Single-core cable contact resistance inversion method and system

Abstract

The invention discloses a single-core cable contact resistance inversion method and system. The method comprises the following steps: acquiring first temperature data and second temperature data of a target cable; establishing a first mapping relation between the second temperature data and the first temperature data to obtain a first inversion model; obtaining first joint equivalent thermal resistance based on the first inversion model; and presetting a first constraint condition, and obtaining the contact resistance of the target cable joint in combination with the first joint equivalent thermal resistance. The contact resistance state of the cable joint can be effectively monitored and evaluated, so that the real-time monitoring of the operation state of the cable is realized. Through accurate temperature data acquisition and establishment of an inversion model, the system can carry out early warning on potential faults of the cable joint, and the problem of overheating caused by overlarge contact resistance is avoided, so that the safety and reliability of cable operation are improved. The method provides powerful technical support for healthy operation of the cable, and has remarkable practical value and market application prospect.

Description

Technical Field

[0001] The invention relates to the technical field of single-core cable contact resistance inversion, and in particular to a single-core cable contact resistance inversion method and system. Background Art

[0002] With the rapid growth of the national economy, the electricity consumption of commerce, enterprises and residents has increased linearly. As the "blood vessels" and "meridians" of the power grid, the operating status and health of power cables are directly related to the safe and stable operation of the distribution network. Cable joints are important accessories in the cable system, connecting the circuits at both ends into a whole to ensure the integrity of power transmission. However, the cable joints are prone to high temperatures due to defects, resulting in severe heating and failures, and heating failures will also reduce the service life of the cable joints. The cable joints will be coupled with the temperature field and the electric field in the electric field. The temperature rise may cause power system failures and lead to insulation breakdown. In power cable temperature failures, cable defects are the main cause of cable joint temperature failures.

[0003] Temperature is one of the decisive factors affecting the insulation performance and service life of cable joints. In actual operation, the conductor is often the highest temperature point of the insulation material. The cable core temperature value cannot exceed the long-term tolerance temperature of the insulation material (usually 90°C) to ensure the life of the cable. Studies have shown that once the conductor temperature exceeds this limit, it will accelerate the aging of the cable, and even cause thermal breakdown due to local overheating, causing power outages. When the long-term operating temperature of the XLPE cable exceeds 8% of the allowable value, its life will be halved; if it exceeds 15%, the cable life will only be 1 / 4. In addition, actual measurements show that due to the presence of a thicker insulation layer and contact resistance, the conductor temperature of the cable joint is often much higher than the cable body, which is the bottleneck of cable thermal aging and needs to be paid special attention to.

[0004] The conductor is wrapped inside the joint, and the degree of heat is closely related to the current, which is hidden and latent to a certain extent. Traditional monitoring methods have blind spots. Therefore, it is of great engineering significance to deeply explore the perception method of the heating state inside the intermediate joint of the cable, conduct online detection of the hot spot temperature, evaluate the contact state of the conductor, and realize early warning of overheating faults. Summary of the invention

[0005] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0006] In view of the above existing problems, the present invention is proposed.

[0007] Therefore, the present invention provides a single-core cable contact resistance inversion method and system, which can solve the problems mentioned in the background technology.

[0008] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0009] In a first aspect, the present invention provides a single-core cable contact resistance inversion method, comprising:

[0010] Acquire first temperature data and second temperature data of the target cable;

[0011] Establishing a first mapping relationship between the second temperature data and the first temperature data to obtain a first inversion model;

[0012] Based on the first inversion model, obtaining an equivalent thermal resistance of a first joint;

[0013] A first constraint condition is preset, and a target cable joint contact resistance is obtained in combination with the first joint equivalent thermal resistance.

[0014] As a preferred solution of the single-core cable contact resistance inversion method of the present invention, wherein: the first inversion model includes:

[0015] The first inversion model is an arbitrary model established according to the first mapping relationship;

[0016] The input of the first inversion model is first temperature data, and the output is second temperature data.

[0017] As a preferred solution of the single-core cable contact resistance inversion method described in the present invention, the first constraint condition includes at least one heat dissipation condition and one crimping condition.

