Method for determining windage yaw of iced suspension insulator string in high altitude area and related system

Abstract

The application discloses a high-altitude icing suspension insulator string wind deviation determination method and a related system, comprising an input unit, a finite element model construction unit, a self-weight load application unit, a transient wind load application unit and a solving unit. Firstly, the structural parameters and meteorological parameters of a line are acquired. Then, a finite element model of a suspension insulator string and a structure connected therewith is constructed according to the structural parameters of the line. Secondly, the self-weight load is applied. In the simulation of a wind speed field, a drag coefficient is introduced, and the air density is corrected according to the influence of the altitude and the environmental temperature on the air characteristics, so that the transient wind load is obtained, and then the transient wind load is applied to the finite element model. Finally, the finite element software is used for solving, the node displacement array of the suspension insulator string is obtained, and the wind deviation angle is converted according to the geometric relationship. The application can accurately apply the wind load and accurately solve the wind deviation angle, so that the wind deviation precision is high.

Description

Technical Field

[0001] This invention relates to a method and related system for determining the wind deflection of suspension insulator strings in icing transmission lines at high altitudes, belonging to the technical field of wind deflection calculation for insulator strings. Background Technology

[0002] my country has a vast territory with diverse and complex topography, including mountains, hills, plateaus, plains, and basins, with plateaus accounting for more than a quarter of the country's total land area. With the continuous advancement of ultra-high voltage and extra-high voltage (UHV) projects and the rapid development of digital power grids, transmission lines inevitably cross high-altitude and heavily icy areas. This undoubtedly poses a significant challenge to the disaster resistance capabilities of overhead conductors, ground wires, insulator strings, and transmission towers in these regions. Therefore, maintaining the safe operation of transmission lines in these areas is of great importance to the long-term stable operation of my country's power grid in plateau regions.

[0003] According to feedback from on-site maintenance personnel, flashover accidents caused by strong winds are particularly prominent in high-altitude areas. Each year, wind-induced tripping incidents account for more than 50% of all incidents across different voltage levels. Insufficient insulation safety distance caused by wind deflection of suspension insulator strings is the primary cause of these trips. If reclosing fails after a wind-induced trip, the line will be out of service, affecting the reliability of the power grid and causing significant economic losses to society and the public.

[0004] Meanwhile, the impact of icing on line structure wind deflection of suspension insulator strings is two-sided. On the one hand, icing increases the vertical load on the line structure, thereby increasing the tension on the suspension insulator strings and effectively suppressing wind deflection. On the other hand, icing increases the wind-exposed area of ​​the line structure, thereby increasing the horizontal load and promoting wind deflection. Therefore, the actual impact of icing on wind deflection needs to be considered in conjunction with specific environmental conditions and cannot be generalized, which contributes to the complexity of wind deflection problems in high-altitude icing areas. Summary of the Invention

[0005] Purpose of the invention: In order to solve the problem of low accuracy in wind deflection calculation in the prior art, the present invention provides a method for determining wind deflection of ice-covered suspension insulator strings in high-altitude areas.

[0006] Technical solution: To achieve the above objectives, the technical solution adopted by this invention is as follows:

[0007] A method for determining wind deflection of icy suspension insulator strings in high-altitude areas includes the following steps:

[0008] Step 1: Obtain the structural and meteorological parameters of the line.

[0009] Step 2: Construct a finite element model of the suspension insulator string and its connected structures based on the structural parameters of the line.

[0010] Step 3: Apply self-weight load to the finite element model based on the structural parameters of the line. The wind speed field simulation is determined based on meteorological parameters. A drag coefficient is introduced into the wind speed field simulation, and the air density is corrected according to the influence of altitude and ambient temperature on air characteristics to obtain the instantaneous wind load. Then, the instantaneous wind load is applied to the finite element model.

[0011] Step 4: Solve the finite element model, self-weight load and instantaneous wind load using finite element software to obtain the corresponding nodal displacement array of the suspension insulator string, and then convert the nodal displacement array into the corresponding wind deflection angle according to the geometric relationship.

[0012] Preferably, the formula for the instantaneous wind load in step 3 is:

[0013] ;

[0014] In the formula, For the instantaneous wind load in the horizontal direction, The instantaneous wind load is in the vertical direction, He is the local average altitude, and T is the instantaneous wind load. a Let be the average air temperature under local icing conditions, h be the equivalent annular ice thickness, U be the horizontal average wind speed, u be the horizontal fluctuating wind speed, v be the vertical instantaneous fluctuating wind speed, and V be the instantaneous wind speed. It is the symbol for scientific notation.

[0015] Preferably, the method for obtaining the instantaneous wind load in step 3 is as follows:

[0016] Step 321: In the simulation of the wind speed field, the AR linear filtering method is used to simulate the random pulsating wind speed field in the direction of the wind along and across at the spatial point, and then the average wind speed field is superimposed to obtain the actual instantaneous wind speed field in the local area.

