Cable joint state evaluation method and device based on flow temperature

Abstract

The invention provides a cable joint state evaluation method and device based on flow temperature, and the method comprises the steps: synchronously measuring the load current and surface temperature of a cable joint through a miniature flow temperature composite sensor disposed on the surface of the cable joint, and carrying out the real-time preprocessing of the load current and surface temperature, the effective load current and the effective surface temperature under the steady-state working condition after preprocessing are obtained, the environment temperature of the cable connector is monitored in real time, and the contact resistance of the cable connector is obtained through inversion based on the effective load current, the effective surface temperature and the environment temperature of the cable connector in combination with a preset heat balance equation; and calculating a corresponding state indication ratio based on the load current, the surface temperature and the environment temperature, evaluating the operation state of the cable joint based on the contact resistance and the state indication ratio, and performing corresponding early warning.

Description

Technical Field

[0001] This application relates to the field of power technology, and more specifically, to a method and apparatus for evaluating the condition of cable joints based on flow temperature. Background Technology

[0002] In the operation of communication power supply terminals, loose connections often occur due to loose bolts, moisture corrosion, high-temperature oxidation, etc., leading to abnormally high resistance and localized temperature rise. In severe cases, this can cause power outages or even equipment burnout, delaying grid dispatching and causing power production accidents. Therefore, it is necessary to monitor cable joints.

[0003] Currently, traditional cable joint monitoring solutions rely on independently installed temperature and current sensors to monitor the cable joints and trigger alarms, requiring regular manual inspections. However, patent application CN202111650145.2 proposes establishing a flow-temperature model to dynamically determine the health status of cable joints.

[0004] However, traditional cable joint monitoring solutions require costly separate designs for temperature and current sensors, and the accuracy of analyzing the operating status of cable joints is generally low, making early fault prediction difficult. Furthermore, the flow-temperature model established in the aforementioned patent document is a relatively fixed model, making it difficult to apply to various application scenarios such as different cable specifications and cable joint types, thus limiting its application scope. Summary of the Invention

[0005] In view of this, the purpose of this application is to provide a method and device for evaluating the condition of cable joints based on flow temperature. By using flow temperature composite sensing technology to simultaneously collect load current and joint temperature data of the cable joint, the contact resistance value is inverted based on the heat balance equation, and the operating status of the cable joint is evaluated and an early warning is given by combining the contact resistance value and the condition indication ratio. This method can meet the monitoring of cable joint status in multiple scenarios and improve the application scope of monitoring. By using quantitative indicators to evaluate the condition of the cable joint and provide early warning, the accuracy of the analysis of the operating status of the cable joint is improved, and early fault warning is achieved.

[0006] In a first aspect, embodiments of this application provide a method for evaluating the condition of cable joints based on flow temperature, the method comprising: The load current and surface temperature of the cable joint are simultaneously measured by a miniature flow-temperature composite sensor mounted on the surface of the cable joint. The load current and the surface temperature are preprocessed in real time to obtain the effective load current and effective surface temperature under steady-state conditions after preprocessing. The ambient temperature of the cable joint is monitored in real time. Based on the effective load current, effective surface temperature and ambient temperature of the cable joint, and combined with the preset heat balance equation, the contact resistance of the cable joint is obtained by inversion. The corresponding status indication ratio is calculated based on the load current, the surface temperature, and the ambient temperature. The operating status of the cable joint is evaluated based on the contact resistance and the status indication ratio, and corresponding early warnings are issued.

[0007] In one possible implementation, the real-time preprocessing of the load current and the surface temperature includes: The load current and the surface temperature are filtered by a sliding window averaging method with a target window length, and a preset temperature gradient is applied for compensation correction to identify abnormal load current and abnormal surface temperature. The abnormal load current and the abnormal surface temperature are removed, and the load current and surface temperature with current fluctuation less than the preset current fluctuation rate and temperature change rate less than the preset temperature change rate are selected as the effective load current and effective surface temperature under steady-state conditions.

[0008] In one possible implementation, the step of inverting the contact resistance of the cable joint by combining a preset heat balance equation includes: The comprehensive heat dissipation coefficient and effective heat dissipation area are obtained based on the pre-stored connector parameter database, and the corresponding inversion formula is determined based on the heat balance equation. The effective load current, the effective surface temperature, the ambient temperature, the comprehensive heat dissipation coefficient, and the effective heat dissipation area are input into the inversion formula to calculate the contact resistance of the cable joint.

[0009] In one possible implementation, the step of evaluating the operating status of the cable joint based on the contact resistance and the status indication ratio and issuing a corresponding early warning includes: A multi-dimensional evaluation index is defined; wherein the evaluation index includes at least electrical performance index, relative change index, and thermal performance index; the electrical performance index is determined by the contact resistance, warning value, and safety threshold; the relative change index is determined by the state indication ratio, baseline value, and change threshold; the thermal performance index is determined by the temperature index, second warning value, and second safety threshold; the temperature index is determined by the surface temperature or the surface temperature change value. When the temperature index exceeds the second safety threshold, the highest level temperature warning is triggered directly; when the temperature index exceeds the second warning value, the corresponding temperature warning flag is marked. The basic warning level is determined based on the combination of the contact resistance, the warning value, the safety threshold, and the status indication ratio; wherein, different levels of basic warning correspond to different colors, conditions, and measures; In response to the occurrence of a temperature warning and the basic warning level being the target basic warning level, the warning level will be dynamically adjusted.

[0010] In one possible implementation, the method further includes: The cable joint is measured multiple times. Based on the load current, surface temperature and ambient temperature obtained from each measurement, the corresponding current data matrix, joint temperature matrix and ambient temperature matrix are obtained respectively. Based on the current data matrix, the joint temperature matrix and the ambient temperature matrix, the vector-calculated state indication ratio is obtained by element-wise multiplication. Based on the connector parameter database, the thermal conductivity, convective heat dissipation coefficient, and radiative heat dissipation coefficient of the cable connector are determined. Based on the state indication ratio and the thermal conductivity, convective heat dissipation coefficient, and radiative heat dissipation coefficient of the cable connector, a correction formula for the comprehensive heat dissipation coefficient is obtained, and the calibration error of the comprehensive heat dissipation coefficient is eliminated based on the correction formula.

