Method for modeling and positioning of electromagnetic interference sources in a substation based on multi-physical field coupling

Abstract

The application discloses a substation electromagnetic interference source modeling and positioning method based on multi-physical field coupling, relates to the technical field of interference positioning, and is used for solving the problem of insufficient positioning precision of electromagnetic interference sources. Ground potential data of a ground net monitoring node is collected, a potential deviation index is calculated, and it is judged whether there is a drainage anomaly. When the anomaly occurs, the ground impedance data of a marked grounding electrode is accessed from a historical database, impedance fluctuation trends are analyzed, and drainage current amounts of each drainage direction are detected. The grounding electrode is marked in combination with drainage imbalance characteristics, and an abnormal corrosion area is divided and screened. Surface magnetic field data and surface temperature data of each divided area are acquired. A drainage concentration coefficient is calculated through magnetic field distribution characteristics and a surface temperature coefficient, a positioning index is generated in combination with drainage path data, a drainage positioning area is screened, and the corrosion positioning precision of the ground net and the maintenance effectiveness are improved.

Description

Technical Field

[0001] This invention relates to the field of interference localization technology, and more specifically, to a method for modeling and locating electromagnetic interference sources in substations based on multi-physics coupling. Background Technology

[0002] The substation grounding grid plays a crucial role in the operation of the power system, including fault current discharge, electromagnetic shielding, and potential equalization. Its structural integrity and conductivity directly affect the electromagnetic environment stability and operational safety of the equipment in the substation. With the widespread deployment of large-scale power electronic devices, flexible transmission equipment, and intelligent terminals in substations, the multi-source coupling effect of power frequency current, high-order harmonic current, and transient impulse current in the substation area has been significantly enhanced.

[0003] The existing technology has the following shortcomings:

[0004] Currently, existing technologies typically rely on a single electrical parameter to determine the health status of the grounding grid, lacking a mechanism for dynamically marking abnormal grounding electrodes based on historical impedance fluctuation trends. This makes it impossible to achieve joint modeling of cross-physical field coupling characteristics and spatial positioning of leakage offset paths. Consequently, complex leakage behaviors such as leakage channel blockage and bypass diffusion caused by corrosion cannot be identified in a timely manner, and the electromagnetic interference source positioning range is large but the accuracy is insufficient. Therefore, a substation electromagnetic interference source modeling and positioning method based on multi-physical field coupling is proposed. Summary of the Invention

[0005] To overcome the aforementioned deficiencies of the prior art, embodiments of the present invention provide a substation electromagnetic interference source modeling and localization method based on multi-physics field coupling. This method solves the problems mentioned in the background art by employing a comprehensive localization mechanism that utilizes ground potential shift analysis, historical impedance trend modeling, multi-directional imbalance feature identification of leakage current, and coupling inversion of the surface magnetic field and temperature field.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for modeling and locating electromagnetic interference sources in substations based on multi-physics coupling, comprising the following steps:

[0007] Step S1: Obtain the grounding potential data of the grounding grid in the area to be tested, analyze the potential deviation status using the grounding potential data and determine whether to detect the grounding electrode. When detecting the grounding electrode, access the historical database to retrieve the grounding impedance data of the grounding electrode.

[0008] Step S2: Analyze the impedance fluctuation trend based on the grounding impedance data, divide the leakage direction of the grounding electrode, detect the leakage current in each leakage direction and evaluate the leakage balance characteristics of the grounding electrode, and mark the grounding electrode in combination with the impedance fluctuation trend.

[0009] Step S3: Divide the grounding grid into regions according to the marked grounding electrodes and screen abnormal corrosion areas. Set the positioning evaluation cycle and detect the surface magnetic field data and surface temperature data of the divided areas within the positioning evaluation cycle.

[0010] Step S4: Analyze the surface magnetic field data to generate magnetic field distribution characteristics, combine the surface temperature data to generate the discharge concentration coefficient for the divided areas, collect discharge path data between the abnormal corrosion area and the divided areas, and filter the discharge location area by combining the discharge concentration coefficient.

[0011] In a preferred embodiment, in step S1, several representative grounding points are selected as monitoring nodes according to the topology of the substation grounding network and the conductor layout.

[0012] Ground potential sensors are installed at monitoring nodes, and the instantaneous ground potential value of each monitoring node relative to the reference electrode is obtained in real time by measuring the potential difference compared with the reference electrode buried far away from the influence range of the grounding grid.

