A method for analyzing breeze vibration of steel tube towers of power transmission lines

Abstract

The present application provides a method for analyzing breeze vibration of steel pipe towers of power transmission lines, comprising the following steps: S1 obtaining operational monitoring data of the steel pipe towers of power transmission lines, as well as historical wind speed and meteorological data; S2 performing sensitivity analysis on several different parameters that may affect the amplitude of the tower, and identifying the main parameters that lead to the vortex-induced vibration response of the steel pipe tower components; S3 simulating a typical steel pipe transmission tower component model with a refined three-dimensional finite element model, and analyzing the component's natural frequency, mode curve, critical wind speed, and maximum amplitude; S4 establishing vortex-induced vibration models of a single steel pipe and adjacent steel pipes, realizing the dynamic grid effect during breeze vibration based on nested grid technology, developing a fluid-structure coupling calculation UDF program for vortex-induced vibration, and embedding it into the FLUENT software to reproduce the vortex-induced vibration response process under complex working conditions. The present application effectively solves the problem of evaluating breeze vibration response of steel pipe towers of high-voltage transmission lines by combining theoretical analysis with numerical simulation, with high computational efficiency and accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of transmission line iron towers, and in particular to a method for analyzing breeze vibration of a transmission line steel pipe tower. Background Art

[0002] Traditional transmission towers are mostly lattice-shaped angle steel towers. However, with increasing transmission capacity and electrical performance requirements, steel tubular towers are gradually replacing angle steel towers. These towers offer advantages such as high load bearing capacity, low structural wind loads, a lightweight and aesthetically pleasing design, strong overload resistance, and low overall cost. These advantages enhance the disaster resistance of transmission towers in extreme environments. Ultra-high voltage (UHV) steel tubular towers, offering both technical and economic advantages, have attracted considerable attention. High-rise circular steel tubular towers, which are in line with electrical developments, have recently gained widespread application.

[0003] However, cylindrical steel tube tower components are more susceptible to breeze vibration in breeze conditions. The frequent occurrence of vortex-induced vibration (VIV) in recent years has become prominent, hindering the widespread application of steel tube towers. When natural wind acts on the surface of steel tube tower components, they vibrate. Once the wind vibration frequency matches the natural frequency of the components, VOR (Vortex-Induced Resonance) occurs. During the operation and maintenance of actual steel tube transmission towers, changes in the structural form of high steel tube towers can cause breeze vibration in certain specific areas, such as the front of the tower legs, the V-face diagonal members, the horizontal cross members of the tower leg partitions, and the tower body diagonal members above the partitions. Furthermore, residual stress exists in the node plate welds of actual steel tube towers. When components are subjected to continuous VIR for long periods of time, if the steel tube slenderness ratio is too large and there are installation errors, initial cracks are very likely to appear at the nodes, ultimately leading to fatigue failure of the node plate, thus affecting the safety of the entire tower.

[0004] In actual environments, where breezes are frequent, the breeze vibration response of steel tube towers cannot be ignored: high-frequency vibrations of horizontal or near-horizontal components can cause physical discomfort to maintenance workers; vortex-induced vibrations of diagonal and transverse members can induce line failures. In severe cases, this can affect the safe operation of the entire line, causing immeasurable economic losses and casualties. Currently, there is a lack of theoretical and experimental support for vortex-induced vibration of steel tube towers, and domestic regulations regarding vortex-induced vibration are relatively vague. For example, the "Technical Regulations for the Structural Design of Overhead Transmission Line Towers" require that the first-order vibration wind speed of the poles must not be less than 15 m / s during steel tube tower design. In actual steel tube tower design, to reduce project costs, the design slenderness ratio of the steel tube tower components is relatively large. As a result, the first-order vibration wind speed obtained according to the regulations does not meet the 15 m / s requirement, leading to a conflict between the two design approaches. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for analyzing breeze vibration of steel pipe towers of power transmission lines, so as to solve the technical problem that vortex-induced vibration of existing steel pipe towers of power transmission lines in breeze environments causes fatigue damage to the steel pipe towers, shortening their service life.

[0006] A method for analyzing breeze vibration of a steel pipe tower of a transmission line, comprising the following specific steps:

[0007] S1 obtains the operation monitoring data of the transmission line steel pipe tower, as well as the historical wind speed meteorological data of the area where the steel pipe tower is located, collects the characteristic parameters of the steel pipe tower, and calculates the mass of the tower;

[0008] S2 conducts sensitivity analysis on several different parameters that may affect the amplitude of the tower, and identifies the main parameters that lead to the vortex-induced vibration response of the steel tube tower components;

[0009] S3 simulates a typical steel pipe transmission tower component model using a refined three-dimensional finite element model, analyzes the component's natural frequency, mode curve, critical wind speed, and maximum amplitude, and studies the first-order and second-order mode shapes, starting wind speed, and maximum amplitude of vortex-induced resonance for the entire model of two support rods and the R section and B leg of the transmission tower.

