Power Transfer Stability Analysis of Grid Forming Converters-Seong-Jeon Lee ․ Joosik Kwak ․ Gyu-Sub Lee-Dept. of Electrical and Computer Engineering, Seoul National University (SNU), Seoul, Republic of Korea and Seoul National University Electric Power Research Institute (SEPRI),

 Power Transfer Stability Analysis of Grid Forming Converters SCR에 따른 그리드 포밍 인버터의 전력 전달 안정성 분석 Seong-Jeon Lee ․ Joosik Kwak ․ Gyu-Sub Lee 이성전* ․ 곽주식** ․ 이규섭†

 Abstract

 With the growth of renewable energy sources (RES) and energy storage systems (ESS), the number of distributed generators (DGs) integrated into power systems via voltage source converters (VSCs) has been increasing. VSCs are operated either in grid-following (GFL) or grid-forming (GFM) control modes. While the GFM mode offers the advantage of not requiring a phase-locked loop (PLL) for grid synchronization, it exhibits a stability issue when the grid impedance decreases. To analyze the stability concerns of GFM inverters, a PSCAD simulation-based study was conducted considering the short-circuit ratio (SCR) and the grid impedance X/R ratio (the ratio of inductive to resistive impedance). The results demonstrate that GFM inverters become more unstable as the SCR increases and the X/R ratio decreases. Key Words Grid forming converter, Short circuit ratio, Stability analysis, Voltage sourced converter, X/R Ratio † Corresponding Author : Dept. of Electrical and Computer Engineering, Seoul National University (SNU), Seoul, Republic of Korea and Seoul National University Electric Power Research Institute (SEPRI), Seoul, Republic of Korea. E-mail : lgs1106@snu.ac.kr https://orcid.org/0000-0002-6313-4685 * Dept. of Electrical and Computer Engineering, Seoul National University (SNU), Seoul, Republic of Korea. https://orcid.org/0009-0003-1996-001X ** Korea Electric Power Corporation Research Institute, Republic of Korea. Received : Oct. 30, 2024 Revised : Apr. 29, 2025 Accepted : Aug. 14, 2025 Copyright ⓒ The Korean Institute of Electrical Engineers This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. ISSN 1975-8359 [Print] / ISSN 2287-4364 [Online]

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Stability Analysis of Grid-Following and GridForming Converters Based on State-Space Modelling Xian Gao, Student Member, IEEE, Dao Zhou, Senior Member, IEEE, Amjad Anvari-Moghaddam, Senior Member, IEEE, and Frede Blaabjerg, Fellow, IEEE AAU Energy, Aalborg University, Aalborg, Denmark

 Stability Analysis of Grid-Following and GridForming Converters Based on State-Space Modelling

 Xian Gao, Student Member, IEEE, Dao Zhou, Senior Member, IEEE, Amjad Anvari-Moghaddam, Senior Member, IEEE, and Frede Blaabjerg, Fellow, IEEE AAU Energy, Aalborg University, Aalborg, Denmark

 Abstract - This paper conducts a comprehensive analysis and comparison of the control loops of the grid-following and grid-forming voltage source converters connected to the power grid. Eigenvalue trajectories are studied in order to obtain an accurate stability analysis. A timedomain simulation model of a 1.5 kW grid-connected converter is developed by using Matlab/Simulink to investigate the stability of the grid-following and gridforming control under different short-circuit ratios. The stability boundaries of the grid-following control and the grid-forming control are explored and compared with theoretical analysis. The result reveals that the gridfollowing control is better suited for a stiff power grid, while the grid-forming control is more suitable for a weak power grid. Finally, an experimental prototype is established to verify the effectiveness of the theoretical analysis.

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Metodologia de projeto de filtros de emissão conduzida aplicada a conversores CA/CC monofásicos Maicon W. M. de Carvalho 1,* , Djonny Weinzierl 1 , Sérgio V. G. Oliveira 1,2 1 Universidade do Estado de Santa Catarina, Programa de Pós-Graduação em Engenharia Elétrica, Santa Catarina, Brasil 2 Universidade Regional de Blumenau, Departamento de Engenharia de Telecomunicações, Elétrica e Mecânica, Santa Catarina, Brasil

Metodologia de projeto de filtros de emissão conduzida aplicada a conversores CA/CC monofásicos Maicon W. M. de Carvalho1,*, Djonny Weinzierl1, Sérgio V. G. Oliveira1,2 1

