CN111879483B - Cable terminal oil leakage detection method and system based on infrared thermal imaging - Google Patents
Cable terminal oil leakage detection method and system based on infrared thermal imaging Download PDFInfo
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Abstract
The invention belongs to the technical field of cable terminal liquid level detection, and particularly relates to a cable terminal oil leakage detection method and system based on infrared thermal imaging. The method comprises the following steps: measuring the relative distance of the cable terminal and calculating the height of the cable terminal; correcting the infrared imaging parameters of the image processing software based on the relative distance and other influence factors; acquiring an infrared image of the cable terminal, and performing image processing on the infrared image through image processing software to determine a liquid level line of the cable terminal; identifying an infrared image of the cable terminal with a liquid level line and calculating the liquid level height of the cable terminal; and calculating an oil leakage ratio based on the liquid level height of the cable terminal and the height of the cable terminal, and comparing the oil leakage ratio with a preset oil leakage threshold value to obtain the oil leakage state of the cable terminal. According to the invention, the power-off detection of the cable terminal is not required, and the oil leakage detection of the cable terminal can be safely, conveniently and quickly carried out in a non-contact detection mode.
Description
Technical Field
The invention belongs to the technical field of cable terminal liquid level detection, and particularly relates to a cable terminal oil leakage detection method and system based on infrared thermal imaging.
Background
The cable termination is a key link affecting the reliable operation of the cable line. Among them, the wet (oil) cable termination accounts for a large proportion of the operating cable terminations. At present, due to factors such as deterioration of a sealing ring and poor mounting process, oil leakage at a wet (oil) cable terminal sometimes occurs. The reduction of the amount of oil in the terminal will result in a change in the distribution of the electric field, causing a change in the creepage distance of the insulation in the cable, and eventually possibly leading to a breakdown of the cable terminal.
For the terminal oil leakage defect, operation and maintenance personnel usually adopt a method of observation and measurement after power failure to perform oil leakage inspection, on one hand, the method reduces the power supply reliability of a cable line, and on the other hand, the risk of introducing moisture or impurities into insulating oil exists during cover opening inspection. And the detection method adopting infrared thermal imaging can effectively avoid the problems.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides the cable terminal oil leakage detection method and system based on the infrared thermal imaging, power-off detection of the cable terminal is not needed, and oil leakage detection of the cable terminal can be safely, conveniently and quickly performed through a non-contact detection mode.
In a first aspect, the invention provides a cable terminal oil leakage detection method based on infrared thermal imaging, which comprises the following steps:
Measuring the relative distance of the cable terminal, and calculating the height of the cable terminal according to the relative distance;
correcting the infrared imaging parameters of the image processing software based on the relative distance and other influence factors;
acquiring an infrared image of the cable terminal, processing the infrared image through the image processing software, and determining a liquid level line of the cable terminal;
identifying the infrared image of the cable terminal with the liquid level line to obtain the number of oil-deficient umbrella skirts and the number of integral umbrella skirts of the cable terminal so as to calculate the liquid level height of the cable terminal;
calculating an oil leakage ratio based on the liquid level height of the cable terminal and the height of the cable terminal, and comparing the oil leakage ratio with a preset oil leakage threshold value to obtain the oil leakage state of the cable terminal.
Preferably, the measuring a relative distance of the cable termination and calculating a height of the cable termination according to the relative distance includes:
measuring a first relative distance S1 and a first included angle alpha 1 between a current detection point A and an upper edge C of a first shed of the cable terminal;
measuring a second relative distance S2 and a second included angle alpha 2 between the current detection point A and the upper edge B of the flange on the cable terminal;
Calculating a relative angle alpha between the straight line AC and the straight line AB based on the first angle alpha 1 and the second angle alpha 2;
calculating the height H of the cable terminal through the first relative distance S1, the second relative distance S2 and the relative included angle alpha.
Preferably, the calculation formula for calculating the height H of the cable termination is as follows:
preferably, the other influencing factors include the surface emissivity, the ambient temperature and the relative humidity of the measured material.
