Method for determining thickness value interval of metal sheath of cable

Abstract

The invention discloses a method for determining a thickness value interval of a metal sheath of a cable. The method comprises the following steps: acquiring a target cable and laying parameters; cable samples with different metal sheath thicknesses are manufactured; respectively carrying out a bending performance test and a short-circuit current temperature test on the sample according to the laying parameters; iteratively adjusting the first initial thickness in the bending test to obtain a first target thickness meeting the bending performance; iteratively adjusting the second initial thickness in the short circuit test to obtain a second target thickness meeting the thermal stability; and determining a thickness value interval of the metal sheath based on the two target thicknesses. According to the invention, the technical problem that it is difficult to design the thickness of the cable metal sheath with both safety and durability in the prior art is solved.

Description

Technical Field

[0001] This invention relates to the field of power cables, and more specifically, to a method for determining the range of metal sheath thickness values ​​for cables. Background Technology

[0002] With the continuous growth of electricity load in some large and medium-sized cities, the voltage level of urban power distribution networks is gradually increasing. To meet the multiple demands of high-density loads, complex wiring structures, and urban aesthetics, more and more large and medium-sized cities are adopting high-voltage, large-section cables in their power grid construction. These cables not only perform excellently in terms of safety, economy, and service life, but have also become the preferred solution for optimizing urban power system design. With the rapid development of urban power grids, the demand for cable lines with higher transmission capacity, better safety performance, and longer service life is showing a continuous upward trend.

[0003] However, during the configuration of the cable's metallic sheath, safety hazards such as the ablation of the buffer layer in corrugated aluminum high-voltage cables still exist due to damage caused by excessive bending of the cable during installation, changes in environmental factors, and aging of the cable during long-term operation. Furthermore, the design of protective measures for different types of cables lacks specific considerations, failing to fully meet the usage requirements of individual cables.

[0004] There is currently no effective solution to the above problems. Summary of the Invention

[0005] This invention provides a method for determining the range of metal sheath thickness values ​​for cables, thereby at least solving the technical problem in related technologies of the difficulty in designing a cable metal sheath thickness that can balance safety and durability.

[0006] According to one aspect of the present invention, a method for determining the range of metallic sheath thickness values ​​for a cable is provided, comprising: acquiring a target cable to be designed and laying parameters, wherein the target cable includes a metallic sheath and an outer sheath; fabricating a plurality of cable samples based on the target cable, wherein the plurality of cable samples includes a first cable sample with a metallic sheath having a first initial thickness value and a second cable sample with a metallic sheath having a second initial thickness value, the first initial thickness value being greater than the second initial thickness value; and conducting specific testing tests on the plurality of cable samples according to the laying parameters, wherein the specific testing tests include at least one of the following: bending performance test, short-circuit current temperature test; wherein the specific testing test corresponding to the first cable sample is the bending performance test. In the following test phase corresponding to the bending performance test, the first initial thickness value is iteratively adjusted until a first target thickness value is obtained where the wrinkle index of the outer sheath is less than or equal to the wrinkle threshold at the target bending radius, wherein the target bending radius is determined according to the laying parameters; when the special test corresponding to the second cable sample is the short-circuit current temperature test, in the test phase corresponding to the short-circuit current temperature test, the second initial thickness value is iteratively adjusted until a second target thickness value is obtained where the temperature of the outer sheath is less than the temperature threshold under a predetermined test environment, wherein the predetermined test environment is determined according to the laying parameters; based on the first target thickness value and the second target thickness value, the range of metal sheath thickness values ​​corresponding to the target cable is determined.

[0007] Optionally, iteratively adjusting the first initial thickness value until a first target thickness value is obtained where the wrinkle index of the outer sheath is less than or equal to a wrinkle threshold at the target bending radius includes: controlling the first cable sample to perform a bending and straightening operation at the target bending radius; determining the initial wrinkle index of the outer sheath of the first cable sample after performing the bending and straightening operation; and, if the initial wrinkle index exceeds the wrinkle threshold, iteratively adjusting the first initial thickness value by gradually reducing the thickness value according to the first step length until a first target thickness value with a corresponding wrinkle index less than or equal to the wrinkle threshold is obtained.

[0008] Optionally, the second initial thickness value is iteratively adjusted until a second target thickness value is obtained where the temperature of the outer sheath is less than a temperature threshold under a predetermined test environment. This includes: when the target cable also includes a conductor and an insulation layer, controlling the application of a conductor current to the conductor of the second cable sample until the conductor current value reaches the rated current carrying capacity of the second cable sample and the corresponding insulation layer temperature no longer increases, and then removing the conductor current; controlling the application of a predetermined short-circuit current to the metal sheath of the second cable sample; determining the initial outer sheath temperature under the applied short-circuit current; determining whether the initial outer sheath temperature is greater than or equal to the temperature threshold; and when the initial outer sheath temperature is greater than or equal to the temperature threshold, iteratively adjusting the second initial thickness value by gradually increasing the thickness value according to a second step size until a second target thickness value is obtained where the corresponding outer sheath temperature is less than the temperature threshold.

[0009] Optionally, before applying a predetermined short-circuit current to the metal sheath of the second cable sample, the method further includes: determining the predetermined short-circuit current based on the reference capacity, the reference voltage, the short-circuit capacity at the fault point of the power system where the target cable is located, the per-unit reactance and per-unit resistance between the target cable and the upstream transformer, and the per-unit total impedance of the power system, provided that the laying parameters include the reference capacity, the reference voltage, the short-circuit capacity, the per-unit reactance, the per-unit resistance, and the per-unit total impedance of the power system.

[0010] Optionally, before conducting specific testing on the multiple cable samples according to the laying parameters, the method further includes: determining and setting the predetermined test environment based on the maximum ambient temperature and minimum wind speed in the tunnel when the laying parameters include the maximum ambient temperature and minimum wind speed in the tunnel; and determining the target bending radius based on the diameter of the shaft, the height of the shaft, the height of the cable tunnel, and the nominal outer diameter of the cable when the laying parameters include the diameter of the shaft, the height of the shaft, and the nominal outer diameter of the cable.

[0011] Optionally, after determining the range of metal sheath thickness values ​​corresponding to the target cable based on the first target thickness value and the second target thickness value, the method further includes: obtaining environmental parameters of the tunnel to be laid corresponding to the target cable, wherein the environmental parameters include temperature parameters and humidity parameters; and adjusting the range of metal sheath thickness values ​​based on the environmental parameters to obtain an updated range of metal sheath thickness values.

[0012] Optionally, after determining the range of metal sheath thickness values ​​corresponding to the target cable based on the first target thickness value and the second target thickness value, the method further includes: determining a target thickness value, wherein the target thickness value is located within the range of metal sheath thickness values; and setting the target cable to be designed based on the target thickness value to obtain the target designed cable.

[0013] According to one aspect of the present invention, a device for determining the range of metallic sheath thickness values ​​for a cable is provided, comprising: an acquisition module for acquiring a target cable to be designed and its laying parameters, wherein the target cable includes a metallic sheath and an outer sheath; a manufacturing module for manufacturing multiple cable samples based on the target cable, wherein the multiple cable samples include a first cable sample with a metallic sheath having a first initial thickness value and a second cable sample with a metallic sheath having a second initial thickness value, the first initial thickness value being greater than the second initial thickness value; a first testing module for performing specific testing tests on the multiple cable samples respectively based on the laying parameters, wherein the specific testing tests include at least one of the following: bending performance test, short-circuit current temperature test; and a second testing module for performing specific testing tests corresponding to the first cable sample, wherein the bending performance test is the same as the first cable sample. In the case of the bending performance test, during the test phase corresponding to the bending performance test, the first initial thickness value is iteratively adjusted until a first target thickness value is obtained where the wrinkle index of the outer sheath is less than or equal to the wrinkle threshold at the target bending radius, wherein the target bending radius is determined according to the laying parameters; the third test module is used to iteratively adjust the second initial thickness value during the test phase corresponding to the short-circuit current temperature test when the special test corresponding to the second cable sample is the short-circuit current temperature test, until a second target thickness value is obtained where the temperature of the outer sheath is less than the temperature threshold under a predetermined test environment, wherein the predetermined test environment is determined according to the laying parameters; the determination module is used to determine the range of metal sheath thickness values ​​corresponding to the target cable based on the first target thickness value and the second target thickness value.

