Transmission conductor icing monitoring method, system and equipment based on SAR satellite remote sensing

Abstract

The invention discloses a transmission conductor icing monitoring method, system and equipment based on SAR satellite remote sensing, and the method comprises the steps: firstly obtaining an SAR image and geometric parameters, analyzing a three-dimensional point cloud to determine transmission conductor parameters and a stress model, then calculating a theoretical sag value through employing the environment temperature and the model, and simulating an actual sag value through combining with the deviation of an SAR coordinate system and a radar coordinate system, thereby achieving the icing monitoring of a transmission conductor. And finally, comparing the theoretical sag value with the actual sag value so as to evaluate the icing weight and thickness. According to the method, an accurate transmission conductor imaging equation is established for long-arc-segment texture features generated by a transmission conductor in a high-resolution SAR satellite image, and the three-dimensional state of the transmission conductor is inverted; meanwhile, a theoretical calculation model is established according to actual materials, environment temperature and the like, information of icing weight and equivalent thickness is obtained through comparative analysis of an SAR satellite actual measurement result and the theoretical calculation model, and therefore the state of the power transmission conductor is effectively evaluated, and the reliability of the power transmission conductor is improved. And the monitoring efficiency and accuracy of icing of the power transmission conductor in a large range and in a complex terrain are greatly improved.

Description

Technical Field

[0001] The invention relates to a means for monitoring ice coating on a power transmission line, belongs to the field of remote sensing applications of power transmission lines, and in particular to a method, system and equipment for monitoring ice coating on a power transmission line based on SAR satellite remote sensing. Background Art

[0002] The problem of ice on transmission lines often occurs in China in winter, especially in mountainous areas that are responsible for key power transmission work. Under specific meteorological conditions in winter and spring, transmission lines are covered with ice due to low temperature, freezing rain and micro-meteorological environment. Ice increases the weight of the wires and increases the sag. In severe cases, it causes damage such as wire breakage. Due to the complex terrain in mountainous areas, traditional means of monitoring ice on transmission lines, such as ground sensor observations and local meteorological data, have limited monitoring range and lack of real-time performance, and are difficult to meet the continuous monitoring needs of large-scale transmission lines. Therefore, how to effectively monitor and evaluate the ice coverage of transmission lines has become the key to ensuring the safe operation of the power grid.

[0003] The technology based on synthetic aperture radar (SAR) images provides a new monitoring method for ice coating on power transmission lines due to its all-weather characteristics. However, SAR images are two-dimensional information, and the curve formed by the wire in the SAR image lacks an effective mathematical model to explain the relationship between its three-dimensional position. Existing SAR methods mainly rely on scattered bright spots (scattering spots) in the image to directly evaluate the sag value of the transmission line, but in SAR images, there is no direct correlation between the imaging position of the transmission line scattering spots and the lowest point of the sag. Although current research can capture the changes in the scattering spots of transmission lines in SAR images, this change is reflected in the changes in azimuth and range as well as the changes in the scattering intensity value.

[0004] In the patent application document with application number CN201711483192.6 and application date of December 29, 2017, a judgment method for establishing the sag change value of the transmission line for the scattering spots of the transmission line is disclosed. However, the imaging position of the scattering spots of the transmission line on the SAR image is related to the satellite imaging parameters and does not directly correspond to the lowest point of the sag. Therefore, the change of the scattering spot position cannot accurately describe the three-dimensional geometric shape of the transmission line, so that the relationship between the scattering spots of the transmission line and the overall transmission line shape cannot be established, and the sag change caused by ice cannot be accurately detected. With the improvement of the resolution of SAR satellites, SAR satellites can observe the texture features of transmission lines in longer arc segments, or even the entire transmission line. Therefore, it is urgent to propose a method with higher accuracy for such scattering lines of the transmission line in high-resolution radar images to solve the above-mentioned defects in the prior art. Summary of the invention

[0005] The purpose of the present invention is to overcome the above-mentioned defects and problems existing in the prior art and to provide a method, system and equipment for monitoring ice coating on power transmission lines based on SAR satellite remote sensing with high accuracy.

[0006] To achieve the above objectives, the technical solution of the present invention is: a transmission line ice coverage monitoring method based on SAR satellite remote sensing, comprising:

[0007] S1. Obtain SAR satellite images of the transmission line area and its geometric positioning parameters;

[0008] S2. Acquire the three-dimensional point cloud data of the transmission line in the geographic coordinate system, and construct a theoretical model of the transmission line sag under the influence of different temperatures and different stresses according to the product type of the transmission line and the stress parameters when it is mounted;

[0009] S3, based on the theoretical model of the change of transmission line sag caused by the ambient temperature during the shooting of the SAR satellite image of the transmission line area, calculate the theoretical sag value of the transmission line sag affected by temperature;

[0010] S4, based on the coordinate value of the transmission line in the SAR coordinate system, obtain the scattered line imaging position of the transmission line in the SAR satellite image, and obtain the distance deviation function of the transmission line point cloud in the radar coordinate system and the SAR coordinate system;

[0011] S5. Based on the distance deviation function, simulate the expression of the transmission line in the sag coordinate system, and calculate the sag value of the transmission line at the time of satellite image shooting;

[0012] S6. Compare the theoretical sag value of the transmission line with the sag value observed by satellite, determine the change in sag after the transmission line is covered with ice, and calculate the weight and thickness of the ice covering the transmission line based on the transmission line stress model.

[0013] The step S1 specifically includes:

[0014] S11, obtaining the imaging parameters of the SAR satellite image and the actual measured coordinates of the ground control points; the imaging parameters include the azimuth resolution δ a , range resolution δ r , radar satellite frequency, perigee distance, local incidence angle η, and satellite orbit data;

[0015] S12. Based on the imaging parameters of the SAR satellite image and the range Doppler model, determine the geometric positioning coordinates of the actual measured coordinates of the ground control point in the radar coordinate system;

[0016] S13, based on the geometric positioning coordinates of the actual measured coordinates of the ground control point in the radar coordinate system and the positioning deviation value of the coordinates of the center point of the radar scattering imaging of the ground control point, correct the geometric positioning of the SAR satellite image of the transmission line area;

[0017] The coordinates of the center point of the ground control point in the radar scattering imaging are: the coordinates of the extreme point of the scattering intensity within the preset range of the ground control point target.

[0018] The step S2 specifically includes:

[0019] S21. Obtain the transmission line spacing L at temperature t0 d , unit weight ω, diameter d, and tension T0 are used to construct the catenary sag equation; the expression of the catenary sag equation is as follows:

[0020]

[0021] S22. Based on the LiDAR point cloud data of the transmission line at temperature t1, obtain the three-dimensional point cloud of the transmission line; take the lowest point of the three-dimensional point cloud of the transmission line as the origin, reconstruct the local two-dimensional Cartesian coordinate system, fit the catenary sag equation for the coordinate values ​​of each point of the transmission line in the two-dimensional coordinate system, and obtain the initial line length L of the transmission line c And the measured sag value L of the transmission line at temperature t1 c ;

[0022] S23, obtaining the thermal expansion coefficient α of the transmission line and the tension T1 of the transmission line at temperature t1, and calculating the total length L′ of the thermally expanded line at temperature t1 compared with that at temperature t0 in the design condition. c ;

[0023] The total length of the thermal expansion wire is L' c The expression is as follows:

[0024] L′ c =L c (1+α(t1-t0));

[0025] S24. Calculate the design sag value f of the transmission line at temperature t1 based on the catenary sag equation d , and compare the design sag value f of the transmission line at temperature t1 d Compared with the measured sag value f c The difference between

[0026] If the difference between the two satisfies |f d -f c |≤0.05·f d, the parameters of the transmission line meet the requirements, and the transmission line sag theoretical model is constructed based on these parameters;

[0027] If the difference between the two does not satisfy |f d -f c |≤0.05·f d , other influencing factors need to be considered.

[0028] The other influencing factors include wind load influence, and the specific steps are as follows:

[0029] S25, substituting the wind load into the catenary sag equation, and repeating steps S21-S24; the catenary sag equation considering the wind load is expressed as follows:

[0030]

[0031] The expression of wind load is as follows:

[0032]

[0033] Where: C d is the damping coefficient, ρ is the air density, A is the windward area, and v is the wind speed.