Preferably, the correcting the infrared imaging parameter of the image processing software based on the relative distance and other influence factors specifically includes:
the measurement distance parameter is set to (S1+ S2)/2;
if the terminal is a composite terminal or a terminal coated with an RTV porcelain bushing or a terminal coated with an HTV porcelain bushing, the surface radiance parameter is set to be 0.95; if the porcelain sleeve terminals are other porcelain sleeve terminals, the surface radiance parameter is set to be 0.92;
the ambient temperature and the relative humidity are set according to actual measurement values.
Preferably, the image processing software processes the infrared image to determine a liquid level line of the cable terminal, specifically:
the image processing software carries out regional analysis on the infrared image, frames out the image of the cable terminal from the infrared image, and calculates the average temperature T of the cable terminal based on the image of the cable terminal selected by the frames ave；
And correcting the upper and lower temperature limiting marks of the infrared image based on the average temperature, and adjusting the contrast of the infrared image through the corrected upper and lower temperature limiting marks so as to clearly display the liquid level line of the cable terminal in the image of the cable terminal.
Preferably, the correcting the upper and lower temperature limit scales of the infrared image based on the average temperature specifically includes:
defining a lower temperature limit of the infrared image as T1, and T1 ═ Tave；
Defining an upper temperature limit of the infrared image as T2, and T2 ═ Tave+(1～2)℃。
Preferably, the calculation formula for calculating the liquid level height of the cable termination is:
h＝(L1-L2)*H/L1；
wherein h is the liquid level height, L1 is the number of integral umbrella skirt pieces, and L2 is the number of oil-deficient umbrella skirt pieces.
Preferably, the calculating of the oil leakage ratio specifically comprises:
△h＝(H-h)/H*100％；
where Δ h is the oil leakage ratio.
In a second aspect, the present invention provides an infrared thermal imaging-based cable terminal oil leakage detection system, which is suitable for the infrared thermal imaging-based cable terminal oil leakage detection method in the first aspect, and includes:
the measurement calculation unit is used for measuring the relative distance of the cable terminal and calculating the height of the cable terminal according to the relative distance;
The parameter correcting unit is used for correcting the infrared imaging parameters of the image processing software based on the relative distance and other influence factors;
the acquisition processing unit is used for acquiring the infrared image of the cable terminal, processing the infrared image through the image processing software and determining the liquid level line of the cable terminal;
the liquid level calculating unit is used for identifying the infrared image of the cable terminal with the liquid level line to obtain the number of oil-deficient umbrella skirts and the number of integral umbrella skirts of the cable terminal so as to calculate the liquid level height of the cable terminal;
and the comparison and judgment unit is used for calculating an oil leakage ratio based on the liquid level height of the cable terminal and the height of the cable terminal, and comparing the oil leakage ratio with a preset oil leakage threshold value to obtain the oil leakage state of the cable terminal.
According to the technical scheme, the power failure detection of the cable terminal is not required, and the oil leakage detection of the cable terminal can be safely, conveniently and quickly performed in a non-contact detection mode.
Drawings
In order to more clearly illustrate the detailed description of the invention or the technical solutions in the prior art, the drawings that are needed in the detailed description of the invention or the prior art will be briefly described below. Throughout the drawings, like elements or portions are generally identified by like reference numerals. In the drawings, elements or portions are not necessarily drawn to scale.
Fig. 1 is a flowchart of a cable terminal oil leakage detection method based on infrared thermal imaging in this embodiment;
FIG. 2 is a flow chart of a specific method for calculating the height of the cable termination in the present embodiment;
FIG. 3 is a flowchart of a specific method for determining the liquid level line of the cable termination by the image processing software according to the embodiment;
fig. 4 is a schematic structural diagram of an oil leakage detection system of a cable terminal based on infrared thermal imaging in this embodiment;
fig. 5 is a schematic diagram illustrating the calculation of the distance measurement performed by the infrared imager on the cable terminal in this embodiment.
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 some, not all, embodiments of the present invention. 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.
