数字化变电站智能设备及网络在线监测与状态评估系统

针对面向数字化变电站智能设备及网络的在线监测与状态评估,研究了变电站网络故障源及故障机理,提出了将变电站通信网络故障分为通信背景层故障和应用层故障,以及变电站通信状态监视的内容,并研制了在线预警终端与子站两类装置;重点研究了预警终端与子站的信息建模和通信建模,以满足IEC61850的设计要求;讨论了预警终端、子站与控制中心主站之间的通信以及控制中心主站的功能设计。实际运行表明,该系统功能丰富,信息模型标准,集成规范,满足了智能变电站智能设备及网络的在线监测与状态评估的要求。     

智能牵引变电站建设方案研究

智能变电站在电力行业已逐步推广,而作为电气化铁路关键环节的牵引变电站在智能化方面尚未真正起步。针对智能牵引变电站研究及应用还比较滞后的问题,介绍了电气化铁路牵引变电站自动化系统现状及其存在的问题,分析了比传统变电站技术水平更先进的数字化变电站的优势及其局限性,对比了智能化变电站和数字化变电站的不同点;参考电力行业相关规范和标准,结合电气化铁路牵引变电站的特点,构建了智能牵引变电站的总体架构,给出了智能牵引变电站的网络结构及站控层、间隔层、过程层等各层的具体配置方案,提出了适合牵引变电站牵引变压器、断路器及高压组合电器等一次设备的智能化方案。该研究成果对开展智能牵引变电站理论及应用研究具有一定的参考价值。     

智能变电站线路保护测控装置应用设计

国内外变电站自动化系统的发展经历了传统集中式变电站、数字化变电站和智能化变电站三个阶段,随着我国网络通信技术和电力系统的发展,智能变电站开始普及。智能化变电站由过程层、间隔层、站控层三层结构构成,可节省二次电缆,实现信息共享,同时方便维护,调试更加方便。随着变电站智能化的发展,测控装置广泛应用于各个变电站中。本文分别论述了智能变电站和测控装置,探究分析了测控装置的设计特点以及设计技术,为智能化变电站设计提供了参考。     

VLAN技术在数字化变电站过程层网络中的应用

对VLAN技术进行了介绍。基于数字化变电站过程层通信网络结构、数据传输要求和VLAN的数据传输特性,重点分析如何将VLAN技术与数字化变电站技术相结合,工业化应用于过程层网络数据传输中,充分发挥VLAN的优势,保证过程层网络数据传输的快速、安全。     

IEC61850标准与数字化变电站设备

针对变电站通讯网络和系统的IEC61850标准,介绍了IEC61850标准的主要特点及数据建模,并分别从变电站的三个逻辑层面阐述实现开放式数字化变电站的设备及通讯方面的技术要求。     

OPNET在微网通信系统仿真中的应用

针对微网通信系统存在的实时性问题,将变电站自动化系统的全球通信标准IEC61850应用到微网通信系统中。建立了基于IEC61850标准的3层微网通信结构,并对微网中的通信业务进行了分析和建模,提出了利用网络仿真软件OPNET对微网通信系统的实时性进行仿真的方法。在OPNET网络仿真平台上,以系统的整体通信延时、保护和控制业务延时和不同节点的延时为研究对象,对采用两种不同链路速率(10 Mbit/s、100 Mbit/s)的微网通信延时进行了试验。研究结果表明,10 Mbit/s的链路带宽基本能满足微网通信系统的整体实时性能要求,但在网络业务流增多时某些业务易出现延时发散,而采用100 Mbit/s的通信链路能较好地全面满足微网通信系统的实时性要求,为微网通信系统带宽的选择以及其他业务的建模提供了一定的参考。     

变电站虚拟仿真教学系统关键技术研究与实现CSCD

针对现有变电站仿真系统现场感不足、学员体验度不高,场景中三维模型数量增加对系统的压力越来越大等缺点,提出一种变电站虚拟仿真教学系统方案,利用三维建模技术、虚拟现实技术及头戴式虚拟现实设备支持,以110kV变电站作为对象仿真,从视觉、听觉、交互方式和故障处理方面为学员建立了沉浸式变电站虚拟实境。其中,在简化率较高情况下模型的细节特征容易丢失,采用了一种基于QEM(quadric error metric)折叠代价改进的简化代价来保证模型的细节特征。实现了沉浸式变电站场景漫游、虚拟交互、故障处理功能,激发学习兴趣,提升教与学质量,具有很高的实用价值。     

