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Asia-Pacific International Conference on Lightning (APL)

作者： Xiankang Wang Xiaopeng Liu Zijian Li Yao Yao Junjia He State Grid Hubei Electric Power Co. Ltd. Electric Power Research Institute Wuhan China State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China

A long-standing but fundamental question in lightning and laboratory spark researches is how the positive and negative leader attach with each other. Here we report optical images and discharge current waveforms during the breakthrough phase of attachment process in positive laboratory sparks. The space leader inside the common streamer zone was observed for the first time. The recorded electric current as well as the calculated impedance of the common streamer zone reveal the evolution process of the space leader. Finally, a new scenario including three subsequent stages is proposed for leaders’ attachment process.

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Research on Protection Tripping Scheme of Multiple Criteria with High Reliability for HV Transmission Lines 4

Research on Protection Tripping Scheme of Multiple Criteria ...

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

作者： Jin, Neng Li, Gan Liang, Zhikai Wu, Gang Fang, Yanchen Lin, Xiangning Planning Design and Research Co. Ltd Changjiang Institute of Survey Hubei China Huazhong University of Science and Technology State Key Laboratory of Advanced Electromagnetic Engineering and Technology Hubei China

ISBN: (纸本)9781728171494

The abnormities occurring at any part of sampling process may cause the maloperation of dual-configured protection systems in smart substations. To cope with this problem, multiple differential protection criteria are formed, which use the currents acquired from the lines that connect to the busbars connecting to the double ends of the protected line. All the acquired information is shared in the substation area protection platform. Then, a novel protection tripping scheme of multiple criteria for high voltage (HV) transmission line is proposed. Theoretical analysis and simulation results indicate that compared with the existing 1-out-of-2 tripping scheme, the proposed protection tripping scheme is immune to the abnormities of current transformer (CT) such as saturation, interference and disconnection, which can effectively enhance the reliability of line protection. © 2021 IEEE.

关键词： Electric instrument transformers

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基于纤维增强和磁场诱导构建坚韧、抗疲劳各向异性水凝胶及其性能研究

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Science China Materials 2023年第12期66卷 4841-4852页

作者：陈琴陈凯武盟张欣悦冯海燕冯存傲王大刚李晓伟张德坤曾宏波 School of Chemical Engineering and Technology School of Materials Science and PhysicsSchool of Mechatronic EngineeringChina University of Mining and TechnologyXuzhou 221116China State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000China State Key Laboratory of Tribology in Advanced Equipment Tsinghua UniversityBeijing 100084China Department of Chemical and Materials Engineering University of AlbertaEdmontonAlberta T6G 1H9Canada

生物组织(如肌腱、软骨等)不仅具有优异的强度、模量和韧性,而且具有长期稳定性,可承受数百万次高应力循环而不断裂,其疲劳阈值超过1000 J m^(−2).相比之下,尽管合成水凝胶在强度、模量、韧性和其他性能方面与天然软组织相当,但这些增... 详细信息

生物组织(如肌腱、软骨等)不仅具有优异的强度、模量和韧性,而且具有长期稳定性,可承受数百万次高应力循环而不断裂,其疲劳阈值超过1000 J m^(−2).相比之下,尽管合成水凝胶在强度、模量、韧性和其他性能方面与天然软组织相当,但这些增韧水凝胶仍然会在反复循环载荷下遭受疲劳断裂,其疲劳阈值通常低于100 J m^(−2).在本工作中,我们报道了一种简单的策略,用于开发韧性和抗疲劳的各向异性水凝胶,其疲劳阈值超过常规水凝胶的100倍.各向异性水凝胶通过两步工艺合成,包括磁场定向工艺形成优先排列的PDA-Fe_(3)O_(4)-CF纤维结构,以及冷冻解冻-退火工艺处理.优先排列纤维结构和高结晶度的协同作用使各向异性水凝胶具有超高的强度和韧性、优异的摩擦学性能和非凡的抗疲劳性能.各向异性水凝胶的抗拉强度、抗压强度和疲劳阈值分别高达11.82±0.85 MPa、5.95±0.35 MPa和1845 J m^(−2),显著高于大多数生物凝胶和合成水凝胶.因此,本研究为制造性能优异的软材料提供了一种可行的方法,拓展了软质材料在承重材料(如人工软组织)、软机器人、柔性电子等领域的应用.