[0017] Step 322, Calculation of wind load:

[0018] The instantaneous wind load component of the icing section is obtained by means of the drag coefficient c d Calculate with instantaneous wind speed V:

[0019] ;

[0020] In the formula, F d The instantaneous wind resistance on the icing section is given by ρ, air density under icing conditions, instantaneous wind speed, and equivalent annular ice thickness. d (V,h) represents the drag coefficient.

[0021] ;

[0022] Considering the influence of altitude and ambient temperature on air properties, the air density ρ is corrected using the following formula:

[0023] ;

[0024] In the formula, He is the local average altitude, and T is... a This represents the average temperature under local icing conditions.

[0025] Transforming the obtained instantaneous wind load into the global coordinate system XOY, we get:

[0026] ;

[0027] In the formula, For the instantaneous wind load in the horizontal direction, Let ρ be the instantaneous wind load in the vertical direction, ρ be the air density under icing conditions, h be the equivalent annular ice thickness, U be the horizontal average wind speed, u be the horizontal fluctuating wind speed, and c be the instantaneous wind load in the vertical direction. d (V,h) is the drag coefficient, V is the instantaneous wind speed, and v is the instantaneous pulsating wind speed in the vertical direction.

[0028] Preferably, the simulation method for the wind speed field in step 321 is as follows:

[0029] The mean wind speed profile of the atmospheric boundary layer within a certain altitude range is described by the following exponential law:

[0030] ;

[0031] In the formula, U is the average wind speed at a height z above the ground. r Reference height (z) r The average wind speed at point z r The reference height is α, and the wind speed profile index is α.

[0032] Consider the influence of downwind and crosswind pulsating wind vibration response on the wind deflection process:

[0033] ;

[0034] In the formula, n is the pulsation frequency. For the power spectrum of downwind pulsating wind, σ u The root variance of the downwind fluctuating wind speed. For dimensionless frequency, , The longitudinal turbulence integral scale is used.

[0035] ;

[0036] In the formula, u * This represents the surface friction velocity. Z is the von Kármán constant, and z0 is a parameter reflecting the surface roughness.

[0037] Crosswind pulsating wind power spectrum S v (n) is expressed as follows:

[0038] ;

[0039] In the formula, For a dimensionless frequency, x = n·z / U(z). The root variance of the crosswind pulsating wind speed.

[0040] ;

[0041] In the formula, u * This represents the surface friction velocity.

[0042] The AR linear filtering method is used to simulate the random pulsating wind speed field in the direction of the wind along and across at a spatial point. The established average wind speed field is then superimposed to obtain the actual instantaneous wind speed field in the local area, which is used for subsequent wind load calculation.

[0043] Preferably, the method for solving the problem using finite element software in step 4 is as follows:

[0044] Step 41, wind deflection is described using the following basic equations of motion for transient dynamics:

[0045] [ M ]{ u ¨ } + [ C ]{ u ˙ } + [ K ]{ u } = { F ( t )} ;

[0046] In the formula, [M] is the mass matrix of the structure, [C] is the damping matrix of the structure, and [K] is the stiffness matrix of the structure. For nodal displacement arrays, For the node velocity array, For the node acceleration array, For nodal load arrays.

[0047] Step 42: Convert the obtained instantaneous wind load into the corresponding nodal load array. The displacements are applied to the corresponding nodes of the finite element model. The Newmark method, a step-by-step integration method in the time domain of ANSYS software, is used to solve the problem, yielding the corresponding nodal displacement array of the suspension insulator string. Then, based on the geometric relationship, it can be converted into the corresponding wind deflection angle.

[0048] Preferably, the method for obtaining the self-weight load in step 3 is as follows:

[0049] The self-weight load of the suspension insulator string model is achieved by setting the linear density of the real material and applying a gravitational field.

[0050] The process of applying the conductor's self-weight load is called form finding, and the initial form finding is performed using the suspension cable analysis method.

[0051] Preferably, the method for constructing the finite element model of the suspension insulator string and its connected structure based on the structural parameters of the line in step 2 is as follows:

[0052] Step 21: Construct and constrain the finite element model of the suspension insulator string based on the structural parameters of the line.

[0053] Based on the different mechanical properties exhibited by suspension insulator strings during wind deflection, different types of units are selected for simulation, namely simulation of porcelain / glass insulator strings and simulation of composite insulator strings.

[0054] The porcelain / glass insulator string is simulated using rigid beam elements to represent a single insulator, and the connection between different elements is hinged.

[0055] The composite insulator string was simulated using ordinary beam elements, and was divided into multiple beam elements according to the actual length of the composite insulator string. The connection between different elements was rigid.

[0056] The upper end of the suspension insulator string is directly hinged.

[0057] Step 22: Construct and constrain the finite element model of the conductor based on the structural parameters of the line.

