Electromagnetic simulation method for rail transit system under complex environment and extreme working conditions

Abstract

The invention relates to the field of electrical engineering, in particular to a rail transit system electromagnetic simulation method under a complex environment and an extreme working condition. The method comprises the following steps: S1, constructing a rail transit system model, wherein the model comprises a contact network, a pantograph, a vacuum circuit breaker and a current transmission part; s2, constructing a tunnel model, setting different climate conditions for the tunnel model, and obtaining an electromagnetic field distribution simulation result of the tunnel model; and S3, constructing a pantograph-catenary electric arc model, enabling the pantograph-catenary electric arc model and the rail transit system model to interact with each other, setting excitation for the pantograph-catenary electric arc model, obtaining an excitation result, and superposing the excitation result onto the rail transit system model, thereby obtaining the total electromagnetic field distribution condition after superposition. The invention provides a high-precision simulation method which can more accurately analyze the electromagnetic field behavior of a rail transit system in a complex environment so as to optimize the design and operation of the system.

Description

Technical Field

[0001] The present invention relates to the field of electrical engineering, and in particular to an electromagnetic simulation method for a rail transit system under complex environments and extreme working conditions. Background Art

[0002] In rail transit systems, electromagnetic pollution is a serious problem. It not only causes equipment-level losses, but may also cause system-level mutual interference. If not properly handled, this pollution will greatly reduce the reliability of the communication system and may cause irreversible damage to personal and property safety. Especially in my country, rail transit systems often face the dual challenges of complex environments and extreme working conditions. The diversity of geographical environments and the resulting environmental complexity have a significant impact on the distribution of electromagnetic fields. On the one hand, China has a vast territory, from the eastern plains to the central basins, and then to the western plateaus. The terrain is high in the west and low in the east, and the environment is very complex. There are huge differences in the natural environment and architectural environment in which railways, intercity urban areas, and urban rail transit operate; on the other hand, the traction power supply system used in electrification is the main source of energy for the operation of rail transit systems, but in actual operation, factors such as the unevenness of the sliding contact surface, installation defects, or the passage of special sections such as the insulated anchor section joints can easily cause the pantograph carbon slide plate to detach from the contact line in an instant, the gap air is broken down, and a huge energy bow-net offline arc is generated. This arc event not only transfers energy to the pantograph and contact wire through heat conduction, but also affects the current intensity flowing through the electronic equipment, causing the distribution of the instantaneous electromagnetic field to be disordered, thereby causing the train to suffer extremely harsh working conditions during high-speed operation.

[0003] Therefore, at the beginning of the project implementation, it should be clear whether the electromagnetic environment is good. If it exceeds the specified standard, it is necessary to adjust the construction technology in time or take targeted shielding measures to effectively suppress electromagnetic pollution and improve the electromagnetic environment. Therefore, the present invention adopts a simulation method to study the distribution of electromagnetic fields around the rail transit system under complex environments and extreme working conditions, which is conducive to maintaining the safety of train operation and communication systems, and has great significance for the development and construction of my country's high-speed trains. It is a major technological breakthrough in the field of rail transit in the world. Summary of the invention

[0004] The purpose of the present invention is to overcome the following deficiencies in the prior art: (1) Failure to effectively simulate and predict the electromagnetic field distribution of rail transit systems under complex terrain and extreme electromagnetic interference conditions, resulting in the inability to fully guarantee the reliability and safety of the system; (2) There are also significant deficiencies in the corresponding and mitigation measures when dealing with sudden electromagnetic events, and the impact of these problems cannot be effectively prevented and controlled. In order to overcome the above problems, the present invention provides an electromagnetic simulation method for rail transit systems under complex environments and extreme working conditions, introduces high-precision simulation models and algorithms, and can more accurately analyze the behavior of electromagnetic fields, thereby optimizing the design and operation of rail transit systems; and, by proposing an improved arc model and corresponding simulation process, the invention helps to identify and solve the problem of sudden electromagnetic events in advance, thereby enhancing the overall reliability and safety of the system.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] A method for electromagnetic simulation of rail transit system under complex environment and extreme working conditions, comprising the following steps:

[0007] S1. Construct rail transit system model;

[0008] S2. constructing a tunnel model, wherein the tunnel model is a sub-model of the rail transit system model; obtaining an electromagnetic field distribution simulation result of the tunnel model by setting different climate conditions for the tunnel model;

[0009] S3. Construct a pantograph-catenary arc model, wherein the pantograph-catenary arc model interacts with the rail transit system model; obtain an excitation result by setting an excitation on the pantograph-catenary arc model, and superimpose the excitation result on the rail transit system model to obtain the total electromagnetic field distribution after superposition.

