Cable current-carrying capacity calculation method and device, and storage medium

Abstract

The invention discloses a cable current-carrying capacity calculation method and device and a storage medium, and the method comprises the steps: constructing a steady-state thermal circuit model for a cable, the steady-state thermal circuit model structurally comprises a conductor, an insulating layer, a buffer layer, an aluminum sheath and an outer sheath, constructing an original thermal circuit control equation for each structure of the steady-state thermal circuit model, and constructing a dynamic characteristic curve representing linkage change between the thermal resistance value and the temperature value under each current for each structure of the steady-state thermal circuit model, correcting the original thermal circuit control equation according to the dynamic characteristic curve to obtain a target thermal circuit control equation, and solving the current-carrying capacity of the cable according to the target thermal circuit control equation. The heat conduction characteristics of the cable under different working conditions can be accurately described by constructing a steady-state thermal circuit model of the cable and carrying out detailed analysis on each structure of the cable. An original thermal circuit control equation is established for each structure, and a target thermal circuit control equation is obtained in combination with the dynamic characteristic curve, so that the current-carrying capacity of the cable can be calculated, and the accuracy of detecting the current-carrying capacity of the cable is improved.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of power systems, and in particular to a cable current carrying capacity calculation method, device and storage medium. Background Art

[0002] As one of the basic facilities for power transmission, cables are widely used in various industries, transportation, communications, civil construction, etc. The current carrying capacity of cables is one of the parameters to measure the performance of cables. Accurate calculation of the current carrying capacity of cables is one of the factors for the stable operation of power systems.

[0003] Traditional cable current-carrying capacity calculation methods usually rely on simplified thermal resistance models. These methods have low comprehensive consideration of the thermal conductivity characteristics of each layer of material inside the cable, the dynamic response under various currents, and changes in environmental factors, resulting in low accuracy in the calculation and detection of cable current-carrying capacity results. Summary of the invention

[0004] The invention provides a cable current carrying capacity calculation method, equipment and storage medium, which are used to improve the accuracy of detecting the cable current carrying capacity.

[0005] In a first aspect, an embodiment of the present invention provides a method for calculating the current carrying capacity of a cable, comprising:

[0006] A steady-state thermal circuit model is constructed for the cable; the structure of the steady-state thermal circuit model includes a conductor, an insulating layer, a buffer layer, an aluminum sheath and an outer sheath;

[0007] Constructing original heat circuit control equations for each structure of the steady-state heat circuit model;

[0008] Constructing a dynamic characteristic curve representing the linkage change between thermal resistance value and temperature value under each current for each structure of the steady-state thermal circuit model;

[0009] Correcting the original heat circuit control equation according to the dynamic characteristic curve to obtain a target heat circuit control equation;

[0010] The current carrying capacity of the cable is solved according to the target thermal circuit control equation.

[0011] In a second aspect, an embodiment of the present invention further provides a cable current carrying capacity calculation device, comprising:

[0012] A model building module is used to build a steady-state thermal circuit model for the cable; the structure of the steady-state thermal circuit model includes a conductor, an insulating layer, a buffer layer, an aluminum sheath and an outer sheath;

[0013] An original heat circuit control equation construction module, used to construct an original heat circuit control equation for each structure of the steady-state heat circuit model;

[0014] A dynamic characteristic curve construction module, used to construct a dynamic characteristic curve representing the linkage change between thermal resistance value and temperature value under each current for each structure of the steady-state thermal circuit model;

[0015] A target heat circuit control equation acquisition module is used to correct the original heat circuit control equation according to the dynamic characteristic curve to obtain a target heat circuit control equation;

[0016] The current carrying capacity calculation module is used to solve the current carrying capacity of the cable according to the target thermal circuit control equation.

[0017] In a third aspect, an embodiment of the present invention further provides a computer device, the computer device comprising:

[0018] one or more processors;

[0019] A storage device for storing one or more programs;

[0020] When the one or more programs are executed by the one or more processors, the one or more processors implement the cable current carrying capacity calculation method provided in the first aspect of the present invention.

[0021] In a fourth aspect, an embodiment of the present invention further provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the cable current-carrying capacity calculation method provided in the first aspect of the present invention.

[0022] In a fifth aspect, an embodiment of the present invention further provides a computer program product, the computer program product comprising a computer program, and when the computer program is executed by a processor, the cable current carrying capacity calculation method provided in the first aspect of the present invention is implemented.

[0023] In an embodiment of the present invention, a steady-state thermal circuit model is constructed for the cable, and the structure of the steady-state thermal circuit model includes a conductor, an insulating layer, a buffer layer, an aluminum sheath and an outer sheath. The original thermal circuit control equation is constructed for each structure of the steady-state thermal circuit model, and a dynamic characteristic curve representing the linkage change between the thermal resistance value and the temperature value under each current is constructed for each structure of the steady-state thermal circuit model. The original thermal circuit control equation is corrected according to the dynamic characteristic curve to obtain the target thermal circuit control equation, and the current carrying capacity of the cable is solved according to the target thermal circuit control equation. By constructing a steady-state thermal circuit model of the cable and performing a detailed analysis on each structure thereof, the thermal conduction characteristics of the cable under different working conditions can be accurately described. By establishing the original thermal circuit control equation for each structure and correcting the target thermal circuit control equation in combination with the dynamic characteristic curve, the temperature rise change of the cable under different currents can be more accurately simulated, thereby optimizing the thermal management of the cable. According to the corrected target thermal circuit control equation, the maximum current carrying capacity of the cable can be calculated to ensure that the cable operates within a safe temperature range, and improve the accuracy of detecting the current carrying capacity of the cable. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A flow chart of a cable current carrying capacity calculation method provided in Embodiment 1 of the present invention;

