Rail transit stray current model acquisition method considering train traction characteristics

Abstract

The application discloses a kind of track traffic stray current model acquisition methods considering train traction characteristics, at least including the following steps: step S10, the specific spatial distribution information of train track and the information of track cross section are collected, train track is gridded, and the basic grounding model of track traffic is established;Step S11, coating is added to the surface of grounding conductor, and the transition resistance is equivalent to the conductor coating, to reflect the leakage characteristic of track with coating model;Step S12, according to the train traction operating characteristics, all operating positions and traction current conditions are traversed, and the stray current distribution is calculated using node voltage method, so as to form the stray current distribution curve of the whole track section. According to the present application, the stray current distribution curve of the whole track section can be quickly and accurately obtained.

Description

Technical Field

[0001] This invention relates to the field of stray current monitoring technology, and in particular to a method for obtaining a stray current model for rail transit that takes into account train traction characteristics. Background Technology

[0002] Urban rail transit traction systems are powered by either DC or AC, with DC being the dominant system in my country. The traction power supply system provides electricity for train operation and lighting / air conditioning equipment. In most cases, DC-powered urban rail transit systems rely on the tracks as a return path for the supplied current. Ideally, the return rail of a rail transit system is strictly insulated from the ground. However, in reality, leakage current inevitably occurs in the return rail. The traction current flows from the rails into the surrounding soil, then back to the running rails, and finally back to the traction substation. This current leaking into the ground is called stray current.

[0003] Stray currents intruding into AC power systems can cause corrosion of the grounding grid. Furthermore, stray currents can cause large power transformers operating on ground to be in a DC biased magnetic state. This leads to severe transformer vibration, increased noise, abnormal temperature rise, and even localized hotspots and mechanical loosening, seriously threatening the safe operation of urban power supply systems and causing noise pollution. Monitoring data indicates that such phenomena have occurred in many parts of my country. With the increasing networking and high-density development of DC subway systems, subway loads are significantly increasing, and the ever-growing stray currents pose new challenges to urban power grids.

[0004] Under the continuous operation of rail transit systems throughout the year, the track-to-ground insulation deteriorates or even fails due to dirt accumulation, corrosion, and wear, greatly exacerbating stray current leakage. However, the magnitude, location, and flow direction of stray currents in rail transit are unpredictable in both time and space. Therefore, establishing a stray current simulation model is currently no easy task.

[0005] For theoretical models of stray current distribution in rail transit, both domestic and international research mainly employs circuit or electromagnetic field theories for modeling, followed by solutions using tools such as MATLAB, CDEGS, and PSCAD. Cai Li and Zhu Feng et al. primarily analyzed the influence of rail-to-ground transition resistance on the stray current distribution characteristics, using CDEGS software to calculate the magnitude and distribution of stray currents. Furthermore, the introduction of the power system grounding software CDEGS has effectively ensured the accuracy of the calculations. However, a crucial characteristic of stray currents is their close correlation with train traction characteristics, and current research is limited to circuit models. Due to limitations in workload and simulation methods, it is currently impossible to model stray currents within CDEGS. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a method for obtaining a stray current model of rail transit that takes into account the traction characteristics of trains, which can quickly and accurately obtain the stray current distribution curve of the entire track section.

[0007] To address the aforementioned technical problems, as one aspect of this invention, a method for obtaining a stray current model for rail transit considering train traction characteristics is provided, comprising at least the following steps:

[0008] Step S10: Collect specific spatial distribution information and track cross-sectional information of the train track, grid the train track, and establish a basic grounding model of rail transit;

[0009] Step S11: Add a coating to the surface of the grounding conductor, and treat the transition resistance as equivalent to the conductor coating, so as to represent the leakage characteristics of the track with the coating model.

[0010] Step S12: Based on the train's traction operation characteristics, traverse all operating positions and traction current conditions, and use the nodal voltage method to calculate the stray current distribution, thereby forming the stray current distribution curve for the entire track section.

