An automatic sag measurement method for power transmission projects based on laser point cloud

Abstract

The invention discloses an automatic sag measurement method for power transmission engineering based on laser point cloud, comprising: obtaining power transmission engineering laser point cloud data in LAS format within a unit span, processing the point cloud data, obtaining tower point cloud and power line point cloud, determining the number of transmission line loops of the span based on the power line point cloud and voting method, classifying each power line according to the number of transmission line loops, and determining the positional relationship of the power lines, using the centroid points of each classified power line for parabola equation fitting, and obtaining sag based on the fitted parabola equation. The method can solve the inaccuracy problem caused by manual measurement.

Description

Technical Field

[0001] The present invention relates to the technical field of power transmission and transformation engineering construction, and more specifically to an automatic sag measurement method for power transmission engineering based on laser point cloud. Background Art

[0002] Nowadays, 3D laser scanning technology has been widely used in power transmission line inspection and completion acceptance. During the inspection and completion acceptance, line sag measurement is a crucial task. At present, the power transmission line sag measurement method based on laser point cloud mainly uses manual point selection measurement, which is not only inefficient but also prone to operational errors. Therefore, it is of great significance to improve the power transmission line sag measurement method based on laser point cloud data. Summary of the invention

[0003] The embodiment of the present invention provides a method for automatic sag measurement of a power transmission project based on laser point cloud, comprising:

[0004] Obtain the laser point cloud data of the power transmission project in LAS format within the unit span;

[0005] Process point cloud data to obtain tower point cloud and power line point cloud;

[0006] Segment and cluster the power line point cloud to determine the number of transmission line loops within the span;

[0007] Classify each power line according to the number of transmission line loops and determine the positional relationship of the power lines;

[0008] The centroid points of the classified power lines are used for parabola equation fitting;

[0009] Obtain sag based on the fitted parabola equation;

[0010] Among them, the power line point cloud is segmented and clustered to determine the number of transmission line loops within the span, specifically including:

[0011] Divide the tower point cloud into T1 end and T2 end;

[0012] Use the vertical grid to segment the power line point cloud between the T1 end and the T2 end of the tower point cloud;

[0013] Perform K-MEANS clustering on the point clouds in each segmented grid and count the total number of clusters in each segmented grid;

[0014] The number of loops of the transmission line is determined by voting based on the total number of clusters.

[0015] Further, the point cloud data is processed to obtain the tower point cloud and power line point cloud, including:

[0016] Statistical analysis methods are used to filter out outliers in the LAS format of the power transmission project laser point cloud data within a unit span;

[0017] Traverse each point in the parsed point cloud and extract the remaining points after filtering out ground points and vegetation points;

[0018] The remaining points are classified according to their respective classification numbers to form a point cloud set P_SET = {P1, P2, ..., P l}, where l is the number of classification numbers;

[0019] Traverse the point cloud set P_SET, calculate the elevation difference of each point cloud, and perform K-MEANS clustering. The point cloud P with the largest elevation difference and K-MEANS clustering result of 2 is selected as i Identify it as a tower point cloud and extract it;

[0020] Traverse the remaining point cloud set P_SET' = {P1, P2, ..., P i-1 ,P i+1 ,...P n}, calculate the horizontal extension length of each point cloud where x max and x min are the maximum and minimum values ​​of the remaining point cloud in the x-axis direction, and y max and min are the maximum and minimum values ​​of the remaining point clouds in the y-axis direction respectively, and the one with the largest length value is identified as the power line point cloud.

[0021] Furthermore, the power line point cloud is segmented and clustered to determine the number of transmission line loops within the span, including:

[0022] Divide the tower point cloud into T1 end and T2 end, and calculate the centroid of T1 end respectively and the centroid of the T2 end according to Calculate the direction of the transmission line, from the centroid point and vector Construct vertical planes Plane1 and Plane2 respectively, retain the point cloud between the two vertical planes, filter out other point clouds, and then segment the power line point cloud with a vertical grid along the direction of the power line. gap_num=floor(dist / 5), where floor() means rounding down, and the vector Unitize The range formed by each segmented grid is expressed as follows:

[0023]

[0024] The value range of k is {1, 2, ..., gap_num-1}. The point cloud in each segmented grid is clustered by K-MEANS. The total number of clusters in each segmented grid is counted. If the total number of clusters is 5, the transmission line is determined to be a single circuit. If the total number of clusters is 8, the transmission line is determined to be a double circuit.

