Traction Network Out-of-Phase Short-Circuit Relay Protection Method Based on Phase-to-Phase Voltage Reduction and Current Increment

Abstract

The traction network out-of-phase short-circuit relay protection method based on phase-to-phase voltage reduction and current increment collects the voltages of the α-phase and β-phase buses of the traction substation. The phase-to-phase voltage reduction is obtained by subtracting the effective values ​​of the phase-to-phase voltages from those of a previous power frequency cycle. The current of any traction network feeder connected to the bus is collected, and the current increment is obtained by subtracting the effective values ​​of the current of that feeder from those of a previous power frequency cycle. If the current increment is greater than its current increment setting value and the phase-to-phase voltage reduction is greater than its setting value, a delay phase begins. If, during the delay phase, both the current increment and phase-to-phase voltage reduction satisfy their respective settings, then after the delay phase, all feeder circuit breakers of that traction network feeder are tripped. This invention can quickly and accurately identify traction network lines experiencing out-of-phase short-circuit faults, and the protection devices do not require communication or synchronization; only the traction network line experiencing the out-of-phase short-circuit fault is disconnected, while others remain unaffected.

Description

Technical Field

[0001] This invention relates to the field of electrified railway power supply technology, and in particular to a method for interphase short-circuit relay protection of traction networks based on phase-to-phase voltage reduction and current increment elements. Background Technology

[0002] my country's electrified railways employ a cyclic phase-switching, segmented power supply method, drawing power from the three-phase power grid alternately to supply power to the power supply arms. Electrical phase separation is installed between two power supply arms with different phases to strictly insulate against voltage differences. When an electric locomotive, while energized, enters an electrical phase separation, the two power supply arms with different phases become connected, resulting in a phase-to-phase short circuit fault. Current traction network distance protection and current increment protection are insufficient for complete protection against phase-to-phase short circuit faults, and protection failures occur frequently, leading to serious consequences and posing a significant threat to the safe and stable operation of the traction power supply system.

[0003] Patent CN200810053159, "Protection Method for Out-of-Phase Short Circuits in Traction Power Supply Systems," and the literature "Research on the Principle of Novel Out-of-Phase Short Circuit Protection in Traction Power Supply" (Power System Protection and Control, Vol. 38, No. 22, 2010, pp. 63-67) propose out-of-phase short circuit protection methods based on inter-phase voltage harmonics. This method is designed for the voltage characteristics of electric arcs and cannot protect against out-of-phase short circuit faults not caused by electric arcs.

[0004] Patent CN201010557242, "Automatic Tripping Method for Electrified Railway Feeders Started by External Contacts," proposes a method for determining whether a short circuit has occurred in an electrical phase using the backup protection device of the traction transformer. This method requires external activation via the traction transformer protection, increasing its complexity.

[0005] Patents CN2020109927530 "A Relay Protection Method for Traction Network Power Supply Arm Based on Directional Current Element", CN2020110049560 "A Relay Protection Method for Traction Network Power Supply Arm Based on Directional Incremental Current Element", and CN2020110049433 "A Relay Protection Method for Traction Network Power Supply Arm Based on Directional Impedance Element" propose protection methods for power supply arms. These methods target line-to-ground faults and line-to-line faults within the power supply arm, but cannot reliably protect against out-of-phase short-circuit faults occurring between two power supply arms.

[0006] The paper "Anisotropic Short Circuit Protection of Power Supply Traction Network Based on Fault Component Correlation Analysis" (Automation of Electric Power Systems, 2007, Vol. 31, No. 6, pp. 82-85) proposes an anisotropic short circuit protection method that extracts fault characteristics using correlation analysis. This method places high demands on the synchronization of current measurements, which is not conducive to engineering implementation.

[0007] The literature "Analysis of Out-of-Phase Short Circuit Faults Based on Contact Line Temperature" (Journal of Dalian Jiaotong University, Vol. 31, No. 4, 2010, pp. 38-40, 62) proposes an out-of-phase short circuit protection method based on contact line temperature. This method requires waiting for the accumulation of the thermal effect of the short-circuit current, resulting in a relatively long operating time, which is not conducive to rapid protection operation.

