Traction power supply 27.5 kV cable interval grounding grid power frequency resistance real-time monitoring method and system

Abstract

The invention relates to the technical field of power frequency resistance real-time monitoring, and provides a traction power supply 27.5 kV cable interval grounding grid power frequency resistance real-time monitoring method and system, and the method comprises the steps: obtaining the temperature distribution data of the surface of a conductor of a grounding grid; acquiring voltage and current response of the grounding grid when the local temperature rise value exceeds a preset reference value to perform frequency domain conversion, and generating a broadband impedance spectroscopy analysis result; aligning earth surface coordinates corresponding to the temperature measurement nodes with underground coordinates corresponding to the impedance measurement points, generating a space correlation grid, generating a temperature rise phase deviation coupling relation matrix, and generating a real-time monitoring result of the power frequency resistance of the grounding grid according to a power frequency impedance correction value in the space correlation grid and the temperature rise phase deviation coupling relation matrix; according to the invention, accurate space matching between the abnormal temperature rise area and the impedance change of the corresponding conductor is realized, the adaptability of a monitoring network to the extension direction and the burial depth change of the conductor is enhanced, and feature signal omission caused by fixed measurement point deployment is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of real-time monitoring of power frequency resistance, and particularly to a method and system for real-time monitoring of the power frequency resistance of the grounding grid in the 27.5 kV cable section of traction power supply. Background Art

[0002] During the operation of the grounding grid in the 27.5 kV cable section of traction power supply, the grounding conductor is prone to abnormal temperature rise in local areas due to long-term exposure to high-frequency transient current and continuous unbalanced current, which may further lead to changes in the grounding resistance and threaten the safe operation of the system. Especially in the case of a long cable section and complex geological environment, a technical means capable of realizing real-time monitoring of the power frequency resistance of the grounding grid in a complex electromagnetic environment is needed to improve the reliability and operation and maintenance intelligence level of the traction power supply system.

[0003] Currently, the mainstream solution is a grounding grid status evaluation method based on the combination of broadband excitation and multi-point impedance measurement. This method applies broadband excitation signals at different positions of the grounding grid, collects the voltage and current responses of each impedance measurement point, and thus establishes an impedance distribution model of the entire grounding grid; by combining historical data analysis and the current operating state, the change trend of the overall resistance of the grounding grid is deduced to preliminarily locate abnormal areas. Existing solutions have some inherent defects, including relying on the change of a single electrical parameter to judge the status of the grounding grid, resulting in limited recognition accuracy of the change of power frequency resistance in a complex operating environment; lacking effective integration of spatial geographic information, which affects the accurate restoration and real-time monitoring ability of the actual operating state of the grounding grid. Summary of the Invention

[0004] The present invention provides a method and system for real-time monitoring of the power frequency resistance of the grounding grid in the 27.5 kV cable section of traction power supply to solve the problems in the prior art that it relies on the change of a single electrical parameter to judge the status of the grounding grid, resulting in limited recognition accuracy of the change of power frequency resistance in a complex operating environment; lacking effective integration of spatial geographic information, which affects the accurate restoration and real-time monitoring ability of the actual operating state of the grounding grid.

[0005] In a first aspect, the present invention provides a method for real-time monitoring of the power frequency resistance of the grounding grid in the 27.5 kV cable section of traction power supply, including: Obtaining temperature distribution data on the surface of the conductor of the grounding grid in the 27.5 kV cable section of traction power supply, where the grounding grid includes a plurality of temperature measurement nodes arranged at equal intervals along the 27.5 kV cable section of traction power supply; Collecting the voltage and current responses of the grounding grid when the local temperature rise value exceeds a preset reference value, and performing frequency domain conversion on the voltage and current responses to generate a broadband impedance spectrum analysis result, where the local temperature rise value is obtained from the temperature distribution data; According to the conductor topological structure of the grounding grid, align the surface coordinates corresponding to the temperature measurement nodes with the underground coordinates corresponding to the impedance measurement points in the broadband impedance spectrum analysis results to generate a spatial correlation grid; Extract the extreme value of the temperature rise rate from the spatial correlation grid, extract the extreme value of the phase shift from the broadband impedance spectrum analysis results, and combine the extreme value of the temperature rise rate and the extreme value of the phase shift to generate a temperature rise-phase shift coupling relationship matrix; Generate the real-time monitoring result of the power frequency resistance of the grounding grid according to the power frequency impedance correction value of the temperature rise-phase shift coupling relationship matrix.

[0006] Optionally, according to the conductor topological structure of the grounding grid, align the surface coordinates corresponding to the temperature measurement nodes with the underground coordinates corresponding to the impedance measurement points in the broadband impedance spectrum analysis results to generate a spatial correlation grid, including: According to the conductor topological structure of the grounding grid, obtain the length of the conductor segments, the positions of the branch connection points, and the vertical coordinates of the conductor burial depths corresponding to the branch connection points; Determine the actual installation positions of the temperature measurement nodes according to the conductor segments and the positions of the branch connection points; Screen out the frequency intervals in the conductor segments where the decrease amplitude of the impedance amplitude exceeds a preset decrease value from the broadband impedance spectrum analysis results, and determine the coordinate points of the positions with the maximum current density in the conductor segments as the impedance measurement points according to the current distribution characteristics corresponding to the frequency intervals; Bind the surface coordinates corresponding to the actual installation positions of the temperature measurement nodes, the vertical coordinates of the conductor burial depths, and the underground coordinates corresponding to the impedance measurement points to generate a spatial correlation grid.

[0007] Optionally, bind the surface coordinates corresponding to the actual installation positions of the temperature measurement nodes, the vertical coordinates of the conductor burial depths, and the underground coordinates corresponding to the impedance measurement points to generate a spatial correlation grid, including: Based on the length of the conductor segments and the positions of the branch connection points, divide the grounding grid into multiple conductor segment units, where each conductor segment unit contains a temperature measurement node and an impedance measurement point; Superimpose the surface coordinates corresponding to the actual installation positions of the temperature measurement nodes in each conductor segment unit with the vertical coordinates of the conductor burial depths to generate the three-dimensional monitoring coordinates corresponding to the temperature measurement nodes in each conductor segment unit; According to the underground coordinates corresponding to the impedance measurement points in each conductor segment unit, spatially bind the underground coordinates corresponding to the impedance measurement points in each conductor segment unit with the corresponding three-dimensional monitoring coordinates to generate the bound coordinate pairs of each conductor segment unit; Aggregating the bound coordinate pairs of multiple conductor segment units adjacent to the branch connection point with the vertical coordinate of the conductor burial depth to generate a branch topology node; The binding coordinate pairs and the branch topology nodes are mapped to generate a spatial association grid.

[0008] Optionally, collecting voltage and current responses of the grounding grid when a local temperature rise value exceeds a preset reference value, performing frequency domain conversion on the voltage and current responses to generate a broadband impedance spectrum analysis result, wherein the local temperature rise value is obtained from the temperature distribution data, includes: When the temperature rise value of at least one temperature measurement node in the temperature distribution data exceeds a preset reference value, it is determined that there is a local temperature rise abnormality in the grounding grid, and the voltage and current time domain waveform data at both ends of the grounding grid under the excitation signal are collected; Dividing the voltage and current time domain waveform data into a plurality of time domain data segments according to a preset time period, and removing the time domain data segments whose waveform distortion rate exceeds a preset distortion threshold, so as to generate optimized voltage and current time domain waveform data; Performing a windowed Fourier transform on each time domain data segment in the optimized voltage and current time domain waveform data to obtain a voltage spectrum and a current spectrum corresponding to each time domain data segment; Extracting the voltage effective value of each discrete frequency point from the voltage spectrum, and extracting the current effective value corresponding to the discrete frequency point from the current spectrum, so as to calculate the voltage-current phase difference and impedance amplitude corresponding to each discrete frequency point; Associating the voltage and current phase difference, impedance amplitude and frequency value corresponding to each discrete frequency point into an impedance spectrum data entry; All impedance spectrum data entries are arranged in ascending order of frequency value to generate broadband impedance spectrum analysis results. During the arrangement process, impedance spectrum data entries with the same frequency value are merged, and abnormal entries with impedance amplitude fluctuations exceeding the preset range are eliminated.

[0009] Optionally, performing a windowed Fourier transform on each time domain data segment in the optimized voltage and current time domain waveform data to obtain a voltage spectrum and a current spectrum corresponding to each time domain data segment includes: Multiplying the voltage waveform data and the current waveform data in each time domain data segment of the optimized voltage and current time domain waveform data by a preset window function point by point to generate windowed voltage waveform segments and current waveform segments; Determining a discrete frequency point set according to the duration and sampling interval of the time domain data segment; Based on the discrete frequency point set, discrete spectrum conversion is performed on the windowed voltage waveform segment and current waveform segment to obtain a voltage spectrum sequence and a current spectrum sequence; Extract the real part value and the first imaginary part value of the voltage at each discrete frequency point from the voltage spectrum sequence to calculate the effective value of the voltage at each discrete frequency point; Extract the real part value and the second imaginary part value of the current at the corresponding discrete frequency point from the current spectrum sequence to calculate the effective value of the current at each discrete frequency point; Calculate the voltage-current phase difference at each discrete frequency point according to the real part value of the voltage, the real part value of the current, the imaginary part value of the voltage, and the imaginary part value of the current at each discrete frequency point; Bind the effective value of the voltage, the effective value of the current, and the voltage-current phase difference at each discrete frequency point to the corresponding frequency value to obtain a plurality of spectrum entries, and sort the plurality of spectrum entries to generate the voltage spectrum and the current spectrum corresponding to each time domain data segment.

