Stray current corrosion simulation and protection experiment device and method

Abstract

This invention discloses a stray current corrosion simulation and protection experimental device and method, belonging to the field of stray current corrosion protection technology for rail transit. The device includes a simulated buried pipeline unit, a simulated stray current unit, a soil corrosivity index control unit, a protection unit, and a data acquisition unit. The simulated buried pipeline unit includes a pipeline under test with insulation layer damage points. The simulated stray current unit forms a stray current leakage channel through a ring rail, a ring contact network, a simulated train, and a conductive rod inserted into the soil. The soil corrosivity index control unit can adjust soil temperature and ion concentration. The protection unit uses a potentiostat and control circuit to achieve forward and reverse current output. The data acquisition unit collects potential data at the pipeline damage points through a reference electrode. This invention can realistically reproduce complex corrosive environments, supports cathodic protection performance verification under various operating conditions, and provides an efficient experimental platform for research on stray current corrosion mechanisms and protection technologies.

Description

Technical Field

[0001] This invention relates to the field of stray current corrosion protection technology for rail transit, and in particular to a stray current corrosion simulation and protection experimental device and method. Background Technology

[0002] With the rapid development of urban rail transit, the widespread application of DC power supply systems in subways, light rail, and electrified railways has led to a significant amount of stray current leaking into the surrounding soil through the running rails. These stray currents diffuse in the soil and may penetrate the metal structure of buried long-distance pipelines through damage to the anti-corrosion coating, forming an electrochemical corrosion loop. This can ultimately cause localized corrosion or even perforation of the pipeline, seriously threatening the safe operation of the energy transmission system. The interference problem caused by stray currents is particularly prominent in areas where pipelines are adjacent to or intersect with rail transit lines, and has become one of the key factors affecting the service life of buried metal pipelines.

[0003] Stray currents affecting pipeline corrosion are influenced by various factors, including pipeline diameter and length, soil ion concentration, pH value, temperature, and whether multiple pipelines run in parallel. When parallel pipelines each have an independent cathodic protection system, the current field can create stray loops between adjacent pipelines, leading to localized overprotection or underprotection. Furthermore, soil corrosivity varies significantly across different regions, types, and environments, thus also impacting pipeline corrosion in different ways.

[0004] In practical engineering for stray current control, a comprehensive technical system has been established, ranging from end-of-pipe treatment to source control. For example, in the case of interference from Nanchang Metro Line 1 to a nearby oil pipeline, engineers used the feed-current drainage method. By applying a precise reverse cathodic protection current to the affected pipeline section, they successfully restored the pipeline potential to the standard protection range. However, improper output current in the feed-current drainage method may lead to cathodic stripping of the pipeline's anti-corrosion layer or hydrogen embrittlement. Currently, there is a lack of systematic experimental equipment for simulation studies. Summary of the Invention

[0005] Based on the above-mentioned technical problems, this invention proposes an experimental device and method for simulating and protecting against stray current corrosion.

[0006] The technical solution adopted in this invention is as follows: A stray current corrosion simulation and protection experimental device includes a simulated buried pipeline unit, a simulated stray current unit, a soil corrosivity index control unit, a protection unit, and a data acquisition unit. The simulated buried pipeline unit includes an insulation box, in which the pipeline to be tested is laid and filled with soil, and insulation layer damage points are preset on the outer surface of the pipeline to be tested. The simulated stray current unit includes insulated sleepers, a ring rail, a ring contact wire, and conductive rods. The insulated sleepers are laid above the soil along the ring test line, and the ring rail is fixed on them. The simulated train is placed above the ring rail. The ring contact wire is suspended above the insulated box by an insulated bracket. The pantograph on the top of the simulated train maintains sliding contact with the ring contact wire. The ring contact wire and the ring rail are connected to the central control power supply. Multiple conductive rods are provided, all of which are laid along the ring rail. The upper end of the conductive rod is connected to the ring rail, and the lower end is inserted into the soil to form a stray current leakage channel. The soil corrosivity index control unit includes a heater for regulating soil temperature and a soil ion concentration regulator for regulating soil ion content. The protection unit includes a potentiostat and a control circuit for adjusting the current flow direction of the potentiostat. The potentiostat is connected to the pipe under test through the control circuit. The data acquisition unit includes a data acquisition unit and a reference electrode. The reference electrode is placed at the point of insulation damage in the pipe under test, and both the reference electrode and the pipe under test are connected to the data acquisition unit.

