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ac loss and contact resistance in highly flexible rebco cable for fusion applications

Superconductivity 2022年第2期2卷 39-45页

作者： Zichuan Guo Jinggang Qin R.Lubkemann Keyang Wang Huan Jin Guanyu Xiao Jiangang Li Chao Zhou Arend Nijhuis University of Twente Faculty of Science&Technology7522 NB EnschedeThe Netherlands University of Science and Technology of China HefeiAnhui 230026People’s Republic of China Institute of Plasma Physics Chinese Academy of SciencesHefeiAnhui 230031People’s Republic of China Department of Mechanics and Engineering Science Lanzhou UniversityLanzhouGansu 730000People's Republic of China

High Temperature Superconductor(HTS)materials can operate at higher magnetic fields up to 20 T with high critical current and higher operating temperature,compared to low temperature superconductors(LTS).A Highly Flexible REBCO Cable(HFRC)is introduced at the Institute of Plasma Physics,Chinese academy of Sciences(ASIPP);a cabling method that is suitable for REBCO HTS tape having anisotropic material properties in its thin REBCO *** type of HTS superconducting cable shows high potential for applications in nuclear *** alternating currents and magnetic fields in tokamak type of fusion magnets,cause ac power losses in such cables,which can provoke instability of the conductor by induced currents and increase the *** a first step in characterizing the electromagnetic(EM)performance of an HFRC cable,the ac loss and contact resistance of the HFRC prototype cable were measured at the University of *** measurements were done in liquid helium(4.2 K)with ac magnetic fields,applied perpendicular to the cable's long *** ac loss was measured simultaneously by a calibrated gas flow calorimeter utilizing the helium boil-off method,and by the magnetization method using pick-up *** the applied test conditions,no coupling loss could be distinguished as a part of the overall ac *** is suggested that this might be explained by the shielding of the conductor interior from the applied magnetic field by the outer tape layer due to the high critical current density of the REBCO tape,leading to a high penetration field.

关键词： High temperature superconductor REBCO tape HFRC ac loss Contact resistance

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Numerical simulation on ac loss in REBCO tapes carrying non-sinusoidal currents

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Superconductivity 2023年第4期8卷 18-25页

作者： Katsuya Uejima Yueming Sun Daisuke Miyagi Jakub Glowacki Nicholas J.Long Zhenan Jiang Department of Electrical and Electronic Engineering Chiba UniversityChiba 263-8522Japan Paihau-Robinson Research Institute Victoria University of WellingtonWellington 6140New Zealand

ac loss is one of the greatest obstacles for high‐temperature superconducting(HTS)*** some HTS applications,coated conductors carry non‐sinusoidal ***,it is important to investigate the effect of various waveforms on ac loss in coated *** this work,transport ac loss in a 4 mm‐wide REBCO coated conductor carrying sinusoidal and non‐sinusoidal currents,is numerically *** current amplitudes,the frequency of the transport current,and n‐value are ***‐sinusoidal transport current waveforms studied include square,five types of trapezoidal,and triangular *** results show that,for a given current amplitude,ac loss for the square current waveform is the greatest,that for the triangular waveform is the *** sequence of ac loss in the conductor for different current waveforms coincides with the penetration depth,which implies the penetration depth determines the ac loss of the coated ***,the transport ac loss in the conductor was found to decrease with frequency as f2=n for non‐sinusoidal transport current.

关键词： REBCO coated conductors ac loss Non‐sinusoidal current

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Field and current driven versions of Brandt method for calculating transport ac loss of superconducting cylinder and strip

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Superconductivity 2023年第3期7卷 8-16页

作者： Xiao-Fen Li Shuo Li Du-Xing Chen School of Electronic Information and Electrical Engineering Shanghai Jiaotong UniversityShanghai 200240China College of Information Science and Engineering Northeastern UniversityShenyang 110004China Departament de Física Universitat Autònoma de Barcelona08193 BellaterraBarcelonaSpain

As an elegant and fast numerical tool for solving time‐dependent electromagnetic field problems in hard superconductors,Brandt’s method has played an important role in understading the magnetic behavior of superconducting strips,discs,bars and cylinders in various aspect ***,the application of this convenient method was mainly in magnetization ***,the solution of current transport problem needs to introduce a driving electric field E_(a),which requires a low efficiency iterative process and E_(a) itself was not clearly *** this work,three integral algorithms based on the Brandt’s method are developed to deal with current transport problems,which directly adopt the applied current as a boundary *** the current(I)‐driven version and two current‐field‐driven versions A and ***,the arbitrary applied magnetic field can also be included in the I‐driven *** derivation with all necessary formulas for the methods are given in this *** an example,the new methods,as well as the traditional method are used for calculating transport ac loss Q of a superconducting cylinder or strip obeying a power‐law relation of E∝J^(n)as a function of a given I(t).Derived from the Ampère law and the differential rather than the integral expression of the Faraday law,the current‐driven version can be used for more accurate and much quicker *** an intermediate quantity,E_(a)(t) in the two current‐field‐driven versions is accurately calculated under the given I(t),but version B is much quicker than *** relating to E_(a)(t) and Q stabilization process are discussed.

