CN111829663B - Composite insulator defect classification diagnosis method based on surface temperature distribution - Google Patents
Composite insulator defect classification diagnosis method based on surface temperature distribution Download PDFInfo
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Abstract
The invention discloses a composite insulator defect classification diagnosis method based on surface temperature distribution, which comprises the following steps: measuring the temperature of the insulator; judging whether the axial temperature rise of the repeating unit exceeds 1K, if so, possibly corroding the core rod; if not, judging whether the difference between the highest circumferential temperature rise and the lowest circumferential temperature rise of the high-pressure end part exceeds 3K or not; if not, the sheath may be affected with damp; if yes, observing whether the circumferential temperature rise of the high-pressure end part exceeds the area of 5K or not and exceeds 45 degrees; if so, the core rod may be corroded and damaged; if not, the sheath may be damaged; for possible sheath breakage, observing whether the breakage position in the picture corresponds to the position with the highest temperature rise or not, and if so, damaging the sheath; if not, the core rod is possibly corroded and damaged; judging whether the highest circumferential temperature rise of the high-pressure end part in the high-humidity environment is lower than the circumferential temperature rise of the same position in the low-humidity environment or not; if yes, the core rod is corroded and damaged; if not, the sheath may be wet. The method can accurately diagnose the defect types of the composite insulator.
Description
Technical Field
The invention relates to the technical field of power equipment diagnosis, in particular to a composite insulator defect classification diagnosis method based on surface temperature distribution.
Background
The line insulator is a device which is arranged between conductors with different electric potentials or between the conductors and a grounding member and can withstand the action of voltage and mechanical stress, and consists of two parts, namely an insulating part and a connecting hardware fitting. Compare traditional ceramic insulator, composite insulator has splendid resistant dirty sudden strain of a muscle characteristic, and the transportation is convenient simultaneously, maintains simply. Since the 20 th century and the 80 th century, the composite insulator is widely applied to ultra-high voltage transmission lines in China, but accidents caused by breakage and flashover of the composite insulator can not only cause long-time power failure accidents, but also seriously threaten the life and property safety of residents under the lines. The line composite insulator is influenced by a production process and an operating environment, and has inevitable hidden defects which can be developed into flashover and fracture accidents. Due to the existence of the hidden defect, the method has very important significance for online detection of the composite insulator of the power transmission line.
At present, surface temperature rise abnormity is considered as early-stage characteristic of abnormal fracture of the composite insulator, tower climbing and unmanned aerial vehicle infrared temperature measurement are widely applied to maintenance work of the line composite insulator, but accurate assessment is difficult to be carried out on specific defect types of the insulator and influences on safe operation of a power transmission line only by taking the highest surface temperature rise as a basis.
Disclosure of Invention
The embodiment of the invention aims to provide a composite insulator defect classification diagnosis method based on surface temperature distribution, which is used for analyzing temperature measurement data by means of environmental conditions and temperature distribution based on a heat production mechanism of different defects in an operation process so as to accurately diagnose the defect types of a composite insulator.
In order to achieve the above object, an embodiment of the present invention provides a method for classifying and diagnosing defects of a composite insulator based on surface temperature distribution, including the following steps:
measuring the temperature of the composite insulator in the axial direction and the circumferential direction under different environmental conditions, and shooting the composite insulator to obtain optical photos corresponding to different detection sections; wherein the detection section comprises a repeating unit of a high voltage end section, a low voltage end section and a composite insulator shed;
processing temperature measurement data to obtain axial temperature rise and circumferential temperature rise of different detection sections of the composite insulator;
judging whether the axial temperature rise of the repeating unit exceeds a first preset threshold value or not, and if so, possibly causing core rod erosion of the composite insulator; if not, judging whether the difference between the highest circumferential temperature rise and the lowest circumferential temperature rise of the high-pressure end section exceeds a second preset threshold value or not;
if not, the composite insulator may have a sheath which is affected with damp; if so, observing whether the area of which the circumferential temperature rise of the high-pressure end section exceeds a third preset threshold exceeds a preset angle range;
if the core rod erosion rate exceeds the preset value, the core rod erosion of the composite insulator may exist; if not, the composite insulator may have a sheath breakage;
for the composite insulator, the sheath damage may exist, the corresponding optical photo and the corresponding temperature measurement data are continuously compared, whether the damage position corresponds to the position with the highest temperature rise or not is observed, and if yes, the composite insulator is confirmed to have the sheath damage; if not, the composite insulator may have core rod erosion;
for the composite insulator, the core rod may be corroded and damaged or the composite insulator may be wetted, and whether the highest circumferential temperature rise of the high-voltage end section in the high-humidity environment is lower than the circumferential temperature rise of the same position in the low-humidity environment is continuously judged;
if yes, directly confirming that the core rod of the composite insulator is corroded and damaged; if not, continuously judging whether the circumferential temperature rise of the high-voltage end section in the low-humidity environment exceeds a fourth preset threshold value, if so, determining that the core rod of the composite insulator is corroded, and if not, determining that the sheath of the composite insulator is damped.