[0058] Rod elements are used to simulate a tensioned conductor, and the connection between different rod elements is rigid.

[0059] The end hanging point of the conductor is usually located on the tension tower on both sides of the tension section. The conductor is connected to it through a string of tension insulators. Due to the rotational effect of the insulator string and the hanging point, as well as the deformation of the conductor itself, only the three translational degrees of freedom and the torsional degree of freedom around the conductor axis of the node are constrained.

[0060] Preferably, the structural parameters of the line include the insulator string type and its corresponding parameters, the conductor type and its corresponding parameters, the adjacent span, the elevation difference, and the local average altitude. The meteorological parameters include the local temperature, the equivalent ice thickness of the conductor / suspension insulator string ring, the ice type, and the instantaneous wind speed.

[0061] Another objective of this invention is to provide a system for determining the wind deflection of ice-covered suspended insulator strings in high-altitude areas, used to implement the method for determining the wind deflection of ice-covered suspended insulator strings in high-altitude areas. The system includes an input unit, a finite element model construction unit, a self-weight load application unit, an instantaneous wind load application unit, and a solution unit, wherein:

[0062] The input unit is used to acquire the structural parameters and meteorological parameters of the line.

[0063] The finite element model building unit is used to construct a finite element model of the suspension insulator string and its connected structure based on the structural parameters of the line.

[0064] The self-weight load application unit is used to apply self-weight load to the finite element model according to the structural parameters of the line.

[0065] The instantaneous wind load application unit is used to simulate the wind speed field based on meteorological parameters. The drag coefficient is introduced into the simulation of the wind speed field, and the air density is corrected according to the influence of altitude and ambient temperature on air characteristics to obtain the instantaneous wind load. Then, the instantaneous wind load is applied to the finite element model.

[0066] The solving unit is used to solve the finite element model, self-weight load and instantaneous wind load using finite element software to obtain the corresponding nodal displacement array of the suspension insulator string, and then convert the nodal displacement array into the corresponding wind deflection angle according to the geometric relationship.

[0067] Another object of the present invention is to provide an electronic device comprising: at least one processor, at least one memory, and a communication interface. The processor, memory, and communication interface communicate with each other. The memory stores program instructions executable by the processor, which invokes the program instructions to execute the method for determining the wind deflection of ice-covered suspension insulator strings in high-altitude areas.

[0068] Compared with the prior art, the present invention has the following advantages:

[0069] By fully considering the dual impact of line icing on wind deflection, this study achieves accurate application of wind load and accurate calculation of wind deflection angle by modifying air characteristic parameters in high-altitude areas and introducing aerodynamic coefficients, resulting in high accuracy of wind deflection calculation. Furthermore, the calculation process is standardized and generalized, greatly improving the applicability of the wind deflection calculation method in high-altitude areas. The results can provide a reference for the design of transmission lines in plateau regions and the prevention of wind and snow disasters. Attached Figure Description

[0070] Figure 1 This is a calculation model for the rigid body static method.

[0071] Figure 2 This is a schematic diagram of the instantaneous wind load acting on the equivalent annular ice-covered cross section.

[0072] Figure 3 This is a schematic diagram of the structural parameters of the line.

[0073] Figure 4 This refers to the finite element model and its constraints (after traverse form finding).

[0074] Figure 5The wind speed simulation results are for the midpoint of L1 in the first gear over a period of 30 minutes.

[0075] Figure 6 The wind load is applied to the finite element model at the initial moment. Detailed Implementation

[0076] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the invention. After reading this invention, any modifications of the invention in various equivalent forms by those skilled in the art will fall within the scope defined by the appended claims.

[0077] Example

[0078] Currently, wind deflection calculations for suspension insulator strings are mostly based on rigid straight bar models, combined with the principle of static equilibrium to calculate the wind deflection angle. This is also the method recommended in my country's overhead transmission line design specifications, hereinafter referred to as the rigid static method.

[0079] like Figure 1 As shown, the rigid body static method treats the suspension insulator string as a rigid rod with uniform mass distribution, whose upper end is connected to the crossarm by a hinge, and whose own weight G j and the horizontal wind load F j Acting at its centroid (at 1 / 2 the length of the rod), the gravity of the conductor and G d The wind load F in the horizontal direction of the conductor d The stabilizing effect is at its lower end.

[0080] According to the principle of moment balance in statics, taking moments about point O, the formula for calculating the wind deflection angle θ is:

[0081] ;

[0082] The rigid body static method model is simple and intuitive, but it considers only a single factor and does not take into account the dynamic process of wind deflection of suspension insulator strings. In actual line engineering, the wind field has certain pulsating characteristics, which in turn has a certain dynamic amplification effect on the wind deflection of suspension insulators. Therefore, the wind deflection calculation results of the rigid body static method are often underestimated. To address this, this embodiment provides a method for determining the wind deflection of icing suspension insulator strings in high-altitude areas. By constructing a finite element model that conforms to the mechanical characteristics of suspension insulator strings and overhead conductors, correcting the air characteristic parameters of high-altitude areas, and introducing the aerodynamic coefficient of the icing windward side, the method can accurately calculate the wind deflection angle under real wind field conditions and line icing conditions in high-altitude areas. The specific steps include:

[0083] Step 1: Obtain the structural and meteorological parameters of the line.

