A series-connected capacitive high voltage DC circuit breaker and its control method

Abstract

The invention relates to a series capacitor type high-voltage direct current breaker and a control method thereof. The breaker comprises direct current breaker units which are connected in series, and each direct current breaker unit comprises a change-over switch, a switching circuit and an energy consumption device which are connected in parallel. The change-over switch adopts a mechanical switch, and the switching circuit adopts a resistance capacitance branch circuit, and the energy consumption device adopts a lightning arrester. The high-voltage direct current breaker is connected with a control circuit, and the mechanical switch detects failure current and acts at the T1moment, and transfers the failure current into the resistance capacitance branch circuit. The failure current charges a capacitor, and controls switching-on and switching-off of the mechanical switch. Before the mechanical switch witches off at the T2 moment, charging voltage on two ends of the capacitor throughout is lower than arcing voltage at fractures of the mechanical switch. When the voltage on two ends of the capacitor reaches operation voltage of the lightning arrester, the control circuit controls the lightning arrester to act at the T3 moment so that energy can be released from the lightning arrester. According to the series capacitor type high-voltage direct current breaker and the control method thereof, the mechanical switch does not have electric arc, non-arc breaking off is realized, energy is released through utilization of the lightning arrester, quick extinguishing of the electric arc is realized, and the failure current is cut off.

Description

technical field [0001] The invention relates to a power system circuit breaker, in particular to a series-connected capacitive high-voltage direct current circuit breaker and a control method thereof. Background technique [0002] High-voltage DC circuit breakers have broad application prospects in IGBT-based multi-terminal flexible DC transmission and DC grid systems. The traditional AC circuit breaker mainly uses the two current zero points of the AC current in each cycle to extinguish the arc, thereby breaking the current, but there is no natural zero point in the DC system, so it is difficult for the high voltage DC circuit breaker to break the current It is how to extinguish the arc quickly. A DC circuit breaker is generally composed of three parts: a transfer switch, a transfer circuit and an energy consumer, such as figure 1 shown. Its main breaking sequence is: when the gate is opened, the current is first transferred from the transfer switch to the conversion cir...

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Problems solved by technology

[0003] However, the existing DC circuit breaker adopts the arc negative resistance characteristic of the circuit breaker and the auxiliary branch capacitor inductance to resonate, so as to create a zero-crossing point on the mechanical switch to realize breaking, and the existing DC circuit breaker has a resonant branch and arc. Auxiliary branch capacitance and inductance are prone to resonance

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