Temperature monitoring method of cable joint and cable joint

Abstract

The invention relates to the technical field of cable monitoring, and discloses a cable joint temperature monitoring method and a cable joint, and the method comprises the steps: obtaining the real-time insulating layer temperature data of the cable joint based on a miniature temperature sensor, and obtaining the real-time environment data of the cable joint based on an auxiliary sensor; comparing the real-time insulating layer temperature data with a real-time environment temperature value, and determining the thermal radiation direction of the cable joint; determining a temperature difference value between the real-time insulating layer temperature data and the real-time environment temperature value, and determining a predicted temperature value of the conductor crimping layer according to the temperature difference value based on the heat radiation direction; determining a predicted temperature change rate of the conductor crimping layer according to the predicted temperature value; the real-time load current of the cable connector is obtained, and the real-time temperature change rate is determined; and determining a difference ratio between the predicted temperature change rate and the real-time temperature change rate, and judging whether the temperature monitoring of the cable joint is abnormal or not. According to the invention, accurate temperature prediction and reliable abnormity judgment of the cable joint are realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cable monitoring, in particular to a temperature monitoring method of a cable joint and the cable joint. BACKGROUND

[0002] With the continuous expansion of the scale of the power system and the improvement of the complexity of the power transmission and distribution network, the cable joint as a key connecting component in the power transmission system is directly related to the safety and stability of the entire power grid. In actual operation, the cable joint is prone to local overheating due to factors such as increased contact resistance, poor crimping, insulation aging, or external environmental changes, which may further cause insulation breakdown, short circuit, and even fire accidents.

[0003] At present, the monitoring of the temperature of the cable joint mainly relies on infrared temperature measurement, optical fiber temperature measurement, or external temperature sensors. However, these methods generally have problems such as response lag, inaccurate measurement position, and susceptibility to environmental interference, making it difficult to truly reflect the actual temperature changes of the conductor crimping layer inside the cable joint. Especially, the conductor crimping layer is wrapped by multiple layers of insulation and shielding structure, so the traditional external temperature measurement method cannot directly obtain its temperature information, resulting in insufficient early warning capability for potential thermal faults. In addition, even if an embedded temperature sensor is used in the prior art, it often only focuses on the temperature data at a single position, without fully considering the influence of environmental temperature and humidity on the temperature reading of the insulation layer, and lacking a dynamic prediction and abnormal judgment mechanism for the temperature of the conductor crimping layer, thereby limiting the accuracy and intelligent level of the temperature monitoring system.

[0004] Therefore, there is an urgent need for a monitoring method that can comprehensively consider environmental factors, load current, and temperature change characteristics to accurately predict and reliably judge the temperature of the conductor crimping layer. SUMMARY

[0005] The purpose of the present application is to provide a temperature monitoring method of a cable joint and the cable joint, which aims to solve one or more of the problems in the prior art, such as the inability to accurately obtain the real temperature of the conductor crimping layer, the insulation layer temperature data being susceptible to environmental factors, the lack of effective prediction and abnormal identification mechanism for temperature change trend, and the lack of dynamic correction and reliability evaluation of temperature monitoring results.

[0006] The present application provides a temperature monitoring method of a cable joint, comprising: a plurality of miniature temperature sensors are pre-buried in different positions of the insulation layer of the cable joint, real-time insulation layer temperature data of the cable joint is obtained based on the miniature temperature sensors, and an auxiliary sensor is deployed in the external environment of the cable joint, real-time environmental data of the cable joint is obtained based on the auxiliary sensor, and the real-time environmental data includes real-time environmental temperature value and real-time environmental humidity value; synchronizing the real-time insulation layer temperature data and the real-time environment data in time, and comparing the real-time insulation layer temperature data with the real-time environment temperature value after processing, and determining the heat radiation direction of the cable joint according to the comparison result; determining the temperature difference between the real-time insulation layer temperature data and the real-time environment temperature value, adjusting the real-time insulation layer temperature data according to the temperature difference based on the heat radiation direction, and determining the predicted temperature value of the conductor compression layer of the cable joint; determining the predicted temperature change rate of the conductor compression layer according to the predicted temperature value, obtaining the real-time load current of the cable joint, and determining the real-time temperature change rate of the conductor compression layer according to the real-time load current; determining the difference ratio between the predicted temperature change rate and the real-time temperature change rate, and determining whether the cable joint is abnormal in temperature monitoring according to the difference ratio.

[0007] Preferably, before comparing the real-time insulation layer temperature data with the real-time environment temperature value, the method further comprises: comparing the environment humidity value with a preset humidity value, and if the environment humidity value is greater than or equal to the preset humidity value, performing credibility inspection on the real-time insulation layer temperature data and the real-time environment temperature value; otherwise, not performing credibility inspection; performing credibility inspection, specifically, comparing the detection data of the micro temperature sensor or the auxiliary sensor with the detection data of the adjacent sensor to determine the temperature deviation degree, and if the temperature deviation degree is greater than a preset deviation degree, determining that the corresponding real-time insulation layer temperature data or real-time environment temperature value is not credible and is to be excluded.

[0008] Preferably, comparing the real-time insulation layer temperature data with the real-time environment temperature value, and determining the heat radiation direction of the cable joint according to the comparison result, specifically comprises: comparing the real-time insulation layer temperature data with the real-time environment temperature value, and if the real-time insulation layer temperature data is greater than or equal to the real-time environment temperature value, determining that the heat radiation direction of the cable joint is a positive heat radiation direction; if the real-time insulation layer temperature data is less than the real-time environment temperature value, determining that the heat radiation direction of the cable joint is a negative heat radiation direction; wherein, the positive heat radiation direction is that the cable joint transfers heat to the environment, and the negative heat radiation direction is that the environment transfers heat to the cable joint.

[0009] Preferably, adjusting the real-time insulation layer temperature data according to the temperature difference based on the heat radiation direction, specifically comprises: If the heat radiation direction is a positive heat radiation direction, the real-time insulation layer temperature data is adjusted in a positive direction according to the temperature difference value; If the heat radiation direction is a negative heat radiation direction, the real-time insulation layer temperature data is adjusted in a negative direction according to the temperature difference value.

[0010] Preferably, the real-time insulation layer temperature data is adjusted according to the temperature difference value based on the heat radiation direction, and a predicted temperature value of the conductor compression layer of the cable joint is determined, specifically: If the heat radiation direction is a positive heat radiation direction, the predicted temperature value of the conductor compression layer = the real-time insulation layer temperature data + the temperature difference value × k1; If the heat radiation direction is a negative heat radiation direction, the predicted temperature value of the conductor compression layer = the real-time insulation layer temperature data - the temperature difference value × k2; Wherein, k1 represents a positive heat radiation direction adjustment coefficient, k2 represents a negative heat radiation direction adjustment coefficient, and the value range of k1 and k2 is 0-0.2.

[0011] Preferably, when the predicted temperature value is used to determine the predicted temperature change rate of the conductor compression layer, the predicted temperature change rate is determined according to the following formula: ΔTp=(Tp t -Tp t-1 ) / Δt; Wherein, ΔTp represents the predicted temperature change rate, Tp t represents the predicted temperature value at t time, Tp t-1 represents the predicted temperature value at t-1 time, and Δt represents the time interval.