关键词： anisotropic hydrogels PDA-Fe_(3)O_(4)-CF fatigueresistant magnetic field induction

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Performance Evaluation of Novel Segmental Rotor Switch Reluctance Motor with Magnetic Bridge

Performance Evaluation of Novel Segmental Rotor Switch Reluc...

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International Conference on Electrical Machines and Systems (ICEMS)

作者： Sinian Su Jianbo Sun Shuixi Zhang Honggang Wang Shuanghong Wang Yang Yang Ziqi Zhao Ronghai Qu Huangyuan Wu State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China State Grid Henan Power Company Luohe Power Supply Company Henan Tailong Power EquipmentCo. LTD Cyan Exploring Power Technology Wuxi Co Wuxi China

ISBN: (数字)9784886864406

ISBN: (纸本)9798350379105

The segmented rotor switched reluctance motor (SSRM) has the characteristics of a short magnetic circuit, high torque density, low wind resistance, and high efficiency compared to the traditional switched reluctance motor (SRM). However, the complex manufacturing process of SSRM acts against their use. In this paper, a new type of segmented rotor switched reluctance motor with a rotor magnetic bridge (SSRMMB) is proposed, which connects the rotor blocks into a whole. The static inductance characteristics of the SSRM and SSRMMB are investigated through electromagnetic simulation. The performance of the two motors is then comparatively analyzed under angle position control (APC) and unipolar sinusoidal excitation control (USC), with a further analysis of the reasons for any differences. The simulation results show that there is little difference in the performance of the two motors during normal operation.

关键词： Bridges Performance evaluation Inductance Torque Rotors Bridge circuits Switches Switched reluctance motors Motors Magnetic circuits

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Recent Progress of Electrode Materials for Flexible Perovskite Solar Cells

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Nano-Micro Letters 2022年第7期14卷 179-208页

作者： Yumeng Xu Zhenhua Lin Wei Wei Yue Hao Shengzhong Liu Jianyong Ouyang Jingjing Chang State Key Discipline Laboratory of Wide Band Gap Semiconductor Technology School of MicroelectronicsXidian University2 South Taibai RoadXi’an 710071People’s Republic of China Advanced Interdisciplinary Research Center for Flexible Electronics Xidian University2 South Taibai RoadXi’an 710071People’s Republic of China Key Laboratory of Applied Surface and Colloid Chemistry Ministry of EducationInstitute for Advanced Energy MaterialsSchool of Materials Science and EngineeringShaanxi Normal UniversityXi’an 710119People’s Republic of China Department of Materials Science and Engineering National University of Singapore7 Engineering Drive 1Singapore 117574Singapore

Flexible perovskite solar cells(FPSCs) have attracted enormous interest in wearable and portable electronics due to their high power-per-weight and low cost. Flexible and efficient perovskite solar cells require the development of flexible electrodes compatible with the optoelectronic properties of perovskite. In this review, the recent progress of flexible electrodes used in FPSCs is comprehensively reviewed. The major features of flexible transparent electrodes, including transparent conductive oxides, conductive polymer, carbon nanomaterials and nanostructured metallic materials are systematically compared. And the corresponding modification strategies and device performance are summarized. Moreover, flexible opaque electrodes including metal films, opaque carbon materials and metal foils are critically assessed. Finally, the development directions and difficulties of flexible electrodes are given.

关键词： Flexible electrode Flexible perovskite solar cell Carbon nanomaterials Metallic nanostructures Conductive oxide

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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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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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Substation-area Backup Protection Scheme for the Failure of 10kV Line Protection Device

Substation-area Backup Protection Scheme for the Failure of ...

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2021 International Conference on Energy, Power and Electrical engineering, EPEE 2021

作者： Wang, Yuxue Liu, Wei Jiao, Shaolin Fang, Zeya Li, Yiquan Wen, Minghao Power Dispatching Control Center of Guangdong Power Grid Guangzhou510600 China State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan430074 China

The research on wide-area backup protection for high-voltage transmission lines has made certain progress in recent years, but there are few reports published on substation-area backup protection for low-voltage 10kV transmission lines. Based on the characteristics of shared information in intelligent substation, a substation-area backup protection scheme to deal with the failure of 10kV line protection device is proposed in this paper. This scheme uses the device self-test information and heartbeat mechanism to monitor the operation status of 10kV line protection devices;to realize the substation-area backup protection for the 10kV transmission lines when any line protection device fails, the protection criterion is constructed by the action results of power directional elements of transformer protections and other 10kV line protections. The proposed scheme can greatly improve the speed of the fault isolation and has low requirements for data demand and synchronization. PSCAD simulation results show that the proposed method is with high correctness and feasibility. © 2021 Institute of Physics Publishing. All rights reserved.

