An Improved Voltage Prediction Criterion of Commutation Failure in HVDC

Aiming at the problem of commutation failure often occurring in high voltage direct current (HVDC), the shortcoming of the existing voltage prediction criterion is analyzed based on the mechanism of commutation failure. By building the HVDC model and studying the transient process of HVDC after three-phase AC fault, a time-series segmentation method is proposed to calculate the post-fault transient DC current based on the post-fault AC voltage. Based on the method, an improved voltage prediction criterion of commutation failure simultaneously considering the DC current dynamics and the pre-fault operating state of HVDC is proposed, which can improve the accuracy of commutation failure prediction significantly. The feasibility and validity of the proposed current calculation method and improved voltage prediction criterion are verified by the comparison with the simulation results.