[0034] The step S3 specifically includes:

[0035] S31, obtaining the temperature t2 at the time of taking the SAR satellite image, and adjusting the sag state parameters of the transmission line based on the temperature t2;

[0036] The adjustment method is: calculate the total length L' of the transmission line in the design working condition at the temperature t2 s , and obtain the tension T2 of the transmission line in the design condition at temperature t2;

[0037] The total length of the transmission line L' s The calculation formula is as follows:

[0038] L′ s =L c (1+α(t2-t0));

[0039] S32, based on the adjusted total length L' of the transmission line s With the transmission line sag theoretical model, calculate the theoretical sag value of the transmission line at the time of shooting;

[0040] The expression of the theoretical sag value is as follows:

[0041]

[0042] Where: f sis the theoretical sag value of the transmission line at temperature t2.

[0043] The step S4 specifically includes:

[0044] S41, select the geographic coordinate values ​​of the two tower foot points in the transmission line LiDAR point cloud, which are expressed as (B1, L1, H) and (B2, L2, H), respectively; where H needs to be kept on an ellipsoid; solve the range Doppler equation for the geographic coordinate values ​​to obtain the coordinate values ​​(i1, j1) and (i2, j2) in the SAR coordinate system;

[0045] S42, performing window clipping on the coordinate area based on the coordinate values ​​(i1, j1) and (i2, j2); wherein the window is not smaller than the pixel of {|i1-i2|+5}*{|j1-j2|+5};

[0046] S43, calculate the scattering intensity value of the SAR satellite image for the clipped window, and calculate the intensity value In=I in the coordinate area 2 +Q 2 ; After normalizing and counting the intensity values, the histogram In under the window is obtained dB =10·log 10 (In);

[0047] S44, based on the histogram In under the window dB , get the background scattering average intensity value RCS b And the average scattering intensity map RCS of the transmission line l , and the histogram In under the window dB Filtering is performed; the threshold of the filtering is RCS b +ΔRCS;

[0048] S45, average scattering intensity diagram of transmission lines RCS l The scattering characteristics are used to define the scattered lines; the scattering characteristics are

[0049] S46, extract the scattering features defined as scattered lines at the pixel level to obtain the position coordinate point set [ij] of each point constituting the scattered line imaging of the transmission line n ;

[0050] S47, for each point's position coordinate point set [ij] n Perform fitting to obtain the expression f(a) of the transmission line in the radar coordinate system;

[0051] In the expression f(a) of the transmission line, when the expression f(a) function defining the transmission line i in the radar coordinate system is a quadratic polynomial function, a is the azimuth coordinate of any point on the line in the radar coordinate system, and f(a) is the range coordinate of any point a on the transmission line i in the radar coordinate system;

[0052] S48. Connect the two points (i1, j1) and (i2, j2) in the SAR coordinate system to obtain a straight line equation g(a); the straight line equation is expressed as follows:

[0053] g(a)=k*a+b;

[0054] k = (j2-j1) / (i2-i1);

[0055] b = j2-(j2-j1) / (i2-i1)*i1;

[0056] Where: k is the coefficient of the linear term of the linear equation; a is the range coordinate value of any point in the SAR coordinate system; b is a constant;

[0057] S49. Obtain a range deviation function between g(a) and f(a) in the SAR coordinate system; the range deviation function is expressed as follows:

[0058] p(a)=|g(a)-f(a)|*δ r / cosη;

[0059] Where: p(a) is the range deviation function.

[0060] The step S5 specifically includes:

[0061] S51, taking the azimuth direction n as the step length, a = min (i1, i2) + n, and bringing it into the range deviation function to calculate and obtain the three-dimensional point set of the transmission line radar scattering imaging [ijh] n , where h = p(a) + H;

[0062] S52. Based on the ellipsoid equation and the range Doppler equation, the three-dimensional point set of radar scattering imaging of transmission lines in the SAR coordinate system [ijh] n Transform to obtain the point set of the transmission line in the geographic coordinate system [B l L l H l ] n ;

[0063] S53, the point set in the geographic coordinate system of the transmission line [B l L l H l ] nConvert to the spatial rectangular coordinate system and obtain [X l Y l Z l ] n ;

[0064] S54. Use the plane formed by the two ends of the transmission line and the plumb line as the projection plane to establish a sag coordinate system, with [X l Y l Z l ] n The lowest point in the point cloud is taken as the origin, and the point cloud coordinates are converted to obtain the point set of the transmission line in the sag coordinate system [M l N l ] n ;

[0065] M l =(X i -X0) / cosβ;

[0066] N l =Z i -Z0;

[0067] Where: M l is the M-axis coordinate value of any point i on the transmission line in the sag coordinate system, N l is the N-axis coordinate value of any point i on the transmission line in the sag coordinate system, X i is the X-axis coordinate value of any point i of the transmission line in the spatial rectangular coordinate system, X0 is the X-axis coordinate value corresponding to the origin of the transmission line in the spatial rectangular coordinate system, Z i is the Z-axis coordinate value of any point i of the transmission line in the spatial rectangular coordinate system, Z0 is the Z-axis coordinate value corresponding to the origin of the transmission line in the spatial rectangular coordinate system, β is the angle between the lines connecting the transmission lines in the XOY plane, X A , Y A With X B , Y B is the coordinate value of the rectangular coordinate system of the mounting points at both ends of the transmission line;

[0068] S55. Set the expression g of the transmission line in the sag coordinate system l (m) is a quadratic polynomial function, and based on [M l N l ] n Fitting polynomial coefficients a1, a2, a3;

[0069] The expression g of the transmission line in the sag coordinate system is l (m) are as follows:

[0070] g l(m) = a1*m*+a2*m+a3;

[0071] Where: m is the M-axis coordinate value of any point on the transmission line in the sag coordinate system;

[0072] S56. Obtain the coordinates of the mounting points at both ends of the transmission line in the sag coordinate system k l (m); the expression of the sag coordinate system is as follows:

[0073]

[0074] Where: n B is the coordinate value of the mounting point B on the N axis in the sag coordinate system, n A is the coordinate value of the mounting point A on the N axis in the sag coordinate system, m B is the coordinate value of the mounting point B on the M axis in the sag coordinate system, m A is the coordinate value of the M axis of the mounting point A in the sag coordinate system;

[0075] Then the sag expression of any point in the sag coordinate system is hc(m)=k l (m)-g l (m);

[0076] When m = 0, the minimum sag value of the transmission line at the time of SAR satellite image shooting is calculated.

[0077] When hc′ (m) = 0, the maximum sag value of the transmission line at the time of SAR satellite image shooting is calculated

[0078] The step S6 specifically includes:

[0079] S61. Calculate the theoretical sag value f s and minimum sag value The difference Obtain the sag change Δf of the transmission line ice ;

[0080] S62, based on the sag change Δf ice , calculate the ice thickness t of the transmission line i ; The expression of the ice layer thickness is as follows:

[0081]

[0082] Where: T is the initial stress, L d is the gear spacing, ρ i is the density of ice, d is the diameter;

[0083] S63, based on ice thickness ti Calculate the ice weight of the transmission line m ice =πdt i ρ i , and according to the deadweight ω of the transmission line and the ice weight m ice , calculate and obtain the unit weight of the transmission line after ice coating;

[0084] ω′=ω+m ice ;

[0085] S64, based on the unit weight ω′ and minimum sag value of the transmission line after ice coating Calculating Stresses in Transmission Lines

[0086] S65, comparing the stress T' of the transmission line with the initial stress T; if T and T' are inconsistent, T' is used as the initial stress, and steps S52-S55 are repeated until T and T' are consistent, and then step S66 is performed;

[0087] S66, according to the ice thickness t of the transmission line i , estimate the ice weight of the transmission line m ice ;

[0088] S67, the ice weight of the transmission line m ice , ice thickness t i Compare with the design threshold of the transmission conductor;

[0089] If the ice weight m ice , ice thickness t i If the ice weight m is within the design threshold, it indicates that the state of the transmission line and the tower is relatively stable. ice , ice thickness t i If it is outside the design threshold, it indicates that there is a large deformation of the transmission lines and towers and maintenance is required.

