Performance of Tense Thin-Film Torsion Bar for Large Rotation and Low-Voltage Driving of Micromirror

In this paper, a micromirror device is developed by realizing the large rotation with the low-voltage driving. The maximum rotation angles observed at 5 V are 8.6deg with hysteresis and 7deg with little hysteresis at the static condition. The thin-film torsion bars contribute to decrease in the torsional spring constant. The tension is included for maintaining the compliance in the rotation of the mirror and for increasing stiffness in other movements. The performance of the torsion bar is investigated. The observed hard-spring effect is significant and this can be explained by the combination of the tension and the vertical displacement of the torsion bar     

大型水轮机转轮立式静平衡工艺比较和分析

对国内大型水轮机转轮制造所采用的三种立式静平衡工艺进行了比较和分析,并提出一些需要进一步了解与处理的问题.     

Superresolution Digital Image Enhancement by Subpixel Image Translation With a Scanning Micromirror

This paper reports on a superresolution digital image enhancement technique using subpixel image translation with a scanning micromirror. We demonstrate that the spatial resolution of digital photomicrography, employing typical black-and-white pixelated image sensors, can be improved by acquiring multiple images with predetermined subpixel shifts and combining them with a superresolution image reconstruction algorithm. A two-axis gimbaled micromirror fabricated with a bulk-micromachining process is used to control the translational image displacements with subpixel accuracy     

大中型变压器用立式新型无励磁分接开关

简介了大中型变压器用无励磁分拉开关现有产品的技术特点,提出了开发新型立式无励磁分接开关的目标及措施,并简述了该开关的结构特点。     

A Varifocal Convex Micromirror Driven by a Bending Moment

A varifocal micromirror is designed and fabricated using silicon micromachining technology. A spherical convex surface of mirror is generated by applying a bending moment to the circumference of micromirror. This method is different from the conventional technique in which a distributed force is exerted on the central area of mirror. On the basis of the theory of materials strength, the deformation of a plate is purely spherical if only a bending moment is applied to the circumference. Spherical surface is well approximated to be a parabola if deflection is small. In order to generate only a bending moment, a force is applied to the plate in the region outside the fulcrum, by which the plate is supported freely in rotation. The proposed mirror was fabricated from a silicon on insulator wafer and a glass plate, which were connected by anodic bonding. The deviation in surface profile of mirror from a parabola was measured with an optical interferometer to be less than 4.7 nm rms in the mirror region inside the 400-mum-diameter fulcrum at the voltage lower than 215 V. The focal length of the fabricated mirror was varied from approximate infinity to 24 mm.     

一种适应大跨度电压变化的综合负荷静态模型

建立合理的综合负荷静态模型对电力系统静态电压稳定性分析具有重要意义．在对感应电动机静态电压特性进行动模实验和仿真分析的基础上,对综合负荷的静态电压特性进行了较深入全面的研究．提出了一种综合负荷静态模型．所提出的模型能合理地描述综合负荷在低电压运行条件下的静态行为,具有全电压范围适应性,对电力系统静态电压稳定性分析具有较大的理论和实用价值．     

灯泡贯流式水轮发电机转子支架立式静平衡工艺

介绍了灯泡贯流式水轮发电机转子支架静平衡工艺原理和工艺过程。     

大中型立式电动机(大附加轴向力)的轴承结构的研究

阐述了大附加轴向力稀油润滑的滚动轴承支承的立式电动机的轴承结构及其冷却方式、推力滑动轴承的轴承结构及其冷却方式,以及在设计轴承结构时需要考虑的技术要点。     

大型同步发电机静态励磁系统的最新技术应用

基于目前大中型同步发电机广泛采用静态励磁系统 ,该文针对静态励磁系统的特殊性 ,提出了关于系统配置、轴电压吸收、失脉冲检测、通讯及远程诊断等方面的最新技术 ,以满足日益提高的可靠性要求。     

大型静态变频器在燃气轮机中的应用

GE公司的S109FA联合循环机组所配套的静态变频器LS2100是一种专门用来将同步发电机作为电动机运行使之启动的一种大型变频装置。介绍了变频器的基本原理、硬件组成,以及在S109FA机组启动和运行中的实际应用情况。     

基于面向时间过程的静态安全分析

针对传统静态安全分析基于单一时间断面、无法细致反映系统状态变化的不足,本文提出了一种面向时间过程的静态安全分析方法。首先介绍了面向过程方法的基本概念。充分利用丰富的电力系统测量和负荷预测数据信息,提取了描述每个时间断面的特征向量;结合电力系统负荷连续变化的特点,通过改进的K-means聚类分析技术,对负荷曲线进行了时间过程的划分。定义了提取时间子过程最大特征断面和最小特征断面的指标,并对特征断面的显著代表性进行了研究。在保证电网安全稳定的前提下,本文方法可一定程度上提高传输线路的利用率。最后,IEEE30节点算例表明面向时间过程静态安全分析方法的合理性和有效性。     

