In the process of high voltage direct current transmission system successive commutation failures

even though no out-of-step oscillation has occurred

electrical quantities on AC lines nearby inverter station will still vary cyclically

which may lead to maloperation of the out-of-step splitting device. By taking the out-of-step splitting criterion based on the phase angle between voltage and current phasor as an example

the effect of successive commutation failures on the splitting criterion is studied. An AC/DC hybrid system simulation model is established on PSCAD/EMTDC

the electrical quantities variation characteristics on AC/DC system during successive commutation failures are analyzed and periodic variation features of inverter bus voltage are summarized. Then

the phase angle trajectories on AC lines during the process of successive commutation failures are calculated for time-domain analysis

the influence of the corresponding electrical quantities on phase angle trajectories features are analyzed and the mechanism of effect of successive commutation failures on the out-of-step splitting criterion is revealed. A numerical example is given to demonstrate the validity of the theoretical analysis. This work is supported by State Grid Corporation of China.