[0013] The instantaneous grounding potential value detected within the preset observation period will be used as the grounding potential data of the grounding grid in the area to be tested;

[0014] The grounding potential data of the monitoring nodes are aligned with the time series, and the potential offset of each monitoring node within the observation period is calculated.

[0015] Potential offset is defined as the degree of deviation of the instantaneous grounding potential value of a monitoring node from the average instantaneous grounding potential of the grid.

[0016] In a preferred embodiment, in step S1, the maximum value of the potential offset in all monitoring nodes is taken as the potential offset index of the grounding grid. When the potential offset index of the grounding grid is greater than or equal to the potential offset threshold, the grounding electrode detection flow loop is entered.

[0017] When entering the grounding electrode detection stage, the grounding electrode number in the corresponding area is locked according to the monitoring node indicated by the potential deviation index, and this number is used as a query condition to access the historical database to retrieve the grounding impedance data of the grounding electrode.

[0018] Grounding impedance refers to the equivalent AC impedance of the grounding electrode relative to the earth.

[0019] In a preferred embodiment, in step S2, the impedance fluctuation trend is obtained by calculating the impedance change rate of the grounding electrode, and the impedance change rate is the derivative of the grounding impedance.

[0020] After obtaining the impedance fluctuation trend, and in combination with the topology of the grounding grid, the grounding electrodes are divided along the discharge direction of each branch conductor according to the physical connection relationship between the grounding electrode and the adjacent node or busbar.

[0021] Each discharge direction corresponds to the path through which the grounding electrode transmits current to the surrounding soil and adjacent grounding electrodes. The discharge current in each discharge direction is obtained by calculating the voltage difference and admittance matrix between the grounding electrode node and the adjacent busbar or grounding electrode node.

[0022] In a preferred embodiment, in step S2, the maximum value of the leakage current is subtracted from the minimum value, and the difference is divided by the sum of the leakage currents of the grounding electrode along all leakage directions to obtain the leakage balance characteristic.

[0023] Based on the impedance fluctuation trend and leakage balance characteristics of the grounding electrode, the grounding electrode is marked as follows:

[0024] When the impedance fluctuation trend of the grounding electrode exceeds the preset fluctuation threshold and the leakage imbalance characteristic exceeds the preset imbalance threshold, it is determined that there is an abnormal leakage phenomenon in the grounding electrode and it is marked.

[0025] Conversely, no marking is performed.

[0026] In a preferred embodiment, in step S3, the topological branch where the marked grounding electrode is located and its electrically connected grounding body set are used as the dividing criteria to form an abnormal corrosion region.

[0027] Other topology branches that do not contain marked ground electrodes are divided into multiple partitioned regions according to the connectivity of the conduction paths.

[0028] In a preferred embodiment, in step S3, a positioning evaluation period is preset, and the magnetic field strength at multiple locations within each divided area is collected by a magnetic field sensor within the preset positioning evaluation period.

[0029] The surface magnetic field data is obtained by subtracting the maximum and minimum values ​​of the magnetic field strength within the divided area.

[0030] The surface temperature of the soil in each divided area is collected by temperature sensors, and the maximum surface temperature is taken as the surface temperature data.

[0031] In a preferred embodiment, in step S4, the average value of the surface magnetic field data of each divided region is taken as the average magnetic field value, and the ratio of the surface magnetic field data of the divided region to the average magnetic field value is taken as the magnetic field distribution characteristic of the divided region.

[0032] After standardizing the magnetic field distribution characteristics and surface temperature data respectively, magnetic field distribution coefficient and surface temperature coefficient are generated.

[0033] The discharge concentration factor is calculated by combining the magnetic field distribution coefficient and the surface temperature coefficient.

[0034] In a preferred embodiment, in step S4, the length of the conductive strip of the discharge path between the abnormal corrosion area and the divided area is obtained through the grounding grid structure database;

[0035] The discharge path data is obtained after standardizing the length of the conductive strip;

[0036] The ratio of the discharge concentration factor to the discharge path data is used as the positioning index;

[0037] If the positioning index is greater than the preset positioning index threshold, the area is determined to be a leakage positioning area;

[0038] Conversely, if the area is not defined, it is determined that the area is not a discharge positioning area.

