Forced commutation circuit for HVDC transmission

This paper studies a novel converter configuration for HVDC systems. The converter is based on a resonant circuit and the forced commutation principle, which enables thyristor commutation to be independent of the AC voltage. The theoretical analysis elaborates the methods for calculating the converter parameters. PSCAD simulation with 200 μs thyristor extinction time indicates that the converter is immune to commutation failure even under most severe faults. The harmonic pollution generated by the new converter is somewhat increased but comparable to the conventional inverters. The simulation further proves that the converter is capable of operating with a significant reactive power export.