[0010] Preferably, the rail transit system model includes a contact network, a pantograph, a vacuum circuit breaker and a current transmission part; wherein: the contact network is simulated as a 25kV industrial frequency AC power supply with a center frequency of 50Hz, which serves as the main power supply source for the rail transit system; the pantograph is configured to receive power from the contact network; the vacuum circuit breaker is used to control the power on and off of the rail transit system model; the current transmission part includes guide rods and copper sheets, which are used to simulate the main transmission path of current in the rail transit system and provide the electrical connection required for electromagnetic simulation.

[0011] Preferably, the tunnel model includes:

[0012] 1) Set the length of the tunnel to L to simulate the electromagnetic field environment of the tunnel;

[0013] 2) The tunnel model also includes a steel mesh, and the density of the steel mesh is adjusted according to simulation requirements;

[0014] 3) inserting anchor rods into the tunnel model, and distributing the tunnel model into a fan-shaped structure through symmetric operations;

[0015] 4) Forming detailed geometric features inside the tunnel model through geometric shearing.

[0016] Preferably, setting different climate conditions for the tunnel model in step S2 is to simulate the electromagnetic field distribution under different climate conditions by setting soil parameters around the tunnel model.

[0017] Preferably, setting soil parameters comprises the following steps:

[0018] 1) Use the four-pole electrical detection method to measure the soil resistance value R;

[0019] 2) Calculate soil resistivity ρ 0 for

[0020] ρ 0 =2πaR

[0021] a is the interval between ground rods, R is the measured soil resistance value;

[0022] 3) Use seasonal correction factors in the tunnel model The seasonal correction factor adjusts the soil resistivity according to the climatic conditions before the measurement date; the climatic conditions include rainfall and soil moisture;

[0023] 4) According to soil resistivity ρ 0 and seasonal correction factor Calculate Standard Soil Resistivity

[0024] Preferably, the rail transit system model also includes a power supply, a contact network, a pantograph, a vacuum circuit breaker and a current transmission part; the contact network is configured as a 25kV industrial frequency AC power supply with a center frequency of 50HZ; the pantograph is configured to receive power from the contact network; the vacuum circuit breaker is used to control the on and off of the power supply; the current transmission part is composed of a guide rod and a copper sheet.

[0025] Preferably, the bow-catenary arc model simulates the impact of arc events on the surrounding electromagnetic environment through dynamic simulation of heat conduction and current intensity changes; further, the bow-catenary arc model is configured to perform instantaneous analysis on the arc center during the stable burning stage of the arc.

[0026] Preferably, the pantograph-catenary arc model further comprises a conductor and a pantograph carbon slide plate, wherein the thermal conductivity of the conductor is k 1The resistivity of the pantograph carbon slide plate is ρ 1 and the thermal conductivity is k 2 ,; The maximum diameter of the central radiation heat source in the stable combustion stage of the arc is D 1 , the plane arc diameter is d 1 to d 2 Changes between.

[0027] Preferably, the thermal conductivity of the wire is about 386-413 W / (m·K), the resistivity of the pantograph carbon slide plate is about 7-12 μΩ / m and the thermal conductivity is 5-7 W / (m·K); the maximum diameter of the central radiation heat source in the stable combustion stage of the arc is 6 mm, and the plane arc diameter varies between 3 mm and 2 mm.

[0028] Preferably, setting excitation for the pantograph-catenary arc model comprises the following steps:

[0029] 1) Select an excitation source, which is a specific voltage or current waveform; the excitation parameters are an industrial frequency AC power supply with a center frequency of 50 Hz and a voltage of 25 kV;

[0030] 2) using the excitation source to set the excitation on the pantograph-catenary arc model and obtain the excitation result; the excitation is realized at both ends of the pantograph-catenary arc model by defining boundary conditions or sources to simulate the generation of arc;

[0031] 3) Applying the excitation result of the pantograph-catenary arc model to the rail transit system model through the superposition principle; wherein, during the superposition process, the total distribution of the electric field and the magnetic field is expressed by the formula

[0032] E total =E arc +E bg

[0033] B total =B arc +B bg

[0034] To calculate; where E arc and B arc Respectively represent the electric field and magnetic field generated by the excitation source; E bg and B bg represent the electric field and magnetic field of the rail transit system model respectively; E total and B total Represent the total electric field and total magnetic field after superposition, respectively.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] 1. The existing technology fails to fully simulate the distribution of electromagnetic fields under complex terrain and extreme electromagnetic interference conditions. The present invention, by introducing high-precision simulation models and algorithms, can more accurately predict and analyze the behavior of electromagnetic fields, thereby optimizing the design and operation of rail transit systems.

