A superconducting direct-current limiter with a power of up to 8 MVA

A resistive switching superconducting fault current limiter (SFCL) for DC networks with a nominal voltage of 3.5 kV and a nominal current of 2 kA was developed, produced, and tested. The SFCL has two main units—an assembly of superconducting modules and a high-speed vacuum circuit breaker. The assembly of superconducting modules consists of nine (3 × 3) parallel–series connected modules. Each module contains four parallel-connected 2G high-temperature superconducting (HTS) tapes. The results of SFCL tests in the short-circuit emulation mode with a maximum current rise rate of 1300 A/ms are presented. The SFCL is capable of limiting the current at a level of 7 kA and break it 8 ms after the current-limiting mode begins. The average temperature of HTS tapes during the current-limiting mode increases to 210 K. After the current is interrupted, the superconductivity recovery time does not exceed 1 s.     

Effect of the Rate of the Rise in Current on Transient Processes in a Superconducting Fault Current Limiter

The effect of the rate of the rise in the current to 1700 A/ms on the characteristics of a transition of units of superconducting (HTSC) modules from a superconducting to normal state has been experimentally studied. The units differed by the critical current of the HTSC tape and design. The units of HTSC modules are used as a part of the resistive superconducting fault current limiter (SFCL) for ac and dc grids. The obtained dependences should be taken into account when designing a resistive SFCL.     

电力故障运行下磁偏置超导限流器超导限流单元的电-热特性分析与验证

本文的磁偏置高温超导故障限流器(SFCL)是一种新型超导限流器,在系统出现短路故障时,发生失超现象,产生高阻抗限制短路电流,达到一定时间后断开超导单元,再由双分裂电抗器二次限流.当短路电流消失后,自动快速恢复到无阻特性,然后重新合闸投入系统运行.在SFCL并网运行前,要对并网运行中出现相间短路等故障的暂态运行特性进行分析,了解并网运行时的状况.本文利用Matlab/Simulink构建了SFCL的仿真分析模型,包含超导限流单元的等效电路模型和热模型.该模型被接入一个由Matlab/Simulink构建的10kV电力系统模型中,用来仿真SFCL的并网运行特性.仿真结果表明了SFCL在并网运行中的效果,以及相间短路故障下失超电阻、通过电流和超导限流单元温度的变化.同时,在中国国网辽宁电力虎石台对SFCL进行了并网运行试验,得到了相间短路故障下的暂态运行特性和失超恢复时间.本文的仿真分析和试验结果,证明了该SFCL样机具备10kV 并网能力,以及快速响应、逐级限流和快速恢复能力     

电压补偿型超导限流器对电流保护的影响

基于电压补偿型超导故障限流器(SFCL)的工作原理,分析了电网故障时由于限流器限流阻抗串入对电流保护的影响.通过重新整定电流保护的动作值,得到了限流器与电流保护配合的解决方法.以一个10kV中性点不接地配电网为例,分别对引入SFCL前后系统三相短路的电流保护进行仿真,验证了该方法的有效性.     

超导故障限流器的数学模型研究

文中总结了几种超导故障限流器的模型。在数学模型的基础上 ,阐述了超导材料的温升、失超传播速度和临界电流密度对超导故障限流器性能的影响     

电压补偿型超导限流器在三相电网中的故障限流特性

基于电压补偿型超导故障限流器(SFCL)的单相电路结构和工作原理,提出了一种关于电压补偿型超导故障限流器的三相电路结构,并对其在三相电力系统发生不同故障时的运行特性进行了分析。利用Matlab/simulink建立仿真模型,仿真结果表明该电压补偿型SFCL的三相拓扑结构具有一定的可行性,对系统中发生不同短路故障时的短路电流都具有良好的限制作用。     

Control strategy for three-phase four-wire PWM converter of integrated voltage compensation type active SFCL

The integrated voltage compensation type active superconducting fault current limiter (SFCL) is composed of three air-core superconducting transformers and a three-phase four-wire PWM converter. In order to realize the current-limiting characteristics of the integrated active SFCL, it is needed to control the three-phase four-wire PWM converter flexibly and reasonably. Thereby, the control strategy for the converter is analyzed in this paper. In dq0 reference frame, the mathematical model of the converter is founded. The double-loop control strategy, consisting of voltage outer loop and current inner loop, is presented. Moreover, the voltage balance control for the split DC link capacitors is also considered. Using MATLAB, the simulation model of the integrated active SFCL is built. According to the simulation results, it is known that, the presented control strategy is feasible and valid, and the converter can work well under unsymmetrical and symmetrical fault conditions, and then the fault current can be limited quickly and effectively.     

