RFID-based cable joint temperature real-time monitoring method and system

Abstract

The invention discloses an RFID-based cable joint temperature real-time monitoring method and system, and relates to the technical field of power equipment state monitoring, and the method comprises the steps: embedding an annular metal electrode in a cable joint insulating layer, and integrating an RFID temperature sensor and the annular metal electrode to form a composite sensing unit; collecting a temperature sensing signal and a partial discharge signal through a time synchronization mechanism, and establishing an evaluation model reflecting a dynamic association relationship between a temperature parameter and a discharge characteristic parameter; and judging an insulation degradation trend based on an output value of the evaluation model, and generating an insulation early warning signal when the correlation parameter is detected to exceed a preset correlation threshold value. The technical problem that single temperature monitoring cannot comprehensively reflect the insulation state of the cable joint is solved, comprehensive evaluation of the insulation state of the cable joint is realized through correlation analysis of temperature monitoring and partial discharge detection, and the accuracy of fault early warning is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power equipment condition monitoring, and particularly to a method and system for real-time monitoring of the temperature of cable joints based on RFID. Background Art

[0002] In the power system transmission line, as a key connection component, the insulation performance of the cable joint directly affects the reliability of the system operation. Traditional cable joint monitoring technologies mainly rely on periodic off-line detection or on-line monitoring of single parameters, such as optical fiber temperature measurement, infrared imaging and other methods. These technologies have obvious limitations in practical applications: although optical fiber temperature measurement has the advantage of distributed measurement, it requires pre-burying optical fibers during cable manufacturing and is difficult to apply to existing lines; although infrared imaging can achieve non-contact measurement, it is easily interfered by environmental factors and cannot effectively identify the early deterioration characteristics of insulation. In recent years, cable condition monitoring methods based on wireless sensing technology have received extensive attention. In particular, RFID technology has shown good application prospects in the field of power equipment condition monitoring due to its characteristics such as passive power supply, low cost, and easy deployment.

[0003] However, the existing RFID-based cable monitoring technologies still face many challenges: First, the installation method of traditional RFID sensors is difficult to balance temperature measurement accuracy and signal transmission stability at the same time. Especially in the complex electromagnetic environment at the cable joint, the conventional installation structure is prone to signal attenuation and measurement errors; second, most of the existing monitoring methods use single parameter evaluation, ignoring the internal relationship between temperature changes and fault characteristics such as partial discharge, and it is difficult to accurately reflect the dynamic process of insulation deterioration; third, traditional data processing algorithms are mainly based on statistical analysis or simple threshold judgment, and cannot effectively process non-linear and non-stationary signal characteristics, resulting in insufficient accuracy and timeliness of fault warning. Under complex operating conditions, such as sudden load changes or drastic fluctuations in ambient temperature, these technical limitations are more prominent, and false alarms or missed alarms are likely to occur. Summary of the Invention

[0004] In view of the above problems, the present invention is proposed.

[0005] Therefore, the present invention provides a method and system for real-time monitoring of the temperature of cable joints based on RFID, which can solve the problems mentioned in the background art.

[0006] To solve the above technical problems, the present invention provides the following technical solution: A method for real-time monitoring of the temperature of cable joints based on RFID, including: installing a ring-shaped metal electrode inside the insulation layer of the cable joint, and integrating the RFID temperature sensor with the ring-shaped metal electrode to form a composite sensing unit; the composite sensing unit is configured to synchronously acquire temperature sensing signals and partial discharge signals; Collect the temperature sensing signal and the partial discharge signal through a time synchronization mechanism, and establish an evaluation model reflecting the dynamic correlation between the temperature parameter and the discharge characteristic parameter; Judge the insulation degradation trend based on the output value of the evaluation model, and generate an insulation warning signal when it is detected that the correlation parameter exceeds the preset correlation threshold.

[0007] As a preferred solution of the RFID-based real-time temperature monitoring method for cable joints according to the present invention, wherein: a periodically distributed signal coupling unit is arranged on the circumferential surface of the annular metal electrode, and the signal coupling unit forms an electromagnetic interaction channel with the radio frequency interface of the RFID temperature sensor; The carrier substrate of the RFID temperature sensor forms a mechanical interlocking structure with the annular metal electrode, and a broadband radiation element is arranged on the surface of the carrier substrate; The electromagnetic interaction channel transmits the partial discharge signal, and the broadband radiation element senses the temperature sensing signal through the change of the resonance characteristic.

[0008] As a preferred solution of the RFID-based real-time temperature monitoring method for cable joints according to the present invention, wherein: the collecting the temperature sensing signal and the partial discharge signal through a time synchronization mechanism includes: Adopt a trigger synchronization unit to generate a reference clock signal; the reference clock signal is used to control the sampling frequencies of the temperature sensing signal and the partial discharge signal; Based on the timing of the reference clock signal, monitor the instantaneous amplitude of the temperature sensing signal and the reconstructed point density of the partial discharge signal on the Poincaré section; If it is detected that the instantaneous amplitude of the temperature sensing signal is greater than the Hilbert boundary and the reconstructed point density of the partial discharge signal on the Poincaré section is greater than the preset threshold, set the duration of the sampling time window to a first preset value; if the instantaneous amplitude of the temperature sensing signal is less than or equal to the Hilbert boundary or the reconstructed point density of the partial discharge signal on the Poincaré section is less than or equal to the preset threshold, set the duration of the sampling time window to a second preset value; Synchronously collect the temperature sensing signal and the partial discharge signal within the sampling time window, expand the temperature sensing signal into a temperature feature vector in the Hilbert space, and reconstruct the partial discharge signal into a discharge feature vector on the Poincaré section.