[0011] In one possible implementation, the method further includes: Based on a preset initial time and multiple time points, an accumulated time step is performed to obtain a corresponding time parameter vector, and based on the time parameter vector, the contact resistance matrix of the cable joint is measured at multiple time points. The contact resistance matrix is ​​fitted twice using the least squares method, transforming the discrete contact resistance points in the matrix into a continuous trend, thus obtaining the contact resistance fitting equation. Based on the contact resistance fitting equation, the time-optimized contact resistance is obtained.

[0012] In one possible implementation, the method further includes: The load current and the surface temperature are time-aligned using a clock built into the miniature flow-temperature composite sensor. Time alignment is performed based on a preset sensor response delay compensation amount and the time of the load current and the surface temperature.

[0013] Secondly, embodiments of this application also provide a cable joint condition assessment device based on flow temperature, the device comprising: The measurement module is used to simultaneously measure the load current and surface temperature of the cable joint using a miniature flow-temperature composite sensor mounted on the surface of the cable joint. The processing module is used to perform real-time preprocessing on the load current and the surface temperature to obtain the effective load current and effective surface temperature under steady-state conditions after preprocessing. The calculation module is used to monitor the ambient temperature of the cable joint in real time, and based on the effective load current, effective surface temperature and ambient temperature of the cable joint, combined with the preset heat balance equation, the contact resistance of the cable joint is obtained by inversion. The evaluation module is used to calculate the corresponding status indication ratio based on the load current, the surface temperature and the ambient temperature, evaluate the operating status of the cable joint based on the contact resistance and the status indication ratio and issue corresponding early warnings.

[0014] In one possible implementation, the processing module is specifically used for: The load current and the surface temperature are filtered by a sliding window averaging method with a target window length, and a preset temperature gradient is applied for compensation correction to identify abnormal load current and abnormal surface temperature. The abnormal load current and the abnormal surface temperature are removed, and the load current and surface temperature with current fluctuation less than the preset current fluctuation rate and temperature change rate less than the preset temperature change rate are selected as the effective load current and effective surface temperature under steady-state conditions.

[0015] In one possible implementation, the computing module is specifically used for: The comprehensive heat dissipation coefficient and effective heat dissipation area are obtained based on the pre-stored connector parameter database, and the corresponding inversion formula is determined based on the heat balance equation. The effective load current, the effective surface temperature, the ambient temperature, the comprehensive heat dissipation coefficient, and the effective heat dissipation area are input into the inversion formula to calculate the contact resistance of the cable joint.

[0016] In one possible implementation, the evaluation module is specifically used for: A multi-dimensional evaluation index is defined; wherein the evaluation index includes at least electrical performance index, relative change index, and thermal performance index; the electrical performance index is determined by the contact resistance, warning value, and safety threshold; the relative change index is determined by the state indication ratio, baseline value, and change threshold; the thermal performance index is determined by the temperature index, second warning value, and second safety threshold; the temperature index is determined by the surface temperature or the surface temperature change value. When the temperature index exceeds the second safety threshold, the highest level temperature warning is triggered directly; when the temperature index exceeds the second warning value, the corresponding temperature warning flag is marked. The basic warning level is determined based on the combination of the contact resistance, the warning value, the safety threshold, and the status indication ratio; wherein, different levels of basic warning correspond to different colors, conditions, and measures; In response to the occurrence of a temperature warning and the basic warning level being the target basic warning level, the warning level will be dynamically adjusted.

[0017] In one possible implementation, the device further includes: The first acquisition module is used to perform multiple measurements on the cable joint, and obtain corresponding current data matrices, joint temperature matrices and ambient temperature matrices based on the load current, surface temperature and ambient temperature obtained from each measurement, and obtain the vector-calculated state indication ratio based on the current data matrix, the joint temperature matrix and the ambient temperature matrix through element-wise multiplication. The second acquisition module is used to determine the thermal conductivity, convective heat dissipation coefficient, and radiative heat dissipation coefficient of the cable joint based on the joint parameter database, obtain the formula for the comprehensive heat dissipation coefficient based on the state indication ratio and the thermal conductivity, convective heat dissipation coefficient, and radiative heat dissipation coefficient of the cable joint, and eliminate the calibration error of the comprehensive heat dissipation coefficient based on the formula of the comprehensive heat dissipation coefficient.

[0018] In one possible implementation, the device further includes: The third acquisition module is used to accumulate time steps based on a preset initial time and multiple time points to obtain a corresponding time parameter vector, and to measure the contact resistance matrix of the cable joint at multiple time points based on the time parameter vector. The fourth acquisition module is used to perform a second-order fitting of the contact resistance matrix based on the least squares method, transforming the discrete contact resistance points in the contact resistance matrix into a continuous trend, obtaining the contact resistance fitting equation, and obtaining the time-optimized contact resistance based on the contact resistance fitting equation.

[0019] In one possible implementation, the device further includes: The first synchronization module is used to time-align the load current and the surface temperature using the clock built into the miniature flow-temperature composite sensor. The second synchronization module is used to perform time alignment based on a preset sensor response delay compensation amount and the time of the load current and the surface temperature.

[0020] Thirdly, embodiments of this application provide an electronic device, including: a processor, a storage medium, and a bus, wherein the storage medium stores machine-readable instructions executable by the processor, and when the electronic device is running, the processor communicates with the storage medium via the bus, and the processor executes the machine-readable instructions to perform the steps of the flow temperature-based cable joint status assessment method as described in any of the first aspects.

[0021] Fourthly, embodiments of this application provide a computer-readable storage medium storing a computer program, which, when executed by a processor, performs the steps of the cable joint condition assessment method based on flow temperature as described in any of the first aspects.

