A method for measuring single-pole-to-ground short-circuit fault distance in a four-track power supply mode for subways

Abstract

The present invention provides a method for measuring the distance of a single-pole short-circuit fault to the ground under a four-track power supply mode of a subway. The method starts the distance measurement process when a preset condition is met; at the same time, the current value of the current I1 fed by the institute is obtained, and the current value is compared with the first preset value; when the current value of the current I1 fed by the institute is at the first preset value, the locomotive is located in the middle of the interval; if the current I1 fed by the institute reaches the first preset value, the first distance measurement process is executed; if the current I1 fed by the institute does not reach the first preset value, the current value is compared with the second preset value; the second preset value is less than the first preset value; if the current I1 fed by the institute is less than the second preset value, it is determined that there is no vehicle in the interval, and the second distance measurement process is executed. The present invention provides a solution for timely and accurately obtaining the location of the positive pole to ground short-circuit fault point and the negative pole to ground short-circuit fault point of a four-track power supply subway, thereby improving the maintenance efficiency of the subway.

Description

Technical Field

[0001] The invention relates to the field of rail transit technology, and in particular to a method for measuring the distance of a single-pole-to-ground short-circuit fault in a four-rail power supply mode of a subway. Background Art

[0002] With the acceleration of China's urbanization process and the rapid growth of urban population, urban road traffic congestion has become the main bottleneck for the economic and social development of large and medium-sized cities. In order to alleviate this dilemma as soon as possible, first-tier cities, provincial capitals and coastal central cities are actively expanding urban rail transit networks. As an important part of the urban transportation system, the safety, reliability and operational efficiency of the subway have always attracted much attention. At present, most urban rail transit in China adopts a low-voltage DC power supply method based on running rail return, but the main drawback of this method is that the stray current on the running rail will cause electrochemical corrosion to the steel bars and metal pipes of the subway tunnel and surrounding buildings.

[0003] To solve this problem, domestic scholars have proposed a dedicated rail return power supply technology, that is, to guide the return current back to the traction substation through a dedicated rail (the fourth rail) rather than the running rail. Although this technology effectively solves the problem of stray current, it also brings new challenges. When the positive pole of the line is short-circuited to the ground, due to the small short-circuit current, it is difficult for conventional DC protection devices to effectively remove the fault. When using the power supply method of the London Underground, the fault is usually judged by detecting the voltage of the resistor, but this method cannot accurately determine the fault range. It is urgent to introduce new methods to accurately locate the fault point to improve the accuracy of fault detection and the safety of the system. Summary of the invention

[0004] In view of this, the invention aims to propose a new single-pole-to-ground short-circuit fault distance measurement method under the four-rail power supply mode of the subway, so as to solve the problem of difficulty in locating the single-pole-to-ground short-circuit fault point in the four-rail power supply subway.

[0005] To achieve the above object, the technical solution created by the present invention is implemented as follows:

[0006] A method for measuring the distance of a single-pole-to-ground short-circuit fault in a four-rail power supply mode of a subway comprises the following steps:

[0007] When the preset conditions are met, the ranging process is started; the ranging process includes a positive pole to ground short circuit fault ranging process and a negative pole to ground short circuit fault ranging process;

[0008] While starting the distance measurement process, obtain the current value of the current I1 fed by the substation, and compare it with the first preset value; when the current value of the current I1 fed by the substation is at the first preset value, the locomotive is located in the middle of the section; the substation is one of the two adjacent substations constituting the section, and the other substation is the opposite substation;

[0009] If the current I1 fed out by the institute reaches the first preset value, the first distance measurement process is executed;

[0010] If the current I1 fed out by the institute does not reach the first preset value, then compare it with the second preset value; the second preset value is smaller than the first preset value;

[0011] If the current I1 fed out by the institute is less than the second preset value, it is determined that there is no vehicle in the section, and the second distance measurement process is executed.

