A mechanical strengthening design method and system for a suspension insulator string in a strong wind environment

Abstract

This invention discloses a mechanical reinforcement design method and system for suspension insulator strings under strong wind conditions, belonging to the field of power transmission technology. The method includes: selecting a suspension insulator string model to obtain a simulation model for wind pressure distribution and stress analysis; analyzing the wind pressure distribution of each section of the insulator string and the stress extrema of key stress nodes to obtain the stress distribution characteristics of the insulator string and the stress extrema distribution of key stress nodes; identifying and determining typical failure modes of the suspension insulator string under strong wind conditions; and adopting corresponding mechanical reinforcement measures for each failure mode to form a mechanical reinforcement scheme for the suspension insulator string. This invention is adaptable to the operating conditions of external insulation of 750kV transmission lines in high-altitude, high-wind areas, relatively improving the mechanical reliability of the insulator string, and optimizing the load-bearing capacity, vibration resistance, and operational reliability of substation external insulation equipment without changing the original installation method.

Description

Technical Field

[0001] This invention belongs to the field of power transmission technology in electric power engineering, specifically relating to a mechanical reinforcement design method and system for suspension insulator strings under strong wind conditions. Background Technology

[0002] As ultra-high-voltage power grids continue to extend into the western plateau regions, the number of 750kV substations in high-altitude areas is constantly increasing. Their external insulation systems operate for extended periods in a complex environment characterized by low air pressure, large temperature differences, and strong winds. Compared to low- and mid-altitude areas, the air density and electrical insulation margin are reduced in the plateau environment. Simultaneously, wind speeds are high and wind direction changes are frequent. During service, the external insulation structure not only faces more stringent electrical challenges but also endures increased wind loads, raising operational safety risks. Actual engineering operations show that high-altitude substations are prone to problems such as insufficient flashover margin, increased structural vibration, and accelerated fatigue damage to hardware and porcelain components, which has become one of the important factors restricting the safe and stable operation of the plateau power grid.

[0003] As an improvement, current substation external insulation design methods are mainly based on engineering experience in low- and medium-altitude areas, lacking systematic research on high-altitude environments with large temperature differences and strong winds, particularly in areas such as umbrella type selection, creepage distance configuration, and structural safety verification. Especially at ultra-high voltage levels such as 750kV, insulators not only provide electrical isolation but are also critical load-bearing components, and their mechanical reliability directly affects the safety of equipment and power grid operation. However, existing standards and engineering practices do not adequately address the stress characteristics, wind-induced vibration, and long-term fatigue effects of insulator strings and post insulators under strong wind conditions. Related designs often rely on empirical margins, making it difficult to meet the increasingly stringent safety requirements of high-altitude areas. Therefore, overall, current mechanical reinforcement designs for insulator strings lack sufficient application of data on stress characteristics, wind-induced vibration, and long-term fatigue effects under high-altitude conditions, and the safety, reliability, and durability of external insulation systems need further optimization. Summary of the Invention

[0004] This invention provides a mechanical reinforcement design method and system for suspension insulator strings in strong wind environments. The purpose is to address the current shortcomings in the application of data on stress characteristics, wind-induced vibration, and long-term fatigue effects under high-altitude conditions in the mechanical reinforcement design of insulator strings, and the need for further optimization of the safety, reliability, and durability of the external insulation system.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a mechanical reinforcement design method for suspension insulator strings in strong wind environments, comprising the following steps: By selecting the suspension insulator string model, a simulation model of the insulator string for wind pressure distribution and stress analysis is obtained; The wind pressure distribution and stress extrema of key stress nodes in each section of the insulator string simulation model are analyzed to obtain the stress distribution characteristics of the insulator string and the stress extrema distribution of key stress nodes. Based on stress distribution characteristics and stress extreme value distribution of key stress nodes, typical failure modes of suspension insulator strings under strong wind conditions are identified and determined. Typical failure modes include failure caused by stress concentration at the connection interface, overload and fatigue failure of the first insulator, and additional stress and overall stress induced by wind deflection. Based on typical failure modes, corresponding mechanical reinforcement measures are adopted for each failure mode to form a mechanical reinforcement scheme for suspension insulator strings. The mechanical reinforcement scheme includes adding a ball head hanging ring as a transition component between the insulator and the connecting hardware, replacing the original insulator with a pre-set high-tonnage high-strength insulator, and replacing the single-string suspension structure with a V-shaped insulator string to achieve mechanical reinforcement design of suspension insulator strings under strong wind conditions.

[0006] In some implementations, a suspension insulator string model is selected, including: selecting a standard umbrella-shaped suspension disc porcelain insulator as the simulation object. The suspension disc porcelain insulator is composed of a steel cap, iron feet, porcelain parts and cement adhesive. Ten suspension insulators are selected to form the insulator string simulation model.

