:

[0151]

[0152] Based on finite element simulation, the coverage range and location of contamination on the surface of the sheds of the FZ-110 / 5 composite post insulator were investigated, and the following conclusions were drawn:

[0153] (1) The electric field distribution along the surface of the insulator is approximately symmetrical. The electric field strength is greater near the sheds of the fittings on both sides, making flashover more likely. When the surface of the insulator is covered with dirt, the electric field strength of the insulator will increase. The electric field distortion is most severe at shed No. 1. Because wet dirt has better conductivity, the electric field distortion caused by wet dirt is greater than that caused by dry dirt.

[0154] (2) At the No. 1 umbrella skirt, the larger the area of ​​dirt covering the upper surface of the umbrella skirt, the greater the field strength distortion along the umbrella skirt edge.

[0155] (3) At the No. 1 umbrella skirt, the closer the dirt covering the upper surface of the umbrella skirt is to the edge of the umbrella skirt, the greater the distortion of the field strength along the umbrella skirt. When the dirt covers the rear part of the umbrella skirt, it has little effect on the field strength of the umbrella skirt.

[0156] (4) At the No. 1 umbrella skirt, when the upper surface of the umbrella skirt is completely covered by wet dirt, the electric field distortion rate is 61.09%, and the risk level is dangerous. The insulator should be washed with live water immediately. When the wet dirt covers 2 / 3 of the area, the electric field distortion rate is 48.12%, and the risk level is high. The insulator should be cleaned as soon as possible. When the wet dirt covers 1 / 3 of the area, the electric field distortion rate is 21.82%, and the risk level is medium risk, close to low risk. The insulator should be cleaned as needed.

[0157] (5) At the No. 1 umbrella skirt, when the wet dirt covers the front section of the umbrella skirt, the electric field distortion rate is 21.82%, and the risk level is medium risk, which has little impact on the electric field of the insulator; when the wet dirt covers the middle section, the electric field distortion rate is 11.72%, and the risk level is low risk; when the wet dirt covers the rear section, the electric field distortion rate is 5.90%, and the risk level is low risk, so the insulator does not need to be cleaned.

[0158] Therefore, when cleaning insulators, priority should be given to cleaning the skirts near the high-voltage end and the grounding end; since the dirt at the rear of the skirts has little impact on the insulator's electric field strength, priority should be given to cleaning the dirt near the edges of the skirts. This invention is beneficial for scientifically formulating a live-line water washing strategy for insulators and can improve the efficiency of daily operation and maintenance of insulators.

[0159] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention, and within the spirit and principles of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for analyzing the electric field of composite post insulators under different pollution morphologies, characterized in that, A 110 kV rated voltage is applied to the composite post insulator, and the finite element method is used for calculation and analysis. The specific steps include: Step 1: Analyze the differences in electric field characteristics of composite post insulators when they are clean, fully covered with dry contamination, and fully covered with wet contamination, and identify the skirts most severely affected by contamination. First, the electric field intensity distribution along the surface of the composite insulator is calculated under clean conditions. Then, dirt is uniformly covered on all surfaces of the insulator skirts, and the dirt is defined as dry dirt and wet dirt. The electric field intensity distribution along the surface of the insulator under dry dirt and wet dirt conditions is calculated respectively. The electric field intensity distribution is compared with that under clean conditions to find the skirts most severely affected by dirt. Then, the changes in the electric field intensity are calculated and analyzed when the range and position of dirt accumulation on the surface of this skirt change. Step 2: Apply wet dirt with different coverage areas and locations to the upper surface of the sheds of the composite post insulator that is most severely affected by pollution, and analyze the impact of the dirt coverage area and location on the electric field characteristics of the insulator; in order to identify the shed area that is most susceptible to pollution on the upper surface of the shed. The insulator surface field strength was analyzed when the upper surface of the shed most severely affected by contamination was covered with contaminants of the same thickness and condition, and when the upper surface of the shed was completely covered with contaminants, 2 / 3 of the area was covered with contaminants, and 1 / 3 of the area was covered with contaminants. The changes in the electric field along the surface of the insulator were analyzed when the insulator was covered with the same amount and condition of dirt on the upper surface of the umbrella skirt, with the dirt covering the front, middle and rear ends of the upper surface of the umbrella skirt respectively.

