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CN117031212A - Method and device for detecting state of corrugated aluminum sheath cable - Google Patents

Method and device for detecting state of corrugated aluminum sheath cable Download PDF

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Publication number
CN117031212A
CN117031212A CN202311271511.2A CN202311271511A CN117031212A CN 117031212 A CN117031212 A CN 117031212A CN 202311271511 A CN202311271511 A CN 202311271511A CN 117031212 A CN117031212 A CN 117031212A
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aluminum sheath
cable
corrugated aluminum
sheath cable
characteristic gas
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CN117031212B (en
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伍云健
郭易凡
张丹枫
张晓星
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Hubei University of Technology
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Hubei University of Technology
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/08Locating faults in cables, transmission lines, or networks
    • G01R31/081Locating faults in cables, transmission lines, or networks according to type of conductors
    • G01R31/083Locating faults in cables, transmission lines, or networks according to type of conductors in cables, e.g. underground
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/08Locating faults in cables, transmission lines, or networks
    • G01R31/088Aspects of digital computing

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Mathematical Physics (AREA)
  • Theoretical Computer Science (AREA)
  • Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)

Abstract

The invention discloses a method and a device for detecting the state of a corrugated aluminum sheath cable. The method comprises the following steps: performing punching operation on the corrugated aluminum sheath cable, wherein the punched aperture extends to a position between the cable aluminum sheath and the buffer layer; collecting characteristic gas between the cable aluminum sheath and the buffer layer at the punching position under different time conditions, detecting the concentration of the characteristic gas at different time points until the concentration of the characteristic gas is not increased, and stopping detection; the time of ending the detection is marked as t; the characteristic gas comprises CO, CH 4 、CO 2 、C 3 H 6 、C 2 H 6 、C 2 H 4 And H 2 The method comprises the steps of carrying out a first treatment on the surface of the And (3) taking the concentration of the characteristic gas at the moment t as a fault characteristic index, and determining the fault generation position of the corrugated aluminum sheath cable by using the fault characteristic index. Compared with partial discharge detection and thermal infrared imaging detection, the method is more convenient and sensitive, can accurately evaluate the cable state, discover potential faults as soon as possible, and improve the reliability of the corrugated aluminum sheath high-voltage cableSex.

Description

Method and device for detecting state of corrugated aluminum sheath cable
Technical Field
The invention belongs to the technical field of power cable state detection, and particularly relates to a corrugated aluminum sheath cable state detection method and device.
Background
High voltage cross-linked polyethylene (XLPE) power cables are an important component of energy transmission, the reliability of which is critical to grid operation. However, in the live operation process of the cable, the insulation state of the cable is aged with time and even breakdown accidents occur under the influence of aging factors such as electricity, heat, chemistry and machinery. Once an insulation breakdown accident occurs, the cable needs to be powered off for maintenance, which brings inconvenience to normal production and life of vast users and even causes serious economic loss. The reliability of the power system can be greatly improved by detecting the state of the cable which is put into operation, and the current detection method for the cable state mainly comprises a partial discharge method, an infrared thermal imaging method and a dielectric loss detection method, but the current detection method has the following problems:
(1) For partial discharge detection methods, in-situ detection is extremely susceptible to noise interference from surrounding electrical equipment; meanwhile, the partial discharge signal generated inside the cable is very weak and has short duration, so that the discharge signal is likely to be missed during detection, and the difficulty in diagnosing the state of the cable through partial discharge detection is very high.
(2) For the infrared thermal imaging detection method, the heat generated by hundreds of pC partial discharge at the defect part of the cable is very small, the heating phenomenon can only occur when the defect part has larger resistive leakage current and has longer duration, not all defects can generate measurable abnormal temperature, and the temperature distribution of the inner insulating layer can not be measured.
(3) For the dielectric loss detection method, the precision of detection instruments and equipment is required to be high, the test result is affected by difficult leakage current separation, ambient temperature and humidity and improper signal processing method, and a detection technology of a system is not formed.
Corrugated aluminum sheath cables are a common form of power cable, which can be divided from inside to outside: the device comprises a conductor, an inner semi-conductive layer, an insulating layer, an outer semi-conductive layer, a buffer layer, an aluminum sheath and a sealing sleeve, wherein a gap exists between the buffer layer and the aluminum sheath, so that a closed cavity is formed. The long-term operation of the high-voltage cable is easily affected by factors such as humidity, corrosion, electrical stress, thermal stress and the like, resulting in degradation of the internal insulating layer and the semiconductive layer and generation of gas. All the gases volatilized during the aging process of the corrugated aluminum sheath cable are concentrated in the porous buffer layer and diffuse freely along the cable. The traditional cable state detection method cannot monitor the content of gas in the cable in real time, and is difficult to accurately judge the health state of the cable, so that an efficient and accurate cable state detection method and device are urgently needed.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a method and a device for detecting the state of a corrugated aluminum sheath cable, which solve the problem that the state of the cable cannot be accurately monitored and estimated in time in the prior art.
