Transient electromagnetic interference voltage determination method and device, equipment and medium

Abstract

The invention relates to a transient electromagnetic interference voltage determination method and device, equipment and a medium, and the method comprises the steps: building a field-circuit cooperation model based on a video monitoring system and the parameter information of a cable connected with the video monitoring system; based on the field-circuit cooperation model, obtaining a first interference voltage coupled to a video monitoring system port by space radiation; constructing a multi-conductor transmission line system model based on the transformer substation earth screen and shielding cable simulation model; based on the multi-conductor transmission line system model, acquiring a second interference voltage of the line which is conductively coupled to the video monitoring system port; and superposing the first interference voltage and the second interference voltage to obtain the transient electromagnetic interference voltage of the video monitoring system port. By adopting the method, the problem that the transient electromagnetic interference voltage cannot be accurately determined in the prior art can be solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electromagnetic compatibility, and particularly relates to a transient electromagnetic interference voltage determination method, device, equipment and medium. BACKGROUND

[0002] With the rapid development of smart substations, video monitoring systems as key infrastructures have been widely applied to substation equipment state monitoring and real-time alarm. However, under the action of transient electromagnetic disturbance such as lightning, operating overvoltage or short-circuit grounding, the video monitoring system often appears the situation of device offline, downtime or even hardware damage due to electromagnetic compatibility problems, which seriously affects the safe operation of the substation.

[0003] However, the related art cannot accurately determine the transient electromagnetic interference voltage. SUMMARY

[0004] Therefore, it is necessary to provide a transient electromagnetic interference voltage determination method, device, computer equipment, computer readable storage medium and computer program product aiming at the above technical problems.

[0005] In a first aspect, the present application provides a transient electromagnetic interference voltage determination method, which comprises:

[0006] constructing a field-circuit coordination model based on parameter information of a video monitoring system and a cable connected with the video monitoring system;

[0007] obtaining a first interference voltage of spatial radiation coupling to a port of the video monitoring system based on the field-circuit coordination model;

[0008] constructing a multi-conductor transmission line system model based on a substation ground net and a shielding cable simulation model;

[0009] obtaining a second interference voltage of line conduction coupling to the port of the video monitoring system based on the multi-conductor transmission line system model;

[0010] superimposing the first interference voltage and the second interference voltage to obtain a transient electromagnetic interference voltage of the port of the video monitoring system.

[0011] In one of the embodiments, the field-circuit coordination model is constructed based on the parameter information of the video monitoring system and the cable connected with the video monitoring system, comprising:

[0012] constructing a three-dimensional full-parameter model and an equivalent circuit model of the video monitoring system;

[0013] establishing a simulation environment simulating transient electromagnetic radiation electric field based on the three-dimensional full-parameter model, and combining the equivalent circuit model with the simulation environment to construct the field-circuit coordination model.

[0014] In one of the embodiments, based on the field-circuit collaborative model, the first interference voltage coupled from the space radiation to the port of the video monitoring system is obtained, comprising:

[0015] Based on the field-circuit collaborative model, the distribution parameters of the transient electromagnetic radiation electric field induced on the cable are calculated; the distribution parameters include the distribution current and / or the distribution voltage;

[0016] The distribution current and / or the distribution voltage are injected into the equivalent circuit model as an excitation source, and the first interference voltage is obtained through the virtual voltage probe arranged at the port of the equivalent circuit model.

[0017] In one of the embodiments, based on the substation grounding grid and the shielding cable simulation model, a multi-conductor transmission line system model is constructed, comprising:

[0018] Based on the soil layering structure data and the grounding grid topology data of the location where the video monitoring system is located, a grounding grid frequency domain impedance matrix model is established by the method of moments;

[0019] Based on the laying path, the shielding layer structure and the grounding mode of the secondary cable, a unit excitation current at different preset frequencies is injected at the preset fault point position of the substation grounding grid, and the current distribution of the secondary cable shielding layer is solved;

[0020] Based on the shielding layer structure parameters of the secondary cable, the transfer impedance of the secondary cable at the preset frequency is calculated;

[0021] Based on the current distribution of the secondary cable shielding layer and the transfer impedance, a multi-conductor transmission line system model is constructed.

[0022] In one of the embodiments, based on the multi-conductor transmission line system model, the second interference voltage coupled from the line conduction to the port of the video monitoring system is obtained, comprising:

[0023] Based on the current distribution of the secondary cable shielding layer and the transfer impedance, the distribution excitation source acting on the multi-conductor transmission line system model is determined;

[0024] The distribution excitation source is injected into the multi-conductor transmission line system model, and the preset transmission line equation is solved to obtain the second interference voltage.

[0025] In one of the embodiments, based on the shielding layer structure parameters of the secondary cable, the transfer impedance of the secondary cable at the preset frequency is calculated, comprising:

[0026] Based on the shielding layer structure parameters of the secondary cable, the initial transfer impedance of the secondary cable at the preset frequency is calculated;

[0027] According to the preset dielectric constant gradient factor, the initial transfer impedance is corrected to obtain the transfer impedance of the secondary cable at the preset frequency.

[0028] In one embodiment, after the second interference voltage coupled to the port of the video monitoring system by line conduction is acquired, the method further comprises:

[0029] According to the ratio of the second interference voltage and the first interference voltage, the electromagnetic interference influence weight of the transient electromagnetic radiation electric field and the electromagnetic interference influence weight of the line conduction are determined;

[0030] The electromagnetic interference influence weight of the transient electromagnetic radiation electric field and the electromagnetic interference influence weight of the line conduction are compared to obtain a comparison result;

[0031] Based on the comparison result, the main interference path of the video monitoring system is determined.

[0032] In a second aspect, the application further provides a transient electromagnetic interference voltage determination device, which comprises:

[0033] A field-circuit collaborative model construction module is configured to construct a field-circuit collaborative model based on parameter information of a video monitoring system and a cable connected to the video monitoring system;

[0034] A first interference voltage determination module is configured to acquire a first interference voltage coupled to a port of the video monitoring system by spatial radiation based on the field-circuit collaborative model;

[0035] A multi-conductor transmission line system model construction module is configured to construct a multi-conductor transmission line system model based on a substation ground net and a shielding cable simulation model;

[0036] A second interference voltage determination module is configured to acquire a second interference voltage coupled to the port of the video monitoring system by line conduction based on the multi-conductor transmission line system model;

[0037] A transient electromagnetic interference voltage determination module is configured to perform superposition processing on the first interference voltage and the second interference voltage to obtain a transient electromagnetic interference voltage of the port of the video monitoring system.

[0038] In a third aspect, the application further provides a computer device, which comprises a memory and a processor, the memory stores a computer program, and the processor implements the following steps when executing the computer program:

[0039] A field-circuit collaborative model is constructed based on parameter information of a video monitoring system and a cable connected to the video monitoring system;

[0040] A first interference voltage coupled to a port of the video monitoring system by spatial radiation is acquired based on the field-circuit collaborative model;

[0041] A multi-conductor transmission line system model is constructed based on a substation ground net and a shielding cable simulation model;

[0042] acquire, based on the multi-conductor transmission line system model, a second interference voltage coupled to the port of the video monitoring system by line conduction;

[0043] superimpose the first interference voltage and the second interference voltage to obtain a transient electromagnetic interference voltage of the port of the video monitoring system.

