考虑磁场径向分量的高温超导储能磁体几何结构优化配置

高温超导储能磁体磁场的径向分量使得带材利用率不高且磁体储能密度低.针对此问题,本文提出了一种获得高温超导储能磁体最优几何结构配置的方法.首先利用MATLAB对YBCO高温超导储能单螺管磁体的结构进行优化获得初步模型,随后对双饼线圈进行分组,利用电磁场有限元分析软件对内外三阶梯和内外八阶梯结构磁体的磁场径向分量、储能大小进行了分析,研究了相邻双饼线圈不同厚度间距对磁体带材利用率和磁体储能密度的影响.由仿真计算结果可知,内外多阶梯结构磁体均能够提升磁体的性能,其本质是减小磁场径向分量.通过对计算结果比较分析最后获得了储能磁体几何结构的最优配置.     

一种基于阶梯电流的高温超导储能磁体优化方法

高温超导带材的各向异性特性一直影响着它工程使用中性能的充分发挥,为了提高带材的利用率,本文提出了一种基于阶梯电流的优化方法,利用MATLAB对YBCO高温超导储能单螺管磁体的结构进行优化获得初步模型,对双饼线圈进行分组,以两阶梯电流和三阶梯电流为例对磁体进行了优化.分析了各组双饼线圈的磁场分布和临界电流,计算了各部分带材性能的利用率.利用有限元软件分析阶梯电流引起的磁场变化,在充分考虑带材的临界特性和各向异性的前提下优化各组线圈的电流大小.仿真计算表明,和统一电流磁体相比,采用阶梯电流法能够优化磁体磁场构型,提高平均储能密度,最终提高磁体带材的利用率从而提升储能.阶梯电流法同样适用于多螺管磁体,对于超导储能磁体的优化是一种行之有效的方法.     

传导冷却高温超导磁体的电磁分析

本文对高温超导双饼线圈的绕制、测试和结果进行了讨论和分析,在此基础之上对传导冷却高温超导磁体进行了电磁分析,通过对6到21个双饼线圈组成的磁体的各种参数进行计算,得到了一系列变化曲线,从中可以看到各个参数的变化趋势,以便有效设计高温超导磁体.     

传导冷却高温超导磁体的电磁分析

本文对高温超导双饼线圈的绕制、测试和结果进行了讨论和分析，在此基础之上对传导冷却高温超导磁体进行了电磁分析，通过对6到21个双饼线圈组成的磁体的各种参数进行计算，得到了一系列变化曲线，从中可以看到各个参数的变化趋势，以便有效设计高温超导磁体。     

高温超导线饼电感的数值计算方法研究

随着高温超导材料技术的进步,高温超导磁体的研究也成为研究的重点对象。鉴于其零电阻、高电流密度等相对于常规导体磁体所不具备的优点,高温超导磁体在电力工业中储能系统、电机、变压器、限流器等电气装置中也有重要的应用意义。饼绕超导磁体的核心即超导线圈绕制而成的线饼,而超导磁储能系统的动态过程则是围绕着磁体的电感充电与放电开展,因此对高温超导磁体内部线饼的电感及互感耦合的分析显得极为重要。文中在单个线饼的基础上,首先介绍了高温超导线饼的结构,提出计算线饼自感及互感参数的若干数值算法及有限元仿真方法,并结合实际测量数值,对高温超导线饼自感及互感参数进行了对比分析;接着对低温相比常温下线饼电感数值下降的情况进行了简单的原因分析。     

120kJ高温超导储能磁体的研究

阐述了120k J高温超导储能磁体的高温超导带选择及磁体主要参数。为确定120k J高温超导储能磁体绕组的通电方式,比较了30个高温超导双饼线圈两种连接方式在225A电流下的磁场特性。为满足杜瓦强度要求,针对120k J高温超导储能磁体杜瓦开展了结构设计及强度分析,结果表明,杜瓦满足高温超导绕组吊挂对其强度的要求。     

YBCO双饼线圈制备工艺及性能测试

针对YBCO高温超导带材在制备磁体过程中性能退化的问题,从骨架结构、预应力、绕制工艺等方面介绍了一种双饼线圈的绕制方法.根据该方法成功绕制了两种规格的双饼线圈,并使用四引线法对线圈的性能进行低温测试,测试结果与设计值的对照表明:线圈性能符合预期目标,绕制工艺稳定可靠,对于高温超导磁体的设计和制备具有一定的指导意义.     

