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SSRN 2023年

作者： Yang, Jingmin Gao, Li Wang, Yajun Rao, Bo Yang, Chengyu Chen, Zhipeng 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 Wuhan430074 China Guangzhou Power Supply Bureau Guangdong Power Grid Co. Ltd China

A multi-chord interferometer system is established on the HUST Field Reversed Configuration (HFRC). Configured as a Mach-Zehnder heterodyne interferometer with seven probe chords distributed in the HFRC middle plane, the system is designed to estimate the integral density within the collisional-merging and compression region of the device. With a spatial resolution of 2cm and a radial coverage range from -7 cm to 31 cm, it provides a density measurement range of 1×1019~1×1020 m-2 . A 10.6μm CO2 laser serves as the laser source, while an acoustic-optic modulator (AOM) generates a modulation frequency of 40 MHz corresponding to a temporal resolution of 25 ns. To reduce frequency drift and vibration noise, a laser interferometric reference chord and a fitting vibration compensation method are implemented. Preliminary experimental results show that the phase resolution within has been achieved, which corresponds to a minimum measurable density of ~2×1018 m-2 . Beyond the density profile measurements, the multi-chord interferometer system plays a pivotal role in observing instabilities of FRC plasmas. © 2023, The Authors. All rights reserved.

关键词： Interferometers

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Fault Location Method for Distributed Power Distribution Network Based on Hybrid Strategy Genetic Algorithm

Fault Location Method for Distributed Power Distribution Net...

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2020 Asia Energy and Electrical engineering Symposium, AEEES 2020

作者： Yong, Zhang Shanming, Wan Jianghua, Zhou Huazhong University of Science and Technology State Key Laboratory of Advanced Electromagnetic Engineering and Technology Wuhan430074 China

ISBN: (纸本)9781728167824

Since the access of the distributed power supply of distribution networks changes the structure of original networks and the direction of the power flow, so that the correctness of the relay protection action is reduced. In order to accurately locate the fault when fault occurs, a new positioning method based on hybrid strategy genetic algorithm is proposed. The entire distribution network is segmented according to the distribution of the multifunctional micro phasor measurement unit. Then the line transmission equation and the goodness function model are established, and the known network structure is fault-located by the improved genetic algorithm. The proposed method by using the global information to comprehensively consider the fault condition, avoids the misjudgment caused by the special situation. Considering the influence of the grounding resistance, the accuracy of fault location is greatly improved, and the resistance of the grounding resistor is solved for the first time. Theoretical analysis and a larger number of simulation results show that this method has high precision and stability. © 2020 IEEE.

关键词： Genetic algorithms

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State Feedback Control of Brushless Doubly-Fed Wind Power Generator Under Symmetrical Drop of Grid Voltage

SSRN

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SSRN 2023年

作者： Nie, Pengcheng Yu, Hongru Hong, Jing State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan430074 China Anhui Jianzhu University Hefei230000 China Sany Heavy Industry Co. Ltd. Changsha410000 China

In the dynamics of grid-connected operation of brushless doubly fed generators (BDFG), when the grid voltage dips, it is equivalent to adding a reverse voltage source at the parallel node suddenly. By deriving the expressions of the transient current of power winding (PW), control winding (CW), and rotor winding (RW) of BDFG in the complex frequency domain under natural state, it is concluded that the overshoot and oscillation time are affected by the generator parameters, the drop degree and phase of the grid voltage, and the rotor speed. Then, a state feedback control strategy is proposed, and a state model with PW, CW, and RW current as state variables is constructed. State variables are added to the input through the feedback matrix, the parameters of system matrix of the generator are changed, that is, the equivalent parameters of the generator are changed. The pole distribution diagram shows that under the state feedback strategy, the poles shift significantly to the left compared with the poles with traditional control, so it could make the system accelerate convergence, reduce the amplitude. Finally, the feasibility of the state feedback algorithm was verified using tests on an experimental platform. © 2023, The Authors. All rights reserved.

关键词： State feedback

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Quantum dots assisted in vivo two-photon microscopy with NIR-Ⅱemission

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Photonics Research 2022年第1期10卷 189-196页

作者： HUWEI NI YALUN WANG TAO TANG WENBIN YU DONGYU LI MUBIN HE RUNZE CHEN MINGXI ZHANG 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 SIEE(Sussex AI Institute) Zhejiang Gongshang UniversityHangzhou 310018China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070China Britton Chance Center for Biomedical Photonics Wuhan National Laboratory for OptoelectronicsHuazhong University of Science and TechnologyWuhan 430074China

With the advantages of high resolution and deep penetration depth,two-photon excited NIR-Ⅱ(900–1880 nm)fluorescence(2PF)microscopic bioimaging is ***,due to the lack of imaging systems and suitable probes,few such works,to our best knowledge,were demonstrated utilizing NIR-II excitation and NIR-Ⅱfluorescence ***,we used aqueously dispersible Pb S/Cd S quantum dots with bright NIR-II fluorescence as the contrast *** the excitation of a 1550 nm femtosecond(fs)laser,they emitted bright 2 PF in the NIR-Ⅱ***,a 2PF lifetime imaging microscopic(2PFLIM)system was implemented,and in vivo 2PFLIM images of mouse brain blood vessels were obtained for the first time to our best *** improve imaging speed,an in vivo two-photon fluorescence microscopy(2 PFM)system based on an In Ga As camera was implemented,and in vivo 2PFM images of QDs-stained mouse brain blood vessels were obtained.