[0008] The paper "Backup Distance Protection for Traction Transformers in High-Speed ​​Railways" (Electrical Automation Equipment, Vol. 32, No. 6, 2012, pp. 27-32) proposes a method for protecting against out-of-phase short circuits by configuring distance protection on the low-voltage side of the traction transformer. This method's trip signal acts on the circuit breaker on the low-voltage side of the traction transformer, which can expand the power outage range after an out-of-phase short circuit and reduce the reliability of power supply. Summary of the Invention

[0009] The purpose of this invention is to provide a relay protection method for traction network out-of-phase short circuits based on phase-to-phase voltage reduction and current increment, especially for out-of-phase short circuit faults occurring under long power supply lines, which can quickly identify and isolate the fault after an out-of-phase short circuit fault occurs in the traction network, thereby achieving protection.

[0010] The technical solution for achieving the objective of this invention is as follows:

[0011] The first technical solution:

[0012] Traction network interphase short-circuit relay protection methods based on phase-to-phase voltage reduction and current increment include:

[0013] The voltages of the α-phase bus and β-phase bus in the traction substation are collected, and the effective value of the phase-to-phase voltage is calculated by subtracting them. The phase-to-phase voltage reduction is calculated by subtracting the effective value of the phase-to-phase voltage from one power frequency cycle ago and the effective value of the phase-to-phase voltage at the current moment.

[0014] The current of any traction network feeder connected to the α-phase bus is collected, and the effective value of the current of the traction network feeder is calculated. The current increment is calculated by subtracting the effective value of the current of the traction network feeder at the current moment from the effective value of the current one power frequency cycle ago. If the current increment of the traction network feeder is greater than its current increment setting value, and the phase-to-phase voltage reduction is greater than its setting value, then a delay stage is entered. If, during the delay stage, the current increment of the traction network feeder is greater than its current increment setting value, and the phase-to-phase voltage reduction is greater than its setting value, then after the delay stage, all feeder circuit breakers of the traction network feeder are tripped. The current increment of the traction network feeder during the delay stage is calculated by subtracting the effective value of the current of the traction network feeder at the current moment from the effective value of the current one power frequency cycle ago at the start of the delay stage. The phase-to-phase voltage reduction during the delay stage is calculated by subtracting the effective value of the phase-to-phase voltage one power frequency cycle ago at the start of the delay stage from the effective value of the phase-to-phase voltage at the current moment.

[0015] The current of any traction network feeder connected to the β-phase bus is collected, and the effective value of the current of the traction network feeder is calculated. The current increment is calculated by subtracting the effective value of the current of the traction network feeder at the current moment from the effective value of the current one power frequency cycle ago. If the current increment of the traction network feeder is greater than its current increment setting value and the phase-to-phase voltage reduction is greater than its setting value, then a delay stage is entered. If the current increment of the traction network feeder is greater than its current increment setting value and the phase-to-phase voltage reduction is greater than its setting value during the delay stage, then all feeder circuit breakers of the traction network feeder are tripped after the delay stage. The current increment of the traction network feeder during the delay stage is calculated by subtracting the effective value of the current of the traction network feeder at the current moment from the effective value of the current one power frequency cycle ago at the start of the delay stage. The phase-to-phase voltage reduction during the delay stage is calculated by subtracting the effective value of the phase-to-phase voltage one power frequency cycle ago at the start of the delay stage from the effective value of the phase-to-phase voltage at the current moment.

[0016] The second technical solution:

[0017] Traction network interphase short-circuit relay protection methods based on phase-to-phase voltage reduction and current increment include:

[0018] The voltages of the α-phase bus and β-phase bus in the traction substation are collected, and the effective value of the phase-to-phase voltage is calculated by subtracting them. The phase-to-phase voltage reduction is calculated by subtracting the effective value of the phase-to-phase voltage from one power frequency cycle ago and the effective value of the phase-to-phase voltage at the current moment.