[0039] The technical effects and advantages of this invention are as follows:

[0040] This invention collects grounding potential data from grounding grid monitoring nodes, calculates the potential deviation index, and determines whether there is an abnormal leakage current. When an abnormality is found, it accesses the historical database to retrieve the grounding impedance data of the marked grounding electrodes, analyzes the impedance fluctuation trend, and detects the leakage current in each leakage direction. Based on the leakage imbalance characteristics, the grounding electrodes are marked, and abnormal corrosion areas are divided and screened. Surface magnetic field data and surface temperature data for each divided area are obtained. The leakage concentration coefficient is calculated based on the magnetic field distribution characteristics and surface temperature coefficient. A positioning index is generated by combining leakage path data to screen leakage positioning areas. This achieves spatial identification of the extent to which corrosion causes obstruction of leakage channels and the range of detour diffusion, improving the accuracy of grounding grid corrosion positioning and the effectiveness of maintenance. Attached Figure Description

[0041] Figure 1 This is a flowchart illustrating the implementation of the substation electromagnetic interference source modeling and localization method based on multi-physics coupling according to the present invention.

[0042] Figure 2 This is a schematic diagram illustrating the steps of the substation electromagnetic interference source modeling and localization method based on multi-physics coupling according to the present invention. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] This invention collects grounding potential data from grounding grid monitoring nodes, calculates the potential deviation index, and determines whether there is an abnormal leakage current. When an abnormality is found, it accesses the historical database to retrieve the grounding impedance data of the marked grounding electrodes, analyzes the impedance fluctuation trend, and detects the leakage current in each leakage direction. Based on the leakage imbalance characteristics, the grounding electrodes are marked, and abnormal corrosion areas are delineated and screened. Surface magnetic field data and surface temperature data for each delineated area are obtained. The leakage concentration coefficient is calculated based on the magnetic field distribution characteristics and surface temperature coefficient. Combined with leakage path data, a location index is generated to screen leakage location areas, achieving spatial identification of the extent to which corrosion obstructs the leakage channel and the detour diffusion range.

[0045] Example 1, such as Figures 1 to 2 As shown, the method for modeling and locating electromagnetic interference sources in substations based on multi-physics coupling includes the following steps:

[0046] Step S1: Obtain the grounding potential data of the grounding grid in the area to be tested, analyze the potential deviation status using the grounding potential data and determine whether to detect the grounding electrode. When detecting the grounding electrode, access the historical database to retrieve the grounding impedance data of the grounding electrode.

[0047] Step S2: Analyze the impedance fluctuation trend based on the grounding impedance data, divide the leakage direction of the grounding electrode, detect the leakage current in each leakage direction and evaluate the leakage balance characteristics of the grounding electrode, and mark the grounding electrode in combination with the impedance fluctuation trend.

[0048] Step S3: Divide the grounding grid into regions according to the marked grounding electrodes and screen abnormal corrosion areas. Set the positioning evaluation cycle and detect the surface magnetic field data and surface temperature data of the divided areas within the positioning evaluation cycle.

[0049] Step S4: Analyze the surface magnetic field data to generate magnetic field distribution characteristics, combine the surface temperature data to generate the discharge concentration coefficient for the divided areas, collect discharge path data between the abnormal corrosion area and the divided areas, and filter the discharge location area by combining the discharge concentration coefficient.

[0050] The specific implementation is as follows:

[0051] In step S1, the substation grounding grid is buried underground for a long time. Under the long-term effects of rainwater infiltration, soil electrochemical reactions, and stray currents, the metal grounding electrodes gradually corrode, causing the effective contact area between the grounding electrodes and the surrounding soil to continuously decrease, and local areas gradually evolve into high-resistivity zones. After the formation of high-resistivity zones, the earth current that is uniformly discharged along the grounding electrodes is forced to bypass the grounding electrode area, thus generating abnormally diffused stray current distribution in the soil. This stray current will change the potential distribution of the grounding grid, forming a hidden but highly harmful source of electromagnetic interference, thereby affecting the stable operation of equipment within the substation.

[0052] Based on the topology and conductor layout of the substation grounding grid, several representative grounding points are selected as monitoring nodes. This involves retrieving the structural drawings and conductor layout parameters of the substation grounding grid to determine that the grounding grid consists of several longitudinal and transverse grounding busbars and their intersecting welding points. The grid intersection nodes, outgoing cable lead-down points, and grounding electrode connection points are used as monitoring nodes. Grounding potential sensors are installed at the monitoring nodes. By measuring the potential difference with a reference electrode buried far from the influence range of the grounding grid, the instantaneous grounding potential value of each monitoring node relative to the reference electrode is obtained in real time. The instantaneous grounding potential values ​​detected within the preset observation period are used as the grounding potential data of the grounding grid in the area to be tested.