[0012] Furthermore, the step of starting the ranging process when the preset conditions are met includes:

[0013] Monitor the voltage value of the positive electrode to ground test resistor of the institute, and compare the voltage value with the first threshold value, and when the voltage value drops to the first threshold value, start the positive electrode to ground short circuit fault distance measurement process; the positive electrode to ground test resistor is set between the power supply line and the ground rail;

[0014] Monitor the voltage value of the negative electrode to ground test resistor of the institute, and compare the voltage value with the second threshold value. When the voltage value drops to the second threshold value, start the negative electrode to ground short circuit fault ranging process; the negative electrode to ground test resistor is set between the return rail and the ground rail.

[0015] Furthermore, the first ranging process includes:

[0016] Determine whether the fault point is closer to the station than the train location;

[0017] If the fault is judged to be closer to the station than the train, the location of the fault point is obtained by calculating the distance between the fault point and the station;

[0018] If it is determined that the fault is farther away from the station than the train, the current value of the current I1 fed from the station is re-obtained, and the current value is compared with the first preset value after the value is reduced;

[0019] If the current I1 fed out of the station reaches the first preset value after the value is reduced, the position of the fault point is obtained by calculating the distance between the fault point and the station.

[0020] Furthermore, in the positive-to-ground short-circuit fault distance measurement process, the method for determining whether the fault point is closer to the station than the train position includes:

[0021] When the current I1 fed out by this institute reaches the first preset value, the current I2 fed out by the institute on the opposite side, the voltage value U3 on the positive electrode to ground test resistor of this institute, and the voltage value U5 on the positive electrode to ground test resistor of the opposite side are obtained; the positive electrode to ground test resistor is set between the power supply line and the ground rail;

[0022] Use the following formula to calculate the L value:

[0023] ,

[0024] When L1 is less than the first set value, it is determined that the fault point is closer to the station than the train;

[0025] When L1 is greater than the first set value, it is determined that the fault point is farther away from the station than the train.

[0026] Furthermore, in the positive-to-ground short-circuit fault distance measurement process, the formula for obtaining the position of the fault point by calculating the distance between the fault point and the station is:

[0027] ,

[0028] Wherein, R1 is the contact network resistance of the fault point on the side of the institute, U3 is the voltage value on the positive pole to ground test resistance of the institute, U4 is the voltage value on the negative pole to ground test resistance of the institute, the negative pole to ground test resistance is set between the return rail and the ground rail, I1 is the feed-out current value of the feeder of the institute, and α is the ratio of the contact network unit resistance to the ground rail unit resistance;

[0029] The fault point is located at a distance of R1 / k from this station, where k is the resistance per unit length of the contact network.

[0030] Further, in the positive-to-ground short-circuit fault ranging process, the second ranging process includes the following steps:

[0031] Obtain the voltage value U3 on the positive electrode to ground test resistor of the institute, the voltage value U4 on the negative electrode to ground test resistor of the institute, the feed current I2 of the opposite institute, and the voltage value U5 on the positive electrode to ground test resistor of the opposite institute; the positive electrode to ground test resistor is set between the power supply line and the ground rail; the negative electrode to ground test resistor is set between the return rail and the ground rail;

[0032] The distance between the fault point and the institute is calculated using the following formula:

[0033] ,

[0034] Among them, R1 is the contact network resistance of the fault point on the side of this station, U3 is the voltage value of the positive pole to ground test resistance of this station, U4 is the voltage value of the negative pole to ground test resistance of this station, U5 is the voltage value of the positive pole to ground test resistance of the opposite station, I1 is the feeder current of this station feeder, I2 is the feeder current of the opposite station feeder, and α is the ratio of the unit resistance of the contact network to the unit resistance of the grounding rail;

[0035] The fault point is located at a distance of R1 / k from this station, where k is the resistance per unit length of the contact network.

[0036] Furthermore, in the negative-to-ground short-circuit fault distance measurement process, the method for determining whether the fault point is closer to the station than the train position includes:

[0037] When the current I1 fed out by this institute reaches the first preset value, the current I2 fed out by the opposite institute at this moment, the voltage value U4 on the negative electrode to ground test resistor of this institute, and the voltage value U6 on the negative electrode to ground test resistor of the opposite institute are obtained; the negative electrode to ground test resistor is set between the return rail and the ground rail;

[0038] Use the following formula to calculate the L value:

[0039] ,

[0040] When L2 is less than the second set value, it is determined that the fault point is closer to the station than the train;

[0041] When L2 is greater than the second set value, it is determined that the fault point is farther away from the station than the train.