[0012] Preferably, the real-time temperature change rate of the conductor compression layer is determined according to the real-time load current, specifically: The real-time current square of the cable joint is calculated according to the real-time load current; The real-time temperature change rate of the conductor compression layer is determined according to the real-time current square; Wherein, the real-time temperature change rate is determined according to the following formula: ΔTr=KI 2 ; Wherein, ΔTr represents the real-time temperature change rate, K represents a real-time temperature change rate adjustment coefficient, and I represents the real-time load current.

[0013] Preferably, when the difference ratio between the predicted temperature change rate and the real-time temperature change rate is determined, the difference ratio is determined according to the following formula: B=|predicted temperature change rate-real-time temperature change rate| / real-time temperature change rate; Wherein, B represents the difference ratio.

[0014] Preferably, whether the cable joint is abnormal in temperature monitoring is determined according to the difference ratio, in particular: The first difference ratio and the second difference ratio are preset, and the first difference ratio is smaller than the second difference ratio; Whether the cable joint is abnormal in temperature monitoring is determined according to the relationship between the difference ratio and the first difference ratio and the second difference ratio, and the abnormality level is determined; If the difference ratio is less than or equal to the first difference ratio, it is determined that the temperature of the cable joint is normal; If the difference ratio is greater than the first difference ratio and less than or equal to the second difference ratio, it is determined that the temperature of the cable joint is slightly abnormal in temperature monitoring; If the difference ratio is greater than the second difference ratio, it is determined that the temperature of the cable joint is severely abnormal in temperature monitoring.

[0015] The application further discloses a cable joint which can be subjected to temperature monitoring by using the temperature monitoring method of the cable joint.

[0016] Compared with the prior art, the application has the beneficial effects that the application provides a cable joint temperature monitoring method, a plurality of micro temperature sensors are embedded in the insulation layer, and an external environment auxiliary sensor (collecting environmental temperature and humidity) is combined to realize accurate perception and intelligent analysis of the internal thermal state of the cable joint.

[0017] The application compares the insulation layer temperature with the environmental temperature to determine the heat radiation direction, and dynamically adjusts the insulation layer temperature data based on the direction and the temperature difference, effectively compensating for the energy loss or gain in the heat conduction path, so as to calculate a conductor crimping layer predicted temperature value closer to the true value. An environmental humidity threshold judgment mechanism is introduced to perform credibility inspection and abnormality elimination on the sensor data under high humidity conditions, avoiding false high temperature signals caused by condensation, water vapor penetration and the like, and significantly improving the reliability of the system under harsh working conditions. The continuous predicted temperature value is used to calculate the predicted temperature change rate, and the real-time temperature change rate is calculated according to the square relationship of the real-time load current, and the difference ratio formed by comparison of the two can effectively identify whether the temperature abnormality is caused by electrical load change or internal fault, avoiding false positives or false negatives. Finally, based on the preset two-level difference ratio threshold, the system can automatically distinguish between "normal", "mild abnormality" and "severe abnormality", providing clear decision basis for operation and maintenance personnel, supporting preventive maintenance and rapid response to faults. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed in the embodiments or prior art description. Obviously, the drawings in the following description only are a part of the present application, and for those skilled in the art, other drawings can be obtained without creative effort based on the provided drawings.

[0019] Figure 1 is a flowchart of a temperature monitoring method of a cable joint. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present application will be clearly and completely described in the following with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present application.

[0021] As shown in Figure 1 , the present application provides a temperature monitoring method of a cable joint, comprising: pre-burying a plurality of micro temperature sensors in different positions in the insulation layer of the cable joint, acquiring real-time insulation layer temperature data of the cable joint based on the micro temperature sensors, and deploying auxiliary sensors in the external environment of the cable joint, acquiring real-time environmental data of the cable joint based on the auxiliary sensors, the real-time environmental data including real-time environmental temperature value and real-time environmental humidity value; performing time synchronization processing on the real-time insulation layer temperature data and the real-time environmental data, and after processing, comparing the real-time insulation layer temperature data with the real-time environmental temperature value, and determining the heat radiation direction of the cable joint according to the comparison result; determining the temperature difference value between the real-time insulation layer temperature data and the real-time environmental temperature value, adjusting the real-time insulation layer temperature data according to the temperature difference value based on the heat radiation direction, and determining the predicted temperature value of the conductor compression layer of the cable joint; determining the predicted temperature change rate of the conductor compression layer according to the predicted temperature value, acquiring the real-time load current of the cable joint, and determining the real-time temperature change rate of the conductor compression layer according to the real-time load current; determining the difference ratio between the predicted temperature change rate and the real-time temperature change rate, and determining whether the cable joint is temperature monitoring abnormal according to the difference ratio.

[0022] The application realizes accurate prediction of the temperature of the internal core heating area (the conductor compression layer) of the cable joint by combining the pre-embedded micro temperature sensor in the cable joint insulation layer with the externally deployed auxiliary sensor. The micro temperature sensor directly senses the temperature at different positions of the insulation layer, providing raw data for internal temperature field analysis. The environmental temperature and humidity data collected by the auxiliary sensor, especially the environmental temperature value consistent with the detection position of the micro temperature sensor, provide key evidence for eliminating the interference of environmental factors on the insulation layer temperature measurement. Time synchronization processing ensures the consistency of temperature data and environmental data in the time dimension, laying a reliable foundation for subsequent comparative analysis. By comparing the real-time insulation layer temperature data with the environmental temperature value, the heat radiation direction is determined, and the insulation layer temperature data is adjusted based on the temperature difference, which can effectively eliminate the influence of external environmental heat radiation or cold radiation on the measurement results, thereby more accurately calculating the predicted temperature value of the conductor compression layer, overcoming the defect that the traditional external temperature measurement method cannot reflect the internal real temperature. Further introducing the difference ratio analysis between the predicted temperature change rate and the real-time temperature change rate determined based on the real-time load current not only considers the static value of the temperature, but also focuses on the dynamic change trend of the temperature over time and its relevance to the load current, which can more sensitively capture early temperature abnormalities caused by potential faults such as increased contact resistance of the cable joint, achieving multi-dimensional and high-precision monitoring of the temperature state of the cable joint, which helps to timely discover safety hazards and improve the safety and reliability of the power system operation.

