Rail transit dc power supply line end low voltage link protection device and method

Abstract

The application provides a low-voltage transfer protection device for the end of a DC power supply line of rail transit, comprising a voltage transmitter A, a voltage transmitter B, a low-voltage protection measurement and control unit and a transfer cable, the input end of the voltage transmitter A is connected with the positive pole and the negative pole of the end of the DC power supply line respectively, and the output end is connected with the low-voltage protection measurement and control unit, the input end of the voltage transmitter B is connected with the positive pole of the end of the DC power supply line and the ground wire respectively, and the output end is connected with the low-voltage protection measurement and control unit, and the output end of the low-voltage protection measurement and control unit is connected with the DC distribution system in the traction substation through the transfer cable. And a protection method, whether the voltage measured by the two voltage transmitters exceeds the setting value is judged respectively, if the setting value is exceeded, the DC distribution system controls the corresponding line circuit breaker to transfer. The application significantly improves the reliability, speed and sensitivity of the over-current protection of the DC line, reduces the engineering investment and the operation and maintenance cost.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of track traffic DC power supply system line protection, and particularly relates to a track traffic DC power supply line end low voltage intertrip protection device and method. BACKGROUND

[0002] Based on the advantages of energy saving, environmental protection, convenient travel and promoting the development of urban economy and life, urban rail transit is developing rapidly in more and more cities. In order to meet the increasing passenger transport demand, the train passenger capacity and train dispatching density are also increasing. At the same time, the load current of the DC power supply line is also greatly increased. When at the end of the long and large DC single-sided power supply line, due to the large line impedance, the overcurrent protection of the traditional DC system is difficult to distinguish the train running load current and the short-circuit fault current, even if the long delay is adjusted to achieve it, but the speed of protection is lost, so the sensitivity and speed of overcurrent protection will be greatly reduced.

[0003] In order to improve the sensitivity of the above-mentioned DC overcurrent protection, the existing domestic and foreign track traffic DC power supply lines usually increase the cross section of overhead ground wire (double splicing) to reduce the short-circuit path impedance or add traction substation at the end of the line to shorten the DC power supply line, but the above-mentioned method will greatly increase the engineering investment cost, increase the operation and maintenance pressure, and also increase the construction difficulty, resulting in high cost of traction power supply system. SUMMARY

[0004] The present application provides a track traffic DC power supply line end low voltage intertrip protection device and method, which sets up a low voltage protection measurement and control unit at the end of the DC power supply line to cut off the line fault by intertripping the corresponding DC line circuit breaker, significantly improves the reliability, speed and sensitivity of the DC line overcurrent protection, reduces the engineering investment and operation and maintenance cost, and provides a new development trend of track traffic DC power supply line protection.

[0005] The technical scheme adopted by the present application is: a track traffic DC power supply line end low voltage intertrip protection device, comprising a voltage transmitter A, a voltage transmitter B, a low voltage protection measurement and control unit and an intertrip cable, the input end of the voltage transmitter A is connected to the positive and negative poles at the end of the DC power supply line respectively, and the output end is connected to the low voltage protection measurement and control unit, the input end of the voltage transmitter B is connected to the positive pole and ground wire at the end of the DC power supply line respectively, and the output end is connected to the low voltage protection measurement and control unit, and the output end of the low voltage protection measurement and control unit is connected to the DC distribution system in the traction substation through the intertrip cable. The output signal of the low voltage protection measurement and control unit is transmitted to the DC distribution system through the intertrip cable to control the intertrip of the corresponding line circuit breaker, cut off the power supply of the positive pole of the DC power supply line and cut off the fault line.

[0006] Further, the jumper cable adopts a multi-core low-voltage control cable.

[0007] Further, the positive pole of the DC power supply line is a catenary, the negative pole is a return rail, and the ground wire is an overhead ground wire.

[0008] Further, the low-voltage protection measurement and control unit comprises a power supply module, an input module, a CPU, a memory, an output module and an external interface, the CPU is connected with the input module, the memory, the output module and the external interface respectively, and the power supply module supplies power for the input module, the CPU and the output module.

