Time-varying corrosion damage assessment method and system for tower-foot bolt joints applied to digital power grids

Abstract

The present invention provides a method and system for evaluating the time-varying corrosion damage of tower-foot bolt joints applied to digital power grids, which relates to the technical field of digital power grids. The method includes: obtaining the basic parameters of the tower-foot bolt joints of transmission towers; determining the most unfavorable internal forces of the tower-foot bolt joints according to the basic parameters of the tower-foot bolt joints of transmission towers; calculating the remaining corrosion diameter of bolts under time-varying corrosion conditions according to the basic parameters of the tower-foot bolt joints of transmission towers; calculating the shear resistance and local bearing capacity of bolts according to the remaining corrosion diameter of bolts; and evaluating the bearing capacity of the tower-foot bolt joints according to the comparison results between the shear resistance and local bearing capacity of bolts and the most unfavorable internal forces of the tower-foot bolt joints. The system includes a data acquisition unit, a structural internal force calculation unit, and a node time-varying corrosion bearing capacity evaluation unit. The present invention can accurately and digitally evaluate the bearing capacity of steel structure tower-foot bolt joints under time-varying corrosion conditions when they are exposed to the atmospheric environment for a long time.

Description

Technical Field

[0001] The present invention relates to the technical field of digital power grids, and more particularly, to a method and system for evaluating the time-varying corrosion damage of tower-foot bolt joints applied to digital power grids. Background Art

[0002] With the advancement of the construction of digital power grids and durable power grids, the grid structure has become increasingly complex, and the operating environment is variable, posing higher requirements for the safety and reliability of grid operation. As one of the key structures of the power grid, the performance of the tower-foot bolt joints of transmission towers is crucial. The tower-foot bolt joints are like the "joints" of the grid structure, connecting various components and bearing the operating load of the entire power grid. Their quality and performance are directly related to the long-term stable operation of the power grid.

[0003] During the long-term service of the tower-foot bolt joints of transmission towers, they face severe time-varying corrosion problems. Since most transmission towers are distributed in outdoor natural environments, the tower-foot bolt joints are long-term exposed to the atmospheric environment and are affected by natural factors such as wind, sun, and rain, making them prone to corrosion. And this corrosion is a process that changes continuously over time, that is, it has time-varying characteristics. In the initial stage of corrosion, corrosion products are formed on the surface of the tower-foot bolt joints. As the corrosion progresses, the corrosion products gradually increase, the effective bearing cross-sectional area of the bolts continuously decreases, and the mechanical properties such as shear strength and tensile strength gradually decrease, ultimately possibly leading to the fracture and failure of the tower-foot bolt joints, seriously threatening the overall safety of the power grid.

[0004] However, there are many deficiencies in the existing analysis methods for the corrosion damage of tower-foot bolt joints. In traditional methods, some simplified empirical formulas are usually established based on limited experimental data or engineering experience to estimate the corrosion damage degree of tower-foot bolt joints. This method lacks an in-depth understanding and accurate description of the corrosion process, and cannot accurately reflect the complexity and uncertainty of time-varying corrosion, resulting in large errors and low reliability in the estimation results. There are also some methods that detect the tower-foot bolt joints through regular manual inspections or the use of some non-destructive testing equipment to obtain their corrosion damage information. This method is not only inefficient and costly, but also limited by the accuracy of the testing equipment and the on-site environmental conditions, making it difficult to comprehensively and accurately evaluate the internal corrosion situation of the tower-foot bolt joints, and at the same time, it is impossible to monitor the dynamic change process of corrosion damage in real time.

[0005] In view of the deficiencies of the existing analysis methods, there is an urgent need for a new method that can more accurately evaluate the bearing capacity of the time-varying corrosion damage of the tower-foot bolt joints of transmission towers to meet the development needs of digital power grids and durable power grids. Summary of the Invention

[0006] The present invention aims to at least solve one of the above technical problems existing in the prior art.

