In order to construct the voltage-sourced converter high-voltage direct current grids, the high capacity direct current circuit breakers (DCCBs) are in demand. The hybrid DCCB has been the mainstream proposal, where the high-voltage solid-state switch (HVSS) is the key component for breaking the final fault current. Investigating the current commutation between the breaking branch and energy-absorbing branch, a hybrid DCCB with repositioned current commutation module (CCM) and redesigned HVSS is proposed in this study. By analysing the equivalent circuit of the CCM and HVSS, the detailed transient stages during current interruption procedure have been revealed, and the comparisons of different topologies for HVSS are made in-depth. The repositioned CCM can greatly decrease the transient voltage stress for HVSS and CCM whilst the improved HVSS including metal oxide varistor can maintain better interruption performances. Then the actual prototypes are developed to verify the effectiveness of the improved hybrid DCCB topology. In the end, a 500 kV DCCB is realised based on the proposed HVSS, which can ensure the reliability and convenience of the hybrid DCCB.

中文翻译：

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±500 kV电压源换流器高压直流电网中混合直流断路器分断的研究

为了构建电压源转换器高压直流电网，需要大容量直流断路器（DCCB）。混合DCCB一直是主流建议，高压固态开关（HVSS）是断开最终故障电流的关键组件。为了研究断路支路和能量吸收支路之间的电流换向，本研究提出了一种具有重新定位的电流换向模块（CCM）和重新设计的HVSS的混合DCCB。通过分析CCM和HVSS的等效电路，揭示了电流中断过程中的详细瞬态阶段，并深入比较了HVSS的不同拓扑结构。重新放置的CCM可以大大降低HVSS和CCM的瞬态电压应力，而改进的HVSS（包括金属氧化物压敏电阻）可以保持更好的中断性能。然后，开发实际的原型以验证改进的混合DCCB拓扑的有效性。最后，基于提出的HVSS实现了500 kV DCCB，可以保证混合DCCB的可靠性和便利性。