[0023] Specifically, several micro temperature sensors are pre-embedded at different positions in the insulation layer: during the manufacturing or installation of the cable joint, small-sized, high-voltage-resistant, and aging-resistant temperature sensing elements (such as thermistors, digital temperature chips, or fiber optic grating sensors) are embedded in multiple key areas inside the insulation layer, such as the inner side near the conductor compression layer, the middle of the insulation layer, and the outer side near the shielding layer. This distributed arrangement can capture the temperature gradient distribution along the radial or axial direction of the insulation layer, avoiding information loss caused by single-point measurement. Real-time insulation layer temperature data is obtained by continuously collecting temperature signals output by each micro sensor through wired or wireless methods (such as radio frequency, near-field communication, or embedded bus), and forming a time series data stream at a set sampling frequency (such as once per second or multiple times per minute). The auxiliary sensor is deployed in the external environment of the cable joint, which means that an environmental temperature and humidity sensor is fixedly installed near the cable joint housing, on the installation support, or in the surrounding air, for synchronous monitoring of the thermal and humid state of the external space where the joint is located. This deployment should ensure that the sensor is not directly exposed to sunlight or soaked in rainwater, but can accurately reflect the joint operating environment. Real-time environmental data includes real-time environmental temperature value and real-time environmental humidity value, emphasizing the completeness of environmental parameters, where humidity information is not only used to judge the risk of condensation, but also as a key input for subsequent data credibility verification, and environmental temperature is used for comparison with insulation layer temperature to determine the heat flow direction.

[0024] For example, in a 10 kV XLPE power cable joint, 4 micro temperature sensors (such as DS18B20 package improvement) are evenly embedded in the insulation layer along the circumferential direction, located at radial depths of 2 mm, 5 mm, 8 mm, and 10 mm from the surface of the conductor compression layer, respectively; meanwhile, 1 each is arranged at both axial ends, for a total of 6 measuring points, covering the hot spot prone area. In the air about 5 cm outside the outer metal shielding layer of the joint, an integrated temperature and humidity sensor module (such as SHT35) is installed, which is packaged by a waterproof and breathable film, fixed to the inner wall of the joint protection box, to avoid direct contact with the metal surface causing heat conduction distortion. The system synchronously collects data from all 7 sensors every 10 seconds: 6 channels of insulation layer temperature (such as 68.2℃, 65.5℃, 62.1℃, 60.3℃, 63.7℃, and 61.9℃, respectively) and 1 set of environmental data (such as ambient temperature 32.5℃, relative humidity 78%). These data are then sent to the central processing unit for time alignment, thermal radiation direction determination, and subsequent prediction model operation.

[0025] Specifically, the micro temperature sensor can use any micro temperature measuring element suitable for high voltage insulation environment, such as thermocouple, thermistor, silicon-based integrated circuit temperature sensor, fiber Bragg grating (FBG) sensor, etc.; its packaging material can be epoxy resin, silicone rubber or ceramic, to ensure compatibility with the insulation layer material and not affect the dielectric properties. The embedded position can be adaptively laid according to the cable joint structure (such as straight-through, T-shaped branch), conductor cross-sectional area, compression process or historical failure statistical data, such as near the compression end face, stress cone area or insulation weak point. The auxiliary sensor can be deployed on the surface of the cable joint body (non-conductive area), in the air of the joint well, near the tunnel wall, or integrated into the intelligent terminal shell; it can also use multiple auxiliary sensors to form an environmental monitoring array, taking the average or main value to improve the representativeness of environmental data. The micro sensor can be led out to the joint tail interface through embedded wires, or use passive wireless methods (such as LC resonance, RFID temperature tag) to realize non-contact transmission of energy and data; the auxiliary sensor can upload data through wired connection or low-power wide-area network (such as LoRa, NB-IoT), as long as it can realize time synchronization with the insulation layer temperature data.

[0026] Specifically, due to the different acquisition frequencies, communication paths or processing delays of the micro temperature sensor and auxiliary environmental sensor, the original data of the two types of sensors may be misaligned in the time axis by microseconds to seconds. Time synchronization processing refers to the process of aligning the two types of data to the same time reference through hardware triggering (such as a common clock source), software interpolation (such as linear or spline interpolation), or timestamp alignment, etc., to ensure that the data points used for subsequent comparative analysis correspond to the same physical time. This processing can be completed by a local edge computing unit or a remote monitoring platform. The direction of thermal radiation here is a broad sense of net heat flow direction, i.e., whether the heat is transferred from the inside of the cable joint to the external environment (positive direction) or from the environment to the inside of the joint (negative direction). This judgment is based on the basic principle of thermodynamics: heat spontaneously transfers from a high-temperature object to a low-temperature object. Therefore, if the insulation layer temperature is higher than the ambient temperature, it is determined that the "positive direction of thermal radiation"; otherwise, it is "negative direction of thermal radiation". This direction information directly determines whether the positive or negative compensation should be used in the subsequent temperature adjustment model.

[0027] For example: assuming that in a certain 110kV cable terminal joint monitoring system, in a certain monitoring period: at t=10:00:00, the insulation layer temperatures reported by the micro sensor are 72.3℃, 68.9℃, and 65.1℃; the auxiliary sensor reports the ambient temperature as 31.8℃ at t=10:00:01 and 31.5℃ at t=09:59:55; the system estimates the ambient temperature at t=10:00:00 to be about 31.75℃ through linear interpolation; comparing the highest insulation layer temperature 72.3℃ with 31.75℃, since 72.3℃>31.75℃, it is determined that the current direction of thermal radiation is positive, i.e., heat is being emitted from the cable joint to the environment. This judgment result will be used for the next step: applying positive adjustment (such as adding the temperature difference x k1) to the insulation layer temperature value of 72.3℃ to estimate a predicted value closer to the real temperature of the conductor compression layer.

[0028] Specifically, the time synchronization method can adopt any technical means that can realize data time alignment, such as hardware synchronization (such as common crystal oscillator, synchronous pulse trigger), software synchronization (timestamp calibration based on NTP / PTP protocol), or data post-processing synchronization (such as sliding window matching, dynamic time warping DTW algorithm), as long as the data used for comparison belongs to the same physical moment. When comparing insulation layer temperature data, single-point temperature (such as the sensor reading closest to the conductor), multi-point average, weighted average (weighted according to radial depth), or maximum / minimum value can be used. The specific strategy can be dynamically selected according to the joint structure, historical thermal distribution characteristics or safety margin requirements, which are all reasonable applications of the present scheme. If multiple auxiliary temperature sensors (such as one on the left, one on the right, one above and one below the joint) are deployed, their readings can be filtered, outliers can be removed, and the average value can be taken as the final ambient temperature value to improve the reliability of the comparison reference. This approach is still within the reasonable extension range of the present step.

[0029] Specifically, based on the direction of heat radiation, the real-time insulation layer temperature data is adjusted according to the temperature difference. If the heat radiation is in the positive direction (the joint generates heat to the environment), it means that the conductor compression layer temperature should be higher than the insulation layer temperature, so it needs to be corrected upwards based on the insulation layer temperature; otherwise, if it is in the negative direction (the environment transmits heat to the joint), the conductor compression layer is lower than the insulation layer temperature, and needs to be corrected downwards. This direction-sensitive adjustment mechanism avoids systematic bias caused by indiscriminate compensation.

[0030] Specifically, the predicted temperature change rate of the conductor compression layer is determined according to the predicted temperature value. The "predicted temperature value" here is the estimated temperature of the conductor compression layer obtained by correcting the insulation layer temperature and the ambient temperature in the previous step. The predicted temperature change rate reflects the time derivative of the actual heat accumulation or heat dissipation process, i.e. the rising or falling rate of the predicted temperature per unit time, which embodies the system's perception ability of the history evolution of the thermal state. The real-time load current can be obtained through conventional power monitoring devices such as current transformers (CT), Hall sensors or smart meters, which represents the actual current flowing through the cable joint conductor. The current is the fundamental cause of conductor heating, and its square value is proportional to the Joule heat power.

