A Design Method of a Rail Impedance Simulation Disk and a Test System for Broken Rail Monitoring Equipment

Abstract

The present invention discloses a design method for a rail impedance simulation disc and a test system for a broken rail monitoring device. The rail impedance is divided into two parts: the equivalent resistance of the rail and the equivalent inductance of the rail. The equivalent resistance and equivalent inductance of the rail are calculated respectively by using the correlation between resistance / inductance and frequency, and are corrected according to the data obtained from standard regulations or on-site collection to obtain an equivalent model of the rail impedance. A rail impedance simulation disc is manufactured according to the obtained equivalent model of the rail impedance. The test device composed of the rail impedance simulation disc and the rail fracture simulation module of the present invention and the device under test together constitute a test system for a broken rail monitoring device; the present invention uses a simulated rail impedance to simulate a real rail, and by using laboratory test techniques, it reduces the consumption of manpower and material resources, improves the test efficiency, and is more likely to conduct repeated experiments and reproduce experiments in the laboratory, having better scientificity.

Description

Technical Field

[0001] The present invention belongs to the technical field of railway transportation safety assurance, and relates to a design method of a rail impedance simulation disc and a broken rail monitoring equipment test system. Background Art

[0002] The broken rail monitoring equipment is an important device for monitoring the integrity of rails. Its application is one of the important links to ensure railway transportation safety. It is essential to conduct functional tests on the broken rail detection equipment before it is put into use.

[0003] However, using the existing line to test the broken rail detection equipment will consume a large amount of manpower and material resources and affect the on-site operation; using the existing ordinary rail simulation disc for testing ignores the inductive characteristics of the rail, ignores the relationship between the rail impedance and the electrical signal frequency, lacks theoretical basis, and the ordinary simulation disc lacks accuracy and scientificity.

[0004] Therefore, it is necessary to study a more scientific, accurate, and easy-to-use test method and system for broken rail monitoring equipment. Summary of the Invention

[0005] In order to solve the pain points of on-site testing and using ordinary rail simulation discs for testing, the present invention combines on-site experience data and theoretical derivation to construct a more scientific, accurate, and easy-to-use rail impedance simulation disc.

[0006] The technical solution of the present invention is a design method of a rail impedance simulation disc. The key lies in dividing the rail impedance into two parts: the equivalent resistance of the rail and the equivalent inductance of the rail, respectively calculating the above-mentioned equivalent resistance and equivalent inductance of the rail by using the correlation between resistance and inductance and frequency, and correcting according to the data obtained from standard regulations or on-site collection to obtain a rail impedance equivalent model. The specific steps of obtaining the above-mentioned rail impedance equivalent model include:

[0007] S1. Calculation of the equivalent resistance of the rail:

[0008] The equivalent resistance of the rail is calculated by Equation 1, and Equation 1 is:

[0009]

[0010] In Equation 1, R is the value of the equivalent resistance of the rail, k1 is the resistance correction coefficient, ρ is the resistivity of the rail, l is the length of the rail, μ is the magnetic permeability of the rail, f is the frequency, and C is the perimeter of the rail;

[0011] S2. Calculation of the equivalent inductance of the rail:

[0012] The equivalent inductance of the rail is calculated by Equation 2, and Equation 2 is:

[0013]

[0014] In Equation 2, L is the equivalent inductance value of the rail, k2 is the inductance correction coefficient, μ0 is the permeability of free space, μ is the permeability of the rail, ρ is the resistivity of the rail, f is the frequency, and D is the distance between the rails;

[0015] S3. On-site data collection: Use the collection equipment to collect the impedance value of the rail;

[0016] S4. Parameter correction:

[0017] Draw the theoretical resistance-frequency curve and the theoretical inductance-frequency curve, and adjust the magnitudes of k1 and k2 so that the above-mentioned theoretical resistance-frequency curve and the above-mentioned theoretical inductance-frequency curve approach the collected point values.