[0044] In a fourth aspect, the present application further provides a computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to implement the following steps:

[0045] construct a field-circuit coordination model based on parameter information of the video monitoring system and a cable connected to the video monitoring system;

[0046] acquire, based on the field-circuit coordination model, a first interference voltage coupled to the port of the video monitoring system by space radiation;

[0047] construct a multi-conductor transmission line system model based on a substation ground grid and a shielding cable simulation model;

[0048] acquire, based on the multi-conductor transmission line system model, a second interference voltage coupled to the port of the video monitoring system by line conduction;

[0049] superimpose the first interference voltage and the second interference voltage to obtain a transient electromagnetic interference voltage of the port of the video monitoring system.

[0050] In a fifth aspect, the present application further provides a computer program product, which comprises a computer program, and the computer program is executed by a processor to implement the following steps:

[0051] construct a field-circuit coordination model based on parameter information of the video monitoring system and a cable connected to the video monitoring system;

[0052] acquire, based on the field-circuit coordination model, a first interference voltage coupled to the port of the video monitoring system by space radiation;

[0053] construct a multi-conductor transmission line system model based on a substation ground grid and a shielding cable simulation model;

[0054] acquire, based on the multi-conductor transmission line system model, a second interference voltage coupled to the port of the video monitoring system by line conduction;

[0055] superimpose the first interference voltage and the second interference voltage to obtain a transient electromagnetic interference voltage of the port of the video monitoring system.

[0056] The transient electromagnetic interference voltage determination method, device, computer device, storage medium and computer program product provided by the application first construct a field-circuit collaborative model based on the parameter information of the video monitoring system and the cable connected with the video monitoring system; then obtain a first interference voltage coupled to the port of the video monitoring system based on the field-circuit collaborative model; then construct a multi-conductor transmission line system model based on a substation ground net and a shielding cable simulation model; then obtain a second interference voltage coupled to the port of the video monitoring system based on the multi-conductor transmission line system model; and then perform superposition processing on the first interference voltage and the second interference voltage to obtain the transient electromagnetic interference voltage of the port of the video monitoring system. By constructing the field-circuit collaborative model and the multi-conductor transmission line system model, the interference voltages coupled to the port of the video monitoring system by space radiation coupling and line conduction coupling are calculated respectively, and then superposition processing is performed to obtain the transient electromagnetic interference voltage. The method comprehensively calculates the radiation and conduction double-path full-band disturbance characteristics for the first time, solves the problem of mutual influence of ground potential rise and shielding layer current, realizes accurate quantization of the interference voltage and current response of the device port and comprehensive analysis of the transient electromagnetic disturbance coupling path, significantly improves the calculation accuracy, provides high-precision quantization basis for electromagnetic protection design of the smart substation, and solves the problem that the prior art cannot accurately determine the transient electromagnetic interference voltage. BRIEF DESCRIPTION OF DRAWINGS

[0057] Figure 1 A schematic diagram of a substation video monitoring system data acquisition gateway far-field coupling model is provided for some embodiments of the application;

[0058] Figure 2 A schematic diagram of a substation monitoring system transient electromagnetic disturbance coupling path is provided for some embodiments of the application;

[0059] Figure 3 A flowchart of a transient electromagnetic interference voltage determination method is provided for some embodiments of the application;

[0060] Figure 4 A flowchart of constructing a field-circuit collaborative model is provided for some embodiments of the application;

[0061] Figure 5 A flowchart of obtaining a first interference voltage is provided for some embodiments of the application;

[0062] Figure 6 A flowchart of constructing a multi-conductor transmission line system model is provided for some embodiments of the application;

[0063] Figure 7 A flowchart of obtaining a second interference voltage is provided for some embodiments of the application;

[0064] Figure 8 A flowchart of obtaining a transfer impedance is provided for some embodiments of the application;

[0065] Figure 9 A flow chart for determining the main interference path of a video monitoring system is provided for some embodiments of the present application;

[0066] Figure 10 A flow chart for a method for calculating the transient electromagnetic disturbance coupling characteristic of a substation video monitoring system is provided for a detailed embodiment of the present application;

[0067] Figure 11 A simulation schematic diagram for the coupling voltage of each cable port of a data acquisition gateway in a far field of a radiated electric field is provided for a detailed embodiment of the present application;

[0068] Figure 12 A structural schematic diagram of a 500 kV substation ground net model is provided for a detailed embodiment of the present application;

[0069] Figure 13 A simulation schematic diagram for the shielding layer current and core line coupling voltage of a substation secondary cable is provided;

[0070] Figure 14 A structural block diagram of a transient electromagnetic interference voltage determination device is provided for some embodiments of the present application;

[0071] Figure 15 An internal structure diagram of a computer device is provided for some embodiments of the present application. DETAILED DESCRIPTION

[0072] In order to make the objectives, technical solutions and advantages of the present application clearer, further detailed descriptions will be given to the present application in combination with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, and are not used to limit the present application.

[0073] The transient electromagnetic interference voltage determination method provided by the embodiments of the present application can be applied in an application environment as shown in Figure 1 and Figure 2 , i.e. in the electromagnetic environment of a substation, Figure 1 , a model of a video monitoring system (such as a data acquisition gateway) under far field radiation coupling is shown, Figure 2 is a coupling path diagram of the whole system, and the core feature of the electromagnetic environment of the substation is that the video monitoring system is simultaneously exposed to two main transient electromagnetic interference coupling paths. Specifically, as shown in Figure 1 , the video monitoring system and various types of cables (power lines, network cables, coaxial cables) connected thereto as a whole are exposed to a spatial radiation electromagnetic field generated by lightning strikes, switch operations and other transient events, and the electromagnetic field directly acts on the device and the cable in the form of a plane wave, etc., like an antenna, inducing interference, i.e. the first interference voltage of the spatial radiation coupling to the port of the video monitoring system. As shown in Figure 6As shown, when a transient event (such as a lightning strike) occurs, a huge transient current will be injected into the substation grounding grid, causing the ground potential to rise. The rising ground potential will generate a strong conductive current through the shield layer of the two-terminal grounded secondary cable, and this current will be coupled to the internal core wire through the transfer impedance of the cable, forming a conductive interference, that is, a second interference voltage coupled to the video monitoring system port through line conduction.

[0074] In order to accurately quantify the multi-path coupling interference, that is, the first interference voltage coupled to the video monitoring system port through spatial radiation and the second interference voltage coupled to the video monitoring system port through line conduction, the transient electromagnetic interference voltage determination method of the present application first constructs a field-circuit collaborative model based on the parameter information of the video monitoring system and the cable connected to the video monitoring system. Then, based on the field-circuit collaborative model, the first interference voltage coupled to the video monitoring system port through spatial radiation is obtained. Then, based on the substation grounding grid and the shielding cable simulation model, a multi-conductor transmission line system model is constructed. Then, based on the multi-conductor transmission line system model, the second interference voltage coupled to the video monitoring system port through line conduction is obtained. Then, the first interference voltage and the second interference voltage are superimposed to obtain the transient electromagnetic interference voltage of the video monitoring system port. In this way, the problem that the prior art cannot accurately determine the transient electromagnetic interference voltage can be solved. The transient electromagnetic interference voltage determination method of the present application can be loaded in a terminal device, including but not limited to a personal computer, a notebook computer, etc.

[0075] In one embodiment, as shown in Figure 3 The method is applied to the terminal device described above. In this embodiment, the method includes the following steps:

[0076] Step 302, based on the parameter information of the video monitoring system and the cable connected to the video monitoring system, a field-circuit collaborative model is constructed.

