三相电抗器型高温超导限流器的阻抗与动态仿真

三相电抗器型超导故障限流器(SCFCL)由三个同匝数的超导绕组绕在单一铁芯上组成，正常工作时阻抗为零，接地短路时，相当于串联了一个大电感，若发生三相或两相短路，其电阻突然增大；本分析了它在各种运行状态下其铁芯内的磁通变化，推导出了相应的阻抗公式；设计了一个小型样机，并对该样机的进行了动态仿真，其结果与理论分析一致．     

超导可控电抗器的原理和特性分析

介绍了超导可控电抗器在电力系统中的作用以及其工作原理和分类,并对各种类型的超导可控电抗器的工作原理、现状、特点及其优缺点都进行了详细的分析介绍,总结了超导可控电抗器的发展方向。     

直流超导限流器的发展和应用现状综述

超特高压直流电网发展迅速,但是直流电网面临故障电流上升速度快、幅值高、切断困难的问题,限流器能够抑制故障电流的上升,降低直流故障电流的开断难度.直流超导限流器是其中极为关键的一类,总结了相关的研究进展,着重介绍了电阻型、磁通耦合型、饱和铁心型、磁屏蔽型超导限流器的工作原理,并且介绍了最新的应用研究.最后讨论了直流超导限...     

磁屏蔽型超导限流器电气建模与应用研究

超导限流器被认为是理想的电力系统短路电流限制手段.主要针对磁屏蔽型超导限流器的电气特性进行系统性的建模研究.首先,基于限流器工作原理和超导材料的特殊电测特性,在PSCAD/EMTDC仿真平台中对磁屏蔽型超导限流器进行了数值模型和电路模型的搭建.随后通过实验室级限流器样机短路实验对仿真模型的可靠性进行了验证,并基于模型完...     

适用于电阻型超导限流器的超导带材选取与实验研究

电阻型超导限流器主要利用超导带材在失超后的电阻抑制故障电流值,目前一般采用不锈钢加强的ReBCO超导材料。由于涂层导体的银、铜稳定层对其电阻率的影响较大,尤其在低温段的影响尤为显著,成为影响超导带材在电流冲击后响应过程的主要因素。实验表明,超导带材可承载的冲击电流幅值随持续时间延长而迅速降低,不锈钢加强层厚度的增大有利于超导带材耐冲击电流水平的增加。因此,交流超导限流器应适当选用加强层较厚的超导带材,而直流超导限流器应选择具有铜稳定层及适当减小不锈钢加强层厚度的超导带材。     

磁屏蔽感应型超导故障限流器的仿真研究

磁屏蔽感应型超导故障限流器主要由一次铜绕组、二次超导圆柱形屏蔽筒、铁芯和液氮冷冻箱组成,其工作原理是利用超导筒从超导态转变到正常态时其阻抗的快速上升而限流,本文利用MATLAB仿真研究了该HTSCFCL模型,仿真结果证明该限流器能显著地减少了暂态及稳态故障电流,也表明该HTSCFCL能有效地提高系统的稳定性.     

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。     

一种用于电阻型超导限流器新型结构的第二代高温超导带材

电阻型超导故障限流器(R-SFCL)结构简单、限流效果好等优点,在电力系统中具有广阔的应用前景.超导故障限流器的发展经历了实验级、配电级、输电级样机研制等阶段.随着超导限流器容量不断攀升,由于单根材料性能的限制,不可避免在系统中会采用大量的串并联方式.带材的临界电流和耐瞬态冲击能力决定着一个限流器在额定电流通流下和过流冲击下的并联支路数.带材的失超电阻决定着一个限流器在一定故障电流抑制率下的串联支路数.通过分析目前REBCO超导带材的参数和典型的限流器设计参数,发现了超导带材电流和耐过流冲击相差近3倍的关系.本文提出了一种宽的不锈钢封装窄的超导带结构,目的是让不锈钢的宽度与超导带材的宽度保持在3倍的关系,以贴合部分限流器的需求.经过测试,结果显示低成本新结构的超导带材瓶颈性能保有原结构带材的91.3%,成本下降一半,这对未来电阻型超导限流器成本的降低来说是一个非常好的选项.     