[0018] Furthermore, the specific process of Step S1 is as follows:

[0019] Calculate the resistance R of two rails according to Equation 3. Equation 3 is:

[0020]

[0021] In Equation 3, k1 is the resistance correction coefficient, ρ is the resistivity of the rail, l is the length of the rail, and A is the cross-sectional area of the current flowing through the rail;

[0022] Calculate the skin depth δ according to Equation 4. Equation 4 is:

[0023]

[0024] In Equation 4, μ is the permeability of the rail, and f is the frequency;

[0025] Calculate the cross-sectional area A of the current flowing through the rail according to Equation 5. Equation 5 is:

[0026] A = C·δ Equation 5,

[0027] In Equation 5, C is the perimeter of the rail;

[0028] From the above-mentioned Equation 3, Equation 4, and Equation 5, the change of resistance with frequency is derived as Equation 1.

[0029] Even further, the specific process of Step S2 is as follows:

[0030] Approximate the rail as two parallel long straight wires, and calculate the magnetic induction intensity B at x, which is expressed by Equation 6. Equation 6 is:

[0031]

[0032] In Equation 6, μ0 is the permeability of free space, I is the magnitude of the current in the rail, and D is the distance between the rails;

[0033] Take a small rectangle with length h and width dx at x. Then its area is dS = hdx. The magnetic flux Φ at x is expressed by Equation 7, and Equation 7 is:

[0034]

[0035] In Equation 7, r is the equivalent radius of the rail;

[0036] According to the self-inductance formula 8: For the equivalent radius r of the rail, approximately take the skin depth δ to obtain Equation 2.

[0037] Specifically, the above-mentioned correction according to the standard regulations is carried out in the ballast subgrade scenario, and the correction is carried out according to the values specified in the standard TB / T3206 - 2017.

[0038] More specifically, in the S3 step, the method for collecting data is the double short-circuit method.

[0039] A test system for a broken rail monitoring device, which is characterized in that the above-mentioned test system includes a test device and a device under test composed of a rail impedance simulation panel and a rail fracture simulation module obtained according to the above-mentioned design method. The above-mentioned device under test is a broken rail monitoring device to be detected.

[0040] Specifically, the above-mentioned rail impedance simulation panel is composed of a frequency collector, an equivalent impedance calculator, an active programmable resistor, and an active programmable inductor.

[0041] More specifically, the input end of the above-mentioned frequency collector is connected to the first output end of the device under test to collect the electrical signal sent by the device under test. The output end of the above-mentioned frequency collector is connected to the input end of the above-mentioned equivalent impedance calculator to output a frequency value;

[0042] The above-mentioned equivalent impedance calculator calculates the equivalent resistance value and equivalent inductance value of the rail through the mutual relationship between the frequency value and the resistance and inductance. The equivalent resistance value of the rail is transmitted to the first input end of the active programmable resistor through the first output end of the equivalent impedance calculator, and the equivalent inductance value of the rail is transmitted to the first input end of the active programmable inductor through the second output end of the equivalent impedance calculator;

[0043] The second input end of the above-mentioned active programmable resistor is connected to the second output end of the device under test, and the output end of the above-mentioned active programmable resistor is connected to the second input end of the above-mentioned active programmable inductor;

[0044] The output end of the above-mentioned active programmable inductor is connected to the input end of a circuit opening and closing controller that can simulate the fracture and integrity of the rail. The output end of the above-mentioned circuit opening and closing controller is connected to the input end of the device under test.

[0045] The beneficial effects of the present invention are as follows:

[0046] The present invention is a new method for testing in an equipment laboratory. When using the rail impedance simulation board designed by the present invention to test the broken rail monitoring equipment, it can utilize the equivalent impedance to simulate the impedance electrical characteristics of the actual rail. It has the following advantages:

[0047] 1. The present invention realizes the simulation of the real rail by simulating the rail impedance. Using laboratory testing technology, compared with on-site testing, it greatly reduces the consumption of manpower and material resources, reduces the impact on on-site operations, and improves the testing efficiency;

[0048] 2. When calculating the rail impedance, the present invention takes into account the influence of frequency on the impedance. When calculating the equivalent impedance, it is based on the theoretical formula and adjusts the parameters in combination with the on-site measured data. This method combines the theoretical formula with the empirical value, and the calculation process is relatively simple.

[0049] 3. The rail impedance simulation board of the present invention makes the testing environment have better stability, reduces the influence of on-site uncontrollable factors on the test results, is not affected by environmental factors such as on-site weather and temperature, and is easier to conduct repeated experiments and experiment reproduction in the laboratory.

[0050] 4. The rail impedance simulation board of the present invention has good automation. It can automatically perform frequency analysis, processing, and operation on the input electrical signal, and then automatically adjust the resistance and inductance, improving the usability of the rail impedance simulation board when used for testing the broken rail detection equipment.

