Optimal Common-Mode Voltage for Grid-Tied Photovoltaic Cascaded H-Bridge Inverters Under Severe Power Imbalances

Felipe Calderon Rivera, Alejandro Angulo, Pablo Acuna, Andres Mora

Research output: Contribution to journalArticleScientificpeer-review

Abstract

This article deals with the control problem of injecting balanced grid currents from a grid-tied photovoltaic cascaded H-bridge (CHB) inverter under severe interphase power imbalances. Existing solutions are hindered by the additional harmonic content required at the inverter output voltages. Therefore, a mathematical formulation for which the solution has minimal harmonic content is proposed. The proposed solution, optimal common-mode voltage (OCMV), has an analytical form that allows deducing and analyzing the CHB operating area. The real-time implementation of the OCMV requires solving a nonlinear two-variables system; thus, an iterative and distributed algorithm is designed. By doing so, the proposed OCMV can be fully formulated and implemented using a real-time control platform. The experimental validation was carried out in a scale-down 3 kW grid-tied seven-level CHB inverter governed by phase-shifted model predictive control. The laboratory results show that the proposed OCMV allows obtaining symmetrical grid currents while maintaining low-distorted inverter output voltages.

Original languageEnglish
Pages (from-to)1-11
Number of pages11
JournalIEEE Transactions on Industrial Electronics
DOIs
Publication statusE-pub ahead of print - 2023

Keywords

  • Cascaded H-bridge (CHB) inverter
  • Harmonic analysis
  • interphase power imbalance
  • Inverters
  • Mathematical models
  • optimal control
  • phase-shifted model predictive control (PS-MPC)
  • Power system harmonics
  • Real-time systems
  • Voltage
  • Voltage control
  • zero-sequence voltage (ZSV)

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