It will be understood that the terms "comprises" and/or "comprising," when used in this specification and the appended claims, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
It is also to be understood that the terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in this specification and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.
It should be further understood that the term "and/or" as used in this specification and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.
As used in this specification and the appended claims, the term "if" may be interpreted contextually as "when", "upon" or "in response to a determination" or "in response to a detection". Similarly, the phrase "if it is determined" or "if a [ described condition or event ] is detected" may be interpreted contextually to mean "upon determining" or "in response to determining" or "upon detecting [ described condition or event ]" or "in response to detecting [ described condition or event ]".
The first embodiment is as follows:
the embodiment provides a cable terminal oil leakage detection method based on infrared thermal imaging, as shown in fig. 1, including the following steps:
s1, measuring the relative distance of the cable terminal, and calculating the height of the cable terminal according to the relative distance;
s2, correcting the infrared imaging parameters of the image processing software based on the relative distance and other influencing factors;
s3, acquiring an infrared image of the cable terminal, processing the infrared image through the image processing software, and determining a liquid level line of the cable terminal;
s4, identifying the infrared image of the cable terminal with the liquid level line to obtain the number of oil-lacking umbrella skirts and the number of integral umbrella skirts of the cable terminal so as to calculate the liquid level height of the cable terminal;
s5, calculating an oil leakage ratio based on the liquid level height of the cable terminal and the height of the cable terminal, and comparing the oil leakage ratio with a preset oil leakage threshold value to obtain the oil leakage state of the cable terminal.
The detection scheme of the embodiment is mainly used for filling the liquid into the cable terminal with the inner insulation, and the cable terminal needs to be determined at a proper detection position before the detection of the cable terminal. In the embodiment, the oil leakage detection of the cable terminal is based on the liquid level detection of the cable terminal, and the liquid level detection of the cable terminal belongs to the category of infrared diagnosis accurate detection, so that the general detection requirements are met, the influence of ambient wind speed, direct sunlight, nearby thermal radiation sources, strong electromagnetic fields and the like on a detection result is paid attention to, the whole view of the detected terminal is ensured to be filled with the whole view field of the infrared imager as far as possible, and the infrared imager can adopt a long-focus infrared lens if necessary.
In this embodiment, be equipped with laser range finding module and image acquisition module in the infrared imaging appearance, detect the relative distance of infrared imaging appearance and cable terminal through the laser range finding module, gather infrared image through the image acquisition module, not only be limited to in this embodiment and measure distance and gather the image through the infrared imaging appearance, adopt other equipment to realize the mode of above-mentioned two kinds of functions, all in the protection range of this embodiment. Fig. 5 is a schematic diagram illustrating the calculation of the distance measurement performed by the infrared imager on the cable termination in this embodiment.
In step S1, the measuring step measures a relative distance of the cable terminal, and calculates a height of the cable terminal according to the relative distance, as shown in fig. 2, specifically includes:
s11, measuring a first relative distance S1 and a first included angle alpha 1 between a current detection point A and the upper edge C of the first shed of the cable terminal;
s12, measuring a second relative distance S2 and a second included angle alpha 2 between the current detection point A and the upper edge B of the flange on the cable terminal;
s13, calculating a relative included angle alpha between the straight line AC and the straight line AB based on the first included angle alpha 1 and the second included angle alpha 2;
s14, calculating the height H of the cable terminal through the first relative distance S1, the second relative distance S2 and the relative included angle alpha.
In this embodiment, after the cable terminal is determined to be at the proper detection position, the infrared imager first aims at the upper edge C of the first shed of the cable terminal, measures a first relative distance S1 and a first included angle α 1 (included angle between the straight line AC and the horizontal line), and then rotates downward in the same working planeAnd (3) aiming at the upper edge B of the flange on the cable terminal at a certain angle, and measuring to obtain a second relative distance S2 and a second included angle alpha 2 (an included angle between a straight line AB and a horizontal line). And subtracting the second included angle alpha 2 from the first included angle alpha 1 to obtain a relative included angle alpha between the straight line AC and the straight line AB. Let the perpendicular point from B to the straight line AC be O and the perpendicular distance be d, then d-S2 sin α, OC-S1-S2 cos α,
in this embodiment, the infrared imager may perform distance measurement, may also collect an infrared image, and processes the infrared image through image processing software, but before processing the infrared image, the infrared imaging parameters of the image processing software need to be set. The infrared imaging is influenced by factors such as relative distance, surface radiance of the detected material, ambient temperature, relative humidity and the like.
