A method and system for evaluating the risk of wire operation and a terminal device thereof

Abstract

The application discloses a kind of conductor operation risk assessment method, system and its terminal equipment, belong to conductor state assessment technical field, this method is: based on real-time operating tension and conductor structure parameter acquisition interlayer comprehensive contact thermal resistance set;Based on real-time line current, conductor structure parameter and preset skin effect coefficient calculation unit length heat generation rate, based on unit length heat generation rate and interlayer comprehensive contact thermal resistance set constructs radial temperature distribution thermal circuit model;Conductor surface layer temperature and ambient temperature are input in radial temperature distribution thermal circuit model to obtain real-time temperature;Based on real-time temperature and temperature-mechanical property degradation model obtains tensile strength, to based on tensile strength and conductor structure parameter calculation limit bearing capacity;Based on real-time operating tension to obtain actual share load and calculate safety margin, to based on safety margin and preset safety threshold value output the risk assessment result of to-be-measured conductor, realize to the precise dynamic evaluation of each layer failure risk in conductor internal.

Description

Technical Field

[0001] This invention relates to the field of conductor condition assessment technology, and in particular to a method, system and terminal equipment for assessing conductor operation risks. Background Technology

[0002] With the continuous advancement of the global energy internet strategy and the increasing electricity load, high-voltage and ultra-high-voltage overhead transmission lines often need to carry currents close to their design limits during operation. This high current-carrying state directly leads to a significant increase in conductor operating temperature. Under long-term high-temperature operation, the mechanical properties of the internal materials of overhead conductors (such as aluminum, steel, and aluminum-clad steel) undergo irreversible degradation. Specifically, key mechanical parameters such as tensile strength and elastic modulus continuously decrease with the cumulative effect of time and temperature. This degradation of material properties directly weakens the conductor's sag safety margin, reduces its actual current-carrying capacity, and significantly shortens the overall service life of the conductor, posing a serious threat to the safe and stable operation of the transmission system.

[0003] Existing technologies for assessing the operational risks of overhead conductors under high-temperature conditions suffer from three main shortcomings and defects: First, most existing assessment methods rely on monitoring and calculating the surface temperature or average cross-sectional temperature of the conductor. This makes it difficult to accurately reflect the significant radial temperature gradient within the conductor caused by factors such as uneven solar radiation distribution, uneven current distribution among strands, and the skin effect. Consequently, these methods cannot obtain the precise thermal state of each structural layer within the conductor, leading to significant deviations in the assessment of the actual mechanical property degradation of each material layer. Second, although thermal aging models based on the principle of thermal equilibrium and fatigue life prediction methods based on statistical laws have been developed in this field, these models and methods typically employ empirical formulas or simplified assumptions. They lack a precise and direct quantitative mapping relationship from real-time temperature monitoring to the core mechanical properties of the material (such as tensile strength), making it difficult for existing technologies to meet practical engineering needs in terms of short-term operational risk warning and accurate remaining life assessment. Third, existing risk assessment methods are mostly based on the overall macroscopic mechanical parameters of the conductor (such as overall tensile strength and overall safety factor), neglecting the differentiated degradation behavior of each layer of the conductor's unique layered stranded structure at high temperatures. This makes it impossible to identify and warn of chain reactions such as load transfer to the steel core caused by the initial strength failure of a specific layer (e.g., the outer aluminum strand), thus failing to achieve dynamic risk warning based on layered failure. Therefore, how to achieve real-time and accurate perception of the mechanical properties of each structural layer of the conductor, and on this basis, to conduct dynamic quantitative assessment of operational risks, is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0004] This invention provides a method, system, and terminal device for assessing the operational risk of conductors. It can solve the technical problem in the prior art that it is impossible to identify the differentiated degradation behavior of each layer, thus making it impossible to achieve real-time and accurate perception of the mechanical properties of the materials of each structural layer inside the conductor. It enables a refined and dynamic assessment of the failure risk of each layer inside the conductor.

[0005] This invention provides a method for assessing the operational risk of conductors, comprising: The system acquires real-time line current, conductor surface temperature, real-time operating tension, conductor structural parameters, and ambient temperature of the conductor under test; wherein the conductor under test comprises several conductor layers. The set of interlayer comprehensive contact thermal resistance is obtained based on the real-time operating tension and conductor structure parameters. Based on the real-time line current, conductor structure parameters and preset skin effect coefficient, calculate the heat generation rate per unit length of each conductor layer, and construct a radial temperature distribution thermal path model based on the heat generation rate per unit length of each conductor layer and the set of interlayer comprehensive contact thermal resistance. The surface temperature of the conductor and the ambient temperature are input into the radial temperature distribution thermal path model for recursive calculation to obtain the real-time temperature corresponding to each conductor layer. The tensile strength of each conductor layer is obtained based on the real-time temperature and the pre-built temperature-mechanical property degradation model, and the ultimate bearing capacity of each conductor layer is calculated based on the tensile strength of each conductor layer and the wire structure parameters. The actual load-sharing of each conductor layer is obtained based on the real-time operating tension. The safety margin of each conductor layer is calculated based on the actual load-sharing and the ultimate bearing capacity of each conductor layer. The risk assessment result of the conductor under test is then output based on the safety margin and the preset safety threshold.

[0006] The above scheme first obtains the real-time line current, conductor surface temperature, real-time operating tension, conductor structural parameters, and ambient temperature of the conductor under test. Based on the real-time operating tension and conductor structural parameters, it obtains the interlayer comprehensive contact thermal resistance set. Simultaneously, based on the real-time line current, conductor structural parameters, and a preset skin effect coefficient, it calculates the heat generation rate per unit length of each conductor layer. Using this heat generation rate and the interlayer comprehensive contact thermal resistance set, it constructs a radial temperature distribution thermal path model, linking the conductor's macroscopic operating parameters with its complex internal microscopic stranding structure and electromagnetic properties. This constructs a physical model that can precisely characterize the heat transfer process from the inside out, avoiding the defect of treating the conductor as a homogeneous whole and ignoring the radial temperature gradient. Then, the conductor surface temperature and ambient temperature are input into the radial temperature distribution thermal path model for recursive calculation to obtain the real-time temperature of each conductor layer. Starting from the easily measurable surface temperature, it accurately inverts the thermal path. The system obtains the true temperature of each structural layer inside the conductor, which is difficult to measure directly. Then, based on the real-time temperature of each conductor layer and a pre-constructed temperature-mechanical property degradation model, the tensile strength of each conductor layer is obtained. Based on this, the ultimate bearing capacity of each conductor layer is calculated in combination with the conductor structural parameters, realizing a direct quantitative mapping from real-time temperature to the core mechanical properties of the material. This solves the technical steady-state problem of existing thermal aging models lacking an accurate temperature-mechanical property mapping relationship. At the same time, based on the real-time operating tension, the actual load-bearing capacity of each conductor layer is obtained. Finally, based on the ultimate bearing capacity and the actual load-bearing capacity, the safety margin corresponding to each conductor layer is calculated. Based on the safety margin and the preset safety threshold, the risk assessment result is output. By comparing the bearing capacity with the actual load layer by layer, a refined and dynamic assessment of the failure risk of each layer inside the conductor is achieved, avoiding the technical problem in the existing technology that cannot identify the layered differential degradation behavior based on the overall mechanical parameter assessment.

[0007] Furthermore, the step of obtaining the set of interlayer comprehensive contact thermal resistances based on the real-time operating tension and conductor structure parameters includes: For each adjacent conductor layer in the conductor under test, a contact thermal resistance calculation is performed to obtain an interlayer comprehensive contact thermal resistance set including the total interlayer contact thermal resistance of all adjacent conductor layers; the adjacent conductor layers include inner conductor layers and outer conductor layers; wherein, the contact thermal resistance calculation includes: The number of single conductors corresponding to the inner conductor layer, the pitch of the inner conductor layer, and the pitch of the outer conductor layer are obtained from the conductor structure parameters. The number of contact points per unit length is obtained based on the number of single conductors, the pitch of the inner conductor layer, and the pitch of the outer conductor layer. The total radial stress of the inner conductor layer is obtained based on the real-time operating tension, and the radial pressure of the contact point corresponding to the inner conductor layer is obtained based on the total radial stress of the conductor layer. Obtain the thermal conductivity coefficient of metal point contact, the thermal conductivity coefficient of contact gap, and the thermal conductivity coefficient of air pores; Based on the thermal conductivity coefficient of the metal point contact, the thermal conductivity coefficient of the contact gap, the thermal conductivity coefficient of the air pore, and the radial pressure of the contact point, the corresponding thermal resistance of the metal point contact, the thermal resistance of the contact gap, and the thermal resistance of the air pore contact are calculated respectively. The interlayer comprehensive contact thermal resistance is obtained by calculating the parallel resistance based on the metal point contact thermal resistance, contact gap contact thermal resistance and air pore contact thermal resistance. The interlayer composite contact thermal resistance is taken as the interlayer composite contact thermal resistance corresponding to the adjacent conductor layer.

