A stray current simulation device

Abstract

The present invention discloses a stray current simulation device, comprising a container, wherein an electrolyte is contained inside; a pipe, which is arranged in the container and immersed in the electrolyte, and an insulating layer damage point is arranged on the surface of the pipe; a metal rail, which is fixed on the container; a metal slider, which is arranged on the metal rail and can slide along the metal rail; a first electrode, which is electrically connected to the metal slider; a voltage-stabilizing power supply, whose positive electrode is electrically connected to the metal slider and whose negative electrode is connected to the second electrode; both the first electrode and the second electrode are immersed in the electrolyte; and the sliding speed v of the metal slider and the concentration c of the electrolyte are controlled to adjust the loop impedance. The present invention provides a simple and convenient test and verification platform for studying the distribution law and transmission characteristics of stray current.

Description

Technical Field

[0001] The invention relates to a stray current interference and protection technology, in particular to a stray current simulation device. Background Art

[0002] With the rapid construction of underground long-distance pipelines, subways, electrified railways and other rail transit, the problem of stray current interference generated by rail transit operation has become increasingly serious. The stray current leaks into the soil through the running rails, flows in and out from the damaged points of the insulation anti-corrosion layer of the buried long-distance pipeline, and then returns to the traction station, thus forming a stray current minimum conduction impedance loop. The inflow and outflow of stray currents will cause problems such as corrosion and dissolution of buried long-distance pipelines, reducing the safety and reliability of the long-term operation of buried long-distance pipelines, and posing a huge hidden danger to the national energy transportation system. Therefore, the study of the conduction law of stray current in rail transit is of great significance.

[0003] In the soil, stray currents are conducted both through the soil and through buried pipelines. Multiple conduction loops of stray currents can be regarded as a parallel relationship, in which the loop with the lowest equivalent impedance flows the most current. Usually, the soil equivalent impedance is greater than the pipeline metal impedance, so the stray current flowing through the buried long-distance pipeline conduction loop is the most. Therefore, the conduction loop impedance of the stray current will affect the distribution of the stray current. Since the soil impedance varies greatly in different regions, types, and environments, it is necessary to build a simulation device for research. The existing technical solutions have a separate simulation of the track running rail resistance, but there is still a lack of research on the conduction loop impedance. Therefore, designing a stray current simulation device and method with adjustable loop impedance is of great significance for studying the distribution law of stray currents under different loop impedances.

[0004] CN105842144B considers the corrosion of buried metals caused by stray current of DC grounding electrodes and the influence of different power supply waveforms on the corrosion of buried pipelines, but ignores the fact that the impedance of the stray current conduction loop is different in different time and space environments due to factors such as climate, humidity, and soil quality. Different loop impedances will change the distribution law and transmission characteristics of the stray current. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a stray current simulation device to simulate the conduction loop of stray current in rail transit, and change the size of the conduction loop impedance by controlling the concentration of the electrolyte and the moving speed of the simulated track, so as to provide an experimental research and testing platform for studying the distribution and interference law of stray current under different loop impedance conditions.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: a stray current simulation device, comprising:

[0007] A container containing an electrolyte;

[0008] A pipeline is arranged in the container and immersed in the electrolyte, and a first damage point of the pipeline insulation layer and a second damage point of the pipeline insulation layer are arranged on the surface of the pipeline;

[0009] a metal guide rail fixed to the container;

[0010] A metal slider is disposed on the metal guide rail and can slide along the metal guide rail;

[0011] A first electrode electrically connected to the metal slider;

[0012] A voltage-stabilized power supply, wherein the positive electrode is electrically connected to the metal slider and the negative electrode is connected to the second electrode;

[0013] The first electrode and the second electrode are both immersed in the electrolyte;

[0014] Controlling the sliding speed v of the metal slider and the concentration c of the electrolyte to adjust the loop impedance;

[0015] The circuit refers to a circuit formed by connecting the voltage-stabilized power supply, the metal guide rail, the metal slider, the first electrode, and the second electrode.

[0016] The present invention utilizes the characteristics that the contact impedance of the guide rail changes with the moving speed, and the equivalent impedance of the electrolyte changes with the solution concentration. Taking into account the change in contact impedance caused by the change in the moving speed of the rail transit vehicle and the change in soil impedance caused by the different electrolyte concentrations in the soil, a metal slider is used to simulate a running train, and an electrolyte solution is used to simulate the soil. The impedance of the conduction loop is changed by controlling the moving speed of the slider and the concentration of the electrolyte solution. The controllable adjustment of the impedance of the stray current conduction loop can be achieved without adding an additional rheostat, thereby providing a simple and convenient testing and verification platform for studying the distribution law and transmission characteristics of stray currents.

