A method for identifying a power line type of a power transmission line based on laser point cloud data

Abstract

This invention discloses a method for identifying the type of power transmission line wires based on laser point cloud data. The method comprises the following steps: first, collecting laser point cloud data of the power transmission line; second, selecting point cloud data for fitting the sag formula; third, solving the wind deflection angle ξ of the power transmission line; fourth, flattening the spatial point positions; and fifth, calculating the wire diameter d. This invention utilizes power transmission line laser point cloud survey technology and employs data analysis to determine the type of wires in existing power transmission lines, thereby improving the reliability of the transmission line structure and reducing construction costs. This method solves the technical problem of needing to collect the type of existing wires to provide a basis for subsequent design in power transmission line rewiring and relocation projects.

Description

Technical Field

[0001] The invention relates to a method for distinguishing transmission line wire models based on laser point cloud data, and belongs to the technical field of power equipment. Background Art

[0002] The construction of power transmission lines often involves the connection of new and existing lines. This requires determining the conductor and ground wire types (hereinafter collectively referred to as wires) of existing lines to ensure the safety and reliability of both existing and newly constructed line structures. Currently, the most common method for determining wire types for existing lines is to review and collect relevant information from the power supply company's archives. However, existing lines may undergo multiple relocations after completion, making document retrieval difficult. Furthermore, the collection of erroneous information due to unarchived engineering data may lead to engineering accidents or increased project costs. Therefore, determining wire types is a crucial technical task in such projects. Successful implementation of this task not only helps select appropriate towers, avoiding the cost of replacing smaller towers with larger ones, but also improves the structural reliability of the lines. With the continuous advancement of LiDAR surveying technology, the accuracy of its survey results has also continued to improve, providing a technical foundation for accurately determining wire types. Summary of the Invention

[0003] In power transmission line rewiring and relocation projects, it's necessary to collect the models of existing power lines to provide a basis for subsequent design. Incorrect information can cause engineering accidents or increase project investment. To address this issue, the present invention aims to provide a method for identifying power line wire models based on laser point cloud data. By combining existing laser point cloud survey technology for transmission lines and using data analysis, this method can determine the wire models of existing transmission lines, improve the reliability of transmission line structures, and reduce construction costs.

[0004] The purpose of the present invention is achieved through the following technical solutions:

[0005] A method for identifying the type of power transmission line wires based on laser point cloud data. The laser point cloud data of the transmission line is a collection of spatial points scanned by a laser radar, and the position information of the points is stored in the form of spatial coordinates (x, y, z). The method for identifying the type of power transmission line wires based on laser point cloud data includes the following steps:

[0006] Step 1: Line measurement:

[0007] Collect laser point cloud data of transmission lines;

[0008] Step 2: Select the point cloud data for fitting the sag formula:

[0009] The point cloud data used for calculation should be selected from points that do not contain tension strings in the section; and point cloud data within the range of three times the size of the clamp along the line direction should not be used; the set of all points that meet the above requirements is called {P}, and the projection length of the two farthest points in {P} in the horizontal plane is called the calculated section distance l;

[0010] Select n groups of data in {P}, n ≥ 3; each group of data contains 3 points. To reduce the calculation error, the selection rules are as follows: (1) the 3 points in each group of data should be evenly distributed in the span; (2) the 3 points in each group of data should be selected in the same area of ​​the four cross-sections of the wire;

[0011] Pij is used to represent the n groups of data, i represents the number of groups i = 1, 2, 3...n, j represents the number of points in each group j = 1, 2, 3;

[0012] Step 3: Calculate the wind deflection angle ξ of the power line:

[0013] Select the i-th group of data in Pij, then the normal vector of the plane where Pi1, Pi2, and Pi3 are located is for: Calculating n sets of data separately can get n plane normal vectors. Taking the average of the coordinate components of the n plane normal vectors, we can get the normal vector of the wire in the windage plane, which is recorded as calculate and Angle ξ is the wind deflection angle of the power line. If the calculated angle is an obtuse angle, the complementary angle is taken as the wind deflection angle ξ. In a physical sense, this angle reflects the ratio of the vertical load to the horizontal load on the power line. ξ is expressed as:

[0014]

[0015] Where: ξ is the wind angle;

[0016] p1 is the unit load of the wire, kg / m;

[0017] d is the wire diameter, mm;

[0018] ν is the wind speed at the average height of the power line, m / s;