[0007] In some implementations, the wind pressure distribution of each section of the insulator string and the stress extrema of key stress nodes are analyzed, including: applying a fixed constraint to the first insulator steel cap at the top of the insulator string simulation model, and applying a surface wind pressure load obtained by flow field mapping, so that the wind direction is perpendicular to the insulator axis, obtaining the law that the surface wind pressure of the insulator string is non-uniformly distributed along the windward side to the leeward side, as well as the stress distribution characteristics that the internal forces of the structure are gradient transmitted along the string length direction, and the upper connection nodes bear the maximum bending moment and shear force, and determining that the stress extrema are concentrated at the interface between the upper hardware and the ceramic parts and at the root of the umbrella skirt.

[0008] In some implementations, the overload and fatigue failure of the first insulator is as follows: the first unit of the insulator string bears the main load transmitted from the whole string, and the stress level is higher than that of the middle and lower units. Under extreme wind loads or long-term vibration, the first insulator porcelain piece experiences stress exceeding the limit or fatigue damage accumulation, leading to crack propagation or even fracture failure.

[0009] In some implementations, the additional stress induced by wind deflection and the increase in overall force are as follows: under strong wind, the insulator string produces wind deflection and swaying, causing the structure to change from axial force to tension-bending coupled force state, the additional bending moment increases, causing the overall force path to shift, and aggravating the unfavorable force on the upper connection area and local structure. At the same time, the root of the umbrella skirt will suffer fatigue damage under high-frequency vibration.

[0010] In some implementations, a ball-headed hanging ring is added between the insulator and the connecting hardware as a transition component, including: introducing a ball-headed hanging ring between the insulator and the connecting hardware; setting rounded corners in key transition areas to avoid new stress concentration; and ensuring that the cross-sectional dimensions of the hanging ring meet the load-bearing requirements, while controlling the overall dimensions within the original installation space.

[0011] In some implementations, the original insulator is replaced with a pre-set high-tonnage, high-strength insulator, including replacing the ordinary porcelain insulator with a high-alumina porcelain insulator without changing the insulator's external dimensions and string structure. The rated electromechanical breaking load, structural height, disc diameter, and nominal creepage distance of the pre-set high-tonnage, high-strength insulator are all greater than those of the original insulator.

[0012] In some implementations, V-shaped insulator strings are used instead of single-string suspension structures, including: a double-string symmetrical arrangement, with the insulator strings on both sides connected to the conductor suspension points via triangular hanging plates to form a V-shaped structure, and the hardware being connected by hinges; or a single-sided insulator string using ten disc-shaped porcelain insulators.

[0013] In some implementations, the selection criteria for mechanical reinforcement schemes under different wind speed conditions include: When the long-term design wind speed in the line area exceeds 25m / s, ordinary single-string suspension insulators will deflect under strong winds; when the wind speed reaches 30m / s or above, a V-shaped insulator string structure is used for mechanical reinforcement.

[0014] This invention also provides a mechanical reinforcement design system for suspension insulator strings under strong wind conditions, to implement the aforementioned mechanical reinforcement design method for suspension insulator strings under strong wind conditions, including a model simulation module, a stress extreme value analysis module, a typical failure mode determination module, and a mechanical reinforcement scheme formation module; wherein: The model simulation module is used to: select a suspension insulator string model to obtain an insulator string simulation model for wind pressure distribution and stress analysis; The stress extremum analysis module is used to analyze the wind pressure distribution and stress extremum of key stress nodes in each section of the insulator string simulation model, and obtain the stress distribution characteristics of the insulator string and the stress extremum distribution of key stress nodes. The typical failure mode determination module is used to identify and determine the typical failure modes of suspension insulator strings in strong wind environments based on stress distribution characteristics and stress extreme value distribution of key stress nodes. Typical failure modes include failure caused by stress concentration at the connection interface, overload and fatigue failure of the first insulator, and additional stress and overall stress increase induced by wind deflection. The mechanical reinforcement scheme formation module is used to: based on typical failure modes, adopt corresponding mechanical reinforcement measures for each failure mode to form a mechanical reinforcement scheme for suspension insulator strings; the mechanical reinforcement scheme includes adding a ball head hanging ring as a transition component between the insulator and the connecting hardware, replacing the original insulator with a pre-set high-tonnage high-strength insulator, and replacing the single-string suspension structure with a V-shaped insulator string to realize the mechanical reinforcement design of suspension insulator strings under strong wind conditions.

