CN112285495A - Electric field distribution based method for judging deterioration of insulator of power transmission line - Google Patents
Electric field distribution based method for judging deterioration of insulator of power transmission line Download PDFInfo
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/12—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
- G01R31/1227—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials
- G01R31/1245—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials of line insulators or spacers, e.g. ceramic overhead line cap insulators; of insulators in HV bushings
Abstract
A method for judging the deterioration of an insulator of a transmission line based on electric field distribution detection is characterized in that measured values of axial electric fields on the surface of an insulator under different working conditions of a 66-500 kV transmission line are converted into corresponding voltage values so as to be compared with standard values of the distribution voltage of the insulator of the transmission line in a standard; based on the insulator degradation characteristic analysis of the electric field, when a low-zero-value insulator with insulation degradation appears in the power transmission line, judging the insulation state of the insulator through the change of the surface axial electric field distribution; the algorithm function is the function equipped by the matched software. The invention has the advantages that: the method effectively overcomes the defects that the existing inferior insulators need to be detected piece by piece, are greatly influenced by the temperature environment and the like, has the advantages of simplicity and convenience in operation, high accuracy and stability and the like, can improve the detection efficiency of the deteriorated insulators of the power transmission line, reduces the operation intensity, has very important significance for ensuring the safe and stable operation of the power transmission line, and provides a new technical discrimination method for the deterioration detection of the insulators of the power transmission line.
Description
Technical Field
The invention relates to the field of transmission line insulator detection, in particular to a method for judging the deterioration of a transmission line insulator based on electric field distribution detection.
Background
The safe and stable operation of the power system is more and more emphasized, and the insulator is used as an important insulation fitting to be widely applied to high-voltage transmission lines, particularly high-voltage alternating-current and direct-current transmission systems which are vigorously developed in recent years, and the safe operation problem of the insulator directly influences the safe reliability of the whole transmission system. If the insulator is degraded, the safety and reliability of the operation of the power system are greatly threatened. In domestic power grids, line flashover accidents caused by deteriorated insulators often occur, and huge losses are caused to national economy. With the continuous expansion of the scale of a power grid and the continuous increase of the running time of an insulator during the operation of the power grid, the insulator on a power transmission line can be degraded in insulating performance or mechanical performance due to the long-term effects of electromechanical load, sun and rain, cold and heat changes and the like in the operation process, so that the insulator can be degraded, faults such as reduction of insulation resistance, insulation cracking and even breakdown can be caused, and potential threats can be brought to the power supply reliability of the power grid.
The deteriorated insulator of the live line detection has become one of the most concerned problems in the domestic and foreign power departments. Therefore, in order to meet the requirement of power development in China, the charged detection method for the degradation of the insulator of the power transmission line is systematically researched by utilizing advanced technical means, so that the charged detection method has important engineering value for ensuring the safe operation of the power transmission line and monitoring the insulation state of the insulator of the power transmission line in operation, and has important significance for promoting and perfecting the research on the detection method for the degradation of the insulator.
Disclosure of Invention
The invention provides a method for judging the deterioration of the insulator of the power transmission line based on the electric field distribution detection aiming at the problems in the prior art, and provides a new technical judgment method for the deterioration detection of the insulator of the power transmission line.
The invention provides a method for judging the deterioration of an insulator of a power transmission line based on electric field distribution detection, which is characterized by comprising the following steps: the discrimination method for detecting the deterioration of the insulator of the power transmission line based on the electric field distribution specifically comprises the following steps:
converting measured values of axial electric fields on the surfaces of insulators under different working conditions of a 66-500 kV power transmission line into corresponding voltage values so as to compare the measured values with standard values of distribution voltages of insulators of the power transmission line in a standard DL/T62-2005;
based on the insulator degradation characteristic analysis of the electric field, when a low-zero-value insulator with insulation degradation appears in the power transmission line, judging the insulation state of the insulator through the change of the surface axial electric field distribution; the algorithm function is the function equipped by the matched software.