[0077] The video monitoring system is a key infrastructure for device state monitoring and real-time alarm in a substation. Under the action of transient electromagnetic disturbance such as lightning strike, operating overvoltage or short-circuit grounding, the video monitoring system is prone to electromagnetic compatibility problems such as device offline, downtime and even hardware damage, affecting the safe operation of the substation. The parameter information of the cable connected to the video monitoring system includes cable layout topology information such as the direction and spacing of power lines and signal lines, and information such as the characteristic impedance of coaxial cables and data transmission network cables. It also involves surrounding environmental information related to the cable, such as the structural parameters of the metal shell of the intelligent video monitoring device (length, width, height, aperture position and aperture diameter), and the characteristics of the surrounding electromagnetic environment (distance from adjacent high-voltage equipment, cable trench material).

[0078] The field-circuit collaborative model is a model constructed after an equivalent circuit model of the video monitoring system is generated based on a transmission line theory in combination with an electromagnetic coupling model of the video monitoring system. The field-circuit collaborative model can realize accurate quantification of port interference voltage and current response of the video monitoring system and comprehensive analysis of a transient electromagnetic disturbance coupling path, thereby providing a basis for subsequent calculation of a first interference voltage of spatial radiation coupling to a port of the video monitoring system.

[0079] Optionally, the field-circuit collaborative model can be constructed in a manner of combining finite element analysis software, circuit-field joint simulation, and empirical formula and numerical calculation. In this embodiment, the construction of the field-circuit collaborative model is taken as an example. In the construction of the field-circuit collaborative model, first, physical structure parameters of the video monitoring system are acquired, such as shapes, sizes, and materials (electromagnetic characteristic parameters such as conductivity of a metal shell) of a camera shell, layout and component distribution of an internal circuit board, and the like. For connected cables, parameters such as types (such as coaxial cables, network cables, and the like), lengths, cross-sectional areas, cable spacings, insulating layer materials, and thicknesses are recorded. Then, the collected parameters are sorted and digitized and converted into an input format recognizable by the finite element analysis software. Then, a modeling function of the finite element analysis software is used to construct a three-dimensional geometric model of the video monitoring system and the connected cables according to the preprocessed data. The model should accurately reflect the actual physical structure of the video monitoring system and the cables, including the shape of the camera, the number of layers and shape of the internal circuit board, the bending and orientation of the cables, and the like. Then, corresponding material properties are defined for each part of the model in the finite element software. For the metal shell of the video monitoring system, electromagnetic parameters such as conductivity and magnetic permeability are set. For the insulating layer of the cable, parameters such as relative permittivity and loss tangent are set. For components on the circuit board, equivalent representations can be made in the model according to their types (such as resistors, capacitors, inductors, and the like) and parameters. The constructed geometric model is meshed and discretized into a finite number of small units. The density of the mesh should be reasonably adjusted according to the different parts of the model and the changes in electromagnetic characteristics. For example, in regions with strong electromagnetic coupling (such as cable joints and the vicinity of the camera antenna), denser meshes should be used to improve the calculation accuracy. In regions with smaller changes in electromagnetic characteristics, sparser meshes can be used to reduce the amount of calculation. Then, reasonable boundary conditions are set for the model according to the actual electromagnetic environment. For example, an absorbing boundary condition is set on the outer boundary of the model to simulate an infinite free space. For the grounded part, a zero potential boundary condition is set. Then, the solver of the finite element software is used to solve the model to obtain electromagnetic field distribution, current distribution, and voltage response of the video monitoring system and the connected cables under transient electromagnetic disturbance. Finally, the solving results are compared with actual measurement data or existing theoretical analysis results to verify the accuracy of the model. If there is a large deviation, the model needs to be adjusted and optimized, such as re-meshing, adjusting material properties or boundary conditions, and the like.

[0080] In step 304, a first interference voltage of spatial radiation coupled to a port of the video monitoring system is obtained based on the field-circuit cooperation model.

[0081] The first interference voltage is an interference voltage coupled to the port of the video monitoring system by spatial radiation coupling under the action of a transient electromagnetic radiation electric field.

[0082] Optionally, the first interference voltage can be obtained based on a time-domain integral equation method. Specifically, the geometric structure of the video monitoring system and the connecting cable is discretized, and the metal surface is represented by a triangular or quadrilateral mesh, and the cable is represented by a line segment. Then, a time-domain integral equation is established according to the Maxwell equations, and the excitation of a spatial radiation source (such as lightning or electromagnetic pulse generated by switch operation) is considered. Then, the time-domain integral equation is solved by using a time-stepping algorithm (MOT) to obtain the current distribution on the surface of the system. Finally, the first interference voltage of the port of the video monitoring system is calculated based on the current distribution on the surface of the system and the transmission line theory.

[0083] In addition, the first interference voltage can also be obtained based on a method combining ray tracing and equivalent circuit. Specifically, the position and radiation characteristics of the spatial radiation source are determined, and the propagation path of the ray in space and the field intensity distribution reaching the system are calculated by using a ray tracing algorithm (such as geometric optics GO, uniform theory of diffraction UTD, etc.). Then, the video monitoring system and the connecting cable are modeled as an equivalent circuit including resistors, inductors, capacitors and other elements. Then, according to the field intensity distribution obtained by ray tracing, corresponding excitation sources are added to the equivalent circuit to simulate the effect of the radiation field on the system. Finally, the equivalent circuit is solved by using circuit analysis software to obtain the first interference voltage of the port of the system.

[0084] In step 306, a multi-conductor transmission line system model is constructed based on a simulation model of the substation ground grid and the shielding cable.

[0085] The substation ground grid is a main ground grid in the substation. For example, the main ground grid of a 500kV substation is a rectangular ground grid with a size of 312m in length and 270m in width, a total area of about 84240m², and a main artificial ground grid laid with φ22 galvanized round steel, with a deep burial of 0.8m in the station and a deep burial of 1.2m at the outer edge of the station. The equalizing belt of the ground grid is arranged with unequal spacing, the outer edge of the horizontal ground body is laid into a closed ring, and a grounding deep well is provided in the station. The substation ground grid provides a grounding path for electrical equipment in the substation, and when transient electromagnetic disturbance occurs, the current is introduced into the ground to reduce the influence of ground potential rise on the equipment.

[0086] The shielding cable simulation model is a model established by numerical calculation of the moment method based on the actual layered structure of the substation soil (including the surface soil resistivity, deep rock conductivity and underground water level parameters) and the grounding grid topology data. In the analysis of conductive coupling, the radial segmentation number of the cable shielding layer is not less than 8 layers, and the axial resolution is controlled within 0.05m. The shielding cable simulation model is used to analyze the influence of ground potential conduction on the cable, and provides a basis for subsequent calculation of the second interference voltage of the line conductive coupling to the video monitoring system port.

[0087] The multi-conductor transmission line system model is a model constructed based on the shielding layer segmented current distribution calculation results, and the core line current response and port conductive interference voltage characteristics are solved by the transmission line equation. The multi-conductor transmission line system model is used to quantify the line conductive interference voltage of the video monitoring system port.

[0088] Optionally, the multi-conductor transmission line system model can be constructed based on the transmission line matrix method. Specifically, first, the geometric model of the substation grounding grid and the shielding cable is established and discretized into transmission line matrix units, and the characteristic impedance and propagation constant of each unit are determined; then, according to the actual connection situation, the connection relationship between each transmission line unit is determined to form a complete multi-conductor transmission line system model; then, the boundary conditions of the model are set, such as the grounding boundary of the grounding grid and the port boundary of the cable; finally, the accuracy of the model is verified by comparing with the results of actual measurement data or other mature models, and if necessary, the model parameters are adjusted to improve the accuracy of the model.