[0025] Figure 2 A schematic diagram of the structure of a steady-state thermal circuit model provided in Embodiment 1 of the present invention;

[0026] Figure 3 A structural block diagram of a cable current carrying capacity calculation device provided in Embodiment 2 of the present invention;

[0027] Figure 4 A schematic diagram of the structure of a computer device provided in Embodiment 3 of the present invention. DETAILED DESCRIPTION

[0028] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0029] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present invention described herein can cover sequential implementations other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0030] Embodiment 1

[0031] See also Figure 1 , shows a flow chart of a cable current carrying capacity calculation method provided by the first embodiment of the present invention, the method can be executed by a cable current carrying capacity calculation device, the cable current carrying capacity calculation device can be implemented in the form of hardware and / or software, and the cable current carrying capacity calculation device can be configured in a computer device. Figure 1 As shown, the method includes:

[0032] Step 101: construct a steady-state thermal circuit model for the cable.

[0033] Cables are usually composed of conductors (such as copper or aluminum wires), insulation materials, outer sheaths, etc. The conductors are responsible for conducting current, the insulation layer prevents current leakage and short circuits, and the outer sheath plays a protective role to ensure the durability and safety of the cable. Cables come in many types, such as low-voltage cables, high-voltage cables, and optical fiber cables, depending on their use and working environment.

[0034] In this embodiment, according to the multi-layer structure of the cable, the thermal behavior of each layer of the structure is characterized by thermal resistance, and a steady-state thermal circuit model is constructed based on the simplified theory of thermal circuit. The structure of the steady-state thermal circuit model includes a conductor, an insulation layer, a buffer layer, an aluminum sheath and an outer sheath. Steady state means that the cable temperature reaches a stable state and no longer changes.

[0035] Step 102: construct original thermal circuit control equations for each structure of the steady-state thermal circuit model.

[0036] In this embodiment, by constructing the original thermal circuit control equation, a mathematical description of heat conduction and temperature distribution is provided for each layer structure of the steady-state thermal circuit model, the thermal behavior of the cable under different working conditions is analyzed, and the relationship between the temperature change and thermal resistance characteristics of each layer of material (such as conductor, insulation layer, buffer layer, aluminum sheath and outer sheath) is understood, which provides a basis for subsequent dynamic correction and optimization.

[0037] For example, Figure 2 The steady-state thermal circuit model is shown. Figure 2 The steady-state thermal circuit model is divided from left to right into conductor, insulation layer (such as cross-linked polyethylene (XLPE) insulation), buffer layer, aluminum sheath and outer sheath, as well as the environment in which the steady-state thermal circuit model is located, θ 1 is the temperature of the conductor, θ 2 is the temperature of the insulation layer, θ 3 is the temperature of the aluminum sheath, θ 4 is the temperature of the outer sheath, θ 5 is the temperature value of the environment where the steady-state thermal circuit model is located, Q 1 is the conductor loss, Q 2 The loss value of the insulation layer close to the conductor, Q 3 is the loss value of the insulating layer close to the buffer layer, Q 4 is the loss value of the aluminum sheath, T 1 is the thermal resistance of the insulation layer, T 2 is the thermal resistance of the buffer layer, T 3 is the thermal resistance of the outer sheath, T 4 is the thermal resistance value of the environment in which the steady-state thermal circuit model is located.

[0038] In one embodiment of the present invention, step 102 may include the following steps:

[0039] Step 1021 : respectively set a first target layer and a second target layer in each layer structure of the steady-state thermal circuit model.

[0040] In this embodiment, each layer structure (such as conductor, insulation layer, buffer layer, etc.) in the steady-state thermal circuit model is a different thermal resistance layer. The first target layer and the second target layer are set in each layer structure, and the first target layer is located on the inner side of the second target layer. In order to analyze the temperature change and heat transfer process between the first target layer and the second target layer, by distinguishing different layers in the order of inside and outside, it is possible to clearly describe how the heat flow is transferred between these layers, and more accurately calculate the thermal resistance and temperature change of each layer. The first target layer and the second target layer can be two adjacent layers or two separated layers.

[0041] Step 1022: Calculate the difference between the temperature value of the first target layer and the temperature value of the second target layer to obtain a temperature difference.

[0042] In this embodiment, the temperature difference between the first target layer and the second target layer is calculated to analyze the driving force of the heat flow. The temperature difference reflects the driving force of heat transfer between the two layers. The calculation of the temperature difference helps to further deduce the law of heat conduction and how it affects the current carrying capacity of the cable.

[0043] Step 1023: Add the loss values ​​from the conductor to the second target layer to obtain the total loss.