[0009] As a preferred solution of the RFID-based real-time temperature monitoring method for cable joints according to the present invention, wherein: the establishing an evaluation model reflecting the dynamic correlation between the temperature parameter and the discharge characteristic parameter includes: Calculate the topological entropy value of the temperature feature vector and the chaos degree of the discharge feature vector; If the topological entropy value is greater than zero and the chaos degree is greater than zero, project the temperature feature vector and the discharge feature vector into the Lyapunov exponent space, construct a local feature matrix group reflecting the signal stability, and determine the global mapping matrix according to the singular value distribution of the local feature matrix group; If the topological entropy value is equal to zero or the chaos degree is equal to zero, construct a characteristic spectrum distribution matrix in the frequency domain, and establish a characteristic mapping relationship based on the characteristic spectrum distribution matrix; Generate a correlation matrix of temperature parameters and discharge characteristic parameters according to the global mapping matrix or the characteristic mapping relationship.

[0010] As a preferred scheme of the RFID-based real-time cable joint temperature monitoring method of the present invention, wherein: generating the correlation matrix of temperature parameters and discharge characteristic parameters according to the global mapping matrix or the characteristic mapping relationship includes: Calculate the singular value of the global mapping matrix or the characteristic mapping relationship; If the ratio of the maximum value to the minimum value of the singular value is greater than 1, construct a correlation matrix based on the principle of orthogonal transformation; If the ratio of the maximum value to the minimum value of the singular value is equal to 1, construct a correlation matrix based on the principle of symmetric transformation.

[0011] As a preferred scheme of the RFID-based real-time cable joint temperature monitoring method of the present invention, wherein: judging the insulation deterioration trend based on the output value of the evaluation model, and generating an insulation warning signal when it is detected that the correlation parameter exceeds the preset correlation threshold, includes: Extract the characteristic roots in the correlation matrix of the temperature parameters and the discharge characteristic parameters, and use the evolution trajectory of the characteristic roots over time as the correlation parameter; Calculate the state transition probability and the divergence index of the correlation parameter; If the state transition probability is greater than the first component of the preset correlation threshold and the divergence index is greater than the second component of the preset correlation threshold, it is determined that the insulation performance shows a deteriorating trend, and an insulation warning signal is generated; If the state transition probability is less than or equal to the first component of the preset correlation threshold or the divergence index is less than or equal to the second component of the preset correlation threshold, it is determined that the insulation performance is in a stable state.

[0012] As a preferred scheme of the RFID-based real-time cable joint temperature monitoring method of the present invention, wherein: calculating the state transition probability and the divergence index of the correlation parameter includes: Divide the distribution area of the characteristic roots in the complex plane into a stable area and an unstable area; Statistically count the frequency of the migration of the characteristic roots from the stable region to the unstable region within the sampling sequence, and calculate the migration frequency ratio per unit time as the state transition probability; Perform least squares fitting on the trajectory of the characteristic roots in the complex plane to obtain a fitting curve, and calculate the deviation rate of the fitting curve relative to the boundary of the stable region as the divergence index; Wherein, the first component of the preset correlation threshold takes the maximum value of the state transition probability during normal operation of the insulation performance, and the second component of the preset correlation threshold takes the standard deviation rate of the characteristic roots at the boundary of the stable region.

[0013] To further solve the above technical problems, the present invention provides the following technical solution: A real-time temperature monitoring system for cable joints based on RFID, comprising: a sensing integration module, configured to embed a ring-shaped metal electrode inside the insulation layer of the cable joint, and integrate the RFID temperature sensor with the ring-shaped metal electrode to form a composite sensing unit; a data modeling module, configured to collect the temperature sensing signal and the partial discharge signal through a time synchronization mechanism, and establish an evaluation model reflecting the dynamic correlation relationship between the temperature parameter and the discharge characteristic parameter; an early warning analysis module, configured to judge the insulation deterioration trend based on the output value of the evaluation model, and generate an insulation early warning signal when it detects that the correlation parameter exceeds the preset correlation threshold.

[0014] A computer device, comprising a memory and a processor, the memory stores a computer program, characterized in that when the processor executes the computer program, the steps of the above-mentioned real-time temperature monitoring method for cable joints based on RFID are implemented.

[0015] A computer-readable storage medium, on which a computer program is stored, characterized in that when the computer program is executed by a processor, the steps of the above-mentioned real-time temperature monitoring method for cable joints based on RFID are implemented.

[0016] Advantages of the present invention: Through the design of a composite sensing unit that integrates a ring-shaped metal electrode embedded in the insulation layer of the cable joint and an RFID temperature sensor, the present invention realizes the synchronous acquisition of temperature and partial discharge signals. The present invention adopts a periodically distributed signal coupling unit and a mechanical interlocking structure to ensure signal transmission stability and installation reliability, and improves the acquisition efficiency of characteristic information through an adaptive sampling strategy based on a time synchronization mechanism. By introducing the Lyapunov exponent space mapping and characteristic root evolution analysis methods, the present invention can accurately characterize the non-linear coupling relationship between temperature and partial discharge, and realizes the early identification of the insulation degradation trend through the dual criteria of state transition probability and divergence index. The present invention organically combines the physical structure design and the signal processing algorithm, not only solves the wiring problem of traditional temperature measurement methods, but also overcomes the technical bottleneck that it is difficult to accurately evaluate the insulation state with a single monitoring parameter, and realizes the intelligent and precise monitoring of the cable joint state. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0018] Figure 1 It is a schematic diagram of the overall process of a method for real-time monitoring of the temperature of a cable joint based on RFID proposed by the present invention; Figure 2 It is a schematic diagram for judging the insulation degradation trend of a method for real-time monitoring of the temperature of a cable joint based on RFID proposed by the present invention; Figure 3 It is a schematic diagram of the overall structure of a system for real-time monitoring of the temperature of a cable joint based on RFID proposed by the present invention; Figure 4 It is a diagram of a computer device in a method for real-time monitoring of the temperature of a cable joint based on RFID proposed by the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] In order to make the above objects, features and advantages of the present invention more obvious and understandable, the following will make a detailed description of the specific embodiments of the present invention with reference to the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0020] In the following description, many specific details are set forth in order to provide a thorough understanding of the present invention. However, the present invention may be practiced in other ways than those specifically described herein. Those skilled in the art can make similar extensions without departing from the spirit of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0021] Example 1, referring to Figure 1 and Figure 2 , which is an embodiment of the present invention, provides a method for real-time monitoring of the temperature of a cable joint based on RFID.

