CN106126884B - The measuring method and system of DC wire simulation contamination device, surface state - Google Patents

Abstract

The invention discloses a device for simulating fouling of DC conductors, a method for measuring surface conditions and a system thereof. The method comprises: using a pre-established device for simulating fouling on the surface of direct current conductors to carry out fouling on the surface of the conductor to be measured to obtain a preset volume. DC conductor samples under polluted conditions; collect the surface image of the DC conductor sample, and process the collected surface image to obtain the corresponding grayscale image; obtain the grayscale matrix according to the grayscale image, and calculate the characteristic parameters of the grayscale matrix Respectively establish the functional relationship between each characteristic parameter of the gray matrix and the corresponding pollution time, and the functional relationship between the statistical characteristic parameters and the corresponding pollution time, and then carry out scientific characterization and quantification of the surface state of the wire to be measured. Therefore, the implementation of the present invention can obtain a large number of DC conductor samples under different pollution conditions, and can realize the scientific characterization and quantification of the surface state of the DC pollution conductor.

Description

Method and system for simulating pollution accumulation device and surface state of DC wire

technical field

The invention relates to the field of electric power transmission, in particular to a device for simulating fouling of DC conductors, and a method and system for measuring the surface state of DC conductors.

Background technique

As the scale of my country's power grid continues to expand, the design and construction of new ultra-high voltage and ultra-high voltage direct current transmission lines all consider electromagnetic environment issues and are strictly controlled and implemented in accordance with power industry standards. One of the key factors for success, and the reason for the change of the electromagnetic environment of the long-term running conductor is mainly the change of the corona discharge effect on the surface of the conductor.

Among them, when the electric field intensity on the surface of the conductor exceeds a certain critical value, it will cause ionization of the surrounding air, and produce partial discharge and light emission, which is called corona discharge phenomenon. In addition to radio interference, audible noise, and corona energy loss caused by corona discharge on DC high-voltage transmission lines, the large amount of space charge generated by the discharge will also have a significant impact on the ground synthetic electric field strength and ion current. In the case of the same wire type, splitting method, installation height, and external environment, the root cause of the difference in the corona effect between the new wire and the long-term running wire is the difference in the surface state of the wire. Transmission lines are directly affected by the atmospheric environment during long-term operation. Under the long-term action of moisture and oxygen, a large amount of acid gas and solid particles discharged by industrial enterprises will undergo a series of physical and chemical reactions with the aluminum wires on the outer layer of the transmission line, causing changes in the state of the outer layer of the wires, thus directly affecting the corona discharge of the wires effect.

So, how to measure the state of the wire surface? The existing methods for measuring the surface state of wires are mainly: obtaining actual wire samples, and then using precision instruments to analyze and measure the wire samples, such as using a scanning electron microscope to observe the two-dimensional microscopic topography of the wire surface, and using three-dimensional white light interference The profiler observes the three-dimensional profile of the surface of the wire.

However, the inventors of the present invention have found through research that there are two main problems in using the above method to observe the surface state of the wire:

1) First of all, it is necessary to obtain actual wire samples by using a scanning electron microscope to observe the two-dimensional microscopic topography of the wire surface and by using a three-dimensional white light interferometer to observe the three-dimensional profile of the wire surface. The time is short. For the DC transmission lines that are running or will be put into operation, it is temporarily impossible to obtain the DC conductor samples of the actual operating lines; even if there are DC conductor samples that can be collected, it still needs to consume a lot of manpower, material and time. difficult to achieve.

2) Secondly, using the above method to analyze and measure the wire sample generally only obtains a qualitative and intuitive description of the wire sample, and cannot scientifically and quantitatively characterize the surface state of the wire.

Contents of the invention

In view of this, the present invention proposes a device for simulating fouling of DC wires and a method and system for measuring the surface state of DC wires, which can obtain a large number of samples of DC wires under different fouling conditions, and can realize the measurement of the surface state of DC wires. scientific characterization and quantification.

Further speaking, the method for measuring the surface state of a DC wire of the present invention includes: using a pre-established DC wire surface simulation device for fouling, collecting dirt on the surface of the wire to be measured, and obtaining samples of the DC wire under preset pollution accumulation conditions; collecting The surface image of the DC wire sample, and processing the collected surface image to obtain a corresponding grayscale image; obtain a grayscale matrix according to the grayscale image, and calculate the characteristic parameters of the grayscale matrix; respectively establish The functional relationship between each characteristic parameter of the grayscale matrix and the corresponding pollution time; carry out weighted calculation on each characteristic parameter of the calculated grayscale matrix to obtain the overall statistical characteristic parameter, and establish the statistical characteristic parameter and The functional relationship of the corresponding pollution time; according to the obtained functional relationship between each characteristic parameter value and the statistical characteristic parameter and the corresponding pollution time, scientifically characterize and quantify the surface state of the wire to be tested.

Optionally, in some embodiments, the method for measuring the surface state of the DC conductor further includes: according to the obtained functional relationship between each characteristic parameter value and the corresponding fouling time, and the statistical characteristic parameter and the corresponding fouling time To predict the surface state of the actual running DC wire; and/or, to establish the functional relationship between the value of each characteristic parameter and the statistical characteristic parameter and the applied voltage of the wire and the concentration of particulate matter, which are used to predict the state of the wire to be tested. Surface states are scientifically characterized and quantified.

Optionally, in some embodiments, the processing the collected surface image and obtaining the corresponding grayscale image includes: using a digital image processing tool to extract grayscale information in the surface image; according to the grayscale degree information, convert the surface image into a grayscale image.