[0011] Preferably, step S10 further includes:

[0012] Step S100: Collect specific spatial distribution information of train tracks and information on track cross sections, including: collecting information on the geographical distribution of tracks over a wide area, the structure and dimensions of track cross sections, and the arrangement of metal conductors;

[0013] Step S101: Divide the long track of the train into a series of subdivided conductor branches and nodes according to the grounding modeling processing method;

[0014] Step S102: Based on the formation relationship between nodes and branches and the direction of stray current flow in the rail transit network, obtain the node voltage column vector V. N and branch current column vector I B According to the branch voltage V B Correlation matrix A with node voltage, branch voltage drop D B The correlation matrix B between the node voltage V and the branch voltage V is used to obtain the branch voltage V. B And branch voltage drop D B ;

[0015] Step S103: Obtain the mutual conductance matrix G of the track branch. b The conduction impedance matrix Y of the track b .

[0016] Preferably, step S11 further includes:

[0017] Step S110: Apply a coating to the surface of the grounding conductor to simulate the transition resistance R per unit length of the track. D Calculate the coating resistivity ρ eq ;

[0018] Step S111, based on the coating resistivity ρ eq Modify the mutual conductance matrix G of the track branch b .

[0019] Preferably, step S12 further includes:

[0020] S120, based on the full path model of traction current in rail transit, the nodal injection current column vector F is defined using the nodal voltage method;

[0021] S121, obtain the formula for calculating the current column vector F;

[0022] S122, based on the train traction operation characteristics, traverse all operating positions and traction load currents, and calculate the stray current at each position according to the calculation formula of the current column vector F, thereby forming the stray current distribution curve of the entire track section.

[0023] Preferably, step S102 includes:

[0024] Define the node voltage column vector V N and branch current column vector I B :

[0025]

[0026]

[0027] Where V1 to V6 are the voltages of each node, and I1 to I4 are the currents of each branch;

[0028] Let A and B be the branch voltages V. B Correlation matrix with node voltage, branch voltage drop D B The correlation matrix between the node voltage V and the node voltage V is:

[0029]

[0030]

[0031] Specifically, for the correlation matrix B between branch voltage and node voltage, the element at the node position corresponding to the branch number in the row should be 0.5, and the element at the node position corresponding to other unrelated nodes in the same row should be 0. For the correlation matrix A between branch voltage drop and node voltage, the element at the node position corresponding to the branch number in the row should be 1, and the element at the node position corresponding to the current flow direction between the branch and node should be -1, and the element at the node position corresponding to the current flow direction should be 0.

[0032] Preferably, step S103 further includes:

[0033] The mutual conductance matrix G of the track branch b M is the mutual resistance matrix R The reverse formation:

[0034]

[0035] Among them, M R The specific location of the track section branch and the Green's function model of the soil are related, and its element calculation expression is as follows:

[0036]

[0037]

[0038] M R (i,j)=0,1≤i≤2,1≤j≤4 (8)

[0039] In the formula, dB is a micro-segment on branch B, dB″ represents the geometric center of the cross section of branch dB, p function is the spatial position function, and g is the Green function; Equation (6) describes the electric field coupling between two branches, and Equation (7) describes the electric field coupling of the branch itself.

[0040] The expressions for the Green's function in equations (6) and (7) are as follows:

[0041]

[0042] In the formula, ρ is the equivalent earth resistivity, the dist function is the function for calculating the distance between two points, and dB′ j Indicates dB j Regarding the mirror image of the ground;

[0043] Y b The diagonal elements are not zero, while the other elements are zero, depending on the material parameters and length of the track branch. The diagonal elements are obtained by the following formula (10):

[0044]

[0045] In the formula, S is the cross-sectional area of ​​the branch conductor, L is the length of the conductor path, and ρ c ρ is the resistivity of the conductor material.

[0046] Preferably, step S110 further includes:

[0047] The coating resistivity ρ is calculated according to the following formula (11). eq :

[0048]

[0049] In the formula, R D The design or measured value of the transition resistance measurement for rail transit is given, where r′ is the preset outer diameter of the conductor and r is the inner diameter of the conductor.

[0050] Step S111 further includes:

[0051] Substituting equation (11) into the stray current grounding calculation model, equation (7) is modified to the following form:

[0052]

[0053] In the formula, dB′″ represents a branch whose dB extends from the inner diameter r to the outer diameter r′.

[0054] Preferably, S120 further includes:

[0055] Based on the full path model of traction current in rail transit, and using the nodal voltage method, the column vector F of nodal injection current is defined as follows:

[0056]

[0057] Wherein, I1 is the traction current between the first traction substation and the pantograph in the overhead contact system; I2 is the traction current between the second traction substation and the pantograph in the overhead contact system; I g1 I represents the current flowing between the train and the first traction substation along the rails. g2 This refers to the current flowing between the train and the second traction substation along the rails.