[0014] According to one aspect of the present invention, an electronic device is provided, comprising: a processor; and a memory for storing processor-executable instructions; wherein the processor is configured to execute the instructions to implement the method for determining the range of metal sheath thickness values ​​of a cable as described in any of the preceding claims.

[0015] According to one aspect of the present invention, a computer-readable storage medium is provided, wherein when the instructions in the computer-readable storage medium are executed by a processor of an electronic device, the electronic device is enabled to perform the method for determining the range of metal sheath thickness values ​​of a cable as described in any of the preceding claims.

[0016] In this embodiment of the invention, a target cable to be designed and laying parameters are obtained, wherein the target cable includes a metal sheath and an outer sheath; based on the target cable, multiple cable samples are manufactured, wherein the multiple cable samples include a first cable sample with a metal sheath of a first initial thickness value and a second cable sample with a metal sheath of a second initial thickness value, the first initial thickness value being greater than the second initial thickness value; based on the laying parameters, specific testing tests are performed on the multiple cable samples, wherein the specific testing tests include at least one of the following: bending performance test, short-circuit current temperature test; when the specific testing test corresponding to the first cable sample is a bending performance test, the bending performance test corresponding to... During the testing phase, the first initial thickness value is iteratively adjusted until a first target thickness value is obtained where the wrinkle index of the outer sheath is less than or equal to the wrinkle threshold at the target bending radius. The target bending radius is determined based on the laying parameters. When the specific testing test corresponding to the second cable sample is a short-circuit current temperature test, the second initial thickness value is iteratively adjusted during the testing phase corresponding to the short-circuit current temperature test until a second target thickness value is obtained where the temperature of the outer sheath is less than the temperature threshold under a predetermined testing environment. The predetermined testing environment is determined based on the laying parameters. The range of metal sheath thickness values ​​corresponding to the target cable is determined based on the first target thickness value and the second target thickness value. A thickness range determination method based on laying parameters and specific tests was adopted. Cable samples with different initial thicknesses were prepared and subjected to bending performance tests and short-circuit current-temperature tests. During the tests, the initial thickness was iteratively adjusted according to the test conditions determined by the laying parameters to obtain two target thickness values ​​that meet the bending performance requirements and the short-circuit thermal stability requirements, respectively. Based on this, the range of metal sheath thickness values ​​was determined. This method achieves the goal of dynamically determining the range of metal sheath thickness that balances mechanical safety and electrical thermal stability for specific cables. As a result, the technical effect of improving the pertinence, reliability and adaptability of cable sheath design is achieved, thereby solving the technical problem in related technologies that it is difficult to design cable metal sheath thickness that can balance safety and durability. Attached Figure Description

[0017] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings:

[0018] Figure 1 This is a flowchart of a method for determining the range of metal sheath thickness values ​​for cables according to an embodiment of the present invention;

[0019] Figure 2 A method flowchart is provided for an optional embodiment of the present invention;

[0020] Figure 3A schematic diagram of the structure of a smooth aluminum-sheathed cable provided for an optional embodiment of the present invention;

[0021] Figure 4 A schematic diagram illustrating the calculation of the bending radius for an optional embodiment of the present invention;

[0022] Figure 5 A bending test prototype diagram provided for an optional embodiment of the present invention;

[0023] Figure 6 A schematic diagram of the temperature distribution of each layer of a cable under short-circuit conditions, provided as an optional embodiment of the present invention;

[0024] Figure 7 This is a structural block diagram of a device for determining the range of metal sheath thickness values ​​for cables according to an embodiment of the present invention. Detailed Implementation

[0025] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0026] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "including" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0027] Example 1

[0028] According to an embodiment of the present invention, an embodiment of a method for determining the range of metal sheath thickness values ​​of a cable is provided. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that shown here.

[0029] Figure 1This is a flowchart of a method for determining the range of metallic sheath thickness values ​​for cables according to an embodiment of the present invention, as shown below. Figure 1 As shown, the method includes the following steps:

[0030] Step S102: Obtain the target cable to be designed and its laying parameters, wherein the target cable includes a metal sheath and an outer sheath;

[0031] In step S102 of this application, the target cable to be designed is obtained, and the range of metal sheath thickness values ​​needs to be determined. It is clarified that the core components of the cable include a metal sheath and an outer sheath. At the same time, various key parameters related to cable laying are collected, and the basic structure and application scenario boundary conditions of the design object are defined.

[0032] This involves the target cable, which is the cable object to be analyzed or designed. The target cable can be a high-voltage smooth aluminum-sheathed cable, whose structure can include multiple components such as conductor, insulation layer, buffer layer, metal sheath, and outer sheath. It is the direct object for optimizing the thickness of the metal sheath.

[0033] This involves laying parameters, which are environmental, geometric, and system-related parameters during the laying of the target cable. These parameters may include the diameter of the laying shaft, the height of the shaft, the height of the cable tunnel, the highest ambient temperature in the tunnel, the lowest wind speed in the tunnel, as well as the reference capacity and reference voltage of the power system where the target cable is located. These parameters are the core basis for setting the conditions for subsequent special testing and inspection.

[0034] This involves the metal sheath, which is a key structural layer of the target cable. The metal sheath can be made of metal materials such as aluminum, copper or steel. In smooth aluminum sheathed cables, it is called smooth aluminum sheath. Its functions can include bearing the short-circuit current loop, providing mechanical protection, and inhibiting the ablation of the buffer layer. The thickness of the metal sheath directly affects the bending performance and short-circuit current withstand capability of the cable.

[0035] This involves the outer sheath, which is the outer protective structure of the target cable, wrapped around the metal sheath, and used to isolate the external environment from the corrosion of the cable's internal structure. Its wrinkle state and temperature change are key indicators for evaluating whether the thickness of the metal sheath is reasonable.

[0036] This step clarifies the structural characteristics and laying environment parameters of the target cable, ensuring that subsequent cable sample preparation and specialized testing are targeted and accurate. It avoids test deviations caused by unclear cable structure or laying conditions, thus providing reliable input for determining the range of metal sheath thickness values. This ensures that the design optimization process is based on actual application scenarios and improves the adaptability and reliability of sheath thickness design.

[0037] Step S104: Based on the target cable, multiple cable samples are made, including a first cable sample with a metal sheath of a first initial thickness value and a second cable sample with a metal sheath of a second initial thickness value, wherein the first initial thickness value is greater than the second initial thickness value.

[0038] In step S104 of this application, multiple cable samples with different metal sheath thicknesses are made according to the structure and parameters of the target cable, including a first cable sample (with a thicker metal sheath) and a second cable sample (with a thinner metal sheath). This provides test objects for subsequent special testing and ensures that the test covers different thickness conditions, thereby systematically evaluating the impact of metal sheath thickness on cable performance.

[0039] This includes cable samples, which are test samples made based on the target cable. The thickness of the metal sheath varies, but other structural parameters remain unchanged. These samples are used to conduct bending performance tests and short-circuit current temperature rise tests to evaluate the performance under different thicknesses.

[0040] This involves a first cable sample, which is a cable sample with a first initial thickness value for the metal sheath. The first initial thickness value is usually set to a relatively thick value for use in bending performance tests to evaluate the bending performance of the cable under higher thickness conditions.

[0041] This involves a second cable sample, which is a cable sample with a metal sheath having a second initial thickness value. The second initial thickness value is usually set to a relatively thin value for short-circuit current temperature rise testing to evaluate the thermal performance of the cable under lower thickness conditions.

[0042] This involves a first initial thickness value, which is the initial thickness setting of the metal sheath in the bending performance test. It is used for the initial bending performance test, and the thickness is gradually reduced through iterative adjustment to find the maximum thickness that prevents the outer sheath from wrinkling.