[0009] The technical scheme adopted by the present application is also a low-voltage jumper protection method for a DC power supply line at the end of rail transit, comprising the following steps:

[0010] S1: Two voltage transmitters continuously measure the voltage between the positive pole and the negative pole and the voltage between the positive pole and the ground wire at the end of the DC power supply line respectively;

[0011] S2: It is judged whether the voltage between the positive pole and the negative pole and the voltage between the positive pole and the ground wire exceed the setting value respectively, and if any voltage exceeds the setting value, a jumper signal is sent to the DC distribution system in the traction substation;

[0012] S3: The DC distribution system controls the corresponding line circuit breaker to jump.

[0013] Further, in step S2, when any voltage exceeds the setting value, it is simultaneously judged whether the voltage transmitter corresponding to the voltage is faulty, and if the voltage transmitter is not faulty, a jumper signal is sent to the DC distribution system in the traction substation.

[0014] Compared with the prior art, the present application has the beneficial effects that:

[0015] 1. The low-voltage protection measurement and control unit and the voltage transmitter of the present application have the advantages of small size, simple wiring, convenient installation, easy construction, etc., and the installation position is flexible, which can be installed on the catenary support at the end of the DC power supply line or on the trackside at the end of the DC power supply line, without any influence on the civil buildings and other facilities.

[0016] 2. The present application increases the line end low-voltage judgment logic under the premise of meeting the overcurrent protection function of the DC power supply line of rail transit, greatly increases the reliability, sensitivity and speed of the protection, and reduces the cost.

[0017] 3. The present application is completely independent of other protections, simple, economical and reliable, the voltage setting value can be set in a very large range, and the protection sensitivity is very high.

[0018] 4. The application completely solves the problem of the blind area of overcurrent protection at the end of the DC power supply line in the prior art, and greatly reduces the safety accidents such as equipment damage and electric shock of personnel caused by the failure to timely remove the line fault. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 Fig. 1 is a structural schematic diagram of the device of the embodiment of the application;

[0020] Figure 2 Fig. 2 is a structural schematic diagram of the low-voltage protection measurement and control unit of the embodiment of the application;

[0021] Figure 3 Fig. 3 is a protection logic diagram of the low-voltage protection measurement and control unit of the embodiment of the application;

[0022] Figure 4 Fig. 4 is a flowchart of the method of the embodiment of the application.

[0023] Fig. 1 is a structural schematic diagram of the device of the embodiment of the application; DETAILED DESCRIPTION

[0024] In order to enable those skilled in the art to better understand the technical solutions of the application, the application will be described in detail below with reference to the drawings and specific embodiments.

[0025] The embodiment of the application provides a low-voltage transfer trip protection device at the end of a DC power supply line of rail transit, as shown in Fig. 1, which comprises a voltage transmitter A1, a voltage transmitter B2, a low-voltage protection measurement and control unit 3 and a transfer trip cable 4. Figure 1-3 The input end of the voltage transmitter A1 is connected to the positive pole and the negative pole at the end of the DC power supply line respectively, and the output end is connected to the low-voltage protection measurement and control unit 3. The input end of the voltage transmitter B2 is connected to the positive pole at the end of the DC power supply line and the ground wire respectively, and the output end is connected to the low-voltage protection measurement and control unit 3. In the rail transit system, the positive pole of the DC power supply line is the contact net, the negative pole is the return rail, and the ground wire is the overhead ground wire. The output end of the low-voltage protection measurement and control unit 3 is connected to the DC power distribution system 5 in the remote traction substation through the transfer trip cable 4. The transfer trip cable 4 adopts a multi-core low-voltage control cable. The DC power distribution system 5 comprises a DC switch cabinet and a DC protection device, signals are transmitted to the DC protection device through the transfer trip cable 4, and the DC protection device controls the line circuit breaker in the DC switch cabinet. The low-voltage protection measurement and control unit 3 comprises a power module, an input module, a CPU, a memory, an output module and an external interface, the CPU is connected to the input module, the memory, the output module and the external interface respectively, and the power module supplies power to the input module, the CPU and the output module.