[0044] In this embodiment, when the current passes through the steady-state thermal circuit model, energy loss (mainly dissipated in the form of heat) will be generated due to resistance, and the loss values ​​from the conductor to the second target layer are accumulated to obtain a total loss. This total loss is one of the important parameters of the heat conduction process.

[0045] Step 1024 , setting the temperature difference equal to the product of the total loss and the thermal resistance value of the second target layer to obtain the original thermal circuit control equation.

[0046] In this embodiment, the original thermal circuit control equation can be used to calculate the thermal resistance value and temperature change of each layer and the total loss, and finally obtain the original thermal circuit control equation describing the thermal behavior of the cable. The relationship between the temperature difference, thermal resistance value and total loss determines the transfer of heat flow. By constructing the original thermal circuit control equation, the heat transfer process of each layer structure of the cable can be quantified to ensure that the thermal performance of the cable can be accurately described by the mathematical model.

[0047] For example, for Figure 2 The steady-state thermal circuit model shown in the figure, the original thermal circuit control equation is expressed as:

[0048] θ 1 -θ 2 =(Q 1 +Q2 )T 1 ;

[0049] θ 2 -θ 3 =(Q 1 +Q 2 +Q 3 )T 2 ;

[0050] θ 3 -θ 4 =(Q 1 +Q 2 +Q 3 +Q 4 )T 3 ;

[0051] θ 4 -θ 5 =(Q 1 +Q 2 +Q 3 +Q 4 )T 4 ;

[0052] Among them, θ 1 is the temperature of the conductor, θ 2 is the temperature of the insulation layer, θ 3 is the temperature of the aluminum sheath, θ 4 is the temperature of the outer sheath, θ 5 is the temperature value of the environment where the steady-state thermal circuit model is located, Q 1 is the conductor loss, Q 2 The loss value of the insulation layer close to the conductor, Q 3 is the loss value of the insulating layer close to the buffer layer, Q 4 is the loss value of the aluminum sheath, T 1 is the thermal resistance of the insulation layer, T 2 is the thermal resistance of the buffer layer, T 3 is the thermal resistance of the outer sheath, T 4 is the thermal resistance value of the environment in which the steady-state thermal circuit model is located.

[0053] Step 103: construct a dynamic characteristic curve representing the linkage change between the thermal resistance value and the temperature value under each current for each structure of the steady-state thermal circuit model.

[0054] In this embodiment, under various currents, the temperature value of each structure of the steady-state thermal circuit model changes with the change of current, and the thermal resistance value in each structure changes with the temperature value in each structure. By linking the dynamic changes between the thermal resistance value and the temperature value, a dynamic characteristic curve between the thermal resistance value and the temperature value can be constructed.

[0055] In one embodiment of the present invention, step 103 may include the following steps:

[0056] Step 1031: Apply power with different current values ​​to the cable.

[0057] In this embodiment, by changing the current, the thermal response of the cable under different load conditions is simulated, and the temperature change of the cable under different working loads is observed, providing a data basis for subsequent thermal analysis. The change in current will cause the temperature of each structure inside the cable to change, thereby affecting its thermal resistance.

[0058] Step 1032: For each power supply, collect the thermal resistance and temperature value of each layer structure in the cable steady-state thermal circuit model.

[0059] In this embodiment, the temperature of each structure of the cable steady-state thermal circuit model will change under the action of current. By collecting the temperature values ​​and thermal resistance values ​​of different structures of the cable steady-state thermal circuit model in real time, the thermal conduction characteristics of different structures inside the cable steady-state thermal circuit model can be understood in detail, and the relationship between the temperature values ​​and thermal resistance values ​​of each structure of the cable steady-state thermal circuit model can be further analyzed.

[0060] Specifically, for each power supply, the temperature value of each layer structure in the steady-state thermal circuit model is collected; if the temperature value of the conductor reaches a preset temperature threshold, and the temperature value of each layer structure of the steady-state thermal circuit model reaches a steady state, the thermal resistance value of each layer structure in the steady-state thermal circuit model is calculated at the temperature value.

[0061] By applying various power sources to the cable, for example, the load current of the first power applied is 100A, and the power applied next time is 150A, the power current value is increased according to this gradient. If the applied load current makes the steady-state temperature of the conductor exceed 90 degrees Celsius, the current is stopped. In this process, when the temperature value of each layer structure of the steady-state thermal circuit model reaches a steady state, the temperature value of each layer structure in the steady-state thermal circuit model is collected.

[0062] Steady state means that when the temperature value no longer changes significantly, the heat transfer of the steady-state thermal circuit model can be considered to have stabilized, and the temperature value at this time can be used as a steady-state condition for further analysis.

[0063] When the temperature of the conductor reaches the set threshold (i.e. 90 degrees Celsius) and the temperature of each layer structure reaches a steady state, the steady-state thermal circuit model can calculate the thermal resistance based on these stable temperature values, which means that the heat transfer process has been completed or stabilized. The thermal resistance formula can be used to evaluate the thermal resistance performance of each layer structure, thereby analyzing the thermal performance of the steady-state thermal circuit model.

[0064] Step 1033: for each layer structure in the steady-state thermal circuit model of the cable, the thermal resistance value and the temperature value are used as data points, and a plurality of data points are fitted into a dynamic characteristic curve.

