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13th International Conference on the technology of Plasticity, ICTP 2021

作者： Li, Xiaoxiang Cao, Quanliang Lai, Zhipeng Lv, Yiliang Chen, Siyuan zhang, Yi 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

ISBN: (纸本)9783030753801

Magnetic pulse welding (MPW) is a high-speed joining process that uses pulse electromagnetic force to achieve welding. It is a clean welding process and it can be applied to dissimilar metals welding, which has a wide range of application prospects. However, this technology is currently mainly used for welding small-diameter thin-walled tubes. This is because the energy and electromagnetic force required for welding increase significantly as the tube size increases, which consequently places strict requirements on welding tools, including pulsed power and coil. To solve this issue, this work developed a two-dimensional (2D) axial-symmetry finite element model to optimize the tube welding process and designed a high-performance magnetic actuator with a high-strength coil to generate a strong enough electromagnetic force. On this basis, both numerical and experimental studies were performed to investigate the welding behavior of a 6061 aluminum alloy tube and a 304 stainless steel tube with 110 mm diameter and 3 mm thickness. Finally, a mechanical test and scanning electron microscope (SEM) were used to verify the joining quality, and the results show that the metallurgical bonding occurred between the two tubes. The presented optimization method and tool design could be of significance to the practical applications of MPW technology. © 2021, The Minerals, Metals & Materials Society.

关键词： Scanning electron microscopy

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Impact of Phase Locked Loop on Commutation Failure in LCC-HVDC 7

Impact of Phase Locked Loop on Commutation Failure in LCC-HV...

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7th International Conference on Electrical engineering, Control and Robotics, EECR 2021

作者： Tang, Peiyuan Yuan, Xiaoming Lu, Jun State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan430074 China China-EU Institute for Clean and Renewable Energy Huazhong University of Science and Technology Wuhan430074 China

Besides the DC faults, AC faults and faults in converter, the dynamic process of control system has its influence on commutation failure. As an important element in LCC-HVDC control system, PLL provides the reference phase of receiving end power system for valve control system. When there is a difference between the real phase of receiving end power system and the output from PLL, control system cannot adjust extinction angle accurately. In this paper, the function of PLL in HVDC control system and the characteristic of PLL's tracking process are analysed. Then the influence of the phase error caused by PLL's tracking process on the extinction angle is discussed. At last, a detailed LCC-HVDC model is used to prove the impact of PLL's dynamic process on commutation failure and test the influence of PLL with different parameters on commutation failure. © Published under licence by IOP Publishing Ltd.

关键词： Phase locked loops

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Comprehensive Performance Analysis for Transient Stability Assessment Machine Learning Models Activated by Features in Multi Temporal Sections 4

Comprehensive Performance Analysis for Transient Stability A...

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

作者： Ren, Junyu Chen, Jinfu Yang, Ruixiong Yang, Yexin Lin, Guihui Huazhong University of Science and Technology State Key Laboratory of Advanced Electromagnetic Engineering and Technology Wuhan China Zhuhai Power Supply Bureau Guangdong Power Grid Co. Ltd Zhuhai China

ISBN: (纸本)9781728171494

To meet the requirement of highly efficient transient stability assessment, we propose a concise but efficient feature set collected from multi temporal sections. Activated by the proposed feature set, some typical machine learning models are constructed and tested respectively on two benchmark systems of different scales. Comprehensive performance analysis of different machine learning models is implemented. The accuracy of most typical models based on the proposed feature set is greater than 98% both for two systems. Further, the interpretability performance is discussed. Rules of stability are very easy to acquire through data propagation in decision tree, showing that the decision tree has a strong interpretability, which is conducive to preventing the system from transient instability. © 2021 IEEE.

关键词： Decision trees

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SIMULATION AND DESIGN OF NEW DCCB TEST CIRCUIT 22

SIMULATION AND DESIGN OF NEW DCCB TEST CIRCUIT

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22nd International Symposium on High Voltage engineering, ISH 2021

作者： Li, Guixia Yuan, Zhao Chen, Lixue Deng, Chun Cai, Wei Qin, Yifan Key Laboratory of Pulsed Power Technology Huazhong University of Science and Technology Ministry of Education Hubei Province Wuhan430074 China State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical andElectronic Engineering Huazhong University of Science and Technology Hubei Province Wuhan430074 China

ISBN: (纸本)9781839536052

It is necessary to ensure the equivalence of the recovery voltage and its rising rate during the breaking test of mechanical HVDC circuit breaker. In this paper, a test circuit topology is proposed, which is composed of current source, commutation source and recovery voltage source. Both current source and commutation source are oscillation circuits composed of L and C, which use low-voltage capacitor to provide fault current and current zero-crossing point for DCCB. Recovery voltage source uses high-voltage capacitor, which mainly provides recovery voltage for DCCB. The design of the test circuit realizes the isolation of the recovery voltage source from the current source and the commutation source, ensuring that the recovery voltage can rise rapidly after the successful breaking of DCCB. The advantage of this topology is that the test circuit ensures the equivalence of di/dt and du/dt in the breaking test, and the consumption of capacitance is smaller and the cost is low. Finally, the effectiveness of the test circuit is verified by simulation software, Whe simulation results show that the test circuit can not only fully simulate the recovery voltage and its rising rate, but also ensure the equivalence of current process. © 2021 The Institution of engineering and technology.

