Equivalent uplink and downlink current ratio fault distance measurement method combined with segmented reactance table

Abstract

The invention relates to an equivalent uplink and downlink current ratio fault distance measurement method combined with a segmented reactance table, and the method employs an uplink and downlink current ratio method combined with the segmented reactance table to replace a common reactance ratio method and a common uplink and downlink current ratio method in a current complex line direct supply operation mode for fault distance measurement. The multi-line direct supply traction network is divided into a plurality of sections according to different unit impedance, then the reactance value of each section is calculated according to the impedance and mutual impedance of each section, the method not only can consider the influence of an anti-thunder coil and a power supply line on the distance measurement result, but also can ensure the distance measurement precision when the number of stations is large, and the method is suitable for large-scale popularization and application. The distance measurement error is controlled within the range of 250 meters; maintenance personnel are ensured to quickly find out fault points, timely process faults and recover normal operation of lines, and the method is very important for safe, reliable and efficient transportation of a railway system.

Description

Technical Field

[0001] The invention belongs to the field of fault location of traction substations in electrified railways, and particularly relates to an equivalent up-down line current ratio fault location method combined with a sectional reactance table. Background Art

[0002] With the development of conventional railways, in order to adapt to the longer power supply distance of the traction network and improve the power supply capacity of the line, more and more conventional railways adopt the double-track direct supply method with parallel connection at the end. Even in some lines, in order to increase the traction load, a strengthening wire is added to the catenary in a certain section. For a double-track direct supply traction network with uniform impedance distribution, the traditional up-down line current ratio can basically meet the accuracy requirements of fault location. The traditional up-down line current ratio calculation formula is: , where D is the fault distance, , are the down-line and up-line feeder currents collected by the fault location device during the fault, is the section length.

[0003] However, in actual operation, due to the existence of lightning protection coils, long power supply lines, multiple stations in the section, and the existence of strengthening wires in some sections, the traditional up-down line current ratio method often cannot meet the accuracy requirements of fault location, and the error often reaches one or two kilometers, which misleads the search for the fault point location and delays the emergency repair time.

[0004] Chinese Patent Application ZL 2024 1 0552094.7 discloses a method for improving the fault location accuracy in the double-track direct supply operation mode. This patent considers the influence of stations on the fault location accuracy, but this method cannot set the specific location of the station, and the calculated equivalent fault distance is difficult to restore to the actual fault kilometer mark. Moreover, for the traction network in the multi-station mode, only multiple stations can be regarded as a whole, and it is impossible to distinguish which specific station section the fault point is located in, so there are certain limitations. Summary of the Invention

[0005] The object of the invention is to provide an equivalent up-down line current ratio fault location method combined with a sectional reactance table, which can not only solve the problem of ranging error caused by uneven impedance distribution of the double-track direct supply traction network due to lightning protection coils, power supply lines, stations, and strengthening wires to the up-down line current ratio method for ranging, but also be flexibly applicable to multi-station power supply sections to accurately judge the fault point location. At the same time, this method considers the mutual impedance of each section separately, and can continuously improve the sectional reactance table according to the subsequent trip report data to further improve the ranging accuracy.

[0006] To achieve the above object, an equivalent up-down line current ratio fault location method combined with a sectional reactance table according to the invention includes the following steps: Step 1: Take the anti-lightning coil, power supply line, substation yard, tunnel or conditions with a strengthening wire, etc. as the sectioning basis, and divide the double-track direct-supply traction network into several sections; Step 2: Calculate the impedance at the end of each sectioning point in the parallel direct-supply mode according to the self-impedance and mutual impedance of each section in the up and down directions, and obtain the characteristic curve of reactance and fault distance in the parallel direct-supply mode at the end; Step 3: According to , where N is the number of sections, calculate the equivalent length of each section in the up and down directions respectively, accumulate all the equivalent lengths before each sectioning point, and obtain the new characteristic curves of reactance and equivalent fault distance in the up and down directions, where 、 are the equivalent length of this section and the actual length of this section respectively, are the unit self-impedance of the catenary, the unit mutual impedance of the catenary, the unit self-impedance of this section, and the unit mutual impedance of this section respectively; Step 4: Starting from the anti-lightning coil of the traction substation, add the equivalent lengths of each section in the up and down directions until the equivalent length of the power supply line of the section post is completed, and obtain the total equivalent distance in the up and down directions of the entire section, 、 , and calculate the equivalent fault distance according to the up and down current ratio method calculation formula; Step 5: According to the position of the fault point obtained in Step 4 in the equivalent model, judge the equivalent distance sectioning interval to which it belongs by looking up the table and comparison, and restore it to the actual fault distance of the fault point.