In order to solve the technical problems, the first solution provided by the present invention is as follows: the corrugated aluminum sheath cable state detection method comprises the following steps:
s1, performing punching operation on a corrugated aluminum sheath cable, wherein the punched aperture extends to a position between the aluminum sheath and a buffer layer of the cable;
s2, collecting characteristic gas between the cable aluminum sheath and the buffer layer at the punching position at different moments, detecting the concentration of the characteristic gas at different moments until the concentration of the characteristic gas is not increased, and stopping detection; the time of ending the detection is marked as t; the characteristic gas comprises CO and CH 4 、CO 2 、C 3 H 6 、C 2 H 6 、C 2 H 4 And H 2
S3, using the concentration of the characteristic gas at the t moment as a fault characteristic index, and determining a fault generation part of the corrugated aluminum sheath cable by using the fault characteristic index; the method for determining the fault generating part of the corrugated aluminum sheath cable comprises the following steps:
when the highest content of the component in the detected characteristic gas is H 2 Indicating that electrochemical corrosion of the buffer layer in the corrugated aluminum sheath cable occurs;
when the component with the highest content in the detected characteristic gas is CO, indicating that the insulating layer of the corrugated aluminum sheath cable has a thermal fault;
when the highest content of the detected characteristic gas is CH 4 Indicating a thermal failure of the semiconductive layer of the corrugated aluminum sheath cable.
Preferably, step S3 further comprises the step of determining the value according to ΔC 2 H 6 ΔCO and ΔC 2 H 4 /ΔC 2 H 2 Determining the type of thermal fault of the corrugated aluminum sheath cable; wherein ΔC 2 H 6 The/. DELTA.CO represents C at the same time interval 2 H 6 Ratio of the amount of change in (C) to the amount of change in CO, deltaC 2 H 4 /ΔC 2 H 2 Representing C at the same time interval 2 H 4 Variation of (C) and C 2 H 2 The ratio of the amounts of change; the method for determining the type of the thermal fault of the corrugated aluminum sheath cable comprises the following steps:
when the component with the highest content in the detected characteristic gas is CO, and the delta C is satisfied 2 H 6 /ΔCO=0.18±0.03,ΔC 2 H 4 /ΔC 2 H 2 =0.55±0.03, indicating that there is thermal decomposition of the insulating layer of the cable; when the component with the highest content in the detected characteristic gas is CO and H 2 The ratio is more than 20%, which indicates that the insulating layer of the cable is carbonized; when the highest content of the detected characteristic gas is CH 4 And meet DeltaC 2 H 6 /ΔCO=0.18±0.03,ΔC 2 H 4 /ΔC 2 H 2 =0.55±0.03, indicating that there is thermal decomposition of the semiconductive layer of the cable.
Preferably, step S3 further comprises the step of determining the value according to ΔH 2 /ΔCH 4 Determining a pyrolysis temperature at which thermal decomposition of the cable occurs; wherein DeltaH 2 /ΔCH 4 Indicating H at the same time interval 2 Variation of (C) and CH 4 The ratio of the amounts of change;
the method for determining the pyrolysis temperature of the cable subjected to thermal decomposition comprises the following steps: when the component with the highest content in the detected characteristic gas is CO, and simultaneously satisfies delta C 2 H 6 /ΔCO=0.18±0.03,ΔC 2 H 4 /ΔC 2 H 2 =0.55±0.03,ΔH 2 /ΔCH 4 =0.75±0.05, indicating that cable insulation layer is subjected to low temperature pyrolysis, and the pyrolysis temperature is 200 ℃ to 250 ℃; when the component with the highest content in the detected characteristic gas is CO, the method simultaneously satisfiesΔC 2 H 6 /ΔCO=0.18±0.03,ΔC 2 H 4 /ΔC 2 H 2 =0.55±0.03,ΔH 2 /ΔCH 4 =0.85±0.05, indicating that cable insulation layer is thermally pyrolyzed at a pyrolysis temperature of 250 ℃ to 300 ℃; when the highest content of the detected characteristic gas is CH 4 And at the same time satisfy delta C 2 H 6 /ΔCO=0.18±0.03,ΔC 2 H 4 /ΔC 2 H 2 =0.55±0.03,ΔH 2 /ΔCH 4 =0.95±0.05, indicating that the semiconductive layer of the cable is subjected to low temperature pyrolysis, the pyrolysis temperature being 300 ℃ to 350 ℃; when the highest content of the detected characteristic gas is CH 4 And at the same time satisfy delta C 2 H 6 /ΔCO=0.18±0.03,ΔC 2 H 4 /ΔC 2 H 2 =0.55±0.03,ΔH 2 /ΔCH 4 =1.05±0.05, indicating that the semiconductive layer of the cable is pyrolyzed at a pyrolysis temperature of 350 ℃ to 400 ℃.
