Method and equipment for monitoring and evaluating degassing state of high-voltage cable

Abstract

The invention provides a method and equipment for monitoring and evaluating the degassing state of a high-voltage cable. The method comprises the following steps: pasting a monitoring label on the high-voltage cable based on a spacing distance, and sending the high-voltage cable into a degassing chamber for degassing treatment; monitoring temperature is obtained according to the temperature monitoring label, and the monitoring temperature and the critical temperature are compared; when the monitoring temperature is in an under-temperature state or an over-temperature state, working parameters are adjusted; when the monitoring temperature is higher than the aging initial temperature, obtaining a marking section according to the position of the temperature monitoring label on the high-voltage cable; obtaining a degassing end point according to a color changing result of the gas sensing color changing label; and after taking out, obtaining a final-state cable based on mark section processing. According to the high-voltage cable degassing state monitoring and evaluating method and equipment, the degassing process and the degassing effect can be evaluated, the aging occurrence rate is reduced, the process is simple, the degassing end point determination is high in accuracy and visual, and the operation is economical, simple and convenient.

Description

Technical Field

[0001] The present invention relates to the technical field of high-voltage cable degassing state evaluation, and in particular to a method and device for monitoring and evaluating the degassing state of a high-voltage cable. Background Art

[0002] Cross-linked polyethylene (XLPE) has been widely used in AC and DC power high-voltage cables due to its excellent electrical, heat-resistant and mechanical properties. XLPE is obtained by cross-linking and modification of polyethylene (PE). At present, XLPE cables are widely produced by peroxide cross-linking using diisopropylbenzene peroxide (DCP) as a cross-linking agent. During the thermal decomposition process, DCP will produce a variety of cross-linking by-products such as cumyl alcohol, acetophenone, styrene, methane, water, etc., which will affect the performance of XLPE and seriously threaten the operation safety of high-voltage cables. In order to reduce the effect of cross-linking by-products, in actual high-voltage cable production, the high-voltage cables will be degassed after cross-linking. During the degassing process, the cross-linking by-products volatilize, thereby ensuring the insulation performance of the high-voltage cable. At present, the methods for determining or evaluating the degassing time or degassing state of high-voltage cables during the production process are:

[0003] CN111736043A provides a method for evaluating the degassing state of XLPE cables based on low-frequency dielectric spectroscopy, wherein the dielectric loss tangent value of the XLPE cable during the degassing process is measured online, and whether the XLPE cable has reached the degassing end point is determined based on the online measurement result of the dielectric loss tangent value. Although this method can truly reflect the degassing condition of the measured cable, timely discover and detect changes in the internal insulation state of the XLPE cable, and determine the degassing end point based on existing measurement data, the dielectric loss angle is a highly sensitive project, and the test data is easily affected by the interference of the external electric field and produces a large deviation. In addition, the instrument requirements are high, and the high-precision measuring instrument is expensive, complicated to operate, and requires a high technical level of the tester.

[0004] CN102426885A provides a method for degassing a flexible DC transmission cable, wherein the cable core is evenly wound on a cable reel to form several layers of core coils and placed in a closed container; a heating device and a temperature measuring device are turned on to heat the air in the closed container; the heating device and the temperature measuring device are turned off to take out the cable core; a section of the cable core is selected for residual pressure detection, and if the detection fails, the step 2 is returned to, and if the detection passes, the cable degassing is completed. Although this method can effectively reduce the concentration of decomposition byproducts in the insulating material, improve the electrical properties of the insulating material, and inhibit the accumulation of space charge in the insulating material, it cannot timely discover and detect changes in the internal insulation state of the XLPE cable, and in most cases multiple degassing is required, the process is cumbersome, and the results are not intuitive.