[0008] The above scheme starts from the microscopic geometric characteristics (including the number of strands, pitch, etc.) and macroscopic stress state (real-time operating tension) of the conductor stranded structure, and quantifies the resistance caused by three different contact states during heat transfer between layers: physical contact of metal points, micron-level contact gaps, and macroscopic air pores. It simulates this as the comprehensive contact thermal resistance between layers to truly reflect the physical heat transfer characteristics of the conductor. This allows the subsequent radial thermal path model to accurately capture the significant temperature drop caused by different interlayer contacts, and solves the technical problem of insufficient accuracy in temperature inversion of internal layers due to neglecting or roughly estimating this contact thermal resistance in existing technologies.

[0009] Further, the step of calculating the heat generation rate per unit length for each conductor layer based on the real-time line current, conductor structure parameters, and a preset skin effect coefficient, and constructing a radial temperature distribution thermal path model based on the heat generation rate per unit length for each conductor layer and the set of interlayer comprehensive contact thermal resistance, includes: The conductor layer current corresponding to each conductor layer is obtained based on the real-time line current and conductor structure parameters. The basic thermal efficiency per unit length of each conductor layer is obtained based on the conductor layer current corresponding to each conductor layer. The basic thermal parameter function for each conductor layer is constructed based on the basic thermal parameter per unit length for each conductor layer and the preset linear temperature resistance influence function. The heat generation rate per unit length of each conductor layer is obtained based on the basic thermal efficiency function corresponding to each conductor layer and the preset skin effect coefficient. A radial temperature distribution thermal path model is constructed based on the heat generation rate per unit length of each conductor layer and the combined interlayer contact thermal resistance.

[0010] The above scheme, in calculating the heat generation rate of each conductor layer, introduces a preset skin effect coefficient to account for the influence of the skin effect on the resistance-temperature relationship, thereby achieving accurate quantification of the heat source distribution inside the conductor. This ensures that the heat source terms that serve as the driving force in the thermal circuit model are layered, accurate, and in line with physical reality. It provides a reliable heat source input for subsequently retrieving accurate temperature distribution of each layer through the thermal circuit model, and solves the risk assessment deviation problem caused by simply dividing the current equally or ignoring the influence of AC electromagnetic effects on heat generation distribution in the existing technology.

[0011] Further, obtaining the conductor layer current corresponding to each conductor layer based on the real-time line current and conductor structure parameters includes: Based on the aforementioned conductor structure parameters, construct several parallel conductor simulation structures corresponding to the conductor layers; The resistance per unit length for each conductor layer is obtained from the aforementioned conductor structure parameters; The conductor layer current corresponding to each conductor layer is obtained based on the real-time line current, the unit length resistance of each conductor layer, and the parallel conductor simulation structure.

[0012] The above scheme utilizes the resistance per unit length of each conductor layer, a parameter that can be directly calculated or obtained from tables based on materials and dimensions. This allows for the rapid and reasonable determination of the total current flowing through different functional layers, even when only the total current is known. This lays the data foundation for subsequent, more precise layer-by-layer current distribution and heat generation calculations.

[0013] Furthermore, the construction of the radial temperature distribution thermal path model based on the heat generation rate per unit length of each conductor layer and the combined interlayer contact thermal resistance includes: Calculate the ambient thermal resistance based on the surface temperature of the conductor and the ambient temperature; A set of thermal circuit principle equations is constructed based on the interlayer integrated contact thermal resistance set, the ambient thermal resistance, and the heat generation rate per unit length of each conductor layer. The thermal circuit principle equations are recursively solved and transformed to construct a radial temperature distribution thermal circuit model.

[0014] The above scheme establishes a clear calculation process by recursively solving the problem, which calculates the temperature of each internal layer from the outermost layer of the conductor inwards, enabling the model to output the complete radial temperature distribution of the conductor stably and efficiently.

[0015] Furthermore, in obtaining the tensile strength of each conductor layer based on the real-time temperature and the pre-built temperature-mechanical property degradation model, and calculating the ultimate bearing capacity of each conductor layer based on the tensile strength and the conductor structure parameters, the pre-construction process of the temperature-mechanical property degradation model includes: Prepare several monofilament samples corresponding to the conductor to be tested; For any single filament sample among the several single filament samples, the original performance test results are obtained based on the preset experimental parameters and the pre-built tensile test platform, and the material strength degradation coefficient is obtained based on the preset experimental parameters and the original performance test results, so as to construct a performance degradation relationship model based on the material strength degradation coefficient. A temperature-mechanical property degradation model is formed based on the performance degradation relationship models corresponding to several monofilament samples.

[0016] The above scheme quantifies the mechanical property degradation law of different conductor materials at high temperature through standardized offline experiments and data processing procedures, and extracts the key material strength degradation coefficient, providing strength judgment reference support for the online evaluation stage. This enables the real load-bearing capacity of each layer to be calculated immediately after knowing the real-time temperature of each conductor layer, thus achieving accurate quantitative evaluation of the temperature-mechanical properties of specific conductor materials.

[0017] Further, the tensile strength of each conductor layer is obtained based on the real-time temperature and the pre-constructed temperature-mechanical property degradation model corresponding to each conductor layer, and the ultimate bearing capacity of each conductor layer is calculated based on the tensile strength of each conductor layer and the conductor structure parameters, including: The tensile strength of each conductor layer is obtained based on the real-time temperature of each conductor layer and the pre-constructed temperature-mechanical property degradation model. The cross-sectional area of ​​a single strand and the number of strands in each conductor layer are obtained from the conductor structure parameters, and the total cross-sectional area of ​​each conductor layer is calculated based on the cross-sectional area of ​​a single strand and the number of strands in each conductor layer. The ultimate bearing capacity of each conductor layer is obtained by multiplying its tensile strength and total cross-sectional area.

[0018] The above scheme combines the strength degradation at the material level with the geometric dimensions at the structural level, accurately calculating the maximum tensile force that each structural layer as a whole can withstand at real-time temperature, thus quantifying the true load-bearing limit of each conductor layer of the conductor at different temperatures.

[0019] Furthermore, the step of calculating the safety margin of each conductor layer based on the actual shared load and the ultimate bearing capacity of each conductor layer, and outputting the risk assessment result of the conductor under test based on the safety margin and a preset safety threshold, includes: The safety margin for each conductor layer is calculated based on the ultimate bearing capacity of each conductor layer and the actual load shared by each conductor layer. When there is a safety margin of not less than a preset safety threshold in the safety margin corresponding to each conductor layer, it is determined that there is a conductor layer failure, and the risk assessment result of the test wire having a risk of breakage is output.

[0020] The above solution monitors the safety status of all conductor layers and can issue timely warnings when conductor layers fail. For example, the outer aluminum wire of the conductor is relatively thin, so the safety margin of the conductor layer corresponding to the outer aluminum wire is usually the first to exceed the preset safety threshold. At this time, this solution can issue an alarm before the outer aluminum wire loses its effective load-bearing capacity due to high temperature softening, causing the tension to be transferred to the inner conductor layer (such as steel core), which is a critical dangerous node, thus achieving accurate early warning of the delamination characteristics of the conductor.

[0021] This invention provides a method for assessing the operational risk of overhead conductors. Starting from easily measurable parameters on the surface of the conductor, it delves into the invisible internal state, such as radial temperature distribution and layered safety margins, and ultimately provides a complete risk assessment process for dynamic line breakage risk levels. By establishing a high-temperature degradation model for materials, constructing a thermal circuit model considering interlayer microscopic contact, and conducting layered safety assessment based on weak points, the method elevates the operational risk assessment of conductors from the traditional extensive mode based on overall assumptions to a refined level that accurately perceives internal states and dynamically identifies layered failures. This achieves a refined and dynamic assessment of the failure risks of each layer within the conductor, significantly improving the accuracy and timeliness of risk warnings, and providing a scientific basis for ensuring the safe operation of transmission lines under high-temperature and high-load conditions.

