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arXiv 2022年

作者： Yao, Jianpeng Cao, Quanliang Ju, Yuwei Sun, Yuxuan Liu, Ruiqi Han, Xiaotao 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 soft robots have attracted growing interest due to their unique advantages in terms of untethered actuation and excellent controllability. However, finding the required magnetization patterns or magnetic fields to achieve the desired functions of these robots is quite challenging in many cases. No unified framework for design has been proposed yet, and existing methods mainly rely on manual heuristics, which are hard to satisfy the high complexity level of the desired robotic motion. Here, we develop an intelligent method to solve the related inverse-design problems, implemented by introducing a novel simulation platform for magnetic soft robots based on Cosserat rod models and a deep reinforcement learning framework based on TD3. We demonstrate that magnetic soft robots with different magnetization patterns can learn to move without human guidance in simulations, and effective magnetic fields can be autonomously generated that can then be applied directly to real magnetic soft robots in an open-loop way. Copyright © 2022, The Authors. All rights reserved.

关键词： Magnetic fields

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Real-Time Estimation of Time-Varying Inertia for Non-Synchronous Devices

SSRN

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SSRN 2023年

作者： Li, Yulong Yao, Wei Zhao, Yifan Huang, Wei Zhai, Suwei Li, Wenyun Wen, Jinyu State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronics Engineering Huazhong University of Science and Technology Wuhan430074 China Kunming Power Supply Bureau Yunnan Power Grid Company Limited Kunming650012 China Yunnan Power Grid Company Limited Kunming650011 China

With the increasing integration of renewable and non-synchronous resources, the declining level of inertia poses a threat to the stability of power systems. This paper delves into the mechanism of time-varying inertia within mainstream non-synchronous devices and proposes a real-time estimation technique to estimate the constant and time-varying inertia associated with them. By applying the numerical integration method, this technique utilizes observations and their integrals over a continuous timeframe to formulate a system of equations, enabling the estimation of inertia at any given moment. Based on the linear operator analysis, the relationship between the aforementioned system of equations and linear operators is investigated to downscale the original high-dimensional system and extract the inertia. A significant addition is the introduction of the streaming dynamic mode decomposition (sDMD) algorithm, which updates linear operators based on snapshots composed of observations. Its update merely necessitates a small snapshot length, resulting in efficient data storage utilization and space conservation. Case studies on mainstream non-synchronous devices under various controls demonstrate its effectiveness and accuracy for real-time estimation of time-varying inertia. The remarkable advantage of this technique over the existing state-of-the-art method lies in its ability to operate without setting any hyperparameters. © 2023, The Authors. All rights reserved.

关键词： Dynamic mode decomposition

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LVRT During-fault-stage Equilibrium Point is Unnecessary for Renewable Grid-tied Systems

LVRT During-fault-stage Equilibrium Point is Unnecessary for...

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Power System and Green Energy Conference (PSGEC)

作者： Yayao Zhang Min Cheng Meng Zhan Jiawei Yu Yihua Zhu Mingkang Wu State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan China Yunnan Power Grid China State Key Laboratory of HVDC Electric Power Research Institute China Southern Power Grid China National Energy Power Grid Technology R&D Centre Electric Power Research Institute China Southern Power Grid China Guangdong Provincial Key Laboratory of Intelligent Operation and Control for New Energy Power System Electric Power Research Institute China Southern Power Grid China

ISBN: (数字)9798350365573

ISBN: (纸本)9798350365580

Transient synchronous stability of renewable grid- tied systems is of paramount importance. Most of previous studies focused on the grid-tied converter in the low voltage ride through (LVRT) during-fault stage and performed stability analysis based on the belief that if the system has (or has no) a stable equilibrium point in the during-fault stage, the system will be stable (or unstable). Therefore, it has been broadly accepted that the existence and/or stability of equilibrium point in the during-fault stage is necessary. However, the whole LVRT contains four different stages and the during-fault stage is only one among them. The transient synchronous stability of whole system should be determined by the initial state in the late post-fault stage and the attraction basin of its equilibrium point. The late post-fault stage is essential for stability and all four stages are important. Clearly treating the during-fault stage as the whole LVRT stages makes the nonlinear switched dynamics problem be greatly simplified and, certainly, is incomplete. In order to clarify this point, this paper analyzes the influence of existence (or nonexistence) of equilibrium point in the during-fault stage on the transient synchronous stability of permanent magnet synchronous generator grid-tied system. We can find that the existence of an equilibrium point in the during-fault stage is only a sufficient condition, rather than a necessary condition. The theoretical analysis is also verified in the hardware-in-the-loop experiment Therefore, a large number of previous studies and results on the transient synchronous stability of renewable grid-tied systems are incomplete and questionable.

