Scale model for simulating diffusion of stray current

Abstract

The scaling model for simulating the diffusion of the stray current comprises a soil simulation layer, a first soil layer and a second soil layer which are sequentially laminated from top to bottom, and the resistivity of the first soil layer is different from that of the second soil layer; a blocky medium for simulating lakes and oceans is embedded in the first soil layer; the rail transit line model is located on the first soil layer of the soil simulation layer and is of a columnar structure, the inner layer is made of a high insulating material for simulating air, the outer layer is an agar layer for simulating a pouring tunnel structure, and carbon rods for simulating a steel rail and a drainage net are embedded in the agar layer; the ground potential measuring module comprises a ground potential measuring point located on the first soil layer and a ground potential measuring instrument connected to the ground potential measuring point; and the power supply analog circuit comprises a power supply and a switch, and the power supply is electrically connected with the carbon rod through the switch. And the accuracy of the urban rail transit direct current interference calculated by the analysis mode is verified by using the scaling model.

Description

Technical Field

[0001] The utility model relates to the field of stray current generated by urban rail transit, in particular to a scaled-down model for simulating the diffusion of stray current. Background Art

[0002] Urban rail transit in my country is generally powered by 750V or 1500V DC. In the rail return system, urban rail transit trains draw current from the contact network or the third rail through the pantograph, and the current returns from the rail to the negative pole of the traction power supply station. However, due to the limitations of operating environment, technical conditions and other factors, the rail and the roadbed structure are often not completely insulated. When the current flows in the rail, it will leak to the ground, interfering with the surrounding buried pipelines and power systems.

[0003] At present, the main methods for evaluating stray currents generated by DC traction power supply systems in urban rail transit include analytical calculation, simulation analysis, and field measurement. The field measurement method is only applicable to existing lines. At the same time, the DC interference measured on site may be affected by other lines and surrounding grounding systems, and cannot accurately reflect the DC interference of the current line. The analytical calculation method can be used to calculate the DC interference of existing and planned lines, and the accuracy of the analytical method needs to be verified. Utility Model Content

[0004] In order to solve the above technical problems, the present application provides a scaled-down model for simulating the diffusion of stray current.

[0005] The scaled model includes:

[0006] A soil simulation layer, comprising a first soil layer and a second soil layer stacked in sequence from top to bottom, wherein the first soil layer and the second soil layer have different resistivities; a block medium simulating a lake or ocean is embedded in the first soil layer;

[0007] The rail transit line model is located on the first soil layer of the soil simulation layer and is a columnar structure, wherein the inner layer is a high-insulation material for simulating air, and the outer layer is an agar layer for simulating a cast tunnel structure, wherein the agar layer is embedded with carbon rods for simulating rails and drainage nets;

[0008] A ground potential measurement module, comprising a ground potential measurement point located in the first soil layer and a ground potential measurement instrument connected to the ground potential measurement point;

[0009] The power supply simulation circuit comprises a power supply and a switch, and the power supply is electrically connected to the carbon rod through the switch.

[0010] In one embodiment, the carbon rods simulating the rails and the drainage net have different diameters.

[0011] In one embodiment, the ground potential measurement module further includes a copper wire with low resistivity, wherein the copper wire is inserted into the ground potential measurement point and is electrically connected to a ground potential measurement instrument.

[0012] In one embodiment, the soil simulation layer is located in a metal pool, and the metal pool is grounded.

[0013] In one embodiment, the power supply of the power supply simulation circuit is a DC power supply, and the switch includes a switch K1, a switch K2, and a switch K3, and the switch K1, the switch K2, and the switch K3 are all electrically connected to the carbon rod, wherein the switch K1, the switch K2, and the switch K3 are connected in parallel.

[0014] In one embodiment, the resistance calculation formula of the carbon rod simulating the rail and the drainage net is:

[0015]

[0016] The resistivity of the carbon rod is ρ, the longitudinal resistance of the rail or drainage network is Rz, the actual line distance L1 and the scaled distance L2 can be calculated according to formula (1) to obtain the scale factor η.