[0084] In another embodiment, the structural parameters of the line include the insulator string type and its corresponding parameters, the conductor type and its corresponding parameters, the adjacent span, the height difference, the local average altitude, etc., while the meteorological parameters include the local temperature, the equivalent ice thickness of the conductor / suspension insulator string ring, the ice type, the instantaneous wind speed, etc.

[0085] Step 2: Construct a finite element model of the suspension insulator string and its connected structures based on the structural parameters of the line.

[0086] In another embodiment, the method for constructing the finite element model of the suspension insulator string and its connected structure based on the structural parameters of the line in step 2 is as follows:

[0087] Step 21, Construction and Constraint of Finite Element Model of Suspension Insulator String

[0088] Based on the different mechanical properties exhibited by suspension insulator strings during wind deflection, different types of units are selected for simulation.

[0089] For porcelain / glass insulator strings: Each insulator hardly deforms during wind deflection, so it is assumed to be a rigid body. Wind deflection bending is caused by the ball joint connection between the steel foot and steel cap of adjacent insulators. Therefore, rigid beam elements are used to simulate a single insulator, and the connection between different elements is a hinge.

[0090] For composite insulator strings: wind-induced bending is due to the low stiffness of the material itself, so ordinary beam elements are used for simulation, and the actual composite insulator string is divided into multiple beam elements according to its length. The connection between different elements is rigid.

[0091] In actual engineering, the upper end of the suspension insulator string is often connected to the transmission tower by a U-shaped ring, which allows for relatively free rotation. Since the wind deflection calculation process does not involve the mechanical calculation of the transmission tower, the upper end of the suspension insulator string is directly hinged, that is, the three translational degrees of freedom of the node are constrained, and the three rotational degrees of freedom are released.

[0092] Step 22, Construction and Constraints of the Finite Element Model of the Conductor

[0093] As a typical flexible cable structure, the mechanical model of overhead transmission lines is mainly based on the following assumptions: the cable material obeys Hooke's Law; the cable can only be subjected to tension and not compression. Therefore, rod elements are used to simulate the tensioned conductor, and the connection between different rod elements is rigid.

[0094] The end hanging point of the conductor is usually located on the tension tower on both sides of the tension section (which includes multiple straight sections). The conductor is connected to it through a string of tension insulators. Due to the rotational effect of the insulator string and the hanging point, as well as the deformation of the conductor itself, only the three translational degrees of freedom and the torsional degree of freedom around the conductor axis of the node are constrained.

[0095] Step 3: Apply self-weight load to the finite element model based on the structural parameters of the line. The wind speed field simulation is determined based on meteorological parameters. A drag coefficient is introduced into the wind speed field simulation, and the air density is corrected according to the influence of altitude and ambient temperature on air characteristics to obtain the instantaneous wind load. Then, the instantaneous wind load is applied to the finite element model.

[0096] Step 31, self-weight load.

[0097] The self-weight load of the suspension insulator string model is achieved by setting the linear density of the real material and applying a gravitational field.

[0098] The process of applying the conductor's self-weight load is called form finding. This is a necessary step before performing any static or dynamic analysis on cable-stayed structures. Only through form finding can the initial position and stress distribution of the conductor before wind deflection be accurately obtained. In another embodiment, the cable-stayed analysis method is used for initial form finding. The specific form finding steps are as follows:

[0099] A. Create a geometric model at the chord position determined by the span and height difference, set the corresponding real constants according to the actual conductor material parameters, and set a small initial strain to obtain solution stability.

[0100] B. After meshing the conductor geometry model, convert it into a corresponding finite element model. Apply a vertical gravity field load and solve the problem. Update the geometry of the conductor by updating the finite element model until the convergence condition is met: the horizontal tension component of the conductor is equal to 38% of the rated breaking force. The initial position and stress distribution of the conductor under self-weight load are obtained.

[0101] In another embodiment, the instantaneous wind load in step 3 is obtained as follows:

[0102] Step 32, application of wind load.

[0103] Step 321, simulation of wind speed field.

[0104] Statistical analysis of a large amount of measured wind speed data shows that the instantaneous wind field under natural conditions can be regarded as the superposition of the time-domain average wind field and the instantaneous fluctuating wind field. The present invention uses the following method to simulate the actual wind speed field:

[0105] The mean wind speed profile of the atmospheric boundary layer within a certain altitude range is described by the following exponential law:

[0106] ;

[0107] In the formula, U is the average wind speed at a height z above the ground. r Reference height (z) r The average wind speed at point zr The reference height is usually 10m, and α is the wind speed profile index, which corresponds to different values ​​for different surface types. This invention adopts the values ​​in my country's "Code for Design of Building Structures GB5009-2012": for four categories, namely offshore, rural, urban, and large city center, the indices are 0.12, 0.15, 0.22, and 0.30, respectively.