[0037] 2. Aiming at the deficiencies of the prior art in dealing with electromagnetic interference, especially the instantaneous electromagnetic disturbance caused by the arc between the catenary and the bow, the present invention proposes an improved arc model and a corresponding simulation process to reduce the impact of these interferences on the safety of rail transit.

[0038] 3. Through more accurate electromagnetic field simulation, the present invention helps to identify and solve problems that may cause communication interruption and equipment damage in advance, thereby enhancing the overall reliability and safety of the system.

[0039] 4. The simulation method provided by the invention can be used to support the selection of construction technology and the diagnosis of problems in operation and maintenance, especially in complex and extreme environmental conditions, and can make more scientific decisions based on the simulation results. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a flow chart of an analysis method for electromagnetic simulation of a rail transit system according to Embodiment 1 of the present invention;

[0041] Figure 2 This is a simplified schematic diagram of a rail transit system model according to Embodiment 2 of the present invention;

[0042] Figure 3 This is a schematic diagram of a pantograph-catenary arc model according to Embodiment 2 of the present invention;

[0043] Figure 4 This is a curve diagram of the arc area, perimeter and power variation of the bow-catenary according to Embodiment 2 of the present invention;

[0044] Figure 5 This is a schematic diagram of a tunnel model according to Embodiment 2 of the present invention;

[0045] Figure 6 This is a schematic diagram of anchor rod distribution in a tunnel model according to Embodiment 2 of the present invention;

[0046] Figure 7 This is a schematic diagram of the quadrupole electrical detection method of Example 2 of the present invention;

[0047] Figure 8 This is an electric field distribution diagram of a rail transit system under normal conditions according to Embodiment 2 of the present invention;

[0048] Fig. 9 This is the electric field distribution diagram of the rail transit system after continuous rainfall in Example 2 of the present invention. DETAILED DESCRIPTION

[0049] The electromagnetic simulation method of a rail transit system under complex environments and extreme working conditions provided by the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. However, this should not be understood as the scope of the above-mentioned subject matter of the present invention being limited to the following embodiments. All technologies implemented based on the content of the present invention belong to the scope of the present invention. Combined with the following description, the advantages and features of the present invention will become clearer. It should be noted that the drawings are all in a very simplified form and use non-precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0050] Example 1

[0051] like Figure 1 As shown, this embodiment provides an electromagnetic simulation method for a rail transit system under complex environments and extreme working conditions, comprising the following steps:

[0052] S1. Construct rail transit system model;

[0053] S2. constructing a tunnel model, wherein the tunnel model is a sub-model of the rail transit system model; obtaining an electromagnetic field distribution simulation result of the tunnel model by setting different climate conditions for the tunnel model;

[0054] S3. Construct a pantograph-catenary arc model, wherein the pantograph-catenary arc model interacts with the rail transit system model; obtain an excitation result by setting an excitation on the pantograph-catenary arc model, and superimpose the excitation result on the rail transit system model to obtain the total electromagnetic field distribution after superposition.

[0055] Preferably, the rail transit system model includes a contact network, a pantograph, a vacuum circuit breaker and a current transmission part; wherein: the contact network is simulated as a 25kV industrial frequency AC power supply with a center frequency of 50Hz, which serves as the main power supply source for the rail transit system; the pantograph is configured to receive power from the contact network; the vacuum circuit breaker is used to control the power on and off of the rail transit system model; the current transmission part includes guide rods and copper sheets, which are used to simulate the main transmission path of current in the rail transit system and provide the electrical connection required for electromagnetic simulation.

[0056] Preferably, the tunnel model includes:

[0057] 1) Set the length of the tunnel to L to simulate the electromagnetic field environment of the tunnel;

[0058] 2) The tunnel model also includes a steel mesh, and the density of the steel mesh is adjusted according to simulation requirements;

[0059] 3) inserting anchor rods into the tunnel model, and distributing the tunnel model into a fan-shaped structure through symmetric operations;

[0060] 4) Forming detailed geometric features inside the tunnel model through geometric shearing.