关键词： Sufficient conditions Stability criteria Switches Voltage Power system stability Synchronous generators Permanent magnets Nonlinear dynamical systems Transient analysis Magnetic switching

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A Numerical Modeling Method for the Electric Field of Grading Rings of UHVAC Double Circuit Transmission Lines

A Numerical Modeling Method for the Electric Field of Gradin...

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International Conference on High Voltage engineering and Application, ICHVE

作者： Jing Liu Lilang Xiao Zhong Fu Hengxing He Electric Power Research Institute of State Grid Anhui Electric Power Co. Ltd. Hefei China State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China

ISBN: (数字)9781665407502

ISBN: (纸本)9781665407519

The use of grading rings is an important measure to control the surface electric field of insulators and fittings and thus corona discharges, and realize noise reduction of UHVAC transmission lines. However, due to the coexistence of the tower and insulator strings with the grading rings, the high complexity of simulation models leads to low quality of meshes, long meshing and computation time, and high memory usage, which hinders from fast optimization design of grading rings. Therefore, it is of need to device a numerical modeling method to reduce the complexity. In this paper, a numerical modeling method is proposed. Infinite element method is coupled with finite element method to reduce the modeling errors and the size of the computation domain. The connecting fittings of insulator strings are omitted and plates are used to model the trusses in order to further reduce the complexity. Moreover, The tower can be reduced to 1/4 size of the full model with the help of symmetry and computation experience. A meshing method based on domain decomposition is brought forward to speed up the grid generation. The results show that this modelling method can hugely decrease the complexity of the model and meshing time.

关键词： Computational modeling Poles and towers Fitting Insulators Transmission line measurements Numerical models Complexity theory

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Determination of Optimal Deformation Temperature and Deformation Mechanism of Thermal Effect in electromagnetic Forming Based on a New Multi-Sized Workpiece Method

SSRN

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SSRN 2022年

作者： Dong, Pengxin Wu, Jiawei Cao, Quanliang Chen, Qi Han, Xiaotao 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

electromagnetic forming (EMF) is a promising and rapidly developing high-speed forming technique of lightweight materials. However, there is currently a lack of accurate analysis of the thermal effect of eddy current induced in workpieces and the influence of deformation temperature on formability. In this work, a multi-sized workpiece method was proposed for electromagnetic ring expansion tests, and one-dimensional uniaxial high-speed tensile tests of 5083 Aluminum alloy (AA5083) rings with varying temperatures and the same velocity were conducted to analyze the influence of thermal effect on deformation behavior. It was found that the fracture strain first increased and then decreased with increasing temperature, and the maximum fracture strain reached 30.8%. It can be concluded that the optimal deformation temperature range of AA5083 in EMF was 161-199℃. The deformation texture and microstructure evolution were investigated using electron back-scattered diffraction. The results indicated that the temperature within the optimal deformation temperature range promoted the occurrence of dynamic recovery, which was the main reason for the enhanced ductility of AA5083 in EMF. The process was gradually replaced by dynamic recrystallization as the temperature increased, which decreased the ductility. Determination of optimal deformation temperature in EMF can further improve the formability of AA5083, and the study of the thermal effect caused by eddy current is instructive for the development and application of EMF. © 2022, The Authors. All rights reserved.

