Extra-high voltage insulator deterioration detection and analysis method based on electric field method

Abstract

The invention discloses an extra-high voltage insulator deterioration detection and analysis method based on an electric field method. The method comprises the following steps: S1, obtaining the axial electric field intensity of an insulator; s2, forming an electric field distribution curve of the insulator based on the electric field intensity obtained in the step S1; s3, analyzing the electric field distribution curve: performing feature extraction on the electric field distribution curve formed in the step S2 to obtain measurement curve features, and comparing the measurement curve features with preset normal curve features to obtain comparison data; and S4, judging whether the insulator is degraded or not based on the comparison data obtained in the step S3. The method has the advantages that the electric field curve characteristics of the current insulator can be objectively reflected, the interference of human subjective factors is avoided, the judgment error is reduced, and the deterioration degree of the current insulator is more accurately reflected.

Description

Technical Field

[0001] The present invention relates to the field of ultra-high voltage insulator detection, and in particular to an ultra-high voltage insulator degradation detection and analysis method based on an electric field method. Background Art

[0002] The insulator strings of transmission lines are prone to aging and degradation due to the long-term exposure to electromechanical loads, sun and rain, cold and heat changes and many other external factors. When insulation degradation occurs in the insulator string, the creepage distance of the insulator string will be shortened, thereby increasing the probability of flashover accidents. When a flashover accident occurs in the insulator string, the connection hardware of the degraded insulator will break and fall off, reducing the overall mechanical properties of the insulator string. It can no longer withstand the tension of the transmission line, causing the transmission line to be grounded and causing serious power system accidents. Therefore, in order to reduce the occurrence of power system accidents and improve power supply reliability, it is crucial to regularly inspect the insulators of the transmission lines and promptly detect and replace degraded insulators.

[0003] In the prior art, for 110kV-500kV transmission lines, the spark gap method is often used to detect the deterioration of insulator strings, and the spark fork contact strip is used to detect the insulator pieces and identify them by sound. However, for UHV transmission lines, since the insulator strings are too long and the corona discharge sound is loud due to the voltage level, the spark gap method has large errors and is inconvenient.

[0004] Therefore, a more intelligent detection method is urgently needed to make up for the shortcomings of current UHV insulator string detection. Summary of the invention

[0005] The object of the present invention is to provide a UHV insulator degradation detection and analysis method based on an electric field method, which can accurately determine the degree of insulator degradation.

[0006] In order to solve the above technical problems, the present invention is achieved through the following technical solutions:

[0007] A method for detecting and analyzing degradation of ultra-high voltage insulators based on an electric field method comprises the following steps:

[0008] S1. Obtain the axial electric field strength of the insulator;

[0009] S2. forming an electric field distribution curve of the insulator based on the electric field strength obtained in step S1;

[0010] S3, analyzing the electric field distribution curve: extracting features of the electric field distribution curve formed in step S2 to obtain measurement curve features, and comparing the measurement curve features with preset normal curve features to obtain comparison data;

[0011] S4. Based on the comparison data obtained in step S3, determine whether the insulator is deteriorated.

[0012] Preferably, the electric field distribution curve in step S2 is a curve with the horizontal axis being the position and the vertical axis being the electric field strength. The electric field distribution curve composed of the position and the electric field strength as coordinates can intuitively understand the current degree of degradation of the high-voltage insulator.

[0013] Preferably, the sampling interval of the horizontal axis of the electric field distribution curve is 15-50 cm. If the sampling interval is too short and the evaluation rate is too high, it will increase the additional sampling workload, and if the sampling interval is too long, the electric field distribution curve cannot be accurately reflected.

[0014] Preferably, in step S3, the electric field intensity corresponding to each position of the electric field distribution curve is normalized to obtain the measurement curve characteristics. The calculation process is simplified by normalization.

[0015] Preferably, in step S3, the electric field strength corresponding to the preset normal curve feature at each position is the normalized electric field strength.