关键词： Capacitance

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Method for Obtaining Leakage Inductance Based on Current Coupling in Unsaturated Zone 2

Method for Obtaining Leakage Inductance Based on Current Cou...

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2nd IEEE China International Youth Conference on Electrical engineering, CIYCEE 2021

作者： Cao, Wenbin Qi, Xuanwei Wang, Song Huang, Xiaoming Chen, Ming Yin, Xianggen State Grid Zhejiang Electrical Power Research Institute Hangzhou310014 China Huazhong University of Science and Technology State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Wuhan430074 China

ISBN: (纸本)9781665400640

The accurate leakage inductance value of the transformer primary and secondary side leakage inductance is the key to the theoretical and simulation analysis of the transformer inrush current transient characteristics. First, the transformer differential equation is deduced, and two calculation expressions for solving leakage inductance under system balance and unbalance are obtained. Aiming at the scenario where the circular current of the delta winding cannot be measured, a parameter acquisition method based on current coupling characteristics in unsaturated zone is proposed. This method takes advantage of the mutual coupling between the circular current of the delta winding and the non-saturated phase current of the primary side. First judge the unsaturated phase, and then use the opposite of the unsaturated phase current instead of the circulating current to solve the quasi-leakage inductance under the two expressions. The quasi-leakage inductance values in the unsaturated zone are almost equal, and the average value in this zone is used as the calculated value. Simulation data and field record data verify the effectiveness of the method. © 2021 IEEE.

关键词： Differential equations

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Study of the spectrum effect on the threshold of resonant magnetic perturbation penetration on J-TEXT

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Plasma Science and technology 2022年第12期24卷 16-25页

作者： Feiyue MAO Nengchao WANG Zhuo HUANG Zhengkang REN Song ZHOU Chengshuo SHEN Xiaoyi ZHANG Ying HE Qi ZHANG Ruo JIA Chuanxu ZHAO Yangbo LI Bo HU Da Li Abba Alhaji BALA Zhipeng CHEN Zhongyong CHEN Zhoujun YANG Yunfeng LIANG Yonghua DING Yuan PAN the J-TEXT Team International Joint Research Laboratory of Magnetic Confinement Fusion and Plasma Physics State Key Laboratory of Advanced Electromagnetic Engineering and TechnologySchool of Electrical and Electronic EngineeringHuazhong University of Science and TechnologyWuhan 430074People's Republic of China College of Computer Science South-Central Minzu UniversityWuhan 430074People's Republic of China Physics Department Federal University DutseDutse 720101JigawaNigeria Forschungszentrum Jülich GmbH Institut für Energie-und Klimaforschung-PlasmaphysikPartner of the Trilateral Euregio Cluster(TEC)Jülich 52425Germany Institute of Plasma Physics Chinese Academy of SciencesHefei 230031People's Republic of China

The spectrum effect on the penetration of resonant magnetic perturbation(RMP) is studied with upgraded in-vessel RMP coils on *** poloidal spectrum of the RMP field,especially the amplitudes of 2/1 and 3/1 components,can be varied by the phase difference between the upper and lower coil rows,ΔΦ=Φ_(top)-Φ_(bottom),where Φ_(top)and Φ_(bottom)are the toroidal phases of the n=1 field of each coil *** type of RMP penetration is found to be related to ΔΦ,including the RMP penetration of either 2/1 or 3/1 RMP and the successive penetrations of 3/1 RMP followed by the 2/1 *** cases with penetration of only one RMP component,the penetration thresholds measured by the corresponding resonant component are close for variousΔΦ.However,the 2/1 RMP penetration threshold is significantly reduced if the 3/1 locked island is formed in *** changes in the rotation profile due to 3/1 locked island formation could partially contribute to the reduction of the 2/1 thresholds.

关键词： tokamak error field resonant magnetic perturbation mode penetration spectrum analysis

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Reconfigurable Converter-Formed Soft Open Point- Assisted Dynamic Restoration for Distribution Systems with Cold-load Pickup

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IEEE Transactions on Sustainable Energy 2025年

作者： Yang, Xiaodong Li, Zihao Ding, Lijian Hu, Zhengli Fang, Hui Sun, Wei Wu, Qiuwei Wen, Jinyu Hefei University of Technology State Key Laboratory of High Efficiency and High Quality Electric Energy Conversion Hefei230009 China State Grid Anhui Ultra High Voltage Company Hefei230022 China Tsinghua University Tsinghua-Berkeley Shenzhen Institute Tsinghua Shenzhen International Graduate School Shenzhen518055 China Huazhong University of Science and Technology State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Wuhan430074 China