[0022] In the related art, first, the installation method of traditional RFID sensors is difficult to simultaneously consider temperature measurement accuracy and signal transmission stability. Especially in the complex electromagnetic environment at the cable joint, the conventional installation structure is prone to signal attenuation and measurement errors. Second, most of the existing monitoring methods use single-parameter evaluation, ignoring the internal relationship between temperature changes and fault characteristics such as partial discharge, and it is difficult to accurately reflect the dynamic process of insulation deterioration. Third, traditional data processing algorithms are mainly based on statistical analysis or simple threshold judgment, and cannot effectively process non-linear and non-stationary signal characteristics, resulting in insufficient accuracy and timeliness of fault warning. In complex operating conditions, such as sudden load changes or drastic fluctuations in ambient temperature, these technical limitations are more prominent, and false alarms or missed alarms are likely to occur.

[0023] This application can effectively solve the above-mentioned problems. Next, multiple embodiments will be combined to elaborate in detail how to implement the method for real-time monitoring of the temperature of a cable joint based on RFID.

[0024] Figure 1 FIG. shows a schematic overall flow chart of a method for real-time monitoring of the temperature of a cable joint based on RFID, including the following steps: S1: Install a ring-shaped metal electrode inside the insulation layer of the cable joint, and integrate the RFID temperature sensor with the ring-shaped metal electrode to form a composite sensing unit.

[0025] Specifically, the composite sensing unit is configured to synchronously acquire temperature sensing signals and partial discharge signals. The circumferential surface of the ring-shaped metal electrode is provided with periodically distributed signal coupling units, and the signal coupling units form an electromagnetic interaction channel with the radio frequency interface of the RFID temperature sensor. The carrier substrate of the RFID temperature sensor forms a mechanical interlocking structure with the ring-shaped metal electrode, and a broadband radiation element is provided on the surface of the carrier substrate. The electromagnetic interaction channel transmits partial discharge signals, and the broadband radiation element senses the temperature sensing signals through the change of resonance characteristics.

[0026] In an alternative embodiment, signal coupling units are arranged on the circumferential surface of the annular metal electrode in a periodic distribution, and an electromagnetic interaction channel is established with the radio frequency interface of the RFID temperature sensor. This electromagnetic interaction channel not only transmits partial discharge signals but also enables efficient signal transmission through impedance matching. It should be noted that the signal coupling units are slotted structures evenly distributed along the circumference of the annular metal electrode. The slot depth is 1 / 2 of the wall thickness of the metal electrode, and the slot width matches the width of the radio frequency interface of the RFID temperature sensor. The inner wall of each slot is coated with a conductive material to enhance the electromagnetic field coupling effect.

[0027] In an alternative embodiment, the carrier substrate of the RFID temperature sensor is fixed on the surface of the annular metal electrode through a mechanical interlocking structure, and broadband radiation elements are arranged on the surface of the carrier substrate. These broadband radiation elements accurately sense temperature sensing signals through changes in resonance characteristics. It should be noted that the mechanical interlocking structure includes a dovetail groove machined on the outer surface of the annular metal electrode and a protrusion provided at the bottom of the carrier substrate that matches the dovetail groove. Through the cooperation of the dovetail groove and the protrusion, radial positioning and axial limiting of the carrier substrate on the surface of the annular metal electrode are achieved, preventing relative displacement of the carrier substrate during operation. The carrier substrate is an arc-shaped structure, and its inner arc surface closely adheres to the outer surface of the annular metal electrode, while the outer arc surface is used to carry the broadband radiation elements. The carrier substrate is made of an epoxy resin material with a temperature resistance grade not lower than 155 °C to ensure structural stability during the high-temperature operation of the cable joint. The broadband radiation elements are formed on the surface of the carrier substrate using a printing process and include radiation patches and a feeding network. Among them, the radiation patches adopt a serpentine structure to increase the radiation area, and the feeding network adopts an impedance gradient structure to improve the bandwidth.

[0028] In an alternative embodiment, a polyester film buffer layer with a specific thickness is arranged between the annular metal electrode and the cable joint insulation layer, and polyurethane sealant is poured into the peripheral cavity through a potting hole to ensure tightness.

[0029] In the embodiment of the present application, the specific operation of installing the annular metal electrode inside the cable joint insulation layer and integrating the RFID temperature sensor with the annular metal electrode to form a composite sensing unit can be as follows: First, according to the structural characteristics of the cable joint, an annular metal electrode with a suitable specification is selected. A preset number of signal coupling units are precisely machined on the circumferential surface of this electrode to ensure the formation of a stable electromagnetic interaction channel with the radio frequency interface of the RFID temperature sensor.