[0019] α is the wind pressure unevenness coefficient, which can be taken as 1.0 according to the measurement environment;

[0020] μ δc The wire body coefficient is 1.2 when the wire diameter is less than 17mm, and 1.1 when the wire diameter is ≥17mm;

[0021] g is the acceleration due to gravity, which is 9.80665 m / s 2 ;

[0022] Step 4: Planarization of spatial points:

[0023] Through Pij, a parabola equation in space is fitted, and then the data in Pij is converted into two-dimensional data, that is, the spatial point is flattened; the edge point on the side of the calculated span is taken as the calculation origin O'. is the normal vector, calculate the plane equation π' passing through O', project Pij onto π', and get the coordinates of Pij on π';

[0024] Then solve the relative position relationship between Pij' and O'. The specific solution method is as follows: First solve the basis vector in the π' plane This vector is perpendicular to both the π' plane normal vector and The vector is obtained by cross-producting the two vectors and normalizing them to the standard. Then the normal vector of the π' plane is obtained by Cross product and unitize to get another basis vector in the π' plane Then connect Pij' and O' to get the vector O'Pij', which is the vector obtained by subtracting the coordinates of O' from the coordinates of Pij. Take O' as the origin of the Cartesian coordinate plane, then x ij 、y ij are the horizontal and vertical coordinate values ​​of Pij' in the Cartesian coordinate system respectively; after transforming all Pij', we can get the projected plane coordinates of the spatial point;

[0025] Step 5: Calculate the wire diameter d:

[0026] According to step 4, a series of discrete points in the plane coordinates are obtained, and these points are plotted. The maximum point in the y-axis direction is selected along the x-axis, and the approximate projection edge line of the wire is obtained by spline interpolation. The wire diameter is obtained by measuring the distance between multiple edge lines and taking the average value.

[0027] In order to further improve the accuracy of judgment, the following technical measures can be taken:

[0028] Substituting the wire diameter d into formula (1), we can get the relationship between the wind speed ν at the average height of the wire and the unit load p1 of the wire; then verify the wire model through load comparison to improve the accuracy of the analysis and judgment of the wire type;

[0029] The specific method is as follows:

[0030] Step 6: Fitting the wire sag equation:

[0031] The sag equation of the wire is actually a catenary, and the least squares method is used for fitting. The process is as follows: Assume that the sag equation satisfies y=a0+a1x+a2x 2 , through the fourth step of spatial point planarization of the coordinate data (x ij ,y ij), and the matrix equation is obtained by the method of finding the extreme value:

[0032]

[0033] By finding the coefficients a0, a1, and a2 from the matrix equation, we can solve the wire sag equation;

[0034] Step 7. Calculate the specific load and stress based on the fitted sag equation. The specific load is the load per unit length and unit area of ​​the wire, p1, and the stress is the stress of the wire during the survey:

[0035] Take the middle value of the calculated gear spacing l and substitute it into the fitting equation y=a0+a1x+a2x 2 , we can get the maximum sag, that is:

[0036]

[0037] Where: l is the calculated gear spacing, m;

[0038] h is the height difference, i.e. the z-axis coordinate difference of the most edge points at both ends of the span is calculated;

[0039] β is the height difference angle,

[0040] γ is the comprehensive load ratio during measurement, N / (m·mm 2 );

[0041] σ0 is the horizontal stress at each point of the wire during measurement (i.e. the stress at the lowest point of sag), N / mm 2 ;

[0042] (3) In the formula, except for σ0 and γ, all other quantities are known. The proportional relationship between σ0 and γ can be obtained by formula (3);

[0043] Find the fitting equation y=a0+a1x+a2x 2 The derivative y′=tanθ=a1 at O', where θ is the inclination angle of point O':

[0044]

[0045] Substituting the proportional relationship between σ0 and γ obtained from equation (3) into equation (4) can solve for σ0 and γ respectively;

[0046] and

[0047] Where: A is the cross-sectional area of ​​the wire, which can be obtained from the wire diameter d;

[0048] (5) In the formula, only two unknown quantities of the wind speed v at the average height and the unit load p1 of the electric wire are combined with the quantity relation of v and p1 obtained from the formula (1), v is represented by p1, and the wind speed v at the average height of the electric wire and the unit load p1 of the electric wire are obtained by substituting the formula (5); since the electric wire type and the unit load p1 of the electric wire have a one-to-one corresponding relation, the electric wire type obtained from the wire diameter d can be checked through the unit load p1 of the electric wire, and the judgment accuracy is improved.