[0007] To this end, the first aspect of the present invention provides a method for evaluating the time-varying corrosion damage of the tower foot bolt joints applied to the digital power grid.

[0008] The second aspect of the present invention provides a system for evaluating the time-varying corrosion damage of the tower foot bolt joints applied to the digital power grid.

[0009] The present invention provides a method for evaluating the time-varying corrosion damage of the tower foot bolt joints applied to the digital power grid, including:

[0010] Obtain the basic parameters of the tower foot bolt joints of the transmission tower, where the basic parameters include the load effect, service life, material, transmission tower structure, and size specifications of the tower foot bolt joints of the transmission tower;

[0011] Determine the most unfavorable internal force of the tower foot bolt joints according to the basic parameters of the tower foot bolt joints of the transmission tower;

[0012] Calculate the corrosion remaining diameter of the bolt under time-varying corrosion conditions according to the basic parameters of the tower foot bolt joints of the transmission tower;

[0013] Calculate the shear resistance and local bearing capacity of the bolt according to the corrosion remaining diameter of the bolt;

[0014] Evaluate the bearing capacity of the tower foot bolt joints according to the comparison results between the shear resistance and local bearing capacity of the bolt and the most unfavorable internal force of the tower foot bolt joints.

[0015] According to the method for evaluating the time-varying corrosion damage of the tower foot bolt joints applied to the digital power grid according to the above technical solution of the present invention, it may also have the following additional technical features:

[0016] In the above technical solution, the calculation of the corrosion remaining diameter of the bolt under time-varying corrosion conditions according to the basic parameters of the tower foot bolt joints of the transmission tower includes:

[0017] Determine the influence degree when the target bolt corrodes according to the assembly position of the target bolt on the tower foot shoe plate, that is, the corrosion connection length influence coefficient of the target bolt;

[0018] Calculate the corrosion remaining diameter of the bolt according to the corrosion connection length influence coefficient.

[0019] In the above technical solution, the determination of the influence degree when the target bolt corrodes according to the assembly position of the target bolt on the tower foot shoe plate, that is, the corrosion connection length influence coefficient of the target bolt, includes:

[0020]

[0021] Among them, represents the corrosion connection length influence coefficient of the x-th bolt; represents the distance of the x-th bolt, i.e., the target bolt, to the center position of the bolt assembly area of the tower foot shoe plate in the length direction; represents the length of the bolt assembly area of the tower foot shoe plate.

[0022] In the above technical solution, calculating the corrosion remaining diameter of the bolt according to the corrosion connection length influence coefficient includes:

[0023]

[0024] wherein, represents the corrosion remaining diameter of the x-th bolt; represents the x initial diameter of the bolt, i.e., the diameter before corrosion damage; represents the bolt corrosion rate; represents the service life of the transmission tower.

[0025] In the above technical solution, the bolt corrosion rate is determined according to the atmospheric corrosion environment grade of the area where the transmission tower is located.

[0026] In the above technical solution, the method for determining the bolt corrosion rate according to the atmospheric corrosion environment grade of the area where the transmission tower is located is:

[0027]

[0028] wherein, represents the atmospheric corrosion environment grade coefficient, and the higher the atmospheric corrosion environment grade of the area where the transmission tower is located, the greater the atmospheric corrosion environment grade coefficient.

[0029] In the above technical solution, the atmospheric corrosion environment grade includes C1 grade, C2 grade, C3 grade, C4 grade, C5 grade and CX grade divided according to ISO9223 standard;

[0030] When the atmospheric corrosion environment grade is C1 grade, the value of the atmospheric corrosion environment grade coefficient is 1;

[0031] When the atmospheric corrosion environment grade is C2 grade, the value of the atmospheric corrosion environment grade coefficient is 2;

[0032] When the atmospheric corrosion environment grade is C3 grade, the value of the atmospheric corrosion environment grade coefficient is 3;

[0033] When the atmospheric corrosion environment grade is C4 grade, the value of the atmospheric corrosion environment grade coefficient is 4;

[0034] When the atmospheric corrosion environment grade is C5, the value of the atmospheric corrosion environment grade coefficient is 5;

[0035] When the atmospheric corrosion environment grade is CX, the value of the atmospheric corrosion environment grade coefficient is 6.