[0026] The voltage transmitter A1 measures the voltage between the positive electrode and the negative electrode, and the voltage transmitter B2 measures the voltage between the positive electrode and the ground. The low-voltage protection measurement and control unit 3 collects the voltage signals measured by the voltage transmitter A1 and the voltage transmitter B2, performs internal operation and logical judgment, and triggers the trip signal of the protection outlet when the voltage between the positive electrode and the negative electrode or the voltage between the positive electrode and the ground is greater than the low-voltage protection setting value. The trip signal output by the low-voltage protection measurement and control unit 3 is transmitted to the DC power distribution system 5 through the trip cable 4 to control the corresponding line circuit breaker trip, cut off the power supply of the positive electrode of the DC power supply line, realize protection tripping, and remove the fault line.

[0027] The embodiment of the application provides a low-voltage trip protection method for a rail transit DC power supply line end, as shown in the figure, comprising the following steps: Figure 4

[0028] S1: Two voltage transmitters continuously measure the voltage between the positive electrode and the negative electrode at the end of the DC power supply line and the voltage between the positive electrode and the ground;

[0029] S2: Judge whether the voltage between the positive electrode and the negative electrode and the voltage between the positive electrode and the ground exceed the low-voltage protection setting value, and if any voltage exceeds the low-voltage protection setting value, judge whether the voltage transmitter corresponding to the voltage is faulty, and if the voltage transmitter is not faulty, send a trip signal to the DC power distribution system 5 in the traction substation;

[0030] S3: After receiving the trip signal, the DC power distribution system 5 controls the corresponding line circuit breaker trip.

[0031] The above describes the application through the embodiments, but the content described is only exemplary embodiments of the application and cannot be considered as limiting the implementation range of the application. The protection scope of the application is defined by the claims. Any similar technical solution that utilizes the technical solutions described in the application or is inspired by the technical solutions of the application within the essence and protection range of the application, achieves the above technical effects, or makes equivalent changes and improvements to the application range, should still belong to the patent coverage and protection range of the application.​

Claims

1. A low-voltage interlocking protection device at the end of a DC power supply line for rail transit, characterized in that: The system includes voltage transmitter A, voltage transmitter B, a low-voltage protection and control unit, and a jumper cable. The input terminals of voltage transmitter A are connected to the positive and negative terminals of the end of the DC power supply line, respectively, and its output terminal is connected to the low-voltage protection and control unit. The input terminals of voltage transmitter B are connected to the positive terminal and ground wire of the end of the DC power supply line, respectively, and its output terminal is connected to the low-voltage protection and control unit. The output terminal of the low-voltage protection and control unit is connected to the DC power distribution system within the traction substation via the jumper cable. The system includes the following steps: S1: Two voltage transmitters continuously measure the voltage between the positive and negative terminals at the end of the DC power supply line, and the voltage between the positive terminal and ground, respectively. S2: Determine whether the voltage between the positive and negative terminals and the voltage between the positive terminal and the ground wire exceed the set value. If either voltage exceeds the set value, send a trip signal to the DC power distribution system in the traction substation. S3: The corresponding line circuit breaker trips in the DC power distribution system control. In step S2, when any voltage exceeds the set value, it is simultaneously determined whether the voltage transmitter corresponding to that voltage is faulty. If the voltage transmitter is not faulty, a trip signal is sent to the DC power distribution system in the traction substation.

2. The low-voltage interlocking protection device at the end of a DC power supply line for rail transit as described in claim 1, characterized in that: The jumper cable is a multi-core low-voltage control cable.

3. The low-voltage interlocking protection device at the end of a DC power supply line for rail transit as described in claim 1, characterized in that: The positive terminal of the DC power supply line is the contact network, the negative terminal is the return rail, and the ground wire is an overhead ground wire.

4. The low-voltage interlocking protection device at the end of a DC power supply line for rail transit as described in claim 1, characterized in that: The low voltage protection and control unit includes a power supply module, an input module, a CPU, a memory, an output module, and an external interface. The CPU is connected to the input module, the memory, the output module, and the external interface, respectively. The power supply module provides power to the input module, the CPU, and the output module.

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