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4th IEEE China International Electrical and Energy Conference, CIEEC 2021

作者： Du, Wenjiao Lu, Chen Xiong, Zilan Tang, Zhenpeng Zhao, Chongzhi Chen, Xingyu Hangmen Power Supply Bureau Guangdong Power Grid Company Jiangmen China State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China

ISBN: (纸本)9781728171494

Surface microdischarge (SMD) has various application potential in biomedicine, agriculture and industry. An important issue for practical use is to develop an online monitoring method for operation mode recognition of SMD. In this paper, we proposed a operation mode recognition method for SMD based on digital image processing technique. The visible light digital images of SMD were shot and the RGB chromaticity index of the discharge images were extracted. It was found that the sum of all pixel values in the SMD discharge gray scale image and in the R, G, and B monochromatic images increased with the applied voltage monotonically, which can reflect the change of the discharge intensity. The difference between the proportions of the B component and the G component ( Δ (B-G)%) showed a trend of first increasing and then decreasing as the applied voltage increased. The Δ (B-G)% reached the maximum value of 46.93% at Vp-p of 5kV and was corresponding to the mode transition point measured by Fourier transform infrared spectrometer (FTIR). Finally, a SMD operation mode recognition method, based on the Δ (B-G)% and the applied voltage was proposed. © 2021 IEEE.

关键词： Image processing

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Junction Temperature Estimation Method for Press-pack IGBTs Using Double-side Thermal Resistance Network Model

Junction Temperature Estimation Method for Press-pack IGBTs ...

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Energy Storage and Conversion (ISESC), CPSS & IEEE International Symposium on

作者： Liuyu Tu Lin Liang Li Wang Ziyang Zhang Zhiyuan Zhang Kaijun Wen State Key Laboratory of Advanced Electromagnetic Technology School of Electrical and Electronic Engineering Engineering Research Center of Power Safety and Efficiency Ministry of Education of China Huazhong University of Science and Technology Wuhan China CTG Jiangsu Energy Investment Co. Ltd Nanjing China

ISBN: (数字)9798350380514

ISBN: (纸本)9798350380521

Due to the asymmetry of the double-side structure of press-pack insulated-gate bipolar transistors (PP IGBTs), the physical significance and calculation method of parameters in the thermal resistance network model are not clear, which brings some challenges to the junction temperature (Tj) estimation method using this model. In this paper, two kinds of double-side thermal resistance network physical models are proposed by calculating the heat flow ratio on both sides and taking the temperature of the top and bottom case as the reference isothermal point. In the single chip packaging and double-side water cooling conditions, the simulation results show that the maximum relative error of the junction temperature estimation of two kinds of models established and the traditional model is −0.13%, 1.21% and −1.42%, respectively. The experiment also verifies that the proposed model has the highest accuracy and a certain range of application for the junction temperature estimation of PP IGBTs.

关键词： Insulated gate bipolar transistors Temperature distribution Accuracy Thermal resistance Simulation Estimation Packaging Thermal conductivity Junctions Resistance heating

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Multiphysics Modeling and Parameter Analysis of Industrial Power-to-Hydrogen Electrolyzers

Multiphysics Modeling and Parameter Analysis of Industrial P...

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Energy, Electrical and Power engineering (CEEPE), International Conference on

作者： Ke Chen Kewei Hu Jie Yang Feng Chen Zhiyao Zhong Jiakun Fang State Grid Hubei Electric Power Company Limited Economic Research Institute Wuhan China State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China

This paper proposes the multiphysics model of the industrial power-to-hydrogen electrolyzers. Based on the multi-energy flow in the industrial power-to-hydrogen electrolysis plant, the coupling among the multiphysics in the electrolyzer, including the electrochemical reaction, the flow field, the mass transfer and the temperature field, are unveiled. The governing equations and coupling mechanisms of the physical fields are introduced in detail, which are further illustrated according to the simulation results in COMSOL Multiphysics. Furthermore, several critical parameters, including the cell voltage, temperature and the concentration of the electrolyte, are analyzed based on the proposed model. Through the analysis on the current density- voltage characteristics, it can be concluded that the operating of the industrial electrolyzer usually faces the trade-off between the hydrogen production rate and the efficiency. The proposed model provides multiphysics explanations on the industrial statistics of the electrolyzer.

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AC Loss Evaluation of a Toroidal D-Shaped 10 MJ Superconducting Magnet

AC Loss Evaluation of a Toroidal D-Shaped 10 MJ Superconduct...

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International Conference on Applied Superconductivity and electromagnetic Devices, ASEMD

作者： Li Li Meng Song Feiyang Long Ying Xu Li Ren Joint Laboratory on Power Superconducting Technology China Southern Power Grid Company Ltd Guangzhou China State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan China

A 10 MJ HTS SMES designed for power system voltage compensation and active-reactive power regulation applications is under construction. The system aims to complete 10MJ charging or discharging in 2s time, so it is crucial to analyze its AC losses. In this paper, the AC loss of the magnet is analyzed by the dimensional reduction inversion method, and the AC loss of the magnet for one complete working cycle is obtained to be about 72 KJ, which provides a reference for the design of the cooling system of SMES.

