Hybrid DC current breaker topological structure

Abstract

The invention relates to a hybrid DC current breaker topological structure. The hybrid DC current breaker topological structure is structurally characterized by comprising three parallel branches, wherein the first branch comprises a first mechanical switch K1, a second mechanical switch K2 and a capacitor C; the first mechanical switch K1 and the second mechanical switch K2 are connected in series and the second mechanical switch K2 and the capacitor C are connected in parallel, so as to get continuity of the normal working current of a system; the second branch is a solid-state switch S which is composed of a plurality of IGBT modules connected in series, wherein each IGBT module comprises two IGBTs in reversed series connection and is used for realizing two-way cutoff of fault current; the third branch is an energy release branch consisting of multiple ZnO lightning arresters in series and parallel connection. The hybrid DC current breaker disclosed by the invention has the advantages of low loss, achievement of two-way rapid cutoff and guarantee of reliable continuity of the solid-state switch.

Description

technical field [0001] The invention belongs to the technical field of direct current circuit breakers, and in particular relates to a topology structure of a hybrid direct current circuit breaker. Background technique [0002] At present, the flexible DC distribution network has significant technical and economic advantages compared with the traditional AC distribution network in terms of increasing the power supply radius and capacity, reducing line costs, facilitating distributed power access, and improving system efficiency. However, in practical applications, due to the lack of practical and reliable DC circuit breakers, it is difficult to clear the short-circuit faults on the DC side of the flexible DC distribution network in time, which has greatly restricted its development. [0003] At present, the development of DC circuit breakers mainly faces the following difficulties: (1) DC current does not have a natural zero-crossing point, and it is difficult to extinguish ...

AI Technical Summary

Problems solved by technology

However, in practical applications, due to the lack of practical and reliable DC circuit breakers, it is difficult to clear the DC side short-circuit faults of the flexible DC distribution network in time, resulting in great restrictions on its development.

[0003] At present, the development of DC circuit breakers mainly faces the following difficulties: (1) DC current does not have a natural zero-crossing point, and it is difficult to extinguish the DC arc; (2) After the current is cut off, a high recovery overvoltage will be generated at both ends of the circuit breaker; (3) The energy stored in the system inductance needs to be released after the current is cut off; (4) Applications such as DC transmission and distribution networks require short break time

[0004] Commonly used DC circuit breakers include: traditional mechanical DC circuit breakers, all-solid-state DC circuit breakers and hybrid DC circuit breakers; their main advantages and disadvantages are: traditional mechanical DC circuit breakers have low loss and slow breaking speed; all-solid-state DC circuit breakers The breaking speed of the circuit breaker is fast and the loss is large; the hybrid DC circuit breaker combines the advantages of both, and has become the most promising solution in the field of medium and high voltage DC

However, in a high-voltage system, the on-state voltage drop generated by a large number of fully-controlled devices connected in series is generally tens of volts or even nearly a hundred volts. Simply relying on the arc voltage cannot 100% guarantee the conduction and complete commutation of the solid-state switch.

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