CN109856513B - XPLE cable partial discharge or overheating gas monitoring method - Google Patents

Abstract

The invention relates to a partial discharge or overheating monitoring technology for cable insulation defects, in particular to a XPLE cable partial discharge or overheating gas monitorThe detection method comprises detecting characteristic gases CO and CH generated in the process of partial discharge or overheating of XPLE cable₄And C₂H₄And the monitoring of XPLE cable partial discharge and overheating is realized. The monitoring method can be applied to XPLE cable laying places with weak gas circulation and is not limited by cable laying modes. The method can be used for positioning the defects, and the line sections with the defects can be determined according to the position information of the gas sensor in the message information. The gas detection method is free from interference of factors such as electromagnetism and the like, and is high in sensitivity.

Description

XPLE cable partial discharge or overheating gas monitoring method

Technical Field

The invention belongs to the technical field of monitoring partial discharge or overheating of cable insulation defects, and particularly relates to a method for monitoring XPLE cable partial discharge or overheating gas.

Background

In recent years, crosslinked polyethylene (XLPE) plastic cables are widely applied by virtue of the advantages of excellent performance, simple process, convenient installation and the like, gradually replace traditional oil paper insulated cables, become the dominant variety in medium and high voltage transmission systems, and have the highest operating voltage of 500 kV. If the cable is manufactured with good quality (including the materials and manufacturing processes for cable core insulation and sheath insulation), has proper operating conditions (including load, overvoltage, temperature, ambient environment and the like), and is not damaged by external factors, the service life of the cable insulation is quite long (about 30 years). However, the cable material itself and the manufacturing and laying engineering inevitably have defects, and the insulation of the cable is aged to different degrees under the influence of factors such as electricity, heat, chemistry, environment and the like in operation, so that the operation life of the cable is seriously weakened.

Partial discharges and overheating are two important causes of cable degradation. When XPLE cable inside appears the defect and produces partial discharge or the high temperature, the insulating layer of cable can age gradually to influence the behavior of cable and even cause the trouble. How to monitor the insulation defect of the cable is a great concern in the fieldTo a problem of (a). When the XPLE cable is in partial discharge or overheating condition, the insulating layer XPLE can be decomposed to generate CO and CO₂Moisture, CH₄And C₂H₄And the monitoring of partial discharge and overheating problems can be realized by detecting whether relevant characteristic gas exists around the cable.

Disclosure of Invention

The invention aims to provide a method for determining whether partial discharge or overheating occurs and the position of the partial discharge or overheating by detecting related characteristic gas generated by an XPLE cable.

In order to achieve the purpose, the invention adopts the technical scheme that: a XPLE cable partial discharge or overheated gas monitoring method, this monitoring method is realized on the basis of the following system, in laying and exchanging the pipeline or tunnel of XPLE cable, mount a gas sensor at a certain distance, each gas sensor connects signal amplifier, A/D conversion module and microprocessor sequentially and then connects with the alarm, the alarm is connected with remote host computer; by detecting characteristic gases CO and CH generated in partial discharge or overheating process of XPLE cable₄And C₂H₄The method realizes monitoring of XPLE cable partial discharge or overheating, and comprises the following specific steps:

step 1, turning on a power supply of the gas sensor, correcting the gas sensor after preheating the gas sensor, and detecting characteristic gases CO and CH by the gas sensor when an XPLE cable is free of defects₄And C₂H₄The concentrations are all close to 0, and the alarm does not act; then, the corresponding gas sensors are respectively tested by using three characteristic gases with the concentration of 10ppm, so that the gas concentration calculated by the microprocessor is equal to the corresponding concentration, and the alarm sends corresponding message information of the gas sensors to the remote host;

step 2, starting monitoring after the correction is finished; in normal operation, the gas environment of the XPLE cable is air, and three characteristic gases are CO and CH₄And C₂H₄The content is very small, three characteristic gases detected by the gas sensor do not reach an alarm threshold value, and the alarm does not act;

step 3, when a partial discharge occurs at a position inside the XPLE cable orWhen overheating occurs or partial discharge and overheating occur simultaneously, the XPLE insulating layer begins to decompose, and characteristic gases CO and CH are gradually generated₄And C₂H₄And gradually accumulating near the defect, and if the gas sensor closest to the defect detects that the concentration of one or more characteristic gases is abnormal, the alarm sends message information to the remote host;

and 4, determining the line section with the defect according to the position information of the gas sensor in the message information, and realizing the positioning of the fault.

