一种新的柔性直流输电系统远端启动策略

模块化多电平换流器(MMC)的启动是MMC柔性直流输电系统工程应用首先需要面临的问题,针对采用MMC结构的两端或者多端柔性直流输电系统,提出了一种新型的有序解锁启动方法,以减少传统充电方式下换流阀解锁瞬间的直流电压跌落和桥臂电流冲击。该方法在传统不控充电过程后,先解锁定直流电压换流站,再对其他换流站进行远端充电,期间其他换流站的桥臂按其子模块电容电压高低顺序逐步减少投入充电的子模块个数,以此不断抬高子模块电容电压,在电容电压到达一定数值后再解锁换流站。通过理论分析计算了本方法最大的电压跌落,并通过PSCAD/EMTDC仿真验证了该方法的有效性和优越性。此外,新的远端启动控制策略对多端柔性直流系统的定功率换流站启动顺序和启动时刻没有特殊要求,并针对单桥臂进行设计,可以重复应用于各桥臂,因此,其适用于实际工程中的多端柔性直流系统远端启动和交流系统故障造成无源端闭锁后的在线重启动。     

Microwave Dielectric Mechanism Studied by Microwave Near-Field Microscopy and Raman Spectroscopy

Microwave dielectric ceramics such as Ba(Mg_1/3Ta_2/3)O₃ and Ba₂Ti₉O₂₀ possess high dielectric constant and low dielectric loss in microwave frequency regime and have tremendous potential for device applications. In these materials, the presence of extrinsic defects, such as secondary phases, usually altered the microwave dielectric properties of the materials markedly, but the correlation of the microwave dielectric response of the materials with their microstructure has not been fully understood due to the lack of dielectric response in the local area. In this article, microwave near-field microscopy and Raman spectroscopy were used to investigate the microwave dielectric mechanism, viz. we measured the microwave dielectric properties of the materials in micron region by using a evanescent microwave probe (EMP) and, at the same time, examined the lattice vibration characteristics of the region by using a micro-Raman spectrum. How the presence of the secondary phase affects the microwave dielectric properties of the materials is thus systematically investigated. The causes of intrinsic or extrinsic dielectric loss were explored by comparing the dielectric images in SEMP at microwave frequencies and the corresponding Raman Spectra.     

SF6及其分解产物SO2的拉曼光谱检测试验研究*

通过检测GIS中SF6及其分解气体组分,可检测到GIS内部存在的潜在性缺陷,对保障GIS设备的可靠运行具有重要意义.基于频率锁定腔增强技术,将激光耦合到V形谐振腔中,搭建了光反馈频率锁定V型腔增强平台,实现了拉曼信号的增强.开展了SF6及其主要分解组分SO2气体的拉曼光谱检测研究,得到了SF6气体的拉曼特征峰位于774 cm-1,SO2气体的拉曼特征峰位于1151 cm-1;对SF6气体的检测下限达到了13.2 Pa,对SO2气体的检测下限达到了25.6 Pa.SF6的拉曼特征峰线宽极窄,说明拉曼光谱在抗交叉干扰上具有极大的潜力.通过对不同压强、不同激光功率与不同温度下的SO2气体进行拉曼光谱试验分析,发现SO2气体的拉曼特征峰强度与气体压强、激光功率、温度之间高度线性相关.这项研究为拉曼光谱法对SF6分解气体成分的检测和定量分析奠定了基础,表明拉曼光谱法在SF6分解气体成分检测领域具有巨大的潜力.     

变压器油中溶解微量糠醛的激光拉曼光谱检测方法

研究变压器油中溶解微量糠醛含量的检测方法及其应用,对运行变压器油纸绝缘老化评估具有重要意义。激光拉曼光谱(LRS)技术作为微量液体检测的有效手段,已经在很多领域得到了广泛应用。本文应用Gaussian 09W程序构建了糠醛分子仿真模型,分析其拉曼振动特性,进而证明了拉曼光谱检测糠醛分子的可行性;应用共聚焦拉曼技术搭建了激光拉曼光谱液体检测试验平台;结合萃取技术研究了糠醛分子的拉曼光谱检测特性,建立了基于特征频谱和最小二乘法对糠醛含量进行定量检测的方法。最后,应用激光拉曼光谱方法对不同糠醛含量的变压器油样进行检测,并与实验室高效液相色谱法(HPLC)的检测结果进行对比,对比结果表明:结合萃取技术的激光拉曼光谱能有效地对变压器油中溶解微量糠醛进行定量检测,为实现变压器油中糠醛含量的快速检测提供了一种方法。     

基于拉曼光谱技术直接检测矿物绝缘油中糠醛含量方法

本文中作者提出了利用拉曼光谱技术对绝缘油中糠醛含量进行检测研究,实验检测纯绝缘油、纯糠醛和糠醛-绝缘油溶液的拉曼光谱.对不同浓度的糠醛溶液进行了原位测试,建立峰面积比与浓度的函数关系.     

