Temperature control method and system for cable current-carrying capacity test

Abstract

The invention provides a temperature control method and system for a cable current-carrying capacity test. The scheme comprises the following steps: respectively establishing a simulation loop and a test loop of a to-be-tested cable; a cable preset position of the simulation loop is locally excavated, and the local excavation is to excavate a cable protection layer outside a cable conductor; according to a cable current-carrying capacity test requirement, setting a temperature sensor at a corresponding position of the local digging area, and integrally backfilling the digging area through the dug cable part; according to the temperature requirement of the test loop, the current size meeting the current temperature requirement is determined by adjusting the current size of the simulation loop and combining the temperature value obtained by the temperature sensor; and based on the obtained current magnitude, temperature control of the cable in the test loop is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of cable current carrying capacity test, and in particular relates to a temperature control method and system for cable current carrying capacity test. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention, and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] During the type test of high-voltage cables, it is necessary to perform a load cycle test on the cable test circuit. During the load cycle test, a through-hole transformer is needed to heat the cable simulation circuit. For example, the AC cable should be heated to a conductor temperature that exceeds the maximum conductor temperature of the cable in normal operation, which is 0K to 5K. At present, the method of implanting sensors through cable pinholes is generally used. The temperature sensor is placed in the conductor to detect the cable conductor temperature. For the detection of the temperature of the cable metal sheath, the sensor is implanted into the metal sheath through a pinhole, and the temperature sensor is placed at the metal sheath for temperature measurement.

[0004] The inventors found that the existing solutions have the following problems: the setting position of the temperature sensor can only be determined according to the pinhole implantation position, and the pinhole implantation position is determined according to the pinhole implantation depth. Since there is a buffer layer in the high-voltage cable, the buffer layer is easily deformed due to compression. At the same time, due to the production deviation of the thickness of the insulating layer, the actual pinhole implantation position is inconsistent with the expectation, resulting in inaccurate cable temperature measurement, and further unable to achieve accurate control of the temperature of the cable current carrying capacity test, resulting in the problem that the test results are inconsistent with the actual results. Summary of the invention

[0005] The embodiments of the present invention provide a temperature control method and system for a cable current carrying capacity test, so as to solve the problem that the traditional solution is to set a temperature sensor by implanting a pinhole, the actual position of the pinhole implantation is inconsistent with the expectation, resulting in inaccurate cable temperature measurement, and thus the temperature of the cable current carrying capacity test cannot be accurately controlled, resulting in the test result being inconsistent with the actual situation.

[0006] According to a first aspect of an embodiment of the present invention, there is provided a temperature control method for a cable current carrying capacity test, comprising:

[0007] Establish the simulation loop and test loop of the cable to be tested respectively;

[0008] Performing local excavation on a preset position of the cable of the simulated loop, wherein the local excavation is performed on the cable protective layer outside the cable conductor;

[0009] According to the requirements of the cable current-carrying capacity test, temperature sensors are set at corresponding positions in the locally excavated area, and the excavated area is filled in as a whole through the excavated part of the cable.

[0010] According to the temperature requirements of the test circuit, by adjusting the current magnitude of the simulation circuit and combining with the temperature values obtained from the temperature sensors, the current magnitude that meets the current temperature requirements is determined.

[0011] Based on the obtained current magnitude, temperature control of the cable in the test circuit is achieved.

[0012] Furthermore, both the simulation circuit and the test circuit are arranged in a U shape. The local excavation of the preset position of the cable in the simulation circuit is specifically as follows: local excavations are respectively carried out on the two straight sections and one arc section of the simulation circuit, and temperature sensors are set at corresponding positions in the locally excavated area according to the requirements of the cable current-carrying capacity test.

[0013] Furthermore, the adjustment of the current magnitude of the simulation circuit is carried out by using a through-core transformer.

[0014] Furthermore, the determination of the current magnitude that meets the current temperature requirements by adjusting the current magnitude of the simulation circuit and combining with the temperature values obtained from the temperature sensors is specifically as follows: the current magnitude of the simulation circuit is adjusted by adjusting the voltage of the through-core transformer. At the same time, the temperature values of the temperature sensors at multiple measuring points in the simulation circuit are obtained in real time. Based on the verification results of the obtained multiple temperature values, the temperature value of the preset position of the cable in the current simulation circuit is determined, and based on the obtained temperature values, the corresponding current magnitude that meets the temperature requirements of the current test circuit is determined.