[0042] Furthermore, in the negative pole to ground short circuit fault distance measurement process, the formula for obtaining the position of the fault point by calculating the distance between the fault point and the station is:

[0043] ,

[0044] Among them, βR1 is the return rail resistance of the fault point on the side of the institute, U3 is the voltage value on the positive pole to ground test resistance of the institute, U4 is the voltage value on the negative pole to ground test resistance of the institute, and the negative pole to ground test resistance is set between the return rail and the grounding rail, I1 is the feed-out current value of the feeder of the institute, α is the ratio of the contact network unit resistance to the grounding rail unit resistance; β is the ratio of the contact network unit resistance to the return rail unit resistance;

[0045] The fault point is located at a distance of R1 / k from this station, where k is the resistance per unit length of the contact network.

[0046] Further, in the negative pole to ground short circuit fault ranging process, the second ranging process includes the following steps:

[0047] Obtain the voltage value U3 on the positive electrode to ground test resistor of the institute, the voltage value U4 on the negative electrode to ground test resistor of the institute, the feed current I2 of the opposite institute, the voltage value U5 on the positive electrode to ground test resistor of the opposite institute; the voltage value U6 on the negative electrode to ground test resistor of the opposite institute; the positive electrode to ground test resistor is set between the power supply line and the ground rail; the negative electrode to ground test resistor is set between the return rail and the ground rail;

[0048] The distance between the fault point and the institute is calculated using the following formula:

[0049] ,

[0050] Among them, βR1 is the return rail resistance of the fault point on the side of this station, U3 is the voltage value on the positive pole of this station to the ground test resistance, U4 is the voltage value on the negative pole of this station to the ground test resistance, U6 is the voltage value on the negative pole of the opposite station to the ground test resistance, I1 is the feeder current of the feeder of this station, I2 is the feeder current of the feeder of the opposite station, α is the ratio of the unit resistance of the overhead contact network to the unit resistance of the grounding rail; β is the ratio of the unit resistance of the overhead contact network to the unit resistance of the return rail;

[0051] The fault point is located at a distance of R1 / k from this station, where k is the resistance per unit length of the contact network.

[0052] Compared with the prior art, the single-pole to ground short-circuit fault distance measurement method under the subway four-rail power supply mode created by the present invention has the following advantages:

[0053] The present invention creates a single-pole-to-ground short-circuit fault distance measurement method under the four-rail power supply mode of the subway, which provides a solution for timely and accurately obtaining the positions of the positive pole-to-ground short-circuit fault point and the negative pole-to-ground short-circuit fault point of the four-rail power supply subway, thereby improving the maintenance efficiency of the subway. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] The drawings constituting part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings:

[0055] Figure 1 The electrical wiring diagram of the positive-to-ground short circuit fault in the four-track power supply mode of the subway is shown;

[0056] Figure 2 The equivalent circuit diagram of the positive pole to ground short circuit fault in the four-track power supply mode of the subway is shown;

[0057] Figure 3 The equivalent circuit diagram of a positive-to-ground short-circuit fault in a subway four-track power supply mode without a train is shown;

[0058] Figure 4 A flow chart showing a method for measuring the distance of a positive-to-ground short-circuit fault in a subway four-rail power supply mode according to an embodiment of the present invention is shown;

[0059] Figure 5 The electrical wiring diagram of the negative pole to ground short circuit fault in the four-track power supply mode of the subway is shown;

[0060] Figure 6 The equivalent circuit diagram of the negative pole to ground short circuit fault in the four-track power supply mode of the subway is shown;

[0061] Figure 7The equivalent circuit diagram of the negative pole to ground short circuit fault in the subway four-track power supply mode without a train is shown;

[0062] Figure 8 A flow chart showing a method for measuring the distance of a negative-to-ground short-circuit fault in a subway four-rail power supply mode according to an embodiment of the present invention is shown;

[0063] Fig. 9 A schematic diagram showing the relationship between the flow conditions and the position of the locomotive in the section under the four-rail power supply mode of the subway according to the embodiment of the present invention is shown. DETAILED DESCRIPTION

