A fault location method of equivalent up-down current ratio combined with segmented reactance table

Abstract

The application relates to an equivalent uplink and downlink current ratio fault location method combined with segmented reactance tables, which uses the uplink and downlink current ratio method combined with segmented reactance tables to replace the reactance ratio method and the common uplink and downlink current ratio method commonly used in the current double-line direct supply operation mode for fault location, divides the double-line direct supply traction network into several sections according to the different unit impedances, and then calculates the reactance value of each section according to the impedance and mutual impedance of each section. The method can not only consider the influence of the lightning protection coil and the power supply line on the location result, but also can guarantee the location accuracy when the number of stations is large, so that the location error is controlled within 250 meters; the method can ensure that the maintenance personnel quickly find the fault point, timely treat the fault, and restore the normal operation of the line, and is very important for the safety, reliability and efficient transportation of the railway system.

Description

Technical Field

[0001] This invention belongs to the field of fault location in traction substations of electrified railways, and specifically relates to a fault location method based on the equivalent uplink and downlink current ratio combined with a segmented reactance meter. Background Technology

[0002] With the development of conventional-speed railways, in order to adapt to the longer power supply distance of the traction network and improve the power supply capacity of the lines, more and more conventional-speed railways are adopting the double-track direct power supply method with parallel connection at the end. Some lines even add reinforcing wires to the contact wire in a certain section to increase the traction load. For a double-track direct power supply traction network with uniform reactance distribution, the traditional up-down current ratio is generally sufficient to meet the accuracy requirements of distance measurement. The traditional formula for calculating the up-down current ratio is:

[0003] ,

[0004] D is the distance to the fault. , These are the downlink and uplink feeder currents collected by the fault location device during a fault. is the interval length.

[0005] However, in actual operation, due to the presence of lightning protection coils, long power supply lines, multiple stations in the section, and reinforced lines in some sections, the traditional uplink and downlink current ratio method often cannot meet the distance measurement accuracy requirements, with errors often reaching one or two kilometers. This can mislead the location of fault points and delay emergency repairs.

[0006] Chinese patent application ZL 2024 1 0552094.7 discloses a method for improving fault location accuracy in double-track direct supply operation mode. This patent takes into account the influence of stations on the location accuracy. However, this method cannot set the specific location of the station, and the calculated equivalent fault distance is difficult to restore the actual fault kilometer marker. Furthermore, for traction networks with multiple stations, it can only treat multiple stations as a whole and cannot distinguish which station section the fault point is located in, which has certain limitations. Summary of the Invention

[0007] The purpose of this invention is to provide a fault location method based on the equivalent uplink / downlink current ratio using segmented reactance meters. This method not only solves the location error problem caused by uneven reactance distribution due to lightning coils, power lines, substations, and reinforcing lines in multi-line direct-supply traction networks, but also allows for flexible application to multi-substation power supply sections, accurately determining the fault location. Furthermore, this method considers the mutual reactance of each segment separately, allowing for continuous improvement of the segmented reactance meters based on subsequent tripping report data, further enhancing location accuracy.

[0008] To achieve the above objectives, the present invention relates to a fault location method combining a segmented reactance meter with an equivalent uplink / downlink current ratio, comprising the following steps:

[0009] Step 1: Based on conditions such as lightning protection coils, power supply lines, stations, tunnels, or reinforced lines, divide the double-track direct traction network into several sections.

[0010] Step 2: Calculate the reactance of each segment in the parallel direct supply mode based on the self-reactance and mutual reactance of each segment, and obtain the characteristic curve of reactance and fault distance in the parallel direct supply mode.

[0011] Step 3: According to N is the number of segments. The equivalent length of each segment in both the uplink and downlink directions is calculated. All equivalent lengths before each segment point are summed to obtain new characteristic curves of the uplink and downlink reactance versus the equivalent fault distance. , These are the equivalent length and the actual length of the segment, respectively. , , , These are the unit self-reactor of the overhead contact line, the unit mutual reactance of the overhead contact line, the unit self-reactor of this section, and the unit mutual reactance of this section, respectively.

[0012] Step 4: Starting from the lightning arrester coil of the traction substation, add up the equivalent lengths of each segment in both the up and down directions until the equivalent length of the power supply line of the section substation ends, to obtain the total equivalent distance for both the up and down directions of the entire section. , The equivalent fault distance is calculated based on the uplink / downlink current ratio method.

[0013] Step 5: Based on the location of the fault point in the equivalent model obtained in Step 4, determine the equivalent distance segment interval to which it belongs by looking up the table and restore the actual fault distance of the fault point.