[0022] This application provides a method and apparatus for evaluating the condition of cable joints based on flow-temperature. It simultaneously measures the load current and surface temperature of the cable joint using a miniature flow-temperature composite sensor mounted on the surface of the cable joint. The load current and surface temperature are preprocessed in real time to obtain the effective load current and effective surface temperature under steady-state conditions. The ambient temperature of the cable joint is monitored in real time. Based on the effective load current, effective surface temperature, and ambient temperature of the cable joint, and combined with a preset heat balance equation, the contact resistance of the cable joint is calculated. The corresponding state indication ratio is calculated based on the load current, surface temperature, and ambient temperature. The operating condition of the cable joint is evaluated based on the contact resistance and the state indication ratio, and corresponding early warnings are issued. This application, through flow-temperature composite sensing technology, simultaneously collects the load current and joint temperature data of the cable joint, calculates the contact resistance value based on the heat balance equation, and evaluates the operating condition of the cable joint and issues early warnings based on the contact resistance value and the state indication ratio. This can meet the monitoring needs of cable joints in multiple scenarios and improves the application scope of monitoring. By using quantitative indicators to evaluate the condition of the cable joint and provide early warnings, the accuracy of the analysis of the operating condition of the cable joint is improved, and early fault warnings are achieved.

[0023] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1This is a flowchart of a cable joint condition assessment method based on flow temperature provided in an embodiment of this application; Figure 2 This is a schematic diagram of the structure of a cable joint condition assessment device based on flow temperature according to an embodiment of this application; Figure 3 This is a schematic diagram of the structure of an electronic device provided according to an embodiment of this application. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. It should be understood that the accompanying drawings in this application are for illustrative and descriptive purposes only and are not intended to limit the scope of protection of this application. Furthermore, it should be understood that the schematic drawings are not drawn to scale. The flowcharts used in this application illustrate operations implemented according to some embodiments of this application. It should be understood that the operations in the flowcharts may not be implemented in sequence, and steps without logical contextual relationships may be reversed or implemented simultaneously. In addition, those skilled in the art, guided by the content of this application, may add one or more other operations to the flowcharts, or remove one or more operations from the flowcharts.

[0027] Furthermore, the described embodiments are merely some, not all, of the embodiments of this application. The components of the embodiments of this application described and illustrated herein can typically be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0028] It should be noted that the term "comprising" will be used in the embodiments of this application to indicate the presence of the features declared thereafter, but does not exclude the addition of other features.

[0029] Considering that in the operation of communication power supply terminals, loose connections often occur due to reasons such as loose bolts, moisture corrosion, and high-temperature oxidation, leading to abnormally high resistance and localized temperature rise. In severe cases, this can cause power outages or even equipment burnout, delaying grid dispatching and causing power production accidents. Therefore, it is necessary to monitor cable joints.

[0030] Currently, traditional cable joint monitoring solutions rely on independently installed temperature and current sensors to monitor the cable joints and trigger alarms, requiring regular manual inspections. However, patent application CN202111650145.2 proposes establishing a flow-temperature model to dynamically determine the health status of cable joints.

[0031] However, traditional cable joint monitoring solutions require costly separate designs for temperature and current sensors, and the accuracy of analyzing the operating status of cable joints is generally low, making early fault prediction difficult. Furthermore, the flow-temperature model established in the aforementioned patent document is a relatively fixed model, making it difficult to apply to various application scenarios such as different cable specifications and cable joint types, thus limiting its application scope.

[0032] To address this issue, this application provides a method and apparatus for assessing the condition of cable joints based on flow-temperature. It simultaneously collects load current and joint temperature data of the cable joint using flow-temperature composite sensing technology, inverts the contact resistance value based on the heat balance equation, and combines the contact resistance value with the condition indication ratio to assess the operating status and provide early warnings. This method can meet the monitoring needs of cable joints in multiple scenarios and expands the application scope of monitoring. By using quantitative indicators to assess the condition of cable joints and provide early warnings, it improves the accuracy of analyzing the operating status of cable joints and achieves early fault warnings.

[0033] Figure 1 This is a flowchart of a cable joint condition assessment method based on flow temperature, provided according to an embodiment of this application. Figure 1 As shown, the cable joint condition assessment method based on flow temperature in this application embodiment may specifically include: S101. The load current and surface temperature of the cable joint are simultaneously measured by a miniature flow-temperature composite sensor installed on the surface of the cable joint.

[0034] S102. Perform real-time preprocessing on the load current and surface temperature to obtain the effective load current and effective surface temperature under steady-state conditions after preprocessing.

[0035] S103. Monitor the ambient temperature of the cable joint in real time. Based on the effective load current, effective surface temperature and ambient temperature of the cable joint, and combined with the preset heat balance equation, the contact resistance of the cable joint is obtained by inversion.

[0036] S104. Calculate the corresponding status indication ratio based on load current, surface temperature and ambient temperature, evaluate the operating status of the cable joint based on contact resistance and status indication ratio and issue corresponding early warnings.

[0037] In the aforementioned cable joint condition assessment method based on flow temperature, the load current and joint temperature data of the cable joint are collected simultaneously through flow temperature composite sensing technology. The contact resistance value is inverted based on the heat balance equation. The operating status of the cable joint is assessed and early warning is given by combining the contact resistance value and the condition indication ratio. This method can meet the monitoring of cable joint status in multiple scenarios and improve the application scope of monitoring. The quantitative indicators are used to assess the status of the cable joint and provide early warning, which improves the accuracy of the analysis of the operating status of the cable joint and realizes early fault warning.

[0038] The exemplary steps described above in the embodiments of this application are illustrated below with specific examples: S101, the load current and surface temperature of the cable joint are simultaneously measured by a miniature flow-temperature composite sensor mounted on the surface of the cable joint. In this embodiment, the miniature flow-temperature composite sensor is a current and temperature composite sensor, such as a TMR (tunnel magnetoresistive)-temperature miniature composite sensor; the miniature flow-temperature composite sensor is mounted on the surface of the cable joint, and the load current and surface temperature data of the cable joint are simultaneously measured by the miniature flow-temperature composite sensor for subsequent processing.

