Rail transit dc protection adaptive fixed value switching system

Abstract

The application provides a track traffic direct current protection adaptive fixed value switching system, which comprises an over-range switch position auxiliary contact and a direct current feeder protection device, the over-range switch position auxiliary contact is connected with an over-range switch, the over-range switch is located in a first traction substation, the over-range switch position auxiliary contact is connected with the direct current feeder protection device in the second traction substation through a control cable, when the over-range switch is in a split position state, the direct current feeder protection device adopts a high current and low time delay setting value group, when the over-range switch is in a closed position state, the direct current feeder protection device adopts a low current and high time delay setting value group. The application increases the judgment logic of the split and closed position of the over-range switch under the premise of meeting the over-current protection function of the track traffic direct current power supply line, ensures that different setting value groups are adopted under different operation conditions of the direct current power supply system, realizes the balance of the protection speed and sensitivity, and does not affect the cost.

Description

Technical Field

[0001] This invention belongs to the field of line protection for DC power supply systems in rail transit, and specifically relates to an adaptive setting switching system for DC protection in rail transit. Background Technology

[0002] Based on its advantages in energy conservation, environmental protection, convenient travel, and promoting urban economic and social development, urban rail transit is rapidly developing in more and more cities. To meet the ever-increasing passenger transport demand, train passenger capacity and train departure frequency are also increasing daily. Simultaneously, the load current of DC power supply lines is also increasing significantly. Some urban rail transit lines have already crossed seas, rivers, or lakes. Due to terrain limitations, the sections crossing seas, rivers, or lakes are usually very long, reaching 7-8 km when power supply is inter-regional (one traction substation is disconnected). In this case, when the contact network at the end of the inter-regional power supply line short-circuits to the overhead ground wire, due to the high line impedance, the overcurrent protection of the DC system has difficulty distinguishing between the train operating load current and the short-circuit fault current. Even if a long delay is set, the protection's speed is lost, thus significantly reducing the sensitivity and speed of the overcurrent protection.

[0003] In existing domestic and international rail transit DC power supply lines, to improve the sensitivity of DC overcurrent protection in the aforementioned situations, methods such as increasing the cross-section of the overhead ground wire to reduce the short-circuit path impedance or extending the setting time of the line overcurrent protection are commonly used. However, these methods either increase engineering investment costs or sacrifice the speed of protection, increasing safety risks before line faults are cleared. They also increase operation and maintenance pressure and construction difficulty, resulting in persistently high costs for traction power supply systems. Summary of the Invention

[0004] This invention addresses the issue of blind spots in DC overcurrent protection due to the similarity between the short-circuit current of the overhead ground wire and the normal operating load current at the end of long-distance DC cross-regional power supply lines, making it difficult for DC line overcurrent protection to distinguish between them. It provides an adaptive setting switching system for rail transit DC protection. By determining the position of the cross-regional disconnecting switch on the overhead contact line, the system automatically switches the protection settings to meet the requirements of using a high-current, low-delay setting group under normal power supply conditions and a low-current, high-delay setting group under cross-regional power supply conditions. This ensures that different setting groups are used under different operating conditions, achieving a balance between protection speed and sensitivity, significantly improving the sensitivity of DC line overcurrent protection, and reducing project investment and operation and maintenance costs.

[0005] The technical solution adopted in this invention is: an adaptive setting value switching system for DC protection in rail transit, including an auxiliary contact for the over-zone switch position and a DC feeder protection device. The auxiliary contact for the over-zone switch position is connected to the over-zone switch and is used to reflect the position status of the over-zone switch. The over-zone switch is located in a first traction substation, and a second traction substation is located next to the first traction substation. The auxiliary contact for the over-zone switch position is connected to the DC feeder protection device in the second traction substation through a control cable. When the over-zone switch is in the open position, the DC feeder protection device adopts a high current and low delay setting value group; when the over-zone switch is in the closed position, the DC feeder protection device adopts a low current and high delay setting value group.

[0006] Furthermore, the setting value group is the setting value group for overcurrent protection.

[0007] Furthermore, the first traction substation and the second traction substation are located in the same DC power supply system, and the DC feeder protection device is used to protect the DC power supply system.

[0008] Compared with the prior art, the beneficial effects of this invention are:

[0009] 1. Under the premise of satisfying the overcurrent protection function of DC power supply lines for rail transit, this invention adds the judgment logic of the open / close position of the cross-zone switch, so as to ensure that different setting value groups are used under different operating conditions of the DC power supply system, so as to achieve a balance between protection speed and sensitivity, without affecting the cost.

[0010] 2. This invention optimizes the protection configuration of DC cross-regional power supply lines, completely solving the problem of blind spots in the protection of DC cross-regional power supply line end faults in existing DC power supply line protection, and greatly reducing safety accidents such as equipment damage and electric shock caused by the inability to disconnect line faults in time.

