Implementation of a 84-pulse voltage-source converter for special applications

This study presents the experimental results on the implementation of a 84-pulse voltage-source converter (VSC), assembled by combining a 12-pulse VSC in conjunction with an asymmetric single-phase seven-level converter. The phase-locked-loop strategy used ensures the determination of the system´s frequency and phase-angle of the fundamental positive sequence voltage of the controlled AC bus. The injection transformer added to the configuration allows the total harmonic distortion on the VSC´s output to be compliant with the IEEE STD 519-1992, for its use in special applications. The amount of switches and capacitors employed on the implementation, and the wide turn ratios allowed to the re-injection transformer, constitute an attractive array in terms of cost and reduced output voltage distortion and notching.