关键词： ac loss Superconducting cylinder and strip Power‐law EeJT relation Brandt method

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Calculation model of ac loss for CICC(cable-in-conduit conductor) based on strain

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Science China(Technological Sciences) 2012年第5期55卷 1132-1139页

作者： JIANG HuaWei WU SongTao ZHANG DeXian XU ZhaoHui ZHEN Tong College of Information Science and Engineering Henan University of TechnologyZhengzhou 450001China Institute of Plasma Physics Chinese Academy of SciencesHefei 230031China

The CICC (cable-in-conduit conductor) in ITER (International Thermal-nuclear Experimental Reactor) will run in high-current, fast transient magnet field and complex environment. In response to the impact of magnet fields above 10 T, the Nb3Sn conductor has been introduced. However, the ac (alternating current) loss mechanism of Nb3Sn conductor on strain has not been explored. So, it is necessary to study the ac loss calculation method with transient electromagnetic field and wide range of strain, the coupling current in complex field and current signal of field is simplified to the spectrum effects of coil excitation, and calculation technology of ac loss, which contains the frequency, magnet field, coil characteristics and other parameters, is constructed to meet the discrete Fourier transform (DFT). By comparative analysis of simulation, it is found that the ac loss calculation of the conductor with spectrum algorithm is closer to the actual project value than the traditional algorithm. For the rapid excitation, in particular plasma discharge and burst, spectrum algorithm and the traditional algorithm are consistent. For the relative error calculation of hysteresis loss and coupling loss, it is found that the coupling loss is cumulative linearly, where the hysteresis loss is not so. As a function of the amplitude, frequency and phase angle, the relative error is less than 40%. The results showed that the method of Fourier restructuring is satisfactory.

关键词： cable-in-conduit conductor (CICC) strain numeric simulation ac loss calculation model

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Analysis and Calculation of ac losses Test of EAST PF Model Coil

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Plasma Science and Technology 2006年第4期8卷 488-490页

作者：谭运飞翁佩德武玉陈灼民王喜鹏 Institute of Plasma Physics Chinese Academy of SciencesHefei 230031China

The poloidal field model coil （PFMC） of EAST was a large NbTi superconducting coil. The PFMC was designed and constructed by Institute of Plasma Physics, CAS, and it was tested during 2003 at our institute. One of the most important performance testing items was the ac （Alternating Current） loss. It was able to measure the ac losses by the calorimetric method. The results will be useful for the evaluation of the ac losses of the poloidal coil and provide meaningful data for future operation of the EAST device.

关键词： ac loss calorimetric method enthalpy

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Numerical analysis of magnetization ac losses in high-temperature superconducting slabs subjected to uniform strains

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Science China(Technological Sciences) 2014年第4期57卷 765-772页

作者： XIA Jing ZHOU YouHe Key Laboratory of Mechanics on Disaster and Environment in Western China attached to the Ministry of Education of China and Department of Mechanics and Engineering Sciences College of Civil Engineering and Mechanics Lanzhou University

High-temperature superconductors in superconductor apparatuses are subjected to mechanical strains under operating *** strains cause the degradation of the critical current densities and influence ac losses in the *** on the dynamic process of thermomagnetic interaction,we report the results of numerical analysis of ac losses in an infinite high-temperature superconducting slab subjected to a uniform in-plane strain in an alternating external magnetic field parallel to the sample *** numerical analysis shows the details of electromagnetic phenomena in the slab and the dependences of ac loss on various external parameters including the uniform strain in the slab and the amplitude and frequency of the external magnetic *** this paper,we find that whether the magnetic field fully penetrates the superconductor is the key factor that influences the features of ac *** the magnetic field cannot fully penetrate the superconductor,the loss rises with increasing strain or decreasing *** the magnetic field can fully penetrate the superconductor,the feature is just *** also analyze the effects of periodic strain on ac *** is interesting to find that when the periodic strain frequency equals the external magnetic field frequency,the ac loss reaches the maximum,regardless if the magnetic field fully penetrates the superconductor or not.

关键词： high-temperature superconducting slab ac loss strain

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Status and Progress on an HTS Strand with Quasi-isotropic Critical Current

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CSEE Journal of Power and Energy Systems 2021年第1期7卷 150-155页

作者： Jian Du Jianlong Sun Yang Nie Siming Mo Yuan Cai Huijuan Chen Wen Yuan Yinshun Wang the State Grid Jiangsu Electric Power Co. Ltd.Economic Research InstituteNanjing 210008China the Key Laboratory of HV and EMC Beijing North China Electric Power UniversityNorth China Electric Power UniversityBeijing 102206China the Jiangsu Etern Company Limited Suzhou 215211China the Eastern Superconducting Science&Technology(Suzhou)Co.Ltd Suzhou 215200China