[0039] Optionally, the miniature flow-temperature composite sensor includes a TMR current sensor and a distributed temperature sensing unit. The TMR current sensor is fixedly installed on the surface of the cable joint in a non-contact manner. Multiple cable joints in the same circuit are selected, and the real-time load current of each cable joint is acquired by the TMR current sensor based on a preset current accuracy (e.g., ±1%). The distributed temperature sensing unit acquires the surface temperature field distribution of each cable joint through multiple temperature measurement points based on a preset temperature resolution (e.g., 0.1℃), and the surface temperature of the cable joint is obtained based on the surface temperature field distribution. For example, multiple cable joints in the same circuit are selected as monitoring points, and the current value (I) and surface temperature value (T) of each joint are synchronously acquired by the sensor array. j ).

[0040] S102 performs real-time preprocessing on the load current and surface temperature to obtain the effective load current and effective surface temperature under steady-state conditions after preprocessing.

[0041] In this embodiment of the application, the steady-state operating conditions are, for example, current fluctuation <5% and temperature change rate <0.1℃ / min. The load current and surface temperature of the cable joint collected in step S101 are preprocessed in real time to obtain the effective load current and effective surface temperature under the preprocessed steady-state operating conditions for subsequent processing.

[0042] Optionally, when performing real-time preprocessing of load current and surface temperature, a sliding window averaging method with a target window length is used to perform sliding average filtering on load current and surface temperature, and a preset temperature gradient compensation correction is performed to identify abnormal load current and abnormal surface temperature; abnormal load current and abnormal surface temperature are removed, and load current and surface temperature with current fluctuation less than a preset current fluctuation rate and temperature change rate less than a preset temperature change rate are selected as the effective load current and effective surface temperature under steady-state conditions.

[0043] Specifically, the raw load current and surface temperature are preprocessed by moving average filtering and temperature compensation to extract the effective data segments under steady-state conditions: First, the data is smoothed by using the moving window averaging method (e.g., window length of 10 points), then temperature gradient compensation correction is performed, abnormal data points are automatically identified and removed, and the effective data segments under steady-state conditions, namely the effective load current and effective surface temperature, are retained.

[0044] S103 monitors the ambient temperature of the cable joint in real time. Based on the effective load current, effective surface temperature and ambient temperature of the cable joint, and combined with the preset heat balance equation, the contact resistance of the cable joint is obtained by inversion.

[0045] Those skilled in the art will understand that, according to the application of the law of conservation of energy in the field of thermodynamics, when a cable joint reaches a thermally stable state, the Joule heat generated per unit time must be equal to the heat lost to the surrounding environment per unit time. Based on this principle, this application can deduce the contact resistance of the cable joint by simultaneously collecting load current, surface temperature, and ambient temperature, combined with the heat balance equation.

[0046] In this embodiment of the application, the ambient temperature of the cable joint is measured in real time. Based on the effective load current, effective surface temperature and ambient temperature of the cable joint obtained in step S102, and combined with the preset heat balance equation, the contact resistance of the cable joint is calculated by inversion for subsequent processing.

[0047] Optionally, when inverting the contact resistance of the cable joint by combining the preset heat balance equation, the comprehensive heat dissipation coefficient and effective heat dissipation area are obtained based on the pre-stored joint parameter database, and the corresponding inversion formula is determined based on the heat balance equation; the effective load current, effective surface temperature, ambient temperature, comprehensive heat dissipation coefficient and effective heat dissipation area are input into the inversion formula to calculate the contact resistance of the cable joint.

[0048] The heat balance equation is as follows:

[0049] The inversion formula is:

[0050] Where I represents the load current as I, T j The surface temperature is represented as T. a Let represent the ambient temperature, K represent the overall heat dissipation coefficient, and A represent the effective heat dissipation area.

[0051] S104 calculates the corresponding status indication ratio based on load current, surface temperature and ambient temperature, evaluates the operating status of the cable joint based on contact resistance and status indication ratio and provides corresponding early warning.

[0052] In this embodiment of the application, the state indication ratio (S represents) is calculated based on the load current and surface temperature measured in step S101 and the ambient temperature monitored in step S103. The operating status of the cable joint is evaluated based on the contact resistance and state indication ratio of the cable joint obtained in step S103, and corresponding early warnings are issued.

[0053] Specifically, the state indication ratio S is introduced as a dimensionless evaluation index. The following formula represents the state indication ratio S calculated based on a single measurement:

[0054] In some implementations, preset multi-dimensional evaluation indicators are determined; the highest level temperature warning is directly triggered when the temperature indicator exceeds the second safety threshold, and a corresponding temperature warning flag is marked when the temperature indicator exceeds the second warning value; a corresponding basic warning level is determined based on the combination of the contact resistance, the warning value, the safety threshold, and the state indication ratio; and the warning level is dynamically adjusted when a temperature warning occurs and the basic warning level is the target basic warning level.

[0055] The evaluation indicators include at least electrical performance indicators, relative change indicators, and thermal performance indicators. Electrical performance indicators are determined by contact resistance, warning values, and safety thresholds. Relative change indicators are determined by the status indication ratio, baseline value, and change threshold. The baseline value represents the average status indication ratio during normal operation after equipment installation and commissioning or during the target period of stable operation after the most recent maintenance. The change threshold represents the baseline value of the target multiplier. Thermal performance indicators are determined by temperature indicators, a second warning value, and a second safety threshold. Temperature indicators are determined by surface temperature or surface temperature change values. Different levels of basic warnings correspond to different colors, conditions, and measures. Basic warning levels include green status, yellow warning, orange alert, and red alert.

[0056] It should be noted that this application adopts a three-level evaluation index system, including a contact resistance index that reflects the absolute level of conductivity, a state indication ratio index that reflects the relative trend of change, and a temperature index that directly reflects the heating status. Clear warning values ​​and safety thresholds are set for each index.

[0057] Among them, the electrical performance index Rc includes: contact resistance (Rc_optimized), which reflects the absolute level of electrical conductivity; warning value (Rc_warning), which is set as a stricter warning line below the safety threshold for early detection of potential hazards; safety threshold (Rc_safe): when the contact resistance exceeds this threshold, it indicates that the joint performance has seriously deteriorated and there is an immediate risk of failure, and it is set according to technical specifications and industry standards.