[0065] In this embodiment, according to the thermal resistance values ​​and temperature values ​​collected under different currents applied by each power supply, a data fitting method is used to form dynamic characteristic curves from these data points. These fitted dynamic characteristic curves reflect the dynamic change relationship between the thermal resistance value and the temperature value, and reflect the thermal conduction behavior of the cable under different loads. For example, as the current increases, the temperature of the conductor and the insulation layer will increase, and the corresponding thermal resistance will also change. By fitting these data, the dynamic characteristic curves obtained can accurately describe the thermal resistance characteristics of different layer structures of the cable at different temperatures.

[0066] The fitting methods include but are not limited to polynomial fitting and least squares fitting.

[0067] Polynomial fitting: Polynomial fitting is to approximate the changing trend of data through polynomial functions. Generally speaking, given a set of data points, by selecting a suitable polynomial form (e.g., quadratic, multiple, etc.), an optimal polynomial function can be found to fit the data as accurately as possible. The core idea of ​​polynomial fitting is to use the flexibility of polynomials to find the curve that best fits the data in models of different complexity.

[0068] Least squares fitting: Least squares is an optimization method whose goal is to find the best fit curve by minimizing the sum of squares of the errors between the data points and the fitted curve. The least squares method calculates the sum of the squares of the vertical distances between all data points and the fitted curve and adjusts the parameters to minimize this error.

[0069] Step 104: correct the original thermal circuit control equation according to the dynamic characteristic curve to obtain the target thermal circuit control equation.

[0070] In this embodiment, the original thermal circuit control equation is adjusted and optimized by using the dynamic characteristic curve, and finally a more accurate target thermal circuit control equation is obtained. The original thermal circuit control equation fails to fully consider the thermal response of the cable under actual working conditions, resulting in deviations in the calculation results. By correcting the original thermal circuit control equation according to the dynamic characteristic curve (i.e., the relationship between the temperature value and the thermal resistance value obtained by fitting the experimental data), the thermal circuit model can more accurately reflect the actual thermal behavior of the cable under different current and temperature conditions, thereby improving the accuracy of the cable current carrying capacity calculation and cable performance evaluation.

[0071] Specifically, the temperature value of the second target layer is substituted into the dynamic characteristic curve of the second target layer to correct the thermal resistance value of the second target layer. If the second target layer is in the environment of the steady-state thermal circuit model, the thermal resistance value of the second target layer remains unchanged. In the original thermal circuit control equation, the corrected thermal resistance value of the second target layer replaces the original thermal resistance value of the second target layer to obtain the target original thermal circuit control equation.

[0072] Among them, the target original thermal circuit control equation is expressed as:

[0073] θ 1 -θ 2 =(Q 1 +Q 2 )T 1 (θ 2 );

[0074] θ 2 -θ 3 =(Q 1 +Q 2 +Q 3 )T 2 (θ 3 );

[0075] θ 3 -θ 4 =(Q 1 +Q 2 +Q 3 +Q 4 )T 3 (θ 4 );

[0076] θ 4 -θ 5 =(Q 1 +Q 2 +Q 3 +Q 4 )T 4 ;

[0077] Among them, θ 1 is the temperature of the conductor, θ 2 is the temperature of the insulation layer, θ 3 is the temperature of the aluminum sheath, θ 4 is the temperature of the outer sheath, θ 5 is the temperature value of the environment where the steady-state thermal circuit model is located, Q 1 is the conductor loss, Q 2 The loss value of the insulation layer close to the conductor, Q 3 is the loss value of the insulating layer close to the buffer layer, Q 4 is the loss value of the aluminum sheath, T 1 (θ 2 ) is the thermal resistance value of the insulation layer corrected at the temperature of the insulation layer, T 2 (θ 3 ) is the thermal resistance value of the buffer layer corrected at the temperature of the aluminum sheath, T 3 (θ 4 ) is the corrected thermal resistance of the outer sheath at the temperature of the outer sheath, T 4 is the thermal resistance value of the environment in which the steady-state thermal circuit model is located.

[0078] Optionally, the temperature value of the conductor in the target original thermal circuit control equation may be 90 degrees Celsius.

[0079] For example, Q 1 =I 2 R(θ 1 );

[0080] Q 2 =0.5ωC(IR(θ 1 )) 2 tanδ;

[0081] Q 3 =Q 2 ;

[0082] Q 4 =λ 1 Q 1 ;

[0083] Among them, Q 1 is the conductor loss, Q 2 The loss value of the insulation layer close to the conductor, Q 3 is the loss value of the insulating layer close to the buffer layer, Q 4 is the loss value of the aluminum sheath, I is the current carrying capacity, R(θ 1 ) is the AC resistance of the conductor, C is the capacitance of the insulation layer, tanδ is the loss tangent of the insulation layer, ω is the frequency of the current, λ 1 It is the ratio of the cable metal shielding loss to the conductor loss.

[0084] Step 105: Solve the current carrying capacity of the cable according to the target thermal circuit control equation.