[0007] This invention also provides a method for simulating and protecting against stray current corrosion, using the experimental apparatus described above, and comprising the following steps: (1) According to the experimental requirements, the insulation box was divided into multiple independent compartments by using insulating baffles. Soil from different regions was filled into each compartment to simulate the corrosion conditions when the pipeline under test passes through different regions. (2) Multiple pipelines to be tested are laid out and arranged in different spatial arrangements according to experimental requirements to simulate the laying conditions of the pipelines to be tested in complex urban environments. (3) By adjusting the heater, the soil temperature in each compartment is changed; and the soil ion concentration regulator is used to change the soil moisture content, pH value and ion concentration to simulate the corrosion conditions of the pipeline under test under different soil corrosion factors. (4) By controlling the second and third switches to be turned on and the first and fourth switches to be turned off, the potentiostat is connected to the pipe under test in the forward direction to apply current to the pipe under test and apply cathodic protection potential when the pipe under test is interfered with by stray current; by controlling the first and fourth switches to be turned on and the second and third switches to be turned off, the potentiostat is connected to the pipe under test in the reverse direction to discharge current from the pipe under test, thereby draining current when the cathodic protection potential of the pipe under test is too large; wherein, the data acquisition unit collects the pipe-to-ground potential of the pipe under test and feeds it back to the central control unit, and the central control unit controls the on / off of the first, second, third and fourth switches.

[0008] The beneficial technical effects of the present invention are as follows: (1) This invention provides a stray current simulation and protection experimental device for rail transit with a structure close to engineering practice and easy to build. The device uses an adjustable soil corrosion index system (including key parameters such as ion concentration, pH value, humidity, and temperature) and flexible pipeline layout and conductive rod layout to realistically reproduce the complex corrosion environment on site and can study the corrosion of pipelines by stray current under different influencing factors.

[0009] (2) This invention introduces a control circuit to drive a potentiostat to achieve precise output of forward and reverse currents, thereby flexibly simulating the actual protection performance of the cathodic protection module under various operating conditions (such as different soil resistivity, stray current interference intensity, and pipeline layout). This design not only improves the accuracy and response speed of current control, but also effectively reproduces the electrochemical interaction process when multiple buried pipelines are laid under complex electromagnetic environments. Thus, it provides a highly controllable and repeatable experimental method for in-depth research on the formation mechanism, propagation path, and coupling effect of stray current-induced corrosion on adjacent pipeline systems, significantly enhancing the scientific rigor and engineering applicability of corrosion protection research.

[0010] (3) This invention integrates three core functional modules: parameter adjustment, corrosion simulation, and protection effect verification, constructing a complete experimental testing chain from corrosion environment simulation to protection performance evaluation. Through the collaborative operation of each unit, it not only achieves high-fidelity reproduction of the service environment of buried pipelines, but also supports the systematic verification and optimization of different protection strategies. This integrated design significantly reduces the complexity of experimental operations and research costs, providing an efficient, reliable, and easy-to-operate experimental platform for exploring the corrosion mechanism and developing protection technologies for buried metal pipelines along rail transit lines, with good engineering application prospects and scientific research promotion value. Attached Figure Description

[0011] Figure 1 This is a schematic diagram illustrating the structural principle of one embodiment of the stray current corrosion simulation and protection experimental device of the present invention; Figure 2 for Figure 1 A top-view schematic diagram of the structural principle.