[0061] Preferably, setting different climate conditions for the tunnel model in step S2 is to simulate the electromagnetic field distribution under different climate conditions by setting soil parameters around the tunnel model.

[0062] Preferably, setting the soil parameters also includes determining the standard soil resistivity ρ, including the following steps:

[0063] 1) Obtain soil resistance value R by quadrupole electrical probing method;

[0064] 2) Calculate soil resistivity ρ 0 for

[0065] ρ 0 =2πaR

[0066] a is the interval between ground rods, R is the measured soil resistance value;

[0067] 3) Use seasonal correction factors in the tunnel model The seasonal correction factor adjusts the soil resistivity according to the climatic conditions before the measurement date; the climatic conditions include rainfall and soil moisture;

[0068] 4) According to soil resistivity ρ 0 and seasonal correction factor Calculate Standard Soil Resistivity

[0069] Preferably, the rail transit system model also includes a power supply, a contact network, a pantograph, a vacuum circuit breaker and a current transmission part; the contact network is configured as a 25kV industrial frequency AC power supply with a center frequency of 50HZ; the pantograph is configured to receive power from the contact network; the vacuum circuit breaker is used to control the on and off of the power supply; the current transmission part is composed of a guide rod and a copper sheet.

[0070] Preferably, the bow-catenary arc model simulates the impact of arc events on the surrounding electromagnetic environment through dynamic simulation of heat conduction and current intensity changes; further, the bow-catenary arc model is configured to perform instantaneous analysis on the arc center during the stable burning stage of the arc.

[0071] Preferably, the pantograph-catenary arc model also includes physical parameters of the conductor and the pantograph carbon slide plate, wherein the thermal conductivity of the conductor is k 1 The resistivity of the pantograph carbon slide plate is ρ 1 and the thermal conductivity is k 2 ,; The maximum diameter of the central radiation heat source in the stable combustion stage of the arc is D 1 , the plane arc diameter is d1 to d 2 Changes between.

[0072] Preferably, the thermal conductivity of the wire is about 386-413 W / (m·K), the resistivity of the pantograph carbon slide plate is about 7-12 μΩ / m and the thermal conductivity is 5-7 W / (m·K); the maximum diameter of the central radiation heat source in the stable combustion stage of the arc is 6 mm, and the plane arc diameter varies between 3 mm and 2 mm.

[0073] Preferably, setting excitation for the pantograph-catenary arc model comprises the following steps:

[0074] 1) Select an excitation source, which is a specific voltage or current waveform; the excitation parameters are an industrial frequency AC power supply with a center frequency of 50 Hz and a voltage of 25 kV;

[0075] 2) using the excitation source to set the excitation on the pantograph-catenary arc model and obtain the excitation result; the excitation is realized at both ends of the pantograph-catenary arc model by defining boundary conditions or sources to simulate the generation of arc;

[0076] 3) Applying the excitation result of the pantograph-catenary arc model to the rail transit system model through the superposition principle; wherein, during the superposition process, the total distribution of the electric field and the magnetic field is expressed by the formula

[0077] E total =E arc +E bg

[0078] B total =B arc +B bg

[0079] To calculate; where E arc and B arc Respectively represent the electric field and magnetic field generated by the excitation source; E bg and B bg represent the electric field and magnetic field of the rail transit system model respectively; E total and B total Represent the total electric field and total magnetic field after superposition, respectively.

[0080] Example 2

[0081] This embodiment provides a method for electromagnetic simulation of rail transit system under complex environment and extreme working conditions, by constructing a simplified rail transit system model, a pantograph arc model and a tunnel model, and setting the climate conditions, and finally setting excitation for the pantograph arc model and superimposing it on the rail transit system model to obtain the surrounding electrostatic field distribution. The method described in this embodiment includes the following steps:

[0082] S1. Construct a simplified rail transit system model;

[0083] The simplified rail transit system model is constructed by using the external circuit components (Equivalent Circuit) of the Maxwell module of ANSYS software to construct an electronic component level connection diagram, such as Figure 2 As shown. The rail transit system includes: a contact network, a pantograph and a vacuum circuit breaker, a current transmission part and a system regarded as a gray box. Among them, the contact network is simulated as a 25kV industrial frequency AC power supply with a center frequency of 50Hz, which meets the standard power supply specifications used by most rail transit systems; the function of the pantograph (Pantogragh) is to receive power from the contact network, and the vacuum circuit breaker is used to control the on and off of the power supply; the current transmission part is regarded as consisting of a guide rod and a copper sheet, which simplifies and reflects the main transmission path of the current in the system, helps to focus on the main electromagnetic interference sources and propagation paths, and ignores minor effects; the transformer, converter, and traction motor in the train system are no longer considered separately, and the entire rail transit system is regarded as a gray box, so that the rail transit system model is more focused on the main electromagnetic interference. Through the above simulation settings, a simplified rail transit system model is constructed, which can effectively analyze and predict electromagnetic interference problems that may occur in actual operation.