[0064] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0065] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0066] refer to Figure 1-Figure 8 As shown, this embodiment provides a method for measuring the distance of a single-pole-to-ground short-circuit fault in a four-rail power supply mode of a subway, specifically comprising Figure 1-Figure 4 The method for measuring the positive-to-ground short-circuit fault location involved, and Figure 5-Figure 8 The method for measuring the distance of a negative pole to ground short circuit fault involved in the subway power supply system monitors both the positive pole to ground short circuit fault and the negative pole to ground short circuit fault. This embodiment describes the method for measuring the distance of a positive pole to ground short circuit fault under the subway four-track power supply mode and the method for measuring the distance of a negative pole to ground short circuit fault under the subway four-track power supply mode.

[0067] In addition, it should be noted that in the subway power supply system, the section is composed of two adjacent substations upstream and downstream of the track. One of the two adjacent substations is set as the local substation and the other is set as the opposite substation. After confirming that there is a short circuit fault, the local substation and the opposite substation start distance measurement at the same time, hoping that at least one side of the local substation or the opposite substation can meet the test conditions and obtain the distance measurement result. This embodiment takes the local substation (corresponding to Figure 2 or Figure 6 The left side of the figure is used as the execution subject for explanation.

[0068] refer to Figure 1-Figure 4 As shown, the positive pole to ground short circuit fault distance measurement method under the subway four-track power supply mode includes the following steps:

[0069] The feeder protection device detects the positive pole to ground test resistance of the station (such as Figure 1 and Figure 2When the voltage value of the 200Ω resistor shown in the figure drops to a preset fixed value, i.e., the first threshold value, it is determined that the subway power supply system has a positive short circuit to the ground, and the current I1 fed out by the institute is recorded to calculate the position of the train. Taking the 1500v subway power supply system as an example, when the resistance value of the 200Ω resistor drops to 200v, it is determined that a positive short circuit to the ground occurs.

[0070] The current I1 fed out by the station is related to the position of the locomotive on the section line. The current is large when the locomotive is close to the station, and the current is small when the locomotive is far away from the station. A first preset value is set in advance, such as a fixed value a. For example, the value a can be set to 200A. When the fed out current is equal to the fixed value a, the train is located in the middle of the section line, which is an ideal distance measurement position for the short-circuit fault site. At this time, it is determined whether the distance from the short-circuit fault point to the station is less than the distance from the locomotive to the station.

[0071] For example, Fig. 9 The diagram shows the relationship between the flow pattern and the locomotive position in the section under the four-track power supply mode of the subway.

[0072] Case 1:

[0073] When the current I1 fed by the institute reaches a (such as Fig. 9 As shown, the train is at 2.5KM at this time), send the GOOSE command to the opposite station, and record the feed current I2 of the opposite station at this moment. At the same time, record the voltage value U3 on the 200Ω resistor of this station at this time, send the GOOSE command to the opposite station, and record the voltage value U5 on the 200Ω resistor of the opposite station at this moment.

[0074] Use the following formula to determine whether the fault point is closer to the station than the train location: Figure 2 The left half of Fig. 9 0-2.5KM section)

[0075] (1)

[0076] When L1 is less than the first set value, such as L1<0.9, the fault is closer to the station than the train. At this moment, the data is suitable for fault distance measurement and is calculated by the formula:

[0077] (2)

[0078] Among them, R1 is Figure 2 The resistance of the contact rail (or contact network) on the left side of the middle fault point, U3 is the voltage value on the 200Ω resistor of this station, U4 is the voltage value on the 100Ω resistor of this station, I1 is the feeder current value of this station's feeder, and α is the ratio of the unit resistance of the contact network to the unit resistance of the rail (ground) (or grounded rail).

[0079] The fault point is located at a distance of R1 / k from this station, where k is the resistance per unit length of the contact network.

[0080] When L1 is greater than the first set value, such as L1>0.9, the fault point is farther away from the station than the train. At this moment, the data is not suitable for fault distance measurement. Then, the station feed current is recorded again to determine whether the fault point is farther away from the station when the locomotive is moving (i.e. Fig. 9 The horizontal axis in the figure is from left to right), and the distance from the office is less than the distance from the locomotive to the office. If the locomotive is heading towards the office (i.e. Fig. 9 The horizontal axis in the figure is from right to left), then the fault point must be farther away from this station than the locomotive. Therefore, it is still not suitable to perform fault distance measurement at this station, and the distance measurement result can be provided by the opposite side.