[0014] More preferably, no matter how complex the line is, the length of the up and down sections and the segmentation characteristics are very different, or there are many stations on the line, each section can be set up as a separate segment. The segmentation method is flexible and varied, and the start and end positions of each segment can be reflected in the segmented reactance table.

[0015] More preferably, since the self-reactance and mutual reactance characteristics of each segment are different, it is necessary to obtain the self-reactance and mutual reactance of each segment point in advance through short-circuit tests or historical trip report data. The following table shows the characteristics of reactance and fault distance.

[0016] The table divides the uplink and downlink sections into N segments based on lightning protection coils, power supply lines, substations, and reinforcement lines. , ... The self-reactance value of each segment of the uplink line is obtained by multiplying the unit self-reactance of each segment by the segment length. , ... The values ​​are the self-reactor values ​​of each segment of the downlink line. , These are the reactance values ​​for each segment of the uplink and downlink; , ... This refers to the distance from the upstream segmentation point to the substation. , ... This refers to the distance from the downlink segment point to the substation. , ... For the mutual reactance of each segment, the mutual reactance of the lightning protection coil The value is 0, therefore it is not listed.

[0017] Table 1 shows the characteristics of reactance and fault distance:

[0018]

[0019] More preferably,

[0020] After obtaining the reactance meters for each segment point, taking the downstream power supply section as an example, according to...

[0021]

[0022] Find the equivalent length of each segment point, where , These represent the unit self-reactance, unit mutual reactance of the segment at this point in the downlink power supply section, and the unit self-reactance and unit mutual reactance of this point when it is equivalent to a pure contact network model. Let be the actual length of each segment. After calculating the equivalent length of each segment point in the downlink, the characteristic curve of downlink reactance versus equivalent distance can be obtained by plotting the segment reactance as the vertical axis and the equivalent distance as the horizontal axis.

[0023] More preferably,

[0024] The equivalent length of each segment point in the uplink power supply section is calculated according to

[0025]

[0026] After calculating the equivalent length of each segment point in the upward direction, plot the segment reactance as the ordinate and the equivalent distance as the abscissa.

[0027] The target can obtain the characteristic curve of the uplink reactance-equivalent distance.

[0028] More preferably,

[0029] When a fault occurs in the traction network, the upstream and downstream feeders are compared at the time of the fault, as recorded by a dedicated ranging device.

[0030] Current and Determine the type of fault. A large uplink feeder current indicates a fault in the uplink, and vice versa.

[0031] The fault distance in the equivalent model is calculated using the uplink / downlink current ratio method. :

[0032]

[0033] More preferably,

[0034] Find it in the reactance-equivalent distance characteristic curve The segmented interval it occupies, and the two ends of the interval respectively correspond to

[0035] The equivalent distance is denoted as and The actual distance between the two endpoints can be obtained from the table above. and The corresponding reactance is and Then, the fault distance was calculated using the equivalent model. The actual location of the fault is obtained by conversion. The conversion formula is as follows:

[0036]

[0037] Compared with the prior art, the beneficial effects of the technical solution of the present invention are as follows:

[0038] (1) The segmented reactance meters of the line are fully utilized and combined with the up and down current ratio method so that the up and down current ratio method will not be affected by the uneven distribution of reactance of each segment of the double-track direct supply traction network, which causes the ranging error.

[0039] (2) By using the fault report data obtained during operation, the reactance value in the segment reactance table can be flexibly adjusted to correct the ranging error. At the same time, the number of segment points can be flexibly expanded to meet the ranging requirements of lines with multiple stations. Furthermore, as the number of segments increases, the ranging accuracy will continue to improve.

[0040] (3) By using the reactance-fault distance segmentation table to obtain the equivalent fault distance of the fault point, the actual kilometer marker corresponding to the fault point can be accurately found.

[0041] (4) Using a dedicated direct-supply fault location device, it can be perfectly connected to old lines that do not have a location location function, without modifying the original feeder protection device function. Attached Figure Description

[0042] Figure 1 A schematic diagram of the equivalent uplink / downlink current ratio ranging method combined with segmented reactance meters.

[0043] Figure 2 This is a schematic diagram of the power supply to the traction network for double-track direct supply in the embodiment.

[0044] Figure 3 This is an equivalent schematic diagram of a faulty mesh in a multi-line direct supply system, as shown in the embodiment.

[0045] Figure 4 A simplified schematic diagram of the power supply arm from Nanxiang Substation to Shanghai. Detailed Implementation

[0046] The specific embodiments of the present invention will be described below to enable those skilled in the art to understand the present invention.