Converting measured values of axial electric fields of the surfaces of insulators of 66-500 kV transmission lines under different working conditions into corresponding voltage values, assuming that the number of insulator pieces of a tested insulator string is n, the system running phase voltage borne by the tested insulator string is U, the standard distribution voltage is SUi (i is 1, 2, …, n) when the insulator string is not degraded, the measured value of the axial electric fields of the surfaces is SEi, and the standard field after normalization is Sei;
when the measured value of the axial electric field of the surface of each insulator under the actual working condition is Ei, the normalized electric field value is Ei:
the calculation method for the electric field voltage conversion coefficient ki is as follows:
ki＝k1i·k2i(1≤i≤n)
then, the distributed voltage of each insulator is calculated according to the measured value of the axial electric field on the surface of the insulator:
the judgment standard is as follows:
(1) the voltage value of the insulator to be tested is lower than a 50% standard specified value, and the insulator is judged to be a deteriorated insulator;
(2) the standard specified value of the measured insulator voltage value with 50% high voltage is obviously lower than the voltage values of qualified insulators at two adjacent sides, namely, the distribution voltage curve is suddenly reduced on the insulator to be in a V shape, and the insulator is judged to be a deteriorated insulator.
The process of analyzing the degradation characteristics of the insulator based on the electric field comprises the following steps:
characteristic amount: the degree of change dci of the self electric field, and the degree of change dai of the adjacent side electric field.
Data preprocessing: the standard field and the measured field are both insulator surface axial electric fields;
acquiring a standard field SEi under the working condition through a database (field actual measurement/simulation calculation), and calculating a normalized electric field Sei; and carrying out normalization processing on the actually measured electric field data Ei to obtain Ei.
And (3) calculating a characteristic value:
calculating a difference field delta ei-Sei between the measured field and the standard field;
calculating the electric field variation degree dci, which shows a decrease when dci is negative:
calculating the difference ai between each point of dci after removing two end points and the front and back mean values, and representing the curvature characteristics:
and (3) subsection analysis:
selecting conditions of the segmentation points:
the point is a maximum value point, ai is more than Y0 which is equal to 2%, the electric field change at the point is positive, dci is more than 0, and a point with dci less than 0 exists on the adjacent side;
when no segmentation point exists, no deteriorated insulator is found;
when there is a segmentation point, a segment whose electric field change is smaller than Y1(Y1 ═ 0) is suspected to be degraded, and the degree of degradation is represented by each point dci or each point curvature value in the segment.
Two-endpoint analysis:
deterioration is observed when the degree of decrease of both ends exceeds 40%, and no deterioration is observed when the degree of decrease is less than 30%;
when the end point descending degree is 30% -40%, the positions between the end points are suspected, and the states of the end points are consistent with the states of the adjacent points.
The algorithm function design specifically comprises the following steps:
1) voltage class: 66kV, 220kV and 500kV
2) The type of the tower is as follows: wine glass tower and double-circuit tower
3) Insulator type: composite insulator and porcelain insulator
4) Insulator string type: strain insulator-string, straight line cluster
5) Number of insulator pieces: 6/7/8, 12/13/14, 25/26/28/29/30
6) Standard field: actual measurement field, simulation field.
The algorithm function design specifically comprises the following input parameters:
1) the standard field is initialized to: when actual measurement field data under the same working condition exist in the database, the actual measurement data are used as a standard field, otherwise, a simulation field is used as the standard field;
2) an electric field voltage conversion coefficient ki;
3) the degradation feature analysis threshold values can be input and initialized as follows: y0 ═ 2%, Y1 ═ 0, Y2 ═ 30%, Y3 ═ 40%, modifiable;
4) and (3) actually measured data Ei of the axial electric field on the surface of the insulator string.
