Quantitative calculation method and system for three-dimensional space velocity of pilot channel

Abstract

The invention provides a pilot channel three-dimensional space velocity quantitative calculation method and system, and the method comprises the steps: building a positive polarity pilot discharge optical form dynamic and static image observation system through a high-speed camera and two single lens reflex cameras, and carrying out the optical shooting of a long-gap pilot discharge channel; and the static development process and the dynamic development process of the pilot channel are accurately obtained. For static images of a discharge channel obtained by two single lens reflex cameras, accurate inversion of a long-gap pilot discharge channel in a three-dimensional space can be realized by using a three-dimensional image inversion algorithm, and a dynamic development process of a pilot in the three-dimensional space is obtained by combining a pilot two-dimensional dynamic development process captured by a high-speed camera. And the pilot three-dimensional space velocity is accurately calculated.

Description

Technical Field

[0001] The invention relates to the field of high voltage electrical technology, and in particular to a method for quantitatively calculating the three-dimensional spatial velocity of a pilot channel. Background Art

[0002] The external insulation of EHV / UHV transmission and transformation equipment in power systems mainly relies on air gaps. The higher the voltage level of the equipment, the longer the required air gap distance. The pilot discharge is the main discharge form of long air gap discharge. Therefore, the long air gap positive polarity pilot discharge characteristics are an important basis for the insulation coordination of EHV / UHV transmission and transformation equipment operation overvoltage. In particular, the three-dimensional development speed of the positive polarity pilot is crucial for the refined design of insulation coordination of transmission and transformation projects.

[0003] The random evolution of the morphology of the positive polarity leader discharge channel makes it very difficult to measure its development speed. In the early days, photomultiplier tubes were mainly used to observe the leader length and speed. However, photomultiplier tubes can only record local luminescence information, and multiple photomultiplier tubes are required to measure the one-dimensional axial velocity of the leader. Other scholars used image converters to shoot the discharge channel, and calculated the leader velocity parameters based on the leader channel image obtained by shooting. However, the image converter only has a one-dimensional spatial resolution, and the obtained one-dimensional development velocity cannot fully represent the true development velocity of the leader channel.

[0004] In order to calculate the three-dimensional development speed of the leader channel, it is necessary to obtain the spatiotemporal evolution process of the three-dimensional path of the leader channel. MacAlpine et al. used prism spectrometry to obtain two pictures of the same discharge and synthesized the discharge channel in three-dimensional space, but the inversion accuracy of the leader three-dimensional path by this method is low, and the leader three-dimensional development speed calculated based on this method has a large error.

[0005] With the development of power electronics technology, high-speed photography technology has developed rapidly. High-speed cameras overcome the shortcomings of short recording time and low resolution of traditional recording methods. They can obtain the continuous development process of the leader discharge channel through high-speed and long-term shooting, and realize the accurate calculation of the leader development speed. However, in order to obtain the three-dimensional space of the leader channel, when two high-speed cameras are used for orthogonal shooting, there may be a problem of trigger asynchrony, which will cause errors in the process of inverting the three-dimensional leader channel. The SLR camera has a high spatial resolution of the image, and multiple SLR cameras can synchronously record the complete breakdown channel in long exposure mode, which provides a basis for the high-precision inversion of the leader channel in three-dimensional space. Summary of the invention

[0006] The technical problem to be solved by the present invention is how to solve the problem of trigger asynchronism when two high-speed cameras are used for orthogonal shooting to obtain the three-dimensional space of the pilot channel.

[0007] To solve the above problems, the present invention provides the following technical solution: a method for quantitatively calculating the three-dimensional spatial velocity of a pilot channel, comprising the following steps:

[0008] S1: The rod electrode is perpendicular to the ground plate electrode. The gap between the rod electrode and the ground plate electrode is used as the axis. SLR camera A and SLR camera B are arranged orthogonally. The shooting directions of SLR camera A and SLR camera B are parallel to the horizontal plane. The high-speed camera is placed at SLR camera A and has the same shooting direction as SLR camera A.

[0009] S2: SLR camera A and SLR camera B are controlled by computer to shoot, and static image A in xz coordinate system and static image B in yz coordinate system are obtained; modeling is performed to obtain xyz coordinate matrix A of the pilot channel in actual space B ;

[0010] S3: The impulse voltage generator generates a positive impulse voltage and applies it to the rod electrode, generating a pilot discharge channel between the rod electrode and the grounding plate electrode; when the voltage signal received by the oscilloscope reaches the trigger level, it outputs a trigger signal to control the high-speed camera to shoot the pilot discharge channel in the continuous time domain;

[0011] S4: According to the xyz coordinate matrix A of the pilot channel in the actual space B The leading discharge channel photographed by the high-speed camera is used to obtain the three-dimensional xyz coordinate matrix S of the leading channel head in all high-speed images. AB ;

[0012] S5: Calculate the time difference Δt between two frames of high-speed images; then calculate the distance matrix Δd of the leading head moving in the actual three-dimensional space between the two frames of high-speed images, and finally calculate the velocity matrix v of the leading head moving in the actual three-dimensional space between the two frames of high-speed images. T .

