Design method of steel rail impedance simulation disc and broken rail monitoring equipment test system

Abstract

The invention discloses a design method of a steel rail impedance simulation disc and a broken rail monitoring equipment test system, and the method comprises the steps: dividing the steel rail impedance into steel rail equivalent resistance and steel rail equivalent inductance, and calculating the steel rail equivalent resistance and steel rail equivalent inductance through the correlation between the resistance and the frequency and the correlation between the inductance and the frequency; correcting according to standard regulation or data acquired on site to obtain a steel rail impedance equivalent model, and manufacturing a steel rail impedance simulation disc according to the obtained steel rail impedance equivalent model; a test device composed of a steel rail impedance simulation disc and a steel rail fracture simulation module and a tested device jointly form a broken rail monitoring device test system. According to the invention, the simulation of the real steel rail is realized by adopting the simulation steel rail impedance, the laboratory test technology is utilized, the consumption of manpower and material resources is reduced, the test efficiency is improved, repeated experiments and experiment reproduction are easier to carry out in a laboratory, and the method has better scientificity.

Description

Technical Field

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

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

[0003] However, using existing lines to test broken rail detection equipment will consume a lot of manpower and material resources, affecting on-site operations; using existing ordinary rail simulation disks for testing ignores the inductive characteristics of the rails, the relationship between rail impedance and electrical signal frequency, and lacks a theoretical basis. Ordinary simulation disks lack accuracy and scientificity.

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

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

[0006] The technical solution of the present invention is a design method for a rail impedance simulation disk. The key lies in that the rail impedance is divided into two parts: rail equivalent resistance and rail equivalent inductance. The rail equivalent resistance and rail equivalent inductance are calculated using the correlation between resistance and inductance and frequency, respectively. The rail equivalent resistance and rail equivalent inductance are corrected according to standard regulations or data collected on site to obtain a rail impedance equivalent model. A rail impedance simulation disk is manufactured according to the rail impedance equivalent model. The specific steps of obtaining the rail impedance equivalent model include:

[0007] S1. Calculation of equivalent rail resistance:

[0008] The equivalent resistance of the rail is calculated by formula 1:

[0009]

[0010] In formula 1, R is 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 circumference of the rail;

[0011] S2. Calculation of equivalent rail inductance:

[0012] The equivalent inductance of the rail is calculated by equation 2:

[0013]

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

[0015] S3. On-site data collection: using collection equipment to collect rail impedance values;

[0016] S4. Parameter correction:

[0017] Draw the resistance-frequency theoretical curve and the inductance-frequency theoretical curve, and adjust the values ​​of k1 and k2 so that the above resistance-frequency theoretical curve and the above inductance-frequency theoretical curve are close to the value of the collection point.

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

[0019] The resistance R of the two rails is calculated according to Formula 3, which is:

[0020]

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

[0022] The skin depth δ is calculated according to Formula 4, which is:

[0023]

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

[0025] The cross-sectional area A of the rail through which the current flows is calculated according to Formula 5, which is:

[0026] A=C·δ Formula 5,

[0027] In formula 5, C is the circumference of the rail;

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

[0029] Furthermore, the specific process of step S2 is as follows:

[0030] The rails are approximately regarded as two parallel long straight wires, and the magnetic induction intensity B at x is calculated and expressed by formula 6, which is:

[0031]

[0032] In formula 6, μ0 is the vacuum magnetic permeability, I is the current in the rail, and D is the distance between the rails;

[0033] Take a small rectangle with a length of h and a width of dx at x, then its area is dS = hdx, then the magnetic flux Φ at x is expressed by formula 7, which is:

[0034]

[0035] In formula 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, the skin depth δ is approximated to obtain Equation 2.

[0037] Specifically, the above correction according to the standard provisions is made in the ballasted roadbed scenario according to the values ​​specified in the standard TB / T3206-2017.

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

[0039] A broken rail monitoring equipment testing system, the key lies in that the above-mentioned testing system includes a testing device and a tested device composed of a rail impedance simulation disk and a rail fracture simulation module obtained according to the above-mentioned design method, and the above-mentioned tested device is a broken rail monitoring device to be tested.