[0047] Figure 1 This is a flowchart illustrating a fault location method using the equivalent uplink / downlink current ratio combined with a segmented reactance meter, as described in this embodiment. The method specifically includes the following steps:

[0048] Step 1: Divide the double-track direct supply traction network into several sections according to specific conditions;

[0049] Step 2: Calculate the reactance of each segment in the parallel direct supply mode based on the self-reactance and mutual reactance of each segment, and obtain the characteristic curve of reactance and fault distance in the parallel direct supply mode.

[0050] Step 3: According to N is the number of segments. The equivalent length of each segment in both the uplink and downlink directions is calculated. All equivalent lengths before each segment point are summed to obtain the new characteristic curves of the uplink and downlink reactance versus the equivalent fault distance. , These are the equivalent length and the actual length of the segment, respectively. , , , These are the unit self-reactor of the overhead contact line, the unit mutual reactance of the overhead contact line, the unit self-reactor of this segment, and the unit mutual reactance of this segment, respectively.

[0051] Step 4: Starting from the lightning arrester coil of the traction substation, add up the equivalent lengths of each segment in both the up and down directions until the equivalent length of the power supply line of the section substation ends, to obtain the total equivalent distance for both the up and down directions of the entire section. , The equivalent fault distance is calculated based on the uplink / downlink current ratio method.

[0052] Step 5: Based on the location of the fault point in the equivalent model obtained in Step 4, determine its equivalent distance segment interval by looking up the table and then restore the actual fault distance.

[0053] A schematic diagram of direct power supply to the traction network for double-track lines is shown below. Figure 2 As shown in the diagram. In the diagram, 1QF and 2QF represent the feeder circuit breakers of the uplink and downlink lines of the substation, respectively, and 3QF represents the circuit breaker of the sectioning substation. The uplink power supply line is divided into the following segments in sequence: lightning protection coil, traction substation power supply line, contact network, substation 1, reinforced line, substation 2, and sectioning substation power supply line; the downlink power supply line is divided into the following segments in sequence: lightning protection coil, traction substation power supply line, contact network, substation 1, substation 2, substation 3, and sectioning substation power supply line.

[0054] Assuming the fault point occurs within segment 2 of the upstream station yard, an equivalent schematic diagram of the mesh at that fault point can be drawn, such as... Figure 3 As shown.

[0055] along The voltage drop from the substation bus to the fault point in the circuit is:

[0056]

[0057] In the formula: This refers to the substation busbar voltage to ground. and For the short-circuit current of the up and down power supply arms; The unit reactance of each segment of the uplink line; The unit reactance of each segment of the uplink line; Let be the length of each segment of the upstream power supply arm. The short-circuit current is known. The unit self-reactance and unit mutual reactance of the overhead contact line are respectively and .

[0058] along The voltage drop from the substation bus to the fault point in the circuit is:

[0059] ,

[0060] To facilitate calculations, each segment in the reactance-fault distance characteristic table is converted into contact wire length. The conversion formula is:

[0061] N is the number of segments;

[0062] in , These are the equivalent length and the actual length of the segment, respectively. , , These are the unit self-reactor of the overhead contact line, the unit mutual reactance of the overhead contact line, the unit self-reactor of this section, and the unit mutual reactance of this section, respectively.

[0063] By combining the two voltage drop formulas and the short-circuit current calculation formula, we can obtain:

[0064]

[0065] By combining the above two equations, the fault distance can be calculated:

[0066]

[0067] As shown in the above formula, the fault distance is still directly 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 in the power supply arm length is that the total length of the equivalent interval is obtained by converting the reactance of each segment into the sum of the equivalent lengths based on the difference between the unit self-reactance and the unit mutual reactance of the contact network. After obtaining the position of the fault point in the equivalent model, it is restored to the actual fault distance, and thus the actual location of the fault point can be found.

[0068] In practical applications, the total reactance value of each segment is easier to obtain than the unit mutual reactance and unit self reactance of each segment. Therefore, the total reactance value of each segment obtained from historical trip reports can be first placed into the segment reactance table of reactance-fault distance, and the above formula can be transformed into calculating the equivalent fault distance. :

[0069]

[0070] Find it in the reactance-equivalent distance characteristic curve The segmented interval it occupies, and the two ends of the interval respectively correspond to

[0071] The equivalent distance is denoted as and The actual distance between the two endpoints can be obtained from the table above. and The corresponding reactance is and Then, the fault distance was calculated using the equivalent model. The actual location of the fault is obtained by conversion. The conversion formula is as follows:

[0072]

[0073] Example:

[0074] Table 2 shows the basic data of the power supply arm from the Nanxiang Substation on the Shanghai-Nanjing Intercity Railway towards Shanghai:

[0075]

[0076] Table 3 shows the data based on... Figure 4 The segmented reactance meters need to include all three stations in the power supply section: Nanxiang North Station, Shanghai West Station, and Shanghai Station. The unit reactance of the contact network is set at 0.32Ω / kM. Nanxiang North and Shanghai West are two-track stations, and the reactance is set at two-thirds of the contact network reactance. Since Shanghai Station is at the end of the section and is shorter, the reactance is calculated as a single track equal to the contact network reactance. When the unit mutual reactance of the station is unknown, it is first set according to the unit mutual reactance of the contact network.