[0015] Furthermore, the cable protective layer outside the cable conductor includes a conductor shielding layer, an insulating layer, an insulation shielding layer, a buffer layer, a metal sheath, an anti-corrosion layer, an outer sheath, and an outer electrode.

[0016] Furthermore, the temperature sensor adopts a wireless thermocouple, and the acquisition of temperature signals is realized through a wireless transmission method.

[0017] Furthermore, the temperature sensor is arranged at the preset position of the cable through a non-magnetic disc.

[0018] According to the second aspect of the embodiments of the present invention, a temperature control system for cable current-carrying capacity test is provided. Based on the above temperature control method for cable current-carrying capacity test, the system includes a simulation circuit and a test circuit constructed based on the cable to be tested, where:

[0019] The simulation loop is used to determine the current magnitude that meets the current temperature requirement by adjusting the current magnitude of the simulation loop according to the temperature requirement of the test loop and combining with the temperature value obtained from the temperature sensor. Specifically, the temperature sensor in the simulation loop is set as follows: a local excavation is performed on a preset position of the cable in the simulation loop, where the local excavation is for the cable protective layer outside the cable conductor; according to the cable current-carrying capacity test requirement, a temperature sensor is set at the corresponding position in the locally excavated area, and the excavated cable part is used to fill the excavated area as a whole.

[0020] The test loop is used to control the temperature of the cable to be tested based on the obtained current magnitude and realize the cable current-carrying capacity test.

[0021] Further, the simulation loop includes the cable to be tested and a through-core transformer, and the test cable passes through the through-core transformer and forms a U-shaped loop.

[0022] Further, the test loop includes the cable to be tested, dry test terminals connected to both ends of the cable to be tested, and a through-core transformer, where the test cable passes through the through-core transformer.

[0023] The above one or more technical solutions have the following beneficial effects:

[0024] (1) The present invention provides a temperature control method and system for cable current-carrying capacity test. By locally excavating the cable in the simulation loop, then accurately setting the temperature sensor at the corresponding position, and filling it with the excavated cable part, accurate temperature measurement can be achieved. Compared with the traditional method of implanting the temperature sensor through a pinhole, the solution of the present invention can effectively improve the accuracy of cable temperature measurement.

[0025] (2) The solution of the present invention adjusts the temperature of the cable in the simulation loop through a through-core transformer (that is, by controlling the voltage of the through-core transformer to adjust the current of the simulation loop, and then realizing the adjustment of the cable temperature), and combines with the temperature value collected by the accurately set temperature sensor, so as to accurately obtain the current value corresponding to the temperature that meets the test requirements, and then effectively ensure the test accuracy.

[0026] (3) The solution of the present invention welds the thermocouple on a non-magnetic material and fixes the non-magnetic material at a preset position of the cable (such as the cable conductor), which can effectively ensure that the contact method is surface contact rather than point contact. On the one hand, it ensures the stability of the installation, and on the other hand, it makes the temperature sensor receive heat evenly, thereby improving the accuracy of temperature detection.

[0027] The advantages of the additional aspects of the present invention will be partially given in the following description, partially become obvious from the following description, or be understood through the practice of the present invention. Brief Description of the Drawings

[0028] The accompanying drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0029] Figure 1 It is a flowchart of a temperature control method for cable ampacity test described in the embodiments of the present invention;

[0030] Figure 2 It is a trapezoidal top view of a cable after cutting on the cable body described in the embodiments of the present invention;

[0031] Figure 3 It is a schematic diagram of a cable type test circuit described in the embodiments of the present invention;

[0032] Among them, 1. Cable conductor; 2. Conductor shielding layer; 3. Insulation layer; 4. Insulation shielding layer; 5. Buffer layer; 6. Metal sheath; 7. Anticorrosion layer; 8. Outer sheath; 9. Outer electrode; 10. Dry test terminal; 11. Test circuit; 12. Through-core transformer; 13. Simulation circuit; 14. Cable joint. Detailed Description of the Embodiments

[0033] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0034] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention.

[0035] In the case of no conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0036] In one or more embodiments, as Figure 1 shown, this embodiment provides a temperature control method for cable ampacity test, which specifically includes the following processing procedures:

[0037] Step 1: Establish a simulation circuit and a test circuit for the cable to be tested respectively; among them, as Figure 3 shown, the specific structures of the simulation circuit and the test circuit are shown.

