Grounding grid conductor integrity diagnosis method

Abstract

The invention discloses a grounding grid conductor integrity diagnosis method which is used for detecting a grounding grid laid in a transformer substation and identifying the health state of the grounding grid. Comprising the following steps: S1, selecting grounding grid lower leads A and B, and injecting current; s2, carrying out regional division on the earth surface region of the earth screen, and recording potential distribution and magnetic induction intensity of each coordinate point location; s3, calculating grey correlation degree coefficients epsilon e and epsilon m of the surface potential and the magnetic induction intensity of the grounding grid; s4, the ground surface potential and the magnetic induction intensity are combined, and a grounding grid integrity diagnosis index S = alpha * epsilon e + beta * epsilon m is calculated; and S5, judging the health state or the fault type of the earth screen. Compared with a traditional method, the method has the advantages that the two types of data of the grounding grid surface potential and the magnetic induction intensity are combined, the data complement each other, and the diagnosis precision is improved.

Description

Technical Field

[0001] The invention relates to the electrical field, and more particularly to a method for diagnosing the integrity of a grounding grid conductor. Background Art

[0002] Grounding grids are laid in substations to ensure the safety and reliability of the power system. The only responsibility of the grounding grid is to discharge dangerous currents into the ground in the event of lightning strikes and faults. Grounding grid materials are mostly made of copper, steel, galvanized steel, etc. Grounding grids working in wet soil conditions will cause corrosion or even breakage. Corrosion or breakage will reduce the performance of the grounding grid and directly endanger the safety of the power system and on-site workers. Therefore, it is necessary to design effective fault diagnosis technology without excavation and power outage to regularly monitor the status of the grounding grid.

[0003] There are three main types of grounding grid fault diagnosis methods: power grid method, electrochemical detection method and electromagnetic method. The power grid method is mainly suitable for diagnosing corrosion and cannot locate the breakpoint. Even if the grid is broken, the change in grounding resistance is very small. The electromagnetic method is mainly based on simulation calculation. Although these methods can diagnose faults to a certain extent, it is difficult to accurately distinguish typical fault types. Summary of the invention

[0004] In response to the above-mentioned deficiencies in the prior art, this patent proposes a grounding grid conductor diagnosis method based on a combination of surface potential distribution and electromagnetic induction data. The method first performs grayscale processing on the surface potential distribution and electromagnetic induction data, and combines the correlation coefficients of the two into a diagnostic indicator of the integrity of the grounding grid. According to the changes in the diagnostic indicator, the diagnosis of grounding grid fracture, corrosion and other conditions can be realized.

[0005] A method for diagnosing the integrity of a grounding grid conductor, the method being used to detect a grounding grid installed in a substation and identify the health status of the grounding grid; comprising:

[0006] S1, select the leads A and B under the grounding grid and inject current;

[0007] S2. Divide the surface area of ​​the ground network into regions and record the electric potential distribution and magnetic induction intensity of each coordinate point;

[0008] S3. Calculate the grey correlation coefficient ε between the surface potential of the grounding grid and the magnetic induction intensity e and ε m ;

[0009] S4. Combine the ground surface potential and magnetic induction intensity to calculate the grounding grid integrity diagnostic index S = α·ε e +β·ε m ;

[0010] S5. Determine the health status or fault type of the ground network.

[0011] The area division is to divide the ground grid surface into grids or concentric circles or rings from the center of the ground grid outwards, and mark the position coordinates.

[0012] The method for calculating the grey correlation coefficient is as follows:

[0013] 3.1 Data initialization;

[0014]

[0015] Among them, D h (k) is the historical test data of the ground grid surface potential or magnetic induction intensity D h The kth data, D t (k) is the test data of ground grid surface potential or magnetic induction intensity D t The kth data, k = 1, 2, ..., n, n is the data length;

[0016] 3.2 Calculating data association s h and t ;

[0017]

[0018] Among them, s h Indicates the correlation degree of historical test data of ground grid surface potential or magnetic induction intensity, s t Indicates the current test data correlation of the ground grid surface potential or magnetic induction intensity;

[0019] 3.3 Calculate the grey correlation coefficient ε of the ground grid surface potential or magnetic induction intensity data;

[0020] ε=(1+|s t |) / (1+|s t |+2|s t -s h |)

[0021] As above, the grey correlation coefficient ε of the surface potential and magnetic induction intensity of the grounding grid is calculated by using the electric potential and magnetic induction data respectively. e and ε m .

[0022] The combined parameter S = α·ε e +β·ε m In the figure, α and β are the gray absolute correlation between the surface potential of the grounding grid and the magnetic induction intensity, and α+β=1; α>0.5.

[0023] The ground grid health status or fault type is: ground grid breakage, ground grid corrosion, and ground grid health.

[0024] The health status or fault type of the grounding grid is judged based on the health threshold range; when S≤0.5, it is judged that the grounding grid is broken; when 0.5<S≤0.7, it is judged that the grounding grid is corroded; when S is close to 1, it is judged that the grounding grid is in a healthier state.

[0025] The present invention has the following advantages and beneficial effects:

[0026] 1. Compared with the traditional method, the present invention combines two types of data, the surface potential of the grounding grid and the magnetic induction intensity, so that the data complement each other and improve the diagnosis accuracy.

[0027] 2. In the data collection stage, the present invention utilizes the many similarities between the two methods to facilitate data combination. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The present invention is a flow chart of the ground conductor integrity diagnosis method. DETAILED DESCRIPTION

[0029] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation method of the present invention is described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the invention, so the present invention is not limited by the specific implementation disclosed below.