[0036] In the above technical solution, calculating the shear bearing capacity and the local bearing capacity of the bolt according to the remaining diameter of the bolt corrosion includes:

[0037]

[0038]

[0039] Among them, represents the shear bearing capacity of the bolt after corrosion damage of the x-th bolt; represents the local bearing capacity of the bolt after corrosion damage of the x-th bolt; represents the shear strength of the bolt; represents the bearing strength of the bolt; represents the minimum thickness of the main material and the gusset plate through which the bolt passes in the same shear direction.

[0040] In the above technical solution, evaluating the bearing capacity of the tower foot bolt joint according to the comparison result between the shear bearing capacity and the local bearing capacity of the bolt and the most unfavorable internal force of the tower foot bolt joint includes:

[0041] Judging whether the most unfavorable internal force of the tower foot bolt joint can meet the judgment condition, and the judgment condition is:

[0042]

[0043] Among them, represents the most unfavorable internal force of the tower foot bolt joint; { represents the shear bearing capacity of the bolt after corrosion damage of the x-th bolt; represents the local bearing capacity of the bolt after corrosion damage of the x-th bolt;

[0044] If the most unfavorable internal force of the tower foot bolt joint meets the judgment condition, it means that the current tower foot bolt joint still meets the operation requirements even if corrosion damage occurs; if the most unfavorable internal force of the tower foot bolt joint does not meet the judgment condition, it means that the corrosion damage of the current tower foot bolt joint has affected the stable operation of the transmission tower.

[0045] A time-varying corrosion damage evaluation system for tower foot bolt joints applied to a digital power grid provided by the present invention is applied to the time-varying corrosion damage evaluation method for tower foot bolt joints applied to a digital power grid as described in any one of the above technical solutions, and the system includes:

[0046] A data acquisition unit that collects and stores the basic parameters of the bolt joints at the tower feet of transmission towers.

[0047] A structural internal force calculation unit that determines the most unfavorable internal force of the bolt joints at the tower feet based on the basic parameters of the bolt joints at the tower feet of transmission towers.

[0048] A node time-varying corrosion bearing capacity evaluation unit that calculates the remaining diameter of the bolt under time-varying corrosion conditions based on the basic parameters of the bolt joints at the tower feet of transmission towers; calculates the shear bearing capacity and local bearing capacity of the bolt according to the remaining diameter of the bolt; and evaluates the bearing capacity of the bolt joints at the tower feet based on the comparison results between the shear bearing capacity and local bearing capacity of the bolt and the most unfavorable internal force of the bolt joints at the tower feet.

[0049] In summary, due to the adoption of the above technical features, the beneficial effects of the present invention are as follows:

[0050] The present invention proposes a method for evaluating the time-varying corrosion damage of bolt joints at tower feet applied to digital power grids, which can accurately and digitally evaluate the bearing capacity of bolt joints at the steel structure tower feet under time-varying corrosion conditions when exposed to the atmospheric environment for a long time. This method starts from the perspective of time-varying corrosion, provides strong support for the construction of the whole-life cycle smart power grid, promotes the process of power grid digitization and durability construction, and effectively fills the gap in the evaluation of the bearing capacity of bolt joints at tower feet in the existing technology.

