The most effective approach to suppressing the first commutation failure (CF) of the LCC-HVDC link at fault inception is to advance firings of the inverter

and the commutation failure prevention (CFPREV) control is the most commonly used method in practical engineering. However

it is discovered in this study that there exist a few serious defects in its original scheme

and thus targeted vital corrections were made. Furthermore

an interesting phenomenon termed the plateau effect

which states that an excessive advancement of firings will contrarily and inevitably lead to more commutation failures

is also revealed and analyzed. It turns out that the inherent commutation dents of the Graetz bridge should be primarily responsible

which bridges the knowledge gap and further enhances the cognition of the limitation of CFPREV control

and it may also be conducive to the design of related control parameters. Simulation results then validate the necessity of these presented corrections and confirm the existence of the plateau effect.