Preferably, in the step S1, holes are punched at the wave crest of the corrugated aluminum sheath cable, and the punching depth is 1.5-3 cm.
Preferably, in step S2, the collection amount of the characteristic gas accounts for 5% -10% of the volume of the gas in the closed cavity between the buffer layer and the aluminum sheath.
Preferably, after the gas is collected, the method further comprises the operation of recovering and repairing the cable at the punching position, so that the cable outer sheath is recovered to a sealing and waterproof state before punching.
In order to solve the technical problems, a second solution provided by the present invention is: a corrugated aluminum sheath cable state detection device, comprising: the device comprises an air taking unit, a sensing detection unit, a data processing unit and an information display unit which are connected in sequence; the gas sampling unit comprises a sampling probe, a pumping sampling tube and a vacuum pump which are sequentially communicated; the detection device is used for executing the corrugated aluminum sheath cable state detection method in the first solution.
Preferably, the sensing detection unit comprises an electrochemical sensor, a catalytic burner and an infrared sensor which are communicated.
Preferably, the outlet end of the pumping sampling tube is provided with a dust screen and an annular heater; the output end of the data processing unit is also connected with an output storage transmission unit and an alarm unit.
The beneficial effects of the invention are as follows:
according to the invention, the characteristic gas between the cable aluminum sheath and the buffer layer is collected, and the concentration of the characteristic gas finally generated in the cable is used as a fault characteristic index, so that compared with partial discharge detection and thermal infrared imaging detection, the method is more convenient and sensitive, potential faults can be found early, and the reliability of the high-voltage cable is improved.
The invention judges the thermal fault type and the pyrolysis temperature of the cable according to the ratio of the concentration variation of different characteristic gases in the same time interval, further accurately evaluates the cause of cable faults, provides important reference value for the detection and diagnosis of actual cable line faults, and is convenient to take targeted protective measures.
The detection device provided by the invention can be used for periodically detecting the characteristic gas, has high detection sensitivity, can be used for monitoring and early warning the fault state of the high-voltage cable in real time, and ensures the safe and stable operation of a power grid system.
Compared with partial discharge detection and thermal infrared imaging detection, the corrugated aluminum sheath cable state detection method and the online detection device provided by the invention are more convenient, have low test cost and are more economical.
Drawings
FIG. 1 is a flow chart of a method for detecting the state of a corrugated aluminum sheath cable according to the invention;
FIG. 2 is a graph of the perforating results of corrugated aluminum jacketed cable;
FIG. 3 is a graph of hydrogen concentration in cable number 1 over time;
FIG. 4 is a bar graph of the ratio of characteristic gas concentration increments for cable No. 2, cable No. 3, cable No. 5, and cable No. 6;
FIG. 5 is a schematic diagram of the external structure of a corrugated aluminum sheath cable state detection device according to an embodiment of the present invention;
FIG. 6 is a schematic diagram of the internal structure of a corrugated aluminum sheath cable state detection device according to an embodiment of the present invention;
FIG. 7 is a schematic diagram of the constituent units of a corrugated aluminum sheath cable status detection device according to an embodiment of the present invention;
in the figure: 1. an air taking unit; 11. a sampling probe; 12. pumping the sampling tube; 13. a vacuum pump; 14. a rubber ring; 15. a pumping sampling interface; 16. a dust screen; 17. an annular heater; 2. a sensing unit; 21. an electrochemical sensor; 22. a catalytic burner; 23. an infrared sensor; 24. a vent pipe; 3. a gas distribution module; 4. a data storage; 5. a battery; 6. a main control chip; 7. a vibration motor; 8. an air outlet; 9. a data interface; 101. the cavity is closed.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described in the following in conjunction with the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, are intended to fall within the scope of the present invention.
