GPRS在电力光缆在线监测与管理系统中的应用

电力光缆在线监测与管理系统需要必要的数据传送通道,采集光功率实时监测信息及对光开关进行控制。介绍了GPRS通信系统的工作原理及特点,讨论了GPRS网络系统作为电力光缆在线监测与管理系统数据采集和控制信息传输通道的意义,并提出了其实现方法。     

Crystalline and optical properties of PLZT films prepared by pulsed laser deposition

Abstract

The PLZT (3/66/34), PLZT (3/46/54), PLZT (9/65/35) and PLZT (28/0/100) thin films were deposited on MgO (100), Sapphire (0001) and fused silica substrates by using pulsed KrF excimer laser deposition technique. The conventional in-situ and 2-step heating processes were utilized to facilitate the synthesis of a large area of uniform PLZT thin film. Pure perovskite phase can be obtained only under very narrow process conditions, the highly textured PLZT films can be easily obtained by in-situ heating process. For PLZT (28/0/100) material, epitaxial films were successfully coated on MgO (100) substrates by 600°C in-situ and RTA 650°C 2-step heating processes. The latter was found to possess higher refractive index and lower extinction coefficient.     

光纤光栅测温系统在电力电缆温度在线监测中的应用

介绍了电力电缆温度在线监测系统目前的现状,光纤光栅测温系统的工作原理、主要技术指标及基于光纤光栅测温传感器的电力电缆温度在线监测系统在实际中的应用情况。     

集成色谱在线监测和真空断路器状态监测的SCADA系统

色谱在线监测技术是一门日益成熟的在线监测技术。真空断路器在线监测能够对火电厂的一些附属设备的开关量进行实时监测。SCADA系统是电力系统运行控制的核心。三者的集成对于电力系统的科学管理有着重要的意义。以华能上海石洞口第二电厂为例 ,探讨了三者集成问题。系统的实现对电力系统的信息优化组合 ,提高管理效率有着特别重要的意义     

基于脉冲激光的河道水位远程监测系统研究

水涝灾害的发生会严重影响河道周边人民生命安全和财产安全,及时准确掌握河道的水位变化十分重要。针对目前传统水位测量与监测方式的时效性、安全性等不足,设计了一种基于脉冲激光和云平台的水位远程监测系统。该测量装置以STM32单片机为核心,发射脉冲激光到测量桶内漂浮板,探测装置到水面漂浮板的距离,最终计算得出待监测的河道水位深度。实验室模拟实验结果表明:将测量装置固定在1m高度处,当水位深度在200mm~800mm时,相对误差小于1.7% ,变异系数小于1.2% 。经过无线传输模块可以实现对水位数据的实时上传,云平台能够准确显示水位及测量时间,表明该远程水位监测系统可行,能够实现对河道水位的远程实时监测,有一定的应用价值。     

An improved analysis of semiconductor laser dynamics under strong optical feedback

We present an improved theoretical model to analyze dynamics and operation of semiconductor lasers under optical feedback (OFB). The model is applicable for arbitrary strength of OFB ranging from weak to very strong. The model has been applied to investigate the dynamics and operation of lasers over wide ranges of OFB and injection current. An improved set of modified rate equations of lasers operating under OFB were proposed. We introduced a theoretical model to determine the power emitted from both the laser back facet and external reflector. The results showed that the operation of semiconductor lasers is classified into continuous wave, chaotic, and pulsing operations, depending on the operating conditions. The light versus current characteristics were examined in the operating regions of the classified operations. Under strong OFB, we predicted for the first time pulsing operation of lasers at injection currents well above the threshold. We observed the pulsing operation in experiments in good correspondence with the simulated results.     

Electrical and optical properties of microwave dielectric thin films prepared by pulsed laser deposition

Abstract

Bi₂(Zn_1/3Nb_2/3)₂O₇, BiZN, materials possess high dielectric constant and low loss factor in microwave frequency region. They have good potential for device application, especially in the form of thin films. However, the microwave dielectric properties of a thin film are very difficult to be accurately measured. Evaluation on the dielectric behavior of the films through the performance of the microstrip line devices made of these films involves metallic conduction and stray field losses. A novel measuring technique, which can directly evaluate the microwave dielectric properties of a thin film is thus urgently needed.