Overload Alleviation With Preventive-Corrective Static Security Using Fuzzy Logic

This paper presents a concept overview of an automatic operator of electrical networks (AOEN) for real-time alleviation of component overloads and increase of system static loadability, based on state-estimator data only. The control used for this purpose is real-power generation rescheduling, although any other control input could fit the new framework. The key performance metrics are the vulnerability index of a generation unit (VIGS) and its sensitivity (SVIGS), accurately computed using a realistic ac power flow incorporating the AGC model (AGC-PF). Transmission overloads, vulnerability indices and their sensitivities with respect to generation control are translated into fuzzy-set notations to formulate, transparently, the relationships between incremental line flows and the active power output of each controllable generator. A fuzzy-rule-based system is formed to select the best controllers, their movement and step-size, so as to minimize the overall vulnerability of the generating system while eliminating overflows. The controller performance is illustrated on the IEEE 39-bus (New England) network and the three-area IEEE-RTS96 network subjected to severe line outage contingencies. A key result is that minimizing the proposed vulnerability metric in real-time results in increased substantial loadability (prevention) in addition to overload elimination (correction).      

大型电力系统静态电压稳定极限的求解

提出适用于大型电力系统电压稳定分析的改进连续潮流法,该算法能很好地克服大型电力系统的雅可比矩阵在照办点附近奇异的现象,从而使寻找电压临界点的工作变得迅速、准确、并且具有较好的收敛性;阐述发电机无功越限对静态电压稳定性的影响;试验验证取得了满意的结果。     

巴基斯坦Guddu电厂单桩竖向抗压静载试验研究

<正>桩基础的承载力与所在土层有性质直接关系,在设计过程中,通过地质勘察资料中的地层参数计算的单桩承载力只是理论值,跟实际值往往有一定差距,因此,在设计之前必须通过现场试验得到真实的单桩承载力以对理论值进行校核,如此才能得到适合工程需要的设计值,才能进行下一步设计。     

大规模风电接入新疆电网静态电压稳定性分析

介绍了含风电接入的电网静态电压稳定性分析机理.基于连续潮流计算,采用DPL仿真语言编程,应用P-V曲线法分析了含风电场的地区电网电压稳定.对基于普通异步风力发电机组、双馈风力发电机组和直驱风力发电机组风电场接入系统后系统的静态电压稳定性进行了分析比较.     

适应大扰动的电力系统戴维南等值参数跟踪算法

针对现有的戴维南等值参数跟踪算法需要假设2个计算时步之间戴维南等值参数不变、不能适应等值系统内部发生扰动等问题,提出了一种可以适应系统内部出现大扰动的戴维南等值参数跟踪算法。该算法利用本地测量信息,主要解决了现有算法不能适应等值系统内部发生大扰动时戴维南等值参数计算问题,跟踪算法利用故障前的戴维南等值参数计算出故障时刻的等值电压源幅值,然后以故障前一时刻的等值电阻和故障时刻的等值电压源幅值作为初值,计算出故障时刻的其他戴维南等值参数,从而再求出故障后各个时刻的戴维南等值参数。该算法的优势在于仅利用负荷母线局部电气量就可以快速、准确、实时地求取戴维南等值参数,而且也适用于等值系统内部发生三相短路的情况,同时该算法具有计算结果误差小的优点。最后,通过IEEE 30和IEEE 39节点标准测试系统验证了本算法的准确性。     

大中型立式电机的卧式试验

通过对筋外冷立式电机的轴承结构分析,采用给角接触轴承轴向施加合适的预紧力,使其在合理的工况下运行,以实现立式电机卧式放置并直接施加负载进行型式试验。试验结果表明,采用此种方法进行试验是可行的,为同类结构电机的负载试验提供参考。     

大型立式变频凝泵某转速下振动大原因分析处理

某330 MW机组凝泵采用变频调节控制方式,在频率39 Hz时电机端振动达200μm,严重超国家标准。经分析排除了联轴器松动、轴承缺陷、转子质量不平衡等因素,认为振动大主要由共振原因引起。应用动平衡方法处理,解决了电厂多次检修未果的问题,为类似故障处理提供了处理方法。     

飞行机电作动系统故障诊断技术综述

飞行机电作动系统故障诊断技术对提高航空器作动系统的可靠性、保证航空器安全运行具有非常重要的意义.基于故障诊断技术在飞行机电作动系统应用中遇到的问题和挑战,首先介绍了飞行机电作动系统故障诊断技术的研究现状与意义.其次,特别关注了新颖故障、闭环控制对故障诊断技术发展的限制,以及故障诊断技术审定与验证的挑战.最后,探讨了飞行...     

同步电动机起动的分析与计算

:通过对起动过程和同步牵入的理论分析 ,从满足实际工程计算精度的要求出发 ,结合实际工作经验 ,介绍了同步电动机起动的实用计算方法 .该方法也可供对同步电动机牵引其它类型负载的起动计算时参考 .