Direct-current breaker and cutoff method thereof

Abstract

The invention discloses a direct-current breaker including a converter circuit, a cutoff circuit and an energy-absorption circuit which are connected in parallel. A breaker comprises a control circuit which is connected to the converter circuit, the cutoff circuit, the energy-absorption circuit and a main circuit respectively. The converter circuit comprises converter units connected in series and at least one mechanical switch. The cutoff circuit comprises N cutoff units connected in series. Arc-less breaking of current can be realized rapidly with the direct current breaker controlled; and number of switches of a power semiconductor is greatly decreased on the premise of realizing two-way cutoff capacity is realized, and cost is reduced.

Description

technical field [0001] The invention belongs to the technical field of power electronics, and in particular relates to a DC circuit breaker and a breaking method thereof. Background technique [0002] With the application of multi-terminal flexible DC and DC grid technology based on voltage source converter (VSC), fast DC circuit breakers have become one of the key equipment to ensure the stable, safe and reliable operation of the system. In the AC system, the AC current has two natural zero-crossing points in one cycle, and the AC circuit breaker uses the natural zero-crossing points of the current to cut off the current, while in the DC system, the DC current does not have a natural zero-crossing point, so the DC current The breaking of the current is much more difficult than the breaking of the alternating current. [0003] There are usually two ways to break the DC current. One is to add an auxiliary circuit on the basis of the conventional AC mechanical circuit breaker...

AI Technical Summary

Problems solved by technology

[0003] There are usually two ways to break the DC current. One is to add an auxiliary circuit on the basis of the conventional AC mechanical circuit breaker, and superimpose the increased oscillation current on the DC current of the breaking arc gap. Breaking the circuit, the mechanical circuit breaker manufactured by this principle cannot meet the requirements of the multi-terminal flexible DC transmission system in terms of breaking time; Although the solid-state circuit breaker manufactured by this principle can meet the requirements of the multi-terminal flexible DC system in terms of time, the loss is too large during normal conduction, and the economy is poor.

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