A Multilevel DC to Three-Phase AC Architecture for Photovoltaic Power Plants

Prasanta K. Achanta, Brian B. Johnson, Gab Su Seo, Dragan Maksimovic

Research output: Contribution to journalArticlepeer-review

42 Scopus Citations

Abstract

This paper presents a photovoltaic (PV) inverter architecture composed of stackable dc to three-phase ac converter blocks. Several such blocks, each containing a converter power stage and controls, are connected in series on their ac sides to obtain transformerless medium-voltage ac interfaces for PV power plants. The series-connected structure is made possible by a quadruple active bridge DC-DC converter that provides isolation between the PV input and each of the three ac-side phases within each block. Furthermore, since incoming PV power is transferred as constant balanced three-phase ac power, instantaneous input-output power balance bypasses the need for bulk energy storage. To streamline implementation and maximize system scalability and resilience, decentralized block-level controllers accomplish dc-link voltage regulation, maximum power point tracking, and ac-side power sharing without centralized means. The proposed architecture is validated by simulations of a PV string to medium-voltage ac system consisting of six blocks and on a proof-of-concept hardware prototype that consists of three cascaded converter blocks.

Original languageAmerican English
Article number8501588
Pages (from-to)181-190
Number of pages10
JournalIEEE Transactions on Energy Conversion
Volume34
Issue number1
DOIs
StatePublished - Mar 2019

Bibliographical note

Publisher Copyright:
© 1986-2012 IEEE.

NREL Publication Number

  • NREL/JA-5D00-72319

Keywords

  • DC-AC power converters
  • decentralized control
  • multilevel converters

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