Accurate Impedance Modeling and Control Strategy for Improving the Stability of DC System in Multiterminal MMC-Based DC Grid

  • Zhenyu Li
  • , Zhang Wang
  • , Yue Wang
  • , Taiyuan Yin
  • , Nian Mei
  • , Bo Yue
  • , Wanjun Lei

Research output: Contribution to journalArticlepeer-review

98 Scopus citations

Abstract

This article proposes an accurate dc-side impedance modeling method of modular multilevel converter (MMC) and a control strategy for improving the stability of the dc system in MMC-based dc grid. First, the impedance modeling method based on harmonic linearization is adopted to establish the dc-side small-signal impedance model of MMC, which considers the internal multiharmonic coupling characteristics and the complete control system. Second, an equivalent model is established to analyze the frequency impedance characteristics of the dc ports in MMC-based dc grid, and the stability of dc ports is further analyzed based on the impedance-based stability criterion. Then, considering both the dynamic characteristics and stability of the dc system, a specific design method of controller parameter optimization and additional virtual damping controller is proposed. Based on MATLAB/Simulink, a detailed time-domain simulation model of MMC-based dc grid is established. The simulation results prove the accuracy of the proposed impedance modeling method and the validity of the proposed control strategy.

Original languageEnglish
Article number9007686
Pages (from-to)10026-10049
Number of pages24
JournalIEEE Transactions on Power Electronics
Volume35
Issue number10
DOIs
StatePublished - Oct 2020

Keywords

  • Frequency impedance characteristic
  • harmonic linearization
  • impedance model
  • modular multilevel converter (MMC)-based dc grid
  • virtual damping

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