[0090] A transmission line ice coverage monitoring system based on SAR satellite remote sensing, the system is applied to the above method, the system comprises:

[0091] Image positioning acquisition module 1, used to obtain SAR satellite images of the transmission line area and its geometric positioning parameters;

[0092] The sag stress model building module 2 is used to obtain the three-dimensional point cloud data of the transmission line in the geographic coordinate system, and build a theoretical model of the transmission line sag under different temperature influences and different stresses according to the product type of the transmission line and the stress parameters when it is mounted;

[0093] Theoretical sag calculation module 3, used for calculating the theoretical sag value of the transmission line sag affected by temperature based on the theoretical model of the change of the transmission line sag caused by the ambient temperature during the shooting of the SAR satellite image of the transmission line area;

[0094] The actual sag calculation module 4 is used to obtain the scattered ray imaging position of the transmission line in the SAR satellite image based on the coordinate value of the transmission line in the SAR coordinate system, and obtain the range deviation function of the transmission line point cloud in the radar coordinate system and the SAR coordinate system; based on the range deviation function, simulate the expression of the transmission line in the sag coordinate system, and calculate the sag value of the transmission line at the time of satellite image shooting;

[0095] The icing status assessment module 5 is used to compare the theoretical sag value of the transmission line with the sag value observed by satellite, determine the sag change of the transmission line after icing, and calculate the weight and thickness of the ice on the transmission line according to the transmission line stress model.

[0096] A transmission line ice-covering monitoring device based on SAR satellite remote sensing, the device comprising a processor and a memory;

[0097] The memory is used to store computer program code and transmit the computer program code to the processor;

[0098] The processor is used to execute the above-mentioned transmission line ice coverage monitoring method based on SAR satellite remote sensing according to the instructions in the computer program code.

[0099] Compared with the prior art, the present invention has the following beneficial effects:

[0100] In a transmission line ice monitoring method, system and device based on SAR satellite remote sensing of the present invention, the method first obtains SAR images and geometric parameters, analyzes three-dimensional point clouds to determine transmission line parameters and stress models, then uses ambient temperature and models to calculate theoretical sag values, combines SAR coordinate system and radar coordinate system deviations to simulate actual sag values, and finally compares theoretical and actual sag values ​​to evaluate ice weight and thickness; in the application of the design, a more accurate transmission line imaging equation is established for the long arc segment texture features generated by the transmission line in high-resolution (1m resolution) SAR satellite images, and the three-dimensional state of the transmission line is inverted; at the same time, a theoretical calculation model of the conductor sag is established according to the actual material model, ambient temperature and conductor construction prestress of the transmission line, and the information of ice weight and equivalent thickness of the transmission line is obtained through comparative analysis of SAR satellite actual measurement results and theoretical calculation models; thereby the state of the transmission line is effectively evaluated, and the monitoring efficiency and accuracy of ice coverage of the transmission line in a large range and complex terrain are greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0101] Figure 1 It is a flow chart of the method steps of the present invention.

[0102] Figure 2 It is a schematic diagram of the three-dimensional state of a transmission line in a certain area in Example 1 of the present invention.

[0103] Figure 3 It is a schematic diagram of the theoretical three-dimensional state of the transmission line in Example 1 of the present invention.

[0104] Figure 4 It is a schematic diagram of the scattered-ray imaging display of the transmission line in Example 1 of the present invention on the SAR satellite image.

[0105] Figure 5 It is a schematic diagram of the sag change of the transmission line in Example 1 of the present invention.

[0106] Figure 6 It is a schematic diagram of the system structure of the present invention.

[0107] Figure 7 It is a schematic diagram of the device structure of the present invention.

[0108] In the figure: image positioning acquisition module 1, sag stress model construction module 2, theoretical sag calculation module 3, actual sag calculation module 4, ice cover state assessment module 5, processor 6, memory 7, computer program code 71. DETAILED DESCRIPTION

[0109] The present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0110] Embodiment 1:

[0111] See also Figure 1 A method for monitoring ice coating on power transmission lines based on SAR satellite remote sensing, comprising:

[0112] S1. Obtain SAR satellite images of the transmission line area and its geometric positioning parameters;

[0113] Furthermore, the step S1 specifically includes:

[0114] S11, obtaining the imaging parameters of the SAR satellite image and the actual measured coordinates of the ground control points; the imaging parameters include the azimuth resolution δ a , range resolution δ r , radar satellite frequency, perigee distance, local incidence angle η, and satellite orbit data;

[0115] S12. Based on the imaging parameters of the SAR satellite image and the range Doppler model, determine the geometric positioning coordinates of the actual measured coordinates of the ground control point in the radar coordinate system;

[0116] S13, based on the geometric positioning coordinates of the actual measured coordinates of the ground control point in the radar coordinate system and the positioning deviation value of the coordinates of the center point of the radar scattering imaging of the ground control point, correct the geometric positioning of the SAR satellite image of the transmission line area;

[0117] The coordinates of the center point of the ground control point in the radar scattering imaging are: the coordinates of the extreme point of the scattering intensity within the preset range of the ground control point target.

[0118] S2. Acquire the three-dimensional point cloud data of the transmission line in the geographic coordinate system, and construct a theoretical model of the transmission line sag under the influence of different temperatures and different stresses according to the product type of the transmission line and the stress parameters when it is mounted;

[0119] Furthermore, the step S2 specifically includes:

[0120] S21. Obtain the transmission line spacing L at temperature t0 d , unit weight ω, diameter d, and tension T0 are used to construct the catenary sag equation; the expression of the catenary sag equation is as follows:

[0121]

[0122] S22. Based on the LiDAR point cloud data of the transmission line at temperature t1, obtain the three-dimensional point cloud of the transmission line; take the lowest point of the three-dimensional point cloud of the transmission line as the origin, reconstruct the local two-dimensional Cartesian coordinate system, fit the catenary sag equation for the coordinate values ​​of each point of the transmission line in the two-dimensional coordinate system, and obtain the initial line length L of the transmission line c And the measured sag value f of the transmission line at temperature t1 c ;

[0123] S23, obtaining the thermal expansion coefficient α of the transmission line and the tension T1 of the transmission line at temperature t1, and calculating the total length L′ of the thermally expanded line at temperature t1 compared with that at temperature t0 in the design condition. c ;

[0124] The total length of the thermal expansion wire is L' c The expression is as follows:

[0125] L′ c =L c (1+α(t1-t0));

[0126] S24. Calculate the design sag value f of the transmission line at temperature t1 based on the catenary sag equation d , and compare the design sag value f of the transmission line at temperature t1 d Compared with the measured sag value f cThe difference between

[0127] If the difference between the two satisfies |f d -f c |≤0.05·f d , the parameters of the transmission line meet the requirements, and the transmission line sag stress model is constructed based on these parameters;

[0128] If the difference between the two does not satisfy |f d -f c |≤0.05·f d , other influencing factors need to be considered.

[0129] Further, the other influencing factors include wind load influence, and the specific steps are as follows:

[0130] S25, substituting the wind load into the catenary sag equation, and repeating steps S21-S24; the catenary sag equation considering the wind load is expressed as follows:

[0131]

[0132] The expression of wind load is as follows:

[0133]

[0134] Where: C d is the damping coefficient, ρ is the air density, A is the windward area, and v is the wind speed.

[0135] S3, based on the theoretical model of the change of transmission line sag caused by the ambient temperature during the shooting of the SAR satellite image of the transmission line area, calculate the theoretical sag value of the transmission line sag affected by temperature;

[0136] Furthermore, the step S3 specifically includes:

[0137] S31, obtaining the temperature t2 at the time of taking the SAR satellite image, and adjusting the sag state parameters of the transmission line based on the temperature t2;

[0138] The adjustment method is: calculate the total length L' of the transmission line in the design working condition at the temperature t2 s , and obtain the tension T2 of the transmission line in the design working condition at temperature t2; the tension T2 can be obtained by referring to the relevant design specifications of the transmission line.