[0017] The electrolyte is a NaCl solution. The NaCl solution is used as an electrolyte because it is cheap and easy to configure. There are relevant standards that can directly obtain the relationship between the conductivity and concentration of the NaCl solution, eliminating the step of measuring the relationship between the conductivity and concentration of the solution, and can keep the pH value of the electrolyte approximately neutral.

[0018] A reference electrode is arranged near the damaged point of the insulating layer on the surface of the pipeline; the reference electrode is electrically connected to a data collector; the data collector is electrically connected to the pipeline. The reference electrode is used as a reference potential to measure the pipeline-to-ground potential.

[0019] In order to facilitate observation of the experimental process, in the present invention, the container is a glass jar.

[0020] In the present invention, in order to prevent corrosion by electrolyte, the pipeline is a steel pipe, and both ends of the pipeline are closed.

[0021] In the present invention, the loop impedance R total The calculation formula is:

[0022]

[0023] Wherein, c is the electrolyte concentration, v is the sliding speed of the metal slider, l1 and S1 represent the distance between the first electrode and the first damaged point of the pipeline insulation layer, and the area of ​​the first damaged point of the pipeline insulation layer, respectively; l2 and S2 represent the distance between the first electrode and the second electrode, and the surface area of ​​the first electrode; l3 and S3 represent the distance between the second electrode and the second damaged point of the pipeline insulation layer, and the area of ​​the second damaged point of the pipeline insulation layer, respectively. R x represents the sum of the inherent impedance of the metal slider and the inherent impedance of the metal guide rail, R0 represents the contact impedance of the metal slider when it is stationary, and R v =R0e Av +Bv+R x , A, B, and P represent proportional coefficients; the surface area of ​​the first electrode is the same as the surface area of ​​the second electrode, S1=S3.

[0024] The present invention uses the movement of a metal slider on a metal guide rail to simulate the operation of rail transit. On the one hand, the actual operation state of rail transit is simulated in form, so that the generated stray current interference is closer to reality; on the other hand, the impedance relationship between the metal slider and the metal guide rail can be used to easily change the guide rail contact impedance R by changing the moving speed v of the metal slider. v The size of the rail transit system provides experimental conditions for researchers to study the impact of stray currents at different operating speeds of rail transit.

[0025] The metal slider and the metal rail are two conductive objects that conduct electricity through the electrical contact surface. There is contact impedance at the electrical contact surface, which is used to simulate the actual scenario of rail transit conducting electricity through the pantograph and the running rail in actual operation. When the metal slider is stationary, the contact impedance is R0; when the metal slider moves, the contact impedance is R v1 It will change with the change of the moving speed v of the metal slider, and the relationship is R v1 =R0e Av +Bv, where A and B are proportional coefficients, and their values ​​can be obtained by least squares method parameter fitting; at the same time, the metal slider and the metal rail have inherent impedance, which is used to simulate the inherent impedance of the running rail and the train. The sum of the inherent impedance of the metal slider and the metal rail is R x .

[0026] In the present invention, an electrolyte is used to simulate the soil electrolyte conductive environment. By utilizing the relationship between the resistivity and concentration of the electrolyte, the resistivity ρ can be easily changed by changing the concentration c of the electrolyte, thereby simulating the soil impedance in different regions and different environments.

[0027] The electrolyte uses an easily configured NaCl solution, and the relationship between the resistivity ρ and the concentration c of the NaCl solution can be directly obtained by looking up the relevant national standard (GB / T 27503-2011) by the table method. Considering that the first electrode and the second electrode conduct electricity through the electrolyte and the pipe in the electrolyte, for the convenience of analysis, it is approximately considered that there are two conduction loops, namely, conduction directly through the electrolyte and conduction through "electrolyte-pipe-electrolyte", and the two loops are in parallel.

[0028] In a circuit that conducts electricity directly through the electrolyte, the circuit impedance consists only of the solution impedance, which is:

[0029]

[0030] Wherein, l2 and S2 represent the distance between the first electrode and the second electrode, the surface area of ​​the first electrode, c represents the concentration of the solution, and P represents the reciprocal of the resistivity ρ of the solution (electrolyte) and the concentration of the solution. The proportionality factor.