[0058] Preferably, step S121 further includes:

[0059] The following formula (17) is used as the formula for calculating the current column vector F:

[0060] F = (B T G b B+A T Y b A)V N (17)

[0061] Among them, AT and B T These are the transposes of matrix A and matrix B, respectively.

[0062] Preferably, step S122 further includes:

[0063] Based on the correspondence between train operation characteristics and traction current, starting from the moment the train starts running, the position of the train and the magnitude of the traction current are dynamically refreshed at fixed intervals to obtain the position of the corresponding network node, as well as the magnitudes of currents I1 and I2, and the stray current distribution corresponding to this position is calculated using formula (17).

[0064] Plot the stray current density curves along the line from the start of the train's operation to its final stop on the same graph to form the track stray current envelope during the train's journey from the starting point to the end point.

[0065] Implementing the embodiments of the present invention has the following beneficial effects:

[0066] This invention proposes a method for obtaining a stray current model for rail transit that considers train traction characteristics. By recognizing the close correlation between stray current and the traction operation characteristics of rail transit trains—that is, both the train's position and traction current change over time—a stray current grounding analysis model considering traction characteristics is used. The nodal voltage method of grounding analysis is employed to solve for the stray current distribution at the dynamic current injection point. Then, based on the train's traction operation characteristics, all operating conditions are traversed to form the stray current distribution curve for the entire track section. This invention helps to accurately assess the leakage level of stray current and assists the rail transit industry and urban power grid systems in jointly addressing the adverse effects of stray current. Attached Figure Description

[0067] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, obtaining other drawings based on these drawings without creative effort still falls within the scope of the present invention.

[0068] Figure 1 This is a schematic diagram of the main flow of an embodiment of a method for obtaining a stray current model of rail transit considering train traction characteristics provided by the present invention.

[0069] Figure 2 This is a schematic diagram of the node branches and traction current flow direction of the gridded rail transit system involved in the present invention.

[0070] Figure 3 This is a schematic diagram of the entire traction current path model for rail transit involved in this invention;

[0071] Figure 4 This is a schematic diagram of the speed, locomotive output, and power curves of the traction process of rail transit involved in this invention;

[0072] Figure 5 for Figure 4 A simplified diagram illustrating the relationship between the operating characteristics of a medium-speed train and its traction current;

[0073] Figure 6 This is a schematic diagram of the geographical distribution of rail transit in one embodiment of the present invention;

[0074] Figure 7 In response to Figure 6 The track stray current envelope during a train's journey from the starting point to the end point is obtained by calculating a transition resistance.

[0075] Figure 8 In response to Figure 6 The envelope of stray track currents during a train's journey from the starting point to the end point is calculated using another transition resistance. Detailed Implementation

[0076] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings.

[0077] Understandably, from a broad geographical perspective, rail transit systems can be viewed as a vast underground network connecting cities. Based on typical rail transit design parameters, the underground track sections are generally located 15m to 30m underground. The cross-sectional structure of the track can be considered as a hollow metal grid frame enclosed by a tunnel boring machine (TBM), composed of a large amount of steel reinforcement, drainage netting, and the track itself.

[0078] Rail transit systems supply power to trains in two ways: single-ended and double-ended. When a train travels to the power supply section between two traction substations, the ideal path for the traction current is through the overhead contact line, the running train, and the rails. The stray current escapes through weak points in the rail insulation, leaking into the nearby ground, and then returning to the neutral / grounding point of the traction substation via the ground and other paths (buried metal, urban power grid, etc.). The theoretical model of stray current distribution can be analyzed using power system grounding theory.

[0079] During different traction phases such as starting, coasting, and deceleration, the traction current exhibits dynamic changes due to variations in locomotive output. Since stray current originates from the train's traction current, its distribution is a dynamic response process. This manifests as changes in the magnitude and direction of the stray current as the train's traction characteristics change, and as leakage changes occur depending on the train's position.

