Sending End AC Faults can Cause Commutation Failure in LCC-HVDC Inverters

In conventional wisdom, commutation failure (CF) in LCC-HVDC inverters has always been reported to be caused by receiving end ac faults. However, this letter presents a new CF phenomenon that sending end ac faults can also cause CF in inverters during the post-fault recovery process. Moreover, the underlying mechanism of the new CF phenomenon is revealed. This is achieved by analyzing the impact of the current error control (CEC) on CF during the post-fault recovery process, using the quasi-steady-state analytical model of inverters. It is concluded that the adverse activation of the CEC in inverters is the inherent reason of the new CF phenomenon.