[0051] Specifically, the present invention comprehensively considers various factors affecting the bearing capacity of bolt joints at tower feet by obtaining the basic parameters of bolt joints at the tower feet of transmission towers, including load effects, service life, material, structure, and dimension specifications, etc. On this basis, the most unfavorable internal force is determined, and the remaining diameter of the bolt under time-varying corrosion conditions is calculated, and then the shear bearing capacity and local bearing capacity of the bolt are obtained, realizing a fine evaluation of the bearing capacity of bolt joints at tower feet, which helps to more accurately predict the performance changes of bolt joints at tower feet during long-term use and provides a scientific basis for the maintenance and renewal of the power grid. This evaluation method takes into account the influence of time-varying corrosion on bolt joints at tower feet, enabling the operation and maintenance of the power grid to more accurately address the problem of the decrease in bearing capacity caused by corrosion of bolt joints at tower feet, thereby improving the safety and reliability of power grid operation, reducing power grid accidents caused by the failure of bolt joints at tower feet, and ensuring stable power supply of the power grid.

[0052] The present invention evaluates the time-varying corrosion damage of bolt joints at tower feet in a digital manner, which not only improves the evaluation efficiency but also makes the evaluation results more objective and accurate. This is crucial for realizing the intelligent management of the power grid, helps to push the construction of the power grid to a higher digital level, promotes the deep integration of the power grid and modern information technology, and lays a foundation for building a smart power grid.

[0053] Additional aspects and advantages of the present invention will become apparent in the following description section or be learned through the practice of the present invention. Description of the Drawings

[0054] The above and / or additional aspects and advantages of the present invention will become apparent and be readily understood from the description of embodiments in conjunction with the following drawings, in which:

[0055] Figure 1 is a flowchart of a time-varying corrosion damage assessment method for tower foot bolt joints applied to a digital power grid according to an embodiment of the present invention;

[0056] Figure 2 is a schematic execution diagram of a time-varying corrosion damage assessment system for tower foot bolt joints applied to a digital power grid according to an embodiment of the present invention. Detailed Embodiments

[0057] In order to more clearly understand the above objects, features and advantages of the present invention, the present invention will be further described in detail below in conjunction with the drawings and specific embodiments. It should be noted that, without conflict, the embodiments of the present application and the features in the embodiments may be combined with each other.

[0058] Many specific details are set forth in the following description in order to fully understand the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited by the specific embodiments disclosed below.

[0059] The following refers to Figure 1 and Figure 2 to describe a time-varying corrosion damage assessment method and system for tower foot bolt joints applied to a digital power grid according to some embodiments of the present invention.

[0060] Some embodiments of the present application provide a time-varying corrosion damage assessment method for tower foot bolt joints applied to a digital power grid.

[0061] [[ID=3)4]]As Figure 1 shown, the first embodiment of the present invention proposes a time-varying corrosion damage assessment method for tower foot bolt joints applied to a digital power grid, including the following steps S1-S5. It should be noted that the order of the above steps S1-S5 is only a schematic representation of the present disclosure, and those skilled in the art can adjust the order of steps S1-S5 according to actual needs, and the steps in different orders can also be executed simultaneously.

[0062] S1. Obtain the basic parameters of the tower foot bolt joints of the transmission tower, where the basic parameters include the load effect, service life, material, transmission tower structure and the size specifications of the tower foot bolt joints of the transmission tower.

[0063] S2. Determine the most unfavorable internal force of the tower-foot bolt joint according to the basic parameters of the tower-foot bolt joint of the transmission tower.

[0064] It should be noted that the calculation method of the most unfavorable internal force of the tower-foot bolt joint is well-known to those skilled in the art, and there are various methods such as simulation and formula calculation. The calculation of the most unfavorable internal force of the tower-foot bolt joint is not the key point of this disclosure, and any one of the existing methods can be selected for calculation.

[0065] In a specific embodiment, based on the spatial finite element calculation theory, this disclosure calculates the internal force according to the bar element. Specifically, based on the known information such as the load effect, material, transmission tower structure, and size specifications of the tower-foot bolt joint of the transmission tower, the most unfavorable internal force of the tower-foot bolt joint is obtained by combining simulation and mathematical calculation. The specific method will not be elaborated here.

[0066] S3. Calculate the corrosion remaining diameter of the bolt under the time-varying corrosion condition according to the basic parameters of the tower-foot bolt joint of the transmission tower.

