Notch-Filter-Based Control Strategy to Extend Stability Limits of LCL-Filtered Grid-Connected Inverters

James N. Silva; Filipe A. da C. Bahia; Andre P. N. Tahim; Darlan Alexandria Fernandes; Fabiano Fragoso Costa

doi:10.18618/REP.e202615

Authors

James N. Silva Federal University of Bahia
Filipe A. da C. Bahia Federal University of Bahia
Andre P. N. Tahim Federal University of Bahia
Darlan Alexandria Fernandes Federal University of Paraíba
Fabiano Fragoso Costa Federal University of Bahia

DOI:

https://doi.org/10.18618/REP.e202615

Keywords:

Grid-connected inverter, LCL filter, Nyquist stability criterion, Active damping, Hardware-in-the-Loop

Abstract

The stable connection of energy sources to the grid via LCL-filtered inverters is often constrained by delays introduced by digital implementation and DPWM modulation. This paper proposes a novel notch-filter-based compensation strategy that explicitly mitigates such delays, extending the stability region of the current control system by increasing the critical frequency. In addition, a systematic methodology is introduced for tuning the active damping gain, demonstrating its direct influence on phase margin and robustness - an aspect not systematically addressed in previous studies. Unlike approaches based on auto-tuning or real-time resonance estimation, the proposed method imposes no additional computational burden while significantly expanding the stability limits. Analytical studies, frequency-domain analysis, and experimental validation using a hardware-in-the-loop (HIL) platform confirm that the proposed strategy extends the stable operating region, improves dynamic performance, and reduces harmonic distortion, representing a distinctive contribution to the control of LCL-filtered grid-connected inverters.

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Author Biographies

James N. Silva, Federal University of Bahia

holds a B.Sc. in Electrical Engineering from the Federal University of the São Francisco Valley (UNIVASF, 2014) and an M.Sc. from the Federal University of Bahia (UFBA, 2019), where he is currently pursuing a Ph.D. His research focuses on the control and stability of grid-connected converters, particularly methods to expand the stability region of LCL inverters.

Filipe A. da C. Bahia, Federal University of Bahia

holds a Bachelor’s degree in Electrical Engineering (2013) from the Federal University of Paraíba (UFPB). He earned his Master’s (2015) and Doctorate (2019) degrees in Electrical Engineering from the Federal University of Campina Grande (UFCG). He is currently an Adjunct Professor at the Department of Electrical and Computer Engineering (DEEC) at the Federal University of Bahia (UFBA). His research interests include power electronic converters, renewable energy generation systems, energy storage systems, electric machine drive systems, and pulse-width modulation (PWM) strategies.

Andre P. N. Tahim, Federal University of Bahia

holds a Bachelor’s degree in Electrical Engineering from the Federal University of Bahia (2004). He earned his Master’s degree in Electrical Engineering and Doctorate in Automation and Systems Engineering from the Federal University of Santa Catarina (2009 and 2015, respectively). Since 2015, he has been a faculty member of the Electrical Engineering Department at the Federal University of Bahia (Brazil). His current research interests include modeling and control of energy conversion systems, dynamic systems analysis, DC distribution systems, and power electronics for renewable energy sources.

Darlan Alexandria Fernandes, Federal University of Paraíba

received the B.S. degree in electrical engineering from the Federal University of Paraiba, Brazil, in 2002, and the M.S. and Ph.D. degrees in electrical engineering from the Federal University of Campina Grande, Brazil, in 2004 and 2008, respectively. He was a Visiting Scholar at the Center for Power Electronics Systems (CPES) at the Virginia Polytechnic Institute and State University (Virginia Tech), Blacksburg, United States, from 2018 to 2019. From 2007 to 2011, he was a Professor with the Industry Department in the Federal Center of Technological Education of Rio Grande do Norte. He is currently an Associate Professor with the Department of Electrical Engineering, Federal University of Paraiba, Brazil. His research interests are in the applications of power electronics in distribution systems, power quality, photovoltaic systems, and impedance-based control design techniques for static converters. He is a member of the Brazilian Power Electronics Association (SOBRAEP) and IEEE.

Fabiano Fragoso Costa , Federal University of Bahia

received his Bachelor’s, Master’s, and Doctorate degrees in Electrical Engineering from the University of São Paulo, Federal University of Paraíba, and Federal University of Campina Grande in 1997, 2001, and 2005, respectively. He is an Associate Professor in the Department of Electrical Engineering at the Federal University of Bahia. His research interests include the stability and modeling of power converters. He is a full member of the Brazilian Power Electronics Society (SOBRAEP) and a Senior Member of IEEE.

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