[0053] It should be noted that a ground potential sensor is an electrical quantity acquisition device used to measure the potential difference between a conductor and the earth. It is used to stably acquire potential changes in the microvolt to volt range under strong electromagnetic field conditions without causing additional impact on the current distribution of the grounding grid during the measurement process. The reference electrode is a non-polarized electrode that provides a stable reference potential. By burying it far away from the current diffusion area of ​​the grounding grid, its electrochemical potential does not fluctuate significantly with changes in the environmental field, thus forming an approximately constant earth reference point for each monitoring node to perform potential difference measurement.

[0054] The grounding potential data of the monitoring nodes are aligned to a time series. For each monitoring node, its potential offset within the observation period is calculated. The potential offset is defined as the degree of deviation of the instantaneous grounding potential value of the monitoring node from the average instantaneous grounding potential of the grid. Its calculation expression is as follows:

[0055] ;

[0056] in, To monitor the potential shift of the nodes, To monitor the instantaneous grounding potential value of the node, To monitor the average instantaneous grounding potential of the node connected to the power grid, The total duration of the observation period. This is the symbol for time integral.

[0057] The maximum potential offset among all monitoring nodes is used as the potential offset index of the grounding grid, and compared with a preset potential offset threshold.

[0058] When the potential deviation index of the grounding grid is less than the potential deviation threshold, it indicates that the potential distribution of the grounding grid is uniform and there is no obvious abnormal leakage path, so it is not necessary to enter the grounding electrode detection stage.

[0059] When the potential deviation index of the grounding grid is greater than or equal to the potential deviation threshold, it is determined that there is a local high resistance area inside the grounding grid, which causes abnormal potential diffusion. Further impedance trend analysis and leakage direction detection of the grounding electrode are required, thus entering the grounding electrode detection flow stage.

[0060] It should be noted that the preset potential offset threshold is quantitatively set based on the potential distribution law of the grounding grid in a healthy state. By retrieving the grounding potential records of the substation in the historical database during the period when no corrosion or leakage abnormality occurred, the potential offset of all monitoring nodes in each historical period is calculated, and the mean of the historical potential offset plus twice the standard deviation is used as the potential offset threshold.

[0061] When entering the grounding electrode detection stage, the grounding electrode number in the corresponding area is locked according to the monitoring node indicated by the potential deviation index, and this number is used as a query condition to access the historical database to retrieve the grounding impedance data of the grounding electrode.

[0062] Grounding impedance refers to the equivalent AC impedance of a grounding electrode relative to the earth. It is calculated by injecting an AC current of known amplitude between the grounding electrode to be tested and an auxiliary electrode far from the grounding grid, while measuring the voltage drop between the grounding electrode and the reference electrode, and then using Ohm's law.

[0063] Grounding impedance reflects the resistance to the diffusion of current through the grounding electrode into the surrounding soil. The higher the value, the smaller the effective contact area between the grounding electrode and the soil. This may result in obstruction of the discharge channel due to corrosion, electrode failure, or soil dryness, thus forming abnormal current diffusion and potential sources of electromagnetic interference. The lower the value, the better the contact between the grounding electrode and the soil, the more smoothly the current can be discharged to the ground, and the grounding electrode is in normal working condition.

[0064] It should be noted that the historical database refers to a structured data system that stores long-term monitoring records of the grounding grid and each grounding electrode, storing information such as grounding impedance, measurement environment, and sampling conditions according to the grounding electrode number and acquisition time index.

[0065] In step S2, the change of grounding impedance of the grounding electrode over time is analyzed to obtain the impedance fluctuation trend. Specifically, the impedance fluctuation trend is obtained by calculating the impedance change rate of the grounding electrode, and its mathematical expression is as follows:

[0066] ;

[0067] in, The impedance fluctuation trend of the grounding electrode. The grounding impedance is the grounding electrode. The symbol for the derivative is .

[0068] Impedance fluctuation trend reflects the dynamic characteristics of the grounding resistance of the grounding electrode changing over time. When the impedance fluctuation trend shows a continuous increase or a sudden peak, it indicates that the effective contact area of ​​the grounding electrode may decrease due to corrosion, electrode damage or changes in the soil environment, thereby causing local discharge obstruction.