[0010] S4 established vortex-induced vibration models for single steel pipes and adjacent steel pipes, realized the dynamic grid effect during breeze vibration based on nested grid technology, developed a UDF program for fluid-solid coupling calculation during vortex-induced vibration, and embedded it in the FLUENT software to reproduce the vortex-induced vibration response process under complex working conditions.

[0011] Optionally, the operation monitoring data of the transmission line steel tube tower in step S1 includes characteristic parameters of damage of the steel tube tower during breeze vibration, and parameters of the cause of damage of the steel tube components analyzed in combination with the on-site environment;

[0012] The historical wind speed meteorological data of the area where the steel pipe tower is located includes historical hourly wind speed and wind direction, and the wind speed range is set according to the wind force level reported on site and the national standard, and several wind speed parameters are selected according to the wind speed range.

[0013] Optionally, the characteristic parameters of the steel tube tower in step S1 include the length, diameter, wall thickness, material, material density, mass ratio, and damping ratio of the tower.

[0014] Optionally, in step S2, the main parameters causing the vortex-induced vibration response of the steel tube tower component obtained by the analytical method are wind speed, wind direction and turbulence.

[0015] Optionally, the three-dimensional finite element model is refined in step S3, including a structural model consistent with the actual component geometric parameters, and various connection types that characterize the node constraints of the rods.

[0016] Optionally, the specific steps of calculating the natural frequency, critical wind speed and maximum amplitude of the component in step S3 are:

[0017] S3.1 The natural frequencies of each order of vibration of steel pipe components are:

[0018]

[0019] The vibration mode function of the steel pipe component is:

[0020] Φ(x)=Acoshβx+Bsinhβx+Ccosβx+Dsinβx

[0021] In the formula, the undetermined constants A, B, C, and D are determined by the boundary conditions at both ends of the beam. The free vibration response of the steel tube member is the superposition of the responses of each mode, so:

[0022]

[0023] S3.2 Calculate the tower's initial wind speed using the tower frequency and the Stauhal number for circular cross-sections:

[0024]

[0025] Where U cr is the vortex vibration initiation wind speed, S t is the Stothal number, f0 is the tower frequency, and D is the circular cross section;

[0026] S3.3 According to structural dynamics, the maximum amplitude expression can be obtained by combining the structural mass and vibration frequency:

[0027]

[0028] Where μ max is the maximum value of the dynamic amplification coefficient, m is the structural mass per unit length, ξ is the structural damping ratio, ω n is the structure's natural circular frequency, ω s is the vortex shedding frequency, φ is the initial phase, D is the characteristic size of the rod, and for a circular rod, the cross-sectional diameter is taken, ρ a is the air density, U is the incoming wind speed, C L is the amplitude of the structural dynamic lift coefficient.

[0029] Optionally, the specific steps of developing a UDF program for fluid-structure interaction calculation during vortex-induced vibration in step S4 are as follows:

[0030] S4.1 Nested Mesh Establishment: Based on the nested meshing feature of the Workbench platform, local high-quality structured meshes can be nested within unstructured mesh types, overcoming the negative volume problem of dynamic meshes and maintaining good mesh quality during motion. Based on the wind-induced vibration area, a background mesh and a steel pipe mesh are established to determine the area affected by wind-induced vibration. A component mesh is then formed outside the steel pipe and imported into the Fluent software to form a mesh model. Nested boundaries are then set in the over-limit boundary condition module.

[0031] S4.2 Develop a vortex-induced vibration program (UDF) and combine it with the Runge-Kutta method to obtain the corresponding velocity and displacement at different times: Combine the user-defined function (UDF) function of Fluent software to write a program, import it into Fluent software through UDF, and thus control the movement of steel pipe tower members in the flow field, thereby realizing fluid-solid coupling.

[0032] Optionally, the specific steps of reproducing the vortex-induced vibration response process of complex working conditions embedded in the FLUENT software in step S4 are:

[0033] S4.3 Set the wind speed range based on the wind force level reported on site and the national standard, and select several wind speed parameters based on the wind speed range; combine the breeze field and the steel pipe characteristic parameters to calculate the correlation between the steel pipe vortex-induced vibration response and the main controlling factors;

[0034] Establish displacement time history curve, lift time history curve, drag time history curve, lift coefficient time history curve, and drag coefficient time history curve, and obtain the frequency corresponding to the maximum vortex-induced vibration characteristic value based on fast Fourier transform (FFT);

[0035] The characteristic parameters of the breeze field and steel pipe include wind speed, turbulence, mass ratio, damping ratio, mass damping ratio SG and wind direction angle combination conditions;

[0036] S4.4 Establish a vortex-induced vibration model for adjacent steel pipes, analyze the vortex-induced vibration interference effect of adjacent steel pipes in a wind field environment, and provide suggestions for optimizing the vibration suppression scheme.

