A method for determining the severity of thermal defects in gas-insulated switchgear

Abstract

A method for determining the severity of thermal defects in gas-insulated combination electrical appliances belongs to the field of testing. The temperature distribution of the gas-insulated combination electrical appliance casing is detected to form a temperature distribution image. The location of the maximum temperature on the outside of the casing is determined. Using this location as the starting point, radial and axial temperature zone distribution curves are obtained. The correlation coefficient between the two curves is calculated, and the severity of the thermal defects in the gas-insulated combination electrical appliance is quantitatively assessed based on the magnitude of the correlation coefficient. This method achieves a quantitative assessment of the severity of thermal defects in the gas-insulated combination electrical appliance. Furthermore, all data sources are based on the actual values ​​of on-site equipment, eliminating the need for various pre-settings and adapting to the specific structure of each on-site device, thus avoiding the drawback of inaccurate results resulting from judgments based solely on temperature values. This method provides a quantitative assessment method that is easy to operate on-site and simple to implement. It can be widely used in the fields of operation management and on-site monitoring of GIS equipment.

Description

Technical Field

[0001] The present invention belongs to the field of fault detection, and in particular relates to a method for determining the severity of thermal defects of a gas-insulated combination electrical appliance. Background Art

[0002] Gas-insulated switchgear (GIS) is subject to high voltage and high current during operation. GIS is assembled with many connection points, such as disconnectors and pot insulators. Once these connection points become loose, hot spots will appear, generating a large amount of heat and causing the casing temperature to rise.

[0003] A Chinese invention patent, with an authorization publication date of September 3, 2019 and publication number CN 108519158 B, discloses an infrared detection method for internal overheating defects in GIS equipment. The method comprises: using infrared detection equipment to collect the temperature of the GIS equipment housing in real time; using the infrared detection equipment to search for temperature peaks on the housing at preset times to determine the abnormal temperature difference of the housing; determining the abnormal temperature rise of the conductor based on the pre-calculated ratio of the temperature rise difference between the housing and the GIS equipment conductor, the normal temperature rise of the conductor, and the abnormal temperature difference of the housing; wherein the normal temperature rise of the conductor is the difference between the temperature of the conductor under normal operating conditions of the GIS equipment and the ambient temperature; and assessing the condition of the GIS equipment based on the abnormal temperature rise of the conductor. This technical solution accurately measures whether a GIS equipment has an internal overheating defect and assesses the severity of the internal overheating defect.

[0004] However, since GIS uses SF6 gas insulation, the gas's thermal conductivity is limited, causing the internal conductor hotspot temperature to rise by dozens of degrees while the outer shell temperature only rises by 1 degree. This results in the conventional method of using only the maximum outer shell temperature to be unable to effectively judge the severity of its internal thermal defects. Usually, only qualitative judgments can be made, and quantitative assessments (i.e., quantitative assessments) are difficult to make.

[0005] To address this issue, the commonly used method currently is to use finite element analysis to calculate the temperature fields inside and outside the GIS, and then invert the internal temperature distribution using the shell temperature distribution based on the calculation results. This method requires a very clear understanding of the structural parameters of the equipment, and finite element analysis is not universal. Once the equipment parameters change, remodeling is required, which is almost impossible to implement at the equipment installation site (mainly substations, distribution stations, or power supply stations). Summary of the Invention

[0006] The technical problem to be solved by this invention is to provide a method for determining the severity of thermal defects in gas-insulated combination units. This method uses on-site temperature distribution testing to calculate the correlation coefficient between the radial temperature distribution curve and the axial temperature zone distribution curve. By analyzing the magnitude and changing trend of the correlation coefficient, it conveniently implements a quantitative assessment of the severity of thermal defects in gas-insulated combination units. This avoids the inaccurate results often associated with determining based solely on temperature values, resulting in a simple and feasible quantitative assessment method that is easy to operate on-site.

[0007] The technical solution of the present invention is to provide a method for determining the severity of thermal defects of a gas-insulated switchgear, which is characterized by:

[0008] 1) Use an infrared temperature measuring device or infrared imager to detect the temperature distribution of the gas-insulated combination electrical appliance casing and form a temperature distribution image;

[0009] 2) Determine the maximum temperature position on the outside of the GIS housing;

[0010] 3) Taking the maximum temperature point on the outside of the GIS shell as the starting point, obtain the radial temperature distribution curve f1(x);

[0011] 4) Taking the maximum temperature point on the outside of the GIS shell as the starting point, obtain the temperature zone distribution curve f2(x) in the axial direction;

[0012] 5) Calculate the correlation coefficient r between the temperature distribution curve f1(x) in the radial direction and the temperature zone distribution curve f2(x) in the axial direction;

[0013] 6) The severity of thermal defects of gas-insulated combination electrical appliances is quantitatively assessed by the value of the correlation coefficient r.

