The hybrid DC circuit breaker(HDCB) is the mainstream technical solution for achieving selective rapid isolation of fault lines in VSC-based DC transmission systems

existing hybrid high-voltage DC circuit breaker technologies face limitations such as constrained interruption capability and high costs. Therefore

an HDCB turned-off-assisted with capacitance self-charging (TWCS-HDCB) is proposed in this paper. By pre-charging capacitors with normal operating currents in the DC system and controlling the switching of power electronic devices in the module

resonance and oscillatory reversal between capacitors and inductors are generated to facilitate rapid current transfer

thereby achieving fast fault current interruption. Firstly

this paper elaborates on the topology and operational principles of the basic switching module unit. Next

the topology of TWCS-HDCB is proposed

and the working principle of TWCS-HDCB when breaking the fault current is studied. Then

the influence mechanism of the capacitance and inductance for the overall breaking performance is revealed

and the component selection method of the switch module unit is determined. Finally

simulation verification and technical performance comparison analysis based on Zhangbei VSC-based DC grid reveal that the proposed TWCS-HDCB has strong breaking capacity

effectively reduces equipment cost and floor area

and has superior technical and economic performance.