[0067] In some embodiments, step S3 includes:

[0068] S31. Determine the influence degree when the target bolt is corroded according to the assembly position of the target bolt on the tower-foot shoe plate, that is, the corrosion connection length influence coefficient of the target bolt; the specific calculation method is:

[0069] Including:

[0070]

[0071] Wherein, represents the corrosion connection length influence coefficient of the x-th bolt; represents the x-th bolt, that is, the distance (unit: mm) of the target bolt to the center position of the bolt assembly area of the tower-foot shoe plate in the length direction; represents the length of the bolt assembly area of the tower-foot shoe plate (unit: mm).

[0072] According to the above formula, the corrosion connection length influence coefficient corresponding to any bolt on the tower-foot shoe plate when it is corroded can be obtained. The corrosion connection length influence coefficient reflects the influence of the ratio between the length from the target bolt to the bolt connection center position (the center of the bolt assembly area of the tower-foot shoe plate) and the length of the bolt assembly area of the tower-foot shoe plate on the corrosion remaining diameter. It can be understood that corrosion usually starts from one end of the tower-foot shoe plate. That is to say, the farther the corroded bolt is from the bolt connection center position, the greater the corrosion influence and the greater the degree of corrosion damage; on the contrary, the closer the corroded bolt is to the bolt connection center position, the smaller the corrosion influence and the smaller the degree of corrosion damage.

[0073] Specifically, when the length from the target bolt to the center position of the bolt connection is greater relative to the length of the bolt assembly area of the tower foot shoe plate, it will increase. This indicates that in this bolt connection area, the influence range of corrosion is relatively large. Because a longer means that corrosion may extend farther along the length direction of the bolt connection, thus having a greater impact on the effective load-bearing part of the bolt (the area corresponding to the remaining diameter). When is smaller, the value is relatively small, indicating that the influence of corrosion is mainly concentrated in the local area of the bolt connection, and the influence degree on the overall remaining diameter of the bolt is relatively low. Through this coefficient, the erosion degree of corrosion on the effective load-bearing part of the bolt can be evaluated more accurately, and thus more accurate basic data can be provided for calculating the corrosion remaining diameter of the bolt in the follow-up.

[0074] S32. Calculate the corrosion remaining diameter of the bolt according to the corrosion connection length influence coefficient; the specific calculation method is:

[0075]

[0076] Where, represents the corrosion remaining diameter of the x-th bolt (unit: mm); represents the initial diameter of the x -th bolt (unit: mm), that is, the diameter before corrosion damage; represents the bolt corrosion rate (μm / year); represents the service life of the transmission tower.

[0077] It should be noted that the bolt corrosion rate can be obtained through various methods, such as looking up tables, actual investigations, assignment, etc., and it should be ensured that the selected value conforms to the actual operation situation of the transmission tower.

[0078] In a specific embodiment, the bolt corrosion rate is determined according to the atmospheric corrosion environment grade of the area where the transmission tower is located.

[0079] Specifically, the method for determining the bolt corrosion rate according to the atmospheric corrosion environment grade of the area where the transmission tower is located is:

[0080]

[0081] [[ID=4x]] represents the atmospheric corrosion environment grade coefficient. The higher the atmospheric corrosion environment grade of the area where the transmission tower is located, the greater the atmospheric corrosion environment grade coefficient.

[0082] ​It should be noted that there are usually differences between the corrosion rate of bolts and that of angle steel members, which are caused by functional differences and installation method differences. That is to say, the existing method for determining the corrosion rate of angle steel members is not fully applicable to the calculation of the corrosion rate of bolts. Based on this, the present disclosure determines the above-mentioned calculation method of the bolt corrosion rate through a large amount of data research based on the numerical fitting method. After verification, the accuracy rate of the calculation result of the above-mentioned bolt corrosion rate is above 98% (the accuracy is ±0.005 μm / year).