[0014] Specifically, in the technical solution of the present invention, the radial direction is the direction from the top to the bottom of the circumference of the GIS shell, which is in an arc shape and the distance is L.

[0015] Specifically, in the technical solution of the present invention, the axial direction is the radial direction of the top of the GIS shell, which is in a straight line and the distance is L.

[0016] Furthermore, the correlation coefficient r ranges from 0 to 1.

[0017] The larger the value of the correlation coefficient is, the more similar the radial temperature distribution curve and the axial temperature zone distribution curve are, indicating that the thermal defect of the gas-insulated switchgear is not serious.

[0018] Alternatively, the smaller the value of the correlation coefficient is, the greater the difference between the radial temperature distribution curve and the axial temperature zone distribution curve is, and the more serious the thermal defect of the gas-insulated switchgear is.

[0019] The method for determining the severity of thermal defects of gas-insulated combination electrical appliances described in the technical solution of the present invention, on the one hand, realizes a quantitative assessment of the severity of thermal defects of gas-insulated combination electrical appliances; on the other hand, all data sources are based on the actual values ​​of the field equipment, without the need for various pre-settings, and can adapt to the specific structure of each field equipment, providing a quantitative assessment method that is easy to operate on site and simple and feasible.

[0020] The method for determining the severity of thermal defects of a gas-insulated switchgear described in the technical solution of the present invention fully utilizes the difference in the temperature distribution of the GIS shell in the axial and radial directions, uses an infrared temperature measuring device or an infrared imager to obtain the axial and radial temperature distribution curves of the GIS shell, and determines the severity of its thermal defects, thereby avoiding the disadvantage of inaccurate results caused by determining only based on the GIS shell temperature value.

[0021] Compared with the prior art, the advantages of the present invention are:

[0022] 1. The technical solution of the present invention uses on-site temperature distribution testing to calculate the correlation coefficient between the radial temperature distribution curve and the axial temperature zone distribution curve of the GIS equipment. By analyzing the magnitude and changing trend of the correlation coefficient, it is convenient to quantitatively assess the severity of thermal defects in the gas-insulated switchgear.

[0023] 2. The technical solution of the present invention fully utilizes the difference in axial and radial temperature distribution of GIS. It can conveniently use infrared imaging devices or temperature measuring devices to obtain axial and radial temperature distribution curves and judge the severity of thermal defects, avoiding the disadvantage of inaccurate results caused by judging only by temperature values.

[0024] 3. In the technical solution of the present invention, all data sources are based on the actual values ​​of the field equipment, without the need for various pre-settings, and can adapt to the specific structure of each field equipment, providing a quantitative assessment method that is easy to operate on site and simple and feasible. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the field test of the present invention;

[0026] Figure 2 Schematic diagram of radial and axial temperature distribution curves on the outer surface of the housing of the present invention;

[0027] Figure 3 Schematic diagram of the flow of the method for determining the severity of thermal defects according to the present invention.

[0028] In the figure, 1 is the GIS shell, 2 is the internal connection point, and 3 is the maximum temperature part of the GIS shell. DETAILED DESCRIPTION

[0029] The present invention will be further described below with reference to the accompanying drawings.

[0030] The present invention provides a method for determining the severity of thermal defects by utilizing the difference in radial and axial temperature distribution of GIS temperature, which has the advantages of being easy to implement and determine on site.

[0031] Specifically, first conduct on-site temperature distribution test, such as Figure 1 As shown in the figure, 1 is the GIS shell, and 2 is the internal connection point (such as disconnector contacts, circuit breaker contacts, etc.), which is a high-incidence location for internal thermal defects.

[0032] During the test, first determine the maximum temperature point 3 on the outside of the GIS shell using an infrared temperature measuring device;

[0033] Then, taking the location of the maximum external temperature as the starting point, the radial temperature distribution curve f1(x) is obtained. In this technical solution, the radial direction is the direction from the top to the bottom of the GIS shell circumference, which is in the shape of an arc and the distance is L.

[0034] Secondly, taking the maximum temperature point 3 on the outside of the GIS shell as the starting point, the temperature zone distribution curve f2(x) in the axial direction is obtained; in this technical solution, the axial direction is the radial direction of the top of the GIS shell, which is a straight line, and its distance is also selected as L.

[0035] Finally, the correlation coefficient of the temperature distribution curve f1(x) in the radial direction and the temperature zone distribution curve f2(x) in the axial direction is calculated;

[0036] The calculation of correlation coefficient is a commonly used method and will not be described in detail here.