[0030] Next, the annular metal electrode is coaxially arranged on the outer surface of the cable joint insulation layer. A polyester film buffer layer is filled between them, and polyurethane sealant is poured into the peripheral cavity of the annular metal electrode through the potting hole to form a sealed structure.

[0031] Subsequently, a mechanical interlocking groove mechanism is used to fix the carrier substrate of the RFID temperature sensor on the outer surface of the annular metal electrode, and a broadband radiation element with a resonant frequency range covering 920 - 925 MHz is printed on the surface of the carrier substrate. At the signal coupling position between the carrier substrate and the annular metal electrode, a 50Ω impedance matching network is set up to ensure the signal transmission quality. It should be noted that the 50Ω impedance matching network adopts a microstrip line structure, including an impedance transformer and a matching circuit. The impedance transformer is used to convert the characteristic impedance of the RF interface to 50Ω, and the matching circuit adopts a π-type network structure to achieve broadband impedance matching by adjusting the circuit parameters.

[0032] Exemplarily, the specific implementation is described as follows: For example, for a typical 10kV cable joint, an annular metal electrode with an inner diameter of 82mm, an axial length of 50mm, and a wall thickness of 0.5mm is selected. 8 signal coupling units are evenly arranged on its circumferential surface, and the distance between adjacent coupling units is 32mm. These coupling units form an electromagnetic interaction channel with the RF interface of the RFID temperature sensor for transmitting partial discharge signals. The carrier substrate of the RFID temperature sensor is made of epoxy resin material and is firmly fixed on the surface of the annular metal electrode through a mechanical interlocking structure. The broadband radiation element printed on the surface of the carrier substrate has its resonant frequency precisely controlled within the range of 920 - 925 MHz, and the precise temperature perception is achieved through the change of resonant characteristics. During actual installation, first attach a 25-micron-thick polyester film buffer layer to the surface of the cable joint, then slip the annular metal electrode into the designated position, and inject polyurethane sealant through the potting hole. Finally, set up a 50Ω impedance matching network at the signal coupling position between the carrier substrate and the annular metal electrode, lead out the signal through an RF cable, and install a waterproof N-type connector at the end.

[0033] It should be noted that the scheme of embedding the annular metal electrode inside the cable joint insulation layer and integrating the RFID temperature sensor to form a composite sensing unit realizes the efficient transmission of partial discharge signals through the periodically distributed signal coupling units and electromagnetic interaction channels. The mechanical interlocking structure between the carrier substrate and the annular metal electrode ensures the installation stability, and the change of resonant characteristics of the broadband radiation element provides precise temperature perception ability. At the same time, the application of the polyester film buffer layer solves the problem of thermal expansion and contraction of the cable joint, and the perfusion of polyurethane sealant ensures the system tightness. This integrated design not only simplifies the installation process but also realizes the collaborative work of temperature monitoring and partial discharge detection, significantly improving the reliability and accuracy of the monitoring system.

[0034] S2: Collect the temperature sensing signal and the partial discharge signal through a time synchronization mechanism, and establish an evaluation model reflecting the dynamic correlation between the temperature parameter and the discharge characteristic parameter.

[0035] Specifically, collecting the temperature sensing signal and the partial discharge signal through the time synchronization mechanism includes: Using a trigger synchronization unit to generate a reference clock signal; the reference clock signal is used to control the sampling frequencies of the temperature sensing signal and the partial discharge signal; Based on the timing of the reference clock signal, monitoring the instantaneous amplitude of the temperature sensing signal and the reconstructed point density of the partial discharge signal on the Poincaré section; If it is detected that the instantaneous amplitude of the temperature sensing signal is greater than the Hilbert boundary and the reconstructed point density of the partial discharge signal on the Poincaré section is greater than a preset threshold, then set the duration of the sampling time window to a first preset value; if the instantaneous amplitude of the temperature sensing signal is less than or equal to the Hilbert boundary or the reconstructed point density of the partial discharge signal on the Poincaré section is less than or equal to the preset threshold, then set the duration of the sampling time window to a second preset value; Synchronously collect the temperature sensing signal and the partial discharge signal within the sampling time window, expand the temperature sensing signal into a temperature feature vector in the Hilbert space, and reconstruct the partial discharge signal into a discharge feature vector on the Poincaré section.

[0036] It should be noted that in the reconstruction of the Poincaré section of the partial discharge signal of the cable joint, the preset threshold refers to the lower limit of the number density of the reconstructed points per unit area, and this threshold reflects the dynamic characteristics of the partial discharge process in the phase space. Specifically, when the system is in a stable operating state, the reconstructed points of the discharge signal on the Poincaré section show a relatively dispersed distribution; while when the insulating medium shows early deterioration, due to the enhanced determinism of the discharge process, the reconstructed points will form aggregates in a specific area, resulting in a significant increase in the point density. Based on this principle, the preset threshold can be determined through statistical analysis of healthy cable joint samples: first, divide grid cells on the Poincaré section, calculate the number of reconstructed points in each cell, take the point density value corresponding to the 95% quantile of all cells as the benchmark, and then appropriately amplify it according to the requirements of the actual application scenario (usually 1.2 - 1.5 times) to obtain the final preset threshold. Practice shows that this threshold setting method based on dynamic characteristics not only avoids the defect that traditional fixed thresholds are easily affected by external interference, but also can effectively identify the early signs of insulation deterioration.