电力系统动模实验用50kJ高温超导储能磁体的设计研究

介绍了 2 0 K下对电力系统动模实验用 5 0 k J高温超导储能磁体的设计步骤 ,给出了用 Bi- 2 2 2 3单根超导带进行5 0 k J磁体线圈的设计和优化结果 ,分析了高温超导体的各向异性对磁体临界电流的影响和磁体漏磁的分布 ,并讨论了用单根高温超导带组成的超导体和用多根高温超导带组成的超导体设计的储能磁体的特性参数对改善电力系统动态特性的能力的影响。     

高温超导储能磁体双圈分裂式嵌套屏蔽研究

随着高温超导储能磁体储能量的进一步增大,对高储能量磁体周围漏磁场的屏蔽愈加重要.增强屏蔽效果与减少屏蔽成本成为磁体屏蔽的两个重要目的.本文利用有限元仿真软件ANSYS对高温超导磁体周围的漏磁场分布进行分析,并对其进行双圈分裂式嵌套屏蔽.以屏蔽效果和超导带材用量为优化目标,对屏蔽磁体的几何参数进行计算和优化,并对不同屏蔽方案进行对比分析.     

基于YBCO的3MJ超导储能线圈模型样件的测试

高温超导储能磁体(HTS-SMES)是超导在电力系统中的重要应用之一。项目设计的3MJ级SMES装置采用YBCO高温超导带材绕制为16组线圈饼,每组线圈饼由8个双饼线圈组成,工作电流超过500A。文中选取3MJ储能线圈中的1个双饼作为模型样件,在完成该模型样件制造及装配后,对其进行了77K液氮环境下的临界电流、磁场分布、应力应变等项目的测试,测试结果满足测试样件的设计条件,可以为工程化SMES装置的设计和运行提供参考。     

舰船电力系统用1MJ高温超导环型储能磁体的设计研究

介绍了舰船电力系统用 1MJ环型高温超导储能磁体的设计优化步骤 ,进行了环型磁体线圈最大磁场的优化、环型磁体单元尺寸的优化和环型磁体单元数目的优化 ,并得出了合适的磁体线圈尺寸。磁体线圈上的最大磁感应强度为 3-4 T,单元数目较大的环型磁体适用于 1MJHTS- SMES     

基于近似解析法的超导储能磁体设计

降低超导储能磁体的研制成本一直是控制超导磁储能系统(Superconducting Magnetic Energy Storage, SMES) 总成本的重要手段之一. 本文考虑在一定磁体结构参数范围内, 磁体产生的最大磁场值可以采用级数进行 表示, 磁体的电感值可以采用线性函数表示, 给出了超导储能磁体磁场能量的近似解析表达式, 提出了一种基于近 似解析法的超导储能磁体设计方法. 该方法以储能磁体的线材用量最小作为设计目标, 在给定超导线材参数和临界电流特性曲线, 以及磁体储能总量要求的情况下, 依据此方法可快速的得到成本最优时所对应的磁体结构参数.将近似解析法优化和采用传统的有限元软件 Ansys 仿真优化进行对比分析, 结果表明采用近似解析法进行磁体优化更加方便快捷, 节省了大量计算时间.     

多种优化方法及其在高温超导磁体优化设计中的应用

本文阐述了几种优化方法及其对它们的改进,并选用测试函数对各种方法的寻优性能作了对比;然后阐述了高温超导磁体的径向磁场对临界电流的影响及最大径向磁场的位置定标方法;最后将各种优化方法应用于高温超导磁体的设计中.经过优化,高温超导磁体大大减小了其体积,提高了超导材料的利用率,节约了超导材料的用量及制冷时所损耗的电源功率.     

Influence of supercurrents on the stability of superconducting magnets

Supercurrents were recently identified as a source of reduced magnet stability which can explain the measured ramp rate limitation in large superconducting magnets. They also explain an unexpected periodic field modulation along the axes of superconducting accelerator dipoles. Supercurrents are extra coupling currents between the strands of a cable which are induced by a variable field sweep rate (x) along the length of the cable. They flow over the whole cable length and have time constants many orders of magnitudes larger than ‘normal' interstrand coupling currents. Supercurrents may lead to a highly inhomogeneous current distribution and to additional coupling losses (‘supercurrent losses'), even in magnet sections with =0. Both effects can drastically reduce the magnet stability during fast ramping up. The complete solution of the space and time dependence is given for a two-strand model cable. The theory of supercurrents can explain typical results of ramp rate limitation in large magnets.     