[0037] Optionally, the specific steps of vortex-induced vibration calculation in step S4.2 are:

[0038] S4.2.1 The entire calculation starts with the steel tubular tower members at rest in the equilibrium position. Determine the initial conditions for the first iteration.

[0039] S4.2.2 Use the transverse displacement and velocity of the steel tubular tower members and the wind lift on the members obtained in the previous time step as the initial conditions for the solution in the current time step;

[0040] S4.2.3 Using the initial conditions, solve the equations of motion of the steel tubular tower members using the fourth-order Runge-Kutta method to obtain the displacement and velocity of the steel tubular tower members at the current time step;

[0041] S4.2.4 Assign the desired velocity of the steel tubular tower member to the member boundary and the mesh area that undergoes rigid body motion with the member using a UDF program, and update the position of this mesh area. Simultaneously, adjust the external mesh adjacent to the mesh boundary using a dynamic mesh technique.

[0042] S4.2.5 Use Fluent software to solve the discrete equations to obtain the flow field characteristic values ​​of velocity and pressure at the current time step. Use the "Computer_Force_Moment" macro to extract the lift force exerted by the wind on the current steel pipe tower member.

[0043] S4.2.6 Obtain the structural response and flow field forces on the members in the current time step, and use them as the initial conditions for the next time step. Repeat this cycle until the calculation is complete.

[0044] The change of the structure's position in the flow field is achieved through grid movement. The boundary surface between the flow field and the structure is given a velocity, so the boundary conditions change when solving the flow field, realizing the fluid-solid coupling process between the steel pipe and the wind field during breeze vibration.

[0045] Due to the adoption of the above technical solution, the present invention has the following advantages:

[0046] 1. This application adopts an analysis method that combines theoretical analysis and numerical simulation, which effectively solves the problem of breeze vibration response evaluation of high-voltage transmission line steel pipe towers at both theoretical and technical levels, clarifies the dynamic response characteristics of steel pipe nodes under different constraint conditions, optimizes the model construction dynamic mesh technology based on FLUENT software, realizes the fluid-solid coupling process of breeze vibration of steel pipe components, reproduces the breeze vibration response characteristics of steel pipe components in a breeze environment, and has outstanding advantages such as high computational efficiency and accuracy.

[0047] 2. This application is an analysis method that directly reflects the impact of breeze environment on the operation of steel pipe components of transmission lines. It is a method for identifying the resonance response, fatigue failure and vibration suppression optimization of steel pipe components under complex conditions. It provides new research ideas for fatigue assessment and vibration suppression optimization of high-voltage transmission steel pipe tower components in mountainous environments, and produces significant economic benefits for the safe operation of power grids and the sustainable development of power construction.

[0048] Other advantages, objects, and features of the present invention will be described in part in the following description and, in part, will be apparent to those skilled in the art upon examination of the following description or may be learned from practice of the present invention. The objects and other advantages of the present invention may be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] The accompanying drawings of the present invention are described below.

[0050] Figure 1 This is a flow chart of the fluid-structure coupling calculation of the present invention.

[0051] Figure 2 This is a model diagram for the refined modeling of the steel tube tower member of the present invention.

[0052] Figure 3These are the vibration mode diagrams of different orders of the fully constrained steel pipe of the present invention.

[0053] Figure 4 Schematic diagram of the structure of the model setting and nested grid of the present invention.

[0054] Figure 5 This is a cloud diagram of the turbulent kinetic energy of the flow around the tower of the present invention.

[0055] Figure 6 This is a curve diagram of wind speed and displacement numerically simulated by the present invention.

[0056] Figure 7 This is a time history curve diagram of the vortex-induced vibration characteristic value of the numerical simulation of wind speed changes in the present invention.

[0057] Figure 8 This is the numerical simulation turbulence-displacement relationship diagram of the present invention.

[0058] Figure 9 This is a time history curve diagram of the vortex-induced vibration characteristic value of turbulence change numerically simulated by the present invention.

[0059] Figure 10 This is the turbulent kinetic energy cloud diagram of different spacings of adjacent steel pipes when the spacings are different according to the numerical simulation of the present invention.

[0060] Figure 11 It is the amplitude characteristic value of the two rods when the spacing between adjacent steel pipes is different in the numerical simulation of the present invention. DETAILED DESCRIPTION

[0061] The present invention will be further described below with reference to the accompanying drawings and examples.