[0084] S2. Construct tunnel model

[0085] As a special rail transit environment, the closed structure and material properties of tunnels (such as metal or concrete walls) have a significant impact on the propagation of electromagnetic waves. In tunnels, the reflection, refraction and absorption behaviors of electromagnetic waves are completely different from those in open environments. The propagation characteristics of electromagnetic waves in tunnels will affect the quality and reliability of communication signals. Establishing a tunnel model can help predict and solve the problems of signal interference and attenuation, thereby improving the communication efficiency and safety of rail transit.

[0086] The tunnel model is established by Maxwell module, such as Figure 5 As shown. The tunnel model is a special rail transit system model, which belongs to the rail transit system model under complex environment; the length of the tunnel model is set to simulate the electromagnetic field environment of the tunnel. Preferably, the length of the tunnel is about 500m; the whole tunnel is in a straight section, and the tunnel cross-section excavation width is 14.86m and the height is 12.52m. The density of the tunnel steel mesh is adjusted according to demand; only one anchor rod needs to be inserted into the tunnel model, and then it is distributed into a fan-shaped structure through symmetry operations. This modeling method ensures the uniformity and symmetry of the structure over the entire tunnel length; Subtract is used for geometric shearing to form detailed geometric features of the internal structure of the tunnel, which is helpful for further analysis of the electromagnetic field in the tunnel model.

[0087] S3, setting climate conditions for the tunnel model

[0088] When soil is used as a propagation medium for electromagnetic waves, its resistivity determines the attenuation speed and propagation distance of electromagnetic waves. Climate change affects the soil resistivity of the surrounding soil layers, which has a direct impact on the electromagnetic characteristics of the tunnel model. The soil layer parameters around the tunnel model are set according to the climate. The soil resistivity is about 100Ω·m, and the tunnel wall soil layer is considered to have the same properties.

[0089] According to the National Environmental Protection Standard of the People's Republic of China HJ802-2016 "Electrode Method for Determining Soil Conductivity": Soil conductivity is defined as the ability of soil to conduct electric current, which can be characterized by taking soil samples under specific conditions and measuring the conductivity of the soil extract. It is easy to understand that resistivity is a physical quantity that describes the resistance characteristics of an object, and is inversely related to conductivity, as shown below:

[0090] σ=1 / ρ or σ·ρ=1

[0091] Among them, the commonly used unit of conductivity is S·m -1 , the commonly used unit of resistivity is Ω·m, which can be converted through a simple formula.

[0092] In actual engineering, soil resistivity is usually measured. Commonly used methods include coil burial method, self-inductance method or double-loop mutual inductance method, geological determination method, dipole method, etc. The most accurate one is the quadrupole electrical detection method. The test principle and instrument layout method are as follows: Figure 7 shown.

[0093] Figure 7 The instrument shown in the figure is a ground resistance measuring instrument, the commonly used ZC-8 type, with four poles, which should be arranged on the same straight line during measurement, with a distance a between them. The value of a depends on the buried depth of the grounding body, usually about 5m. The depth of the pole driven into the underground part should be less than 0.05 times the distance between two adjacent poles. When arranging the instrument, on the one hand, it should be noted that the connection sequence of the terminal blocks and the poles on the measuring instrument cannot be reversed, that is, the positions of the two P terminals and the C terminal are fixed, so that a closed circuit can be formed and the resistance value can be measured. On the other hand, the general direction of the buried metal objects should be clear in advance. For example, if the underground pipeline is arranged horizontally along the ground, then the arrangement of the grounding rods should be perpendicular to the pipeline, otherwise the metal objects may cause unnecessary interference to the measurement results. According to this measurement method, the resistance value R can be measured, and the soil resistivity ρ can be calculated. 0 , as shown in the following formula:

[0094]

[0095] Where, b is the depth of the buried part of the test electrode. Since b is required to be less than 1 / 20 of a, the size of b can be ignored in the above formula, so the formula is simplified to the following form:

[0096] ρ 0 =2πaR

[0097] Among them, as long as the resistance value is measured, the soil resistivity at that location can be calculated.