[0013] Preferably, in step S1, SLR camera A and SLR camera B are both placed 4 to 5 meters away from the rod electrode.

[0014] Preferably, the modeling process in step S2 includes the following steps:

[0015] S2-1: Read static image A and static image B, and obtain the position information matrix C of the center of the leading channel in the image taken by SLR camera A according to static image A. A , and static image B to obtain the position information matrix D of the center of the pilot channel in the image taken by SLR camera B B ; Use the interp1 interpolation function in MATLAB to interpolate C A and D BInterpolate to make the two have the same number of rows Z and get the new position information matrix C A ' and D B ';

[0016] S2-2: C A 'The first element of is used as the origin of the xz coordinate system to obtain the pixel coordinate C of the leading channel in the xz coordinate system A ”, with D B 'The first element of is used as the origin of the yz coordinate system to obtain the pixel coordinate D of the leading channel in the yz coordinate system B ”;

[0017] S2-3: Set pixel coordinates C A ”、D B ” are converted into xz coordinates C in real space respectively A ”' and D B "'; According to the xz coordinate C in the actual space A '' and D B "Get the xyz coordinate matrix A in the actual space B .

[0018] Preferably, in step S2-3, the pixel coordinate C A ”、D B "Converted to the xz coordinates C of d in real space A ”' and D B The formula for ' is:

[0019] C″′ A =C A ″·R;D″′ B =D B ″·R;

[0020] In the above formula, R is the spatial resolution of the static image.

[0021] Preferably, in step S3, the trigger signal is first converted into an optical signal by an electro-optical converter, and then converted into an electrical signal by an optical fiber-connected photoelectric converter, and then transmitted to the high-speed camera to control the high-speed camera to shoot.

[0022] Preferably, in step S4, the three-dimensional xyz coordinate matrix S of the leading channel head in all high-speed images is obtained. AB , including the following steps:

[0023] S4-1: Read the first frame of high-speed image and obtain the actual two-dimensional xz spatial coordinates of the leader head in this frame of high-speed image.

[0024] S4-2: Retrieval Matrix A BThe third column, that is, find the row number of the element with the same value as the second column of the xz spatial coordinate of this frame on the z axis. The xyz coordinate corresponding to this row represents the three-dimensional spatial coordinate of the leader head in this frame of image;

[0025] S4-3: After completing the above steps, continue to read the next frame of high-speed image and perform the same operations as the above steps until the three-dimensional space xyz coordinate matrix S of the leading channel head in all high-speed images is obtained. AB .

[0026] Preferably, in step S5, the formula for calculating the time difference Δt between two frames of high-speed images is: Δt=1 / Fps, where Fps is the shooting frequency set by the high-speed camera.

[0027] Preferably, in step S5, the formula for calculating the distance matrix Δd of the movement of the leading head in the actual three-dimensional space between two frames of high-speed images is:

[0028]

[0029] In the above formula, Δx1 represents the change in distance on the x-axis between the first frame and the second frame of high-speed image; Δy1 represents the change in distance on the y-axis at this time; Δz1 represents the change in distance on the z-axis at this time;

[0030] Δx2 represents the change in distance on the x-axis between the second and third high-speed images; Δy2 represents the change in distance on the y-axis at this time; Δz2 represents the change in distance on the z-axis at this time;

[0031] Δx n-1 Indicates the change in distance on the x-axis between the nth frame and the n-1th frame of high-speed image; Δy n-1 Indicates the change in distance on the y-axis at this time; Δz n-1 Indicates the change in distance on the z-axis at this time;

[0032] The formula for calculating the velocity matrix vT of the leader head moving in the actual three-dimensional space between two frames of high-speed images is: T =Δd / Δt.

[0033] Preferably, MATLAB software is used to read the static image A, the static image B and all high-speed images.

[0034] The present invention also provides a system for a method for quantitatively calculating the three-dimensional spatial velocity of a pilot channel, comprising the following modules;

[0035] Shooting module: including a computer, an oscilloscope, a SLR camera A and a SLR camera B and a high-speed camera; when the pilot channel is in a non-discharge state, the computer controls the orthogonally placed SLR cameras A and B to shoot, and obtains a static image A in the xz coordinate system and a static image B in the yz coordinate system; when the pilot channel is in a discharge state, the oscilloscope controls the high-speed camera to shoot the pilot discharge channel in a continuous time domain;

[0036] Modeling module: used to obtain the xyz coordinate matrix A of the pilot channel in the actual space based on the acquired static image A in the xz coordinate system and the static image B in the yz coordinate system B ;

[0037] A discharge channel generation module: comprising an impulse voltage generator, a rod electrode and a grounding plate electrode. The impulse voltage generator is used to generate a positive polarity impulse voltage, and when the impulse voltage is applied to the rod electrode, a pilot discharge channel is generated between the rod electrode and the grounding plate electrode.