[0139] The total length of the transmission line L' s The calculation formula is as follows:

[0140] L' s =L c (1+α(t2-t0));

[0141] S32, based on the adjusted total length L' of the transmission line s With the transmission line sag theoretical model, calculate the theoretical sag value of the transmission line at the time of shooting;

[0142] The expression of the theoretical sag value is as follows:

[0143]

[0144] Where: f s is the theoretical sag value of the transmission line at temperature t2.

[0145] S4, based on the coordinate value of the transmission line in the SAR coordinate system, obtain the scattered line imaging position of the transmission line in the SAR satellite image, and obtain the distance deviation function of the transmission line point cloud in the radar coordinate system and the SAR coordinate system;

[0146] Furthermore, the step S4 specifically includes:

[0147] S41, select the geographic coordinate values ​​of the two tower foot points in the transmission line LiDAR point cloud, which are expressed as ((B1, L1, H) and (B2, L2, H), respectively; where H needs to be kept on an ellipsoid; solve the range Doppler equation for the geographic coordinate values ​​to obtain the coordinate values ​​(i1, j1) and (i2, j2) in the SAR coordinate system;

[0148] S42, performing window clipping on the coordinate area based on the coordinate values ​​(i1, j1) and (i2, j2); wherein the window is not smaller than the pixel of {|i1-i2|+5}*{|j1-j2|+5};

[0149] S43, calculate the scattering intensity value of the SAR satellite image for the clipped window, and calculate the intensity value In=I in the coordinate area 2 +Q 2 ; After normalizing and counting the intensity values, the histogram In under the window is obtained dB =10·log 10 (In);

[0150] S44, based on the histogram In under the window dB , get the background scattering average intensity value RCS b And the average scattering intensity map RCS of the transmission line l , and the histogram In under the window dB Filtering is performed; the threshold of the filtering is RCS b +ΔRCS; ΔPCS should be determined in combination with the current SAR image noise. In principle, ΔRCS should be less than (RCS l -RCSb +3).

[0151] S45, average scattering intensity diagram of transmission lines RCS l The scattering characteristics are used to define the scattered lines; the scattering characteristics are Said The number of continuous lines in the azimuth direction needs to be greater than 1 / 8 of the total number of the two towers.

[0152] S46, extract the scattering features defined as scattered lines at the pixel level to obtain the position coordinate point set [ij] of each point constituting the scattered line imaging of the transmission line n ;

[0153] S47, for each point's position coordinate point set [ij] n Perform fitting to obtain the expression f(a) of the transmission line in the radar coordinate system;

[0154] In the expression f(a) of the transmission line, when the expression f(a) function defining the transmission line i in the radar coordinate system is a quadratic polynomial function, a is the azimuth coordinate of any point on the line in the radar coordinate system, and f(a) is the range coordinate of any point a on the transmission line i in the radar coordinate system;

[0155] S48. Connect the two points (i1, j1) and (i2, j2) in the SAR coordinate system to obtain a straight line equation g(a); the straight line equation is expressed as follows:

[0156] g(a)=k*a+b;

[0157] k = (j2-j1) / (i2-i1);

[0158] b = j2-(j2-j1) / (i2-i1)*i1;

[0159] Where: k is the coefficient of the linear term of the linear equation; a is the range coordinate value of any point in the SAR coordinate system; b is a constant;

[0160] S49. Obtain a range deviation function between g(a) and f(a) in the SAR coordinate system; the range deviation function is expressed as follows:

[0161] p(a)=|g(a)-f(a)|*δ r / cosη;

[0162] Where: p(a) is the range deviation function.

[0163] S5. Based on the distance deviation function, simulate the expression of the transmission line in the sag coordinate system and calculate the actual sag value of the transmission line;

[0164] Furthermore, the step S5 specifically includes:

[0165] S51, taking the azimuth direction n as the step length, a = min (i1, i2) + n, and bringing it into the range deviation function to calculate and obtain the three-dimensional point set of the transmission line radar scattering imaging [ijh] n , where h = p(a) + H; where a is within the range of i1 and i2, and where n needs to consider the resolution of the satellite. In the SAR satellite azimuth resolution δ a When it is greater than 3m, n should not be greater than 3.

[0166] S52. Based on the ellipsoid equation and the range Doppler equation, the three-dimensional point set of radar scattering imaging of transmission lines in the SAR coordinate system [ijh] n Transform to obtain the point set of the transmission line in the geographic coordinate system [B l L l H l ] n ;

[0167] S53, the point set in the geographic coordinate system of the transmission line [B l L l H l ] n Convert to the spatial rectangular coordinate system and obtain [X l Y l Z l ] n ;

[0168] S54. Use the plane formed by the two ends of the transmission line and the plumb line as the projection plane to establish a sag coordinate system, with [X l Y l Z l ] n The lowest point in the point cloud is taken as the origin, and the point cloud coordinates are converted to obtain the point set of the transmission line in the sag coordinate system [M l N l ] n ;

[0169] M l =(X i -X0) / cosβ;

[0170] Z l =Z i -Z0;

[0171] Where: M l is the M-axis coordinate value of any point i on the transmission line in the sag coordinate system, N l is the N-axis coordinate value of any point i on the transmission line in the sag coordinate system, X iis the X-axis coordinate value of any point i of the transmission line in the spatial rectangular coordinate system, X0 is the X-axis coordinate value corresponding to the origin of the transmission line in the spatial rectangular coordinate system, Z i is the Z-axis coordinate value of any point i of the transmission line in the spatial rectangular coordinate system, Z0 is the Z-axis coordinate value corresponding to the origin of the transmission line in the spatial rectangular coordinate system, β is the angle between the lines connecting the transmission lines in the XOY plane, X A , Y A With X B , Y B is the coordinate value of the rectangular coordinate system of the mounting points at both ends of the transmission line;

[0172] S55. Set the expression g of the transmission line in the sag coordinate system l (m) is a quadratic polynomial function, and based on [M l N l ] n Fitting polynomial coefficients a1, a2, a3;

[0173] The expression g of the transmission line in the sag coordinate system is l (m) are as follows:

[0174] g l (m) = a1*m*m+a2*m+a3;

[0175] Where: m is the m-axis coordinate value of any point on the transmission line in the sag coordinate system;

[0176] S56. Obtain the coordinates of the mounting points at both ends of the transmission line in the sag coordinate system k l (m); the expression of the sag coordinate system is as follows:

[0177]

[0178] Where: n B is the coordinate value of the mounting point B on the n-axis in the sag coordinate system, n A is the coordinate value of the mounting point A on the n-axis in the sag coordinate system, m B is the coordinate value of the mounting point B on the m-axis in the sag coordinate system, m A is the coordinate value of the m-axis of the mounting point A in the sag coordinate system;

[0179] Then the sag expression of any point in the sag coordinate system is hc(m)=k l (m)-g l (m);

[0180] When m = 0, the minimum sag value of the transmission line at the time of SAR satellite image shooting is calculated.

[0181] When h c ' (m) = 0, the maximum sag value of the transmission line at the time of SAR satellite image shooting is calculated

[0182] S6. Compare the theoretical sag value of the transmission line with the actual sag value, determine the sag change of the transmission line covered with ice, calculate the weight and thickness of the ice covering the transmission line, and evaluate the ice covering status of the transmission line and the stability of the tower.