[0012] In the diagram: 1-Central control unit, 2-Central control power supply, 3-Simulated train, 4-Pantograph, 5-Ring contact network, 6-Insulating support, 7-Pipe under test, 8-Conductive rod, 9-Heater, 10-Reference electrode, 11-Insulating box, 12-Soil ion concentration regulator, 13-Potentialistor, 14-Ring rail, 15-Soil, 16-Data acquisition unit, 17-Insulating baffle, 18-Control circuit, 19-Insulating sleeper. Detailed Implementation

[0013] This invention proposes an experimental apparatus and method for simulating and protecting against stray current corrosion under multi-pipeline deployment conditions. The apparatus can simulate the corrosive effects of stray currents generated by rail traffic on buried pipelines. By adjusting key soil corrosivity indicators such as temperature, ion concentration, and pH value, and by changing the pipeline layout, the corrosion behavior under different operating conditions is systematically studied. Furthermore, by controlling the real-time monitoring information fed back by the data acquisition device, the control circuit is dynamically adjusted and optimized, thereby achieving efficient and precise protection of the pipeline system. This experimental apparatus and method not only improve the timeliness and accuracy of the system response but also enhance the adaptive capability of the overall protection strategy, providing a reliable guarantee for the safe and stable operation of pipelines under complex operating conditions. Simultaneously, by comparing the experimental results under the same conditions with and without the activation of the cathodic protection module (i.e., potentiostat and control circuit), the protection effect is quantitatively evaluated, providing experimental basis for optimizing pipeline corrosion protection strategies in complex soil environments.

[0014] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0015] like Figure 1 As shown, a stray current corrosion simulation and protection experimental device includes a simulated buried pipeline unit, a simulated stray current unit, a soil corrosivity index control unit, a protection unit, and a data acquisition unit.

[0016] The simulated buried pipeline unit includes an insulation box 11, in which the pipeline to be tested 7 is laid out and filled with soil 15. The outer surface of the pipeline to be tested 7 is pre-set with insulation layer damage points to simulate on-site coating defects, provide a channel for stray current to flow in / out, and thus realistically reproduce the local corrosion behavior of buried steel pipelines under complex soil conditions.

[0017] The aforementioned insulation box 11 is an integral load-bearing structure. Several removable insulation baffles 17 can be further installed inside the insulation box 11 to divide the inner cavity of the insulation box 11 into several independent compartments or multiple independent areas. Each compartment is filled with different types of soil, such as different corrosivity levels or different physical and chemical properties (e.g., resistivity, porosity), according to the experimental plan, to simulate the working conditions of the pipeline under test crossing different geological environments, thereby simultaneously reproducing multiple geological environments within the same box. Figure 2As shown, the insulation box 11 is equipped with four horizontally or vertically equally distributed insulation baffles 17 to divide the insulation box 11 into eight independent compartments. Multiple test pipes 7 are provided, which are laid at different burial depths according to experimental requirements and employ various spatial arrangement methods, including but not limited to parallel arrangement, cross arrangement, overlapping arrangement, grid arrangement, or radial arrangement. Of course, the diameter of each test pipe can also be set to different sizes. The test pipes can penetrate through each compartment, and through holes adapted to the test pipes are provided on the insulation baffles, ensuring that each pipe segment is in full contact with the corresponding soil.

[0018] The simulated stray current unit includes insulated sleepers 19, a circular rail 14, a circular contact wire 5, and conductive rods 8. The insulated sleepers 14 are laid equidistantly on the soil along the circular test line, and the circular rail 14 is fixed on them. Insulating pads can be used for the insulated sleepers 14 to support the circular rail. The simulated train 3 is placed above the circular rail 14. The circular contact wire 5 is suspended above the insulating box 11 by an insulating bracket 6, the bottom end of which is inserted into the soil. The pantograph 4 on top of the simulated train 3 maintains sliding contact or a sliding connection with the circular contact wire 5. The circular contact wire 5 and the circular rail 14 are electrically connected to the positive and negative terminals of the central control power supply 2, respectively, to form a complete traction power supply circuit.