[0049] Compared with the prior art, the beneficial effects of the present application are: the present application uses the power transmission line laser point cloud surveying technology, adopts data analysis, determines the existing power transmission line wire type, improves the power transmission line structure reliability, and reduces the construction cost. BRIEF DESCRIPTION OF DRAWINGS

[0050] Figure 1 It is a schematic diagram of the cross-sectional area of the electric wire. DETAILED DESCRIPTION

[0051] The present application will be further described below in combination with the drawings and specific embodiments.

[0052] The unmanned aerial vehicle carrying the laser radar lens can shoot the laser point cloud data of the power transmission line, and the data is a collection of spatial points of the object scanned by the laser radar, and the position information of the points is saved in the form of spatial coordinates (x, y, z).

[0053] In the overhead power transmission line, the electric wire mechanics is the basic theory related to the calculation of the electric wire sag, and is also the starting point of the present application. In the calculation theory of the electric wire sag, the rigidity of the electric wire material can be ignored, and the load of the electric wire is uniformly distributed along the line length. It is considered that the shape of the electric wire suspension is a catenary, and the advantage of using the equation of the catenary to describe the electric wire sag is high precision, but the disadvantage is complex formula, which is not convenient to use. The inclined parabolic formula is commonly used in engineering to simplify the calculation of the electric wire sag, and its characteristics are simple formula and convenient to use, and the precision is relatively poor compared with the catenary formula, but it still meets the engineering requirements. The inclined parabolic formula is used to illustrate the principle of the present application.

[0054] The flow of the present application for distinguishing the type of the ground wire is as follows:

[0055] First step, line measurement:

[0056] The laser point cloud data of the power transmission line is shot by the unmanned aerial vehicle carrying the high-precision laser radar lens. In order to reduce the measurement error, the requirements for the environment during the survey are slight wind and no icing on the electric wire, and the point cloud data should cover the electric wire circumference as much as possible. The atmospheric temperature needs to be recorded during the survey.

[0057] Second step, select the point cloud data for fitting the sag formula:

[0058] For a section of wires, along the line direction, the selection of point cloud data should reduce the unknowns in the sag formula and avoid using the isolated section sag formula. Therefore, the point cloud data used for calculation should be selected from points within the section (i.e., between two base towers) that do not contain tension strings. Wire clamps are hardware that grip wires. Various types of wire clamps vary in size and dimensions. Considering the influence of wire stiffness and the grip of tension clamps or suspension clamps on the sag of the conductor, point cloud data within 3 times the size of the wire clamps (tension clamps and suspension clamps) along the line direction should not be used. The set of all points that meet the above requirements is called {P}. The projection length of the two farthest points in {P} in the horizontal plane is called the calculated section distance l.

[0059] Select n sets of data in {P}, usually n≥3. Each set of data contains 3 points. To reduce calculation errors, the selection rules are as follows: (1) The 3 points in each set of data should be evenly distributed in the gear spacing and should not be too close. (2) The 3 points in each set of data should be selected as close as possible. Figure 1 In the same area, the area division in the figure is on the cross section of the wire. Points are taken to fit the curve. In order to make the linear error of the fitted curve equation as small as possible and facilitate data picking, the above-mentioned areas are divided. If the area is not divided, the points taken will be more discrete. For example, points in areas I and III may be taken. The curves fitted by the points in these two areas are not as accurate as the curve fitted by the points in the same area.

[0060] Pij is used to represent the n groups of data, i represents the number of groups i = 1, 2, 3...n, j represents the number of points in each group j = 1, 2, 3. 23 Represents the third point in the second set of data.

[0061] Step 3: Calculate the wind deflection angle ξ of the power line (the wind deflection angle is the angle between the wind deflection plane and the vertical plane):

[0062] Select the i-th group of data in Pij, then the normal vector of the plane where Pi1, Pi2, and Pi3 are located is for: Calculating n sets of data separately can get n plane normal vectors. Taking the average of the coordinate components of the n plane normal vectors, we can get the normal vector of the wire in the wind deflection plane (the wind deflection plane refers to the plane where the wire is located after it is deflected under the action of strong wind load), which is recorded as calculate and Angle ξ is the wind deflection angle of the power line. If the calculated angle is an obtuse angle, the complementary angle is taken as the wind deflection angle ξ. In a physical sense, this angle reflects the ratio of the vertical load to the horizontal load on the power line. ξ can be expressed as:

