A novel optimized pulse pattern for modular multilevel converters in high power applications

The main objective of this work is to propose a modulation strategy focused in minimization of total harmonic distortion (THD) for high power modular multilevel converters. A mathematical approach is given in order to write the Fourier series for a general N levels stepped voltage waveform sythesized by the converter. The study shows how an optimization system using equations for each harmonic component can be drawn in order to minimize THD. A ±200 kV DC, 400 MW inverter based on MMC topology is simulated on PSIM software using the optimized parameters. Three setting cases are presented in order to validade the study. Simulation shows that the proposed modulation can fit total harmonic distortion and individual frequency components into predetermined standards.