Improving the power supply resilience under extreme conditions is an important construction goal faced by modern distribution systems (DSs). In this paper, we develop a dynamic restoration framework for renewable DSs with cold-load pickup (CLPU), assisted by the reconfigurable converter-formed multi-terminal soft open point (R-SOP) to minimize the de-energized loads and renewables curtailment under extreme weather events. Traditional SOP often designed as symmetric capacity topology, which may limit the DS restoration quality by the converter capacity of symmetric SOPs. To address this, a dynamic network reconfiguration model of DSs is established that embedded with R-SOP, whose typical feature is the asymmetric converter capacity design while keeping the total port capacity unchanged compared with traditional SOP. On this basis, a multi-period distribution service restoration model is formulated integrating the converter reconfiguration of R-SOP, DS topology changes and coordinated actions of flexible resources to enhance the restoration level and improve the renewable energy utilization. Moreover, restoration strategies that ignore the CLPU phenomenon may face remarkable gap from the realistic system operating conditions. Accordingly, a frequency-constrained dynamic restoration model is proposed in a faster-timescale to respond to the CLPU and restore the DS in a reliable and adaptable manner. Numerical simulations on two modified IEEE test systems and an actual distribution system verify the effectiveness of the developed framework. © 2010-2012 IEEE.

关键词： Restoration

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Transient Process Analysis of Grid-Forming Converter Under Severe Voltage Sags With Different Q-V Controllers

Transient Process Analysis of Grid-Forming Converter Under S...

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Power and Electrical technology Conference (APET), Asia

作者： Chenyang Xie Xinchun Lin Huiqiang Sun Jiayan Zhang Juntian Wei Tianyu Fang Dan Liu Kezheng Jiang State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China State Grid Hubei Electric Power Co. LTD Electric Power Research Institute Wuhan China

Grid-forming VSCs based on Virtual Synchronous Generator (VSG) control strategy provide primary frequency regulation and voltage support for weak grids or VSC-dominated grids. Analyzing the transient stability of VSG-VSCs under large disturbances is useful for maintaining the security of the grid. However, different control strategies in grid-forming converters will cause the VSC to operate at different transient processes, and this topic is little studied. In this paper, the impacts of Q-V controller on transient process under severe voltage drops are elaborately studied. In particular, it is shown that the change of controller will change the transient process of the VSC, which impacts the transient stability of VSG-VSCs. Simulations verify the validity of the transient stability analysis.

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Roles of non-axisymmetric perturbations in free drift vertical displacement events on EAST

arXiv

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arXiv 2024年

作者： Li, Haolong Zhu, Ping Li, Hang Wu, Muquan Zhu, Xiang Luo, Jingting College of Physics and Optoelectronic Engineering Shenzhen University Shenzhen518060 China 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 Advanced Energy Research Center Shenzhen University Shenzhen518060 China

The safe operation of most tokamaks, especially the largen sized ones, rely on the feedback control of the vertical displacement events (VDEs). However, most these feedback control systems are based on the axisymmetric VDE models. In this work, we use NIMROD simulations to study the roles of non-axisymmetric perturbations in free drift vertical displacement events on EAST. The high-n modes in non-axisymmetric VDE grow first, which drive the formation of high-n magnetic island chains. Subsequently, the magnetic island chains grow and overlap with each other, leading to the destruction of the magnetic flux surface, which induces a minor disruption and accelerates the start of the following major disruption. The magnetic island and the stochastic magnetic field allow the toroidally asymmetric poloidal plasma current to jet towards the hoop force direction, forming the finger and filamentary structures. Such a plasma current asymmetry strongly depends on the anisotropy in thermal transport coefficients. Copyright © 2024, The Authors. All rights reserved.

关键词： Feedback control

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Transient Stability Assessment of Power Systems Based on Semi-Supervised Active Learning

Transient Stability Assessment of Power Systems Based on Sem...

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IEEE Asia Power and Energy engineering Conference (APEEC)

作者： Yuanzhuo Sheng Defu Cai Erxi Wang Jinfu Chen State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China Electric Power Research Institute State Grid Hubei Electric Power Co. Ltd Wuhan China

Machine learning method has a broad application prospect in the power system transient stability assessment field. Still, there is a problem that it needs to use a large number of labeled samples to train the model, and time domain simulation takes a long time. Combining the semi-supervised learning method with the active learning method, a power system transient stability assessment method based on semi-supervised active learning is proposed to solve the problem. A clustering algorithm is used to select the initial samples, ensuring the initial model’s performance. Semi-supervised learning makes full use of the unlabeled sample pool and accelerate overall learning process. The simulation results on IEEE 10-machine, 39-bus system show that this method requires fewer labeled samples than traditional active learning methods, further improving assessment efficiency.

关键词： Training Electrical engineering Simulation Transfer learning Clustering algorithms Power system stability Semisupervised learning

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