[0025] Furthermore, each power line is classified according to the number of transmission line loops, and the position relationship of the power lines is determined, including:

[0026] When the power line loop is determined to be a single loop, the centroids {c1, c2, c3, c4, c5} of the cluster point cloud are obtained through K-MEANS clustering. The two centroids with the largest z values ​​are classified as two ground lines, and the remaining three centroids are classified as three-phase power lines. Their left and right position relationships are determined based on the size of their x or y values.

[0027] When the power line loop is determined to be a double loop, the centroid of the cluster point cloud {c1, c2, c3, c4, c5, c6, c7, c8} is obtained through K-MEANS clustering, and the centroid point c0 (c x ,c y ,c z ), select the 8 centroid points that are smaller than c x or c y Those that are greater than c are classified into one category. x or c y The two centroids are classified into one category, and their upper and lower relationships are determined according to the size of their z values.

[0028] Furthermore, the centroid points of the classified power lines are used to fit the parabola equation, including:

[0029] Get the centroid point set {p1,p2,p3,...,p m};

[0030] According to the x and y coordinates of each point, the least squares method is used to fit the straight line equation L1:

[0031] L1:y=k1x+b1;

[0032] Find a straight line Intersection point with L1

[0033] The centroid point is converted from a three-dimensional point to a two-dimensional point. The conversion formula is as follows:

[0034]

[0035] Where d is the distance from point S to the origin;

[0036] According to the w and z coordinates of each centroid point, the parabolic equations of each fitted power line are obtained:

[0037] z=aw 2 +bw+c.

[0038] Further, the obtaining of the sag based on the fitted parabola equation includes:

[0039] According to the direction of the transmission line within the span Get two suspension points q of a single power line point cloud l (q lx ,q ly ,q lz ) and q r (q rx ,q ry ,q rz );

[0040] Convert the suspension points from three-dimensional points to two-dimensional points and obtain the equation of the straight line connecting the suspension points, L2:

[0041] L2: t = k2w + b2;

[0042] Solve the maximum value by combining the fitted parabolic equations of each power line and the straight line equation L2 connecting the suspension points:

[0043] f=k2w+b2-(aw 2 +bw+c)

[0044] when When , the maximum distance is obtained

[0045] The embodiment of the present invention provides a method for automatic sag measurement of power transmission engineering based on laser point cloud. Compared with the prior art, the method has the following beneficial effects:

[0046] The present invention realizes the full automation of transmission line sag measurement, which solves the shortcomings of field measurement such as high work intensity and terrain restrictions, and avoids the accuracy problems caused by manual operation. Furthermore, the present invention discusses in detail the modeling method of power line point cloud data of power transmission engineering, which has a wide range of applications, high accuracy, and high practical value, and promotes the application of point cloud processing technology in the field of power transmission engineering construction to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 A flowchart of an automatic sag measurement method for power transmission engineering based on laser point cloud provided by an embodiment of the present invention;

[0048] Figure 2A schematic diagram of power transmission project point cloud data classification for a power transmission project sag automatic measurement method based on laser point cloud provided by an embodiment of the present invention;

[0049] Figure 3 A schematic diagram of power line point cloud filtering of a method for automatic sag measurement of power transmission projects based on laser point cloud provided by an embodiment of the present invention;

[0050] Figure 4 A schematic diagram of a power line point cloud segmentation of a method for automatic sag measurement of a power transmission project based on laser point cloud provided by an embodiment of the present invention;

[0051] Figure 5 A schematic diagram of reconstruction of a three-dimensional model of a power line point cloud for an automatic sag measurement method for a power transmission project based on laser point cloud provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0052] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0053] See also Figures 1 to 4 The present invention provides an automatic sag measurement method for power transmission projects based on laser point cloud. Here, the Qizhuang-Yinghu 220kV line project in Suqian City, Jiangsu Province is taken as an example to illustrate the implementation process of the present invention in detail.