[0043] This involves a second initial thickness value, which is the initial thickness setting of the metal sheath in the short-circuit current temperature rise test. It is used for the initial short-circuit current temperature rise test, and the thickness is gradually increased through iterative adjustment to find the minimum thickness that makes the cable temperature rise meet the requirements.

[0044] This step involves creating cable samples with different metal sheath thicknesses, providing specific test objects for subsequent bending performance and short-circuit current temperature rise tests. This allows for iterative adjustments to find the maximum thickness (first target thickness value) that meets bending performance requirements and the minimum thickness (second target thickness value) that meets short-circuit current temperature rise requirements, thereby determining a reasonable thickness range for the metal sheath. This solves the problems of fixed sheath thickness, lack of specificity and adaptability, and ensures that cable design balances mechanical strength and thermal stability.

[0045] Step S106: Based on the laying parameters, conduct special tests on multiple cable samples, including at least one of the following: bending performance test, short-circuit current temperature test;

[0046] In step S106 of this application, multiple cable samples are subjected to specialized testing based on laying parameters, including bending performance test and short-circuit current temperature test. By simulating the mechanical and thermal conditions under real laying environment, the performance of the cable samples is systematically evaluated, providing test data support for subsequent adjustment of the metal sheath thickness.

[0047] This includes specialized testing, which are specific tests for cable performance, including bending performance tests and short-circuit current temperature tests. These tests are based on laying parameter settings and are used to evaluate the impact of cable metal sheath thickness on mechanical and thermal properties.

[0048] This includes a bending performance test, which is a mechanical test to evaluate whether the outer sheath of the cable wrinkles under bending conditions. The test involves bending the cable sample at least one full turn at the target bending radius and then straightening it, and repeating the cycle multiple times to detect the wrinkling of the outer sheath. The target bending radius is calculated and determined based on the laying parameters (shaft diameter, height, and tunnel height).

[0049] This includes a short-circuit current temperature test, which is a thermal test to evaluate the temperature rise of a cable under short-circuit current conditions. The test may include removing the current after the cable conductor reaches its rated current carrying capacity, immediately applying a predetermined short-circuit current to the metal sheath, and testing whether the temperature rise of the outer sheath meets the requirements. The test environment conditions are set according to the laying parameters.

[0050] This step involves conducting specialized tests on multiple cable samples based on laying parameters, including bending performance tests and short-circuit current temperature rise tests. This simulates the actual laying and operating environment of the cable, systematically evaluating the impact of the metallic sheath thickness on the cable's mechanical and thermal properties. This ensures the accuracy and practicality of the test results, providing a reliable basis for subsequent thickness adjustments. The tests simultaneously meet the cable's safety and durability requirements, preventing bending performance degradation due to excessive sheath thickness or excessive temperature rise due to insufficient sheath thickness, thus improving the overall performance and economy of the cable.

[0051] Step S108: If the specific test corresponding to the first cable sample is a bending performance test, in the test stage corresponding to the bending performance test, the first initial thickness value is iteratively adjusted until a first target thickness value is obtained in which the wrinkle index of the outer sheath is less than or equal to the wrinkle threshold under the target bending radius, wherein the target bending radius is determined according to the laying parameters.

[0052] In step S108 provided in this application, during the bending performance test stage, the first initial thickness value of the metal sheath of the first cable sample is iteratively adjusted. Through repeated tests, the thickness of the metal sheath that can make the wrinkle index of the cable outer sheath meet the requirements under the target bending radius calculated based on the laying parameters is found. This thickness is the first target thickness value.

[0053] This involves iterative adjustment, which refers to modifying the initial thickness value multiple times and step by step based on the test results during the bending performance test. When the outer sheath of the cable wrinkles, the thickness of the metal sheath is gradually reduced and the test is repeated until the outer sheath no longer produces wrinkles exceeding the limit.

[0054] This involves the target bending radius, which is the bending radius applied to the cable sample during the bending performance test. This radius is calculated and determined based on the laying parameters and is used to simulate the bending conditions of the cable during the actual laying process.

[0055] This includes the wrinkle index of the outer sheath, which is an index that quantitatively evaluates the degree of wrinkling on the surface of the outer sheath of the cable after a bending test. It is characterized by detecting the wrinkling condition on the surface of the cable after the test.

[0056] This includes a wrinkle threshold, which is a standard limit for judging whether the wrinkles of the outer sheath are qualified. When the wrinkles exceed this limit, they are considered not to meet the bending performance requirements.

[0057] This involves a first target thickness value, which is the metal sheath thickness value finally determined through iterative adjustments of bending performance tests. This thickness value is the thickness that ensures the outer sheath wrinkle index does not exceed the limit under the target bending radius, reflecting the upper limit of the sheath thickness for the cable to meet mechanical performance requirements.

[0058] This step, through iterative adjustments to the initial thickness value based on bending performance test results, accurately determines the maximum permissible thickness of the metallic sheath that prevents harmful wrinkling of the cable's outer sheath under real-world laying conditions. This ensures sufficient mechanical flexibility and structural stability during cable laying, avoiding problems such as wrinkling and damage to the outer sheath during bending due to excessive sheath thickness. Simultaneously, the upper limit of thickness determined through testing provides crucial data for subsequently defining a reasonable thickness range, achieving a balance between mechanical and thermal properties.

[0059] Step S110: When the special test corresponding to the second cable sample is the short-circuit current temperature test, the second initial thickness value is iteratively adjusted in the test stage corresponding to the short-circuit current temperature test until the second target thickness value is obtained in the predetermined test environment, where the temperature of the outer sheath is less than the temperature threshold. The predetermined test environment is determined based on the laying parameters.

[0060] In step S110 provided in this application, during the short-circuit current temperature test stage, the second initial thickness value of the metal sheath of the second cable sample is iteratively adjusted. Through repeated tests, the metal sheath thickness that can make the cable outer sheath temperature meet the requirements under the predetermined test environment set according to the laying parameters is found. This thickness is the second target thickness value.

[0061] This involves a predetermined test environment, which refers to the environmental conditions set in the short-circuit current temperature test. These conditions may include ambient temperature and ambient wind speed. These conditions are determined based on the highest ambient temperature and lowest wind speed in the tunnel in the laying parameters, simulating the most unfavorable heat dissipation conditions.

[0062] This includes the temperature of the outer sheath, which is the surface temperature of the cable's outer sheath measured during a short-circuit current temperature test. It is a key indicator for evaluating the thermal stability of the cable under short-circuit conditions.

[0063] This involves a temperature threshold, which is a standard limit for judging whether the temperature of the outer sheath is qualified. When the temperature of the outer sheath exceeds this limit, it is considered that the short-circuit current temperature rise requirement is not met.

[0064] This involves a second target thickness value, which is the metal sheath thickness value finally determined through iterative adjustments of short-circuit current temperature test. This thickness value is the thickness that can ensure the outer sheath temperature does not exceed the limit under the predetermined test environment, reflecting the lower limit of the sheath thickness for the cable to meet the thermal performance requirements.

[0065] This step, through iterative adjustments to the second initial thickness value based on the short-circuit current temperature test results, accurately determines the minimum necessary thickness of the metallic sheath for ensuring the cable's outer sheath temperature does not exceed limits under the most unfavorable heat dissipation conditions. This ensures the cable possesses sufficient thermal stability and current carrying capacity under short-circuit conditions, avoiding the risk of increased resistance and excessive heat generation due to an excessively thin sheath, which could lead to performance degradation of the outer sheath and hot melt adhesive. The lower limit of thickness determined through testing provides a crucial basis for ultimately establishing a reasonable thickness range, achieving synergistic optimization of thermal and mechanical properties.

[0066] Step S112: Determine the range of metal sheath thickness values ​​corresponding to the target cable based on the first target thickness value and the second target thickness value.

[0067] In step S112 of this application, a first target thickness value determined based on a bending performance test and a second target thickness value determined based on a short-circuit current temperature test are comprehensively analyzed to determine a reasonable thickness range for the target cable's metallic sheath.