[0019] After the central control power supply 2 is started, the output current is modulated by the central control unit 1 into different waveforms and amplitudes according to the experimental requirements, and flows sequentially through the ring contact network 5, pantograph 4, simulated train 3 and ring rail 14 to form a complete traction power supply circuit. After the simulated train 3 obtains electrical energy, the traction motor drives the wheels to rotate, that is, to run continuously along the ring rail 14.

[0020] The central control power supply 2 can be configured as a DC regulated power supply. It provides an adjustable DC voltage to the ring contact network 5 to simulate traction current under different operating conditions. Multiple conductive rods 8 are arranged equidistantly along the extension direction of the ring rail. The upper end of each conductive rod 8 is connected to the ring rail 14, and the lower end is inserted into the soil, forming a stray current leakage channel. This realistically reproduces the stray current distribution characteristics caused by poor rail-to-ground insulation during train operation. In other words, the ring rail and the test pipeline passing through each compartment below are electrically connected via multiple conductive rods 8. This connection method can guide the stray current generated by the simulation experimental device to different pipeline interface positions according to preset experimental conditions, thereby achieving controllable allocation and flexible adjustment of the stray current path and providing necessary boundary condition support for the study of pipeline electrochemical behavior under multiple operating conditions.

[0021] The soil corrosivity index control unit includes a heater 9 for regulating soil temperature and a soil ion concentration regulator 12 for regulating soil ion content. The heater 9 is located at the bottom of the insulation box 11, with multiple heaters installed, one at the bottom of each compartment. The heater 9 allows for independent, zoned temperature control of different areas within the insulation box, enabling differentiated heating and improving the accuracy of temperature field control during stray current simulation. It also enhances the system's operational flexibility and reliability under various operating conditions. The soil ion concentration regulator 12 includes a spray head connected to a storage tank via a solution delivery pipe. The storage tank contains an ion solution, which is uniformly sprayed onto the soil surface using the soil ion concentration regulator. Figure 2 As shown, each compartment is also equipped with a soil ion concentration regulator 12. The soil ion concentration regulator 12 contains various types of ionized water with different ion concentrations, and can adjust soil parameters such as ion concentration, humidity, and pH value through spraying. The soil ion concentration regulator 12 uniformly injects pre-prepared electrolyte solutions (such as NaCl, NaOH, HCl, etc.) into the soil through spraying.

[0022] The protection unit includes a potentiostat 13 and a control circuit 18 for adjusting the current flow of the potentiostat 13. The potentiostat 13 is connected to the pipe under test 7 through the control circuit 18. Specifically, the control circuit 18 includes a first control switch Q1, a second control switch Q2, a third control switch Q3, and a fourth control switch Q4. The negative terminal of the potentiostat 13 is connected to the pipe under test 7 through a first line, and the first control switch Q1 is located on the first line. The positive terminal of the potentiostat 13 is connected to the pipe under test through a second line, and the second control switch Q2 is located on the second line. The negative terminal of the potentiostat is connected to a sacrificial anode buried in the soil through a third line, and the third control switch Q3 is located on the third line. The positive terminal of the potentiostat 13 is connected to the sacrificial anode buried in the soil through a fourth line, and the fourth control switch Q4 is located on the fourth line. When the pipe is in an underprotected state, by turning on the second and third control switches and turning off the first and fourth control switches, the potentiostat applies current to the pipe under test to protect it. When the pipeline is in over-protection mode, open the first and fourth control switches, and close the second and third control switches. The potentiostat will then discharge current from the pipeline under test, stabilizing the pipeline-to-ground potential between -0.85V and 1.20V.