[0081] When the locomotive is moving farther from the station, because the direction of the locomotive is fixed, the feed current of the 200Ω resistor of the station should be the largest when the locomotive enters the station, and decreases as the locomotive moves away. At this time, the constant a is reduced to a / 2, that is, when the locomotive is at Fig. 9 When the fault point is at 2.5-4KM, re-determine whether the fault point is closer to the office than the locomotive.

[0082] Specifically, when the output current I1 of this station reaches a / 2, send the GOOSE command to the opposite station and record the output current I2 of the opposite station at this moment. At the same time, record the voltage value U3 on the 200Ω resistor of this station at this moment, send the GOOSE command to the opposite station and record the voltage value U5 on the 200Ω resistor of the opposite station at this moment. Re-calculate the L1 value using formula (1), and judge whether the fault point is closer to this station than the train position by comparing the L1 value with 0.9.

[0083] If the fault point is close to the institute, the specific location of the fault point can be calculated using formula (2).

[0084] If the condition for calculating L is still not met after lowering the first preset value, for example, when the locomotive is heading towards the station, the feed current of the 200Ω resistor of the station should be the smallest when the locomotive enters the station, and increase as the locomotive moves away. At this time, the feed current I1 of the station cannot reach a / 2, that is, the fault point is still farther away from the station than the locomotive, indicating that this side is not suitable for ranging, and the ranging of this side is abandoned, and the ranging procedure ends. Since the stations on the left and right sides and the station on the opposite side start ranging at the same time, at least one side will meet the ranging conditions.

[0085] Case 2:

[0086] When the current I1 fed by the station does not reach a, it is determined whether the current fed by the station is less than another fixed value a', that is, the second preset value. If the current fed by the station is less than this fixed value a', it is considered that there is no car in the interval at this time, and the equivalent circuit diagram becomes Figure 3 For example, a' can be set to 30A.

[0087] At this time, we only need to record the voltage values ​​U3 and U4 of the 200Ω and 100Ω resistors, send the GOOSE command to read the current I2 fed from the opposite side and the voltage value U5 of the 200Ω resistor on the opposite side, and then substitute them into formula (3):

[0088] (3)

[0089] Among them, R1 is Figure 3 The contact network resistance on the left side of the middle fault point, U3 is the voltage value on the 200Ω resistor of this station, U4 is the voltage value on the 100Ω resistor of this station, U5 is the voltage value on the 200Ω resistor of the opposite station, I1 is the feeder current value of this station's feeder, I2 is the feeder current value of the opposite station's feeder, and α is the ratio of the unit resistance of the contact network to the unit resistance of the grounding rail.

[0090] The fault point is located at a distance of R1 / k from this station, where k is the resistance per unit length of the contact network.

[0091] refer to Figure 5-Figure 8 As shown, the method for measuring the distance of a negative-to-ground short-circuit fault under the four-track power supply mode of the subway includes the following steps:

[0092] The feeder protection device detects the negative pole to ground test resistance of the station (such as Figure 5 and Figure 6 When the voltage value of the 100Ω resistor shown in the figure drops to a preset fixed value, i.e., the second threshold value, it is determined that the subway power supply system has a negative pole to ground short circuit, and the fed current I1 is recorded to calculate the position of the train. Taking the 1500v subway power supply system as an example, when the resistance value of the 100Ω resistor drops to 100v, it is determined that a positive pole to ground short circuit fault has occurred.

[0093] The current I1 fed from this station is related to the position of the locomotive on the section line. The current is large when the locomotive is close to this station, and the current is small when the locomotive is far away from this station. A first preset value is set in advance, such as a fixed value b. For example, the b value can be set to 200A. When the fed current is equal to the fixed value b, the train is located in the middle of the section line, which is an ideal distance measurement position for the short-circuit fault site. At this time, it is determined whether the distance from the short-circuit fault point to this station is less than the distance from the locomotive to this station.