[0098] Soil belongs to the natural environment, and the impact of changes in natural climate conditions on soil properties cannot be ignored. For example, in humid areas or rainy seasons, the water content of the soil increases; the temperature of the soil will increase significantly under the scorching sun; the soil salt level in coastal cities is higher than that in inland areas, so the measurement results need to be reasonably corrected.

[0099] Taking into account the changes in soil resistivity under different environments, the correction coefficient of soil resistivity is given. Since the standard field measurement of soil resistivity should be selected in the dry season, or a few days after the weather is clear, the resistivity is close to the upper limit within the range. Therefore, for the soil resistivity measured under different climatic conditions, the correction coefficient should be greater than 1. The seasonal correction coefficients of some soils are listed in Table 1 below.

[0100] Table 1 Seasonal correction coefficients for some soils

[0101]

[0102] in the above table and They are selected when the rainfall is moderate to heavy or slight a few days before the measurement date. The resistivity of the wet soil is close to half of that of the dry soil. The standard soil resistivity ρ is calculated as shown in the following formula:

[0103]

[0104] In the above formula, ρ 0 represents the measured soil resistivity, is the seasonal correction coefficient. It can be seen that the season has a certain influence on soil resistivity, that is, the change of natural environment has an interference effect on the distribution of electromagnetic fields around the rail transit system.

[0105] In summary, when studying the electromagnetic field conditions around the rail transit system, it is necessary to consider the external influence of the complex environment. If the building environment and natural environment can be accurately restored, the electromagnetic field distribution map results will be more accurate.

[0106] Take a large traffic tunnel section in a mountainous area as an example. This section of the tunnel is located in a hilly area with diverse terrain. The maximum burial depth can reach about 378 meters underground. The surrounding clay layer is soft and mixed with sandstone. Chengdu is in the subtropical monsoon climate temperature zone with an average annual temperature of about 16°C and an annual rainfall of about 1000mm, which is relatively abundant. Therefore, the surrounding soil layer parameters are set. Referring to the above analysis, the soil resistivity is about 100Ω·m.

[0107] S4, constructing the bow-cat arc model;

[0108] Pantograph-catenary arc is a common extreme electrical fault in rail transit. When it occurs, it generates high temperature and strong electromagnetic field, which may cause serious interference to surrounding electronic equipment and signal transmission. Building a pantograph-catenary arc model helps to understand and prevent problems that may occur under such extreme conditions.

[0109] The pantograph-catenary arc model is established by the Maxwell module, such as Figure 3 As shown, a longitudinal cross-sectional view of the bow-catenary arc model is selected to analyze a certain moment in the stable combustion process.

[0110] Figure 4 The curves of the arc area, circumference and power of the bow-cat within a cycle are shown. Figure 4 In the schematic diagram of periodic changes shown, a certain moment is selected for analysis. Due to the stable combustion process, the arc center radiates, and the area to circumference ratio can reach about 13.5, so the maximum radial heat source can reach about 6mm. Considering the influence of the high-speed moving airflow of the train, the plane arc diameter of the train is smaller, so the maximum y-direction of the determined arc physical model is 3mm and the minimum is 2mm; considering wear and process technology, the resistivity of the pantograph carbon slide plate is 7-12μΩ / m and the thermal conductivity is 5-7W / (mK), and the thermal conductivity of the wire is 386-413W / (mK).

[0111] Preferably, according to the cause of the arc formation, the model will be more accurate by considering the relevant parameters of the upper conductor and the lower pantograph carbon slide plate. The resistivity of the pantograph carbon slide plate is about 10μΩ / m, the thermal conductivity is 6W / (m·K), the thermal conductivity of the conductor is about 398W / (m·K), and the arc belongs to air breakdown with high temperature in the center, and material properties can be added.

[0112] S5. Set excitation for the pantograph-catenary arc model, and superimpose the excitation result of the pantograph-catenary arc model on the rail transit system model to obtain the surrounding electrostatic field distribution.

[0113] Conduct electromagnetic field simulation of rail transit system, set excitation for the pantograph-catenary arc model, and simulate the impact of arc events on electromagnetic environment in actual operation. The excitation refers to setting a specific voltage or current waveform for the pantograph-catenary arc model to simulate the conditions when an arc event occurs.