[0005] CN114184612A provides a method for evaluating the degassing effect of a cross-linked polyethylene cable, wherein a cable sample to be tested is subjected to a heating treatment to obtain a transparent cable sample to be tested whose insulation layer is in a transparent state; under darkroom conditions, at least one spot image of the transparent cable sample to be tested under the irradiation of a monochromatic laser light source is obtained; light intensity data of at least one spot image within a preset spot image range is extracted; the light intensity data is normalized to obtain the maximum value and average value of the normalized light intensity coefficient of the transparent cable sample to be tested within the preset insulation layer thickness range; a degassing uniformity coefficient is calculated based on the maximum value and average value; and an evaluation result of the degassing effect of the cross-linked polyethylene cable is obtained based on the maximum value, average value and degassing uniformity coefficient. This method can only detect the degassing effect of the cable after degassing, and a heating treatment is required before detection. There are many steps and changes in the internal insulation state of the XLPE cable cannot be discovered and detected in time. Summary of the invention

[0006] In view of the problems existing in the prior art, the present invention provides a method and equipment for monitoring and evaluating the degassing status of a high-voltage cable, which can monitor the degassing process of the high-voltage cable according to a temperature monitoring label and a gas sensing color-changing label to evaluate the degassing process and the degassing effect, has strong production guidance, low aging rate, economical and simple operation, high accuracy in confirming the degassing endpoint, simple process, and intuitive results.

[0007] To achieve the above object, the technical solution adopted by the present invention is as follows: A method for monitoring and evaluating the degassing state of a high-voltage cable comprises the following steps:

[0008] Get the interval distance;

[0009] Based on the spacing distance, a plurality of monitoring labels are attached to the high-voltage cable to obtain a cable to be degassed, wherein the monitoring labels include a temperature monitoring label and a gas sensing color changing label; the gas sensing color changing label is used to sense the concentration of byproducts during degassing;

[0010] The cable to be degassed is sent into a degassing chamber, working parameters are set, and the degassing process is started;

[0011] Obtaining critical temperatures, wherein the critical temperatures include a degassing temperature lower limit, a degassing temperature upper limit, and an aging initial temperature;

[0012] Obtain the monitored temperature according to the temperature monitoring tag, and compare the monitored temperature with the critical temperature:

[0013] When the monitored temperature is in an under-temperature state or an over-temperature state, adjusting the working parameters; the under-temperature state is when the monitored temperature is lower than the lower limit of the degassing temperature, and the over-temperature state is when the monitored temperature is between the upper limit of the degassing temperature and the initial aging temperature;

[0014] When the monitoring temperature is higher than the initial aging temperature, obtaining a marking segment according to the position of the temperature monitoring tag on the high-voltage cable;

[0015] Obtaining a degassing endpoint according to the color change result of the gas sensing color change label;

[0016] Stop the degassing process according to the degassing endpoint to obtain an intermediate cable, and take out the intermediate cable from the degassing chamber;

[0017] The intermediate-state cable is processed based on the marker segment to obtain a final-state cable.

[0018] Further, the operating parameters include operating temperature and air flow rate;

[0019] When the proportion of the temperature monitoring tags in the under-temperature state or in the over-temperature state is less than 20%, adjusting the working parameter by increasing the air flow rate;

[0020] When the proportion of the temperature monitoring tags in the under-temperature state is ≥ 20%, and there is no temperature monitoring tag in the over-temperature state, adjusting the working parameter by increasing the working temperature;

[0021] When the proportion of the temperature monitoring tags in the over-temperature state is ≥20%, and there is no temperature monitoring tag in the under-temperature state, the operating parameter is adjusted by lowering the operating temperature.

[0022] Furthermore, the voltage level of the high-voltage cable is a conventional high-voltage cable, an extra-high-voltage cable or an ultra-high-voltage cable.

[0023] Furthermore, the temperature monitoring tag is a passive online temperature monitoring tag.

[0024] Furthermore, the color change of the gas-sensing color-changing label is irreversible.