[0022] This invention also provides a conductor operation risk assessment system, comprising: a data acquisition module, a temperature distribution analysis module, a performance parameter acquisition module, and a performance degradation analysis module; wherein: The data acquisition module is used to acquire the real-time line current, conductor surface temperature, real-time operating tension, conductor structural parameters, and ambient temperature of the conductor under test; wherein, the conductor under test includes several conductor layers; The temperature distribution analysis module is used to obtain the set of interlayer comprehensive contact thermal resistance based on the real-time operating tension and conductor structural parameters; to calculate the heat generation rate per unit length of each conductor layer based on the real-time line current, conductor structural parameters and preset skin effect coefficient; and to construct a radial temperature distribution thermal path model based on the heat generation rate per unit length of each conductor layer and the set of interlayer comprehensive contact thermal resistance; and to recursively calculate the real-time temperature of each conductor layer by inputting the conductor surface temperature and ambient temperature into the radial temperature distribution thermal path model. The performance parameter acquisition module is used to obtain the tensile strength of each conductor layer based on the real-time temperature of each conductor layer and the pre-built temperature-mechanical property degradation model, so as to calculate the ultimate bearing capacity of each conductor layer based on the tensile strength of each conductor layer and the conductor structure parameters. The performance degradation analysis module is used to obtain the actual load-sharing of each conductor layer based on the real-time operating tension; calculate the safety margin of each conductor layer based on the actual load-sharing of each conductor layer and the ultimate bearing capacity of each conductor layer; and output the risk assessment result of the conductor under test based on the safety margin and the preset safety threshold.

[0023] This invention provides a conductor operation risk assessment system, which solidifies the aforementioned refined conductor operation risk assessment method into an integrated technical solution that includes modules such as data acquisition, temperature distribution analysis, performance parameter acquisition, and performance degradation analysis. This system can access online monitoring data of transmission lines in real time and automatically execute the entire calculation process from data preprocessing, multi-physics coupling modeling, internal state inversion to risk level determination. This enables power grid operation and maintenance departments to visualize and monitor the actual health status of the conductors in real time, and to receive clear graded early warnings before danger occurs. This achieves proactive and precise management of high-voltage transmission line operation risks, improving the intelligent operation and maintenance level and safe power supply capability of the power grid.

[0024] The present invention also provides a terminal device, including a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein when the processor executes the computer program, it implements the above-described method for assessing the risk of conductor operation. Attached Figure Description

[0025] To more clearly illustrate the technical solution of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of a conductor operation risk assessment method provided in this embodiment; Figure 2 This is a schematic diagram of a parallel structure of the conductor to be tested provided in this embodiment; Figure 3 This is a schematic diagram of a radial temperature distribution thermal path model provided in this embodiment; Figure 4 This is a schematic diagram of an internal parallel circuit of a conductor under test provided in this embodiment; Figure 5 This is a schematic diagram of a conductor operation risk assessment system provided in this embodiment; Figure 6 This is a schematic diagram of a complete process for assessing the operational risks of a conductor, as provided in this embodiment. Among them, 1. Parallel structure of outer conductor layer; 2. Parallel structure of inner conductor layer. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0029] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0030] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0031] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0032] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0033] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0034] Example 1: like Figure 1 As shown, this embodiment provides a method for assessing the operational risk of conductors, including: S1. Obtain the real-time line current, conductor surface temperature, real-time operating tension, conductor structural parameters, and ambient temperature of the conductor under test. The wire to be tested includes several conductor layers; S2. Obtain the set of interlayer comprehensive contact thermal resistance based on the real-time operating tension and conductor structure parameters; S3. Calculate the heat generation rate per unit length of each conductor layer based on the real-time line current, conductor structure parameters and preset skin effect coefficient, and construct a radial temperature distribution thermal path model based on the heat generation rate per unit length of each conductor layer and the set of interlayer comprehensive contact thermal resistance. S4. Input the surface temperature of the conductor and the ambient temperature into the radial temperature distribution thermal path model for recursive calculation to obtain the real-time temperature corresponding to each conductor layer. S5. Based on the real-time temperature of each conductor layer and the pre-built temperature-mechanical property degradation model, obtain the tensile strength of each conductor layer, and calculate the ultimate bearing capacity of each conductor layer based on the tensile strength of each conductor layer and the wire structure parameters. S6. Obtain the actual shared load corresponding to each conductor layer based on the real-time operating tension; S7. Calculate the safety margin of each conductor layer based on the actual shared load and the ultimate bearing capacity of each conductor layer, and output the risk assessment result of the conductor under test based on the safety margin and the preset safety threshold.

[0035] In the specific implementation process, this embodiment takes the steel-cored aluminum stranded wire as an example for explanation.

[0036] Optionally, step S2 includes: For each adjacent conductor layer in the conductor under test, a contact thermal resistance calculation is performed to obtain an interlayer comprehensive contact thermal resistance set including the total interlayer contact thermal resistance of all adjacent conductor layers; the adjacent conductor layers include inner conductor layers and outer conductor layers; wherein, the contact thermal resistance calculation includes: The number of single conductors corresponding to the inner conductor layer, the pitch of the inner conductor layer, and the pitch of the outer conductor layer are obtained from the conductor structure parameters. The number of contact points per unit length is obtained based on the number of single conductors, the pitch of the inner conductor layer, and the pitch of the outer conductor layer. The total radial stress of the inner conductor layer is obtained based on the real-time operating tension, and the radial pressure of the contact point corresponding to the inner conductor layer is obtained based on the total radial stress of the conductor layer. Obtain the thermal conductivity coefficient of metal point contact, the thermal conductivity coefficient of contact gap, and the thermal conductivity coefficient of air pores; Based on the thermal conductivity coefficient of the metal point contact, the thermal conductivity coefficient of the contact gap, the thermal conductivity coefficient of the air pore, and the radial pressure of the contact point, the corresponding thermal resistance of the metal point contact, the thermal resistance of the contact gap, and the thermal resistance of the air pore contact are calculated respectively. The interlayer comprehensive contact thermal resistance is obtained by calculating the parallel resistance based on the metal point contact thermal resistance, contact gap contact thermal resistance and air pore contact thermal resistance. The interlayer composite contact thermal resistance is taken as the interlayer composite contact thermal resistance corresponding to the adjacent conductor layer.

[0037] Optionally, the conductor layer is an outer conductor or an inner conductor layer, that is, the wire to be tested includes several outer conductor layers and several inner conductor layers.

[0038] In practical implementation, taking the test conductor of an n-layer steel-cored aluminum stranded wire as an example, the outer conductor layers refer to the outer aluminum conductor layers, and the inner conductor layers refer to the central steel conductor layers, which are usually a single steel core. Each aluminum conductor layer is formed by several aluminum strands, and each steel conductor layer is formed by several steel strands. The center is the 0th layer, and the outermost layer is the nth conductor layer.

[0039] In practical implementation, the main reason for the temperature gradient inside the conductor under test is the temperature drop caused by heat passing through metal-metal point contacts, contact gaps, and air pores. In this embodiment, the comprehensive contact thermal resistance between any adjacent conductor layers inside the conductor under test can be simulated as follows: Figure 2 The parallel structure of the conductors to be tested is shown, wherein This represents the combined interlayer contact thermal resistance between the i-th conductor layer and the (i+1)-th conductor layer. This indicates the thermal resistance of a metal-to-metal point contact. Indicates the contact gap thermal resistance. Indicates the thermal resistance of air gap contact. This represents the temperature of the i-th conductor layer. The temperature of the (i+1)th conductor layer is given by... Figure 2 The simulated parallel relationship can be obtained as follows: In this process, the i-th conductor layer is the inner conductor layer, and the (i+1)-th conductor layer is the outer conductor layer.

[0040] In the specific calculation process, the number of single strands of the i-th layer of single conductor is first obtained from the conductor structure parameters. That is, the number of single conductors, and the inner conductor pitch of the i-th layer conductor and the outer conductor pitch of the (i+1)-th layer conductor, and thereby calculate the number of contact points per unit length between the i-th layer conductor and the (i+1)-th layer conductor. The specific calculation process is shown in the following formula: ; In the formula, This represents the pitch of the inner conductor of the i-th layer. This represents the outer conductor pitch of the (i+1)th conductor layer, where, for the steel conductor layer at the core position of the conductor under test, , This represents the number of single strands in the i-th layer conductor.