[0094] For example, Fig. 9 The diagram shows the relationship between the flow pattern and the locomotive position in the section under the four-track power supply mode of the subway.

[0095] Case 1:

[0096] When the current I1 fed by the institute reaches b (such as Fig. 9As shown, the train is at 2.5KM at this time), send the GOOSE command to the opposite station, and record the feed current I2 of the opposite station at this moment. At the same time, record the voltage value U4 on the 100Ω resistor of this station at this time, send the GOOSE command to the opposite station, and record the voltage value U6 on the 100Ω resistor of the opposite station at this moment.

[0097] Use the following formula to determine whether the fault point is closer to the station than the train location: Figure 6 The left half of Fig. 9 0-2.5KM section)

[0098] (4)

[0099] When L2 is less than the second set value, such as L2<0.9, the fault is closer to the station than the train. At this moment, the data is suitable for fault distance measurement and is calculated by the formula:

[0100] (5)

[0101] Among them, βR1 is Figure 2 The return rail resistance on the left side of the middle fault point, U3 is the voltage value on the 200Ω resistor of this station, U4 is the voltage value on the 100Ω resistor of this station, I1 is the feeder current value of this station's feeder, α is the ratio of the unit resistance of the overhead contact network to the unit resistance of the grounding rail, and β is the ratio of the unit resistance of the overhead contact network to the unit resistance of the return rail.

[0102] The fault point is located at a distance of R1 / k from this station, where k is the resistance per unit length of the contact network.

[0103] When L2 is greater than the second set value, such as L2>0.9, the fault point is farther away from the station than the train. At this moment, the data is not suitable for fault distance measurement. Then, the station feed current is recorded again to determine whether the fault point is farther away from the station (i.e. Fig. 9 The horizontal axis in the figure is from left to right), and the distance from the office is less than the distance from the locomotive to the office. If the locomotive is heading towards the office (i.e. Fig. 9 The horizontal axis in the figure is from right to left), then the fault point must be farther away from this station than the locomotive. Therefore, it is still not suitable to perform fault distance measurement at this station, and the distance measurement result can be provided by the opposite side.

[0104] When the locomotive is moving farther from the station, because the direction of the locomotive is fixed, the feed current of the 100Ω resistor of the station should be the largest when the locomotive enters the station, and decreases as the locomotive moves away. At this time, the constant b is reduced to b / 2, that is, when the locomotive is at Fig. 9 When the fault point is at 2.5-4KM, re-determine whether the fault point is closer to the office than the locomotive.

[0105] Specifically, when the output current I1 of this station reaches b / 2, send the GOOSE command to the opposite station and record the output current I2 of the opposite station at this moment. At the same time, record the voltage value U4 on the 100Ω resistor of this station at this moment, send the GOOSE command to the opposite station and record the voltage value U6 on the 100Ω resistor of the opposite station at this moment. Re-calculate the L1 value using formula (4), and judge whether the fault point is closer to this station than the train position by comparing the L2 value with 0.9.

[0106] If the fault point is close to the institute, the specific location of the fault point can be calculated using formula (5).

[0107] If the condition for calculating L is still not met after lowering the first preset value, for example, when the locomotive is heading towards the station, the feed current of the 100Ω resistor of the station should be the smallest when the locomotive enters the station, and increase as the locomotive moves away. At this time, the feed current I1 of the station cannot reach b / 2, that is, the fault point is farther away from the station than the locomotive, indicating that this side is not suitable for ranging, and the ranging of this side is abandoned, and the ranging procedure ends. Since the stations on the left and right sides and the station on the opposite side start ranging at the same time, at least one side will meet the ranging conditions.

[0108] Case 2:

[0109] When the current I1 fed by the station does not reach b, it is determined whether the current fed by the station is less than another fixed value b', that is, the second preset value. If the current fed by the station is less than the fixed value b', it is considered that there is no car in the interval at this time, and the equivalent circuit diagram becomes Figure 3 For example, b' can be set to 30A.