Optionally, in some embodiments, the obtaining a grayscale matrix according to the grayscale image, and calculating the characteristic parameters of the grayscale matrix includes: performing image removal on the grayscale image by using a neighborhood averaging method. dry processing; the grayscale image after digital processing and image denoising is expressed as a grayscale matrix composed of pixel grayscale values; based on the obtained grayscale matrix G, multiple characteristic parameters are obtained to reflect the Quantitatively describe the texture features of the information in the image; wherein, the plurality of feature parameters include but are not limited to the following five: 1) variance: when calculating, the grayscale matrix is converted into a column vector, and then the column elements are obtained. The standard deviation value of all elements in the matrix is used to describe the degree of variation or dispersion of all data in the matrix; 2) energy: it is the sum of the squares of each element in the grayscale matrix, which is used to reflect the uniformity and degree of grayscale distribution of the image The roughness of the texture; 3) Contrast: It is the moment of inertia about the diagonal in the gray matrix, which is used to reflect the distribution of matrix values, and the value of contrast represents the depth of the image texture; 4) Correlation: It is a measure of the gray matrix Parameters of similarity in a certain direction; 5) Entropy: a measurement parameter of the randomness of image content, used to measure the amount of image information, and the numerical value of entropy reflects the complexity of image texture.

Optionally, in some embodiments, the functional relationship between each characteristic parameter and fouling time includes:

1) The variance F ₁ and the pollution time t have an approximate exponential rise relationship, which is expressed as:

Among them, A ₁ , B ₁ , and K ₁ are constants, the value range of A ₁ is 2.88-3.66, the value range of B ₁ is 400-420, and the value range of K ₁ is 1300-1500;

2) The energy F ₂ has an approximately linear rising relationship with the pollution time t, which can be expressed as:

F ₂ =A ₂ t+B ₂

Among them, A ₂ and B ₂ are constants, the value range of A ₂ is 0.07-0.12, and the value range of B ₂ is 0.34-0.41;

3) Contrast ratio F ₃ has an approximately linear rising relationship with pollution time t, which is expressed as:

F ₃ =A ₃ t+B ₃

Among them, A ₃ and B ₃ are constants, the value range of A ₃ is 0.03-0.11, and the value range of B ₃ is 0.02-0.11;

4) The correlation F ₄ and the pollution time t show an approximate exponential decline relationship, which is expressed as:

Among them, A ₄ , B ₄ , and K ₄ are constants, the value range of A ₄ is 3.87-4.25, the value range of B ₄ is 2.06-3.19, and the value range of K ₄ is 10.82-12.19;

5) The entropy F ₅ has an approximately linear rising relationship with the pollution time t, which is expressed as:

F ₅ =A ₅ t+B ₅

Wherein, A ₅ and B ₅ are constants, the value range of A ₅ is 0.09-0.18, and the value range of B ₅ is 0.63-0.74.

Optionally, in some embodiments, the functional relationship between the global statistical feature parameter W used to reflect the overall information of the image and each feature parameter F _i is:

Wherein, F _i is each characteristic parameter obtained, μ _i is the weight of the image information reflected by each characteristic parameter in the whole information. The value range of F _i is 860-1240, and the value range of μ _i is 0.20-0.90.

On the other hand, the present invention also proposes a dc wire simulation fouling device, which includes:

A high-voltage DC power supply is connected to one end of the wire to be tested through a high-voltage cable;

The plexiglass cover is set on the electrode of the grounded aluminum plate to form a closed space; in the closed space, the electrode of the grounded aluminum plate is provided with a pollution particle generating device for simulating the actual operating environment of the outdoor wire; the grounded aluminum plate The electrode and the wire to be tested together form an electrode structure of a single wire to the ground;

Insulating pillars are arranged at both ends of the plexiglass cover, and the centers of the left and right end faces of the plexiglass cover are provided with through holes for the wires to be tested to pass through;

Wherein, the wires to be tested are erected horizontally at the left and right ends of the plexiglass cover, and the wires to be tested are supported by the insulating pillars, and the two ends of the wires to be tested are equipped with voltage equalizers for preventing end discharge. ball.

Optionally, in some embodiments, the voltage regulation range of the high-voltage direct current power supply is: 0~±120kV; and/or, the plexiglass cover is made of a 10mm thick plexiglass plate detachable on six sides It consists of a gasket used to ensure the airtightness of the glass cover at the junction of each surface; the left and right sides of the plexiglass cover have an opening at the center for passing the wire to be tested; and/or, the to-be-tested The measuring wire is a smooth reinforced cylindrical wire or a steel-cored aluminum stranded wire; the insulating support is a cylinder made of epoxy resin; and/or, the pollution particle generating device is approximately cylindrical with an open upper end for A variety of dirt accumulation particles are generated, and the dirt accumulation particles are diffused uniformly in the plexiglass cover; the dirt accumulation particles include: smoke, dust, kaolin, diatomaceous earth and carbon powder.

In addition, in order to realize the above method, the present invention also proposes a measurement system for the surface state of the DC conductor, which includes:

Any one of the above-mentioned DC wire simulation fouling devices is used for fouling the surface of the wire to be tested according to different fouling conditions;

An image acquisition device, configured to acquire a surface image of the DC wire sample;

An image processing device, configured to process the collected surface image to obtain a corresponding grayscale image;

A computing device, used to obtain a grayscale matrix according to the grayscale image, and calculate the characteristic parameters of the grayscale matrix; and also used to respectively establish the functional relationship between each characteristic parameter of the grayscale matrix and the corresponding pollution time ; and performing weighted calculations on each characteristic parameter of the calculated grayscale matrix to obtain an overall statistical characteristic parameter, and establishing a functional relationship between the statistical characteristic parameter and the corresponding pollution time;

The quantitative characterization device is used to scientifically characterize and quantify the surface state of the wire to be tested according to the obtained functional relationship between each characteristic parameter value and the statistical characteristic parameter and the corresponding pollution time.

Optionally, in some embodiments, the above-mentioned measurement system for the surface state of the DC conductor further includes: a predicting device, used for obtaining the functional relationship between each characteristic parameter value and the corresponding pollution time, and the statistical characteristic parameter and Corresponding functional relationship of fouling time to predict the surface state of the actual running DC wire; and/or, the calculation device is also used to establish the values of each characteristic parameter and the statistical characteristic parameter and the applied voltage of the wire and the particle concentration The functional relationship is used to scientifically characterize and quantify the surface state of the wire to be tested.