[0016] Preferably, in step S3, the comparison data is obtained by subtracting the electric field strength corresponding to each position of the preset normal curve feature from the electric field strength corresponding to each position of the measurement curve feature, thereby obtaining the electric field strength difference ΔE at each position. The electric field strength difference can clearly reflect the change of the electric field strength at the current position, thereby judging the degree of deterioration of the insulator at the position.

[0017] Preferably, in step S4, judging whether the insulator is degraded is judging whether the electric field strength difference ΔE is greater than or equal to a threshold electric field strength difference. Judging whether the insulator at the current position is degraded is based on the difference between the electric field strength difference and the threshold.

[0018] Preferably, the threshold electric field strength difference is divided into at least three levels, so as to more accurately describe the current degree of insulator degradation.

[0019] Preferably, the threshold electric field strength difference is divided into three levels, and the threshold electric field strength differences corresponding to the three levels are 20%, 30% and 50%, the threshold electric field strength difference of 20% represents slight degradation, the threshold electric field strength difference of 30% represents moderate degradation, and the threshold electric field strength difference of 50% represents complete degradation. Whether the current UHV insulator needs to be replaced is determined based on different threshold electric field strength differences.

[0020] Compared with the prior art, the advantages of the present invention are:

[0021] By comparing the electric field distribution curve with the normal curve characteristics, it is determined whether the insulator is degraded, which solves the problem that the current spark gap method cannot accurately determine the degree of insulator degradation through sound identification. First, the axial electric field strength of the insulator is obtained, and the electric field distribution curve is drawn with the measured electric field strength, and then compared with the preset electric field curve characteristics. The comparison data is used to determine whether the insulator is degraded. The measurement of the electric field strength of the insulator is already a relatively mature technology, and it can objectively reflect the electric field curve characteristics of the current insulator. The result obtained by comparing with the curve characteristics of the normal insulator electric field is relatively more objective, which can avoid interference from human subjective factors, reduce judgment errors, and more accurately reflect the current degree of insulator degradation. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural schematic diagram of an insulator string of the present invention;

[0023] Figure 2 A step diagram of the detection method provided by the present invention;

[0024] Figure 3 It is the experimental diagram of the detection result of the present invention. DETAILED DESCRIPTION

[0025] A method for detecting and analyzing degradation of ultra-high voltage insulators based on an electric field method comprises the following steps:

[0026] S1. Obtain the axial electric field strength of the insulator;

[0027] S2. forming an electric field distribution curve of the insulator based on the electric field strength obtained in step S1;

[0028] S3, analyzing the electric field distribution curve: extracting features of the electric field distribution curve formed in step S2 to obtain measurement curve features, and comparing the measurement curve features with preset normal curve features to obtain comparison data;

[0029] S4. Based on the comparison data obtained in step S3, determine whether the insulator is deteriorated.

[0030] By comparing the electric field distribution curve with the normal curve characteristics, it is determined whether the insulator is degraded, which solves the problem that the current spark gap method cannot accurately determine the degree of insulator degradation through sound identification. First, the axial electric field strength of the insulator is obtained, and the electric field distribution curve is drawn with the measured electric field strength, and then compared with the preset electric field curve characteristics. The comparison data is used to determine whether the insulator is degraded. The measurement of the electric field strength of the insulator is already a relatively mature technology, and it can objectively reflect the electric field curve characteristics of the current insulator. The result obtained by comparing with the curve characteristics of the normal insulator electric field is relatively more objective, which can avoid interference from human subjective factors, reduce judgment errors, and more accurately reflect the current degree of insulator degradation.

[0031] Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0032] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0033] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0034] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0035] like Figure 1As shown, the insulator string 100 includes a plurality of insulators P1-Pn, wherein n is 6 / 7 / 8 or 12 / 13 / 14 or 25 / 26 / 28 / 29 / 30. The present invention only takes n=30 as an example and does not limit n.