Preferably, the method further comprises:
and if the local temperature rise of the composite insulator which cannot be confirmed exceeds 3K, re-measuring the temperature after a preset time period so as to re-diagnose.
Preferably, the method further comprises:
and measuring and recording the relative humidity of air and the sun direction on site while measuring the temperature of the composite insulator.
Preferably, the thermometric data of each detection zone comprises at least one set of thermometric data with air relative humidity over 80% and at least one set of thermometric data with air relative humidity under 40%;
if sunlight exists in the temperature measurement process, the temperature measurement data of each detection section further comprises at least one group of temperature measurement data 3 hours after sunrise, one group of temperature measurement data at noon and one group of temperature measurement data 3 hours before sunset.
Preferably, the axial and circumferential temperature measurement of the composite insulator specifically includes:
in the axial temperature measurement, at least three points are selected in each detection section of the composite insulator for temperature measurement, and the highest temperature of the three points is taken as the section temperature;
and selecting the detection section with the lowest section temperature for circumferential measurement, selecting the lowest value of the circumferential measurement temperature as a reference value, and performing circumferential temperature measurement on other detection sections with the section temperature higher than the reference value 1K.
Preferably, in circumferential temperature measurement, the true north direction, the northeast direction, the true east direction, the southeast direction, the true south direction, the southwest direction, the true west direction and the northwest direction of the composite insulator are sequentially marked as 0 °, 45 °, 90 °, 135 °, 180 °, 225 °, 270 ° and 315 °, infrared temperature measurement is performed within a range of ± 22.5 ° with each direction as the center, and the highest temperature is selected as temperature measurement data of the direction.
Preferably, the processing of the temperature measurement data to obtain the axial temperature rise and the circumferential temperature rise of different detection sections of the composite insulator specifically includes:
if the temperature measurement data of the detection section in the same day is influenced by sunshine, taking the temperature measurement data 3 hours after sunrise or the temperature measurement data 3 hours before sunset as the temperature measurement data of the detection section;
and calculating the axial temperature rise and the circumferential temperature rise of different detection sections of the composite insulator according to the temperature measurement data of the detection sections and the reference value.
Preferably, if the highest temperature in each set of circumferential temperature measurement data of the detection section corresponding to the lowest section temperature in the same day changes with the change of the solar azimuth, the temperature measurement data of the detection section in the same day is affected by sunlight.
Preferably, the first preset threshold is 1K, the second preset threshold is 3K, the third preset threshold is 5K, the fourth preset threshold is 3K, and the preset angle is 45 °.
Compared with the prior art, the composite insulator defect classification diagnosis method based on surface temperature distribution provided by the embodiment of the invention is based on the heat production mechanism of different defects in the operation process, and analyzes temperature measurement data by means of environmental conditions and temperature distribution so as to accurately diagnose the defect types of the composite insulator.