关键词： Tensile testing

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Modular Multilevel DC-DC Converter With Inherent Bipolar Operation Capability for Resilient Bipolar MVDC Grids

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CPSS Transactions on Power Electronics and Applications 2022年第1期7卷 37-48页

作者： Shanshan Zhao Yu Chen Shenghui Cui Jingxin Hu State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology China Department of Electrical and Computer Engineering Seoul National University Korea Institute for Power Generation and Storage Systems E. ON Energy Research Center RWTH Aachen University Germany

Bipolar medium-voltage dc (MVDC) distribution systems are of great interests nowadays due to its high availability and reliability. A bipolar MVDC grid can be established by the installation of power-balancers or directly by converters with inherent bipolar operation capability to avoid the extra cost and volume. Therefore, this paper proposes a modular multilevel dc-dc converter (MMDC) with inherent bipolar operation capability for the interconnection of bipolar MVDC grids and LVDC girds. Considering that the MMDC is normally only capable of operating with monopole MVDC distribution systems due to the symmetric structure and operation scheme, a center-tapped high-frequency interface transformer is employed on the MV side of the MMDC. Based on the concept of the flux dc-bias cancellation, a dedicated operation method is proposed, whereby the power flows of the two MVDC poles can be regulated independently with a simple control scheme, and no penalty of increased current rating is imposed on the semiconductor devices or the interface transformer compared to the conventional MMDC with monopole operation. Additionally, the MMDC can realize single-pole operation in case one pole is faulty and deliver at least 50% of the rated power capacity, which significantly enhance the reliability and availability of the power delivery. The validity of the proposed bipolar operation scheme of the MMDC has been verified by both simulations and experiments with a down-scale prototype.

关键词： Multilevel converters Semiconductor devices Prototypes DC-DC power converters Transformers Valves Power electronics

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A high-resistance unbalance fault identification method for high-proportion new energy access system

A high-resistance unbalance fault identification method for ...

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12th IET International Conference on Advances in Power System Control, Operation and Management (APSCOM 2022)

作者： D. Liu Y. Kang F. Xiao P. Xiong K. Cao J. Yan M. Wen Electric Power Research Institute State Grid Hubei Electric Power Co. Ltd. Wuhan China State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China

With the large number of power electronic power sources such as wind power, photovoltaic power, energy storage connected to the grid, the degree of electric power electronic system gets higher and higher. The fault characteristics of power electronic power supply and synchronous generator are obviously different. When unbalance fault occurs in transmission line especially in the case of high transition resistance, the zero-sequence current will be so small that the zero-sequence overcurrent protection of the line fails to operate, which brings great challenges to the traditional relay protection. In this paper we analyzed the adaptability of traditional zero-sequence protection in different working conditions under the background of typical high-proportion new energy grid engineering, and a high-sensitivity protection principle for unbalance faults of high-proportion new energy access system is proposed. On the basis of traditional zero-sequence overcurrent protection, the protection sensitivity is improved by combining zero-sequence voltage criteria. Considering that the zero-sequence current and zero-sequence voltage criteria may not be sensitive enough under high resistance fault conditions, and the limiting link of some systems will also reduce the fault current, the three-phase voltage specific unbalance is defined to reflect the characteristics of the fault. The voltage specific unbalance fits the voltage characteristics well when unbalance fault occurs in transmission line. In theory the results are very accurate when the fault is identified by the voltage specific unbalance. In order to avoid the influence of phasor extraction algorithm of power frequency, the proposed method uses modulus values of voltage and current instantaneous values in one power frequency period to replace the power frequency phasor. We have verified that the proposed method has a good ability to identify faults with high transition resistance especially when dealing with unbalance fau

关键词：

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Hot-band absorption of indocyanine green for advanced anti-stokes fluorescence bioimaging

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Light(Science & Applications) 2021年第10期10卷 1877-1888页

作者： Jing Zhou Xiaoxiao Fan Di Wu Jie Liu Yuhuang Zhang Zikang Ye Dingwei Xue Mubin He Liang Zhu Zhe Feng Andrey N.Kuzmin Wen Liu Paras N.Prasad Jun Qian State Key Laboratory of Modern Optical Instrumentations Centre for Optical and Electromagnetic ResearchCollege of Optical Science and EngineeringInternational Research Center for Advanced PhotonicsZhejiang UniversityHangzhou 310058China Sir Run-Run Shaw Hospital School of MedicineZhejiang UniversityHangzhou 310016China Key Laboratory of Flexible Electronics(KLOFE)Institute of Advanced Materials(IAM) Nanjing Tech University(Nanjing Tech)Nanjing 211800China Department of Chemistry Zhejiang UniversityHangzhou 310058China Interdisciplinary Institute of Neuroscience and Technology(ZIINT) College of Biomedical Engineering and Instrument ScienceZhejiang UniversityHangzhou 310027China Institute for Lasers Photonicsand BiophotonicsDepartment of ChemistryUniversity at BuffaloState University of New YorkBuffaloNY 14260USA Key Laboratory of Optical Information Detection and Display Technology of Zhejiang Zhejiang Normal UniversityJinhua 321004China