The coated conductors(CCs),also known as the second-generation high-temperature superconducting(2G HTS)tape,has attractive potential applications in transmissions at low magnetic field/liquid nitrogen temperatures and high-field applications at low temperatures due to their excellent critical current density and mechanical *** critical current density has strong anisotropy,particularly at 77 *** the single tape has limited capacity of carrying current,the cable or strand making of multi-tapes,stacked in parallel,is *** recent years,several cables,such as the Roebel cable,CORC cable,TSTC cable,TS cable,and the HTSCroCo cable,were *** paper presents a status and progress on a type of HTS strand made from REBCO *** quasi-isotropic critical current is experimentally confirmed for liquid nitrogen temperature,mechanical characteristics,ac losses,thermal stability,and quench characterizations are also ***,the feasible process for the production of practical length of such strand is described by processing 10 m long sample,which is promising for applications of high fields or power transmission.

关键词： ac loss critical current mechanical characteristics quasi-isotropic strand stability

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Test and Analysis of China's First Short Conductor Sample for ITER Toroidal Field Coils

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Plasma Science and Technology 2011年第1期13卷 106-110页

作者：刘勃武玉 Institute of Plasma Physics Chinese Academy of Sciences

In the flamework of the ITER qualification tests, the first China TF conductor sample （CNTF1） was tested at the SULTAN facility. The sample was made of two TF conductor sections manufactured from identical internal stannum strands provided by the Oxford ~upercon- cluctlng technology company （OST）. In order to evaluate the conductor performance, the current sharing temperature （Tcs） was measured at specified electromagnetic load cycling steps. Both conductor sections of the CNTF1 sample showed identical performance. Tcs was 7.2 K before cycling loading, and 6.9 K even after 950 cycles, without significant degradation, which substan- tially exceeds the ITER requirement of 5.7 K. The tests of the CNTF1 conductor sample showed that the electromagnetic cyclic load exhibited a negligible effect on the conductor performance. The coupling time constant 0 for ac loss was 214 ms and 71.52 nrs before and after the cycling load. respectively. The test results of the sample are compared with the strand performance and parameter model analysis.

关键词： current sharing temperature. ITER, NbaSn TF conductor ac loss

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HTS Transformer and Its Related loss Measurement and Quench Protection Techniques

HTS Transformer and Its Related Loss Measurement and Quench ...

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第二十七届中国控制会议

作者： Jin Jianxun 1,Chen Xiaoyuan 1,Guo Youguang 2,Zhan Yuedong 2,3,Zhu Jianguo 2 1.Center of Applied Superconductivity and Electrical Engineering,University of Electronic Science and Technology of China,Chengdu610054,P.R.China 2.Faculty of Engineering,University of Technology,Sydney,NSW 2007,Australia 3.Kunming University of Science and Technology,Kunming,150001,P.R.China

Recently research and development concerning applications of high temperature superconducting（HTS） transformers have been progressed actively in the *** the HTS rated current capability,it is also essential to develop the relevant and precise performance test and protection systems for HTS *** paper mainly presents elementary test and protection methods of HTS transformers including ac loss measurement,and quench detection and protection.A new integrated measurement system for HTS transformers is also proposed by using the Labview virtual instrument software.

关键词： High Temperature Superconductor (HTS) HTS Transformer ac loss Quench Protection Labview

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面向自然场景的中文文本检测

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微电子学与计算机 2022年第3期39卷 25-33页

作者：贾颖程艳云南京邮电大学自动化学院、人工智能学院江苏南京210000

随着深度学习的发展,自然场景的文本检测取得了进步,但多方向和弯曲中文文本检测效果仍不理想.针对多方向和弯曲中文文本的检测问题,提出一种融合注意力机制的多尺度文本检测方法.为了平衡模型准确性和降低计算复杂度,采用轻量级Resnet1... 详细信息

随着深度学习的发展,自然场景的文本检测取得了进步,但多方向和弯曲中文文本检测效果仍不理想.针对多方向和弯曲中文文本的检测问题,提出一种融合注意力机制的多尺度文本检测方法.为了平衡模型准确性和降低计算复杂度,采用轻量级Resnet18为主干网络.针对特征金字塔(FPN)提取的特征分布不确定性的问题,嵌入平衡注意力机制(BAM)提取有效文本特征并抑制低效特征通道,进而提升检测方法的鲁棒性.针对空洞空间金字塔池化网络(ASPP)下采样时图像局部信息和细节信息丢失的问题,改进ASPP以降低特征图分辨率的损失.针对FPN提取特征不足以及感受野小的问题,将嵌入注意力机制的FPN和改进的ASPP并行增强特征提取融合.针对正负样本的不平衡性的问题,基于可微二值化模块在二值图损失中引入对数化的ac loss,从而增强检测模型的泛化能力.在公开数据集MSRA-TD500上的实验结果表明,该算法与目前快速高效的DBnet相比,准确率、召回率和F值分别提升0.1%、1.4%和0.6%,并且该算法的检测速率也有较好表现.

关键词：文本检测特征金字塔 BAM注意力机制可微二值化 ac loss

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