[0018] As a preferred solution of the single-core cable contact resistance inversion method described in the present invention, wherein: the preset first constraint condition, combined with the first joint equivalent thermal resistance, obtains the target cable joint contact resistance, including:

[0019] Establishing a first equivalent thermal circuit model based on a first constraint condition;

[0020] Calculating the convection heat transfer coefficient according to the first equivalent heat circuit model;

[0021] The target cable joint contact resistance is obtained according to the convection heat transfer coefficient and the first joint equivalent thermal resistance.

[0022] As a preferred solution of the single-core cable contact resistance inversion method of the present invention, wherein: based on the first inversion model, obtaining the first joint equivalent thermal resistance includes:

[0023] The first joint equivalent thermal resistance is obtained by the inversion value of the first inversion model at the corresponding moment, the conductor load current, the conductor resistance of the joint part and the ambient temperature;

[0024] The ambient temperature is the stable ambient temperature of the joint resistor without wind, rain or sunshine.

[0025] As a preferred solution of the single-core cable contact resistance inversion method described in the present invention, the step of obtaining the target cable joint contact resistance according to the convection heat transfer coefficient combined with the first joint equivalent thermal resistance includes:

[0026] Establishing a functional relationship between the convection heat transfer coefficient, the equivalent thermal resistance of the first joint, and the contact resistance coefficient of the target cable joint;

[0027] The contact resistance coefficient of the target cable joint in the functional relationship is solved by the convection heat transfer coefficient and the equivalent thermal resistance of the first joint;

[0028] The target cable joint contact resistance is obtained according to the target cable joint contact resistance coefficient.

[0029] As a preferred solution of the single-core cable contact resistance inversion method of the present invention, the obtaining of the first temperature data and the second temperature data of the target cable comprises:

[0030] The first temperature data and the second temperature data of the target cable are obtained by establishing a temperature field simulation model of the target cable intermediate joint and the body.

[0031] In a second aspect, the present invention provides a single-core cable contact resistance inversion system, comprising:

[0032] A data acquisition module, used to acquire first temperature data and second temperature data of a target cable;

[0033] A model building module, used to establish a first mapping relationship between the second temperature data and the first temperature data to obtain a first inversion model;

[0034] A first calculation module, used for obtaining an equivalent thermal resistance of a first joint based on the first inversion model;

[0035] The second calculation module is used to preset a first constraint condition and obtain a target cable joint contact resistance in combination with the first joint equivalent thermal resistance.

[0036] In a third aspect, the present invention provides a computer device, comprising a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the above-mentioned method when executing the computer program.

[0037] In a fourth aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program implements the steps of the method described above when executed by a processor.

[0038] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention proposes a single-core cable contact resistance inversion method and system, which obtains the first temperature data and the second temperature data of the target cable; establishes a first mapping relationship between the second temperature data and the first temperature data to obtain a first inversion model; based on the first inversion model, obtains the first joint equivalent thermal resistance; presets a first constraint condition, and obtains the target cable joint contact resistance in combination with the first joint equivalent thermal resistance. It can effectively monitor and evaluate the contact resistance state of the cable joint, thereby realizing real-time monitoring of the cable operation state. Through accurate temperature data collection and the establishment of an inversion model, the system can warn of potential faults of the cable joint, avoid overheating problems caused by excessive contact resistance, and thus improve the safety and reliability of cable operation. The present application provides strong technical support for the healthy operation of cables, and has significant practical value and market application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0040] Figure 1 A method flow chart of a single-core cable contact resistance inversion method and system provided by an embodiment of the present invention;

[0041] Figure 2 A detailed method flow chart of a single-core cable contact resistance inversion method and system provided by an embodiment of the present invention;

[0042] Figure 3 A schematic diagram of an inversion model of a single-core cable contact resistance inversion method and system provided by an embodiment of the present invention;

[0043] Figure 4 A cable body steady-state thermal circuit model diagram of a single-core cable contact resistance inversion method and system provided by an embodiment of the present invention;

[0044] Figure 5 An internal structural diagram of a computer device of a single-core cable contact resistance inversion method and system provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0045] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0046] Example 1

[0047] Reference Figure 1-Figure 5 , which is the first embodiment of the present invention, provides a single-core cable contact resistance inversion method and system, including:

[0048] There are some problems in the existing related technologies, such as increased resistance caused by poor contact of cable joints, which may cause overheating of the cable during operation and may even cause safety accidents such as fire.