[0023] The data acquisition unit includes a data acquisition unit 16 and a reference electrode 10. The reference electrode 10 is positioned near the insulation damage point of the pipe under test. Both the reference electrode 10 and the pipe under test 7 are connected to the data acquisition unit 16, and can be used to measure the potential between the pipe and the ground. The first control switch Q1, the second control switch Q2, the third control switch Q3, and the fourth control switch Q4 are all connected to the central control unit 1. This allows the central control unit 1 to adjust the control circuit 18 in real time based on the data acquired by the data acquisition unit 16. The central control power supply 2, the data acquisition unit 16, the soil ion concentration regulator 12, and the heater 9 are all connected to the central control unit 1. The central control unit 1 controls the central control power supply 2, the heater 9, and the soil ion concentration regulator 12 in real time. If the central control power supply 2 and the central control unit 1 form a high dynamic response closed loop, under the command drive and real-time closed-loop adjustment of the central control unit 1, it has the ability to generate various high-precision preset waveforms and arbitrary waveform current outputs based on programmable logic. This system can flexibly generate current signals including but not limited to step, ramp, pulse, and complex time-varying waveforms.

[0024] In other words, one end of the control circuit 18 is connected to the pipe under test, and the other end is connected to the sacrificial anode material buried in the soil, with a potentiostat 13 connected in series in the middle. The circuit integrates four electronic switches controlled by the central control unit, which can switch between multiple modes such as "open circuit (no protection)", "sacrificial anode protection", "forced current cathodic protection" and "drainage protection" through switch combinations.

[0025] Current sensors are distributed on both the circular steel rail 14 and the circular contact wire 5, and these current sensors are also connected to the central control unit 1. The current sensors can monitor the stray current released directly into the soil by the track, i.e., the circular steel rail 14.

[0026] The test pipes buried in the soil within the aforementioned insulation box 11 can be configured as ring structures, and the diameter, material, and length of each test pipe can be differentiated according to experimental needs. Furthermore, the pipes can be laid at different burial depths according to experimental requirements and can be arranged in various spatial arrangements, including but not limited to parallel, intersecting, grid-like, or radial arrangements.

[0027] To simulate real-world conditions as closely as possible, the test pipe was made of steel and sealed at both ends. In this experimental setup, the pipe was passed through various types of soil, allowing for easy observation of corrosion and comparison of corrosion rates across different soil types.

[0028] The electrolyte used in this invention is an easily prepared solution such as NaCl, NaOH, or HCl.

[0029] This invention also provides a method for simulating and protecting against stray current corrosion, using the experimental apparatus described above, and comprising the following steps: (1) According to the experimental requirements, the insulating box 11 is divided into multiple independent compartments by the insulating baffle 17, and each compartment is filled with soil from different regions to simulate the corrosion conditions when the long-distance pipeline passes through different regions.

[0030] (2) Multiple pipelines to be tested are laid out and arranged in different spatial ways according to experimental requirements to simulate the laying conditions of the pipelines to be tested in complex urban environments.

[0031] (3) The soil temperature in each compartment is changed by adjusting the heater 9. The soil ion concentration regulator 12 is used to change the soil moisture content, pH value and ion concentration to simulate the corrosion conditions of the pipeline under test under different soil corrosion factors. The final corrosion condition or protection condition needs to be determined by observation after the experiment is completed.

[0032] (4) By controlling the second switch Q2 and the third switch Q3 to be turned on, and the first switch Q1 and the fourth switch Q4 to be turned off, the potentiostat 13 is connected to the pipe under test 7 in the forward direction to apply current to the pipe under test and apply cathodic protection potential when the pipe under test is interfered with by stray current. By controlling the first switch Q1 and the fourth switch Q4 to be turned on, and the second switch Q2 and the third switch Q3 to be turned off, the potentiostat 13 is connected to the pipe under test 7 in the reverse direction to discharge current from the pipe under test 7, thereby draining current when the cathodic protection potential of the pipe under test is too high. The pipe under test is also connected to the data acquisition unit 16. The data acquisition unit 16 collects the pipe-to-ground potential of the pipe under test and feeds it back to the central control unit 1, which controls the on / off state of the first switch, the second switch, the third switch and the fourth switch.