The traditional temperature measurement technology is to install a point type temperature sensor at an important part of a cable to measure temperature, has a limited temperature measurement range and is easy to generate a measurement blind area. Aiming at the defects of the prior art, the invention creatively provides a novel high-voltage cable overheat fault detection technology according to the structure and the materials of the high-voltage cable. The high-voltage cable can be divided into from inside to outside: the device comprises a conductor, an inner semi-conductive layer, an insulating layer, an outer semi-conductive layer, a buffer layer, an aluminum sheath and a sealing sleeve, wherein a gap exists between the buffer layer and the metal aluminum sheath, and a closed cavity is formed. At present, most buffer layers are made of porous polyester fiber non-woven fabrics, and all gases volatilized in the cable degradation process are concentrated in the porous buffer layers and are freely diffused along the cable. The main components of the insulating layer and the semiconductive layer are crosslinked polyethylene (XLPE), and because of current heating, XLPE can generate decomposed gas at high temperature, and meanwhile, the inventor finds that the decomposed gas can be decomposed under the action of thermal oxygen to generate characteristic decomposed products in advance, so that the fault generation part and the type of corresponding faults of the cable are determined according to the concentration of the characteristic gas and the ratio of concentration variation of different characteristic gases in the same time interval based on the characteristic decomposed gas in a sealed cavity between the buffer layer and the metal sheath.
When the cable is produced, stored and operated, the cable has insufficient tightness, so that external moisture invades the cable buffer layer, and water blocking powder in the buffer layer absorbs the moisture and expands into spheres to be in direct contact with the trough of the aluminum sheath. Because the water-blocking powder is sodium polyacrylate and is an alkaline substance, free Na can be generated after the water-blocking powder absorbs water and expands + And OH (OH) - The ion, aluminum is an active amphoteric metal, so the aluminum sheath in direct contact with the water-blocking powder can be connected with free Na + And OH (OH) - The ions react as follows:
2A1+2OH - +2H 2 O+2Na + =2NaAlO 2 +3H 2
in addition, when the buffer layer is wetted, water molecules will be adsorbed on the carbon black surface of the buffer layer. The water is used as electrolyte, the joint of the carbon black and the aluminum sheath is used as an electron circulation lead, a primary cell is finally formed, and an electrolytic cell is formed under the action of current. When the electrolyte solution is acidic, hydrogen evolution reaction occurs:
2Al+O 2 +4H 2 O=2Al(OH) 3 ↓+H 2
referring to fig. 1, the method for detecting the state of the corrugated aluminum sheath cable provided by the invention comprises the following steps:
s1, performing punching operation on a corrugated aluminum sheath cable, wherein the punched aperture extends to a position between the aluminum sheath and a buffer layer of the cable;
s2, collecting characteristic gas between the cable aluminum sheath and the buffer layer at the punching position at different moments, detecting the concentration of the characteristic gas at different moments until the concentration of the characteristic gas is not increased, and stopping detection; the time of ending the detection is marked as t; the characteristic gas comprises CO and CH 4 、CO 2 、C 3 H 6 、C 2 H 6 、C 2 H 4 And H 2
S3, using the concentration of the characteristic gas at the t moment as a fault characteristic index, and determining a fault generation part of the corrugated aluminum sheath cable by using the fault characteristic index; the method for determining the fault generating part of the corrugated aluminum sheath cable comprises the following steps:
when the highest content of the component in the detected characteristic gas is H 2 Indicating that electrochemical corrosion of the buffer layer inside the cable occurs; when the component with the highest content in the detected characteristic gas is CO, indicating that the insulating layer of the cable has a thermal fault; when the highest content of the detected characteristic gas is CH 4 Indicating a thermal failure of the semiconductive layer of the cable. The fault diagnosis of the invention is based on the following table 1:
TABLE 1
The invention also relates to delta C 2 H 6 ΔCO and ΔC 2 H 4 /ΔC 2 H 2 Determining a thermal fault type of the cable; wherein ΔC 2 H 6 The/. DELTA.CO represents C at the same time interval 2 H 6 Ratio of the amount of change in (C) to the amount of change in CO, deltaC 2 H 4 /ΔC 2 H 2 Representing C at the same time interval 2 H 4 Variation of (C) and C 2 H 2 Ratio of the amount of change.