Compared with the prior art, each embodiment of the present invention has the following advantages:

After adopting the technical scheme of the embodiment of the present invention, a large number of DC wire samples under different pollution conditions can be obtained through an artificially simulated pollution accumulation device designed in the present invention with controllable environmental conditions, pollution particle composition, concentration, etc., The problem of being unable to obtain actual DC wire samples in the prior art is solved.

In addition, by obtaining DC wire samples under different pollution conditions, the surface image of the DC wire sample is further obtained, and then the surface image of the DC wire sample is processed, and the corresponding grayscale image is obtained by image processing methods. According to the obtained grayscale The corresponding gray matrix is obtained from the image, and the characteristic parameters of the gray matrix are calculated, and the functional relationship between each characteristic parameter and statistical characteristic parameters of the gray matrix and the pollution time is established, so as to realize the scientific analysis of the surface state of the DC pollution conductor. Characterization and quantification.

More features and advantages of the embodiments of the present invention will be described in the following specific implementation manners.

Description of drawings

The drawings constituting a part of the embodiments of the present invention are used to provide a further understanding of the embodiments of the present invention, and the schematic embodiments of the present invention and their descriptions are used to explain the present invention, and do not constitute improper limitations to the present invention. In the attached picture:

FIG. 1 is a schematic flow chart of a method for measuring the surface state of a DC conductor proposed in an embodiment of the present invention;

Fig. 2 is a schematic diagram of the composition of a dc wire simulated fouling device proposed by an embodiment of the present invention.

Explanation of reference signs

1 High voltage DC power supply

2 plexiglass cover

3 wires to be tested

4 Ground aluminum plate electrodes

5 equalizing balls

6 insulating posts

7 Fouling particle generating device

8 High voltage cables

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

It should be noted that, in the case of no conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

Below in conjunction with accompanying drawing, each embodiment of the present invention is described further:

The embodiment of the present invention designs a device for simulating fouling for DC wires, which is an artificially simulated fouling device with controllable environmental conditions, fouling particle composition, concentration, etc. The test of the influence of factors on the surface state of the conductor can obtain the sample after contamination equivalent to the surface of the actual DC conductor under the condition that the actual DC conductor sample cannot be obtained. Moreover, the embodiment of the present invention also proposes a method and system for measuring the surface state of DC conductors, which can further obtain surface images of corresponding conductor samples according to the obtained DC conductor samples under different pollution conditions, and use image processing methods to obtain samples Multiple characteristic parameters of the surface image, so as to realize the scientific and quantitative characterization of the surface state of the DC wire.

method embodiment

Referring to FIG. 1 , it is a schematic flowchart of a method for measuring the surface state of a DC conductor proposed by an embodiment of the present invention. In this embodiment, the method for measuring the surface state of the DC conductor includes the following steps:

S102: Use a pre-established DC wire surface simulation device to accumulate contamination on the surface of the wire to be tested, and obtain DC wire samples under different preset contamination conditions;

S104: Collect a surface image of the DC wire sample, and process the collected surface image to obtain a corresponding grayscale image;

S106: Obtain a grayscale matrix according to the grayscale image, and calculate characteristic parameters of the grayscale matrix;

S108: Establish the functional relationship between each characteristic parameter of the gray scale matrix and the corresponding pollution time;

S110: Perform weighted calculation on each characteristic parameter of the calculated gray scale matrix to obtain the overall statistical characteristic parameter, and establish a functional relationship between the statistical characteristic parameter and the corresponding pollution time;

S112: Scientifically characterize and quantify the surface state of the wire to be tested according to the obtained functional relationship between each characteristic parameter value and the statistical characteristic parameter and the corresponding pollution time.

Optionally, the above embodiment can also be used to scientifically characterize and quantify the surface state of the wire to be tested by establishing the functional relationship between each characteristic parameter value and statistical characteristic parameter, the voltage applied to the wire, the particle concentration, etc.

In the above-mentioned embodiment, a large number of samples of DC conductors under different pollution conditions can be obtained by using the pre-established DC conductor surface simulation device for fouling, which solves the problem that the actual DC conductor samples cannot be obtained in the prior art; in addition, compared to the available In terms of actual direct current conductor samples obtained, the sample acquisition method in the above embodiment saves a lot of manpower, material resources and financial resources. In addition, by establishing the functional relationship between the characteristic parameters of the surface image of the DC polluted conductor and the fouling time, the scientific characterization and quantification of the surface state of the DC polluted conductor can be realized.

It should be noted that, in the above-mentioned embodiments, experiments can be carried out on the DC wire samples under different pollution time, therefore, according to the experimental conditions, the range of the pollution time can be set to 0-10 hours, for example, it can be 0, 0.5 , 1, 2, 3, 4 hours.

As an optional implementation, the method for measuring the surface state of the DC conductor may also include the following processing steps:

S114: According to the obtained functional relationship between each characteristic parameter value and the corresponding fouling time, and the functional relationship between the statistical characteristic parameters and the corresponding fouling time, predict the surface state of the actually running DC conductor.

Therefore, the above-mentioned embodiment can predict the surface state of the DC conductor in actual operation by using the established functional relationship between each characteristic parameter value and the corresponding fouling time, and the functional relationship between the statistical characteristic parameter and the corresponding fouling time, so that The structure of the transmission wire can be optimized to meet the requirements of the electromagnetic environment of the transmission line.

As an optional implementation, in the above embodiments, the obtained DC wire sample can be scanned by scanning electron microscope to obtain a two-dimensional microscopic image of the DC wire sample, that is, a surface image of the DC wire sample. It should be pointed out that in the above-mentioned embodiment S104, processing the collected surface image and obtaining the corresponding grayscale image includes the following processing methods:

S1041: Using a digital image processing tool to extract grayscale information in the surface image;

S1042: Convert the surface image into a grayscale image according to the grayscale information.