[0108] Pulsating wind fields are the turbulent components of wind fields. Their intensity varies randomly with time and space, and their periods are short, thus exerting a pulsating force on structures. This embodiment primarily considers the influence of downwind and crosswind pulsating wind vibration responses on the wind deflection process. The downwind pulsating wind power spectrum S... u (z,n) adopts the empirical formula for wind spectrum proposed by Theodore von Karman in 1948 based on the assumption of isotropic turbulence, and is later improved by Harris:

[0109] ;

[0110] In the formula, n is the pulsation frequency. For the power spectrum of downwind pulsating wind, σ u The root variance of the downwind fluctuating wind speed. For dimensionless frequency, , It is the longitudinal turbulence integral scale, and typically has the following: .

[0111] ;

[0112] In the formula, u * This represents the surface friction velocity. Z is the von Kármán constant, typically taken as 0.4. Z0 is a parameter reflecting the roughness of the earth's surface, given by empirical values, such as 0.01~0.05m in open grasslands, 0.1~0.5m in suburban areas, and 1~5m in densely built-up urban centers.

[0113] Crosswind pulsating wind power spectrum S v (n) uses the following empirical expression:

[0114] ;

[0115] In the formula, For a dimensionless frequency, x = n·z / U(z). The root variance of the crosswind pulsating wind speed.

[0116] ;

[0117] In the formula, u * Surface friction speed

[0118] The AR linear filtering method is used to simulate the random pulsating wind speed field in the direction of the wind along and across at a spatial point. The established average wind speed field is then superimposed to obtain the actual instantaneous wind speed field in the local area, which is used for subsequent wind load calculation.

[0119] Step 322, Calculation of wind load:

[0120] The instantaneous wind load acting on the equivalent annular icing cross section is as follows: Figure 2 As shown, Figure 2 In the middle, U represents the horizontal average wind speed. Considering the influence of fluctuating wind speed, the instantaneous wind speed in the horizontal direction (X-axis) is U+u (where u is the fluctuating wind speed in the horizontal direction), and the instantaneous fluctuating wind speed in the vertical direction (Y-axis) is v. Therefore, the actual instantaneous incoming wind speed in the structure is V ( ), and the angle of V relative to the direction of the average wind speed is δ. F d ρ is the resistance of the instantaneous wind to the icing cross section; h is the thickness of the equivalent annular icing.

[0121] Based on Bernoulli's equation and the quasi-steady assumption, the instantaneous wind load component of the icing section is determined using the drag coefficient c. d Calculate with instantaneous wind speed V:

[0122] ;

[0123] In the formula, F d The instantaneous wind resistance on the icing section is given by ρ, air density under icing conditions, instantaneous wind speed, and equivalent annular ice thickness. d (V,h) is the drag coefficient, a function of instantaneous wind speed V and equivalent annular ice thickness h, which can be solved using the following expression:

[0124] ;

[0125] In the formula, It is the symbol for scientific notation.

[0126] Considering the influence of altitude and ambient temperature on air properties, the air density ρ is corrected using the following formula:

[0127] ;

[0128] In the formula, He is the local average altitude, and T is... a This represents the average temperature under local icing conditions.

[0129] Transforming the obtained instantaneous wind load into the global coordinate system XOY, we get:

[0130] ;

[0131] In the formula, For the instantaneous wind load in the horizontal direction, Let ρ be the instantaneous wind load in the vertical direction, ρ be the air density under icing conditions, h be the equivalent annular ice thickness, U be the horizontal average wind speed, u be the horizontal fluctuating wind speed, and c be the instantaneous wind load in the vertical direction. d (V,h) is the drag coefficient, V is the instantaneous wind speed, and v is the instantaneous pulsating wind speed in the vertical direction.

[0132] The formula for instantaneous wind load is:

[0133]

[0134] In the formula, For the instantaneous wind load in the horizontal direction, The instantaneous wind load is in the vertical direction, He is the local average altitude, and T is the instantaneous wind load. a Let be the average air temperature under local icing conditions, h be the equivalent annular ice thickness, U be the horizontal average wind speed, u be the horizontal fluctuating wind speed, v be the vertical instantaneous fluctuating wind speed, and V be the instantaneous wind speed. It is the symbol for scientific notation.

[0135] Step 4, calculate the wind deflection.

[0136] The finite element model, self-weight load, and instantaneous wind load are solved using finite element software to obtain the corresponding nodal displacement array of the suspension insulator string. Then, based on geometric relationships, the nodal displacement array is converted into the corresponding wind deflection angle.