In step S2, the correcting the infrared imaging parameter of the image processing software based on the relative distance and other influence factors specifically includes:
The measured distance parameter is set to (S1+ S2)/2;
if the terminal is a composite terminal or a terminal coated with an RTV porcelain bushing or a terminal coated with an HTV porcelain bushing, the surface radiance parameter is set to be 0.95; if the porcelain sleeve terminals are other porcelain sleeve terminals, the surface radiance parameter is set to be 0.92;
the ambient temperature and the relative humidity are set according to actual measurement values.
According to the embodiment, the infrared imaging parameters are corrected, so that the subsequent imaging effect is clearer and more accurate. After the parameters are corrected, the acquired infrared image can be imaged by adopting image processing software.
In step S3, the image processing software processes the infrared image to determine a liquid level line of the cable terminal, as shown in fig. 3, specifically:
s31, the image processing software carries out region analysis on the infrared image, frames out the image of the cable terminal from the infrared image, and frames out the cable terminal based on the imageImage of the end calculates the average temperature T of the cable terminationave；
S32, correcting the upper and lower temperature limiting marks of the infrared image based on the average temperature, adjusting the contrast of the infrared image through the corrected upper and lower temperature limiting marks, and further clearly displaying the liquid level line of the cable terminal in the image of the cable terminal.
In the embodiment, the acquired infrared image should be as complete and clear as possible, the image information should include the full view from the lower flange to the wire outlet rod of the cable terminal, so that the image of the cable terminal can be conveniently selected from the infrared image, and the image processing software can automatically calculate the average temperature T of the cable terminal according to the image of the framed cable terminal after framingave. Then, the upper and lower temperature limits of the infrared image are corrected based on the average temperature, and the lower temperature limit T1 of the infrared image is set to Tave(ii) a The upper limit temperature scale T2 of the infrared image is set to TaveAnd (1-2) DEG C (the value of the temperature scale can be flexibly adjusted according to the display effect of the image). The contrast of the infrared image is directly related to the setting of the temperature scale, and the proper contrast can more intuitively reflect the position of the liquid level line of the cable terminal, so that the infrared image contrast is adjusted by correcting the temperature scale, and the liquid level line of the cable terminal is displayed more intuitively and clearly.
In this embodiment, the image of the cable terminal is analyzed by image recognition, so that the number of oil-starved sheds L2 (i.e., the number of sheds above the liquid level line) and the number of overall sheds L1 (for the number of sheds, if the external insulation adopts a large and small shed structure, the measurement is performed in groups of one large and one small) of the cable terminal are obtained, and the liquid level height H of the cable terminal is calculated as (L1-L2) × H/L1.
In this embodiment, the oil leakage ratio Δ H can be calculated by using the liquid level height H of the cable terminal and the height H of the cable terminal, where Δ H is (H-H)/H100%, and the oil leakage ratio is the ratio of the oil leakage part to the height of the cable terminal. And finally, comparing the oil leakage ratio with a preset oil leakage threshold value to obtain the oil leakage state of the cable terminal. At present, the power industry has not formed a unified standard for determining the oil leakage degree of a cable terminal, so that when an oil leakage threshold is set, the oil leakage threshold may be set according to the importance degree of a cable line corresponding to the cable terminal, the oil leakage threshold of a primary cable line is slightly lower (for example, set to 10%), and the oil leakage threshold of a secondary cable line may be appropriately relaxed (for example, set to 20%). If the oil leakage ratio exceeds the oil leakage threshold value, the technical scheme of the embodiment can perform early warning in modes of voice/information/mails and the like, so that the operation and maintenance personnel can find abnormal oil leakage states in time, the maintenance plan can be arranged in time, the power failure accident can be avoided, and if the oil leakage ratio does not exceed the oil leakage threshold value, the operation and maintenance personnel can perform daily work patrol by adopting a mode of appropriately shortening the patrol period.