[0017] In one embodiment, the switch K1 is closed, and the switches K2 and K3 are opened to simulate unilateral power supply of urban rail transit; the switches K2 and K3 are closed, and the switch K1 is opened to simulate bilateral power supply of urban rail transit.

[0018] In general, the above technical solution conceived by the utility model has the following beneficial effects compared with the prior art:

[0019] The beneficial effects of the utility model are as follows: the DC interference generated by the DC power supply system of rail transit is simulated under indoor conditions, and the influence mechanism of bilateral power supply mode, block medium and soil stratification on the diffusion of stray current can be studied, and the accuracy of the DC interference of urban rail transit calculated by analytical method can be verified. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the scaled-down experiment of the stray current diffusion model for urban rail transit.

[0021] Figure 2 This is a schematic diagram of the scaled model of the urban rail transit line.

[0022] Figure 3 Schematic diagram of switching power supply modes for trains.

[0023] Figure 4 Schematic diagram of soil stratification and bulk media.

[0024] Figure 5 This is a schematic diagram for ground potential measurement. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the utility model more clear, the utility model is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the utility model and are not used to limit the utility model. In addition, the technical features involved in each embodiment of the utility model described below can be combined with each other as long as they do not conflict with each other.

[0026] like Figure 1 As shown, a scaled model simulating the diffusion of stray current disclosed in the present application includes: a soil simulation layer, a first soil layer 10 and a second soil layer 20 are stacked in sequence from top to bottom, and the resistivity of the first soil layer is different from that of the second soil layer; a block medium 80 simulating a lake or ocean is embedded in the first soil layer 10.

[0027] The soil simulation layer of the present application is placed in a metal pool. The metal pool 30 has a square metal shell and is grounded.

[0028] The rail transit line model is located on the first soil layer 10 of the soil simulation layer and is a columnar structure, wherein the inner layer is a high-insulation material 40 for simulating air, and the outer layer is an agar layer 50 for simulating a cast tunnel structure, wherein the agar layer is embedded with carbon rods 60 for simulating rails and drainage nets;

[0029] In this embodiment, carbon rods of different diameters simulate rails and drainage nets respectively, and block agar simulates rivers, lakes, oceans, etc.

[0030] In this embodiment, the ground potential measurement module includes a ground potential measurement point 90 located in the first soil layer 10 and a ground potential measurement instrument 70 connected to the ground potential measurement point; the ground potential measurement module also includes a low-resistivity copper wire, which is inserted into the ground potential measurement point and electrically connected to the ground potential measurement instrument.

[0031] In this embodiment, the power supply simulation circuit includes a power supply and a switch, and the power supply is electrically connected to the carbon rod through the switch.

[0032] like Figure 2 As shown in the figure, the urban rail transit line is scaled down, the resistivity of agar is adjusted to simulate the tunnel structure, carbon rods of different diameters simulate the rails and drainage nets respectively, and high insulation material 40 simulates the tunnel air space. The carbon rods are embedded in the agar casting. Figure 3The power supply simulation circuit shown in the figure includes a power supply and a switch. The power supply is electrically connected to the carbon rod through the switch to simulate the single and double-sided power supply of urban rail transit. The carbon rod leads 1, 2, and 3, and each lead is provided with a switch K1, K2, and K3. The resistivity of agar is adjusted to simulate a block medium (river, lake, ocean, etc.). The produced line model and block medium are placed as follows Figure 4 The first layer of soil in Figure 5 Insert copper wire at the corresponding ground potential measurement point and connect a high-precision ground potential measuring instrument. Close K1, open K2 and K3 to simulate unilateral power supply for urban rail transit, close K2 and K3, open K1 to simulate bilateral power supply for urban rail transit.