[0040] Specifically, the rail impedance simulation disk is composed of a frequency collector, an equivalent impedance operator, an active programmable resistor and an active programmable inductor.

[0041] More specifically, 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 operator to output the frequency value;

[0042] The above-mentioned equivalent impedance operator calculates the equivalent resistance value and the equivalent inductance value of the rail through the relationship between the frequency value and the resistance and the inductance, 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 operator, 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 operator;

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

[0044] The output end of the active programmable inductor is connected to the input end of a circuit switch controller capable of simulating the breakage and integrity of the rail, and the output end of the circuit switch controller is connected to the input end of the device under test.

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

[0046] The present invention is a new method for testing equipment in a laboratory. The rail impedance simulation disk designed by the present invention is used to test the broken rail monitoring equipment, and the impedance electrical characteristics of the actual rail can be simulated by using equivalent impedance. It has the following advantages:

[0047] 1. The present invention uses simulated rail impedance to simulate real rails. Compared with on-site testing, the laboratory testing technology greatly reduces the consumption of manpower and material resources, reduces the impact on on-site operations, and improves testing efficiency.

[0048] 2. The present invention takes into account the influence of frequency on impedance when calculating rail impedance, takes theoretical formula as the basis when calculating equivalent impedance, and adjusts parameters in combination with field measured data. This method combines theoretical formula with empirical values, and the calculation process is relatively simple.

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

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

[0051] 5. The present invention is more scientific than the curve fitting method of machine learning regression algorithm. The curve fitting method of machine learning regression algorithm is unexplainable. This method cannot correctly handle "bad values" and has overfitting problems. However, when dealing with the "bad value" problem, the impedance calculation will not be affected by individual erroneous data. When adjusting the parameters k1 and k2, the same effect can still be obtained as when there is no "bad value", which is more scientific. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 The figure is a test principle diagram of the broken rail monitoring system of the present invention.

[0053] Figure 2 It is a schematic diagram of field data collection according to an embodiment of the present invention.

[0054] Figure 3 This is a resistance-frequency theoretical curve diagram drawn in an embodiment of the present invention.

[0055] Figure 4 This is a theoretical inductance-frequency curve diagram drawn in an embodiment of the present invention.

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

[0057] Figure 6 This is the inductance-frequency curve fitted by machine learning in the comparative example of the present invention. DETAILED DESCRIPTION

[0058] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0059] The parameters and their meanings involved in this embodiment are shown in Table 1.

[0060] Table 1: Parameters and corresponding meanings comparison table

[0061]

[0062]

[0063] This embodiment designs a rail impedance simulation disk and constructs a broken rail monitoring equipment test system. The specific steps are as follows:

[0064] S1. Calculation of equivalent rail resistance.

[0065] When electrical signals propagate in rails, there is a skin effect, which increases with the frequency of the electrical signals. The rails are approximated as long straight wires, and the resistance of two rails with a length of l can be calculated by the following formula 3:

[0066]

[0067] Define skin depth δ: The current density here is 1 / e of the surface current density, and we get equation 4:

[0068]

[0069] According to Formula 5, calculate the cross-sectional area A of the rail through which the current flows:

[0070] A=C·δ Formula 5;

[0071] According to equations 3 to 5, it can be deduced that resistance changes with frequency, that is, equation 1:

[0072]

[0073] S2. Calculation of equivalent rail inductance:

[0074] The rails are approximately viewed as two parallel long straight conductors. The magnetic induction intensity at x is represented by 6, and formula 6 is:

[0075]

[0076] Take a small rectangle with a length of h and a width of dx at x, then its area is dS = hdx, then the magnetic flux at x is expressed by equation 7, which is:

[0077]

[0078] The self-inductance formula 8 is:

[0079]

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

[0081] Similarly, considering the actual conditions on site, including ground electromagnetic rebound, temperature and humidity changes, and different materials of rails and ballast, multiplying the correction factor k2, we get the calculation formula for the change of inductance with frequency, which is expressed as Formula 2:

[0082]

[0083] S3. Field data collection:

[0084] A rail section with no turnout structure, single ballast, no track circuit installed and a length of several hundred meters was selected. The double short-circuit method was used. The sending frequency of the acquisition equipment was changed from 50Hz to 20000Hz with an interval of 100Hz to collect the impedance value of the rail at the above sampling frequency.