[0010] Optionally, extract the extreme value of the temperature rise rate from the spatial correlation grid, extract the extreme value of the phase shift amount from the broadband impedance spectrum analysis result, and combine the extreme value of the temperature rise rate and the extreme value of the phase shift amount to generate a temperature rise-phase shift coupling relationship matrix, including: Extract the extreme value of the temperature rise rate of each temperature measurement node in the preset time window from the spatial correlation grid; Extract the extreme value of the phase shift amount corresponding to each impedance measurement point from the broadband impedance spectrum analysis result; According to the binding relationship between the conductor segment unit, the temperature measurement node, and the impedance measurement point in the spatial correlation grid, associate the extreme value of the temperature rise rate and the extreme value of the phase shift amount corresponding to each conductor segment unit to generate a coupling parameter pair; Based on the conductor topology structure of the grounding grid, map the coupling parameter pair corresponding to each conductor segment unit to the preset matrix row and column to generate a temperature rise-phase shift coupling relationship matrix.

[0011] Optionally, generate the real-time monitoring result of the power frequency resistance of the grounding grid according to the power frequency impedance correction value of the temperature rise-phase shift coupling relationship matrix, including: Screen out a plurality of target matrix elements from the temperature rise-phase shift coupling relationship matrix, and use the target matrix elements as key correction factors. The target matrix elements are matrix elements whose extreme values of the temperature rise rate and the phase shift amount both exceed the preset threshold; Calculate the weight coefficient of each key correction factor according to the proportional relationship between the extreme value of the temperature rise rate and the extreme value of the phase shift amount corresponding to each key correction factor; Superimpose each key correction factor according to the weight coefficient to generate a power frequency impedance regional correction value; Map the power frequency impedance regional correction value to the corresponding conductor segment unit in the spatial correlation grid to generate the real-time monitoring result of the power frequency resistance of the grounding grid.

[0012] In a second aspect, the present invention provides a real-time monitoring system for the power frequency resistance of the grounding grid in the 27.5 kV cable section of traction power supply, comprising: An acquisition module, configured to acquire temperature distribution data on the surface of the conductor of the grounding grid in the 27.5 kV cable section of traction power supply, wherein the grounding grid includes a plurality of temperature measurement nodes arranged at equal intervals along the 27.5 kV cable section of traction power supply; A conversion module, configured to collect the voltage-current response when the local temperature rise value of the grounding grid exceeds a preset reference value, and perform frequency-domain conversion on the voltage-current response to generate a broadband impedance spectrum analysis result, wherein the local temperature rise value is obtained from the temperature distribution data; An alignment module, configured to align the surface coordinates corresponding to the temperature measurement nodes with the underground coordinates corresponding to the impedance measurement points in the broadband impedance spectrum analysis result according to the conductor topology of the grounding grid, so as to generate a spatial correlation grid; An extraction module, configured to extract the extreme value of the temperature rise rate from the spatial correlation grid, extract the extreme value of the phase shift amount from the broadband impedance spectrum analysis result, and combine the extreme value of the temperature rise rate and the extreme value of the phase shift amount to generate a temperature rise-phase shift coupling relationship matrix; A generation module, configured to generate a real-time monitoring result of the power frequency resistance of the grounding grid according to the power frequency impedance correction value of the temperature rise-phase shift coupling relationship matrix.

[0013] In a third aspect, the present invention provides a computing device, comprising a processor and a memory, wherein a computer program is stored in the memory, and the processor is configured to run the computer program to execute the real-time monitoring method for the power frequency resistance of the grounding grid in the 27.5 kV cable section of traction power supply according to any one of the first aspects.

[0014] In a fourth aspect, the present invention provides a computer storage medium, on which computer program instructions are stored, and when the computer program instructions are executed by a processor, the real-time monitoring method for the power frequency resistance of the grounding grid in the 27.5 kV cable section of traction power supply according to any one of the first aspects is implemented.

[0015] In the present invention, temperature distribution data of the surface of the conductor of the grounding grid in the 27.5 kV cable section of traction power supply is obtained. The grounding grid includes a plurality of temperature measurement nodes arranged at equal intervals along the 27.5 kV cable section of traction power supply. The voltage and current responses of the grounding grid when the local temperature rise value exceeds a preset reference value are collected, and the voltage and current responses are subjected to frequency domain conversion to generate a broadband impedance spectrum analysis result. The local temperature rise value is obtained from the temperature distribution data. According to the conductor topology structure of the grounding grid, the surface coordinates of the ground corresponding to the temperature measurement nodes are aligned with the underground coordinates of the impedance measurement points in the broadband impedance spectrum analysis result to generate a spatial correlation grid. The extreme value of the temperature rise rate is extracted from the spatial correlation grid, and the extreme value of the phase shift amount is extracted from the broadband impedance spectrum analysis result. Combining the extreme value of the temperature rise rate and the extreme value of the phase shift amount, a temperature rise-phase shift coupling relationship matrix is generated. According to the power frequency impedance correction value of the temperature rise-phase shift coupling relationship matrix, a real-time monitoring result of the power frequency resistance of the grounding grid is generated. The technical solution provided by the present invention realizes full-coverage monitoring of the surface temperature of the grounding grid through temperature measurement nodes arranged at equal intervals, overcomes the defect of the traditional single-point temperature measurement being lagging in response to local abnormal temperature rise, effectively identifies the change of the distribution parameters of the grounding grid by capturing the high-frequency current response triggered by local temperature rise, enhances the detection sensitivity to hidden defects such as conductor deterioration and local fracture, realizes three-dimensional space mapping of the surface temperature monitoring points and the underground impedance measurement points based on the topology structure, solves the problem of spatial mismatch between the ground temperature data and the underground electrical parameters in the prior art, reveals the non-linear correlation law between conductor temperature rise and electrical parameters by coupling the temperature change rate and the impedance phase shift characteristics, breaks through the limitation of the traditional method of analyzing thermal and electrical parameters in isolation, and eliminates the influence of high-frequency components on the calculation of power frequency resistance through the power frequency impedance correction mechanism of the coupling matrix, improving the reliability of the grounding grid state assessment in a strong electromagnetic interference environment. Among them, by breaking through the technical barrier of the spatial separation between the ground temperature data and the underground electrical state in the traditional grounding grid monitoring, the accurate spatial matching between the abnormal temperature rise area and the corresponding conductor impedance change is realized; by dynamically binding the impedance measurement points and the physical properties of the conductor segments, the adaptability of the monitoring network to the conductor extension direction and burial depth change is enhanced, and the omission of characteristic signals caused by the deployment of fixed measurement points is avoided.

[0016] These aspects or other aspects of the present invention will be more clearly understood in the following description of the embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0018] Figure 1 A flowchart of a method for real-time monitoring of the power frequency resistance of the grounding grid in the 27.5 kV cable section of the traction power supply provided by an embodiment of the present invention; Figure 2 A schematic structural diagram of a real-time monitoring system for the power frequency resistance of the grounding grid in the 27.5 kV cable section of the traction power supply provided by an embodiment of the present invention; Figure 3 A schematic structural diagram of a computing device provided by an embodiment of the present invention. Detailed implementation manners

[0019] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0020] In some processes described in the specification, claims and above-mentioned drawings of the present invention, a plurality of operations that appear in a specific order are included. However, it should be clearly understood that these operations may not be executed in the order in which they appear in this document or may be executed in parallel. The serial numbers of the operations, such as 101, 102, etc., are only used to distinguish different operations, and the serial numbers themselves do not represent any execution order. In addition, these processes may include more or fewer operations, and these operations may be executed in sequence or in parallel. It should be noted that the descriptions such as "first" and "second" in this document are used to distinguish different messages, devices, modules, etc., and do not represent a sequence, nor do they limit that "first" and "second" are of different types.

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present invention.

[0022] Figure 1 A flowchart of a method for real-time monitoring of the power frequency resistance of the grounding grid in the 27.5 kV cable section of the traction power supply provided by an embodiment of the present invention is as Figure 1 shown, and the method includes: Aiming at the problem that it is difficult to monitor the abnormal distributed temperature rise caused by conductor corrosion and poor contact in the traction power supply cable section grounding grid in real time, traditional methods are limited by single-point temperature detection and cannot correlate local overheating with power frequency resistance changes. Moreover, the power frequency impedance measurement is vulnerable to electromagnetic interference, resulting in misjudgment. The existing technologies lack a spatial matching mechanism for the underground conductor topology and the surface temperature field, leading to fuzzy fault location. The present invention realizes the dynamic perception of the temperature field through equally spaced temperature measurement nodes. When the local temperature rise is triggered, it collects the broadband impedance spectrum to capture the high-frequency characteristics of conductor deterioration. Combining the conductor topology, it three-dimensionally binds the surface temperature rise points and the underground impedance measurement points, constructs a coupling matrix of the temperature rise rate and phase shift, and finally eliminates the interference through dynamic correction of the power frequency impedance, forming a real-time monitoring scheme for the grounding grid resistance that takes into account spatial accuracy and anti-interference ability, breaking through the technical bottleneck of multi-parameter mismatch and hidden defect undetected in the traditional methods in complex underground structure scenarios. Based on this, the present invention provides a method for real-time monitoring of the power frequency resistance of the 27.5 kV cable section grounding grid for traction power supply, such as Figure 1 , including: Step 101: Obtain the temperature distribution data of the surface of the conductors of the grounding grid in the 27.5 kV cable section for traction power supply, where the grounding grid includes a plurality of temperature measurement nodes equally spaced along the 27.5 kV cable section for traction power supply.

[0023] In this step, the temperature distribution data refers to the set of surface temperatures of the grounding grid conductors periodically collected by equally spaced temperature measurement nodes, including the geographical coordinates, temperature values and timestamps of each node, and is used to reflect the local overheating abnormality of the conductors.

[0024] In the embodiment of the present invention, through a plurality of temperature measurement nodes (such as distributed optical fiber sensors or infrared temperature measurement devices) equally spaced along the 27.5 kV cable section for traction power supply, the surface temperature data of the grounding grid conductors is collected in real time to form temperature distribution data covering the entire cable section. This data includes the geographical location coordinates of each temperature measurement node and its corresponding temperature value, and constructs a dynamic temperature field model through periodic data upload (for example, sampling once every 10 seconds).

[0025] Step 102: Collect the voltage and current responses of the grounding grid when the local temperature rise value exceeds a preset reference value, perform frequency domain conversion on the voltage and current responses to generate a broadband impedance spectrum analysis result, and the local temperature rise value is obtained from the temperature distribution data.