[0041] Next, based on the radial stress transfer theory in the layered mechanics of overhead conductors, the radial force of a single layer of strands is first calculated, for including The k-th conductor of a monofilament strand, where the axial tension of any monofilament strand is... Due to the helical geometry, this axial tension will generate a centripetal radial component force per unit length of the strand. The twist angle of the monofilament strands in the i-th layer conductor is obtained from the conductor structure parameters. and the spiral radius of that layer The helix radius, also known as the pitch circle radius, is the distance from the center of the strand to the conductor axis. According to the classic Costello's Ordinary Elastic Theory of Wire Rope, the relationship between this radial component of the force and the axial tension, lay angle, and the radius of the strand can be expressed as follows: Among them, under engineering conditions with a smaller twist angle, Therefore, the above formula can be simplified to: Therefore, the total radial stress on the i-th conductor layer is obtained by multiplying the radial component of the single strand by the number of strands. ,Right now .

[0042] For any circular strand conductor layer concentrically twisted in the conductor under test, the helix radius of the k-th layer is... It can be approximated as the diameter of the monofilament in this layer. The function of layer number k, under the assumption that the diameter of each filament in each layer of the conductor under test is the same (denoted as d), has the following geometric relationship: ; Therefore, the total radial stress of a single layer can be expressed as follows: ; In practice, since the total operating tension of the conductor is not uniformly distributed across all layers, the axial stiffness of the k-th layer conductor is related to the cross-sectional area of ​​the single strands in that layer. Elastic modulus and twisted corner Related. The axial stiffness of the monofilament strand can be expressed as: Therefore, the total axial stiffness of the k-th layer The contribution can be expressed as follows: ; Assuming that the cross-sectional area of ​​the monofilament strands in each layer of material is the same, the stiffness ratio of each layer simplifies to: The total tension F is distributed to each layer according to the stiffness ratio, so the total axial tension borne by the k-th layer is... for: ; In the formula, This represents the number of single-strand wires in the i-th layer of conductor. Let be the twist angle of the single strand in the i-th layer of conductor, and F represent the real-time operating tension; then the axial tension borne by a single strand is: ; Substituting this axial tension into the expression for the total radial stress of a single layer, we get the total radial stress of a single layer as follows: ; The total radial stress on the i-th conductor layer is equal to the sum of the radial forces generated by all conductor layers located outside it (i.e., the (i+1)-th to (n)-th conductor layers). Therefore, the total radial stress on the i-th conductor layer can be calculated based on the total radial stress of a single layer. The specific calculation process is shown in the following formula: ; When the conductor under test in this embodiment includes a steel core layer (i.e., inner conductor layer) and two aluminum conductor layers (i.e., outer conductor layers) located at the conductor core position, the total radial stress of the i-th aluminum conductor layer is... It can be expressed as follows: ; Then the radial pressure at each contact point of the i-th layer conductor is .

[0043] For the thermal conductivity of metal-metal point contacts It can be described as: ; In the formula, This is the harmonic mean of the thermal conductivity of the two materials, where the aluminum conductor layer is valued at 226 W / (m·K), the steel core layer at 15 W / (m·K), and the steel-aluminum contact layer at 75 W / (m·K). H represents the slope of the micro-protrusions on the contact surface, and H represents the microhardness of the material in Pa, which is related to the yield stress of the material. It is the average stress of the apparent contact area, where A represents the contact area of ​​a single contact point. In this embodiment, the apparent contact area between the strands of the conductor under test is usually preset according to experience. Specifically, the apparent contact area of ​​steel-aluminum is usually considered to be 0.5 mm2 / mm, and the apparent contact area of ​​aluminum-aluminum is usually considered to be 0.05 mm2 / mm. Therefore, for the metal-metal point contact thermal resistance per unit length of conductor in the i-th layer and the (i+1)-th layer, It can be described as follows: ; in, This represents the contact area between metal-to-metal point contacts per unit length between the i-th layer and the (i+1)-th layer. , This represents the area of ​​a single metal-to-metal point contact between the conductors of layer i and layer i+1. , It indicates the microhardness of the softer material, for example, the hardness of aluminum is taken for the contact between aluminum and steel layers, and the hardness of aluminum is taken for aluminum-aluminum contact. Correspondingly, the contact thermal resistance of the metal-to-metal contact gap in the unit length conductors of the i-th and (i+1)-th layers can be described by the following formula: ; in, This represents the contact gap thermal conductivity coefficient between the i-th and (i+1)-th layers per unit length of conductor for metal-to-metal point contact. , The thermal conductivity of air, The effective length of the contact gap can be 1µm; The total contact area of ​​the contact gaps per unit length of conductor, where, , This represents the apparent contact area of ​​two adjacent conductors per unit length in the i-th and (i+1)-th layers that may come into geometric contact. Where C is the empirical contact coefficient (usually taken as 0.1~0.3), which takes into account the influence of the cross angle and the effective contact width, and can be calibrated through experiments or finite element simulation.

[0044] Accordingly, the air pore contact thermal resistance between the i-th layer and the (i+1)-th layer per unit length of conductor can be described as follows: ; in, This represents the air pore thermal conductivity coefficient between the i-th layer and the (i+1)-th layer per unit length. ; This represents the equivalent scale of the macroscopic air pores in the direction of heat conduction between layers i and i+1 with no metal contact per unit length. In this embodiment, this value is typically taken as a constant on the sub-millimeter scale. This represents the area of ​​the air pores between conductors per unit length, where: .

[0045] Finally, the metal point contact thermal resistance, contact gap contact thermal resistance, and air pore contact thermal resistance obtained in the above calculation process are substituted into the calculation formula. Parallel resistance calculations were performed to obtain the overall interlayer contact thermal resistance. .

[0046] Optionally, step S3 includes: The conductor layer current corresponding to each conductor layer is obtained based on the real-time line current and conductor structure parameters. The basic thermal efficiency per unit length of each conductor layer is obtained based on the conductor layer current corresponding to each conductor layer. The basic thermal parameter function for each conductor layer is constructed based on the basic thermal parameter per unit length for each conductor layer and the preset linear temperature resistance influence function. The heat generation rate per unit length of each conductor layer is obtained based on the basic thermal efficiency function corresponding to each conductor layer and the preset skin effect coefficient. A radial temperature distribution thermal path model is constructed based on the heat generation rate per unit length of each conductor layer and the combined interlayer contact thermal resistance.

[0047] Optionally, obtaining the conductor layer current corresponding to each conductor layer based on the real-time line current and conductor structure parameters includes: Based on the aforementioned conductor structure parameters, construct several parallel conductor simulation structures corresponding to the conductor layers; The resistance per unit length for each conductor layer is obtained from the aforementioned conductor structure parameters; The conductor layer current corresponding to each conductor layer is obtained based on the real-time line current, the unit length resistance of each conductor layer, and the parallel conductor simulation structure.

[0048] Optionally, if the conductor layer current corresponding to each conductor layer, the outer conductor layer current corresponding to each outer conductor layer, and the inner conductor layer current corresponding to each inner conductor layer are defined, then the parallel conductor simulation structure includes a parallel outer conductor layer structure and a parallel inner conductor layer structure. The unit length resistance includes the unit length resistance of the outer conductor layer and the unit length resistance of the inner conductor layer. The conductor layer current includes the outer conductor layer current and the inner conductor layer current. Then, step S3 includes: obtaining the unit length resistance of the outer conductor layer and the unit length resistance of the inner conductor layer from the conductor structure parameters; obtaining the simulated total resistance of the outer conductor layer based on the parallel outer conductor layer structure and the unit length resistance of the outer conductor layer, and obtaining the simulated total resistance of the inner conductor layer based on the parallel inner conductor layer structure and the unit length resistance of the inner conductor layer; obtaining the total resistance of the outer conductor layer based on the real-time line current, the simulated total resistance of the outer conductor layer, the simulated total resistance of the inner conductor layer, and the parallel conductor simulation structure. The process involves: obtaining the total current of the outer conductor layer and the total current of the inner conductor layer; obtaining the outer conductor layer current corresponding to each outer conductor layer based on the total current of the inner conductor layer and the conductor structure parameters; obtaining the corresponding basic thermal efficiency per unit length of the outer layer based on the outer conductor layer current; obtaining the corresponding basic thermal efficiency per unit length of the inner layer based on the inner conductor layer current; constructing a basic thermal efficiency function for each conductor layer based on a preset linear temperature resistance influence function, the basic thermal efficiency per unit length of the outer layer, and the basic thermal efficiency per unit length of the inner layer, forming a set of basic thermal efficiency function sets; obtaining the heat generation rate per unit length of each conductor layer based on the basic thermal efficiency function and the preset skin effect coefficient; and constructing a radial temperature distribution thermal path model based on the heat generation rate per unit length of each conductor layer and the set of interlayer comprehensive contact thermal resistance.