The image processing conversion process will be further explained in conjunction with an example below:

For example, it should be noted that an image can be defined as a two-dimensional function f(x,y), where x and y are spatial coordinates, and the magnitude at any coordinate (x,y) is called the image in this The brightness of a location. Grayscale is generally the term used to represent the brightness of black and white images, and color images are formed by combining individual images. Among them, the more widely used images are RGB images, also known as true color images, which use the combination of three primary colors of red (R), green (G), and blue (B) to express the color of each pixel, while grayscale images The pixels in the middle only have light and dark information, expressed as brightness or gray level (gray level). A grayscale image is an image with only intensity information but no color information. Each element value in the matrix represents a different brightness or gray level. For example, the gray level is 0, which means black, and the gray level is 255, which means white. Here, digital image processing software (such as Matlab, etc.) can be used to realize image type conversion.

Here, the conversion method that can be used is: the RGB image is saved in Matlab as a three-dimensional data matrix X of m×n×3, and the storage matrix after conversion into a grayscale image is G. The algorithm is as follows:

f:g _i,j ＝0.31x _i,j,1 +0.59x _i,j,2 +0.11x _i,j,3

Therefore, the above-mentioned surface image of the DC wire can be processed into a grayscale image through the above-mentioned image processing, so as to perform subsequent calculations.

As an optional implementation, in the above S106: obtaining the grayscale matrix according to the grayscale image, and calculating the characteristic parameters of the grayscale matrix may further include the following processing procedures of S1061-S1063:

S1061: Perform image de-drying processing on the grayscale image by using a neighborhood averaging method.

Since digital images are affected by external environmental noise during digitization and transmission, such images are called noise images, and the process of reducing noise in digital images is called image denoising.

In this step, the method of image denoising can adopt the neighborhood average method. The principle of neighborhood average method denoising is to add the gray value of a certain pixel in the original image and the gray value of adjacent pixels around it, and then calculate The average value is used as the gray value of the pixel in the processed image. Using the neighborhood averaging method to denoise can obviously weaken the noise point, make the gray level in the neighborhood relatively uniform, and achieve the effect of smoothing the gray level. Among them, the mathematical expression of neighborhood averaging method denoising is:

Among them, S is the neighborhood of (x, y) determined in advance, and M is the total number of pixels contained in the neighborhood S.

S1062: Represent the grayscale image after digital processing and image denoising as a grayscale matrix composed of pixel grayscale values.

It should be noted that a digital image is a discretized image composed of a series of image points, each point is called a pixel, and the size of a pixel is determined by the resolution of the image. Grayscale is the brightness of a pixel, which is used to represent the degree of distinction between black and white image pixels. The grayscale image after digital processing and image denoising can be expressed as a matrix composed of pixel grayscale values called grayscale matrix G.

In this step, the gray matrix G with gray level L can be expressed as:

S1063: Based on the obtained grayscale matrix G, obtain a plurality of feature parameters, which are used to reflect texture features for quantitatively describing information in the image.

It should be noted that since the texture features of the image describe the recurring local patterns and their arrangement rules in the image, which reflect some rules of grayscale changes in the macro sense, the image can be regarded as a combination of different texture regions. It is a measure of the relationship between pixels in a local area, and texture features can be used to quantitatively describe the information in an image. There must be a certain grayscale relationship between two pixels separated by a certain distance in the image space, which is called the spatial correlation characteristic of the grayscale in the image, and the texture is described by studying the spatial correlation of the grayscale. Practice has proved that the gray value matrix has a very strong vitality in the statistical method, and the texture features extracted by this method have good discrimination ability.

In this step, the grayscale matrix of the surface image of the wire reflects the roughness of the wire surface to a certain extent, that is, the surface position corresponding to a large (bright) grayscale value is convex, and the larger the value, the higher the convexity; otherwise, A small (dark) grayscale value corresponds to a concave surface position, and the smaller the value, the deeper the depression. Therefore, multiple feature parameters are defined based on the obtained grayscale matrix G to reflect the texture features of the image, and five of them can be selected: variance, energy, contrast, correlation, and entropy. The expression of each feature parameter and the meaning of the texture feature represented are as follows:

1) Variance F ₁ :

Where m is the mean value of each element of Q(i,j).

When calculating, the grayscale matrix is converted into a column vector, and then the column element, that is, the standard deviation value of all elements in the matrix, is obtained to describe the degree of variation or dispersion of all data in the matrix. The more uneven the grayscale of the image, the greater the dispersion of the data in the average grayscale matrix, and the greater the variance; on the contrary, the more uniform the grayscale of the image, the smaller the variance.

2) Energy F ₂ :

The energy _F2 is the sum of the squares of each element in the grayscale matrix, which is used to reflect the uniformity of the image grayscale distribution and the roughness of the texture. If the values of each element in the matrix are equal, then F ₂ is small and the texture is fine; if the element values in the matrix differ greatly, then F ₂ is large and the texture is rough.

3) Contrast F ₃ :

Contrast _F3 is the moment of inertia about the diagonal in the grayscale matrix, which is used to reflect the distribution of matrix values, and the value of contrast represents the depth of image texture. For example, from a mathematical point of view, the more elements in the matrix away from the diagonal, the larger the value, and because the value of (ij) ² is large, the value of F ₃ is also larger. A large value of F ₃ means that the groove of the texture is deep and the contrast is large.

4) Correlation F ₄ :

in:

Correlation F ₄ is a parameter to measure the similarity of the gray matrix in a certain direction. If the values of the elements in the matrix are evenly equal, the correlation value is large; on the contrary, if the elements in the matrix are very different, the correlation value is small. Corresponding to the image, if there is a texture in the vertical direction in the image, the correlation value of the vertical direction matrix is greater than that of other direction matrices; on the contrary, if the image has no texture in the horizontal direction and the gray level is uniform, the horizontal direction matrix The matrix correlation values are small.