氮掺杂氟化非晶碳薄膜的拉曼光谱结构研究

以CF4、CH4和N2的混合气体为源气体,采用PECVD技术,在不同源气体流量比下制备了α-C:F:N薄膜。对制备的薄膜进行了真空退火处理,并对退火前后的薄膜进行了拉曼结构分析。拉曼分析表明:α-C:F:N薄膜是由sp2和sp3混合结构组成的非晶碳薄膜;随源气体流量比的增大,α-C:F:N薄膜中sp2键的含量增加,交联结构加强,薄膜的热稳定性得到提高;对低流量比下沉积的薄膜,退火处理可以提高其热稳定性。     

小区电力远程智能管理控制系统研究——防盗电灵活接线系统

文章提出配电接线系统综合布线思想,完成了系统主要部件的功能设计和电气设计。该接线系统与武汉供电公司多用户电能集中检测控制器配合使用,较好地解决了防窃电和消除配电接线火灾隐患难题。接线系统施工方便,降低了工程造价。     

Raman amplifiers for telecommunications

Raman amplifiers are being deployed in almost every new long-haul and ultralong-haul fiber-optic transmission systems, making them one of the first widely commercialized nonlinear optical devices in telecommunications. This paper reviews some of the technical reasons behind the wide-spread acceptance of Raman technology. Distributed Raman amplifiers improve the noise figure and reduce the nonlinear penalty of fiber systems, allowing for longer amplifier spans, higher bit rates, closer channel spacing, and operation near the zero-dispersion wavelength. Lumped or discrete Raman amplifiers are primarily used to increase the capacity of fiber-optic networks, opening up new wavelength windows for wavelength-division multiplexing such as the 1300 nm, 1400 nm, or short-wavelength S-band. As an example, using a cascade of S-band lumped amplifiers, a 20-channel, OC-192 system is shown that propagates over 867 km of standard, single-mode fiber. Raman amplifiers provide a simple single platform for long-haul and ultralong-haul amplifier needs and, therefore, should see a wide range of deployment in the next few years     

基于远程桌面的厂站自动化系统远程维护

变电站普遍采用了无人值班运行模式,文中介绍了一种基于当地监控机和远程桌面的灵活实用的远程维护方案,利用计算机技术和调度自动化通信技术,远程控制具有维护功能的监控机,实现变电站站内自动化系统的远程维护.     

可扩展多输入多输出信道高效模拟器研制

针对现有信道模拟器通道规模受限、扩展性差等缺陷,设计实现了一种可扩展的多输入多输出(multiply-input multiply-output, MIMO)信道高效模拟器。 该模拟器采用改进的坐标旋转数字计算(coordinate rotation digital computer, CORDIC)算法,只 需较少硬件资源便可实现大规模多支路的随机信道衰落精确模拟。 基于 MIMO 信道离散化模型提出了一种可扩展的硬件模拟 架构,并结合现场可编程门阵列(field-programmable gate array, FPGA)的并行处理优势,进行硬件实现及实测验证。 针对 3GPP 标准扩展车载 A 信道模型(extended vehicular A model, EVA)静态场景和时变场景的实测结果表明,所研制的 MIMO 信道模拟 器输出时延功率谱和多普勒功率谱等统计特性均与理论值吻合,可用于无线通信设备的方案验证、算法优化和性能分析。     

Field-Filter Probes and the Measurement of Alternating-Current Corona

The principles of the field-filter probe, which is capable of measuring both field changes and conduction current at an electrode in the presence of space charge, are described. Design characteristics are given for a simple field filter and for two further types which can be used for bipolar (reversing) fields and currents. Measurements are given for the discharge characteristics at the plane electrode of rod-plane gaps in the range 50-300 mm subjected to alternating voltages up to 100 kV root mean square (rms).     