[0063]

[0064] Where: ξ is the wind angle;

[0065] p1 is the unit load of the wire, kg / m;

[0066] d is the wire diameter, mm;

[0067] ν is the wind speed at the average height of the power line, m / s;

[0068] α is the wind pressure unevenness coefficient, which can be taken as 1.0 according to the measurement environment;

[0069] μ δc The wire body coefficient is 1.2 when the wire diameter is less than 17mm, and 1.1 when the wire diameter is ≥17mm;

[0070] g is the acceleration due to gravity, which is 9.80665 m / s 2 .

[0071] Step 4: Planarization of spatial points:

[0072] Through Pij, a parabola equation in space can be fitted, but the parabola equation in space is more complicated to analyze, so the data in Pij is converted into two-dimensional data, that is, the spatial point is flattened. The edge point on one side of the calculation span (that is, the side between the two selected towers and the wire range without insulator strings) is taken as the calculation origin O'. As the normal vector, calculate the plane equation π' passing through O', project Pij onto π', and get the coordinates of Pij on π'; for example, take a point in Pij, Find the parametric equation of the line passing through Pij for the direction vector, substitute the parametric equation into the plane equation, find the parameters that satisfy the plane equation π', substitute the parameters back into the parametric equation of the line in space, and you can find the coordinates of the projection point of Pij on π'. Project all Pij onto π' to get Pij'.

[0073] Then solve the relative position relationship between Pij' and O'. The specific solution method is as follows: First solve the basis vector in the π' plane This vector is perpendicular to both the π' plane normal vector and The vector can be calculated by cross-multiplying the two vectors and normalizing them (i.e. dividing the vector by its own modulus by vector π'× vector Z), and then by the π' plane normal vector and Cross product and unitize to get another basis vector in the π' plane Then connect Pij' and O' to get the vector O'Pij' (that is, the vector obtained by subtracting the coordinates of O' from the coordinates of Pij), then Take O' as the origin of the Cartesian coordinate plane, then x ij 、y ijPij' are the horizontal coordinate value and the vertical coordinate value of Pij in the plane Cartesian coordinate system. The projection plane coordinates of the space point are obtained after all Pij' are transformed in this way.

[0074] Step 5, calculate the wire diameter d:

[0075] According to step 4, a series of discrete points in the plane coordinates are obtained. Plot these points, select the maximum and minimum value points in the y-axis direction along the x-axis (the maximum and minimum values can be understood as the upper edge and lower edge of the conductor corresponding to the two maximum and minimum lines, and the distance between the two lines is the conductor diameter), and use the spline curve interpolation to obtain the approximate conductor projection edge line. The wire diameter is obtained by measuring the distance of the edge line at multiple points and taking the average. The wire type can be determined according to the wire diameter d calculated in step 5.

[0076] In order to further improve the accuracy of judgment, the following technical measures can be further taken:

[0077] Substitute the wire diameter d into equation (1) to obtain the relationship between the wind speed v at the average height of the wire and the unit load p1 of the wire. Then, the wire type is reviewed by the specific load (i.e. the load p1 per unit length and unit area) to improve the accuracy of analyzing and determining the wire type.

[0078] The specific method is as follows:

[0079] Step 6, fit the wire sag equation:

[0080] The wire sag equation is actually a catenary, which can also be approximately regarded as a parabola. Taking a parabola as an example, the least squares method is used to fit, and the process is as follows: assume that the sag equation satisfies y = a0 + a1x + a2x 2 , and the coordinate data (x ij , y ij ) after the plane of the space point is obtained by the fourth step, the matrix equation is obtained by the method of finding the extreme value:

[0081]

[0082] The coefficients a0, a1 and a2 are obtained from the matrix equation, that is, the wire sag equation is solved.