[0083] In some embodiments, the atmospheric corrosion environment grades include C1 grade, C2 grade, C3 grade, C4 grade, C5 grade, and CX grade divided according to the ISO9223 standard;

[0084] When the atmospheric corrosion environment grade is C1 grade, the atmospheric corrosion environment grade coefficient takes a value of 1;

[0085] When the atmospheric corrosion environment grade is C2 grade, the atmospheric corrosion environment grade coefficient takes a value of 2;

[0086] When the atmospheric corrosion environment grade is C3 grade, the atmospheric corrosion environment grade coefficient takes a value of 3;

[0087] When the atmospheric corrosion environment grade is C4 grade, the atmospheric corrosion environment grade coefficient takes a value of 4;

[0088] When the atmospheric corrosion environment grade is C5 grade, the atmospheric corrosion environment grade coefficient takes a value of 5;

[0089] When the atmospheric corrosion environment grade is CX grade, the atmospheric corrosion environment grade coefficient takes a value of 6.

[0090] S4. Calculate the shear resistance and local bearing capacity of the bolt according to the remaining diameter of the bolt after corrosion.

[0091] In some embodiments, step S4 includes:

[0092]

[0093]

[0094] Among them, represents the shear resistance of the x-th bolt after corrosion damage; represents the local bearing capacity of the x-th bolt after corrosion damage; represents the shear strength of the bolt (unit: MPa); Denotes the bearing strength of the bolt (unit: MPa); Denotes the minimum thickness (unit: mm) of the main material and the gusset plate through which the bolt passes in the same shear direction.

[0095] S5. Evaluate the bearing capacity of the tower foot bolt joint according to the comparison results of the shear bearing capacity and the local bearing capacity of the bolt with the most unfavorable internal force of the tower foot bolt joint.

[0096] In some embodiments, step S5 includes:

[0097] Judge whether the most unfavorable internal force of the tower foot bolt joint can meet the judgment condition, and the judgment condition is:

[0098]

[0099] Wherein, Denotes the most unfavorable internal force of the tower foot bolt joint; Denotes the shear bearing capacity of the bolt after corrosion damage of the x-th bolt; Denotes the local bearing capacity of the bolt after corrosion damage of the x-th bolt;

[0100] If the most unfavorable internal force of the tower foot bolt joint meets the judgment condition, it means that the current tower foot bolt joint still meets the operation requirements even if corrosion damage occurs; if the most unfavorable internal force of the tower foot bolt joint does not meet the judgment condition, it means that the corrosion damage of the current tower foot bolt joint has affected the stable operation of the transmission tower.

[0101] Some other embodiments of the present invention provide a time-varying corrosion damage assessment system for tower foot bolt joints applied to a digital power grid, which is applied to the time-varying corrosion damage assessment method for tower foot bolt joints applied to a digital power grid as described in any of the above embodiments, as Figure 2 shown, the system includes a data acquisition unit, a structural internal force calculation unit, and a node time-varying corrosion bearing capacity assessment unit.

[0102] The data acquisition unit collects and stores the basic parameters of the tower foot bolt joints of the transmission tower. In Figure 2 the shown embodiment, the data acquired by the data acquisition unit is divided into two parts. One part is the initial data of the power grid project collected and sorted out by the designers, including the basic parameters of the tower foot bolt joints of the transmission tower such as the load effect and service life of the transmission tower structure; the other part is the preset model data stored in the standardized material library, model library, and component library.

[0103] The structural internal force calculation unit is used to determine the most unfavorable internal force of the tower foot bolt joint according to the basic parameters of the tower foot bolt joint of the transmission tower. In Figure 2In the illustrated embodiment, the structural internal force calculation unit is shown as a structural internal force calculation platform. The structural internal force calculation platform calls the standardized material library, model library, and component library, and calculates according to the bar element based on the spatial finite element calculation theory to obtain the control internal force of the tower foot bolt node, that is, the most unfavorable internal force.