[0085] In this embodiment, the new target thermal circuit control equation is obtained by modifying the original thermal circuit control equation. The target thermal circuit control equation more accurately reflects the thermal characteristics of the cable in actual work. The current carrying capacity of the conductor of the cable under the preset temperature threshold can be calculated through the target thermal circuit control equation. The current carrying capacity refers to the maximum current value that can pass through the cable without exceeding the temperature limit. Through the calculation of the current carrying capacity of the cable, the comprehensive heat dissipation level of the surrounding environment of the cable can be evaluated, thereby providing guidance for the operation load distribution of the cable line.

[0086] In an embodiment of the present invention, a steady-state thermal circuit model is constructed for the cable, and the structure of the steady-state thermal circuit model includes a conductor, an insulating layer, a buffer layer, an aluminum sheath and an outer sheath. The original thermal circuit control equation is constructed for each structure of the steady-state thermal circuit model, and a dynamic characteristic curve representing the linkage change between the thermal resistance value and the temperature value under each current is constructed for each structure of the steady-state thermal circuit model. The original thermal circuit control equation is corrected according to the dynamic characteristic curve to obtain the target thermal circuit control equation, and the current carrying capacity of the cable is solved according to the target thermal circuit control equation. By constructing a steady-state thermal circuit model of the cable and performing a detailed analysis on each structure thereof, the thermal conduction characteristics of the cable under different working conditions can be accurately described. By establishing the original thermal circuit control equation for each structure and correcting the target thermal circuit control equation in combination with the dynamic characteristic curve, the temperature rise change of the cable under different currents can be more accurately simulated, thereby optimizing the thermal management of the cable. According to the corrected target thermal circuit control equation, the maximum current carrying capacity of the cable can be accurately calculated to ensure that the cable operates within a safe temperature range, and the accuracy of detecting the current carrying capacity of the cable can be improved.

[0087] Embodiment 2

[0088] Figure 3 A schematic diagram of a cable current carrying capacity calculation device provided in the second embodiment of the present invention is shown in FIG. Figure 3 As shown, the device comprises:

[0089] The model building module 301 is used to build a steady-state thermal circuit model for the cable; the structure of the steady-state thermal circuit model includes a conductor, an insulating layer, a buffer layer, an aluminum sheath and an outer sheath;

[0090] An original heat circuit control equation construction module 302 is used to construct an original heat circuit control equation for each structure of the steady-state heat circuit model;

[0091] A dynamic characteristic curve construction module 303 is used to construct a dynamic characteristic curve representing the linkage change between thermal resistance value and temperature value under each current for each structure of the steady-state thermal circuit model;

[0092] A target heat circuit control equation acquisition module 304 is used to correct the original heat circuit control equation according to the dynamic characteristic curve to obtain a target heat circuit control equation;

[0093] The current carrying capacity calculation module 305 is used to solve the current carrying capacity of the cable according to the target thermal circuit control equation.

[0094] In one embodiment of the present invention, the original thermal circuit control equation construction module 302 includes:

[0095] A target layer setting module, used to set a first target layer and a second target layer in each layer structure of the steady-state thermal circuit model; the first target layer is located inside the second target layer;

[0096] a temperature difference calculation module, used for calculating the difference between the temperature value of the first target layer and the temperature value of the second target layer to obtain the temperature difference;

[0097] A total loss calculation module, used for accumulating the loss value from the conductor to the second target layer as the total loss;

[0098] The original heat circuit control equation acquisition module is used to set the temperature difference equal to the product of the total loss and the thermal resistance value of the second target layer to obtain the original heat circuit control equation.

[0099] In one embodiment of the present invention, the original heat circuit control equation is expressed as:

[0100] θ 1 -θ 2 =(Q 1 +Q 2 )T 1 ;

[0101] θ 2 -θ 3 =(Q 1 +Q 2 +Q 3 )T 2 ;

[0102] θ 3 -θ 4 =(Q 1 +Q 2 +Q 3 +Q 4 )T 3 ;

[0103] θ 4 -θ 5 =(Q 1 +Q 2 +Q 3 +Q 4 )T 4 ;

[0104] Among them, θ 1 is the temperature value of the conductor, θ 2 is the temperature value of the insulation layer, θ 3 is the temperature value of the aluminum sheath, θ 4 is the temperature value of the outer sheath, θ 5 is the temperature value of the environment where the steady-state thermal circuit model is located, Q 1 is the loss value of the conductor, Q 2 The loss value of the insulation layer close to the conductor, Q 3 is the loss value of the insulating layer close to the buffer layer, Q 4is the loss value of the aluminum sheath, T 1 is the thermal resistance of the insulation layer, T 2 is the thermal resistance of the buffer layer, T 3 is the thermal resistance of the outer sheath, T 4 is the thermal resistance value of the environment in which the steady-state thermal circuit model is located.

[0105] In one embodiment of the present invention, the target thermal circuit control equation acquisition module 304 includes:

[0106] a thermal resistance value correction module, used for substituting the temperature value of the second target layer into the dynamic characteristic curve of the second target layer to correct the thermal resistance value of the second target layer;

[0107] a target layer judgment module, configured to keep the thermal resistance value of the second target layer unchanged if the second target layer is the environment where the steady-state thermal circuit model is located;

[0108] The original thermal circuit control equation correction module is used to replace the original thermal resistance value of the second target layer with the corrected thermal resistance value of the second target layer in the original thermal circuit control equation to obtain the target original thermal circuit control equation.