[0051] 5. The present invention is more scientific than the method of fitting curves by the machine learning regression algorithm. The method of fitting curves by the machine learning regression algorithm has inexplicability. When facing "bad values", this method cannot handle them correctly and there is an overfitting problem. However, the method in the present invention will not be affected by individual incorrect data when dealing with the "bad value" problem and can still obtain the same effect as when there is no "bad value" when adjusting the parameters k1 and k2, which is more scientific. Description of the Drawings

[0052] Figure 1 It is the test schematic diagram of the broken rail monitoring system of the present invention.

[0053] Figure 2 It is the schematic diagram of on-site data collection in the embodiment of the present invention.

[0054] Figure 3 It is the theoretical resistance-frequency curve graph drawn in the embodiment of the present invention.

[0055] Figure 4 It is the theoretical inductance-frequency curve graph drawn in the embodiment of the present invention.

[0056] Figure 5The resistance - frequency curve fitted by machine learning in the comparative example of the present invention.

[0057] Figure 6 The inductance - frequency curve fitted by machine learning in the comparative example of the present invention. Specific embodiments

[0058] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0059] For the parameters and their meanings involved in this embodiment, refer to Table 1.

[0060] Table 1: Parameter and corresponding meaning comparison table

[0061]

[0062]

[0063] In this embodiment, a rail impedance simulation disc is designed, and a broken rail monitoring equipment test system is constructed. The specific steps are as follows:

[0064] S1. Calculation of the equivalent resistance of the rail.

[0065] When an electrical signal propagates in a rail, there is a skin effect, and the skin effect increases with the increase of the electrical signal frequency. The rail is approximated as a long straight wire, and the resistance of two rails with a length of l can be calculated by Equation 3 below:

[0066]

[0067] Define the skin depth δ: the magnitude of the current density here is 1 / e of the magnitude of the surface current density, and Equation 4 is obtained:

[0068]

[0069] Then, according to Equation 5, calculate the cross - sectional area A of the current flowing through the rail:

[0070] A = C·δ Equation 5;

[0071] Based on Equations 3 - 5, it is deduced that the resistance changes with frequency, that is, Equation 1:

[0072]

[0073] S2. Calculation of the equivalent inductance of the rail:

[0074] The rail is approximately regarded as two parallel long straight wires. The magnetic induction intensity at x is represented by 6, and Equation 6 is as follows:

[0075]

[0076] At x, a small rectangle with length h and width dx is taken, and its area is dS = hdx. Then the magnetic flux at x is represented by Equation 7, and Equation 7 is as follows:

[0077]

[0078] The self-inductance formula 8 is as follows:

[0079]

[0080] For the equivalent radius r of the rail, due to the skin effect, the skin depth δ can be approximately taken;

[0081] Similarly, considering on-site actual situations including ground electromagnetic rebound, temperature and humidity changes, and different rail and ballast materials, multiplying by the correction factor k2, the calculation formula for the inductance varying with frequency is obtained, which is represented by Equation 2:

[0082]

[0083] S3. On-site data collection:

[0084] Select a rail section without turnout structure, single ballast bed, not equipped with track circuit and with a length of several hundred meters. Using the double-short circuit method, the frequency of the signal sent by the acquisition device changes from 50 Hz to 20,000 Hz, with an interval of 100 Hz, and the impedance values of the rail at the above sampling frequencies are collected.

[0085] The specific method is as follows: Use the MR200 multi-impedance comprehensive analyzer for rails as the test equipment and connect it to the two-side rails using clamps. As shown in the attachment Figure 2 As shown, the rail is evenly divided into four sections, each with a length of l. Use a grinding machine to grind the two ends of each section and connect the fixtures so that the rail can be in reliable contact with the fixtures. First, perform the open-circuit operation shown in the upper sub-figure according to the prompts on the MR200 device interface, and then perform the short-circuit operation shown in the lower sub-figure. The MR200 device can automatically complete the measurement of the rail impedance and display the measured value on the display interface.

[0086] S4. Parameter correction:

[0087] Use MATLAB software to plot graphs. According to the resistance-frequency and inductance-frequency values collected in a certain environmental scenario or specified in the standard TB / T 3206-2017, respectively plot the theoretical resistance-frequency curve and the theoretical inductance-frequency curve, and adjust the magnitudes of k1 and k2 so that the two theoretical curves are as close as possible to the collected point values.