[0080] like Figure 1 The diagram illustrates the main flow of an embodiment of the method for obtaining a stray current model of rail transit considering train traction characteristics provided by the present invention; combined with... Figures 2 to 5 As shown, in this embodiment, the method includes at least the following steps:

[0081] Step S10: Collect specific spatial distribution information and track cross-sectional information of the train track, grid the train track, and establish a basic grounding model of rail transit;

[0082] In a specific example, step S10 further includes:

[0083] Step S100: Collect specific spatial distribution information of train tracks and information on track cross sections, including: collecting information on the geographical distribution of tracks over a wide area, the structure and dimensions of track cross sections, and the arrangement of metal conductors;

[0084] Step S101: The long track of the train is divided into a series of subdivided conductor branches and nodes according to the grounding modeling method; such as... Figure 2 The diagram illustrates a gridded node branch and traction current flow of a rail transit system according to the present invention. The power supply nodes from the traction substation to the overhead contact line are N1 and N3; the power supply node from the overhead contact line to the train is N2; the rail nodes connected to the return line of the traction substation are N4 and N6; and the node connecting the train to the rail is N5. Under the above node configuration, four stray current branches are identified: branch B1, connecting nodes N1 and N2; branch B2, connecting nodes N2 and N3; branch B3, connecting nodes N4 and N5; and branch B4, connecting nodes N5 and N6.

[0085] Step S102: Based on the formation relationship between nodes and branches and the direction of stray current flow in the rail transit network, obtain the node voltage column vector V. N and branch current column vector I B According to the branch voltage V B Correlation matrix A with node voltage, branch voltage drop D B The correlation matrix B between the node voltage V and the branch voltage V is used to obtain the branch voltage V. B And branch voltage drop D B ;

[0086] More specifically, step S102 includes:

[0087] Define the node voltage column vector V N and branch current column vector I B :

[0088]

[0089]

[0090] Where V1 to V6 are the voltages of each node, and I1 to I4 are the currents of each branch;

[0091] Let A and B be the branch voltages V. B Correlation matrix with node voltage, branch voltage drop D B The correlation matrix between the node voltage V and the node voltage V is:

[0092]

[0093]

[0094] Specifically, for the correlation matrix B between branch voltage and node voltage, the element at the node position corresponding to the branch number in the row should be 0.5, and the element at the node position corresponding to other unrelated nodes in the same row should be 0. For the correlation matrix A between branch voltage drop and node voltage, the element at the node position corresponding to the branch number in the row should be 1, and the element at the node position corresponding to the current flow direction between the branch and node should be -1, and the element at the node position corresponding to the current flow direction should be 0.

[0095] Step S103, after defining the nodes and branches, and defining the node and branch currents, voltages, and correlation matrix AB, it is also necessary to obtain the mutual conductance matrix G of the track branches. b The conduction impedance matrix Y of the track b .

[0096] More specifically, step S103 further includes:

[0097] The mutual conductance matrix G of the track branch b M is the mutual resistance matrix R The reverse formation:

[0098]

[0099] Among them, M R The specific location of the track section branch and the Green's function model of the soil are related, and its element calculation expression is as follows:

[0100]

[0101]

[0102] M R (i,j)=0,1≤i≤2,1≤j≤4 (8)

[0103] In the formula, dB is a micro-segment on branch B, dB″ represents the geometric center of the cross section of branch dB, p function is the spatial position function, and g is the Green function; Equation (6) describes the electric field coupling between two branches, and Equation (7) describes the electric field coupling of the branch itself.

[0104] The expressions for the Green's function in equations (6) and (7) are as follows:

[0105]

[0106] In the formula, ρ is the equivalent earth resistivity, the dist function is the function for calculating the distance between two points, and dB′ j Indicates dB j Regarding the mirror image of the ground;

[0107] The conduction impedance matrix Y of the track b The diagonal elements are not zero, while the other elements are zero, depending on the material parameters and length of the track branch. The diagonal elements are obtained by the following formula (10):

[0108]

[0109] In the formula, S is the cross-sectional area of ​​the branch conductor, and L is the length of the conductor path. c ρ is the resistivity of the conductor material.

[0110] Step S11: Add a coating to the surface of the grounding conductor, treating the transition resistance as equivalent to the conductor coating, and use the coating model to represent the leakage characteristics of the track. It is understandable that the biggest difference between rail transit tracks and ordinary grounding conductors is their poor conductivity to the earth, specifically manifested in the transition resistance R per unit length of track. D This refers to the parallel resistance per unit length of track to the ground, and the regulations require the parallel resistance value to be 15Ω / km.

