On the Ground Potentials and Grounding Circuits of Transformerless Grid-Connected Multilevel Power Electronic Converters

Saleh Saleh, Ahmed Al-Durra, Razzaqul Ahshan

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

Transformerless grid-connected power electronic converters (PECs) are used in photovoltaic systems, motor drives, and solid-state power transformers. In these applications, transformerless grid-connected multilevel PECs can reduce harmonic distortions, increase power, and voltage ratings. This article aims to develop models for the ground potentials in these PECs, and to design grounding circuits for them. The models for ground potentials are developed using the common-mode voltages across each leg of the multilevel PEC. Grounding circuits for transformerless grid-connected multilevel PECs are designed using frequency selective circuits to limit ground potentials, and block ground currents from flowing through grounding of the host grid. The developed models, and grounding circuits are evaluated for transformerless grid connected, diode clamped, flying capacitor, and cascaded $H$-bridge multilevel PECs under different operating conditions. Test results demonstrate the significant advantages of the frequency-selective grounding for transformerless grid-connected PECs. Observed advantages include reduced harmonic distortion, minimized ground potentials, and improved efficiency.

Original languageBritish English
Article number9181476
Pages (from-to)6286-6297
Number of pages12
JournalIEEE Transactions on Industry Applications
Volume56
Issue number6
DOIs
StatePublished - 1 Nov 2020

Keywords

  • And level-shifted pulsewidth modulation
  • grid-connected power electronic converters
  • harmonic distortion
  • power system grounding

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