[0049] In the specific implementation process, it is assumed that the steel core and aluminum layer wires are simulated as a simple parallel conductor structure. Based on the wire structure parameters such as the resistance per unit length of the outer conductor layer, the resistance per unit length of the inner conductor layer, and the number of conductor layers, a parallel wire simulation structure is constructed. Taking the wire under test, which includes m single-layer steel core layers and n aluminum layers, as an example, the following is obtained: Figure 4 The schematic diagram of the internal parallel circuit of the conductor under test shown includes an outer conductor layer parallel structure 1 and an inner conductor layer parallel structure 2. Among them, , Let A be the current flowing through the steel core layer resistor (i.e., the total current of the inner conductor layer) and the aluminum layer resistor (i.e., the total current of the outer conductor layer); , These represent the parallel resistance of the steel core conductor layer (i.e., the simulated total resistance of the inner conductor layer) and the parallel resistance of the aluminum conductor layer (i.e., the simulated total resistance of the outer conductor layer), respectively, in Ω / m; , These represent the resistance per unit length of the outer conductor layer and the inner conductor layer of the i-th layer, respectively, in Ω / m. It can also be expressed as the parallel resistance of the i-th layer, which consists of several single-wire aluminum conductors of unit length. This value can be calculated from the resistance of the aluminum conductor per unit length and the number of strands of the single-wire aluminum conductor in the i-th layer. Similarly, it can be calculated from the resistance per unit length of the steel conductor and the number of strands in the i-th layer of monofilament steel wire. After obtaining... and Afterwards, combined , The currents of the outer conductor layers corresponding to each of the aforementioned outer conductor layers can be calculated. and several inner conductor layer currents corresponding to each of the aforementioned inner conductor layers. .

[0050] Due to the skin effect and eddy current losses, an increase in resistance is introduced on top of the DC resistance of the conductor. To maintain the actual heat generation rate of the conductor, this embodiment incorporates a preset skin effect coefficient into the calculated heat generation rate of each conductor layer. Specifically: First, the heat generation rate Q per unit length is calculated using the basic thermal efficiency function corresponding to each conductor layer as follows: ; Where: d represents the conductor diameter, A represents the conductor cross-sectional area, A=πd² / 4, and ρ represents the conductor resistivity; Based on the above basic thermal efficiency function, the basic thermal efficiency function corresponding to each conductor layer is obtained by substituting the conductor diameter and conductor cross-sectional area corresponding to each conductor layer. The effect of temperature on resistivity is represented by a linear approximation, that is, the resistivity at temperature T is calculated using a preset linear temperature-resistivity influence function as shown in the following formula. : ; Where ρ is the resistivity at 20°C, α is the temperature coefficient of resistance, and T is the current temperature of the conductor; Because the skin effect in AC power transmission causes current to concentrate on the conductor surface, resulting in an increase in equivalent resistance, this embodiment introduces a preset skin effect coefficient k into the heat generation rate per unit length. The heat generation rate formula is as follows: ; Applying the above heat generation rate formula to the steel core and aluminum layer respectively, we obtain the following set of equations to calculate the heat generation rate per unit length for each conductor layer: ; in, , It refers to the diameter of single-wire steel conductors and single-wire aluminum conductors, in meters (m). , These are the heat generation rates per unit length of steel conductors and aluminum conductors after current is passed through them, respectively, in W / m2; , These represent the inner and outer conductor layer currents flowing through single-strand steel and aluminum conductors, respectively, in amperes (A). k is the preset skin effect coefficient for this type of conductor. , The resistivity of steel and aluminum conductors per unit length at 20°C is given in Ω / m. , These are the temperature coefficients of resistance for steel and aluminum conductors, respectively, in units of 1 / °C; , These are the operating temperatures of the steel core layer and the aluminum layer conductors, respectively, in 1°C.

[0051] Optionally, the step of constructing a radial temperature distribution thermal path model based on the heat generation rate per unit length of each conductor layer and the combined interlayer contact thermal resistance includes: Calculate the ambient thermal resistance based on the surface temperature of the conductor and the ambient temperature; A set of thermal circuit principle equations is constructed based on the interlayer integrated contact thermal resistance set, the ambient thermal resistance, and the heat generation rate per unit length of each conductor layer. The thermal circuit principle equations are recursively solved and transformed to construct a radial temperature distribution thermal circuit model.

[0052] In the specific implementation process, this embodiment treats each of the outer and inner conductor layers in the wire under test as an isothermal body, ignoring the small temperature differences between conductors within the same layer. Let the wire under test have n layers from the inside out, and the temperature of each layer be denoted as... , … In this embodiment, a solar radiation meter is also installed near the conductor under test to measure the solar radiation intensity in real time. The solar heat absorption power of the conductor under test is then calculated based on the surface absorptivity of the conductor. Based on this, establish as follows Figure 3 The radial temperature distribution thermal path model shown includes solar heat absorption power. Joule heating simulations of each conductor layer serve as distributed heat sources. (include , ... Interlayer integrated contact thermal resistance The resistance that reflects heat transfer, environmental thermal resistance Used to characterize convective and radiative heat transfer between the surface of a conductor and the external environment, among which Indicates ambient temperature. This refers to the surface temperature of the conductor. Based on the nodal voltage method in circuits, a reference node needs to be selected and its potential specified. The voltages of the other nodes are then the potential differences relative to the reference node. When solving the radial temperature distribution thermal circuit model of the conductor, a reference node also needs to be specified and assigned a corresponding temperature value. From the thermal circuit principle, the following set of thermal circuit principle equations can be obtained: ; in, , ... These represent the combined interlayer contact thermal resistances between the first and second layers, between the second and third layers, ..., and between the (n-1)th and nth layers of the conductor under test, respectively. The heat generated by the i-th conductor layer; By recursively solving and transforming the above thermal circuit principle equations, we obtain the temperature distribution equations for each layer as shown below: ; Finally, the equations in the above-mentioned temperature distribution equation set are superimposed and transformed to construct the radial temperature distribution thermal path model as shown in the following equation. .

[0053] In the solution process of step S4, according to the nodal method in the thermal circuit principle, that is, the temperature difference between adjacent layers is equal to the product of the total heat flow through the thermal resistance of that layer and the thermal resistance, starting from the known surface temperature of the conductor and the ambient temperature, the calculation is performed layer by layer inward. The specific recursive calculation process is shown in the following formula: ; Taking a three-strand conductor as an example, with the innermost layer being a steel core and the outer two layers being aluminum conductors, the above recursive calculation process can be further expanded as shown in the following formula: ; ; ; ; ; Through the above calculation and deduction process, this embodiment only needs to measure the surface temperature of the conductor and the ambient temperature to accurately deduce the complete real-time temperature across the conductor cross-section from the surface to the steel core. This enables real-time monitoring of the temperature from the surface of the conductor to the temperature of each internal layer of material.

[0054] In the specific implementation process, this embodiment uses fiber optic grating sensors or infrared temperature measuring devices deployed on the surface of the conductor to obtain the surface temperature of the conductor in real time.

[0055] Optionally, in step S5, the pre-construction process of the temperature-mechanical property degradation model includes: Prepare several monofilament samples corresponding to the conductor to be tested; For any single filament sample among the several single filament samples, the original performance test results are obtained based on the preset experimental parameters and the pre-built tensile test platform, and the material strength degradation coefficient is obtained based on the preset experimental parameters and the original performance test results, so as to construct a performance degradation relationship model based on the material strength degradation coefficient. A temperature-mechanical property degradation model is formed based on the performance degradation relationship models corresponding to several monofilament samples.