2. The method for analyzing the electric field of composite post insulators under different pollution morphologies as described in claim 1, characterized in that, The composite post insulator has a total of 25 skirts, with one large skirt and two small skirts arranged in sequence from the high voltage end to the grounding end, and the skirts are numbered from 1 to 25.

3. The method for analyzing the electric field of composite post insulators under different pollution morphologies as described in claim 1, characterized in that, The composite post insulator's shed material is silicone rubber, with a rated voltage of 110kV; in the simulation calculation, a high potential is applied... The electric potential, with an electric field frequency of 50Hz, is calculated using the current field module in COMSOL.

4. The method for analyzing the electric field of composite post insulators under different pollution morphologies as described in claim 1, characterized in that, The contaminants on the surface of the insulators are all set to a uniform contaminant layer of 1 mm.

5. The method for analyzing the electric field of composite post insulators under different pollution morphologies as described in claim 1, characterized in that, The electric field distortion rate is defined to reflect changes in the electric field. : （1） （2） in The peak field strength when a certain umbrella skirt is contaminated. The peak field strength when the umbrella skirt is clean. This represents the change in electric field strength due to contamination of the umbrella skirt compared to the clean state.

6. The method for analyzing the electric field of composite post insulators under different pollution morphologies as described in claim 2, characterized in that, The electric field distribution along the surface of the insulator is approximately symmetrical. The electric field strength is greater near the sheds of the fittings on both sides, making them prone to flashover. When the surface of the insulator is covered with dirt, the electric field strength of the insulator will increase. The electric field distortion is most severe at the No. 1 shed. Because wet dirt has better conductivity, the electric field distortion caused by wet dirt is greater than that caused by dry dirt.

7. The method for analyzing the electric field of composite post insulators under different pollution morphologies as described in claim 6, characterized in that, At the No. 1 umbrella skirt, the larger the area of ​​dirt covering the upper surface of the umbrella skirt, the greater the field strength distortion along the umbrella skirt edge. At the No. 1 umbrella skirt, the closer the dirt covering the upper surface of the umbrella skirt is to the edge of the umbrella skirt, the greater the distortion of the field strength along the umbrella skirt edge; when the dirt covers the rear end of the umbrella skirt, it has little effect on the field strength of the umbrella skirt. At the No. 1 umbrella skirt, when the upper surface of the umbrella skirt is completely covered with wet dirt, the electric field distortion rate is 61.09%, which is a dangerous level, and the insulator should be washed with live water immediately; when the wet dirt covers 2 / 3 of the area, the electric field distortion rate is 48.12%, which is a high-risk level, and the insulator should be cleaned as soon as possible; when the wet dirt covers 1 / 3 of the area, the electric field distortion rate is 21.82%, which is a medium-risk level, close to low-risk, and the insulator should be cleaned as needed. At the No. 1 umbrella skirt, when the wet contamination on the upper surface of the umbrella skirt covers the front end, the electric field distortion rate is 21.82%, which is a medium risk level and has little impact on the electric field of the insulator. When the wet contamination covers the middle, the electric field distortion rate is 11.72%, which is a low risk level. When the wet contamination covers the rear end, the electric field distortion rate is 5.90%, which is a low risk level and does not require cleaning of the insulator.

8. The electric field analysis system for composite post insulators under different pollution conditions according to any one of claims 1 to 7, characterized in that, include: The umbrella skirt determination module analyzes the differences in electric field characteristics when the composite post insulator is clean, fully covered with dry pollution, and fully covered with wet pollution, and identifies the umbrella skirt most severely affected by pollution. The electric field characteristic analysis module applies wet contaminants with different coverage areas and locations sequentially to the upper surface of the composite post insulator skirt, which is most severely affected by contamination. Analyze the effects of the extent and location of contamination on the upper surface of the insulator skirt on the electric field characteristics of the insulator. The risk assessment module calculates the electric field distortion rate under different pollution conditions and assigns a risk rating to the occurrence of flashover based on the magnitude of the electric field distortion rate. Four risk levels for insulator flashover are defined: a risk level of greater than 50% is dangerous; a risk level of 50% to 35% is high risk; a risk level of 35% to 20% is medium risk; a risk level of 20% to 10% is low risk; and a risk level of less than 10% is defined as low risk.

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