5) Entropy F ₅ :

Entropy _F5 is a measure parameter of the randomness of image content, which is used to measure the amount of image information, and the numerical value of entropy _F5 reflects the complexity of image texture. For example, when the randomness of the image content is large, the elements in the gray matrix are scattered and almost all values are equal, the entropy is very large; on the contrary, if the image does not have any texture, the gray matrix is almost zero, and the entropy is very small. Therefore, if the image texture is complex, the entropy value will be large; if the image gray level is uniform, the entropy value will be small.

As an optional implementation, in the above-mentioned embodiment S108, after processing a large number of experimental wire samples, the functional relationship between each characteristic parameter and the pollution time is obtained, including:

1) The variance F ₁ and the pollution time t have an approximate exponential rise relationship, which is expressed as:

Wherein, A ₁ , B ₁ , and K ₁ are constants, the value range of A ₁ is 2.88-3.66, the value range of B ₁ is 400-420, and the value range of K ₁ is 1300-1500.

2) The energy F ₂ has an approximately linear rising relationship with the pollution time t, which can be expressed as:

F ₂ =A ₂ t+B ₂

Wherein, A ₂ and B ₂ are constants, the value range of A ₂ is 0.07-0.12, and the value range of B ₂ is 0.34-0.41.

3) Contrast ratio F ₃ has an approximately linear rising relationship with pollution time t, which is expressed as:

F ₃ =A ₃ t+B ₃

Wherein, A ₃ and B ₃ are constants, the value range of A ₃ is 0.03-0.11, and the value range of B ₃ is 0.02-0.11.

4) The correlation F ₄ and the pollution time t show an approximate exponential decline relationship, which is expressed as:

Among them, A ₄ , B ₄ , and K ₄ are constants, the value range of A ₄ is 3.87-4.25, the value range of B ₄ is 2.06-3.19, and the value range of K ₄ is 10.82-12.19.

5) The entropy F ₅ has an approximately linear rising relationship with the pollution time t, which is expressed as:

F ₅ =A ₅ t+B ₅

Wherein, A ₅ and B ₅ are constants, the value range of A ₅ is 0.09-0.18, and the value range of B ₅ is 0.63-0.74.

Since each feature parameter reflects certain information of the image from different aspects, after obtaining various local information, it is necessary to establish the global statistical feature parameter W and the functional relationship between the statistical feature parameter W and the pollution time t, which is used to Reflect the overall information of the image.

Therefore, as an optional implementation manner, in the above embodiment S110, the functional relationship between the global statistical feature parameter W used to reflect the overall information of the image and each feature parameter F _i is:

Wherein, F _i is each characteristic parameter obtained, μ _i is the weight of the image information reflected by each characteristic parameter in the whole information. The value range of F _i is 860-1240, and the value range of μ _i is 0.20-0.90.

It can be seen that the relationship between the characteristic parameters under different fouling conditions and the fouling time, applied voltage, particle concentration, etc. can be obtained through the above-mentioned embodiments. Moreover, in terms of application range, the method of image characterization can also be used in other materials, not only wires, and the application range is relatively wide, which is not limited in the present invention.

For the materials contained in the direct current transmission network in the electric power field, there are metal materials (such as line fittings) and insulating materials (such as line insulators). The state changes, and the application of the image processing method in this patent can realize the scientific characterization and quantification of different surface states before and after fouling.

In summary, based on the foregoing embodiments, it can be seen that the present invention has the following advantages:

First of all, the present invention designs an artificially simulated fouling device with controllable environmental conditions, fouling particle composition, concentration, etc., which can obtain equivalent fouled samples under the condition that actual DC wire samples cannot be obtained. Furthermore, it is possible to flexibly measure the influence of various external factors (including: different applied voltages on the wires, the time of contamination on the wires, the types of dirt particles, etc.) on the surface state of the wires.

Secondly, by obtaining DC wire samples under different pollution conditions, the surface image of the DC wire sample is further obtained, and then the surface image of the DC wire sample is processed, and the corresponding grayscale image is obtained by using the image processing method. According to the obtained grayscale The corresponding grayscale matrix is obtained from the image, and the characteristic parameters of the grayscale matrix are calculated, and the functional relationship between each characteristic parameter of the grayscale matrix and the pollution time is established, so as to realize the scientific and quantitative characterization of the surface state of the DC conductor. In addition, each feature parameter can be weighted and calculated to obtain the functional relationship between the statistical feature parameters reflecting the overall information of the image and the pollution time, so as to realize the scientific characterization and quantification of the surface state of the DC conductor at different pollution times.

It should be noted that, for the foregoing method embodiments, for the sake of simple description, they are expressed as a series of action combinations, but those skilled in the art should know that the present invention is not limited by the described action sequence, because Certain steps may be performed in other orders or simultaneously in accordance with the present invention. Secondly, those skilled in the art should also know that the embodiments described in the specification are all preferred embodiments, and the actions involved are not necessarily required by the present invention.

Device embodiment

Embodiment one:

Referring to FIG. 2 , it is a schematic diagram of the composition of a dc wire simulated fouling device proposed in this embodiment. In this embodiment, the DC wire simulation device includes the following components: a high-voltage DC power supply 1, a plexiglass cover 2, a wire to be tested 3, a grounded aluminum plate electrode 4, a pressure equalizing ball 5, an insulating support 6, and a pollution particle generating device 7, and high voltage cables 8. Wherein, the high-voltage DC power supply 1 is connected to one end of the wire 3 to be tested through a high-voltage cable 8 . The plexiglass cover 2 is covered on the grounded aluminum plate electrode 4 to form a closed space. In the confined space, the grounded aluminum plate electrode 4 is provided with a pollution particle generating device 7 for simulating the actual operating environment of the outdoor wire. The grounded aluminum plate electrode 4 and the lead wire 3 to be tested together form an electrode structure of a single wire to the ground. The insulating pillars 6 are arranged at both ends of the plexiglass cover 2, and the centers of the left and right end faces of the plexiglass cover 2 are provided with through holes for passing the wires 3 to be tested. Wherein, the lead wire 3 to be tested is erected horizontally at the left and right ends of the plexiglass cover 2, and the lead wire 3 to be tested is supported by insulating pillars 6, and the two ends of the lead wire 3 to be tested are provided with equalizing balls 5 for preventing end discharge.