[0007] Further preferably, no matter how complex the line is, the interval lengths and sectioning characteristics of the up and down directions are quite different or there are a large number of substation yards on the line, each section can be set separately, the sectioning method is flexible and changeable, and the starting and ending positions of each section can be reflected in the section reactance table.

[0008] Further preferably, since the self-impedance and mutual impedance characteristics of each sectioning interval are different, it is necessary to obtain the self-impedance and mutual impedance of each sectioning point in advance through short-circuit tests or historical tripping report data. Obtain the characteristic table of reactance and fault distance shown in the following table. In the table, the up and down intervals are divided into N sections according to the anti-lightning coil, power supply line, substation yard, and strengthening wire as the sectioning basis, is the self-impedance value of each section of the up-line, which is obtained by multiplying the unit self-impedance of each up-line section by the section length, is the self-impedance value of each section of the down-line, 、 are the impedance values of each up and down section; is the distance of the up-line sectioning point from the substation; is the distance of the down-line sectioning point from the substation; is the mutual impedance of each section, and the mutual impedance of the anti-lightning coil It is 0, so it is not listed.

[0009] Table 1 is a characteristic table of reactance and fault distance:

[0010]

[0011] Further preferably, after obtaining the impedance table of each sectional point, taking the down-line power supply section as an example, according to calculate the equivalent length of each sectional point, where are respectively the unit self-impedance of this sectional point on the down-line power supply section, the unit mutual impedance of this section, the unit self-impedance and unit mutual impedance when this sectional point is equivalent to a pure catenary model, is the actual length of each section. After calculating the equivalent length of each down-line sectional point, a characteristic curve of down-line impedance-equivalent distance can be obtained with sectional impedance as the ordinate and equivalent distance as the abscissa.

[0012] Further preferably, the equivalent length of each sectional point in the up-line power supply section is calculated according to After calculating the equivalent length of each up-line sectional point, a characteristic curve of up-line impedance-equivalent distance can be obtained with sectional impedance as the ordinate and equivalent distance as the abscissa.

[0013] Further preferably, when a fault occurs in the traction network, by comparing the up-line and down-line feeder currents recorded by the dedicated ranging device at the fault moment and judge the fault line. If the up-line feeder current is large, the fault is on the up-line; otherwise, the fault is on the down-line.

[0014] Calculate the fault distance of the fault point in the equivalent model according to the up-down line current ratio method : , further preferably, find the sectional interval where is located in the impedance-equivalent distance characteristic curve. The equivalent distances corresponding to both ends of this interval are denoted as and , and at the same time, the actual distances and of both ends can be obtained from the above table, and the corresponding impedances are and . Then, through conversion processing of the fault distance obtained under the equivalent model, the actual fault point position is obtained. The conversion formula is as follows: .

[0015] Compared with the prior art, the beneficial effect of the technical solution of the present invention is that: (1) It makes full use of the sectional reactance table of the line and combines it with the up-down line current ratio method, so that the up-down line current ratio method will not be affected by the ranging error caused by the uneven distribution of the impedance of each section of the double-track direct supply traction network. (2) Through the fault report data obtained during operation, the reactance value in the sectional reactance table can be flexibly adjusted to correct the ranging error. At the same time, the number of sectional points can be flexibly expanded to meet the ranging requirements of lines with multiple stations. And as the number of sections increases, the ranging accuracy will continuously improve. (3) When obtaining the equivalent fault distance of the fault point through the reactance-fault distance sectional table, it can accurately find the actual kilometer mark corresponding to the fault point. (4) Using a dedicated direct supply fault ranging device, it can be perfectly connected to old lines without ranging function without modifying the functions of the original feeder protection device. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic flow chart of the equivalent up-down line current ratio ranging method combined with the sectional reactance table.

[0017] Figure 2 It is a schematic diagram of the power supply of the double-track direct supply traction network in the embodiment.

[0018] Figure 3 It is a schematic diagram of the equivalent of the double-track direct supply fault mesh in the embodiment.

[0019] Figure 4 It is a schematic diagram of the power supply arm from Nanxiang Substation to Shanghai. DETAILED DESCRIPTION OF THE INVENTION

[0020] The following describes the specific implementation manners of the present invention to facilitate those skilled in the art to understand the present invention.