[0049] The present application provides a method that can effectively solve the above-mentioned problems. Next, multiple embodiments will be combined to explain in detail how to implement the single-core cable contact resistance inversion method;

[0050] Figure 1 A method flow chart of a single-core cable contact resistance inversion method and system is shown, including:

[0051] S101, obtaining first temperature data and second temperature data of a target cable;

[0052] In an optional embodiment, the second temperature data is the temperature data at the contact resistance joint of the cable joint to be tested, and the first temperature data may be data at other locations, such as the surface temperature data of the cable to be tested, the temperature data of the cable body, etc.

[0053] In an optional embodiment, temperature data within a fixed range or a temperature without a fixed range can be selected, and the temperature when the cable is running or not running can also be selected. Relevant technical personnel can make corresponding designs according to actual needs. Because it is necessary to find the relationship from the first temperature data to the second temperature data, the second temperature data in the present application must be the temperature data at the contact resistance joint of the cable joint to be tested, but there is no restriction on the first temperature data. In theory, no matter it is the surface temperature data of the cable to be tested, the temperature data of the cable body, or the data at other locations, as long as the temperature data at a position physically associated with the intermediate joint can be used as the first temperature data for the operation of this application.

[0054] In an optional embodiment, the first temperature data and the second temperature data may be obtained in a variety of ways, such as using a thermocouple, an infrared sensor or other temperature sensing devices, which can provide continuous temperature readings to ensure the real-time and accuracy of the data.

[0055] In an optional embodiment, the first temperature data and the second temperature data may also be obtained through a cable operation status monitoring system, which can monitor the temperature change of the cable in real time and transmit the data to the data acquisition module.

[0056] In an embodiment of the present application, obtaining the first temperature data and the second temperature data of the target cable includes:

[0057] The first temperature data and the second temperature data of the target cable are obtained by establishing a temperature field simulation model of the target cable intermediate joint and the body.

[0058] In an embodiment of the present application, by setting different boundary conditions for the target cable intermediate joint and body temperature field simulation model, namely, the ambient temperature and the cable surface convection heat transfer coefficient and different contact resistance values, the intermediate joint hotspot temperature (second temperature data) and the surface temperature measurement point temperature data (first temperature data) are obtained, and an inversion model sample set is constructed.

[0059] It should be noted that the target cable intermediate joint and body temperature field simulation model can be simulated by computational fluid dynamics (CFD) software to ensure the accuracy and reliability of the model. In this way, the temperature distribution of the cable under different working conditions can be simulated, thereby providing the necessary data support for the inversion model.

[0060] It should be noted that obtaining the first temperature data and the second temperature data of the target cable can provide a solid foundation for obtaining the following first mapping relationship.

[0061] S102, establishing a first mapping relationship between the second temperature data and the first temperature data to obtain a first inversion model;

[0062] In the embodiment of the present application, the first inversion model includes:

[0063] The first inversion model is an arbitrary model established according to the first mapping relationship;

[0064] The input of the first inversion model is the first temperature data, and the output is the second temperature data.

[0065] In an optional embodiment, the first mapping relationship can be established by a machine learning algorithm, such as a support vector machine (SVM), a neural network or a regression analysis, etc. Through the training data set, these algorithms can learn the complex relationship between the first temperature data and the second temperature data, and build a model that can accurately predict the second temperature data.

[0066] In an optional embodiment, the first mapping relationship can also be established by a statistical analysis method, such as a multivariate linear regression analysis. This method can determine a mathematical model between the first temperature data and the second temperature data by analyzing the statistical relationship between the two, thereby realizing the prediction of the second temperature data.