To sum up, compared with the prior art, the technical scheme of the embodiment has the following beneficial effects:
1. By adopting a non-contact oil leakage detection mode, compared with the existing contact detection mode, the method does not need to perform power failure detection, does not influence the normal operation of the cable, and can perform oil leakage detection safely and quickly.
2. The cable termination liquid level detection mode is easy and convenient to operate, based on the existing infrared imager or other equipment, does not need to newly increase detection equipment, and is suitable for large-area popularization and application.
3. The quantitative calculation of the height of the liquid level at the cable terminal is realized, the oil leakage state at the cable terminal can be accurately detected and the oil leakage early warning can be realized, and therefore a more visual and scientific overhaul suggestion is provided for operation and maintenance personnel.
The second embodiment:
the embodiment provides an infrared thermal imaging-based cable terminal oil leakage detection system 100, which is suitable for the infrared thermal imaging-based cable terminal oil leakage detection method in the first embodiment, and as shown in fig. 4, the infrared thermal imaging-based cable terminal oil leakage detection system includes:
a measurement calculation unit 10 for measuring a relative distance of the cable terminal and calculating a height of the cable terminal according to the relative distance;
a parameter correction unit 20, configured to correct the infrared imaging parameters of the image processing software based on the relative distance and other influence factors;
the acquisition processing unit 30 is configured to acquire an infrared image of the cable terminal, process the infrared image through the image processing software, and determine a liquid level line of the cable terminal;
The liquid level calculating unit 40 is used for identifying the infrared image of the cable terminal with the liquid level line to obtain the number of oil-lacking umbrella skirts and the number of integral umbrella skirts of the cable terminal so as to calculate the liquid level height of the cable terminal;
and the comparison and determination unit 50 is used for calculating an oil leakage ratio based on the liquid level height of the cable terminal and the height of the cable terminal, and comparing the oil leakage ratio with a preset oil leakage threshold value to obtain the oil leakage state of the cable terminal.
The detection scheme of the embodiment is mainly used for filling the inner insulation cable terminal with liquid, and the cable terminal needs to be determined at a proper detection position before the cable terminal is detected. In this embodiment, the oil leakage detection of the cable terminal is based on the liquid level detection of the cable terminal, and the liquid level detection of the cable terminal belongs to the category of infrared diagnosis accurate detection, so that the general detection requirements are met, the influence of ambient wind speed, direct sunlight, nearby thermal radiation sources, strong electromagnetic fields and the like on the detection result is noticed, the whole view of the detected terminal is ensured to be filled with the whole view field of the infrared imager as much as possible, and the infrared imager can adopt a long-focus infrared lens if necessary.
In this embodiment, be equipped with laser range finding module and image acquisition module in the infrared imaging appearance, detect the relative distance of infrared imaging appearance and cable terminal through the laser range finding module, gather infrared image through the image acquisition module, not only be limited to in this embodiment and measure distance and gather the image through the infrared imaging appearance, adopt other equipment to realize the mode of above-mentioned two kinds of functions, all in the protection range of this embodiment. Fig. 5 is a schematic diagram illustrating the calculation of the distance measurement performed by the infrared imager on the cable termination in this embodiment.
The measuring of the relative distance of the cable terminal and the calculating of the height of the cable terminal according to the relative distance specifically include:
measuring a first relative distance S1 and a first included angle alpha 1 between a current detection point A and an upper edge C of a first shed of the cable terminal;
measuring a second relative distance S2 and a second included angle alpha 2 between the current detection point A and the upper edge B of the flange on the cable terminal;
calculating a relative angle alpha between the straight line AC and the straight line AB based on the first angle alpha 1 and the second angle alpha 2;
calculating the height H of the cable terminal through the first relative distance S1, the second relative distance S2 and the relative included angle alpha.