[0109] In one embodiment of the present invention, the target original heat path control equation is expressed as:

[0110] θ 1 -θ 2 =(Q 1 +Q 2 )T 1 (θ 2 );

[0111] θ 2 -θ 3 =(Q 1 +Q 2 +Q 3 )T 2 (θ 3 );

[0112] θ 3 -θ 4 =(Q 1 +Q 2 +Q 3 +Q 4 )T 3 (θ 4 );

[0113] θ 4 -θ 5 =(Q 1 +Q 2 +Q 3 +Q 4)T 4 ;

[0114] Among them, θ 1 is the temperature value of the conductor, θ 2 is the temperature value of the insulation layer, θ 3 is the temperature value of the aluminum sheath, θ 4 is the temperature value of the outer sheath, θ 5 is the temperature value of the environment where the steady-state thermal circuit model is located, Q 1 is the loss value of the conductor, Q 2 The loss value of the insulation layer close to the conductor, Q 3 is the loss value of the insulating layer close to the buffer layer, Q 4 is the loss value of the aluminum sheath, T 1 (θ 2 ) is the thermal resistance value of the insulating layer modified at the temperature value of the insulating layer, T 2 (θ 3 ) is the thermal resistance value of the buffer layer corrected at the temperature of the aluminum sheath, T 3 (θ 4 ) is the thermal resistance value of the outer sheath corrected at the temperature value of the outer sheath, T 4 is the thermal resistance value of the environment in which the steady-state thermal circuit model is located.

[0115] In one embodiment of the present invention, Q 1 =I 2 R(θ 1 );

[0116] Q 2 =0.5ωC(IR(θ 1 )) 2 tanδ;

[0117] Q 3 =Q 2 ;

[0118] Q 4 =λ 1 Q 1 ;

[0119] Among them, Q 1 is the loss value of the conductor, Q 2 The loss value of the insulation layer close to the conductor, Q 3 is the loss value of the insulating layer close to the buffer layer, Q 4 is the loss value of the aluminum sheath, I is the current carrying capacity, R(θ 1 ) is the AC resistance of the conductor, C is the capacitance of the insulating layer, tanδ is the loss tangent of the insulating layer, ω is the frequency of the current, λ 1It is the ratio of the metal shielding loss of the cable to the loss value of the conductor.

[0120] In one embodiment of the present invention, the dynamic characteristic curve construction module 303 includes:

[0121] A power supply application module, used for applying power supplies of different current values ​​to the cable;

[0122] A numerical acquisition module, used for acquiring the thermal resistance and temperature value of each layer structure in the steady-state thermal circuit model of the cable for each power supply;

[0123] The numerical fitting module is used for fitting a plurality of the data points into a dynamic characteristic curve with the thermal resistance value and the temperature value as data points for each layer structure in the steady-state thermal circuit model of the cable.

[0124] In one embodiment of the present invention, the value acquisition module includes:

[0125] The thermal resistance value calculation module is used to collect the temperature value of each layer structure in the steady-state thermal circuit model; if the temperature value of the conductor reaches a preset temperature threshold and the temperature value of each layer structure of the steady-state thermal circuit model reaches a steady state, the thermal resistance value of each layer structure in the steady-state thermal circuit model is calculated at the temperature value.

[0126] The cable current carrying capacity calculation device provided in the embodiment of the present invention can execute the cable current carrying capacity calculation method provided in any embodiment of the present invention, and has the corresponding functional modules and beneficial effects for executing the cable current carrying capacity calculation method.

[0127] Embodiment 3

[0128] See also Figure 4 , showing a schematic diagram of the structure of a computer device provided by an embodiment of the present invention. The computer device is intended to represent various forms of digital computers, such as laptop computers, desktop computers, workbenches, personal digital assistants, blade servers, mainframe computers, and other suitable computers. The computer device may also represent various forms of mobile devices, such as personal digital processing, cellular phones, smart phones, wearable devices (such as helmets, glasses, watches, etc.), and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely examples and are not intended to limit the implementation of the present invention described and / or required herein.

[0129] like Figure 4As shown, the computer device 10 includes at least one processor 11, and a memory connected to the at least one processor 11, such as a read-only memory (ROM) 12, a random access memory (RAM) 13, etc., wherein the memory stores a computer program that can be executed by at least one processor, and the processor 11 can perform various appropriate actions and processes according to the computer program stored in the read-only memory (ROM) 12 or the computer program loaded from the storage unit 18 to the random access memory (RAM) 13. In the RAM 13, various programs and data required for the operation of the computer device 10 can also be stored. The processor 11, ROM 12 and RAM 13 are connected to each other through a bus 14. An input / output (I / O) interface 15 is also connected to the bus 14.

[0130] A number of components in the computer device 10 are connected to the I / O interface 15, including: an input unit 16, such as a keyboard, a mouse, etc.; an output unit 17, such as various types of displays, speakers, etc.; a storage unit 18, such as a disk, an optical disk, etc.; and a communication unit 19, such as a network card, a modem, a wireless communication transceiver, etc. The communication unit 19 allows the computer device 10 to exchange information / data with other devices through a computer network such as the Internet and / or various telecommunication networks.

