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Fault locating for traveling-wave accelerators based on transmission line theory

Nuclear Science and Techniques 2023年第8期34卷 24-34页

作者： Tong-Ning Hu Hai-Meng Wang Yi-Feng Zeng Hong-Jie Xu Li Chen Guang-Yao Feng Yuan-Ji Pei State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic EngineeringHuazhong University of Science and TechnologyWuhan 430074China State Grid Fujian Economic Research Institute Fuzhou 350012China National Synchrotron Radiation Laboratory University of Science and Technology of ChinaHefei 230029China

Radio-frequency(RF)breakdown analysis and location are critical for successful development of high-gradient traveling-wave(TW)accelerators,especially those expected to generate high-intensity,high-power *** with commonly used schemes involving dedicated devices or complicated techniques,a convenient approach for breakdown locating based on transmission line(TL)theory offers advantages in the typical constant-gradient TW-accelerating *** deliver such an approach,an equivalent TL model has been constructed to equate the TW-accelerating structure based on the fun-damental theory of the TL transient response in the time *** equivalence relationship between the TW-accelerating structure and the TL model has been established via analytical derivations associated with grid charts and verified by TL circuit ***,to validate the proposed fault-locating method in practical applications,an elaborate analysis via such a method has been conducted for the recoverable RF-breakdown phenomena observed at an existing prototype of a TW-accelerating-structure-based beam injector constructed at the Huazhong University of Science and *** addition,further considerations and discussion for extending the applications of the proposed method have been *** breakdown-locating approach involving the transient response in the framework of TL theory can be a conceivable supple-ment to existing methods,facilitating solution to construction problems at an affordable cost.

关键词： Traveling-wave structure RF breakdown Fault locating Transmission line

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Porous metal oxides in the role of electrochemical CO_(2) reduction reaction

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Journal of Energy Chemistry 2024年第1期88卷 373-398,I0009页

作者： Ziqi Zhang Jinyun Xu Yu Zhang Liping Zhao Ming Li Guoqiang Zhong Di Zhao Minjing Li Xudong Hu Wenju Zhu Chunming Zheng Xiaohong Sun School of Chemical Engineering and Technology Tianjin Key Laboratory of Green Chemical Technology and Process EngineeringState Key Laboratory of Separation Membrane and Membrane ProcessesTiangong UniversityTianjin 300387China School of Materials Science and Engineering Key Laboratory of Advanced Ceramics and Machining TechnologyMinistry of EducationTianjin UniversityTianjin 300072China

The global energy-related CO_(2) emissions have rapidly increased as the world economy heavily relied on fossil *** paper explores the pressing challenge of CO_(2) emissions and highlights the role of porous metal oxide materials in the electrocatalytic reduction of CO_(2)(CO_(2)RR).The focus is on the development of robust and selective catalysts,particularly metal and metal-oxide-based *** metal oxides offer high surface area,enhancing the accessibility to active sites and improving reaction *** tunability of these materials allows for tailored catalytic behavior,targeting optimized reaction mechanisms for CO_(2)*** work also discusses the various synthesis strategies and identifies key structural and compositional features,addressing challenges like high overpotential,poor selectivity,and low *** on these insights,we suggest avenues for future research on porous metal oxide materials for electrochemical CO_(2) reduction.

关键词： CO_(2)reduction Carbon dioxide Transformation Porous metal oxides Electrocatalysis

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Low-temperature rapid sintering for the fabrication of biphasic Si3N4 ceramics with outstanding mechanical properties

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Journal of advanced Ceramics 2025年第3期14卷 143-150页

作者： Shuo Zhao Songmo Du Shijia Zhang Dengke Zhao Binbin Fan Bohan Wang Fei Li Kexin Chen Guanghua Liu State Key Laboratory of New Ceramic Materials School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China State Key Laboratory for Advanced Metals and Materials University of Science and Technology BeijingBeijing 100083China

The fabrication of Si3N4 ceramics typically requires high temperatures(above 1700℃)and prolonged sintering time to achieve densification,resulting in high energy consumption and increased manufacturing ***,reports on the fabrication of dense Si3N4 ceramics with good mechanical properties under MPa-level pressure and low temperatures are *** this work,we propose a low-temperature rapid spark plasma sintering strategy involving the introduction of fine-grainedβ-Si3N4 powder with high lattice strain energy as an“additive”.Dense biphasic Si3N4 ceramics,predominantlyα-Si3N4,were successfully fabricated at a mechanical pressure of 200 MPa and a temperature of 1300℃,achieving a relative density of 97%.The application of high pressure promoted particle rearrangement and uniform liquid‒phase distribution,providing additional driving forces for *** introduction ofβ-Si3N4 seeds facilitated an in-situ solution–reprecipitation process,enabling rapid densification with a minimal liquid phase and without significant grain growth,resulting in nanometer-scale *** Si3N4 sample prepared at 1350℃ exhibited a desirable combination of high hardness(18.5±0.3 GPa)and fracture toughness(6.7±0.2 MPa·m_(1/2)).The results demonstrate that by adjusting the sintering temperature and time,the phase composition and mechanical properties of the ceramics can be flexibly *** work holds significant potential for industrial manufacturing and provides valuable insights into low-temperature strategies for ceramic fabrication.