[0038] Specifically, the construction of the simulation circuit and the test circuit specifically includes the following processing procedures:

[0039] Step 101. Determine the installation position: According to the design requirements of the experimental circuit, as Figure 3As shown, install the through-core transformer at a suitable location. Generally, it should be installed in a place convenient for connecting high-voltage cables and other experimental equipment, and sufficient space should be left around it for operation and maintenance. Considering the location of the through-core transformer, determine the positions of the simulation circuit and the test circuit.

[0040] Step 102: Fix the through-core transformer: Use anchor bolts or other fixing devices to firmly fix the through-core transformer on the foundation or mounting bracket to ensure that the through-core transformer does not move or shake during the experiment.

[0041] Step 103: Connect the cables: Pass the high-voltage cable through the central through-hole of the through-core transformer, and pay attention not to damage the insulation layer of the cable during the insertion process. After the cable is inserted, connect the two ends of the cable to other equipment in the test circuit, such as a high-voltage generator, a voltage divider, etc. When connecting the cables, ensure that the connections are firm and the contacts are good, and suitable connectors and clamps can be used for fixation.

[0042] Step 104: Connect the grounding wire: Reliably connect the grounding terminal of the through-core transformer to the grounding system of the test circuit. The grounding resistance should meet the requirements of relevant standards, generally not exceeding 4Ω.

[0043] Step 105: Install the cooling system: If the through-core transformer generates a large amount of heat during operation, a corresponding cooling system, such as an air-cooling or water-cooling system, needs to be installed, and ensure that the cooling system is tightly connected to the through-core transformer and operates normally.

[0044] Step 2: Locally excavate the preset position of the cable in the simulation circuit, where the local excavation is for the cable protective layer outside the cable conductor 1.

[0045] In a specific implementation, the cable protective layer outside the cable conductor includes a conductor shielding layer 2, an insulating layer 3, an insulation shielding layer 4, a buffer layer 5, a metal sheath 6, an anti-corrosion layer 7, an outer sheath 8, and an outer electrode 9.

[0046] In a specific implementation, the local excavation of the preset position of the cable in the simulation circuit is specifically as follows: Locally excavate at two straight sections and one arc section of the simulation circuit respectively, and set temperature sensors at corresponding positions in the locally excavated areas according to the requirements of the cable current-carrying capacity test.

[0047] Specifically, as Figure 3 shown, the test simulation circuit is generally U-shaped. At least three pieces of cable need to be cut from two straight sections and one arc section respectively. Peel off the semi-conductive tape, place temperature sensors on the surface of the cable conductor respectively, and then put the cut cables back to detect the temperatures at the three places.

[0048] It is understandable that in more embodiments, the temperature sensor can also be placed in other cable protective layers outside the cable conductor.

[0049] In more embodiments, it is necessary to calibrate the deployed temperature sensors. Specifically:

[0050] Select a temperature sensor with a temperature measurement accuracy of 0.1 °C. Boil a kettle of water in a kettle. Put all the temperature sensors to be used into the boiling water. The head of the temperature sensor should not touch the wall of the kettle. Observe the temperature display of the temperature recorder. If the temperature does not show 100 °C, it can be calibrated on the temperature recorder.

[0051] Furthermore, the temperature sensor adopts a wireless thermocouple, and the temperature signal is collected through a wireless transmission method. During the test, through the wireless thermocouple, the cable temperature can be remotely monitored in the test control room. The through-hole variable current can be adjusted according to the test plan to control the cable temperature and meet the test requirements.

[0052] In specific implementation, by installing a preset hole opener on the surface of the cable outer sheath, according to the thickness from the cable conductor shield layer to the outer sheath layer, adjust the cutting depth, and remove the cable protective layer outside the cable conductor at one time, as Figure 2 shown, keep the cut part as a whole during the cutting process.

[0053] In specific implementation, during the partial excavation of the preset position of the cable in the simulation loop, the depth of the hole opener is set as follows: Taking Table 1 as an example, initially set the depth of the hole opener to 35.2 mm ((112.5 - 42.1) / 2). Considering the deviation between the cable production structure size and the design size, the opening depth is based on the fact that the hole opener cannot penetrate further (touching the copper conductor).