[0067] In an optional embodiment, the first mapping relationship can also be established by an analysis method based on a physical model. For example, the thermal conduction equation and boundary conditions of the cable can be used to simulate the temperature distribution of the cable through a numerical calculation method (such as a finite difference method, a finite element method, etc.), thereby obtaining a mapping relationship between the first temperature data and the second temperature data. This method can provide a more accurate physical basis and help improve the accuracy of the inversion model.

[0068] In the embodiment of the present application, an extreme learning machine (ELM) algorithm is used to construct a first inversion model, which can also be referred to as a cable intermediate joint hot spot temperature inversion model in the present application. ELM is a fast and effective single-layer feedforward neural network that can be used to solve regression and classification problems. Its principle is to train the network by solving the pseudo-inverse solution of the output weight under the condition of randomly generated input weights and biases. This method avoids the cumbersome back propagation algorithm in traditional neural networks, thereby improving training speed and efficiency.

[0069] Specifically, for a training data set X, the input of each sample is x(i) and the output is y(i). Assume that X has n samples, each sample has m inputs and h output categories. The goal of ELM is to learn the function so that f(x) is as close to y as possible. The specific steps are as follows:

[0070] Randomly generate input weights w and bias b, and calculate the hidden layer output Y;

[0071] Y=G(Xw+b)

[0072] In an optional embodiment, a pseudo-inverse solution is used to obtain the output weight β;

[0073] β=pinv(Y)O

[0074] Where β is the output weight, O is the n×h output matrix, and pinv(Y) represents the pseudo-inverse of Y.

[0075] In an optional embodiment, for a new input sample, the output of the ELM is solved by the following equation:

[0076] f(x)=G(xw+b)

[0077] Among them, G is the sigmoid function.

[0078] In an alternative embodiment, it is possible to establish Figure 3 The hot spot temperature inversion model of the cable intermediate joint shown in this figure has a two-layer neural network model, which includes two sub-models (labeled as "sub-model 1" and "sub-model 2") and a main model (labeled as "secondary model"). The following is a specific description: Sub-model 1: Input: skin temperature T b1 ; Output: Cable core temperature T l1 ; Submodel 2: Input: skin temperature T b2 Output: Cable core temperature T l2 ; Both sub-models are radial inversion models, and their function is to estimate the cable core temperature based on different measured values ​​of the skin temperature. It is worth noting that although their inputs and outputs look the same, they may actually be based on different data sets or use different algorithms to complete this task. The secondary model is a radial inversion model, and the secondary model is an axial inversion model. Secondary model: Input: Output of sub-model 1 and sub-model 2 (cable core temperature T l1 、T l1 ) Output: Joint temperature T j ; This secondary model is called the axial inversion model, and its main responsibility is to further infer the true temperature of the joint after receiving the cable core temperature estimates provided by the two sub-models. This means that it not only relies on directly observed skin temperature data, but also needs to take into account changes in cable core temperature to give the most accurate answer. This figure shows the design concept of a hierarchical neural network, in which each layer has a clear functional division of labor: the underlying sub-model focuses on learning local features, while the high-level main model is responsible for integrating this local information to make global judgments. Such an architecture helps to improve the overall generalization and robustness of the model, enabling it to perform well in complex and changing application scenarios.

[0079] It should be noted that by establishing the first mapping relationship of the second temperature data to the first temperature data and obtaining the first inversion model, the relationship of the second temperature data with respect to the first temperature data can be obtained, thereby finding the key point where the first temperature data affects the second temperature data, which can provide an important reference basis for the subsequent calculation of the equivalent thermal resistance of the first joint.

[0080] S103, obtaining a first joint equivalent thermal resistance based on a first inversion model;

[0081] In an optional embodiment, there are many ways to obtain the equivalent thermal resistance of the first joint, for example, it can be directly measured by a thermal resistance tester, or calculated by the current and voltage data of the cable. The thermal resistance tester can directly measure the thermal resistance value of the cable joint, while the calculation by current and voltage data needs to be based on the relationship between the power loss and temperature rise of the cable. In practical applications, which method to choose depends on the site conditions and the convenience of measurement.

