Aiming at the difficulty of fault isolation caused by large short-circuit fault current and no natural zero crossing of current in flexible direct distribution network,a hybrid capacitor-assisted circuit breaker is proposed.The circuit breaker possesses a two-stage current limiting structure.The low-resistance current limiting module is used to quickly limit the fault current in the initial stage and achieve the fault-current transfer.The high-resistance current limiting module is used to ensure the effective isolation.It can play a current limiting role before the fault line is identified.Compared with the typical method,the capacitor-assisted module can limit the development of the initial fault current and greatly reduce the peak current value of the main-breaker branch,and it has minimum impact on the main branch during the normal operation.Finally,a six-terminal DC distribution network is established by PSCAD/EMTDC for simulation analysis,and results show that the proposed scheme can significantly limit the fault current and meet both the economy and practicality.
fault current limiterscapacitanceshort circuit currentsflexible DC distribution networkDC short circuit breaker
NETL
NSTL
万方数据