[0104] The node time-varying corrosion bearing capacity evaluation unit is used to calculate the remaining corrosion diameter of the bolt under time-varying corrosion conditions according to the basic parameters of the transmission tower tower foot bolt node; and calculate the shear bearing capacity and local compression bearing capacity of the bolt according to the remaining corrosion diameter of the bolt; and evaluate the bearing capacity of the tower foot bolt node according to the comparison results between the shear bearing capacity and local compression bearing capacity of the bolt and the most unfavorable internal force of the tower foot bolt node. The node time-varying corrosion bearing capacity evaluation unit is shown as a node time-varying corrosion bearing capacity evaluation center. During the application process, the time-varying corrosion bearing capacity evaluation center calls the time-varying corrosion bearing capacity calculation criterion of the tower foot bolt node for bearing capacity evaluation. For the time-varying corrosion bearing capacity calculation criterion of the tower foot bolt node, refer to steps S3 and S4.

[0105] In some embodiments, the evaluation results of the node time-varying corrosion bearing capacity evaluation unit will be displayed through a visualization interface and output through an output terminal. In a specific embodiment, if the most unfavorable internal force of the tower foot bolt node meets the determination condition, the evaluation unit will display "Meet" on the visualization interface and mark the color as green; if the most unfavorable internal force of the tower foot bolt node does not meet the determination condition, the evaluation unit will display "Does not meet" on the visualization interface and mark the color as red. After receiving the result data stream transmitted by the evaluation center, the output terminal will upload the evaluation result to the owner and wait for the owner to give a final instruction regarding the evaluation result. The instructions include "Meet, normal operation" and "Does not meet, the node needs to be repaired". After the owner's instruction is determined, the terminal will generate a final evaluation analysis report, which will go through process approval, signing, and stamping at all levels within the owner's organization and then output the final finished report (pdf encrypted format) for reference by the owner, construction, and operation and maintenance.

[0106] In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiments or examples. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0107] Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A time-varying corrosion damage assessment method for tower foot bolt nodes applied to a digital power grid, characterized in that Including: Obtain the basic parameters of the tower-foot bolt joint of the transmission tower, where the basic parameters include the load effect, service life, material, transmission tower structure, and size specifications of the tower-foot bolt joint of the transmission tower; Determine the most unfavorable internal force of the tower-foot bolt joint according to the basic parameters of the tower-foot bolt joint of the transmission tower; Calculate the corrosion remaining diameter of the bolt under time-varying corrosion conditions according to the basic parameters of the tower-foot bolt joint of the transmission tower; Calculate the shear resistance and local bearing capacity of the bolt according to the corrosion remaining diameter of the bolt; Evaluate the bearing capacity of the tower-foot bolt joint according to the comparison result between the shear resistance and local bearing capacity of the bolt and the most unfavorable internal force of the tower-foot bolt joint; Among them, calculating the corrosion remaining diameter of the bolt under time-varying corrosion conditions according to the basic parameters of the tower-foot bolt joint of the transmission tower includes: Determine the influence degree when the target bolt is corroded according to the assembly position of the target bolt on the tower-foot shoe plate, that is, the corrosion connection length influence coefficient of the target bolt; including: Among them, represents the corrosion connection length influence coefficient of the x-th bolt; represents the x-th bolt, that is, the distance in the length direction from the target bolt to the center position of the bolt assembly area of the tower foot shoe plate; represents the length of the bolt assembly area of the tower foot shoe plate; Calculate the corrosion remaining diameter of the bolt according to the corrosion connection length influence coefficient, including: Among them, represents the remaining diameter of corrosion of the x th bolt; represents the initial diameter of the x th bolt, that is, the diameter before corrosion damage; represents the corrosion rate of the bolt; represents the service life of the transmission tower.

2. The method for evaluating the time-varying corrosion damage of the tower-foot bolt node applied to the digital power grid according to claim 1, wherein The bolt corrosion rate is determined according to the atmospheric corrosion environment grade of the area where the transmission tower is located.