The algorithm function design specifically comprises the following steps of outputting a result:
1) an electric field distribution curve Ei;
2) calculating a comparison curve of the obtained voltage Ui and the standard distribution voltage Sui;
3) the degree of decrease dci and curvature curve ai of the electric field at each point;
4) degradation diagnosis results: suspected deterioration region, deterioration position, number of sheets, and deterioration degree.
The method can convert the measured values of the axial electric field on the surface of the insulator under different working conditions of the 66-500 kV power transmission line into corresponding voltage values, analyze the degradation characteristics of the insulator based on electric field distribution, and judge the suspected degradation area (degradation position and number of pieces) and the degradation degree of the insulator string.
The following explains a comparison of the method for judging deterioration of an insulator of a power transmission line according to the present invention:
currently, in the actual operation process, an operator moves an electric field detector by holding an operating rod to measure an insulator electric field piece by piece, then, measurement data is imported into a computer system, and an insulator string electric field distribution curve is drawn to judge whether a deteriorated insulator exists or not by observing whether a distortion point exists in the curve or not. The method for judging the deterioration condition of the insulator by directly observing the curve change has low judgment efficiency and insufficient accuracy and depth of data analysis, and the method for judging the deterioration condition of the insulator of the power transmission line has simple operation, can quickly and accurately and automatically judge suspected deterioration areas (deterioration positions and numbers) of the insulator string and the deterioration degree information, greatly saves the time for data analysis of operating personnel, is suitable for domestic popularization and use, and provides an effective technical judgment method for judging the deterioration condition of the insulator of the high-voltage power transmission line.
The invention has the advantages that:
the method for judging the deterioration of the insulator of the power transmission line based on the electric field distribution detection effectively overcomes the defects that the existing inferior insulators need to be detected piece by piece, are greatly influenced by the temperature environment and the like, has the advantages of simplicity and convenience in operation, high accuracy and stability and the like, can improve the detection efficiency of the deteriorated insulator of the power transmission line, reduces the operation intensity, and has very important significance for ensuring the safe and stable operation of the power transmission line. Aiming at the current situation that the existing electric field detection judgment is not standard and whether the deterioration exists can only be judged through a conventional electric field detection distribution curve, a method for judging the deterioration condition of an insulator according to the surface axial electric field data of the insulator of the power transmission line, which is more accurate and has a judgment basis, is provided, and a new technical judgment method is provided for the detection of the deterioration of the insulator of the power transmission line.
Drawings
The invention is described in further detail below with reference to the following figures and embodiments:
FIG. 1 is a flow chart of electric field based insulator degradation characteristic analysis calculation;
FIG. 2 is a graph of voltage distribution under different operating conditions.
Detailed Description
Example 1
The invention provides a method for judging the deterioration of an insulator of a power transmission line based on electric field distribution detection, which is characterized by comprising the following steps: the discrimination method for detecting the deterioration of the insulator of the power transmission line based on the electric field distribution specifically comprises the following steps:
converting measured values of axial electric fields on the surfaces of insulators under different working conditions of a 66-500 kV power transmission line into corresponding voltage values so as to compare the measured values with standard values of distribution voltages of insulators of the power transmission line in a standard DL/T62-2005;
based on the insulator degradation characteristic analysis of the electric field, when a low-zero-value insulator with insulation degradation appears in the power transmission line, judging the insulation state of the insulator through the change of the surface axial electric field distribution; the algorithm function is the function equipped by the matched software.
