Analysis and Mitigation of Transient Overvoltage and Voltage Imbalance in Submodule Capacitors for MMC-Based Grid Emulators

The modular multilevel converter (MMC) has recently emerged as a promising candidate for medium-voltage megawatt grid emulators (GEs). However, when emulating grid faults, the MMC-based GE may encounter the transient overvoltage and voltage imbalance issues in its submodule (SM) capacitors. Followin...

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Bibliographic Details
Published inIEEE journal of emerging and selected topics in power electronics p. 1
Main Authors Li, Zejie, Zhao, Fangzhou, Munk-Nielsen, Stig, Geske, Martin, Wang, Xiongfei
Format Journal Article
LanguageEnglish
Published IEEE 2024
Subjects
Capacitors
Fault currents
Germanium
Grid emulator
grid faults
modular multilevel converter
Modulation
Transient analysis
transient overvoltage
Voltage control
Voltage fluctuations
voltage imbalance
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Summary:The modular multilevel converter (MMC) has recently emerged as a promising candidate for medium-voltage megawatt grid emulators (GEs). However, when emulating grid faults, the MMC-based GE may encounter the transient overvoltage and voltage imbalance issues in its submodule (SM) capacitors. Following the mechanism analysis of these issues, this paper proposes an enhanced SM capacitor energy balancing approach. Differing from conventional methods, this approach effectively mitigates these issues even when emulating faults with residual voltages close to zero, ensuring the reliable operation of SM capacitors within 70%~110% of the rated voltage. Lastly, the effectiveness of the enhanced method is confirmed by the controller hardware-in-the-loop test.
ISSN:2168-6777
2168-6785
DOI:10.1109/JESTPE.2024.3387078