基于KVM、远程桌面和VPN的数据机房远程维护

介绍了一种基于KVM、远程桌面和VPN的数据中心机房远程维护方案,借助计算机技术和调度自动化通信技术以及利用KVM技术为机房主机设备的集中监控管理提供方便可靠的管理模式,在公网中利用VPN技术通过远程桌面技术远程控制电力公司内网中KVM用户工作站,实现数据中心机房的远程维护,为电网调度自动化系统的可靠运行提供技术保障。     

传统电气闭锁与微机保护问题的探讨

介绍对现有变电站的传统二次电气控制闭锁回路以及现代微机防闭锁方式的原理、功能、技术发展等相关问题的研究探讨情况,对一些技术问题提出了自己的见解。     

面向需求响应业务的灵活弹性传输策略

随着需求响应(demand response,DR)不断深化实践,未来需要依靠高可靠的信息交互支撑精细化的DR控制.然而在DR无线通信场景下,复杂的信道环境极大影响DR高效的信息交互,现有技术难以匹配和满足DR业务的特性.针对DR无线传输中的信道质量问题,设计了面向DR业务的灵活弹性传输策略,该策略通过自适应编码实现....     

灵活的5G波形及超宽带信号生成和分析测试系统

目前5G技术研究遇到的一大挑战是：需要对太多的波形、频率和带宽加以分析。除了6 GHz以下频率的波形之外,还包括微波和毫米波频率的波形。有的波形可能还涉及到大带宽。所有这些因素对5G信号的生成和分析提出了新的测试挑战,因此灵活性是当今5G研究的关键要求。本文将讨论部分候选波形,并介绍一款创新和灵活的、适用于5G波形生成和分析的测试台。该测试系统将软件解决方案和测试设备完美结合起来,通过仿真前沿的5G波形应用场景来执行“假设－分析”研究。文中还将分析候选5G波形与4G波形共存的场景,并将讨论微波和毫米波频段、调制带宽高达2 GHz的宽带信号生成和分析案例。     

Flexible Communication and Control Protocol for Injectable Neuromuscular Interfaces

BION2 is a system based on injectable neuromuscular implants whose main goal is to restore the functional movement of paralyzed limbs. To achieve this objective, the functional requirements of the implanted interfaces include not only stimulation but also integrated sensors in order to detect patient intention, to provide servocontrol of muscle activation and to sense posture to inform more global motor planning and coordination. The technical constraints for managing the system include the efficient use of forward and reverse telemetry channels with limited capacity, minimization of adverse consequences from errors in data transmission or intermittent loss of power to the implants, and ability to adjust stimulation rates and phases to achieve efficient fine control of muscle force while minimizing fatigue. This paper describes a communication and control architecture with several novel features that address these requirements     

一种柔性直流子模块测试装置的研制及应用

本文针对柔直输电系统缺乏调试手段的现状,提出一种用于模块化多电平柔直子模块自动调试的方法,设计了一种测试装置,包括管理单元、模块化多电平换流器(MMC)控制模拟单元、采集单元和能量输出单元。能量输出单元给子模块供电,MMC控制模拟单元模拟阀控协议控制子模块功能测试,采集单元采集子模块相关的电压状态,管理单元结合采集信息和通信状态信息共同辅助测试判断,从而完成柔直输电系统子模块的自动调试,工程实际表明该方法完全适用于现场验收测试以及出厂调试的需要。     

Flexible Laminates: Key Insulation for Motors and Generators

The use of flexible laminates (the bonding together of two or more flexible substrates to form a thin, strong insulation material) as a key insulation source for motors and generators is explained.     

Remote Laboratories for Optical Circuits

This paper presents a remote laboratory implementation for an optical circuits course. The process from design and implementation towards assessment and continuous improvement phase is outlined. The design of the experiments involved the research on remote access technology and the investigation of best practices for an experimental setup. The first pilot implementations were used to determine the possible shortfalls during an ldquoIntroduction to an Optical Communicationsrdquo course in fall 2004 at the University of Colorado, Boulder, and an ldquoOptical Circuitsrdquo course in fall 2005 at the University of Houston, Houston, TX. After improvements, two experiments were pilot tested during spring 2006 at the University of Houston. Assessment of learning outcomes and teaching methods were performed. The remote access methods, in addition to the delivery of the class and lectures, are presented in the paper. Delivery of a class with remote laboratories and videotaped lectures are also outlined under future directions of this project.     

远程电机转速检测与控制

介绍了一套基于红外通信的远程电机转速检测与控制装置.该装置主要分为两个模块:电机模块和控制模块.电机模块可实时检测电机转速值,并根据控制模块发送过来的脉宽调制(PWM)信号控制电机的转速;控制模块将电机模块发送过来的电机转速信号跟设定转速值进行PID运算并返回PWM信号,通过红外通信将该信号发送给电机模块.通过不断调整使得电机的转速最终稳定在设定转速值.