新型磁屏蔽感应型超导故障限流器的研究

在研究磁屏蔽感应型超导故障限流器原理的基础上,提出了一种新型磁屏蔽感应型高温超导故障限流器,它主要由一次超导绕组、二次超导圆柱形屏蔽筒、铁芯和液氮冷冻箱组成,其工作原理是利用超导绕组和超导筒从超导态转变到正常态时其阻抗的快速上升而限流,对应用于三相系统的新型磁屏蔽感应型超导故障限流器进行了仿真研究,它能显著地减少暂态及稳态的故障电流,有效地提高电力系统的稳定性.     

饱和铁芯型超导限流器对距离保护的影响

饱和铁芯型超导限流器SCFCL(Saturated Core Superconducting Fault Current Limiter)是一种较为理想的高电压限流器,利用其技术特点可以实现无时限的明显限流作用,有着广泛的运用前景。距离保护能够很好的满足高电压复杂网络快速、精确切除故障的要求,其主要元件阻抗继电器是现阶段普遍应用的高性能继保装置。SCFCL在高压输电网络的接入会对距离保护产生很大影响,运用PSCAD搭建500kV输电线路模型,详细分析限流器接入前后不同短路故障类型及故障距离对线路距离保护的影响。     

深冷温区环氧树脂和聚四氟乙烯电阻率与击穿特性研究

电阻型超导直流限流器的主要部件是限流单元和电气终端,其采用的低温绝缘材料主要是玻璃纤维加强环氧树脂和聚四氟乙烯。针对环氧树脂和聚四氟乙烯样品在深冷温区的绝缘特性进行研究。利用三电极法对两种材料的电阻率随温度和场强的变化规律进行了测量,对两种材料的击穿耐压进行测试并观察其击穿痕迹,进一步利用Weibull分布对试验结果进行分析,试验结果表明:电阻率随温度和场强变化,击穿耐压符合Weibull分布。     

基于PSCAD的500kV饱和铁芯型超导限流器运行仿真研究

介绍了饱和铁芯型超导限流器基本原理,从结构原理上分析了饱和铁芯型超导限流器(SCSFCL)工作运行区间和阻抗特性。在分析SCSFCL工作阻抗特性基础上用EMTDC/PSCAD软件建立了饱和铁芯型超导限流器的电磁模型,搭建了500kV超导限流器基本运行电路,并在此基础上开展了系统仿真分析。     

Plasmonic split disk resonator based on graphene

In this paper, we designed and simulated an ultra-compact plasmonic filter consisting of a graphene ribbon laterally coupled to a graphene split disk resonator. Introducing a split inside the disk leads to split of the resonance modes symmetrically and asymmetrically. The spacing between the symmetric and asymmetric modes can be controlled through changing length of the split in the disk and the simulation results reveal that all modes identically shift as a result of changing the Fermi level of the disk. finite-difference time-domain method is used to investigate the device performance.     

Design criteria of a chemical reactor based on a chaotic flow

We consider the design criteria of a chemical mixing device based on a chaotic flow, with an emphasis on the steady-state devices. The merit of a reactor, defined as the Q-factor, is related to the physical dimension of the device and the molecular diffusivity of the reactants through the local Lyapunov exponents of the flow. The local Lyapunov exponent can be calculated for any given flow field and it can also be measured in experimental situations. Easy-to-compute formulae are provided to estimate the Q-factor given either the exact spatial dependence of the local Lyapunov exponent or its probability distribution function. The requirements for optimization are made precise in the context of local Lyapunov exponents. (c) 1999 American Institute of Physics.     