 Universidade do Estado de Santa Catarina, Programa de Pós-Graduação em Engenharia Elétrica, Santa Catarina, Brasil 2 Universidade Regional de Blumenau, Departamento de Engenharia de Telecomunicações, Elétrica e Mecânica, Santa Catarina, Brasil 

 ABSTRACT Electromagnetic interference filter design specifies circuit topology and elements, inductors, and capacitors of an electrical network whose purpose is to reduce interferential signals. This work presents an iterative methodology of EMI filter design for switched power supplies based on the sequential element theorem and the concept of the dominant effect in electromagnetic compatibility. This design methodology was proposed based on experiments with three commercial off-the-shelf power supplies and knowledge about common, differential, and mixed-mode emissions, as well as the non-idealities of the elements and the power supply's input impedance characteristics. In practical tests, the effect of the EMI filter resonance and the power supply's mixed-mode input impedance was observed, which served as a guideline for determining which component should be included or whether its value should be increased in the EMI filter structure. The most restrictive requirements were met with a few iterations and fewer components than the original filters, demonstrating that the concepts used as a reference are valid and valuable.

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Electronic Load for Parameter Characterization in Equivalent Circuit Models of Lithium-Ion Batteries-Suelen Bampi 1,* , Gierri Waltrich 1 , Anderson Vaccari 2 1Federal University of Santa Catarina, Postgraduate Program in Electrical Engineering, Florianopolis - SC, Brasil. 2Vale S.A, Development and Innovation Sector, Vila Velha - ES, Brasil.

 Electronic Load for Parameter Characterization in Equivalent Circuit Models of Lithium-Ion Batteries Suelen Bampi1,*, Gierri Waltrich 1, Anderson Vaccari2 1 Federal University of Santa Catarina, Postgraduate Program in Electrical Engineering, Florianopolis - SC, Brasil. 2 Vale S.A, Development and Innovation Sector, Vila Velha - ES, Brasil. 

 ABSTRACT The applications and implemented volume of lithium-ion batteries have been gaining momentum each year. Aiming to contribute to the development of research in this area, this paper presents the design and implementation of an electronic load focused on characterizing parameters inherent to equivalent circuit models (ECM). ECMs are commonly applied for estimating the State of Charge (SoC), State of Health (SoH), and Remaining Useful Life (RUL) of lithium batteries. In this paper, an electrical design of an electronic load was implemented and validated through laboratory instrumentation to obtain characteristic data from a lithium titanate cell. The data from the tests performed on the cell were used as input for a SoC estimation algorithm based on the Extended Kalman Filter (EKF) to help corroborate the prototype's performance. The results comprise the performance of the electronic load, the results associated with the parameterization tests of the lithium cells, and the results obtained for the cell’s SoC estimation using the EKF.

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Analysis and Implementation of a Single-Phase Bridgeless Hybrid Switched-Capacitor Rectifier in Discontinuous Conduction Mode for Power Factor Correction-

 

Analysis and Implementation of a Single-Phase Bridgeless Hybrid Switched-Capacitor Rectifier in Discontinuous Conduction Mode for Power Factor Correction

 Chrystian Mumic 1,∗, Marcus V. Soares 2, Yales R. de Novaes 1, Alan J. Watson 3 1Santa Catarina State University, Dept of Electrical Engineering, Joinville, Brazil. 2Silicon Austria Labs, Division Power Electronics, Graz, Austria. 3University of Nottingham, Dept. Electrical and Electronic Engineering, Nottingham, United Kingdom.

ABSTRACT 

This work presents the quantitative and qualitative analysis, as well as the experimental results of a practical implementation of the Single-Phase Bridgeless Hybrid Switched Capacitor Rectifier operating in discontinuous conduction mode (DCM) to achieve a high input power factor. Operating in DCM provides several advantages, including natural power factor correction (PFC) behavior of the input current and reduced semiconductor switching losses. The paper begins with a literature review on key studies of hybrid switched-capacitor converters with a high power factor. Subsequently, the converter analysis, including its modulation scheme, operational stages and design methodology, is detailed. The proposed approach is validated with results from a practical prototype implementation, achieving an output voltage of 1200 V and an output power of 315 W from an input voltage of 220 V. The converter demonstrated an efficiency of 97.3%, a power factor of 0.99, and harmonic distortion levels within the limits specified by IEC61000-3-2.

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