Converting measured values of axial electric fields of the surfaces of insulators of 66-500 kV transmission lines under different working conditions into corresponding voltage values, assuming that the number of insulator pieces of a tested insulator string is n, the system running phase voltage borne by the tested insulator string is U, the standard distribution voltage is SUi (i is 1, 2, …, n) when the insulator string is not degraded, the measured value of the axial electric fields of the surfaces is SEi, and the standard field after normalization is Sei;
when the measured value of the axial electric field of the surface of each insulator under the actual working condition is Ei, the normalized electric field value is Ei:
the calculation method for the electric field voltage conversion coefficient ki is as follows:
ki＝k1i·k2i(1≤i≤n)
then, the distributed voltage of each insulator is calculated according to the measured value of the axial electric field on the surface of the insulator:
the judgment standard is as follows:
(1) the voltage value of the insulator to be tested is lower than a 50% standard specified value, and the insulator is judged to be a deteriorated insulator;
(2) the standard specified value of the measured insulator voltage value with 50% high voltage is obviously lower than the voltage values of qualified insulators at two adjacent sides, namely, the distribution voltage curve is suddenly reduced on the insulator to be in a V shape, and the insulator is judged to be a deteriorated insulator.
The process of analyzing the degradation characteristics of the insulator based on the electric field comprises the following steps:
characteristic amount: the degree of change dci of the self electric field, and the degree of change dai of the adjacent side electric field.
Data preprocessing: the standard field and the measured field are both insulator surface axial electric fields;
acquiring a standard field SEi under the working condition through a database (field actual measurement/simulation calculation), and calculating a normalized electric field Sei; and carrying out normalization processing on the actually measured electric field data Ei to obtain Ei.
And (3) calculating a characteristic value:
calculating a difference field delta ei-Sei between the measured field and the standard field;
calculating the electric field variation degree dci, which shows a decrease when dci is negative:
calculating the difference ai between each point of dci after removing two end points and the front and back mean values, and representing the curvature characteristics:
and (3) subsection analysis:
selecting conditions of the segmentation points:
the point is a maximum value point, ai is more than Y0 which is equal to 2%, the electric field change at the point is positive, dci is more than 0, and a point with dci less than 0 exists on the adjacent side;
when no segmentation point exists, no deteriorated insulator is found;
when there is a segmentation point, a segment whose electric field change is smaller than Y1(Y1 ═ 0) is suspected to be degraded, and the degree of degradation is represented by each point dci or each point curvature value in the segment.
Two-endpoint analysis:
deterioration is observed when the degree of decrease of both ends exceeds 40%, and no deterioration is observed when the degree of decrease is less than 30%;
when the end point descending degree is 30% -40%, the positions between the end points are suspected, and the states of the end points are consistent with the states of the adjacent points.
The method can convert the measured values of the axial electric field on the surface of the insulator under different working conditions of the 66-500 kV power transmission line into corresponding voltage values, analyze the degradation characteristics of the insulator based on electric field distribution, and judge the suspected degradation area (degradation position and number of pieces) and the degradation degree of the insulator string.
The following explains a comparison of the method for judging deterioration of an insulator of a power transmission line according to the present invention:
currently, in the actual operation process, an operator moves an electric field detector by holding an operating rod to measure an insulator electric field piece by piece, then, measurement data is imported into a computer system, and an insulator string electric field distribution curve is drawn to judge whether a deteriorated insulator exists or not by observing whether a distortion point exists in the curve or not. The method for judging the deterioration condition of the insulator by directly observing the curve change has low judgment efficiency and insufficient accuracy and depth of data analysis, and the method for judging the deterioration condition of the insulator of the power transmission line has simple operation, can quickly and accurately and automatically judge suspected deterioration areas (deterioration positions and numbers) of the insulator string and the deterioration degree information, greatly saves the time for data analysis of operating personnel, is suitable for domestic popularization and use, and provides an effective technical judgment method for judging the deterioration condition of the insulator of the high-voltage power transmission line.
Example 2
The invention provides a method for judging the deterioration of an insulator of a power transmission line based on electric field distribution detection, which is characterized by comprising the following steps: the discrimination method for detecting the deterioration of the insulator of the power transmission line based on the electric field distribution specifically comprises the following steps:
converting measured values of axial electric fields on the surfaces of insulators under different working conditions of a 66-500 kV power transmission line into corresponding voltage values so as to compare the measured values with standard values of distribution voltages of insulators of the power transmission line in a standard DL/T62-2005;
based on the insulator degradation characteristic analysis of the electric field, when a low-zero-value insulator with insulation degradation appears in the power transmission line, judging the insulation state of the insulator through the change of the surface axial electric field distribution; the algorithm function is the function equipped by the matched software.