[0111] In a specific example, step S11 further includes:

[0112] Step S110: Apply a coating to the surface of the grounding conductor to simulate the transition resistance R per unit length of the track. D Calculate the coating resistivity ρ eq Specifically, the coating resistivity ρ is calculated according to the following formula (11). eq :

[0113]

[0114] In the formula, R D The design or measured value of the transition resistance measurement for rail transit is given, where r′ is the preset outer diameter of the conductor and r is the inner diameter of the conductor.

[0115] Step S111, based on the coating resistivity ρ eq Modify the mutual conductance matrix G of the track branch b .

[0116] More specifically, step S111 further includes:

[0117] Substituting equation (11) into the stray current grounding calculation model, equation (7) is modified to the following form:

[0118]

[0119] In the formula, dB′″ represents a branch whose dB extends from the inner diameter r to the outer diameter r′.

[0120] Step S12: Based on the train's traction operation characteristics, traverse all operating positions and traction current conditions, and use the nodal voltage method to calculate the stray current distribution, thereby forming the stray current distribution curve for the entire track section.

[0121] Due to the presence of the coating resistance, the self-resistance of the grounding branch will be increased by the coating resistance (equivalent to DC resistance). As for the conduction impedance, since the longitudinal conduction current does not pass through the coating, formula (10) does not need to be modified.

[0122] In a specific example, step S12 further includes:

[0123] S120, based on the full path model of traction current in rail transit, the nodal voltage method is used to define the nodal injection current column vector F; such as Figure 3 As shown, a schematic diagram of the entire traction current path model for rail transit involved in this invention is illustrated; based on Figure 3 The model can be defined as follows: the column vector F of node injection currents can be defined as follows:

[0124]

[0125] Wherein, I1 is the traction current between the first traction substation and the pantograph in the overhead contact system; I2 is the traction current between the second traction substation and the pantograph in the overhead contact system; I g1 I represents the current flowing between the train and the first traction substation along the rails. g2 This refers to the current flowing between the train and the second traction substation along the rails.

[0126] S121, obtain the formula for calculating the current column vector F;

[0127] The stray current from track leakage is obtained by solving a generalized grounding model. From the current conservation at the nodes, we have...

[0128] F = F1 + F2 (14)

[0129] In the formula, F1 and F2 are the node current dissipation current and conduction current, respectively, and the specific calculation formula is as follows:

[0130] F1 = B T G b BV N (15)

[0131] F2 = A T Y b AV N (16)

[0132] Therefore, the following formula (17) can be used as the formula for calculating the current column vector F:

[0133] F = (B T G b B+A T Y b A)V N (17)

[0134] Among them, A T and B T These are the transposes of matrix A and matrix B, respectively.

[0135] It is understandable that in equation (14), the node excitation current F is related to the location of the traction substation and the traction characteristics of the train. By changing the train's running position and the specific input traction current (I1 and I2), equations (5), (10) and (13) can be updated, and the corresponding stray current distribution can be solved using equation (17).

[0136] S122, based on the train traction operation characteristics, traverse all operating positions and traction load currents, and calculate the stray current at each position according to the calculation formula of the current column vector F, thereby forming the stray current distribution curve of the entire track section.

[0137] Figure 4 A schematic diagram showing the speed, locomotive output, and power curves obtained from the traction process of the traction system within the subway system involved in this invention is presented. Through analysis of... Figure 4 The traction system operation process shown can be established Figure 5 A simplified diagram showing the time relationship between traction current and train speed.

[0138] More specifically, step S122 further includes:

[0139] Based on the correlation between train operating characteristics and traction current, starting from the moment the train begins operation, the train's position and traction current magnitude are dynamically refreshed at fixed intervals (e.g., every 1 second) to obtain the corresponding network node information. Figure 2 The positions of nodes N2 and N5 in the diagram, and Figure 3 The magnitudes of the currents I1 and I2 are determined, and the stray current distribution at this location is calculated using formula (17).

[0140] Plot the stray current density curves along the line from the start of the train's operation to its final stop on the same graph to form the track stray current envelope during the train's journey from the starting point to the end point.