[0068] This involves the range of metal sheath thickness values, which is a thickness range jointly defined by the first target thickness value and the second target thickness value. Any thickness value within this range can simultaneously meet the cable's bending performance requirements and short-circuit current temperature rise requirements.

[0069] This step, by comprehensively considering the upper limit of thickness determined by mechanical tests and the lower limit of thickness determined by thermal tests, establishes a range of metallic sheath thickness values ​​that simultaneously ensures the mechanical and electrical safety of the cable. This allows for dynamic optimization of cable design based on its specific laying environment and operating parameters. The determined thickness range provides clear guidance for the final design and manufacturing of the cable, ensuring its comprehensive performance and long-term operational reliability under complex operating conditions, and achieving an optimal balance between safety and economy.

[0070] Through steps S102-S112 above, the target cable to be designed and its laying parameters are obtained. The target cable includes a metal sheath and an outer sheath. Based on the target cable, multiple cable samples are fabricated. These samples include a first cable sample with a metal sheath of a first initial thickness and a second cable sample with a metal sheath of a second initial thickness, where the first initial thickness is greater than the second initial thickness. Based on the laying parameters, specific testing tests are conducted on each of the multiple cable samples. These specific testing tests include at least one of the following: bending performance test and short-circuit current-temperature test. If the specific testing test corresponding to the first cable sample is a bending performance test, then the bending performance test... In the corresponding test phase, the first initial thickness value is iteratively adjusted until a first target thickness value is obtained where the wrinkle index of the outer sheath is less than or equal to the wrinkle threshold at the target bending radius, wherein the target bending radius is determined based on the laying parameters; in the case where the special test corresponding to the second cable sample is the short-circuit current temperature test, in the test phase corresponding to the short-circuit current temperature test, the second initial thickness value is iteratively adjusted until a second target thickness value is obtained where the temperature of the outer sheath is less than the temperature threshold under the predetermined test environment, wherein the predetermined test environment is determined based on the laying parameters; the range of metal sheath thickness values ​​corresponding to the target cable is determined based on the first target thickness value and the second target thickness value. A thickness range determination method based on laying parameters and specific tests was adopted. Cable samples with different initial thicknesses were prepared and subjected to bending performance tests and short-circuit current-temperature tests. During the tests, the initial thickness was iteratively adjusted according to the test conditions determined by the laying parameters to obtain two target thickness values ​​that meet the bending performance requirements and the short-circuit thermal stability requirements, respectively. Based on this, the range of metal sheath thickness values ​​was determined. This method achieves the goal of dynamically determining the range of metal sheath thickness that balances mechanical safety and electrical thermal stability for specific cables. As a result, the technical effect of improving the pertinence, reliability and adaptability of cable sheath design is achieved, thereby solving the technical problem in related technologies that it is difficult to design cable metal sheath thickness that can balance safety and durability.

[0071] As an optional embodiment, the first initial thickness value is iteratively adjusted until a first target thickness value is obtained where the wrinkle index of the outer sheath is less than or equal to the wrinkle threshold at the target bending radius. This includes: controlling the first cable sample to perform a bending and straightening operation at the target bending radius; determining the initial wrinkle index of the outer sheath of the first cable sample after performing the bending and straightening operation; and if the initial wrinkle index exceeds the wrinkle threshold, iteratively adjusting the first initial thickness value by gradually reducing the thickness value according to the first step length until a first target thickness value with a corresponding wrinkle index less than or equal to the wrinkle threshold is obtained.

[0072] In this embodiment, a process is described in which a first initial thickness value is iteratively adjusted to obtain a first target thickness value that meets the bending performance requirements.

[0073] This includes the initial wrinkle index, which is a quantitative measurement of the degree of wrinkling on the surface of the outer sheath after a bending and straightening operation, used to determine whether the cable meets the bending performance requirements.

[0074] This involves the first step length, which is a preset step size value for reducing the thickness of the metal protective layer each time during the iterative adjustment process. This is used to gradually reduce the thickness to find the required thickness, ensuring that the adjustment process is controllable and precise.

[0075] In this step, the first cable sample is first controlled to perform a bending and straightening operation at the target bending radius to simulate real laying conditions; then the initial wrinkle index of the outer sheath is measured after the operation; if the initial wrinkle index exceeds the wrinkle threshold, the thickness of the metal sheath is gradually reduced according to the first step length, and the bending and straightening operation and wrinkle index measurement are repeated. This iterative process is repeated until the wrinkle index is less than or equal to the wrinkle threshold, and the corresponding thickness is the first target thickness value.

[0076] This method allows for the precise determination of the upper limit of the metallic sheath thickness through systematic iterative adjustments, ensuring that the outer sheath does not develop harmful wrinkles under bending conditions. This avoids deterioration in bending performance due to excessive sheath thickness, such as wrinkling or damage to the outer sheath, thereby improving the cable's mechanical reliability and laying safety. Iterative adjustments based on experimental results ensure the accuracy and objectivity of the thickness value, avoiding design deviations caused by relying on subjective experience, making the sheath thickness design more scientific and adaptable to actual laying conditions. Simultaneously, by gradually adjusting and optimizing the thickness design, material usage is minimized while meeting mechanical performance requirements.

[0077] As an optional embodiment, the second initial thickness value is iteratively adjusted until a second target thickness value is obtained where the temperature of the outer sheath is less than a temperature threshold under a predetermined test environment. This includes: when the target cable also includes a conductor and an insulation layer, controlling the application of a conductor current to the conductor of the second cable sample until the conductor current value reaches the rated current carrying capacity of the second cable sample and the corresponding insulation layer temperature no longer increases, and then removing the conductor current; controlling the application of a predetermined short-circuit current to the metal sheath of the second cable sample; determining the initial outer sheath temperature under the applied short-circuit current; determining whether the initial outer sheath temperature is greater than or equal to a temperature threshold; and when the initial outer sheath temperature is greater than or equal to the temperature threshold, iteratively adjusting the second initial thickness value by gradually increasing the thickness value according to a second step size until a second target thickness value corresponding to an outer sheath temperature less than a temperature threshold is obtained.

[0078] In this embodiment, the process of obtaining a second target thickness value that meets the short-circuit current temperature rise requirement by iteratively adjusting the second initial thickness value is described.

[0079] This involves conductors, which are the core components of cables that transmit electrical energy. In short-circuit current and temperature tests, current must be applied in advance to bring the conductor to its operating temperature to simulate the actual operating conditions of the cable.

[0080] This includes the rated current carrying capacity, which is the maximum current value that the cable is designed to carry for a long period of time. It is an important parameter for the safe operation of the cable.

[0081] This involves a second step size, which is a preset step size value for each increase in the thickness of the metal protective layer during the iterative adjustment process, used to gradually increase the thickness to find the thickness that meets the requirements.

[0082] This involves a predetermined short-circuit current, which is a short-circuit current value calculated based on power system parameters. It is used to simulate the current surge that the metal sheath of the cable needs to withstand under short-circuit fault conditions.

[0083] In this step, a conductor current is first applied to the conductor of the second cable sample until the current reaches the rated current carrying capacity and the insulation temperature stabilizes, simulating the normal operating state of the cable. Then, the conductor current is removed, and a predetermined short-circuit current is immediately applied to the metal sheath. The initial temperature of the outer sheath is measured at this time. If the initial temperature exceeds the temperature threshold, the thickness of the metal sheath is gradually increased according to the second step size, and the entire test is repeated. This iterative process is repeated until the temperature of the outer sheath is less than the temperature threshold. The corresponding thickness at this time is the second target thickness value.

[0084] This method enables precise optimization of the metal sheath thickness. Through iterative adjustments and real-time monitoring, the thickness value is ensured to be as small as possible while meeting short-circuit thermal performance requirements. This avoids increased resistance and excessive temperature rise due to an excessively thin sheath, thereby ensuring the safe operation of the cable under short-circuit faults and preventing the risk of thermal failure. Based on actual test data, this method simulates the most stringent operating environment, significantly improving the targeting and reliability of thickness design and overcoming the lack of adaptability that may result from traditional fixed thickness designs.