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Reduced-order Model of Frequency Response Including PLL-based DFIG Wind Turbine

Reduced-order Model of Frequency Response Including PLL-base...

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Smart Grids and Energy Systems (SGES), International Conference on

作者： Ye Zhang Wangqianyun Tang Yifan Fang Yanjun Liu Wei He Yingbiao Li State Key Laboratory of HVDC China Southern Power Grid CSG Electric Power Research Institute Guangzhou China State Key Laboratory of Advanced Electromagnetic Engineering and Technology and School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan China

In the existing power system frequency response models, most of them ignore the dynamic process of inertial response of renewable energy generation equipment, which makes the new characteristics of power system frequency dynamics not described. In this paper, we take a doubly-fed induction generator (DFIG) as an example and establish its electromechanical time-scale motion equation in the frequency domain from its basic control structure, and extract the active power-frequency branch as the equivalent inertia of the DFIG, and the average frequency response model of the system was developed on this basis. Considering the inconvenience of higher order systems in the analysis, the least squares method is used to reduce the order of the frequency response model. Finally, the above model is simulated in MATLAB/Simulink and the simulation results are analyzed.

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Magnetic Welding of Large-Diameter Aluminum-Steel Dissimilar Metal Tubes: Actuator Design, Welding Process and Mechanism

SSRN

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SSRN 2023年

作者： Li, Xiaoxiang Liu, Haixiang Tang, Xinyu Tang, Yinghao Lai, Zhipeng Han, Xiaotao Cao, Quanliang Li, Liang Wuhan National High Magnetic Field Center Huazhong University of Science and Technology Wuhan430074 China State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan430074 China

Magnetic pulse welding (MPW) belongs to the category of high-speed welding technology that shows unique advantages and broad application prospects in welding of dissimilar metals. However, this technology faces bottlenecks of limited processing scale and difficulty in improving welding quality, which restrict its application and development. This is because welding tubes with large diameters places strict requirements on the welding tools, and the relationship between the performance of welded joints and welding process parameters is unclear. To solve these issues, the fiber reinforcement layer technology and a field shaper (FS) with a multi-turn winding structure are introduced to develop a magnetic actuator with high mechanical strength and good heat dissipation performance. The influences of multiple parameters on welding quality were revealed through systematic welding experiments and mechanical tests. The results show that the 6061-O aluminum alloy tubes with diameter of 110 mm and thickness of 3 mm achieve high quality welding with 304 stainless steel tubes. Importantly, the voltage-gap and velocity-angle welding quality windows are built up by combining the experimental and numerical methods. The voltage-gap welding window indicates that moderately increasing the tube gap and discharge voltage are conducive to improve the welding quality. Besides, the relationship among the impact velocity, angle, and bonding strength is provided by velocity-angle welding window. Meanwhile, the simulations of welding interface formation and metallographic observation methods are presented to further investigate the welding effect and reveal the dynamic behavior under different welding conditions. The presented results are of great significance to understanding the MPW process and expanding its practical applications. © 2023, The Authors. All rights reserved.

关键词： Numerical methods

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Research on Fast-Cooling Extinguishing Agent for Lithium-Ion Battery Fire 9th

Research on Fast-Cooling Extinguishing Agent for Lithium-Ion...

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9th Frontier Academic Forum of Electrical engineering, FAFEE 2020

作者： Tian, Jie Wu, Lin Li, Yan Zhao, Yuming Cao, Yuan-Cheng Shenzhen Power Supply Col. Ltd Shenzhen518001 China State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan430074 China

ISBN: (纸本)9789813366053

Present extinguishing agents for lithium-ion battery fire have room for improvement. Conventional fire extinguishing agents such as Perfluoro(2-Methyl-3-Pentanone) (NOVEC1230) have strong ability to extinguish fire but with poor cooling effect. While ‘Semi-fluorine materials’ such as hydrogen fluoride ether (HFE) and hydrofluorocarbon (HFC) present excellent cooling effect but with weaker ability of extinguishing fire. After combining the two extinguishing agents, the mixture features excellent performance in both extinguishing and cooling aspects. Based on this, a special fire extinguishing agent for lithium-ion battery, composed of a ratio of 1:1 of NOVEC1230 and 1,1,2,2,3,3,4-heptafluorocyclopentane (heptafluorocyclopentane) was designed and a tiny bit of isocyanate additives was added to decelerate the corrosion of the steel container during the storage period. And it has great extinguishing effect on the lithium-ion battery fire. © 2021, Beijing Oriental Sun Cult. Comm. CO Ltd.

