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Computational Study on the Steady-state Impedance of Saturated-core Superconducting Fault Current Limiter

Physics Procedia 2016年 81卷 195-198页

作者： C. Zhang Y. Tang S. Liang L. Ren Z. Wang Y. Xu State Key Lab. of Advanced Electromagnetic Engineering and Technology (R&D Center of Applied Superconductivity Huazhong University of Science and Technology) 1037 Luoyu Road Wuhan 430074 P. R. China

This paper presents the electromagnetic analysis of a high voltage saturated-core superconducting fault current limiter (SCSFCL). The numerical analyses of a three-dimensional (3D) model is shown, and the specific parameters are given. The model focus on the steady-state impedance of the limiter when connected to the power grid. It analyzed the dependence of steady-state impedance on the AC coil current, and the relationship between oil gap and coil inductance. The results suggest that, adding oil gap between slice of silicon steel can reduce the core cross-section, restrain the ultraharmonic and decrease the steady-state impedance. As the core cross-section of AC limb decreased from 4344 cm 2 to 3983 cm 2 , the total harmonic distortion for voltage decreased from 2.4% to 1.8%, and the impedance decreased from 1.082 Ω to 1.069 Ω(I dc =400A,I ac =1296A).

关键词： Steady-state impedance Saturated-core superconducting fault current limiter Oil gap

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A Novel Routing Protocol for Pilot Protection Communication Channel Reconstruction Based on Wireless Sensor Network

A Novel Routing Protocol for Pilot Protection Communication ...

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IEEE Power and Energy Society General Meeting

作者： Xu Chen Ertao Lei Hang Yang Xianggen Yin Xin Yin State Key Lab. of Adv. Electromagnetic Eng. & Tech. School of Electrical and Electronic Engineering Huazhong University of Science and Technology School of Electrical and Electronic Engineering The University of Manchester

ISBN: (纸本)9781509041695

Natural disasters may wreak havoc on overhead transmission lines and cause communication outage of pilot protection. This paper proposes a communication channel reconstruction method based on wireless sensor network (WSN) modules of monitoring system. To meet the needs of pilot protection's time delay, a novel routing protocol for WSN is proposed based on GPS. It has three stages including route list establishment, route discovery and route maintenance, which assures the directional propagation of data packets in chain-type topology network. Practical experiments and simulations results indicates that the performance of the proposed routing protocol satisfies time delay of protection relaying as emergency communication channel, as well as guarantees the connectivity of network when some WSN nodes are damaged.

关键词： Communication Channel reconstruction Overhead transmission line Pilot protection Routing protocol WSN

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POLSAR LAND COVER CLASSIFICATION BASED on HIDDEN POLARIMETRIC FEATURES in ROTATION DOMAIN and SVM CLASSIFIER

POLSAR LAND COVER CLASSIFICATION BASED on HIDDEN POLARIMETRI...

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ISPRS Geospatial Week 2017

作者： Tao, Chen-Song Chen, Si-Wei Li, Yong-Zhen Xiao, Shun-Ping State Key Lab. of Complex Electromagnetic Environment Effects on Electronics and Information System School of Electronics Science and Engineering National University of Defense Technology Changsha410073 China

Land cover classification is an important application for polarimetric synthetic aperture radar (PolSAR) data utilization. Rollinvariant polarimetric features such as iH/Ani/α/Span are commonly adopted in PolSAR land cover classification. However, target orientation diversity effect makes PolSAR images understanding and interpretation difficult. Only using the roll-invariant polarimetric features may introduce ambiguity in the interpretation of targets' scattering mechanisms and limit the followed classification accuracy. To address this problem, this work firstly focuses on hidden polarimetric feature mining in the rotation domain along the radar line of sight using the recently reported uniform polarimetric matrix rotation theory and the visualization and characterization tool of polarimetric coherence pattern. The former rotates the acquired polarimetric matrix along the radar line of sight and fully describes the rotation characteristics of each entry of the matrix. Sets of new polarimetric features are derived to describe the hidden scattering information of the target in the rotation domain. The latter extends the traditional polarimetric coherence at a given rotation angle to the rotation domain for complete interpretation. A visualization and characterization tool is established to derive new polarimetric features for hidden information exploration. Then, a classification scheme is developed combing both the selected new hidden polarimetric features in rotation domain and the commonly used roll-invariant polarimetric features with a support vector machine (SVM) classifier. Comparison experiments based on AIRSAR and multi-temporal UAVSAR data demonstrate that compared with the conventional classification scheme which only uses the roll-invariant polarimetric features, the proposed classification scheme achieves both higher classification accuracy and better robustness. For AIRSAR data, the overall classification accuracy with the proposed classification schem

关键词： Land Cover Classification Polarimetric Feature Mining Polarimetric Synthetic Aperture Radar (PolSAR) Rotation Domain Support Vector Machine (SVM)

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Coupling effects of mechanical vibrations and thermal cycling on reliability of CCGA solder joints

Coupling effects of mechanical vibrations and thermal cyclin...