关键词： low temperature sintering silicon nitride β-Si3N4 seeds spark plasma sintering(SPS)

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Analysis of Discharge Characteristics and Parameter Influence of Pulsed Power Supply for Electrothermal Chemical Shotguns

Analysis of Discharge Characteristics and Parameter Influenc...

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2024 IEEE China International Youth Conference on Electrical engineering, CIYCEE 2024

作者： Fu, Chenxu Yu, Kexun Xie, Xianfei School of Electrical and Electronic Engineering Huazhong University of Science and Technology The State Key Laboratory of Advanced Electromagnetic Engineering and Technology Wuhan430074 China

ISBN: (纸本)9798331530174

The discharge current waveform of the pulse power supply(PPS) has a direct relationship with the characteristics of the discharge load. The load of the electrothermal chemical cannon is mainly a plasma generator, which involves many complex physical processes in the discharge emission process. However, at present, fixed resistance is generally used to simulate the load for discharge, so it is impossible to accurately study the discharge characteristics of pulsed power supply to electrothermal chemical cannon. Therefore, a 560KJ PPS is initially designed in this paper, and the mathematical model of the pulse power supply and plasma generator load is established. Combined with the internal ballistic model of the electrothermal chemical gun, the model is discretized by the fourth-order Runge-Kutta method, and the corresponding discharge current, discharge output energy and projectile velocity curves are calculated and drawn. Based on the established mathematical model of pulse power supply for electrothermic chemical shotguns, the effects of different parameters of PPS on discharge performance are analyzed, which provides a reference for the optimization of discharge parameters of PPS. © 2024 IEEE.

关键词： Electric discharges

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Challenges and strategies of formulating low-temperature electrolytes in lithium-ion batteries

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Interdisciplinary Materials 2023年第2期2卷 308-336页

作者： Mingsheng Qin Ziqi Zeng Shijie Cheng Jia Xie State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic EngineeringHuazhong University of Science and TechnologyWuhanChina State Key Laboratory of Materials Processing and Die&Mould Technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhanChina

Lithium-ion batteries(LIBs)have monopolized energy storage markets in modern *** reliable operation of LIBs at cold condition(<0°C),nevertheless,is inevitably hampered by the sluggish kinetics and parasite reactions,which falls behind the increasing demands for portable electronics and electric *** electrolyte controls both Li+transport and interfacial reaction,dictating the low-temperature performance ***,the rational formulation of electrolytes is significant for realizing superior lowtemperature performance and broadening application niches of ***,we first discuss the kinetic limitations of low-temperature LIBs,highlighting the importance of electrolyte structure and interfacial ***,the advancements for formulating subzero-temperature electrolyte are summarized with in-depth discussions about electrolyte formulation,solvation structure,interfacial chemistry,and low-temperature ***,some opportunities for lithium metal batteries and the corresponding lowtemperature electrolyte are ***,the major challenges and future perspectives are outlined for low-temperature LIBs.

关键词： electrolyte lithium-ion batteries low temperatures solvation structures

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Adaptive state-of-Charge Control Strategy for Hybrid Energy Storage System Based on Grid-Forming Converter

Adaptive State-of-Charge Control Strategy for Hybrid Energy ...

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2024 IEEE China International Youth Conference on Electrical engineering, CIYCEE 2024

作者： Cui, Bowen Chen, Changsong Gan, Lin Li, Xiayan Zhong, Yuanhao School of Electrical and Electronic Engineering Huazhong University of Science and Technology State Key Laboratory of Advanced Electromagnetic Engineering and Technology Wuhan430074 China

ISBN: (纸本)9798331530174

At present, Grid-Forming (GFM) control is recognized as the most promising control technology for grid-connected converters. The energy the GFM converters provide for grid frequency support is mainly sourced from energy storage (ES). Hybrid Energy Storage (HES) systems have the potential to combine the advantages of different types of ES, thereby enhancing the frequency response and inertia emulation capabilities. Nevertheless, ES may encounter state-of-Charge (SOC) limit issues in practice. This paper focuses on the control of the HES system based on GFM converter (GFM-HES). An adaptive SOC control strategy is proposed. On the one hand, closed-loop control of the Supercapacitor terminal voltage is employed to achieve fast SOC recovery. On the other hand, adaptive SOC control for the battery is adopted to prevent it from entering the overcharge and over-discharge zone. The simulation results verify the effectiveness of the proposed control strategy. © 2024 IEEE.