[0030] like Figure 1 As shown, it is a flow chart of the method of the present invention, and the specific implementation steps are as follows;

[0031] The specific implementation steps of this method are as follows:

[0032] 1. Select the lower leads A and B of the grounding grid; use A and B to inject current into the grounding grid;

[0033] 2. Divide the area and record the potential distribution and magnetic induction intensity of each coordinate point in the grounding grid surface area;

[0034] The area division is to divide the ground grid surface into grids or concentric circles or rings from the center of the ground grid outward, and mark the position coordinates;

[0035] 3. Based on the grey correlation theory, calculate the grey correlation coefficient ε between the surface potential of the grounding grid and the magnetic induction intensity e and ε m ;

[0036] Among them, the grey correlation coefficient ε is calculated according to the steps 3.1-3.3 below. e and ε m,as follows:

[0037] 3.1D h represents historical test data, D t Represents the current test data, and the data is initialized as follows:

[0038]

[0039] Among them, D h (k) is the historical test data of the ground grid surface potential or magnetic induction intensity D h The kth data, D t (k) is the test data of ground grid surface potential or magnetic induction intensity D t The kth data, k = 1, 2, ..., n, n is the data length.

[0040] 3.2 Calculation of data correlation s of ground grid surface potential or magnetic induction intensity h and t

[0041]

[0042] Among them, s h Indicates the correlation degree of historical test data of ground grid surface potential or magnetic induction intensity, s t Indicates the current test data correlation of the ground grid surface potential or magnetic induction intensity.

[0043] 3.3 Calculation of the grey correlation coefficient ε of the ground grid surface potential or magnetic induction intensity data

[0044] ε=(1+|s t |) / (1+|s t |+2|s t -s h |)

[0045] Therefore, the grey correlation coefficient ε between the surface potential and magnetic induction intensity of the grounding grid can be calculated by using the electric potential and magnetic induction data respectively. e and ε m ;

[0046] 4. Combine the ground surface potential and magnetic induction intensity to calculate the combined parameter S = α·ε e +β·ε m , S is used as a diagnostic indicator of grounding grid integrity;

[0047] Calculate the combined parameter S = α·ε e +β·ε mIn , α and β are the gray absolute correlation between the surface potential of the grounding grid and the magnetic induction intensity, and α+β = 1. Based on past experience, the surface potential will contain more information, so α>0.5 is usually selected.

[0048] 5. Determine the grounding grid status or fault type: grounding grid breakage, grounding grid corrosion, grounding grid health. When S≤0.5, it is determined that the grounding grid is broken; when 0.5<S≤0.7, it is determined that the grounding grid is corroded; when S is closer to 1 in (0.7, 1), the grounding grid is healthier.

[0049] The present invention is described above by way of example in conjunction with the accompanying drawings. Obviously, the present invention is not limited to the above embodiments, and may also have many variations. As long as various non-substantial improvements are made using the method concept and technical solution of the present invention, or the concept and technical solution of the invention are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. A method for diagnosing the integrity of a grounding grid conductor, characterized in that: The method is used to detect the grounding grid installed in the substation and identify the health status of the grounding grid; it includes: S1, select the leads A and B under the grounding grid and inject current; S2. Divide the surface area of ​​the ground network into regions and record the electric potential distribution and magnetic induction intensity of each coordinate point; S3. Calculate the grey correlation coefficient ε between the surface potential of the grounding grid and the magnetic induction intensity e and ε m ; S4. Combine the ground surface potential and magnetic induction intensity to calculate the grounding grid integrity diagnostic index S = α·ε e +β·ε m ; S5. Determine the health status or fault type of the ground network.

2. A grounding grid conductor integrity diagnosis method according to claim 1, characterized in that: The area division is to divide the ground grid surface into grids or concentric circles or rings from the center of the ground grid outwards, and mark the position coordinates.

3. A grounding grid conductor integrity diagnosis method according to claim 1, characterized in that: The method for calculating the grey correlation coefficient is as follows: 3.1 Data initialization; Among them, D h (k) is the historical test data of the ground grid surface potential or magnetic induction intensity D h The kth data, D t (k) is the test data of ground grid surface potential or magnetic induction intensity D t The kth data, k = 1, 2, ..., n, n is the data length; 3.2 Calculating data association s h and t ; Among them, s h Indicates the correlation degree of historical test data of ground grid surface potential or magnetic induction intensity, s t Indicates the current test data correlation of the ground grid surface potential or magnetic induction intensity; 3.3 Calculate the grey correlation coefficient ε of the ground grid surface potential or magnetic induction intensity data; ε=(1+|s t |) / (1+|s t |+2|s t -s h |) As above, the grey correlation coefficient ε of the surface potential and magnetic induction intensity of the grounding grid is calculated by using the electric potential and magnetic induction data respectively. e and ε m .

4. A grounding grid conductor integrity diagnosis method according to claim 1 or 3, characterized in that: The combined parameter S = α·ε e +β·ε m In the figure, α and β are the gray absolute correlation between the surface potential of the grounding grid and the magnetic induction intensity, and α+β=1; α>0.

5.

5. A method for diagnosing the integrity of a grounding grid conductor according to claim 1, characterized in that: The ground grid health status or fault type is: ground grid breakage, ground grid corrosion, and ground grid health.

6. A method for diagnosing the integrity of a grounding grid conductor according to claim 5, characterized in that: The health status or fault type of the grounding network is determined based on the health threshold range; when S≤0.5, it is determined that the grounding network is broken; When 0.5<S≤0.7, it is judged that the grounding grid is corroded; when S is close to 1, it is judged that the grounding grid is in a healthier state.

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