In the above-mentioned XPLE cable partial discharge or overheating gas monitoring method, one gas sensor is installed at every same distance.

In the above method for monitoring the XPLE cable partial discharge or overheating gas, the conductor of the XPLE cable is copper, and the insulating layer is XPLE.

The invention has the beneficial effects that: the method can be applied to XPLE cable laying places with weak gas circulation and is not restricted by cable laying modes. The defect positioning can be carried out, and the line section with the defect can be determined according to the position information of the gas sensor in the message. The gas detection method is free from interference of factors such as electromagnetism and the like, and is high in sensitivity.

Drawings

FIG. 1 is a schematic view of a gas monitoring schematic for partial discharge or overheating of an XPLE cable according to one embodiment of the present invention;

FIG. 2 is a schematic view of a XPLE cable monitoring system under normal conditions in accordance with one embodiment of the present invention;

figure 3 is a schematic view of the inside of an XPLE raceway or tunnel in the presence of a defect according to an embodiment of the present invention.

Detailed Description

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

The embodiment is realized by the following technical scheme that the method for monitoring the gas generated by the XPLE cable in the partial discharge or overheat state reflects whether the partial discharge or overheat state occurs or not by detecting the related characteristic gas generated by the XPLE cable. As shown in FIG. 1, the method is not affected by electromagnetic interference and has high sensitivity. In laying XPLIn the pipeline or tunnel of the E cable, a gas sensor is arranged at a certain distance (such as every 200 meters) and is used for monitoring characteristic gas generated under the condition of partial discharge or overheating of the XPLE cable, wherein the characteristic gas comprises CO and CH₄And C₂H₄And the like. CO is not certain because the moisture originally present in the air is uncertain₂Due to its high density, it is easily deposited under the air, so moisture and CO are not detected₂. When the cable has no local discharge or local overheat, the XPLE insulating layer is hardly decomposed, the characteristic gas detected by the gas sensor cannot reach the threshold value, and the alarm does not act; once partial discharge or overheating defect occurs in the cable or the two conditions occur simultaneously, XPLE decomposes to generate characteristic gases CO and CH₄And C₂H₄The characteristic gas is gathered and diffused to the gas sensor to be detected by the gas sensor, and the concentration of the corresponding gas is calculated by the microprocessor after passing through the A/D conversion module. The detected concentrations of the three characteristic gases are compared with a preset concentration threshold, the concentration of any one characteristic gas exceeds the preset threshold, (including 7 conditions that only one characteristic gas exceeds the preset concentration, two characteristic gases exceed the preset concentration or three characteristic gases exceed the preset concentration at the same time), the alarm sends a fault message to the remote host, and the alarm does not act when none of the three characteristic gases exceeds the threshold, so that the monitoring of partial discharge or overheating of the XPLE cable is achieved.

Moreover, the monitored latent fault includes only partial discharge, only overheating, and the presence of both partial discharge and overheating.

Furthermore, three characteristic gases CO, CH to be monitored₄And C₂H₄If one of the gases exceeds the set value, defects including CO and CH occur₄、C₂H₄CO and CH₄CO and C₂H₄、CH₄And C₂H₄CO and CH₄And C₂H₄Seven cases.

In specific implementation, firstly, the equipment involved in monitoring XPLE cable partial discharge or overheating is described:

XPLE cable 7 is actual engineering application's cable, and the conductor is the copper, and the insulating layer is XPLE, and length is several hundred meters to kilometers.

The gas sensor 1 is a common gas sensor capable of detecting CO and CH₄And C₂H₄Gas is detected in an equal range of 5-500 ppm, and the sensitivity is high<0.5, response time<60s, the working temperature is minus 10 ℃ to plus 50 ℃, the circuit voltage is 5V plus or minus 0.2V, and the working humidity is 10 percent to 95 percent RH (no condensation).

The signal amplifier 2 is a commonly used sensor signal amplifier, the input voltage is several mV, the output voltage is 0-5V, the output current is 0-10 mA, the working voltage is 5-10V, and the working temperature is-20-80 ℃.

The A/D conversion module 3 is a common A/D conversion device, the input voltage is-10 to +10V, the working temperature is-25 to 85 ℃, and the humidity is 5 to 95 percent RH (without condensation).

The microprocessor 4 is a general small-sized processor capable of performing digital signal operation.

The alarm 5 is an electronic alarm, the working voltage is AC220V, the working temperature is-30-70 ℃, the working humidity is 10-95% (no condensation), and the warning mode is to send message information to the remote host.