[0085] As an optional embodiment, before controlling the application of a predetermined short-circuit current to the metal sheath of the second cable sample, the method further includes: determining the predetermined short-circuit current based on the reference capacity, reference voltage, short-circuit capacity at the fault point of the power system where the target cable is located, the per-unit reactance and per-unit resistance between the target cable and the upstream transformer, and the per-unit total impedance of the power system, provided that the laying parameters include the reference capacity, reference voltage, short-circuit capacity, per-unit reactance, per-unit resistance, and per-unit total impedance of the power system.

[0086] In this embodiment, the process of calculating a predetermined short-circuit current based on power system parameters is described.

[0087] This involves the reference capacity, which is a unified power reference value used in power system calculations. It is used for per-unit value calculations and is a basic parameter for performing system equivalent calculations.

[0088] This involves a reference voltage, which is a unified voltage reference value used in power system analysis for per-unit value calculations. It is used to normalize voltage parameters and ensure the consistency of short-circuit current calculations.

[0089] This involves the per-unit reactance value, which is a relative value expressed as a reference value for the reactance parameters of the connection line between the target cable and the upstream transformer, reflecting the reactance characteristics of the line.

[0090] This includes the per-unit resistance value, which is a relative value expressed as a reference value for the resistance parameters of the connection line between the target cable and the upstream transformer, reflecting the resistance characteristics of the line.

[0091] In this step, the reference capacity, reference voltage, short-circuit capacity at the fault point, and per-unit reactance, per-unit resistance, and total impedance of the power system where the target cable is located are first obtained. Then, based on these parameters, the predetermined short-circuit current value is determined by power system short-circuit calculation. This current value reflects the level of short-circuit current that the cable may withstand in the actual system.

[0092] This method ensures the authenticity and accuracy of the test current. By calculating the predetermined short-circuit current based on actual power system parameters, the short-circuit current temperature rise test more closely reflects the actual operating environment of the cable, avoiding test deviations caused by improper current value settings, thereby improving the reliability of thickness optimization results. This method considers the comprehensive influence of system impedance and can accurately reflect the amplitude and thermal effect of the short-circuit current, providing a solid data foundation for the design of metal sheath thickness and enhancing the safety performance of the cable under short-circuit faults.

[0093] As an optional embodiment, before conducting specialized testing on multiple cable samples based on the laying parameters, the method further includes: if the laying parameters include the maximum ambient temperature and minimum wind speed in the tunnel, determining and setting a predetermined test environment based on the maximum ambient temperature and minimum wind speed in the tunnel; if the laying parameters include the shaft diameter, shaft height, cable tunnel height, and nominal outer diameter of the cable, determining the target bending radius based on the shaft diameter, shaft height, cable tunnel height, and nominal outer diameter of the cable.

[0094] This embodiment illustrates the process of setting specific testing conditions based on laying parameters.

[0095] This includes the highest ambient temperature in the tunnel, which is the highest ambient temperature that may occur in the cable-laying tunnel during operation. It serves as the basis for setting the ambient temperature for the short-circuit current temperature rise test, simulating the most stringent heat dissipation conditions to evaluate the thermal stability of the cable at high temperatures.

[0096] This includes the minimum wind speed in the tunnel, which is the lowest wind speed that may occur during the operation of the cable laying tunnel. It serves as the basis for setting the wind speed of the short-circuit current temperature rise test environment to simulate the most unfavorable cooling conditions and verify the heat dissipation capacity of the cable under low wind speed.

[0097] This involves the diameter of the shaft, which is the lateral dimension of the cable laying shaft. It affects the radius of curvature of the cable when it bends in the shaft and is one of the key geometric parameters for calculating the target bending radius.

[0098] This involves the shaft height, which is the vertical depth of the cable laying shaft. It affects the length of the cable's bending path from the ground to the tunnel and is an important geometric parameter for calculating the target bending radius.

[0099] This involves the cable tunnel height, which is the internal height dimension of the tunnel where the cable is laid. It limits the bending space of the cable within the tunnel and is a constraint parameter for calculating the target bending radius.

[0100] This involves the nominal outer diameter of the cable, which is the standard outer diameter in cable design. It is a basic parameter of cable geometry and directly affects the calculation result of the bending radius, used to determine the minimum allowable curvature of the cable when bending.

[0101] In this step, the highest ambient temperature and lowest wind speed in the tunnel are first extracted from the laying parameters and used as the set values ​​for the predetermined test environment for short-circuit current temperature rise test. At the same time, the shaft diameter, shaft height, cable tunnel height and nominal outer diameter of the cable are extracted from the laying parameters. Based on these geometric parameters, the target bending radius is determined by calculation formula for bending performance test.

[0102] This method ensures the authenticity and rigor of test conditions. By setting predetermined test environments and target bending radii based on actual laying parameters, the specialized testing more closely resembles the actual operating scenarios of cables, covering the most unfavorable environmental and mechanical conditions, thereby improving the reliability and representativeness of test results. This method avoids subjective setting of test conditions, enhances the pertinence and adaptability of thickness optimization design, provides an accurate data basis for determining the thickness range of cable metal sheaths, and effectively improves the safety and durability of cables under complex working conditions.

[0103] As an optional embodiment, after determining the range of metal sheath thickness values ​​corresponding to the target cable based on the first target thickness value and the second target thickness value, the method further includes: obtaining the environmental parameters of the tunnel to be laid corresponding to the target cable, wherein the environmental parameters include temperature parameters and humidity parameters; and adjusting the range of metal sheath thickness values ​​based on the environmental parameters to obtain an updated range of metal sheath thickness values.

[0104] This embodiment illustrates the process of fine-tuning the initial range of metal sheath thickness values ​​by combining specific parameters of the actual cable laying environment.

[0105] This involves environmental parameters, which are a set of parameters describing the environmental conditions of cable laying tunnels, including temperature and humidity parameters, etc. They are used to assess the degree of influence of the environment on cable performance and are input conditions for thickness range adjustment.

[0106] This involves temperature parameters, which are indicators of the temperature state inside the tunnel to be laid, including average temperature, temperature fluctuation range, or extreme temperature values. These parameters affect the heat dissipation efficiency, material aging rate, and insulation performance of the cable, and are key factors in adjusting the thickness range to optimize thermal stability.

[0107] This involves humidity parameters, which are indicators of the air humidity state inside the tunnel to be laid, such as relative humidity. High humidity environments may exacerbate the electrochemical corrosion of the metal sheath or affect the material properties of the outer sheath, making it an important consideration to adjust the thickness range to enhance environmental resistance.

[0108] In this step, the environmental parameters of the tunnel where the target cable is planned to be laid are first obtained, with a focus on collecting temperature and humidity parameters; then, the potential impact of these environmental parameters on cable performance is analyzed; finally, based on the analysis results, the initial range of metal sheath thickness values ​​determined by the experiment is adjusted to obtain an updated range of metal sheath thickness values ​​that better fits the actual engineering application.

[0109] This approach enhances the precision and engineering applicability of thickness range design. By incorporating specific environmental parameters from the tunnel installation, the thickness range of the metal sheath is no longer limited to laboratory standards but fully considers the unique characteristics of the actual operating environment of the cable. This significantly improves the long-term durability, safety, reliability, and economy of the cable under real-world conditions. This method overcomes the limitations of relying solely on specialized tests to determine the thickness range, achieving optimization from meeting standard performance requirements to adapting to specific environments.

[0110] As an optional embodiment, after determining the range of metal sheath thickness values ​​corresponding to the target cable based on the first target thickness value and the second target thickness value, the method further includes: determining the target thickness value, wherein the target thickness value is located within the range of metal sheath thickness values; setting the target cable to be designed based on the target thickness value to obtain the target designed cable.

[0111] This embodiment illustrates the process of determining the range of metal sheath thickness values, selecting a specific thickness value within the range, and applying it to cable design to ultimately form a cable product that can be used in actual engineering implementation.

[0112] This involves target design cables, which are cable products whose metal sheath thickness has been set according to the target thickness value, whose structural parameters have been determined, and which meet the engineering implementation conditions for actual power transmission.