[0056] In the specific implementation process, this embodiment provides an experimental method to investigate the changes in the mechanical properties of several monofilament samples corresponding to the test conductor at different temperatures due to temperature variations during the pre-construction of the temperature-mechanical property degradation model. In this embodiment, the test conductor is an aluminum-clad steel core conductor, consisting of an inner steel core and an outer aluminum core. Therefore, the materials of the several monofilament samples corresponding to the test conductor include steel core, aluminum core, and aluminum-clad steel core. To quantify the influence of temperature on the mechanical properties of the conductor, this experimental method specifically involves conducting high-temperature tensile tests on steel core, aluminum core, and aluminum-clad steel core conductors to establish a temperature-mechanical property degradation model. Specifically: First, several monofilament samples corresponding to the test conductor are cut from the finished conductor. That is, 350mm strands are cut from conductors longer than 10m, the ends are fixed with crimped tubes, and the outer layer is peeled off to obtain monofilament samples with a length of 250mm (determined according to the national standard GB / T 4909.3-2009, Part 3: Tensile Test of Bare Wires). A tensile testing platform was constructed, comprising a steel frame, a tensioning structure, a heating unit (including steel braided straps and a high-current generator), a measurement unit (including a tension sensor, a video extensometer, and thermocouples), and a data acquisition and analysis system. The preset experimental parameters included ambient temperature and conductor tension. Since the conductor operating temperature does not exceed 80°C under normal operating conditions, room temperature (25°C) was selected as the baseline temperature to provide raw performance data at room temperature. Control temperatures of 80°C, 120°C, 180°C, and 250°C were also set to cover the conductor operating temperature range. Monofilament samples of the same material were taken from the same roll of finished conductor to ensure consistency. After measuring the actual diameter of the monofilament sample, both ends of the sample are mounted on a steel frame. An initial prestress is applied using a tensioning structure such as a tensile testing machine. A high-current generator in the heating unit applies a loading current to the steel woven bag, heating the monofilament sample to the target temperature and holding it at that temperature for at least 30 minutes, ensuring temperature fluctuations are ≤±2℃. Once the sample temperature stabilizes, the tension is controlled using the tensioning structure of the tensile testing platform, starting from the initial stress and continuing until the sample breaks. The measured tensile force data and the breaking force at the moment of breakage are recorded in real-time by the tensile sensor in the measuring unit, recording the tensile force change during the stretching process. The initial value of the extensometer corresponding to the initial stress and the measured values ​​during subsequent stretching are obtained using a video extensometer, recording the strain of the experimental monofilament. In this embodiment, the stretching rate is set to 25~100 mm / min. The initial stress was determined based on the nominal diameter of the monofilament sample according to GB / T 17937-2024 (i.e., the electrical test methods - attenuation constant test of coaxial communication cables, part 1-113 of the national standard) and GB / T 3428-2024 (i.e., the national standard for bare wires), as shown in Table 1 below: Table 1 Initial Stress Setting for Single Wire Samples Based on the principle that tensile strength is the ratio of breaking force to its actual cross-sectional area, the data acquisition and analysis system collects tensile force measurements for different materials and calculates the tensile strength using the measured diameter of the specimen before stress application and the measured breaking force. The specific calculation process is shown in the following formula: ; in, The tensile strength of a single filament (N / mm2); S is the measured breaking force (N); S is the measured area of ​​the single filament before stress is applied (mm2), which is based on the measured diameter of the sample.

[0057] Since the high-temperature strength degradation of metallic materials typically follows an exponential law, after obtaining the original performance experimental results including the tensile strength of a single filament at different temperatures, this embodiment combines the corresponding preset experimental parameters and uses nonlinear regression to establish a material strength degradation coefficient to construct a performance degradation relationship model, as shown in the following formula: ; in: Indicates reference temperature (Tensile strength of a single filament at room temperature) This represents the material strength degradation coefficient related to the material. Indicates the melting point or softening point of a material.

[0058] Finally, the performance degradation relationship models corresponding to all conductor materials are combined to form the temperature-mechanical property degradation model. This temperature-mechanical property degradation model can determine the thermo-mechanical coupling failure threshold of each material, providing input parameters for subsequent risk assessment.

[0059] Optionally, step S5 includes: The tensile strength of each conductor layer is obtained based on the real-time temperature of each conductor layer and the pre-constructed temperature-mechanical property degradation model. The cross-sectional area of ​​a single strand and the number of strands in each conductor layer are obtained from the conductor structure parameters, and the total cross-sectional area of ​​each conductor layer is calculated based on the cross-sectional area of ​​a single strand and the number of strands in each conductor layer. The ultimate bearing capacity of each conductor layer is obtained by multiplying its tensile strength and total cross-sectional area.

[0060] In the specific implementation process, the calculated real-time temperature corresponding to each conductor layer is substituted into the established bonding temperature-mechanical property degradation model to obtain the tensile strength of each layer at the corresponding temperature. Key mechanical parameters are used to achieve real-time calculations from surface temperature to the mechanical properties of each internal layer of material. The specific calculation process is shown in the following formula: ; in, Indicates reference temperature Tensile strength at room temperature Indicates the material strength degradation coefficient. Indicates the melting point or softening point of a material. This represents the real-time temperature corresponding to the i-th conductor layer.

[0061] When calculating the ultimate bearing capacity of each conductor layer by multiplying its tensile strength and total cross-sectional area, for the i-th layer, the real-time tensile strength of the material in the i-th layer is used as the basis for the calculation. and the total cross-sectional area of ​​this floor Calculate the ultimate bearing capacity of the i-th floor. : ; Among them, the total cross-sectional area It equals the cross-sectional area of ​​a single strand in the i-th layer multiplied by the number of strands in the i-th layer.

[0062] Optionally, step S7 includes: The safety margin for each conductor layer is calculated based on the ultimate bearing capacity of each conductor layer and the actual load shared by each conductor layer. When there is a safety margin of not less than a preset safety threshold in the safety margin corresponding to each conductor layer, it is determined that there is a conductor layer failure, and the risk assessment result of the test wire having a risk of breakage is output.

[0063] In the specific implementation process, the current real-time operating tension of the conductor is then considered, and the load is allocated according to the proportion of the remaining load-bearing capacity of each layer at the current temperature to obtain the actual tensile force borne by each layer, that is, the actual load-bearing capacity of each conductor layer. The specific calculation process is shown in the following formula: ; When calculating the safety margin for each conductor layer based on its ultimate bearing capacity and the actual shared load, the safety margin for the i-th layer is defined. The ratio of its actual load-bearing capacity to its ultimate bearing capacity is shown in the following formula: ; In this embodiment, the preset security threshold is set to 1. When When the value is ≥1, it indicates that the layer is in a state of failure.

[0064] For steel-cored aluminum stranded wire, the aluminum layer primarily bears the electrical load, while the steel core primarily bears the mechanical load. If the aluminum layer fails due to softening at high temperatures, the tension it bears will transfer to the steel core, potentially causing overload fracture. Load limiting, cooling, or maintenance measures should be taken promptly. The risk of breakage in overhead conductors depends on the relationship between the load-bearing capacity of its weakest layer and the actual load it receives. The outer aluminum conductor experiences significant strength degradation under high-temperature conditions, typically constituting the weakest link. When the safety margin of any conductor layer reaches or exceeds the preset failure threshold, conductor layer failure is determined. For example, if the outer conductor layer fails, it is determined that the layer has experienced strength failure due to softening at high temperatures. The original tension it bore is then transferred to the inner layer and the steel core, leading to a sudden increase in the stress level of the steel core and a risk of overload fracture. In this case, a risk assessment result should be immediately output and a graded warning should be triggered, prompting the implementation of load limiting, cooling, or maintenance measures.

[0065] In the specific implementation process, taking the steel-cored aluminum stranded wire of model JL / G1A-400 / 35 as an example, the conductor under test consists of a central steel core layer and three layers of aluminum stranded wire. Under a certain high-temperature and high-load operating condition, the total operating tension of the conductor is obtained as 28.5 kN through the aforementioned steps of this embodiment. The real-time temperatures of each conductor layer, from the outside to the inside, are 118℃, 102℃, 89℃, and 72℃, respectively. Substituting the real-time temperatures of each conductor layer into the pre-established monofilament performance degradation relationship model, the tensile strengths of the aluminum wires in each conductor layer, from the outside to the inside, are obtained as 152 MPa, 167 MPa, 181 MPa, and 189 MPa, respectively, and the tensile strength of the steel core is 1180 MPa. The ultimate bearing capacity is calculated based on the total cross-sectional area of ​​each conductor layer, and the total tension is distributed to each conductor layer according to the real-time stiffness ratio of each conductor layer to obtain the actual load-bearing capacity of each conductor layer. The safety margin of each conductor layer is calculated. The safety margin of the outermost aluminum wire is 1.08, which exceeds the preset safety threshold of 1. Therefore, the outermost aluminum wire is determined to have failed due to high-temperature softening. At this point, the tension originally borne by the outermost aluminum wire will transfer to the inner aluminum wire and steel core, and the stress level of the steel core will increase accordingly. Therefore, a breakage risk warning is immediately issued. A risk assessment result and a level one warning are output, indicating outer aluminum wire failure and suggesting current limiting or cooling measures to prevent steel core overload and breakage. If the operating conditions continue to deteriorate, and the safety margin of the second outermost aluminum wire also reaches 1, the second aluminum wire is determined to have failed. The current risk assessment result and a level two warning are output, indicating multiple aluminum wire failures and a significant increase in steel core load, suggesting immediate load reduction. When the safety margin of all aluminum layers exceeds the threshold and the steel core safety margin reaches 0.95, a level three warning is output, indicating that all aluminum layers have failed, the steel core is approaching its load-bearing limit, and there is a serious risk of wire breakage, requiring emergency power outage and maintenance. The output risk assessment results include the identified failure layer data and the current safety margin.