[0019] The current of any traction network feeder connected to the α-phase bus is collected, and the effective value of the current of that feeder is calculated. The current increment is calculated by subtracting the current effective value of the feeder at the current moment from the current effective value one power frequency cycle ago. If the current increment of the feeder is greater than its current increment setting value and the phase-to-phase voltage drop is greater than its setting value, then the delay stage begins. If, during the delay stage, the current increment of the feeder is greater than its current increment setting value and the phase-to-phase voltage drop is greater than its setting value, then the delay stage ends. All feeder circuit breakers of the traction network feeder are tripped, and all feeder circuit breakers of the traction network feeder connected to the β-phase busbar corresponding to the traction network feeder electrical branch are tripped; the current increment of the traction network feeder during the delay phase is calculated by subtracting the effective current value of the traction network feeder at the current moment from the effective current value one power frequency cycle before the start of the delay phase; the phase-to-phase voltage reduction during the delay phase is calculated by subtracting the effective phase-to-phase voltage value one power frequency cycle before the start of the delay phase from the effective phase-to-phase voltage value at the current moment;

[0020] or,

[0021] The current of any traction network feeder connected to the β-phase bus is collected, and the effective value of the current of that feeder is calculated. The current increment is calculated by subtracting the current effective value of the feeder at the current moment from the current effective value one power frequency cycle ago. If the current increment of the feeder is greater than its current increment setting value and the phase-to-phase voltage drop is greater than its setting value, then the delay stage begins. If, during the delay stage, the current increment of the feeder is greater than its current increment setting value and the phase-to-phase voltage drop is greater than its setting value, then the delay stage ends. All feeder circuit breakers of the traction network feeder are tripped, and all feeder circuit breakers of the traction network feeder connected to the α-phase busbar corresponding to the traction network feeder are tripped; the current increment of the traction network feeder during the delay phase is calculated by subtracting the effective current value of the traction network feeder at the current moment from the effective current value one power frequency cycle before the start of the delay phase; the phase-to-phase voltage reduction during the delay phase is calculated by subtracting the effective phase-to-phase voltage value one power frequency cycle before the start of the delay phase from the effective phase-to-phase voltage value at the current moment.

[0022] In both of the above technical solutions, the traction network feeder connected to the α-phase bus and the traction network feeder connected to the β-phase bus include a T-line; the current in the traction network feeder is the T-line current.

[0023] Furthermore, the traction network feeder connected to the α-phase bus and the traction network feeder connected to the β-phase bus also include the F-line; the current of the traction network feeder is a combination of the T-line current and the F-line current.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] (1) The feeder protection configuration in the substation is based on the phase-to-phase voltage reduction and current increment. It utilizes the fault characteristics of the phase-to-phase voltage suddenly decreasing and the related line current suddenly increasing during the phase-to-phase short circuit. When the phase-to-phase voltage reduction is greater than the setting value and the feeder current increment is greater than the setting value, the protection is activated, which can quickly and accurately identify the traction network line where the phase-to-phase short circuit fault has occurred.

[0026] (2) It is simple to implement. There is no need for communication and synchronization between protection devices. Only the traction network line that has an out-of-phase short circuit fault is cut off, while other traction networks and traction transformers are not affected.

[0027] (3) It can be used for both phase short circuits caused by fault arcs and phase short circuits caused by suspension wires or foreign objects. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of an out-of-phase short circuit fault.

[0029] Figure 2This is the action logic diagram for Protection 1.

[0030] Figure 3 This is the action logic diagram for Protection 2.

[0031] Figure 4 This is the protection action logic diagram.

[0032] Figure 5 This is the protection 4-action logic diagram.

[0033] Figure 6 This is a schematic diagram of a fully parallel AT power supply system with dual circuit breakers.

[0034] Figure 7 This is a schematic diagram of a fully parallel AT power supply system in single-circuit breaker mode.

[0035] Figure 8 This is a schematic diagram of a dual-line direct supply system.

[0036] Figure 9 This is a schematic diagram of a single-line direct supply system. Detailed Implementation

[0037] The invention will be further described below with reference to the accompanying drawings.

[0038] The traction substation draws power from the three-phase power grid and feeds it to two busbars of different phases, called the α-phase busbar and the β-phase busbar. The traction network feeders are connected to the busbars and are divided into uplink and downlink lines, etc. Figure 1 As shown (the traction network feeders for both the uplink and downlink lines can be one or more; the diagram shows one feeder as an example). In the diagram, 1QF to 12QF are the feeder circuit breakers installed in the traction substation, AT substation 1, AT substation 2, section substation 1, and section substation 2, respectively, and they are controlled by the corresponding protections 1 to 12.