[0036] See also Figures 1 to 3 This is an embodiment of a method for detecting and analyzing degradation of ultra-high voltage insulators based on an electric field method of the present invention. The method for detecting and analyzing degradation of ultra-high voltage insulators based on an electric field method comprises the following steps:

[0037] S1. Obtain the axial electric field strength of the insulator;

[0038] S2. forming an electric field distribution curve of the insulator based on the electric field strength obtained in step S1;

[0039] S3, analyzing the electric field distribution curve: extracting features of the electric field distribution curve formed in step S2 to obtain measurement curve features, and comparing the measurement curve features with preset normal curve features to obtain comparison data;

[0040] S4. Based on the comparison data obtained in step S3, determine whether the insulator is deteriorated.

[0041] In the above embodiment, the electric field distribution curve in step S2 is a curve in which the horizontal axis is the position and the vertical axis is the electric field strength. The horizontal axis sampling interval of the electric field distribution curve is 15-50cm. If the sampling interval is too short and the evaluation rate is too high, the additional sampling workload will be increased, and if the sampling interval is too long, the electric field distribution curve cannot be accurately reflected.

[0042] In the step S3, the electric field strength corresponding to each position of the electric field distribution curve is normalized to obtain the measurement curve characteristics; the electric field strength corresponding to each position of the preset normal curve characteristics is the normalized electric field strength. The calculation process is simplified by normalization.

[0043] Furthermore, in step S3, the comparison data is obtained by subtracting the electric field strength corresponding to each position of the preset normal curve feature from the electric field strength corresponding to each position of the measurement curve feature, thereby obtaining the electric field strength difference ΔE at each position. The electric field strength difference can clearly reflect the change of the electric field strength at the current position, thereby judging the degree of deterioration of the insulator at the position.

[0044] For step S4, judging whether the insulator is degraded is judging whether the electric field strength difference ΔE is greater than or equal to the threshold electric field strength difference. Judging whether the insulator at the current position is degraded is based on the difference between the electric field strength difference and the threshold. The threshold electric field strength difference is divided into three levels, and the threshold electric field strength differences corresponding to the three levels are 20%, 30% and 50%. The threshold electric field strength difference of 20% represents slight degradation, the threshold electric field strength difference of 30% represents moderate degradation, and the threshold electric field strength difference of 50% represents complete degradation. Determine whether the current UHV insulator needs to be replaced based on different threshold electric field strength differences.

[0045] The method of the present invention is applicable to the detection and analysis of different types of insulator strings, including but not limited to string insulators, tension insulators, DC insulators, composite insulators, polymer insulators, and glass insulators; wherein, string insulators are usually composed of multiple ceramic rings and are used for suspension and tension support in high-voltage transmission lines. The characteristics of string insulators are strong insulation capacity and good resistance to dielectric damage. Tension insulators are usually composed of one or more ceramic rods and are used for spanning and vertical support in high-voltage transmission lines. The characteristics of tension insulators are strong tension capacity, light weight, and easy installation. DC insulators are usually composed of multiple ceramic rings or glass fiber materials and are used for support and isolation in DC transmission lines. DC insulators are characterized by strong durability, high mechanical strength, and excellent insulation capacity. Composite insulators are a new type of insulator developed in recent years, consisting of a ceramic core rod and a silicone rubber outer layer. Composite insulators are characterized by good insulation capacity, high mechanical strength, and excellent anti-pollution flashover performance. Polymer insulators are usually made of polymer materials such as plastics or rubber, and are used for support and isolation in low-voltage distribution systems. The characteristics of polymer insulators are low cost, light weight and easy installation. Glass insulators are made of glass fiber materials and are usually used in power equipment in high temperature and high humidity environments. The characteristics of glass insulators are high temperature resistance, strong moisture resistance and high mechanical strength.

[0046] Figure 3 The experiment obtained by the method provided by the present invention is shown as follows: Figure 3 As shown in the curve graph, the horizontal axis is the position corresponding to the insulators P1-P30, and the vertical axis is the electric field strength (KV / m) at the corresponding position. The dotted line shows the characteristics of the measured curve, and the dotted line shows the characteristics of the normal curve. It can be seen from the figure that the insulator at the position P21 has deteriorated.

