Post — DC fault recharging of the H-bridge modular multilevel converter

This paper presents a new recharging strategy for the DC link capacitors of the H-bridge modular multilevel converter (HB-M2C) following DC side faults. The recharging strategy investigated in this paper focuses on the charging algorithm that ensures controlled charging of the DC link capacitors, while ensuring that voltage across the H-bridge cell capacitors remain balanced, and within switching device operating limits. This control strategy limits any potential inrush current from the AC side during re-energizing of the DC link following a DC side fault, without the need of any external circuitry or charging resistors. This may improve the fast recovery of the power networks from DC side faults and minimize the impact on the AC grids. To demonstrate the technical feasibility of the proposed recharging scheme, an H-bridge modular multilevel converter with reverse power blocking capability is simulated.