3. The method for evaluating the time-varying corrosion damage of the tower foot bolt node applied to the digital power grid according to claim 2, wherein The method for determining the bolt corrosion rate according to the atmospheric corrosion environment grade of the area where the transmission tower is located is: Among them, represents the atmospheric corrosion environment grade coefficient. The higher the atmospheric corrosion environment grade of the area where the transmission tower is located, the greater the atmospheric corrosion environment grade coefficient.

4. The method for evaluating the time-varying corrosion damage of the tower-foot bolt node applied to the digital power grid according to claim 3, characterized in that, The atmospheric corrosion environment grades include C1 grade, C2 grade, C3 grade, C4 grade, C5 grade, and CX grade divided according to the ISO9223 standard; When the atmospheric corrosion environment grade is C1, the value of the atmospheric corrosion environment grade coefficient is 1; When the atmospheric corrosion environment grade is C2, the value of the atmospheric corrosion environment grade coefficient is 2; When the atmospheric corrosion environment grade is C3, the value of the atmospheric corrosion environment grade coefficient is 3; When the atmospheric corrosion environment grade is C4, the value of the atmospheric corrosion environment grade coefficient is 4; When the atmospheric corrosion environment grade is C5, the value of the atmospheric corrosion environment grade coefficient is 5; When the atmospheric corrosion environment grade is CX grade, the value of the atmospheric corrosion environment grade coefficient is 6.

5. The time-varying corrosion damage assessment method for tower-foot bolt joints applied to digital power grids according to claim 1, characterized in that Calculating the shear resistance and local bearing capacity of the bolt according to the corrosion remaining diameter of the bolt includes: Among them, represents the shear bearing capacity of the bolt after corrosion damage of the x-th bolt; represents the bearing capacity of the bolt under local pressure after corrosion damage of the x-th bolt; represents the shear strength of the bolt; represents the bearing strength of the bolt; represents the minimum thickness of the main material and the gusset plate through which the bolt passes in the same shear direction.

6. The method for evaluating the time-varying corrosion damage of the tower-foot bolt node applied to the digital power grid according to claim 1, wherein Evaluating the bearing capacity of the tower-foot bolt joint according to the comparison result between the shear resistance and local bearing capacity of the bolt and the most unfavorable internal force of the tower-foot bolt joint includes: Judge whether the most unfavorable internal force of the tower-foot bolt joint can meet the determination condition, and the determination condition is: Among them, represents the most unfavorable internal force of the tower foot bolt node; represents the shear resistance of the bolt after corrosion damage of the x-th bolt; represents the local bearing capacity of the bolt after corrosion damage of the x-th bolt; If the most unfavorable internal force of the tower-foot bolt joint meets the determination condition, it means that the current tower-foot bolt joint still meets the operation requirements even if corrosion damage occurs; if the most unfavorable internal force of the tower-foot bolt joint does not meet the determination condition, it means that the corrosion damage of the current tower-foot bolt joint has affected the stable operation of the transmission tower.

7. A time-varying corrosion damage assessment system for tower foot bolt joints applied to a digital power grid, characterized in that, When applied to the time-varying corrosion damage assessment method of the tower-foot bolt joint applied to the digital power grid as described in any one of claims 1 to 6, the system includes: A data acquisition unit that acquires and stores the basic parameters of the tower-foot bolt joint of the transmission tower; A structural internal force calculation unit for determining the most unfavorable internal force of the tower-foot bolt joint according to the basic parameters of the tower-foot bolt joint of the transmission tower; A node time-varying corrosion bearing capacity assessment unit for calculating the corrosion remaining diameter of the bolt under time-varying corrosion conditions according to the basic parameters of the tower-foot bolt joint of the transmission tower; calculating the shear resistance and local bearing capacity of the bolt according to the corrosion remaining diameter of the bolt; and evaluating the bearing capacity of the tower-foot bolt joint according to the comparison result between the shear resistance and local bearing capacity of the bolt and the most unfavorable internal force of the tower-foot bolt joint.

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