[0038] Retrieval module: used to retrieve matrix A B The third column of , i.e., the number of rows on the z-axis where the element has the same value as the second column of the actual two-dimensional xz spatial coordinates of the leading head in the high-speed image, and the xyz coordinates corresponding to the row are expressed as the three-dimensional spatial coordinates of the leading head in the frame image, thereby generating the three-dimensional spatial xyz coordinate matrix S of the leading channel head in all high-speed images. AB ;

[0039] Calculation module: used to calculate the time difference Δt between two frames of high-speed images, the distance matrix Δd of the leading head moving in the actual three-dimensional space between the two frames of high-speed images, and the velocity matrix v of the leading head moving in the actual three-dimensional space between the two frames of high-speed images T .

[0040] The advantages of the present invention are: before a certain long gap discharge experiment begins, that is, a few seconds before the leading discharge channel appears, the SLR camera is set in a long exposure mode, and shooting can be completed without triggering. The development time of the leading channel is generally tens to hundreds of us, and the exposure time of the SLR camera can completely cover the development time of the leading channel, which can not only completely record the leading channel, but also effectively avoid the errors caused by the triggering asynchronism and triggering uncertainty of the two high-speed cameras. The present invention utilizes the long exposure advantage of the SLR camera to record the complete main leading channel, and then utilizes the continuous shooting mode of a single high-speed camera to record the dynamic evolution process of the leader, which can well avoid the synchronization problem of the high-speed camera, and can also analyze the dynamic three-dimensional development process of the positive leader and calculate the three-dimensional development speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1This is a schematic diagram of a three-dimensional space path observation system for a pilot channel in Example 1 of the present invention;

[0042] Figure 2 This is a flow chart for calculating the three-dimensional spatial development speed of the pilot channel in Example 1 of the present invention. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are 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.

[0044] Example 1

[0045] like Figure 1 As shown, firstly, a rod electrode, a grounding plate electrode, a single-lens reflex camera A, a single-lens reflex camera B and a high-speed camera are arranged. The rod electrode is perpendicular to the grounding plate ground level, and the impulse voltage generator is connected to the upper end of the rod electrode and can generate a positive impulse voltage. After the positive impulse voltage is generated, the rod electrode will generate a leading discharge channel developing toward the grounding plate electrode; the impulse voltage generator is connected to the rod electrode through an exposed copper wire, and the height of the high-voltage electrode to the ground is D m, generally more than 2 m, and the impulse voltage generator generates a 250 / 2500 us type standard operation impulse voltage waveform; the impulse voltage generator is connected to the voltage divider through a wire, and the voltage divider is connected to the oscilloscope through a coaxial cable. After receiving the voltage signal of the voltage divider, the oscilloscope displays and stores the waveform, and the oscilloscope is set to a trigger mode, and the trigger level is set to 500 mV; the shooting frequency of the high-speed camera is set to Fps frame / s, and the exposure time is set to Exp us. In this embodiment, the shooting frequency Fps=630000frame / s, and the exposure time Exp=1.5us.

[0046] With the gap between the rod electrode and the grounding plate electrode as the axis, SLR camera A and SLR camera B are arranged orthogonally. In this embodiment, the exposure time of the SLR camera is 3us. Both SLR camera A and SLR camera B are placed 4 to 5m away from the high-voltage electrode. The shooting directions of the SLR cameras are parallel to the horizontal plane. The high-speed camera is arranged at the position of SLR camera A, and its shooting direction is the same as that of SLR camera A and parallel to the horizontal plane.

[0047] Combination Figure 1 and Figure 2Before the discharge of the leading channel begins, the SLR camera A and the SLR camera B are controlled by a computer to shoot. The computer and the two SLR cameras are connected by a USB data cable to receive and obtain the static image of the leading channel shot by the SLR camera. After obtaining the static image A of the leading discharge breakdown channel in the xz coordinate system and the static image B of the leading discharge breakdown channel in the yz coordinate system, three-dimensional modeling is performed according to the static image A and the static image B. The specific modeling process is as follows:

[0048] S2-1: Use MATLAB software to read the static image A and obtain the gray value matrix Z Aij , i is the number of matrix rows, j is the number of matrix columns, in this embodiment, i = 4000, j = 5328; read Z A The grayscale values ​​of all elements in the grayscale value distribution are obtained; the grayscale value threshold A1 is set. In this embodiment, A1=254; Z A Set the elements below A1 to 0 and the elements above A1 to 255; read Z A In the first row, the 255 element is in Z A Column position A in m , m = 1, 2, 3 ... a; calculate Z A In the first row, all 255 elements are in Z A The average value C1 of the column number; the formula for calculating the average value C1 is:

[0049]

[0050] Continue reading Z A In the second row, the 255 element is in Z A Column position A in m , m = 1, 2, 3 ... a; calculate Z A In the second row, all 255 elements in Z A The average value of the number of columns in the image is C2, and the reading continues until the average value of the number of columns of 255 elements in all rows is calculated to form the position information matrix C of the center of the leading channel in the image taken by the SLR camera A A :

[0051] In this embodiment,

[0052] Also use MATLAB software to read the static image B and obtain the gray value matrix Z Bkl , k is the number of matrix rows, l is the number of matrix columns, in this embodiment, k = 1509, l = 770; read Z B The grayscale values ​​of all elements in the image are calculated to obtain the grayscale value distribution; the grayscale value threshold B1, Z B Set the elements below B1 to 0 and the elements above B1 to 255; read ZB In the first row, the 255 element is in Z B Column position B in n , n = 1, 2, 3...b; calculate Z B In the first row, all 255 elements are in Z B The average value D1 of the column number is calculated as follows:

[0053]

[0054] Continue reading Z B In the second row, the 255 element is in Z B Column position B in n , n = 1, 2, 3...b; calculate Z B In the second row, all 255 elements in Z B The average value of the number of columns in the middle is C2, and the reading continues until the column average value of 255 elements in all rows is calculated to form the position information matrix D of the center of the leading channel in the image taken by the SLR camera B B , D B It is expressed as:

[0055] In this embodiment,

[0056] Then use the interp1 interpolation function in MATLAB to interpolate C A and D B Interpolate so that both have the same number of rows Z, and then get the matrix C A ' and matrix D B ':

[0057]

[0058] In this embodiment,

[0059]

[0060] S2-1: Set the first element in the first row of pixels in the static image A, i.e. (1, C1'), as the origin of the xz coordinate system, and obtain the pixel coordinate C of the leading discharge channel in the xz coordinate system. A ”:

[0061] In this embodiment,

[0062] The first element in the first row of pixels in the static image B, i.e. (1, D1'), is set as the origin of the yz coordinate system to obtain the pixel coordinate D of the leading discharge channel in the yz coordinate system. B ”:

[0063] In this embodiment,

[0064] Calculate the spatial resolution R of the static image:

[0065] R = D / Z;

[0066] In this embodiment, R = 0.002 meters, where D is the gap distance, Z is C A ' and C B 'The number of lines;

[0067] S2-3: Use the formula to convert pixel coordinates C A ” and D B ” are converted into the actual space xz coordinates C A ”' and yz coordinate D B ”', the conversion formula is:

[0068] C″′ A =C A ″·R;D″′ B =D B ″·R;

[0069] Specific:

[0070]

[0071] In this embodiment, C A ”' and D B ”' are:

[0072]

[0073] According to C A ”' and D B ”', obtain the xyz coordinate matrix A of the leading breakdown channel in the actual space B :

[0074]

[0075] In this embodiment, The modeling process is now complete.

[0076] The impulse voltage generator is started to generate a positive impulse voltage, and the rod electrode generates a leading discharge channel that develops toward the ground plate electrode. When the voltage signal of the voltage divider received by the oscilloscope reaches the trigger level, the oscilloscope outputs a trigger signal; the trigger signal is converted into an optical signal by the electro-optical converter, and then converted into an electrical signal by the photoelectric converter connected by the optical fiber; after the high-speed camera receives the trigger signal converted by the photoelectric converter, it is synchronously triggered and shoots the leading channel in the continuous time domain; because the high-speed camera is at the position of the SLR camera A, the high-speed image captured is a two-dimensional xz coordinate system. After the high-speed camera shoots, in order to obtain the three-dimensional space xyz coordinate matrix S of the head of the leading channel in the high-speed image AB， Follow these steps:

[0077] S4-1: Use MATLAB to read the first frame of high-speed image, and use the imadjust function to invert the color of the high-speed image, and read the pixel matrix H of the inverted continuous high-speed image. uv , read H uv The tip of the middle rod electrode, that is, the bottom pixel of the rod electrode, is located in the row number u1 and the intersection position of the rod electrode vertically downward and the ground plate electrode is located in the row number u2; calculate the spatial resolution R of the high-speed image h :

[0078] R h =D / (u1-u2);

[0079] In this embodiment, R h = 0.016 m;

[0080] Read H uv In the first row, the number of columns with all 0 elements is h p , p=1, 2, 3…q, in this embodiment, q=3, h1=26, h2=27, h3=28; calculate H uv In the first row, all 0 elements in H uv The average value h1 of the column number:

[0081]

[0082] Continue reading H uv The second row, the third row, etc. until H is calculated uv The column average of the 0 elements in all rows constitutes the position information matrix H of the center of the leading channel in the image taken by the high-speed camera. A :