[0137] Step 41: Wind deflection in practical engineering is a typical nonlinear dynamics problem, which is described by the following basic equations of motion of transient dynamics:

[0138] [ M ]{ u ¨ } + [ C ]{ u ˙ } + [ K ]{ u } = { F ( t )} ;

[0139] In the formula, [M] is the mass matrix of the structure, [C] is the damping matrix of the structure, and [K] is the stiffness matrix of the structure. For nodal displacement arrays, For the node velocity array, For the node acceleration array, For nodal load arrays.

[0140] Step 42: Convert the nodal wind loads obtained according to formula (10) into the corresponding nodal load arrays. The displacements are applied to the corresponding nodes of the finite element model. The Newmark method, a step-by-step integration method in the time domain of ANSYS software, is used to solve the problem, yielding the corresponding nodal displacement array of the suspension insulator string. Then, based on the geometric relationship, it can be converted into the corresponding wind deflection angle.

[0141] Due to the nonlinearity of the structure itself and the complexity of actual wind loads, it is difficult to obtain analytical solutions for the structure. Therefore, the large-scale commercial finite element software ANSYS is used to obtain numerical solutions for the above motion equations.

[0142] Step 421: First, the basic finite element model is constructed. The corresponding structural mass matrix [M] and stiffness matrix [K] can be automatically generated in the software.

[0143] Step 422, the damping matrix of the structure is calculated using the Rayleigh damping model:

[0144] [ C ] = α [ M ] + β [ K ] ;

[0145] In the formula: α and β are the mass damping coefficient and stiffness damping coefficient, respectively, which can be calculated from the modal damping ratio.

[0146] ;

[0147] In the formula: w1 and w2 are the first and second natural frequencies of the structure, respectively, which can be obtained through modal analysis or experiments of the structure; For constant damping ratios, the recommended values ​​are as follows: for uniced structures Take 5% for icing structures Take 2%.

[0148] Step 423: Convert the instantaneous wind load obtained in step 3 into the corresponding nodal load array. It is applied to the corresponding nodes of the finite element model.

[0149] Step 424: The Newmark method in the time-domain successive integration method of ANSYS software is used to solve the problem and obtain the corresponding nodal displacement array of the suspension insulator string. Then, based on the geometric relationship, it can be converted into the corresponding wind deflection angle.

[0150] In another embodiment, a system for determining the wind deflection of ice-covered suspended insulator strings in high-altitude areas is provided. This system implements the method for determining the wind deflection of ice-covered suspended insulator strings in high-altitude areas. It includes an input unit, a finite element model construction unit, a self-weight load application unit, an instantaneous wind load application unit, and a solution unit, wherein:

[0151] The input unit is used to acquire the structural parameters and meteorological parameters of the line.

[0152] The finite element model building unit is used to construct a finite element model of the suspension insulator string and its connected structure based on the structural parameters of the line.

[0153] The self-weight load application unit is used to apply self-weight load to the finite element model according to the structural parameters of the line.

[0154] The instantaneous wind load application unit is used to simulate the wind speed field based on meteorological parameters. The drag coefficient is introduced into the simulation of the wind speed field, and the air density is corrected according to the influence of altitude and ambient temperature on air characteristics to obtain the instantaneous wind load. Then, the instantaneous wind load is applied to the finite element model.

[0155] The solving unit is used to solve the finite element model, self-weight load and instantaneous wind load using finite element software to obtain the corresponding nodal displacement array of the suspension insulator string, and then convert the nodal displacement array into the corresponding wind deflection angle according to the geometric relationship.

[0156] In another embodiment, an electronic device is provided, comprising: at least one processor, at least one memory, and a communication interface. The processor, memory, and communication interface communicate with each other. The memory stores program instructions executable by the processor, which invokes the program instructions to execute the method for determining the wind deflection of icing-covered suspension insulator strings in high-altitude areas.

[0157] simulation

[0158] Taking one phase of a tension span (two straight spans) of a 500kV overhead transmission line in Tibet, my country as an example, the feasibility of the wind deflection calculation method proposed in this invention is introduced.

[0159] S1. Obtain the structural and meteorological parameters of the line, as follows: Figure 3 As shown in Table 1.

[0160] Table 1. Line Structure and Meteorological Parameters

[0161] Parameter name value Parameter name value <![CDATA[L1(m)]]> 345 <![CDATA[H1(m)]]> 20 <![CDATA[L2(m)]]> 500 <![CDATA[H2(m)]]> -20 wire type 4×LGJ-300 / 40 Insulator string model FXBW-500 / 160 Average wind speed (m / s) at a reference height of 10m 20 Equivalent annular icing thickness of insulator string (mm) 20 Equivalent ring-shaped icing thickness of the conductor (mm) 20 Icing type Mixed pine

[0162] S2. Construct a finite element model of the suspension insulator string and its connected structures.