Bright anti-Stokes fluorescence(ASF)in the first near-infrared spectral region(NIR-I,800 nm–900 nm)under the excitation of a 915 nm continuous wave(CW)laser,is observed in Indocyanine Green(ICG),a dye approved by the Food and Drug Administration for clinical *** dependence of fluorescence intensity on excitation light power and temperature,together with fluorescence lifetime measurement,establish this ASF to be originated from absorption from a thermally excited vibrational level(hot-band absorption),as shown in our experiments,which is stronger than the upconversion fluorescence from widely-used rare-earth ion doped *** test the utility of this ASF NIR-I probe for advanced bioimaging,we successively apply it for biothermal sensing,cerebral blood vessel tomography and blood stream ***,in combination with L1057 nanoparticles,which absorb the ASF of ICG and emit beyond 1100 nm,these two probes generate multi-mode images in two fluorescent channels under the excitation of a single 915 nm CW *** channel is used to monitor two overlapping organs,urinary system&blood vessel of a live mouse,while the other shows urinary system *** in intraoperative real-time monitoring,such multi-mode imaging method can be beneficial for visual guiding in anatomy of the urinary system to avoid any accidental injury to the surrounding blood vessels during surgery.

关键词： absorption excitation anatomy

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Species dependence of the impurity injection induced poloidal flow and magnetic island rotation in a tokamak

arXiv

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arXiv 2023年

作者： Zeng, Shiyong Zhu, Ping Ren, Haijun Department of Engineering and Applied Physics University of Science and Technology of China Anhui Hefei230026 China International Joint Research Laboratory of Magnetic Confinement Fusion and Plasma Physics State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Hubei Wuhan430074 China Department of Engineering Physics University of Wisconsin-Madison MadisonWI53706 United States

Recent experiments have demonstrated the species dependence of the impurity poloidal drift direction along with the magnetic island rotation in the poloidal plane. Our resistive MHD simulations have reproduced such a dependence of the impurity poloidal flow, which is found mainly determined by a local plasmoid formation due to the impurity injection. The synchronized magnetic island rotation is dominantly driven by the electromagnetic torque produced by the impurity radiation primarily through the modification to the axisymmetric components of current density. © 2023, CC BY-NC-SA.

关键词： Magnetoplasma

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Message from Editors

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CES Transactions on Electrical Machines and Systems 2021年第4期5卷 271-272页

作者： Ronghai Qu Shoudao Huang Jianxin Shen Fengge Zhang Xiuhe Wang Metin Aydin Xiaoyong Zhu Yongxiang Xu Zhuoran Zhang Gaolin Wang Pinjia Zhang Hong Li Dawei Li academic degrees committee State and Province Joint Engineering Research Center of Novel Electrical Machines Center for Advanced Electrical Machines and Drives(CAEMD) State Key Laboratory of Advanced Electromagnetic Engineering and Technology Hunan University China Zhejiang University China Shenyang University of Technology China Shandong University China Kocaeli University Turkey Jiangsu University China Harbin Institute of Technology China Nanjing University of Aeronautics and Astronautics China Tsinghua University China Huazhong University of Science and Technology China

IN recent years,4th Industrial Revolution and Industry 4.0 have swept the world and deeply influenced the development of global industry *** movement arises wide attention to electric motor drive system which is playing an increasing important role in energy consumption transformation and environment *** this tremendous change in industry field,the concept of high-efficient,energy-saving and intelligent motor system has been *** one hand,motor system with advantages such as low vibration,low noise,weak magnetic interference,renewable utilization capacity,high-efficiency and high-reliability could promote the progress of major industries such as mining,renewable energy and cutting-edged equipment *** the other hand,the realization of intelligent and automated operations of motor drive system would help boosting the automation of industrial production.

关键词： operations realization boosting

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