[0113] In this step, firstly, a specific value is selected as the target thickness value from the determined range of metal sheath thickness values ​​based on the actual engineering requirements; then, this target thickness value is applied to the target cable to be designed, specifically in determining the production thickness specifications of the metal sheath and adjusting the corresponding cable structure; finally, all structural parameters are set to obtain the target design cable that can be directly used for manufacturing and laying.

[0114] This approach enables the transition from theoretical design to engineering practice. By transforming the thickness range obtained through experimental optimization into a definite production parameter, cable design has a clear manufacturing basis. This ensures that the final product (target design cable) meets the core requirements of bending performance and short-circuit thermal stability, while also conforming to the constraints of economy and manufacturability in actual engineering. This significantly enhances the practical value and industrial feasibility of the thickness determination method.

[0115] Based on the above embodiments and optional embodiments, an optional implementation method is provided, which is described in detail below.

[0116] As the problem of buffer layer erosion in corrugated aluminum high-voltage cables becomes increasingly prominent, this invention proposes a novel cable structure in an optional embodiment to fundamentally address the buffer layer erosion issue, thus providing a solution. This optional embodiment uses a smooth aluminum sheathed cable as the novel cable structure. Because the aluminum sheath lacks protrusions, it can make good contact with the buffer layer, thereby fundamentally suppressing the buffer layer erosion problem. The metallic sheath of the smooth aluminum sheathed cable serves two purposes: it acts as a loop for short-circuit current and it maintains the cable's bending performance. However, there are no clear regulations regarding the determination of the thickness of the metallic sheath in smooth aluminum sheathed cables. Therefore, this optional embodiment also proposes a method for determining the metallic sheath of high-voltage smooth aluminum sheathed cables, calculating a reference range for the thickness of the metallic sheath of smooth aluminum sheathed cables at selected voltage levels and cross-sections.

[0117] Specifically, an optional embodiment of the present invention provides a method for calculating the reference range of the metallic sheath thickness of smooth aluminum-sheathed cables for various voltage levels and cross-sections based on bending performance tests and short-circuit current temperature rise tests. On the one hand, when the metallic sheath thickness of a smooth aluminum-sheathed cable increases, the bending radius of the cable increases, making it prone to wrinkles or damage during installation. On the other hand, when the metallic sheath thickness decreases, the resistance per unit length of the metallic sheath increases, resulting in increased heat generation per unit length of the metallic sheath when the same short-circuit capacity is applied, thus affecting the performance of the outer sheath and hot melt adhesive. Figure 2 A method flowchart is provided for an optional embodiment of the present invention; Figure 3 A schematic diagram of the structure of a smooth aluminum-sheathed cable provided for an optional embodiment of the present invention; Figure 4 A schematic diagram illustrating the calculation of the bending radius for an optional embodiment of the present invention; Figure 5 A bending test prototype diagram provided for an optional embodiment of the present invention; Figure 6 A schematic diagram of the temperature distribution of each layer of the cable under short-circuit conditions is provided for an optional embodiment of the present invention, as shown below. Figures 2 to 6 As shown, the optional embodiments of the present invention will be described below:

[0118] The technical solution adopted in the optional embodiment of the present invention generally follows this process: First, the initial thickness of the metallic sheath of the smooth aluminum-sheathed cable to be tested is set. Then, a bending performance test is performed on the smooth aluminum-sheathed cable, and the thickness of the metallic sheath is modified according to the results. The test steps are repeated until a metallic sheath thickness that meets the bending performance requirements is obtained, which is taken as the maximum value of the metallic sheath thickness. Similarly, a short-circuit current temperature rise test is performed on the smooth aluminum-sheathed cable based on the initial thickness of the metallic sheath. The thickness of the metallic sheath is modified according to the results, and the test steps are repeated until a metallic sheath thickness that meets the short-circuit capacity requirements is calculated, which is taken as the minimum value of the metallic sheath thickness. Combining the above steps, a reference range for the thickness of the metallic sheath of the smooth aluminum-sheathed cable is obtained.

[0119] An optional embodiment of the present invention proposes the following method flow:

[0120] A. First, obtain information on the cable structure dimensions and laying conditions;

[0121] B. Calculate the bending radius of the smooth aluminum sheathed cable in the bending test based on the laying conditions;

[0122] C. Based on the configuration of the cable operating line and the laying conditions, determine the short-circuit current capacity, test ambient temperature, and test ambient wind speed that the smooth aluminum sheath cable needs to withstand.

[0123] D. Perform a bending test on the cable at the bending radius described in step B to evaluate the degree of surface wrinkling;

[0124] E. In the short-circuit current temperature rise test, set the conditions corresponding to step C, and analyze the temperature rise of the cable under short-circuit current conditions.

[0125] Step A specifically includes the following process:

[0126] A1. First, obtain the geometric and structural information of the part of the cable under study without the metal sheath, including the conductor radius, the radius of the composite layer consisting of conductor shield, XLPE insulation and insulation shield, the outer diameter of the buffer layer, the thickness of the hot melt adhesive layer, the outer diameter of the outer sheath, and set the thickness of the smooth aluminum sheath as an unknown parameter.

[0127] A2. Based on the structural characteristics of the cable, determine the mechanical property parameters required for finite element modeling. Required data include: Young's modulus, Poisson's ratio, and corresponding plastic parameters of the XLPE layer; Young's modulus, Poisson's ratio, and plastic parameters of the aluminum material used for the aluminum sheath; tensile modulus, shear modulus, shear strength, and fracture energy of the hot melt adhesive; and Young's modulus, Poisson's ratio, and plastic parameters of the outer sheath.

[0128] A3. Collect cable laying conditions, including: the diameter and height of the laying shaft, the height of the laying tunnel, the highest ambient temperature of the laying tunnel, and the lowest wind speed of the laying tunnel.

[0129] As can be seen, A1A2A3 above is the same as obtaining the target cable to be designed and the laying parameters.

[0130] Step B includes the following steps:

[0131] B1. Calculate the bending radius based on the cable's nominal outer diameter, the diameter and height of the laying shaft, and the height of the laying tunnel (similar to the above, where the laying parameters include the shaft diameter, shaft height, cable tunnel height, and cable nominal outer diameter, the target bending radius is determined based on the shaft diameter, shaft height, cable tunnel height, and cable nominal outer diameter).

[0132] Step C includes the following steps:

[0133] C1. First, collect the key electrical parameters of the smooth aluminum sheathed cable operating system, including the per-unit value of the system's equivalent impedance. The per-unit resistance value of the cable connecting to the upstream power transformer. With reactance per unit value System baseline capacity Short-circuit capacity at the fault point Rated cable voltage And the short-circuit current clearing time after the relay protection trips. .

[0134] C2. Based on the parameters obtained in C1, calculate the short-circuit current that the cable must withstand under short-circuit conditions, and determine the short-circuit capacity corresponding to the cable's metallic sheath accordingly. Its equivalent expression is: (As described above, when the laying parameters include the reference capacity, reference voltage, short-circuit capacity at the fault point of the power system where the target cable is located, the per-unit reactance and per-unit resistance between the target cable and the upstream transformer, and the per-unit total impedance of the power system, the predetermined short-circuit current is determined based on the reference capacity, the reference voltage, the short-circuit capacity, the per-unit reactance, the per-unit resistance, and the per-unit total impedance.)

[0135] Step D specifically includes the following steps:

[0136] D1. Bend the sample with a cylinder at least one full turn at the bending radius determined in step B, then straighten it. Next, rotate the sample 180 degrees along the cable axis and repeat the above process. This is one cycle, and it is performed three times (as described above, control the first cable sample to perform bending and straightening operations at the target bending radius).

[0137] D2. Inspect the wrinkling condition of the cable surface after the test (same as the initial wrinkling index of the outer sheath of the first cable sample after performing the bending and straightening operation as described above).