[0025] Furthermore, the lower limit of the degassing temperature is 65-70°C, the upper limit of the degassing temperature is 75-80°C, and the initial aging temperature is 80-85°C.

[0026] Furthermore, the interval between adjacent monitoring tags is 15 to 25 meters.

[0027] Furthermore, based on the marker segment, marker segment data is obtained according to the monitoring tag.

[0028] Furthermore, when a plurality of the gas-sensing color-changing labels all change color, the degassing endpoint is obtained.

[0029] A device for implementing the above-mentioned high-voltage cable degassing state monitoring and evaluation method, comprising a data processing unit, a control unit, a post-processing unit and a plurality of the above-mentioned monitoring tags;

[0030] Several of the monitoring tags:

[0031] Used to stick on the high-voltage cable based on the spacing distance to obtain the cable to be degassed;

[0032] The data processing unit:

[0033] Used to obtain and input the critical temperature;

[0034] Used to obtain the monitoring temperature according to the temperature monitoring tag;

[0035] for comparing the monitored temperature with the critical temperature and obtaining the marking segment and the first control signal;

[0036] Used to obtain the degassing endpoint according to the color change result of the gas sensing color change label;

[0037] Used to obtain a second control signal according to the degassing endpoint;

[0038] for transmitting the first control signal and the second control signal to the control unit;

[0039] The control unit:

[0040] Used to set the working parameters;

[0041] For starting the degassing process;

[0042] used to adjust the operating parameter according to the first control signal;

[0043] for stopping the degassing process according to the second control signal to obtain the intermediate state cable;

[0044] The post-processing unit:

[0045] Used to process the intermediate state cable based on the marking segment to obtain the final state cable.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] 1. The present invention uses a temperature monitoring label to monitor the degassing process of the high-voltage cable to ensure the quality of the degassing process, and combines a gas sensing color-changing label to identify the concentration of by-products during the degassing process to obtain the degassing endpoint, thereby realizing the evaluation of the degassing process and degassing effect of the high-voltage cable, and further realizing the evaluation of the degassing quality of the high-voltage cable;

[0048] 2. The present invention guides the degassing production of high-voltage cables by setting monitoring tags for real-time monitoring, thereby improving the degassing efficiency. In addition, the aging rate of the cable during degassing can be effectively reduced, and the aged parts can be marked to facilitate subsequent performance evaluation;

[0049] 3. The present invention is economical and simple to operate, has high accuracy of degassing endpoint, simple process, intuitive results, strong production guidance significance, and can be widely used in the manufacture of high-voltage cable products. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 It is a schematic flow chart of the method for monitoring and evaluating the degassing state of a high-voltage cable according to the present invention;

[0051] Figure 2 The figure is a schematic diagram of the working principle of the device for realizing the method for monitoring and evaluating the degassing state of a high-voltage cable according to the present invention. DETAILED DESCRIPTION

[0052] It is worth noting that the methods used in the present invention are all conventional methods unless otherwise specified; the raw materials and devices used are all conventional commercially available products, and their sources are not specifically limited unless otherwise specified.

[0053] See also Figure 1 , a method for monitoring and evaluating the degassing state of a high-voltage cable, comprising the following steps:

[0054] Obtaining the interval distance, preferably, the interval distance is 15 to 25 meters, so as to realize full online monitoring of the temperature at different positions of the high-voltage cable;

[0055] A plurality of monitoring labels are pasted on the high-voltage cable based on the interval distance to obtain the cable to be degassed. Preferably, the monitoring labels are pasted at intervals of 20 meters, and the monitoring labels include temperature monitoring labels and gas sensing color-changing labels; the gas sensing color-changing labels are used to sense the concentration of by-products during degassing treatment; preferably, the voltage level of the high-voltage cable is a conventional high-voltage cable, an ultra-high voltage cable or an ultra-high voltage cable, wherein the voltage level of the conventional high-voltage cable generally refers to 110 kV to 220 kV, the voltage level of the ultra-high voltage cable is between 330 kV and 800 kV, and the voltage level of the ultra-high voltage cable is generally 1000 kV and above, all of which are applicable to the high-voltage cable degassing state monitoring and evaluation method in the embodiment of the present invention;

