Component sizing and voltage balancing of MMC-based solid-state transformers under various AC-link excitation voltage waveforms

Lei Zhang, Jiangchao Qin, Qing Duan, Wanxing Sheng

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Scopus citations

Abstract

Modular multilevel converter (MMC) has been employed for solid state transformer (SST) applications. For the MMC-based SSTs, ac-link excitation voltage waveforms are multilevel and controllable for energizing medium-frequency transformers. Different multilevel ac-link voltage waveforms have different performance and specification requirements in design and control. In this paper, power transfer characteristics and capacitor voltage ripple are investigated for the MMC-SSTs under different ac-link excitation voltage waveforms, i.e., sinusoidal and generalized non-sinusoidal voltages. Based on the analysis, capacitance and inductance sizing method is developed and verified. To address voltage balancing issue of the MMC under medium-frequency operating conditions, various capacitor voltage balancing methods are evaluated and compared based on phase-shift modulation and nearest-level modulation methods. The study is conducted in the PSCAD/EMTDC software environment. The study results show that, for the same design specifications, different ac-link excitation voltage waveforms have different capacitance requirements, which can be used for optimization design of the MMC-SSTs.

Original languageEnglish (US)
Title of host publication34th Annual IEEE Applied Power Electronics Conference and Exposition, APEC 2019
PublisherInstitute of Electrical and Electronics Engineers Inc.
Pages371-375
Number of pages5
ISBN (Electronic)9781538683309
DOIs
StatePublished - May 24 2019
Event34th Annual IEEE Applied Power Electronics Conference and Exposition, APEC 2019 - Anaheim, United States
Duration: Mar 17 2019Mar 21 2019

Publication series

NameConference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC
Volume2019-March

Conference

Conference34th Annual IEEE Applied Power Electronics Conference and Exposition, APEC 2019
CountryUnited States
CityAnaheim
Period3/17/193/21/19

Keywords

  • Capacitor voltage ripple
  • Modular multilevel converter (MMC)
  • Solid state transformer (SST)

ASJC Scopus subject areas

  • Electrical and Electronic Engineering

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