[0031] In a circuit that conducts electricity directly through "electrolyte-pipeline-electrolyte", the circuit impedance consists of two parts of solution impedance and pipeline impedance (approximately 0), and the formula is:

[0032]

[0033] Among them, l1 and S1 represent the distance between the first electrode and the first damaged point of the pipeline insulation layer, and the area of ​​the first damaged point of the pipeline insulation layer, respectively; l3 and S3 represent the distance between the second electrode and the second damaged point of the pipeline insulation layer, and the area of ​​the second damaged point of the pipeline insulation layer, and S1=S3.

[0034] Since the parameters l1, l2, l3, S1, S2, and S3 are determined when the device is installed, the solution impedance R c1 , R c2 With R c3 It is only determined by the solution concentration c, and the solution impedance R can be easily changed by changing the solution concentration c. c1 , R c2 With R c3 The series impedance is connected in series to the entire stray current impedance loop, so when the output of the regulated power supply remains unchanged, the larger the series impedance, the smaller the stray current. In the present invention, when considering the series impedance, the stray current Is The calculation formula is: Among them, U s Indicates the output of the regulated power supply, R v Represents the track contact impedance.

[0035] Since the stray current is divided in the parallel branches, the branch with larger impedance has smaller stray current, so the distribution of the stray current in the parallel branches can be changed by changing the soil impedance. In the present invention, when considering the parallel impedance, the calculation formula of the stray current of the loop is:

[0036]

[0037] Among them, I s1 Represents the current flowing through the electrolyte, I s2 Represents the current flowing through the pipeline, I s Indicates the stray current in the loop.

[0038] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention provides a rail transit stray current simulation experimental device with a simple structure and easy implementation, utilizing the characteristics that the contact impedance of the guide rail changes with the moving speed and the equivalent impedance of the electrolyte changes with the solution concentration, from the perspective of the impedance of the rail transit stray current conduction loop, taking into account the change in contact impedance caused by the change in the moving speed of rail transit, and the change in soil impedance caused by different soil electrolyte concentrations, a slider is used to simulate a running train, and an electrolyte solution is used to simulate the soil, and the impedance of the conduction loop is changed by controlling the moving speed of the slider and the concentration of the electrolyte solution, and the controllable adjustment of the stray current conduction loop impedance can be achieved without adding an additional rheostat, thereby providing a simple and convenient testing and verification platform for studying the distribution law and transmission characteristics of stray currents. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a structural schematic diagram of the present invention;

[0040] Figure 2 Schematic diagram of equivalent impedance of the conducting loop of the stray current simulation device in the present invention. DETAILED DESCRIPTION

[0041] like Figure 1 As shown, the stray current simulation device of the embodiment of the present invention can realize the adjustable loop impedance without an impedance device; the stray current simulation device of this embodiment includes a buried pipeline simulation unit, a stray current simulation loop unit, and a data acquisition unit; the specific structure of the device is as follows:

[0042] The simulated buried pipeline unit includes an experimental container 1, an electrolyte 2, and a pipeline 3; wherein the experimental container 1 contains the electrolyte 2, the pipeline 3 is placed in the experimental container 1 and immersed in the electrolyte 2, and the surface of the pipeline 3 is provided with a first damage point 4 of the insulating layer and a second damage point 5 of the insulating layer; the electrolyte 2 adopts a NaCl solution with a concentration of c to simulate the soil electrolyte environment.

[0043] The simulated stray current loop unit includes a metal rail 6, a metal slider 7, a voltage-stabilized power supply 8, a first electrode 9, and a second electrode 10; wherein the metal rail 6 is fixed on the upper surface of the experimental container 1; the metal slider 7 is embedded in the metal rail 6 and slides along the metal rail 6 at a speed v to simulate the operation of a subway train; the first electrode 9 is connected to the metal slider 7 by a wire; the positive terminal of the voltage-stabilized power supply 8 is connected to one end of the metal rail 6 by a wire, and the negative terminal of the voltage-stabilized power supply 8 is connected to the second electrode 10 by a wire; the first electrode 9 and the second electrode 10 are fixed to the side wall of the experimental container 1 and immersed in the electrolyte 2 to form a stray current conduction loop with the electrolyte 2 and the pipeline 3; there are two stray current conduction loops, and the total loop impedance is R total , and can be dynamically adjusted by the loop impedance adjustment method, the two conduction loops are as follows:

[0044] (a) Stray current forms a loop 1 only through the electrolyte, and the connection relationship is "positive terminal of the stabilized power supply 8-metal guide rail 6-metal slider 6-first electrode 9-electrolyte 2-second electrode 10-negative terminal of the stabilized power supply 8".

