Commutation failure prediction method based on characteristic of accumulated energy in inverter

Abstract

Abstract Concerning the difficulty in predicting commutation failure in HVDC transmission system, a commutation failure prediction method based on the energy accumulation characteristic of 12-pulse inverter is proposed. First, the operation characteristic of valve-side current in the commutation process is analyzed. And then, according to the characteristic of cross commutation between Y bridge and D bridge of 12-pulse inverter, the model of accumulated energy difference between commutation inductances is built. On this basis, considering the instantaneous values of real-time firing angle and valve-side current in the DC system, the commutation failure prediction criterion is constructed, which combined with the variation rate of valve-side current can predict commutation failure. Simulation tests in RTDS verify that, the proposed method can effectively predict commutation failure in HVDC system without phasor calculation. Besides, it is strongly immune to disturbance and fault resistance and unaffected by the type of AC system fault.