超导限流式无弧分断直流断路器研究

针对系统可靠运行与快速切断故障电流间的矛盾,提出一种基于超导限流的无弧分断直流断路器结构。该结构利用超导限流单元有效抑制了故障电流峰值,加快了换流速度,结合全控器件减少换流次数,解决了因可靠性延时期间过快的电流增长率,并缩短开断时间。对超导限流单元进行建模,通过数学模型分析断路器各阶段工作状态并进行了仿真。结果表明,该结构能够在提高分断速度同时有效缓解可靠性与速动性间的矛盾。     

基于规范化样本拆分的轴承缺陷检测

表面缺陷对轴承的性能和寿命存在严重影响.近年来,深度学习在缺陷检测中发挥了重要的作用,然而对于轴承检测而言,缺陷样本的采集耗时耗力.选择轴承内径作为研究对象,根据轴承的对称性特性提出一种规范化样本拆分方法,可有效扩充轴承样本数据集.分别采用不同的样本处理方法,而后利用ResNet网络训练轴承缺陷检测模型,进行多组对比实...     

Design and implementation of dual-band antennas based on a complementary split ring resonators

A simple dual-band antenna design and implementation method is proposed in this work, based on the equivalent media properties inspired by resonant metamaterial elements. The equivalent circuit model of dual-band patch antennas based on a complementary split ring resonator (CSRR) is presented and validated. The dual-band patch antenna is designed etching a CSRR in the patch of a conventional rectangular microstrip patch antenna. The first resonance is governed by the quasi-static resonance of the CSRR while the second resonance is originated by the rectangular patch. The fact of etching a CSRR on a rectangular patch antenna also produces a miniaturization of a conventional patch antenna. The equivalent circuit model proposed in this letter is sound in order to understand the functionality of dual-band patch antennas based on a CSRR. Good agreement between simulation, equivalent circuit model and experimental results is shown and discussed. These results lead the equivalent circuit model to become a simple and straightforward tool for the design of this type of multiband antennas, of low cost and versatile operation for a broad range of wireless communication systems.     

An effective approach for designing a low pressure DC glow discharge plasma reactor

Most plasma reactors are designed for research purposes and they are less appropriate for industry. To facilitate the engineering of an industrial reactor, an effective approach based only on the calculated Paschen curve, the simulation of the electric field and the breakdown reduced field is proposed. The results show that the experimental Paschen curve is different from the theoretical one; consequently the recalculation of the electric parameters is discussed. The experimental voltage/Current characteristic is used to identify the abnormal glow discharge regime and also to correlate the visual aspect of the discharge with its regimes.     

Research on Si-Al based catalysts prepared by complete liquid-phase method for DME synthesis in a slurry reactor

A series of Si-Al based DME synthesis catalysts were prepared by complete liquid-phase method and characterized by in situ XPS, XRD, N₂ adsorption and NH₃-TPD analyses. Based on the results, the addition of Si could adjust the pore structure and surface acidity of catalyst, exhibiting a strong promoting effect on the CO conversion and DME selectivity. However, when Si/Al ratio is higher, Si would cover active sites and increase the amount of strong acidity sites, causing the reduction in catalytic activity. It was found from in situ XPS characterization that Cu⁰ is the active center of methanol synthesis in DME production, and the addition of Si changes the chemical surroundings of active components and weaken the interaction between Cu, Zn and Al, which maybe give rise to the decrease in catalyst stability.     

连通的开口和闭口谐振环构成的磁超材料设计

在已有的磁超材料和左手材料结构中,负等效磁导率主要通过开口谐振环、平行短金属线对或者它们的变形结构来实现. 这些结构要求入射电磁波的电场方向平行于基板. 针对这一特点,利用将开口和闭口的谐振环相连通的思想,设计出了入射电磁波的电场方向垂直于基板型的三维磁超材料,并予以实验验证. 该对称结构中金属线线宽的变化对磁谐振频率影响很小,有利于实际的加工和应用. 同时,该结构对于设计三维以及具有极化无关、均匀各向同性等特点的磁超材料和左手材料具有参考价值. 关键词： 磁超材料 谐振环 电场方向