[0088] In this example, the rail impedance data laid in the section between Dali Xiangyun Station is adopted. The double short-circuit method described above is used as the acquisition method on site. The theoretical resistance-frequency and on-site data curves, and the theoretical inductance-frequency and on-site data curves are obtained. See Appendix Figure 3 and Appendix Figure 4 .

[0089] Figure 3 and Figure 4 where k1 = 0.79 and k2 = 2.53 in

[0090] S5. Fabrication of the rail impedance simulation panel:

[0091] Based on the steps S1 - S4, the equivalent model of the rail impedance is obtained, that is, the theoretical resistance-frequency curve and the theoretical inductance-frequency curve. This model is continuous and can provide complete resistance-frequency, inductance, and frequency data. Based on this, the rail impedance simulation panel is fabricated.

[0092] The rail impedance simulation panel consists of a frequency collector, an equivalent impedance calculator, an active programmable resistor, and an active programmable inductor. The connection method can refer to Appendix Figure 1 .

[0093] The rail break monitoring device to be tested is the device to be tested, which can send an electrical signal of a certain frequency. The frequency collector collects the electrical signal, outputs the frequency value and sends it to the equivalent impedance calculator. The equivalent impedance calculator calculates the equivalent resistance according to the frequency of the input electrical signal based on Formulas 1 and 2 and sends it to the active programmable resistor, and calculates the equivalent inductance number and sends it to the active programmable inductor. The active programmable resistor adjusts its own resistance value according to the received resistance value, and the active programmable inductor adjusts its own inductance value according to the received inductance value.

[0094] The current signal passes through the active programmable resistor and the active programmable inductor, which is equivalent to connecting to the rail with the equivalent impedance.

[0095] The rail break simulator module realizes the simulation of rail break and integrity by controlling the opening and closing of the circuit.

[0096] Comparative Example 1

[0097] Taking the device to be tested in the embodiment as the test object, the on-site test is used to replace the laboratory test of the present invention. For the on-site test, it is necessary to go to the unopened railway site, select a rail section without turnout structure, single ballast bed, without track circuit installed and with a length of several hundred meters, connect the device to be tested to the rail, and test the detection performance of the device to be tested by artificially creating rail damage and other means.

[0098] The test conditions of this comparative example are harsh, consuming a large amount of manpower and material resources, and having a certain impact on the on-site construction and operation.

[0099] Comparative Example 2

[0100] For processes S1 and S2, using the device under test in the embodiment as the test object, a machine learning regression algorithm is used to fit the rail impedance-frequency curve, and values are taken on the curve as the rail impedance. The fitting results are shown in the appendix Figure 5 and the appendix Figure 6 .

[0101] The curve fitted by the machine learning regression algorithm is a data-based method and has non-interpretability. As shown in the appendix Figure 5 and the appendix Figure 6 , the curve fitted by the machine learning method used cannot correctly handle "bad values" and has an overfitting problem. However, when dealing with the above problems, the method in the present invention is based on a theoretical formula and will not be affected by individual incorrect data in impedance calculation. The same effect as when there are no "bad values" can still be obtained when adjusting parameters k1 and k2, which is more scientific.

[0102] Comparative Example 3

[0103] For processes S3 and S5, using the device under test in the embodiment as the test object, the frequency values of the electrical signals output by the device under test are manually collected and measured, and the rail impedance is calculated using Equations 1 and 2. The resistance value and inductance value are manually adjusted or the resistor and inductor are replaced.

[0104] Compared with the process described in the present invention, this comparative example adds operations of manual collection, measurement, and adjustment, resulting in lower experimental efficiency. There is a greater possibility of mistakes by the experimenter during the operation process, and higher requirements are imposed on the experimenter.

