CN109782136B - Method for determining defect position of contact net based on longitudinal wave and transverse wave speed difference - Google Patents
Method for determining defect position of contact net based on longitudinal wave and transverse wave speed difference Download PDFInfo
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- CN109782136B CN109782136B CN201811615587.1A CN201811615587A CN109782136B CN 109782136 B CN109782136 B CN 109782136B CN 201811615587 A CN201811615587 A CN 201811615587A CN 109782136 B CN109782136 B CN 109782136B
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Abstract
The invention discloses a method for determining the defect position of a contact net based on the difference of longitudinal wave and transverse wave speeds, which comprises the following steps: s1, determining the time difference of arrival of longitudinal waves and transverse waves at a defect position at a detection point; and S2, calculating the distance between the defect position and the detection point. Specifically, the propagation time difference between the longitudinal wave and the transverse wave is obtained by selecting the maximum amplitude of the longitudinal wave in a plurality of certain time periods and corresponding to the time point when the longitudinal wave is matched with the transverse wave for a plurality of times, so that the distance between the defect position and the detection point is determined, the accurate positioning of the defect position is realized, the efficiency is improved, and the cost is reduced.
Description
Technical Field
The invention relates to the technical field of contact networks, in particular to a method for determining the defect position of a contact network based on the difference of longitudinal wave and transverse wave speeds.
Background
The overhead contact system is a high-voltage transmission line which is erected along a zigzag shape above a steel rail in an electrified railway and is used for a pantograph to draw current. The overhead contact system is a main framework of the railway electrification engineering and is a special power transmission line which is erected along a railway line and supplies power to an electric locomotive. The quality and the working state of a contact network directly influence the transportation capacity of an electrified railway, so that the contact network is required to be capable of guaranteeing that electric energy is well supplied to an electric locomotive no matter under any condition, the electric locomotive is guaranteed to run safely and at high speed on a line, investment is saved as far as possible under the condition that the requirements are met, the structure is reasonable, the maintenance is simple and convenient, a vibration sensor is usually installed at the anchoring position of the contact network, the defects of hard points, cracks and the like of the contact line can be monitored according to detection data of the vibration sensor, but the defect can only be determined at which anchoring section, and the position of the defect cannot be accurately determined. The potential defects are possibly analyzed, but the accurate positions of the defects cannot be determined, so that a great amount of time is spent for confirming the positions of the defects when a maintenance worker overhauls the defects on site, the defects are not easy to find, and even the defects cannot be found, and a great amount of manpower and material resources are wasted.
Disclosure of Invention
The invention aims to provide a method for determining the defect position of a contact net based on the speed difference of longitudinal waves and transverse waves.
The above object of the present invention is achieved by the following technical solutions:
a method for determining the defect position of a contact net based on the difference of longitudinal wave and transverse wave speeds comprises the following steps:
s1, determining the time difference between the propagation of longitudinal waves and transverse waves at the defect position and the arrival of the longitudinal waves and the transverse waves at the detection point;
and S2, calculating the distance between the defect position and the detection point.
The invention is further configured to: in step S1, the method includes the steps of:
a1, selecting sampling data in K first time durations, and solving a longitudinal wave amplitude average value and a transverse wave amplitude average value in each first time duration;
a2, selecting the position where the maximum value of the longitudinal wave amplitude average value is located as a first position i, and marking the corresponding time as a first time t 1;
a3, at the first position i, calculating a first longitudinal wave amplitude average value and a first transverse wave amplitude average value in M continuous second time durations, sequentially obtaining a ratio of the first longitudinal wave amplitude average value to the first transverse wave amplitude average value, and calculating a mean square error delta 1 of all the ratios;
a4, after moving forward or backward for a second time length, re-calculating the second transverse wave amplitude average value of M continuous second time lengths, sequentially obtaining the ratio of the first longitudinal wave amplitude average value to the second transverse wave amplitude average value, and calculating the mean square error delta 2 of all the ratios;
a5, repeating the step A4 until the time corresponding to all M continuous second time duration exceeds the time required by the sound to propagate the whole anchor segment;
a6, selecting the minimum mean square error delta min of all the mean square errors;
a7, when the minimum mean square error δ min is smaller than a set value, the transverse wave at the time t2 and the longitudinal wave at the first time t1 are considered to be vibration waves of the same vibration source;
a8, a time difference between the first time t1 and the time t2 is the propagation time difference d between the longitudinal wave and the transverse wave.