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作者： Ding, Ying Tian, Ruyu Wang, Xiuli Hang, Chunjin Yu, Fang Zhou, Ling Meng, Xiangang Tian, Yanhong Beijing Institute of Control Engineering Beijing100190 China State Key Lab. of Advanced Welding Production Technology Harbin Institute of Technology Harbin150001 China

The microstructures and crack propagation behavior of CCGA (ceramic column grid array) solder joints after sinusoidal vibration loading, random vibration loading, and thermal cycling test have been discussed in this study. The failure mechanism of solder joints was analyzed using an experimental method and finite element analysis. It was found that the failed solder joints mainly distributed at the peripheral area in the solder column arrays and the crack initiation was mainly caused by mechanical vibrations. The deformation of PCB (printed circuit board) introduced by mechanical vibrations brought the outermost solder columns in CCGA devices with significant stress concentration and induced the initiation of cracks. Furthermore, cracks propagated during the process of mechanical vibrations and thermal cycling. The cracks propagated rapidly and the solder joints finally failed. The structure of the PCB holder was improved to relieve the vibration response from the peripheral joints. No visible crack was found in the solder joints after the same mechanical vibrations and thermal cycling test. The reliability of solder joints have been greatly improved with the new PCB holder. © 2015 Elsevier Ltd. All rights reserved.

关键词： Vibrations (mechanical)

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Optimizing the balance of holes and electrons in inverted quantum dot light-emitting diodes by inserting electron transportation barrier layer

Optimizing the balance of holes and electrons in inverted qu...

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2015 SID International Symposium

作者： Jiang, Yibin Tang, Haoning Chen, Shuming Kwok, Hoi-Sing State Key Lab. on Advanced Displays and Optoelectronics Department of Electronic and Computer Engineering Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong Department of Electrical and Electronic Engineering South University of Science and Technology of China Shenzhen518055 China

In this study, the hole-electron balance of quantum dot light-emitting diodes (QDLED) was tuned in order to achieve efficiency enhancement This hole-electron balance optimization was realized by inserting thin barrier layer in the electron transportation layer. Although the current density was slightly sacrificed because of the electron blocking of the barrier layer, the charge balance was improved hence leading to 123% efficiency enhancement. © 2015 SID.

关键词： Semiconductor quantum dots

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Subset simulation for assessing structural reliability of multiple limit state functions 1

Subset simulation for assessing structural reliability of mu...

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1st ECCOMAS Thematic Conference on Uncertainty Quantification in Computational Sciences and engineering, UNCECOMP 2015

作者： Li, Hong-Shuang Ma, Yuan-Zhuo Cao, Zijun Key Lab. of Fundamental Science for National Defense-Advanced Design Technology of Flight Vehicles Nanjing University of Aeronautics and Astronautics Nanjing210016 China State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan University Wuhan430072 China

It remains a challenging task to calculate failure probabilities of multiple limit state functions (LSFs) using a single run of Subset Simulation in structural reliability analysis. To address this issue, this article presents a variant of standard Subset Simulation (SS), in which a unified intermediate event is designed to drive the simulation procedure progressively approaching multiple failure regions defined by all LSFs simultaneously. All failure probabilities of multiple LSFs are obtained by a single run of SS, which bypasses the sorting difficulty arising from the multiple LSFs. A representative example is used to demonstrate the efficiency, accuracy and robustness of the presented SS method.