[0037] The correlation coefficient r is obtained, and the range of r is 0-1. The larger the value, the more similar the two curves are.

[0038] See also Figure 2 As shown in , when the thermal defect is serious, the difference in temperature distribution in the radial direction and the radial direction becomes larger due to the difference in heat conduction characteristics;

[0039] The smaller the value of the correlation coefficient r, the greater the difference, which means the thermal defect is more serious; otherwise, it means the thermal defect is not serious.

[0040] The severity of thermal defects of gas-insulated switchgear can be quantitatively assessed by the value of r.

[0041] Figure 3The specific implementation steps of this technical solution are given in:

[0042] 1) Use an infrared temperature measuring device or infrared imager to detect the temperature distribution of the gas-insulated combination electrical appliance casing and form a temperature distribution image;

[0043] 2) Determine the maximum temperature position on the outside of the GIS housing;

[0044] 3) Taking the maximum temperature point on the outside of the GIS shell as the starting point, obtain the radial temperature distribution curve f1(x);

[0045] 4) Taking the maximum temperature point on the outside of the GIS shell as the starting point, obtain the temperature zone distribution curve f2(x) in the axial direction;

[0046] 5) Calculate the correlation coefficient r between the temperature distribution curve f1(x) in the radial direction and the temperature zone distribution curve f2(x) in the axial direction;

[0047] 6) Quantitatively assess the severity of thermal defects of gas-insulated combination electrical appliances through the size or change trend of the correlation coefficient r value.

[0048] The technical solution of the present invention, on the one hand, realizes the quantitative assessment of the severity of thermal defects of gas-insulated combination electrical appliances. On the other hand, all data sources are based on the actual values ​​of the on-site equipment, without the need for various pre-settings, and can adapt to the specific structure of each on-site equipment, providing a quantitative assessment method that is easy to operate on-site and simple and feasible.

[0049] The technical solution of the present invention makes full use of the differences in GIS temperature distribution in the axial and radial directions. It can conveniently use an infrared imaging device to obtain the axial and radial temperature distribution curves of the GIS shell and judge the severity of its thermal defects, avoiding the disadvantage of inaccurate results caused by judging only based on temperature values.

[0050] The present invention can be widely used in the fields of operation management and on-site monitoring of GIS equipment.

Claims

1. A method for determining the severity of thermal defects in a gas-insulated combination electrical appliance, comprising detecting the temperature distribution of the housing of the gas-insulated combination electrical appliance using an infrared temperature measuring device or an infrared imager to form a temperature distribution image; the method is characterized by: 1) Determine the maximum temperature position on the outside of the GIS housing; 2) Taking the maximum temperature point on the outside of the GIS shell as the starting point, obtain the radial temperature distribution curve f1(x); 3) Taking the maximum temperature point on the outside of the GIS shell as the starting point, obtain the temperature zone distribution curve f2(x) in the axial direction; 4) Calculate the correlation coefficient r between the temperature distribution curve f1(x) in the radial direction and the temperature zone distribution curve f2(x) in the axial direction; 5) Quantitatively assess the severity of thermal defects of gas-insulated switchgear through the numerical value or change trend of the correlation coefficient r; The larger the value of the correlation coefficient, the more similar the radial temperature distribution curve and the axial temperature zone distribution curve are, indicating that the thermal defect of the gas-insulated switchgear is not serious. The smaller the value of the correlation coefficient, the greater the difference between the radial temperature distribution curve and the axial temperature zone distribution curve, indicating that the thermal defect of the gas-insulated combination electrical appliance is more serious. The method for determining the severity of the thermal defect of the gas-insulated combination electrical appliance calculates the correlation coefficient of the radial temperature distribution curve and the axial temperature zone distribution curve by means of on-site temperature distribution testing. By analyzing the size and change trend of the correlation coefficient, a quantitative assessment of the severity of the thermal defect of the gas-insulated combination electrical appliance is conveniently achieved, avoiding the disadvantage of inaccurate results caused by judging only based on the GIS shell temperature value. The method is a quantitative assessment method that is easy to operate on-site and simple and feasible.

2. The method for determining the severity of thermal defects of a gas-insulated switchgear according to claim 1, wherein: The radial direction is the direction from the top to the bottom of the circumference of the GIS shell, which is in the shape of an arc and the distance is L.

3. The method for determining the severity of thermal defects of a gas-insulated switchgear according to claim 1, wherein: The axial direction is the radial direction of the top of the GIS shell, which is in a straight line and has a distance of L.

4. The method for determining the severity of thermal defects of a gas-insulated switchgear according to claim 1, wherein The correlation coefficient r ranges from 0 to 1.

Images