[0083] In this embodiment, H A =

[27] ;

[0084] Set (1, h1) as the origin of the xz coordinate system and obtain the pixel coordinate H of the leading channel in the xz coordinate system. A ':

[0085] In this embodiment, H' A = [1 0];

[0086] The pixel coordinate H A 'Convert to actual space xz coordinates H A ", the conversion formula is:

[0087] H A =H A ′·R h ;

[0088] Specifically:

[0089] In this embodiment, H″ A = [0 0];

[0090] Thus, the actual two-dimensional xz space icon (h u -h1)·R h , (u-1)·R h ); In this embodiment, the actual two-dimensional xz space coordinates of the leading head in this frame of high-speed image are (0,0).

[0091] S4-2: Search the third column of matrix AB for the value that matches (u-1)·R h The xyz coordinates of the row represent the three-dimensional spatial coordinates of the leader head in the frame image. In this embodiment,

[0092] S4-3: Continue to read the second and third high-speed images, and perform the operations in S4-1 and S4-2 until the three-dimensional xyz coordinate matrix S of the leading channel head in all high-speed images is obtained. AB :

[0093]

[0094] In this embodiment,

[0095] According to the three-dimensional space xyz coordinate matrix S of the pilot channel head AB , calculate the time difference Δt between two frames of high-speed images:

[0096] Δt=1 / FPS;Δt=7.94us.

[0097] Then the distance matrix Δd of the leader head moving in the actual three-dimensional space between the two frames of high-speed images is calculated:

[0098]

[0099] In the above formula, Δx1 represents the change in distance on the x-axis between the first frame and the second frame of high-speed image; Δy1 represents the change in distance on the y-axis at this time; Δz1 represents the change in distance on the z-axis at this time;

[0100] Δx2 represents the change in distance on the x-axis between the second and third high-speed images; Δy2 represents the change in distance on the y-axis at this time; Δz2 represents the change in distance on the z-axis at this time;

[0101] Δx n-1 Indicates the change in distance on the x-axis between the nth frame and the n-1th frame of high-speed image; Δy n-1 Indicates the change in distance on the y-axis at this time; Δz n-1 Indicates the change in distance on the z-axis at this time;

[0102] Specifically,

[0103]

[0104] In this embodiment,

[0105] Finally, the velocity matrix v of the leading head moving in the actual three-dimensional space between two frames of high-speed images is calculated. T :

[0106]

[0107] In this embodiment,

[0108] The present embodiment provides a three-dimensional space quantitative calculation method for a leader channel, and adopts a SLR camera for dynamic modeling. The SLR camera has the characteristics of high spatial resolution, and can completely obtain the breakdown channel of the gap, especially for a discharge channel with a large degree of tortuosity of the leader channel, and its long exposure mode can complete the shooting without a trigger signal, that is, the SLR camera can not only completely record the leader channel, but also effectively avoid the errors caused by different triggering and triggering uncertainty of the two high-speed cameras, and can realize the accurate inversion of the three-dimensional space of the long gap leader discharge channel.

[0109] The continuous shooting mode of the high-speed camera can record the dynamic development process of the pilot channel, greatly improving the time resolution. According to the high-speed images recorded by the high-speed camera, the three-dimensional spatial coordinates of the pilot head can be determined in real time, the three-dimensional development length of the pilot can be calculated, and the three-dimensional speed of the pilot can be obtained in real time. In short, this method is simple in layout and easy to operate. While taking into account convenience, it can complete the calculation of the three-dimensional development speed of the pilot channel under the conditions of high spatial resolution and time resolution.

[0110] Example 2

[0111] Corresponding to the first embodiment of the present invention, the second embodiment of the present invention further provides a pilot channel three-dimensional space velocity quantitative calculation system, comprising the following modules:

[0112] Shooting module: including a computer, an oscilloscope, a SLR camera A and a SLR camera B and a high-speed camera; when the pilot channel is in a non-discharge state, the computer controls the orthogonally placed SLR cameras A and B to shoot, and obtains a static image A in the xz coordinate system and a static image B in the yz coordinate system; when the pilot channel is in a discharge state, the oscilloscope controls the high-speed camera to shoot the pilot discharge channel in a continuous time domain;

[0113] Modeling module: used to obtain the xyz coordinate matrix A of the pilot channel in the actual space based on the acquired static image A in the xz coordinate system and the static image B in the yz coordinate system B ; The specific modeling process is:

[0114] S2-1: Use MATLAB software to read the static image A and obtain the gray value matrix Z Aij , i is the number of matrix rows, j is the number of matrix columns; read Z A The grayscale values ​​of all elements in the image are calculated to obtain the grayscale value distribution; the grayscale value threshold A1 is set; Z A Set the elements below A1 to 0 and the elements above A1 to 255; read Z A In the first row, the 255 element is in Z A Column position A in m , m = 1, 2, 3 ... a; calculate Z A In the first row, all 255 elements are in Z A The average value C1 of the column number; the formula for calculating the average value C1 is:

[0115]

[0116] Continue reading Z A In the second row, the 255 element is in Z A Column position A in m , m = 1, 2, 3 ... a; calculate Z AIn the second row, all 255 elements in Z A The average value of the number of columns in the image is C2, and the reading continues until the average value of the number of columns of 255 elements in all rows is calculated to form the position information matrix C of the center of the leading channel in the image taken by the SLR camera A A :

[0117]

[0118] Also use MATLAB software to read the static image B and obtain the gray value matrix Z Bkl , k is the number of matrix rows, l is the number of matrix columns; read Z B The grayscale values ​​of all elements in the image are calculated to obtain the grayscale value distribution; the grayscale value threshold B1, Z B Set the elements below B1 to 0 and the elements above B1 to 255; read Z B In the first row, the 255 element is in Z B Column position B n , n = 1, 2, 3...b; calculate Z B In the first row, all 255 elements are in Z B The average value D1 of the column number is calculated as follows:

[0119]

[0120] Continue reading Z B In the second row, the 255 element is in Z B Column position B in n , n = 1, 2, 3...b; calculate Z B In the second row, all 255 elements in Z B The average value of the number of columns in the middle is C2, and the reading continues until the column average value of 255 elements in all rows is calculated to form the position information matrix D of the center of the leading channel in the image taken by the SLR camera B B , D B It is expressed as:

[0121]

[0122] Then use the interp1 interpolation function in MATLAB to interpolate C A and D B Interpolate so that both have the same number of rows Z, and then get the matrix C A ' and matrix D B ':

[0123]

[0124] S2-1: Set the first element in the first row of pixels in the static image A, i.e. (1, C1'), as the origin of the xz coordinate system, and obtain the pixel coordinate C of the leading discharge channel in the xz coordinate system. A ”:

[0125]

[0126] The first element in the first row of pixels in the static image B, i.e. (1, D1'), is set as the origin of the yz coordinate system to obtain the pixel coordinate D of the leading discharge channel in the yz coordinate system. B ”:

[0127]

[0128] Calculate the spatial resolution R of the static image:

[0129] R = D / Z;

[0130] S2-3: Use the formula to convert pixel coordinates C A ” and D B ” are converted into the actual space xz coordinates C A ”' and yz coordinate D B ”', the conversion formula is:

[0131] C″′ A =C A ″·R;D″′ B =D B ″·R;

[0132] Specific:

[0133]

[0134] According to C A ”' and D B ”', obtain the xyz coordinate matrix A of the leading breakdown channel in the actual space B :

[0135] The modeling process is now complete.

[0136] A discharge channel generation module: comprising an impulse voltage generator, a rod electrode and a grounding plate electrode. The impulse voltage generator is used to generate a positive polarity impulse voltage, and when the impulse voltage is applied to the rod electrode, a pilot discharge channel is generated between the rod electrode and the grounding plate electrode.

[0137] Retrieval module: used to retrieve matrix A BThe third column of , i.e., the number of rows on the z-axis where the element has the same value as the second column of the actual two-dimensional xz spatial coordinates of the leading head in the high-speed image, and the xyz coordinates corresponding to the row are expressed as the three-dimensional spatial coordinates of the leading head in the frame image, thereby generating the three-dimensional spatial xyz coordinate matrix S of the leading channel head in all high-speed images. AB ; The specific process is:

[0138] S4-1: Use MATLAB to read the first frame of high-speed image, and use the imadjust function to invert the color of the high-speed image, and read the pixel matrix H of the inverted continuous high-speed image. uv , read H uv The tip of the middle rod electrode, that is, the bottom pixel of the rod electrode, is located in the row number u1 and the intersection position of the rod electrode vertically downward and the ground plate electrode is located in the row number u2; calculate the spatial resolution R of the high-speed image h :

[0139] R h =D / (u1-u2);

[0140] Read H uv In the first row, the number of columns with all 0 elements is h p , p = 1, 2, 3…q; calculate H uv In the first row, all 0 elements in H uv The average value h1 of the column number:

[0141]

[0142] Continue reading H uv The second row, the third row, etc. until H is calculated uv The column average of the 0 elements in all rows constitutes the position information matrix H of the center of the leading channel in the image taken by the high-speed camera. A :

[0143]

[0144] Set (1, h1) as the origin of the xz coordinate system and obtain the pixel coordinate H of the leading channel in the xz coordinate system. A ':

[0145]

[0146] The pixel coordinate H A 'Convert to actual space xz coordinates H A ", the conversion formula is:

[0147] H A =H A ′·R h ;

[0148] Specifically:

[0149]

[0150] Thus, the actual two-dimensional xz space icon (h u -h1)·R h , (u-1)·R h );

[0151] S4-2: Search the third column of matrix AB for the value that matches (u-1)·R h The xyz coordinates of the row represent the three-dimensional spatial coordinates of the leader head in the frame image.