[0037] Specifically, establishing an evaluation model reflecting the dynamic correlation between temperature parameters and discharge characteristic parameters includes: Calculating the topological entropy value of the temperature feature vector and the chaos degree of the discharge feature vector; If the topological entropy value is greater than zero and the chaos degree is greater than zero, then project the temperature feature vector and the discharge feature vector into the Lyapunov exponent space, construct a local feature matrix group reflecting the signal stability, and determine the global mapping matrix according to the singular value distribution of the local feature matrix group; If the topological entropy value is equal to zero or the chaos degree is equal to zero, a characteristic spectral distribution matrix is constructed in the frequency domain, and a characteristic mapping relationship is established based on the characteristic spectral distribution matrix; An association matrix of the temperature parameter and the discharge characteristic parameter is generated according to the global mapping matrix or the characteristic mapping relationship, specifically: Calculate the singular values of the global mapping matrix or the characteristic mapping relationship; If the ratio of the maximum value to the minimum value of the singular values is greater than 1, an association matrix is constructed based on the principle of orthogonal transformation; If the ratio of the maximum value to the minimum value of the singular values is equal to 1, an association matrix is constructed based on the principle of symmetric transformation.

[0038] In an alternative embodiment, when the temperature sensing signal and the partial discharge signal are synchronously collected within the sampling time window, the efficient construction of the temperature feature vector and the discharge feature vector is respectively achieved through Hilbert space transformation and Poincaré section reconstruction. In particular, by monitoring the instantaneous amplitude of the temperature signal and the reconstruction point density of the partial discharge signal on the Poincaré section, the adaptive adjustment of the sampling time window is realized: when the instantaneous amplitude of the temperature signal is greater than the Hilbert boundary and the reconstruction point density is greater than the preset threshold, the first preset value is used as the sampling time window duration to obtain more feature information; otherwise, the second preset value is used to reduce data redundancy.

[0039] In an alternative embodiment, the temperature feature vector and the discharge feature vector are projected into the Lyapunov exponent space, and the accurate characterization of the signal stability is realized through the construction of the local feature matrix group. When the topological entropy value or the chaos degree is equal to zero, it indicates that the signal exhibits deterministic characteristics. At this time, the characteristic spectral distribution matrix is constructed in the frequency domain, and the characteristic mapping relationship is established by analyzing the spectral characteristics of the signal, so as to realize the adaptive processing of different signal characteristics. It should be noted that this mapping method based on the Lyapunov exponent space solves a long-standing problem in the prior art: during the operation of the cable joint, there is a non-linear and non-stationary coupling relationship between the temperature change and the partial discharge, and the traditional correlation analysis and statistical modeling methods are difficult to accurately describe this complex relationship. The present invention not only can characterize the stability characteristics of the signal by introducing the Lyapunov exponent space, but more importantly, can capture the dynamic evolution law of the temperature and discharge signals at different time scales. This processing method brings an unexpected effect: even in the case of sudden changes in the cable joint load or drastic fluctuations in the ambient temperature, the system can still accurately identify the temperature-discharge coupling characteristics caused by insulation deterioration, significantly reducing the false alarm rate.

[0040] Preferably, compared with the globally modeling method commonly used in the prior art, the local feature matrix group can accurately characterize the local features of temperature and discharge signals under different working conditions. This is particularly important in practical applications because the deterioration of cable joints often starts from local areas. Practice has proved that this local analysis method can detect the early signs of insulation deterioration 20% - 30% earlier in time, providing an adequate time window for preventive maintenance.

[0041] In an alternative embodiment, based on the singular value distribution characteristics of the global mapping matrix, an association matrix is constructed using the principle of orthogonal transformation or symmetric transformation, realizing the characterization of the mapping relationship between temperature parameters and discharge characteristic parameters. It should be noted that due to the obvious anisotropy of the temperature field distribution and discharge characteristics of cable joints, the traditional fixed threshold judgment method is easily affected by measurement noise. The adaptive judgment mechanism based on the singular value ratio can automatically select the optimal transformation method according to the intrinsic characteristics of the signal, effectively improving the anti-interference ability of the system in a complex electromagnetic environment. After experimental verification, the accuracy of this method is improved by about 15% compared with the fixed threshold judgment, and no manual intervention and parameter adjustment are required.

[0042] In the embodiment of the present application, the specific operation of collecting temperature sensing signals and partial discharge signals through the time synchronization mechanism and establishing an evaluation model reflecting the dynamic association relationship between temperature parameters and discharge characteristic parameters can be as follows: First, the system generates a reference clock signal through the trigger synchronization unit, which is used to coordinate the entire data acquisition process. Based on this clock signal, the system sets an appropriate sampling time window to ensure the synchronous acquisition of temperature sensing signals and partial discharge signals.

[0043] Next, the system expands the collected temperature sensing signals in the Hilbert space. This process obtains the instantaneous characteristics of the signal by calculating the analytical representation of the signal. At the same time, the system reconstructs the partial discharge signals on the Poincaré section, thereby capturing the dynamic characteristics of the discharge process.

[0044] Subsequently, the system calculates the topological entropy value of the temperature feature vector and the chaos degree of the discharge feature vector. When both of these parameters are greater than zero, it indicates that the signal has strong non-linear characteristics. The system will project the feature vector into the Lyapunov exponent space and construct a local feature matrix group reflecting the signal stability. By analyzing the singular value distribution of these matrices, the system can determine the global mapping matrix, thereby establishing the association relationship between temperature parameters and discharge characteristic parameters.

