Analysis of Transformer Magnetizing Reactance Using Describing Function in Direct Power Control of Back-to-Back Modular Multilevel Converter with Advanced Grid Support

Authors

Vikram Roy Chowdhury, Ramanathan Thiagarajan, Akanksha Singh, Barry Mather, Dihao Ma, Ke Wang, Sihun Song, Andrea Rueetschi, Jin Wang, Karl Schoder, Kurtis Buck, Peter Gotseff, Brian Fedish

Abstract

This article presents a port-controlled Hamiltonian (PCH)-based direct power control (DPC) architecture for a back-to-back (B2B) modular multilevel converter (MMC) system connecting two ac sources at different frequencies. The system features advanced grid support functionalities based on IEEE 1547-2018, implemented on the inverter side. The rectifier-side controller ensures reference following for active and/or reactive powers and maintains the commanded dc bus voltage. The inverter-side controller ensures power command following for active and reactive powers. The proposed control architecture is designed to suppress second-harmonic oscillations in powers during unbalanced grid voltage sags by dynamically adjusting the currents on each ac side. This also ensures effective elimination of any second-harmonic oscillations in the equivalent dc bus voltage. Validation is performed on an OPAL-RT Technologies Inc. (OPAL-RT) real-time platform with case studies on unbalanced and balanced sags, demonstrating the controller’s effectiveness during real-time implementation. A reduced-scale laboratory prototype further verifies these case studies, with experimental results for balanced sags due to grid simulator limitations. The results confirm the robustness and efficiency of the proposed control strategy in ensuring stable and reliable operation under various grid conditions.

Citation

• Journal: IEEE Journal of Emerging and Selected Topics in Power Electronics
• Year: 2025
• Volume: 13
• Issue: 4
• Pages: 5022–5047
• Publisher: Institute of Electrical and Electronics Engineers (IEEE)
• DOI: 10.1109/jestpe.2025.3568852

BibTeX

@article{Chowdhury_2025,
  title={{Analysis of Transformer Magnetizing Reactance Using Describing Function in Direct Power Control of Back-to-Back Modular Multilevel Converter with Advanced Grid Support}},
  volume={13},
  ISSN={2168-6785},
  DOI={10.1109/jestpe.2025.3568852},
  number={4},
  journal={IEEE Journal of Emerging and Selected Topics in Power Electronics},
  publisher={Institute of Electrical and Electronics Engineers (IEEE)},
  author={Chowdhury, Vikram Roy and Thiagarajan, Ramanathan and Singh, Akanksha and Mather, Barry and Ma, Dihao and Wang, Ke and Song, Sihun and Rueetschi, Andrea and Wang, Jin and Schoder, Karl and Buck, Kurtis and Gotseff, Peter and Fedish, Brian},
  year={2025},
  pages={5022--5047}
}

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