Article
Engineering, Electrical & Electronic
Haozhe Jin, Wu Chen, Yeyuan Xie, Liangcai Shu, Yutao Xu
Summary: This article proposes an optimized asymmetric trapezoidal wave (ATW) modulation scheme for a modular multilevel resonant dc/dc converter (MMRDC) to reduce current stress over wide load and voltage ranges. The optimized operating point of MMRDC is derived based on the soft switching characteristic and reactive current analysis, considering low current stress and zero voltage switching constraint. The experimental results on a 4 kW MMRDC prototype verify the correctness and effectiveness of the analysis and the optimized ATW modulation scheme.
IEEE TRANSACTIONS ON POWER ELECTRONICS
(2023)
Article
Engineering, Electrical & Electronic
Haozhe Jin, Wu Chen, Shuai Shao, Liangcai Shu
Summary: This article proposes a high step-ratio modular multilevel resonant dc/dc converter, which can reduce the number of submodules and the size of the filter, and achieve flexible current-shaping capability.
IEEE TRANSACTIONS ON POWER ELECTRONICS
(2023)
Article
Engineering, Electrical & Electronic
Govind Avinash Reddy, Anshuman Shukla
Summary: In this article, a new enhanced modular multilevel converter (EMMC) is introduced, which addresses the drawbacks of the conventional modular multilevel converters (MMC). The EMMC, based on a new submodule (SM) structure, is fully modular and requires fewer switches and capacitors. It possesses the features of reduced energy-storage requirement and dc fault-tolerant capability.
IEEE TRANSACTIONS ON POWER ELECTRONICS
(2023)
Article
Automation & Control Systems
Philippe A. Gray, Peter W. Lehn, Netan Yakop
Summary: This article proposes a novel modular multilevel dc-dc converter with high power-density potential. It combines the advantages of modular multilevel converter (MMC) and flying capacitor converter. The converter features a new current source submodule (CSM) stage that reduces the string current and allows common grounding of the input source and output load. The article introduces the operating principles and the control design, and the laboratory-scale prototype achieves a peak efficiency of 97.1%.
IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS
(2022)
Article
Engineering, Multidisciplinary
Mai Diab, Ahmed A. Elserougi, A. S. Abdel-Khalik
Summary: This paper presents a hybrid modular multilevel DC-DC converter topology that successfully solves the issue of capacitors voltage imbalance during DC-DC conversion. The proposed converter can achieve arm energy equalization and operate as a DC transformer.
ALEXANDRIA ENGINEERING JOURNAL
(2023)
Article
Engineering, Electrical & Electronic
Ramin Razani, Yasser Abdel-Rady I. Mohamed
Summary: This study investigates the operation limits of a hybrid dc/dc modular multilevel converter, identifying minimum achievable ac circulating current and maximum transmitted power impacted by unbalance in capacitor voltages. The research reveals that hybrid converters with larger transmitted power, higher conversion ratios, and larger arm inductance have more limited operation ranges.
IEEE JOURNAL OF EMERGING AND SELECTED TOPICS IN POWER ELECTRONICS
(2021)
Article
Engineering, Electrical & Electronic
Cristian Pineda, Javier Pereda, Felix Rojas, Gabriel Droguett, Claudio Burgos-Mellado, Alan J. Watson
Summary: This study introduces a novel zero-current switching modulation technique for high-step-ratio MMC DC-DC converters, which generates trapezoidal or triangular current by minimizing the root-mean-square current to operate the converter over a wide range of output voltage and power. The proposed optimization uses a simple control scheme to regulate output voltage and voltage balance among the floating cell capacitors, and has been validated through theoretical analysis and a laboratory-scaled prototype, demonstrating effectiveness and excellent dynamical response.
IEEE TRANSACTIONS ON POWER ELECTRONICS
(2021)
Article
Computer Science, Information Systems
Ming Huang
Summary: This paper proposes a non-isolated DC-DC MMC equipped with middle cells for interconnecting different DC voltages in medium-voltage applications. It achieves DC voltage conversion without bulky passive LC filters.