关键词： excitation photon system

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Observation of Stem Branching in Long laboratory Sparks under Positive Switching Impulses

Observation of Stem Branching in Long Laboratory Sparks unde...

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2022 IEEE International Conference on High Voltage engineering and Applications, ICHVE 2022

作者： Liu, Xiaopeng Zhao, Xiangen Liao, Minchuan Liao, Yuqin Du, Yaping He, Junjia State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China Hong Kong Polytechnic University Department of Building Environment and Energy Engineering Hong Kong Hong Kong State Key Laboratory of Hvdc Electric Power Research Institute Csg Guangzhou China Maintenance and Test Ctr. of Extra High Voltage Pwr. Transmiss. Company of China Southern Power Grid Guangzhou China

ISBN: (数字)9781665407502

ISBN: (纸本)9781665407502

The phenomenon of leader branching in natural lightning and laboratory sparks has raised broad and long-standing concerns, while the physical mechanism has not been fully understood. Recently, a stem-driven mechanism has been proposed to explain the leader branching behavior. To this end, this paper mainly studies the stem branching phenomenon to explain the branching behavior of positive leaders. Streamer stems were visualized with both the schlieren photography and the direct photography. The corresponding current pulses were recorded synchronously. Based on the experimental results, the relationship between the second streamer stem structure and its corresponding current waveform is classified into three types. Besides, the elongation of the main and secondary branches and the charge required per unit for them are calculated. The charge per unit required to elongate for the main and secondary branches is 7.09 μC/m and 28.32 μC/m, respectively. These findings provide new insights into the branching behavior of the stem and the direction variation during the leader propagation process. © 2022 IEEE.

关键词： Photography

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Structure design of pulse power module based on vacuum polarity effect 1

Structure design of pulse power module based on vacuum polar...

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1st IEEE China International Youth Conference on Electrical engineering, CIYCEE 2020

作者： Siyu, Wang Ling, Dai Yanling, Weng Fuchuang, Lin Huazhong University of Science and Technology State Key Laboratory of Advanced Electromagnetic Engineering and Technology Wuhan430074 China

ISBN: (纸本)9781728196596

The voltage polarity and structural design of the pulsed power module are the key factors affecting the dielectric strength. In a vacuum environment, the voltage polarity of the pulse power module is different, and the flashover voltage is also different, and there is a significant polarity effect. After analysis, the cathode field emission and the gas desorption of the insulating material are the main reasons for the surface breakdown voltage of the negative-point positive plate electrode being lower than the surface breakdown voltage of the positive-point negative plate. To verify this conclusion, a needle-plate electrode vacuum breakdown experiment was designed. The internal electric field distribution of the pulse power module was calculated by COMSOL software. At the same time, the module vacuum breakdown experiment was designed. The simulation and experimental results show that the vacuum breakdown voltage of the pulse power supply module can be effectively improved by positively charging the electrode with smaller curvature radius and increasing the curvature radius of the inner electrode of the power supply module. © 2020 IEEE.

关键词： Plates (structural components)

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A High Efficiency Hybrid Modular Multilevel Converter with a SiC Device-Based External Shaping Module

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IEEE Transactions on Power Electronics 2025年

作者： Ren, Peng Guo, Qi Hou, Yuchao Tu, Chunming Zhu, Donghai Sun, Kai Wang, Lei Xiao, Fan Hunan University College of Electrical and Information Engineering Changsha410082 China Tsinghua Shenzhen International Graduate School Shenzhen518000 China Huazhong University of Science and Technology State Key Laboratory of Advanced Electromagnetic Technology School of Electrical and Electronic Engineering Wuhan430074 China Tsinghua University State Key Lab of Power Systems Department of Electrical Engineering Beijing100084 China

In order to improve the waveform quality and efficiency of medium voltage modular multilevel converter (MMC), a hybrid MMC (HMMC) topology with an external shaping module is proposed. Each arm of the HMMC consists of N half-bridge submodules (HSMs) based on Si IGBT, while a full-bridge submodule (FSM) based on SiC MOSFET on the ac side. Furthermore, a 2N+1 level hybrid modulation strategy is proposed for this topology. The HSMs operate in the low-frequency state to output the staircase wave voltage, while the FSM operates in the high-frequency state to reduce the harmonics of the output voltage. It makes full use of the advantages of low on-state loss of Si devices and low switching loss of SiC devices. Additionally, the energy fluctuation of the HMMC submodules is analyzed in detail, and a voltage balancing scheme is proposed. In the end, the feasibility and effectiveness of the proposed topology and modulation method are validated by simulation and experimental studies on a single-phase HMMC. Moreover, the comparison of cost and loss between HMMC and existing MMCs proves that the proposed HMMC can better balance the device cost and operating loss. © 1986-2012 IEEE.