[0077] Table 3 shows the data based on... Figure 4 Segmented Reactance Table:

[0078]

[0079] Table 4 is a comparison table of short-circuit test data and test results using the original up-down current ratio method:

[0080]

[0081] As can be seen from Table 4, the error control range of the traditional uplink-downlink current ratio method is not stable enough. However, the uplink-downlink current ratio ranging method combined with the segmented reactance meter provided by this invention can control the error well within the range of 500 meters, and the ranging result is more accurate.

[0082] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A fault location method of equivalent up / down current ratio with segmented reactance table, characterized in that, Includes the following steps: Step 1: Divide the double-track direct supply traction network into several sections according to specific conditions; Step 2: Calculate the reactance of each segment in the parallel direct supply mode at the end of each segment based on the self-reactance and mutual reactance of each segment 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 N is the number of segments. The equivalent length of each segment in both the uplink and downlink directions is calculated. All equivalent lengths before each segment point are summed to obtain the new characteristic curves of the uplink and downlink reactance versus the equivalent fault distance. , These are the equivalent length and the actual length of the segment, respectively. , , , These are the unit self-reactor of the overhead contact line, the unit mutual reactance of the overhead contact line, the unit self-reactor of this segment, and the unit mutual reactance of this segment, respectively. Step 4: Starting from the lightning arrester coil of the traction substation, add up the equivalent lengths of each segment in both the up and down directions until the equivalent length of the power supply line of the section substation ends, to obtain the total equivalent distance for both the up and down directions of the entire section. , The equivalent fault distance is calculated based on the uplink / downlink current ratio formula. Step 5: Based on the location of the fault point in the equivalent model obtained in Step 4, determine its equivalent distance segment interval by looking up the table and comparing it, and then restore it to the actual fault distance; When a fault occurs in the traction network, the upstream and downstream feeders are compared at the time of the fault, as recorded by a dedicated ranging device. Current and Determine the type of fault; A large uplink feeder current indicates a fault in the uplink, and vice versa; The fault distance in the equivalent model is calculated using the uplink / downlink current ratio method. : ； Find it in the reactance-equivalent distance characteristic curve The segmented interval in which it is located, and the equivalent distances corresponding to the two ends of the interval are denoted as . and Meanwhile, the actual distance between the two endpoints can be obtained from the segmented table of reactance and fault distance. and The corresponding reactance is and Then, the fault distance was calculated using the equivalent model. The actual location of the fault is obtained by conversion. The conversion formula is as follows: ； in, This is the unit self-reactance when the segment point is equivalent to a pure overhead contact line model. Unit mutual reactance.

2. The fault location method based on the equivalent uplink / downlink current ratio combined with a segmented reactance meter according to claim 1, characterized in that: For complex lines, each segment can be set up as a separate section, and the start and end positions of each segment can be reflected in the segment reactance table. Complex lines include those with unequal lengths of up and down sections, large differences in reactance characteristics of each segment, or a large number of stations on the line.

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

4. The fault location method based on the equivalent uplink / downlink current ratio combined with a segmented reactance meter according to claim 1 or 3, characterized in that: After obtaining the reactance meters for each segment point, taking the downstream power supply section as an example, according to... The calculation formula yields the equivalent length of each segment point, where... These are, respectively, the unit self-reactor, the unit mutual reactance of the segment at this point in the downlink power supply section, and the unit self-reactor and unit mutual reactance when the segment is equivalent to a pure contact network model; This represents the actual length of each segment; The equivalent length of each segment point is given. After calculating the equivalent length of each segment point in the downlink, the characteristic curve of the downlink reactance versus the equivalent distance can be obtained by using the segment reactance as the vertical axis and the equivalent distance as the horizontal axis.

5. The fault location method based on the equivalent uplink / downlink current ratio combined with a segmented reactance meter according to claim 4, characterized in that: The equivalent length of each segment point in the uplink power supply section is calculated according to After calculating the equivalent length of each segment point in the upward direction, the characteristic curve of the upward reactance versus the equivalent distance can be obtained by using the segment impedance as the vertical axis and the equivalent distance as the horizontal axis.

6. The fault location method based on the equivalent uplink / downlink current ratio combined with a segmented reactance meter according to claim 1, characterized in that: The specific conditions in step one include: lightning protection coils, power supply lines, stations, tunnels, and reinforced wires.

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