The invention is further configured to: the value range of M is less than 200, and the value range of K is less than 100.
The invention is further configured to: the value of M is equal to 50.
The invention is further configured to: the first duration is equal to the second duration.
The invention is further configured to: m continuous second time lengths are selected at the first position, and M/2 second time lengths are selected before and after the first position respectively.
The invention is further configured to: the first or second duration is no more than 0.3 seconds.
The invention is further configured to: and when the minimum mean square error delta min is larger than or equal to a set value, the selected sampling data is considered as an interference signal and discarded, and the sampling data is reselected for analysis.
The invention is further configured to: and at the time t2, selecting a third time length to repeat the steps A4-A7, wherein the third time length is smaller than the second time length, and the positioning accuracy is improved.
The invention is further configured to: in step S2, the distance S between the defect position and the detection point is obtained by the following equation:
S=v1*v2*d/(v1-v2)
where v1 represents the propagation velocity of the longitudinal wave; v2 represents the propagation velocity of the transverse wave, and d represents the propagation time difference between the longitudinal wave and the transverse wave.
In conclusion, the beneficial technical effects of the invention are as follows:
1. according to the method, the defect position is accurately determined through the propagation time difference of the longitudinal wave and the transverse wave of the same vibration source, the efficiency is improved, the investment of manpower and material resources is reduced, and the cost is reduced;
2. furthermore, the invention obtains the accurate time difference of the transverse wave and the longitudinal wave by comparing the sampling signals in the time domain, thereby improving the accuracy of defect position judgment.
3. Furthermore, the invention not only reduces the calculation amount, but also ensures the positioning precision by further carrying out accurate positioning after coarse positioning.
Drawings
FIG. 1 is a schematic flow chart of a method according to an embodiment of the present invention.
FIG. 2 is a schematic diagram illustrating a process for determining a propagation time difference between longitudinal and transverse waves according to an embodiment of the present invention.
FIG. 3 is a schematic diagram of longitudinal and transverse wave waveforms in accordance with an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings.
The invention discloses a method for determining the defect position of a contact net based on the difference of longitudinal wave and transverse wave speeds, a flow chart of which is shown in figure 1, and the method comprises the following steps:
s1, determining the time difference between the propagation of longitudinal waves and transverse waves at the defect position and the arrival of the longitudinal waves and the transverse waves at the detection point;
and S2, calculating the distance between the defect position and the detection point.
When in vibration sampling, the transverse wave and the longitudinal wave of vibration are simultaneously collected, wherein the transverse wave refers to the vibration vertical to the surface of the lead, and the longitudinal wave refers to the vibration parallel to the direction of the lead; assuming that the propagation speed of the longitudinal wave is v1 and the propagation time is t 1; the propagation speed of the transverse wave is v2, and the propagation time is t 2; the propagation speeds of the longitudinal wave and the transverse wave are mainly related to materials and temperature, and can be measured in advance.
The propagation times t1 and t2 cannot be directly measured, but since the longitudinal wave and the transverse wave correspond to the same defect position, that is, the time when the longitudinal wave and the transverse wave are generated is the same, the time difference d between the longitudinal wave and the transverse wave can be measured, and t2= t1+ d.