[0021] Figure 1 It is a schematic flow chart of an equivalent up-down line current ratio fault ranging method combined with a sectional reactance table in this embodiment, specifically including the following steps: Step 1: Divide the double-track direct supply traction network into several sections according to specific conditions. Step 2: Calculate the impedance at the end of each sectional point in the parallel direct supply mode according to the self-impedance and mutual impedance of each up-down line section, and obtain the characteristic curve of the reactance and fault distance in the parallel direct supply mode at the end. Step 3: According to , where N is the number of sections, calculate the equivalent length of each up-down line section respectively, and accumulate all the equivalent lengths before each sectional point to obtain the new characteristic curves of the up and down line reactance and equivalent fault distance, where , are the equivalent length of this section and the actual length of this section respectively, They are the self-impedance per unit length of the catenary, the mutual-impedance per unit length of the catenary, the self-impedance per unit length of this section, and the mutual-impedance per unit length of this section respectively; Step 4: Starting from the lightning protection coil of the traction substation, add the equivalent lengths of each section of the up and down lines until the equivalent length of the power supply line of the section post ends, to obtain the total equivalent distance of the up and down lines of the entire section. , , and calculate the equivalent fault distance according to the calculation formula of the up and down line current ratio method; Step 5: According to the position of the fault point obtained in Step 4 in the equivalent model, judge the equivalent distance section interval where it is located by looking up the table and comparing, and then restore it to the actual fault distance.

[0022] The schematic diagram of the double-track direct supply traction network power supply is as Figure 2 shown. In the figure, 1QF and 2QF respectively represent the feeder breakers of the up and down line of the substation, and 3QF represents the breaker of the section post. The up line power supply line sections are successively the lightning protection coil, the traction substation power supply line, the catenary, yard 1, the strengthening line, yard 2, and the section post power supply line; the down line power supply line sections are successively the lightning protection coil, the traction substation power supply line, the catenary, yard 1, yard 2, yard 3, and the section post power supply line.

[0023] Assume that the fault point appears within the section of yard 2 on the up line, then the equivalent schematic diagram of the mesh of this fault point can be drawn, as Figure 3 shown.

[0024] Along the voltage drop from the substation busbar to the fault point along the

[0025] loop is: is the voltage of the substation busbar to the ground; and are the short-circuit currents of the up and down line power supply arms; is the self-impedance per unit length of each section of the up line; is the mutual-impedance per unit length of each section of the up line; is the length of each section interval of the up line power supply arm. Given the short-circuit current , the self-impedance per unit length and the mutual-impedance per unit length of the catenary are respectively and .

[0026] Along the voltage drop from the substation busbar to the fault point along the loop is: Meanwhile, for the convenience of calculation, each section in the characteristic table of reactance and fault distance is converted into the catenary length , and the conversion formula is , where , are the equivalent length and the actual length of the segment respectively, They are the unit self-impedance of the overhead line, the unit mutual impedance of the overhead line, the unit self-impedance of the section, and the unit mutual impedance of the section.

[0027] Combining the two voltage drop formulas and the short-circuit current calculation formula, we can get:

[0028]

[0029] Combining the above two equations, we can get the fault distance: , It can be seen from the above formula that the fault distance is still proportional to the ratio of the uplink and downlink currents at the time of the fault. Compared with the traditional uplink and downlink current ratio, the only difference between the unit self-impedance and the unit mutual impedance of the contact network is converted into the total length of the equivalent interval of the sum of the equivalent lengths in the power supply arm length. After the position of the fault point in the equivalent model is obtained and then restored to the actual fault distance, the actual position of the fault point can be found.

[0030] In practical applications, it is easier to obtain the total impedance value of each segment than the unit mutual impedance and unit self-impedance of each segment. Therefore, the total impedance value of the segment point obtained from the historical trip report can be put into the segment reactance table of impedance-fault distance, and the above formula can be converted into the equivalent fault distance. :

[0031] Find the impedance-equivalent distance characteristic curve The equivalent distances corresponding to the two ends of the segmented interval are recorded as and , and the actual distance between the two end points can be obtained from the above table and , the corresponding impedance is and , and then the fault distance obtained under the equivalent model is Perform conversion processing to obtain the actual fault point location , the conversion formula is as follows: .

[0032] Embodiment: Table 2 is the basic data table of the power supply arm of the Shanghai-Nanjing Intercity Nanxiang Substation:

[0033] Table 3 is based on Figure 4The segmented reactance table to be divided needs to include the three station yards of Nanxiang North Station, Shanghai West Station, and Shanghai Station in this power supply section. The unit reactance of the catenary is 0.32 Ω / kM. For Nanxiang North and Shanghai West, which are two-track station yards, it is set according to two-thirds of the catenary reactance. Since Shanghai Station is at the end of the section and has a short length, it is calculated according to the single-track equal to the catenary reactance. When the unit mutual impedance of the station yard is unknown, it is first set according to the unit mutual impedance of the catenary.