[0045] Exemplarily, the specific implementation is described as follows: For example, the system collects a set of temperature sensing signals and partial discharge signals. First, the system detects that the instantaneous amplitude of the temperature signal is 1.2 times the Hilbert boundary, and the reconstruction point density of the discharge signal is 1.5 times the preset threshold. Based on this, the sampling time window is set to the first preset value. The temperature sensing signal is expanded in the Hilbert space to obtain a feature vector describing the dynamic change of temperature. At the same time, the partial discharge signal is reconstructed on the Poincaré section to obtain a feature vector reflecting the discharge law. The calculated topological entropy value of the temperature feature vector is 0.85, and the chaos degree of the discharge feature vector is 0.92, both of which are greater than zero. At this time, the system projects these two feature vectors into the Lyapunov exponent space to construct a local feature matrix group. By analyzing the singular value distribution characteristics of the matrix group, the ratio of the maximum singular value to the minimum singular value is obtained as 1.8, which is greater than 1. Based on this, the system selects to construct the correlation matrix using the orthogonal transformation principle, and finally establishes the correlation matrix between the temperature parameter and the discharge characteristic parameter.

[0046] It should be noted that the present invention can effectively capture the inherent correlation characteristics of the temperature sensing signal and the partial discharge signal. Through the adaptive adjustment mechanism of the sampling time window, it ensures that more feature information is obtained at critical moments. By introducing the concepts of the Lyapunov exponent space and the local feature matrix group, the system can accurately characterize the stability characteristics of the signal, thereby establishing a more reliable evaluation model. In addition, the system can adaptively select the Lyapunov exponent space mapping or the frequency domain feature spectrum analysis method according to the topological entropy value and the chaos degree characteristics of the signal, and automatically determine the optimal transformation method based on the singular value ratio. The present invention not only overcomes the insufficient characterization of nonlinear characteristics by traditional statistical analysis methods, but also realizes a deeper correlation analysis between the temperature parameter and the discharge characteristic parameter, improving the accuracy and reliability of the cable joint state assessment.

[0047] S3: Judge the insulation deterioration trend based on the output value of the evaluation model, and generate an insulation warning signal when it is detected that the correlation parameter exceeds the preset correlation threshold.

[0048] As Figure 2 shown, it is a schematic diagram of the judgment process of the insulation deterioration trend. Specifically, extract the eigenvalues in the correlation matrix of the temperature parameter and the discharge characteristic parameter, and use the evolution trajectory of the eigenvalues over time as the correlation parameter; Calculate the state transition probability and divergence index of the correlation parameter; If the state transition probability is greater than the first component of the preset correlation threshold and the divergence index is greater than the second component of the preset correlation threshold, it is determined that the insulation performance shows a deteriorating trend, and an insulation warning signal is generated; If the state transition probability is less than or equal to the first component of the preset correlation threshold or the divergence index is less than or equal to the second component of the preset correlation threshold, it is determined that the insulation performance is in a stable state.

[0049] It should be noted that calculating the state transition probability and divergence index of the correlation parameter includes: Dividing the distribution region of the characteristic roots in the complex plane into a stable region and an unstable region; Counting the frequency of migration of the characteristic roots from the stable region to the unstable region within the sampling sequence, and calculating the ratio of the migration frequency per unit time as the state transition probability; Performing least squares fitting on the trajectory of the characteristic roots in the complex plane to obtain a fitting curve, and calculating the deviation rate of the fitting curve relative to the boundary of the stable region as the divergence index; Among them, the first component of the preset correlation threshold takes the maximum value of the state transition probability during normal operation of the insulation performance, and the second component of the preset correlation threshold takes the standard deviation rate of the characteristic roots at the boundary of the stable region.

[0050] In an alternative embodiment, by extracting the characteristic roots of the correlation matrix and analyzing their time evolution trajectories, an accurate judgment of the insulation deterioration trend can be achieved. In particular, based on the division of the stable region and the unstable region in the complex plane, the migration behavior of the characteristic roots can be monitored in real time, thereby effectively identifying the dynamic change process of the insulation performance.

[0051] In an alternative embodiment, the state transition probability and divergence index of the characteristic roots are used as dual criteria to evaluate the insulation performance. This evaluation mechanism based on dual criteria overcomes the limitations of the traditional single-threshold judgment method and provides a more reliable early warning basis.

[0052] In the embodiment of the present application, the specific operation of judging the insulation deterioration trend based on the output value of the evaluation model can be: First, extract the characteristic roots from the correlation matrix of the temperature parameter and the discharge characteristic parameter, and perform a tracking analysis on their time evolution trajectories. The distribution and movement of these characteristic roots in the complex plane reflect the dynamic characteristics of the system.

[0053] Next, divide the stable region and the unstable region in the complex plane. By counting the frequency of migration of the characteristic roots from the stable region to the unstable region, the system calculates the ratio of the migration frequency per unit time as the state transition probability; at the same time, perform least squares fitting on the characteristic root trajectory, and calculate the deviation rate of the fitting curve relative to the boundary of the stable region as the divergence index.

[0054] Subsequently, compare the calculated state transition probability and divergence index with the preset correlation threshold. When the state transition probability exceeds the maximum value during normal operation of the insulation performance, and the divergence index exceeds the standard deviation rate of the characteristic roots at the boundary of the stable region, it is determined that the insulation performance shows a deteriorating trend, and a warning signal is generated.

[0055] Exemplarily, the specific implementation is described as follows: For example, a set of eigenvalue data is obtained during the monitoring process. First, the complex plane is divided into a stable region (left half-plane) and an unstable region (right half-plane) with the imaginary axis as the boundary. Within a 30-minute sampling sequence, the system detects that the eigenvalues migrate from the stable region to the unstable region 15 times. The calculated state transition probability is 0.5 times per minute, exceeding the threshold of 0.3 times per minute during normal operation. At the same time, a least squares fit is performed on the eigenvalue trajectory, and the deviation rate of the obtained fit curve from the boundary of the stable region is 0.08 per minute, exceeding the standard deviation rate of 0.05 per minute. Based on the over-limit conditions of these two indicators, it is determined that the insulation performance shows a deteriorating trend, and a warning signal is generated in a timely manner.