[0039] The following is a relay protection method for interphase short circuits in traction networks based on phase-to-phase voltage reduction and current increment:

[0040] When a phase-to-phase short-circuit fault occurs in the traction network, taking the upstream line as an example, phase α and phase β are connected, and the phase-to-phase voltage decreases by ΔU. αβ Significant changes were observed. Simultaneously, the fault current primarily flowed through the 1QF-fault point-3QF loop, and the increments ΔI1 and ΔI3 of the measured currents at 1QF and 3QF increased significantly. Therefore, protection 1 reduced the phase-to-phase voltage by ΔU. αβ Greater than the set value U set Furthermore, its current increment ΔI1 is greater than the setting value I. set1 This allows for accurate identification of an out-of-phase short-circuit fault in 1QF; similarly, protection 3 reduces the phase-to-phase voltage by ΔU. αβ Greater than the set value U setFurthermore, its current increment ΔI3 is greater than the setting value I. set1 This allows for accurate identification of an out-of-phase short-circuit fault in the 3QF.

[0041] Due to the special parallel structure of the traction network, when such... Figure 1 When an upward out-of-phase short-circuit fault is detected, tripping only 1QF and 3QF is insufficient to clear the fault, as a fault loop can still be formed via 2QF-6QF-5QF-fault point-9QF-10QF-4QF. Therefore, after a protection device detects an out-of-phase short-circuit fault and a delay t is completed, all circuit breakers on the corresponding line should be tripped. That is, if protection 1 detects an out-of-phase short-circuit fault and a delay t is completed, all circuit breakers 1QF, 5QF, and 7QF on that line should be tripped; similarly, if protection 3 detects an out-of-phase short-circuit fault and a delay t is completed, all circuit breakers 3QF, 9QF, and 11QF on that line should be tripped.

[0042] In the traction network interphase short-circuit relay protection method based on phase-to-phase voltage reduction and current increment, the phase-to-phase voltage reduction is:

[0043] ΔU αβ =U αβq -U αβh

[0044] In the formula, U αβh U is the effective value of the phase-to-phase voltage at the current moment. αβq This is the effective value of the phase-to-phase voltage one power frequency cycle prior.

[0045] The current increment is:

[0046] ΔI=I h -I q

[0047] In the formula, I h I is the effective value of the current at the current moment. q This is the effective value of the current one power frequency cycle ago.

[0048] The activation condition for protecting i (i = 1, 2, 3, or 4) is:

[0049] ΔU αβ >U set &&ΔI i >I seti

[0050] In the formula, U set The voltage setting value is set to avoid the maximum phase-to-phase voltage drop during normal operation; I seti To protect the current setting value of i, it is set according to the maximum value of the current increment during normal operation of the line.

[0051] After protection is enabled, the boot-time U will be... αβq Recorded as (i.e., the effective value of the phase-to-phase voltage one power frequency cycle before startup), I q Recorded as (i.e., the effective value of the current one power frequency cycle before startup) is stored in the protection device. During the delay phase, the phase-to-phase voltage decrease and current increase are respectively:

[0052]

[0053]

[0054] If the starting conditions are met throughout the delay period, all feeder circuit breakers on this line will trip and a signal will be issued after the delay t ends. The operating logic of protections 1-4 is as follows: Figures 2-5 As shown.

[0055] In the above protection method, the detection of an out-of-phase short circuit fault by protection 1 and its subsequent protection actions are independent of the detection of an out-of-phase short circuit fault and its subsequent protection actions by protection 3. They do not need to be synchronized or communicated.

[0056] This invention also provides another method for interphase short-circuit relay protection of traction networks based on phase-to-phase voltage reduction and current increment. Again, taking an interphase short-circuit fault occurring on the upstream line as an example, the difference from the previous protection method is:

[0057] When Protection 1 detects an out-of-phase short-circuit fault and after the delay t ends, it trips all circuit breakers such as 1QF, 5QF, and 7QF on the line, and also trips all circuit breakers such as 3QF, 9QF, and 11QF on the corresponding line of the line.

[0058] Alternatively, if protection 3 detects an out-of-phase short-circuit fault and the delay t ends, it will trip all circuit breakers such as 3QF, 9QF, and 11QF on that line, and also trip all circuit breakers such as 1QF, 5QF, and 7QF on the corresponding line of that line.