[0015] Compared with the prior art, the mechanical reinforcement design method and system for suspension insulator strings in strong wind environments of the present invention has the following beneficial effects: This invention obtains a simulation model of the insulator string by selecting a suspension insulator string model, thus establishing a computational foundation for subsequent mechanical analysis. Based on this, by analyzing the wind pressure distribution of each section of the insulator string and the stress extremities of key stress nodes, the stress distribution characteristics and stress extremities of key areas of the insulator string under strong winds are obtained relatively accurately, providing a mechanical basis for the identification of failure modes. Based on the above stress distribution characteristics and stress extremity distribution, typical failure modes such as failure caused by stress concentration at the connection interface, overload and fatigue failure of the first insulator, and wind-induced additional stress and overall stress increase can be identified. For each of the identified failure modes, mechanical reinforcement measures are adopted, such as adding a ball-head hanging ring as a transition component, replacing the original insulator with a pre-set high-tonnage, high-strength insulator, and replacing the single-string suspension structure with a V-shaped insulator string. These measures improve the different types of failure risks faced by the suspension insulator string under strong winds from the perspectives of improving the local stress transmission path, increasing the overall load-bearing capacity, and changing the structural stress system. This invention achieves a systematic enhancement of the mechanical properties of suspension insulator strings in strong wind environments. Compared with traditional designs that rely on experience margins or single local reinforcement, it can relatively effectively improve the operational reliability and structural safety of suspension insulator strings in high-altitude, strong-wind areas. Attached Figure Description

[0016] The accompanying drawings are provided to further understand the invention and constitute a part of this invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0017] Figure 1 This is a flowchart illustrating a mechanical reinforcement design method for suspension insulator strings under strong wind conditions according to the present invention. Figure 2 This is a schematic diagram of the internal structure of a porcelain insulator in an embodiment of a mechanical reinforcement design method for suspension insulator strings under strong wind conditions according to the present invention. Figure 3 This is a schematic diagram of a single suspension insulator model in an embodiment of the mechanical reinforcement design method for suspension insulator strings under strong wind conditions according to the present invention. Figure 4 This is a schematic diagram of a ten-piece insulator string model in an embodiment of the mechanical reinforcement design method for suspension insulator strings under strong wind conditions according to the present invention. Figure 5 This is a stress cloud diagram of a suspension porcelain insulator string in an embodiment of the mechanical reinforcement design method for suspension insulator strings under strong wind conditions according to the present invention. Figure 6 This is a stress cloud diagram of the key connection part of ten insulator strings in an embodiment of the mechanical reinforcement design method for suspension insulator strings under strong wind conditions according to the present invention. Figure 7 This is a diagram showing the maximum principal stress of a suspension porcelain insulator string in an embodiment of a mechanical reinforcement design method for suspension insulator strings under strong wind conditions according to the present invention. Figure 8 This is a schematic diagram of the ball-head hanging ring structure in an embodiment of the mechanical reinforcement design method for suspension insulator strings under strong wind conditions according to the present invention; Figure 9 This is a schematic diagram illustrating the fit between the load-bearing hardware and the insulator string in an embodiment of the mechanical reinforcement design method for a suspension insulator string under strong wind conditions according to the present invention. Figure 10 This is a schematic diagram comparing finite element analysis models of insulator strings of different strength grades in an embodiment of the mechanical reinforcement design method for suspension insulator strings under strong wind conditions according to the present invention. Figure 11 This is a schematic diagram of a V-shaped insulator string in an embodiment of a mechanical reinforcement design method for suspension insulator strings under strong wind conditions according to the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0019] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0020] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0021] It should be noted that the apparatus and methods disclosed in the embodiments herein can also be implemented in other ways. The apparatus embodiments described above are merely illustrative; for example, the flowcharts and block diagrams in the accompanying drawings show the architecture, functionality, and operation of possible implementations of apparatus, methods, and computer program products according to various embodiments herein. In this regard, each block in a flowchart or block diagram may represent a module, program, or part of code containing one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than those marked in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram and / or flowchart, and combinations of blocks in block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system to perform the specified function or action, or can be implemented using a combination of dedicated hardware and computer instructions.

[0022] In addition, the functional modules in the various embodiments of this article can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part.

[0023] How to provide a mechanical reinforcement design scheme for insulator strings suitable for 750kV substations in high-altitude areas, to make up for the shortcomings of existing engineering methods under high-altitude meteorological conditions, and to improve the safety, reliability and durability of the external insulation system.