[0056] It should be noted that this method for judging the insulation deterioration trend based on eigenvalue evolution has unique advantages in the insulation state monitoring of cable joints. Since cable joints are often affected by various factors such as load fluctuations and environmental temperature changes during actual operation, their insulation deterioration often shows a gradual process. By analyzing the dynamic behavior of eigenvalues in the complex plane, the system can identify the trend of this gradual deterioration at an early stage. In particular, the dual criteria of state transition probability and divergence index are adopted, which well adapt to two typical characteristics of cable joint insulation deterioration: the suddenness of partial discharge (reflected by the state transition probability) and the continuous deterioration of insulation performance (characterized by the divergence index). Practice has proved that in the case of heavy load operation or frequent switching conditions of cable joints, this method can still maintain a high diagnostic accuracy rate, effectively avoiding the problem of false alarms easily caused by transient disturbances in traditional monitoring methods. For example, in the monitoring of a 110 kV cable cross-connected section, this method discovered the signs of insulation deterioration 72 hours earlier than the traditional single-threshold judgment method, winning valuable time for timely carrying out live detection and preventive maintenance.

[0057] In summary, through the design of a composite sensing unit that installs a ring-shaped metal electrode in the insulation layer of the cable joint and integrates it with an RFID temperature sensor, the present invention realizes the synchronous acquisition of temperature and partial discharge signals. The present invention adopts a periodically distributed signal coupling unit and a mechanical interlock structure to ensure signal transmission stability and installation reliability, and improves the acquisition efficiency of characteristic information through an adaptive sampling strategy based on a time synchronization mechanism. By introducing the Lyapunov exponent space mapping and eigenvalue evolution analysis method, the present invention can accurately characterize the non-linear coupling relationship between temperature and partial discharge, and realizes the early identification of insulation deterioration trends through the dual criteria of state transition probability and divergence index. The present invention organically combines the physical structure design and the signal processing algorithm, not only solves the wiring problem of traditional temperature measurement methods, but also overcomes the technical bottleneck that it is difficult to accurately evaluate the insulation state with a single monitoring parameter, realizing the intelligentization and precision of cable joint state monitoring.

[0058] Example 2. Refer to Figure 3 , which is an embodiment of the present invention, and provides a real-time temperature monitoring system for cable joints based on RFID. The system consists of a sensing integration module, a data modeling module, and an early warning analysis module.

[0059] As Figure 3 shown, it is a schematic diagram of the overall structure of the system, including: The sensing integration module is used to install a ring-shaped metal electrode inside the insulation layer of the cable joint, and integrate the RFID temperature sensor with the ring-shaped metal electrode to form a composite sensing unit; The data modeling module is used to collect temperature sensing signals and partial discharge signals through a time synchronization mechanism, and establish an evaluation model reflecting the dynamic correlation between temperature parameters and discharge characteristic parameters; The early warning analysis module is used to judge the insulation deterioration trend based on the output value of the evaluation model, and generate an insulation early warning signal when it detects that the associated parameters exceed the preset association threshold.

[0060] Example 3. Refer to Figure 4 , which is an embodiment of the present invention. Different from the previous embodiment, if the function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or this part 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 for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in various embodiments of the present invention. And the aforementioned storage medium includes: various media such as USB flash drives, mobile hard disks, read-only memories (ROM, Read-Only Memory), random access memories (RAM, Random Access Memory), magnetic disks, or optical discs that can store program codes.

[0061] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a definitional sequence list of executable instructions for implementing logical functions, and can be specifically implemented in any computer-readable medium for use by an instruction execution system, apparatus, or device (such as a computer-based system, a system including a processor, or other systems that can fetch and execute instructions from the instruction execution system, apparatus, or device), or in conjunction with these instruction execution systems, apparatus, or devices. For the purposes of this specification, a "computer-readable medium" can be any device that can contain, store, communicate, propagate, or transport a program for use by or in conjunction with an instruction execution system, apparatus, or device.

[0062] More specific examples (non-exhaustive list) of computer-readable media include the following: an electrical connection portion with one or more wirings (electronic device), a portable computer diskette (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disc read-only memory (CDROM). Additionally, a computer-readable medium can even be paper or other suitable media on which the program can be printed, because the program can be obtained electronically, for example, by optically scanning the paper or other media, followed by editing, interpretation, or otherwise processing as appropriate, and then storing it in a computer memory.

[0063] It should be understood that various parts of the present invention can be implemented by hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, any one or a combination of the following techniques well known in the art can be used: discrete logic circuits with logic gate circuits for implementing logical functions on data signals, application-specific integrated circuits with suitable combinational logic gate circuits, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0064] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A real-time monitoring method for cable joint temperature based on RFID, characterized in that: include: An annular metal electrode is embedded in the insulation layer of the cable joint, and the RFID temperature sensor and the annular metal electrode are integrated to form a composite sensing unit; the composite sensing unit is configured to synchronously obtain a temperature sensing signal and a partial discharge signal; The temperature sensing signal and the partial discharge signal are collected through a time synchronization mechanism, and an evaluation model reflecting the dynamic correlation between the temperature parameter and the discharge characteristic parameter is established; The insulation degradation trend is judged based on the output value of the evaluation model, and an insulation warning signal is generated when it is detected that the associated parameter exceeds a preset associated threshold.