In this paper, BiZN thin films were grown on [100] MgO single crystal substrates using pulsed laser deposition process. The high-frequency dielectric properties of thus obtained thin films were determined using optical transmission spectroscopy (OTS). The [100] preferentially oriented films with pyrochlore structure can be obtained for the thin films deposited at 400–600°C substrate temperature under 0.1 mbar oxygen pressure. OTS measurements reveal that the index of refraction (n=1.95–2.35) and absorption coefficient (k=0.28x10^?4-2.25 × 10^?4 nm^?1) of the films vary insignificantly with the crystallinity of the BiZN films.     

SBN thin film growth by pulsed laser deposition and study of nonlinear optical properties

Abstract

Strontium barium niobate (Sr_xBa_1?xNb₂O₆) thin films were grown by PLD and characterized as to their structure, composition, and both linear and nonlinear optical properties. Attempted composition of very nearly x'0.61 was achieved, as shown within experimental error of RBS and PIXE techniques. Films deposited with high growth rates and at 700°C substrate temperature resulted polycrystalline on (001)-cut MgO and amorphous on fused silica, while those grown on MgO at lower growth rates were very well oriented with the substrate. A considerable blue shift in the absorption band edge was observed for the disordered SBN:61 films, compared to that for bulk SBN:61 crystal. A broad luminescence band was observed to occur, similar to that for bulk SBN. Degenerate four-wave-mixing techniques were used to study the nonlinear optical response of the amorphous films. A considerable enhancement, by 2 orders of magnitude, of the third order nonlinear susceptibility χ⁽³⁾ in transverse alignment was found to occur with respect to bulk values. A significant squeezing of the coherent response signal was observed in the SBN films.     

温度在线检测单元的设计

介绍一种以AT89C52单片机为核心的开关柜温度实时检测单元的工作原理，该检测单元利用红外温度传感器和V／F变换将开关柜被测点温度信号转变为适合单片机处理的脉冲信号，单片机对脉冲信号进行处理后可得到开关柜被测点温度值；实时显示温度值的变化情况，发现温度超限则给出报警信号。本检测单元可通过串行通信接口的实现与上位机的数据交换，有利于实现配电系统的网络化。     

收几组非典型容性设备绝缘在线监测数据的分析

在大量在线监测数据积累的基础上，提出了在线高压容性设备绝缘中出现的几种非典型现象，分析了一些影响在线绝缘参数的可能因素。最后指出依靠状态监测技术实现状态维修的可行性，对于那些无法排除的干扰因素，通过具体问题具体分析是完全可以得出正确的结论的．     

Effects of temperature on structural and optical properties of ZnMgO films fabricated by pulsed laser deposition

ZnMgO thin films have been deposited on Si(111) substrates by pulsed laser deposition (PLD) technique at growth temperature from 300 to 700°C in nitrogen ambient of 1.0 Pa. The effects of growth temperature on structural and optical properties of deposited ZnMgO thin films have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), infrared absorption (IR) spectra and photoluminescence (PL) spectra. The results of XRD and SEM analyses show that the film fabricated at 400°C possesses good crystallinity with hexagonal wurtzite structure and surface morphology. The Mg has been incorporated into ZnO in the form of substitutional Zn. The IR spectra reveal the typical absorption peaks of ZnMgO. The band-gap values have been obtained from 2.96 to 4.23 eV with increasing growth temperature. The PL spectra show that the highest UV emission is obtained at growth temperature of 600°C, and the obvious blue-shift is observed. This may be assigned as the change of the band-gap due to the increasing incorporation of Mg²⁺ ions with the increasing growth temperature.     

氧化锌避雷器阻性电流的在线监测

介绍了避雷器在线监测的几种常用方法,对阻性电流在线监测的原理和具体操作方法进行了详细的阐述,对可能出现的误差和干扰进行了解释并提出了解决的办法。     

Experimental and theoretical study of semiconductor laser dynamics due to filtered optical feedback