[0183] Furthermore, the step S6 specifically includes:

[0184] S61. Calculate the theoretical sag value f s and minimum sag value The difference Obtain the sag change Δf of the transmission line ice ;

[0185] S62, based on the sag change Δf ice , calculate the ice thickness t of the transmission line i ; The expression of the ice layer thickness is as follows:

[0186]

[0187] Where: T is the initial stress, L d is the gear spacing, ρ i is the density of ice, d is the diameter;

[0188] S63, based on ice thickness t i Calculate the ice weight of the transmission line m ice =πdt i ρ i , and according to the deadweight ω of the transmission line and the ice weight m ice , calculate and obtain the unit weight of the transmission line after ice coating;

[0189] ω′=ω+m ice ;

[0190] S64, based on the unit weight ω′ and minimum sag value of the transmission line after ice coating Calculating Stresses in Transmission Lines

[0191] S65, comparing the stress T' of the transmission line with the initial stress T; if T and T' are inconsistent, T' is used as the initial stress, and steps S52-S55 are repeated until T and T' are consistent, and then step S66 is performed;

[0192] S66, according to the ice thickness t of the transmission line i, estimate the ice weight of the transmission line m ice ;

[0193] S67, the ice weight of the transmission line m ice , ice thickness t i Compare with the design threshold of the transmission conductor;

[0194] If the ice weight m ice , ice thickness t i If the ice weight m is within the design threshold, it indicates that the state of the transmission line and the tower is relatively stable. ice , ice thickness t i Outside the design threshold, it indicates that there is a large deformation of the transmission line and the tower, and maintenance is required, such as de-icing operations.

[0195] In this embodiment, according to a known three-dimensional point cloud of a certain transmission line area, there are 8 transmission lines in the area, and the two iron towers are a straight tower and a tension tower respectively;

[0196] Based on the fact that the type of a transmission line is 220kV, the stress parameters refer to the relevant document LGJ-240 / 30, and the insulator length is 2.3m, the initial state of the transmission line is obtained, such as Figure 2 shown; based on Figure 2 Assuming the initial state of the transmission line shown in the figure and the ambient temperature of the transmission line at the time of SAR satellite data shooting is 22℃, the initial sag of the transmission line at a certain place is calculated to be 8.55m; assuming that the ambient temperature at a certain time of ice coverage is -2℃, the theoretical sag value of the transmission line at a certain place is determined to be 5.72m by calculation, as shown in Figure 3 As shown; obtain the SAR image of the area at a certain ice-covering time, such as Figure 4 As shown, the ambient temperature is -2℃; by calculating the theoretical sag and actual sag through this scheme, it is found that the abnormal sag value caused by icing is 1.5m, as shown in Figure 5 As shown, the numerical values ​​in the figure represent the pixel numbers in the azimuth / range direction.

[0197] It should be noted that existing methods usually lack support for three-dimensional modeling of conductors. This solution uses the LiDAR point cloud data of transmission lines to establish a sag stress model for transmission lines, that is, there is a reference for the sag value of the transmission lines under normal working conditions, making the three-dimensional position estimation of transmission lines based on SAR images more accurate. This improvement improves the spatial accuracy of the monitoring results, and is particularly suitable for scenes with complex terrain and high precision requirements. Unlike traditional technologies that only use scattered bright spots in SAR images to represent conductors, this solution uses scattered rays to characterize the spatial state of transmission lines; by simulating and modeling the scattered rays of transmission lines, it can more accurately reflect the actual state of the entire transmission line under different environmental conditions, providing more reliable data support for sag change estimation. In the prior art, the sag point and the center point of the scattering spot are often considered to coincide, but in reality they are not the same. This solution is based on the combination of a three-dimensional model and SAR images. It not only clarifies the difference between the sag point and the scattering point, but also realizes the method of calculating the actual three-dimensional sag result of the transmission line from the two-dimensional imaging curve result of the transmission line in the SAR satellite image. In addition, by comparing the actual sag result of the line extracted by SAR with the theoretical sag change after the transmission line is covered with ice, the ice weight of the line can be further estimated and the ice thickness can be inverted. Therefore, this solution can accurately extract the actual sag change of the line, thereby improving the accuracy of ice detection, and solving the problem of how to use the characteristics of iced transmission lines monitored by SAR to accurately extract the ice status of the line.

[0198] Embodiment 2:

[0199] See also Figure 6 , a transmission line ice monitoring system based on SAR satellite remote sensing, the system is applied to the method described in Example 1, the system comprising:

[0200] Image positioning acquisition module 1, used to obtain SAR satellite images of the transmission line area and its geometric positioning parameters;

[0201] Furthermore, the image positioning acquisition module 1 acquires satellite images and parameters according to the following steps:

[0202] S11, obtaining the imaging parameters of the SAR satellite image and the actual measured coordinates of the ground control points; the imaging parameters include the azimuth resolution δ a , range resolution δ r , radar satellite frequency, perigee distance, local incidence angle η, and satellite orbit data;

[0203] S12. Based on the imaging parameters of the SAR satellite image and the range Doppler model, determine the geometric positioning coordinates of the actual measured coordinates of the ground control point in the radar coordinate system;

[0204] S13, based on the geometric positioning coordinates of the actual measured coordinates of the ground control point in the radar coordinate system and the positioning deviation value of the coordinates of the center point of the radar scattering imaging of the ground control point, correct the geometric positioning of the SAR satellite image of the transmission line area;

[0205] The coordinates of the center point of the ground control point in the radar scattering imaging are: the coordinates of the extreme point of the scattering intensity within the preset range of the ground control point target.

[0206] The sag stress model building module 2 is used to obtain the three-dimensional point cloud data of the transmission line in the geographic coordinate system, and build a theoretical model of the transmission line sag under different temperature influences and different stresses according to the product type of the transmission line and the stress parameters when it is mounted;

[0207] Furthermore, the sag stress model building module 2 builds a theoretical model of the transmission line sag according to the following steps:

[0208] S21. Obtain the transmission line spacing L at temperature t0 d , unit weight ω, diameter d, and tension T0 are used to construct the catenary sag equation; the expression of the catenary sag equation is as follows:

[0209]

[0210] S22. Based on the LiDAR point cloud data of the transmission line at temperature t1, obtain the three-dimensional point cloud of the transmission line; take the lowest point of the three-dimensional point cloud of the transmission line as the origin, reconstruct the local two-dimensional Cartesian coordinate system, fit the catenary sag equation for the coordinate values ​​of each point of the transmission line in the two-dimensional coordinate system, and obtain the initial line length L of the transmission line c And the measured sag value f of the transmission line at temperature t1 c ;

[0211] S23, obtaining the thermal expansion coefficient α of the transmission line and the tension T1 of the transmission line at temperature t1, and calculating the total length L′ of the thermally expanded line at temperature t1 compared with that at temperature t0 in the design condition. c ;

[0212] The total length of the thermal expansion wire is L' c The expression is as follows:

[0213] L′ c =L c (1+α(t1-t0));

[0214] S24. Calculate the design sag value f of the transmission line at temperature t1 based on the catenary sag equation d , and compare the design sag value f of the transmission line at temperature t1d Compared with the measured sag value f c The difference between

[0215] If the difference between the two satisfies |f d -f c |≤0.05·f d , the parameters of the transmission line meet the requirements, and the transmission line sag theoretical model is constructed based on these parameters;

[0216] If the difference between the two does not satisfy |f d -f c |≤0.05·f d , other influencing factors need to be considered.

[0217] The other influencing factors include wind load influence, and the specific steps are as follows:

[0218] S25, substituting the wind load into the catenary sag equation, and repeating steps S21-S24; the catenary sag equation considering the wind load is expressed as follows:

[0219]

[0220] The expression of wind load is as follows:

[0221]

[0222] Where: C d is the damping coefficient, ρ is the air density, A is the windward area, and v is the wind speed.

[0223] Theoretical sag calculation module 3, used for calculating the theoretical sag value of the transmission line sag affected by temperature based on the theoretical model of the change of the transmission line sag caused by the ambient temperature during the shooting of the SAR satellite image of the transmission line area;

[0224] Furthermore, the theoretical sag calculation module 3 calculates the theoretical sag value according to the following steps:

[0225] S31, obtaining the temperature t2 at the time of taking the SAR satellite image, and adjusting the sag state parameters of the transmission line based on the temperature t2;

[0226] The adjustment method is: calculate the total length L' of the transmission line in the design working condition at the temperature t2 s , and obtain the tension T2 of the transmission line in the design condition at temperature t2;

[0227] The total length of the transmission line L' s The calculation formula is as follows:

[0228] L′ s =L c(1+α(t2-t0));

[0229] S32, based on the adjusted total length L' of the transmission line s With the transmission line sag theoretical model, calculate the theoretical sag value of the transmission line at the time of shooting;

[0230] The expression of the theoretical sag value is as follows:

[0231]

[0232] Where: f s is the theoretical sag value of the transmission line at temperature t2.