[0058] The relative change index includes: status indication ratio (S), which reflects the change trend relative to the baseline; baseline value (Sbaseline), which takes the average value of S during normal operation after equipment installation and commissioning or during a stable operation period (such as 168 hours) after the most recent maintenance as the health baseline; change threshold, for example, S > 1.2×S_baseline (a 20% over-standard is considered a significant relative deterioration trend of the joint).

[0059] The thermal performance index (T or ΔT) includes: temperature index (Tj / ΔT), which directly reflects the heating condition; warning value Tj_warning = or ΔT_warning, a lower warning value for early warning of overheating risk; safety threshold, Tj_safe sets the absolute upper limit of the joint temperature, and ΔT_safe sets the upper limit of the temperature rise relative to the ambient temperature.

[0060] Continuing, this application adopts a hierarchical decision-making mechanism, and the specific process is as follows: The first level: temperature priority judgment: If Tj ≥ Tj_safe or ΔT ≥ ΔT_safe → directly trigger a red alarm; If Tj ≥ Tj_warning or ΔT ≥ ΔTwarning → mark the temperature warning flag.

[0061] The second level: core decision of electrical parameters Green status: Rc < Rc_warning and S ≤ 1.2Sbaseline Yellow warning: Rc < Rc_warning but S > 1.2Sbaseline Orange alarm: Rc_warning ≤ Rc < Rc_safe Red alarm: Rc ≥ Rc_safe The third level: temperature verification and warning upgrade Electrical parameter decision is green / yellow + temperature warning → the warning level is upgraded by one level; Electrical parameter decision is orange / red + temperature warning → maintain the original alarm level.

[0062] Therefore, this application proposes a multi-indicator fusion decision-making logic, employing a hierarchical judgment mechanism. First, temperature is prioritized; when the temperature exceeds a safety threshold, the highest-level alarm is triggered directly. Second, electrical parameters are used for core decision-making, determining the basic warning level based on the combination of contact resistance and status indication ratio. Finally, the warning level is dynamically adjusted through temperature verification. This multi-indicator cross-verification mechanism ensures high system sensitivity to typical "high resistance with high temperature" faults while effectively avoiding false alarms from single parameters.

[0063] In addition, the warning level and operation and maintenance decisions for this application are as follows: Level 1 Alert (Green) Conditions: Electrical parameters are green + temperature is normal Measures: Routine monitoring.

[0064] Level II Warning (Yellow) Conditions: Electrical parameter yellow + normal temperature, or electrical parameter green + temperature warning. Measures: Strengthen monitoring and alert for "early degradation" Level 3 Alert (Orange) Conditions: Electrical parameters are orange, or electrical parameters are yellow + temperature warning. Measures: Planned maintenance.

[0065] Level IV Alert (Red) Conditions: Electrical parameters are red, or temperature exceeds the safe threshold. Measures: Immediate shutdown, emergency repairs, and activation of emergency procedures.

[0066] The cable joint condition assessment method based on flow temperature provided in this application synchronously measures the load current and surface temperature of the cable joint using a miniature flow temperature composite sensor installed on the surface of the cable joint. The load current and surface temperature are preprocessed in real time to obtain the effective load current and effective surface temperature under steady-state conditions after preprocessing. The ambient temperature of the cable joint is monitored in real time. Based on the effective load current, effective surface temperature, and ambient temperature of the cable joint, and combined with a preset heat balance equation, the contact resistance of the cable joint is obtained by inversion. The corresponding state indication ratio is calculated based on the load current, surface temperature, and ambient temperature. The operating status of the cable joint is assessed based on the contact resistance and the state indication ratio, and corresponding early warnings are issued. This method, based on flow temperature, synchronously collects load current and joint temperature data of the cable joint using flow temperature composite sensing technology. It inverts the contact resistance value based on the heat balance equation and combines the contact resistance value and the state indication ratio to assess the operating status of the cable joint and issue early warnings. This method can meet the monitoring needs of cable joints in multiple scenarios and improves the application scope of monitoring. By using quantitative indicators to assess the status of the cable joint and provide early warnings, it improves the accuracy of the analysis of the operating status of the cable joint and achieves early fault warnings.

[0067] Furthermore, multiple measurements were performed on the cable joint. Based on the load current, surface temperature, and ambient temperature obtained from each measurement, corresponding current data matrices, joint temperature matrices, and ambient temperature matrices were obtained. Based on the current data matrices, joint temperature matrices, and ambient temperature matrices, the vector-calculated state indication ratio was obtained through element-by-element multiplication. Based on the joint parameter database, the thermal conductivity, convective heat dissipation coefficient, and radiative heat dissipation coefficient of the cable joint were determined. Based on the state indication ratio and the thermal conductivity, convective heat dissipation coefficient, and radiative heat dissipation coefficient of the cable joint, a correction formula for the comprehensive heat dissipation coefficient was obtained, and the calibration error of the comprehensive heat dissipation coefficient was eliminated based on the correction formula.

[0068] Specifically, in order to eliminate the calibration error of the comprehensive heat dissipation coefficient K, the state indication ratio S is introduced as a dimensionless evaluation index, which is calculated based on a single measurement.

[0069] When the cable joint is measured multiple times (n measurements), the load current, surface temperature, and ambient temperature data for each measurement can be represented in matrix form: The current data matrix (unit: A) from n measurements is as follows:

[0070] The joint temperature matrix (unit: K) from n measurements is as follows:

[0071] The ambient temperature matrix (unit: K) from n measurements is as follows:

[0072] Using the matrix described above, the vector calculation of the state indication ratio S can be achieved through element-by-element operations, resulting in the following vector-calculated state indication ratio:

[0073] Where ⊙ denotes element-wise multiplication, and the vector calculation of the contact resistance Rc is:

[0074] The overall heat dissipation coefficient K needs to be determined based on the joint material and specifications, taking into account the thermal conductivity λ, convective heat dissipation coefficient h, and radiative heat dissipation coefficient ε (obtained from the joint parameter database). The formula for the overall heat dissipation coefficient K is as follows:

[0075] Where σ is the Stefan-Boltzmann constant (5.67×10⁻⁸ W / (m²·K)).