For a defect, the "amplitude-time" characteristics of the shear wave and the longitudinal wave are similar, as shown in fig. 3, and the same vibration source (i.e., defect location) is found in the shear wave and the longitudinal wave data, as shown in fig. 2, and the following steps are included:
a1, selecting sampling data in K first time durations, and solving a longitudinal wave amplitude average value and a transverse wave amplitude average value in each first time duration;
a2, selecting the position where the maximum value of the longitudinal wave amplitude average value is located as a first position i, and marking the corresponding time as a first time t 1;
a3, at the first position i, calculating a first longitudinal wave amplitude average value and a first transverse wave amplitude average value in M continuous second time durations, sequentially obtaining a ratio of the first longitudinal wave amplitude average value to the first transverse wave amplitude average value, and calculating a mean square error delta 1 of all the ratios;
a4, after moving back for a second time length, re-calculating a second transverse wave amplitude average value of M continuous second time lengths, sequentially obtaining the ratio of the first longitudinal wave amplitude average value to the second transverse wave amplitude average value, and calculating the mean square error delta 2 of all the ratios;
a5, repeating the step A4 until the time corresponding to all M continuous second time duration exceeds the time required by the sound to propagate the whole anchor segment;
a6, selecting the minimum mean square error delta min of all the mean square errors;
a7, when the minimum mean square error δ min is smaller than a set value, the transverse wave at the time t2 and the longitudinal wave at the first time t1 are considered to be vibration waves of the same vibration source;
a8, a time difference between the first time t1 and the time t2 is the propagation time difference d between the longitudinal wave and the transverse wave.
In a specific embodiment of the present invention, sampling data in K time periods in the vibration sampling database is selected, that is, the sampling database is windowed, that is, the first windows, where the time tk of each first window is the same, the first windows are dispersed in the sampling database, and the average value of the amplitude of the longitudinal wave in each first window is obtained, and the average values are respectively labeled as f1, f 2. Selecting a position i with the maximum longitudinal wave amplitude average value from the position i, wherein the corresponding time is t1, then taking M continuous second windows before and after the time t1, wherein the time tm of each second window is the same, respectively calculating the longitudinal wave amplitude average value fm and the transverse wave amplitude average value hm of the sampled data in the M windows, and respectively marking as: fm (1), fm (2),. fm (m), hm (1), hm (2), and so (hm) (m), wherein the average value of the amplitude of the longitudinal wave and the average value of the amplitude of the transverse wave with the same serial number are sequentially divided to obtain a longitudinal wave amplitude ratio p1, which is p11= fm (1)/hm (1), p12= fm (2)/hm (2), and so 1m = fm (m)/hm (m), and then all the longitudinal wave amplitude ratios p1 are subjected to mean square error operation to obtain a first mean square error δ 1.
The M connected second windows are selected at time t1, and preferably M/2 connected second windows are selected before and after time t1, respectively.
Moving the sampling data of the transverse wave backward by a second window time tm, recalculating a transverse wave amplitude average value which is respectively marked as hm (2),. hm (m), and hm (m +1), sequentially dividing the longitudinal wave amplitude average value at the time t1 and the transverse wave amplitude average value at the time t1+ tm to obtain a transverse wave amplitude ratio p2 which is respectively p21= fm (1)/hm (2), p22= fm (2)/hm (3),. p2m = fm (m)/hm (m +1), and then performing mean square operation on all the transverse wave amplitude ratios p2 to obtain a second mean square difference δ 2;
and by analogy, q times of mean square error operation are calculated to obtain a q-th mean square error delta q, the value of q is determined by the time T required by sound to propagate in the whole anchor section, and if the length of the anchor section is G meters and the minimum speed of sound propagation is 3000 meters per second, the time T = G/3000 required by sound to propagate in the anchor section is obtained, so that q = T/tm is obtained.
The minimum mean square deviation δ min is obtained for q mean square deviations δ 1 and δ 2 … δ q, when the mean square deviation δ min is smaller than a set value, the transverse wave at the moment and the longitudinal wave at the moment t1 are considered to be generated by the same vibration source, the moment corresponding to the mean square deviation δ min is recorded as t2, and the time difference d = t2-t1 between the longitudinal wave and the transverse wave reaching a detection point.
Preferably, the length of the anchor segment is G =1500 meters, and T is max 0.5 seconds. If tm is selected to be 10 ms, the above calculation is performed, and the positioning accuracy is about 75 m, which is a coarse positioning.
After the coarse positioning, the window time tm is reduced, for example, to 1 ms, and the above calculation is performed around the aforementioned time t2, so that the positioning accuracy can be achieved to about 7.5 m.
And when the mean square error delta min is larger than or equal to a set value, considering the current sampling data as an interference signal, discarding the interference signal, and reselecting the sampling data for analysis.
Preferably, the value range of M is less than 200, and the value range of K is less than 100.
