Low-Voltage-Ride-Through Control of a Modular Multilevel Single-Delta Bridge-Cell (SDBC) Inverter for Utility-Scale Photovoltaic Systems

Paul Sochor, Nadia Mei Lin Tan, Hirofumi Akagi

Research output: Contribution to journalArticle

3 Citations (Scopus)


This paper presents theoretical and experimental discussions on low-voltage-ride-through operation of a modular multilevel single-delta bridge-cell (SDBC) inverter intended for utility-scale photovoltaic (PV) systems. Modern grid codes require grid-tied inverters to provide dynamic grid support during grid-fault events by injecting reactive current. This paper discusses decoupled positive- and negative-sequence reactive-current control, focusing on asymmetric voltage sags with imbalanced magnitude and phase relationships. The main objective is to present a feedforward control method based on calculation of the zero-sequence current required for achieving power balance during normal and grid-fault conditions. Moreover, this paper demonstrates a practical method that minimizes overcurrent stress in the three inverter clusters by adjusting active power drawn from PV arrays. Experimental results on a three-phase 12.6-kVA system prove that the SDBC inverter is capable of seamlessly operating through asymmetric voltage sags.

Original languageEnglish
Article number8378265
Pages (from-to)4739-4751
Number of pages13
JournalIEEE Transactions on Industry Applications
Issue number5
Publication statusPublished - 01 Sep 2018


All Science Journal Classification (ASJC) codes

  • Control and Systems Engineering
  • Industrial and Manufacturing Engineering
  • Electrical and Electronic Engineering

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