Drawings
Fig. 1 is a schematic flowchart of a composite insulator defect classification diagnosis method based on surface temperature distribution according to an embodiment of the present invention;
fig. 2 is a simplified flowchart of a method for diagnosing defects of a composite insulator based on surface temperature distribution according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of a composite insulator for a circuit according to an embodiment of the present invention;
fig. 4 is a graph showing the change of the polarization heating power of a composite insulator before moisture absorption according to the change of the electric field strength;
fig. 5 is a graph showing the change of the polarization heating power with the change of the electric field strength after moisture absorption of a composite insulator according to an embodiment of the present invention;
FIG. 6 is a graph showing the variation of circumferential temperature rise of different composite insulator samples in different humidity environments after the sheath is wetted according to an embodiment of the present invention;
FIG. 7 is a graph showing the temperature rise in the circumferential direction after the sheath is damaged and after the core rod is eroded for a composite insulator sample according to an embodiment of the present invention;
fig. 8 is an infrared thermography of local heating caused by other types of defects existing in the composite insulator according to an embodiment of the present invention;
fig. 9 is an infrared thermography of partial discharge caused by erosion of the core rod in the composite insulator according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1, it is a schematic flow chart of a method for classifying and diagnosing defects of a composite insulator based on surface temperature distribution according to the embodiment of the present invention, where the method includes steps S1 to S10:
s1, measuring the temperature of the composite insulator in the axial direction and the circumferential direction under different environmental conditions, and shooting the composite insulator to obtain optical photos corresponding to different detection sections; wherein the detection section comprises a repeating unit of a high voltage end section, a low voltage end section and a composite insulator shed;
s2, processing the temperature measurement data to obtain axial temperature rise and circumferential temperature rise of different detection sections of the composite insulator;
s3, judging whether the axial temperature rise of the repeating unit exceeds a first preset threshold value or not, and if so, judging that the composite insulator may have core rod erosion; if not, judging whether the difference between the highest circumferential temperature rise and the lowest circumferential temperature rise of the high-pressure end section exceeds a second preset threshold value or not;
s4, if not, the composite insulator may have a sheath which is affected with damp; if so, observing whether the area of which the circumferential temperature rise of the high-pressure end section exceeds a third preset threshold exceeds a preset angle range;
s5, if the core rod erosion rate exceeds the first threshold value, the core rod erosion of the composite insulator may exist; if not, the composite insulator may have a sheath breakage;
s6, continuously comparing the corresponding optical photo with the temperature measurement data when the composite insulator is possibly damaged, observing whether the damaged position corresponds to the position with the highest temperature rise or not, and if so, confirming that the composite insulator is damaged; if not, the composite insulator may have core rod erosion;
s7, judging whether the highest circumferential temperature rise of the high-voltage end section in the high-humidity environment is lower than the circumferential temperature rise of the same position in the low-humidity environment or not continuously when the core rod of the composite insulator is corroded and damaged or the sheath of the composite insulator is damped;
s8, if yes, directly confirming that the composite insulator has core rod erosion; if not, continuously judging whether the circumferential temperature rise of the high-voltage end section in the low-humidity environment exceeds a fourth preset threshold value, if so, determining that the core rod of the composite insulator is corroded, and if not, determining that the sheath of the composite insulator is damped.
For convenience of understanding, refer to fig. 2, which is a simplified flowchart of a method for diagnosing defects of a composite insulator based on surface temperature distribution according to the embodiment of the present invention, and fig. 2 can more intuitively illustrate the implementation process of the present invention. Referring to fig. 3, which is a schematic structural diagram of a composite insulator for a line according to the embodiment of the present invention, as can be seen from fig. 3, the composite insulator includes a shed, a high voltage end portion and a low voltage end portion, wherein the shed includes a plurality of repeating units. The following is a detailed description of the practice of the invention.
Specifically, the axial and circumferential temperature of the composite insulator is measured under different environmental conditions, and the composite insulator is photographed to obtain optical photos corresponding to different detection sections; wherein the detection section comprises a repeating unit of a high voltage end section, a low voltage end section and a composite insulator shed.
The temperature measurement refers to measuring the surface temperature of the composite insulator, generally by means of a thermal infrared imager, the measurement is carried out in a manner of tower climbing of handheld equipment or an unmanned aerial vehicle, temperature data need to be recorded in the measurement process, and an infrared thermal image and an optical photo need to be reserved.
Processing the temperature measurement data to obtain axial temperature rise and circumferential temperature rise of different detection sections of the composite insulator; the temperature measurement data is processed, including correction and calculation, so that unreasonable data can be eliminated, and reliable and effective data can be selected for temperature rise calculation.
Firstly, the axial measurement result is judged, and preferably, the temperature rise result measured 3 hours after sunrise in a dry environment is selected as a judgment basis. And (3) removing the high-voltage end section and the low-voltage end section, judging whether the axial temperature rise of the repeating unit exceeds a first preset threshold value, if so, judging that the composite insulator may have core rod corrosion loss and generally considering that the composite insulator may have hardware sealing defects. The first preset threshold may be set to 1K, K being a thermodynamic temperature unit. If the temperature rise of the high-pressure end section exceeds the second preset threshold, the circumferential measurement result is judged, the circumferential measurement result of the high-pressure end section is used as a judgment basis, whether the difference between the highest circumferential temperature rise and the lowest circumferential temperature rise of the high-pressure end section exceeds the second preset threshold or not is judged, and the second preset threshold can be set to be 3K.