[0059] This protection method can provide protection against out-of-phase short-circuit faults that occur when one of the protection devices malfunctions or disconnects due to a fault. Figure 1 For example, if an out-of-phase short circuit fault occurs on the uplink line when the protection device where protection 3 is located malfunctions, protection 1 can reliably identify the out-of-phase short circuit fault and trip all circuit breakers such as 1QF, 5QF, 7QF, 3QF, 9QF, and 11QF.

[0060] The specific implementation method is as follows:

[0061] 1. Dual-circuit breaker mode fully parallel AT power supply system

[0062] For example Figure 6 The implementation scheme of the fully parallel AT power supply system with dual circuit breaker mode, using the first protection method, is as follows:

[0063] Traction network interphase short-circuit protection based on phase-to-phase voltage reduction and current increment is configured for protections 1 to 4 corresponding to circuit breakers 1QF to 4QF. The collected voltages are the voltages to ground of the α-phase T bus and the β-phase T bus, respectively, and the collected current is the T-line current. The protection is activated when the phase-to-phase voltage reduction is greater than the voltage setting value and the T-line current increment is greater than the current setting value. If the activation conditions are met throughout the delay, the protection will operate after the delay ends, tripping all circuit breakers on the corresponding line. That is: interphase short-circuit protection at 1QF requires tripping 1QF, 5QF, and 7QF; interphase short-circuit protection at 2QF requires tripping 2QF, 6QF, and 8QF; interphase short-circuit protection at 3QF requires tripping 3QF, 9QF, and 11QF; and interphase short-circuit protection at 4QF requires tripping 4QF, 10QF, and 12QF.

[0064] In the implementation scheme of the second protection method, after detecting an out-of-phase short-circuit fault and delaying for a period of time, the trip operation is as follows:

[0065] The phase-to-phase short circuit protection at 1QF trips 1QF, 5QF and 7QF, and also trips the circuit breakers on the corresponding electrical phases of the line, namely 3QF, 9QF and 11QF.

[0066] Alternatively, the phase-to-phase short-circuit protection at 2QF trips 2QF, 6QF and 8QF, and trips the circuit breakers on the corresponding electrical phases of the line, namely 4QF, 10QF and 12QF.

[0067] Alternatively, the phase-to-phase short-circuit protection at 3QF trips 3QF, 9QF and 11QF, and trips the circuit breakers on the corresponding electrical phases of the line, namely 1QF, 5QF and 7QF.

[0068] Alternatively, the phase-to-phase short-circuit protection at 4QF trips 4QF, 10QF, and 12QF, and also trips the circuit breakers on the corresponding electrical phases of the line, namely 2QF, 6QF, and 8QF.

[0069] In both of the above schemes, the T-line current and F-line current can be collected and combined to obtain the feeder current. (T-line current) and F-line current The combined feeder current is Its effective value

[0070] 2. Single circuit breaker mode fully parallel AT power supply system

[0071] For example Figure 7The protection implementation scheme for the fully parallel AT power supply system in single-circuit breaker mode, taking the first protection method as an example, is as follows:

[0072] Traction network interphase short-circuit protection based on phase-to-phase voltage reduction and current increment is configured for protections 1 to 4 corresponding to circuit breakers 1QF to 4QF. The collected voltages are the voltages to ground of the α-phase T bus and the β-phase T bus, respectively, and the collected current is the T-line current. The protection is activated when the phase-to-phase voltage reduction is greater than the voltage setting value and the T-line current increment is greater than the current setting value. If the activation conditions are met throughout the delay, the protection will operate after the delay ends, tripping all circuit breakers on the corresponding line. That is: interphase short-circuit protection at 1QF requires tripping 1QF, 5QF, and 6QF; interphase short-circuit protection at 2QF requires tripping 2QF, 5QF, and 6QF; interphase short-circuit protection at 3QF requires tripping 3QF, 7QF, and 8QF; and interphase short-circuit protection at 4QF requires tripping 4QF, 7QF, and 8QF.

[0073] The implementation scheme using the second protection method is similar to that of the fully parallel AT power supply system with dual circuit breakers, and will not be described in detail here.

[0074] Similarly, the T-line current and F-line current can be collected and combined to form the feeder current.

