Selective Harmonic Elimination modulation for Medium Voltage Modular Multilevel Converter

The use of medium voltage converter in applications of voltage and grid supporting is increasing. To improve the power quality from the point of view of total harmonic distortion, this paper proposes the use of a Modular Multilevel Converter (MMC) with Selective Harmonic Pulse-Width Modulation (SHE-PWM). SHE-PWM allows control the harmonics generated at the output while it provides reduced switching losses. The main drawback of this modulation technique is to solve the equation system required to obtain the switching angles that minimize the generated harmonics. This paper studies the SHE-PWM for a six-level MMC where fifteen harmonics are minimized. The switching angles required to minimize the harmonics are obtained using Genetic Algorithms. Simulation and experimental results are presented to verify the proposed scheme for the MMC.