[0047] The present invention can convert the measured value of the axial electric field on the surface of the insulator string under different working conditions of the 110kV-500kV transmission line into the corresponding electric field strength value, analyze the degradation characteristics of the insulator based on the electric field distribution, and judge the degree of degradation of the suspected deteriorated position of the insulator string. The present invention sets three levels, and the corresponding threshold electric field strength difference is 20%, 30% and 50%. The threshold electric field strength difference of 20% represents slight degradation, the threshold electric field strength difference of 30% represents moderate degradation, and the threshold electric field strength difference of 50% represents complete degradation. The user can choose the corresponding measures as needed. For example, when the detection result is slight degradation, you can choose to continue to use it, while focusing on monitoring and shortening the next detection time; or replace it and install it in a power grid with low requirements, or only replace a few failed insulators; when the detection result is moderate degradation, you can focus on replacing the failed insulator; when the detection result is complete degradation, you need to replace a brand new insulator string and analyze the cause of failure.

[0048] The above description is only a specific embodiment of the present invention, but the technical features of the present invention are not limited thereto. Any changes or modifications made by any technician in the field of the present invention are included in the patent scope of the present invention.

Claims

1. A method for detecting and analyzing degradation of ultra-high voltage insulators based on electric field method, characterized in that: The following steps are involved: S1. Obtain the axial electric field strength of the insulator; S2. forming an electric field distribution curve of the insulator based on the electric field strength obtained in step S1; S3, analyzing the electric field distribution curve: extracting features of the electric field distribution curve formed in step S2 to obtain measurement curve features, and comparing the measurement curve features with preset normal curve features to obtain comparison data; S4. Based on the comparison data obtained in step S3, determine whether the insulator is deteriorated.

2. The method for detecting and analyzing degradation of ultra-high voltage insulators based on electric field method according to claim 1, characterized in that: The electric field distribution curve in step S2 is a curve in which the horizontal axis is the position and the vertical axis is the electric field strength.

3. The method for detecting and analyzing degradation of ultra-high voltage insulators based on electric field method according to claim 2, characterized in that: The sampling interval of the abscissa of the electric field distribution curve is 15-50 cm.

4. The method for detecting and analyzing degradation of ultra-high voltage insulators based on electric field method according to claim 1, characterized in that: In the step S3, it also includes normalizing the electric field intensity corresponding to each position of the electric field distribution curve, so as to obtain the measurement curve characteristics.

5. The method for detecting and analyzing degradation of ultra-high voltage insulators based on electric field method according to claim 4, characterized in that: In the step S3, the electric field strength corresponding to the preset normal curve feature at each position is the normalized electric field strength.

6. The method for detecting and analyzing degradation of ultra-high voltage insulators based on electric field method according to claim 5, characterized in that: In step S3, the comparison data is obtained by subtracting the electric field intensity corresponding to each position of the preset normal curve feature from the electric field intensity corresponding to each position of the measurement curve feature, thereby obtaining the electric field intensity difference ΔE at each position.

7. The method for detecting and analyzing degradation of ultra-high voltage insulators based on electric field method according to claim 6, characterized in that: In the step S4, judging whether the insulator is degraded is judging whether the electric field strength difference ΔE is greater than or equal to a threshold electric field strength difference.

8. The method for detecting and analyzing degradation of ultra-high voltage insulators based on electric field method according to claim 7, characterized in that: The threshold electric field strength difference is divided into at least three levels.

9. The method for detecting and analyzing degradation of ultra-high voltage insulators based on electric field method according to claim 8, characterized in that: The threshold electric field strength difference is divided into three levels, and the threshold electric field strength differences corresponding to the three levels are 20%, 30% and 50%. The threshold electric field strength difference of 20% represents slight degradation, the threshold electric field strength difference of 30% represents moderate degradation, and the threshold electric field strength difference of 50% represents complete degradation.

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