A new high-pulse voltage-sourced converter for HVDC transmission

The proposed converter is based on the reinjection of a series of dc voltage pulses, at a frequency multiple of the fundamental, that shape the output voltage waveforms into a multilevel scheme. The reinjection ratio and frequency are chosen to convert the standard 12-pulse into 36-pulse configuration without the assistance of filters or PWM. Thus, the switching losses are greatly reduced. The harmonic current injection can be kept within present standards by an appropriate choice of the interface transformer leakage reactance.