[0033] (5) According to the experimental requirements, by changing the number and placement of the conductive rods 8, the stray current leakage scenario caused by the decrease in insulation performance of the ring rail 14 in different sections and to different degrees can be simulated, so as to provide an adjustable experimental condition for studying the interference law of local insulation failure on the pipeline under test.

[0034] (6) During the simulated train operation, the central control unit 1 simulates the actual operating conditions of nighttime shutdown and morning and evening peak start-up and shutdown by instantly cutting off or suddenly increasing the current, thereby reproducing the corresponding stray current transient process and providing dynamic data for studying the corrosion risk of the pipeline under test.

[0035] After completing the above steps, all instruments can be turned off, and heater 9 and soil ion concentration regulator 12 can be started to switch to different operating conditions and continue the experiment.

[0036] For any parts not mentioned above, existing technologies can be adopted or referenced.

[0037] Of course, the above description is only a preferred embodiment of the present invention. The present invention is not limited to the above-described embodiments. It should be noted that any equivalent substitutions or obvious modifications made by those skilled in the art under the guidance of this specification fall within the scope of this specification and should be protected by the present invention.

Claims

1. A stray current corrosion simulation and protection experimental device, characterized in that: It includes a simulated buried pipeline unit, a simulated stray current unit, a soil corrosivity index control unit, a protection unit, and a data acquisition unit; The simulated buried pipeline unit includes an insulation box, in which the pipeline to be tested is laid and filled with soil, and insulation layer damage points are preset on the outer surface of the pipeline to be tested. The simulated stray current unit includes insulated sleepers, a ring rail, a ring contact wire, and conductive rods. The insulated sleepers are laid above the soil along the ring test line, and the ring rail is fixed on them. The simulated train is placed above the ring rail. The ring contact wire is suspended above the insulated box by an insulated bracket. The pantograph on the top of the simulated train maintains sliding contact with the ring contact wire. The ring contact wire and the ring rail are connected to the central control power supply. Multiple conductive rods are provided, all of which are laid along the ring rail. The upper end of the conductive rod is connected to the ring rail, and the lower end is inserted into the soil to form a stray current leakage channel. The soil corrosivity index control unit includes a heater for regulating soil temperature and a soil ion concentration regulator for regulating soil ion content. The protection unit includes a potentiostat and a control circuit for adjusting the current flow direction of the potentiostat. The potentiostat is connected to the pipe under test through the control circuit. The data acquisition unit includes a data acquisition unit and a reference electrode. The reference electrode is placed at the point of insulation damage in the pipe under test, and both the reference electrode and the pipe under test are connected to the data acquisition unit.

2. The stray current corrosion simulation and protection experimental device according to claim 1, characterized in that: The control circuit includes a first control switch, a second control switch, a third control switch, and a fourth control switch. The negative terminal of the potentiostat is connected to the pipe under test via a first line, and the first control switch is located on the first line. The positive terminal of the potentiostat is connected to the pipe under test via a second line, and the second control switch is located on the second line. The negative terminal of the potentiostat is connected to the sacrificial anode in the soil via a third line, and the third control switch is located on the third line. The positive terminal of the potentiostat is connected to the sacrificial anode in the soil via a fourth line, and the fourth control switch is located on the fourth line. Turn on the second and third control switches, and turn off the first and fourth control switches to apply current to the pipe under test using the potentiostat; turn on the first and fourth control switches, and turn off the second and third control switches to discharge current from the pipe under test using the potentiostat.