[0024] Based on this, such as Figure 1 As shown, this invention provides a mechanical reinforcement design method for suspension insulator strings in strong wind environments, comprising the following steps: By selecting the suspension insulator string model, a simulation model of the insulator string for wind pressure distribution and stress analysis is obtained; The wind pressure distribution and stress extrema of key stress nodes in each section of the insulator string simulation model are analyzed to obtain the stress distribution characteristics of the insulator string and the stress extrema distribution of key stress nodes. Based on stress distribution characteristics and stress extreme value distribution of key stress nodes, typical failure modes of suspension insulator strings under strong wind conditions are identified and determined. Typical failure modes include failure caused by stress concentration at the connection interface, overload and fatigue failure of the first insulator, and additional stress and overall stress induced by wind deflection. Based on typical failure modes, corresponding mechanical reinforcement measures are adopted for each failure mode to form a mechanical reinforcement scheme for suspension insulator strings. The mechanical reinforcement scheme includes adding a ball head hanging ring as a transition component between the insulator and the connecting hardware, replacing the original insulator with a pre-set high-tonnage high-strength insulator, and replacing the single-string suspension structure with a V-shaped insulator string to achieve mechanical reinforcement design of suspension insulator strings under strong wind conditions.

[0025] This invention addresses the safety issues of external insulation structures caused by strong winds in high-altitude areas. Based on a typical suspension insulator string model, it analyzes the wind pressure distribution and stress level of the external insulation structure under strong wind conditions, identifies typical failure modes of suspension insulators, and proposes a mechanical reinforcement design scheme for suspension insulator strings. This provides technical support for improving the load-bearing capacity, vibration resistance, and operational reliability of external insulation equipment in high-altitude substations.

[0026] Specifically, the mechanical reinforcement design method of the present invention is carried out according to the following steps: Step 1: Select the suspension insulator string model This invention reveals the aerodynamic response characteristics, electric field distribution, and mechanical response mechanism of insulator skirts under strong winds. The simulation analysis uses a simplified single-umbrella standard insulator as the research object. To ensure the simulation model has clear engineering orientation and parameter basis, a typical 750kV substation line standard umbrella-shaped suspension disc porcelain insulator is selected as an example to model and analyze its geometric structure and material properties. The simulation object is the U120BP / 146D suspension disc porcelain insulator standard umbrella type, which mainly consists of four parts: steel cap, iron foot, porcelain component, and cement adhesive. Considering computer computing power and minimizing simulation errors, ten-piece (set) suspension insulators are selected for simulation research.

[0027] Step 2: Wind pressure distribution and stress extreme value analysis of key stress nodes in each section of the insulator string The wind pressure on the insulator string surface exhibits a distinctly non-uniform distribution along the windward and leeward sides, with relatively higher local wind pressures at the edges and upper regions of the sheds. Consequently, the internal forces of the structure are transmitted in a gradient along the string length, with the upper connection nodes bearing the greatest bending moment and shear force. Stress extremes are mainly concentrated at the upper hardware-ceramic connection interface and at the root of the sheds, with the upper connection area showing the most significant stress. These key stress-bearing nodes and their stress extreme distribution characteristics constitute the main control basis for subsequent mechanical strengthening design.

[0028] Step 3: Typical Failure Mode Analysis of Suspension Insulators Step 2 identifies typical failure modes that may occur in the external insulation structure under high-altitude and strong wind conditions. Identifying these failure modes is crucial for understanding the structural stress mechanism and serves as an important basis for subsequent mechanical reinforcement design, skirt fatigue life analysis, and external insulation type optimization.

[0029] 1) Failure caused by stress concentration at the connection interface Under strong wind lateral loads, the connection area between the upper hardware and ceramic components is prone to significant stress concentration due to structural abrupt changes and material stiffness differences, resulting in localized areas experiencing large bending moments and shear forces. Long-term alternating loads may lead to cracking of the cement adhesive layer or interface debonding, ultimately causing connection failure. Therefore, this type of failure needs to be controlled by optimizing the hardware connection method and improving the force transmission path.

[0030] 2) Overload and fatigue failure of the first-end insulator The first unit of the insulator string bears the main load transmitted from the entire string, and its stress level is significantly higher than that of the middle and lower units. Under extreme wind loads or long-term vibration, the porcelain component of the first insulator may experience stress exceeding limits or fatigue damage accumulation, leading to crack propagation or even fracture failure. This type of problem requires improving the strength grade of key components to enhance their load-bearing capacity and safety margin.

[0031] 3) Wind-induced additional stress and overall increased force Under strong winds, insulator strings experience significant wind deflection and swaying, causing the structure to shift from axial stress to a tension-bending coupled stress state. This significantly increases the additional bending moment, leading to a shift in the overall stress path and exacerbating the adverse stress on the upper connection area and local structures. Simultaneously, areas such as the base of the sheds are prone to fatigue damage under high-frequency vibration. This type of failure requires suppressing wind deflection and swaying to reduce the impact of additional loads at the source.

