A DC circuit breaker and its control method and device

Abstract

The invention relates to a direct current circuit breaker, a control method and device thereof. The method comprises the following steps that: after a system has a short circuit fault, a mechanical switch in a main current circuit is controlled to be disconnected and a zero current circuit is controlled to be conducted; when the current of a mechanical switch S is reduced to zero, a zero-voltage circuit is controlled to be conducted, so that a loop is formed between the zero-voltage circuit and a zero-current circuit to carry out follow current, and the voltage clamp at two ends of the mechanical switch is zero so as to prevent an arc from rekindling; after the follow current is finished, the system voltage reversely charges a precharging capacitor in the zero-current circuit to complete the disconnection. According to the invention, a zero-crossing point of the current is manufactured through the forerunner zero-passing current circuit, so that a zero-crossing arc of the mechanical switch is extinguished, and the short-circuit current is ensured to be completely transferred to a null-current circuit; then the zero-voltage circuit is switched on to clamp the recovery voltage of themechanical switch after the arc is extinguished so as to prevent the arc from rekindling and ensure that the mechanical switch is reliably extinguished.

Description

technical field [0001] The invention relates to a direct current circuit breaker and its control method and device, belonging to the technical field of direct current circuit breakers. Background technique [0002] Compared with the AC grid, the DC grid can make distributed energy access more convenient, and more and more DC electrical appliances are connected, which makes the research and development of the DC grid particularly important. As the key equipment in the DC power grid, the DC circuit breaker can not only switch on or cut off part of the power equipment or lines according to the needs of the operation under normal operation conditions, and play a control role, but also can switch the fault to the current equipment or line when the current equipment or line fails. Part of it is quickly cut off from the grid to play a protective role. [0003] The opening time of traditional mechanical DC circuit breakers is generally tens of milliseconds, which is far from meetin...

AI Technical Summary

Problems solved by technology

[0009] The purpose of the present invention is to provide a DC circuit breaker and its control method and device, which are used to solve the problem that the short-circuit current of the mechanical switch cannot be transferred reliably due to the failure of zero point during the transfer process, resulting in unreliable breaking

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