[0083] Step 7, calculate the specific load (specific load, i.e. load p1 per unit length and unit area) and stress (stress of the wire during survey) according to the fitted sag equation:

[0084] Take the middle value of the calculated span l and substitute it into the fitted equation y = a0 + a1x + a2x 2 , to obtain the maximum sag, that is:

[0085]

[0086] In the formula: l is the calculation span, m;

[0087] h is the height difference, i.e. the z-axis coordinate difference of the most edge points at both ends of the span is calculated;

[0088] β is the height difference angle,

[0089] γ is the comprehensive load ratio during measurement, N / (m·mm 2 );

[0090] σ0 is the horizontal stress at each point of the wire during measurement (i.e. the stress at the lowest point of sag), N / mm 2 ;

[0091] (3) In the formula, except for σ0 and γ, all other quantities are known. The proportional relationship between σ0 and γ can be obtained by formula (3);

[0092] Find the fitting equation y=a0+a1x+a2x 2 The derivative y′=tanθ=a1 at O', where θ is the inclination angle of point O':

[0093]

[0094] Substituting the proportional relationship between σ0 and γ obtained from equation (3) into equation (4) can solve for σ0 and γ respectively;

[0095] and

[0096] Where: A is the cross-sectional area of ​​the wire, which can be obtained from the wire diameter d;

[0097] In formula (5), there are only two unknown quantities: the wind speed ν at the average height and the unit load p1 of the power line. Combining the quantitative relationship between ν and p1 obtained in formula (1), using ν to represent p1 (elimination, that is, obtaining a one-variable equation containing P1, which makes it easy to solve for P1) and substituting it into formula (5), the wind speed ν at the average height of the power line and the unit load p1 of the power line can be obtained. Because there is a one-to-one correspondence between the power line model and its unit load p1, the power line unit load p1 can be used to verify the power line model initially determined by the wire diameter d, improving the accuracy of the judgment.

[0098] Based on the obtained wire model parameters, in order to ensure the structural safety and reliability of existing and new lines, and to avoid selecting towers with overly large design conditions to reduce project costs, the following design methods can be used:

[0099] Calculate the maximum service stress σ of the wire max :

[0100] According to the above-mentioned wire model and the horizontal stress σ0 at each point of the wire, combined with the design meteorological conditions and the temperature t recorded during measurement, the critical span is calculated, and then the maximum service stress σ of the wire is calculated according to the wire state equation. max, the calculation formula is as follows:

[0101]

[0102] Where: γ m , t m is the specific load and temperature of the state to be determined, γ,t is the specific load and temperature during measurement; E is the elastic modulus of the wire; α is the expansion coefficient of the wire;

[0103] By the maximum service stress σ max The maximum working tension T=σ can be obtained max ×A, select the appropriate tower according to T.

[0104] The above is the process flow of the present invention's method for determining wire type. This method combines high-precision radar laser point cloud data with wire diameter and mass per unit length to determine wire type, significantly improving accuracy and providing strong support for safe line operation.

[0105] In addition to the above embodiments, the present invention may also have other implementation methods. Any technical solutions formed by equivalent replacement or equivalent transformation fall within the protection scope required by the present invention.