[0026] In this step, the voltage-current response refers to the time-domain waveform data of voltage and current generated by the grounding grid under an external excitation signal (swept frequency or pulse), which is used to characterize the impedance characteristics of the conductor; the frequency-domain conversion operation refers to the process of converting the time-domain voltage-current signal into a frequency-domain impedance spectrum through fast Fourier transform (FFT), including the calculation between the amplitude obtained by dividing the voltage amplitude by the current amplitude and the phase obtained by subtracting the current phase from the voltage phase; the wide-frequency impedance spectrum analysis result refers to the impedance amplitude and phase angle curves covering the frequency range of 1 Hz - 10 MHz, which is used to identify the resonance frequency point shift caused by conductor deterioration.

[0027] In an embodiment of the present invention, when it is detected that the local temperature rise value exceeds a preset reference value (such as ambient temperature + 15°C), a high-frequency voltage-current acquisition device (such as a broadband mutual inductor) is triggered to inject a swept frequency signal (1 Hz - 10 MHz) into the grounding grid, and the time-domain waveforms of voltage and current are synchronously acquired; the time-domain signal is subjected to frequency-domain conversion through fast Fourier transform (FFT) to generate a wide-frequency impedance spectrum analysis result including amplitude-frequency characteristics and phase-frequency characteristics. Among them, this result is stored in the form of a two-dimensional curve with frequency as the horizontal axis and impedance amplitude and phase angle as the vertical axis, and the frequency band where the impedance amplitude drops by more than 30% (reflecting the characteristics of conductor deterioration) is focused on for analysis.

[0028] Step 103: According to the conductor topological structure of the grounding grid, align the surface coordinates corresponding to the temperature measurement nodes with the underground coordinates corresponding to the impedance measurement points in the wide-frequency impedance spectrum analysis result to generate a spatial correlation grid.

[0029] In this step, the alignment operation refers to the geometric association process of binding the surface temperature measurement points and the underground impedance measurement points to the same conductor segment through three-dimensional space coordinate mapping; the spatial correlation grid refers to a three-dimensional grid unit based on conductor topological segmentation, and each unit contains bound temperature, impedance data, and conductor attribute parameters.

[0030] In an embodiment of the present invention, based on the grounding grid conductor topological structure (including conductor segment length, branch connection point coordinates, and burial depth parameters), the surface plane coordinates (x, y) of the temperature measurement nodes are combined with the vertical coordinate (z) of the conductor burial depth to form three-dimensional coordinates (x, y, z); at the same time, the point with the maximum current density within the conductor segment (the underground coordinate corresponding to the lowest impedance amplitude point) is extracted from the wide-frequency impedance spectrum; through the spatial matching algorithm of geographic information system (GIS), the surface temperature measurement node coordinates and the underground impedance measurement point coordinates are three-dimensionally aligned to generate a grid-like spatial model including temperature-impedance correlation relationships, and each grid unit is bound with temperature data, impedance data, and conductor physical attributes.

[0031] Step 104: Extract the extreme value of the temperature rise rate from the spatial correlation grid, extract the extreme value of the phase offset from the broadband impedance spectrum analysis result, and combine the extreme value of the temperature rise rate and the extreme value of the phase offset to generate a temperature rise-phase offset coupling relationship matrix.

[0032] In this step, the extreme value of the phase offset refers to the maximum deviation amount (Δθ) of the phase angle in the broadband impedance spectrum relative to the reference value, reflecting the change in the dielectric properties of the conductor.

[0033] The temperature rise-phase offset coupling matrix: refers to a two-dimensional data table that quantifies the non-linear relationship between the temperature rise rate and the phase offset with the spatial grid as the unit, and is used for power frequency impedance correction.

[0034] In the embodiment of the present invention, the extreme value of the temperature rise rate (the maximum value of the temperature change rate ΔT / Δt) of each grid unit is extracted from the spatial correlation grid, and the corresponding extreme value of the phase offset (the maximum value of the phase angle change Δθ) in the broadband impedance spectrum is extracted; through multivariate regression analysis, a non-linear relationship function between the temperature rise rate and the phase offset is established, and is expressed in matrix form as: coupling coefficient = extreme value of temperature rise rate × extreme value of phase offset / reference temperature rise threshold.

[0035] Step 105: Generate the real-time monitoring result of the power frequency resistance of the grounding grid according to the power frequency impedance correction value of the temperature rise-phase offset coupling relationship matrix.

[0036] In this step, the power frequency impedance correction value refers to the dynamic compensation amount of the impedance value in the 50Hz power frequency band through the coupling matrix, eliminating the influence of temperature rise and high-frequency interference; the power frequency resistance refers to the equivalent resistance value of the grounding grid after correction at 50Hz frequency, which is used to evaluate the safety state of the grounding grid.

[0037] In the embodiment of the present invention, according to the power frequency impedance correction value (coupling coefficient × power frequency band impedance reference value) of each grid unit in the temperature rise-phase offset coupling matrix, dynamic compensation is performed on the traditional power frequency resistance measurement value; specifically, the weighted average algorithm is used to fuse the correction values of each grid according to the proportion of the conductor length, generate the power frequency resistance value that eliminates the influence of high-frequency interference and temperature rise, and finally output the real-time monitoring results of the overall and sectional resistances of the grounding grid.

[0038] For example, in the cable tunnel of a traction substation, fiber optic temperature measurement nodes are deployed every 5 meters along the 27.5 kV grounding grid; when a certain node detects a temperature rise reaching 25 °C (ambient reference 10 °C), a broadband signal source is triggered to inject a 1 - 100 kHz swept signal, and the voltage and current waveforms are synchronously collected; an impedance spectrum is generated through FFT, and it is identified that the impedance amplitude at the 2.4 kHz frequency point drops by 42%. Based on this, the deterioration point of the conductor 1.2 m underground is located; the temperature rise rate of 0.8 °C / s and the phase shift of 28° in this area are extracted to generate a grid cell with a coupling coefficient of 0.45; finally, the power frequency impedance is corrected according to the coupling coefficient, and the actual resistance value of 0.85 Ω (traditional measurement is 1.2 Ω) is output, accurately reflecting the corrosion state of the conductor.

[0039] In the embodiment of the present invention, full - coverage monitoring of the temperature field is achieved through equally - spaced temperature measurement nodes, and the limitation of traditional power frequency measurement is broken through by combining broadband impedance spectrum analysis; the problem of mismatch between ground temperature and underground electrical parameters is solved by the spatial correlation grid based on the conductor topology of the grounding grid; the hidden defect characteristics are revealed by the temperature - rise phase - shift coupling matrix, and finally, the power frequency resistance measurement accuracy is improved through dynamic correction. The overall solution significantly improves the early detection rate of faults such as local corrosion and poor contact in complex grounding grids and enhances the anti - interference ability in a strong electromagnetic interference environment.

[0040] The present invention provides a specific embodiment. Step 103: According to the conductor topology of the grounding grid, align the surface coordinates corresponding to the temperature measurement nodes with the underground coordinates corresponding to the impedance measurement points in the broadband impedance spectrum analysis result to generate a spatial correlation grid, which specifically includes the following steps: Step 301: According to the conductor topology of the grounding grid, obtain the length of the conductor segments, the positions of the branch connection points, and the vertical coordinates of the conductor burial depths corresponding to the branch connection points.

[0041] In this step, the conductor topology refers to the physical connection and spatial distribution relationship of the grounding grid conductors, including the connection methods between conductor segments, the number of branches and their directions, which are used to define the logical framework of the monitoring network; the conductor segments refer to the independent conductor segments separated by branch connection points in the grounding grid, and their lengths and spatial coordinates form the basic units of the topology; the branch connection points refer to the intersection positions of three or more conductor segments in the grounding grid, and their three - dimensional coordinates determine the conductor extension direction and the monitoring node deployment strategy.

[0042] In the embodiment of the present invention, according to the conductor topology of the grounding grid (i.e., the physical connection relationship and spatial distribution of the conductors), by analyzing the grounding grid design drawings or three - dimensional modeling data, the lengths of the conductor segments, the positions of the branch connection points, and the vertical coordinates of the conductor burial depths corresponding to the branch connection points are obtained. Specifically, the building information model tool BIM or underground pipeline detection equipment is used to extract the conductor burial depth parameters, and the data is formatted into a topology database containing segment numbers, coordinates, and burial depths.

[0043] Step 302: Determine the actual installation positions of the temperature measurement nodes according to the conductor segmentation and the positions of the branch connection points.

[0044] In this step, the actual installation position refers to the deployment coordinates of the temperature measurement nodes calculated based on the conductor segment length and the positions of the branch connection points, ensuring the coverage of the key monitoring areas along the entire length of the conductor.

[0045] In the embodiment of the present invention, according to the conductor segment length and the positions of the branch connection points, a spacing calculation algorithm is used to determine the actual installation positions of the temperature measurement nodes; for straight conductor segments, the number of nodes is obtained by dividing the segment length by the preset spacing, and they are deployed equidistantly along the extension direction of the conductor; for the branch connection points, the positions extending a preset distance from this point to the adjacent three conductor segments are used as the installation points to avoid signal interference caused by the nodes directly covering the connection points. The installation position coordinates are calibrated on-site by GPS or total station and associated with the conductor topology database.

[0046] Step 303: Screen out the frequency intervals in the broadband impedance spectrum analysis results where the decrease amplitude of the impedance amplitude within the conductor segment exceeds the preset decrease value, and according to the current distribution characteristics corresponding to the frequency intervals, determine that the coordinate point of the position with the maximum current density in the conductor segment is the impedance measurement point.

[0047] In this step, the impedance amplitude refers to the ratio of the voltage to the current amplitude at a specific frequency in the broadband impedance spectrum, reflecting the conductive performance of the conductor at this frequency; the frequency interval refers to the continuous frequency band in the broadband impedance spectrum where the impedance amplitude decreases by more than the preset threshold, used to locate the resonance characteristics caused by conductor deterioration; the current distribution characteristics refer to the spatial distribution law of the current density on the cross-section of the conductor, obtained by electromagnetic field simulation calculation, used to determine the position of the current concentration area; the impedance measurement point refers to the underground three-dimensional coordinates corresponding to the position with the maximum current density within the conductor segment, reflecting the potential fault points of conductor deterioration or fracture.