[0069] After obtaining the impedance fluctuation trend, and in conjunction with the topology of the grounding grid, the grounding electrodes are divided along the discharge direction of each branch conductor according to the physical connection relationship between the grounding electrode and the adjacent node or busbar.

[0070] Each discharge direction corresponds to the path through which the grounding electrode transmits current to the surrounding soil and adjacent grounding electrodes. The discharge current in each discharge direction is obtained by calculating the voltage difference and admittance matrix between the grounding electrode node and the adjacent busbar or grounding electrode node, so as to reflect the distribution of current in each discharge path.

[0071] It should be noted that the admittance matrix is ​​a mathematical representation used to describe the electrical coupling relationship between each grounding electrode node in a grounding grid. Each element represents the equivalent conductance or mutual conductance relationship between two grounding electrode nodes along the grounding conductor and soil path. The diagonal elements are the total admittance of the grounding electrode node itself, including the sum of its grounding admittance with the surrounding soil and the admittance of all directly connected branches. The off-diagonal elements are the negative mutual conductance between two grounding electrode nodes, reflecting the current distribution coupling characteristics between nodes.

[0072] When calculating the leakage current, a node voltage vector is established based on the topology of the grounding grid. The connection between the grounding electrode of each grounding electrode node and the adjacent busbar or grounding electrode node is mapped to the admittance matrix. The leakage current vector of each grounding electrode node is calculated through a linear relationship, where each element represents the total leakage current of the grounding electrode node along each connection path. Finally, based on the corresponding branch relationship between the node voltage and the admittance matrix, the leakage current in each leakage direction is extracted.

[0073] Subsequently, the leakage imbalance characteristics of the grounding electrode are calculated based on the leakage current. The leakage imbalance characteristics are the degree of non-uniformity of the current distribution in each leakage direction of the grounding electrode. The calculation method is to subtract the minimum value from the maximum value of the leakage current, and then divide the difference by the sum of the leakage current of the grounding electrode along all leakage directions to obtain the leakage imbalance characteristics.

[0074] The leakage balance characteristic is used to characterize the balance of the leakage capacity of the grounding electrode. When the value is large, it indicates that the current discharge of the grounding electrode is blocked in a certain leakage direction, and there is a local high resistance area or corrosion damage.

[0075] Based on the impedance fluctuation trend and leakage balance characteristics of the grounding electrode, the grounding electrode is marked as follows:

[0076] When the impedance fluctuation trend of the grounding electrode exceeds the preset fluctuation threshold and the leakage imbalance characteristic exceeds the preset imbalance threshold, it is determined that there is an abnormal leakage phenomenon in the grounding electrode and it is marked.

[0077] Conversely, no marking is performed.

[0078] It should be noted that the preset fluctuation threshold is determined based on the impedance stability characteristics of the grounding electrode in a healthy state. By retrieving the impedance record sequence during periods when no corrosion or leakage anomalies occurred from the historical database, the impedance fluctuation rate within each historical period is calculated, and the statistical upper limit of impedance fluctuation is constructed by adding twice the standard deviation to the mean. This statistical upper limit is used as the preset fluctuation threshold. The preset imbalance threshold is determined based on the leakage current distribution characteristics of the grounding electrode in a healthy state. By retrieving the current in each leakage direction of the same grounding electrode during periods without anomalies from the historical database, the leakage imbalance is calculated, and its mean and standard deviation are obtained. The upper limit deviation of the leakage distribution is calculated by adding twice the standard deviation to the mean, and this upper limit deviation is used as the preset imbalance threshold.

[0079] In step S3, the connection branch of the marked grounding electrode is used as the basis for division, and the topological branch where the marked grounding electrode is located and its electrically connected grounding body set are regarded as the abnormal corrosion area; other topological branches that do not contain the marked grounding electrode are divided into multiple division areas according to the connection relationship of the conduction path, and each division area independently corresponds to a direction that may undertake bypass discharge.

[0080] For example, starting with the marked ground electrode, the grounding nodes that maintain continuous electrical connection with the conductive strip are traced one by one along the connection direction of the conductive strip, and the set of grounding nodes included in the continuous conductive path is defined as an abnormal corrosion region. At the same time, the same connection tracing process is performed on other conductive strip connection directions that do not include the marked ground electrode, and the corresponding set of grounding nodes is obtained according to their respective independent continuous conductive paths. Each set of nodes is used as a division region to characterize the leakage bypass behavior that may be undertaken in that direction due to corrosion.