[0056] Send the cable to be degassed into the degassing chamber, set the working parameters, and start the degassing process;

[0057] Obtain the critical temperature, which includes the lower limit of degassing temperature, the upper limit of degassing temperature and the initial aging temperature. Preferably, the lower limit of degassing temperature is 65-70°C, the upper limit of degassing temperature is 75-80°C, and the initial aging temperature is 80-85°C, wherein the temperature interval between the lower limit of degassing temperature and the upper limit of degassing temperature is the degassing temperature interval. Usually in production, the degassing temperature interval is [70, 80), and the initial aging temperature is 85 degrees;

[0058] Obtain the monitored temperature according to the temperature monitoring tag and compare the monitored temperature with the critical temperature:

[0059] When the monitoring temperature is in an under-temperature state or an over-temperature state, adjust the working parameters; the under-temperature state is when the monitoring temperature is lower than the lower limit of the degassing temperature, that is, the monitoring temperature is less than 70°C. At this temperature, the degassing process does not occur in the cable to be degassed, and the concentration of by-products inside the cable to be degassed is high. The over-temperature state is when the monitoring temperature is between the upper limit of the degassing temperature and the initial aging temperature, that is, the monitoring temperature is ≥80°C and <85°C.

[0060] When the monitoring temperature is higher than the initial aging temperature, the marking segment is obtained according to the position of the temperature monitoring tag on the high-voltage cable;

[0061] The degassing endpoint is obtained according to the color change result of the gas sensing color changing label. The concentration of the by-product during the degassing treatment is determined by the gas sensing color changing label to evaluate the degassing effect. When the concentration of the by-product during the degassing treatment reaches the color change critical value of the gas sensing color changing label, the degassing of the detection part is completed, and the gas sensing color changing label changes color. When all the gas sensing color changing labels change color, the overall degassing of the high-voltage cable is completed, that is, when all the gas sensing color changing labels change color, it is the degassing endpoint;

[0062] Stop the degassing process according to the degassing end point to obtain the intermediate state cable, and take out the intermediate state cable from the degassing chamber;

[0063] The final cable is obtained by processing the intermediate cable based on the marking segment. If no marking segment is generated during the degassing process, the intermediate cable is the final cable. If a marking segment is generated during the degassing process, the final cable is obtained by cutting off the marking segment from the intermediate cable.

[0064] In some preferred embodiments, based on the marking segment, the marking segment data is obtained according to the monitoring label, and the marking segment data includes the time to reach the initial aging temperature, the aging duration, the color change time of the gas-sensing color-changing label corresponding to the marking segment, etc., to facilitate subsequent performance evaluation.

[0065] The temperature monitoring label is used to monitor the degassing process of the high-voltage cable to ensure the quality of the degassing process. The gas sensing color-changing label is used to identify the concentration of by-products during the degassing process to obtain the degassing endpoint, thereby realizing the evaluation of the degassing quality of the high-voltage cable. At the same time, the degassing production of the high-voltage cable is guided to improve the degassing efficiency. In addition, the aging rate of the high-voltage cable during degassing can be effectively reduced, and the aged parts can be marked to facilitate subsequent performance evaluation. The operation is economical and simple, the degassing endpoint is highly accurate, the process is simple, the results are intuitive, and the production guidance significance is strong. It can be widely used in the manufacturing of high-voltage cable products.