[0089] In addition, the multi-conductor transmission line system model can also be constructed based on the combination of the finite difference frequency domain method (FDFD) and the circuit model. Specifically, first, a two-dimensional or three-dimensional geometric model of the substation grounding grid and the shielding cable is established, and the electromagnetic field distribution in the frequency domain is calculated by the finite difference frequency domain method; then, the shielding cable is modeled as a multi-conductor transmission line circuit model, considering the parameters such as resistance, inductance, capacitance and conductance of the cable; then, according to the electromagnetic field distribution calculated by FDFD, the excitation source received by the cable core is determined and coupled into the circuit model of the cable; finally, the circuit models of multiple cables and the equivalent circuit model of the grounding grid are connected to construct a complete multi-conductor transmission line system model.

[0090] In step 308, based on the multi-conductor transmission line system model, the second interference voltage of the line conductive coupling to the video monitoring system port is obtained.

[0091] The second interference voltage is the interference voltage conducted to the video monitoring system port through the ground potential when the transient electromagnetic disturbance occurs.

[0092] Optionally, the second interference voltage can be obtained based on the state variable method. Specifically, first, the state equations of the system are established according to the multi-conductor transmission line system model. The state variables can be selected as the current and voltage of the cable cores; then, the initial conditions of the system are determined, such as the current and voltage values ​​at the initial moment; then, the state equations are solved using numerical integration methods (such as the Runge-Kutta method) to obtain the state variable values ​​of the system at different moments; finally, the second interference voltage of the video surveillance system port is calculated based on the values ​​of the state variables.

[0093] In addition, the second interference voltage can be obtained by combining the method of characteristics with convolution integral. Specifically, the transmission line equation of the multi-conductor transmission line system can be solved first using the method of characteristics to obtain the forward and reverse traveling waves on the transmission line; then, the reflection and scattering effects of discontinuities on the line (such as cable joints, branch points, etc.) can be considered, and the reflected and scattered waves can be calculated by convolution integral; finally, the forward traveling wave, the reverse traveling wave, and the reflected and scattered waves are synthesized at the port of the video surveillance system to obtain the second interference voltage of the port.

[0094] Step 310: The first interference voltage and the second interference voltage are superimposed to obtain the transient electromagnetic interference voltage of the video surveillance system port.

[0095] Among them, the transient electromagnetic interference voltage is the interference voltage of the video surveillance system port obtained by superimposing the first interference voltage and the second interference voltage, taking into account the coupling effect of both spatial radiation and line conduction paths.

[0096] Optionally, the two voltage waveforms can be algebraically added in the time domain to obtain the transient electromagnetic interference voltage.

[0097] The aforementioned method for determining transient electromagnetic interference (EMI) voltage constructs a field-circuit cooperative model and a multi-conductor transmission line system model to calculate the interference voltages from spatial radiation coupling and line conduction coupling to the video surveillance system ports, respectively. These are then superimposed to obtain the transient EMI voltage. This method is the first to comprehensively calculate the full-band interference characteristics of both radiated and conducted paths, overcoming the challenge of the interaction between ground potential rise and shielding current. It achieves accurate quantification of the interference voltage and current response at equipment ports and a comprehensive analysis of transient EMI coupling paths, significantly improving calculation accuracy. This provides a high-precision quantitative basis for electromagnetic protection design in smart substations and solves the problem of existing technologies being unable to accurately determine transient EMI voltage.

[0098] In one embodiment, such as Figure 4 As shown, based on the parameter information of the video surveillance system and the cables connected to it, a field-road cooperative model is constructed, including:

[0099] Step 402: Construct a three-dimensional fully parameterized model and an equivalent circuit model of the video surveillance system.

[0100] wherein the three-dimensional full-parameterized model is an accurate three-dimensional geometric representation of the video monitoring system and its connecting cables, which can accurately describe the physical structure of the video monitoring system, including detailed size, shape, position and material properties of each component in the system and other parameter information. For example, the size of the camera, the focal length and aperture of the lens, the length, diameter and material of the cable are all defined in the form of parameters in the model. Through the three-dimensional full-parameterized model, the propagation and scattering of electromagnetic radiation in the system and the interaction between the system and the external electromagnetic environment can be accurately simulated. The equivalent circuit model is a model that uses circuit elements (such as resistors, capacitors, inductors, transistors, etc.) and circuit connection relationships to equivalently represent the electronic components and cables in the video monitoring system. The equivalent circuit model simplifies the complex electronic system into a circuit form that is easy to analyze and calculate based on the circuit principle and electrical characteristics of the system.

[0101] Optionally, professional three-dimensional modeling software can be used to accurately model the actual size and structure of the video monitoring system. In the modeling process, the size, shape and material properties of each component are defined in detail, and then the model is imported into the electromagnetic field simulation software for subsequent processing; then according to the circuit schematic diagram of the video monitoring system, the equivalent circuit model is constructed using circuit simulation software, and in the model, the parameters and connection relationships of each electronic component are accurately set.

[0102] Step 404, based on the three-dimensional full-parameterized model, a simulation environment for simulating transient electromagnetic radiation electric field is established, and the equivalent circuit model is combined with the simulation environment to construct a field-circuit collaborative model.

[0103] wherein the simulation of transient electromagnetic radiation electric field refers to the simulation of rapidly changing electromagnetic radiation electric field generated in a short time (such as lightning, switch operation, etc. instantaneous event). The simulation environment refers to the software platform and related settings for electromagnetic field simulation, including the import of the three-dimensional full-parameterized model, the definition of material properties, the setting of boundary conditions, the application of excitation source and the selection of solver, etc. The simulation environment provides a virtual experimental platform for electromagnetic field simulation. By setting different parameters and conditions, various actual electromagnetic scenes can be simulated to obtain the response results of the video monitoring system under different electromagnetic environments.

[0104] Optionally, a three-dimensional full parametric model can be imported into an electromagnetic field simulation software, material properties (such as conductivity, dielectric constant, etc.) of each component in the model are defined, boundary conditions such as absorbing boundary, ground boundary, etc. are set to simulate the actual electromagnetic environment; then a transient electromagnetic radiation electric field excitation source is applied, the parameters of the excitation source can be set according to the actual situation; then the equivalent circuit model is connected with the electromagnetic field simulation environment through a specific interface or method, the circuit-field co-simulation tool can be used to interact and couple the current and voltage information in the circuit model with the electric field and magnetic field information in the electromagnetic field model.

[0105] In this embodiment, the physical structure of the system is accurately described by the three-dimensional full parametric model, and the circuit behavior of the system is analyzed by combining the equivalent circuit model, which can more accurately simulate the response of the video monitoring system under the transient electromagnetic radiation electric field and improve the accuracy of the analysis results; in addition, the field-circuit collaborative model comprehensively considers the interaction between the electromagnetic field and the circuit, which can not only analyze the influence of spatial radiation coupling on the system, but also analyze the influence of line conduction coupling, and can comprehensively evaluate the electromagnetic compatibility of the video monitoring system.

[0106] In one embodiment, as shown in Figure 5 Based on the field-circuit collaborative model, the first interference voltage of the spatial radiation coupling to the port of the video monitoring system is obtained, including:

[0107] Step 502, based on the field-circuit collaborative model, the distribution parameters induced by the transient electromagnetic radiation electric field on the cable are calculated.

[0108] The distribution parameters refer to the resistance, inductance, capacitance and conductance parameters distributed along the transmission line (such as the cable connected to the video monitoring system). For the effect of the transient electromagnetic radiation electric field on the cable, the distribution parameters specifically represent the distribution current and the distribution voltage. The distribution current refers to the current flowing through the cross section of the cable at different positions, and the distribution voltage refers to the voltage difference between different positions of the cable. The distribution parameters are not concentrated at a certain point, but continuously distributed along the entire length of the cable. The distribution parameters include the distribution current and / or the distribution voltage.