[0048] In the embodiment of the present invention, screen out the frequency intervals (such as 2 - 5 kHz) in the broadband impedance spectrum analysis results where the decrease amplitude of the impedance amplitude within the conductor segment exceeds the preset decrease value (such as 30%), calculate the current density distribution of the conductor cross-section through finite element electromagnetic simulation to extract the current distribution characteristics at each frequency point within this interval; according to the spatial coordinate point corresponding to the maximum current density (current density = total current of the conductor segment / cross-sectional area), combined with the geometric parameters of the conductor segment, such as length or orientation, determine the precise coordinates of this point in the underground three-dimensional space, marked as the impedance measurement point.

[0049] Step 304: Bind the surface coordinates corresponding to the actual installation positions of the temperature measurement nodes, the vertical coordinates of the conductor burial depth, and the underground coordinates corresponding to the impedance measurement points to generate a spatial correlation grid.

[0050] In this step, the vertical coordinate of the conductor burial depth refers to the vertical depth value of the conductor from the ground surface, which is obtained through underground detection or design drawings and is used to construct a three-dimensional monitoring network; the binding operation refers to the data fusion process of spatially correlating the surface temperature measurement node coordinates, the conductor burial depth coordinates, and the underground impedance measurement point coordinates, and establishing a multi-dimensional mapping relationship of temperature-impedance-position.

[0051] In the embodiment of the present invention, the surface plane coordinates (x, y) of the actual installation position of the temperature measurement node, the vertical coordinate (z) of the conductor burial depth, and the underground coordinates (x', y', z') of the impedance measurement point are subjected to a binding operation, that is, through a spatial coordinate transformation algorithm, the surface plane coordinates are vertically projected onto the plane corresponding to the conductor burial depth z, and the horizontal offset from the impedance measurement point is calculated. If the offset is less than a preset threshold, it is determined as the same conductor segmented correlation point, and finally a spatial correlation grid including the temperature-impedance-position mapping relationship is generated.

[0052] The embodiment of the present invention accurately calculates the deployment position of the temperature measurement node through the conductor topology structure, avoiding monitoring blind spots caused by blind layout; combines broadband impedance spectrum screening and current density analysis to dynamically locate the deterioration points of underground conductors; constructs a spatial correlation grid through three-dimensional coordinate binding to achieve the spatial consistency matching of surface temperature data and underground electrical parameters, significantly improving the fault location accuracy of complex branch structure grounding grids, and solving the problem of missing characteristic signals caused by the deployment of fixed measurement points in traditional methods.

[0053] The present invention provides a specific embodiment, step 304, binding the surface coordinates corresponding to the actual installation position of the temperature measurement node, the vertical coordinate of the conductor burial depth, and the underground coordinates corresponding to the impedance measurement point to generate a spatial correlation grid, which specifically includes the following steps: Step 341: Based on the length of the conductor segment and the position of the branch connection point, divide the grounding grid into multiple conductor segment units, where each conductor segment unit includes a temperature measurement node and an impedance measurement point.

[0054] In this step, the conductor segment unit refers to an independent monitoring area divided according to the conductor segment length and the branch connection point, including at least one temperature measurement node and an impedance measurement point, and is used to construct the minimum monitoring unit.

[0055] In the embodiment of the present invention, based on the length of the conductor segments and the positions of the branch connection points, a grid division algorithm is used to divide the grounding grid into multiple conductor segment units. Among them, the boundary of each conductor segment unit is determined by the two end branch connection points of the conductor segment, and at least one temperature measurement node and one impedance measurement point are compulsorily included in each unit; for a straight conductor segment, the unit length is equal to the length of the conductor segment; for the adjacent area of the branch connection point, the unit boundary extends to 1 / 3 of the length of the adjacent segment to ensure the spatial association continuity at the branch.

[0056] Step 342: Superimpose the surface coordinates corresponding to the actual installation positions of the temperature measurement nodes in each conductor segment unit with the vertical coordinates of the conductor burial depth to generate the three-dimensional monitoring coordinates corresponding to the temperature measurement nodes in each conductor segment unit.

[0057] In this step, the superimposing operation refers to the data fusion process of combining the surface plane coordinates (x, y) with the vertical coordinates of the conductor burial depth (z) into three-dimensional coordinates (x, y, z), which is used to establish a three-dimensional monitoring reference; the three-dimensional monitoring coordinates refer to the three-dimensional coordinates that fuse the surface position and the burial depth information, reflecting the precise position of the temperature measurement node in the three-dimensional space of the grounding grid.

[0058] In the embodiment of the present invention, the surface plane coordinates (x, y) corresponding to the actual installation positions of the temperature measurement nodes in each conductor segment unit are superimposed with the vertical coordinates of the conductor burial depth (z), that is, through the three-dimensional coordinate system conversion formula: (x, y, z) = (surface x, surface y, burial depth z), to generate the three-dimensional monitoring coordinates of the temperature measurement nodes. Among them, this coordinate is also associated with the number of the conductor segment unit for subsequent spatial binding.

[0059] Step 343: According to the underground coordinates corresponding to the impedance measurement points in each conductor segment unit, spatially bind the underground coordinates corresponding to the impedance measurement points in each conductor segment unit with the corresponding three-dimensional monitoring coordinates to generate the bound coordinate pairs of each conductor segment unit.

[0060] In this step, the spatial binding operation refers to the data matching process of associating the underground impedance measurement point coordinates with the three-dimensional coordinates of the surface temperature measurement nodes through distance threshold determination; the bound coordinate pairs refer to the associated data group composed of the three-dimensional monitoring coordinates and the impedance measurement point coordinates, which characterize the temperature-impedance spatial correspondence relationship of the same conductor segment unit.

[0061] In the embodiments of the present invention, for each conductor segment unit, the underground coordinates (x', y', z') of the impedance measurement point are associated with the three-dimensional monitoring coordinates (x, y, z) through a spatial binding operation. Specifically, the Euclidean distance calculation method is adopted. If the horizontal projection distance between the impedance measurement point and the three-dimensional monitoring coordinates is less than 10% of the conductor segment length (for example, if the segment length is 5 meters, the threshold is 0.5 meters), it is determined to be the same physical position, and a bound coordinate pair ((x, y, z), (x', y', z')) is generated.

[0062] Step 344: Aggregate the bound coordinate pairs of multiple conductor segment units adjacent to the position of the branch connection point with the vertical coordinate of the conductor burial depth to generate a branch topology node.

[0063] In this step, the aggregation operation refers to a data fusion method that takes the arithmetic mean of the coordinates of multiple bound coordinate pairs to generate the central position of the branch connection point; a branch topology node refers to the three-dimensional coordinates representing the spatial position of the branch connection point, which is generated by aggregating the bound coordinate pairs of adjacent conductor segment units and is used to describe complex branch structures.

[0064] In the embodiments of the present invention, for multiple conductor segment units adjacent to the position of the branch connection point, the three-dimensional monitoring coordinates and impedance measurement point coordinates in their bound coordinate pairs are extracted, and the geometric center point is calculated through an aggregation operation. Among them, the branch topology node coordinates are obtained by the following formula: (Σ three-dimensional monitoring coordinates + Σ impedance measurement point coordinates) / (2 × number of units), and the calculation result is fused with the vertical coordinate of the conductor burial depth to generate the topology node coordinates representing the branch connection point.

[0065] Step 345: Map the bound coordinate pairs and the branch topology nodes to generate a spatial connection grid.

[0066] In this step, the mapping operation refers to a spatial modeling process that constructs a continuous grid model based on the topological connection relationship for the discrete bound coordinate pairs and branch topology nodes.

[0067] In the embodiments of the present invention, the bound coordinate pairs and the branch topology nodes are topologically connected through a GIS spatial mapping algorithm; with the branch topology node as the hub, adjacent bound coordinate pairs are connected in series according to the conductor extension direction to form a grid-like spatial model covering the entire grounding grid area, and each grid node contains temperature, impedance, and three-dimensional coordinate attributes.

[0068] The embodiment of the present invention achieves refined monitoring granularity by dividing the conductor into segmented units, and eliminates the surface-underground data layer separation by combining three-dimensional coordinate superposition and spatial binding; the dynamic aggregation of branch topology nodes enhances the modeling capability of complex branch structures, and the spatial correlation grid finally formed breaks through the monitoring blind spots of traditional methods in multi-branch and three-dimensional wiring scenarios of grounding grids, significantly improving the positioning accuracy of local defects and the reliability of status assessment.

[0069] The present invention provides a specific embodiment, step 102, collecting the voltage and current responses of the grounding grid when the local temperature rise value exceeds a preset reference value, performing frequency domain conversion on the voltage and current responses to generate a broadband impedance spectrum analysis result, wherein the local temperature rise value is obtained from the temperature distribution data, specifically includes the following steps: Step 201: When the temperature rise value of at least one temperature measurement node in the temperature distribution data exceeds a preset reference value, it is determined that there is a local temperature rise anomaly in the grounding grid, and the voltage and current time domain waveform data at both ends of the grounding grid under the excitation signal are collected.

[0070] In this step, the excitation signal refers to a broadband swept-frequency signal injected into the grounding grid, with a frequency range of typically 0.1 Hz to 1 MHz, used to stimulate the electrical response of the grounding grid at different frequencies, including voltage and current signals. The voltage and current time domain waveform data refers to the original waveform data of the voltage and current at both ends of the grounding grid collected by the sensor over time, reflecting the instantaneous amplitude of the signal.