[0076] Furthermore, based on the preset initial time and multiple time points, the cumulative time step is obtained to obtain the corresponding time parameter vector, and the contact resistance matrix of the cable joint is measured at multiple time points based on the time parameter vector; the contact resistance matrix is ​​then fitted twice using the least squares method to transform the discrete contact resistance points in the contact resistance matrix into a continuous trend, resulting in a contact resistance fitting equation, and the time-optimized contact resistance is obtained based on the contact resistance fitting equation.

[0077] The contact resistance fitting equation is determined based on a predetermined design matrix and parameter vector. The design matrix is ​​determined by the time parameter vector, and the parameter vector is determined by the design matrix and the contact resistance.

[0078] It should be noted that this application combines time series data and uses the least squares method to fit the changing trend of contact resistance. Because the measurement data contains Gaussian noise, dynamic correction is achieved through state equations.

[0079] Specifically, the time vector and contact resistance vector matrix are determined at N time points. The time parameter vector is obtained by accumulating time steps starting from the initial time t=0.

[0080] A matrix of contact resistance measured at N time points:

[0081] Based on the least squares method, a quadratic fitting is performed. Through mathematical modeling, discrete contact resistance points are transformed into continuous trend equations. The quadratic model achieves a balance between fitting local fluctuations and maintaining global stability, resulting in the contact resistance fitting equation:

[0082] The design matrix is ​​as follows:

[0083] The parameter vector is:

[0084] Furthermore, using Kalman filtering, a state equation is obtained based on a preset state vector, observation matrix, and contact resistance fitting equation; the load current and surface temperature (contact resistance) are dynamically corrected based on the state equation.

[0085] Specifically, taking into account measurement noise and model uncertainty, the following state equation is used to update the contact resistance trend:

[0086] Where xk is the state vector (containing the optimized Rc_optimized and the rate-of-change optimized Rc_optimized for subsequent evaluation), and zk is the observation value, which is the Kalman filter dynamic correction estimate.

[0087] Furthermore, the load current and surface temperature are time-aligned using the built-in clock of the miniature flow-temperature composite sensor; time alignment is also performed based on a preset sensor response delay compensation amount and the time of the load current and surface temperature.

[0088] It should be noted that time synchronization and data alignment are achieved through the sensor's built-in clock, ensuring time alignment of current and temperature data. The actual sampling time difference is corrected as follows:

[0089] in, The amount of compensation for sensor response delay can be set between 1 and 10 ms.

[0090] Furthermore, the diagnostic results of the cable joints are transmitted to a pre-set monitoring platform; the diagnostic results of the cable joints can be viewed in real time based on the monitoring platform.

[0091] Furthermore, based on the diagnostic results, corresponding early warning information is generated; and the early warning information is sent to preset push channels.

[0092] The warning information should include at least the warning level, parameter values, and handling suggestions; the push channels should include at least the monitoring center's large screen, mobile APP, SMS (for orange and above warnings), and email (daily summary).

[0093] Therefore, through a multi-channel information push system, early warning information is simultaneously sent to the monitoring center's large screen, mobile APP, SMS (orange and above warnings), and email (daily summary) to ensure timely and accurate transmission of early warning information and support rapid decision-making and response.

[0094] Furthermore, the electromagnetic noise intensity at the cable joint is obtained; if the electromagnetic noise intensity exceeds a preset electromagnetic noise intensity threshold, adaptive band-stop filtering is performed to suppress power frequency interference and random noise.

[0095] Therefore, this application utilizes a TMR-temperature miniature composite sensor to simultaneously acquire the load current and surface temperature of cable joints, and uses the thermal balance equation to invert the contact resistance value, thereby achieving an accurate assessment of the joint's health status. Based on the dynamic trend analysis of the condition indication ratio, early degradation of contact resistance can be identified, overcoming the hysteresis limitation of traditional temperature threshold alarms and enabling predictive maintenance. The non-contact measurement method avoids damage to the original circuit structure. Under complex operating conditions such as load fluctuations and ambient temperature changes, the condition indication ratio effectively eliminates the interference of current and ambient temperature on the diagnostic results, improving the robustness of the condition assessment. At a deeper level, the ability to accurately assess the contact resistance of cable joints allows maintenance personnel to promptly detect potential defects such as loose joints and oxidation, shifting from "reactive maintenance" to "predictive maintenance." Early warnings can prevent power outages caused by overheating of joints, significantly improving power supply reliability. This requires no modification to existing equipment, is easy to install, and can drastically reduce the frequency and cost of manual inspections during maintenance, extending equipment maintenance cycles. High-reliability diagnostics reduce false alarms and over-maintenance, avoiding unplanned downtime losses. It is suitable for intelligent upgrades in scenarios such as urban power grids and industrial parks.

[0096] Figure 2 This is a schematic diagram of the structure of a cable joint condition assessment device based on flow temperature according to an embodiment of this application; as shown. Figure 2 As shown, the cable joint condition assessment device 200 based on flow temperature according to an embodiment of this application may specifically include: Measurement module 201 is used to simultaneously measure the load current and surface temperature of the cable joint using a miniature flow-temperature composite sensor mounted on the surface of the cable joint.

[0097] The processing module 202 is used to perform real-time preprocessing on the load current and surface temperature to obtain the effective load current and effective surface temperature under steady-state conditions after preprocessing.

[0098] The calculation module 203 is used to monitor the ambient temperature of the cable joint in real time. Based on the effective load current, effective surface temperature and ambient temperature of the cable joint, and combined with the preset heat balance equation, the contact resistance of the cable joint is obtained by inversion.

[0099] The evaluation module 204 is used to calculate the corresponding status indication ratio based on load current, surface temperature and ambient temperature, evaluate the operating status of the cable joint based on contact resistance and status indication ratio and provide corresponding early warnings.