[0066] Further, the operating parameters include operating temperature and air flow rate;

[0067] When the proportion of temperature monitoring tags in under-temperature state or over-temperature state is less than 20%, the working parameters are adjusted by increasing the air flow rate. When the monitoring temperature measured by only a small number of temperature monitoring tags is in under-temperature state or over-temperature state, it means that the temperature in the degassing chamber is uneven. By increasing the air flow rate, the temperature uniformity in the degassing chamber can be improved so that all monitoring temperatures enter or return to the degassing temperature range, ensuring the degassing efficiency and quality.

[0068] When the proportion of temperature monitoring tags in the under-temperature state is ≥ 20%, and there is no temperature monitoring tag in the over-temperature state, the working parameters are adjusted by increasing the working temperature. When the monitoring temperature measured by most temperature monitoring tags is in the under-temperature state, and there is no temperature monitoring tag in the over-temperature state, the overall working temperature in the degassing chamber is low. At this time, the working temperature needs to be increased so that the monitoring temperature enters the degassing temperature range. In addition, the air flow rate can also be increased while increasing the working temperature to ensure that the temperature in the degassing chamber is quickly uniform while increasing the temperature of the degassing chamber.

[0069] When the proportion of temperature monitoring tags in overtemperature state is ≥20% and there is no temperature monitoring tag in undertemperature state, the working parameters are adjusted by lowering the working temperature. When the monitoring temperatures measured by most temperature monitoring tags are in overtemperature state and there is no temperature monitoring tag in undertemperature state, the overall working temperature in the degassing chamber is high. At this time, the working temperature needs to be lowered to make the monitoring temperature return to the degassing temperature range. In addition, the air flow rate can be increased while lowering the working temperature to ensure that the temperature in the degassing chamber is quickly uniform while increasing the temperature of the degassing chamber.

[0070] In some of the preferred embodiments, the temperature monitoring tag is a passive online temperature monitoring tag. Since the passive online temperature tag can monitor the temperature in real time online, has high temperature measurement accuracy, is highly flexible, does not require built-in batteries and has no complex circuits, can work stably in harsh environments, can greatly reduce the cost of use, and ensure real-time and measurement accuracy.

[0071] In some preferred embodiments, the color change of the gas sensing color-changing label is irreversible, thereby ensuring the monitoring effect.

[0072] See also Figure 2 , a device for realizing a high voltage cable degassing state monitoring and evaluation method, comprising a data processing unit, a control unit, a post-processing unit and a plurality of monitoring tags;

[0073] Several monitoring tags:

[0074] Used to stick on high voltage cables based on the spacing distance to obtain the cables to be degassed;

[0075] Data processing unit:

[0076] Used to obtain and input critical temperature;

[0077] Used to obtain the monitoring temperature according to the temperature monitoring tag;

[0078] Used to compare the monitoring temperature and the critical temperature, and obtain the marking segment and the first control signal;

[0079] Used to obtain a degassing endpoint according to the color change result of the gas sensing color-changing label;

[0080] Used to obtain a second control signal according to a degassing endpoint;

[0081] for transmitting the first control signal and the second control signal to the control unit;

[0082] Control unit:

[0083] Used to set working parameters;

[0084] Used to start the degassing process;

[0085] Used to adjust the working parameters according to the first control signal;

[0086] Used to stop the degassing process according to the second control signal to obtain an intermediate state cable;

[0087] Post-processing unit:

[0088] Used to process the intermediate cable based on the marker segment to obtain the final cable.

[0089] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the present invention.