[0032] Step 4: Mechanical reinforcement scheme for insulator strings 1) Structural load-bearing hardware - ball head hanging ring added and optimized design Introducing a QP-12 ball-head ring as a transition component between the insulator and the connecting hardware helps alleviate abrupt stress changes and makes the load transfer smoother. In the specific design, the geometry of the newly added ball-head ring is rationally selected: rounded corners are set in key transition areas to avoid new stress concentrations; at the same time, the cross-sectional dimensions of the ring meet the load-bearing requirements, and the overall dimensions are controlled within the original installation space. The addition of the ball-head ring, to a certain extent, serves as a transitional force, making the load transfer more uniform; and significantly improving the mechanical properties of the structure. The ball-head ring addition scheme can improve the stress state of the connection area without changing the main structure of the insulator, and is suitable for situations where the original structure has strong connection rigidity and obvious abrupt stress changes.

[0033] 2) Replacement scheme for large-tonnage, high-strength insulators This invention addresses the problem of insufficient mechanical strength in 750kV transmission lines under special conditions such as icy areas or long spans by employing a strategy of replacing insulators with large-tonnage, high-strength insulators. The large-tonnage model U210BP / 170D is selected, which, compared to the original conventional model, not only increases the weight of a single insulator but also raises the structural height from 146mm to 170mm, the disc diameter from 255mm to 300mm, the creepage distance from 450mm to 525mm, and the mechanical failure load of the insulator string from 210kN to 300kN.

[0034] Compared to the U120BP / 146D type insulator, the rated electromechanical breaking load of the U210BP / 170D type insulator has been increased from 120kN to 210kN, making it a typical large-tonnage insulator. Furthermore, this model features enhanced structural dimensions, body rigidity, and material strength, and can also be classified as a large-tonnage, high-strength insulator, better suited to the mechanical load-bearing capacity and structural stability requirements of 750kV lines in high-altitude and high-wind areas.

[0035] Without altering the insulator's external dimensions and string structure, replacing ordinary porcelain insulators with high-alumina porcelain insulators can achieve an overall improvement in the mechanical properties of the insulator string. Specifically, this manifests as a reduction in stress level, increased structural stiffness, and a significantly improved safety factor, thereby effectively enhancing the operational reliability of 750kV transmission lines under complex weather conditions. This solution requires no adjustments to the existing hardware connections or electrical clearances during engineering implementation, demonstrating good compatibility and widespread application value.

[0036] 3) Mechanical reinforcement scheme for V-shaped insulator strings To address the problems of excessive wind deflection, stress concentration in fittings, and decreased structural stability in the external insulation system of 750kV transmission lines in high-altitude, wind-prone areas, this invention proposes using V-shaped insulator strings as a typical mechanical reinforcement solution. Compared to the traditional single-string suspension structure, the V-shaped string can form a stable triangular support system through the coordinated force of two strings, thereby effectively improving the lateral stiffness of the insulator string, reducing the lateral sway of the conductor and insulator string under strong winds, and enhancing the safety of line operation.

[0037] This invention employs a double-string symmetrical arrangement, with the insulator strings on both sides connected to the conductor suspension points via triangular mounting plates to form a V-shaped structure. Considering structural stability, wind deflection suppression capability, and engineering application experience, the V-angle is set at 90°. Each insulator string on one side uses 10 disc-shaped porcelain insulators to meet the external insulation requirements of 750kV lines. The connecting hardware includes cup-shaped hanging rings, triangular mounting plates, and connecting pins, etc., and the hardware is hinged to ensure that the structure has reasonable rotational freedom under wind loads.

[0038] Analysis shows that although the V-shaped string structure does not reduce the overall stress level, it improves the uniformity of stress distribution on the insulator string, reduces the tendency of local stress concentration, and transforms the structure from localized stress to overall coordinated stress distribution. Engineering operation experience indicates that when the long-term design wind speed in the line area exceeds 25 m / s, ordinary single-string suspension insulators are prone to significant wind deflection under strong winds, which in severe cases may lead to reduced electrical clearance and increased local stress in the fittings. When the wind speed reaches 30 m / s or higher, it is recommended to prioritize the use of V-shaped insulator string structures for mechanical reinforcement.