[0082] In the embodiment of the present application, based on the first inversion model, obtaining the first joint equivalent thermal resistance includes:

[0083] The first joint equivalent thermal resistance is obtained by the inversion value of the first inversion model at the corresponding moment, the conductor load current, the conductor resistance of the joint part and the ambient temperature;

[0084] The ambient temperature is the stable ambient temperature of the joint resistor without wind, rain or sunshine.

[0085] In an embodiment of the present application, based on the first inversion model trained by the above-mentioned extreme learning machine, the cable surface temperature is used as input, and the hot spot temperature value of the cable intermediate joint under different heat dissipation conditions and crimping conditions is inverted, and the contact resistance of the intermediate joint is identified based on this.

[0086] In the embodiment of the present application, the contact resistance is characterized by the inversion result of the hot spot temperature under steady state: Assuming that in an ideal situation, the conductor load current is I, the conductor resistance of the joint part is R, the joint resistance is free of wind, rain and sunshine, and the ambient temperature is stable at T e At this time, the inversion value of the joint hot spot temperature is T ij , then define the joint equivalent thermal resistance θ ij for:

[0087]

[0088] Obviously, under the condition that the joint structure is fixed, θ ij The contact resistance R can be uniquely determined ij .

[0089] It should be noted that obtaining the equivalent thermal resistance of the first joint can provide an important reference for calculating the contact resistance of the target cable joint described below. In this way, the thermal performance of the cable joint can be evaluated more accurately, and the overall health of the cable system can be monitored and managed.

[0090] S104, presetting a first constraint condition, and obtaining a target cable joint contact resistance in combination with the first joint equivalent thermal resistance.

[0091] In the embodiment of the present application, the first constraint condition includes at least one heat dissipation condition and one crimping condition.

[0092] In an optional embodiment, the heat dissipation conditions may include factors such as ambient temperature, wind speed, and sunlight intensity, while the crimping conditions involve the physical contact state of the connector, such as contact area, contact pressure, etc. For example, specifically, the heat dissipation conditions may be that the ambient temperature is between 20°C and 30°C, the wind speed does not exceed 3m / s, and the sunlight intensity is less than 500W / m2. The crimping conditions may be that the contact area is not less than 100mm2 and the contact pressure is between 50N and 100N. These conditions are set to ensure that in actual applications, the thermal performance evaluation of the cable connector is carried out in a relatively stable and controllable environment, thereby improving the accuracy and reliability of the evaluation results.

[0093] In the embodiment of the present application, there is no restriction on the first constraint condition, and at least one may be randomly selected or several may be specified by relevant technical personnel, but it must at least include one heat dissipation condition and one crimping condition.

[0094] It should be noted that by setting these constraints, the heat conduction and heat exchange process of the cable joint in actual work can be simulated, so as to more accurately calculate the target cable joint contact resistance. The preset constraints will be used to optimize the output of the inversion model to ensure that the obtained contact resistance value can truly reflect the performance of the cable joint under a specific working environment. In practical applications, the setting of these constraints needs to be determined according to the use environment of the cable and the physical properties of the cable itself to ensure the accuracy and applicability of the model. In this way, the health of the cable joint can be effectively monitored and potential failures can be prevented, thereby ensuring the stable operation of the entire power system.

[0095] In the embodiment of the present application, the first constraint condition is preset, and the target cable joint contact resistance is obtained in combination with the first joint equivalent thermal resistance, including:

[0096] Establishing a first equivalent thermal circuit model based on a first constraint condition;

[0097] Calculating the convection heat transfer coefficient according to the first equivalent heat circuit model;

[0098] The target cable joint contact resistance is obtained according to the convection heat transfer coefficient and the equivalent thermal resistance of the first joint.