[0110] At this time, we only need to record the voltage values ​​U3 and U4 of the 200Ω and 100Ω resistors, send the GOOSE command to read the current I2 fed from the opposite side and the voltage value U6 of the 100Ω resistor on the opposite side, and then substitute them into formula (6):

[0111] (6)

[0112] Among them, βR1 is Figure 3 The return rail resistance on the left side of the middle fault point, U3 is the voltage value on the 200Ω resistor of this station, U4 is the voltage value on the 100Ω resistor of this station, I1 is the outgoing current value of the feeder of this station, I2 is the outgoing current value of the feeder of the opposite station, α is the ratio of the unit resistance of the contact network to the unit resistance of the rail, and β is the ratio of the unit resistance of the contact network to the unit resistance of the return rail.

[0113] The fault point is located at a distance of R1 / k from this station, where k is the resistance per unit length of the contact network.

[0114] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.

[0115] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for measuring the distance of a single-pole to ground short-circuit fault in a four-rail power supply mode of a subway, characterized in that: The steps include: When the preset conditions are met, the ranging process is started; the ranging process includes a positive pole to ground short circuit fault ranging process and a negative pole to ground short circuit fault ranging process; While starting the distance measurement process, obtain the current value of the current I1 fed by the substation, and compare it with the first preset value; when the current value of the current I1 fed by the substation is at the first preset value, the locomotive is located in the middle of the section; the substation is one of the two adjacent substations constituting the section, and the other substation is the opposite substation; If the current I1 fed out by the institute reaches the first preset value, the first distance measurement process is executed; If the current I1 fed out by the institute does not reach the first preset value, then compare it with the second preset value; the second preset value is smaller than the first preset value; If the current I1 fed out by the institute is less than the second preset value, it is determined that there is no vehicle in the interval, and the second distance measurement process is executed; The first ranging process includes: Determine whether the fault point is closer to the station than the train location; If the fault is determined to be closer to the station than the train, the location of the fault point is obtained by calculating the distance between the fault point and the station; If it is determined that the fault is farther away from the station than the train, the current value of the current I1 fed from the station is re-obtained, and the current value is compared with the first preset value after the value is reduced; If the current I1 fed from the station reaches the first preset value after the value is reduced, the location of the fault point is obtained by calculating the distance between the fault point and the station; In the positive-to-ground short-circuit fault distance measurement process, the formula for obtaining the location of the fault point by calculating the distance between the fault point and the station is: ， Wherein, R1 is the contact network resistance of the fault point on the side of the institute, U3 is the voltage value on the positive pole to ground test resistance of the institute, U4 is the voltage value on the negative pole to ground test resistance of the institute, the negative pole to ground test resistance is set between the return rail and the ground rail, I1 is the feed-out current value of the feeder of the institute, and α is the ratio of the contact network unit resistance to the ground rail unit resistance; The fault point is located at a distance of R1 / k from the station, where k is the resistance per unit length of the overhead contact network; In the positive-to-ground short-circuit fault ranging process, the second ranging process includes the following steps: Obtain the voltage value U3 on the positive electrode to ground test resistor of the institute, the voltage value U4 on the negative electrode to ground test resistor of the institute, the feed current I2 of the opposite institute, and the voltage value U5 on the positive electrode to ground test resistor of the opposite institute; the positive electrode to ground test resistor is set between the power supply line and the ground rail; the negative electrode to ground test resistor is set between the return rail and the ground rail; The distance between the fault point and the institute is calculated using the following formula: ， Among them, R1 is the contact network resistance of the fault point on the side of this station, U3 is the voltage value of the positive pole to ground test resistance of this station, U4 is the voltage value of the negative pole to ground test resistance of this station, U5 is the voltage value of the positive pole to ground test resistance of the opposite station, I1 is the feeder current of this station feeder, I2 is the feeder current of the opposite station feeder, and α is the ratio of the unit resistance of the contact network to the unit resistance of the grounding rail; The fault point is located at a distance of R1 / k from this station, where k is the resistance per unit length of the contact network.

2. The method for measuring the distance of a single-pole to ground short-circuit fault in a four-rail power supply mode of a subway according to claim 1, characterized in that: The step of starting the ranging process when the preset conditions are met includes: Monitor the voltage value of the positive electrode to ground test resistor of the institute, and compare the voltage value with the first threshold value, and when the voltage value drops to the first threshold value, start the positive electrode to ground short circuit fault distance measurement process; the positive electrode to ground test resistor is set between the power supply line and the ground rail; Monitor the voltage value of the negative electrode to ground test resistor of the institute, and compare the voltage value with the second threshold value. When the voltage value drops to the second threshold value, start the negative electrode to ground short circuit fault ranging process; the negative electrode to ground test resistor is set between the return rail and the ground rail.