[0081] By obtaining the grounding grid topology table from the grounding grid structure database, the electrical connection relationship between the conductive strip and the grounding body is indexed to obtain the topology branch where the grounding electrode is located and the set of grounding bodies that are electrically connected to it.

[0082] An abnormal corrosion zone refers to a grounding grid area where the leakage path is blocked, identified by leakage direction analysis and grounding impedance fluctuation trend. The corrosion has led to a decrease in leakage diffusion capacity and caused the leakage current to diffuse around other branches.

[0083] A preset positioning evaluation period is set. Within the preset positioning evaluation period, the magnetic field strength of multiple locations in each divided area is collected by a magnetic field sensor. The difference between the maximum and minimum magnetic field strength in each divided area is used to obtain the surface magnetic field data.

[0084] At the same time, the surface temperature of the soil in each divided area is collected by temperature sensors, and the maximum surface temperature is taken as the surface temperature data.

[0085] Surface temperature data reflects the degree of concentration of leakage current near the surface; the larger the surface temperature data, the more leakage current the area receives and the more the leakage current is concentrated in that direction; the smaller the surface temperature data, the less the leakage current is concentrated or the leakage behavior is normally and evenly distributed in the area.

[0086] It should be noted that the preset positioning evaluation cycle can be set according to the fluctuation characteristics of the grounding grid's operating status, the rate of change of the discharge current, and the on-site environmental conditions; a magnetic field sensor is a magnetic field measuring device used to detect the magnetic field strength of the Earth's surface space; a temperature sensor is a temperature measuring device used to detect the surface temperature of the grounding grid area.

[0087] By dividing the area into regions centered on the marked grounding electrode and following the discharge path, and collecting the difference in the surface magnetic field and the peak surface temperature of each region within a preset positioning and evaluation period, the abnormal corrosion area can be distinguished from other discharge directions. This provides a data basis for subsequent discharge concentration factor calculation and discharge positioning, and improves the accuracy of identification and positioning effectiveness of the impact range of corrosion on the discharge path.

[0088] In step S4, the average value of the surface magnetic field data of each divided region is taken as the average magnetic field value, and the ratio of the surface magnetic field data to the average magnetic field value is taken as the magnetic field distribution characteristics of the divided region.

[0089] The magnetic field distribution characteristics reflect the degree of deviation of the variation of the surface magnetic field in the divided area from the overall leakage state. The larger the magnetic field distribution characteristics, the more obvious the concentration or bypass behavior of the leakage current in that direction. The smaller the magnetic field distribution characteristics, the closer the variation of the surface magnetic field in the divided area is to the overall average state, and the leakage current does not show obvious concentration in that direction or the leakage behavior is relatively uniformly distributed.

[0090] After standardizing the magnetic field distribution characteristics and surface temperature data respectively, magnetic field distribution coefficient and surface temperature coefficient are generated.

[0091] Calculate the discharge concentration factor by combining the magnetic field distribution coefficient and the surface temperature coefficient: ,in, and To preset the adjustment weight, The magnetic field distribution coefficient, Here, e is the surface temperature coefficient, and e is the natural constant. The discharge concentration factor;

[0092] The discharge concentration factor is used to reflect the degree of shift and concentration of the discharge current in that direction after corrosion obstructs the main discharge path. The larger the discharge concentration factor, the more bypass discharge current is carried in that direction, and the more significant the impact of corrosion on the grounding electrode.

[0093] The conductive strip length of the discharge path between the abnormal corrosion area and the division area is obtained by the grounding grid structure database. The conductive strip length refers to the geometric length of the continuous conductive path formed along the conductive strip of the grounding grid between the abnormal corrosion area and the division area. The shorter the conductive strip length, the easier it is for the discharge current to diffuse around in this direction after the main discharge channel is blocked by the abnormal corrosion area.

[0094] The discharge path data is obtained after standardizing the length of the conductive strip;

[0095] The ratio of the discharge concentration factor to the discharge path data is used as the positioning index;

[0096] The larger the positioning index, the stronger the original discharge capacity in that direction and the more obvious the current obstruction. The discharge current tends to concentrate in that direction, which is the area affected by corrosion. The smaller the positioning index, the weaker the original discharge capacity or the absence of significant obstruction. That direction is not the area affected by corrosion.