关键词： Fires

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Ultrafast Synthesis of Spinel AMn2O4 (a= Co, Mn, Zn) Nanopolyhedras and Their Composites Applied to Lithium Ion Battery Anode

SSRN

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SSRN 2024年

作者： Zhang, Dan Zhang, Chunyan Xu, Huishi Huo, Jie Shi, Xinyu Luo, Baomin Liu, Guangyin Liu, Xiaodi Li, Liping Yu, Chuang College of Chemistry and Pharmaceutical Engineering Nanyang Normal University Nanyang473061 China State Key Laboratory of Inorganic Synthesis and Preparative Chemistry College of Chemistry Jilin University Changchun130012 China State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan430074 China

Spinel oxide anode materials are hardly used for commercial lithium-ion batteries because of their evident volume expansion in the discharging process and poor electronic conduction. Preparing a composite material of nanostructured spinel bimetallic oxides and carbon will solve the above problems and achieve outstanding electrochemical performance. In this study, an ultrafast approach (only 10 min) to synthesize spinel AMn2O4 (A= Co, Mn, Zn) nanopolyhedras and their composites with GO was successfully developed. Integrating spinel CoMn2O4 nanopolyhedras with GO can profoundly inhibit the problem of volume expansion but also eminently upgrading conductivity. The CoMn2O4/GO composite anode displays competent cyclic life and rate capability for lithium ion battery, delivering a large capacity of 738 mAh g-1 after 340 cycles at 2 A g-1. The ultrafast approach and alluring electrochemical performance of this work will inevitably give impetus to the fast development and application of spinel oxides. © 2024, The Authors. All rights reserved.

关键词： Anodes

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Pole-to-ground Fault Analysis for HVDC Grid Based on Common-and Differential-mode Transformation

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Journal of Modern Power Systems and Clean Energy 2020年第3期8卷 521-530页

作者： Zhen He Jiabing Hu Lei Lin Yuanzhu Chang Zhiyuan He State Key Laboratory of Advanced Electromagnetic Engineering and Technology and School of Electrical and Electronic EngineeringHuazhong University of Science and TechnologyWuhan 430074China Global Energy Interconnection Research Institute State GridBeijing 100192China

Pole-to-ground(PTG) fault analysis is of vital importance for high-voltage direct current(HVDC) grid. However, many factors are not considered in the existing studies such as the asymmetrical property of PTG fault, the coupling issue between DC transmission lines and the complexity of the structure of DC grid. This paper presents a PTG fault analysis method, which is based on common-and differential-mode(CDM)transformation. Similar to the symmetrical component method in AC system, the transformation decomposes the HVDC grid into CDM networks, which is balanced and decoupled. Then, a transfer impedance is defined and calculated based on the impedance matrices of the CDM networks. With the transfer impedance, analytical expressions of fault characteristics that vary with space and time are obtained. The proposed PTG fault analysis method is applicable to arbitrary HVDC grid topologies,and provides a new perspective to understand the fault mechanism. Moreover, the analytical expressions offer theoretical guidance for PTG fault protection. The validity of the proposed PTG fault analysis method is verified in comparison with the simulation results in PSCAD/EMTDC.

关键词： High-voltage direct current(HVDC)grid pole-to-ground(PTG)fault common-and differential-mode(CDM)transformation DC ciruit breaker(DCCB)

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Electrochemical Lithium Storage Mechanism Exploration of A 4.1 V Cathode Material with high energy/power density and low cost

SSRN

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SSRN 2023年

作者： Hou, Jie Chen, Suo Wang, Wei Wang, Kangli Jiang, Kai State Key Laboratory of Materials Processing and Die & Mould Technology School of Materials Science and Engineering Huazhong University of Science and Technology Hubei Wuhan430074 China State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Hubei Wuhan430074 China

In this work, cost effective and high energy/power density Na2.4Fe1.8(SO4)3 (NFS) is adopted as cathode material in Lithium ion Batteries (LIBs) for the first time. The carbon coated NFS is synthesized via a simple solid state method under 400 ℃. The highly effective multidimensional electron transport path and stable polyanion structure enables extremely high electrochemical lithium storage performance of NFS. The optimized NFS composite displays high specific capacity and discharge voltage (101.2 mAh g-1, 3.82 V at 1 C), superb rate performance (88.1 mAh g-1 at 20 C with average discharge voltage plateau of 3.46 V vs. Li+/Li) and excellent cycle stability (92.6% of the initial capacity after 1000 cycles at 10 C). Electrochemical and non-electrochemical behaviors of NFS cathode in lithium ions contained electrolyte have been thoroughly studied to better understanding the Lithium storage mechanism. This work proves that the low cost Fe-based sulfate NFS is a very competitive candidate as cathode material for LIBs. © 2023, The Authors. All rights reserved.

关键词： Lithium-ion batteries

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