The method for determining the cable thermal fault type comprises the following steps: when the component with the highest content in the detected characteristic gas is CO, and the delta C is satisfied 2 H 6 /ΔCO=0.18±0.03,ΔC 2 H 4 /ΔC 2 H 2 =0.55±0.03, indicating that there is thermal decomposition of the insulating layer of the cable; when the component with the highest content in the detected characteristic gas is CO and H 2 The ratio is more than 20%, which indicates that the insulating layer of the cable is carbonized; when the highest content of the detected characteristic gas is CH 4 And meet DeltaC 2 H 6 /ΔCO=0.18±0.03,ΔC 2 H 4 /ΔC 2 H 2 =0.55±0.03, indicating that there is thermal decomposition of the semiconductive layer of the cable. The thermal fault type diagnosis is based on the following table 2:
TABLE 2
The invention also provides a method for producing a light-emitting diode according to delta H 2 /ΔCH 4 Further judging the pyrolysis temperature, thereby obtaining the temperature generated by thermal decomposition in the cable. ΔH 2 /ΔCH 4 Indicating H at the same time interval 2 Variation of (C) and CH 4 Ratio of the amount of change. The temperature interval can be determined from the following table 3:
TABLE 3 Table 3
Specifically, the method for determining the pyrolysis temperature at which thermal decomposition of the cable occurs includes: when the component with the highest content in the detected characteristic gas is CO, and simultaneously satisfies delta C 2 H 6 /ΔCO=0.18±0.03,ΔC 2 H 4 /ΔC 2 H 2 =0.55±0.03,ΔH 2 /ΔCH 4 =0.75±0.05, indicating that cable insulation layer is subjected to low temperature pyrolysis, and the pyrolysis temperature is 200 ℃ to 250 ℃; when the component with the highest content in the detected characteristic gas is CO, and simultaneously satisfies delta C 2 H 6 /ΔCO=0.18±0.03,ΔC 2 H 4 /ΔC 2 H 2 =0.55±0.03,ΔH 2 /ΔCH 4 =0.85±0.05, indicating that cable insulation layer is thermally pyrolyzed at a pyrolysis temperature of 250 ℃ to 300 ℃; when the highest content of the detected characteristic gas is CH 4 And at the same time satisfy delta C 2 H 6 /ΔCO=0.18±0.03,ΔC 2 H 4 /ΔC 2 H 2 =0.55±0.03,ΔH 2 /ΔCH 4 =0.95±0.05, indicating that the semiconductive layer of the cable is subjected to low temperature pyrolysis, the pyrolysis temperature being 300 ℃ to 350 ℃; when the highest content of the detected characteristic gas is CH 4 And at the same time satisfy delta C 2 H 6 /ΔCO=0.18±0.03,ΔC 2 H 4 /ΔC 2 H 2 =0.55±0.03,ΔH 2 /ΔCH 4 =1.05±0.05, indicating that the semiconductive layer of the cable is pyrolyzed at a pyrolysis temperature of 350 ℃ to 400 ℃.
Further, after the gas is collected, the method further comprises the operation of recovering and repairing the cable at the punching position, and the recovery and repairing process of the invention adopts a conventional method in the field to plug the sampling hole so as to ensure that the cable outer sheath is recovered to a sealing and waterproof state before punching.
In order to make the implementation objects, technical solutions and advantages of the present invention more clear, the technical solutions in the embodiments of the present invention will be described in more detail below with reference to the accompanying drawings of the present invention.
For the first solution of the present invention, the method for detecting the state of the corrugated aluminum sheath cable provided by the present invention includes the following steps:
s1, penetrating an aluminum sheath at the wave crest of a corrugated aluminum sheath cable by using a drill bit with the diameter of 2.5mm, and cutting test holes at the wave crest, wherein the drilling depth is 1.5-3 cm, and the drilling result is shown in figure 2;
s2, collecting characteristic gas in the closed cavity between the aluminum sheath and the buffer layer every 5min, wherein the collection amount of the characteristic gas is 10mL until the concentration of the characteristic gas is not increased any more, and detecting the concentration of the characteristic gas collected each time; the characteristic gas comprises CO and CH 4 、CO 2 、C 3 H 6 、C 2 H 6 、C 2 H 4 And H 2
S3, according to the detected concentration and delta C when the characteristic gas reaches balance 2 H 6 ΔCO and ΔC 2 H 4 /ΔC 2 H 2 ΔH 2 /ΔCH 4 The type of fault of the cable and the location of the fault generation are determined.
Specifically, the test of the embodiment of the invention is carried out on 6 110 and kV high-voltage cables in a certain region of Hubei province, and the results are shown in table 4:
TABLE 4 Table 4
FIG. 3 is a graph of hydrogen concentration in a No. 1 cable over time, as can be seen in conjunction with FIGS. 3 and 4, the volume fraction of hydrogen content in a No. 1 corrugated aluminum sheath cable has exceeded the overallEighty percent of the product and the remaining gas content were less, it can be inferred that cable No. 1 was electrochemically corroded in the buffer layer. As can be seen from Table 3, the characteristic gas detected in the cable No. 4 has the largest CO content and H 2 The ratio is more than 20%, which indicates that the cable has electric breakdown or flashover to cause XLPE carbonization.
The ratio (average value) of the concentration increment of different characteristic gases every 5min in the No. 2-3 and No. 5-6 high voltage cables is shown in Table 5 and FIG. 4.