3. The stray current corrosion simulation and protection experimental device according to claim 2, characterized in that: The first, second, third, and fourth control switches are all connected to the central control unit; the central control power supply, data acquisition unit, soil ion concentration regulator, and heater are all connected to the central control unit.

4. The stray current corrosion simulation and protection experimental device according to claim 3, characterized in that: The insulation box is equipped with several removable insulation baffles to divide the inner cavity of the insulation box into several independent compartments. Each compartment is filled with soil of different corrosiveness levels according to the experimental plan. Multiple test pipes are set up and laid at different burial depths according to experimental requirements, and various spatial arrangement methods are adopted, including but not limited to parallel arrangement, cross arrangement, vertical overlapping arrangement, grid arrangement or radial arrangement. The test pipes run through each compartment, and through holes adapted to the test pipes are set on the insulation baffles.

5. The stray current corrosion simulation and protection experimental device according to claim 4, characterized in that: The insulated sleepers are equidistantly arranged along the circular test line, and multiple conductive rods are equidistantly arranged along the extension direction of the circular rail; the bottom end of the insulated support is inserted into the soil; the central control power supply provides an adjustable DC voltage to the circular contact network to simulate the traction current under different operating conditions.

6. The stray current corrosion simulation and protection experimental device according to claim 5, characterized in that: The heater is arranged at the bottom of the insulation box, and multiple heaters are provided, with one heater corresponding to the bottom of each compartment; the soil ion concentration regulator includes a spray head, which is connected to a storage tank through a solution delivery pipe. The storage tank is filled with an ion solution, and the soil ion concentration regulator evenly sprays the ion solution in the storage tank onto the soil surface.

7. The stray current corrosion simulation and protection experimental device according to claim 6, characterized in that: Current sensors are distributed on both the annular steel rail and the annular contact wire, and the current sensors are connected to the central control unit.

8. A method for simulating and protecting against stray current corrosion, using the experimental apparatus described in any one of claims 1-7, characterized in that... Includes the following steps: (1) According to the experimental requirements, the insulation box was divided into multiple independent compartments by using insulating baffles. Soil from different regions was filled into each compartment to simulate the corrosion conditions when the pipeline under test passes through different regions. (2) Multiple pipelines to be tested are laid out and arranged in different spatial arrangements according to experimental requirements to simulate the laying conditions of the pipelines to be tested in complex urban environments. (3) By adjusting the heater, the soil temperature in each compartment is changed; and the soil ion concentration regulator is used to change the soil moisture content, pH value and ion concentration to simulate the corrosion conditions of the pipeline under test under different soil corrosion factors. (4) By controlling the second and third switches to be turned on and the first and fourth switches to be turned off, the potentiostat is connected to the pipeline under test in the forward direction to apply current to the pipeline under test and apply cathodic protection potential when the pipeline under test is subjected to stray current interference. By controlling the first and fourth switches to be turned on and the second and third switches to be turned off, the potentiostat is reverse-connected to the pipe under test to discharge current from the pipe under test, thereby draining current when the cathodic protection potential of the pipe under test is too high; wherein, the data acquisition unit collects the pipe-to-ground potential of the pipe under test and feeds it back to the central control unit, which controls the on / off state of the first, second, third and fourth switches.

9. The stray current corrosion simulation and protection experimental method according to claim 8, characterized in that, It also includes the following steps: By changing the number and placement of conductive rods, stray current leakage scenarios caused by varying degrees of insulation performance degradation in different sections of the circular rail can be simulated, providing adjustable experimental conditions for studying the interference patterns of local insulation failure in the pipeline under test.

10. The stray current corrosion simulation and protection experimental method according to claim 8, characterized in that, It also includes the following steps: During the simulated train operation, the central control unit instantly cuts off or sharply increases the current to simulate the real operating conditions of nighttime shutdown and morning and evening peak hours, thereby reproducing the corresponding stray current transient process and providing dynamic data for studying the corrosion risk of the pipeline under test.

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