If not, the composite insulator may have a sheath which is affected with damp and needs to be further confirmed; if so, observing whether the area of the high-pressure end section with the circumferential temperature rise exceeding a third preset threshold exceeds a preset angle range, wherein the third preset threshold can be set to be 5K, the preset angle can be 45 degrees, namely observing whether the area with the temperature rise exceeding 5K exceeds the 45-degree range.
If the corrosion rate exceeds the preset value, the core rod of the composite insulator is possibly corroded and damaged, and further confirmation is needed; if not, the composite insulator may be damaged, and the position of the heat generated on the surface of the sheath needs to be further confirmed by a photograph.
If the composite insulator is possibly damaged, continuously comparing the corresponding optical photo with the temperature measurement data, observing whether the damaged position of the sheath in the optical photo corresponds to the position of the highest temperature rise in the temperature measurement data, and if so, confirming that the composite insulator is damaged; if not, the core rod of the composite insulator may be corroded and damaged, and further confirmation is needed.
For the composite insulator, the core rod may be corroded and damaged or the sheath may be damp, the measurement results under different humidity needs to be judged, that is, whether the highest circumferential temperature rise of the high-voltage end section under the high-humidity environment is lower than the circumferential temperature rise of the same position under the low-humidity environment is continuously judged.
If yes, directly confirming that the core rod of the composite insulator is corroded and damaged; if not, continuously judging whether the circumferential temperature rise of the high-voltage end section under the low-humidity environment exceeds a fourth preset threshold value, if so, determining that the core rod of the composite insulator is corroded, and if not, determining that the sheath of the composite insulator is damped. The fourth preset threshold may be set to 3K.
In addition, the composite insulator only with core rod corrosion or sheath damage is replaced in time, the composite insulator only affected by the sheath damp can still normally operate, and the safe operation of the power transmission line cannot be affected in a short period.
According to the composite insulator defect classification diagnosis method based on the surface temperature distribution, provided by the embodiment 1 of the invention, temperature measurement data are analyzed by means of environmental conditions and temperature distribution based on the heat production mechanism of different defects in the operation process, so that the defect types of the composite insulator can be accurately diagnosed.
As an improvement of the above scheme, the method further comprises:
and if the local temperature rise of the composite insulator which cannot be confirmed exceeds 3K, re-measuring the temperature after a preset time period so as to re-diagnose.
Specifically, for the composite insulator which cannot be confirmed, if the local temperature rise exceeds 3K, the temperature needs to be measured again after a preset time period to perform re-diagnosis. An unidentifiable composite insulator refers to a composite insulator that does not meet any of the above criteria. The preset time period can be set to be half a year, namely, the infrared temperature measurement is carried out again after half a year, and diagnosis is carried out according to the flow.
As an improvement of the above scheme, the method further comprises:
and measuring and recording the relative humidity of air and the sun direction on site while measuring the temperature of the composite insulator.
Specifically, while the composite insulator is subjected to temperature measurement, the relative humidity of air and the sun position on the site are measured and recorded, so that whether the surface temperature data of the composite insulator is influenced by sunlight and air humidity or not is obtained according to the data, and whether the core rod corrosion damage, the sheath damage and the sheath dampness defect exist in the composite insulator or not is deduced.
As an improvement of the above scheme, the temperature measurement data of each detection section comprises at least one group of temperature measurement data with air relative humidity over 80% and at least one group of temperature measurement data with air relative humidity under 40%;
if sunlight exists in the temperature measurement process, the temperature measurement data of each detection section further comprises at least one group of temperature measurement data 3 hours after sunrise, one group of temperature measurement data at noon and one group of temperature measurement data 3 hours before sunset.
Specifically, the thermometric data of each detection zone comprises at least one set of thermometric data with air relative humidity over 80% and at least one set of thermometric data with air relative humidity under 40%. Of course, other relative humidity thermometry data may be included in addition to the two sets of 80% and 40%.
If sunlight exists in the temperature measurement process, the temperature measurement data of each detection section further comprises at least one group of temperature measurement data 3 hours after sunrise, one group of temperature measurement data at noon and one group of temperature measurement data 3 hours before sunset.