TABLE 5
As can be seen by combining tables 4-5 and FIG. 4, the carbon monoxide content in the No. 2 cable is highest, reaches 95ppm, and the concentration increment in the same time interval satisfies the delta C 2 H 6 /ΔCO=0.18、ΔC 2 H 4 /ΔC 2 H 2 =0.53 and Δh 2 /ΔCH 4 =0.74, and it is inferred that the insulating layer of the cable is subjected to low-temperature pyrolysis, and the pyrolysis temperature is 200 ℃ to 250 ℃. The characteristic gas of the No. 3 cable is mainly carbon monoxide, and the concentration increment in the same time interval satisfies delta C 2 H 6 /ΔCO=0.18、ΔC 2 H 4 /ΔC 2 H 2 =0.54 and Δh 2 /ΔCH 4 =0.87, indicating that the insulating layer of the high voltage cable is pyrolyzed at a pyrolysis temperature of 250 ℃ to 300 ℃. The characteristic gas in the No. 5 cable is mainly methane, the content reaches about 155ppm, and the concentration increment in the same time interval meets delta C 2 H 6 /ΔCO=0.17、ΔC 2 H 4 /ΔC 2 H 2 =0.58 and Δh 2 /ΔCH 4 =0.94, indicating that the semiconductive layer of the cable was subjected to low temperature pyrolysis at 300 to 350 ℃. The characteristic gas detected by the No. 6 cable is mainly methane, and the concentration increment in the same time interval satisfies delta C 2 H 6 /ΔCO=0.17、ΔC 2 H 4 /ΔC 2 H 2 =0.58 and Δh 2 /ΔCH 4 =1.01, illustrating the pyrolysis of a semiconductive layerThe pyrolysis temperature is 350-400 ℃.
The high-voltage cable is disassembled, and a large amount of white powder exists on the surface of the buffer layer of the No. 1 high-voltage cable, which is generated by electrochemical corrosion; the surface of the buffer layer of the No. 2-4 cable is provided with ablation perforations, the ablation area of the No. 2 cable is smaller than that of the No. 3 cable, and the fact that the No. 3 cable is subjected to high-temperature pyrolysis compared with the No. 2 cable is shown; black powder exists on the surface of the buffer layer of the No. 4 cable, which indicates that carbonization occurs. The surface of the semiconductive layers of the No. 5 cable and the No. 6 cable are provided with ablation perforations, and the ablation area of the semiconductive layer of the No. 6 cable is larger than that of the semiconductive layer of the No. 5 cable, so that the perforation is deeper, and the pyrolysis temperature of the No. 6 cable is higher than that of the No. 5 cable.
For a second solution of the present invention, please refer to fig. 5 to 7, a corrugated aluminum sheath cable state detecting apparatus of the present invention includes: the device comprises an air taking unit 1, a sensing unit 2, a data processing unit and an information display unit which are connected in sequence; the output end of the data processing unit is also connected with an output storage transmission unit and an alarm unit. Specifically, the gas taking unit comprises a sampling probe 11, a pumping sampling tube 12 and a vacuum pump 13 which are sequentially communicated; as shown in fig. 6, the sensor unit is an original inlet high-precision sensor capable of detecting H 2 、CO、CO 2 、CH 4 、C 2 H 6 And C 2 H 4 The detection range of the equal gas is 5-2000 ppm, and the sensitivity is high<0.5 response time<30s, working temperature is minus 20 ℃ to +50 ℃, circuit voltage is 5V plus or minus 0.2V, working humidity is 10 percent to 95 percent RH (non-condensation). The sensing unit 2 is arranged inside the device housing and comprises an electrochemical sensor 21, a catalytic burner 22 and an infrared sensor 23 which are communicated in sequence through a vent pipe 24. The outside of the sampling probe 11 is provided with a rubber ring 14 for sealing when collecting gas.
The pumping sampling tube 12 is made of iron nickel alloy and can be freely bent; the shell of the device is made of high-strength ABS material, and the whole device can reach the IP66 protection level, and is safe and explosion-proof. One side of the device shell is provided with a pumping sampling interface 15, a gas outlet end of the pumping sampling tube 12 is communicated with the pumping sampling interface 15, and a dustproof net 16 is arranged at the joint of the pumping sampling interface 15 and the device shell and used for preventing the sampling tube from being blocked due to excessive dust particles and the like. An annular heater 17 is also provided between the electrochemical sensor 21 and the pumping sampling interface 15.
Specifically, the device shell is also internally provided with a gas distribution module 3, a data memory 4, a battery 5, a main control chip 6, a vibration motor 7, a gas outlet 8 and a data interface 9. The air distribution module 3 is used for ensuring that the oxygen content fed into the detection device is sufficient and reaches more than 5 percent VOL. The battery 5 is a lithium battery of 8000mAH, and the continuous working time is longer than 12 hours. The main control chip 6 has a temperature digital compensation function in a full range. The data interface 9 is miniUSB (trapezoidal interface) and the charging interface are integrated.