[0099] In an embodiment of the present application, obtaining the target cable joint contact resistance according to the convection heat transfer coefficient combined with the first joint equivalent thermal resistance includes:

[0100] Establishing a functional relationship between the convection heat transfer coefficient, the equivalent thermal resistance of the first joint, and the contact resistance coefficient of the target cable joint;

[0101] The contact resistance coefficient of the target cable joint in the functional relationship is solved by the convection heat transfer coefficient and the equivalent thermal resistance of the first joint;

[0102] The target cable connector contact resistance is obtained according to the target cable connector contact resistance coefficient.

[0103] In an optional embodiment, the first equivalent thermal circuit model may use the π-type equivalent thermal circuit model recommended by IEC 60853, and may also use other equivalent thermal circuit models, such as T-type or H-type equivalent thermal circuit models, to adapt to different cable structures and working conditions. The π-type equivalent thermal circuit model recommended by IEC 60853 is designed based on the physical structure and thermal conductivity characteristics of the cable, and it can provide a simplified thermal circuit network to simulate the thermal behavior of the cable in actual work. Through such a model, the thermal resistance value of the cable joint under specific heat dissipation and crimping conditions can be calculated, and then the contact resistance can be derived.

[0104] In the embodiment of the present application, the π-type equivalent thermal circuit model recommended by IEC 60853 is used to calculate the corresponding conductor temperature according to the surface temperature. The radial transient thermal circuit of the cable body is simplified to obtain a steady-state thermal circuit model as follows: Figure 4 shown.

[0105] According to the above Figure 4 Thermal circuit model, air thermal resistance R k It can be expressed as:

[0106]

[0107] Where I is the current, A; R is the resistance of the conductor core per unit length, Ω; T e is the external environment temperature, ℃; T s is the outer sheath surface temperature, ℃.

[0108] In the embodiment of the present application, the air thermal resistance is the convection thermal resistance between the outer sheath and the air, and the expression can be written as:

[0109]

[0110] Where: h is the convective heat transfer coefficient, W / (m 2 ·K); A is the surface area of ​​the outer sheath of the body per unit length, m 2 .

[0111] In the embodiment of the present application, the convective heat transfer coefficient h can be expressed as:

[0112]

[0113] The above formula indicates that in actual operation, the convective heat transfer coefficient value can be effectively identified by load current, surface temperature and ambient temperature. This value comprehensively reflects the impact of external environmental factors on cable heat exchange.

[0114] In the embodiment of the present application, according to θ ij The contact resistance of the cable middle joint is inverted by the value of . Obviously, when the heat dissipation condition on the cable surface is constant, the equivalent thermal resistance θ of the joint is ij With contact resistance R ij There is a one-to-one correspondence. Considering the contact resistance coefficient k, the convection heat transfer coefficient h and the joint equivalent thermal resistance θ ij The three-factor multi-level orthogonal table is used as the training sample set to establish the three-way relationship, and the contact resistance coefficient k and the equivalent contact thermal resistance θ under different convective heat transfer coefficients h are obtained respectively. ij The functional relationship between them is finally found to have a good linear relationship between them. a and b in the following formula represent function fitting coefficients, which have no specific meaning and are related to the convective heat transfer coefficient h:

[0115] k=a·θ ij +b

[0116] Under different convective heat transfer coefficients h, the contact resistance coefficient k and the equivalent contact thermal resistance θ ij After the functional relationship between a and b is obtained, the functional relationship between coefficients a, b and the convective heat transfer coefficient h is established. The results show that the convective heat transfer coefficient presents an approximate exponential relationship with a and b, so the relationship between the convective heat transfer coefficient h and a and b is constructed respectively:

[0117]

[0118] Among them, the convective heat transfer coefficient h as an unknown quantity also needs to be identified. m1, m2, n1, n2, τ1, τ2 are all constants, and the constants that change with the cable model are fitted values.