[0062] Example 1:

[0063] A method for analyzing breeze vibration of a steel pipe tower of a transmission line, comprising the following specific steps:

[0064] S1 obtains the operation monitoring data of the transmission line steel pipe tower, as well as the historical wind speed meteorological data of the area where the steel pipe tower is located, collects the characteristic parameters of the steel pipe tower, and calculates the mass of the tower;

[0065] The operation monitoring data of the transmission line steel pipe tower includes the characteristic parameters of the steel pipe tower's damage during breeze vibration, and the parameters of the cause of steel pipe component damage analyzed in combination with the on-site environment. The historical wind speed meteorological data of the area where the steel pipe tower is located includes the historical hourly wind speed and wind direction, and the wind speed range is set according to the wind force level reported on site and the national standard, and several wind speed parameters are selected based on the wind speed range.

[0066] The characteristic parameters of the steel pipe tower include the length, diameter, wall thickness, material, material density, mass ratio and damping ratio of the tower.

[0067] In this embodiment, the length of the pole 1 is 9.0329 m, the diameter is 0.159 m, the wall thickness is 0.005 m, and the tower material is manganese steel (Mn), with a density of about 7833 kg / m 3 , the estimated total weight of the rod is 171.16kg. Rod 2 is 13.2728m long, 0.194m in diameter, and 0.006m thick. The steel pipe material is manganese steel (Mn), with a density of approximately 7833kg / m 3 , so the estimated total weight of rod 1 is 171.16 kg, and the total weight of rod 2 is 386.43 kg.

[0068] S2 conducts sensitivity analysis on several different parameters that may affect the amplitude of the tower, and clarifies the main parameters that cause the vortex-induced vibration response of the steel tube tower components; the main parameters that cause the vortex-induced vibration response of the steel tube tower components are wind speed, wind direction and turbulence.

[0069] S3 Figure 2 As shown in the figure, a refined three-dimensional finite element model is used to simulate a typical steel pipe transmission tower component model, analyze the component's natural frequency, mode curve, critical wind speed and maximum amplitude, and study the first-order and second-order mode shapes, starting wind speed and maximum amplitude of vortex-induced resonance of the model containing two support rods and all the rods including the R section and B leg of the transmission tower; Figure 2 (a) is a schematic diagram of the tower structure. Figure 2 (b) is a partial schematic diagram of the tower. Figure 2 (c) is a schematic diagram of the local grid of the tower.

[0070] S3.1 The natural frequencies of each order of vibration of steel pipe components are:

[0071]

[0072] The vibration mode function of the steel pipe component is:

[0073] Φ(x)=Acoshβx+Bsinhβx+Ccosβx+Dsinβx

[0074] In the formula, the undetermined constants A, B, C, and D are determined by the boundary conditions at both ends of the beam, and (β n l) 2 As shown in Table 1.

[0075] Table 1 Constraint parameters under various conditions

[0076]

[0077] The free vibration response of the steel pipe component is the superposition of the responses of each vibration mode, so:

[0078]

[0079] In this embodiment, 3D refined modeling of steel pipe components is carried out based on the ANSYS software platform. The refined 3D finite element model includes a structural model consistent with the actual component geometric parameters and various connection types that characterize the node constraints of the rods. Figure 3 and Figure 4 As shown, Figure 3 (a)- Figure 3 (h) are the vibration mode diagrams of the steel pipe, the supporting steel pipe structure and the structure including the tower legs at different vibration frequencies, as shown in the figure below. Figure 3 Table 2 shows the fundamental frequencies of the finite element model under different constraints, as analyzed by ANSYS software. Table 2 shows the multiple natural frequencies of the tower when constrained by bolted joints. The first-order natural frequency of member 1 is 6.0475 Hz, and the first-order natural frequency of member 2 is 3.3598 Hz. Table 3 shows the tower parameters.

[0080] Table 2 Fundamental frequency (Hz) of finite element models with different constraints (9032.9×159×5mm)

[0081]

[0082] Table 3 Tower parameters

[0083]

[0084] S3.2 Calculate the tower's initial wind speed using the tower frequency and the Stauhal number for circular cross-sections:

[0085]

[0086] Where U cr is the vortex vibration initiation wind speed, S t is the Stothal number, f0 is the tower frequency, and D is the circular cross section. S3.3 According to structural dynamics, the maximum amplitude expression can be obtained by combining the structural mass and the vibration frequency:

[0087]