[0031] Specifically, the real-time load current can come from local sensors, upper-level substation SCADA systems, smart terminal communication interfaces or cloud dispatch platforms, as long as it can be aligned in time with the temperature data and represent the real current flowing through the joint.

[0032] In some embodiments of the present application, before comparing the real-time insulation layer temperature data with the real-time ambient temperature value, the method further comprises: comparing the ambient humidity value with a preset humidity value, if the ambient humidity value is greater than or equal to the preset humidity value, performing a reliability test on the real-time insulation layer temperature data and the real-time ambient temperature value; otherwise, not performing the reliability test; and performing the reliability test, specifically: comparing the detection data of the micro temperature sensor or the auxiliary sensor with the detection data of the adjacent sensor to determine a temperature deviation degree, if the temperature deviation degree is greater than a preset deviation degree, determining that the corresponding real-time insulation layer temperature data or real-time ambient temperature value is unreliable and is to be eliminated.

[0033] Specifically, the present scheme is to improve the reliability of temperature monitoring data in a high-humidity environment. Since high environmental humidity can cause condensation on the sensor surface, moisture absorption of insulation materials, or moisture absorption of measurement circuits, resulting in temperature reading drift or distortion, the present application introduces a humidity threshold judgment mechanism: only when the ambient humidity reaches or exceeds the preset value, the reliability test of temperature data is started, avoiding unnecessary calculation overhead in dry environment; while in high humidity working condition, through the data consistency check between sensors, abnormal measuring points are identified and eliminated in time, ensuring that the data relied on for subsequent thermal radiation direction judgment and temperature prediction is real and effective.

[0034] Specifically, before comparing the real-time insulation layer temperature data with the real-time ambient temperature value, the real-time ambient humidity value collected by the auxiliary sensor is first obtained, and compared with a preset humidity threshold (for example, 70% RH). If the real-time ambient humidity value is less than the preset humidity value, it indicates that the current environment is relatively dry, the risk of sensor moisture is low, and the data reliability is high, at this time, the subsequent temperature comparison step can be directly entered, without additional inspection. If the real-time ambient humidity value is greater than or equal to the preset humidity value, it is considered that there is a possibility of temperature measurement error caused by moisture interference, and the reliability test needs to be performed on the related temperature data.

[0035] The specific way of credibility check is: for each micro temperature sensor or auxiliary temperature sensor, the current detected temperature data is compared with the detection data of other sensors of the same type and adjacent in space. For example, the reading of a micro temperature sensor in an insulation layer should be similar to the readings of other micro temperature sensors in the same insulation layer at adjacent positions; similarly, the reading of a certain auxiliary environmental temperature sensor should also be basically consistent with the readings of other auxiliary temperature sensors deployed nearby. The system calculates the deviation (i.e. temperature deviation) between the sensor reading and the reading of the adjacent sensor of the same type, and if the deviation exceeds the pre-set allowed range (such as ±3℃), it is determined that the current output data of the sensor is not reliable, and is excluded or marked as invalid in subsequent processing, and no longer participates in the heat radiation direction judgment and temperature adjustment calculation. Through this mechanism, the risk of misjudgment caused by individual sensor failure or interference in a high humidity environment is effectively suppressed, and the robustness and accuracy of the entire temperature monitoring method are ensured.

[0036] It can be understood that by introducing the pre-set threshold value judgment mechanism of environmental humidity value, dynamic triggering of temperature data credibility check is realized. When the environmental humidity value reaches or exceeds the pre-set humidity value, it indicates that the environmental water vapor content is high at this time, which may cause the sensor surface to dew or the insulation layer to be damp, thereby affecting the accuracy of temperature measurement, at this time, the credibility check process is started, which can specifically check abnormal data; in a low humidity environment, the interference of environmental factors on the sensor is small, and the check can be skipped to improve the data processing efficiency. The credibility check compares the detection data of the same sensor with the data of the adjacent sensors of the same type, judges the temperature deviation by using the spatial correlation, and if the deviation exceeds the pre-set range, it is determined that the data is not reliable and is excluded, which effectively avoids abnormal data caused by single sensor failure or local environmental mutation from entering the subsequent analysis process, and improves the reliability of the original data.

[0037] In some embodiments of the present application, the real-time insulation layer temperature data is compared with the real-time environmental temperature value, and the heat radiation direction of the cable joint is determined according to the comparison result, specifically: comparing the real-time insulation layer temperature data with the real-time environmental temperature value, if the real-time insulation layer temperature data is greater than or equal to the real-time environmental temperature value, it is determined that the heat radiation direction of the cable joint is the positive heat radiation direction; if the real-time insulation layer temperature data is less than the real-time environmental temperature value, it is determined that the heat radiation direction of the cable joint is the negative heat radiation direction; wherein the positive heat radiation direction is that the cable joint transfers heat to the environment, and the negative heat radiation direction is that the environment transfers heat to the cable joint.

[0038] Specifically, the scheme is to accurately determine the net heat flow direction between the cable joint and the surrounding environment, and to provide a physical basis for the subsequent directional correction of the insulation layer temperature data. Since the actual temperature of the conductor compression layer cannot be directly measured, and there is a heat conduction relationship between it and the insulation layer, only by determining whether the heat is emitted from the joint interior to the outside or transmitted from the outside environment to the joint interior, can it be reasonably inferred whether the conductor compression layer temperature is higher or lower than the insulation layer temperature, so as to determine the direction of temperature compensation.

[0039] Specifically, after completing the time synchronization of the real-time insulation layer temperature data and the real-time environment temperature value, the system compares the two values. The "real-time insulation layer temperature data" here usually refers to the temperature value obtained from the micro temperature sensor embedded in the insulation layer, which can adopt the single-point maximum value, specific position value or representative value of multiple measuring points; the "real-time environment temperature value" comes from the auxiliary temperature sensor deployed in the external environment of the cable joint. If the real-time insulation layer temperature data is greater than or equal to the real-time environment temperature value, it indicates that the internal temperature of the cable joint is higher than the external environment, and the heat naturally flows from the high-temperature zone to the low-temperature zone, that is, from the cable joint to the surrounding environment, at this time the heat radiation direction is determined to be the positive direction of heat radiation. Conversely, if the real-time insulation layer temperature data is less than the real-time environment temperature value, it indicates that the environment temperature is higher, and the heat may be transmitted from the environment to the cable joint in the opposite direction, at this time the heat radiation direction is determined to be the negative direction of heat radiation.

[0040] Among them, the positive direction of heat radiation is defined as the process of heat transfer from the cable joint to the environment, corresponding to the conductor compression layer temperature should be higher than the insulation layer temperature; the negative direction of heat radiation is defined as the process of heat transfer from the environment to the cable joint, corresponding to the conductor compression layer temperature may be lower than or close to the insulation layer temperature. The direction judgment result is directly used for the adjustment mode selection (positive compensation or negative compensation) of the insulation layer temperature data in the subsequent steps, and is the key prerequisite for realizing the accurate estimation of the predicted temperature of the conductor compression layer.