[0054] like Figure 1 As shown in the implementation flow chart of the present invention, a method for automatic sag measurement of power transmission engineering based on laser point cloud comprises the following steps:

[0055] (1) Inputting the LAS format power transmission project laser point cloud file in units of span, and dividing it into four categories: ground points, vegetation points, tower points and power line points. Step (1) includes the following steps:

[0056] 1-1) Input the LAS format point cloud file in units of span, and use statistical analysis methods to filter out outliers;

[0057] 1-2) By traversing each point in the point cloud, extract the points with classification number 2 and classify them as ground points, extract the points with classification numbers 3 to 9 and classify them as vegetation points, and classify the remaining points according to their respective classification numbers to form a point cloud set P_SET = {P1, P2, ..., P l}(l is the number of classification numbers);

[0058] 1-3) Traverse the point cloud set P_SET, calculate the elevation difference of each point cloud, and perform K-MEANS clustering. The point cloud P with the largest elevation difference and K-MEANS clustering result of 2 is selected as i Identify it as the tower point cloud TowerCloud and take it out from the point cloud set P_SET;

[0059] 1-4) Traverse the point cloud set P_SET' = {P1, P2, ..., P i-1 ,P i+1 ,...P n}, calculate the horizontal extension length of each point cloud where x max and x min are the maximum and minimum values ​​of the point cloud in the x-axis direction, and y max and min are the maximum and minimum values ​​of the point cloud in the y-axis direction respectively, and the one with the largest dist value is identified as the power line point cloud LineCloud, such as Figure 2 This is the classification result of the point cloud for this span, where ground points are purple, vegetation points are green, tower points are blue, and power line points are red.

[0060] (2) Determine the number of transmission line loops of the span based on the power line point cloud and voting method. Step (2) includes the following steps:

[0061] 2-1) First input the tower point cloud TowerCloud, and divide it into tower point clouds T1 and T2 according to the clustering results of the previous step, and calculate the centroids of point clouds T1 and T2 respectively. The following formula is the centroid of point cloud T1 Calculation method, T2 centroid Similarly:

[0062]

[0063]

[0064]

[0065] Where n is the size of point cloud T1, x 1j ,y 1j and z 1j They are respectively the midpoint t of point cloud T1 j The x-axis, y-axis, and z-axis coordinates.

[0066] The centroid of the tower point cloud T1 within this span is calculated to be (740.209m, -1292.68m, 32.3484m) and the centroid of T2 is (1059.56m, -1457.17m, 31.7829m).

[0067] 2-2) Using vectors Indicates the direction of the transmission line at this span, vector The calculation method is

[0068]

[0069] Calculated

[0070] 2-3) From the centroid point and vector Construct vertical planes Plane1 and Plane2 respectively, and the calculation formula is as follows:

[0071] Plane1:v x x+v y y+d1=0

[0072] Plane2:v x x+v y y+d2=0

[0073] d1=-(T 1x *v x +T 1y *v y )

[0074] d2=-(T 2x *v x +T 2y *v y )

[0075] The calculated equations of planes Plane1 and Plane2 are:

[0076] Plane1:-319.347x+164.49y=449017

[0077] Plane2:-319.347x+164.49y=578056

[0078] 2-4) If the electric line point q(q x ,q y ,q z ) If the following conditions are met at the same time, the point is between the vertical planes Plane1 and Plane2 and is retained; otherwise, it is filtered out.

[0079]

[0080] Figure 3 This is the effect after removing redundant power lines.

[0081] 2-5) Next, segment the power line point cloud using vertical grids along the power line direction. gap_num = floor(dist / 5), where floor() means rounding down, and the vector Unitize The range formed by each segmented grid can be expressed as follows:

[0082]

[0083] The value range of k is {1,2,...,gap_num-1}.

[0084] Figure 4 This is a segmented schematic diagram of the power line point cloud. The calculated dist is 359.221 and gap_num is 71.

[0085] 2-6) Finally, K-MEANS clustering is performed on the point cloud in each segmented grid, and the clustering results are {res1,res2,...,res gap_num-1}, count the total number of each clustering result, and take the one with the largest total number as the final number of loops of the power line of the transmission line with this span. The clustering result here is 8, indicating that the transmission project adopts the dual-loop assumption method.

[0086] (3) Fitting the power line point cloud based on the least squares method to obtain the parabolic model of each power line. Step (3) includes the following steps:

[0087] 3-1) If the clustering result in the previous step is 5, it is judged as a single loop. Assume that the centroids of the obtained cluster point cloud are {c1, c2, c3, c4, c5} respectively. The two centroids with the largest z values ​​are classified as two ground lines, and the remaining three centroids are classified as three-phase power lines. Their left and right position relationships are determined based on the size of their x or y values.