[0100] In one possible implementation, the processing module is specifically used for: The load current and surface temperature are filtered by the sliding window averaging method with a target window length, and the load current and surface temperature are compensated and corrected by a preset temperature gradient to identify abnormal load current and abnormal surface temperature. Abnormal load current and abnormal surface temperature are eliminated, and load current and surface temperature with current fluctuation less than the preset current fluctuation rate and temperature change rate less than the preset temperature change rate are selected as the effective load current and effective surface temperature under steady-state conditions.

[0101] In one possible implementation, the computing module is specifically used for: The comprehensive heat dissipation coefficient and effective heat dissipation area are obtained based on the pre-stored connector parameter database, and the corresponding inversion formula is determined based on the heat balance equation. The effective load current, effective surface temperature, ambient temperature, comprehensive heat dissipation coefficient, and effective heat dissipation area are input into the inversion formula to calculate the contact resistance of the cable joint.

[0102] In one possible implementation, the evaluation module is specifically used for: Define pre-defined multi-dimensional evaluation indicators; among which, the evaluation indicators include at least electrical performance indicators, relative change indicators, and thermal performance indicators; the electrical performance indicators are determined by contact resistance, warning value, and safety threshold; the relative change indicators are determined by state indication ratio, baseline value, and change threshold; the thermal performance indicators are determined by temperature indicators, second warning value, and second safety threshold; the temperature indicators are determined by surface temperature or surface temperature change value. When the temperature index exceeds the second safety threshold, the highest level temperature warning is triggered directly; when the temperature index exceeds the second warning value, the corresponding temperature warning flag is marked. The basic warning level is determined based on a combination of contact resistance, warning value, safety threshold, and status indication ratio; different levels of basic warning correspond to different colors, conditions, and measures. In response to the occurrence of a temperature warning and the basic warning level being the target basic warning level, the warning level will be dynamically adjusted.

[0103] In one possible implementation, the apparatus further includes: The first acquisition module is used to perform multiple measurements on the cable joint. Based on the load current, surface temperature and ambient temperature obtained from each measurement, it obtains the corresponding current data matrix, joint temperature matrix and ambient temperature matrix respectively. Based on the current data matrix, joint temperature matrix and ambient temperature matrix, it obtains the vector-calculated state indication ratio through element-by-element multiplication. The second acquisition module is used to determine the thermal conductivity, convective heat dissipation coefficient and radiative heat dissipation coefficient of the cable joint based on the joint parameter database, obtain the formula for the comprehensive heat dissipation coefficient based on the state indication ratio and the thermal conductivity, convective heat dissipation coefficient and radiative heat dissipation coefficient of the cable joint, and eliminate the calibration error of the comprehensive heat dissipation coefficient based on the formula for the comprehensive heat dissipation coefficient.

[0104] In one possible implementation, the apparatus further includes: The third acquisition module is used to accumulate time steps based on a preset initial time and multiple time points to obtain the corresponding time parameter vector, and to measure the contact resistance matrix of the cable joint at multiple time points based on the time parameter vector. The fourth acquisition module is used to perform a second-order fitting of the contact resistance matrix based on the least squares method, transforming the discrete contact resistance points in the contact resistance matrix into a continuous trend, obtaining the contact resistance fitting equation, and obtaining the time-optimized contact resistance based on the contact resistance fitting equation.

[0105] In one possible implementation, the apparatus further includes: The first synchronization module is used to time-align the load current and surface temperature using the clock built into the miniature flow-temperature composite sensor. The second synchronization module is used for time alignment based on a preset sensor response delay compensation amount and the time of load current and surface temperature.

[0106] The cable joint condition assessment device based on flow temperature provided in this application synchronously measures the load current and surface temperature of the cable joint using a miniature flow temperature composite sensor installed on the surface of the cable joint. The load current and surface temperature are preprocessed in real time to obtain the effective load current and effective surface temperature under steady-state conditions after preprocessing. The ambient temperature of the cable joint is monitored in real time. Based on the effective load current, effective surface temperature, and ambient temperature of the cable joint, and combined with a preset heat balance equation, the contact resistance of the cable joint is obtained by inversion. The corresponding state indication ratio is calculated based on the load current, surface temperature, and ambient temperature. The operating status of the cable joint is assessed based on the contact resistance and the state indication ratio, and corresponding early warnings are issued. This flow temperature-based cable joint condition assessment device synchronously collects load current and joint temperature data of the cable joint using flow temperature composite sensing technology. It inverts the contact resistance value based on the heat balance equation and combines the contact resistance value and the state indication ratio to assess the operating status of the cable joint and issue early warnings. This can meet the monitoring needs of cable joints in multiple scenarios and improve the application scope of monitoring. By using quantitative indicators to assess the status of the cable joint and provide early warnings, it improves the accuracy of the analysis of the operating status of the cable joint and realizes early fault warnings.

[0107] like Figure 3As shown in the embodiment of this application, an electronic device 300 includes a processor 301, a memory 302, and a bus. The memory 302 stores machine-readable instructions that can be executed by the processor 301. When the electronic device is running, the processor 301 communicates with the memory 302 via the bus. The processor 301 executes the machine-readable instructions to perform the steps of the above-described method for evaluating the condition of cable connectors based on flow temperature.

[0108] Specifically, the memory 302 and processor 301 can be general-purpose memory and processor, without any specific limitations. When the processor 301 runs the computer program stored in the memory 302, it can execute the above-mentioned cable joint status evaluation method based on flow temperature.

[0109] Corresponding to the above-described method for assessing the condition of cable joints based on flow temperature, this application also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, performs the steps of the above-described method for assessing the condition of cable joints based on flow temperature.

[0110] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems and devices described above can be referred to the corresponding processes in the method embodiments, and will not be repeated here. In the several embodiments provided in this application, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. The device embodiments described above are merely illustrative. For example, the division of modules is only a logical functional division, and in actual implementation, there may be other division methods. Furthermore, multiple modules or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed mutual coupling or direct coupling or communication connection can be through some communication interfaces; the indirect coupling or communication connection of devices or modules can be electrical, mechanical, or other forms.

