Modulation techniques applied to medium voltage modular multilevel converters for renewable energy integration: A review

• Published in: Electric power systems research Vol. 155; pp. 21 - 39
• Main Authors: Antonio Ferreira, Abel, Gomis Bellmunt, Oriol, Collados Rodríguez, Carlos
• Format: Journal Article Publication
• Language: English
• Published: Amsterdam Elsevier B.V 01.02.2018; Elsevier Science Ltd
• Subjects: Alternative energy; Converters; Convertidors de corrent elèctric; Distribució; Electric current converters; Electric potential; Electric power distribution; Energia elèctrica; Energies; Energy distribution; Integration; Losses; MMC; Modulation; Multilevel; Power quality; Pulse width modulation (PWM); Studies; Àrees temàtiques de la UPC; MMC; Losses; Pulse width modulation (PWM); Power quality
• ISSN: 0378-7796; 1873-2046
• DOI: 10.1016/j.epsr.2017.08.015

•A comprehensive survey modular multilevel converter voltage modulation is presented.•Key points discussion of zero sequence signals injection into arm voltage modulation.•A medium-voltage scenario is embraced.•Modulation impact on MMC efficiency, power quality and capacitor's ripple is studied. Modular multilevel converters (MMC) inherent features are gaining more attention for dc voltage transmission systems. One of the main research paths regarding the converter performance deals with its voltage modulation. Specifically, for medium voltage applications with relatively small number of submodules, the voltage modulation techniques impact on the MMC performance needs to be studied. This work provides an extensive review of the carrier-based pulse with modulation (CB-PWM) techniques proposed to be applied on previous multilevel inverter versions. The CB-PWM methods were adapted to be compatible with an additional cell ranking and selection algorithm to ensure equal energy distribution on the arm cells. The state-of-the-art of zero sequence signals (ZSS) applied on three-phase inverters is also reviewed. The alliance between the ZSS with the CB-PWM, as well as the nearest level modulation (NLM), has an important impact on the MMC harmonic content, efficiency and voltage ripple of its cells capacitors. A 15MW 28-cell-based MMC is used to investigate each particular combination between the modulation method and the common mode ZSS.