[0033] The utility model is further described in detail below with reference to the accompanying drawings and specific implementation methods;

[0034] like Figure 1 As shown in the figure, the steps for establishing a scaled model for simulating stray current diffusion are as follows:

[0035] Step 1: Determine the reduction ratio and structural dimensions. Based on the actual distance L1 of the track before reduction and the distance L2 after reduction, the reduction coefficient η can be calculated according to formula (1). It is known that the longitudinal resistance of a row of rails or drainage nets is R z The equivalent resistance R of the rails or drainage network of two rows of the actual line before scaling can be calculated by formula (2): eq The resistivity of the carbon rod is ρ, and the diameter d of the carbon rod simulating the rail and the drainage net can be calculated by formula (3).

[0036]

[0037] Step 2: Model making

[0038] Step 2.1 Select soil layers and bulk media: If you need to simulate the diffusion of stray current generated by urban rail transit in multiple layers of soil, you need to use soils with different resistivities to simulate soil layers. Figure 4 As shown, it must be placed in the first layer of soil.

[0039] Step 2.2 Fix the carbon rods simulating the high insulation material of the air domain and the rails and drainage network, connect the lead wires simulating the single and double-sided power supply of the DC power supply system of urban rail transit, and connect them with K1, k2, K3 and the DC constant current source, and then use agar simulating the tunnel structure for casting.

[0040] Step 2.3 Arrange the ground potential measurement module: Arrange ground potential test points on both sides of the line model, insert copper wires at the test points, and then press Figure 5 Connect to high-precision potential measuring instrument.

[0041] Step 3: Power on and ground the equipment. Ground the metal pool 30, close K1, open K2 and K3, simulate unilateral power supply for urban rail transit, close K2 and K3, open K1, simulate bilateral power supply for urban rail transit.

[0042] Step 4: Data recording and analysis

[0043] The potentials of the test points on both sides of the scaled model are processed respectively, and the effects of single and double-sided power supply modes, blocky media, soil stratification, etc. on the diffusion of stray current are analyzed.

[0044] It is easy for those skilled in the art to understand that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A scaled-down model for simulating stray current diffusion, characterized in that: The scaled model includes: A soil simulation layer, comprising a first soil layer and a second soil layer stacked in sequence from top to bottom, wherein the first soil layer and the second soil layer have different resistivities; a block medium simulating a lake or ocean is embedded in the first soil layer; The rail transit line model is located on the first soil layer of the soil simulation layer and is a columnar structure, wherein the inner layer is a high-insulation material for simulating air, and the outer layer is an agar layer for simulating a cast tunnel structure, wherein the agar layer is embedded with carbon rods for simulating rails and drainage nets; A ground potential measurement module, comprising a ground potential measurement point located in the first soil layer and a ground potential measurement instrument connected to the ground potential measurement point; The power supply simulation circuit comprises a power supply and a switch, and the power supply is electrically connected to the carbon rod through the switch.

2. The scaled-down model for simulating stray current diffusion according to claim 1, characterized in that: The carbon rods simulating the steel rails and the drainage net have different diameters.

3. The scaled-down model for simulating stray current diffusion according to claim 1, characterized in that: The ground potential measurement module further includes a copper wire with low resistivity, which is inserted into the ground potential measurement point and electrically connected to a ground potential measurement instrument.

4. The scaled-down model for simulating stray current diffusion according to claim 2, characterized in that: The soil simulation layer is located in a metal pool, and the metal pool is grounded.

5. The scaled-down model for simulating stray current diffusion according to claim 1, characterized in that: The power supply of the power supply simulation circuit is a DC power supply, and the switches include switch K1, switch K2, and switch K3. The switches K1, switch K2, and switch K3 are all electrically connected to the carbon rod, wherein the switches K1, switch K2, and switch K3 are connected in parallel.

6. The scaled-down model for simulating stray current diffusion according to claim 5, characterized in that: Close switch K1, open switch K2 and switch K3 to simulate unilateral power supply of urban rail transit; close switch K2 and switch K3, open switch K1 to simulate bilateral power supply of urban rail transit.

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