[0097] The location index is compared with a preset location index threshold to filter out the leakage location area:

[0098] If the positioning index is greater than the preset positioning index threshold, the area is determined to be a leakage positioning area;

[0099] Conversely, if the area is not defined, it is determined that the area is not a discharge location area;

[0100] The larger the positioning index, the more concentrated the leakage current in that direction is compared to the normal distribution, and the greater the impact of corrosion on the grounding electrode, indicating a leakage positioning area; the smaller the positioning index, the more normal the leakage behavior in that direction is, with no obvious current concentration, and it does not belong to the leakage positioning area.

[0101] The discharge location area refers to the area where the discharge current detours and shows an abnormally concentrated distribution after the original discharge path is blocked due to abnormal corrosion. It reflects the range of the impact of corrosion on the discharge characteristics of the grounding grid.

[0102] By integrating the magnetic field distribution characteristics and surface temperature data of each divided area, a discharge concentration coefficient is generated. Combined with the conductive strip length of the discharge path between the abnormal corrosion area and the divided area, a positioning index is formed to determine the discharge positioning area. This realizes the spatial positioning of the range of discharge path obstruction caused by abnormal corrosion, and provides a basis for accurate detection of hidden corrosion of the grounding grid and maintenance of the target area.

[0103] It should be noted that the standardization methods include, but are not limited to, standard linear transformation based on interval scaling, Z-Score standardization based on statistics, or normalization based on nonlinear mapping functions. The application methods of standardization will not be elaborated here. The preset adjustment weight can be set according to the contribution ratio of the changes in magnetic field distribution characteristics and surface temperature changes in historical data to the discharge obstruction index. The grounding grid structure database is an engineering archive database used to store grounding grid layout structure data, including conductive strip laying routes, etc. The preset positioning index threshold can be set according to the statistical results of historical operation data or the accuracy required by actual needs.

[0104] Finally, it should be noted that in this paper, relational terms such as first and second are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0105] Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0106] In this document, the singular forms “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that terms such as “comprising / including” or “having” specify the presence of the stated features, integrals, steps, operations, components, parts, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, integrals, steps, operations, components, parts, or combinations thereof. Meanwhile, the term “and / or” as used in this specification includes any and all combinations of the associated listed items.

[0107] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The various embodiments can be combined as needed, and the same or similar parts can be referred to each other.

[0108] The above description of the disclosed embodiments will enable those skilled in the art to make or use various modifications to these embodiments. It will be readily apparent to those skilled in the art that the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for modeling and locating electromagnetic interference sources in substations based on multi-physics coupling, characterized in that: Includes the following steps: Step S1: Obtain the grounding potential data of the grounding grid in the area to be tested, analyze the potential deviation status using the grounding potential data and determine whether to detect the grounding electrode. When detecting the grounding electrode, access the historical database to retrieve the grounding impedance data of the grounding electrode. Step S2: Analyze the impedance fluctuation trend based on the grounding impedance data, divide the leakage direction of the grounding electrode, detect the leakage current in each leakage direction and evaluate the leakage balance characteristics of the grounding electrode, and mark the grounding electrode in combination with the impedance fluctuation trend. Step S3: Divide the grounding grid into regions according to the marked grounding electrodes and screen abnormal corrosion areas. Set the positioning evaluation cycle and detect the surface magnetic field data and surface temperature data of the divided areas within the positioning evaluation cycle. Step S4: Analyze the surface magnetic field data to generate magnetic field distribution characteristics, combine the surface temperature data to generate the discharge concentration coefficient for the divided areas, collect discharge path data between the abnormal corrosion area and the divided areas, and filter the discharge location area by combining the discharge concentration coefficient. In step S4, the average value of the surface magnetic field data of each divided region is taken as the average magnetic field value, and the ratio of the surface magnetic field data of the divided region to the average magnetic field value is taken as the magnetic field distribution characteristics of the divided region. After standardizing the magnetic field distribution characteristics and surface temperature data respectively, magnetic field distribution coefficient and surface temperature coefficient are generated. Calculate the discharge concentration factor by combining the magnetic field distribution coefficient and the surface temperature coefficient: ,in, and To preset the adjustment weight, The magnetic field distribution coefficient, Here, e is the surface temperature coefficient, and e is the natural constant. This is the discharge concentration factor.