[0138] Step E includes the following steps:

[0139] E1. In the short-circuit cable temperature rise test environment, introduce the required environmental conditions and the short-circuit current and disconnection time determined in step C;

[0140] E2. Based on the temperature rise of the outer sheath during the test, the performance of the smooth aluminum sheathed cable under thermal effects is determined, thereby obtaining the lower limit value of its metal sheath thickness (similar to the above, in the case where the special test corresponding to the second cable sample is the short-circuit current temperature test, in the test stage corresponding to the short-circuit current temperature test, the second initial thickness value is iteratively adjusted until a second target thickness value is obtained where the temperature of the outer sheath is less than the temperature threshold under a predetermined test environment, wherein the predetermined test environment is determined based on the laying parameters).

[0141] Specifically, the method of the present invention includes the following steps:

[0142] Step 1: Obtain the relevant geometric information and laying conditions of the cable, and make a target cable sample based on this (similar to the above, multiple cable samples are made based on the target cable).

[0143] Step 1.1: Collect the structural characteristic parameters of the cable to be analyzed, including: conductor radius, outer radius of the conductor shield, XLPE insulation and insulation shield three-layer composite structure, outer radius of the buffer layer, hot melt adhesive thickness, outer radius of the outer sheath, and set the smooth aluminum sheath as a parameter to be determined, and give the initial value of the outer radius of the aluminum sheath.

[0144] Table 1 shows the parameters of the smooth aluminum sheathed cable used in this method example.

[0145] Table 1

[0146]

[0147] in, This indicates the outer radius of the metal sheath of a smooth aluminum cable.

[0148] Step 1.2: Collect cable laying conditions, including the diameter and height of the shaft, the height of the tunnel, the highest ambient temperature in the tunnel, and the lowest wind speed in the tunnel.

[0149] In an optional embodiment, Table 2 is a schematic table of laying condition parameters provided by an optional embodiment of the present invention. The cable laying condition parameters of the smooth aluminum sheathed cable used in the present invention are shown in Table 2.

[0150] Table 2

[0151]

[0152] Step 2: Determine the bending radius for the bending performance test based on the nominal outer diameter of the cable and the laying conditions.

[0153] Step 2.1: The nominal outer diameter of the cable is D, the diameter of the laying shaft is d, the height of the shaft is h, and the height of the laying tunnel is H. The bending radius R can be calculated using the following formula, in meters. The calculation method is as follows.

[0154]

[0155] Step 3: Calculate the short-circuit capacity of the cable based on the short-circuit conditions of the power system in which the smooth aluminum sheathed cable is located.

[0156] Step 3.1: Investigate and collect short-circuit related parameters of the system in which the cable is located, including the per-unit impedance of the system. The per-unit resistance value of the line between the cable and the upstream transformer. and per unit value of reactance Base capacity System short-circuit capacity Reference voltage and short-circuit current clearing time .

[0157] Step 3.2: Based on the parameters obtained in Step 3.1, calculate the current amplitude of the cable under short-circuit conditions. The short-circuit capacity used in the cable short-circuit current temperature rise test was determined to be... .

[0158]

[0159] Step 4: Determine the maximum value of the aluminum sheath thickness of the smooth aluminum-sheathed cable through a bending performance test (similar to the above, in the case where the specific test corresponding to the first cable sample is the bending performance test, in the test stage corresponding to the bending performance test, the first initial thickness value is iteratively adjusted until a first target thickness value is obtained where the wrinkle index of the outer sheath is less than or equal to the wrinkle threshold at the target bending radius, wherein the target bending radius is determined according to the laying parameters).

[0160] Step 4.1: In the bending performance test, the target cable sample is bent around the test cylinder at least one full turn at ambient temperature, then straightened. The sample should then be rotated 180 degrees along the cable axis. This process is repeated three times as one cycle.

[0161] Step 4.2: Inspect the surface wrinkles of the cable after the test. If the wrinkles exceed 1mm, gradually reduce the thickness of the metal sheath and repeat the test until the smooth aluminum sheath cable meets the bending performance requirements. The corresponding thickness is the maximum value of the aluminum sheath thickness.

[0162] Step 5: Determine the minimum thickness of the aluminum sheath of the smooth aluminum-sheathed cable through short-circuit current temperature rise test analysis (similar to the above, in the case where the special test corresponding to the second cable sample is the short-circuit current temperature test, in the test stage corresponding to the short-circuit current temperature test, the second initial thickness value is iteratively adjusted until a second target thickness value is obtained in which the temperature of the outer sheath is less than the temperature threshold under a predetermined test environment, wherein the predetermined test environment is determined based on the laying parameters).

[0163] Step 5.1: Set the environmental conditions and mechanism in the short-circuit current temperature rise test. Specifically, this includes: setting the ambient temperature to the highest ambient temperature in the cable laying tunnel, setting the ambient wind speed to the lowest wind speed in the cable laying tunnel, setting the aluminum sheath for short-circuit capacity excitation, and setting the insulation to the temperature at which the cable reaches its current-carrying capacity.

[0164] Step 5.2: Based on the maximum temperature that the outer sheath and hot melt adhesive can withstand, analyze the temperature distribution of the cable under the short-circuit capacity conditions obtained in the test.

[0165] The above optional implementation methods can achieve at least the following beneficial effects:

[0166] (1) Targeted calculation of the thickness of the metal sheath of smooth aluminum sheathed cable: By conducting mechanical tests and short-circuit capacity tests on smooth aluminum sheathed cables with different thicknesses of metal sheath, this invention can accurately determine the reference thickness range of the metal sheath of smooth aluminum sheath.

[0167] (2) Wide applicability of the method: By adjusting the thickness and material of each layer of the cable sample, this method can be used to analyze smooth aluminum sheathed cables with different voltage levels and cross sections. It has good universality and is suitable for the design optimization of various smooth aluminum sheathed cables.

[0168] It should be noted that, for the sake of simplicity, the foregoing method embodiments are all described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, because according to the present invention, some steps can be performed in other orders or simultaneously. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to the present invention.

[0169] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods according to the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) and includes several instructions to cause a terminal device (which may be a mobile phone, computer, server, or network device, etc.) to execute the methods of the various embodiments of the present invention.

[0170] Example 2

[0171] According to embodiments of the present invention, an apparatus is also provided for implementing the method for determining the range of metallic sheath thickness values ​​for the above-described cable. Figure 7 This is a structural block diagram of a cable metal sheath thickness range determination device according to an embodiment of the present invention, as shown below. Figure 7 As shown, the device includes: an acquisition module 702, a manufacturing module 704, a first test module 706, a second test module 708, a third test module 710, and a determination module 712. The device will be described in detail below.

[0172] An acquisition module 702 is used to acquire the target cable to be designed and its laying parameters, wherein the target cable includes a metal sheath and an outer sheath; a manufacturing module 704, connected to the acquisition module 702, is used to manufacture multiple cable samples based on the target cable, wherein the multiple cable samples include a first cable sample with a metal sheath of a first initial thickness value and a second cable sample with a metal sheath of a second initial thickness value, the first initial thickness value being greater than the second initial thickness value; a first testing module 706, connected to the manufacturing module 704, is used to perform specific testing tests on the multiple cable samples according to the laying parameters, wherein the specific testing tests include at least one of the following: bending performance test, short-circuit current temperature test; a second testing module 708, connected to the first testing module 706, is used to, when the specific testing test corresponding to the first cable sample is the bending performance test, In the test phase corresponding to the bending performance test, the first initial thickness value is iteratively adjusted until a first target thickness value is obtained where the wrinkle index of the outer sheath is less than or equal to the wrinkle threshold at the target bending radius, wherein the target bending radius is determined according to the laying parameters; the third test module 710, connected to the second test module 708, is used to iteratively adjust the second initial thickness value in the test phase corresponding to the short-circuit current temperature test when the special test corresponding to the second cable sample is the short-circuit current temperature test, until a second target thickness value is obtained where the temperature of the outer sheath is less than the temperature threshold under a predetermined test environment, wherein the predetermined test environment is determined according to the laying parameters; the determination module 712, connected to the third test module 710, is used to determine the range of metal sheath thickness values ​​corresponding to the target cable based on the first target thickness value and the second target thickness value.