[0233] The actual sag calculation module 4 obtains the scattered ray imaging position of the transmission line in the SAR satellite image based on the coordinate value of the transmission line in the SAR coordinate system, and obtains the range deviation function of the transmission line point cloud in the radar coordinate system and the SAR coordinate system; based on the range deviation function, simulates the expression of the transmission line in the sag coordinate system, and calculates the sag value of the transmission line at the time of satellite image shooting;

[0234] Furthermore, the actual sag calculation module 4 calculates the distance deviation function according to the following steps:

[0235] S41, select the geographic coordinate values ​​of the two tower foot points in the transmission line LiDAR point cloud, which are expressed as (B1, L1, H) and (B2, L2, H), respectively; where H needs to be kept on an ellipsoid; solve the range Doppler equation for the geographic coordinate values ​​to obtain the coordinate values ​​(i1, j1) and (i2, j2) in the SAR coordinate system;

[0236] S42, performing window clipping on the coordinate area based on the coordinate values ​​(i1, j1) and (i2, j2); wherein the window is not smaller than the pixel of {|i1-i2|+5}*{|j1-j2|+5};

[0237] S43, calculate the scattering intensity value of the SAR satellite image for the clipped window, and calculate the intensity value In=I in the coordinate area 2 +Q 2 ; After normalizing and counting the intensity values, the histogram In under the window is obtained dB =10·log 10 (In);

[0238] S44, based on the histogram In under the window dB , get the background scattering average intensity value RCS b And the average scattering intensity map RCS of the transmission line l , and the histogram In under the window dBFiltering is performed; the threshold of the filtering is RCS b +ΔRCS;

[0239] S45, average scattering intensity diagram of transmission lines RCS l The scattering characteristics are used to define the scattered lines; the scattering characteristics are

[0240] S46, extract the scattering features defined as scattered lines at the pixel level to obtain the position coordinate point set [ij] of each point constituting the scattered line imaging of the transmission line n ;

[0241] S47, for each point's position coordinate point set [ij] n Perform fitting to obtain the expression f(a) of the transmission line in the radar coordinate system;

[0242] In the expression f(a) of the transmission line, when the expression f(a) function defining the transmission line i in the radar coordinate system is a quadratic polynomial function, a is the azimuth coordinate of any point on the line in the radar coordinate system, and f(a) is the range coordinate of any point a on the transmission line i in the radar coordinate system;

[0243] S48. Connect the two points (i1, j1) and (i2, j2) in the SAR coordinate system to obtain a straight line equation g(a); the straight line equation is expressed as follows:

[0244] g(a)=k*a+b;

[0245] k = (j2-j1) / (i2-i1);

[0246] b = j2-(j2-j1) / (i2-i1)*i1;

[0247] Where: k is the coefficient of the linear term of the linear equation; a is the range coordinate value of any point in the SAR coordinate system; b is a constant;

[0248] S49. Obtain a range deviation function between g(a) and f(a) in the SAR coordinate system; the range deviation function is expressed as follows:

[0249] p(a)=|g(a)-f(a)|*δ r / cosη;

[0250] Where: p(a) is the range deviation function.

[0251] Furthermore, the actual sag calculation module 4 calculates the actual sag value according to the following steps:

[0252] S51, taking the azimuth direction n as the step length, a = min (i1, i2) + n, and bringing it into the range deviation function to calculate and obtain the three-dimensional point set of the transmission line radar scattering imaging [ijh] n , where h = p(a) + H;

[0253] S52. Based on the ellipsoid equation and the range Doppler equation, the three-dimensional point set of radar scattering imaging of transmission lines in the SAR coordinate system [ijh] n Transform to obtain the point set of the transmission line in the geographic coordinate system [B l L l H l ] n ;

[0254] S53, the point set in the geographic coordinate system of the transmission line [B l L l H l ] n Convert to the spatial rectangular coordinate system and obtain [X l Y l Z l ] n ;

[0255] S54. Use the plane formed by the two end points of the transmission line and the plumb line as the projection plane to establish a sag coordinate system, with [Xl Y l Z l ] n The lowest point in the point cloud is taken as the origin, and the point cloud coordinates are converted to obtain the point set of the transmission line in the sag coordinate system [M l N l ] n ;

[0256] M l =(X i -X0) / cosβ;

[0257] N l =Z i -Z0;

[0258] Where: M l is the M-axis coordinate value of any point i on the transmission line in the sag coordinate system, N l is the N-axis coordinate value of any point i on the transmission line in the sag coordinate system, X i is the X-axis coordinate value of any point i of the transmission line in the spatial rectangular coordinate system, X0 is the X-axis coordinate value corresponding to the origin of the transmission line in the spatial rectangular coordinate system, Z iis the Z-axis coordinate value of any point i of the transmission line in the spatial rectangular coordinate system, Z0 is the Z-axis coordinate value corresponding to the origin of the transmission line in the spatial rectangular coordinate system, β is the angle between the lines connecting the transmission lines in the XOY plane, X A , Y A With X B , Y B is the coordinate value of the rectangular coordinate system of the mounting points at both ends of the transmission line;

[0259] S55. Set the expression g of the transmission line in the sag coordinate system l (m) is a quadratic polynomial function based on [M1, N l ] n Fitting polynomial coefficients a1, a2, a3;

[0260] The expression g of the transmission line in the sag coordinate system is l (m) are as follows:

[0261] q l (m) = a1*m*m+a2*m+a3;

[0262] Where: m is the M-axis coordinate value of any point on the transmission line in the sag coordinate system;

[0263] S56. Obtain the coordinates of the mounting points at both ends of the transmission line in the sag coordinate system k l (m); the expression of the sag coordinate system is as follows:

[0264]

[0265] Where: n B is the coordinate value of the mounting point B on the N axis in the sag coordinate system, n A is the coordinate value of the mounting point A on the N axis in the sag coordinate system, m B is the coordinate value of the mounting point B on the M axis in the sag coordinate system, m A is the coordinate value of the M axis of the mounting point A in the sag coordinate system;

[0266] Then the sag expression of any point in the sag coordinate system is hc(m)=k l (m)-g l (m);

[0267] When m=0, the minimum sag value of the transmission line at the time of SAR satellite image shooting is calculated. Filming

[0268] When hc′ (m) = 0, the maximum sag value of the transmission line at the time of SAR satellite image shooting is calculated

[0269] The icing status assessment module 5 is used to compare the theoretical sag value of the transmission line with the sag value observed by satellite, determine the sag change of the transmission line after icing, and calculate the weight and thickness of the ice on the transmission line according to the transmission line stress model.

[0270] Further, the ice coating state assessment module 5 assesses stability according to the following steps:

[0271] S61. Calculate the theoretical sag value f s and minimum sag value The difference Obtain the sag change Δf of the transmission line ice ;

[0272] S62, based on the sag change Δf ice , calculate the ice thickness t of the transmission line i ; The expression of the ice layer thickness is as follows:

[0273]

[0274] Where: T is the initial stress, L d is the gear spacing, ρ i is the density of ice, d is the diameter;

[0275] S63, based on ice thickness t i Calculate the ice weight of the transmission line m ice =πdt i ρ i , and according to the deadweight ω of the transmission line and the ice weight m ice , calculate and obtain the unit weight of the transmission line after ice coating;

[0276] ω'=ω+m ice ;

[0277] S64, based on the unit weight ω′ and minimum sag value of the transmission line after ice coating Calculating Stresses in Transmission Lines

[0278] S65, comparing the stress T' of the transmission line with the initial stress T; if T and T' are inconsistent, T' is used as the initial stress, and steps S52-S55 are repeated until T and T' are consistent, and then step S66 is performed;

[0279] S66, according to the ice thickness t of the transmission line i , estimate the ice weight of the transmission line m ice ;

[0280] S67, the ice weight of the transmission line m ice , ice thickness ti Compare with the design threshold of the transmission conductor;

[0281] If the ice weight m ice , ice thickness t i If the ice weight m is within the design threshold, it indicates that the state of the transmission line and the tower is relatively stable. ice , ice thickness t i If it is outside the design threshold, it indicates that there is a large deformation of the transmission lines and towers and maintenance is required.

