In the HVDC transmission systems, AC filter circuit breakers (CB) are switched frequently to keep the balance of reactive power. CB stays under AC/DC hybrid conditions since the current flowing through AC filter is capacitive. Moreover, due to the differences between the resistances of multiple breaks, the unbalanced voltage distribution is easy to occur, which will cause a high transient overvoltage on one break among them. In recent years, the circuit breaker explosion accidents have occurred many times. In this paper, a real case of the AC filter arc fault is briefly described. Based on PSCAD, a simulation model is established for CB and dynamic arcing resistance. The combination of simulation results and strip inspections of on-site CB confirms the reasons for the arc fault and provides a basis for the operation and maintenance of AC filter in HVDC converter stations.

arc fault,AC filter,dynamic arc model,overvoltage,circuit breaker