Calculation of the critical currents of Bi(2223)/Ag tapes and coils with reduced anisotropy in Ic(B) characteristic — effect of different proportional representations of the filaments oriented parallel and perpendicularly to the tape surface

A mathematical model was developed to allow for the prediction of critical currents in Bi(2223)/Ag-sheathed tapes that consist of two groups of filaments, having crystalline texture (c-axis) predominantly in two directions orthogonal to each other and to the length of the conductor (filaments oriented parallel and perpendicular to the tape surface). Using the theory presented, it is possible to estimate the upper limit of critical currents in the tapes prepared with a two-axial rolling technique. Magnetic field and angular dependencies of critical currents were obtained at 77 K measuring tapes with various proportional representations of filaments oriented in both preferred directions, i.e., the parallel and perpendicular directions. The results of calculation indicate that the anisotropy in the I_c(B) characteristic should be reduced considerably using the two-axial rolling. Unfortunately, the effect of anisotropy reduction is accompanied by simultaneous decrease in the current-carrying capacity of the tapes. The data obtained for short tape samples were utilised to estimate the critical currents of the individual turns of a small cylindrical magnet, assembled of eight pancake coils. It is shown that only a slight increase in the critical current of the magnet can be expected if the winding should be made of the tape with reduced anisotropy in the I_c(B) characteristic. The factors that limit the increase of the magnet critical current are discussed in detail.     

Theory of muon spin relaxation by critical fluctuations in antiferromagnetic salts

Relaxation rates for positive muons implanted in antiferromagnetic salts are predicted on the basis of calculations performed with a coupled-mode theory of critical fluctuations in isotropic and uniaxial magnets. Anisotropy suppresses fluctuations transmitted by the isotropic (hyperfine) relaxation mechanism. The dipolar mechanism leads to a relaxation rate which increases on lowering the temperature to the critical point; the predicted form, proportional to the critical correlation length, yields the same temperature dependence as for the NMR linewidth. For a magnet with isotropic spin interactions, both contributions (hyperfine and dipolar) to the relaxation rate diverge with a temperature dependence given by the square-root of the correlation length.     

合肥同步辐射光源波动器UD-1物理设计

 介绍了国家同步辐射实验室二期工程新建波动器UD-1的物理设计，给出了设计参数和主要技术要求。从储存环电子束流的要求和用户对光源的要求两方面分析了波动器磁场品质应满足的技术指标，给出UD 1的磁场一次积分值应小于2×10^-4T·m，二次积分值应小于2×10^-4T·m ²,相位误差应小于10°。     

Angular Dependence of Lateral and Levitation Forces in Asymmetric Small Magnet/Superconducting Systems

The dipole-dipole interaction model is used to calculate the angular dependence of lateral and levitation forces on a small permanent magnet and a cylindrical superconductor in the Meissner state lying laterally off the symmetric axis of the cylinder. Under the assumption that the lateral displacement of the magnet is small compared with the physical dimensions of the system, we obtain analytical expressions for the lateral and levitation forces as functions of geometrical parameters of the superconductor as well as the height, the lateral displacement and the orientation of magnetic moment of the magnet. The effect of thickness and radius of the superconductor on the levitation force is similar to that for a symmetric magnet/superconducting cylinder system, but within the range of lateral displacement. The splitting in the levitation force increases with the increasing angle of orientation of the magnetic moment of the magnet. For a given lateral displacement of the magnet, the lateral force vanishes when the magnetic moment is perpendicular to the surface of the superconductor and has a maximum value when the moment is parallel to the surface. For a given orientation of the magnetic moment, the lateral force has a linear relationship with the lateral displacement. The stability of the magnet above the superconducting cylinder is discussed in detail.     

Scaling study for a high-field magnet for quasi-optical gyrotrons

The design of a 12 T superconducting magnet for a 280 GHz quasi-optical gyrotron is discussed. The gyrotron geometry requires a clear bore perpendicular to the magnetic axis through the center of the magnet, thus forcing the magnet to be formed of two separate sections. This causes the peak field on the windings to be over 14 T, and produces a double-peaked structure in the field. Calculations of mirror and cross bore RF heating and electron beam reflection as a function of the magnet and cross bore dimensions are presented, as are discussions of other tradeoffs in the magnet design. The conclusion of the study is that a suitable magnet is feasible