[0045] (b) Stray current forms a loop 2 through the electrolyte and the pipeline, and the connection relationship is "positive terminal of the stabilized power supply 8-metal guide rail 6-metal slider 7-first electrode 9-electrolyte 2-pipeline 3-electrolyte 2-second electrode 10-negative terminal of the stabilized power supply 8".

[0046] The data acquisition unit includes a first reference electrode 11, a second reference electrode 12, and a data collector 13. The first reference electrode 11 is placed near a first damaged point 4 of the insulation layer of the pipeline 3, and the second reference electrode 12 is placed near a second damaged point 5 of the insulation layer of the pipeline 3. The data collector 13 is connected to the first reference electrode 11, the second reference electrode 12, and the pipeline 3 through a wire for collecting and monitoring the pipe-to-ground potential.

[0047] In the embodiment of the present invention, the loop impedance adjustment method is to achieve the loop impedance R by changing the speed v of the metal slider and the concentration c of the electrolyte. total Adjustable, the specific implementation method is as follows:

[0048] (1) The metal slider 7 makes electrical contact with the metal guide rail 6 when sliding, and a contact impedance R is formed on the contact surface. v , the contact impedance R v As the sliding speed v of the metal slider 7 increases, the expression is:

[0049] R v =R0e Av +Bv+R x ;

[0050] Where R0 represents the contact impedance of the metal slider 7 when it is stationary, A and B represent the proportionality coefficients, and R x represents the inherent impedance of the metal slider 7 and the metal guide rail 6;

[0051] (2) The first electrode 9 and the second electrode 10 form a conductive loop through the electrolyte 2 and the pipeline 3. The electrolyte 2 and the pipeline 3 both have a certain impedance; wherein the impedance of the pipeline 3 is R p The electrolyte 2 between the first electrode 9 and the first damaged point 4 of the pipeline insulation layer forms a solution impedance R c1 The electrolyte 2 between the first electrode 9 and the second electrode 10 forms a solution impedance R c2 The electrolyte 2 between the second damaged point 5 of the pipeline insulation layer and the second electrode 10 forms a solution impedance R c3 ; The solution impedance R c1 , R c2 , R c3 It decreases with the increase of electrolyte concentration c, and the expression is:

[0052]

[0053] Among them, l1 and S1 represent the distance between the first electrode 9 and the first damaged point 4 of the pipeline insulation layer, and the area of ​​the first damaged point 4 of the pipeline insulation layer, respectively; l2 and S2 represent the distance between the first electrode 9 and the second electrode 10, and the surface area of ​​the first electrode 9; l3 and S3 represent the distance between the second electrode 10 and the second damaged point 5 of the pipeline insulation layer, and the area of ​​the second damaged point 5 of the pipeline insulation layer.

[0054] (3) Figure 2 As shown, under the series-parallel relationship of contact impedance, solution impedance, and pipeline impedance, the total loop impedance R total The expression is:

[0055]

[0056] Loop impedance R totalIt is related to the concentration c of the electrolyte 2 and the sliding speed v of the metal slider 7; therefore, the stray current simulation device can realize the loop impedance R by controlling the metal slider speed v and the electrolyte concentration c without adding an impedance device. total Adjustable.

[0057] In one embodiment of the present invention:

[0058] The experimental container 1 is a glass cylinder with a length of 1200 mm, a width of 500 mm, and a height of 500 mm;

[0059] Pipe 2 is made of Q235 steel with a length of 1100 mm, an outer diameter of 114 mm, and a wall thickness of 4 mm, and its two ends are sealed;

[0060] The electrolyte 3 uses a NaCl solution of a certain concentration;

[0061] The first damage point 4 of the insulating layer and the second damage point 5 of the insulating layer are in the shape of a rectangle, and the size of the rectangle is 10 mm×10 mm (length×width);

[0062] The metal guide rail 6 and the metal slide block 7 are made of SGI-10-1100MM;

[0063] The voltage stabilized power supply 8 uses IT7800 AC / DC Power Supply;

[0064] The first electrode 9 and the second electrode 10 are graphite electrodes with a length of 60 mm, a width of 60 mm and a thickness of 10 mm;

[0065] The first reference electrode 11 is a portable saturated copper sulfate reference electrode, which is installed just above the first damaged point 4 of the insulating layer;

[0066] The second reference electrode 12 is a portable saturated copper sulfate reference electrode, which is installed just above the second damaged point 5 of the insulating layer;

[0067] The data collector 13 uses the Labview acquisition card USB3133A;

[0068] The present invention can realize dynamic adjustment of the stray current conduction loop impedance without adding an additional resistor, thereby providing a simple and easy-to-implement test platform for studying the distribution law and transmission characteristics of rail transit stray current under different conduction loop impedances.

