Seamless Transition Control Method of Grid-Connected Inverters Under Unbalanced Voltage Conditions

The transition between Grid-Forming (GFM) and Grid-Following (GFL) modes is critical for adapting to changing power grid conditions. These transitions are essential for protecting grid-connected inverter systems and ensuring reliable power supply. However, abrupt changes during the transition proces...

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Main Authors: Hyun J. Kim, Ho J. Lee, Min S. Kim, Eun S. Lee
Format: Article
Language:English
Published: IEEE 2025-01-01
Series:IEEE Open Journal of Power Electronics
Subjects:
Online Access:https://ieeexplore.ieee.org/document/11088226/
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author Hyun J. Kim
Ho J. Lee
Min S. Kim
Eun S. Lee
author_facet Hyun J. Kim
Ho J. Lee
Min S. Kim
Eun S. Lee
author_sort Hyun J. Kim
collection DOAJ
description The transition between Grid-Forming (GFM) and Grid-Following (GFL) modes is critical for adapting to changing power grid conditions. These transitions are essential for protecting grid-connected inverter systems and ensuring reliable power supply. However, abrupt changes during the transition process can disrupt both internal and external control loops, potentially causing voltage and current distortions that jeopardize system stability. This challenge is particularly significant when transitioning between GFL and GFM modes under unbalanced load conditions. To address this, this paper proposes a seamless control strategy that enables dynamic and stable transitions between GFL and GFM modes, even under unbalanced three-phase voltage conditions. The proposed approach is based on three key criteria that ensure stability during transitions across various grid scenarios. Additionally, a simple yet effective method for extracting positive and negative sequence components using digital filters is introduced to facilitate the seamless control implementation. The effectiveness of the control strategy is validated through extensive simulations and experiments using a 300 kVA hardware setup. The results demonstrate successful seamless transitions under unbalanced conditions while maintaining a total harmonic distortion (THD) of less than 3%. This method significantly enhances the stability and reliability of power systems, especially in environments characterized by varying grid strengths.
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spelling doaj-art-1de4b2ae29d5404baaf272925e77c5d82025-08-20T03:39:36ZengIEEEIEEE Open Journal of Power Electronics2644-13142025-01-0161333134610.1109/OJPEL.2025.359164011088226Seamless Transition Control Method of Grid-Connected Inverters Under Unbalanced Voltage ConditionsHyun J. Kim0https://orcid.org/0009-0002-2368-3919Ho J. Lee1https://orcid.org/0009-0000-0895-0500Min S. Kim2https://orcid.org/0000-0002-2928-0005Eun S. Lee3https://orcid.org/0000-0002-4887-8272ZetaElec Company, Ltd., Ansan, South KoreaSchool of Electrical Engineering, Hanyang University ERICA Campus, Ansan, South KoreaSchool of Electrical Engineering, Hanyang University ERICA Campus, Ansan, South KoreaSchool of Electrical Engineering, Hanyang University ERICA Campus, Ansan, South KoreaThe transition between Grid-Forming (GFM) and Grid-Following (GFL) modes is critical for adapting to changing power grid conditions. These transitions are essential for protecting grid-connected inverter systems and ensuring reliable power supply. However, abrupt changes during the transition process can disrupt both internal and external control loops, potentially causing voltage and current distortions that jeopardize system stability. This challenge is particularly significant when transitioning between GFL and GFM modes under unbalanced load conditions. To address this, this paper proposes a seamless control strategy that enables dynamic and stable transitions between GFL and GFM modes, even under unbalanced three-phase voltage conditions. The proposed approach is based on three key criteria that ensure stability during transitions across various grid scenarios. Additionally, a simple yet effective method for extracting positive and negative sequence components using digital filters is introduced to facilitate the seamless control implementation. The effectiveness of the control strategy is validated through extensive simulations and experiments using a 300 kVA hardware setup. The results demonstrate successful seamless transitions under unbalanced conditions while maintaining a total harmonic distortion (THD) of less than 3%. This method significantly enhances the stability and reliability of power systems, especially in environments characterized by varying grid strengths.https://ieeexplore.ieee.org/document/11088226/Grid-forming (GFM)grid-following (GFL)seamless transition controlvoltage unbalancedbalancing controlpositive & negative sequence
spellingShingle Hyun J. Kim
Ho J. Lee
Min S. Kim
Eun S. Lee
Seamless Transition Control Method of Grid-Connected Inverters Under Unbalanced Voltage Conditions
IEEE Open Journal of Power Electronics
Grid-forming (GFM)
grid-following (GFL)
seamless transition control
voltage unbalanced
balancing control
positive & negative sequence
title Seamless Transition Control Method of Grid-Connected Inverters Under Unbalanced Voltage Conditions
title_full Seamless Transition Control Method of Grid-Connected Inverters Under Unbalanced Voltage Conditions
title_fullStr Seamless Transition Control Method of Grid-Connected Inverters Under Unbalanced Voltage Conditions
title_full_unstemmed Seamless Transition Control Method of Grid-Connected Inverters Under Unbalanced Voltage Conditions
title_short Seamless Transition Control Method of Grid-Connected Inverters Under Unbalanced Voltage Conditions
title_sort seamless transition control method of grid connected inverters under unbalanced voltage conditions
topic Grid-forming (GFM)
grid-following (GFL)
seamless transition control
voltage unbalanced
balancing control
positive & negative sequence
url https://ieeexplore.ieee.org/document/11088226/
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AT hojlee seamlesstransitioncontrolmethodofgridconnectedinvertersunderunbalancedvoltageconditions
AT minskim seamlesstransitioncontrolmethodofgridconnectedinvertersunderunbalancedvoltageconditions
AT eunslee seamlesstransitioncontrolmethodofgridconnectedinvertersunderunbalancedvoltageconditions