That is, for the same detection section, the measured data includes at least two sets of temperature measurement data with different relative humidity of air, preferably, the relative humidity of air is slightly different, and the data measured in one day includes at least three sets of data to observe whether the data is affected by sunshine or not, thereby excluding sunshine factors, and the above 3 hours can be set as 2 hours or 1 hour.
As an improvement of the above scheme, the measuring the temperature of the composite insulator in the axial direction and the circumferential direction specifically includes:
in the axial temperature measurement, at least three points are selected in each detection section of the composite insulator for temperature measurement, and the highest temperature of the three points is taken as the section temperature;
and selecting the detection section with the lowest section temperature for circumferential measurement, selecting the lowest value of the circumferential measurement temperature as a reference value, and performing circumferential temperature measurement on other detection sections with the section temperature higher than the reference value 1K.
Specifically, in general, composite insulator surface temperature measurement follows the principle of axial first and circumferential second. In the axial temperature measurement, temperature measurement equipment is arranged on the north side of the composite insulator through an unmanned aerial vehicle or a hand, at least three points are selected in each detection section of the composite insulator for temperature measurement, and the highest temperature of the three points is taken as the section temperature.
In order to reduce the workload of circumferential measurement of the detection sections, the detection section with the lowest temperature of the sections is selected for circumferential measurement, the lowest value of the circumferential measurement temperature is selected as a reference value, and circumferential temperature measurement is carried out on other detection sections with the section temperature higher than the reference value 1K, so that circumferential temperature measurement on all the detection sections is avoided.
As an improvement of the above scheme, in circumferential temperature measurement, the true north direction, the northeast direction, the true east direction, the southeast direction, the true south direction, the southwest direction, the true west direction and the northwest direction of the composite insulator are sequentially marked as 0 °, 45 °, 90 °, 135 °, 180 °, 225 °, 270 ° and 315 °, infrared temperature measurement is performed within a range of ± 22.5 ° with each direction as the center, and the highest temperature is selected as temperature measurement data of the direction.
Specifically, in circumferential temperature measurement, the true north, the northeast, the true east, the southeast, the southwest and the northwest of the composite insulator are sequentially marked as 0 °, 45 °, 90 °, 135 °, 180 °, 225 °, 270 ° and 315 °, and infrared temperature measurement is performed within a range of ± 22.5 ° with each azimuth as the center, that is, measurement data within a range of 22.5 ° with each angle as the center can be used as effective data, and the highest temperature in the measurement data of a certain azimuth is selected as the temperature measurement data of the azimuth.
As an improvement of the above scheme, the processing of the temperature measurement data to obtain the axial temperature rise and the circumferential temperature rise of the different detection sections of the composite insulator specifically includes:
if the temperature measurement data of the detection section in the same day is influenced by sunshine, taking the temperature measurement data 3 hours after sunrise or the temperature measurement data 3 hours before sunset as the temperature measurement data of the detection section;
and calculating the axial temperature rise and the circumferential temperature rise of different detection sections of the composite insulator according to the temperature measurement data of the detection sections and the reference value.
Specifically, if the temperature measurement data of the detection section on the same day is affected by sunlight, the temperature measurement data 3 hours after sunrise or the temperature measurement data 3 hours before sunset is used as the temperature measurement data of the detection section. Generally, with respect to the temperature measurement data 3 hours after sunrise, the temperature rise affecting the circumferential sun shine angle is corrected according to the temperature rise at the same angle 3 hours before sunset, that is, the minimum value of the temperature measurement data 3 hours after sunrise and the temperature measurement data 3 hours before sunset is taken as the temperature measurement data.
And subtracting the reference values from the temperature measurement data of the detection sections one by one according to the temperature measurement data and the reference values of the detection sections to obtain the axial temperature rise and the circumferential temperature rise of different detection sections of the composite insulator. The reference value is the lowest circumferential temperature of the detection zone where the zone temperature is lowest.
As an improvement of the above scheme, if the highest temperature in each set of circumferential temperature measurement data of the detection section corresponding to the lowest section temperature in the same day changes with the change of the solar azimuth, the temperature measurement data of the detection section in the same day is affected by sunlight.
Specifically, if the highest temperature in each set of circumferential temperature measurement data of the detection section corresponding to the lowest temperature of the section in the same day changes with the change of the solar azimuth, the temperature measurement data of the detection section in the same day is affected by the sunlight. That is, whether the highest temperature has a trend from 90 ° to 180 ° to 270 °, if so, it is proved that the local heating of the insulator is affected by the sunlight. Here 90 ° corresponds to the east orientation, 180 ° to the south orientation and 270 ° to the west orientation, i.e. coinciding with the sun orientation.