[0141] Understandably, this invention employs a method for obtaining a stray current model for rail transit that considers train traction characteristics. First, the track is meshed to solve the modeling problem of train position changes; that is, the equivalent train position is represented by the corresponding track mesh. Second, the transition resistance is equivalent to a conductor coating, using the coating model to represent the track's leakage characteristics. Finally, based on the train traction characteristics, the stray current distribution is calculated using the nodal voltage method across all operating positions and traction current conditions, thus forming the stray current distribution curve for the entire track section. This invention abandons the traditional simplified dynamic stray current-circuit model analysis technique and uses a more accurate power system grounding theory model for larger-scale dynamic grounding calculations, effectively simulating the dynamic stray current distribution considering train traction characteristics.

[0142] Taking Metro Line 1 in a certain city as an example, the distribution of stray currents on the track can be calculated. For example... Figure 6 The map shown depicts the geographical distribution of Metro Line 1. Points on the map represent specific metro stations, and line segments represent rail transit tracks.

[0143] Figure 7 In response to Figure 6 The track stray current envelope during a train's journey from the starting point to the end point is obtained by calculating a transition resistance.

[0144] In the diagram, when the transition resistance of Metro Line 1 is 15Ω / km, the stray current density calculated using the method of this invention is approximately 13mA / m. The maximum leakage stray current occurs at the 8km mark. When the train starts and accelerates, it draws DC current from the traction network for acceleration, and the motor power increases linearly, resulting in current values ​​of several thousand amperes. This weakens the insulation near the track, causing significant stray current leakage. Therefore, maintenance of the initial distance section of the metro line should be strengthened to minimize stray current leakage to the ground. It can be seen that the train in the traction power supply system can be considered a moving load. Since the station spacing on the line is often within several kilometers, train acceleration and deceleration are frequent, and the traction current rises or falls regularly with train operation. During the starting and braking phases, the power changes drastically, and the traction current exhibits high time-varying characteristics.

[0145] If the transition resistance is set to 1 Ω / km, the stray current density calculated using the method of this invention reaches approximately 140 mA / m. Its specific envelope is as follows: Figure 8 As shown.

[0146] Similarly, the transition resistance can be set to 3Ω / km, 5Ω / km, 7Ω / km, 10Ω / km, etc., and the envelope obtained by the method of this invention is... Figure 7 and Figure 8 Similarly, this will not be elaborated upon here.

[0147] Implementing the embodiments of the present invention has the following beneficial effects:

[0148] This invention proposes a method for obtaining a stray current model for rail transit that considers train traction characteristics. By recognizing the close correlation between stray current and the traction operation characteristics of rail transit trains—that is, both the train's position and traction current change over time—a stray current grounding analysis model considering traction characteristics is used. The nodal voltage method of grounding analysis is employed to solve for the stray current distribution at the dynamic current injection point. Then, based on the train's traction operation characteristics, all operating conditions are traversed to form the stray current distribution curve for the entire track section. This invention helps to accurately assess the leakage level of stray current and assists the rail transit industry and urban power grid systems in jointly addressing the adverse effects of stray current.

[0149] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, apparatus, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0150] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0151] The above description is merely a preferred embodiment of the present invention and should not be construed as limiting the scope of the invention. Therefore, any equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. A method for obtaining a model of stray current in rail transit considering train traction characteristics, characterized in that, It should include at least the following steps: Step S10: Collect specific spatial distribution information and track cross-sectional information of the train track, grid the train track, and establish a basic grounding model of rail transit; Step S11: Add a coating to the surface of the grounding conductor, and treat the transition resistance as equivalent to the conductor coating, so as to represent the leakage characteristics of the track with the coating model. Step S12: Based on the train traction operation characteristics, traverse all operating positions and traction current conditions, and use the nodal voltage method to calculate the stray current distribution, thereby forming the stray current distribution curve of the entire track section. Step S10 further includes: Step S100: Collect specific spatial distribution information of train tracks and information on track cross sections, including: collecting information on the geographical distribution of tracks over a wide area, the structure and dimensions of track cross sections, and the arrangement of metal conductors; Step S101: Divide the long track of the train into a series of subdivided conductor branches and nodes according to the grounding modeling processing method; Step S102, according to the formation relationship of nodes and branches, the stray current flow direction of the rail transit network, obtain the node voltage column vector V N And branch current column vector I B , according to the association matrix A between branch voltage V B And node voltage, the association matrix B between branch pressure drop D B And node voltage, obtain branch voltage V B And branch pressure drop D B ; Step S103, obtaining the mutual conductance matrix G of the track branch b and the on-resistance matrix Y of the track b ; Step S11 further includes: Step S110, coating the surface of the ground conductor, simulating the transition resistance R of the unit length track D , calculating the resistivity p of the coating eq ; Step S111, according to the coating resistivity p eq Modifying the mutual conductance matrix G of the track branches b ; Step S12 further includes: S120, based on the full path model of traction current in rail transit, the nodal injection current column vector F is defined using the nodal voltage method; S121, obtain the formula for calculating the current column vector F; S122, based on the train traction operation characteristics, traverse all operating positions and traction load currents, and calculate the stray current at each position according to the calculation formula of the current column vector F, thereby forming the stray current distribution curve of the entire track section.