In this embodiment, after the cable terminal is determined to be at the proper detection position, the infrared imager first aims at the upper edge C of the first shed of the cable terminal, and measures to obtain a first relative distance S1 and a first included angle α 1 (an included angle between the straight line AC and the horizontal line), then rotates downward by a certain angle in the same working plane until aiming at the upper edge B of the flange at the cable terminal, and measures to obtain a second relative distance S2 and a second included angle α 2 (an included angle between the straight line AB and the horizontal line). And subtracting the second included angle alpha 2 from the first included angle alpha 1 to obtain a relative included angle alpha between the straight line AC and the straight line AB. If the perpendicular point from B to the straight line AC is O and the perpendicular distance is d, d is S2 sin α, OC is S1-S2 cos α,
in this embodiment, the infrared imager may perform distance measurement, may also collect an infrared image, and processes the infrared image through image processing software, but before processing the infrared image, the infrared imaging parameters of the image processing software need to be set. The infrared imaging is influenced by factors such as relative distance, surface radiance of the measured material, ambient temperature, relative humidity and the like.
Wherein, the correcting the infrared imaging parameters of the image processing software based on the relative distance and other influence factors specifically comprises:
The measured distance parameter is set to (S1+ S2)/2;
if the terminal is a composite terminal or a terminal coated with an RTV porcelain bushing or a terminal coated with an HTV porcelain bushing, the surface radiance parameter is set to be 0.95; if the porcelain sleeve is the terminal of other porcelain sleeves, the surface radiance parameter is set to be 0.92;
the ambient temperature and the relative humidity are set according to actual measurement values.
According to the embodiment, the infrared imaging parameters are corrected, so that the subsequent imaging effect is clearer and more accurate. After the parameters are corrected, the acquired infrared image can be imaged by adopting image processing software.
The processing of the infrared image by the image processing software to determine the liquid level line of the cable terminal specifically comprises:
the image processing software carries out regional analysis on the infrared image, frames out the image of the cable terminal from the infrared image, and calculates the average temperature T of the cable terminal based on the image of the cable terminal selected by the framesave；
And correcting the upper and lower temperature limiting marks of the infrared image based on the average temperature, and adjusting the contrast of the infrared image through the corrected upper and lower temperature limiting marks so as to clearly display the liquid level line of the cable terminal in the image of the cable terminal.
In this embodiment, the collected infrared image should be as complete and clear as possible, the image information should include the full view from the lower flange to the outlet rod of the cable terminal, so as to select the image of the cable terminal from the infrared image, and the image processing software after the frame selection can automatically calculate the average temperature T of the cable terminal according to the image of the cable terminal selected by the frame selectionave. Then, the upper and lower temperature limits of the infrared image are corrected based on the average temperature, and the lower temperature limit T1 of the infrared image is set as Tave(ii) a The upper limit temperature scale T2 of the infrared image is set to TaveAnd (1-2) DEG C (the value of the temperature scale can be flexibly adjusted according to the display effect of the image). The contrast of the infrared image is directly related to the setting of the temperature scale, and the proper contrast can more intuitively reflect the position of the liquid level line of the cable terminal, so that the infrared image contrast is adjusted by correcting the temperature scale, and the liquid level line of the cable terminal is displayed more intuitively and clearly.
In this embodiment, the image of the cable terminal is analyzed by image recognition, so that the number of oil-starved sheds L2 (i.e., the number of sheds above the liquid level line) and the number of overall sheds L1 (for the number of sheds, if the external insulation adopts a large and small shed structure, the measurement is performed in groups of one large and one small) of the cable terminal are obtained, and the liquid level height H of the cable terminal is calculated as (L1-L2) × H/L1.