[0114] The arc burning process can be divided into several stages, among which the stable burning stage is a period when the arc length and current intensity are relatively stable. In this stage, the heat and light radiation generated by the arc are relatively uniform, and the electrical characteristics of the arc (such as resistance and conductive path) are relatively stable. Therefore, choosing the bow-catenary arc setting excitation in the stable burning stage helps to accurately evaluate the impact of the arc on the surrounding electromagnetic field.

[0115] Content and process:

[0116] 1. Excitation source selection: The excitation source usually applies a specific voltage or current waveform to the arc model to simulate the actual conditions when the arc event occurs. In the stable burning stage, the electrical parameters of the arc tend to be stable, so a stable current or voltage source is set as the excitation.

[0117] 2. Excitation parameter setting: 25kV industrial frequency AC power supply with a center frequency of 50Hz.

[0118] 3. Application of excitation: In the simulation software ANSYS Maxwell, excitation can be achieved by defining boundary conditions or sources. In the pantograph-catenary arc model, excitation is applied to both ends of the arc model to simulate the generation of actual arc.

[0119] The stimulus and simulation results are shown in Figure 8 and Fig. 9 As shown, Figure 8 Under normal circumstances, Fig. 9 This is the distribution cloud map of the electric field in a humid air environment after continuous rainfall. By comparing Figure 8 and Fig. 9 The electric field distribution in the surrounding space shown in the figure shows that in a humid environment, the potentials of the high voltage end, the ground end and their surroundings are significantly increased; in both cases, the maximum electric field intensity reaches 2×10 3 V / m, but the distribution is obviously different, which is related to the influence of the degree of humidity on the relative dielectric constant and bulk conductivity. When the humidity is 30%, the relative dielectric constant is set to 24 and the conductivity is about 0.002S / m.

[0120] The excitation results of the pantograph arc model are superimposed on the entire rail transit system model, that is, the electromagnetic effect generated by the arc is integrated into the electromagnetic environment of the system. Through the superposition operation, the changes in the electrostatic field caused by the arc event in the entire rail system are obtained.

[0121] The superposition principle in electromagnetism is applied. The superposition principle states that in a linear system, when multiple independent sources act on the system together, the total response is equal to the algebraic sum of the responses of each source when it acts alone.

[0122] The superposition process can be expressed by mathematical formulas. Assume that there is an arc source in the system that generates an electric field of E arc , and the system background electric field (i.e., the electric field without arc influence) is E bg , then the total electric field E total It can be calculated by the superposition principle as follows:

[0123] E total =E arc +E bg

[0124] For magnetic fields, a similar superposition formula applies. arc is the magnetic field generated by the arc source, and B bg is the background magnetic field, then the total magnetic field B total for:

[0125] B total =B arc +B bg

[0126] In the actual simulation of ANSYS Maxwell, the software automatically handles complex mathematical operations and integrations, and outputs the superimposed electromagnetic field distribution. This superposition is performed at the numerical level and is achieved through the algorithm inside the software.

[0127] Those skilled in the art will appreciate that the embodiments of the present invention may be provided as methods, systems or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware.

[0128] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described 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.

[0129] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. An electromagnetic simulation method for rail transit system under complex environment and extreme working conditions, characterized in that: The following steps are involved: S1. Construct rail transit system model; S2. constructing a tunnel model, wherein the tunnel model is a sub-model of the rail transit system model; obtaining an electromagnetic field distribution simulation result of the tunnel model by setting different climate conditions for the tunnel model; S3. Construct a pantograph-catenary arc model, wherein the pantograph-catenary arc model interacts with the rail transit system model; obtain an excitation result by setting an excitation on the pantograph-catenary arc model, and superimpose the excitation result on the rail transit system model to obtain the total electromagnetic field distribution after superposition.

2. The electromagnetic simulation method of a rail transit system under complex environment and extreme working conditions according to claim 1 is characterized in that: The rail transit system model includes a contact network, a pantograph, a vacuum circuit breaker and a current transmission part; wherein: The overhead line is simulated as a 25kV industrial frequency AC power source with a center frequency of 50Hz, which serves as the main power supply source for the rail transit system; The pantograph is configured to receive power from the overhead line; The vacuum circuit breaker is used to control the power on and off of the rail transit system model; The current transmission part includes a guide rod and a copper sheet, which is used to simulate the main transmission path of the current in the rail transit system and provide the electrical connection required for electromagnetic simulation.