[0131] The processor 11 may be a variety of general and / or special processing components with processing and computing capabilities. Some examples of the processor 11 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various special artificial intelligence (AI) computing chips, various processors running machine learning model algorithms, a digital signal processor (DSP), and any appropriate processor, controller, microcontroller, etc. The processor 11 executes the various methods and processes described above, such as the cable current carrying capacity calculation method.

[0132] In some embodiments, the cable current carrying capacity calculation method can be implemented as a computer program, which is tangibly contained in a computer-readable storage medium, such as a storage unit 18. In some embodiments, part or all of the computer program can be loaded and / or installed on the computer device 10 via the ROM 12 and / or the communication unit 19. When the computer program is loaded into the RAM 13 and executed by the processor 11, one or more steps of the cable current carrying capacity calculation method described above can be performed. Alternatively, in other embodiments, the processor 11 can be configured to execute the cable current carrying capacity calculation method in any other appropriate manner (for example, by means of firmware).

[0133] Various implementations of the systems and techniques described above herein can be implemented in digital electronic circuit systems, integrated circuit systems, field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), systems on chips (SOCs), load programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various implementations can include: being implemented in one or more computer programs that can be executed and / or interpreted on a programmable system including at least one programmable processor, which can be a special purpose or general purpose programmable processor that can receive data and instructions from a storage system, at least one input device, and at least one output device, and transmit data and instructions to the storage system, the at least one input device, and the at least one output device.

[0134] Computer programs for implementing the methods of the present invention may be written in any combination of one or more programming languages. These computer programs may be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device, so that when the computer program is executed by the processor, the functions / operations specified in the flow chart and / or block diagram are implemented. The computer program may be executed entirely on the machine, partially on the machine, partially on the machine and partially on a remote machine as a stand-alone software package, or entirely on a remote machine or server.

[0135] In the context of the present invention, a computer-readable storage medium may be a tangible medium that may contain or store a computer program for use by or in combination with an instruction execution system, device or equipment. A computer-readable storage medium may include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices or equipment, or any suitable combination of the foregoing. Alternatively, a computer-readable storage medium may be a machine-readable signal medium. A more specific example of a machine-readable storage medium may include an electrical connection based on one or more lines, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0136] To provide interaction with a user, the systems and techniques described herein can be implemented on a computer device having: a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user; and a keyboard and a pointing device (e.g., a mouse or trackball) through which the user can provide input to the computer device. Other types of devices can also be used to provide interaction with the user; for example, the feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form (including acoustic input, voice input, or tactile input).

[0137] The systems and techniques described herein may be implemented in a computing system that includes backend components (e.g., as a data server), or a computing system that includes middleware components (e.g., an application server), or a computing system that includes frontend components (e.g., a user computer with a graphical user interface or a web browser through which a user can interact with implementations of the systems and techniques described herein), or a computing system that includes any combination of such backend components, middleware components, or frontend components. The components of the system may be interconnected by any form or medium of digital data communication (e.g., a communication network). Examples of communication networks include: a local area network (LAN), a wide area network (WAN), a blockchain network, and the Internet.

[0138] A computing system may include a client and a server. The client and the server are generally remote from each other and usually interact through a communication network. The client and server relationship is generated by computer programs running on the corresponding computers and having a client-server relationship with each other. The server may be a cloud server, also known as a cloud computing server or cloud host, which is a host product in the cloud computing service system to solve the defects of difficult management and weak business scalability in traditional physical hosts and VPS services.

[0139] Embodiment 4

[0140] An embodiment of the present invention further provides a computer program product, which includes a computer program. When the computer program is executed by a processor, the cable current carrying capacity calculation method provided by any embodiment of the present invention is implemented.

[0141] In the process of implementation, the computer program product can be written in one or more programming languages ​​or a combination thereof to perform the computer program code of the present invention, including object-oriented programming languages, such as Java, Smalltalk, C++, and conventional procedural programming languages, such as "C" language or similar programming languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a separate software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the case of a remote computer, the remote computer can be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or can be connected to an external computer (for example, using an Internet service provider to connect through the Internet).

[0142] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0143] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for calculating the current carrying capacity of a cable, characterized in that: include: Construct a steady-state thermal circuit model for the cable; The structure of the steady-state thermal circuit model includes a conductor, an insulating layer, a buffer layer, an aluminum sheath and an outer sheath; Constructing original heat circuit control equations for each structure of the steady-state heat circuit model; Constructing a dynamic characteristic curve representing the linkage change between thermal resistance value and temperature value under each current for each structure of the steady-state thermal circuit model; Correcting the original heat circuit control equation according to the dynamic characteristic curve to obtain a target heat circuit control equation; The current carrying capacity of the cable is solved according to the target thermal circuit control equation.

2. The method according to claim 1, characterized in that The constructing of the original heat circuit control equation for each structure of the steady-state heat circuit model includes: A first target layer and a second target layer are respectively set in each layer structure of the steady-state thermal circuit model; the first target layer is located inside the second target layer; Calculating a difference between a temperature value of the first target layer and a temperature value of the second target layer to obtain a temperature difference; Accumulating the loss values ​​from the conductor to the second target layer as the total loss; The temperature difference is set equal to the product of the total loss and the thermal resistance value of the second target layer to obtain the original thermal circuit control equation.