Specifically, the vacuum pump 13 is a miniature vacuum pump, the maximum vacuum degree is-100 kPa, the material is high temperature resistant, and the tail part of the vacuum pump is connected with the air outlet 8. The ventilation pipe in the device is an integrated heat-insulating pipeline and comprises a guide pipe and a heat-insulating layer from inside to outside in sequence; the conduit is made of stainless steel, and the heat-insulating material is glass fiber cotton; in this embodiment, the length of the gas taking pipeline is 0.45m, and the maximum length is not more than 0.8m.
Further, based on the method for detecting the state of the corrugated aluminum sheath cable in the first solution, a specific operation process of the detecting device is described, and the specific steps include:
the tip of the sampling probe 11 is communicated with a closed cavity 101 between an aluminum sheath and a buffer layer of the corrugated aluminum sheath cable, when the vacuum pump 13 works, characteristic gas is extracted from the closed cavity between the aluminum sheath and the buffer layer of the corrugated aluminum sheath cable through a pumping sampling tube 12 and is conveyed to a pumping sampling interface 15, then the characteristic gas is dehumidified and heated through an annular heater 17, then the characteristic gas is quantitatively detected through an infrared sensor, a catalytic combustion sensor and an electrochemical sensor in sequence, finally the characteristic gas is discharged from an air outlet 8, the concentration of the characteristic gas is detected by a sensing unit, the concentration of each gas of which the target gas is used as a time function is obtained, and a data processing unit processes the concentration change ratio of different characteristic gases in the same time interval to judge the fault type and the fault generation position of the cable by taking the ratio as indexes, and when the abnormality of the cable is detected, an alarm signal is sent to the outside through an alarm lamp, a buzzer and a vibration motor of the alarm unit.
It should be noted that, the foregoing embodiments all belong to the same inventive concept, and the descriptions of the embodiments have emphasis, and where the descriptions of the individual embodiments are not exhaustive, reference may be made to the descriptions of the other embodiments.
The foregoing examples merely illustrate embodiments of the invention and are described in more detail and are not to be construed as limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.

Claims (10)

1. The method for detecting the state of the corrugated aluminum sheath cable is characterized by comprising the following steps of:
s1, performing punching operation on a corrugated aluminum sheath cable, wherein the aperture of punching extends to a position between the aluminum sheath and a buffer layer of the cable;
s2, collecting characteristic gas between the cable aluminum sheath and the buffer layer at the punching position at different moments, detecting the concentration of the characteristic gas at different moments until the concentration of the characteristic gas is not increased, and stopping detection; the time of ending the detection is marked as t; the characteristic gas comprises CO, CH 4 、CO 2 、C 3 H 6 、C 2 H 6 、C 2 H 4 And H 2
S3, using the concentration of the characteristic gas at the moment t as a fault characteristic index, and determining a fault generation part of the corrugated aluminum sheath cable by using the fault characteristic index; the method for determining the fault generation part of the corrugated aluminum sheath cable comprises the following steps:
when the highest content of the component in the detected characteristic gas is H 2 Indicating that electrochemical corrosion of the buffer layer in the corrugated aluminum sheath cable occurs;
when the component with the highest content in the detected characteristic gas is CO, indicating that the insulating layer of the corrugated aluminum sheath cable has a thermal fault;
when the highest content of the detected characteristic gas is CH 4 Indicating a thermal failure of the semiconductive layer of the corrugated aluminum sheath cable.
2. The method for detecting the state of a corrugated aluminum sheath cable according to claim 1, wherein step S3 further includes the step of detecting the state of the corrugated aluminum sheath cable according to Δc 2 H 6 ΔCO and ΔC 2 H 4 /ΔC 2 H 2 Determining a thermal fault type of the corrugated aluminum sheath cable; wherein ΔC 2 H 6 The/. DELTA.CO represents C at the same time interval 2 H 6 Ratio of the amount of change in (C) to the amount of change in CO, deltaC 2 H 4 /ΔC 2 H 2 Representing C at the same time interval 2 H 4 Variation of (C) and C 2 H 2 The ratio of the amounts of change; the method for determining the type of the thermal fault of the corrugated aluminum sheath cable comprises the following steps:
when the component with the highest content in the detected characteristic gas is CO, and the delta C is satisfied 2 H 6 /ΔCO=0.18±0.03,ΔC 2 H 4 /ΔC 2 H 2 =0.55±0.03, indicating that there is thermal decomposition of the insulation layer of the corrugated aluminum sheath cable;
when the component with the highest content in the detected characteristic gas is CO and H 2 The proportion is more than 20%, which indicates that the insulating layer of the corrugated aluminum sheath cable is carbonized;
when the highest content of the detected characteristic gas is CH 4 And meet DeltaC 2 H 6 /ΔCO=0.18±0.03,ΔC 2 H 4 /ΔC 2 H 2 =0.55±0.03, indicating that there is thermal decomposition of the semiconductive layer of the corrugated aluminum sheath cable.