3. The electromagnetic simulation method of a rail transit system under complex environment and extreme working conditions according to claim 2 is characterized in that: The tunnel model includes: 1) Set the length of the tunnel to L to simulate the electromagnetic field environment of the tunnel; 2) The tunnel model also includes a steel mesh, and the density of the steel mesh is adjusted according to simulation requirements; 3) inserting anchor rods into the tunnel model, and distributing the tunnel model into a fan-shaped structure through symmetric operations; 4) Forming detailed geometric features inside the tunnel model through geometric shearing.

4. The electromagnetic simulation method for rail transit system under complex environment and extreme working conditions according to claim 3 is characterized in that: In step S2, different climate conditions are set for the tunnel model by setting soil parameters around the tunnel model to simulate the electromagnetic field distribution under different climate conditions.

5. The electromagnetic simulation method for rail transit system under complex environment and extreme working conditions according to claim 4 is characterized in that: Setting soil parameters involves the following steps: 1) Obtain soil resistance value R by quadrupole electrical probing method; 2) Calculate the soil resistivity ρ0 as ρ0 = 2πaR Where a is the interval between ground rods, and R is the measured soil resistance value; 3) using a seasonal correction factor φ in the tunnel model, the seasonal correction factor adjusting the soil resistivity according to the climatic conditions before the measurement date; the climatic conditions include rainfall and soil moisture; 4) Calculate the standard soil resistivity based on the soil resistivity ρ0 and the seasonal correction factor φ 6. The electromagnetic simulation method for rail transit system under complex environment and extreme working conditions according to claim 5 is characterized in that: The rail transit system model includes a power supply, a contact network, a pantograph, a vacuum circuit breaker and a current transmission part; the contact network is configured as a 25kV industrial frequency AC power supply with a center frequency of 50HZ; the pantograph is configured to receive power from the contact network; the vacuum circuit breaker is used to control the on and off of the power supply; the current transmission part is composed of a guide rod and a copper sheet.

7. The electromagnetic simulation method for rail transit system under complex environment and extreme working conditions according to claim 6 is characterized in that: The bow-catenary arc model simulates the impact of arc events on the surrounding electromagnetic environment through dynamic simulation of heat conduction and current intensity changes; further, the bow-catenary arc model is configured to perform instantaneous analysis on the arc center during the stable burning stage of the arc.

8. The electromagnetic simulation method for rail transit system under complex environment and extreme working conditions according to claim 7 is characterized in that: The pantograph-catenary arc model also includes a conductor and a pantograph carbon slide plate, wherein the thermal conductivity of the conductor is k1, the resistivity of the pantograph carbon slide plate is ρ1 and the thermal conductivity is k2; the maximum diameter of the central radiation heat source in the stable combustion stage of the arc is D1, and the plane arc diameter varies between d1 and d2.

9. The electromagnetic simulation method for rail transit system under complex environment and extreme working conditions according to claim 8 is characterized in that: The thermal conductivity of the wire is about 386-413W / (m·K), the resistivity of the pantograph carbon slide plate is about 7-12μΩ / m and the thermal conductivity is 5-7W / (m·K); the maximum diameter of the central radiation heat source in the stable combustion stage of the arc is 6mm, and the plane arc diameter varies between 3mm and 2mm.

10. The electromagnetic simulation method of rail transit system under complex environment and extreme working conditions according to claim 9, characterized in that: Setting excitation for the pantograph-catenary arc model comprises the following steps: 1) Select an excitation source, which is a specific voltage or current waveform; the excitation parameters are an industrial frequency AC power supply with a center frequency of 50 Hz and a voltage of 25 kV; 2) using the excitation source to set excitation for the pantograph-catenary arc model and obtain the excitation result; the excitation is realized at both ends of the pantograph-catenary arc model by defining boundary conditions or sources to simulate the generation of arc; 3) Applying the excitation result of the pantograph-catenary arc model to the rail transit system model through the superposition principle; wherein, during the superposition process, the total distribution of the electric field and the magnetic field is expressed by the formula: AND total =And arc +E bg B total =B arc +B bg To calculate; where E arc and B arc Respectively represent the electric field and magnetic field generated by the excitation source; E bg and B bg represent the electric field and magnetic field of the rail transit system model respectively; E total and B total Represent the total electric field and total magnetic field after superposition, respectively.

Images