Claims

1. A design method for a rail impedance simulation board, characterized in that, The rail impedance is divided into two parts: the equivalent resistance of the rail and the equivalent inductance of the rail. The equivalent resistance and equivalent inductance of the rail are calculated by using the correlations between resistance / inductance and frequency respectively, and are corrected according to the data obtained from standard regulations or on-site collection, so as to obtain an equivalent model of rail impedance. Making a rail impedance simulation panel according to the equivalent model of rail impedance, the specific steps of the equivalent model of rail impedance include: S1. Calculation of the equivalent resistance of the rail: The equivalent resistance of the rail is calculated by Equation 1, and Equation 1 is: Formula 1, In Equation 1 R is the equivalent resistance value of the rail, is the resistance correction coefficient, is the resistivity of the rail, is the length of the rail, and µ is the magnetic permeability of the rail, is the frequency, C is the perimeter of the rail; S2. Calculation of the equivalent inductance of the rail: The equivalent inductance of the rail is calculated by Equation 2, and Equation 2 is: Formula 2, In Equation 2 L is the equivalent inductance value of the rail, k 2 is the inductance correction factor, is the permeability of free space, and µ is the permeability of the rail, is the resistivity of the rail, is the frequency, D is the distance between the rails; S3. On-site data collection: Use the collection device to collect the impedance value of the rail; S4. Parameter correction: Draw the theoretical curves of resistance - frequency and inductance - frequency, and adjust according to the data or standards collected in step S3 k 1 、 k 2 the magnitudes so that the theoretical curves of resistance - frequency and inductance - frequency approximate the values of the collected points; The specific process of Step S2 is: Approximate the rail as two parallel long straight wires and calculate x the magnetic induction intensity at B , which is expressed by Equation 6. Equation 6 is as follows: Formula 6, In Equation 6, is the permeability of free space, I is the magnitude of the current in the rail, D is the distance between the rails; At x take a small rectangle with a length of h and a width of dx , then its area is , then x the magnetic flux at is expressed by Equation 7, and Equation 7 is: Formula 7, In Equation 7, r is the equivalent radius of the rail; According to the self-inductance formula 8: , for the equivalent radius r of the steel rail, approximately take the skin depth δ , and obtain Equation 2.

2. The design method of a rail impedance simulation board according to claim 1, characterized in that The specific process of Step S1 is: Calculate the resistances of two rails according to Equation 3 R , where Equation 3 is as follows: Formula 3, In Equation 3, k 1 is the resistance correction coefficient, is the resistivity of the rail, is the length of the rail, A is the cross-sectional area of the current flowing through the rail; Calculate the skin depth according to Equation 4 δ , and Equation 4 is as follows: Formula 4, In Equation 4, μ is the magnetic permeability of the rail, is the frequency; Calculate the cross-sectional area of the current flowing through the rail according to Equation 5 A , Equation 5 is as follows: Formula 5, In Formula 5, C is the perimeter of the rail; From the above-mentioned Equations 3, 4 and 5, the change of resistance with frequency is deduced to be Equation 1.

3. The design method of a rail impedance simulation panel according to claim 1, characterized in that, The correction according to the standard regulations is carried out in the ballast subgrade scenario according to the values specified in Standard TB / T 3206-2017.

4. The design method of a rail impedance simulation disc according to claim 1, characterized in that In Step S3, the method of collecting data is the double short-circuit method.

5. A broken rail monitoring device test system, characterized in that, The test system includes a test device and a device under test composed of a rail impedance simulation panel and a rail fracture simulation module obtained by the design method according to any one of Claims 1-4, and the device under test is a broken rail monitoring device to be detected.

6. The test system for a broken rail monitoring device according to claim 5, wherein, The rail impedance simulation panel is composed of a frequency collector, an equivalent impedance calculator, an active programmable resistor and an active programmable inductor.

7. The test system for a broken rail monitoring device according to claim 6, characterized in that, The input end of the frequency collector is connected to the first output end of the device under test to collect the electrical signal sent by the device under test, and the output end of the frequency collector is connected to the input end of the equivalent impedance calculator to output the frequency value; The equivalent impedance calculator calculates the equivalent resistance value and equivalent inductance value of the rail through the mutual relationship between the frequency value and resistance / inductance, and transmits the equivalent resistance value of the rail to the first input end of the active programmable resistor through the first output end of the equivalent impedance calculator, and transmits the equivalent inductance value of the rail to the first input end of the active programmable inductor through the second output end of the equivalent impedance calculator; The second input end of the active programmable resistor is connected to the second output end of the device under test, and the output end of the active programmable resistor is connected to the second input end of the active programmable inductor; The output end of the active programmable inductor is connected to the input end of a circuit opening and closing controller capable of simulating rail fracture and integrity, and the output end of the circuit opening and closing controller is connected to the input end of the device under test.

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