In this embodiment, the oil leakage ratio Δ H can be calculated by using the liquid level height H of the cable terminal and the height H of the cable terminal, where Δ H is (H-H)/H100%, and the oil leakage ratio is the ratio of the oil leakage part to the height of the cable terminal. And finally, comparing the oil leakage ratio with a preset oil leakage threshold value to obtain the oil leakage state of the cable terminal. At present, the power industry has not formed a unified standard for determining the oil leakage degree of a cable terminal, so that when an oil leakage threshold value is set, the oil leakage threshold value can be set according to the importance degree of a cable line corresponding to the cable terminal, the oil leakage threshold value of a primary cable line is slightly lower (for example, set to 10%), and the oil leakage threshold value of a secondary cable line can be properly relaxed (for example, set to 20%). If the oil leakage ratio exceeds the oil leakage threshold value, the technical scheme of the embodiment can perform early warning in modes of voice/information/mails and the like, so that the operation and maintenance personnel can find abnormal oil leakage states in time, the maintenance plan can be arranged in time, the power failure accident can be avoided, and if the oil leakage ratio does not exceed the oil leakage threshold value, the operation and maintenance personnel can perform daily work patrol by adopting a mode of appropriately shortening the patrol period.
In summary, compared with the prior art, the technical scheme of the embodiment has the following beneficial effects:
1. Adopt non-contact's oil leak detection mode, compare in current contact detection mode, need not to carry out the power failure and detect, do not influence the normal operating of cable, consequently can safe swift carry out oil leak detection.
2. The cable termination liquid level detection mode is easy and convenient to operate, based on the existing infrared imager or other equipment, does not need to newly increase detection equipment, and is suitable for large-area popularization and application.
3. The quantitative calculation of the height of the liquid level at the cable terminal is realized, the oil leakage state at the cable terminal can be accurately detected and the oil leakage early warning can be realized, and therefore a more visual and scientific overhaul suggestion is provided for operation and maintenance personnel.
Those of ordinary skill in the art will appreciate that the elements or steps of the various examples described in connection with the embodiments disclosed herein may be embodied in electronic hardware, computer software, or combinations of both, and that the components and steps of the various examples have been described in a functional general in the foregoing description for the purpose of illustrating clearly the interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
In the embodiments provided in the present application, it should be understood that the division of the steps is only one logical functional division, and there may be other division ways in actual implementation, for example, multiple steps may be combined into one step, one step may be split into multiple steps, or some features may be omitted.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the present invention, and they should be construed as being included in the following claims and description.
Claims (9)
1. A cable terminal oil leakage detection method based on infrared thermal imaging is characterized by comprising the following steps:
measuring the relative distance of the cable terminal, and calculating the height of the cable terminal according to the relative distance;
Correcting infrared imaging parameters of image processing software based on the relative distance and other influence factors;
acquiring an infrared image of the cable terminal, and processing the infrared image through the image processing software to determine a liquid level line of the cable terminal;
identifying the infrared image of the cable terminal with the liquid level line to obtain the number of oil-lacking umbrella skirts and the number of integral umbrella skirts of the cable terminal so as to calculate the liquid level height of the cable terminal;
calculating an oil leakage ratio based on the liquid level height of the cable terminal and the height of the cable terminal, and comparing the oil leakage ratio with a preset oil leakage threshold value to obtain an oil leakage state of the cable terminal;
the oil leakage ratio is the proportion of an oil leakage part to the height of the cable terminal, and the specific calculation method comprises the following steps:
△h＝(H-h)/H*100％
where Δ H is the oil leakage ratio, H is the height of the cable termination, and H is the liquid level height.
2. The method for detecting oil leakage of a cable terminal based on infrared thermal imaging according to claim 1, wherein the measuring a relative distance of the cable terminal and calculating a height of the cable terminal according to the relative distance are specifically:
measuring a first relative distance S1 and a first included angle alpha 1 between a current detection point A and an upper edge C of a first shed of the cable terminal;
Measuring a second relative distance S2 and a second included angle alpha 2 between the current detection point A and the upper edge B of the flange on the cable terminal;
calculating a relative angle alpha between the straight line AC and the straight line AB based on the first angle alpha 1 and the second angle alpha 2;
calculating the height H of the cable terminal through the first relative distance S1, the second relative distance S2 and the relative included angle alpha.
