@inproceedings{29938,
  abstract     = {{Modular solid-state transformers (SSTs) are a promising technology in converting power from a 10kV three-phase medium voltage to a lower DC-voltage in the range of 100…400V to provide pure DC power to applications such as electrolyzers for hydrogen generation, data centers with a DC power distribution and DC micro grids. Modular SSTs which can be interpreted as modular multilevel converters with an isolated DC-DC output stage per module, are designed with redundant modules to increase reliability. Usually, each of the three arms operates independently, and therefore, only a fixed number of faulty modules can be compensated in each arm, even if all modules are operational in the remaining two arms. With the proposed zero-sequence voltage injection, up to 100% more faulty modules can be compensated in an arm by employing the same hardware. In addition, module power imbalances are nearly eliminated by utilizing a fundamental frequency zero-sequence voltage. A dominant 3rd harmonic zero-sequence voltage injection in combination with the 5th, 7th and several higher order harmonics with adaptive (small) amplitudes minimize the required arm voltages at steady-state. For nominal operation or symmetrical faults, the proposed technique is equivalent to the well known Min-Max voltage injection, which already reduces the peak arm voltage by 13.4% compared to a constant star point potential. A statistical analysis proves, that the expected number of tolerable faulty modules of the 1MW SST increases by 12% without the need for additional hardware.}},
  author       = {{Unruh, Roland and Lange, Jarren and Schafmeister, Frank and Böcker, Joachim}},
  booktitle    = {{23rd European Conference on Power Electronics and Applications (EPE'21 ECCE Europe)}},
  isbn         = {{978-9-0758-1537-5}},
  keywords     = {{Solid-State Transformer, Zero sequence voltage, Fault handling strategy, Power balance control technique, Three-phase system}},
  location     = {{Ghent, Belgium}},
  publisher    = {{IEEE}},
  title        = {{{Adaptive Zero-Sequence Voltage Injection for Modular Solid-State Transformer to Compensate for Asymmetrical Fault Conditions}}},
  doi          = {{https://doi.org/10.23919/EPE21ECCEEurope50061.2021.9570542}},
  year         = {{2021}},
}