As an improvement of the above scheme, the first preset threshold is 1K, the second preset threshold is 3K, the third preset threshold is 5K, the fourth preset threshold is 3K, and the preset angle is 45 °.
Specifically, the first preset threshold is 1K, the second preset threshold is 3K, the third preset threshold is 5K, the fourth preset threshold is 3K, and the preset angle is 45 °. The preset values are manually set according to experience, and with the research depth and the improvement of the alignment accuracy, the preset values may be changed correspondingly, and the preset values are also changed correspondingly in the judgment process.
In order to deepen the understanding of the invention, the invention explains the heating mechanism of the composite insulator, and analyzes the heating states of the composite insulators with different defect types under different environments under laboratory conditions.
(1) Heating mechanism of composite insulator
The local heating of the composite insulator detected by using the thermal infrared imager has the following three possibilities from the theoretical point of view:
a. under the influence of sunlight angle, the different positions of the insulator have different absorption and reflection radiation energy, so that the surface temperature distribution observed by the thermal infrared imager is different.
b. The high field intensity region has polarization heating after the sheath is affected with damp. The water absorption test result shows that the surface of the sheath of the composite insulator can absorb a certain amount of water in humid air. The water molecules are polar molecules and have inherent electric moments, namely the action centers of positive charges and negative charges never coincide, so that the water molecules can deflect under the action of an electric field force. Influenced by an alternating electric field, water molecules deflect repeatedly under the action of the electric field force, and certain damping effect exists in the deflection process, so that loss can be generated in the rotation process of overcoming the damping effect. The polarization loss of the composite insulator sheath is influenced by the water absorption amount and the electric field intensity, when the environmental humidity is high, the polarization loss of the high-voltage end part with the high electric field intensity is remarkably increased, and when the polarization loss exceeds the heat dissipation level, heat is continuously accumulated, so that the temperature rise of the high-voltage end part is abnormal. Referring to fig. 4 and 5, graphs of the change of the polarization heating power with the change of the electric field strength before and after moisture absorption of the composite insulator provided by the embodiment of the invention are respectively shown. From the comparison between fig. 4 and fig. 5, it can be seen that the polarization heating power of the composite insulator is significantly increased after moisture absorption.
c. The composite insulator generates heat due to partial discharge. The surface and the inside of the composite insulator are likely to generate partial discharge under the influence of sheath breakage and hardware sealing failure. On one hand, after the sheath is damaged, the electric field is distorted at the damaged position due to the accumulation of moisture and the change of the surface appearance, so that partial discharge is caused; on the other hand, the epoxy resin core rod used by the composite insulator is made of hydrophilic materials, when the end hardware is sealed and loses efficacy, moisture can be axially diffused along the core rod, so that the original electric field distribution is changed, and partial discharge possibly occurs at a higher electric field intensity position. The generation of partial discharge can release a large amount of energy in a tiny area, so that the local temperature rise is obviously increased, and the surface temperature change of the composite insulator is finally shown to different degrees under the influence of the heat conduction performance of the jacket and the core rod material.
(2) Differences in surface temperature distribution due to different types of defects
Carrying out infrared temperature measurement on the composite insulators with different types of defects in a laboratory environment, and summarizing the heating characteristics:
a. local temperature rise due to sunlight angle difference: the composite insulator has the advantages that the composite insulator exists only under the condition that sunlight can directly irradiate the composite insulator, and the peripheral temperature distribution of the composite insulator has obvious change within one day due to different sunlight irradiation angles at sunrise time, noon time and sunset time, corresponds to the sunlight angle, and shows the same change rule at different positions in the axial direction;
b. local temperature rise due to damp sheath: the abnormal heating gradually disappears along with the reduction of the air humidity only when the air humidity is in a rainy day with larger air humidity or in a sunny day after rain. The heating position only exists in the high-voltage end or the low-voltage end of the sheath with high electric field intensity in the axial direction, the heating area is usually not more than 3cm, the heating temperature rise difference at different positions in the circumferential direction is small, the maximum temperature rise is not more than 10K, and the circumferential temperature difference is not more than 3K. Referring to fig. 6, it is a graph showing the circumferential temperature rise variation of different composite insulator samples provided by this embodiment of the present invention in different humidity environments after the sheath is affected with moisture. Corresponding to the field photo, the heating insulator usually has the phenomenon of serious high-voltage end dirt accumulation or damaged equalizing ring;
c. local temperature rise due to sheath breakage: the local temperature rise is not influenced by weather conditions, the heating position is possibly arranged at any position in the axial direction and the circumferential direction, the heating temperature rise is high, the surface temperature rise of other positions on the periphery is in sharp contrast, the maximum temperature rise is more than 10K, the temperature rise of other positions in the circumferential direction is less than 3K, and the corresponding sheath damage point can be found at the highest point of the temperature rise through temperature distribution;
d. local temperature rise caused by local discharge in the core rod: the local temperature rise is not influenced by weather conditions, the heating position exists in a section of area starting from the high-pressure end or the low-pressure end in the axial direction, and the heating area is usually more than 3cm and is in a segmented or continuous shape; the heat generating area can only cover 180 degrees or more in the circumferential direction, and the temperature rise is distinct. Such exothermic temperature increases are generally higher than 10K, up to 60K or more, while the temperature difference developed in the circumferential direction can exceed 5K.
