Analysis of commutation failure propagation characteristics and influence factor of multi-infeed LCC-HVDC system

The multi-infeed DC system can effectively transmit power and ensure the flexibility of the system’s operation mode, but the strong coupling among the converter stations makes the analysis of the commutation failure (CF) problem complicated. To this end, this paper firstly studies the propagation characteristics of CF among multiple stations, and the influence of the coupling impedances among these stations and the fault location on the CF. Then a method based on the decoupling idea is used to change the CF analysis problem of a multi-infeed DC system into that of the weakest single-infeed system. Finally, using the simulation analysis, the influence of fault type/wiring mode on CF is analyzed considering the relationship between the extinction angle, i.e., the CF criterion, and the influence of various variables on this factor is studied.