[0071] In an embodiment of the present invention, the temperature distribution data of each temperature measuring node of the grounding grid is first monitored in real time. When it is detected that the temperature rise value of at least one temperature measuring node exceeds a preset reference value (for example, the temperature rise threshold is set to 10°C), the system determines that there is a local temperature rise anomaly in the grounding grid and triggers a data acquisition action. Subsequently, an excitation signal in a preset frequency range (such as a 0.1Hz-1MHz sweep frequency signal) is injected into both ends of the grounding grid. In the case of a local temperature rise anomaly, the voltage time domain waveform data and the current time domain waveform data at both ends of the grounding grid are synchronously collected through a high-precision data acquisition card, and the two are stored with time stamp alignment.

[0072] Step 202: Divide the voltage and current time domain waveform data into multiple time domain data segments according to a preset time period, and remove the time domain data segments whose waveform distortion rate exceeds a preset distortion threshold to generate optimized voltage and current time domain waveform data.

[0073] In this step, the time-domain data segment refers to the data segment obtained by dividing the continuous time-domain waveform into fixed time lengths (such as 1 second) for segmented processing and analysis; the waveform distortion rate refers to the degree of deviation of the time-domain waveform from the ideal sine wave, obtained by calculating the ratio of the root mean square error, and is used to evaluate the signal quality; the optimized voltage and current time-domain waveform data refers to the time-domain data segments retained after screening by the waveform distortion rate, which have lower noise and distortion.

[0074] In the embodiment of the present invention, the voltage time-domain waveform data and the current time-domain waveform data are divided into multiple equal-length time-domain data segments according to a preset time period (for example, each 1 second is a period); then, the waveform distortion rate of each time-domain data segment is calculated, that is, the waveform peak value in the time-domain data segment is compared with the peak value of the theoretical sine waveform, and the ratio of the root mean square error between the two is calculated. If it exceeds the preset distortion threshold (such as 5%), it is considered that there is noise interference or signal distortion in this data segment and it is excluded; finally, the time-domain data segments with the waveform distortion rate meeting the requirements are retained to generate the optimized voltage time-domain waveform data and the optimized current time-domain waveform data.

[0075] Step 203: Perform windowed Fourier transform on each time-domain data segment in the optimized voltage and current time-domain waveform data to obtain the voltage spectrum and current spectrum corresponding to each time-domain data segment.

[0076] In this step, the windowed Fourier transform refers to an algorithm that performs Fourier transform on a time-domain signal after windowing, used to reduce spectral leakage and extract frequency-domain features; the voltage spectrum and current spectrum refer to the frequency-domain representation of the signal obtained by Fourier transform, including the amplitude and phase information of each frequency point.

[0077] In the embodiment of the present invention, perform windowed Fourier transform on each time-domain data segment in the optimized voltage time-domain waveform data and the current time-domain waveform data respectively, that is, use the Hann window function to perform windowing on the time-domain data segment to reduce spectral leakage, and then convert the time-domain signal into a frequency-domain signal through the fast Fourier transform to obtain the voltage spectrum and current spectrum corresponding to each time-domain data segment respectively.

[0078] Step 204: Extract the voltage effective value of each discrete frequency point from the voltage spectrum, and extract the current effective value of the corresponding discrete frequency point from the current spectrum to calculate the voltage-current phase difference and impedance amplitude corresponding to each discrete frequency point.

[0079] In this step, the discrete frequency point refers to the frequency sampling point divided at a fixed interval in the spectrum, used to extract parameters at a specific frequency; the voltage effective value and current effective value refer to the equivalent energy values calculated from the spectrum amplitude, reflecting the average power of the signal; the voltage-current phase difference refers to the phase angle difference between the voltage and current signals at the same frequency, used to calculate the phase characteristics of the impedance.

[0080] In an embodiment of the present invention, the effective value of the voltage at each discrete frequency point (for example, at intervals of 1 Hz) is extracted from the voltage spectrum, and the calculation formula is the square root of the voltage spectrum amplitude multiplied by the normalization coefficient; similarly, the effective value of the current at the corresponding discrete frequency point is extracted from the current spectrum; subsequently, the voltage-current phase difference at each discrete frequency point is calculated, that is, the voltage phase angle minus the current phase angle, and the impedance amplitude is calculated, and the formula is the effective value of the voltage divided by the effective value of the current.

[0081] Step 205: Correlate the voltage-current phase difference, impedance amplitude, and frequency value corresponding to each discrete frequency point into an impedance spectrum data entry.

[0082] In this step, the frequency value refers to the frequency parameter corresponding to the signal or impedance, and the unit is Hz.

[0083] In an embodiment of the present invention, the voltage-current phase difference, impedance amplitude, and frequency value (such as 50 Hz, 100 Hz, etc.) corresponding to each discrete frequency point are correlated into a structured data entry, that is, an impedance spectrum data entry, where each entry contains three fields: namely, the frequency value (unit: Hz), the phase difference (unit: degree), and the impedance amplitude (unit: Ω).

[0084] Step 206: Arrange all the impedance spectrum data entries in ascending order of the frequency value to generate a broadband impedance spectrum analysis result. During the arrangement process, the impedance spectrum data entries with the same frequency value are merged, and the abnormal entries whose impedance amplitude fluctuates beyond the preset range are excluded.

[0085] In this step, the impedance spectrum data entry refers to a structured data unit containing the frequency value, phase difference, and impedance amplitude, and is used to construct the impedance spectrum.

[0086] In an embodiment of the present invention, all the impedance spectrum data entries are arranged in ascending order of the frequency value to generate a broadband impedance spectrum analysis result. Among them, during the arrangement process, if there are entries with the same frequency value (such as measuring the same frequency point multiple times), they are merged into a single entry, and the average value of their impedance amplitudes is taken; at the same time, the abnormal entries whose impedance amplitude fluctuates beyond the preset range (such as the impedance change between adjacent frequency points exceeds 20%) are excluded; finally, the output broadband impedance spectrum analysis result is an impedance characteristic curve arranged in order of frequency, which is used to reflect the impedance response of the grounding grid at different frequencies.

[0087] In the embodiments of the present invention, through waveform distortion rate screening and windowing processing, the influence of noise on impedance calculation is effectively suppressed; meanwhile, by combining the temperature anomaly trigger mechanism and the broadband impedance spectrum, the correlation analysis between electrical parameters and thermal characteristics is realized; in addition, the impedance analysis is only started when there is an abnormal temperature rise in the embodiments, reducing the consumption of computing resources and improving the dynamic monitoring efficiency; finally, through the elimination of abnormal entries in the impedance spectrum and the frequency response curve, local corrosion or fracture faults of the grounding grid are accurately identified.

[0088] The present invention provides a specific embodiment. In step 203, perform windowed Fourier transform on each time-domain data segment in the optimized voltage and current time-domain waveform data to obtain the voltage spectrum and current spectrum corresponding to each time-domain data segment, which specifically includes the following steps: Step 231: Multiply the voltage waveform data and current waveform data in each time-domain data segment in the optimized voltage and current time-domain waveform data with a preset window function point by point to generate a windowed voltage waveform segment and a windowed current waveform segment.

[0089] In this step, the window function refers to a time-domain weighting function used to reduce spectral leakage, including Hanning window, Hamming window, etc. Its amplitude gradually decays to zero at both ends of the time domain, which is used to suppress the frequency-domain distortion caused by signal truncation; point-by-point multiplication refers to performing multiplication operations on each point of the window function and the corresponding points of the voltage and current time-domain waveform data to generate a windowed time-domain signal; the windowed voltage waveform segment and windowed current waveform segment refer to the time-domain signal segments after being weighted by the window function, having smooth start and end characteristics.

[0090] In the embodiments of the present invention, each time-domain data segment in the optimized voltage and current time-domain waveform data (such as a voltage waveform data segment and a current waveform data segment with a length of 1 second) is multiplied with a preset window function point by point. In specific operations, the length of the window function is the same as the number of sampling points of the time-domain data segment. The voltage value of each data point (such as the kth sampling point) is multiplied by the value at the corresponding position of the window function to generate a windowed voltage waveform segment; the current waveform data segment is processed in the same way to generate a windowed current waveform segment. [[ID=,12]]

[0091] Step 232: Determine a set of discrete frequency points according to the duration and sampling interval of the time-domain data segment.

[0092] In this step, the set of discrete frequency points refers to a set of discretized frequency analysis points calculated through the duration and sampling interval of the time-domain data segment, covering integer multiples of frequencies from 0 Hz to the Nyquist frequency.

[0093] In an embodiment of the present invention, according to the duration of the time-domain data segment (e.g., 1 second) and the sampling interval (e.g., 0.001 second, corresponding to a sampling rate of 1 kHz), the frequency resolution (e.g., 1 Hz) is determined by the formula fres = 1 / T, where T is the duration of the time-domain data segment; the set of discrete frequency points is determined by the frequency resolution, covering all integer multiple frequency points (e.g., 0 Hz, 1 Hz, 2 Hz,..., 500 Hz) from 0 Hz to the Nyquist frequency (i.e., half of the sampling rate, such as 500 Hz).

[0094] Step 233: Based on the set of discrete frequency points, perform discrete spectral conversion on the windowed voltage waveform segment and the current waveform segment respectively to obtain a voltage spectral sequence and a current spectral sequence.

[0095] In this step, discrete spectral conversion refers to the process of converting a time-domain signal into a frequency-domain complex spectrum using algorithms such as the fast Fourier transform. Each frequency point corresponds to real and imaginary components; the voltage spectral sequence and the current spectral sequence refer to the sequences composed of the complex spectrum values of discrete frequency points, reflecting the amplitude and phase characteristics of the signal at different frequencies.

[0096] In an embodiment of the present invention, based on the set of discrete frequency points, perform discrete spectral conversion on the windowed voltage waveform segment and the current waveform segment respectively, that is, use the fast Fourier transform algorithm to convert the time-domain signal into a frequency-domain signal to obtain a voltage spectral sequence and a current spectral sequence. Each spectral sequence contains complex spectrum values of multiple discrete frequency points, where each complex number is composed of a real part (in-phase component) and an imaginary part (orthogonal component). The complex number at the 50 Hz frequency point in the voltage spectral sequence is represented as V(50) = V_real + jV_imag.

[0097] Step 234: Extract the voltage real part value and the first imaginary part value of each discrete frequency point from the voltage spectral sequence to calculate the voltage effective value of each discrete frequency point.