[0119] Combining the above formula, the calculation formula for the contact resistance coefficient k can be obtained as follows:

[0120]

[0121] In an optional embodiment, the specific value of the contact resistance can be obtained by the contact resistance coefficient k. It is only necessary to determine the wire length l, the cross-sectional area S and the resistivity ρ of the cable conductor that need to be obtained in the target cable to calculate the corresponding contact resistance value. Therefore, as long as the specific contact resistance coefficient k is obtained, the target cable joint contact resistance R can be completed. ij Obtaining:

[0122]

[0123] In an optional embodiment, the method of the present application can be implemented by a more detailed summary, such as Figure 2 As shown, the cable surface temperature data is obtained 201: First, the temperature data of the cable surface needs to be collected. This part of the data is usually obtained through sensors or other measurement methods. The intermediate joint hot spot temperature data is obtained 202: It is also necessary to obtain the hot spot temperature data at the intermediate joint position, which is also measured in a corresponding manner. Use the extreme learning machine (ELM) 203: The above two temperature data are input into the extreme learning machine (ELM), which is an efficient learning algorithm for constructing an intermediate joint hot spot temperature inversion model. Construct an intermediate joint hot spot temperature inversion model 204: Through the ELM algorithm, based on the existing cable surface temperature and intermediate joint hot spot temperature data, a mapping relationship between the two is established, thereby constructing an intermediate joint hot spot temperature inversion model. Define the joint equivalent thermal resistance 205: In order to further improve the model, it is necessary to define the concept of joint equivalent thermal resistance, which involves the identification of the convective heat transfer coefficient. Convective heat transfer coefficient identification 206: Through the identification of the convective heat transfer coefficient, the heat transfer process can be described more accurately, thereby improving the prediction accuracy of the model. Intermediate joint contact resistance 207: The last step is to determine the contact resistance of the intermediate joint, which is also an important parameter and has a direct impact on the simulation of the temperature field.

[0124] In summary, the present invention proposes a single-core cable contact resistance inversion method, obtains the first temperature data and the second temperature data of the target cable; establishes a first mapping relationship of the second temperature data to the first temperature data, and obtains a first inversion model; based on the first inversion model, obtains the first joint equivalent thermal resistance; presets a first constraint condition, and obtains the target cable joint contact resistance in combination with the first joint equivalent thermal resistance. It can effectively monitor and evaluate the contact resistance state of the cable joint, thereby realizing real-time monitoring of the cable operation state. Through accurate temperature data acquisition and the establishment of an inversion model, the system can warn of potential faults of the cable joint, avoid overheating problems caused by excessive contact resistance, thereby improving the safety and reliability of cable operation. The present application provides strong technical support for the healthy operation of the cable, and has significant practical value and market application prospects. The present application adopts an extreme learning machine algorithm to construct an intermediate joint hot spot temperature inversion model, and defines the joint equivalent thermal resistance based on the inverted cable intermediate joint hot spot temperature. Subsequently, a relationship between the joint contact resistance, the joint equivalent thermal resistance and the cable surface convection heat transfer coefficient is established. By simplifying the radial transient thermal circuit of the cable body, a steady-state thermal circuit model is obtained. The air thermal resistance is calculated through the thermal circuit model, and the convective heat transfer coefficient identification formula is obtained by combining it with the air thermal resistance definition formula. The heat dissipation conditions on the surface of the cable body can be effectively obtained, thereby inverting the contact resistance of the cable intermediate joint.

[0125] This embodiment also provides a single-core cable contact resistance inversion system, including:

[0126] A data acquisition module, used to acquire first temperature data and second temperature data of a target cable;

[0127] A model building module, used to establish a first mapping relationship between the second temperature data and the first temperature data to obtain a first inversion model;

[0128] A first calculation module, used for obtaining an equivalent thermal resistance of a first joint based on a first inversion model;

[0129] The second calculation module is used to preset the first constraint condition and obtain the target cable joint contact resistance in combination with the first joint equivalent thermal resistance.

[0130] The above-mentioned unit modules may be embedded in or independent of a processor in a computer device in the form of hardware, or may be stored in a memory in a computer device in the form of software, so that the processor can call and execute operations corresponding to the above-mentioned modules.

