Extinction angle predictive control strategy for commutation failure mitigation in HVDC systems considering voltage distortion

Abstract

In this study, an extinction angle predictive (EAP) control strategy is proposed to mitigate commutation failure (CF) in high voltage direct current (HVDC) systems. The proposed strategy works effectively during both AC system faults and commutation voltage distortions. At first, an index is put forward to evaluate the prospective commutation area drop and quantify the upcoming commutation stress considering the commutation mechanism. Then, the extinction angle is predicted based on the detected commutation area drop incident. Further, the predicted extinction angle is introduced into the HVDC inverter control to design the EAP control strategy, ensuring that the CF can be prevented due to a sufficient commutation margin. The advantage of the proposed strategy is that it evaluates the upcoming commutation stress based on the transient commutation voltage waveform. Thus, a better sensitivity for commutation voltage distortion can be ensured. The proposed strategy is simulated in the PSCAD/EMTDC platform and the results are compared with that of the conventional schemes, verifying the performance of the proposed strategy in mitigating the CF during AC faults and voltage distortion.