Smart Transformer-Fed Variable Frequency Distribution Grid

Zhi Xiang Zou, Giovanni De Carne, Giampaolo Buticchi, Marco Liserre

Research output: Journal PublicationArticlepeer-review

35 Citations (Scopus)


The smart transformer (ST), a solid-state transformer with control and communication functionalities, that interfaces medium voltage (MV) and low voltage (LV) grids, enables the control of the frequency in the LV grid independently from the MV one. In a ST-fed distribution grid, the ST can interact with the droop controllers of local generators and loads frequency characteristic to control the LV power demand. However, most of the existing controllers for power converters cannot guarantee good harmonic control under variable frequency condition. To address this issue, a frequency-adaptive control scheme based on the fractional-order repetitive control and the frequency-adaptive phase-locked loop are proposed in this paper. The proposed scheme provides fast online parameter tuning capability in order to be highly adaptive to variable frequencies, and it can be easily implemented in the power converters controllers of a ST-fed distribution grid. Moreover, the stability analysis of the frequency-adaptive system considering the effect of synchronization has been investigated in this paper. Simulation and experiments have been carried out to verify the effectiveness of the proposed scheme as well as the considered scenarios.

Original languageEnglish
Article number7812775
Pages (from-to)749-759
Number of pages11
JournalIEEE Transactions on Industrial Electronics
Issue number1
Publication statusPublished - Jan 2018
Externally publishedYes


  • Distribution grid
  • Frequency control
  • Solid-state transformer
  • Stability
  • Synchronization

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Electrical and Electronic Engineering


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