关键词： Silicon carbide

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A Novel Station-Wide Area Information Interaction Intelligent System

A Novel Station-Wide Area Information Interaction Intelligen...

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7th IEEE International Conference on Industrial engineering and Applications, ICIEA 2020

作者： Jin, Neng Lin, Xiang-Ning Li, Zheng-Tian Rong, Zi-Rui Zhang, Pei-Fu State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wu Han China

ISBN: (纸本)9781728167855

Wide area differential protection (WADP) is verified to have many advantages over local protection. However, it is rarely applied in the field due to its high requirement to the communication network bandwidth. To deal with this problem, on the basis of the service oriented architecture of the internet cloud computing model, a novel station-wide area information interaction intelligent system is proposed. Within the system, the station-area intelligent unit with signal processing ability is taken as terminal and initiates request, while the wide area protection layer is taken as cloud platform and provides fast response service for WADP. The simulation results verify that the proposed intelligent system has high adaptability to the low-quality communication networks with limited bandwidth. © 2020 IEEE.

关键词： Wide area networks

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Effects of zero and reversed magnetic shear on resistive wall modes in a limiter tokamak plasma

arXiv

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arXiv 2024年

作者： Wan, Sui Zhu, Ping Li, Haolong Han, Rui State Key Laboratory of Advanced Electromagnetic Technology International Joint Research Laboratory of Magnetic Confinement Fusion and Plasma Physics School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan430074 China Department of Nuclear Engineering and Engineering Physics University of Wisconsin-Madison MadisonWI53706 United States College of Physics and Optoelectronic Engineering Shenzhen University Shenzhen518060 China CAS Key Laboratory of Geospace Environment Department of Engineering and Applied Physics University of Science and Technology of China Hefei230026 China

advanced tokamak scenarios often feature equilibriums with zero and reversed magnetic shear. To isolate and investigate their impacts on the resistive wall mode (RWM) instability analytically, we construct a series of cylindrical limiter equilibriums with reversed magnetic shear in the core and zero magnetic shear towards plasma edge, as a prototype of the configurations in advanced tokamak scenarios. Uniform plasma pressure is assumed, so that we can focus our analysis on the current-driven RWMs. Based on the reduced ideal MHD equations, analytical solutions for the n = 1 resistive wall mode are obtained, which indicate that increasing the reversal of magnetic shear in the core region enhances the RWM instability, whereas the widened region of zero shear near edge leads to lower growth rate of RWM, except when the q value with zero magnetic shear approaches rational values. On the other hand, enhanced positive shear at plasma edge is found to be stabilizing on RWM. NIMROD calculation results confirm these analytical findings. Copyright © 2024, The Authors. All rights reserved.

关键词： Magnetoplasma

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Vibration suppression of magnetic bearing system based on active disturbance rejection control with generalized integrator extend state observer 1

Vibration suppression of magnetic bearing system based on ac...

引用

1st IEEE China International Youth Conference on Electrical engineering, CIYCEE 2020

作者： Sun, Hongbo Jiang, Dong Huazhong University of Science and Technology State Key Laboratory of Advanced Electromagnetic Engineering and Technology Wuhan430074 China

ISBN: (纸本)9781728196596

Vibration is a common problem in rotating machine. Active Magnetic Bearing (AMB) produces controllable magnetic force to levitate rotor and the control algorithm contributes to reduce vibration. This paper proposes a vibration suppression strategy based on active disturbance rejection control (ADRC). ADRC applies extend state observer (ESO) to estimate generalized disturbance. However, in AMB system, disturbance is mainly caused by centrifugal force, whose frequency is rotating frequency. For sinusoidal disturbance, ESO cannot estimate it absolutely. To estimate sinusoidal disturbance in AMB system, generalized integrator ESO (GI-ESO) is applied in ADRC. The resonant frequency of GI is set as rotating frequency. Transfer function of error of GI-ESO is analyzed and notch feature at resonant frequency is displayed. The transfer function of third-order of ADRC applied GI-ESO is obtained. Stability of proposed vibration suppressing strategy is analyzed by root locus. Results of simulations show better effect for sinusoidal disturbance estimation of GI-ESO. After applying ADRC based on GI-ESO, vibration of displacement in AMB system is reduced effectively, which shows the effectiveness of proposed vibration suppressing strategy. © 2020 IEEE.

关键词： Natural frequencies

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