3. The method according to claim 2, characterized in that The original heat circuit control equation is expressed as: θ1-θ2=(Q1+Q2)T1; θ2-θ3=(Q1+Q2+Q3)T2; θ3-θ4=(Q1+Q2+Q3+Q4)T3; θ4-θ5=(Q1+Q2+Q3+Q4)T4; Among them, θ1 is the temperature value of the conductor, θ2 is the temperature value of the insulating layer, θ3 is the temperature value of the aluminum sheath, θ4 is the temperature value of the outer sheath, θ5 is the temperature value of the environment in which the steady-state thermal circuit model is located, Q1 is the loss value of the conductor, Q2 is the loss value of the insulating layer close to the conductor, Q3 is the loss value of the insulating layer close to the buffer layer, Q4 is the loss value of the aluminum sheath, T1 is the thermal resistance value of the insulating layer, T2 is the thermal resistance value of the buffer layer, T3 is the thermal resistance value of the outer sheath, and T4 is the thermal resistance value of the environment in which the steady-state thermal circuit model is located.

4. The method according to claim 2, characterized in that: The step of correcting the original heat circuit control equation according to the dynamic characteristic curve to obtain a target heat circuit control equation includes: Substituting the temperature value of the second target layer into the dynamic characteristic curve of the second target layer to correct the thermal resistance value of the second target layer; If the second target layer is the environment where the steady-state thermal circuit model is located, the thermal resistance value of the second target layer remains unchanged; In the original thermal circuit control equation, the corrected thermal resistance value of the second target layer replaces the original thermal resistance value of the second target layer to obtain the target original thermal circuit control equation.

5. The method according to claim 4, characterized in that The target original heat path control equation is expressed as: θ1-θ2=(Q1+Q2)T1(θ2); θ2-θ3=(Q1+Q2+Q3)T2(θ3); θ3-θ4=(Q1+Q2+Q3+Q4)T3(θ4); θ4-θ5=(Q1+Q2+Q3+Q4)T4; Among them, θ1 is the temperature value of the conductor, θ2 is the temperature value of the insulation layer, θ3 is the temperature value of the aluminum sheath, θ4 is the temperature value of the outer sheath, θ5 is the temperature value of the environment in which the steady-state thermal circuit model is located, Q1 is the loss value of the conductor, Q2 is the loss value of the insulation layer close to the conductor, Q3 is the loss value of the insulation layer close to the buffer layer, Q4 is the loss value of the aluminum sheath, T1(θ2) is the corrected thermal resistance value of the insulation layer at the temperature value of the insulation layer, T2(θ3) is the corrected thermal resistance value of the buffer layer at the temperature value of the aluminum sheath, T3(θ4) is the corrected thermal resistance value of the outer sheath at the temperature value of the outer sheath, and T4 is the thermal resistance value of the environment in which the steady-state thermal circuit model is located.

6. The method according to claim 3 or 5, characterized in that: Q1=I 2 R(θ1); <h2 style=";text-align:left;direction:ltr">Q2 = 0.5ωC(IR(θ1))<h2 style=";text-align:left;direction:ltr"> 2 <h2 style=";text-align:left;direction:ltr"> tanδ; Q3 = Q2; Q4=λ1Q1; Among them, Q1 is the loss value of the conductor, Q2 is the loss value of the insulation layer close to the conductor, Q3 is the loss value of the insulation layer close to the buffer layer, Q4 is the loss value of the aluminum sheath, I is the current carrying capacity, R(θ1) is the AC resistance of the conductor, C is the capacitance of the insulation layer, tanδ is the loss tangent of the insulation layer, ω is the frequency of the current, and λ1 is the ratio of the cable metal shielding loss to the conductor loss value.

7. The method according to any one of claims 1 to 5, characterized in that: The dynamic characteristic curves representing the linkage changes between thermal resistance value and temperature value under each current are constructed for each structure of the steady-state thermal circuit model, including: applying power sources of different current values ​​to the cable; For each of the power supplies, collecting the thermal resistance and temperature of each layer structure in the cable steady-state thermal circuit model; For each layer structure in the steady-state thermal circuit model of the cable, the thermal resistance value and the temperature value are used as data points, and a plurality of the data points are fitted into a dynamic characteristic curve.

8. The method according to claim 7, characterized in that For each of the power supplies, collecting the thermal resistance and temperature of each layer structure in the cable thermal circuit model includes: The temperature value of each layer structure in the steady-state thermal circuit model is collected; if the temperature value of the conductor reaches a preset temperature threshold, and the temperature value of each layer structure of the steady-state thermal circuit model reaches a steady state, the thermal resistance value of each layer structure in the steady-state thermal circuit model is calculated at the temperature value.

9. A computer device, characterized in that: The computer device comprises: one or more processors; A storage device for storing one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors implement the cable current carrying capacity calculation method as described in any one of claims 1-8.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the cable current carrying capacity calculation method as described in any one of claims 1-8 is implemented.

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