[0066] This embodiment provides a method for assessing the operational risk of conductors. Compared with traditional assessment methods that rely on empirical formulas or make holistic assumptions about the conductor, this method first conducts high-temperature tensile tests on steel-core, aluminum-core, and aluminum-clad steel-core monofilaments to obtain the mechanical property degradation laws of different materials under multiple temperature conditions. Based on this, a temperature-mechanical property degradation model of the conductor monofilament material is established, and a thermo-mechanical coupling failure threshold at the material level is constructed. This provides more accurate input parameters for subsequent operational risk assessment and effectively avoids assessment bias caused by ignoring the differences in performance degradation of different materials at high temperatures. Based on this, by establishing a radial temperature distribution thermal path model that considers the layered stranded structure of the conductor and the comprehensive contact thermal resistance between the layers, it is possible to accurately invert the real-time temperature of each structural layer inside the conductor using only the easily measurable surface temperature of the conductor and the ambient temperature. Furthermore, by substituting the real-time temperature of each conductor layer into the aforementioned temperature-mechanical property degradation model, the core mechanical parameters such as tensile strength and elastic modulus of each conductor layer under the current operating conditions can be mapped to obtain the core mechanical parameters. This achieves precise perception from easily measurable external parameters to the invisible mechanical state inside the conductor, significantly improving the depth and accuracy of overhead conductor condition monitoring. Furthermore, addressing the issue that existing risk assessment methods are mostly based on the overall mechanical parameters of the conductor and cannot identify the differentiated degradation behavior caused by radial temperature gradients, this embodiment proposes a fault-based fault risk assessment logic. This model defines a fault safety margin index by calculating the ultimate bearing capacity of each conductor layer at real-time temperature and its actual mechanical load share, and uses the weakest layer as the criterion for overall risk. This assessment logic more closely reflects the actual failure evolution process of steel-cored aluminum stranded wire under high-temperature operating conditions, significantly improving the accuracy and timeliness of fault risk warnings, and providing a more reliable scientific basis for dynamic capacity expansion scheduling and condition-based maintenance decisions of transmission lines.

[0067] Example 2: This embodiment provides a conductor operation risk assessment system, such as Figure 5 As shown, it includes: a data acquisition module, a temperature distribution analysis module, a performance parameter acquisition module, and a performance degradation analysis module; wherein: The data acquisition module is used to acquire the real-time line current, conductor surface temperature, real-time operating tension, conductor structural parameters, and ambient temperature of the conductor under test; wherein, the conductor under test includes several conductor layers; The temperature distribution analysis module is used to obtain the set of interlayer comprehensive contact thermal resistance based on the real-time operating tension and conductor structural parameters; to calculate the heat generation rate per unit length of each conductor layer based on the real-time line current, conductor structural parameters and preset skin effect coefficient; and to construct a radial temperature distribution thermal path model based on the heat generation rate per unit length of each conductor layer and the set of interlayer comprehensive contact thermal resistance; and to recursively calculate the real-time temperature of each conductor layer by inputting the conductor surface temperature and ambient temperature into the radial temperature distribution thermal path model. The performance parameter acquisition module is used to obtain the tensile strength of each conductor layer based on the real-time temperature of each conductor layer and the pre-built temperature-mechanical property degradation model, so as to calculate the ultimate bearing capacity of each conductor layer based on the tensile strength of each conductor layer and the conductor structure parameters. The performance degradation analysis module is used to obtain the actual load-sharing of each conductor layer based on the real-time operating tension; calculate the safety margin of each conductor layer based on the actual load-sharing of each conductor layer and the ultimate bearing capacity of each conductor layer; and output the risk assessment result of the conductor under test based on the safety margin and the preset safety threshold.

[0068] It should be noted that the system embodiments described above are merely illustrative, and some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Furthermore, in the accompanying drawings of the system embodiments provided by this invention, the connection relationships between modules indicate that they have communication connections, which can be specifically implemented as one or more communication buses or signal lines. Those skilled in the art can understand and implement this without any creative effort.

[0069] Example 3: like Figure 6 As shown, based on the above-described method embodiments, this embodiment provides a complete process for assessing the operational risks of conductors, specifically including: S61. Construct a temperature-mechanical property degradation model: Conduct high-temperature tensile tests to obtain the material strength degradation coefficient, and establish a performance degradation relationship model based on this.

[0070] S62. Construction and Solution of Radial Temperature Distribution Thermal Circuit Model: During the actual operation evaluation phase, the real-time line current, surface temperature, operating tension, structural parameters, and ambient temperature of the conductor are obtained. Based on the operating tension and structural parameters, the interlayer comprehensive contact thermal resistance between adjacent conductor layers is calculated. At the same time, based on the line current, structural parameters, and skin effect coefficient, the heat generation rate per unit length corresponding to each conductor layer is calculated, thereby constructing a radial temperature distribution thermal circuit model. The conductor surface temperature and ambient temperature are then input into this thermal circuit model for recursive solution to obtain the real-time temperature distribution of each structural layer inside the conductor.

[0071] S63. Conductor Delamination Failure Risk Assessment: The real-time temperature distribution is substituted into a temperature-mechanical property degradation model to obtain the tensile strength corresponding to each conductor layer. The ultimate bearing capacity of each conductor layer is calculated based on its total cross-sectional area. The total operating tension is then distributed according to the real-time stiffness ratio of each conductor layer to obtain the actual load-bearing capacity of each layer. Finally, the safety margin for each conductor layer is calculated, and the risk assessment result is output based on the delamination failure criterion.

[0072] Example 4: Based on the above-described embodiment of conductor operation risk assessment, another embodiment of the present invention provides a terminal device, which includes a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, it implements a conductor operation risk assessment according to any embodiment of the present invention.

[0073] For example, in this embodiment, the computer program can be divided into one or more modules, which are stored in the memory and executed by the processor to complete the present invention. The one or more modules may be a series of computer program instruction segments capable of performing a specific function, which describe the execution process of the computer program in the terminal device.

[0074] The terminal device may be a desktop computer, laptop, handheld computer, or cloud server, etc. The terminal device may include, but is not limited to, a processor and a memory.

[0075] The processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor can be a microprocessor or any conventional processor. The processor is the control center of the terminal device, connecting all parts of the terminal device via various interfaces and lines.

[0076] Example 5: Based on the above-described method embodiments, another embodiment of the present invention provides a computer-readable storage medium including a stored computer program, wherein, when the computer program is executed, it controls the device where the computer-readable storage medium is located to perform a conductor operation risk assessment as described in any of the above-described method embodiments of the present invention.

[0077] The modules / units integrated in the device / terminal equipment, if implemented as software functional units and sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the above embodiments of the present invention can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying the computer program code, a recording medium, a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electrical carrier signal, a telecommunication signal, and a software distribution medium, etc.

[0078] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for assessing the operational risk of conductors, characterized in that, include: The system acquires real-time line current, conductor surface temperature, real-time operating tension, conductor structural parameters, and ambient temperature of the conductor under test; wherein the conductor under test comprises several conductor layers. The set of interlayer comprehensive contact thermal resistance is obtained based on the real-time operating tension and conductor structure parameters. Based on the real-time line current, conductor structure parameters and preset skin effect coefficient, calculate the heat generation rate per unit length of each conductor layer, and construct a radial temperature distribution thermal path model based on the heat generation rate per unit length of each conductor layer and the set of interlayer comprehensive contact thermal resistance. The surface temperature of the conductor and the ambient temperature are input into the radial temperature distribution thermal path model for recursive calculation to obtain the real-time temperature corresponding to each conductor layer. The tensile strength of each conductor layer is obtained based on the real-time temperature and the pre-built temperature-mechanical property degradation model, and the ultimate bearing capacity of each conductor layer is calculated based on the tensile strength of each conductor layer and the wire structure parameters. The actual load-sharing of each conductor layer is obtained based on the real-time operating tension. The safety margin of each conductor layer is calculated based on the actual load-sharing and the ultimate bearing capacity of each conductor layer. The risk assessment result of the conductor under test is then output based on the safety margin and the preset safety threshold.