[0163] Based on the aforementioned parameters, construct one phase finite element model of the tension span (two straight spans) and its constraints as follows: Figure 4 As shown.

[0164] S3. Apply load.

[0165] The AR linear filtering method (AR model order 5) is used to simulate the random fluctuating wind speed fields in the along and across directions at different locations of the structure. By superimposing the average wind speed field, the instantaneous wind speed at different nodes can be simulated. Figure 5 The simulation results of wind speed at the midpoint of L1 in the first gear are shown over a 30-minute period.

[0166] The initial wind load applied to the finite element model is as follows: Figure 6 As shown.

[0167] S4. Calculation of wind deflection.

[0168] Modal analysis yielded the first two natural frequencies of the structure to be 0.144520 Hz and 0.200715 Hz, respectively. The damping ratio under icing conditions was constant. Taking 2%, the mass damping coefficient α and stiffness damping coefficient β in the Rayleigh damping model can be determined to be 0.0336 and 1.1586, respectively, using the modal damping ratio calculation formula. The corresponding damping matrix is ​​constructed, and the Newmark method is used to solve it, yielding a maximum wind deflection angle of 33.1937°.

[0169] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for determining the wind deflection of ice-covered suspension insulator strings in high-altitude areas, characterized in that, Includes the following steps: Step 1: Obtain the structural and meteorological parameters of the line; Step 2: Construct a finite element model of the suspension insulator string and its connected structures based on the structural parameters of the line; Step 3: Apply self-weight load to the finite element model according to the structural parameters of the line; determine the simulation of the wind speed field according to the meteorological parameters, introduce the drag coefficient in the simulation of the wind speed field, and at the same time correct the air density according to the influence of altitude and ambient temperature on air characteristics to obtain the instantaneous wind load, and then apply the instantaneous wind load to the finite element model. The instantaneous wind load is obtained as follows: Step 321: In the simulation of the wind speed field, the AR linear filtering method is used to simulate the random pulsating wind speed field in the direction of the wind along and across the spatial point, and then the average wind speed field is superimposed to obtain the actual instantaneous wind speed field in the local area. Step 322, Calculation of wind load: The instantaneous wind load component of the icing section is obtained by means of the drag coefficient c d Calculate with instantaneous wind speed V: ； In the formula, F d The instantaneous wind resistance on the icing section is given by ρ, air density under icing conditions, instantaneous wind speed, and equivalent annular ice thickness. d (V,h) is the drag coefficient; ； Considering the influence of altitude and ambient temperature on air properties, the air density ρ is corrected using the following formula: ； In the formula, He is the local average altitude, and T is... a The average temperature under local icing conditions; Transforming the obtained instantaneous wind load into the global coordinate system XOY, we get: ； In the formula, For the instantaneous wind load in the horizontal direction, Let ρ be the instantaneous wind load in the vertical direction, ρ be the air density under icing conditions, h be the equivalent annular ice thickness, U be the horizontal average wind speed, u be the horizontal fluctuating wind speed, and c be the instantaneous wind load in the vertical direction. d (V,h) is the drag coefficient, V is the instantaneous wind speed, and v is the instantaneous pulsating wind speed in the vertical direction; The formula for instantaneous wind load is: In the formula, For the instantaneous wind load in the horizontal direction, The instantaneous wind load is in the vertical direction, He is the local average altitude, and T is the instantaneous wind load. a Let be the average air temperature under local icing conditions, h be the equivalent annular ice thickness, U be the horizontal average wind speed, u be the horizontal fluctuating wind speed, v be the vertical instantaneous fluctuating wind speed, and V be the instantaneous wind speed. The symbol of scientific notation; Step 4: Solve the finite element model, self-weight load and instantaneous wind load using finite element software to obtain the corresponding nodal displacement array of the suspension insulator string, and then convert the nodal displacement array into the corresponding wind deflection angle according to the geometric relationship.

2. The method for determining wind deflection of ice-covered suspension insulator strings in high-altitude areas according to claim 1, characterized in that, The simulation method for the wind speed field in step 321 is as follows: The mean wind speed profile of the atmospheric boundary layer within a certain altitude range is described by the following exponential law: ； In the formula, U is the average wind speed at a height z above the ground. r Reference height (z) r The average wind speed at point z r The reference height is α, and the wind speed profile index is α. Consider the influence of downwind and crosswind pulsating wind vibration response on the wind deflection process: ； In the formula, n is the pulsation frequency. For the power spectrum of downwind pulsating wind, σ u The root variance of the downwind fluctuating wind speed. For dimensionless frequency, , The longitudinal turbulence integral scale; ； In the formula, u * This refers to the surface friction velocity; denoted as the von Kármán constant, and z0 is a parameter reflecting the surface roughness. Crosswind pulsating wind power spectrum S v (n) is expressed as follows: ； In the formula, For a dimensionless frequency, x = n·z / U(z). The root variance of the crosswind fluctuating wind speed; ； In the formula, u * This refers to the surface friction velocity; The AR linear filtering method is used to simulate the random pulsating wind speed field in the direction of the wind along and across at a spatial point. The established average wind speed field is then superimposed to obtain the actual instantaneous wind speed field in the local area, which is used for subsequent wind load calculation.