[0088] Where μ max is the maximum value of the dynamic amplification coefficient, m is the structural mass per unit length, ξ is the structural damping ratio, ω n is the structure's natural circular frequency, ω s is the vortex shedding frequency, φ is the initial phase, D is the characteristic size of the rod, and for a circular rod, the cross-sectional diameter is taken, ρ a is the air density, U is the incoming wind speed, C Lis the amplitude of the dynamic lift coefficient of the structure. Calculations show that the first-order vibration velocity for the two supporting steel tube members is 2.68 m / s, and the second-order vibration velocity is 6.53 m / s. The maximum amplitude of the first-order vortex-induced resonance is 4.026e-5 m, and the maximum amplitude of the second-order vortex-induced resonance is 2.390e-4 m. The first-order vibration velocity for the steel tubes in the tower leg structure is 2.540 m / s, and the second-order vibration velocity is 4.682 m / s. The maximum amplitude of the first-order vortex-induced resonance is 3.617e-5 m, and the maximum amplitude of the second-order vortex-induced resonance is 1.229e-4 m.

[0089] S4 established vortex-induced vibration models for single steel pipes and adjacent steel pipes, realized the dynamic grid effect during breeze vibration based on nested grid technology, developed a UDF program for fluid-solid coupling calculation during vortex-induced vibration, and embedded it in the FLUENT software to reproduce the vortex-induced vibration response process under complex working conditions.

[0090] S4.1 Nested Mesh Establishment: Nested meshing, based on the Workbench platform, allows you to nest high-quality local structured meshes within unstructured mesh types, overcoming the negative volume issue often seen with dynamic meshes and maintaining good mesh quality during motion. Based on the wind-induced vibration area, a background mesh and a steel pipe mesh are established to determine the area affected by wind-induced vibration. A component mesh is then formed outside the steel pipe. This mesh is then imported into Fluent software to form a mesh model, and nested boundaries are set in the over-limit boundary condition module.

[0091] In this embodiment, numerical simulation analysis is performed based on Fluent software. The kinetic energy cloud diagram of vortex-induced vibration turbulence around the cylinder based on FLUENT numerical simulation is as follows: Figure 4 shown. Figure 4 (a) is the regional setting of the single steel pipe vortex-induced vibration model, Figure 4 (b) Nested grid model in vortex-induced vibration grid design.

[0092] S4.2 Develop a vortex-induced vibration program (UDF) and combine it with the Runge-Kutta method to obtain the corresponding velocity and displacement at different times: Combine the user-defined function (UDF) function of Fluent software to write a program, import it into Fluent software through UDF, and thus control the movement of steel pipe tower members in the flow field, thereby realizing fluid-solid coupling.

[0093] In this embodiment, a vortex-induced vibration program (UDF) is developed based on:

[0094]

[0095] Where: ρ f , U, D are fluid density, flow rate, and steel pipe diameter respectively, C D , C L are the lift coefficient and the drag coefficient respectively; ω0, The natural frequencies of the steel tube components are respectively identified and obtained through structural dynamics tests or numerical simulations; the modal damping ratio of the vibration system of the steel tube components can be obtained through the free attenuation vibration curve of the structure.

[0096] Solving the above equations with the Runge-Kutta method yields the corresponding velocities and displacements at different times:

[0097]

[0098] Where:

[0099]

[0100] In this embodiment, based on the construction of the above model, its mesh quality is verified to meet the accuracy requirements, and a fluid-structure coupling calculation program for vortex-induced vibration is developed and substituted into the FLUENT software to obtain the vortex-induced vibration response characteristic value under breeze vibration conditions, such as Figure 5 The turbulent kinetic energy cloud diagram of the flow is shown.

[0101] In this embodiment, if Figure 1 As shown in Figure 2, the specific steps for vortex-induced vibration calculation are as follows:

[0102] S4.2.1 The entire calculation starts with the steel tubular tower members at rest in the equilibrium position. Determine the initial conditions for the first iteration.

[0103] S4.2.2 Use the transverse displacement and velocity of the steel tubular tower members and the wind lift on the members obtained in the previous time step as the initial conditions for the solution in the current time step;

[0104] S4.2.3 Using the initial conditions, solve the equations of motion of the steel tubular tower members using the fourth-order Runge-Kutta method to obtain the displacement and velocity of the steel tubular tower members at the current time step;

[0105] S4.2.4 Use a UDF program to assign the desired velocity of the steel tubular tower member to the member boundary and the mesh area that undergoes rigid body motion with the member, and update the position of this mesh. Simultaneously, use dynamic mesh technology to adjust the external mesh adjacent to the mesh boundary.

[0106] S4.2.5 Use Fluent software to solve the discrete equations to obtain the flow field characteristic values ​​of velocity and pressure at the current time step. Use the "Computer_Force_Moment" macro to extract the lift force exerted by the wind on the current steel pipe tower member.