We report experimental results on the nonlinear dynamical response of a semiconductor laser subjected to time-delayed (>5 ns), frequency selective, optical feedback from a Fabry-Pe/spl acute/rot interferometer type of filter. Three regimes of interest, based on the relative value of the filter bandwidth with respect to the relevant laser parameters (relaxation oscillation frequency and external cavity mode spacing), are identified, viz. a wide filter case, an intermediate filter width case, and a narrow filter case. The dynamical response of the laser is shown to be quite different in each of these regimes. The principal results are 1) the laser's linewidth enhancement factor, coupled with the nonlinear response of the filter, can be exploited to induce nonlinear dynamics in the instantaneous optical frequency of the laser light on a time scale related to the time-delay of the feedback, 2) a mode mismatch effect which arises from a detuning between the filter center frequency and the nearest external cavity mode and manifests itself in a reduction of the maximum light available for feedback, and 3) a reduction in, or even disappearance of, relaxation oscillations in the laser dynamics when a filter of appropriate width is chosen. More generally, it is observed that certain dynamics that occur due to unfiltered optical feedback may be suppressed when the feedback light is spectrally filtered.     

高压断路器在线监测技术的研究

高压断路器是变电站中仅次于变压器的高压开关设备,起到控制和保护作用.本文介绍了状态检修机制的必要,阐述了作为状态检修机制基础的高压断路器在线监测技术推广的意义.文章重点介绍了高压断路器的机械性能监测、SF6气体综合监测、电气寿命监测、以及绝缘监测等四个部分的内容.文章还分析了高压断路器在线监测推广使用中存在的问题以及市场前景.     

调度电话线路在线监测系统的实现

分析了目前通信监测系统在对通信网进行监测中所存在的问题,并针对存在的不足提出了一套详细的解决方案,并详细论述了该方案的组成结构、特点、原理以及监测系统的工作过程。该监测系统的实现,对完善通信监测系统、及时发现调度电话的故障、提高工作效率将起到积极作用。     

输电线路在线监测系统的电源解决方案

目前在输电线路的自动化改造中,由于监测设备一般安装于野外,使得设备工作电源的获取和现有的低压监测设备有很大的不同.现阶段流行的光伏电源系统系统由于材料稳定性的原因,使其在使用上完全不能满足设备长期可靠工作的要求.针对目前几种主要的取能方案进行分析比较,在此基础上提出了一种以感应取能为基础的新电源解决方案,该方案不但在设计原理上克服了光能和风能取电的弱点,同时还克服了常规耦合取电方式中电源适应面过窄,使用寿命和使用范围受输电线路工作状态影响很大的问题.     

Advancements during the past quarter century in on-line monitoring of motor and generator winding insulation

Electrical insulation plays a critical role in the operation of motor and generator rotor and stator windings. Premature failure of the insulation can cost millions of dollars per day. With advancements in electronics, sensors, computers and software, tremendous progress has been made in the past 25 yr which has transformed on-line insulation monitoring from a rarely used and expensive tool, to the point where 50% of large utility generators in North America are now equipped for such monitoring. This review paper outlines the motivation for online monitoring, discusses the transition to today's technology, and describes the variety of methods now in use for rotor winding and stator winding monitoring.     

蓄电池剩余容量在线监测的探讨

实现蓄电池剩余容量在线实时监测,对提高直流系统的安全运行、提高供电系统的可靠性和自动化程度有着十分重要的意义.对现有的几种直流系统蓄电池容量测量方法如密度法、开路电压法、直流放电法和交流法等进行了比较分析,指出了它们的优缺点.提出了一种新的蓄电池剩余容量测量方法--交流纹波法.介绍了该测量方法的原理和具体实现过程.实际情况表明:该方法测量简单、精度高,具有良好的实用价值和推广意义.     

基于GSM的城市配电变压器在线监测系统

针对城市配电网负荷急剧增长导致配电变压器故障增多,从而造成配电变压器运行状态管理困难的问题,在分析城市配电变压器在线监测系统必要性的基础上,介绍了系统构成和终端设备电路设计。比较了多种配电网通信方式,分析了10kV系统网络方案,提出了基于全球移动通信系统GSM(Global System for Mobile communication)短信技术的配电变压器在线监测系统的设计方案,并完成了软、硬件的功能设计。     

变电站绝缘在线监测技术的研究与应用

介绍了HVM2000变电站高压设备状态监测系统的结构、工作原理和主要特点，在对大量在线监测数据进行较深入研究的基础上，分析了一些影响高压设备在线监测的因素，最后指出依靠状态监测技术实现状态维修是可行的。