Claims

1. A method for identifying the type of power transmission line wires based on laser point cloud data. The laser point cloud data of the transmission line is a collection of spatial points scanned by a laser radar, and the position information of the points is stored in the form of spatial coordinates (x, y, z); characterized in that: The method for identifying the type of power transmission line wires based on laser point cloud data includes the following steps: Step 1: Line measurement: Collect laser point cloud data of transmission lines; Step 2: Select the point cloud data for fitting the sag formula: The point cloud data used for calculation should be selected from points that do not contain tension strings in the section; and point cloud data within the range of three times the size of the clamp along the line direction should not be used; the set of all points that meet the above requirements is called {P}, and the projection length of the two farthest points in {P} in the horizontal plane is called the calculated section distance l; Select n groups of data in {P}, n ≥ 3; each group of data contains 3 points. To reduce the calculation error, the selection rules are as follows: (1) the 3 points in each group of data should be evenly distributed in the span; (2) the 3 points in each group of data should be selected in the same area of ​​the four cross-sections of the wire; Pij is used to represent the n groups of data, i represents the number of groups i = 1, 2, 3...n, j represents the number of points in each group j = 1, 2, 3; Step 3: Calculate the wind deflection angle ξ of the power line: Select the i-th group of data in Pij, then the normal vector of the plane where Pi1, Pi2, and Pi3 are located is for: Calculating n sets of data separately can get n plane normal vectors. Taking the average of the coordinate components of the n plane normal vectors, we can get the normal vector of the wire in the windage plane, which is recorded as calculate and Angle ξ is the wind deflection angle of the power line. If the calculated angle is an obtuse angle, the complementary angle is taken as the wind deflection angle ξ. In a physical sense, this angle reflects the ratio of the vertical load to the horizontal load on the power line. ξ is expressed as: Where: ξ is the wind angle; p1 is the unit load of the wire, kg / m; d is the wire diameter, mm; ν is the wind speed at the average height of the power line, m / s; α is the wind pressure unevenness coefficient, which is taken as 1.0 according to the measurement environment; μ δc The wire body coefficient is 1.2 when the wire diameter is less than 17mm, and 1.1 when the wire diameter is ≥17mm; g is the acceleration due to gravity, which is 9.80665 m / s 2 ; Step 4: Planarization of spatial points: Through Pij, a parabola equation in space is fitted, and then the data in Pij is converted into two-dimensional data, that is, the spatial point is flattened; the edge point on the side of the calculated span is taken as the calculation origin O'. is the normal vector, calculate the plane equation π' passing through O', project Pij onto π', and get the coordinates of Pij on π'; Then solve the relative position relationship between Pij' and O'. The specific solution method is as follows: First solve the basis vector in the π' plane This vector is perpendicular to both the π' plane normal vector and The vector is obtained by cross-producting the two vectors and normalizing them to the standard. Then the normal vector of the π' plane is obtained by Cross product and unitize to get another basis vector in the π' plane Then connect Pij' and O' to get the vector O'Pij', which is the vector obtained by subtracting the coordinates of O' from the coordinates of Pij. Take O' as the origin of the Cartesian coordinate plane, then x ij 、y ij are the horizontal and vertical coordinate values ​​of Pij' in the Cartesian coordinate system respectively; after transforming all Pij', we can get the projected plane coordinates of the spatial point; Step 5: Calculate the wire diameter d: According to step 4, a series of discrete points in the plane coordinates are obtained, and these points are plotted. The maximum point in the y-axis direction is selected along the x-axis, and the approximate projection edge line of the wire is obtained by spline interpolation. The wire diameter is obtained by measuring the distance between multiple edge lines and taking the average value.

2. The method for identifying the type of power transmission line wires based on laser point cloud data according to claim 1, characterized in that: Substituting the wire diameter d into formula (1), we can obtain the relationship between the wind speed ν at the average height of the wire and the unit load p1 of the wire. Then, we can verify the wire model by comparing the loads to improve the accuracy of the analysis and judgment of the wire type. The specific method is as follows: Step 6: Fitting the wire sag equation: The sag equation of the wire is actually a catenary, and the least squares method is used for fitting. The process is as follows: Assume that the sag equation satisfies y=a0+a1x+a2x 2 , through the fourth step of spatial point plane coordinate data (x ij ,y ij ), and the matrix equation is obtained by the method of finding the extreme value: By finding the coefficients a0, a1, and a2 from the matrix equation, we can solve the wire sag equation; Step 7. Calculate the specific load and stress based on the fitted sag equation. The specific load is the load per unit length and unit area of ​​the wire, p1, and the stress is the stress of the wire during the survey: Take the middle value of the calculated gear spacing l and substitute it into the fitting equation y=a0+a1x+a2x 2 , we can get the maximum sag, that is: Where: l is the calculated gear spacing, m; h is the height difference, i.e. the z-axis coordinate difference of the most edge points at both ends of the span is calculated; β is the height difference angle, γ is the comprehensive load ratio during measurement, N / (m·mm 2 ); σ0 is the horizontal stress at each point of the wire during measurement, that is, the stress at the lowest point of sag, N / mm 2 ; (3) In formula (3), except for σ0 and γ, all other quantities are known. The proportional relationship between σ0 and γ can be obtained by formula (3); Find the fitting equation y=a0+a1x+a2x 2 The derivative at O' is y' = tanθ = a1, where θ is the inclination angle of point O': Substituting the proportional relationship between σ0 and γ obtained from equation (3) into equation (4) can solve for σ0 and γ respectively; Where: A is the cross-sectional area of ​​the wire, which can be obtained from the wire diameter d; In formula (5), there are only two unknown quantities: the wind speed ν at the average height and the unit load p1 of the power line. Combining the quantitative relationship between ν and p1 obtained in formula (1), using ν to represent p1 and substituting it into formula (5), the wind speed ν at the average height of the power line and the unit load p1 of the power line can be obtained. Since there is a one-to-one correspondence between the wire model and its unit load p1, the wire model derived from the wire diameter d can be verified by the wire unit load p1, thereby improving the accuracy of the judgment.

Images