[0011] 3. This invention utilizes existing equipment and devices, offering advantages such as simple wiring, convenient installation, and ease of construction. It reduces operation and maintenance workload and improves the reliability of DC power supply line protection without affecting project investment. This invention does not affect existing DC protection systems and is simple, economical, and reliable. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the structure of an embodiment of the present invention.

[0013] In the diagram: 1-Auxiliary contact of the over-zone switch position, 2-DC feeder protection device, 3-Over-zone switch, 4-First traction substation, 5-Second traction substation. Detailed Implementation

[0014] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0015] Embodiments of the present invention provide an adaptive setpoint switching system for DC protection in rail transit, such as... Figure 1 As shown, it includes an auxiliary contact 1 for the over-range switch position and a DC feeder protection device 2. A first traction substation 4 and two second traction substations 5 are located in the same DC power supply system, with the two second traction substations 5 located on either side of the first traction substation 4. The over-range switch 3 is located within the first traction substation 4. The auxiliary contact 1 for the over-range switch position is connected to the over-range switch 3 and is used to reflect the position status of the over-range switch 3. The auxiliary contact 1 for the over-range switch position is connected to the DI interface of the DC feeder protection device 2 within the second traction substation 5 via a control cable. The DC feeder protection device 2 is used to receive the position signal of the over-range switch 3 to trigger the switching of the protection setting value group, providing protection for the DC power supply system within the protection zone. When the over-range switch 3 is in the open position, the DC feeder protection device 2 uses a high current, low delay setting value group; when the over-range switch 3 is in the closed position, the DC feeder protection device 2 uses a low current, high delay setting value group.

[0016] Under normal power supply conditions, the over-range switch 3 is in the open position, and the DC feeder protection device 2 uses a high-current, low-delay setting value group. When the first traction substation 4 is disconnected and power is supplied from the over-range area, the over-range switch 3 in the first traction substation 4 closes, and the over-range switch position auxiliary contact 1 sends a signal indicating that the over-range switch 3 is closed to the DC feeder protection device 2 via a control cable. The DC feeder protection device 2 then switches its setting value group to a low-current, high-delay setting value group. When the first traction substation 4 resumes power supply, the over-range switch 3 opens, and the over-range switch position auxiliary contact 1 sends a signal indicating that the over-range switch 3 is open to the DC feeder protection device 2 via a control cable. The DC feeder protection device 2 then switches its setting value group to a high-current, low-delay setting value group.

[0017] The present invention has been described in detail above through embodiments, but the content described is only an exemplary embodiment of the present invention and should not be considered as limiting the scope of the present invention. The scope of protection of the present invention is defined by the claims. Any technical solutions designed by those skilled in the art using the technical solutions described in the present invention, or designed by those skilled in the art under the inspiration of the technical solutions of the present invention, within the substance and protection scope of the present invention, to achieve the above-mentioned technical effects, or any equivalent changes and improvements made to the scope of the application, should still fall within the patent protection scope of the present invention.

Claims

1. A DC protection adaptive setting switching system for rail transit, characterized in that: The system includes an auxiliary contact for a cross-zone switch position and a DC feeder protection device. The auxiliary contact for the cross-zone switch position is connected to the cross-zone switch and is used to reflect the position status of the cross-zone switch. The cross-zone switch is located in a first traction substation, and a second traction substation is located next to the first traction substation. The auxiliary contact for the cross-zone switch position is connected to the DC feeder protection device in the second traction substation via a control cable. The DC feeder protection device is equipped with two sets of pre-set setting value groups. When the cross-zone switch is in the open position, the system is in normal power supply mode. At this time, the system impedance is small and the short-circuit current is large. The DC feeder protection device adopts the first setting value group, which has a high current setting value and a low delay setting value to achieve rapid fault clearing. When the cross-zone switch is in the closed position, the system is in the cross-zone power supply mode. At this time, the power supply path becomes longer, the system impedance increases significantly, and the short-circuit current level at the same fault point decreases. The DC feeder protection device adopts the second setting value group, which has a lower current setting value and a higher delay setting value to improve protection sensitivity and cooperate with downstream protection. The position status of the over-zone switch is connected to the switching input circuit of the DC feeder protection device through its auxiliary contacts. The DC feeder protection device automatically selects the corresponding setting value group according to the auxiliary contact status of the over-zone switch to realize adaptive switching of protection settings.

2. The adaptive setpoint switching system for DC protection of rail transit as described in claim 1, characterized in that: The setting value group is the setting value group for overcurrent protection.

3. The adaptive setpoint switching system for DC protection of rail transit as described in claim 1, characterized in that: The first traction substation and the second traction substation are located in the same DC power supply system, and the DC feeder protection device is used to protect the DC power supply system.

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