Converting measured values of axial electric fields of the surfaces of insulators of 66-500 kV transmission lines under different working conditions into corresponding voltage values, assuming that the number of insulator pieces of a tested insulator string is n, the system running phase voltage borne by the tested insulator string is U, the standard distribution voltage is SUi (i is 1, 2, …, n) when the insulator string is not degraded, the measured value of the axial electric fields of the surfaces is SEi, and the standard field after normalization is Sei;
when the measured value of the axial electric field of the surface of each insulator under the actual working condition is Ei, the normalized electric field value is Ei:
the calculation method for the electric field voltage conversion coefficient ki is as follows:
ki＝k1i·k2i(1≤i≤n)
then, the distributed voltage of each insulator is calculated according to the measured value of the axial electric field on the surface of the insulator:
the judgment standard is as follows:
(1) the voltage value of the insulator to be tested is lower than a 50% standard specified value, and the insulator is judged to be a deteriorated insulator;
(2) the standard specified value of the measured insulator voltage value with 50% high voltage is obviously lower than the voltage values of qualified insulators at two adjacent sides, namely, the distribution voltage curve is suddenly reduced on the insulator to be in a V shape, and the insulator is judged to be a deteriorated insulator.
The process of analyzing the degradation characteristics of the insulator based on the electric field comprises the following steps:
characteristic amount: the degree of change dci of the self electric field, and the degree of change dai of the adjacent side electric field.
Data preprocessing: the standard field and the measured field are both insulator surface axial electric fields;
acquiring a standard field SEi under the working condition through a database (field actual measurement/simulation calculation), and calculating a normalized electric field Sei; and carrying out normalization processing on the actually measured electric field data Ei to obtain Ei.
And (3) calculating a characteristic value:
calculating a difference field delta ei-Sei between the measured field and the standard field;
calculating the electric field variation degree dci, which shows a decrease when dci is negative:
calculating the difference ai between each point of dci after removing two end points and the front and back mean values, and representing the curvature characteristics:
and (3) subsection analysis:
selecting conditions of the segmentation points:
the point is a maximum value point, ai is more than Y0 which is equal to 2%, the electric field change at the point is positive, dci is more than 0, and a point with dci less than 0 exists on the adjacent side;
when no segmentation point exists, no deteriorated insulator is found;
when there is a segmentation point, a segment whose electric field change is smaller than Y1(Y1 ═ 0) is suspected to be degraded, and the degree of degradation is represented by each point dci or each point curvature value in the segment.
Two-endpoint analysis:
deterioration is observed when the degree of decrease of both ends exceeds 40%, and no deterioration is observed when the degree of decrease is less than 30%;
when the end point descending degree is 30% -40%, the positions between the end points are suspected, and the states of the end points are consistent with the states of the adjacent points.
The algorithm function design specifically comprises the following steps:
1) voltage class: 66kV, 220kV and 500kV
2) The type of the tower is as follows: wine glass tower and double-circuit tower
3) Insulator type: composite insulator and porcelain insulator
4) Insulator string type: strain insulator-string, straight line cluster
5) Number of insulator pieces: 6/7/8, 12/13/14, 25/26/28/29/30
6) Standard field: actual measurement field, simulation field.
The algorithm function design specifically comprises the following input parameters:
1) the standard field is initialized to: when actual measurement field data under the same working condition exist in the database, the actual measurement data are used as a standard field, otherwise, a simulation field is used as the standard field;
2) an electric field voltage conversion coefficient ki;
3) the degradation feature analysis threshold values can be input and initialized as follows: y0 ═ 2%, Y1 ═ 0, Y2 ═ 30%, Y3 ═ 40%, modifiable;
4) and (3) actually measured data Ei of the axial electric field on the surface of the insulator string.