3. The infrared thermal imaging-based cable terminal oil leakage detection method according to claim 2, wherein the calculation formula for calculating the height H of the cable terminal is as follows:
4. the infrared thermal imaging-based method for detecting oil leakage from cable terminals according to claim 2, wherein the other factors include surface emissivity, ambient temperature and relative humidity of the tested material.
5. The method for detecting oil leakage of a cable terminal based on infrared thermal imaging according to claim 4, wherein the correcting the infrared imaging parameters of the image processing software based on the relative distance and other influencing factors specifically comprises:
the measurement distance parameter is set to (S1+ S2)/2;
if the terminal is a composite terminal or a terminal coated with an RTV porcelain bushing or a terminal coated with an HTV porcelain bushing, the surface radiance parameter is set to be 0.95; if the porcelain sleeve terminals are other porcelain sleeve terminals, the surface radiance parameter is set to be 0.92;
The ambient temperature and the relative humidity are set according to actual measurement values.
6. The method for detecting oil leakage of a cable terminal based on infrared thermal imaging according to claim 1, wherein the image processing software is used for processing the infrared image to determine a liquid level line of the cable terminal, and specifically comprises:
the image processing software carries out regional analysis on the infrared image, frames out the image of the cable terminal from the infrared image, and calculates the average temperature T of the cable terminal based on the image of the cable terminal selected by the framesave；
And correcting the upper and lower temperature limiting marks of the infrared image based on the average temperature, and adjusting the contrast of the infrared image through the corrected upper and lower temperature limiting marks so as to clearly display the liquid level line of the cable terminal in the image of the cable terminal.
7. The method for detecting the oil leakage of the cable terminal based on the infrared thermal imaging as claimed in claim 6, wherein the correcting the upper and lower temperature limit indicators of the infrared image based on the average temperature specifically comprises:
defining a lower temperature limit of the infrared image as T1, and T1 ═ Tave；
Defining an upper temperature limit of the infrared image as T2, and T2 ═ T ave+(1～2)℃。
8. The infrared thermal imaging-based cable terminal oil leakage detection method according to claim 1, wherein the calculation formula for calculating the liquid level height of the cable terminal is as follows:
h＝(L1-L2)*H/L1；
wherein h is the liquid level height, L1 is the number of integral umbrella skirt pieces, and L2 is the number of oil-deficient umbrella skirt pieces.
9. An infrared thermal imaging-based cable terminal oil leakage detection system, which is suitable for the infrared thermal imaging-based cable terminal oil leakage detection method according to any one of claims 1 to 8, and comprises:
the measurement calculation unit is used for measuring the relative distance of the cable terminal and calculating the height of the cable terminal according to the relative distance;
the parameter correcting unit is used for correcting the infrared imaging parameters of the image processing software based on the relative distance and other influencing factors;
the acquisition processing unit is used for acquiring the infrared image of the cable terminal, processing the infrared image through the image processing software and determining the liquid level line of the cable terminal;
the liquid level calculating unit is used for identifying the infrared image of the cable terminal with the liquid level line to obtain the number of oil-lacking umbrella skirts and the number of integral umbrella skirts of the cable terminal so as to calculate the liquid level height of the cable terminal;
And the comparison and judgment unit is used for calculating an oil leakage ratio based on the liquid level height of the cable terminal and the height of the cable terminal, and comparing the oil leakage ratio with a preset oil leakage threshold value to obtain the oil leakage state of the cable terminal.
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| CN103528771B (en) * | 2013-10-11 | 2015-11-18 | 广州供电局有限公司 | A kind of method measuring oil leakage fault of cable terminal porcelain sleeve |
| CN104122054A (en) * | 2014-07-27 | 2014-10-29 | 北京航星网讯技术股份有限公司 | Infrared thermal imaging type laser gas leak detection method and apparatus |
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