[0054] Table 1 Schematic diagram of the structure of 110 kV 1×1200 high-voltage cable

[0055]

[0056]

[0057] Step 3: According to the cable current-carrying capacity test requirements, set the temperature sensor at the corresponding position in the partial excavation area, and use the excavated cable part to backfill the excavation area as a whole;

[0058] In specific implementation, according to the temperature measurement requirement, a thermocouple (i.e., temperature sensor) is placed on the cable conductor, the conductor shielding layer or the insulation shielding layer. The thermocouple is set on a stainless steel disc (non-magnetic material). The stainless steel disc (usually with a diameter of φ20mm) is drilled in the middle (usually with a diameter of φ10mm). A non-magnetic screw (usually with the model of M5) is used to fix the stainless steel disc on the conductor surface, and it is checked whether the thermocouple is firmly installed (check its mechanical performance). The temperature collected by the thermocouple is viewed, compared with the greenhouse, and the electrical performance is checked. Then the cut part of the cable is integrally backfilled. During the backfilling process, according to the requirement, a thermocouple is installed at the insulation shielding part. During the backfilling process, the size of the cut position is kept consistent with that of the uncut position. A temperature sensor is also placed at the cable outer sheath to monitor the temperature of the cable outer sheath. After the backfilling is completed, it is wrapped with insulating tape to do a good job in sealing and waterproofing treatment.

[0059] Step 4: According to the temperature requirement of the test loop, by adjusting the current magnitude of the simulation loop and combining with the temperature value obtained from the temperature sensor, determine the current magnitude when the current temperature requirement is met.

[0060] In specific implementation, the adjustment of the current magnitude of the simulation loop is carried out by using a through-core transformer.

[0061] In specific implementation, the determination of the current magnitude when the current temperature requirement is met by adjusting the current magnitude of the simulation loop and combining with the temperature value obtained from the temperature sensor is specifically as follows: The current magnitude of the simulation loop is adjusted by adjusting the voltage of the through-core transformer. At the same time, the temperature values of the temperature sensors at multiple measuring points in the simulation loop are obtained in real time. Based on the verification results of the obtained multiple temperature values, the temperature value at the preset position of the cable in the current simulation loop is determined, and based on the obtained temperature values, the corresponding current magnitude when the current test loop temperature requirement is met is determined.

[0062] Specifically, after the through-core transformer is turned on and the temperature measurement system of the cable system test loop is installed, according to the previously calculated cable current-carrying capacity, the voltage of the through-core transformer is adjusted to further adjust the current magnitude in the cable loop, so that the conductor of the cable loop reaches the specified temperature within the specified time (generally speaking, the operating temperature of the AC cable conductor is 90°C, and the DC cable conductor is 70°C). At the same time, the temperatures at the conductor shielding part, the insulation shielding part and the cable outer sheath can also be observed.

[0063] Step 5: Based on the obtained current magnitude, realize the temperature control of the cable in the test loop.

[0064] In specific implementation, check the influencing factors around the test circuit, keep the temperatures collected by the thermocouples at the same three positions the same, and after determining the voltage of the through-type transformer in the simulation circuit, keep the test circuit set the same. After completion, the thermal cycle test of the cable system can be carried out normally. Specifically, when carrying out the type test normally, after the temperature measurement system displays normally, all personnel evacuate the laboratory, and the type test is carried out normally according to the corresponding standard requirements.

[0065] In one or more embodiments, a temperature control system for cable ampacity test is based on the above-mentioned temperature control method for cable ampacity test. The system includes a simulation circuit and a test circuit constructed based on the cable to be tested, where:

[0066] The simulation circuit is used to determine the current magnitude that meets the current temperature requirement by adjusting the current magnitude of the simulation circuit according to the temperature requirement of the test circuit and combining the temperature value obtained from the temperature sensor. Among them, the setting of the temperature sensor in the simulation circuit is specifically as follows: locally dig a preset position of the cable in the simulation circuit, where the local digging is for the cable protective layer outside the cable conductor; according to the cable ampacity test requirements, set the temperature sensor at the corresponding position in the locally dug area, and fill the dug area as a whole through the dug part of the cable.

[0067] The test circuit is used to control the temperature of the cable to be tested based on the obtained current magnitude to implement the cable ampacity test.

[0068] In specific implementation, the simulation circuit 13 includes the cable to be tested and a through-type transformer, and the test cable passes through the through-type transformer and forms a U-shaped circuit.

[0069] In specific implementation, the test circuit 11 includes the cable to be tested, dry test terminals 10 connected to both ends of the cable to be tested, and a through-type transformer 12, where the test cable passes through the through-type transformer. As Figure 3 shown, the two sections of cable in the test circuit are connected by a cable joint 14.