Optionally, in the above embodiment, the high-voltage DC power supply 1 is used to apply a high-voltage DC voltage to the wire, so that a high-voltage electric field is generated in the space around the wire, and the voltage adjustment range is 0~±120kV.

Optionally, the plexiglass cover 2 is composed of a plexiglass plate with a thickness of 10 mm that can be detached on six sides, and gaskets for ensuring the airtightness of the glass cover are installed at the joints of each surface. The overall size of the plexiglass cover 2 can be 2×1×1m, and the left and right sides of the plexiglass cover 2 have openings at the center for passing the wire 3 to be tested.

The lead wire 3 to be tested is erected horizontally at the central opening position of the left and right sides of the plexiglass cover, supported by two insulating pillars 6 made of epoxy resin at both ends, and the equalizing ball 5 is set at both ends of the lead wire for To prevent discharge at the end, a section of the wire is connected to the high-voltage DC power supply 1 through a high-voltage cable 8 . The wire 3 to be tested can be a smooth reinforced cylindrical wire, or a steel-cored aluminum stranded wire.

The grounded aluminum plate electrode 4 is placed on the bottom surface of the plexiglass cover, and together with the wire 3 to be tested constitutes a single-wire-to-ground electrode structure.

The dirt particle generating device 7 is made of insulating and high-temperature-resistant material, approximately cylindrical, with an open upper end, used to generate various dirt particles, and make the dirt particles diffuse evenly in the plexiglass cover 2 . Contamination particles include: soot, dust, kaolin, diatomaceous earth, and toner.

It should be noted that, in the above-mentioned embodiment, experiments can be carried out on samples of DC wires under different pollution accumulation times. Considering that the DC power supply cannot be operated with electricity for a long time, a range is set for the pollution accumulation time t in the test, which can be 0-10 hours, which is determined by the experimental conditions and experimental equipment, for example, the fouling time can be 0, 0.5, 1, 2, 3, 4 hours.

Embodiment two:

In order to realize the above-mentioned embodiment of the method for measuring the surface state of the DC conductor, this embodiment proposes a measurement system for the surface state of the DC conductor, which includes:

The dc conductor analog pollution accumulating device described in the foregoing embodiment 1 is used for accumulating contamination on the surface of the conductor to be measured according to different accumulating conditions;

An image acquisition device, configured to acquire a surface image of the DC wire sample;

An image processing device, configured to process the collected surface image to obtain a corresponding grayscale image;

The calculation device is used to obtain the grayscale matrix according to the grayscale image, and calculate the characteristic parameters of the grayscale matrix; it is also used to respectively establish the functional relationship between each characteristic parameter of the grayscale matrix and the corresponding pollution time; and to calculate Each characteristic parameter of the obtained gray scale matrix is weighted and calculated to obtain the overall statistical characteristic parameter, and the functional relationship between the statistical characteristic parameter and the corresponding pollution time is established;

The quantitative characterization device is used to scientifically characterize and quantify the surface state of the wire to be tested according to the obtained functional relationship between each characteristic parameter value and the statistical characteristic parameter and the corresponding pollution time.

In the above-mentioned embodiments, a large number of samples of DC conductors under different pollution conditions can be obtained by using the surface of the DC conductor to simulate the pollution accumulation device, which solves the problem that the actual DC conductor samples cannot be obtained in the prior art. Compared with the available actual DC conductor For samples, the sample acquisition method in the above embodiment saves a lot of manpower, material resources and financial resources. In addition, the image acquisition device and image processing device are used to process the collected wire samples, and the functional relationship between each characteristic parameter value and the corresponding pollution time established by the computing device and the quantitative characterization device, as well as the statistical characteristic parameters and the corresponding product The functional relationship of the pollution time can be realized to realize the scientific characterization and quantification of the surface state of the DC polluted conductor, and the surface state of the actual DC conductor can be predicted, and then the structure of the transmission conductor can be optimized to meet the requirements of the electromagnetic environment of the transmission line.

In an optional embodiment, the above-mentioned image processing device further includes:

The acquisition module is used for extracting grayscale information in the surface image by using a digital image processing tool.

The conversion module is used for converting the surface image into a grayscale image according to the grayscale information.

In an optional embodiment, the above computing device further includes:

A parameter calculation module, used to obtain a grayscale matrix according to the grayscale image, and calculate the characteristic parameters of the grayscale matrix;

The first functional relationship construction module is used to respectively establish the functional relationship between each characteristic parameter of the gray scale matrix and the corresponding pollution time;

The second functional relationship building module is used to perform weighted calculation on each characteristic parameter of the calculated gray scale matrix to obtain the overall statistical characteristic parameter, and establish a functional relationship between the statistical characteristic parameter and the corresponding pollution accumulation time.

In an optional embodiment, the above-mentioned calculation device may further include: a newly added functional relationship building module, which is used to respectively establish the functional relationship between each characteristic parameter value and statistical characteristic parameter, the applied voltage of the wire, and the particle concentration, and is used for the above-mentioned The surface state of the wire to be tested is scientifically characterized and quantified.

In an optional embodiment, the above-mentioned measuring system for the surface state of the DC conductor further includes: a predicting device, which is used to obtain the functional relationship between each characteristic parameter value and the corresponding pollution time, and the statistical characteristic parameter and the corresponding The functional relationship of the fouling time is used to predict the surface state of the DC conductor in actual operation.

Here, combined with an example, the method of using the measurement system for the surface state of the above-mentioned DC wire is further explained:

1) Before conducting the simulated pollution test, check the connection between the wire 3 to be tested and the high-voltage DC power supply 1, the grounding aluminum plate electrode 4 is correctly grounded, and the airtightness of the plexiglass cover 2, and start the test after ensuring that the installation and connection of each device are correct.