3. The method for measuring the distance of a single-pole to ground short-circuit fault in a four-rail power supply mode of a subway according to claim 1, characterized in that: In the positive-to-ground short-circuit fault distance measurement process, the method for determining whether the fault point is closer to the station than the train position includes: When the current I1 fed out by this institute reaches the first preset value, the current I2 fed out by the institute on the opposite side, the voltage value U3 on the positive electrode to ground test resistor of this institute, and the voltage value U5 on the positive electrode to ground test resistor of the opposite side are obtained; the positive electrode to ground test resistor is set between the power supply line and the ground rail; Use the following formula to calculate the L1 value: ， When L1 is less than the first set value, it is determined that the fault point is closer to the station than the train; When L1 is greater than the first set value, it is determined that the fault point is farther away from the station than the train.

4. The method for measuring the distance of a single-pole to ground short-circuit fault in a four-rail power supply mode of a subway according to claim 1, characterized in that: In the negative pole to ground short circuit fault distance measurement process, the method for determining whether the fault point is closer to the station than the train position includes: When the current I1 fed out by this institute reaches the first preset value, the current I2 fed out by the opposite institute at this moment, the voltage value U4 on the negative electrode to ground test resistor of this institute, and the voltage value U6 on the negative electrode to ground test resistor of the opposite institute are obtained; the negative electrode to ground test resistor is set between the return rail and the ground rail; The L2 value is calculated using the following formula: ， When L2 is less than the second set value, it is determined that the fault point is closer to the station than the train; When L2 is greater than the second set value, it is determined that the fault point is farther away from the station than the train.

5. The method for measuring the distance of a single-pole to ground short-circuit fault in a four-rail power supply mode of a subway according to claim 1, characterized in that: In the negative pole to ground short circuit fault distance measurement process, the formula for obtaining the position of the fault point by calculating the distance between the fault point and the station is: ， Among them, βR1 is the return rail resistance of the fault point on the side of the institute, U3 is the voltage value on the positive pole to ground test resistance of the institute, U4 is the voltage value on the negative pole to ground test resistance of the institute, and the negative pole to ground test resistance is set between the return rail and the grounding rail, I1 is the feed-out current value of the feeder of the institute, α is the ratio of the contact network unit resistance to the grounding rail unit resistance; β is the ratio of the contact network unit resistance to the return rail unit resistance; The fault point is located at a distance of R1 / k from this station, where k is the resistance per unit length of the contact network.

6. The method for measuring the distance of a single-pole to ground short-circuit fault in a four-rail power supply mode of a subway according to claim 1, characterized in that: In the negative pole to ground short circuit fault ranging process, the second ranging process includes the following steps: Obtain the voltage value U3 on the positive electrode to ground test resistor of the institute, the voltage value U4 on the negative electrode to ground test resistor of the institute, the feed current I2 of the opposite institute, the voltage value U5 on the positive electrode to ground test resistor of the opposite institute; the voltage value U6 on the negative electrode to ground test resistor of the opposite institute; the positive electrode to ground test resistor is set between the power supply line and the ground rail; the negative electrode to ground test resistor is set between the return rail and the ground rail; The distance between the fault point and the institute is calculated using the following formula: ， Among them, βR1 is the return rail resistance of the fault point on the side of this station, U3 is the voltage value on the positive pole of this station to the ground test resistance, U4 is the voltage value on the negative pole of this station to the ground test resistance, U6 is the voltage value on the negative pole of the opposite station to the ground test resistance, I1 is the feeder current of the feeder of this station, I2 is the feeder current of the feeder of the opposite station, α is the ratio of the unit resistance of the overhead contact network to the unit resistance of the grounding rail; β is the ratio of the unit resistance of the overhead contact network to the unit resistance of the return rail; The fault point is located at a distance of R1 / k from this station, where k is the resistance per unit length of the contact network.

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