Referring to fig. 7, it is a graph showing the corresponding circumferential temperature rise of the composite insulator sample provided in this embodiment of the present invention after the sheath is damaged and after the core rod is eroded. As can be seen from fig. 7, the region where the circumferential temperature rise of the composite insulator with the damaged sheath exceeds 5K is much smaller than the region where the circumferential temperature rise of the composite insulator with the core rod eroded exceeds 5K. For the sake of safety, in the present invention, the preset angle is set to 45 °, and whether the sheath damage or the core rod erosion damage is determined according to whether the region in which the circumferential temperature rise exceeds 5K exceeds the range of 45 °.
In addition, referring to fig. 8 and fig. 9, an infrared thermal image of local heating caused by other types of defects of the composite insulator and an infrared thermal image of local discharge caused by erosion of the core rod are respectively shown. As can be seen from fig. 8 and 9, the infrared thermograph can clearly distinguish that the local temperature rise caused by the local discharge in the core rod is different from other types, and further distinguish the specific defects of the composite insulator by comparing the circumferential temperature rise parameters.
In summary, the method for classifying and diagnosing the defects of the composite insulator based on the surface temperature distribution provided by the embodiment of the invention has the following advantages: a. the core rod corrosion damage, the sheath damage and the sheath damp defects of the composite insulator can be diagnosed in a line running state, and the insulator which is possible to rapidly reduce the electrical and mechanical properties in a short period can be replaced as soon as possible, so that the breakage and flashover accidents are effectively avoided; b. based on the infrared temperature measurement technology commonly adopted in the operation and maintenance process of the power transmission line, the method has the characteristics of wide application range, high detection speed and low popularization difficulty, and can meet the requirements of classification diagnosis and maintenance of the defects of the composite insulators of the power transmission line; c. the limitation of the existing infrared temperature measurement method is overcome, the influence of the sunshine angle on the measurement result is avoided, the measurement results under different air humidity are fully utilized, and the heating temperature rise of the insulator is described from two dimensions of the axial direction and the axial direction; d. the construction influence and the increase of equipment cost caused by blind replacement of the line composite insulator are effectively avoided, and after the defect types of the composite insulator are confirmed, the defect types are relieved through effective measures, so that the service life of the composite insulator can be prolonged.
While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.
