Current interruption characteristic optimization circuit of current injection type DC circuit breaker

Abstract

The invention provides a current interruption characteristic optimization circuit of a current injection type DC circuit breaker. The optimization circuit comprises a vacuum switch, a discharge branchcircuit and an LC resonance branch circuit, wherein the LC resonance branch circuit is connected with the vacuum switch in parallel, the discharge branch circuit is connected with a capacitor of theLC resonance branch circuit in parallel, and the capacitor of the LC resonance branch circuit realizes the discharge voltage reduction during the low current interruption process of the DC circuit breaker through the discharge branch circuit. The optimization circuit not only improves the low current interruption characteristic under the premise of maintaining the high fault current interruption characteristic, but also avoids the increased equipment complexity, high loss and low reliability caused by a series saturable reactor in the prior art at the same time. Meanwhile, the invention can further omit a buffer branch circuit structure of the novel current injection type DC circuit breaker at present, and greatly increases the equipment reliability.

Description

technical field [0001] The invention relates to electric power technology, in particular to a circuit for optimizing current breaking characteristics of a current injection type DC circuit breaker. Background technique [0002] In end-to-end LCC-HVDC (line commutated converter high voltage direct current, high voltage direct current based on phase-controlled converter), DC circuit breakers are widely studied and applied. The structure of the parallel LC resonant branch circuit achieves the purpose of fault removal by superimposing the resonant current on the DC fault current in reverse. This method of manufacturing the "artificial zero-crossing point" of the AC circuit breaker is called the passive resonant type. DC circuit breaker. [0003] With the continuous maturity of VSC-HVDC (voltage sourced converter high voltage direct current) technology, multi-terminal flexible DC grids have become a development trend. Although flexible DC grids have broad prospects, due to their...

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Problems solved by technology

[0005] However, in the case of small current breaking, the breaking time of the Inj-LC DC circuit breaker cannot meet the requirements of the flexible DC grid demonstration project, and the large transient recovery voltage borne by the mechanical fracture makes the Inj-LC DC circuit breaker exist. The risk of breaking failure, it is urgent to improve the small current breaking problem of current injection DC circuit breaker through the optimization of circuit topology

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