[0098] In this step, the voltage real part value and the first imaginary part value refer to the in-phase component (real part) and the orthogonal component (imaginary part) of a certain frequency point in the voltage spectrum, which are used to calculate the effective value and the phase angle.

[0099] In an embodiment of the present invention, extract the voltage real part value (e.g., V_real) and the first imaginary part value (e.g., V_imag) of each discrete frequency point from the voltage spectral sequence, and calculate the voltage effective value through the formula, that is, take the square root after adding the square of the voltage real part value and the square of the first imaginary part value, and then multiply by the normalization coefficient (e.g., 1 / 2), that is, through frequency-domain parameter conversion, obtain the effective value reflecting the energy of the voltage signal.

[0100] Step 235: Extract the current real part value and the second imaginary part value of the corresponding discrete frequency point from the current spectral sequence to calculate the current effective value of each discrete frequency point.

[0101] In this step, the real part value of the current and the second imaginary part value refer to the in-phase component and the quadrature component of the corresponding frequency point in the current spectrum, which are extracted synchronously with the voltage spectrum parameters.

[0102] In the embodiment of the present invention, the real part value of the current (such as I_real) and the second imaginary part value (such as I_imag) corresponding to the discrete frequency points are extracted from the current spectrum sequence, and the root mean square value of the current is calculated through a formula, that is, the square root is taken after adding the square of the real part value of the current and the square of the second imaginary part value, and then multiplied by a normalization coefficient.

[0103] Step 236: Calculate the voltage-current phase difference for each discrete frequency point according to the real part value of the voltage, the real part value of the current, the imaginary part value of the voltage, and the imaginary part value of the current.

[0104] In this step, the calculation operation refers to the mathematical process of calculating the phase difference through the real and imaginary part values of the voltage and the current, which includes calculating the voltage phase angle and the current phase angle using the arctangent function, and performing a subtraction operation on the voltage phase angle and the current phase angle to obtain the voltage-current phase difference.

[0105] In the embodiment of the present invention, according to the real part value of the voltage, the real part value of the current, the imaginary part value of the voltage (i.e., the first imaginary part value), and the imaginary part value of the current (i.e., the second imaginary part value) of each discrete frequency point, the voltage-current phase difference is calculated, where the voltage phase angle θV = arctan(V_imag / V_real), the current phase angle θI = arctan(I_imag / I_real), and the phase difference Δθ = θV - θI. That is, through the arctangent function and the difference operation, the phase relationship between the voltage and current signals is accurately quantified.

[0106] Step 237: Bind the root mean square value of the voltage, the root mean square value of the current, and the voltage-current phase difference of each discrete frequency point to the corresponding frequency value to obtain a plurality of spectrum entries, and sort the plurality of spectrum entries to generate the voltage spectrum and the current spectrum corresponding to each time domain data segment.

[0107] In this step, the binding operation refers to the operation of associating the frequency value, the root mean square value of the voltage, the root mean square value of the current, and the phase difference as a data record, forming a structured spectrum entry; the spectrum entry refers to a data unit containing the voltage and current parameters at a single frequency point, which is used to construct the complete spectrum analysis result; the sorting operation refers to arranging the spectrum entries in ascending order of the frequency value to generate an ordered voltage spectrum and current spectrum.

[0108] In the embodiment of the present invention, the effective voltage value, effective current value, and voltage-current phase difference of each discrete frequency point are associated with the corresponding frequency value (such as 50 Hz) through a binding operation to form a structured data unit, that is, a spectrum entry. Each spectrum entry includes four fields: frequency value, effective voltage value, effective current value, and phase difference. Finally, all spectrum entries are sorted in ascending order of frequency value to generate the voltage spectrum and current spectrum corresponding to each time-domain data segment.

[0109] In the embodiment of the present invention, the window function is used to suppress spectrum leakage and reduce the interference of noise on the phase difference calculation, achieving the technical effect of improving the anti-interference ability; based on the accurate extraction of the real part and imaginary part, it ensures the high-precision calculation of the effective voltage and current values and the phase difference to optimize the calculation accuracy; through the binding and sorting of spectrum entries, a spectrum result in a unified format is generated, which is convenient for subsequent fault diagnosis and comparative analysis for standardized output of data; based on the complete coverage of the discrete frequency point set, it comprehensively reflects the impedance characteristics of the grounding grid at different frequencies to achieve effective coverage of broadband response.

[0110] The present invention provides a specific embodiment. Step 104: Extract the extreme value of the temperature rise rate from the spatial correlation grid, extract the extreme value of the phase offset from the broadband impedance spectrum analysis result, and combine the extreme value of the temperature rise rate and the extreme value of the phase offset to generate a temperature rise-phase offset coupling relationship matrix, which specifically includes the following steps: Step 401: Extract the extreme value of the temperature rise rate of each temperature measurement node in the preset time window from the spatial correlation grid.

[0111] In this step, the extreme value of the temperature rise rate refers to the maximum value of the temperature rise rate of the temperature measurement node in the preset time window, which is calculated by dividing the temperature change amount by the time interval and reflects the abnormal heating intensity of the local conductor.

[0112] In the embodiment of the present invention, the temperature change data of each temperature measurement node in the preset time window (such as 10 minutes) is obtained from the spatial correlation grid. The temperature rise rate curve is obtained by calculating the first derivative of the temperature with respect to time, and the maximum value point (such as the local peak) in the curve is extracted as the extreme value of the temperature rise rate, that is, the sliding window difference calculation is performed on the temperature sequence of each temperature measurement node, and the formula is ΔT / Δt (temperature change amount divided by time interval), and the extreme value points exceeding the preset threshold (such as 5 °C / min) are screened out.

[0113] Step 402: Extract the extreme value of the phase offset corresponding to each impedance measurement point from the broadband impedance spectrum analysis result.

[0114] In this step, the extreme value of the phase offset corresponding to the impedance measurement point refers to the maximum or minimum value of the phase difference between the voltage and current at a certain impedance measurement point under specific frequencies in the broadband impedance spectrum analysis, which is used to characterize the abnormal offset degree of the conductor impedance characteristics.

[0115] In the embodiment of the present invention, the phase offset data corresponding to each impedance measurement point (such as both ends of the segmented conductor of the grounding grid) is extracted from the broadband impedance spectrum analysis result. By traversing the recorded phase differences at all discrete frequency points, the maximum and minimum values of the phase offset are screened out (for example, the extreme values with a phase difference reaching ±15° at 50 Hz frequency).

[0116] Step 403: According to the binding relationship between the conductor segmented unit and the temperature measurement node and the impedance measurement point in the spatial correlation grid, associate the extreme value of the temperature rise rate and the extreme value of the phase offset corresponding to each conductor segmented unit to generate a coupling parameter pair.

[0117] In this step, the binding relationship refers to the predefined spatial association rule between the conductor segmented unit and the temperature measurement node and the impedance measurement point. For example, a conductor segmented unit binds the temperature measurement nodes on its left and right sides and its own impedance measurement point; the association operation refers to the operation of combining the extreme value of the temperature rise rate and the extreme value of the phase offset corresponding to the same conductor segmented unit into a data pair, which is used to establish a joint analysis unit for thermal - electrical parameters; the coupling parameter pair refers to the data pair composed of the extreme value of the temperature rise rate and the extreme value of the phase offset, such as (12 °C / min, -10°), which is used to comprehensively reflect the thermoelectric abnormal state of the conductor.

[0118] In the embodiment of the present invention, according to the binding relationship (such as each conductor segmented unit is associated with 2 temperature measurement nodes and 1 impedance measurement point) predefined in the spatial correlation grid, the extreme value of the temperature rise rate (such as 12 °C / min) and the extreme value of the phase offset (such as -10°) corresponding to the conductor segmented unit are subjected to the association operation to generate a coupling parameter pair. Among them, each coupling parameter pair contains two fields, namely the extreme value of the temperature rise rate (unit: °C / min) and the extreme value of the phase offset (unit: °).

[0119] Step 404: Based on the conductor topology of the grounding grid, map the coupling parameter pair corresponding to each conductor segmented unit to the rows and columns of a preset matrix to generate a temperature rise - phase offset coupling relationship matrix.

[0120] In this step, the mapping operation refers to the process of allocating the coupling parameter pair to the rows and columns of the matrix according to the conductor topology. For example, it is mapped to matrix elements according to the level and orientation to form a spatialized data analysis structure.

[0121] In an embodiment of the present invention, through the row index, column index, and matrix element values of the conductor topology structure of the grounding grid, the coupling parameter pairs corresponding to each conductor segment unit are mapped to the preset matrix rows and columns to generate a temperature rise phase shift coupling relationship matrix. If the matrix shows that the position parameters of the conductor segment unit are abnormal, combined with topological analysis, it is determined that there is a capacitive overheating fault caused by insulation deterioration in the column index branch conductor.

[0122] In an embodiment of the present invention, through the coupling analysis of the temperature rise rate and the phase shift amount, the discrimination accuracy of fault types (such as overheating, corrosion) is improved, and multi-parameter fusion diagnosis is realized; based on the matrix mapping of the conductor topology, the spatial distribution of the abnormal area is intuitively displayed, supporting rapid fault point location, enhancing the spatial correlation; through the extraction of extreme values within the time window, transient abnormal signals are captured to avoid missed detection and improve the dynamic monitoring ability; by mapping complex thermoelectric parameters into a matrix structure, the analysis complexity under a large amount of data is simplified, thereby performing data dimensionality reduction processing.

[0123] The present invention provides a specific embodiment. Step 105: Generate a real-time monitoring result of the power frequency resistance of the grounding grid according to the power frequency impedance correction value of the temperature rise phase shift coupling relationship matrix, which specifically includes the following steps: Step 501: Screen out a plurality of target matrix elements from the temperature rise phase shift coupling relationship matrix, and use the target matrix elements as key correction factors. The target matrix elements are matrix elements whose extreme values of the temperature rise rate and the phase shift amount both exceed a preset threshold.