[0041] It can be understood that by directly comparing the real-time insulation layer temperature data and the real-time environment temperature value, the determination standard of the heat radiation direction is proposed, and the positive direction of heat radiation (heat transfer from the cable joint to the environment) and the negative direction of heat radiation (heat transfer from the environment to the cable joint) are clearly defined, which intuitively reflects the heat exchange state between the cable joint and the environment.

[0042] In some embodiments of the present application, based on the heat radiation direction, the real-time insulation layer temperature data is adjusted according to the temperature difference value, specifically: if the heat radiation direction is the positive direction of heat radiation, the real-time insulation layer temperature data is adjusted in the positive direction according to the temperature difference value; if the heat radiation direction is the negative direction of heat radiation, the real-time insulation layer temperature data is adjusted in the negative direction according to the temperature difference value.

[0043] Specifically, the present scheme is to compensate the insulation layer temperature data physically according to the heat flow direction, so as to more accurately estimate the actual temperature of the conductor compression layer wrapped by the insulation layer. When the joint generates heat, the conductor temperature is higher than the insulation layer; when the ambient temperature is higher, the insulation layer may be temporarily higher or close to the conductor temperature. Therefore, the measured insulation layer temperature must be adjusted directionally according to the heat radiation direction to avoid deviation caused by indiscriminate correction.

[0044] After determining the heat radiation direction and calculating the temperature difference between the real-time insulation layer temperature and the ambient temperature, the system selects the corresponding adjustment mode according to the heat radiation direction. If the heat radiation direction is the positive direction of heat radiation (i.e. insulation layer temperature ≥ ambient temperature, heat is transferred from the cable joint to the environment), it indicates that the conductor compression layer acts as a heat source, and its temperature should be higher than the insulation layer temperature. Therefore, a positive adjustment should be made to the real-time insulation layer temperature data, i.e. adding a compensation amount related to the temperature difference, so that the prediction result is closer to the actual conductor temperature. If the heat radiation direction is the negative direction of heat radiation (i.e. insulation layer temperature < ambient temperature, heat is transferred from the environment to the cable joint), the conductor compression layer may be in a cooling state or less affected by environmental heating, and its temperature may be lower than or equal to the insulation layer temperature. At this time, a negative adjustment should be made to the real-time insulation layer temperature data, i.e. subtracting a compensation amount related to the temperature difference, to avoid overestimating the conductor temperature. This adjustment mechanism ensures that the predicted temperature value always conforms to the basic physical law of heat conduction, and improves the accuracy of subsequent temperature change rate calculation and abnormality judgment.

[0045] It can be understood that by making a targeted positive or negative adjustment to the real-time insulation layer temperature data according to the heat radiation direction, the deviation caused by environmental factors and heat transfer direction on the insulation layer temperature measurement can be effectively corrected. When the heat radiation direction is positive, it indicates that the self-heating of the cable joint dominates, and at this time, the temperature difference (the difference between the real-time insulation layer temperature data and the real-time ambient temperature value) is used for positive adjustment, which can more accurately reflect the contribution of the real heat accumulation caused by the internal loss of the joint to the insulation layer temperature. When the heat radiation direction is negative, the environment transfers heat to the cable joint, and by making a negative adjustment through the temperature difference, the superimposed effect of high ambient temperature on the insulation layer temperature can be better offset, so that the adjusted insulation layer temperature data is closer to its intrinsic temperature state without interference from external dominant heat transfer. This directional dynamic adjustment mechanism further optimizes the quality of the temperature parameter used as input for the subsequent prediction model, providing a more reliable data basis for improving the accuracy of conductor compression layer temperature prediction, and ensuring the scientificity and effectiveness of temperature data preprocessing under complex and variable heat exchange conditions.

[0046] In some embodiments of the present application, based on the heat radiation direction, the real-time insulation layer temperature data is adjusted according to the temperature difference value to determine the predicted temperature value of the conductor compression layer of the cable joint, specifically: if the heat radiation direction is a positive heat radiation direction, the predicted temperature value of the conductor compression layer = real-time insulation layer temperature data + temperature difference value x k1; if the heat radiation direction is a negative heat radiation direction, the predicted temperature value of the conductor compression layer = real-time insulation layer temperature data - temperature difference value x k2; wherein k1 represents a positive heat radiation direction adjustment coefficient, k2 represents a negative heat radiation direction adjustment coefficient, and the value range of k1 and k2 is 0-0.2.

[0047] Specifically, based on the determination of the heat flow direction, the proportional coefficient matched with the physical characteristics is introduced to quantitatively compensate the insulation layer temperature, so as to obtain the predicted value closer to the real temperature of the conductor compression layer.

[0048] After determining the heat radiation direction and the temperature difference value (i.e. the absolute value of the difference between the real-time insulation layer temperature and the real-time environment temperature), the system determines the predicted temperature value of the conductor compression layer according to the heat radiation direction using different calculation formulas. When the heat radiation direction is positive, it means that the cable joint generates heat inside and radiates heat outward, and the temperature of the conductor compression layer should be higher than that of the insulation layer. At this time, the predicted temperature value is equal to the real-time insulation layer temperature data plus the product of the temperature difference value and the positive adjustment coefficient k1; when the heat radiation direction is negative, it means that the environment temperature is higher than the insulation layer, and the heat may be transferred from the outside, and the temperature of the conductor compression layer may be lower than that of the insulation layer. At this time, the predicted temperature value is equal to the real-time insulation layer temperature data minus the product of the temperature difference value and the negative adjustment coefficient k2. Wherein, k1 and k2 are dimensionless empirical coefficients, and the value range is limited between 0 and 0.2. This range is a reasonable interval determined based on a large amount of experimental data and engineering experience, which can effectively reflect the typical temperature difference proportional relationship between the conductor and the insulation layer under different cable joint structures. The specific values of k1 and k2 need to be determined in advance through laboratory temperature rise test or field calibration according to the thermal conductivity of the insulation material used in the cable joint, the thickness of the insulation layer, the compression structure form and other factors, and different coefficient groups can be configured for different types of joints. Through this parameterized adjustment method based on physical characteristics, the universality of the prediction model is ensured.

[0049] It can be understood that by introducing the thermal radiation direction adjustment coefficients k1 and k2 and combining the temperature difference to construct a specific predicted temperature value calculation formula, the quantitative prediction of the conductor compression layer temperature is realized. When the thermal radiation direction is positive, the positive adjustment formula of “real-time insulation layer temperature data + temperature difference x k1” is used, where k1 is the positive direction adjustment coefficient, which can map the part of the heat accumulated in the insulation layer dominated by the joint internal loss to the conductor compression layer temperature according to the thermal conductivity characteristics (such as thermal conductivity and thickness) of the insulation layer material, ensuring the accurate quantization of the contribution of the internal heat source to the compression layer temperature; and when the thermal radiation direction is negative, the negative adjustment formula of “real-time insulation layer temperature data - temperature difference x k2” is used, where k2 is the negative direction adjustment coefficient, which can deduct the heat transferred from the environment to the joint from the insulation layer temperature according to the insulation layer material parameters, in order to eliminate the interference of environmental heat input on the intrinsic temperature of the compression layer. The value range of k1 and k2 is limited to 0-0.2 and calibrated by experiment, which not only avoids the prediction distortion caused by excessive adjustment, but also can be personalized according to the physical characteristics of different cable joints, so that the prediction formula has both universality and pertinence. This dual quantitative adjustment based on direction and coefficient converts the abstract heat transfer influence into a calculable mathematical model, providing a standardized and operable implementation path for the accurate prediction of the conductor compression layer temperature.