Article
Chemistry, Multidisciplinary
Hui Cai, Junli Zhang, Jingqiu Yu, Zheren Zhang
Summary: In order to address the challenges of DC short-circuit faults in MMC-based DC grid, a new method for accurately estimating fault currents and voltages was proposed. The model takes into account the dynamics of MMC control during faults and has a smaller error compared to existing methods, making it suitable for the entire DC grid.
APPLIED SCIENCES-BASEL
(2021)
Article
Engineering, Electrical & Electronic
Nibedita Parida, Anandarup Das
Summary: This article presents an isolated dc-dc modular multilevel converter topology designed to extract power from the HVdc link, featuring two stages of power conversion and a high-voltage transformation ratio. Operating at medium-frequency ac reduces the size of the transformer and passive elements, while implementing a sinusoidal level-shifted pulsewidth modulation technique ensures voltage close to a sine wave.
IEEE TRANSACTIONS ON POWER ELECTRONICS
(2021)
Article
Engineering, Electrical & Electronic
Zhengxuan Li, Bojin Tang, Qiang Song, Lifeng Gou, Biao Zhao, Na Jia, Fang Cai
Summary: A unidirectional-current clamp-double submodule (UC-CDSM) is proposed in this study, which combines two unidirectional-current full-bridge SMs (UC-FBSMs) using a shared switching device. The sharing design reduces the number of switching devices in the UC-CDSM-based MMC (UC-CD-MMC) by 25% compared to the UC-FBSM-based MMC. The UC-CD-MMC retains several advantages, such as low capacitor usage, dc fault clearing capability, and wide-range dc voltage adjustability.
IEEE TRANSACTIONS ON POWER ELECTRONICS
(2023)
Article
Automation & Control Systems
Mahmoud Mehrabankhomartash, Shiyuan Yin, Rajendra Prasad Kandula, Deepak Divan, Maryam Saeedifard
Summary: This article investigates the impact of magnetizing inductance on various aspects of the isolated modular multilevel dc-dc (IMM dc-dc) converter, including power, currents, voltage ripple, and soft-switching operation. The analysis is validated through time-domain simulation in MATLAB/Simulink and experiments on a scaled-down prototype.
IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS
(2023)
Article
Green & Sustainable Science & Technology
Ahmed Elserougi, Ibrahim Abdelsalam, Ahmed Massoud, Shehab Ahmed
Summary: This paper proposes a modified modular multilevel DC-DC converter with self-energy equalization, ensuring successful DC-DC conversion with balanced capacitor voltages. The new topology features clamping IGBTs in each arm for parallel connection of capacitors, and during operation, energy is transferred between arms using a small limiting inductor to maintain equal voltages. The proposed configuration, operational concepts, mathematical analysis, and design are presented, along with simulation and experimental results for validation.
IET RENEWABLE POWER GENERATION
(2021)
Article
Engineering, Electrical & Electronic
Wentao Cui, Shuai Shao, Tong Wu, Wu Chen, Junming Zhang
Summary: In this article, a full-range soft switching converter with wide voltage gain is proposed for modular multilevel resonant dc-dc converters. The converter utilizes a modular multilevel structure and CLLC resonant tank for isolated and bidirectional power conversion in medium-voltage applications, achieving high efficiency. The coordinated gain control method enables wide and continuous voltage gain regulation.
IEEE TRANSACTIONS ON POWER ELECTRONICS
(2023)
Article
Automation & Control Systems
Saurav Dey, Tanmoy Bhattacharya
Summary: A modular multilevel dc-dc converter philosophy is proposed in this article to exchange power between HVdc links of different voltage levels. The converter operates symmetrically in four quadrants, unaffected by voltage polarity, allowing power flow direction/magnitude to remain constant even with reversal of power flow in the HVdc link. The working principle is analytically explained and validated through simulation and experimental results.
IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS
(2021)
Article
Engineering, Electrical & Electronic
Jing Sheng, Cong Chen, Rui Lu, Chushan Li, Xin Xiang, Wuhua Li, Xiangning He
Summary: This article studies the output voltage control strategy of modular multilevel resonant dc converters (MMRDC) for medium-voltage wide-input-range applications. The feasibility and influence of switching frequency regulation and modulation index regulation are investigated, and a design and control optimization method based on modulation index regulation and switching frequency regulation is proposed. Experimental validation shows that the optimized control methods are effective, with an efficiency over 96.4% under a wide input range.