Further, M is equal to 50.
After the propagation time difference d between the longitudinal wave and the transverse wave is obtained, the distance S between the defect position and the detection point is calculated:
S=v1*t1
S=v2*t2
solving to obtain:
S=v1*v2*d/(v1-v2)。
from this equation, it can be seen that the accuracy of the distance between the defect position and the detection point is determined by the measurement accuracy of the propagation velocity of the longitudinal wave and the transverse wave and the measurement accuracy of the time difference d.
The embodiments of the present invention are preferred embodiments of the present invention, and the scope of the present invention is not limited by these embodiments, so: all equivalent changes made according to the structure, shape and principle of the invention are covered by the protection scope of the invention.
Claims (9)
1. A method for determining the defect position of a contact net based on the difference of longitudinal wave and transverse wave speeds is characterized by comprising the following steps: the method comprises the following steps:
s1, selecting sampling data in K first window time periods in a vibration sampling database, obtaining a longitudinal wave amplitude average value of each first window, selecting the maximum position of the longitudinal wave amplitude average value as a first moment, obtaining M continuous second windows before and after a t1 moment in total, obtaining the mean square error of the longitudinal wave amplitude proportion of all the second windows, moving the M continuous second window positions, obtaining the mean square error of a plurality of longitudinal wave amplitude proportions, selecting the minimum of all the mean square errors, and determining the time difference of arrival of the longitudinal wave and the transverse wave at a defect position at a detection point according to the second moment and the first moment when the minimum mean square error is smaller than a set value as the second moment;
s2, calculating the distance S between the defect position and the detection point according to the time difference and the longitudinal and transverse wave propagation speeds, and obtaining the distance S according to the following formula:
S＝v1*v2*d/(v1-v2)
where v1 represents the propagation velocity of the longitudinal wave; v2 represents the propagation velocity of the transverse wave, and d represents the propagation time difference between the longitudinal wave and the transverse wave.
2. The method of claim 1, wherein: in step S1, the method includes the steps of:
a1, selecting sampling data in K first time durations, and solving a longitudinal wave amplitude average value and a transverse wave amplitude average value in each first time duration;
a2, selecting the position of the maximum value of the longitudinal wave amplitude average value as a first position i, and marking the corresponding time as a first time t 1;
a3, at the first position i, calculating a first longitudinal wave amplitude average value and a first transverse wave amplitude average value in M continuous second time durations, sequentially obtaining a ratio of the first longitudinal wave amplitude average value to the first transverse wave amplitude average value, and calculating a mean square error delta 1 of all the ratios;
a4, after moving forward or backward for a second time length, re-calculating the second transverse wave amplitude average value of M continuous second time lengths, sequentially obtaining the ratio of the first longitudinal wave amplitude average value to the second transverse wave amplitude average value, and calculating the mean square error delta 2 of all the ratios;
a5, repeating the step A4 until the time corresponding to all M continuous second time duration exceeds the time required by the sound to propagate the whole anchor segment;
a6, selecting the minimum mean square error delta min of all the mean square errors;
a7, when the minimum mean square error δ min is smaller than a set value, the transverse wave at the time t2 and the longitudinal wave at the first time t1 are considered to be vibration waves of the same vibration source;
a8, a time difference between the first time t1 and the time t2 is the propagation time difference d between the longitudinal wave and the transverse wave.
3. The method of claim 2, wherein: the value range of M is less than 200, and the value range of K is less than 100.
4. The method of claim 3, wherein: the value of M is equal to 50.
5. The method of claim 2, wherein: the first duration is equal to the second duration.
6. The method of claim 2, wherein: m continuous second time lengths are selected at the first position, and M/2 second time lengths are selected before and after the first position respectively.
7. The method of claim 2, wherein: the first or second duration is no more than 0.3 seconds.
8. The method of claim 2, wherein: and when the minimum mean square error delta min is larger than or equal to a set value, the selected sampling data is considered as an interference signal and discarded, and the sampling data is reselected for analysis.
9. The method of claim 2, wherein: and at the time t2, selecting a third time length to repeat the steps A4-A7, wherein the third time length is less than the second time length, and the positioning accuracy is improved.
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