The algorithm function design specifically comprises the following steps of outputting a result:
1) an electric field distribution curve Ei;
2) calculating a comparison curve of the obtained voltage Ui and the standard distribution voltage Sui;
3) the degree of decrease dci and curvature curve ai of the electric field at each point;
4) degradation diagnosis results: suspected deterioration region, deterioration position, number of sheets, and deterioration degree.
The method can convert the measured values of the axial electric field on the surface of the insulator under different working conditions of the 66-500 kV power transmission line into corresponding voltage values, analyze the degradation characteristics of the insulator based on electric field distribution, and judge the suspected degradation area (degradation position and number of pieces) and the degradation degree of the insulator string.
The following explains a comparison of the method for judging deterioration of an insulator of a power transmission line according to the present invention:
currently, in the actual operation process, an operator moves an electric field detector by holding an operating rod to measure an insulator electric field piece by piece, then, measurement data is imported into a computer system, and an insulator string electric field distribution curve is drawn to judge whether a deteriorated insulator exists or not by observing whether a distortion point exists in the curve or not. The method for judging the deterioration condition of the insulator by directly observing the curve change has low judgment efficiency and insufficient accuracy and depth of data analysis, and the method for judging the deterioration condition of the insulator of the power transmission line has simple operation, can quickly and accurately and automatically judge suspected deterioration areas (deterioration positions and numbers) of the insulator string and the deterioration degree information, greatly saves the time for data analysis of operating personnel, is suitable for domestic popularization and use, and provides an effective technical judgment method for judging the deterioration condition of the insulator of the high-voltage power transmission line.
The present invention is not limited to the above-described embodiments, and it will be apparent to those skilled in the art that various modifications and improvements can be made without departing from the principle of the present invention, and such modifications and improvements are also considered to be within the scope of the present invention. Those not described in detail in this specification are within the skill of the art.
Claims (10)
1. A method for judging the deterioration of an insulator of a transmission line based on electric field distribution detection is characterized in that: the discrimination method for detecting the deterioration of the insulator of the power transmission line based on the electric field distribution specifically comprises the following steps:
converting measured values of axial electric fields on the surfaces of insulators under different working conditions of a 66-500 kV power transmission line into corresponding voltage values so as to compare the measured values with standard values of distribution voltages of insulators of the power transmission line in a standard DL/T62-2005;
based on the insulator degradation characteristic analysis of the electric field, when a low-zero-value insulator with insulation degradation appears in the power transmission line, judging the insulation state of the insulator through the change of the surface axial electric field distribution; the algorithm function is the function equipped by the matched software.
2. The method for judging the deterioration of the insulator of the power transmission line based on the electric field distribution detection according to claim 1, wherein: converting measured values of axial electric fields of the surfaces of insulators of 66-500 kV transmission lines under different working conditions into corresponding voltage values, assuming that the number of insulator pieces of a tested insulator string is n, the system running phase voltage borne by the tested insulator string is U, the standard distribution voltage is SUi (i is 1, 2, …, n) when the insulator string is not degraded, the measured value of the axial electric fields of the surfaces is SEi, and the standard field after normalization is Sei;
when the measured value of the axial electric field of the surface of each insulator under the actual working condition is Ei, the normalized electric field value is Ei:
the calculation method for the electric field voltage conversion coefficient ki is as follows:
ki＝k1i·k2i(1≤i≤n)
then, the distributed voltage of each insulator is calculated according to the measured value of the axial electric field on the surface of the insulator:
3. the method for judging the deterioration of the insulator of the power transmission line based on the electric field distribution detection according to claim 2, wherein: the judgment standard is as follows:
(1) the voltage value of the insulator to be tested is lower than a 50% standard specified value, and the insulator is judged to be a deteriorated insulator;
(2) the standard specified value of the measured insulator voltage value with 50% high voltage is obviously lower than the voltage values of qualified insulators at two adjacent sides, namely, the distribution voltage curve is suddenly reduced on the insulator to be in a V shape, and the insulator is judged to be a deteriorated insulator.