Claims

1. A method for monitoring and evaluating the degassing state of a high-voltage cable, characterized in that: The following steps are involved: Get the interval distance; Based on the spacing distance, a plurality of monitoring labels are attached to the high-voltage cable to obtain a cable to be degassed, wherein the monitoring labels include a temperature monitoring label and a gas sensing color changing label; the gas sensing color changing label is used to sense the concentration of byproducts during degassing; The cable to be degassed is sent into a degassing chamber, working parameters are set, and the degassing process is started; Obtaining critical temperatures, wherein the critical temperatures include a degassing temperature lower limit, a degassing temperature upper limit, and an aging initial temperature; Obtain the monitoring temperature according to the temperature monitoring tag, and compare the monitoring temperature with the critical temperature: When the monitored temperature is in an under-temperature state or an over-temperature state, adjusting the working parameters; the under-temperature state is when the monitored temperature is lower than the lower limit of the degassing temperature, and the over-temperature state is when the monitored temperature is between the upper limit of the degassing temperature and the initial aging temperature; When the monitoring temperature is higher than the initial aging temperature, obtaining a marking segment according to the position of the temperature monitoring tag on the high-voltage cable; Obtaining a degassing endpoint according to the color change result of the gas sensing color change label; Stop the degassing process according to the degassing endpoint to obtain an intermediate cable, and take out the intermediate cable from the degassing chamber; The intermediate-state cable is processed based on the marker segment to obtain a final-state cable.

2. The method for monitoring and evaluating the degassing state of a high-voltage cable according to claim 1, characterized in that: The operating parameters include operating temperature and air flow rate; When the proportion of the temperature monitoring tags in the under-temperature state or in the over-temperature state is less than 20%, adjusting the working parameter by increasing the air flow rate; When the proportion of the temperature monitoring tags in the under-temperature state is ≥ 20%, and there is no temperature monitoring tag in the over-temperature state, adjusting the working parameter by increasing the working temperature; When the proportion of the temperature monitoring tags in the over-temperature state is ≥20%, and there is no temperature monitoring tag in the under-temperature state, the operating parameter is adjusted by lowering the operating temperature.

3. The method for monitoring and evaluating the degassing state of a high-voltage cable according to claim 1, characterized in that: The voltage level of the high-voltage cable is a conventional high-voltage cable, an extra-high-voltage cable or an ultra-high-voltage cable.

4. The method for monitoring and evaluating the degassing state of a high-voltage cable according to claim 1, characterized in that: The temperature monitoring tag is a passive online temperature monitoring tag.

5. The method for monitoring and evaluating the degassing state of a high-voltage cable according to claim 1, characterized in that: The color change of the gas-sensing color-changing label is irreversible.

6. The method for monitoring and evaluating the degassing state of a high-voltage cable according to claim 1, characterized in that: The lower limit of the degassing temperature is 65-70°C, the upper limit of the degassing temperature is 75-80°C, and the initial aging temperature is 80-85°C.

7. The method for monitoring and evaluating the degassing state of a high-voltage cable according to claim 1, characterized in that: The interval between adjacent monitoring tags is 15 to 25 meters.

8. The method for monitoring and evaluating the degassing state of a high-voltage cable according to claim 1, characterized in that: Based on the marker segment, marker segment data is obtained according to the monitoring tag.

9. The method for monitoring and evaluating the degassing state of a high-voltage cable according to claim 1, characterized in that: When a plurality of the gas-sensing color-changing labels all change color, the degassing endpoint is obtained.

10. A device for implementing the high-voltage cable degassing state monitoring and evaluation method according to any one of claims 1 to 9, characterized in that: It includes a data processing unit, a control unit, a post-processing unit and a plurality of monitoring tags; Several of the monitoring tags: Used to stick on the high-voltage cable based on the spacing distance to obtain the cable to be degassed; The data processing unit: Used to obtain and input the critical temperature; Used to obtain the monitoring temperature according to the temperature monitoring tag; for comparing the monitored temperature with the critical temperature and obtaining the marking segment and the first control signal; Used to obtain the degassing endpoint according to the color change result of the gas sensing color change label; Used to obtain a second control signal according to the degassing endpoint; for transmitting the first control signal and the second control signal to the control unit; The control unit: Used to set the working parameters; For starting the degassing process; used to adjust the operating parameter according to the first control signal; for stopping the degassing process according to the second control signal to obtain the intermediate state cable; The post-processing unit: Used to process the intermediate state cable based on the marking segment to obtain the final state cable.

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