[0109] Optionally, electromagnetic field simulation software can be used to perform numerical solution based on field-circuit collaborative model. The software will calculate the distributed current and voltage on the cable according to Maxwell's equations, combined with the geometric structure of the cable in the three-dimensional full parameter model, material properties and simulation environment settings of the transient electromagnetic radiation electric field. For example, the cable is divided into many small units by using the finite element method, and the electromagnetic field of each unit is analyzed to obtain the distributed parameters of the entire cable. For some relatively simple cable structures, under certain approximation conditions, analytical formulas can be used for calculation. For example, for a uniform transmission line, the analytical expressions of the distributed current and voltage can be derived according to the transmission line equation and the related boundary conditions, and then substituted into the specific parameters for calculation.

[0110] Step 504, the distributed current and / or distributed voltage are injected into the equivalent circuit model as an excitation source, and a first interference voltage is obtained through a virtual voltage probe arranged at the port of the equivalent circuit model.

[0111] The virtual voltage probe is a virtual measurement tool arranged in the equivalent circuit model and does not actually exist in the physical circuit, but is used in the simulation software to measure the voltage value at a specific port. Its principle is similar to that of an actual voltage probe, except that the measurement process is simulated by software algorithms.

[0112] Optionally, the equivalent circuit model can be opened in the circuit simulation software, and the distributed current or distributed voltage calculated in step 502 is added to the corresponding position as an excitation source. For example, if the distributed current is calculated, it can be injected as a current source to the corresponding circuit node of the cable; if it is a distributed voltage, it is injected as a voltage source; a virtual voltage probe is arranged at the video monitoring system port of the equivalent circuit model. In the circuit simulation software, there are usually special measurement tools or functions to set up virtual voltage probes. After setting up, the simulation is run, and the software will automatically record the voltage value measured by the probe, which is the first interference voltage.

[0113] In this embodiment, the field-circuit collaborative model comprehensively considers the interaction between electromagnetic field and circuit. By first calculating the distributed parameters on the cable and then injecting them as excitation sources into the equivalent circuit model, the influence of spatial radiation coupling on the video monitoring system port can be more accurately simulated, and the errors caused by simply using field models or circuit models can be avoided.

[0114] In one embodiment, as shown in Figure 6 Based on the substation ground net and shielding cable simulation model, a multi-conductor transmission line system model is constructed, including:

[0115] Step 602, based on the soil layering structure data and the grounding net topology data of the location where the video monitoring system is located, a ground net frequency domain impedance matrix model is established by the method of moments.

[0116] The soil layering structure data is used to describe the layering of the soil at the location where the video monitoring system is located in the vertical direction and the related electrical characteristics, including the thickness, electrical conductivity, and relative permittivity of each layer of soil. The parameters of different layers of soil can be different, and these data are crucial for accurately simulating the electromagnetic interaction between the grounding grid and the soil. The grounding grid topology data refers to the information about the physical layout and connection relationship of the grounding grid of the substation, including the geometric shape (such as length, width, height) of the conductors in the grounding grid, the connection mode (such as welding, bolt connection) between the conductors, the position coordinates of the conductors, and the like, which are used to determine the electrical structure of the grounding grid. The method of moments is a numerical calculation method that discretizes continuous equations into algebraic equation systems, which is commonly used to solve electromagnetic field problems. The grounding grid frequency-domain impedance matrix model is a mathematical model that describes the electrical characteristics of the grounding grid at different frequencies, and represents the impedance relationship between nodes in the grounding grid in matrix form.

[0117] Optionally, the soil layering structure data and the grounding grid topology data can be collected first and arranged into a format suitable for numerical calculation; then the method of moments is used to discretize the conductors in the grounding grid into a series of small line segments or surface elements, and based on the electrical characteristics of the soil and the geometric structure of the conductors, integral equations are established; then the integral equations are discretized into matrix equations, and the grounding grid frequency-domain impedance matrix model is obtained by solving the matrix equations. Professional electromagnetic field simulation software can be used to realize this process.

[0118] At step 604, based on the laying path of the secondary cable, the shielding layer structure, and the grounding mode, unit excitation currents at different preset frequencies are injected at the preset fault point positions of the substation grounding grid, and the current distribution of the secondary cable shielding layer is solved.

[0119] The secondary cable is a cable used to connect secondary devices (such as protection devices, measurement devices, control devices, etc.) and primary devices (such as transformers, circuit breakers, etc.) in a substation. It is mainly used to transmit control signals, measurement signals, and protection signals, etc. The shielding layer structure refers to the physical structure of the secondary cable shielding layer, including the material (such as copper, aluminum, etc.), thickness, and weaving method (such as weaving density, weaving angle) of the shielding layer. Different shielding layer structures have an important impact on the shielding effect of the cable. The grounding method of the secondary cable shielding layer has many kinds, such as single-point grounding, multi-point grounding, etc. The grounding method will affect the distribution of current in the shielding layer and the anti-interference ability of the cable. The preset fault point is a position where a fault may occur in the substation ground grid. In the simulation, the electrical response of the ground grid and the secondary cable under fault conditions is simulated by injecting excitation current at these positions. The unit excitation current refers to a current signal with an amplitude of 1, which is injected into the preset fault point at a preset frequency. By injecting the unit excitation current, the response of the system can be easily calculated, and the transmission characteristics of the system can be obtained. The current distribution of the secondary cable shielding layer refers to the distribution of the current size and direction at different positions in the secondary cable shielding layer after the unit excitation current at the preset frequency is injected into the preset fault point. The current distribution of the secondary cable shielding layer reflects the propagation of electromagnetic interference in the secondary cable shielding layer when the ground grid fails.

[0120] Optionally, an electromagnetic model of the secondary cable can be established according to the laying path of the secondary cable, the shielding layer structure, and the grounding method; then unit excitation currents with different preset frequencies (such as 50 Hz, 1 kHz, 10 kHz, etc.) are injected into the preset fault point positions of the substation ground grid; finally, the electromagnetic field simulation software or numerical calculation method (such as the finite element method, the time domain finite difference method, etc.) is used to solve the current distribution of the secondary cable shielding layer.

[0121] Step 606, based on the shielding layer structure parameters of the secondary cable, the transfer impedance of the secondary cable at the preset frequency is calculated.

[0122] The transfer impedance is a parameter that describes the degree of electromagnetic coupling of the secondary cable shielding layer to the internal conductor. It represents the ratio of the voltage induced on the internal conductor by the current on the shielding layer to the shielding layer current, and reflects the shielding effect of the shielding layer on external electromagnetic interference.

[0123] Optionally, the transfer impedance of the secondary cable at the preset frequency can be calculated using relevant theoretical formulas (such as transmission line theory, electromagnetic shielding theory, etc.) according to the structural parameters of the secondary cable shielding layer, such as the material, thickness, and weaving method; then the transfer impedance at different frequencies is obtained through experimental measurement.

[0124] Step 608, based on the current distribution of the secondary cable shielding layer and the transfer impedance, a multi-conductor transmission line system model is constructed.

[0125] Optionally, the voltage and current equations of the multi-conductor transmission line system can be established according to the current distribution and transfer impedance of the secondary cable shielding layer in combination with the multi-conductor transmission line theory; and the equations can be arranged into a matrix form to obtain the multi-conductor transmission line system model.

[0126] In this embodiment, various factors such as the layered structure of the soil, the grounding grid topology, the laying and shielding of the secondary cable, etc. are comprehensively considered, and the model is established by an accurate numerical calculation method, so that the electromagnetic characteristics of the grounding grid and the secondary cable of the substation under fault conditions can be more accurately simulated, and the accuracy of the analysis result is improved.