IEEE TRANSACTIONS ON POWER ELECTRONICS
(2022)
Review
Energy & Fuels
Sohail Sarwar, Desen Kirli, Michael M. C. Merlin, Aristides E. Kiprakis
Summary: This article reviews recent literature on the stability, management, and control strategies of AC/DC hybrid microgrids (HMG). Power flow analysis, power sharing, global control of distributed generation, and the complexity of HMG protection plans are examined. The review highlights the common techniques used in HMG control and identifies the challenges and limitations that need to be addressed for sustainable operation.
Article
Engineering, Electrical & Electronic
Jintao Lei, Xin Xiang, Wuhua Li, Xiangning He
Summary: This article introduces a Krylov-Bogoliubov-Mitropolsky (KBM) asymptotic method with perturbation theory to analyze the power angle trajectory under large disturbances. It also proposes a tailored integral method to simplify the solution and facilitate the analysis and calculation. The effectiveness and accuracy of the method are verified through simulations and control-hardware-in-loop experiments.
IEEE TRANSACTIONS ON POWER ELECTRONICS
(2023)
Article
Engineering, Electrical & Electronic
Ye Yan, Xin Xiang, Jintao Lei, Yuxiang Wang, Chushan Li, Chengmin Li, Wuhua Li, Xiangning He
Summary: In this article, the amplification effect of negative sequence voltage to negative sequence current under unbalanced grid voltage is revealed and explained. A phase-corrected proportional resonant (PR) controller is introduced to suppress the amplification effect and enhance system stability. A design scheme for phase correction angles is proposed to improve system dynamics. Finally, simulation and experiments validate the effectiveness of the proposed approach.
IEEE JOURNAL OF EMERGING AND SELECTED TOPICS IN POWER ELECTRONICS
(2023)
Article
Engineering, Electrical & Electronic
Yue Zhu, Yifan Zhang, Timothy C. Green
Summary: Impedance measurement techniques based on small-signal injections in ac power system have been well developed but lack accurate selection of injection amplitude. This letter proposes an analytical process to analyze power system noise and determine the minimum injection amplitude based on an allowable error. The process utilizes stochastic processes, statistics, and the Monte Carlo method. Experimental verification is performed using a power hardware-in-the-loop system with a grid-following inverter.
IEEE TRANSACTIONS ON POWER ELECTRONICS
(2023)
Article
Engineering, Electrical & Electronic
Tianling Shi, Hongyi Chen, Boxin Liu, Shiyuan Fan, Fei Wang, Xin Xiang, Huan Yang, Wuhua Li
Summary: The article studies the positive feedback islanding detection technique in DC microgrids, which has advantages in detection speed and nondetection zone. However, it may reduce the stability margin in the grid-connected state. In order to address this issue, the article develops a DC output impedance model to accurately reveal the dynamic interactions and instability mechanism caused by islanding detection. The stability region of the interconnected system is derived based on the output admittance model, and a grid-current-based active-damping control scheme is proposed to mitigate instability caused by the positive feedback loop. Simulations and experimental results validate the effectiveness of the proposed control method.
IEEE TRANSACTIONS ON POWER ELECTRONICS
(2023)
Article
Engineering, Electrical & Electronic
Yue Zhu, Yunjie Gu, Yitong Li, Timothy C. C. Green
Summary: Impedance models are useful in power systems where only black-box models are available. Sensitivity of modes to components and parameters are needed for tracing system problems. This paper formalizes the relationships between two forms of impedance models and between two forms of root-cause analysis, and develops a complete theory of impedance-based root-cause analysis. The theoretical relationships and tuning of parameters have been illustrated with different networks, showing that tools can be developed for tuning IBR-rich power systems.
IEEE TRANSACTIONS ON POWER SYSTEMS
(2023)
Article
Engineering, Electrical & Electronic
Jintao Lei, Xin Xiang, Boxin Liu, Wuhua Li, Xiangning He
Summary: In this study, a physical and intuitive assessment method is proposed to evaluate the damping effect in virtual synchronous generator (VSG) control. The concept of damping area is introduced to provide a visual representation of transient damping energy. Additionally, an approximation method is developed to quantitatively evaluate the attraction domain and its conservativeness for VSG control is validated.