2. The method as described in claim 1, characterized in that, Step S102 includes: Definition of the node voltage column vector V N and the branch current column vector I B : （1） （2） Where V1 to V6 are the voltages of each node, and I1 to I4 are the currents of each branch; Let A and B be the branch voltages V B the incidence matrix of the network, the branch voltage drops D B the incidence matrix between the node voltages, and have （3） （4） Specifically, for the correlation matrix B between branch voltage and node voltage, the element at the node position corresponding to the branch number in the row should be 0.5, and the element at the node position corresponding to other unrelated nodes in the same row should be 0. For the correlation matrix A between branch voltage drop and node voltage, the element at the node position corresponding to the branch number in the row should be 1, and the element at the node position corresponding to the current flow direction between the branch and node should be -1, and the element at the node position corresponding to the current flow direction should be 0.

3. The method of claim 2, wherein, Step S103 further includes: The mutual impedance matrix G of the track branches b is the inverse of the mutual resistance matrix M R : （5） where M R The elements of the Green's function model associated with the specific location of the track segment branch and the soil are calculated by the expression: （6） （7） （8） In the formula, dB is the micro-segment on branch B, dB The geometric center of the cross section of the branch dB is represented by p function, which is the spatial position function, and g is the Green's function; Equation (6) describes the electric field coupling between two branches, and Equation (7) describes the electric field coupling of the branch itself. The expressions for the Green's function in equations (6) and (7) are as follows: （9） In the formula, For the equivalent earth resistivity, the dist function is a function to calculate the distance between two points, in dB. j Indicates dB j Regarding the mirror image of the ground; The on-resistance matrix Y of the track b The diagonal elements are not zero and the other elements are zero, which are related to the material parameters and length of the track branches. The diagonal elements are obtained by the following formula (10): （10） In the formula, S is the cross-sectional area of ​​the branch conductor, and L is the length of the conductor path. c ρ is the resistivity of the conductor material.

4. The method of claim 3, wherein, in: Step S110 further includes: The coating resistivity p is calculated according to the following formula (11) eq : （11） In the formula, R D For the design or measured value of the transition resistance of rail transit, r Let r be the predetermined outer diameter of the conductor, and r be the inner diameter of the conductor. Step S111 further includes: Substituting equation (11) into the stray current grounding calculation model, equation (7) is modified to the following form: （12） In the formula, dB This indicates that the branch dB expands from the inner diameter r to the outer diameter r. A side road.

5. The method of claim 4, wherein, S120 further includes: Based on the full path model of traction current in rail transit, and using the nodal voltage method, the column vector F of nodal injection current is defined as follows: （13） wherein I1 is the traction current between the first traction substation and the pantograph in the catenary; I2 is the traction current between the second traction substation and the pantograph in the catenary; I g1 is the current between the train in the rail and the first traction substation; I g2 is the current between the train in the rail and the second traction substation.

6. The method as described in claim 5, characterized in that, Step S121 further includes: The following formula (17) is used as the formula for calculating the current column vector F: （17） where A T and B T are the transpose of matrix A and matrix B, respectively.

7. The method as described in claim 6, characterized in that, Step S122 further includes: Based on the correspondence between train operation characteristics and traction current, starting from the moment the train starts running, the position of the train and the magnitude of the traction current are dynamically refreshed at fixed intervals to obtain the position of the corresponding network node, as well as the magnitudes of currents I1 and I2, and the stray current distribution corresponding to this position is calculated using formula (17). Plot the stray current density curves along the line from the start of the train's operation to its final stop on the same graph to form the track stray current envelope during the train's journey from the starting point to the end point.

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