关键词： Reliability analysis

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Stress Analysis and Bobbin Structure Optimization Design of a 35kV HTS-controllab.e Reactor

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Physics Procedia 2015年 65卷 278-281页

作者： Z. Wang L. Ren S. Shen M. Song Y. Zhang H. Liu L. Chen B. Yu N. Hu State Key Lab of Advanced Electromagnetic Engineering and Technology (R&D Center of Applied Superconductivity Huazhong University of Science and Technology) 1037 Luoyu Road Wuhan 430074 P. R. China

A 35kV high temperature superconducting controllab.e reactor (HTS-CR) is under development and the electromagnetic design has been completed. Due to the AC conditions, the thermal stress caused by AC losses can be so strong that the stress analysis should be carried out to verify that the maximum stress under different operating conditions is in appropriate range. In addition, Lorentz force of HTS windings will impact the bobbin structure of the HTS windings which will endanger the 35 kV HTS-CR. Stress analysis is important for the design of a mechanically stable structure. This paper provides the analysis of the bobbin structure and its result of optimization design considering the requirements of safety and cooling.

关键词： thermal stress analysis bobbin structure optimization design

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Research on DC voltage control strategies for typical four-terminal HVDC system

Research on DC voltage control strategies for typical four-t...

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2013 2nd International Conference on Sustainable Energy and Environmental engineering, ICSEEE 2013

作者： Wang, Kai Sun, Hai Shun Hua, Yu Liu, Yuan Lin, Wei Xing Li, Cheng Hao State Key Lab of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China

ISBN: (纸本)9783038350217

The continuous development of alternative energy has put forward higher requirement for electricity transmission. To cope with its fluctuation characteristics, high voltage direct current (HVDC) technology has received more attention. Voltage Source Converter (VSC) based Multi-Terminal High Voltage Direct Current (MTDC) represents the future trend of HVDC technology. This paper mainly focuses on the control strategies of a four-terminal VSC based MTDC power transmission system. The operation characteristic of the system was studied, and the proposed two control strategies, master-slave control strategy and DC voltage droop control strategy, were verified through simulations. The latter control strategy was proved to be performing well under various conditions, including converter station disconnection and faults at AC side of the converter. © (2014) Trans Tech Publications, Switzerland.

关键词： HVDC power transmission

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A Landmark Calibration Based IP Geolocation Approach

A Landmark Calibration Based IP Geolocation Approach

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International Conference on Availab.lity, Reliability and Security, ARES

作者： Jingning Chen Fenlin Liu Xiangyang Luo Fan Zhao Guang Zhu State Key Laboratory of Mathematical Engineering and Advanced Computing Zhengzhou Science and Technology Institute Zhengzhou Henan China State Key Lab. of Math. Eng. & Adv. Comput. Zhengzhou Sci. & Technol. Inst. Zhengzhou China

ISBN: (纸本)9781467365918

Aiming at the existing IP geolocation approaches does not consider the errors of landmarks, a new geolocation approach utilized landmark calibration is proposed in this paper. At first, by assigning a deviation, the location of the landmark with low reliability is regarded as a possible area, then geolocating the target IP can be converted into a constrained optimization problem, finding the location estimation of target IP by solving this problem, as well as the real deviation of landmark. The algorithm analysis and experimental results show that, when a landmark is not located in its claimed position, our geolocation approach can still give a location for the target IP.

关键词： Geology Delays IP networks Probes Optimization Calibration Propagation delay

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Vibration analysis of motor stator

Vibration analysis of motor stator

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2014 2nd International Conference on Manufacturing engineering and technology for Manufacturing Growth, METMG 2014

作者： Yan, Rong Ge Feng, Xu Zhu, Li Hua Yang, Qing Xin Province-Ministry Joint Key Lab. of Electromagnetic Field and Electrical Apparatus Reliability Hebei University of Technology Tianjin 300130 China Tianjin Key Laboratory of Advanced Technology of Electrical Engineering and Energy Tianjin Polytechnic University Tianjin 300387 China

ISBN: (纸本)9783038350354

Motor vibration is one of the main causes of the motor noise, and the vibration of the motor also brings great harm for the safe and reliable operation of the motor load system. The vibration and noise level is one of the essential elements in evaluating the electrical machine's quality. Accurate calculation of the stator natural frequencies and harmonic response of an electrical machine is essential to the prediction of the vibration. This paper takes the common Y series induction motors as the sample. The motor is a complex electromechanical coupling system, which includes stator and rotor. The finite element analysis is used to study on the stator modal shapes and natural frequencies of the induction motor. Then this paper calculates the electromagnetic force by using the finite element method, and gets the spectrum distribution of the radial electromagnetic force. Thus it provides a good method for the motor design by predicting natural frequency and optimizing the motor parameters to avoid resonance. All of them provide theory fundamental basis and technical support for reducing vibration and noise of the motor. © (2014) Trans Tech Publications, Switzerland.

关键词： Stators

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