[0124] In this step, the target matrix element refers to a matrix unit in the temperature rise phase shift coupling relationship matrix that simultaneously satisfies the condition that the extreme value of the temperature rise rate and the extreme value of the phase shift amount exceed a preset threshold, and is used to identify the conductor abnormally sensitive area; the key correction factor refers to the coupling coefficient value extracted from the target matrix element, which reflects the comprehensive influence intensity of local temperature rise and phase shift on the power frequency impedance.

[0125] In an embodiment of the present invention, screening the target matrix elements from the temperature rise phase shift coupling relationship matrix specifically means matrix units that simultaneously satisfy the condition that the extreme value of the temperature rise rate (ΔT / Δt) exceeds a preset temperature rise threshold (for example, 0.5 °C / s) and the extreme value of the phase shift amount (Δθ) exceeds a preset phase threshold (for example, 20°); by traversing all elements of the matrix through a threshold determination algorithm, the qualified elements are marked as key correction factors, which are used to characterize the significant influence area of conductor local abnormality on the power frequency impedance.

[0126] Step 502: Calculate the weight coefficients of each key correction factor according to the proportional relationship between the extreme value of the temperature rise rate and the extreme value of the phase shift amount corresponding to each key correction factor.

[0127] In this step, the calculation operation refers to a data processing process of determining the contribution weights of each key correction factor through the proportional relationship and normalization of the extreme value of the temperature rise rate and the extreme value of the phase offset; the weight coefficient refers to a proportional parameter that quantifies the influence degree of the key correction factor on the overall correction value, and the sum is 1, which is used for weighted superposition calculation.

[0128] In the embodiment of the present invention, according to the proportional relationship between the extreme value of the temperature rise rate and the extreme value of the phase offset corresponding to the key correction factor, the weight coefficient is calculated, that is: (extreme value of the temperature rise rate / temperature rise threshold) × (extreme value of the phase offset / phase threshold), and then the calculation results of all key correction factors are normalized (each weight coefficient is divided by the sum), so that the sum of the weight coefficients is 1; this process is implemented through a numerical normalization algorithm to ensure that the contribution degrees of the correction factors in different regions are distributed proportionally.

[0129] Step 503: According to the weight coefficient, each key correction factor is superimposed to generate a power frequency impedance region correction value.

[0130] In this step, the superimposing operation refers to a calculation method of multiplying each key correction factor by its weight coefficient and then accumulating to generate a comprehensive correction value to eliminate local interference; the power frequency impedance region correction value refers to an impedance compensation amount obtained by weighted calculation of the key correction factor, which is used to correct the error in the traditional power frequency measurement value.

[0131] In the embodiment of the present invention, the superimposing operation is used to multiply each key correction factor by its weight coefficient and then accumulate to generate a power frequency impedance region correction value. For example, if the three key correction factors are 0.6, 0.8, and 1.0 respectively, and the weight coefficients are 0.2, 0.3, and 0.5 respectively, then the region correction value = 0.6×0.2 + 0.8×0.3 + 1.0×0.5 = 0.12 + 0.24 + 0.5 = 0.86. Among them, the region correction value is used to dynamically correct the power frequency impedance measurement value.

[0132] Step 504: Map the power frequency impedance region correction value to the corresponding conductor segment unit in the spatial connection network grid to generate a real-time monitoring result of the power frequency resistance of the grounding grid.

[0133] In this step, the mapping operation refers to a data matching process of dynamically associating the correction value according to the distribution of the conductor segment units of the spatial connection network grid to ensure that the correction value acts on the corresponding physical position; the real-time monitoring result of the power frequency resistance refers to the 50Hz equivalent resistance value corrected by the region correction value, which dynamically reflects the conductive state of the overall and segmented grounding grid.

[0134] In the embodiment of the present invention, the power frequency impedance region correction value is associated with the corresponding conductor segment unit in the spatial connection network grid through a mapping operation, that is, according to the position index of the matrix element to which the correction value belongs, the conductor segment unit number in the spatial connection network grid is matched, the correction value is multiplied by the ratio of the unit conductor length (unit conductor length / total length of the grounding grid), and finally the overall power frequency resistance value is obtained by accumulating the contribution values of all units to realize the dynamic output of the real-time monitoring result.

[0135] The embodiment of the present invention focuses on local abnormal regions by screening key correction factors, and combines weight coefficient allocation to enhance the physical rationality of the correction logic; superposition calculation and spatial mapping operation are used to realize the dynamic compensation of abnormal effects, break through the problem of overall error accumulation caused by local interference in traditional power frequency resistance measurement, and significantly improve the accuracy and anti-interference ability of grounding grid state evaluation under complex working conditions.

[0136] Figure 2 FIG. is a schematic structural diagram of a real-time monitoring system for the power frequency resistance of a grounding grid in a 27.5 kV cable section of a traction power supply provided by an embodiment of the present invention, as Figure 2 shown, the system includes: An acquisition module 21, configured to acquire temperature distribution data on the surface of the conductors of the grounding grid in a 27.5 kV cable section of a traction power supply, where the grounding grid includes a plurality of temperature measurement nodes arranged at equal intervals along the 27.5 kV cable section of the traction power supply; A conversion module 22, configured to collect the voltage and current responses of the grounding grid when the local temperature rise value exceeds a preset reference value, and perform frequency domain conversion on the voltage and current responses to generate a broadband impedance spectrum analysis result, where the local temperature rise value is obtained from the temperature distribution data; An alignment module 23, configured to align the surface coordinates corresponding to the temperature measurement nodes with the underground coordinates corresponding to the impedance measurement points in the broadband impedance spectrum analysis result according to the conductor topology of the grounding grid to generate a spatial connection network grid; An extraction module 24, configured to extract the extreme value of the temperature rise rate from the spatial connection network grid, extract the extreme value of the phase offset from the broadband impedance spectrum analysis result, and generate a temperature rise phase offset coupling relationship matrix by combining the extreme value of the temperature rise rate and the extreme value of the phase offset; A generation module 25, configured to generate a real-time monitoring result of the power frequency resistance of the grounding grid according to the power frequency impedance correction value of the temperature rise phase offset coupling relationship matrix.

[0137] Figure 2 The real-time monitoring system for the power frequency resistance of a grounding grid in a 27.5 kV cable section of a traction power supply can execute Figure 1For the real-time monitoring method of the power frequency resistance of the grounding grid in the 27.5 kV cable section of traction power supply described in the illustrated embodiment, its implementation principle and technical effects will not be elaborated further. For the real-time monitoring system of the power frequency resistance of the grounding grid in the 27.5 kV cable section of traction power supply in the above embodiment, the specific ways for each module and unit to perform operations have been described in detail in the embodiments related to this method, and will not be elaborated here.

[0138] In a possible design, Figure 2 The real-time monitoring system of the power frequency resistance of the grounding grid in the 27.5 kV cable section of traction power supply in the illustrated embodiment can be implemented as a computing device, such as Figure 3 as shown, the computing device may include a storage component 31 and a processing component 32; The storage component 31 stores one or more computer instructions, wherein the one or more computer instructions are called and executed by the processing component 32.

[0139] The processing component 32 is configured to: obtain the temperature distribution data on the surface of the conductor of the grounding grid in the 27.5 kV cable section of traction power supply, where the grounding grid includes a plurality of temperature measurement nodes arranged at equal intervals along the 27.5 kV cable section of traction power supply; collect the voltage and current responses of the grounding grid when the local temperature rise value exceeds a preset reference value, perform frequency domain conversion on the voltage and current responses to generate a broadband impedance spectrum analysis result, and the local temperature rise value is obtained from the temperature distribution data; align the surface coordinates corresponding to the temperature measurement nodes with the underground coordinates corresponding to the impedance measurement points in the broadband impedance spectrum analysis result according to the conductor topology structure of the grounding grid to generate a spatial correlation grid; extract the extreme value of the temperature rise rate from the spatial correlation grid, extract the extreme value of the phase offset from the broadband impedance spectrum analysis result, and generate a temperature rise-phase offset coupling relationship matrix by combining the extreme value of the temperature rise rate and the extreme value of the phase offset; generate the real-time monitoring result of the power frequency resistance of the grounding grid according to the power frequency impedance correction value of the temperature rise-phase offset coupling relationship matrix.

[0140] Among them, the processing component 32 may include one or more processors to execute computer instructions to complete all or part of the steps in the above method. Of course, the processing component may also be implemented by one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), controllers, microcontrollers, microprocessors or other electronic components for executing the above method.

[0141] The storage component 31 is configured to store various types of data to support the operation of the terminal. The storage component can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic memory, flash memory, magnetic disk or optical disk.

[0142] Of course, the computing device may also necessarily include other components, such as input / output interfaces, display components, communication components, etc.

[0143] The input / output interface provides an interface between the processing component and the peripheral interface module, and the above-mentioned peripheral interface module can be an output device, an input device, etc.

[0144] The communication component is configured to facilitate communication between the computing device and other devices in a wired or wireless manner, etc.

[0145] Among them, the computing device can be a physical device or an elastic computing host provided by a cloud computing platform, etc. At this time, the computing device can refer to a cloud server, and the above-mentioned processing component, storage component, etc. can be basic server resources leased or purchased from a cloud computing platform.

[0146] The embodiment of the present invention also provides a computer storage medium storing a computer program, and when the computer program is executed by a computer, it can implement the above-mentioned Figure 1 real-time monitoring method for the power frequency resistance of the traction power supply 27.5 kV cable section grounding grid shown in the embodiment.

[0147] Those skilled in the art can clearly understand that for the convenience and brevity of description, the specific working processes of the above-described systems, devices, and units can refer to the corresponding processes in the foregoing method embodiments, and will not be elaborated herein.

[0148] The device embodiments described above are only illustrative. The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place, or may be distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art can understand and implement it without creative labor.

