One of the reasons for commutation failure of the HVDC system is that the phase-locked loop(PLL) can not lock the AC voltage phase in the transient process, which leads to the deviation between the command trigger angle given by the control system and the measured trigger angle. Moreover, the mechanism of commutation failure caused by transient error of phase-locked loop is analyzed intuitively. In this paper, a feedback compensation link is designed to reduce the adverse effect of the PLL transient deviation on the control system on the basis of indirect measurement of the transient error of phase-locked loop. On the basis of the PSCAD/EMTDC platform and considering the minimum arc extinguishing time in the simulation model, the compensation link proposed in this paper is verified to suppress the subsequent commutation failure. The calculation example shows that the compensation link proposed in this paper has obvious ability reduce to the probability of commutation failure. The compensation link proposed in this paper is reliable and effective, and has great practical significance in engineering.