2) Utilize the pollution particle generating device 7 to generate a certain concentration of suspended particles in the air in the plexiglass cover 2. After the suspended particles are diffused evenly in the space, turn on the high-voltage DC power supply 1 and apply a certain high-voltage DC voltage U to the wire 3 to be tested. , start timing at this time to make the wire 3 under test charged and polluted for a certain time t.

3) After a certain period of time of contamination, the surface of the wire 3 to be tested has absorbed a large amount of particulate matter. Open the front panel of the plexiglass cover 2, take out the wire 3 to be tested, and intercept the wire to obtain a sample of the wire 3 to be tested.

4) Change the applied voltage U and pollution time t of the wire 3 to be tested, and repeat the experimental steps 1), 2), and 3), to obtain DC wire samples under different applied voltages and different pollution time.

5) Scanning the DC wire sample obtained above with an electron microscope to obtain a two-dimensional microscopic image of the DC wire sample.

6) Process the obtained two-dimensional microscopic image of the DC wire sample to obtain a grayscale image.

7) Obtain corresponding grayscale matrices according to the above grayscale images, and calculate characteristic parameters of each grayscale matrix.

8) Establish the functional relationship between each characteristic parameter of the gray matrix and the pollution time.

9) Perform weighted calculations on the obtained multiple characteristic parameters to obtain the overall statistical parameters, establish the functional relationship between the statistical parameters and the pollution time, and then scientifically characterize and quantify the surface state of the wire under the experimental conditions.

Therefore, the above example uses the simulated pollution device to obtain the sample after pollution equivalent to the actual environment, and then obtains the surface images of the wire samples under different pollution conditions, and uses the image processing method to obtain multiple characteristic parameters of the image, and establishes The functional relationship between the characteristic parameters and the fouling time is obtained, so as to realize the scientific and quantitative characterization of the surface state of the DC conductor.

Those skilled in the art can understand that the image representation method proposed in the above embodiments of the present invention can also be used in other metal materials, not just wires, and has a wide range of applications, and the present invention does not limit its application range. For the materials contained in the direct current transmission network in the electric power field, there are metal materials (such as line fittings) and insulating materials (such as line insulators). The state changes, and the application of the image processing method in this patent can realize the scientific characterization and quantification of different surface states before and after fouling.

It should be pointed out that the above-mentioned measurement system for the surface state of the DC conductor corresponds to the above-mentioned method for measuring the surface state of the DC conductor, and the specific implementation process can refer to the foregoing method embodiments. Since any of the above-mentioned methods for measuring the surface state of DC conductors has the above-mentioned technical effects, the measuring system for the surface state of DC conductors should also have corresponding technical effects.

Obviously, those skilled in the art should understand that each device module or each step in the measurement method of the DC conductor surface state in the above-mentioned measuring system of the DC conductor surface state of the present invention can be realized by a general computing device, and they can be concentrated in On a single computing device, or distributed on a network formed by a plurality of computing devices, optionally, they can be implemented with program codes executable by the computing device, thereby, they can be stored in a storage device to be executed by the computing device Execute, or make them into individual integrated circuit modules, or make multiple modules or steps among them into a single integrated circuit module to realize. As such, the present invention is not limited to any specific combination of hardware and software. The storage device is a non-volatile memory, such as: ROM/RAM, flash memory, magnetic disk, optical disk, etc.

The above description is only an embodiment of the present invention, and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention within.

Claims (10)