饱和铁芯型超导限流器研究进展综述

电力系统短路电流对系统的稳定安全运行造成了极大的威胁,超导故障限流器是一种将超导技术、电力技术相结合产生的故障限流装置,能有效地限制短路电流。饱和铁芯型超导限流器是产业化前景较好的一种超导限流器,在对此类型的故障限流器进行了深入调研和广泛收集资料的基础上,介绍了饱和铁芯型超导限流器的工作原理,分析了它的优缺点,阐述了饱和铁芯型超导限流器的国内外发展现状,归纳了其在设计过程中的关键技术和制约其工业化应用的主要问题,并提出了技术建议,最后展望了饱和铁芯型超导限流的应用前景。     

串联超导单元失超特性改善方法的仿真研究(英文)

为承受高电压与高电流等级,电阻型超导限流器的各个无感超导单元间不可避免地要进行串并联,由此会带来单元间失超不同步的问题.本文以单根344S超导带材在100ms的故障时间内,带材温度由92K升至300K时,失超电阻随温度的变化为基础,对两者间的关系进行了拟合.之后,以拟合函数为核心,利用Simulink的库中元件构建了单位长度344S带材的失超电阻模型并将其封装为模块.最后,搭建仿真电路模拟了故障时间内两个串联失超模块不同步失超的过程,仿真了分流电阻对失超不同步的改善并对分流电阻的选取进行了优化分析.结论证实,较小阻值的分流电阻更有利于改善失超特性.     

Environment-resistive coating for the thin-film-based superconducting fault-current limiter Ag/Au–Ag/YBa2Cu3O7/CeO2/Al2O3

We have studied environment-resistive coatings (ERC) for the thin-film-based superconducting fault-current limiter (SFCL) Ag/Au–Ag/YBa₂Cu₃O₇/CeO₂/Al₂O₃. We evaluated nine candidate ERC materials by two accelerating-environment tests, and revealed that the shellac- and the fluorine-resin have a high environmental resistance. Especially, the shellac resin almost completely protected Jc of an element exposed to 60 °C saturated water vapor for 2 h (3.4–>3.2 MA/cm²). We also performed a practical operation test of SFCL using an element half covered by shellac, and found that the ERC does not diminish the current limiting properties similarly to the previous results of the Teflon-coated SFCL [1].     

桥式超导故障限流器的研究新进展

普通桥式超导故障限流器(Superconducting Fault Current Limiter,SFCL)只能限制故障短路电流的峰值,不能限制短路电流的稳态值。应用电力电子技术对桥式超导限流器的结构进行改进能在保持原有桥式限流器优点的基础上,有效限制短路电流的稳态值。针对现今的研究热点,着重介绍了全控桥型、电阻投切型、混合型、有源型等几种实用价值较高的桥式SFCL的工作原理及其特点,并对桥式超导限流器研究中存在的问题及其发展趋势做了说明。     

超导故障限流器的研究现状及其应用

超导故障限流器(Superconducting Fault Current Limiter,SFCL)是利用超导体的基本特性,有效限制电力系统故障短路电流,提高电网安全性和稳定性的一种新型电力设备。文中在综合大量文献的基础上,对超导故障限流器进行了一种较为系统的分类。基于该种分类,结合目前国内外的研究现状,就电阻型、磁屏蔽型、饱和铁芯电抗器型、桥路型SFCL的工作原理作了详细的分析介绍,还给出了它们在电力系统中的安装位置。最后,对超导故障限流器的研究中存在的问题及其发展趋势做了说明。     

A novel method of flat YBCO rings development for shield-type superconducting fault current limiters fabrication

The application of flat superconductor rings has been investigated in the structure of inductive shield-type high temperature superconducting fault current limiters, HT_c-SFCL. A laboratory scale inductive shield-type HT_c-SFCL has been designed and fabricated using flat superconductor rings. The fabrication process has been fully presented. YBCO powder has been used for the fabrication of superconductor rings. This fabrication process, being quite innovative, is introduced completely. The method of the trapped field measurement has been used for the critical current density measurement of the fabricated superconductor rings. The device with nominal current of 2 A was tested in a 30 V circuit. The SFCL successfully limited the fault currents of up to 10 times the nominal current to an approximately fixed value of 3 A. The voltage-current characteristic of the fabricated prototype has also been obtained and has shown compatibility with the fault current limitation results.     