[0075] 3. Dual-line direct supply system

[0076] For example Figure 8 The dual-line direct supply system shown below, taking the first protection method as an example, has the following protection implementation scheme:

[0077] Traction network interphase short-circuit protection based on phase-to-phase voltage reduction and current increment is configured for protections 1 to 4 corresponding to circuit breakers 1QF to 4QF. The collected voltages are the voltages to ground of the α-phase bus and β-phase bus, respectively, and the collected current is the feeder current (T-line current). The protection is activated when the phase-to-phase voltage reduction is greater than the voltage setting value and the feeder current increment is greater than the current setting value. If the activation conditions are met throughout the delay, the protection will operate after the delay ends, tripping all circuit breakers on the corresponding line. That is: interphase short-circuit protection at 1QF requires tripping 1QF and 5QF; interphase short-circuit protection at 2QF requires tripping 2QF and 5QF; interphase short-circuit protection at 3QF requires tripping 3QF and 6QF; and interphase short-circuit protection at 4QF requires tripping 4QF and 6QF.

[0078] The implementation plan for the second protection method is similar to that of the aforementioned system and will not be described in detail here.

[0079] 4. Single-line direct supply system

[0080] For example Figure 9 The single-line direct power supply system shown below, taking the first protection method as an example, has the following protection implementation scheme:

[0081] Traction network interphase short-circuit protection is configured in protections 1 to 2 corresponding to circuit breakers 1QF to 2QF, based on phase-to-phase voltage reduction and current increment. The collected voltages are the voltages to ground of the α-phase bus and β-phase bus, respectively, and the collected current is the feeder current (T-line current). The protection is activated when the phase-to-phase voltage reduction is greater than the voltage setting value and the feeder current increment is greater than the current setting value. If the activation conditions are met throughout the delay period, the interphase short-circuit protection at 1QF trips after the delay ends, and the interphase short-circuit protection at 2QF trips.

[0082] The implementation plan for the second protection method is similar to that of the aforementioned system and will not be described in detail here.

Claims

1. A traction network interphase short-circuit relay protection method based on phase-to-phase voltage reduction and current increment, characterized in that, include: Data collection from traction substations Phase bus voltage and The effective value of the phase-to-phase voltage is calculated by subtracting the voltage of the phase bus; the phase-to-phase voltage reduction is calculated by subtracting the effective value of the phase-to-phase voltage from one power frequency cycle ago and the effective value of the phase-to-phase voltage at the current moment. Data collection connection The effective value of the current of any traction network feeder of the phase busbar is calculated. The current increment is calculated by subtracting the current effective value of the current of the traction network feeder at the current moment from the current effective value one power frequency cycle ago. If the current increment of the traction network feeder is greater than its current increment setting value, and the phase-to-phase voltage reduction is greater than its setting value, then the delay stage begins. If, during the delay phase, the current increment of the traction network feeder is greater than its current increment setting value and the phase-to-phase voltage reduction is greater than its setting value, then after the delay phase, all feeder circuit breakers of the traction network feeder will trip. The current increment of the traction network feeder during the delay phase is calculated by subtracting the effective current value of the traction network feeder at the current moment from the effective current value one power frequency cycle before the start of the delay phase. The phase-to-phase voltage reduction during the delay phase is calculated by subtracting the effective value of the phase-to-phase voltage one power frequency cycle before the start of the delay phase from the effective value of the phase-to-phase voltage at the current moment. Data collection connection The effective value of the current of any traction network feeder of the phase busbar is calculated. The current increment is calculated by subtracting the current effective value of the current of the traction network feeder at the current moment from the current effective value one power frequency cycle ago. If the current increment of the traction network feeder is greater than its current increment setting value, and the phase-to-phase voltage reduction is greater than its setting value, then the delay stage begins. If, during the delay phase, the current increment of the traction network feeder is greater than its current increment setting value and the phase-to-phase voltage reduction is greater than its setting value, then after the delay phase, all feeder circuit breakers of the traction network feeder will trip. The current increment of the traction network feeder during the delay phase is calculated by subtracting the effective current value of the traction network feeder at the current moment from the effective current value one power frequency cycle before the start of the delay phase. The phase-to-phase voltage reduction during the delay phase is calculated by subtracting the effective value of the phase-to-phase voltage one power frequency cycle before the start of the delay phase from the effective value of the phase-to-phase voltage at the current moment. The phase-to-phase voltage reduction setting value is set to avoid the maximum phase-to-phase voltage reduction during normal operation. The current increment setting value is set according to the maximum current increment during normal operation of the line.