2. The method for modeling and locating electromagnetic interference sources in substations based on multiphysics coupling according to claim 1, characterized in that: In step S1, based on the topology of the substation grounding network and the conductor layout, several representative grounding points are selected as monitoring nodes. Ground potential sensors are installed at monitoring nodes, and the instantaneous ground potential value of each monitoring node relative to the reference electrode is obtained in real time by measuring the potential difference compared with the reference electrode buried far away from the influence range of the grounding grid. The instantaneous grounding potential value detected within the preset observation period will be used as the grounding potential data of the grounding grid in the area to be tested; The grounding potential data of the monitoring nodes are aligned with the time series, and the potential offset of each monitoring node within the observation period is calculated. Potential offset is defined as the degree of deviation of the instantaneous grounding potential value of a monitoring node from the average instantaneous grounding potential of the grid.

3. The method for modeling and locating electromagnetic interference sources in substations based on multiphysics coupling according to claim 2, characterized in that: In step S1, the maximum value of the potential offset in all monitoring nodes is taken as the potential offset index of the grounding grid. When the potential offset index of the grounding grid is greater than or equal to the potential offset threshold, the grounding electrode detection current loop is entered. When entering the grounding electrode detection stage, the grounding electrode number in the corresponding area is locked according to the monitoring node indicated by the potential deviation index, and this number is used as a query condition to access the historical database to retrieve the grounding impedance data of the grounding electrode. Grounding impedance refers to the equivalent AC impedance of the grounding electrode relative to the earth.

4. The method for modeling and locating electromagnetic interference sources in substations based on multiphysics coupling according to claim 1, characterized in that: In step S2, the impedance fluctuation trend is obtained by calculating the impedance change rate of the grounding electrode, and the impedance change rate is the derivative of the grounding impedance. After obtaining the impedance fluctuation trend, and in combination with the topology of the grounding grid, the grounding electrodes are divided along the discharge direction of each branch conductor according to the physical connection relationship between the grounding electrode and the adjacent node or busbar. Each discharge direction corresponds to the path through which the grounding electrode transmits current to the surrounding soil and adjacent grounding electrodes. The discharge current in each discharge direction is obtained by calculating the voltage difference and admittance matrix between the grounding electrode node and the adjacent busbar or grounding electrode node.

5. The method for modeling and locating electromagnetic interference sources in substations based on multiphysics coupling according to claim 4, characterized in that: In step S2, the maximum value of the leakage current is subtracted from the minimum value, and the difference is divided by the sum of the leakage current along all leakage directions of the grounding electrode to obtain the leakage balance characteristic. Based on the impedance fluctuation trend and leakage balance characteristics of the grounding electrode, the grounding electrode is marked as follows: When the impedance fluctuation trend of the grounding electrode exceeds the preset fluctuation threshold and the leakage imbalance characteristic exceeds the preset imbalance threshold, it is determined that there is an abnormal leakage phenomenon in the grounding electrode and it is marked. Conversely, no marking is performed.

6. The method for modeling and locating electromagnetic interference sources in substations based on multiphysics coupling according to claim 1, characterized in that: In step S3, the topological branch where the marked grounding electrode is located and its electrically connected grounding body set are used as the dividing criteria to form an abnormal corrosion region. Other topology branches that do not contain marked ground electrodes are divided into multiple partitioned regions according to the connectivity of the conduction paths.

7. The method for modeling and locating electromagnetic interference sources in substations based on multiphysics coupling according to claim 6, characterized in that: In step S3, a preset positioning evaluation period is set, and the magnetic field strength at multiple locations within each divided area is collected by a magnetic field sensor within the preset positioning evaluation period. The surface magnetic field data is obtained by subtracting the maximum and minimum values ​​of the magnetic field strength within the divided area. The surface temperature of the soil in each divided area is collected by temperature sensors, and the maximum surface temperature is taken as the surface temperature data.

8. The method for modeling and locating electromagnetic interference sources in substations based on multiphysics coupling according to claim 1, characterized in that: In step S4, the length of the conductive strip of the discharge path between the abnormal corrosion area and the divided area is obtained through the grounding grid structure database; The discharge path data is obtained after standardizing the length of the conductive strip; The ratio of the discharge concentration factor to the discharge path data is used as the positioning index; If the positioning index is greater than the preset positioning index threshold, the area is determined to be a leakage positioning area; Conversely, if the area is not defined, it is determined that the area is not a discharge positioning area.

Images