[0069] In the rail transit stray current conduction loop, the stray current will flow through the track contact impedance, pipeline impedance (approximately 0) and soil impedance. In the soil environment, the stray current will flow through the soil and pipeline at the same time. These two conduction paths can be approximately regarded as a parallel relationship. Then, by changing the size of the rail transit contact impedance, the series impedance of the loop can be changed, thereby affecting the size of the stray current. By changing the size of the soil impedance, the parallel impedance of the loop can be changed, thereby affecting the distribution of the stray current in the parallel branch.

[0070] like Figure 2 As shown, the series impedance is connected in series to the entire stray current impedance loop, so when the output of the regulated power supply remains unchanged, the larger the series impedance, the smaller the stray current. The formula is:

[0071]

[0072] Among them, U s Indicates the output of the regulated power supply, I s Represents the stray current of the entire stray current loop, R v Represents the series track contact impedance.

[0073] like Figure 2 As shown, since the stray current is divided in the parallel branches, the stray current flowing through the branch with larger impedance is small, so the distribution of stray current in the parallel branches can be changed by changing the soil impedance. The formula is:

[0074]

[0075] Among them, I s1 Represents the current flowing through the soil (electrolyte), I s2 Represents the current flowing through the pipe.

Claims

1. A stray current simulation device, characterized in that: include: A container containing an electrolyte; A pipe is arranged in the container and immersed in the electrolyte, and an insulation layer damage point is arranged on the surface of the pipe; a metal guide rail fixed to the container; A metal slider is disposed on the metal guide rail and can slide along the metal guide rail; A first electrode electrically connected to the metal slider; A voltage-stabilized power supply, wherein the positive electrode is electrically connected to the metal slider and the negative electrode is connected to the second electrode; The first electrode and the second electrode are both immersed in the electrolyte; Controlling the sliding speed v of the metal slider and the concentration c of the electrolyte to adjust the loop impedance; The circuit refers to the voltage-stabilized power supply, the metal guide rail, the metal slider, the first electrode, A loop formed by connecting the second electrode; The loop impedance R total The calculation formula is: Wherein, c is the electrolyte concentration, v is the sliding speed of the metal slider, l1 and S1 represent the distance between the first electrode and the first damaged point of the pipeline insulation layer, and the area of ​​the first damaged point of the pipeline insulation layer, respectively; l2 and S2 represent the distance between the first electrode and the second electrode, and the surface area of ​​the first electrode; l3 and S3 represent the distance between the second electrode and the second damaged point of the pipeline insulation layer, and the area of ​​the second damaged point of the pipeline insulation layer, respectively. R x represents the sum of the inherent impedance of the metal slider and the inherent impedance of the metal guide rail, R0 represents the contact impedance of the metal slider when it is stationary, and R v =R0e Av +Bv+R x , A, B, and P represent proportional coefficients; the surface area of ​​the first electrode is the same as the surface area of ​​the second electrode, S1=S3; The stray current I s The calculation formula is: Among them, U s Indicates the output of the regulated power supply, R v Indicates the rail contact impedance.

2. The stray current simulation device according to claim 1, characterized in that: The electrolyte is a NaCl solution.

3. The stray current simulation device according to claim 1, characterized in that: A reference electrode is arranged near the damaged point of the insulating layer on the surface of the pipeline; the reference electrode is electrically connected to the data acquisition device; The data collector is electrically connected to the pipeline.

4. The stray current simulation device according to claim 1, characterized in that: The container is a glass jar.

5. The stray current simulation device according to claim 1, characterized in that: The pipeline is a steel pipe, and both ends of the pipeline are closed.

6. The stray current simulation device according to claim 1, characterized in that: The size of the damaged point of the insulation layer is 10 mm×10 mm.

7. The stray current simulation device according to claim 1, characterized in that: The calculation formula of the stray current of the loop is: Among them, I s1 Represents the current flowing through the electrolyte, I s2 Represents the current flowing through the pipeline, I s Indicates the stray current in the loop.

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