[0127] In one embodiment, as shown in FIG. 7, based on the multi-conductor transmission line system model, the second interference voltage conducted by the line to the port of the video monitoring system is obtained, including: Figure 7

[0128] Step 702, determining the distributed excitation source acting on the multi-conductor transmission line system model based on the current distribution and transfer impedance of the secondary cable shielding layer.

[0129] The distributed excitation source refers to the excitation factor distributed along the transmission line due to the interaction between the current distribution and the transfer impedance of the secondary cable shielding layer in the multi-conductor transmission line system. The distributed excitation source is the source of the change of the current and voltage in the multi-conductor transmission line, through which the electromagnetic interference effect on the secondary cable shielding layer can be transmitted to the entire multi-conductor transmission line system, and then affect the voltage of the port of the video monitoring system.

[0130] Optionally, according to the electromagnetic theory, there is a certain relationship between the distributed excitation source and the current distribution and transfer impedance of the secondary cable shielding layer. For the multi-conductor transmission line system, the relevant formula in the transmission line theory, such as the formula derived based on the Maxwell equations, can be used to substitute the current distribution and transfer impedance of the secondary cable shielding layer, calculate the expression of the distributed excitation source, for example, in the case of a uniform transmission line, the specific value of the distributed excitation source can be obtained by integration and other mathematical operations according to the known current distribution and transfer impedance; and the professional electromagnetic field simulation software is used to construct the multi-conductor transmission line system model with the current distribution and transfer impedance of the secondary cable shielding layer as input parameters. The software will automatically calculate the distributed excitation source acting on the multi-conductor transmission line system model according to the built-in algorithm and physical model.

[0131] Step 704, injecting the distributed excitation source into the multi-conductor transmission line system model, and solving the preset transmission line equation to obtain the second interference voltage.

[0132] ​The preset transmission line equations are mathematical equations describing the relationship between voltage and current in a multi-conductor transmission line as a function of position and time. By solving the preset transmission line equations, the voltage and current values ​​at each point in the multi-conductor transmission line system can be obtained, thereby determining the second interference voltage conducted to the video surveillance system port.

[0133] Optionally, for some simple multi-conductor transmission line systems, the preset transmission line equations can be solved analytically. First, the distributed excitation source is substituted into the preset transmission line equations. Then, based on boundary conditions (such as the load conditions at the transmission line terminals), mathematical methods (such as Laplace transform, Fourier transform, etc.) are used to solve the equations, yielding analytical expressions for voltage and current. Finally, the location of the video surveillance system port is substituted into the expressions to calculate the second interference voltage.

[0134] Furthermore, analytical solutions are often difficult for complex multi-conductor transmission line systems. In such cases, numerical methods can be used to solve the pre-defined transmission line equations. Common numerical methods include the finite difference method and the finite element method. Using professional circuit simulation software, a multi-conductor transmission line system model is built within the software, and distributed excitation sources are injected into the model. The software automatically discretizes the pre-defined transmission line equations and iteratively solves the discretized equations to obtain the voltage and current values ​​at various points in the multi-conductor transmission line system, thereby acquiring the second interference voltage at the video surveillance system port.

[0135] In this embodiment, the distributed excitation source is determined based on the actual current distribution and transfer impedance of the secondary cable shielding layer, which can accurately reflect the coupling of electromagnetic interference in the multi-conductor transmission line system. By solving the preset transmission line equation, the second interference voltage conducted to the video surveillance system port can be accurately calculated, providing accurate data support for evaluating the anti-interference performance of the video surveillance system.

[0136] In one embodiment, such as Figure 8 As shown, based on the shielding structure parameters of the secondary cable, the transfer impedance of the secondary cable at a preset frequency is calculated, including:

[0137] Step 802: Calculate the initial transfer impedance of the secondary cable at a preset frequency based on the shielding structure parameters of the secondary cable.

[0138] The initial transfer impedance is the transfer impedance of the secondary cable at a preset frequency, calculated based on the basic structural parameters of the secondary cable shield (such as the conductivity, permeability, thickness, and braiding method of the shield material), without considering some complex influencing factors (such as the non-uniformity of the surrounding medium).

[0139] Optionally, based on transmission line theory and electromagnetic shielding theory, there are corresponding theoretical formulas to calculate the initial transfer impedance for different shielding structures (such as braided shielding layers, metal foil shielding layers, etc.). Alternatively, professional measuring equipment (such as a network analyzer) can be used to test the secondary cable and measure the transfer impedance at different frequencies to obtain experimental data on the initial transfer impedance. For example, taking a braided shielding layer as an example, the initial transfer impedance can be calculated using the following formula. : ,in, It is the surface resistance of the shielding layer; It is the average radius of the shielding layer; It is the wavelength of the electromagnetic wave, which is related to the preset frequency. , It's the speed of light.

[0140] Step 804: Correct the initial transfer impedance according to the preset dielectric constant gradient factor to obtain the transfer impedance of the secondary cable at the preset frequency.

[0141] The preset dielectric constant gradient factor is a coefficient used to correct the initial transfer impedance. In real-world environments, the dielectric constant of the medium surrounding the secondary cable (such as soil or air) may be non-uniform. This non-uniformity can affect the coupling of electromagnetic interference between the cable shield and the internal conductor. The preset dielectric constant gradient factor takes into account the impact of this dielectric constant variation on the transfer impedance. By correcting the initial transfer impedance using this factor, a transfer impedance value that more closely reflects the actual situation can be obtained.

[0142] Optionally, based on electromagnetic theory and the dielectric constant distribution of the medium surrounding the secondary cable, the relationship between a preset dielectric constant gradient factor and the transfer impedance can be derived. This factor can then be used to correct the initial transfer impedance. The transfer impedance of the secondary cable at a preset frequency can be calculated using the following formula. :

[0143] ;

[0144] In the formula, It is a preset dielectric constant gradient factor.

[0145] In this embodiment, the initial transfer impedance is first calculated, and then corrected using a preset dielectric constant gradient factor, further considering the influence of dielectric constant inhomogeneity in the surrounding medium. This step-by-step calculation and correction method can more accurately calculate the transfer impedance of the secondary cable at a preset frequency, improving the consistency between the calculation results and the actual situation.

[0146] In one embodiment, such as Figure 9As shown, after obtaining the second interference voltage conducted to the video surveillance system port, the method further includes:

[0147] Step 902: Determine the electromagnetic interference influence weights of the transient electromagnetic radiation electric field and the electromagnetic interference influence weights of the line conduction based on the ratio of the second interference voltage to the first interference voltage.

[0148] Optionally, assuming the ratio of the second interference voltage to the first interference voltage is 1:3, the weight of electromagnetic interference influence of transient electromagnetic radiation electric field is 0.25, and the weight of electromagnetic interference influence of line conduction is 0.75.

[0149] Step 904: Compare the electromagnetic interference influence weights of transient electromagnetic radiation electric fields and electromagnetic interference influence weights of line conduction to obtain the comparison results.

[0150] Alternatively, taking the weighting example above as an example, it is clear that the comparison result shows that the weight of electromagnetic interference from transient electromagnetic radiation electric field is less than the weight of electromagnetic interference from line conduction.

[0151] Step 906: Based on the comparison results, determine the main interference path of the video surveillance system.

[0152] Optionally, taking the above comparison results as an example, since the comparison results show that the electromagnetic interference influence weight of transient electromagnetic radiation electric field is less than the electromagnetic interference influence weight of line conduction, it can be determined that the main interference path of video surveillance is line conduction.