Design and study of a high-current 5-cell superconducting rf cavity

The Advanced Photon Source (APS) at Argonne National Laboratory is considering the development of a superconducting linac-based fourth-generation hard X-ray source to meet future scientific needs of the hard X-ray user community. This work specifically focuses on the design of an optimized 5-cell superconducting radio-frequency structure well suited for a high-energy, high-beam-current energy recovery linac. The cavity design parameters are based on the APS storage ring nominal 7 GeV and 100 mA beam operation. A high-current 5-cell cw superconducting cavity operating at 1.4 GHz has been designed. In order to achieve a high current, the accelerating cavity shape has been optimized and large end-cell beam pipes have been adopted. The beam break-up threshold of the cavity has been estimated using the code TDBBU, which predicts a high threshold beam current for a 7 GeV energy recovery linac model. A copper prototype cavity has been fabricated that uses half-cell modules, initially assembled by clamping the cells together.     

基于超导储能脉冲变压器的多模块脉冲电源设计

为了探索一种更加紧凑的导轨型电磁推进基础实验用脉冲电源,以实验室现有高温超导储能脉冲变压器为单元模型,在单谐振电路脉冲成形方案的基础上,设计了环形结构的多模块脉冲电源,分析了环形结构中考虑互感的多模脉冲电源电路的充放电过程。通过对八模块环形结构脉冲电源进行仿真分析,得到了接近150kA的电流脉冲,原边电压限制13kV左右。可以得出,利用单谐振电路的多模块超导储能脉冲变压器并联放电方式,可以实现大电流脉冲的输出的要求,而且环形结构中各线圈存在的互感更有利于多模块脉冲电源。     

高温超导电流引线研究进展概述

超导装置中需要电流引线实现室温端外部电源与处于低温环境的超导磁体相连，采用高温超导电流引线可以有效降低端漏热，降低运行成本.在满足设计电流的基础上，尽可能降低电流引线的总漏热，提升其失冷时间与烧毁时间，是高温超导电流引线的优化目标.本文概述了高温超导电流引线的传热分析、结构设计、安全性评价以及国内外具体应用案例.     

YBCO薄膜过电流失超特性实验及分析

YBCO薄膜材料作为电阻型高温超导限流器的限流元件具有单位通流长度耐压高,失超后不易损毁等优点.本文设计一套实验设备,在不同幅值交流电源条件下,对YBCO薄膜过电流失超特性进行了测量.实验得到了在不同过电流作用下YBCO薄膜的阻抗及电压随时间的变化关系.大量实验数据表明,YBCO对短路电流有很好的限流效果.并且动作迅速,失超后有效限流电阻大.结合实验数据,文中将YBCO薄膜的过电流失超过程分为三个不同阶段.对应于不同幅值的交流电源,分析了不同阶段YBCO的电阻发展过程.本文得到的结论对YBCO薄膜限流元件的建模及失超传播分析有着重要的参考意义.     

新型桥路型高温超导故障限流器的仿真研究

研究应用于三相电力系统中新型桥路型高温超导故障限流器.正常工作情况,在电桥上引入直流偏置电流,不出现限流现象.在短路故障情况,整流桥中的直流偏流影响限流效果,将二极管和偏压电源从限流器中退出运行,超导线圈的电感能限制故障电流峰值和稳态值,利用限流电阻与超导线圈串联限流,进一步提高其限流能力.分析了限流器的工作原理和限流特性.仿真结果表明,该限流器有很好的限流和重合闸能力,能显著减少暂态及稳态的故障电流,有效提高系统动态稳定性和电网电能质量.     

利用超导结的直流约瑟夫逊效应探测β粒子的初步实验结果

利用超导结的直流约瑟夫逊效应探测粒子,具有能量分辨率高和时间响应快的优点。我们首次进行了用Sr⁹⁰-Y⁹⁰β源辐照Nb-NbO_x-Pb超导结的实验。结果表明:在β粒子的辐照下,不仅超导结的临界电流和能隙电压都变小,而且在超导结的两端产生电压脉冲讯号。本文报道了利用直流约瑟夫逊效应探测β粒子所观察到的一些现象。 关键词：     

改进桥路型高温超导限流器的实验研究

本文介绍了单相基本桥型高温超导限流器的基本工作原理,及其参数变化对限流特性的影响.在此基础上研究应用于电力系统中的改进桥路型高温超导故障限流器实验室样机,正常工作情况,在电桥上引入直流偏置电流,不出现限流现象;短路故障情况,整流桥中的直流偏流影响限流效果,在桥路上引入限流电阻,使故障电流限制到预定的范围.研究了该限流器的工作原理,分析限流参数的变化对其限流特性的影响.实验表明,该限流器有很好的限流和重合闸能力,能显著减少暂态及稳态的故障电流。