Selecting frequency and parameters of DC-fault tolerant Non-Isolated high power MMC DC/DC Converter

Aliakbar Jamshidi Far* (Corresponding Author), Dragan Jovcic, A. Nami, Y. Okazaki

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)
8 Downloads (Pure)


This paper studies MMC-based non-isolated DC/DC converter for DC transmission grids. The key design parameters including operating frequency and size of passive components are evaluated with the aim of ensuring DC fault tolerance and minimizing losses and size. An analytical model is used to perform parametric studies while detailed non-linear model is used for verification. The case study on 600MW, 320kV/250kV system reveals the narrow range of optimal cell capacitance and arm inductance while lower-side arms require substantially larger capacitors. With the targeted losses of 1.5%, and voltage ripple of ±5%, it is recommended to use around 150Hz operating frequency. For the offshore applications, higher frequency enables significantly smaller size with some increase in losses. The line inductor on the lowvoltage side should be much larger than the arm inductor and plays a key role in the dc fault responses.
Original languageEnglish
Article number106896
Number of pages9
JournalElectric Power Systems Research
Early online date21 Oct 2020
Publication statusPublished - 1 Feb 2021


  • HVDC
  • High power DC-DC converter
  • DC Grids


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