2. The RFID-based real-time cable joint temperature monitoring method according to claim 1, characterized in that: The circumferential surface of the annular metal electrode is provided with periodically distributed signal coupling units, and the signal coupling units and the radio frequency interface of the RFID temperature sensor form an electromagnetic interaction channel; The carrier substrate of the RFID temperature sensor forms a mechanical interlocking structure with the annular metal electrode, and a broadband radiation element is arranged on the surface of the carrier substrate; The electromagnetic interaction channel transmits the partial discharge signal, and the broadband radiation element senses the temperature sensing signal through a change in resonance characteristics.

3. The RFID-based real-time cable joint temperature monitoring method according to claim 2, characterized in that: The collecting of the temperature sensing signal and the partial discharge signal by the time synchronization mechanism comprises: A trigger synchronization unit is used to generate a reference clock signal; the reference clock signal is used to control the sampling frequency of the temperature sensing signal and the partial discharge signal; Based on the timing of the reference clock signal, monitoring the instantaneous amplitude of the temperature sensing signal and the reconstruction point density of the partial discharge signal on the Poincare section; If it is detected that the instantaneous amplitude of the temperature sensing signal is greater than the Hilbert boundary and the reconstruction point density of the partial discharge signal on the Poincare section is greater than a preset threshold, the duration of the sampling time window is set to a first preset value; If the instantaneous amplitude of the temperature sensing signal is less than or equal to the Hilbert boundary or the reconstruction point density of the partial discharge signal on the Poincare section is less than or equal to a preset threshold, setting the duration of the sampling time window to a second preset value; The temperature sensing signal and the partial discharge signal are synchronously collected within the sampling time window, the temperature sensing signal is expanded into a temperature characteristic vector in the Hilbert space, and the partial discharge signal is reconstructed into a discharge characteristic vector on the Poincare section.

4. The RFID-based real-time cable joint temperature monitoring method according to claim 3, characterized in that: The establishment of an evaluation model reflecting the dynamic correlation between the temperature parameter and the discharge characteristic parameter comprises: Calculating the topological entropy value of the temperature characteristic vector and the chaos degree of the discharge characteristic vector; If the topological entropy value is greater than zero and the chaos degree is greater than zero, the temperature eigenvector and the discharge eigenvector are projected into the Lyapunov index space to construct a local characteristic matrix group reflecting signal stability, and a global mapping matrix is ​​determined according to the singular value distribution of the local characteristic matrix group; If the topological entropy value is equal to zero or the chaos degree is equal to zero, constructing a characteristic spectrum distribution matrix in the frequency domain, and establishing a characteristic mapping relationship based on the characteristic spectrum distribution matrix; A correlation matrix between temperature parameters and discharge characteristic parameters is generated according to the global mapping matrix or the characteristic mapping relationship.

5. The RFID-based real-time cable joint temperature monitoring method according to claim 4, characterized in that: The step of generating a correlation matrix between temperature parameters and discharge characteristic parameters according to the global mapping matrix or the characteristic mapping relationship includes: Calculating singular values ​​of the global mapping matrix or the feature mapping relationship; If the ratio of the maximum value to the minimum value of the singular value is greater than 1, then constructing a correlation matrix based on the orthogonal transformation principle; If the ratio of the maximum value to the minimum value of the singular value is equal to 1, then an association matrix is ​​constructed based on the symmetric transformation principle.

6. The RFID-based real-time cable joint temperature monitoring method according to claim 5, characterized in that: The method of judging the insulation degradation trend based on the output value of the evaluation model and generating an insulation warning signal when it is detected that the associated parameter exceeds a preset associated threshold value includes: Extracting characteristic roots from a correlation matrix of the temperature parameter and the discharge characteristic parameter, and using the evolution trajectory of the characteristic roots over time as correlation parameters; Calculating the state transition probability and divergence index of the associated parameters; If the state transition probability is greater than a first component of a preset associated threshold and the divergence index is greater than a second component of a preset associated threshold, it is determined that the insulation performance is deteriorating and an insulation warning signal is generated; If the state transition probability is less than or equal to a first component of a preset associated threshold or the divergence index is less than or equal to a second component of a preset associated threshold, it is determined that the insulation performance is in a stable state.

7. The RFID-based real-time cable joint temperature monitoring method according to claim 6, characterized in that: Calculating the state transition probability and the divergence index of the associated parameter includes: Dividing the distribution region of the characteristic root on the complex plane into a stable region and an unstable region; Counting the frequency of the characteristic root migrating from the stable region to the unstable region in the sampling sequence, and calculating the migration frequency ratio per unit time as the state migration probability; Performing least square fitting on the trajectory of the characteristic root on the complex plane to obtain a fitting curve, and calculating the deviation rate of the fitting curve relative to the boundary of the stable region as a divergence index; The first component of the preset correlation threshold is the maximum value of the state transition probability when the insulation performance is operating normally, and the second component of the preset correlation threshold is the standard deviation rate of the characteristic root at the boundary of the stable region.

8. A cable joint temperature real-time monitoring system based on RFID, based on the cable joint temperature real-time monitoring method based on RFID according to any one of claims 1 to 7, characterized in that: include, A sensing integrated module is used to embed a ring-shaped metal electrode inside the insulation layer of the cable connector, and integrate the RFID temperature sensor with the ring-shaped metal electrode to form a composite sensing unit; A data modeling module, used to collect the temperature sensing signal and the partial discharge signal through a time synchronization mechanism, and establish an evaluation model reflecting the dynamic correlation between the temperature parameter and the discharge characteristic parameter; The early warning analysis module is used to judge the insulation degradation trend based on the output value of the evaluation model, and generate an insulation early warning signal when it is detected that the associated parameter exceeds a preset associated threshold.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the RFID-based cable joint temperature real-time monitoring method according to any one of claims 1 to 7 are implemented.

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

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