[0107] S4.2.6 Obtain the structural response and flow field forces on the members in the current time step, and use them as the initial conditions for the next time step. Repeat this cycle until the calculation is complete.

[0108] The change of the structure's position in the flow field is achieved through grid movement. The boundary surface between the flow field and the structure is given a velocity, so the boundary conditions change when solving the flow field, realizing the fluid-solid coupling process between the steel pipe and the wind field during breeze vibration.

[0109] S4.3 Set the wind speed range based on the wind force level reported on site and the national standard, and select several wind speed parameters based on the wind speed range; combine the breeze field and the steel pipe characteristic parameters to calculate the correlation between the steel pipe vortex-induced vibration response and the main controlling factors;

[0110] Establish displacement time history curve, lift time history curve, drag time history curve, lift coefficient time history curve, and drag coefficient time history curve, and obtain the frequency corresponding to the maximum vortex-induced vibration characteristic value based on fast Fourier transform (FFT);

[0111] The characteristic parameters of the breeze field and steel pipe include wind speed, turbulence, mass ratio, damping ratio, mass damping ratio SG and wind direction angle combination conditions;

[0112] S4.3.1 The specific steps for conducting sensitivity analysis on wind speed are as follows:

[0113] S4.3.1.1 Calculate the tower's initial wind speed using the tower frequency and the Stothal number for circular cross-sections:

[0114]

[0115] Where U cr is the vortex vibration initiation wind speed, S t is the Stothal number, f0 is the tower frequency, and D is the circular cross-section.

[0116] In this embodiment, the circular cross section is 0.2. Substituting the cross section of the rod 1 into the cross section, the predicted first-order vibration wind speed of the actual tower is 4.81m / s.

[0117] S4.3.1.2 Set the wind speed range based on the wind force level reported on site and the national standard, and select several wind speed parameters based on the wind speed range;

[0118] In this embodiment, according to the on-site report, the wind speed at the site is level 3, and the wind speed range of level 3 in the national standard "Wind Force Level" is 3.4-5.4m / s. Therefore, the wind speeds are set to 3.8m / s, 4.4m / s, 4.8m / s, 5.0m / s, and 5.4m / s respectively.

[0119] S4.3.1.3 Simulate the displacement amplitude under several wind speed parameters while assuming that other parameters are consistent; the other parameters include turbulence intensity, mass ratio, damping ratio, mass-damping ratio SG, and wind direction angle.

[0120] In this embodiment, other parameters remain unchanged, and the specific wind speed conditions are shown in Table 4.

[0121] Table 4 Wind speed conditions

[0122]

[0123] like Figure 6 The figure shows the displacement amplitude under different wind speeds. As can be seen from the figure, as the wind speed increases, the displacement amplitude also increases, and the two show a positive correlation. When the wind speed is 5m / s, the vibration amplitude is 5.4cm, which is similar to the amplitude on site. The displacement time history curve, lift time history curve, drag time history curve, lift coefficient time history curve, drag coefficient time history curve and the corresponding fast Fourier FFT changes of the corresponding working conditions are shown in the figure respectively. Figure 7 (a)- Figure 7 As shown in (e), the locking frequency corresponding to the maximum value of the vortex-induced vibration characteristic value can be obtained, providing a scientific basis for vibration suppression optimization.

[0124] S4.3.2 The specific steps for sensitivity analysis of turbulence are:

[0125] S4.3.2.1 Turbulence is an important parameter for describing the flow state of a fluid and is used to measure the relative magnitude of velocity fluctuations in a turbulent flow. In fluid mechanics, turbulence is a disordered, complex, three-dimensional flow phenomenon in which the fluid velocity fluctuates randomly in all directions. Turbulence is usually defined as:

[0126]

[0127] Where: u′ is the root mean square fluctuation of the fluid velocity, indicating the magnitude of the velocity fluctuation, and U is the average velocity of the fluid.

[0128] In this embodiment, other parameters remain unchanged, and the specific turbulence conditions are shown in Table 5.

[0129] Table 5 Turbulence conditions

[0130]

[0131] like Figure 8 The figure shows the displacement amplitude at different turbulence levels. As can be seen from the figure, the amplitude reaches its maximum value at a turbulence level of 1%, with a displacement of 5.7 cm. After decreasing to the minimum amplitude at a turbulence level of 3%, the amplitude increases with the increase of turbulence level. The displacement time history curve, lift time history curve, drag time history curve, lift coefficient time history curve, drag coefficient time history curve and the corresponding fast Fourier transform (FFT) changes of the corresponding working conditions are shown as follows: Figure 9 (a)- Figure 9As shown in (e), the frequency corresponding to the maximum value of the vortex-induced vibration effect can be obtained, providing a scientific basis for vibration suppression optimization.