[0088] If the clustering result in the previous step is 8, it is judged as a double loop. Assume that the centroids of the obtained cluster point cloud are {c1, c2, c3, c4, c5, c6, c7, c8} respectively. Find the centroid point c0 (c x ,c y ,c z ), select the 8 centroid points that are smaller than c x or c y Those are classified as Class 1, greater than c x or c y The ones are classified into category 1. Among these two types of centroids, their upper and lower relationships are determined according to their z values.

[0089] 3-2) Next, the centroids of the classified power lines are used to fit the parabola equation. Let the centroid set of one of the power lines be {p1, p2, p3, ..., p m}, according to the x and y coordinates of each point, the least squares method is used to fit the straight line equation L1:

[0090] L1:y=k1x+b1

[0091] Taking the upper left phase electric power line as an example, the equation of the fitted straight line is: y=-0.514797x-924.445.

[0092] 3-3) Find the straight line Intersection point with L1 The centroid point is converted from a three-dimensional point to a two-dimensional point. The conversion formula is as follows:

[0093]

[0094] 3-4) Where d is the distance from point S to the origin. Finally, according to the w and z coordinates of each centroid point, the parabolic equation of each power line is fitted:

[0095] z=aw 2 +bw+c

[0096] The parabola equation obtained by fitting the upper left phase conductor is: z = 0.000227496w 2 -0.653395w+528.713. The parabola equation obtained by fitting the upper right phase conductor is: z=0.000204252w 2 -0.586997w+482.006.

[0097] Figure 5 After all the power line equations are fitted, each power line is displayed in a different color.

[0098] (4) Obtaining the sag based on the parabolic model of each power line, step (4) comprises the following steps:

[0099] 4-1) The method of obtaining the sag based on the fitted parabola equation includes:

[0100] According to the direction of the transmission line within the span Get two suspension points q of a single power line point cloud l (q lx ,q ly ,q lz ) and q r (q rx ,q ry ,q rz );

[0101] Convert the suspension points from three-dimensional points to two-dimensional points and obtain the equation of the straight line connecting the suspension points, L2:

[0102] L2: t = k2w + b2;

[0103] Solve the maximum value by combining the fitted parabolic equations of each power line and the straight line equation L2 connecting the suspension points:

[0104] f=k2w+b2-(aw 2 +bw+c)

[0105] when When , the maximum distance is obtained

[0106] The equation of the straight line connecting the two suspension points of the upper left phase conductor is: z = -0.00270587w + 70.6892. The simultaneous equations give the axis of symmetry w = 1430.11, and the maximum distance is z = 7.25528. The equation of the straight line connecting the two suspension points of the upper right phase conductor is: z = -0.00307952x + 71.3673. The simultaneous equations give the axis of symmetry w = 1429.41, and the maximum distance is z = 6.68863.

[0107] Table 1 Power line sag measurement results

[0108] Power line name Upper left ground line Upper left wire Left center wire Lower left wire Sag(m) 7.25528 8.53895 8.38606 8.10813 Power line name Upper right ground line Upper right wire Right middle wire Lower right wire Sag(m) 6.68863 8.67196 8.39573 8.11706

[0109] Disclosed above are only a few specific embodiments of the present invention. Those skilled in the art may make various changes and modifications to the embodiments of the present invention without departing from the spirit and scope of the present invention. However, the embodiments of the present invention are not limited thereto. Any changes that can be conceived by those skilled in the art should fall within the scope of protection of the present invention.

Claims

1. A method for automatic sag measurement of power transmission engineering based on laser point cloud, characterized in that: include: Obtain the laser point cloud data of the power transmission project in LAS format within the unit span; Process point cloud data to obtain tower point cloud and power line point cloud; Segment and cluster the power line point cloud to determine the number of transmission line loops within the span; Classify each power line according to the number of transmission line loops and determine the positional relationship of the power lines; The centroid points of the classified power lines are used for parabola equation fitting; Obtain sag based on the fitted parabola equation; Among them, the power line point cloud is segmented and clustered to determine the number of transmission line loops within the span, specifically including: Divide the tower point cloud into T1 end and T2 end; Use the vertical grid to segment the power line point cloud between the T1 end and the T2 end of the tower point cloud; Perform K-MEANS clustering on the point clouds in each segmented grid and count the total number of clusters in each segmented grid; The number of loops of the transmission line is determined by voting based on the total number of clusters.