[0034] Table 3 is based on Figure 4 The segmented reactance table divided:

[0035] Table 4 is a comparison table of short-circuit test data and test results using the original up and down line current ratio method:

[0036] It can be seen from Table 4 that the error control range of the traditional up and down line current ratio method is not stable enough, while the up and down line current ratio ranging method combining the segmented reactance table provided by the present invention can well control the error within the range of 500 meters, and the ranging result is more accurate.

[0037] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. An equivalent up-down line current ratio fault location method combined with a segmented reactance table, characterized in that Including the following steps: Step 1: Divide the double-track direct-supply traction network into several sections according to specific conditions; Step 2: Calculate the impedance at the end of each sectional point in the parallel direct-supply mode according to the self-impedance and mutual impedance of each section of the up and down lines, and obtain the characteristic curve of reactance and fault distance in the parallel direct-supply mode at the end; Step 3: According to , where N is the number of segments, calculate the equivalent length of each segment for both the up and down lines respectively. Accumulate all the equivalent lengths before each segment point to obtain the characteristic curves of the new up and down line reactances and the equivalent fault distance, where and are the equivalent length of this segment and the actual length of this segment respectively, are the self-impedance per unit length of the catenary, the mutual-impedance per unit length of the catenary, the self-impedance per unit length of this segment and the mutual-impedance per unit length of this segment respectively; Step 4: Starting from the lightning protection coil of the traction substation, add the equivalent lengths of each section of the up and down lines until the equivalent length of the power supply line of the section post ends, to obtain the total equivalent distance of the up and down lines of the entire section. , and calculate the equivalent fault distance according to the calculation formula of the up and down line current ratio method. Step 5: According to the position of the fault point obtained in Step 4 in the equivalent model, judge the equivalent distance section interval it is in by looking up the table and comparing, and then restore it to the actual fault distance.

2. The equivalent up / downlink current ratio fault location method combined with a sectional reactance table according to claim 1, characterized in that: For complex lines, they can be set as a single section separately, and the starting and ending positions of each section can be reflected in the sectional reactance table; complex lines include those with large differences in the interval lengths of the up and down lines, large differences in the reactance characteristics of each section, or a large number of stations on the line.

3. The equivalent up / downlink current ratio fault location method combined with a segmented reactance table according to claim 1, characterized in that: Since the self-impedance and mutual-impedance characteristics of each sectional interval are different, it is necessary to obtain the self-impedance and mutual-impedance of each sectional point in advance through short-circuit tests or historical tripping report data, so as to obtain the sectional table of impedance and fault distance.

4. The equivalent up and down line current ratio fault location method combined with a sectional reactance table according to claim 1 or 3, characterized in that: After obtaining the impedance table for each sectional point, taking the down-line power supply section as an example, according to , the equivalent length of each sectional point is calculated by the formula, where are respectively the unit self-impedance of this sectional point on the down-line power supply section, the unit mutual impedance of this section, the unit self-impedance and unit mutual impedance when this sectional point is equivalent to a pure catenary model; is the actual length of each section; after obtaining the equivalent length of each sectional point on the down-line, taking the sectional impedance as the ordinate and the equivalent distance as the abscissa, the impedance-equivalent distance characteristic curve of the down-line can be obtained.

5. The equivalent up and down line current ratio fault location method combined with a sectional reactance table according to claim 4, characterized in that: The equivalent length of each sectional point in the up - supply section is calculated according to . After obtaining the equivalent length of each sectional point in the up - supply section, with the sectional impedance as the vertical coordinate and the equivalent distance as the horizontal coordinate, the characteristic curve of the up - supply impedance - equivalent distance can be obtained.

6. The equivalent up and down line current ratio fault location method combined with the sectional reactance table according to claim 1, characterized in that: When a traction network fails, the fault line is determined by comparing the up and down feeder currents recorded by a dedicated distance measuring device at the fault moment and judging the fault line type; If the current of the up-line feeder is large, the fault is on the up-line; otherwise, the fault is on the down-line; Calculate the fault distance of the fault point in the equivalent model according to the up / down line current ratio method : 。 7. The equivalent up / downlink current ratio fault location method combined with a segmented reactance table according to claim 1, characterized in that: Find in the impedance-equivalent distance characteristic curve The segmented interval where it is located, and the equivalent distances corresponding to both ends of this interval are denoted as and , and at the same time, the actual distances of both endpoints can be obtained from the segmented table of impedance and fault distance and , and the corresponding impedances are and , then through the fault distance obtained under the equivalent model, perform conversion processing to obtain the actual fault point position , and the conversion formula is as follows: 。 8. The equivalent up / downlink current ratio fault location method combined with a segmented reactance table according to claim 1, characterized in that: The specific conditions in Step 1 include: lightning protection coils, supply lines, stations, tunnels, and lines with strengthening wires.

Images