IEEE TRANSACTIONS ON SMART GRID
(2023)
Article
Automation & Control Systems
Shiyuan Fan, Xin Xiang, Chushan Li, Yunjie Gu, Huan Yang, Wuhua Li, Xiangning He, Timothy C. Green
Summary: This article proposes a dual-circulant modulation method for balancing submodule capacitor voltages in modular multilevel dc-dc converters (MMDCs). The method combines two sets of circular switching patterns to fulfill the constraints on submodule voltages. The switching patterns are reallocated and optimized to ensure submodule uniformity and reduce capacitor voltage ripple. Simulations and experiments validate the voltage balancing capability and the optimization of capacitor voltage ripple with the proposed dual-circulant modulation.
IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS
(2023)
Article
Automation & Control Systems
Jintao Lei, Xin Xiang, Qiannan Qu, Wuhua Li, Xiangning He
Summary: With the increasing use of power converters in modern power systems, virtual synchronous generator (VSG) control is considered a promising method due to its grid friendliness. However, the lack of clear and accurate description of the power angle dynamics of VSG control poses challenges to stability analysis and converter parameter design. This article introduces the Krylov-Bogoliubov averaging method to characterize the dynamic trajectory of VSG control, and proposes an unperturbed-result-based averaging method to obtain the explicit time-domain expression of power angle dynamics, which may have potential applications in transient stability analysis and grid-connected converter design. Simulations and control-hardware-in-the-loop experiments are conducted to verify the effectiveness of the proposed method.
IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS
(2023)
Article
Engineering, Electrical & Electronic
Jing Sheng, Xin Xiang, Boliang Li, Rui Lu, Chushan Li, Xiaotian Zhang, Wuhua Li, Xiangning He
Summary: This article provides a detailed analysis of the technical challenges faced by the modular multilevel resonant dc-dc converters (MMRDCs) in high-efficient operation, wide input range, and wide load condition. It proposes tailored solutions to address these challenges, including a voltage regulation method combining phase shift angle control and inserted submodule number control. The effectiveness of the proposed strategy is demonstrated through simulation and experimental results.
IEEE TRANSACTIONS ON POWER ELECTRONICS
(2023)
Article
Engineering, Electrical & Electronic
Ye Yan, Jintao Lei, Boxin Liu, Xin Xiang, Chushan Li, Chengmin Li, Wuhua Li, Xiangning He
Summary: This article studies phase-corrected proportional resonant (PCPR) current controllers under low carrier ratios for high-power converters. It is found that without proper parameter design, the system can become unstable or have poor dynamics. To guide parameter design, bilateral Bode plots are used to illustrate stability and dynamics, considering the negative jump direction at resonant frequencies. The analysis tool verifies the feasibility of phase correction angles over 90 degrees, especially under a carrier ratio below six. Through the designed phase correction and resonant gain, the stability region of carrier ratios is extended to the theoretical limit of one, and dynamic performance is improved.
IEEE TRANSACTIONS ON POWER ELECTRONICS
(2023)
Article
Engineering, Electrical & Electronic
Yunjie Gu, Timothy C. Green
Summary: This article discusses the dynamics of inverter-based resources (IBRs) and how they can be categorized in terms of power system stability. The study shows that inverters have different dynamics compared to synchronous-generator-based sources and their interactions with the power system are changing. The article also explores the similarities and differences between grid-forming (GFM) and grid-following (GFL) inverters in terms of synchronization, inertia, and voltage control. Additionally, the article highlights the importance of further research in nonlinear stability analysis, spatial-temporal indices of system strength and stability margin, and data-driven approaches for inverter models.
PROCEEDINGS OF THE IEEE
(2023)
Editorial Material
Engineering, Electrical & Electronic
Chongqing Kang, Daniel Kirschen, Timothy C. Green
Summary: This month's articles provide a comprehensive examination of the smart grid evolution through power system digitalization and marketization, renewable energy penetration, and electronic device integration.
PROCEEDINGS OF THE IEEE
(2023)
