Predictive control of a modular multilevel converter for a back-to-back HVDC system

Jiangchao Qin, Maryam Saeedifard

Research output: Contribution to journalArticle

292 Scopus citations

Abstract

The modular multilevel converter (MMC) is one of the most potential converter topologies for high-power/voltage systems, specifically for high-voltage direct current (HVDC). One of the main technical challenges of an MMC is to eliminate/minimize the circulating currents of converter arms while the capacitor voltages are maintained balanced. This paper proposes a model predictive control (MPC) strategy that takes the advantage of a cost function minimization technique to eliminate the circulating currents and carry out the voltage balancing task of an MMC-based back-to-back HVDC system. A discrete-time mathematical model of the system is derived and a predictive model corresponding to the discrete-time model is developed. The predictive model is used to select the best switching states of each MMC unit based on evaluation and minimization a defined cost function associated with the control objectives of MMC units and the overall HVDC system. The proposed predictive control strategy: 1) enables control of real and reactive power of the HVDC system; 2) achieves capacitor voltage balancing of the MMC units; and 3) mitigates the circulating currents of the MMC units. Performance of the proposed MPC-based strategy for a five-level back-to-back MMC-HVDC is evaluated based on time-domain simulation studies in the PSCAD/EMTDC software environment. The reported study results demonstrate a satisfactory response of the MMC-HVDC station operating based on the proposed MPC strategy, under various conditions.

Original languageEnglish (US)
Article number6192340
Pages (from-to)1538-1547
Number of pages10
JournalIEEE Transactions on Power Delivery
Volume27
Issue number3
DOIs
StatePublished - May 8 2012
Externally publishedYes

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Keywords

  • Modular multilevel converter (MMC)
  • capacitor voltage balancing
  • circulating current control
  • high-voltage direct-current (HVDC) transmission
  • predictive control

ASJC Scopus subject areas

  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering

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