[0039] This invention also provides a mechanical reinforcement design system for suspension insulator strings under strong wind conditions, including a model simulation module, a stress extreme value analysis module, a typical failure mode determination module, and a mechanical reinforcement scheme formation module; wherein: The model simulation module is used to: select a suspension insulator string model to obtain an insulator string simulation model for wind pressure distribution and stress analysis; The stress extremum analysis module is used to analyze the wind pressure distribution and stress extremum of key stress nodes in each section of the insulator string simulation model, and obtain the stress distribution characteristics of the insulator string and the stress extremum distribution of key stress nodes. The typical failure mode determination module is used to identify and determine the typical failure modes of suspension insulator strings in strong wind environments based on stress distribution characteristics and stress extreme value distribution of key stress nodes. Typical failure modes include failure caused by stress concentration at the connection interface, overload and fatigue failure of the first insulator, and additional stress and overall stress increase induced by wind deflection. The mechanical reinforcement scheme formation module is used to: based on typical failure modes, adopt corresponding mechanical reinforcement measures for each failure mode to form a mechanical reinforcement scheme for suspension insulator strings; the mechanical reinforcement scheme includes adding a ball head hanging ring as a transition component between the insulator and the connecting hardware, replacing the original insulator with a pre-set high-tonnage high-strength insulator, and replacing the single-string suspension structure with a V-shaped insulator string to realize the mechanical reinforcement design of suspension insulator strings under strong wind conditions.

[0040] The present invention will be further described in detail below through specific embodiments.

[0041] Step 1: Taking a typical 750kV substation line standard umbrella-shaped suspension disc porcelain insulator as an example, model and analyze its geometric structure and material properties. The simulation object is the U120BP / 146D standard umbrella-shaped suspension disc porcelain insulator, which mainly consists of four parts: steel cap, iron foot, porcelain component, and cement adhesive. The structural parameters are shown in Table 1, and its internal structure is as follows. Figure 2 As shown.

[0042] Table 1 Structural parameters of porcelain insulators

[0043] Considering both computing power and minimizing simulation errors, a ten-piece (or group) suspension insulator was selected for simulation research. The three-dimensional model of a single piece (or group) is as follows: Figure 3 As shown, the insulator string model is as follows: Figure 4 As shown.

[0044] Step 2: Fix the first insulator cap at the top of the insulator string model, constraining its displacement to zero in the x, y, and z directions to simulate the actual constraint state of the connection end. Then, apply a surface wind pressure load obtained from flow field mapping. Since the wind direction is perpendicular to the insulator axis, the wind pressure will cause the entire structure to be subjected to lateral wind and form a bending moment-dominated stress pattern. The load is transmitted along the path of "outer surface—fittings—ceramic components," and the vicinity of the connection end often becomes a point of convergence and abrupt change in force flow, thus making stress concentration more likely.

[0045] like Figure 5 and Figure 6As shown in the figure, under the conditions of an altitude of 3400m and a wind speed of 30m / s, the stress cloud diagram of the suspension porcelain insulator string exhibits a clear gradient distribution characteristic in its mechanical response: the metal connection area of ​​the top insulator connected to the crossarm is a stress concentration area, with a significantly higher stress level than other parts of the string, and the stress intensity gradually decreases from top to bottom along the insulator string, with the bottom insulator experiencing a relatively low stress level. This distribution pattern is consistent with the load transfer logic under wind load, that is, the top insulator needs to bear the wind deflection load of the entire string and the conductor, so the stress is concentrated in the upper connection part, which also becomes the mechanically weak link under wind load under this condition. Its strength adaptability needs to be given special attention. This stress characteristic can provide a direct basis for the structural optimization of the insulator string and the safety assessment under wind deflection conditions.

[0046] According to the first strength theory, the main factors causing the failure of brittle materials are the maximum principal stress. The tensile strength of the ceramic part is around 170 MPa, the tensile strength of the iron cap is not less than 450 MPa, the tensile strength of the steel foot is not less than 1080 MPa, and the tensile strength of the cement is much lower than that of other parts. Figure 7 The maximum principal stress cloud diagram of ten suspended porcelain insulators at a wind speed of 30 m / s and an altitude of 3400 m.

[0047] from Figure 7 It can be seen that the maximum principal stress of the ten suspension porcelain insulator strings is 11.672 MPa. The red area in the stress scale corresponds to the maximum value, and its distribution shows significant local concentration characteristics: the stress is concentrated at the metal fitting-ceramic connection interface of the upper unit in the insulator string, and at the root area of ​​the shed of the lower unit. The connection interface between the metal fitting and the porcelain is a heterogeneous connection of rigid and brittle materials, and the abrupt change in geometry leads to stress concentration during load transfer.

[0048] Step 3: As before, wind-induced additional stress and overall increased force are applied. 1) Failure caused by stress concentration at the connection interface, 2) Overload and fatigue failure of the first insulator, 3) Wind-induced additional stress and overall increased force.

[0049] Step 4: Adopt a mechanical reinforcement scheme for insulator strings.