[0111] The modules described as separate components may or may not be physically separate. The components shown as modules may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0112] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0113] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a processor-executable, non-volatile, computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the deployment methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, ROM, RAM, magnetic disks, or optical disks.

[0114] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for assessing the condition of cable joints based on flow temperature, characterized in that, The method includes: The load current and surface temperature of the cable joint are simultaneously measured by a miniature flow-temperature composite sensor mounted on the surface of the cable joint. The load current and the surface temperature are preprocessed in real time to obtain the effective load current and effective surface temperature under steady-state conditions after preprocessing. The ambient temperature of the cable joint is monitored in real time. Based on the effective load current, effective surface temperature and ambient temperature of the cable joint, and combined with the preset heat balance equation, the contact resistance of the cable joint is obtained by inversion. The corresponding status indication ratio is calculated based on the load current, the surface temperature, and the ambient temperature. The operating status of the cable joint is evaluated based on the contact resistance and the status indication ratio, and corresponding early warnings are issued.

2. The method according to claim 1, characterized in that, The real-time preprocessing of the load current and the surface temperature includes: The load current and the surface temperature are filtered by a sliding window averaging method with a target window length, and a preset temperature gradient is applied for compensation correction to identify abnormal load current and abnormal surface temperature. The abnormal load current and the abnormal surface temperature are removed, and the load current and surface temperature with current fluctuation less than the preset current fluctuation rate and temperature change rate less than the preset temperature change rate are selected as the effective load current and effective surface temperature under steady-state conditions.

3. The method according to claim 1, characterized in that, The contact resistance of the cable joint is obtained by inverting the process using a preset heat balance equation, including: The comprehensive heat dissipation coefficient and effective heat dissipation area are obtained based on the pre-stored connector parameter database, and the corresponding inversion formula is determined based on the heat balance equation. The effective load current, the effective surface temperature, the ambient temperature, the comprehensive heat dissipation coefficient, and the effective heat dissipation area are input into the inversion formula to calculate the contact resistance of the cable joint.

4. The method according to claim 1, characterized in that, The process of evaluating the operating status of the cable joint based on the contact resistance and the status indication ratio, and issuing corresponding early warnings, includes: A multi-dimensional evaluation index is defined; wherein the evaluation index includes at least electrical performance index, relative change index, and thermal performance index; the electrical performance index is determined by the contact resistance, warning value, and safety threshold; the relative change index is determined by the state indication ratio, baseline value, and change threshold; the thermal performance index is determined by the temperature index, second warning value, and second safety threshold; the temperature index is determined by the surface temperature or surface temperature change value. When the temperature index exceeds the second safety threshold, the highest level temperature warning is triggered directly; when the temperature index exceeds the second warning value, the corresponding temperature warning flag is marked. The basic warning level is determined based on the combination of the contact resistance, the warning value, the safety threshold, and the status indication ratio; wherein, different levels of basic warning correspond to different colors, conditions, and measures; In response to the occurrence of a temperature warning and the basic warning level being the target basic warning level, the warning level will be dynamically adjusted.

5. The method according to claim 3, characterized in that, The method further includes: The cable joint is measured multiple times. Based on the load current, surface temperature and ambient temperature obtained from each measurement, the corresponding current data matrix, joint temperature matrix and ambient temperature matrix are obtained respectively. Based on the current data matrix, the joint temperature matrix and the ambient temperature matrix, the vector-calculated state indication ratio is obtained by element-wise multiplication. Based on the connector parameter database, the thermal conductivity, convective heat dissipation coefficient, and radiative heat dissipation coefficient of the cable connector are determined. Based on the state indication ratio and the thermal conductivity, convective heat dissipation coefficient, and radiative heat dissipation coefficient of the cable connector, a formula for the comprehensive heat dissipation coefficient is obtained, and the calibration error of the comprehensive heat dissipation coefficient is eliminated based on the formula for the comprehensive heat dissipation coefficient.

6. The method according to claim 1, characterized in that, The method further includes: Based on a preset initial time and multiple time points, an accumulated time step is performed to obtain a corresponding time parameter vector, and based on the time parameter vector, the contact resistance matrix of the cable joint is measured at multiple time points. The contact resistance matrix is ​​fitted twice using the least squares method, transforming the discrete contact resistance points in the matrix into a continuous trend, thus obtaining the contact resistance fitting equation. Based on the contact resistance fitting equation, the time-optimized contact resistance is obtained.

7. The method according to claim 1, characterized in that, The method further includes: The load current and the surface temperature are time-aligned using a clock built into the miniature flow-temperature composite sensor. Time alignment is performed based on a preset sensor response delay compensation amount and the time of the load current and the surface temperature.

8. A cable joint condition assessment device based on flow temperature, characterized in that, The device includes: The measurement module is used to simultaneously measure the load current and surface temperature of the cable joint using a miniature flow-temperature composite sensor mounted on the surface of the cable joint. The processing module is used to perform real-time preprocessing on the load current and the surface temperature to obtain the effective load current and effective surface temperature under steady-state conditions after preprocessing. The calculation module is used to monitor the ambient temperature of the cable joint in real time, and based on the effective load current, effective surface temperature and ambient temperature of the cable joint, combined with the preset heat balance equation, the contact resistance of the cable joint is obtained by inversion. The evaluation module is used to calculate the corresponding status indication ratio based on the load current, the surface temperature and the ambient temperature, evaluate the operating status of the cable joint based on the contact resistance and the status indication ratio and issue corresponding early warnings.

9. An electronic device, characterized in that, include: The device includes a processor, a memory, and a bus. The memory stores machine-readable instructions executable by the processor. When the electronic device is running, the processor communicates with the memory via the bus. When the machine-readable instructions are executed by the processor, they perform the steps of the flow temperature-based cable joint condition assessment method as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, performs the steps of the flow temperature-based cable joint condition assessment method as described in any one of claims 1 to 7.

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