4. The method for judging the deterioration of the insulator of the power transmission line based on the electric field distribution detection according to claim 1, wherein: the process of analyzing the degradation characteristics of the insulator based on the electric field comprises the following steps:
characteristic amount: the degree of change dci of the self electric field, and the degree of change dai of the adjacent side electric field.
Data preprocessing: the standard field and the measured field are both insulator surface axial electric fields;
acquiring a standard field SEi under the working condition through a database (field actual measurement/simulation calculation), and calculating a normalized electric field Sei; and carrying out normalization processing on the actually measured electric field data Ei to obtain Ei.
5. The method for judging the deterioration of the insulator of the power transmission line based on the electric field distribution detection according to claim 1, wherein: and (3) calculating a characteristic value:
calculating a difference field delta ei-Sei between the measured field and the standard field;
calculating the electric field variation degree dci, which shows a decrease when dci is negative:
calculating the difference ai between each point of dci after removing two end points and the front and back mean values, and representing the curvature characteristics:
6. the method for judging the deterioration of the insulator of the power transmission line based on the electric field distribution detection according to claim 1, wherein: and (3) subsection analysis:
selecting conditions of the segmentation points:
the point is a maximum value point, ai is more than Y0 which is equal to 2%, the electric field change at the point is positive, dci is more than 0, and a point with dci less than 0 exists on the adjacent side;
when no segmentation point exists, no deteriorated insulator is found;
when there is a segmentation point, a segment whose electric field change is smaller than Y1(Y1 ═ 0) is suspected to be degraded, and the degree of degradation is represented by each point dci or each point curvature value in the segment.
7. The method for judging the deterioration of the insulator of the power transmission line based on the electric field distribution detection according to claim 1, wherein: two-endpoint analysis:
deterioration is observed when the degree of decrease of both ends exceeds 40%, and no deterioration is observed when the degree of decrease is less than 30%;
when the end point descending degree is 30% -40%, the positions between the end points are suspected, and the states of the end points are consistent with the states of the adjacent points.
8. The method for judging the deterioration of the insulator of the power transmission line based on the electric field distribution detection according to claim 1, wherein:
the algorithm function design specifically comprises the following steps:
1) voltage class: 66kV, 220kV and 500kV
2) The type of the tower is as follows: wine glass tower and double-circuit tower
3) Insulator type: composite insulator and porcelain insulator
4) Insulator string type: strain insulator-string, straight line cluster
5) Number of insulator pieces: 6/7/8, 12/13/14, 25/26/28/29/30
6) Standard field: actual measurement field, simulation field.
9. The method for judging the deterioration of the insulator of the power transmission line based on the electric field distribution detection according to claim 1, wherein: the algorithm function design specifically comprises the following input parameters:
1) the standard field is initialized to: when actual measurement field data under the same working condition exist in the database, the actual measurement data are used as a standard field, otherwise, a simulation field is used as the standard field;
2) an electric field voltage conversion coefficient ki;
3) the degradation feature analysis threshold values can be input and initialized as follows: y0 ═ 2%, Y1 ═ 0, Y2 ═ 30%, Y3 ═ 40%, modifiable;
4) and (3) actually measured data Ei of the axial electric field on the surface of the insulator string.
10. The method for judging the deterioration of the insulator of the power transmission line based on the electric field distribution detection according to claim 1, wherein: the algorithm function design specifically comprises the following steps of outputting a result:
1) an electric field distribution curve Ei;
2) calculating a comparison curve of the obtained voltage Ui and the standard distribution voltage Sui;
3) the degree of decrease dci and curvature curve ai of the electric field at each point;
4) degradation diagnosis results: suspected deterioration region, deterioration position, number of sheets, and deterioration degree.
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