Relay protection method and system based on flexible traction network

Abstract

The invention provides a relay protection method and a relay protection system based on a flexible traction network, which are used for solving the problems of imperfect, unreliable and insensitive relay protection of the flexible traction network. The relay protection method comprises the following steps: configuring protection devices for substations and subareas, establishing a local area network, acquiring bus voltage of the substations and adjacent substations and current and position states of all switches by the substation protection devices, judging an operation mode, selecting incoming line switch current as a reference current direction when the bus voltage is less than a preset threshold value, calculating the current directions of other switches through current relative phase comparison, and comparing the current directions with the current directions in the truth table; when the result is consistent with the truth table, determining a fault position and tripping a corresponding switch. Fault points can be quickly and accurately removed, the power failure time is shortened, the power failure range is narrowed, and the safety and reliability of a traction network are improved; meanwhile, all operation modes can be self-adapted, manual constant value adjustment is not needed, human errors during constant value adjustment can be avoided, and potential safety hazards are reduced.

Description

technical field [0001] The invention belongs to the field of railway electric power safety, and in particular relates to a relay protection method and system based on a flexible traction network. Background technique [0002] The normal operation of railway trains requires the traction network to provide electricity. figure 1 Shown is a schematic structural diagram of a conventional railway traction network in the prior art. Such as figure 1 shown. Because the voltage phases of each section of the traction network are different, the traction network where the substation and the sub-area are located needs to be equipped with electrical phase separation. During normal operation, the bus tie switch of the substation and the sub-area must be opened, with the tie switch as the boundary. The traction nets on both sides operate independently. The protection configuration of the traction network under this operation mode is shown in Table 1. Its protection configuration and coor...

AI Technical Summary

Problems solved by technology

[0013] (1) The longitudinal differential protection only protects the range between the current transformers on both sides, and does not protect the range outside the current transformers (such as the busbar), and the protection range is incomplete

[0014] (2) When setting the longitudinal differential protection, it is necessary to avoid the differential current brought by the current taken by the train in normal operation, resulting in a large setting value of the longitudinal differential protection and insufficient protection sensitivity

[0015] (3) After the short circuit, the bus voltage is very low. For the distance protection where the partition is located, the impedance angle cannot be accurately calculated in a large range, which will cause the protection of the four feeders in the partition to operate simultaneously, and the protection selectivity will be lost.

[0016] (4) Under most fault conditions, the 4 feeders of the partition station have a fault current, so that the low-voltage start-up overcurrent protection of the 4 feeders operates simultaneously, which is not selective

[0017] (5) Both the distance protection and the low-voltage start-up overcurrent protection need to use the bus voltage. When the PT is disconnected, the distance protection will malfunction or be blocked, and the overcurrent protection will malfunction due to the large load current. The protection is not completely reliable, and the distance protection or overcurrent protection may fail

[0018] (6) For different operation modes of the traction network (power supply device failure, support power supply), distance protection and low-voltage start-up over-current protection set different setting values. The adjustment of the setting value needs to be manually adjusted when switching the operation mode, which is inconvenient to use

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