[0173] It should be noted that the above-mentioned acquisition module 702, manufacturing module 704, first test module 706, second test module 708, third test module 710 and determination module 712 correspond to steps S102 to S112 in the method for determining the range of metal sheath thickness values ​​of cables. The multiple modules and the corresponding steps are the same in terms of implementation examples and application scenarios, but are not limited to the content disclosed in the above embodiment 1.

[0174] Example 3

[0175] According to another aspect of the present invention, an electronic device is also provided, comprising: a processor; and a memory for storing processor-executable instructions, wherein the processor is configured to execute the instructions to implement the method for determining the range of metal sheath thickness values ​​of a cable as described above.

[0176] Example 4

[0177] According to another aspect of the present invention, a computer-readable storage medium is also provided, which, when the instructions in the computer-readable storage medium are executed by a processor of an electronic device, enables the electronic device to perform the method for determining the range of metal sheath thickness values ​​of a cable as described above.

[0178] The sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0179] In the above embodiments of the present invention, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0180] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. The device embodiments described above are merely illustrative; for example, the division of units can be a logical functional division, and in actual implementation, there may be other division methods. For instance, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the displayed or discussed mutual coupling, direct coupling, or communication connection may be through some interfaces; the indirect coupling or communication connection between units or modules may be electrical or other forms.

[0181] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0182] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0183] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, read-only memory (ROM), random access memory (RAM), portable hard drives, magnetic disks, or optical disks.

[0184] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for determining the range of metallic sheath thickness values ​​for a cable, characterized in that, include: Obtain the target cable to be designed and its laying parameters, wherein the target cable includes a metal sheath and an outer sheath; Based on the target cable, multiple cable samples are manufactured, including a first cable sample with a metal sheath of a first initial thickness value and a second cable sample with a metal sheath of a second initial thickness value, wherein the first initial thickness value is greater than the second initial thickness value. Based on the laying parameters, specific testing tests are conducted on the plurality of cable samples, wherein the specific testing tests include at least one of the following: bending performance test, short-circuit current temperature test; When the specific test corresponding to the first cable sample is the bending performance test, the first initial thickness value is iteratively adjusted during the test phase corresponding to the bending performance test until a first target thickness value is obtained in which the wrinkle index of the outer sheath is less than or equal to the wrinkle threshold at the target bending radius, wherein the target bending radius is determined according to the laying parameters; When the specific test corresponding to the second cable sample is the short-circuit current temperature test, the second initial thickness value is iteratively adjusted during the test phase corresponding to the short-circuit current temperature test until a second target thickness value is obtained in which the temperature of the outer sheath is less than the temperature threshold under a predetermined test environment, wherein the predetermined test environment is determined based on the laying parameters; Based on the first target thickness value and the second target thickness value, the range of metal sheath thickness values ​​corresponding to the target cable is determined.

2. The method according to claim 1, characterized in that, The initial thickness value is iteratively adjusted until a first target thickness value is obtained where, at the target bending radius, the wrinkle index of the outer sheath is less than or equal to the wrinkle threshold, including: At the target bending radius, the first cable sample is controlled to perform a bending and straightening operation; Determine the initial wrinkle index of the outer sheath of the first cable sample after performing the bending and straightening operation; If the initial wrinkle index exceeds the wrinkle threshold, the thickness value is gradually reduced according to the first step length, and the first initial thickness value is iteratively adjusted until a first target thickness value with a corresponding wrinkle index less than or equal to the wrinkle threshold is obtained.

3. The method according to claim 1, characterized in that, The second initial thickness value is iteratively adjusted until a second target thickness value is obtained where the temperature of the outer sheath is less than a temperature threshold under a predetermined test environment, including: If the target cable also includes a conductor and an insulation layer, control the application of conductor current to the conductor of the second cable sample until the conductor current value reaches the rated current carrying capacity of the second cable sample and the corresponding insulation layer temperature no longer increases, then remove the conductor current; A predetermined short-circuit current is applied to the metal sheath of the second cable sample; Determine the initial outer sheath temperature under the applied short-circuit current; Determine whether the initial outer sheath temperature is greater than or equal to the temperature threshold; If the initial outer sheath temperature is greater than or equal to the temperature threshold, the thickness value is gradually increased according to the second step size, and the second initial thickness value is iteratively adjusted until a second target thickness value is obtained corresponding to an outer sheath temperature less than the temperature threshold.

4. The method according to claim 3, characterized in that, Before applying a predetermined short-circuit current to the metal sheath of the second cable sample, the method further includes: When the laying parameters include the reference capacity, reference voltage, short-circuit capacity at the fault point of the power system where the target cable is located, the per-unit reactance and per-unit resistance between the target cable and the upstream transformer, and the per-unit total impedance of the power system, the predetermined short-circuit current is determined based on the reference capacity, the reference voltage, the short-circuit capacity, the per-unit reactance, the per-unit resistance, and the per-unit total impedance.

5. The method according to claim 1, characterized in that, Before conducting specialized testing on the multiple cable samples according to the laying parameters, the process also includes: When the laying parameters include the maximum ambient temperature of the tunnel and the minimum wind speed of the tunnel, the predetermined test environment is determined and set according to the maximum ambient temperature of the tunnel and the minimum wind speed of the tunnel; When the laying parameters include shaft diameter, shaft height, cable tunnel height, and cable nominal outer diameter, the target bending radius is determined based on the shaft diameter, shaft height, cable tunnel height, and cable nominal outer diameter.

6. The method according to claim 1, characterized in that, After determining the range of metal sheath thickness values ​​corresponding to the target cable based on the first target thickness value and the second target thickness value, the method further includes: Obtain the environmental parameters of the tunnel to be laid corresponding to the target cable, wherein the environmental parameters include temperature parameters and humidity parameters; Based on the environmental parameters, the range of metal coating thickness values ​​is adjusted to obtain an updated range of metal coating thickness values.

7. The method according to any one of claims 1 to 6, characterized in that, After determining the range of metal sheath thickness values ​​corresponding to the target cable based on the first target thickness value and the second target thickness value, the method further includes: Determine a target thickness value, wherein the target thickness value is located within the range of the metal sheath thickness value; The target cable to be designed is set according to the target thickness value to obtain the target designed cable.

8. A device for determining the range of metallic sheath thickness values ​​for a cable, characterized in that, include: The acquisition module is used to acquire the target cable to be designed and its laying parameters, wherein the target cable includes a metal sheath and an outer sheath; The manufacturing module is used to manufacture multiple cable samples based on the target cable, wherein the multiple cable samples include a first cable sample with a metal sheath of a first initial thickness value and a second cable sample with a metal sheath of a second initial thickness value, wherein the first initial thickness value is greater than the second initial thickness value; The first test module is used to conduct special tests on the plurality of cable samples according to the laying parameters, wherein the special tests include at least one of the following: bending performance test, short circuit current temperature test; The second test module is used to iteratively adjust the first initial thickness value during the test phase corresponding to the bending performance test when the specific test corresponding to the first cable sample is the bending performance test, until a first target thickness value is obtained in which the wrinkle index of the outer sheath is less than or equal to the wrinkle threshold at the target bending radius, wherein the target bending radius is determined according to the laying parameters. The third test module is used to iteratively adjust the second initial thickness value during the test phase corresponding to the short-circuit current temperature test when the special test corresponding to the second cable sample is the short-circuit current temperature test, until a second target thickness value is obtained in which the temperature of the outer sheath is less than the temperature threshold under a predetermined test environment, wherein the predetermined test environment is determined according to the laying parameters; The determining module is used to determine the range of metal sheath thickness values ​​corresponding to the target cable based on the first target thickness value and the second target thickness value.

9. An electronic device, characterized in that, include: processor; Memory used to store the processor's executable instructions; The processor is configured to execute the instructions to implement the method for determining the range of metal sheath thickness values ​​for a cable as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, When the instructions in the computer-readable storage medium are executed by the processor of the electronic device, the electronic device is able to perform the method for determining the range of metal sheath thickness values ​​of the cable as described in any one of claims 1 to 7.

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