[0085] The specific method is: use the MR200 rail multi-impedance comprehensive analyzer as the test equipment, and connect it to the rails on both sides with a clamp. Figure 2 As shown, the rail is evenly divided into four sections, each with a length of l. Use a grinder to grind both ends of each section and connect the fixture to ensure reliable contact between the rail and the fixture. According to the prompts on the MR200 device interface, first perform the open circuit operation shown in the upper sub-diagram, and then perform the short circuit operation in the lower sub-diagram. The MR200 device can automatically complete the rail impedance measurement and display the measured value on the display interface.

[0086] S4. Parameter correction:

[0087] Use MATLAB software to draw the graph. According to the resistance-frequency and inductance-frequency values ​​collected in a certain environment scene or specified in the standard TB / T3206-2017, draw the resistance-frequency theoretical curve and the inductance-frequency theoretical curve respectively, and adjust the values ​​of k1 and k2 so that the two theoretical curves are as close to the collection point values ​​as possible.

[0088] This example uses the rail impedance data of Dali Xiangyun Station section. The double short-circuit method mentioned above is used as the acquisition method on site. The resistance-frequency theory, field data curve and inductance-frequency theory, field data curve are obtained. See the attached Figure 3 and attached Figure 4 .

[0089] Figure 3 and Figure 4 In this case, k1=0.79, k2=2.53.

[0090] S5. Rail impedance simulation disk production:

[0091] According to steps S1 to S4, the rail impedance equivalent model, namely the resistance-frequency theoretical curve and the inductance-frequency theoretical curve, is obtained. The model is continuous and can provide complete resistance-frequency, inductance, and frequency data. Based on this, a rail impedance simulation disk is made.

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

[0093] The broken rail 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 operator. The equivalent impedance operator calculates the equivalent resistance according to the frequency of the input electrical signal and according to formulas 1 and 2 and sends it to the active programmable resistor, and calculates the equivalent inductance 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 a rail with equivalent impedance.

[0095] The rail fracture simulator module simulates the fracture and integrity of the rail by controlling the opening and closing of the circuit.

[0096] Comparative Example 1

[0097] The equipment to be tested in the embodiment is used as the test object, and field testing is used instead of the laboratory test of the present invention. The field test requires going to the unopened railway site, selecting a rail section with no turnout structure, a single ballast, no track circuit installed, and a length of several hundred meters, connecting the equipment to be tested to the rails, and testing the detection performance of the equipment to be tested by artificially creating rail damage.

[0098] The testing conditions for this ratio are harsh, consuming a lot of manpower and material resources, and having a certain impact on on-site construction operations.

[0099] Comparative Example 2

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

[0101] The machine learning regression algorithm curve fitting is a data-based method and is not interpretable. Figure 5 and attached Figure 6 As shown, the curve fitted by machine learning cannot correctly handle "bad values" and has an overfitting problem. When dealing with the above problems, the method in the present invention is based on theoretical formulas and will not affect the impedance calculation due to individual erroneous data. When adjusting parameters k1 and k2, the same effect can still be obtained as when there is no "bad value", which is more scientific.

[0102] Comparative Example 3

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

[0104] Compared with the process described in the present invention, this comparative example adds manual collection, measurement, and adjustment operations, resulting in low experimental efficiency. The experimenter is more likely to make mistakes during the operation, and higher requirements are placed on the experimenter.