[0282] Embodiment 3:

[0283] See also Figure 7 , a transmission line ice monitoring device based on SAR satellite remote sensing, the device comprising a processor 6 and a memory 7;

[0284] The memory 7 is used to store computer program code 71 and transmit the computer program code 71 to the processor 6;

[0285] The processor 6 is used to execute the transmission line ice coverage monitoring method based on SAR satellite remote sensing described in Example 1 according to the instructions in the computer program code 71.

[0286] This embodiment also includes a computer-readable storage medium, in which computer-executable instructions are stored. When the computer-executable instructions are executed on a computer, the method for monitoring ice coating on transmission lines based on SAR satellite remote sensing described in Example 1 is implemented.

[0287] Generally speaking, the computer instructions for implementing the method of the present invention may be carried in any combination of one or more computer-readable storage media. Non-transitory computer-readable storage media may include any computer-readable media, except for the signal itself that is temporarily propagating.

[0288] The computer-readable storage medium may be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device or device, or any combination thereof. More specific examples of computer-readable storage media (a non-exhaustive list) include: an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EKROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof. In the present invention, a computer-readable storage medium may be any tangible medium containing or storing a program that may be used by or in conjunction with an instruction execution system, device, or device.

[0289] Computer program code for performing the operation of the present invention can be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, SMalltalk, C++, and conventional procedural programming languages ​​such as "C" or similar programming languages, in particular, Python suitable for neural network computing and platform frameworks based on TensorFlow, PyTorch, etc. can be used. The program code can be executed entirely on the user's computer, partially on the user's computer, as an independent software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the case of a remote computer, the remote computer can be connected to the user's computer or to an external computer (for example, using an Internet service provider to connect via the Internet) through any type of network, including a local area network (LAN) or a wide area network (WAN).

[0290] The above-mentioned device and non-temporary computer-readable storage medium can be found in the detailed description of a method for monitoring ice coating on power transmission lines based on SAR satellite remote sensing and its beneficial effects, which will not be repeated here.

[0291] Although the embodiments of the present invention have been shown and described above, it should be understood that the above embodiments are exemplary and should not be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for monitoring ice coating on power transmission lines based on SAR satellite remote sensing, characterized in that: include: S1. Obtain SAR satellite images of the transmission line area and its geometric positioning parameters; S2. Acquire the three-dimensional point cloud data of the transmission line in the geographic coordinate system, and construct a theoretical model of the transmission line sag under the influence of different temperatures and different stresses according to the product type of the transmission line and the stress parameters when it is mounted; S3, based on the theoretical model of the change of transmission line sag caused by the ambient temperature during the shooting of the SAR satellite image of the transmission line area, calculate the theoretical sag value of the transmission line sag affected by temperature; S4, based on the coordinate value of the transmission line in the SAR coordinate system, obtain the scattered line imaging position of the transmission line in the SAR satellite image, and obtain the distance deviation function of the transmission line point cloud in the radar coordinate system and the SAR coordinate system; S5. Based on the distance deviation function, simulate the expression of the transmission line in the sag coordinate system, and calculate the sag value of the transmission line at the time of satellite image shooting; S6. Compare the theoretical sag value of the transmission line with the sag value observed by satellite, determine the change in sag after the transmission line is covered with ice, and calculate the weight and thickness of the ice covering the transmission line based on the transmission line stress model.

2. The method for monitoring ice coating on power transmission lines based on SAR satellite remote sensing according to claim 1, characterized in that: The step S1 specifically includes: S11, obtaining the imaging parameters of the SAR satellite image and the actual measured coordinates of the ground control points; the imaging parameters include the azimuth resolution δ a , range resolution δ r , radar satellite frequency, perigee distance, local incidence angle η, and satellite orbit data; S12. Based on the imaging parameters of the SAR satellite image and the range Doppler model, determine the geometric positioning coordinates of the actual measured coordinates of the ground control point in the radar coordinate system; S13, based on the geometric positioning coordinates of the actual measured coordinates of the ground control point in the radar coordinate system and the positioning deviation value of the coordinates of the center point of the radar scattering imaging of the ground control point, correct the geometric positioning of the SAR satellite image of the transmission line area; The coordinates of the center point of the ground control point in the radar scattering imaging are: the coordinates of the extreme point of the scattering intensity within the preset range of the ground control point target.

3. The method for monitoring ice coating on power transmission lines based on SAR satellite remote sensing according to claim 2 is characterized in that: The step S2 specifically includes: S21. Obtain the transmission line spacing L at temperature t0 d , unit weight ω, diameter d, and tension T0 are used to construct the catenary sag equation; the expression of the catenary sag equation is as follows: S22. Based on the LiDAR point cloud data of the transmission line at temperature t1, obtain the three-dimensional point cloud of the transmission line; take the lowest point of the three-dimensional point cloud of the transmission line as the origin, reconstruct the local two-dimensional Cartesian coordinate system, fit the catenary sag equation for the coordinate values ​​of each point of the transmission line in the two-dimensional coordinate system, and obtain the initial line length L of the transmission line c And the measured sag value f of the transmission line at temperature t1 c ; S23, obtaining the thermal expansion coefficient α of the transmission line and the tension T1 of the transmission line at temperature t1, and calculating the total length L′ of the thermally expanded line at temperature t1 compared with that at temperature t0 in the design condition. c ; The total length of the thermal expansion wire is L' c The expression is as follows: IT' c =L c ·(1+α(t1-t0)); S24. Calculate the design sag value f of the transmission line at temperature t1 based on the catenary sag equation d , and compare the design sag value f of the transmission line at temperature t1 d Compared with the measured sag value f c The difference between If the difference between the two satisfies |f d -f c |≤0.05·f d , the parameters of the transmission line meet the requirements, and the transmission line sag theoretical model is constructed based on these parameters; If the difference between the two does not satisfy |f d -f c |≤0.05·f d , other influencing factors need to be considered.

4. The method for monitoring ice coating on power transmission lines based on SAR satellite remote sensing according to claim 3 is characterized in that: The other influencing factors include wind load influence, and the specific steps are as follows: S25, substituting the wind load into the catenary sag equation, and repeating steps S21-S24; the catenary sag equation considering the wind load is expressed as follows: The expression of wind load is as follows: Where: C d is the damping coefficient, ρ is the air density, A is the windward area, and v is the wind speed.

5. The method for monitoring ice coating on power transmission lines based on SAR satellite remote sensing according to claim 3 is characterized in that: The step S3 specifically includes: S31, obtaining the temperature t2 at the time of taking the SAR satellite image, and adjusting the sag state parameters of the transmission line based on the temperature t2; The adjustment method is: calculate the total length L' of the transmission line in the design working condition at the temperature t2 s , and obtain the tension T2 of the transmission line in the design condition at temperature t2; The total length of the transmission line L' s The calculation formula is as follows: L′ s =L c ·(1+α(t2-t0)); S32, based on the adjusted total length L' of the transmission line s With the transmission line sag theoretical model, calculate the theoretical sag value of the transmission line at the time of shooting; The expression of the theoretical sag value is as follows: Where: f s is the theoretical sag value of the transmission line at temperature t2.

