A DC Chopper Topology to Mitigate Commutation Failure of Line Commutated Converter Based High Voltage Direct Current Transmission

To reduce the probability of commutation failure (CF) of a line commutated converter based high-voltage direct current (LCC-HVDC) transmission, a DC chopper topology composed of power consumption sub-modules based on thyristor full-bridge module (TFB-PCSM) is proposed. Firstly, the mechanism of the proposed topology to mitigate CF is analyzed, and the working modes of TFB-PCSM in different operation states are introduced. Secondly, the coordinated control strategy between the proposed DC chopper and LCC-HVDC is designed, and the voltage-current stresses of the TFB-PCSMs are investigated. Finally, the ability to mitigate the CF issues and the fault recovery performance of LCC-HVDC system are studied in PSCAD/EMTDC. The results show that the probability of CF of LCC-HVDC is significantly reduced, and the performances of fault recovery are effectively improved by the proposed DC chopper.