The remote host 6 is a communication computer and can receive message information of the alarm.

The monitoring method for the XPLE cable to carry out partial discharge or overheating comprises the following steps: as shown in fig. 3, in the inside of the pipeline or tunnel, near the XPLE cable 7, the gas sensor 1 is installed at a certain distance, the gas sensor 1, the signal amplifier 2, the a/D conversion module 3, the microprocessor 4 and the alarm 5 are correctly connected, the power supply of the gas sensor is turned on, and the gas sensor 1 is corrected after being preheated. When the XPLE cable 7 is not defective, the concentrations of three characteristic gases detected by the gas sensor 1 are all close to 0, and the alarm 5 does not act; the corresponding gas sensor 1 is then tested with three characteristic gases of a certain concentration (e.g., 10ppm) respectively, such that the gas concentration calculated by the microprocessor 4 is approximately equal to the corresponding concentration, and the alarm 5 sends relevant sensor message information to the remote host 6. After the correction is finished, the defect exceeding the set concentration can be monitored.

In normal operation, the gas environment of the XPLE cable 7 is air, and the characteristic gas (such as CO and CH) to be detected in the air₄And C₂H₄Etc.) content is extremely low, the signals detected by the gas sensors 1 of the three characteristic gases do not reach the set values after being calculated by the microprocessor 4, and the alarm 5 does not give an alarm, as shown in fig. 2.

When partial discharge or overheating or even both of them occur in a part inside the XPLE cable 7, the XPLE insulating layer begins to decompose and generates CO and CH gradually₄And C₂H₄Etc. characteristic gas as shown in fig. 3. The characteristic gases are gradually accumulated near the defect, the gas sensor 1 closest to the defect detects that the concentration of one or more of the characteristic gases is abnormal, for example, one of CO, CH4 or C2H4 exceeds the set concentration, or two of CO and CH4, CO and C2H4, CH4 and C2H4 exceed the set concentration at the same time, or three of CO and CH4 and C2H4 exceed the set concentration at the same time, and then the alarm 5 sends message information of the corresponding gas sensor to the remote host 6. And determining the defective line section according to the position information of the gas sensor in the message information, realizing approximate positioning of the fault and only needing to overhaul the corresponding line section.

It should be understood that parts of the specification not set forth in detail are well within the prior art.

Although specific embodiments of the present invention have been described above with reference to the accompanying drawings, it will be appreciated by those skilled in the art that these are merely illustrative and that various changes or modifications may be made to these embodiments without departing from the principles and spirit of the invention. The scope of the invention is only limited by the appended claims.

Claims (1)

1. A monitoring method for XPLE cable partial discharge or overheated gas is realized based on the following system, in laying the pipeline or tunnel of XPLE cable, install a gas sensor at an interval, each gas sensor connects signal amplifier, A/D conversion module and microprocessor in proper order then with the alarm connection, the alarm is connected with long-range main ownerMachine connection; the method is characterized in that characteristic gases CO and CH generated in the process of partial discharge or overheating of XPLE cable are detected₄And C₂H₄The method realizes monitoring of XPLE cable partial discharge or overheating, and comprises the following specific steps:

step 1, turning on a power supply of the gas sensor, correcting the gas sensor after preheating the gas sensor, and detecting characteristic gases CO and CH by the gas sensor when an XPLE cable is free of defects₄And C₂H₄The concentrations are all close to 0, and the alarm does not act; then, the corresponding gas sensors are respectively tested by using three characteristic gases with the concentration of 10ppm, so that the gas concentration calculated by the microprocessor is equal to the corresponding concentration, and the alarm sends corresponding message information of the gas sensors to the remote host;

step 2, starting monitoring after the correction is finished; in normal operation, the gas environment of the XPLE cable is air, and three characteristic gases are CO and CH₄And C₂H₄The content is very small, three characteristic gases detected by the gas sensor do not reach an alarm threshold value, and the alarm does not act;

step 3, when partial discharge or overheating occurs at a certain position inside the XPLE cable or the partial discharge and the overheating occur simultaneously, the XPLE insulating layer starts to decompose to gradually generate characteristic gases CO and CH₄And C₂H₄And gradually accumulating near the defect, and if the gas sensor closest to the defect detects that the concentration of one or more characteristic gases is abnormal, the alarm sends message information to the remote host;

and 4, determining the line section with the defect according to the position information of the gas sensor in the message information, and realizing the positioning of the fault.

Images