1. A method for measuring the surface state of a DC conductor, characterized in that the method comprises: Use the pre-established DC wire surface simulation device to accumulate pollution on the surface of the wire to be tested, and obtain DC wire samples under the preset pollution accumulation conditions; collecting a surface image of the DC wire sample, and processing the collected surface image to obtain a corresponding grayscale image; Obtaining a grayscale matrix according to the grayscale image, and calculating characteristic parameters of the grayscale matrix; Respectively establish the functional relationship between each characteristic parameter of the gray scale matrix and the corresponding pollution time; Carrying out weighted calculation on each characteristic parameter of the calculated gray scale matrix to obtain the overall statistical characteristic parameter, and establishing a functional relationship between the statistical characteristic parameter and the corresponding fouling time; According to the obtained functional relationship between each characteristic parameter value and the statistical characteristic parameter and the corresponding pollution time, the surface state of the wire to be tested is scientifically characterized and quantified. 2. The method for measuring the surface state of a DC conductor according to claim 1, further comprising: According to the obtained functional relationship between each characteristic parameter value and the corresponding fouling time, and the functional relationship between the statistical characteristic parameters and the corresponding fouling time, the surface state of the DC conductor in actual operation is predicted; and/or, The functional relationship between each characteristic parameter value and statistical characteristic parameter and the applied voltage of the wire and the particle concentration is respectively established, so as to scientifically characterize and quantify the surface state of the wire to be tested. 3. The method for measuring the surface state of a DC conductor according to claim 2, wherein said processing the collected surface image and obtaining a corresponding grayscale image comprises: Using a digital image processing tool to extract grayscale information in the surface image; Converting the surface image into a grayscale image according to the grayscale information. 4. The method for measuring the surface state of a DC conductor according to claim 3, wherein said obtaining a grayscale matrix according to said grayscale image, and calculating the characteristic parameters of said grayscale matrix include: Carrying out image de-drying processing on the grayscale image by adopting the neighborhood averaging method; Represent the grayscale image after digital processing and image denoising as a grayscale matrix composed of pixel grayscale values; Based on the obtained grayscale matrix G, a plurality of characteristic parameters are obtained to reflect the texture characteristics used to quantitatively describe the information in the image; wherein, the plurality of characteristic parameters include but are not limited to the following five: 1) Variance: When calculating, convert the grayscale matrix into a column vector, and then obtain the standard deviation value of the column elements, that is, all elements in the matrix, to describe the degree of variation or dispersion of all data in the matrix; 2) Energy: it is the sum of the squares of each element in the grayscale matrix, which is used to reflect the uniformity of the image grayscale distribution and the roughness of the texture; 3) Contrast: It is the moment of inertia about the diagonal in the grayscale matrix, which is used to reflect the distribution of matrix values, and the value of contrast represents the depth of image texture; 4) Correlation: It is a parameter to measure the similarity of the gray matrix in a certain direction; 5) Entropy: It is a measurement parameter of the randomness of image content, which is used to measure the amount of image information, and the numerical value of entropy reflects the complexity of image texture. 5. The method for measuring the surface state of a DC conductor according to claim 4, wherein the functional relationship between each characteristic parameter and the fouling time includes: 1) The variance F ₁ and the pollution time t have an approximate exponential rise relationship, which is expressed as: Among them, A ₁ , B ₁ , and K ₁ are constants, the value range of A ₁ is 2.88-3.66, the value range of B ₁ is 400-420, and the value range of K ₁ is 1300-1500; 2) The energy F ₂ has an approximately linear rising relationship with the pollution time t, which can be expressed as: F ₂ =A ₂ t+B ₂ Among them, A ₂ and B ₂ are constants, the value range of A ₂ is 0.07-0.12, and the value range of B ₂ is 0.34-0.41; 3) Contrast ratio F ₃ has an approximately linear rising relationship with pollution time t, which is expressed as: F ₃ =A ₃ t+B ₃ Among them, A ₃ and B ₃ are constants, the value range of A ₃ is 0.03-0.11, and the value range of B ₃ is 0.02-0.11; 4) The correlation F ₄ and the pollution time t show an approximate exponential decline relationship, which is expressed as: Among them, A ₄ , B ₄ , and K ₄ are constants, the value range of A ₄ is 3.87-4.25, the value range of B ₄ is 2.06-3.19, and the value range of K ₄ is 10.82-12.19; 5) The entropy F ₅ has an approximately linear rising relationship with the pollution time t, which is expressed as: F ₅ =A ₅ t+B ₅ Wherein, A ₅ and B ₅ are constants, the value range of A ₅ is 0.09-0.18, and the value range of B ₅ is 0.63-0.74. 6. according to the measuring method of the described direct-current wire surface state according to any one of claim 1 to 5, it is characterized in that, the function between the global statistical characteristic parameter W and each characteristic parameter _F that is used to reflect the integral information of image The relationship is: Among them, F _i is the obtained characteristic parameters, μ _i is the weight of the image information reflected by each characteristic parameter in the whole information, the value range of F _i is 860-1240, and the value range of μ _i is 0.20-0.90 . 7. A measurement system for the surface state of a DC conductor, characterized in that it comprises: The dc wire simulates the pollution accumulation device, which is used to accumulate pollution on the surface of the measured wire according to different pollution accumulation conditions; An image acquisition device, configured to acquire a surface image of the DC wire sample; An image processing device, configured to process the collected surface image to obtain a corresponding grayscale image; A computing device, used to obtain a grayscale matrix according to the grayscale image, and calculate the characteristic parameters of the grayscale matrix; and also used to respectively establish the functional relationship between each characteristic parameter of the grayscale matrix and the corresponding pollution time ; and performing weighted calculations on each characteristic parameter of the calculated grayscale matrix to obtain an overall statistical characteristic parameter, and establishing a functional relationship between the statistical characteristic parameter and the corresponding pollution time; The quantitative characterization device is used to scientifically characterize and quantify the surface state of the wire to be tested according to the obtained functional relationship between each characteristic parameter value and the statistical characteristic parameter and the corresponding pollution time. 8. The measurement system of the surface state of the DC conductor according to claim 7, further comprising: A prediction device for predicting the surface state of the actually running DC wire according to the obtained functional relationship between each characteristic parameter value and the corresponding fouling time, and the functional relationship between the statistical characteristic parameters and the corresponding fouling time; and / or, The calculation device is also used to establish the functional relationship between each characteristic parameter value and statistical characteristic parameter, the applied voltage of the wire, and the particle concentration, so as to scientifically characterize and quantify the surface state of the wire to be tested. 9. The measuring system of the surface state of the DC wire according to claim 7 or 8, wherein the dc wire simulating fouling device further comprises: A high-voltage DC power supply (1) is connected to one end of the wire to be tested (3) through a high-voltage cable (8); The plexiglass cover (2) is set on the grounded aluminum plate electrode (4) to form a closed space; in the closed space, the grounded aluminum plate electrode (4) is provided with a product for simulating the actual operating environment of the outdoor wire. A dirt particle generating device (7); the grounded aluminum plate electrode (4) and the wire to be measured (3) together form a single wire-to-ground electrode structure; Insulating pillars (6) are arranged at both ends of the plexiglass cover (2), and the centers of the left and right end faces of the plexiglass cover (2) are provided with through holes for the wires to be tested (3) to pass through ; Wherein, the wire to be tested (3) is erected horizontally at the left and right ends of the plexiglass cover (2), and the wire to be tested (3) is supported by the insulating support (6), and the wire to be tested (3) is ) are equipped with pressure equalizing balls (5) for preventing end discharge. 10. The measuring system of the surface state of the DC conductor according to claim 9, characterized in that: The voltage regulation range of the high-voltage DC power supply (1) is: 0～±120kV; and/or, The plexiglass cover (2) is made up of 10mm thick plexiglass plates detachable on six sides, and a liner for ensuring the airtightness of the glass cover is installed at the junction of each surface; the plexiglass cover (2) The left and right sides have openings at the center for passing the wires (3) to be tested; and/or, The wire to be tested (3) is a smooth reinforced cylindrical wire or a steel-reinforced aluminum stranded wire; the insulating support (6) is a cylinder made of epoxy resin; and/or, The pollution particle generating device (7) is approximately cylindrical, with an opening at the upper end, and is used to generate a variety of pollution particles, and make the pollution particles diffuse evenly in the plexiglass cover (2); the pollution particles Includes: Soot, Dust, Kaolin, Diatomaceous Earth, and Toner.