[0050] In some embodiments of the present application, when the predicted temperature change rate of the conductor compression layer is determined according to the predicted temperature value, the predicted temperature change rate is determined according to the following formula: ΔTp= (Tp t -Tp t-1 ) / Δt; wherein ΔTp represents the predicted temperature change rate, Tpt represents the predicted temperature value at time t, Tpt-1 represents the predicted temperature value at time t-1, and Δt represents the time interval.

[0051] Specifically, by using the predicted temperature values at consecutive time points, the application quantifies the change trend of the conductor compression layer temperature over time, thereby obtaining the predicted temperature change rate reflecting the actual thermal dynamic behavior. The change rate is used to compare with the theoretical temperature rise rate calculated based on the current, which is a key basis for subsequent judgment of whether there is an unexpected thermal anomaly.

[0052] Specifically, after obtaining the predicted temperature value Tpt of the conductor compression layer at the current time t and the predicted temperature value Tpt-1 at the previous time t-1, the system calculates the predicted temperature change rate ΔTp in unit time according to the difference between the two divided by the corresponding time interval Δt. Wherein, Tpt and Tpt-1 are both the estimated values of the conductor compression layer temperature corrected by the foregoing steps, and Δt is the time interval between two temperature predictions, which is usually determined by the system sampling period (such as 30 seconds, 1 minute, etc.).

[0053] It can be understood that by constructing the prediction temperature change rate calculation formula of "ΔTp= (Tpt-Tpt-1) / Δt", the dynamic trend of the conductor compression layer temperature is quantitatively characterized. In the formula, Tpt and Tpt-1 represent the prediction temperature values at two consecutive time points (t time point and t-1 time point) respectively, and the difference between the two directly reflects the absolute change of temperature in the unit time interval Δt. By comparing with the time interval Δt, the temperature change is converted from "static value" to "dynamic rate" index. This change rate calculation based on time series can sensitively capture the instantaneous rising and falling trend of the conductor compression layer temperature. For example, when ΔTp is positive and the absolute value is large, it indicates that the compression layer temperature is in a rapid rising stage, which may indicate that the contact resistance in the joint increases or the local overheating risk intensifies. When ΔTp is negative, it reflects that the temperature is gradually decreasing, which can be combined with the environmental conditions to determine whether it is a normal heat dissipation process or an abnormal cooling phenomenon. Compared with single temperature threshold judgment, the prediction temperature change rate ΔTp can better reflect the "acceleration" characteristics of temperature change, and provides a key dynamic basis for early fault warning. Through continuous monitoring of the change rate and threshold setting (such as triggering an alarm when the change rate exceeds a certain safe change rate threshold), potential thermal hazard development trends can be identified in advance before the temperature reaches the absolute dangerous value, so as to gain more sufficient disposal time for the operation and maintenance personnel.

[0054] In some embodiments of the present application, the real-time temperature change rate of the conductor compression layer is determined according to the real-time load current, specifically: the real-time current square of the cable joint is calculated according to the real-time load current; the real-time temperature change rate of the conductor compression layer is determined according to the real-time current square; wherein the real-time temperature change rate is determined according to the following formula: ΔTr=KI 2 ; wherein ΔTr represents the real-time temperature change rate, K represents the real-time temperature change rate adjustment coefficient, and I represents the real-time load current.

[0055] Specifically, based on the Joule heat principle, the present application uses the real-time load current to establish a theoretical temperature rise rate model of the conductor compression layer in an ideal normal state as a benchmark for judging whether there is abnormal heating. Since the conductor heating is mainly caused by the current passing through the resistance, the heat power is proportional to the square of the current, so the theoretical temperature change trend can be derived from the current, which is used for comparison with the actual observed thermal response.

[0056] Specifically, first, the real-time load current I flowing through the cable joint is obtained, and the square value I2 thereof is calculated. According to Joule's law, the heat power generated by the conductor is proportional to I2, and the temperature change rate depends on the relationship between the heat power and the heat capacity of the conductor. On this basis, a comprehensive adjustment coefficient K is introduced to convert the current square into the real-time temperature change rate ΔTr of the conductor compression layer, and the calculation formula is ΔTr = K I2. Wherein, K is a parameter related to the physical characteristics of the conductor, and its value is determined by the effective resistance, mass and specific heat capacity of the conductor compression layer, which reflects the temperature rise rate caused by unit joule heat. The coefficient can be determined in advance by theoretical calculation or experimental calibration, and can be configured for cable joints of different specifications or materials.

[0057] Specifically, according to the known two heat formulas Q = I 2 Rt and Q = mcΔT, the temperature change rate is related to the change rate of the square of the current multiplied by time. Q is heat, I is current, R is resistance, t is current time, m represents mass, unit is kilogram (kg); c represents specific heat capacity; ΔT represents temperature change.

[0058] The two formulas are combined to obtain: .

[0059] The derivative with respect to time is taken to obtain the temperature change rate as: ; Therefore, the real-time temperature change rate adjustment coefficient can be obtained, which is related to the cable resistance, cable mass and cable specific heat capacity.

[0060] It can be understood that by establishing the real-time temperature change rate calculation model of “ΔTr = KI2”, the direct correlation and quantification of the dynamic change of the conductor compression layer temperature based on the real-time load current are realized. In the formula, I represents the real-time load current, the square term I2 is directly related to the Joule heat loss (Q = I2Rt) of the cable joint, and is the core driving factor leading to the temperature change of the conductor compression layer. K as the real-time temperature change rate adjustment coefficient, comprehensively considers the influence of key physical parameters such as the resistance, mass m and specific heat capacity c of the conductor compression layer on the temperature change rate, the resistance determines the heat generation per unit time, and the mass and specific heat capacity determine the difficulty of temperature rise after the object absorbs heat, therefore the introduction of K value makes the model more accurately match the thermal characteristics of cable joints of different materials and structures. This calculation method directly links the real-time load current and the temperature change rate, which can quickly respond to the instantaneous influence of current fluctuation on the compression layer temperature: when the load current I increases, I2 increases in square, and ΔTr also significantly increases, which intuitively reflects the temperature rapid rising trend caused by current mutation; on the contrary, when the current decreases, ΔTr also decreases accordingly.

[0061] In some embodiments of the present application, when determining the difference ratio between the predicted temperature change rate and the real-time temperature change rate, the difference ratio is determined according to the following formula: B = |predicted temperature change rate - real-time temperature change rate| / real-time temperature change rate; wherein B represents the difference ratio.