3. The method for determining wind deflection of ice-covered suspension insulator strings in high-altitude areas according to claim 2, characterized in that, The method for solving the problem using finite element software in step 4 is as follows: Step 41, wind deflection is described using the following basic equations of motion for transient dynamics: ； In the formula, [M] is the mass matrix of the structure, [C] is the damping matrix of the structure, and [K] is the stiffness matrix of the structure. For nodal displacement arrays, For the node velocity array, For the node acceleration array, For nodal load arrays; Step 42: Convert the obtained instantaneous wind load into the corresponding nodal load array. The displacements are applied to the corresponding nodes of the finite element model; the Newmark method in the time-domain stepwise integration method of ANSYS software is used to solve the problem, and the corresponding nodal displacement array of the suspension insulator string is obtained. Then, based on the geometric relationship, it can be converted into the corresponding wind deflection angle.

4. The method for determining wind deflection of ice-covered suspension insulator strings in high-altitude areas according to claim 3, characterized in that: The method for obtaining the self-weight load in step 3 is as follows: The self-weight load of the suspension insulator string model is achieved by setting the linear density of the real material and applying a gravitational field; The process of applying the conductor's self-weight load is called form finding, and the initial form finding is performed using the suspension cable analysis method.

5. The method for determining wind deflection of ice-covered suspension insulator strings in high-altitude areas according to claim 4, characterized in that: The method for constructing the finite element model of the suspension insulator string and its connected structure based on the structural parameters of the line in step 2 is as follows: Step 21: Construct and constrain the finite element model of the suspension insulator string based on the structural parameters of the line; Based on the different mechanical properties exhibited by suspension insulator strings during wind deflection, different types of units are selected for simulation, namely simulation of porcelain insulator strings, simulation of glass insulator strings, and simulation of composite insulator strings. Rigid beam elements are used to simulate single insulators for porcelain insulator strings and glass insulator strings, and the connection between different elements is hinged. The composite insulator string was simulated using ordinary beam elements, and was divided into multiple beam elements according to the actual length of the composite insulator string. The connection between different elements was rigid. The upper end of the suspension insulator string is directly hinged; Step 22: Construct and constrain the finite element model of the conductor based on the structural parameters of the line; A rod element is used to simulate a tensioned conductor, and the connection between different rod elements is rigid. The end hanging point of the conductor is usually located on the tension tower on both sides of the tension section. The conductor is connected to it through a string of tension insulators. Due to the rotational effect of the insulator string and the hanging point, as well as the deformation of the conductor itself, only the three translational degrees of freedom and the torsional degree of freedom around the conductor axis of the node are constrained.

6. The method for determining wind deflection of ice-covered suspension insulator strings in high-altitude areas according to claim 5, characterized in that: The structural parameters of the line include the insulator string type and its corresponding parameters, the conductor type and its corresponding parameters, the adjacent span, the elevation difference, and the local average altitude. The meteorological parameters include the local temperature, the equivalent annular icing thickness of the conductor, the equivalent annular icing thickness of the suspension insulator string, the icing type, and the instantaneous wind speed.

7. A system for determining wind deflection of ice-covered suspension insulator strings in high-altitude areas, characterized in that, The method for determining wind deflection of ice-covered suspension insulator strings in high-altitude areas as described in any of claims 1-6 includes an input unit, a finite element model construction unit, a self-weight load application unit, an instantaneous wind load application unit, and a solution unit, wherein: The input unit is used to acquire the structural parameters and meteorological parameters of the line; The finite element model building unit is used to construct a finite element model of the suspension insulator string and its connected structure based on the structural parameters of the line. The self-weight load application unit is used to apply self-weight load to the finite element model according to the structural parameters of the line; The instantaneous wind load application unit is used to determine the simulation of the wind speed field based on meteorological parameters. The drag coefficient is introduced in the simulation of the wind speed field. At the same time, the air density is corrected according to the influence of altitude and ambient temperature on air characteristics to obtain the instantaneous wind load. Then, the instantaneous wind load is applied to the finite element model. The solving unit is used to solve the finite element model, self-weight load and instantaneous wind load using finite element software to obtain the corresponding nodal displacement array of the suspension insulator string, and then convert the nodal displacement array into the corresponding wind deflection angle according to the geometric relationship.

8. An electronic device, characterized in that, include: At least one processor, at least one memory, and a communication interface; The processor, memory, and communication interface communicate with each other; The memory stores program instructions that can be executed by the processor, which calls the program instructions to execute the method for determining wind deflection of ice-covered suspension insulator strings in any of claims 1-6.

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