变电站虚拟仿真教学系统关键技术研究与实现

针对现有变电站仿真系统现场感不足、学员体验度不高,场景中三维模型数量增加对系统的压力越来越大等缺点,提出一种变电站虚拟仿真教学系统方案,利用三维建模技术、虚拟现实技术及头戴式虚拟现实设备支持,以110kV变电站作为对象仿真,从视觉、听觉、交互方式和故障处理方面为学员建立了沉浸式变电站虚拟实境。其中,在简化率较高情况下模型的细节特征容易丢失,采用了一种基于QEM(quadric error metric)折叠代价改进的简化代价来保证模型的细节特征。实现了沉浸式变电站场景漫游、虚拟交互、故障处理功能,激发学习兴趣,提升教与学质量,具有很高的实用价值。     

基于BFD的OBS链路快速故障检测方案

目的：光突发交换（OBS）网络是一种实现全光因特网的富有前景的技术方案。由于OBS网络通常采用单向资源预留机制,一般的链路故障检测方法难以在OBS网络中使用,因此必须设计符合OBS数据传输机制的链路故障检测方案。方法：将双向转发检测（BFD）协议应用于OBS的故障检测机制中,并根据实际网络需要设定BFD报文的发送周期与检测时间,从而满足OBS网络快速故障检测的要求。以NSFNET为仿真网络,实现了业务流量发生器与节点故障发生器,对BFD在单链路场景与网络场景下的链路故障检测性能进行了仿真。结果：仿真结果表示：在单链路场景下,OBS网络平均丢包率小于0.001;在网络场景中,由于存在资源冲突、固定偏置时间等OBS网络自身的因素,OBS网络平均丢包率接近0.1。结论：因此,BFD是一种适合OBS网络的快速的链路故障检测协议。     

基于ADAMS的阀控非对称缸仿真研究

文章基于ADAMS,建立了阀控非对称缸的实体模型和液压系统,对其速比特性进行了分析并得出仿真结果;进一步对阀控非对称缸进行非线性建模,利用ADAMS与MATLAB对系统进行仿真,得到阀控非对称缸系统的动态及静态参数值。详细介绍了ADAMS与MATLAB联合仿真的建模过程及实现方法。     

Security Analysis and Improvement of Authentication Scheme Based on a One-way Hash Function and Diffie-Hellman Key Exchange Using Smart Card

A new authentication scheme based on a one-way hash function and Diffie-Hellman key exchange using smart card was proposed by Yoon et al.in 2005.They claimed that the proposed protocol is against password guessing attack.In this paper,the author demonstrate that Yoon's scheme is vulnerable to the off-line password guessing attack by using a stolen smart card and the DoS attack by computational load at the remote system.An improvement of Yoon's scheme to resist the above attacks is also proposed.     

Effect of Degree-of-Symmetry on Kinetostatic Characteristics of Flexure Mechanisms:A Comparative Case Study

The current research of kinetostatic characteristics in flexure mechanisms mainly focus on the improvement of accuracy. To reduce or eliminate the parasitic motion is considered as an approach by using the common knowledge of symmetry. However, there is no study on designing the flexure mechanisms with symmetrical features as many as possible for better kinetostatic performance, when considering the resulting cost by the symmetry. In this paper, the concept of degree of symmetry(DoS) is proposed for the first time, which is committed to symmetry design in the phase of conceptual design. A class of flexure mechanisms with 0?DoS, 1?DoS, 2?DoS and 3?DoS are synthesized respectively based on the Freedom and Constraint Topology method. Their overall compliance matrices in an analytical form formulated within the framework of the screw theory are used to analyze and compare the effect of different number of DoS on the kinetostatic characteristics for flexure mechanisms. The finite element analysis(FEA) simulations are implemented to verify the analytical results. These results show that the higher the DoS is, the smaller the parasitic motion error will be. The flexure model with 3?DoS is optimized according to the overall compliance matrix and then tested by using the FEA simulation. The testing result shows that with the best combination parameters, the parasitic motion error for 3?DoS mechanism is almost eliminated. This research introduces a design principle which can alleviate the unwanted parasitic motion for better accuracy.     

飞行汽车概念设计与气动特性分析

利用CFD软件Fluent,根据Spalart-Allmaras模型建立了飞行汽车外流场的三维湍流流动模型.通过数值模拟,得到飞行汽车在不同攻角下的升阻力系数变化规律.研究结果表明,在所选攻角范围内,随着攻角的增大,飞行汽车的升阻力系数不断增大,当攻角达到14＆#176;左右时,飞行汽车由于气流分离而发生失速.Fluent为飞行汽车的气动特性分析提供了重要依据.     