[0062] It can be understood that by introducing the calculation formula of the difference ratio B, the quantitative evaluation of the deviation degree between the predicted temperature change rate and the real-time temperature change rate is realized. In the formula, the absolute difference between the two is represented by the numerator “|predicted temperature change rate - real-time temperature change rate|”, which clearly reflects the deviation amplitude of the predicted value from the real-time value; the denominator uses the real-time temperature change rate ΔTr as the reference for normalization, so that the B value can eliminate the influence of the magnitude of the temperature change rate itself, and more objectively measure the relative deviation degree. For example, when the real-time temperature change rate ΔTr is large (such as in the stage of rapid temperature rise caused by sudden increase of current), even if the absolute difference is large, if the B value is small, it still indicates that the prediction model has high consistency with the actual situation; on the contrary, if ΔTr is small but B is significantly large, it indicates that there is a large relative error in the prediction. This quantitative method of relative deviation provides a clear index for judging the accuracy and reliability of the prediction model: when the B value is within the preset threshold range, it means that the predicted temperature change rate can well follow the real-time temperature change rate, and the model is effective; when the B value exceeds the threshold, it means that the prediction has a significant deviation, which may be caused by factors such as model parameter drift, external environmental interference, or changes in the characteristics of the cable joint, at which time the system can trigger the calibration mechanism of the prediction model or issue a warning signal. Compared with simply comparing the absolute difference, the design of the difference ratio B is more practical in engineering, can adapt to the dynamic range of the temperature change rate under different load conditions, provides an important guarantee for the accuracy of subsequent fault warning based on predicted temperature, and helps operation and maintenance personnel to more accurately identify potential risks.

[0063] In some embodiments of the present application, whether the cable joint is temperature monitoring abnormal is determined according to the difference ratio, specifically: a first difference ratio and a second difference ratio are preset, the first difference ratio is smaller than the second difference ratio; whether the cable joint is temperature monitoring abnormal and the abnormal level are determined according to the relationship between the difference ratio and the first difference ratio and the second difference ratio; if the difference ratio is less than or equal to the first difference ratio, it is determined that the temperature of the cable joint is normal; if the difference ratio is greater than the first difference ratio and less than or equal to the second difference ratio, it is determined that the temperature monitoring of the cable joint is mildly abnormal; if the difference ratio is greater than the second difference ratio, it is determined that the temperature monitoring of the cable joint is severely abnormal.

[0064] In the present embodiment, the first difference ratio and the second difference ratio are not arbitrarily set, and can be determined based on the following basis and engineering practice.

[0065] For example, according to the normal thermal-electric characteristic calibration data of the cable joint: through laboratory or field temperature rise test on the same type and specification of cable joints under standard working conditions (such as rated current, environmental temperature and humidity, good crimping state), a large amount of comparison data of "predicted temperature change rate" and "real-time temperature change rate based on current calculation" is collected, and the difference proportion distribution range of the normal operation is counted. The first difference proportion is usually set near the upper limit of the distribution (for example, 95% confidence interval) to cover the normal fluctuation.

[0066] Or set the threshold according to the simulation test results of typical fault modes: for common abnormal conditions (such as loose crimping, contact surface oxidation, partial discharge, etc.), artificial construction of mild and severe fault samples, and recording the evolution characteristics of the difference proportion during operation. The second difference proportion is set at a clear dividing point between mild abnormality and severe abnormality to ensure that different risk levels can be effectively distinguished.

[0067] In addition, the threshold can also be determined according to the power equipment operation safety specifications and operation experience. Referring to the relevant standards of the state or industry (such as DL / T, IEC, etc. on cable joint temperature rise limit, fault early warning threshold), and combining the fault cases and disposal thresholds accumulated in the long-term operation of power grid enterprises, the first and second difference proportions are calibrated to make them meet the acceptable risk control level of actual engineering.

[0068] It can be understood that by setting the first difference proportion and the second difference proportion as two thresholds, and comparing the difference proportion B with the two thresholds, the classification judgment of the temperature monitoring abnormality degree of the cable joint is realized. This classification mechanism first determines the normal temperature by "the difference proportion is less than or equal to the first difference proportion", which provides a benchmark for stable system operation; then, when "the difference proportion is greater than the first difference proportion and less than or equal to the second difference proportion", it is defined as "mild abnormality", which means that the prediction model and the actual situation deviate to a certain extent, but it has not reached a serious degree, providing early warning for operation and maintenance personnel to facilitate timely preliminary investigation and model adjustment to avoid further expansion of the abnormality; when "the difference proportion is greater than the second difference proportion", it is determined as "severe abnormality", which means that the deviation between prediction and reality is relatively significant, which may indicate that the cable joint has a potential serious fault risk or the prediction model has a major problem, which needs to trigger high-level early warning and take emergency measures immediately. This multi-level abnormality division method, compared with the simple "normal / abnormal" binary judgment, can more accurately reflect the complex situation of temperature change, making the operation and maintenance decision more hierarchical and targeted, avoiding overreaction to slight deviation, and ensuring timely response to serious abnormality.

[0069] The application further discloses a cable joint which can be monitored by the temperature monitoring method of the cable joint.

[0070] The application provides a cable joint structure which is suitable for the temperature monitoring method, so that the temperature monitoring function is realized in the physical layer. Since the conductor crimping layer is wrapped by multiple layers of materials, the temperature cannot be directly measured from the outside, and the sensor must be integrated into the key position in the manufacturing or installation stage, so as to obtain effective data reflecting the internal thermal state. By embedding the miniature temperature sensor in the insulation layer and clearly arranging the order of each functional layer, the transmission element is ensured to be in a reasonable position which can sense the conductor heating and does not affect the electrical insulation performance, thereby providing a hardware basis for the whole monitoring method.

[0071] The cable joint adopts a typical multi-layer concentric structure, and sequentially comprises a conductor crimping layer, an insulation layer, a shielding layer and a sealing protection layer from inside to outside. The conductor crimping layer is used to realize the electrical connection of two cable conductors; the insulation layer is wrapped outside the conductor crimping layer and serves as the main insulation; the shielding layer is used to uniform the electric field and provide a grounding path; and the sealing protection layer protects the internal structure from the external environment such as moisture and dust. In the manufacturing process, a plurality of miniature temperature sensors are embedded in different positions inside the insulation layer, such as the inner side region close to the conductor crimping layer or the key hot spot region distributed along the axial direction. These sensors are small in size, high in pressure resistance and compatible with the insulation material, and can collect the temperature data inside the insulation layer in real time without affecting the electrical performance and mechanical strength of the cable joint. The structure design makes the "real-time insulation layer temperature data" required in the foregoing temperature monitoring method have a reliable source, so that the temperature of the conductor crimping layer is indirectly but effectively monitored.

[0072] Those skilled in the art will appreciate that embodiments of the application can be supplied as methods, systems or computer program products. Accordingly, the application can be embodied in the form of complete hardware embodiments, complete software embodiments or embodiments combining software and hardware aspects. Furthermore, the application can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROMs, optical storage media, etc.) having computer-usable program code embodied thereon.