2. The automatic sag measurement method for power transmission engineering based on laser point cloud according to claim 1, characterized in that: The processing of point cloud data to obtain tower point cloud and power line point cloud includes: Statistical analysis methods are used to filter out outliers in the LAS format of the power transmission project laser point cloud data within a unit span; Traverse each point in the parsed point cloud and extract the remaining points after filtering out ground points and vegetation points; The remaining points are classified according to their respective classification numbers to form a point cloud set P_SET = {P1, P2, ..., P l }, where l is the number of classification numbers; Traverse the point cloud set P_SET, calculate the elevation difference of each point cloud, and perform K-MEANS clustering. The point cloud P with the largest elevation difference and K-MEANS clustering result of 2 is selected as i Identify it as a tower point cloud and extract it; Traverse the remaining point cloud set P_SET' = {P1, P2, ..., P i-1 ,P i+1 ,...P n }, calculate the horizontal extension length of each point cloud where x max and x min are the maximum and minimum values ​​of the remaining point cloud in the x-axis direction, and y max and min are the maximum and minimum values ​​of the remaining point clouds in the y-axis direction respectively, and the one with the largest length value is identified as the power line point cloud.

3. The automatic sag measurement method for power transmission engineering based on laser point cloud according to claim 1, characterized in that: Segment and cluster the power line point cloud to determine the number of transmission line loops within the span, including: Divide the tower point cloud into T1 end and T2 end, and calculate the centroid of T1 end respectively and the centroid of the T2 end according to Calculate the direction of the transmission line, from the centroid point and vector Construct vertical planes Plane1 and Plane2 respectively, retain the point cloud between the two vertical planes, filter out other point clouds, and then segment the power line point cloud with a vertical grid along the direction of the power line. gap_num=floor(dist / 5), where floor() means rounding down, and the vector Unitize The range formed by each segmented grid is expressed as follows: The value range of k is {1, 2, ..., gap_num-1}. The point cloud in each segmented grid is clustered by K-MEANS. The total number of clusters in each segmented grid is counted. If the total number of clusters is 5, the transmission line is determined to be a single circuit. If the total number of clusters is 8, the transmission line is determined to be a double circuit.

4. The automatic sag measurement method for power transmission engineering based on laser point cloud according to claim 3, characterized in that: The method of classifying each power line according to the number of power transmission line loops and determining the positional relationship of the power lines includes: When the power line loop is determined to be a single loop, the centroids {c1, c2, c3, c4, c5} of the cluster point cloud are obtained through K-MEANS clustering. The two centroids with the largest z values ​​are classified as two ground lines, and the remaining three centroids are classified as three-phase power lines. Their left and right position relationships are determined based on the size of their x or y values. When the power line loop is determined to be a double loop, the centroid of the cluster point cloud {c1, c2, c3, c4, c5, c6, c7, c8} is obtained through K-MEANS clustering, and the centroid point c0 (c x ,c y ,c z ), select the 8 centroid points that are smaller than c x or c y Those that are greater than c are classified into one category. x or c y The two types of centroids are classified into one category, and their upper and lower relationships are determined according to the size of their z values.

5. The automatic sag measurement method for power transmission engineering based on laser point cloud according to claim 4, characterized in that: The method of using the centroid points of the classified electric power lines for parabola equation fitting includes: Get the centroid point set {p1,p2,p3,...,p m }; According to the x and y coordinates of each point, the least squares method is used to fit the straight line equation L1: L1:y=k1x+b1; Find the line L2: Intersection point with L1 The centroid point is converted from a three-dimensional point to a two-dimensional point. The conversion formula is as follows: Where d is the distance from point S to the origin; According to the w and z coordinates of each centroid point, the parabolic equations of each fitted power line are obtained: z=aw 2 +bw+c。 6. The automatic sag measurement method for power transmission engineering based on laser point cloud according to claim 5, characterized in that: The method of obtaining the sag based on the fitting parabola equation includes: According to the direction of the transmission line within the span Get two suspension points q of a single power line point cloud l (q lx ,q ly ,q lz ) and q r (q rx ,q ry ,q rz ); Convert the suspension points from three-dimensional points to two-dimensional points and obtain the equation of the straight line connecting the suspension points, L2: L2: t = k2w + b2; Solve the maximum value by combining the fitted parabolic equations of each power line and the straight line equation L2 connecting the suspension points: <h2 style=";text-align:left;direction:ltr">f = k2w + b2 - (aw<h2 style=";text-align:left;direction:ltr"> 2 <h2 style=";text-align:left;direction:ltr"> +bw+c) when When , the maximum distance is obtained

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