基于Pro/E与Simulink的Delta并联机器人运动仿真

针对"三自由度并联机器人的运动空间比传统六自由度并联机器人受到更多约束,以及其运动特性也更加复杂"的问题,将可视化运动仿真分析技术应用到并联机器人的研究上。以三自由度Delta并联机器人为例,在复杂轨迹下其整体位姿难以直观想象;为了便捷、高效地实现Delta并联机器人可视化运动仿真分析,结合SimMechanics Link接口软件,以Pro/E与Simulink/SimMechanics为仿真开发平台,提出了采用三维模型转换成SimMechanics模型的建模方法,并建立了SimMechanics模型,进行了仿真。研究结果表明,该方法能够直观地对Delta并联机器人进行可视化运动仿真分析,进而可为并联机器人机构的选型及优化、控制器的设计提供参考依据。     

车身冲压线中端拾器的仿真设计

介绍车身冲压线中端拾器的总体设计架构、建模、虚拟装配及其程序开发。该系统是基于C/S和B/S相结合的架构,采用VisualBasic.NET对CATIA进行二次开发,通过ADO访问数据库Oracle9i来建立的。而且,为了使计算机模型具有可扩充性和智能性,形成智能化的设计系统,对基于知识工程的计算机建模、参数化的虚拟装配进行了研究。     

CIM-OSA在ASP模式应用服务系统建模中的应用研究

针对ASP模式应用服务系统的建模特性 ,引入CIM OSA(ComputerIntegratedManufacturing OpennessSystemArchitec ture ,计算机集成制造开放系统体系结构 )作为系统建模过程的参考体系结构 ,同时扩展了一个过程视图。为确保视图之间的一致性和关联性 ,提出一个具有指导意义的模型化框架。     

Universal mechanism modeling method in virtual assembly environment

Motion simulation and performance analysis of mechanism are important methods for analyzing assembly quality after finishing assembly simulation in virtual assembly environment. However, most simulation systems have no function of mechanism motion simulation due to the randomicity of mechanism and lack of universal mechanism modeling method. In order to realize the simulation of any mechanism after finishing assembly simulation in a virtual environment, a new universal mechanism modeling method is presented. Two main models are contained in the mechanism model: information model and mathematical model. Firstly, the information model of mechanism is proposed to describe the data structure of mechanism which contains bottom geometry data, information of constraint, link, kinematic pair and physical data. Because the object of mechanism simulation is the assembly, which is assembled during the process of assembly simulation, the information of mechanism can be obtained automatically through mechanism automatic search method. Secondly, mathematical model of mechanism is presented. The mathematical model uses mathematical method to express the mechanism. In order to realize the automatic expression of any random mechanism, basic constraint library is presented, consequently random mechanism can be described based on the basic constraint library. Finally, two examples are introduced to validate the method in the prototype system named VAPP(Virtual Assembly Process Planning). The validation result shows that the mechanism modeling provides a universal modeling method for mechanism motion simulation in virtual assembly environment. This research has important effect on the development both of mechanism motion simulation and virtual assembly.     

Modeling and real time simulation of an HVDC inverter feeding a weak AC system based on commutation failure study

This paper presents modeling and study of 12-pulse HVDC (High Voltage Direct Current) based on real time simulation where the HVDC inverter is connected to a weak AC system. In goal to study the dynamic performance of the HVDC link, two serious kind of disturbance are applied at HVDC converters where the first one is the single phase to ground AC fault and the second one is the DC link to ground fault. The study is based on two different mode of analysis, which the first is to test the performance of the DC control and the second is focalized to study the effect of the protection function on the system behavior. This real time simulation considers the strength of the AC system to witch is connected and his relativity with the capacity of the DC link. The results obtained are validated by means of RT-lab platform using digital Real time simulator Hypersim (OP-5600), the results carried out show the effect of the DC control and the influence of the protection function to reduce the probability of commutation failures and also for helping inverter to take out from commutation failure even while the DC control fails to eliminate them.     

基于装配任务集的装配过程建模研究

反映产品装配的装配过程模型是装配仿真和装配评价的基础,基于单向顺序装配任务链的装配过程模型不能描述装配任务的层次结构和并行特性。简要分析了装配过程建模研究的现状,提出了产品层次信息模型及其实现方法,给出了装配任务的详细描述。基于装配任务的层次关系,提出了基于层次结构的装配任务集链来描述装配过程的方法。采用嵌套表技术,实现了基于层次结构的装配任务集链的存储与访问。采用层次结构的装配任务集链,给出了一个基于装配任务集的装配过程模型应用示例。     

基于RFID的牵引变电所防误系统设计

针对牵引变电所检修作业中的误操作问题,对自动识别防误机制、设备选型与开发、通讯链路和ASP.Net管理程序等方面进行了研究,对防止误操作的方法进行了归纳,提出了一种基于RFID技术以及Web Service技术的牵引变电所防误系统。该系统通过在现场终端采用RFID标签和PDA实现了对设备的自动识别、语音提示和过程控制,通过在通讯链路采用Wi-Fi和Web Service实现了任务数据交互,通过在服务器端采用Web应用程序实现了对任务信息全生命周期管理。研究结果表明,该系统能实现离线作业、自动识别、语音提示与报警等功能,能够有效防止人员误操作,并已成功应用于某牵引变电所。