[0073] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart or flowsheet block or blocks. Figure 1 one or more flowcharts and / or blocks Figure 1 means for functionally implementing the steps listed in the flowchart

[0074] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart or flowsheet block or blocks. Figure 1 one or more flowcharts and / or blocks Figure 1 means for functionally implementing the steps listed in the flowchart

[0075] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart or flowsheet block or blocks. Figure 1 one or more flowcharts and / or blocks Figure 1 means for functionally implementing the steps listed in the flowchart

[0076] Finally, it should be noted that the above-mentioned embodiments are merely intended for describing the technical solutions of the present application, but not for limiting it. Although the present application is described in detail with reference to the above embodiments, those skilled in the art should understand that the specific embodiments of the present application can be modified or replaced equivalently without departing from the spirit and scope of the present application, and any modification or equivalent replacement without departing from the spirit and scope of the present application should be covered in the protection scope of the claims of the present application.

Claims

1. A method of temperature monitoring of a cable joint, characterized by, The method comprises the following steps: embedding a plurality of micro temperature sensors at different positions in the insulation layer of the cable joint, obtaining real-time insulation layer temperature data of the cable joint based on the micro temperature sensors, and deploying auxiliary sensors in the external environment of the cable joint, obtaining real-time environmental data of the cable joint based on the auxiliary sensors, the real-time environmental data including real-time environmental temperature values and real-time environmental humidity values; time-synchronizing the real-time insulation layer temperature data and the real-time environmental data, and after processing, comparing the real-time insulation layer temperature data with the real-time environmental temperature values, and determining the heat radiation direction of the cable joint according to the comparison result; determining the temperature difference value between the real-time insulation layer temperature data and the real-time environmental temperature values, adjusting the real-time insulation layer temperature data according to the temperature difference value based on the heat radiation direction, and determining the predicted temperature value of the conductor compression layer of the cable joint; determining the predicted temperature change rate of the conductor compression layer according to the predicted temperature value, obtaining the real-time load current of the cable joint, and determining the real-time temperature change rate of the conductor compression layer according to the real-time load current; determining the difference ratio between the predicted temperature change rate and the real-time temperature change rate, and determining whether the cable joint is temperature monitoring abnormal according to the difference ratio.

2. The method of temperature monitoring of a cable joint according to claim 1, characterized in that, Before comparing the real-time insulation layer temperature data with the real-time environmental temperature values, the method further comprises the following steps: comparing the environmental humidity value with a preset humidity value, if the environmental humidity value is greater than or equal to the preset humidity value, performing credibility inspection on the real-time insulation layer temperature data and the real-time environmental temperature values; otherwise, not performing credibility inspection; performing credibility inspection, specifically: comparing the detection data of the micro temperature sensor or the auxiliary sensor with the detection data of the adjacent sensor to determine the temperature deviation degree, if the temperature deviation degree is greater than a preset deviation degree, determining that the corresponding real-time insulation layer temperature data or real-time environmental temperature value is not credible and is excluded.

3. The method of temperature monitoring of a cable joint according to claim 1, characterized in that, Comparing the real-time insulation layer temperature data with the real-time environmental temperature values, and determining the heat radiation direction of the cable joint according to the comparison result, specifically: comparing the real-time insulation layer temperature data with the real-time environmental temperature values, if the real-time insulation layer temperature data is greater than or equal to the real-time environmental temperature values, determining that the heat radiation direction of the cable joint is the positive heat radiation direction; if the real-time insulation layer temperature data is less than the real-time environmental temperature values, determining that the heat radiation direction of the cable joint is the negative heat radiation direction; wherein, the positive heat radiation direction is that the cable joint transfers heat to the environment, and the negative heat radiation direction is that the environment transfers heat to the cable joint.

4. The method of temperature monitoring of a cable joint according to claim 3, characterized in that, Adjusting the real-time insulation layer temperature data according to the temperature difference value based on the heat radiation direction, specifically: if the heat radiation direction is the positive heat radiation direction, positively adjusting the real-time insulation layer temperature data according to the temperature difference value; if the heat radiation direction is the negative heat radiation direction, negatively adjusting the real-time insulation layer temperature data according to the temperature difference value.

5. The method of temperature monitoring of a cable joint according to claim 4, characterized in that, Based on the heat radiation direction, the real-time insulation layer temperature data is adjusted according to the temperature difference value, and a predicted temperature value of the conductor compression layer of the cable joint is determined, specifically: If the heat radiation direction is a positive heat radiation direction, the predicted temperature value of the conductor compression layer = the real-time insulation layer temperature data + the temperature difference value x k1; If the heat radiation direction is a negative heat radiation direction, the predicted temperature value of the conductor compression layer = the real-time insulation layer temperature data - the temperature difference value x k2; Wherein, k1 represents the positive heat radiation direction adjustment coefficient, k2 represents the negative heat radiation direction adjustment coefficient, and the value range of k1 and k2 is 0-0.

2.

6. The method of temperature monitoring of a cable joint according to claim 1, characterized in that, When the predicted temperature value is used to determine the predicted temperature change rate of the conductor compression layer, the predicted temperature change rate is determined according to the following formula: ΔTp = (Tp t -Tp t-1 ) / Δt; where ΔTp represents a predicted temperature change rate, Tp t represents a predicted temperature value at time t, Tp t-1 represents a predicted temperature value at time t-1, and Δt represents a time interval.

7. The method of temperature monitoring of a cable joint according to claim 1, characterized in that, The real-time temperature change rate of the conductor compression layer is determined according to the real-time load current, specifically: The real-time current square of the cable joint is calculated according to the real-time load current; The real-time temperature change rate of the conductor compression layer is determined according to the real-time current square; Wherein, the real-time temperature change rate is determined according to the following formula: ΔTr = KI 2 ; Wherein, ΔTr represents the real-time temperature change rate, K represents the real-time temperature change rate adjustment coefficient, and I represents the real-time load current.

8. The method of temperature monitoring of a cable joint according to claim 1, characterized in that, When the difference between the predicted temperature change rate and the real-time temperature change rate is determined, the difference ratio is determined according to the following formula: B=|predicted temperature change rate-real-time temperature change rate| / real-time temperature change rate; Wherein, B represents the difference ratio.

9. The method of temperature monitoring of a cable joint according to claim 1, characterized in that, According to the difference ratio, it is determined whether the cable joint is temperature monitoring abnormal, specifically: The first difference ratio and the second difference ratio are set in advance, and the first difference ratio is less than the second difference ratio; According to the relationship between the difference ratio and the first difference ratio and the second difference ratio, it is determined whether the cable joint is temperature monitoring abnormal, and the abnormal level is determined; If the difference ratio is less than or equal to the first difference ratio, it is determined that the cable joint temperature is normal; If the difference ratio is greater than the first difference ratio, and the difference ratio is less than or equal to the second difference ratio, it is determined that the cable joint temperature is slightly abnormal; If the difference ratio is greater than the second difference ratio, it is determined that the cable joint temperature is severely abnormal.

10. A cable joint for temperature monitoring by the temperature monitoring method according to any one of claims 1 to 9, characterized in that The cable joint comprises, from inside to outside, a conductor compression layer, an insulation layer, a shielding layer and a sealing protection layer, and a plurality of micro temperature sensors are embedded in the insulation layer.

Images