关键词： state of charge

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Intelligent Predetermination of Generator Tripping Scheme: Knowledge Fusion-based Deep Reinforcement Learning Framework

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CSEE Journal of Power and Energy Systems 2024年第1期10卷 66-75页

作者： Lingkang Zeng Wei Yao Ze Hu Hang Shuai Zhouping Li Jinyu Wen Shijie Cheng State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronics EngineeringHuazhong University of Science and TechnologyWuhan 430074China Dispatching and Control Center Central China Branch of State Grid Corporation of ChinaWuhan 430077China. Department of Electrical Engineering and Computer Science University of TennesseeKnoxvilleTN 37996USA

Generator tripping scheme(GTS)is the most commonly used scheme to prevent power systems from losing safety and ***,GTS is composed of offline predetermination and real-time scenario ***,it is extremely time-consuming and labor-intensive for manual predetermination for a large-scale modern power *** improve efficiency of predetermination,this paper proposes a framework of knowledge fusion-based deep reinforcement learning(KF-DRL)for intelligent predetermination of ***,the Markov Decision Process(MDP)for GTS problem is formulated based on transient instability ***,linear action space is developed to reduce dimensionality of action space for multiple controllable ***,KF-DRL leverages domain knowledge about GTS to mask invalid actions during the decision-making *** can enhance the efficiency and learning ***,the graph convolutional network(GCN)is introduced to the policy network for enhanced learning *** simulation results obtained on New England power system demonstrate superiority of the proposed KF-DRL framework for GTS over the purely data-driven DRL method.

关键词： Deep reinforcement learning generator tripping scheme graph convolutional network invalid action masking knowledgefusion

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Control Delay Compensation of Three-Level Synchronous SVPWM Based on Smith Predictor

Control Delay Compensation of Three-Level Synchronous SVPWM ...

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2024 IEEE China International Youth Conference on Electrical engineering, CIYCEE 2024

作者： Wang, Zhengxiao Liu, Kaifeng Ye, Caiyong Liu, Haoqi Wan, Shanming School of Electrical and Electronic Engineering Huazhong University of Science and Technology State Key Laboratory of Advanced Electromagnetic Engineering and Technology Wuhan430074 China

ISBN: (纸本)9798331530174

High-speed and high-power motor drive systems are critical for applications such as electric vehicles and industrial automation. These systems often utilize synchronous space vector pulse width modulation (SSVPWM) strategies to optimize performance. However, the multi-mode synchronous SVPWM will bring about a sudden change in the phase angle due to the switching of the number of pulses. This paper proposes a method employing the Smith predictor to correct phase and amplitude errors caused by digital control delays. Compared with the existing methods, this method can respond to phase error more quickly, especially at low carrier ratio, thus improving the stability and performance of the system. © 2024 IEEE.

关键词： Digital control systems

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Small-Signal Stability Analysis of Parallel Grid-Connected System with Grid-Forming Converter and Grid-Following Converter

Small-Signal Stability Analysis of Parallel Grid-Connected S...

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2024 IEEE China International Youth Conference on Electrical engineering, CIYCEE 2024

作者： Li, Xiayan Chen, Changsong Gan, Lin Bai, Chenxi He, Taihang School of Electrical and Electronic Engineering Huazhong University of Science and Technology State Key Laboratory of Advanced Electromagnetic Engineering and Technology Wuhan430074 China

ISBN: (纸本)9798331530174

In order to guarantee the stable operation of new energy sources when connected to the power system through converters, it is of paramount importance to conduct thorough research the small-signal stability of parallel grid-connected system with grid-forming converter (GFM) and grid-following converter (GFL). Initially, the state-space small-signal model of the parallel grid-connected system with GFM and GFL are derived. Subsequently, the impact of the phase-locked loop (PLL) bandwidth, virtual inertia, and reactive power loop integral coefficient on system stability is assessed using the eigenvalue locus method. Moreover, the participation factor analysis method is employed to identify the dominant state variables of the oscillatory mode. Finally, the correctness of the theoretical analysis is validated using PLECS. © 2024 IEEE.

关键词： Eigenvalues and eigenfunctions

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Low-Voltage Ride-Through Method for Grid-Forming Converter Based on Adaptive Virtual Impedance

Low-Voltage Ride-Through Method for Grid-Forming Converter B...

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2024 IEEE China International Youth Conference on Electrical engineering, CIYCEE 2024

作者： Zhong, Yuanhao Chen, Changsong Cui, Bowen Bai, Chenxi He, Taihang School of Electrical and Electronic Engineering Huazhong University of Science and Technology The State Key Laboratory of Advanced Electromagnetic Engineering and Technology Wuhan430074 China

ISBN: (纸本)9798331530174

Due to the good weak grid adaptability and grid support capability, Grid-Forming (GFM) energy storage converter is considered to be an effective solution for the grid-connected interface of new power systems. When a symmetrical low-voltage fault occurring, grid-forming converters may face transient overcurrent problems during the fault and recovery phases. A virtual synchronous generator (VSG)-controlled GFM converter is take as the research object in this paper and a low-voltage ride-through (LVRT) control method of GFM converter is proposed, which realizes the current limitation of GFM converter under low-voltage fault by using adaptive virtual impedance. On the basis of guaranteeing the voltage source characteristics of GFM converter, L VRT control method injects reactive current into the grid according to standards. Finally, based on the Simulink/Matlab simulation platform, the effectiveness of L VRT control method for transient current suppression is verified. © 2024 IEEE.

关键词： Synchronous generators

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