3. The method for detecting the state of a corrugated aluminum sheath cable according to claim 2, wherein step S3 further includes the step of detecting the state of the corrugated aluminum sheath cable according to Δh 2 /ΔCH 4 Determining a pyrolysis temperature at which thermal decomposition of the corrugated aluminum sheath cable occurs; wherein DeltaH 2 /ΔCH 4 Indicating H at the same time interval 2 Variation of (C) and CH 4 The ratio of the amounts of change;
the method for determining the pyrolysis temperature of the corrugated aluminum sheath cable after thermal decomposition comprises the following steps:
when the component with the highest content in the detected characteristic gas is CO, and simultaneously satisfies delta C 2 H 6 /ΔCO=0.18±0.03,ΔC 2 H 4 /ΔC 2 H 2 =0.55±0.03,ΔH 2 /ΔCH 4 =0.75±0.05, indicating that the corrugated aluminum sheath cable insulation layer is subjected to low-temperature pyrolysis, and the pyrolysis temperature is 200 ℃ to 250 ℃;
when the component with the highest content in the detected characteristic gas is CO, and simultaneously satisfies delta C 2 H 6 /ΔCO=0.18±0.03,ΔC 2 H 4 /ΔC 2 H 2 =0.55±0.03,ΔH 2 /ΔCH 4 =0.85±0.05, indicating that the corrugated aluminum sheath cable insulation layer is subjected to pyrolysis, and the pyrolysis temperature is 250 ℃ to 300 ℃;
when the highest content of the detected characteristic gas is CH 4 And at the same time satisfy delta C 2 H 6 /ΔCO=0.18±0.03,ΔC 2 H 4 /ΔC 2 H 2 =0.55±0.03,ΔH 2 /ΔCH 4 =0.95±0.05, indicating that the semiconductive layer of the corrugated aluminum sheath cable is subjected to pyrolysis, the pyrolysis temperature being 300 ℃ to 350 ℃;
when the highest content of the detected characteristic gas is CH 4 And at the same time satisfy delta C 2 H 6 /ΔCO=0.18±0.03,ΔC 2 H 4 /ΔC 2 H 2 =0.55±0.03,ΔH 2 /ΔCH 4 =1.05±0.05, indicating that the semiconductive layer of the corrugated aluminum sheath cable is thermally pyrolyzed at a temperature of 350 ℃ to 400 ℃.
4. The method for detecting the state of the corrugated aluminum sheath cable according to claim 1, wherein in the step S1, holes are punched at the wave crest of the corrugated aluminum sheath cable, and the punching depth is 1.5-3 cm.
5. The method for detecting the state of the corrugated aluminum sheath cable according to claim 1, wherein in the step S2, the collection amount of the characteristic gas is 5% -10% of the volume of the gas in the closed cavity between the buffer layer and the aluminum sheath.
6. The method for detecting the state of the corrugated aluminum sheath cable according to claim 1, further comprising the operation of recovering and repairing the corrugated aluminum sheath cable at the punching position after the gas is collected, so that the outer sheath of the corrugated aluminum sheath cable is recovered to a sealed waterproof state before punching.
7. The utility model provides a ripple aluminium sheath cable state detection device which characterized in that includes: the device comprises an air taking unit, a sensing detection unit, a data processing unit and an information display unit which are connected in sequence; the gas taking unit comprises a sampling probe, a pumping sampling tube and a vacuum pump which are sequentially connected;
the detection device is used for executing the corrugated aluminum sheath cable state detection method according to any one of claims 1-6.
8. The corrugated aluminum sheath cable state detection apparatus of claim 7, wherein the sensing detection unit includes an electrochemical sensor, a catalytic combustion sensor, an infrared sensor in communication.
9. The corrugated aluminum sheath cable state detection apparatus of claim 7, wherein the pumping sampling tube outlet end is provided with a dust screen and an annular heater.
10. The corrugated aluminum sheath cable state detection device of claim 7, wherein the output end of the data processing unit is further connected with an output storage transmission unit and an alarm unit.
CN202311271511.2A 2023-09-28 2023-09-28 Method and device for detecting state of corrugated aluminum sheath cable Active CN117031212B (en)

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