[0132] S4.4 Establish a vortex-induced vibration model for adjacent steel pipes, analyze the vortex-induced vibration interference effect of adjacent steel pipes in a wind field environment, and provide suggestions for optimizing the vibration suppression scheme. The specific method is:

[0133] Rod 1 and rod 2 are arranged in parallel in the incoming flow direction, and different spacings are set between the two rods, which are D1+D2, 1.5(D1+D2), and 2(D1+D2) respectively from the center of the rod. D1 and D2 are the diameters of steel pipe 1 and steel pipe 2 respectively. The kinetic energy cloud diagram of vortex-induced vibration turbulence around the cylinder based on FLUENT numerical simulation is shown as follows: Figure 10 shown.

[0134] like Figure 11 As shown, Figure 11 (a) is the amplitude variation diagram of rod 1, Figure 11 (b) is a graph showing the amplitude variation of rod 2. For rod 1, the amplitude of rod 1 at different spacings shows a trend of first increasing and then decreasing, reaching a maximum amplitude at 4.5 m / s, with an amplitude of approximately 8 mm, indicating a wind speed locking phenomenon. Compared to rod spacings of 1.5 (D1+D2) and 2 (D1+D2), the amplitude at D1+D2 is smaller when the rod spacing is smaller; however, the amplitude variation with wind speed at different spacings between the former is not much different. The amplitude of rod 2 at different spacings decreases with increasing wind speed, reaching a maximum amplitude at 3.5 m / s. When the rod spacing is smaller, the amplitude of rod 2 at different wind speeds is greater than that at larger spacings. This is because smaller spacing may cause flow interaction between the two cylinders, thereby affecting the vortex shedding pattern and frequency. This interaction leads to an increase in the amplitude of rod 2.

[0135] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A method for analyzing breeze vibration of a steel pipe tower of a transmission line, characterized in that: The specific steps are: S1 obtains the operation monitoring data of the transmission line steel pipe tower, as well as the historical wind speed meteorological data of the area where the steel pipe tower is located, collects the characteristic parameters of the steel pipe tower, and calculates the mass of the tower; S2 conducts sensitivity analysis on several different parameters that may affect the amplitude of the tower, and identifies the main parameters that lead to the vortex-induced vibration response of the steel tube tower components; S3 simulates a typical steel pipe transmission tower component model using a refined three-dimensional finite element model, analyzes the component's natural frequency, mode curve, critical wind speed, and maximum amplitude, and studies the first-order and second-order mode shapes, starting wind speed, and maximum amplitude of vortex-induced resonance for the entire model of two support rods and the R section and B leg of the transmission tower. S4 established vortex-induced vibration models for single steel pipes and adjacent steel pipes, realized the dynamic grid effect during breeze vibration based on nested grid technology, developed a fluid-structure coupling calculation UDF program for vortex-induced vibration, and embedded it into FLUENT software to reproduce the vortex-induced vibration response process under complex working conditions; The specific steps of developing the UDF program for fluid-structure interaction calculation in the vortex-induced vibration process in step S4 are as follows: S4.1 Nested Mesh Establishment: Based on the nested meshing feature of the Workbench platform, local high-quality structured meshes can be nested within unstructured mesh types, overcoming the negative volume problem of dynamic meshes and maintaining good mesh quality during motion. Based on the wind-induced vibration area, a background mesh and a steel pipe mesh are established to determine the area affected by wind-induced vibration. A component mesh is then formed outside the steel pipe and imported into the Fluent software to form a mesh model. Nested boundaries are then set in the over-limit boundary condition module. S4.2 Develop a vortex-induced vibration program (UDF) and combine it with the Runge-Kutta method to obtain the corresponding velocity and displacement at different times: Combine the user-defined function (UDF) function of Fluent software to write a program, import it into Fluent software through UDF, and thus control the movement of steel pipe tower members in the flow field, thereby realizing fluid-solid coupling.

2. The method for analyzing breeze vibration of a steel pipe tower of a transmission line according to claim 1, characterized in that: The operation monitoring data of the transmission line steel pipe tower in step S1 includes characteristic parameters of the steel pipe tower's damage during breeze vibration, and parameters of the cause of damage to the steel pipe components analyzed in combination with the on-site environment; The historical wind speed meteorological data of the area where the steel pipe tower is located includes historical hourly wind speed and wind direction, and the wind speed range is set according to the wind force level reported on site and the national standard, and several wind speed parameters are selected according to the wind speed range.

3. The method for analyzing breeze vibration of a steel pipe tower of a transmission line according to claim 1, characterized in that: The characteristic parameters of the steel pipe tower in step S1 include the length, diameter, wall thickness, material, material density, mass ratio and damping ratio of the tower.

