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Keywords

flexible DC grid; hybrid DC circuit breaker; thyristor; capacitive energy transfer; reclosing detection

Abstract

The thyristor-based hybrid DC circuit breaker (THDCB) pre-charges the capacitor through the DC system and adopts LC oscillation to assist fault current commutation and interruption. However, the existing schemes have problems such as a large amplitude of oscillation current and the lack of a reclosing detection function, which limits their application in overhead-line flexible DC grids with high instantaneous fault rates. To address this issue, a THDCB with low-amplitude oscillation current and a reclosing detection function is proposed. A capacitor voltage-divider pre-charging method and a capacitor energy transfer method are adopted to reduce the oscillation current amplitude and to provide the reclosing detection function without increasing additional cost and control complexity. First, the reasons for the high-amplitude oscillation current generated by existing schemes are analyzed, and the capacitor voltage-divider pre-charging and capacitor energy transfer scheme is proposed. Second, the topology of the proposed THDCB is presented, and its operating principles of DC current interruption and reclosing detection are analyzed. Then, parameter influence analysis is carried out, and the selection ranges of capacitance and inductance parameters are determined. Finally, simulation cases and comparative analysis are conducted to verify the effectiveness and techno-economic performance of the proposed scheme. This paper may provide a reference for promoting the development of overhead-line flexible DC grids in China.

DOI

10.19781/j.issn.1673-9140.2025.06.016

First Page

164

Last Page

174

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