[0131] This embodiment also provides a computer device, which may be a terminal, and its internal structure diagram may be as follows: Figure 5As shown. The computer device includes a processor, a memory, a communication interface, a display screen and an input device connected through a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be achieved through WIFI, an operator network, NFC (near field communication) or other technologies. When the computer program is executed by the processor, a single-core cable contact resistance inversion method is implemented. The display screen of the computer device can be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device can be a touch layer covered on the display screen, or a button, trackball or touchpad set on the computer device housing, or an external keyboard, touchpad or mouse, etc.

[0132] This embodiment further provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the following steps are implemented:

[0133] Acquire first temperature data and second temperature data of the target cable;

[0134] Establishing a first mapping relationship between the second temperature data and the first temperature data to obtain a first inversion model;

[0135] Based on the first inversion model, obtaining the equivalent thermal resistance of the first joint;

[0136] A first constraint condition is preset, and the target cable joint contact resistance is obtained in combination with the first joint equivalent thermal resistance.

[0137] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

[0138] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of complete hardware embodiments, complete software embodiments, or embodiments in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code. The scheme in the embodiments of the present application can be implemented in various computer languages, for example, object-oriented programming language Java and literal scripting language JavaScript, etc.

[0139] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0140] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0141] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0142] Although the preferred embodiments of the present application have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0143] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A single-core cable contact resistance inversion method, characterized in that: include: Acquire first temperature data and second temperature data of the target cable; Establishing a first mapping relationship between the second temperature data and the first temperature data to obtain a first inversion model; Based on the first inversion model, obtaining an equivalent thermal resistance of a first joint; A first constraint condition is preset, and a target cable joint contact resistance is obtained in combination with the first joint equivalent thermal resistance.

2. The single-core cable contact resistance inversion method according to claim 1, characterized in that: The first inversion model includes: The first inversion model is an arbitrary model established according to the first mapping relationship; The input of the first inversion model is first temperature data, and the output is second temperature data.

3. The single-core cable contact resistance inversion method according to claim 2, characterized in that: The first constraint condition includes at least one heat dissipation condition and one crimping condition.

4. The single-core cable contact resistance inversion method according to claim 3, characterized in that: The preset first constraint condition and the first joint equivalent thermal resistance are combined to obtain the target cable joint contact resistance, which includes: Establishing a first equivalent thermal circuit model based on a first constraint condition; Calculating the convection heat transfer coefficient according to the first equivalent heat circuit model; The target cable joint contact resistance is obtained according to the convection heat transfer coefficient and the first joint equivalent thermal resistance.

5. The single-core cable contact resistance inversion method according to claim 4, characterized in that: The obtaining the first joint equivalent thermal resistance based on the first inversion model includes: The first joint equivalent thermal resistance is obtained by the inversion value of the first inversion model at the corresponding moment, the conductor load current, the conductor resistance of the joint part and the ambient temperature; The ambient temperature is the stable ambient temperature of the joint resistor without wind, rain or sunshine.

6. The single-core cable contact resistance inversion method according to claim 5, characterized in that: The step of obtaining the target cable joint contact resistance according to the convection heat transfer coefficient and the first joint equivalent thermal resistance comprises: Establishing a functional relationship between the convection heat transfer coefficient, the equivalent thermal resistance of the first joint, and the contact resistance coefficient of the target cable joint; The contact resistance coefficient of the target cable joint in the functional relationship is solved by the convection heat transfer coefficient and the equivalent thermal resistance of the first joint; The target cable joint contact resistance is obtained according to the target cable joint contact resistance coefficient.

7. The single-core cable contact resistance inversion method according to claim 6, characterized in that: The obtaining of the first temperature data and the second temperature data of the target cable comprises: The first temperature data and the second temperature data of the target cable are obtained by establishing a temperature field simulation model of the target cable intermediate joint and the body.

8. A single-core cable contact resistance inversion system, characterized in that: include: A data acquisition module, used to acquire first temperature data and second temperature data of a target cable; A model building module, used to establish a first mapping relationship between the second temperature data and the first temperature data to obtain a first inversion model; A first calculation module, used for obtaining an equivalent thermal resistance of a first joint based on the first inversion model; The second calculation module is used to preset a first constraint condition and obtain a target cable joint contact resistance in combination with the first joint equivalent thermal resistance.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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