4. The method for analyzing breeze vibration of a steel pipe tower of a transmission line according to claim 2, characterized in that: In step S2, the main parameters causing the vortex-induced vibration response of the steel tube tower component are obtained by analytical method, namely, wind speed, wind direction and turbulence.

5. The method for analyzing breeze vibration of a steel pipe tower of a transmission line according to claim 1, characterized in that: In step S3, the three-dimensional finite element model is refined, including a structural model consistent with the actual component geometric parameters, and various connection types representing the node constraints of the rods.

6. The method for analyzing breeze vibration of a steel pipe tower of a transmission line according to claim 1, characterized in that: The specific steps for calculating the natural frequency, critical wind speed and maximum amplitude of the component in step S3 are: S3.1 The natural frequencies of each order of vibration of steel pipe components are: The vibration mode function of the steel pipe component is: Φ(x)=A coshβx+B sinhβx+C cosβx+D sinβx In the formula, the undetermined constants A, B, C, and D are determined by the boundary conditions at both ends of the beam. The free vibration response of the steel tube member is the superposition of the responses of each mode, so: S3.2 Calculate the tower's initial wind speed using the tower frequency and the Stauhal number for circular cross-sections: Where U cr is the vortex vibration initiation wind speed, S t is the Stothal number, f0 is the tower frequency, and D is the circular cross section; S3.3 According to structural dynamics, the maximum amplitude expression can be obtained by combining the structural mass and vibration frequency: Where μ max is the maximum value of the dynamic amplification coefficient, m is the structural mass per unit length, ξ is the structural damping ratio, ω n is the structure's natural circular frequency, ω s is the vortex shedding frequency, φ is the initial phase, D is the characteristic size of the rod, and for a circular rod, the cross-sectional diameter is taken, ρ a is the air density, U is the incoming wind speed, C L is the amplitude of the structural dynamic lift coefficient.

7. The method for analyzing breeze vibration of a steel pipe tower of a power transmission line according to claim 1, characterized in that: The specific steps of the vortex-induced vibration response process embedded in the FLUENT software in step S4 to reproduce complex working conditions are as follows: S4.3 Set the wind speed range based on the wind force level reported on site and the national standard, and select several wind speed parameters based on the wind speed range; calculate the correlation between the vortex-induced vibration response of the steel pipe and the main controlling factors based on the breeze field and the steel pipe characteristic parameters; Establish displacement time history curve, lift time history curve, drag time history curve, lift coefficient time history curve, and drag coefficient time history curve, and obtain the frequency corresponding to the maximum vortex-induced vibration characteristic value based on fast Fourier transform (FFT); The characteristic parameters of the breeze field and steel pipe include wind speed, turbulence, mass ratio, damping ratio, mass damping ratio SG and wind direction angle combination conditions; S4.4 Establish a vortex-induced vibration model for adjacent steel pipes, analyze the vortex-induced vibration interference effect of adjacent steel pipes in a wind field environment, and provide suggestions for optimizing the vibration suppression scheme.

8. The method for analyzing breeze vibration of a steel pipe tower of a power transmission line according to claim 1, characterized in that: The specific steps of vortex-induced vibration calculation in step S4.2 are: S4.2.1 The entire calculation starts with the steel tubular tower members at rest in the equilibrium position. Determine the initial conditions for the first iteration. S4.2.2 Use the transverse displacement and velocity of the steel tubular tower members and the wind lift on the members obtained in the previous time step as the initial conditions for the solution in the current time step; S4.2.3 Using the initial conditions, solve the equations of motion of the steel tubular tower members using the fourth-order Runge-Kutta method to obtain the displacement and velocity of the steel tubular tower members at the current time step; S4.2.4 Assign the desired velocity of the steel tubular tower member to the member boundary and the mesh area that undergoes rigid body motion with the member using a UDF program, and update the position of this mesh area. Simultaneously, adjust the external mesh adjacent to the mesh boundary using a dynamic mesh technique. S4.2.5 Use Fluent software to solve the discrete equations to obtain the flow field characteristic values ​​of velocity and pressure at the current time step. Use the "Computer_Force_Moment" macro to extract the lift force exerted by the wind on the current steel pipe tower member. S4.2.6 Obtain the structural response and flow field forces on the members in the current time step, and use them as the initial conditions for the next time step. Repeat this cycle until the calculation is complete. The change of the structure's position in the flow field is achieved through grid movement. The boundary surface between the flow field and the structure is given a velocity, so the boundary conditions change when solving the flow field, realizing the fluid-solid coupling process between the steel pipe and the wind field during breeze vibration.

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