[0152] S4-3: Continue to read the second and third high-speed images, and perform the operations of S4-1 and S4-2 until the three-dimensional xyz coordinate matrix S of the leading channel head in all high-speed images is obtained. AB :

[0153]

[0154] Calculation module: used to calculate the time difference Δt between two frames of high-speed images, the calculation formula is: Δt = 1 / FPS; calculate the distance matrix Δd of the leader head moving in the actual three-dimensional space between two frames of high-speed images, the calculation formula is:

[0155]

[0156] Specific:

[0157]

[0158] Calculate the velocity matrix v of the leader head moving in the actual three-dimensional space between two frames of high-speed images T , the calculation formula is:

[0159]

[0160] In this embodiment, a static image A of the leader discharge breakdown channel in the xz coordinate system and a static image B of the leader discharge breakdown channel in the yz coordinate system are first obtained by using a single-lens reflex camera of the shooting module. After processing the two static images using MATLAB software, the xyz coordinate matrix A of the leader breakdown channel in the actual space is obtained using the modeling module. B; Use the discharge channel generation module to generate the leading discharge channel, use the high-speed camera of the shooting module to obtain the two-dimensional xz space coordinates, and then use the retrieval module to retrieve and generate the three-dimensional space xyz coordinate matrix S of the leading channel head in all high-speed images AB Finally, the calculation module is used to calculate the time difference Δt between the two frames of high-speed images, the distance matrix Δd of the leading head moving in the actual three-dimensional space between the two frames of high-speed images, and the velocity matrix v T That is, this embodiment realizes the accurate inversion of the three-dimensional space of the pilot channel through the operation and mutual cooperation of the five modules, and solves the problem that the error caused by the different triggering and triggering uncertainty of the two high-speed cameras is solved.

[0161] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for quantitatively calculating the three-dimensional spatial velocity of a pilot channel, characterized in that: The following steps are involved: S1: The rod electrode is perpendicular to the ground plate electrode. The gap between the rod electrode and the ground plate electrode is used as the axis. SLR camera A and SLR camera B are arranged orthogonally. The shooting directions of SLR camera A and SLR camera B are parallel to the horizontal plane. The high-speed camera is placed at SLR camera A and has the same shooting direction as SLR camera A. S2: SLR camera A and SLR camera B are controlled by computer to shoot, and static image A in xz coordinate system and static image B in yz coordinate system are obtained; modeling is performed to obtain xyz coordinate matrix A of the pilot channel in actual space B ; S3: The impulse voltage generator generates a positive impulse voltage and applies it to the rod electrode, generating a pilot discharge channel between the rod electrode and the grounding plate electrode; when the voltage signal received by the oscilloscope reaches the trigger level, it outputs a trigger signal to control the high-speed camera to shoot the pilot discharge channel in the continuous time domain; S4: According to the xyz coordinate matrix A of the pilot channel in the actual space B The leading discharge channel photographed by the high-speed camera is used to obtain the three-dimensional xyz coordinate matrix S of the leading channel head in all high-speed images. AB ; S5: Calculate the time difference Δt between two frames of high-speed images; then calculate the distance matrix Δd of the leading head moving in the actual three-dimensional space between the two frames of high-speed images, and finally calculate the velocity matrix v of the leading head moving in the actual three-dimensional space between the two frames of high-speed images. T .

2. A method for quantitatively calculating the three-dimensional space velocity of a pilot channel according to claim 1, characterized in that: In step S1, SLR camera A and SLR camera B are both placed 4 to 5 meters away from the rod electrode.

3. A method for quantitatively calculating the three-dimensional space velocity of a pilot channel according to claim 1, characterized in that: The modeling process in step S2 includes the following steps: S2-1: Read static image A and static image B, and obtain the position information matrix C of the center of the leading channel in the image taken by SLR camera A according to static image A. A , and static image B to obtain the position information matrix D of the center of the pilot channel in the image taken by SLR camera B B ; Use the interp1 interpolation function in MATLAB to interpolate C A and D B Interpolate to make the two have the same number of rows Z and get the new position information matrix C A ' and D B '; S2-2: C A 'The first element of is used as the origin of the xz coordinate system to obtain the pixel coordinate C of the leading channel in the xz coordinate system A ”, with D B 'The first element of is used as the origin of the yz coordinate system to obtain the pixel coordinate D of the leading channel in the yz coordinate system B ”; S2-3: Set pixel coordinates C A ”、D B " are converted into xz coordinates C in real space A ”' and D B ”'; According to the xz coordinate C in the actual space A ” and D B "Get the xyz coordinate matrix A in the actual space B .