[0050] 1) Structural load-bearing hardware - ball head hanging ring added and optimized design A QP-12 ball-head ring is introduced as a transition component between the insulator and the connecting hardware. This structural adjustment helps to mitigate sudden stress changes and makes the load transfer smoother. In the specific design, the geometry of the newly added ball-head ring is rationally selected: rounded corners are set in key transition areas to avoid new stress concentrations; at the same time, the cross-sectional dimensions of the ring are ensured to meet the load-bearing requirements, and the overall dimensions are controlled within the original installation space. The dimensions of the ball-head ring are shown in Table 2, and the structure is as follows. Figure 8 The actual connection method between the ball head ring and the insulator is shown in the assembly diagram. Figure 9 .

[0051] Table 2. Structural Dimensions of QP-12 Type Ball Head Hanger

[0052] 2) Replacement scheme using large-tonnage, high-strength insulators as described above. To further quantify the structural reinforcement characteristics of high-tonnage, high-strength insulators, Table 3 lists the design parameters that differentiate them from conventional strength-grade insulators in key geometric dimensions and mechanical performance indicators. Modeling was performed based on these parameters. Figure 10 .

[0053] Table 3 Comparison of parameters between mechanically reinforced high-tonnage insulators and conventional insulators.

[0054] 3) The mechanical reinforcement scheme using V-shaped insulator strings is adopted as described above. Figure 11 For the overall assembly of V-shaped insulator strings, Table 4 shows the dimensional parameters of the L-1240 triangular mounting plate, and Table 5 shows the dimensional parameters of the WS-12 ball head mounting plate.

[0055] Table 4 Key Parameters of L-1240 Triangular Hanging Board Dimensions

[0056] Table 5 Key Parameters of WS-12 Ball Head Pegboard Dimensions

[0057] In summary, this invention provides a mechanical reinforcement design method for suspension insulator strings in strong wind environments. Firstly, through wind pressure distribution and stress extreme value analysis, key weak points are identified, such as the upper hardware-ceramic connection interface, the first-end insulator, and the root of the shed. Three typical failure modes are identified: stress concentration at the connection interface, overload fatigue at the first end, and additional stress from wind deflection. This gives the reinforcement measures a clear physical direction. By adding ball-head hanging rings to improve force flow transmission, replacing large-tonnage insulators to increase load-bearing capacity, and using V-shaped strings to suppress wind deflection and improve stress uniformity, the mechanical reliability of the insulator strings can be relatively improved. This method can be applied to the operation of external insulation of 750kV transmission lines in high-altitude, high-wind areas without changing the original installation method.

[0058] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Anyone skilled in the art can readily implement the present invention according to the description and above. Any modifications, alterations, or equivalent variations made using the technical content disclosed above are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, or variations made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the present invention.

Claims

1. A mechanical reinforcement design method for suspension insulator strings under strong wind conditions, characterized in that, Includes the following steps: By selecting the suspension insulator string model, a simulation model of the insulator string for wind pressure distribution and stress analysis is obtained; The wind pressure distribution and stress extrema of key stress nodes in each section of the insulator string simulation model are analyzed to obtain the stress distribution characteristics of the insulator string and the stress extrema distribution of key stress nodes. Based on stress distribution characteristics and stress extreme value distribution of key stress nodes, typical failure modes of suspension insulator strings under strong wind conditions are identified and determined. Typical failure modes include failure caused by stress concentration at the connection interface, overload and fatigue failure of the first insulator, and additional stress and overall stress induced by wind deflection. Based on typical failure modes, corresponding mechanical reinforcement measures are adopted for each failure mode to form a mechanical reinforcement scheme for suspension insulator strings. The mechanical reinforcement scheme includes adding a ball head hanging ring as a transition component between the insulator and the connecting hardware, replacing the original insulator with a pre-set high-tonnage high-strength insulator, and replacing the single-string suspension structure with a V-shaped insulator string to achieve mechanical reinforcement design of suspension insulator strings under strong wind conditions.

2. The mechanical reinforcement design method for suspension insulator strings under strong wind conditions according to claim 1, characterized in that, The suspension insulator string model is selected, including: a standard umbrella-shaped suspension disc porcelain insulator is selected as the simulation object. The suspension disc porcelain insulator is composed of a steel cap, iron feet, porcelain parts and cement adhesive. Ten suspension insulators are selected to form the insulator string simulation model.

3. The mechanical reinforcement design method for suspension insulator strings under strong wind conditions according to claim 1, characterized in that, The wind pressure distribution of each section of the insulator string and the stress extrema of key stress nodes are analyzed, including: applying a fixed constraint to the first insulator steel cap at the top of the simulation model of the insulator string, and applying a surface wind pressure load obtained by flow field mapping, so that the wind direction is perpendicular to the insulator axis, obtaining the law that the surface wind pressure of the insulator string is non-uniformly distributed along the windward side to the leeward side, as well as the stress distribution characteristics of the internal forces of the structure being gradient transmitted along the string length direction, and the upper connection nodes bearing the maximum bending moment and shear force, and determining that the stress extrema are concentrated at the interface between the upper hardware and the porcelain parts and at the root of the umbrella skirt.