[0149] Through the description of the above embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on this understanding, the essence of the above technical solution, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0150] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A real-time monitoring method for the power frequency resistance of the grounding grid in the 27.5 kV cable section of traction power supply, characterized in that Including: Obtaining temperature distribution data of the surface of the conductor of the grounding grid in the 27.5 kV cable section of traction power supply, where the grounding grid includes a plurality of temperature measurement nodes arranged at equal intervals in the 27.5 kV cable section of traction power supply; Collecting the voltage and current responses of the grounding grid when the local temperature rise value exceeds a preset reference value, and performing frequency domain conversion on the voltage and current responses to generate a broadband impedance spectrum analysis result, where the local temperature rise value is obtained from the temperature distribution data; According to the conductor topology of the grounding grid, aligning the surface coordinates corresponding to the temperature measurement nodes with the underground coordinates corresponding to the impedance measurement points in the broadband impedance spectrum analysis result to generate a spatial correlation grid; Extracting the extreme value of the temperature rise rate from the spatial correlation grid, extracting the extreme value of the phase shift amount from the broadband impedance spectrum analysis result, and combining the extreme value of the temperature rise rate and the extreme value of the phase shift amount to generate a temperature rise-phase shift coupling relationship matrix; Generating a real-time monitoring result of the power frequency resistance of the grounding grid according to the power frequency impedance correction value of the temperature rise-phase shift coupling relationship matrix.

2. The method according to claim 1, wherein According to the conductor topology of the grounding grid, aligning the surface coordinates corresponding to the temperature measurement nodes with the underground coordinates corresponding to the impedance measurement points in the broadband impedance spectrum analysis result to generate a spatial correlation grid, including: According to the conductor topology of the grounding grid, obtaining the length of the conductor segment, the position of the branch connection point, and the vertical coordinate of the conductor burial depth corresponding to the branch connection point; Determining the actual installation position of the temperature measurement node according to the conductor segment and the position of the branch connection point; Selecting from the broadband impedance spectrum analysis result the frequency range in which the decrease amplitude of the impedance amplitude in the conductor segment exceeds a preset decrease value, and determining the coordinate point of the position with the largest current density in the conductor segment as the impedance measurement point according to the current distribution characteristics corresponding to the frequency range; Binding the surface coordinates corresponding to the actual installation position of the temperature measurement node, the vertical coordinate of the conductor burial depth, and the underground coordinates corresponding to the impedance measurement point to generate a spatial correlation grid.

3. The method according to claim 2, wherein Binding the surface coordinates corresponding to the actual installation position of the temperature measurement node, the vertical coordinate of the conductor burial depth, and the underground coordinates corresponding to the impedance measurement point to generate a spatial correlation grid, including: Based on the length of the conductor segment and the position of the branch connection point, dividing the grounding grid into a plurality of conductor segment units, where each conductor segment unit contains a temperature measurement node and an impedance measurement point; Superimposing the surface coordinates corresponding to the actual installation position of the temperature measurement node in each conductor segment unit with the vertical coordinate of the conductor burial depth to generate the three-dimensional monitoring coordinates corresponding to the temperature measurement node in each conductor segment unit; According to the underground coordinates corresponding to the impedance measurement point in each conductor segment unit, spatially binding the underground coordinates corresponding to the impedance measurement point in each conductor segment unit with the corresponding three-dimensional monitoring coordinates to generate a binding coordinate pair for each conductor segment unit; Aggregating the binding coordinate pairs of a plurality of conductor segment units adjacent to the position of the branch connection point with the vertical coordinate of the conductor burial depth to generate a branch topology node; The binding coordinate pairs and the branch topology nodes are mapped to generate a spatial association grid.

4. The method according to claim 1, wherein Collecting the voltage and current responses of the grounding grid when the local temperature rise value exceeds a preset reference value, performing frequency domain conversion on the voltage and current responses to generate a broadband impedance spectrum analysis result, wherein the local temperature rise value is obtained from the temperature distribution data, including: When the temperature rise value of at least one temperature measurement node in the temperature distribution data exceeds a preset reference value, it is determined that there is a local temperature rise abnormality in the grounding grid, and the voltage and current time domain waveform data at both ends of the grounding grid under the excitation signal are collected; Dividing the voltage and current time domain waveform data into a plurality of time domain data segments according to a preset time period, and removing the time domain data segments whose waveform distortion rate exceeds a preset distortion threshold, so as to generate optimized voltage and current time domain waveform data; Performing a windowed Fourier transform on each time domain data segment in the optimized voltage and current time domain waveform data to obtain a voltage spectrum and a current spectrum corresponding to each time domain data segment; Extracting the voltage effective value of each discrete frequency point from the voltage spectrum, and extracting the current effective value corresponding to the discrete frequency point from the current spectrum, so as to calculate the voltage-current phase difference and impedance amplitude corresponding to each discrete frequency point; Associating the voltage and current phase difference, impedance amplitude and frequency value corresponding to each discrete frequency point into an impedance spectrum data entry; All impedance spectrum data entries are arranged in ascending order of frequency value to generate broadband impedance spectrum analysis results. During the arrangement process, impedance spectrum data entries with the same frequency value are merged, and abnormal entries with impedance amplitude fluctuations exceeding the preset range are eliminated.

5. The method according to claim 4, wherein Performing a windowed Fourier transform on each time domain data segment in the optimized voltage and current time domain waveform data to obtain a voltage spectrum and a current spectrum corresponding to each time domain data segment, including: Multiplying the voltage waveform data and the current waveform data in each time domain data segment of the optimized voltage and current time domain waveform data by a preset window function point by point to generate windowed voltage waveform segments and current waveform segments; Determining a discrete frequency point set according to the duration and sampling interval of the time domain data segment; Based on the discrete frequency point set, discrete spectrum conversion is performed on the windowed voltage waveform segment and current waveform segment to obtain a voltage spectrum sequence and a current spectrum sequence; Extracting the voltage real part value and the first imaginary part value of each discrete frequency point from the voltage spectrum sequence to calculate the effective value of the voltage at each discrete frequency point; Extracting the current real part value and the second imaginary part value corresponding to the discrete frequency point from the current spectrum sequence to calculate the effective value of the current at each discrete frequency point; Calculate the voltage and current phase difference at each discrete frequency point based on the voltage real part value, current real part value, voltage imaginary part value and current imaginary part value at each discrete frequency point; The voltage RMS value, current RMS value, and voltage-current phase difference of each discrete frequency point are bound to the corresponding frequency value to obtain multiple spectrum entries. The multiple spectrum entries are sorted to generate the voltage spectrum and current spectrum corresponding to each time domain data segment.

6. The method according to claim 1, characterized in that Extract the extreme value of the temperature rise rate from the spatial correlation grid, extract the extreme value of the phase offset from the broadband impedance spectrum analysis result, and combine the extreme value of the temperature rise rate and the extreme value of the phase offset to generate a temperature rise-phase offset coupling relationship matrix, including: Extract the extreme value of the temperature rise rate of each temperature measurement node in the preset time window from the spatial correlation grid; Extract the extreme value of the phase offset corresponding to each impedance measurement point from the broadband impedance spectrum analysis result; According to the binding relationship between the conductor segment units, temperature measurement nodes, and impedance measurement points in the spatial correlation grid, associate the extreme value of the temperature rise rate and the extreme value of the phase offset corresponding to each conductor segment unit to generate a coupling parameter pair; Based on the conductor topology of the grounding grid, map the coupling parameter pairs corresponding to each conductor segment unit into the rows and columns of a preset matrix to generate a temperature rise-phase offset coupling relationship matrix.

7. The method according to claim 1, characterized in that Generate the real-time monitoring result of the power frequency resistance of the grounding grid according to the power frequency impedance correction value of the temperature rise-phase offset coupling relationship matrix, including: Screen out multiple target matrix elements from the temperature rise-phase offset coupling relationship matrix, and use the target matrix elements as key correction factors. The target matrix elements are matrix elements where both the extreme value of the temperature rise rate and the extreme value of the phase offset exceed a preset threshold; Calculate the weight coefficient of each key correction factor according to the proportional relationship between the extreme value of the temperature rise rate and the extreme value of the phase offset corresponding to each key correction factor; Superimpose each key correction factor according to the weight coefficient to generate a power frequency impedance regional correction value; Map the power frequency impedance regional correction value into the corresponding conductor segment unit in the spatial correlation grid to generate the real-time monitoring result of the power frequency resistance of the grounding grid.

8. A real-time monitoring system for the power frequency resistance of the grounding grid in the 27.5 kV cable section of traction power supply, characterized in that, Including: An acquisition module for acquiring the temperature distribution data on the surface of the conductor of the grounding grid in the 27.5 kV cable section of the traction power supply. The grounding grid includes a plurality of temperature measurement nodes arranged at equal intervals along the 27.5 kV cable section of the traction power supply; A conversion module for collecting the voltage-current response of the grounding grid when the local temperature rise value exceeds a preset reference value, and performing frequency domain conversion on the voltage-current response to generate a broadband impedance spectrum analysis result. The local temperature rise value is obtained from the temperature distribution data; An alignment module for aligning the surface coordinates corresponding to the temperature measurement nodes with the underground coordinates corresponding to the impedance measurement points in the broadband impedance spectrum analysis result according to the conductor topology of the grounding grid to generate a spatial correlation grid; An extraction module for extracting the extreme value of the temperature rise rate from the spatial correlation grid, extracting the extreme value of the phase offset from the broadband impedance spectrum analysis result, and combining the extreme value of the temperature rise rate and the extreme value of the phase offset to generate a temperature rise-phase offset coupling relationship matrix; A generation module for generating the real-time monitoring result of the power frequency resistance of the grounding grid according to the power frequency impedance correction value of the temperature rise-phase offset coupling relationship matrix.

9. A computing device, characterized in that, It includes a processing component and a storage component; the storage component stores one or more computer instructions; the one or more computer instructions are used to be called and executed by the processing component to implement a method for real-time monitoring of the power frequency resistance of the traction power supply 27.5 kV cable section grounding grid as described in any one of claims 1 to 7.

10. A computer storage medium, characterized in that, A computer program is stored, and when the computer program is executed by a computer, it implements a method for real-time monitoring of the power frequency resistance of the traction power supply 27.5 kV cable section grounding grid as described in any one of claims 1 to 7.

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