2. The method for assessing the operational risk of a conductor as described in claim 1, characterized in that, The process of obtaining the set of interlayer comprehensive contact thermal resistance based on the real-time operating tension and conductor structure parameters includes: For each adjacent conductor layer in the conductor under test, a contact thermal resistance calculation is performed to obtain an interlayer comprehensive contact thermal resistance set including the total interlayer contact thermal resistance of all adjacent conductor layers; the adjacent conductor layers include inner conductor layers and outer conductor layers; wherein, the contact thermal resistance calculation includes: The number of single conductors corresponding to the inner conductor layer, the pitch of the inner conductor layer, and the pitch of the outer conductor layer are obtained from the conductor structure parameters. The number of contact points per unit length is obtained based on the number of single conductors, the pitch of the inner conductor layer, and the pitch of the outer conductor layer. The total radial stress of the inner conductor layer is obtained based on the real-time operating tension, and the radial pressure of the contact point corresponding to the inner conductor layer is obtained based on the total radial stress of the conductor layer. Obtain the thermal conductivity coefficient of metal point contact, the thermal conductivity coefficient of contact gap, and the thermal conductivity coefficient of air pores; Based on the thermal conductivity coefficient of the metal point contact, the thermal conductivity coefficient of the contact gap, the thermal conductivity coefficient of the air pore, and the radial pressure of the contact point, the corresponding thermal resistance of the metal point contact, the thermal resistance of the contact gap, and the thermal resistance of the air pore contact are calculated respectively. The interlayer comprehensive contact thermal resistance is obtained by calculating the parallel resistance based on the metal point contact thermal resistance, contact gap contact thermal resistance and air pore contact thermal resistance. The interlayer composite contact thermal resistance is taken as the interlayer composite contact thermal resistance corresponding to the adjacent conductor layer.

3. The method for assessing the operational risk of a conductor as described in claim 2, characterized in that, The calculation of the heat generation rate per unit length for each conductor layer based on the real-time line current, conductor structure parameters, and a preset skin effect coefficient, and the construction of a radial temperature distribution thermal path model based on the heat generation rate per unit length for each conductor layer and the combined interlayer contact thermal resistance, includes: The conductor layer current corresponding to each conductor layer is obtained based on the real-time line current and conductor structure parameters. The basic thermal efficiency per unit length of each conductor layer is obtained based on the conductor layer current corresponding to each conductor layer. The basic thermal parameter function for each conductor layer is constructed based on the basic thermal parameter per unit length for each conductor layer and the preset linear temperature resistance influence function. The heat generation rate per unit length of each conductor layer is obtained based on the basic thermal efficiency function corresponding to each conductor layer and the preset skin effect coefficient. A radial temperature distribution thermal path model is constructed based on the heat generation rate per unit length of each conductor layer and the combined interlayer contact thermal resistance.

4. The method for assessing the operational risk of a conductor as described in claim 3, characterized in that, The process of obtaining the conductor layer current corresponding to each conductor layer based on the real-time line current and conductor structure parameters includes: Based on the aforementioned conductor structure parameters, construct several parallel conductor simulation structures corresponding to the conductor layers; The resistance per unit length for each conductor layer is obtained from the aforementioned conductor structure parameters; The conductor layer current corresponding to each conductor layer is obtained based on the real-time line current, the unit length resistance of each conductor layer, and the parallel conductor simulation structure.

5. The method for assessing the operational risk of a conductor as described in claim 3, characterized in that, The radial temperature distribution thermal path model, constructed based on the heat generation rate per unit length of each conductor layer and the combined interlayer contact thermal resistance, includes: Calculate the ambient thermal resistance based on the surface temperature of the conductor and the ambient temperature; A set of thermal circuit principle equations is constructed based on the interlayer integrated contact thermal resistance set, the ambient thermal resistance, and the heat generation rate per unit length of each conductor layer. The thermal circuit principle equations are recursively solved and transformed to construct a radial temperature distribution thermal circuit model.

6. The method for assessing the operational risk of a conductor as described in claim 1, characterized in that, In obtaining the tensile strength of each conductor layer based on the real-time temperature and a pre-built temperature-mechanical property degradation model, and calculating the ultimate bearing capacity of each conductor layer based on the tensile strength and the conductor structure parameters, the pre-construction process of the temperature-mechanical property degradation model includes: Prepare several monofilament samples corresponding to the conductor to be tested; For any single filament sample among the several single filament samples, the original performance test results are obtained based on the preset experimental parameters and the pre-built tensile test platform, and the material strength degradation coefficient is obtained based on the preset experimental parameters and the original performance test results, so as to construct a performance degradation relationship model based on the material strength degradation coefficient. A temperature-mechanical property degradation model is formed based on the performance degradation relationship models corresponding to several monofilament samples.

7. The method for assessing the operational risk of a conductor as described in claim 1, characterized in that, The tensile strength of each conductor layer is obtained based on the real-time temperature and a pre-constructed temperature-mechanical property degradation model. The ultimate bearing capacity of each conductor layer is then calculated based on its tensile strength and the conductor structure parameters, including: The tensile strength of each conductor layer is obtained based on the real-time temperature of each conductor layer and the pre-constructed temperature-mechanical property degradation model. The cross-sectional area of ​​a single strand and the number of strands in each conductor layer are obtained from the conductor structure parameters, and the total cross-sectional area of ​​each conductor layer is calculated based on the cross-sectional area of ​​a single strand and the number of strands in each conductor layer. The ultimate bearing capacity of each conductor layer is obtained by multiplying its tensile strength and total cross-sectional area.

8. The method for assessing the operational risk of a conductor as described in claim 2, characterized in that, The process of calculating the safety margin of each conductor layer based on the actual load-sharing and ultimate bearing capacity of each conductor layer, and outputting the risk assessment result of the conductor under test based on the safety margin and a preset safety threshold, includes: The safety margin for each conductor layer is calculated based on the ultimate bearing capacity of each conductor layer and the actual load shared by each conductor layer. When there is a safety margin of not less than a preset safety threshold in the safety margin corresponding to each conductor layer, it is determined that there is a conductor layer failure, and the risk assessment result of the test wire having a risk of breakage is output.

9. A conductor operation risk assessment system, characterized in that, include: The module includes a data acquisition module, a temperature distribution analysis module, a performance parameter acquisition module, and a performance degradation analysis module; among which: The data acquisition module is used to acquire the real-time line current, conductor surface temperature, real-time operating tension, conductor structural parameters, and ambient temperature of the conductor under test; wherein, the conductor under test includes several conductor layers; The temperature distribution analysis module is used to obtain the set of interlayer comprehensive contact thermal resistance based on the real-time operating tension and conductor structural parameters; to calculate the heat generation rate per unit length of each conductor layer based on the real-time line current, conductor structural parameters and preset skin effect coefficient; and to construct a radial temperature distribution thermal path model based on the heat generation rate per unit length of each conductor layer and the set of interlayer comprehensive contact thermal resistance; and to recursively calculate the real-time temperature of each conductor layer by inputting the conductor surface temperature and ambient temperature into the radial temperature distribution thermal path model. The performance parameter acquisition module is used to obtain the tensile strength of each conductor layer based on the real-time temperature of each conductor layer and the pre-built temperature-mechanical property degradation model, so as to calculate the ultimate bearing capacity of each conductor layer based on the tensile strength of each conductor layer and the conductor structure parameters. The performance degradation analysis module is used to obtain the actual load-sharing of each conductor layer based on the real-time operating tension; calculate the safety margin of each conductor layer based on the actual load-sharing of each conductor layer and the ultimate bearing capacity of each conductor layer; and output the risk assessment result of the conductor under test based on the safety margin and the preset safety threshold.

10. A terminal device, characterized in that, The device includes a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein when the processor executes the computer program, it implements a conductor operation risk assessment method as described in any one of claims 1-8.

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