[0153] In this embodiment, by determining and comparing the influence weights of transient electromagnetic radiation electric fields and electromagnetic interference conducted through lines, it is possible to clearly understand which interference source has a greater impact on the system ports in a video surveillance system. This helps to focus on the main interference sources in anti-interference design and troubleshooting, thereby improving the pertinence and effectiveness of anti-interference measures.

[0154] In a detailed embodiment, the following uses a typical application scenario of a 500kV smart substation as an example, combined with... Figure 10 The flowchart shown illustrates the calculation process for transient electromagnetic interference coupling characteristics of a video surveillance system, detailing the implementation process of dual-path transient electromagnetic interference coupling characteristics in an intelligent video surveillance system. The implementation process is divided into three stages: spatial radiation coupling characteristic calculation, line conduction coupling characteristic calculation, and coupling path analysis.

[0155] Step 1: Establish a far-field coupling model for the data acquisition gateway of the substation video monitoring system, such as... Figure 1As shown, the far-field simulation range is defined with a radius greater than 1 / 6 of the wavelength, centered on the video surveillance system (data acquisition gateway). When the data acquisition gateway and its various types of cables are within the simulation range, the spatial radiated electric field is simulated using plane waves, under which the ratio of magnetic field strength to electric field strength remains constant. With the radiation field direction fixed, the interference voltage coupled from the spatial radiated electric field to the cable core terminals is simulated.

[0156] Step 2: Analyze the coupling effect of the transient electromagnetic radiation field of the substation on the cable of the sensor data acquisition gateway. By establishing a simulation excitation signal, and based on the far-field radiation interference calculation model of the communication line and power line of the sensor data acquisition gateway, simulate the voltage of the cable core port coupled by the spatial radiation electric field, and further obtain the interference characteristics of radiation on various types of cables of the data acquisition gateway.

[0157] Step 3: Establish an equivalent circuit model of the monitoring system and calculate the induced voltage of various types of cables in the data acquisition gateway within the plane wave electric field with added transient excitation. The data acquisition gateway body is simulated using a square metal shell model. The cable modeling parameters are set as follows: the network cable adopts a 2×4 standard logarithmic structure, with all four twisted pairs consisting of copper core conductors, polyethylene insulation layer, and PVC sheath; compared to the network cable structure, the coaxial cable has an additional copper mesh braided shielding layer outside the insulation layer; the power line is a double-wire structure with copper conductors inside and PVC insulation layer outside. The calculated coupling voltages at each cable port of the data acquisition gateway in the far field of the radiated electric field are as follows: Figure 11 As shown.

[0158] Step 4: Construct a refined model of the 500kV substation grounding system, such as... Figure 12 As shown. The main grounding grid within the substation measures 312m in length and 270m in width, with a total area of ​​approximately 84,240m². 2 A rectangular grounding grid is constructed, consisting primarily of horizontal grounding electrodes, using φ22 galvanized round steel. The grid is buried 0.8 m deep inside the station and 1.2 m deep along the outer edge. The grounding grid's equipotential bonding strips are arranged at unequal intervals, with the outer edge of the horizontal grounding conductors forming a closed loop. Sixteen deep grounding wells are installed within the station, each approximately 30 m long. Outdoor cables are laid using cable trenches, direct burial, and conduit methods. Five cables of equal length from the power supply panel to the intelligent terminal box, but at different distances from the fault point, are selected as the first group of target cables (No. 1 to No. 5); five cables of different lengths at the same distance from the fault point are selected as the second group of target cables (No. 6 to No. 10).

[0159] Step 5: Based on the grounding grid model, construct secondary cable shielding layer models. The first set of target shielded cables is 125m long, with the shielding layer made of braided copper wire and a cross-sectional radius of 7.35mm. The calculated substation secondary cable shielding layer current and core coupling voltage are as follows:Figure 13 As shown.

[0160] Step 6: Based on simulation results, during the occurrence of transient electromagnetic interference, in addition to the spatial electric field generated by the transient interference source causing electromagnetic interference to the equipment in the form of electric field radiation, it also enters the various cable ports of the equipment through conduction via the substation grounding grid, causing interference to the sensing and monitoring equipment. By superimposing the coupling voltage of spatial radiation and line conduction, a cable port coupling voltage that comprehensively considers both paths is obtained. The proposed transient electromagnetic interference coupling path for the intelligent substation monitoring system is as follows: Figure 2 As shown.

[0161] This implementation method, through a closed-loop process of theoretical modeling, numerical simulation, and coupling path analysis, fully realizes the accurate quantification of the coupling characteristics of transient electromagnetic interference on intelligent video monitoring devices and the comprehensive analysis of coupling paths, providing a standardized technical route for the electromagnetic protection design of substation secondary equipment.

[0162] It should be understood that although the steps in the flowcharts of the embodiments described above are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages of other steps.

[0163] Based on the same inventive concept, this application also provides a transient electromagnetic interference voltage determination device for implementing the transient electromagnetic interference voltage determination method described above. The solution provided by this device is similar to the solution described in the above method; therefore, the specific limitations in one or more embodiments of the transient electromagnetic interference voltage determination device provided below can be found in the limitations of the transient electromagnetic interference voltage determination method described above, and will not be repeated here.

[0164] In one embodiment, such as Figure 14 As shown, a transient electromagnetic interference voltage determination device is provided, comprising: a field-circuit cooperative model construction module 1402, a first interference voltage determination module 1404, a transmission line system model construction module 1406, a second interference voltage determination module 1408, and a transient electromagnetic interference voltage determination module 1410, wherein:

[0165] The field-path coordination model construction module 1402 is used to construct a field-path coordination model based on the parameter information of the video surveillance system and the cables connected to the video surveillance system.

[0166] The first interference voltage determination module 1404 is used to obtain the first interference voltage that is spatially radiated and coupled to the port of the video surveillance system based on the field-path cooperation model.

[0167] Transmission line system model building module 1406 is used to build a multi-conductor transmission line system model based on the simulation model of substation grounding grid and shielded cable;

[0168] The second interference voltage determination module 1408 is used to obtain the second interference voltage conducted to the video surveillance system port based on the multi-conductor transmission line system model.

[0169] The transient electromagnetic interference voltage determination module 1410 is used to superimpose the first interference voltage and the second interference voltage to obtain the transient electromagnetic interference voltage of the video surveillance system port.

[0170] In one embodiment, the field-circuit cooperative model construction module 1402 is also used to: construct a three-dimensional fully parameterized model and an equivalent circuit model of the video surveillance system; based on the three-dimensional fully parameterized model, establish a simulation environment for simulating transient electromagnetic radiation electric fields, and combine the equivalent circuit model with the simulation environment to construct a field-circuit cooperative model.

[0171] In one embodiment, the field-circuit cooperative model construction module 1402 is further configured to: calculate the distribution parameters of the transient electromagnetic radiation electric field induced on the cable based on the field-circuit cooperative model; the distribution parameters include distributed current and / or distributed voltage; inject the distributed current and / or distributed voltage as an excitation source into the equivalent circuit model, and obtain the first interference voltage through a virtual voltage probe set at the port of the equivalent circuit model.

[0172] In one embodiment, the transmission line system model building module 1406 is further configured to: establish a grounding grid frequency domain impedance matrix model using the method of moments based on soil stratification data and grounding grid topology data of the location of the video surveillance system; inject unit excitation current at different preset frequencies at preset fault points in the substation grounding grid based on the laying path, shielding structure, and grounding method of the secondary cable, and solve for the current distribution of the secondary cable shielding layer; calculate the transfer impedance of the secondary cable at preset frequencies based on the shielding structure parameters of the secondary cable; and construct a multi-conductor transmission line system model based on the current distribution and transfer impedance of the secondary cable shielding layer.