6. The method for monitoring ice coating on power transmission lines based on SAR satellite remote sensing according to claim 4 is characterized in that: The step S4 specifically includes: S41, select the geographic coordinate values ​​of the two tower foot points in the transmission line LiDAR point cloud, which are expressed as (B1, L1, H) and (B2, L2, H), respectively; where H needs to be kept on an ellipsoid; solve the range Doppler equation for the geographic coordinate values ​​to obtain the coordinate values ​​(i1, j1) and (i2, j2) in the SAR coordinate system; S42, performing window clipping on the coordinate area based on the coordinate values ​​(i1, j1) and (i2, j2); wherein the window is not smaller than the pixel of {|i1-i2|+5}*{|j1-j2|+5}; S43, calculate the scattering intensity value of the SAR satellite image for the clipped window, and calculate the intensity value In=I in the coordinate area 2 +Q 2 ; After normalizing and counting the intensity values, the histogram Ina under the window is obtained B =10·Log 10 (In); S44, based on the histogram In under the window dB , get the background scattering average intensity value RCS b And the average scattering intensity map RCS of the transmission line f , and the histogram In under the window dB Filtering is performed; the threshold of the filtering is RCS b +ΔRCS; S45, average scattering intensity diagram of transmission lines RCS f The scattering characteristics are used to define the scattered lines; the scattering characteristics are S46, extract the scattering features defined as scattered lines at the pixel level to obtain the position coordinate point set [ij] of each point constituting the scattered line imaging of the transmission line n ; S47, for each point's position coordinate point set [ij] n Perform fitting to obtain the expression f(a) of the transmission line in the radar coordinate system; In the expression f(a) of the transmission line, when the expression f(a) function defining the transmission line i in the radar coordinate system is a quadratic polynomial function, a is the azimuth coordinate of any point on the line in the radar coordinate system, and f(a) is the range coordinate of any point a on the transmission line i in the radar coordinate system; S48. Connect the two points (i1, j1) and (i2, j2) in the SAR coordinate system to obtain a straight line equation g(a); the straight line equation is expressed as follows: g(a)=k*a+b; k = (j2-j1) / (i2-i1); b=j2-(j2-j1) / (i2-i1)*i1; Where: k is the coefficient of the linear term of the linear equation; a is the range coordinate value of any point in the SAR coordinate system; b is a constant; S49. Obtain a range deviation function between g(a) and f(a) in the SAR coordinate system; the range deviation function is expressed as follows: p(a)=|g(a)-f(a)|*δ r / cosη: Where: p(a) is the range deviation function.

7. The method for monitoring ice coating on power transmission lines based on SAR satellite remote sensing according to claim 6 is characterized in that: The step S5 specifically includes: S51, taking the azimuth direction n as the step length, a = min (i1, i2) + n, and bringing it into the range deviation function to calculate and obtain the three-dimensional point set of the transmission line radar scattering imaging [ijh] n , where h = p(a) + H; S52. Based on the ellipsoid equation and the range Doppler equation, the three-dimensional point set of radar scattering imaging of transmission lines in the SAR coordinate system [ijh] n Transform to obtain the point set of the transmission line in the geographic coordinate system [B f L l H l ] n ; S53, the point set in the geographic coordinate system of the transmission line [B l L l H l ] n Convert to the spatial rectangular coordinate system and obtain [X l Y l Z l ] n ; S54. Use the plane formed by the two ends of the transmission line and the plumb line as the projection plane to establish a sag coordinate system, with [X l Y l Z l ] n The lowest point in the point cloud is taken as the origin, and the point cloud coordinates are converted to obtain the point set of the transmission line in the sag coordinate system [M l N l ] n ; M f =(X i -X0) / cosβ; N l =Z i -Z0; Where: M f is the M-axis coordinate value of any point i on the transmission line in the sag coordinate system, N f is the N-axis coordinate value of any point i on the transmission line in the sag coordinate system, X i is the X-axis coordinate value of any point i of the transmission line in the spatial rectangular coordinate system, X0 is the X-axis coordinate value corresponding to the origin of the transmission line in the spatial rectangular coordinate system, Z i is the Z-axis coordinate value of any point i of the transmission line in the spatial rectangular coordinate system, Z0 is the Z-axis coordinate value corresponding to the origin of the transmission line in the spatial rectangular coordinate system, β is the angle between the lines connecting the transmission lines in the XOY plane, X A , Y A With X B , Y B is the coordinate value of the rectangular coordinate system of the mounting points at both ends of the transmission line; S55. Set the expression g of the transmission line in the sag coordinate system l (m) is a quadratic polynomial function, and based on [M l N l ] n Fitting polynomial coefficients a1, a2, a3; The expression gf(m) of the transmission line in the sag coordinate system is as follows: g l (m)=a1*m*m+a2*m+a3; Where: m is the M-axis coordinate value of any point on the transmission line in the sag coordinate system; S56. Obtain the coordinates of the mounting points at both ends of the transmission line in the sag coordinate system k l (m); the expression of the sag coordinate system is as follows: Where: n B is the coordinate value of the mounting point B on the N axis in the sag coordinate system, n A is the coordinate value of the mounting point A on the N axis in the sag coordinate system, m B is the coordinate value of the mounting point B on the M axis in the sag coordinate system, m A is the coordinate value of the M axis of the mounting point A in the sag coordinate system; Then the sag expression of any point in the sag coordinate system is hc(m)=k l (m)-g l (m); When m = 0, the minimum sag value f′s of the transmission line at the time of SAR satellite image shooting is calculated. min ; When hc′ (m) = 0, the maximum sag value f′s of the transmission line at the time of SAR satellite image shooting is calculated max .

8. The method for monitoring ice coating on power transmission lines based on SAR satellite remote sensing according to claim 7 is characterized in that: The step S6 specifically includes: S61. Calculate the theoretical sag value f s and minimum sag value f′s min The difference f′s min -f s , obtain the sag change Δfi of the transmission line ce ; S62, based on the sag change Δf ice , calculate the ice thickness t of the transmission line i ; The expression of the ice layer thickness is as follows: Where: T is the initial stress, L d is the gear spacing, ρ i is the density of ice, d is the diameter; S63, based on ice thickness t i Calculate the ice weight of the transmission line m ice =πdt i ρ i , and according to the deadweight ω of the transmission line and the ice weight m ice , calculate the unit weight of the transmission line after ice coating; ω′=ω+m ice ; S64, based on the unit weight ω′ of the transmission line after ice coating and the minimum sag value f′s min , calculate the stress of the transmission line T′=ω′L d 2 / 8f′s min ; S65, comparing the stress T' of the transmission line with the initial stress T; if T and T' are inconsistent, T' is used as the initial stress, and steps S52-S55 are repeated until T and T' are consistent, and then step S66 is performed; S66, according to the ice thickness t of the transmission line i , estimate the ice weight of the transmission line m ice ; S67, the ice weight of the transmission line m ice , ice thickness t i Compare with the design threshold of the transmission conductor; If the ice weight m ice , ice thickness t i If the ice weight m is within the design threshold, it indicates that the state of the transmission line and the tower is relatively stable. ice , ice thickness t i If it is outside the design threshold, it indicates that there is a large deformation of the transmission lines and towers and maintenance is required.

9. A transmission line ice monitoring system based on SAR satellite remote sensing, characterized in that: The system is applied to the method described in any one of claims 1 to 8, and the system comprises: An image positioning acquisition module (1) is used to acquire SAR satellite images of the transmission line area and its geometric positioning parameters; A sag stress model building module (2) is used to obtain three-dimensional point cloud data of the transmission line in the geographic coordinate system, and to build a theoretical model of the transmission line sag under different temperature influences and different stresses according to the product type of the transmission line and the stress parameters when the transmission line is mounted; Theoretical sag calculation module (3), used for calculating the theoretical sag value of the transmission line sag affected by temperature based on the theoretical model of the change of the transmission line sag caused by the ambient temperature during the shooting of the SAR satellite image of the transmission line area; The actual sag calculation module (4) is used to obtain the scattered ray imaging position of the transmission line in the SAR satellite image based on the coordinate value of the transmission line in the SAR coordinate system, and obtain the range deviation function of the transmission line point cloud in the radar coordinate system and the SAR coordinate system; based on the range deviation function, simulate the expression of the transmission line in the sag coordinate system, and calculate the sag value of the transmission line at the time of satellite image shooting; The ice coating state assessment module (5) is used to compare the theoretical sag value of the transmission line with the sag value observed by satellite, determine the sag change of the transmission line after ice coating, and calculate the ice coating weight and thickness of the transmission line according to the transmission line stress model.

10. A transmission line ice monitoring device based on SAR satellite remote sensing, characterized in that: The device comprises a processor (6) and a memory (7); The memory (7) is used to store computer program code (71) and transmit the computer program code (71) to the processor (6); The processor (6) is used to execute the transmission line ice coverage monitoring method based on SAR satellite remote sensing according to any one of claims 1 to 8 according to the instructions in the computer program code (71).

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