4. A method for quantitatively calculating the three-dimensional space velocity of a pilot channel according to claim 3, characterized in that: In step S2-3, the pixel coordinate C A ”、D B "Converted to the xz coordinates C of d in real space A ”' and D B The formula for ' is: C″′ A =C A ”·R; D″′ B =D″ B ·R; In the above formula, R is the spatial resolution of the static image.

5. A method for quantitatively calculating the three-dimensional space velocity of a pilot channel according to claim 1, characterized in that: In step S3, the trigger signal is first converted into an optical signal by an electro-optical converter, and then converted into an electrical signal by an optical fiber-connected photoelectric converter, and then transmitted to the high-speed camera to control the high-speed camera to shoot.

6. A method for quantitatively calculating the three-dimensional space velocity of a pilot channel according to claim 1, characterized in that: In step S4, the three-dimensional xyz coordinate matrix S of the leading channel head in all high-speed images is obtained. AB , including the following steps: S4-1: Read the first frame of high-speed image and obtain the actual two-dimensional xz spatial coordinates of the leader head in this frame of high-speed image. S4-2: Retrieval Matrix A B The third column, that is, find the row number of the element with the same value as the second column of the xz spatial coordinate of this frame on the z axis. The xyz coordinate corresponding to this row represents the three-dimensional spatial coordinate of the leader head in this frame of image; S4-3: After completing the above steps, continue to read the next frame of high-speed image and perform the same operations as the above steps until the three-dimensional space xyz coordinate matrix S of the leading channel head in all high-speed images is obtained. AB .

7. A method for quantitatively calculating the three-dimensional space velocity of a pilot channel according to claim 1, characterized in that: In step S5, the formula for calculating the time difference Δt between two frames of high-speed images is: Δt=1 / Fps, where Fps is the shooting frequency set by the high-speed camera.

8. A method for quantitatively calculating the three-dimensional velocity of a pilot channel according to any one of claims 1 to 7, characterized in that: In step S5, the formula for calculating the distance matrix Δd of the leader head moving in the actual three-dimensional space between two frames of high-speed images is: In the above formula, Δx1 represents the change in distance on the x-axis between the first frame and the second frame of high-speed image; Δy1 represents the change in distance on the y-axis at this time; Δz1 represents the change in distance on the z-axis at this time; Δx2 represents the change in distance on the x-axis between the second and third high-speed images; Δy2 represents the change in distance on the y-axis at this time; Δz2 represents the change in distance on the z-axis at this time; Δx n-1 Indicates the change in distance on the x-axis between the nth frame and the n-1th frame of high-speed image; Δy n-1 Indicates the change in distance on the y-axis at this time; Δz n-1 Indicates the change in distance on the z-axis at this time; Calculate the velocity matrix v of the leader head moving in the actual three-dimensional space between two frames of high-speed images T The formula is: T =Δd / Δt.

9. A method for quantitatively calculating the three-dimensional space velocity of a pilot channel according to claim 3 or 6, characterized in that: Use MATLAB software to read static image A, static image B, and all high-speed images.

10. A system using the method for quantitatively calculating the three-dimensional space velocity of a pilot channel according to any one of claims 1 to 9, characterized in that: Includes the following modules; Shooting module: including a computer, an oscilloscope, a SLR camera A and a SLR camera B and a high-speed camera; when the pilot channel is in a non-discharge state, the computer controls the orthogonally placed SLR cameras A and B to shoot, and obtains a static image A in the xz coordinate system and a static image B in the yz coordinate system; when the pilot channel is in a discharge state, the oscilloscope controls the high-speed camera to shoot the pilot discharge channel in a continuous time domain; Modeling module: used to obtain the xyz coordinate matrix A of the pilot channel in the actual space based on the acquired static image A in the xz coordinate system and the static image B in the yz coordinate system B ; A discharge channel generation module: comprising an impulse voltage generator, a rod electrode and a grounding plate electrode. The impulse voltage generator is used to generate a positive polarity impulse voltage, and when the impulse voltage is applied to the rod electrode, a pilot discharge channel is generated between the rod electrode and the grounding plate electrode. Retrieval module: used to retrieve matrix A B The third column of , i.e., the number of rows on the z-axis where the element has the same value as the second column of the actual two-dimensional xz spatial coordinates of the leading head in the high-speed image, and the xyz coordinates corresponding to the row are expressed as the three-dimensional spatial coordinates of the leading head in the frame image, thereby generating the three-dimensional spatial xyz coordinate matrix S of the leading channel head in all high-speed images. AB ; Calculation module: used to calculate the time difference Δt between two frames of high-speed images, the distance matrix Δd of the leading head moving in the actual three-dimensional space between the two frames of high-speed images, and the velocity matrix v of the leading head moving in the actual three-dimensional space between the two frames of high-speed images T .

Images