4. The mechanical reinforcement design method for suspension insulator strings under strong wind conditions according to claim 1, characterized in that, Overload and fatigue failure of the first insulator is as follows: The first unit of the insulator string bears the main load transmitted from the whole string, and the stress level is higher than that of the middle and lower units. Under extreme wind load or long-term vibration, the first insulator porcelain piece experiences stress exceeding the limit or fatigue damage accumulation, leading to crack propagation or even fracture failure.

5. The mechanical reinforcement design method for suspension insulator strings under strong wind conditions according to claim 1, characterized in that, The additional stress induced by wind deflection and the increase in overall force are as follows: Under the action of strong wind, the insulator string will produce wind deflection and swaying, which will change the structure from axial force to tension-bending coupled force state. The additional bending moment increases, which will cause the overall force path to shift and aggravate the unfavorable force on the upper connection area and local structure. At the same time, the root of the umbrella skirt will suffer fatigue damage under the action of high frequency vibration.

6. The mechanical reinforcement design method for suspension insulator strings under strong wind conditions according to claim 1, characterized in that, Adding a ball-head hanging ring as a transition component between the insulator and the connecting hardware includes: introducing a ball-head hanging ring between the insulator and the connecting hardware; setting rounded corners in key transition areas to avoid new stress concentration; and ensuring that the cross-sectional dimensions of the hanging ring meet the load-bearing requirements, while controlling the overall dimensions within the original installation space.

7. The mechanical reinforcement design method for suspension insulator strings under strong wind conditions according to claim 1, characterized in that, The original insulators are replaced with pre-set high-tonnage, high-strength insulators, including replacing ordinary porcelain insulators with high-alumina porcelain insulators without changing the insulator's external dimensions and string structure. The rated electromechanical breaking load, structural height, disc diameter, and nominal creepage distance of the pre-set high-tonnage, high-strength insulators are all greater than those of the original insulators.

8. The mechanical reinforcement design method for suspension insulator strings under strong wind conditions according to claim 1, characterized in that, The V-shaped insulator string is used to replace the single-string suspension structure, including: a double-string symmetrical arrangement, with the insulator strings on both sides connected to the conductor suspension points through triangular hanging plates to form a V-shaped structure, and the hardware is connected by hinges; the single-side insulator string is arranged with ten disc-shaped porcelain insulators.

9. The mechanical reinforcement design method for suspension insulator strings under strong wind conditions according to claim 1, characterized in that, The selection criteria for mechanical reinforcement schemes under different wind speed conditions include: When the long-term design wind speed in the line area exceeds 25m / s, ordinary single-string suspension insulators will deflect under strong winds; when the wind speed reaches 30m / s or above, a V-shaped insulator string structure is used for mechanical reinforcement.

10. A mechanical reinforcement design system for suspension insulator strings under strong wind conditions, used to implement the mechanical reinforcement design method for suspension insulator strings under strong wind conditions as described in any one of claims 1-9, characterized in that, It includes a model simulation module, a stress extreme value analysis module, a typical failure mode determination module, and a mechanical reinforcement scheme formation module; among which: The model simulation module is used to: select a suspension insulator string model to obtain an insulator string simulation model for wind pressure distribution and stress analysis; The stress extremum analysis module is used to analyze the wind pressure distribution and stress extremum of key stress nodes in each section of the insulator string simulation model, and obtain the stress distribution characteristics of the insulator string and the stress extremum distribution of key stress nodes. The typical failure mode determination module is used to identify and determine the typical failure modes of suspension insulator strings in strong wind environments based on stress distribution characteristics and stress extreme value distribution of key stress nodes. Typical failure modes include failure caused by stress concentration at the connection interface, overload and fatigue failure of the first insulator, and additional stress and overall stress increase induced by wind deflection. The mechanical reinforcement scheme formation module is used to: based on typical failure modes, adopt corresponding mechanical reinforcement measures for each failure mode to form a mechanical reinforcement scheme for suspension insulator strings; the mechanical reinforcement scheme includes adding a ball head hanging ring as a transition component between the insulator and the connecting hardware, replacing the original insulator with a pre-set high-tonnage high-strength insulator, and replacing the single-string suspension structure with a V-shaped insulator string to realize the mechanical reinforcement design of suspension insulator strings under strong wind conditions.

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