నైరూప్య

Multilevel Converter for Immunity in VSC HVDC Transmission

S S S BBHARAT, D.SESHI REDDY

Recent advances in technology have realized the diode clamped topology to have a considerable reduction in switching losses and the ability to control the harmonic content. Control methods based on selective harmonic elimination pulse-width modulation (SHE-PWM) techniques offer the lowest possible number of switching transitions. This feature also results in the lowest possible level of converter switching losses. For this reason, they are very attractive techniques for the voltage-source-converter-(VSC) based high-voltage dc (HVDC) power transmission systems. The paper discusses optimized modulation patterns which offer controlled harmonic immunity between the ac and dc side. The application focuses on the conventional two-level converter when its dc-link voltage contains a mix of low-frequency harmonic components. Simulation and experimental results are presented to confirm the validity of the proposed switching patterns. Finally a seven level Multilevel converter topology is applied for this application