2. The traction network interphase short-circuit relay protection method based on phase-to-phase voltage reduction and current increment as described in claim 1, characterized in that, The connection The traction network feeder of the phase busbar is connected to... The traction network feeder of the phase bus includes a T-line; the current of the traction network feeder is the T-line current.

3. The traction network interphase short-circuit relay protection method based on phase-to-phase voltage reduction and current increment as described in claim 2, characterized in that, The connection The traction network feeder of the phase busbar is connected to... The traction network feeder of the phase bus also includes the F line; the current of the traction network feeder is a combination of the T line current and the F line current.

4. A traction network interphase short-circuit relay protection method based on phase-to-phase voltage reduction and current increment, characterized in that, include: Data collection from traction substations Phase bus voltage and The effective value of the phase-to-phase voltage is calculated by subtracting the voltage of the phase bus; the phase-to-phase voltage reduction is calculated by subtracting the effective value of the phase-to-phase voltage from one power frequency cycle ago and the effective value of the phase-to-phase voltage at the current moment. Data collection connection The effective value of the current of any traction network feeder of the phase busbar is calculated. The current increment is calculated by subtracting the current effective value of the current of the traction network feeder at the current moment from the current effective value one power frequency cycle ago. If the current increment of the traction network feeder is greater than its current increment setting value, and the phase-to-phase voltage reduction is greater than its setting value, then the delay stage begins. If, during the delay period, the current increment of the traction network feeder is greater than its current increment setting value, and the phase-to-phase voltage decrease is greater than its setting value, then after the delay period, all feeder circuit breakers of the traction network feeder will trip, and the corresponding circuit breakers connected to the traction network feeder power distribution circuit will trip. All feeder circuit breakers of the traction network feeder of the phase busbar; the current increment of the traction network feeder during the delay period is calculated by subtracting the effective current value of the traction network feeder at the current moment from the effective current value one power frequency cycle before the start of the delay period; The phase-to-phase voltage reduction during the delay phase is calculated by subtracting the effective value of the phase-to-phase voltage one power frequency cycle before the start of the delay phase from the effective value of the phase-to-phase voltage at the current moment. or, Data collection connection The effective value of the current of any traction network feeder of the phase busbar is calculated. The current increment is calculated by subtracting the current effective value of the current of the traction network feeder at the current moment from the current effective value one power frequency cycle ago. If the current increment of the traction network feeder is greater than its current increment setting value, and the phase-to-phase voltage reduction is greater than its setting value, then the delay stage begins. If, during the delay period, the current increment of the traction network feeder is greater than its current increment setting value, and the phase-to-phase voltage decrease is greater than its setting value, then after the delay period, all feeder circuit breakers of the traction network feeder will trip, and the corresponding circuit breakers connected to the traction network feeder power distribution circuit will trip. All feeder circuit breakers of the traction network feeder of the phase busbar; the current increment of the traction network feeder during the delay period is calculated by subtracting the effective current value of the traction network feeder at the current moment from the effective current value one power frequency cycle before the start of the delay period; The phase-to-phase voltage reduction during the delay phase is calculated by subtracting the effective value of the phase-to-phase voltage one power frequency cycle before the start of the delay phase from the effective value of the phase-to-phase voltage at the current moment. The phase-to-phase voltage reduction setting value is set to avoid the maximum phase-to-phase voltage reduction during normal operation. The current increment setting value is set according to the maximum current increment during normal operation of the line.

5. The traction network interphase short-circuit relay protection method based on phase-to-phase voltage reduction and current increment as described in claim 4, characterized in that, The connection The traction network feeder of the phase busbar is connected to... The traction network feeder of the phase bus includes a T-line; the current of the traction network feeder is the T-line current.

6. The traction network interphase short-circuit relay protection method based on phase-to-phase voltage reduction and current increment as described in claim 5, characterized in that, The connection The traction network feeder of the phase busbar is connected to... The traction network feeder of the phase bus also includes the F line; the current of the traction network feeder is a combination of the T line current and the F line current.

Images