[0070] The method in the above embodiments can be directly implemented by a hardware processor, or implemented by a combination of hardware and software modules in the processor. The software module can be located in a mature storage medium in the art such as random access memory, flash memory, read-only memory, programmable read-only memory, or electrically erasable programmable memory, register, etc. This storage medium is located in the memory, and the processor reads the information in the memory and combines its hardware to complete the steps of the above method. To avoid repetition, it will not be described in detail here.

[0071] Those of ordinary skill in the art can realize that the units or algorithm steps of the examples described in conjunction with this embodiment can be implemented by electronic hardware or a combination of computer software and electronic hardware. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. Professional technicians can use different methods for each specific application to implement the described functions, but such implementation should not be considered to exceed the scope of the present invention.

[0072] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A temperature control method for cable current carrying capacity test, characterized in that: include: Establish the simulation loop and test loop of the cable to be tested respectively; Performing local excavation on a preset position of the cable of the simulated loop, wherein the local excavation is performed on the cable protective layer outside the cable conductor; According to the cable current carrying capacity test requirements, the temperature sensor is set at the corresponding position of the local excavation area, and the excavated area is backfilled as a whole through the excavated cable part; According to the temperature requirement of the test circuit, the current size of the simulation circuit is adjusted, and combined with the temperature value obtained by the temperature sensor, the current size that meets the current temperature requirement is determined; Based on the obtained current, the temperature of the cable in the test loop is controlled.

2. The temperature control method for cable current carrying capacity test according to claim 1, characterized in that: The temperature sensor is arranged at a preset position of the cable through a non-magnetic disc.

3. The temperature control method for cable current carrying capacity test according to claim 2, characterized in that: The simulation loop and the test loop both adopt a U-shaped setting, and the preset cable position of the simulation loop is locally excavated, specifically: local excavation is performed on two straight sections and one arc section of the simulation loop respectively, and temperature sensors are set at corresponding positions of the local excavated areas according to the cable current carrying capacity test requirements.

4. The temperature control method for cable current carrying capacity test according to claim 1, characterized in that: The current size of the simulation loop is adjusted by using a through-hole transformer.

5. The temperature control method for cable current carrying capacity test according to claim 1, characterized in that: The current size when the current requirement is met is determined by adjusting the current size of the simulation loop in combination with the temperature value obtained by the temperature sensor. Specifically, the current size of the simulation loop is adjusted by adjusting the voltage of the through-hole transformer, and at the same time, the temperature values ​​of the temperature sensors at multiple measuring points of the simulation loop are obtained in real time. Based on the verification results of the multiple temperature values ​​obtained, the temperature value of the preset position of the cable in the current simulation loop is determined, and based on the obtained temperature value, the corresponding current size when the temperature requirement of the current test loop is met is determined.

6. The temperature control method for cable current carrying capacity test according to claim 1, characterized in that: The cable protective layer outside the cable conductor includes a conductor shielding layer, an insulating layer, an insulating shielding layer, a buffer layer, a metal sheath, an anti-corrosion layer, an outer sheath and an outer electrode.

7. The temperature control method for cable current carrying capacity test according to claim 1, characterized in that: The temperature sensor adopts a wireless thermocouple and collects temperature signals through wireless transmission.

8. A temperature control system for cable current carrying capacity testing, characterized in that: It is based on the temperature control method for cable current carrying capacity test according to any one of claims 1 to 7, the system comprises a simulation circuit and a test circuit constructed based on the cable to be tested, wherein: The simulation loop is used to determine the current size when the current requirement is met by adjusting the current size of the simulation loop according to the temperature requirement of the test loop, combined with the temperature value obtained by the temperature sensor; wherein the setting of the temperature sensor in the simulation loop is specifically as follows: local excavation is performed on the preset position of the cable of the simulation loop, wherein the local excavation is performed on the cable protective layer outside the cable conductor; according to the cable current carrying capacity test requirements, the temperature sensor is set at the corresponding position of the local excavation area, and the excavation area is backfilled as a whole through the excavated cable part; The test circuit is used to control the temperature of the cable to be tested based on the obtained current size, so as to realize the cable current carrying capacity test.

9. The temperature control system for cable current carrying capacity test according to claim 8, characterized in that: The simulation loop includes a cable to be tested and a through-hole transformer, and the test cable passes through the through-hole transformer to form a U-shaped loop.

10. The temperature control system for cable current carrying capacity test according to claim 8, characterized in that: The test loop includes a cable to be tested, dry test terminals connected to both ends of the cable to be tested, and a through-hole transformer, wherein the test cable passes through the through-hole transformer.

Images