Claims (9)
1. A composite insulator defect classification diagnosis method based on surface temperature distribution is characterized by comprising the following steps:
measuring the temperature of the composite insulator in the axial direction and the circumferential direction under different environmental conditions, and shooting the composite insulator to obtain optical photos corresponding to different detection sections; wherein the detection section comprises a high pressure end section, a low pressure end section, and a shed, wherein the shed comprises a plurality of repeating units;
processing temperature measurement data to obtain axial temperature rise and circumferential temperature rise of different detection sections of the composite insulator;
judging whether the axial temperature rise of the repeating unit exceeds a first preset threshold value or not, and if so, possibly causing core rod erosion of the composite insulator; if not, judging whether the difference between the highest circumferential temperature rise and the lowest circumferential temperature rise of the high-pressure end section exceeds a second preset threshold value or not;
if not, the composite insulator may have a sheath which is affected with damp; if so, observing whether the area of which the circumferential temperature rise of the high-pressure end section exceeds a third preset threshold exceeds a preset angle range;
if the core rod erosion rate exceeds the preset value, the core rod erosion of the composite insulator may exist; if not, the composite insulator may have a sheath breakage;
for the composite insulator, the sheath damage may exist, the corresponding optical photo and the corresponding temperature measurement data are continuously compared, whether the damage position corresponds to the position with the highest temperature rise or not is observed, and if yes, the composite insulator is confirmed to have the sheath damage; if not, the composite insulator may have core rod erosion;
for the composite insulator, the core rod may be corroded and damaged or the composite insulator may be wetted, and whether the highest circumferential temperature rise of the high-voltage end section in the high-humidity environment is lower than the circumferential temperature rise of the same position in the low-humidity environment is continuously judged;
if yes, directly confirming that the core rod of the composite insulator is corroded and damaged; if not, continuously judging whether the circumferential temperature rise of the high-voltage end section in the low-humidity environment exceeds a fourth preset threshold value, if so, determining that the core rod of the composite insulator is corroded, and if not, determining that the sheath of the composite insulator is damped.
2. The method for classifying and diagnosing the defects of the composite insulator based on the surface temperature distribution as set forth in claim 1, further comprising:
and if the local temperature rise of the composite insulator which cannot be confirmed exceeds 3K, re-measuring the temperature after a preset time period so as to re-diagnose.
3. The method for classifying and diagnosing the defects of the composite insulator based on the surface temperature distribution as set forth in claim 1, further comprising:
and measuring and recording the relative humidity of air and the sun direction on site while measuring the temperature of the composite insulator.
4. The method for classifying and diagnosing the defects of the composite insulator based on the surface temperature distribution as claimed in claim 1, wherein the temperature measurement data of each detection section comprises at least one group of temperature measurement data with air relative humidity more than 80% and at least one group of temperature measurement data with air relative humidity less than 40%;
if sunlight exists in the temperature measurement process, the temperature measurement data of each detection section further comprises at least one group of temperature measurement data 3 hours after sunrise, one group of temperature measurement data at noon and one group of temperature measurement data 3 hours before sunset.
5. The method for classifying and diagnosing the defects of the composite insulator based on the surface temperature distribution as claimed in claim 4, wherein the step of measuring the temperature of the composite insulator in the axial direction and the circumferential direction specifically comprises the steps of:
in the axial temperature measurement, at least three points are selected in each detection section of the composite insulator for temperature measurement, and the highest temperature of the three points is taken as the section temperature;
and selecting the detection section with the lowest section temperature for circumferential measurement, selecting the lowest value of the circumferential measurement temperature as a reference value, and performing circumferential temperature measurement on other detection sections with the section temperature higher than the reference value 1K.
6. The method for classifying and diagnosing the defects of the composite insulator based on the surface temperature distribution as claimed in claim 5, wherein in the circumferential temperature measurement, the true north direction, the northeast direction, the true east direction, the southeast direction, the southwest direction, the true west direction and the northwest direction of the composite insulator are sequentially marked as 0 °, 45 °, 90 °, 135 °, 180 °, 225 °, 270 ° and 315 °, and infrared temperature measurement is performed within a range of ± 22.5 ° with each direction as the center, and the highest temperature is selected as the temperature measurement data of the direction.
7. The method for classifying and diagnosing the defects of the composite insulator based on the surface temperature distribution as claimed in claim 5, wherein the step of processing the temperature measurement data to obtain the axial temperature rise and the circumferential temperature rise of different detection sections of the composite insulator specifically comprises the steps of:
if the temperature measurement data of the detection section in the same day is influenced by sunshine, taking the temperature measurement data 3 hours after sunrise or the temperature measurement data 3 hours before sunset as the temperature measurement data of the detection section;
and calculating the axial temperature rise and the circumferential temperature rise of different detection sections of the composite insulator according to the temperature measurement data of the detection sections and the reference value.
8. The method as claimed in claim 7, wherein if the highest temperature of each set of circumferential temperature measurement data of the detection section corresponding to the lowest section temperature on the same day changes with the change of the solar azimuth, the temperature measurement data of the detection section on the same day is affected by sunshine.
9. The method for classifying and diagnosing the defects of the composite insulator based on the surface temperature distribution as claimed in claim 1, wherein the first preset threshold value is 1K, the second preset threshold value is 3K, the third preset threshold value is 5K, the fourth preset threshold value is 3K, and the preset angle is 45 °.
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