[0173] In one embodiment, the transmission line system model construction module 1406 is further configured to: determine the distributed excitation source acting on the multi-conductor transmission line system model based on the current distribution and transfer impedance of the secondary cable shield; inject the distributed excitation source into the multi-conductor transmission line system model and solve the preset transmission line equation to obtain the second interference voltage.

[0174] In one embodiment, the transmission line system model building module 1406 is further configured to: calculate the initial transfer impedance of the secondary cable at a preset frequency based on the shielding structure parameters of the secondary cable; and correct the initial transfer impedance according to a preset dielectric constant gradient factor to obtain the transfer impedance of the secondary cable at the preset frequency.

[0175] In one embodiment, the device is further configured to determine the electromagnetic interference influence weight of the transient electromagnetic radiation electric field and the electromagnetic interference influence weight of the line conduction based on the ratio of the second interference voltage to the first interference voltage; compare the electromagnetic interference influence weight of the transient electromagnetic radiation electric field and the electromagnetic interference influence weight of the line conduction to obtain a comparison result; and determine the main interference path of the video surveillance system based on the comparison result.

[0176] Each module in the aforementioned transient electromagnetic interference voltage determination device can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in the processor of a computer device in hardware form or independent of it, or stored in the memory of a computer device in software form, so that the processor can call and execute the operations corresponding to each module.

[0177] In one embodiment, a computer device is provided, which may be a server, and its internal structure diagram may be as follows: Figure 15 As shown. The computer device includes a processor, memory, and network interface connected via a system bus. The processor provides computing and control capabilities. The memory includes a non-volatile storage medium and internal memory. The non-volatile storage medium stores an operating system, computer programs, and a database. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage medium. The database stores data related to the method for determining transient electromagnetic interference voltage, such as parameter information of the video surveillance system and the cables connected to it. The network interface communicates with external terminals via a network connection. When the computer program is executed by the processor, it implements a method for determining transient electromagnetic interference voltage.

[0178] In one embodiment, a computer device is provided, which may be a terminal, and its internal structure diagram may be as follows: Figure 15As shown, the computer device includes a processor, memory, communication interface, display screen, and input devices connected via a system bus. The processor provides computing and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs stored in the non-volatile storage media. The communication interface is used for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, mobile cellular networks, NFC (Near Field Communication), or other technologies. When executed by the processor, the computer program implements a method for determining transient electromagnetic interference voltage. The display screen can be an LCD screen or an e-ink screen. The input devices can be a touch layer covering the display screen, buttons, a trackball, or a touchpad mounted on the computer device casing, or an external keyboard, touchpad, or mouse.

[0179] Those skilled in the art will understand that Figure 15 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0180] In one embodiment, a computer device is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps in the above-described method embodiments.

[0181] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the steps in the above method embodiments.

[0182] In one embodiment, a computer program product is provided, including a computer program that, when executed by a processor, implements the steps in the above method embodiments.

[0183] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties.

[0184] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments described above. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc., and are not limited to these.

[0185] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0186] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A method for determining transient electromagnetic interference voltage, characterized in that, The method includes: Based on the parameter information of the video surveillance system and the cables connected to the video surveillance system, a field-road cooperative model is constructed; Based on the field-path cooperative model, the first interference voltage coupled to the port of the video surveillance system by spatial radiation is obtained; Based on the simulation model of substation grounding grid and shielded cable, a multi-conductor transmission line system model is constructed. Based on a multi-conductor transmission line system model, the second interference voltage conducted to the port of the video surveillance system is obtained. The first interference voltage and the second interference voltage are superimposed to obtain the transient electromagnetic interference voltage of the video surveillance system port.

2. The method according to claim 1, characterized in that, The construction of a field-road cooperative model based on parameter information of the video surveillance system and the cables connected to the video surveillance system includes: Construct a three-dimensional fully parameterized model and an equivalent circuit model of the video surveillance system; Based on the three-dimensional fully parameterized model, a simulation environment for simulating transient electromagnetic radiation electric fields is established, and the equivalent circuit model is combined with the simulation environment to construct the field-circuit cooperative model.

3. The method according to claim 2, characterized in that, The step of obtaining the first interference voltage coupled to the video surveillance system port by spatial radiation based on the field-path coordination model includes: Based on the field-circuit cooperative model, the distribution parameters of the transient electromagnetic radiation electric field induced on the cable are calculated; the distribution parameters include distributed current and / or distributed voltage. The distributed current and / or the distributed voltage are injected into the equivalent circuit model as an excitation source, and the first interference voltage is obtained by using a virtual voltage probe set at the port of the equivalent circuit model.

4. The method according to claim 1, characterized in that, The simulation model of the substation grounding grid and shielded cable is used to construct a multi-conductor transmission line system model, including: Based on the soil stratification data and grounding grid topology data of the location of the video surveillance system, a grounding grid frequency domain impedance matrix model is established using the method of moments. Based on the laying path, shielding structure, and grounding method of the secondary cable, unit excitation currents at different preset frequencies are injected at preset fault points in the substation grounding grid to obtain the current distribution of the secondary cable shielding layer. Based on the shielding structure parameters of the secondary cable, calculate the transfer impedance of the secondary cable at the preset frequency; Based on the current distribution of the secondary cable shield and the transfer impedance, a model of the multi-conductor transmission line system is constructed.

5. The method according to claim 4, characterized in that, The method for obtaining the second interference voltage conducted to the video surveillance system port based on the multi-conductor transmission line system model includes: Based on the current distribution of the secondary cable shield and the transfer impedance, the distributed excitation source acting on the multi-conductor transmission line system model is determined; The distributed excitation source is injected into the multi-conductor transmission line system model, and the preset transmission line equation is solved to obtain the second interference voltage.

6. The method according to claim 4, characterized in that, The calculation of the transfer impedance of the secondary cable at the preset frequency based on the shielding structure parameters of the secondary cable includes: Based on the shielding structure parameters of the secondary cable, the initial transfer impedance of the secondary cable at the preset frequency is calculated; The initial transfer impedance is corrected according to the preset dielectric constant gradient factor to obtain the transfer impedance of the secondary cable at the preset frequency.

7. The method according to claim 1, characterized in that, After acquiring the second interference voltage conducted to the video surveillance system port, the method further includes: The electromagnetic interference influence weights of the transient electromagnetic radiation electric field and the electromagnetic interference influence weights of the line conduction are determined based on the ratio of the second interference voltage to the first interference voltage. The comparison results are obtained by comparing the electromagnetic interference influence weight of the transient electromagnetic radiation electric field and the electromagnetic interference influence weight of the line conduction. Based on the comparison results, the main interference path of the video surveillance system is determined.

8. A device for determining transient electromagnetic interference voltage, characterized in that, The device includes: The field-path coordination model construction module is used to construct a field-path coordination model based on the parameter information of the video surveillance system and the cables connected to the video surveillance system. The first interference voltage determination module is used to obtain the first interference voltage that is spatially radiated and coupled to the port of the video surveillance system based on the field-path coordination model. The transmission line system model building module is used to build a multi-conductor transmission line system model based on the simulation model of the substation grounding grid and shielded cable; The second interference voltage determination module is used to obtain the second interference voltage conducted to the port of the video surveillance system based on the multi-conductor transmission line system model. The transient electromagnetic interference voltage determination module is used to superimpose the first interference voltage and the second interference voltage to obtain the transient electromagnetic interference voltage of the video surveillance system port.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 7.

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