Claims

1. A design method for a rail impedance simulation disk, characterized in that: The rail impedance is divided into two parts: rail equivalent resistance and rail equivalent inductance. The rail equivalent resistance and rail equivalent inductance are calculated using the correlation between resistance and inductance and frequency, respectively. The rail equivalent resistance and rail equivalent inductance are corrected according to standard regulations or data collected on site to obtain a rail impedance equivalent model. A rail impedance simulation disk is manufactured according to the rail impedance equivalent model. The specific steps of the rail impedance equivalent model include: S1. Calculation of equivalent rail resistance: The equivalent resistance of the rail is calculated by formula 1: In formula 1, R is 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 circumference of the rail; S2. Calculation of equivalent rail inductance: The equivalent inductance of the rail is calculated by equation 2: In formula 2, L is the equivalent inductance of the rail, k2 is the inductance correction coefficient, μ0 is the vacuum permeability, μ is the rail permeability, ρ is the rail resistivity, f is the frequency, and D is the distance between the rails; S3. On-site data collection: using collection equipment to collect rail impedance values; S4. Parameter correction: Draw a resistance-frequency theoretical curve and an inductance-frequency theoretical curve, and adjust the values ​​of k1 and k2 according to the data or standard collected in step S3, so that the resistance-frequency theoretical curve and the inductance-frequency theoretical curve approach the collection point value.

2. The design method of a rail impedance simulation disk according to claim 1, characterized in that: The specific process of step S1 is as follows: The resistance R of the two rails is calculated according to Formula 3, which is: In formula 3, k1 is the resistance correction coefficient, ρ is the rail resistivity, l is the rail length, and A is the cross-sectional area of ​​the rail through which the current flows; The skin depth δ is calculated according to Formula 4, which is: In formula 4, μ is the magnetic permeability of the rail, and f is the frequency; The cross-sectional area A of the rail through which the current flows is calculated according to Formula 5, which is: A=C·δ Formula 5, In formula 5, C is the circumference of the rail; From the above-mentioned equations 3, 4 and 5, the change of resistance with frequency is derived as equation 1.

3. The design method of a rail impedance simulation disk according to claim 1, characterized in that: The specific process of step S2 is as follows: The rails are approximately regarded as two parallel long straight wires, and the magnetic induction intensity B at x is calculated and expressed by formula 6, which is: In formula 6, μ0 is the vacuum magnetic permeability, I is the current in the rail, and D is the distance between the rails; Take a small rectangle with a length of h and a width of dx at x, then its area is dS = hdx·, then the magnetic flux Φ at x is expressed by formula 7, which is: In formula 7, r is the equivalent radius of the rail; According to the self-inductance formula 8: For the equivalent radius r of the rail, the skin depth δ is approximated to obtain Equation 2.

4. The design method of a rail impedance simulation disk according to claim 1, characterized in that: The correction according to the standard provisions is performed in the ballasted roadbed scenario according to the values ​​specified in the standard TB / T3206-2017.

5. The design method of a rail impedance simulation disk according to claim 1, characterized in that: In the step S3, the method for collecting data is the double short-circuit method.

6. A broken rail monitoring equipment testing system, characterized in that: The test system comprises a test device and a device under test consisting of a rail impedance simulation disk and a rail fracture simulation module obtained by the design method according to any one of claims 1 to 5, wherein the device under test is a broken rail monitoring device to be detected.

7. A broken rail monitoring equipment testing system according to claim 6, characterized in that: The rail impedance simulation disk is composed of a frequency collector, an equivalent impedance operator, an active program-controlled resistor and an active program-controlled inductor.

8. A broken rail monitoring equipment testing system according to claim 7, 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 operator to output the frequency value; The equivalent impedance operator calculates the rail equivalent resistance value and rail equivalent inductance value through the relationship between the frequency value and the resistance and inductance, transmits the rail equivalent resistance value to the first input end of the active program-controlled resistor through the first output end of the equivalent impedance operator, and transmits the rail equivalent inductance value to the first input end of the active program-controlled inductor through the second output end of the equivalent impedance operator; The second input terminal of the active programmable resistor is connected to the second output terminal of the device under test, and the output terminal of the active programmable resistor is connected to the second input terminal of the active programmable inductor; The output end of the active program-controlled inductor is connected to the input end of a circuit switch controller capable of simulating the breakage and integrity of the rail, and the output end of the circuit switch controller is connected to the input end of the device under test.

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