关键词： Electric lines

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Resilient Market Bidding Strategy for Mobile Energy Storage System Considering Transfer Uncertainty

SSRN

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SSRN 2024年

作者： Wang, Kaijie Wei, Fanrong Lin, Xiangning Li, Zhengtian Ma, Yuncong Dawoud, Samir Mohammed State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Hubei Wuhan430074 China Xiangyang Power Supply Company State Grid Hubei Electric Power Company Hubei Xiangyang441000 China Department of Electrical Power and Machines Engineering Faculty of Engineering Tanta University Tanta31512 Egypt

The participation of Mobile Energy Storage Systems (MESS) in the electricity market can not only increase its own profit but also alleviate power transmission congestion and increase market clearing balance. However, relevant market trading strategies have yet to be explored. Accordingly, this paper proposes a resilient market bidding strategy for MESS considering the operation of transportation network. Firstly, this paper proposes a joint optimization framework of energy and transportation systems. In this framework, the upper layer is to make decisions on the space-time distribution and bidding strategy of MESS, and the lower layers is designed for the equilibrium of the transportation network and electricity market clearing. Subsequently, for the newly introduced transportation layer, this paper proposes a Logit-type Robust Stochastic User Equilibrium (LRSUE) to calculate the uncertain transfer time of MESS in the transportation network. Further, based on strong duality theory and Karush-Kuhn-Tucker Conditions (KKT) conditions, the two-layer model can achieve an efficient solution. Finally, IEEE14-bus system and a typical traffic network were provided to validate the proposed methods, demonstrating that MESS increase its revenue, alleviate power transmission congestion, and increase the electricity market clearing balance. © 2024, The Authors. All rights reserved.

关键词： Power markets

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Adaptive Anomaly Detection Disruption Prediction Starting from First Discharge on Tokamak

arXiv

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arXiv 2024年

作者： Ai, X.K. Zheng, W. Zhang, M. Ding, Y.H. Chen, D.L. Chen, Z.Y. Guo, B.H. Shen, C.S. Wang, N.C. Yang, Z.J. Chen, Z.P. Pan, Y. Shen, B. Xiao, B.J. 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 Institute of Plasma Physics Chinese Academy of Sciences Hefei230031 China

Plasma disruption presents a significant challenge in tokamak fusion, especially in large-size devices like ITER, where it can cause severe damage and economic losses. Current disruption predictors mainly rely on data-driven methods, requiring extensive discharge data for training. However, future tokamaks require disruption prediction from the first shot, posing challenges of data scarcity and difficulty in training and hyperparameter selection during the early operation period. In this period disruption prediction also aims to support safe exploration of operation range and accumulate necessary data to develop advanced prediction models. Thus, predictors must adapt to evolving plasma environments during this exploration phase. To address these challenges, this study proposes a cross-tokamak adaptive deployment method based on the Enhanced Convolutional Autoencoder Anomaly Detection (E-CAAD) predictor. This method enables disruption prediction from the first discharge of new devices, addressing the challenges of cross-tokamak deployment of data-driven disruption predictors. Experimental results demonstrate the ability of the E-CAAD model trained on existing devices to effectively differentiate between disruption precursors and non-disruption samples on new devices, proving the feasibility of model cross-device transfer. Building upon this, adaptive learning from scratch and threshold adaptive adjustment strategies are proposed to achieve model cross-device transfer. The adaptive learning from scratch strategy enables the predictor to fully use scarce data during the early operation of the new device while rapidly adapting to changes in the operation environment. The warning threshold adaptive adjustment strategy addresses the challenge of selecting warning thresholds on new devices where the validation set is lacking, ensuring that the warning thresholds adapt to changes in the operation environment. Finally, experiments transferring the model from J-TEXT to EAST e

关键词： Anomaly detection

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