变压器内部故障判断与分析

掌握溶解于变压器油中气体的组分、浓度。及油和固体材料产生气体成分,简要介绍不同故障产生不同含量气体,通过比较检测进一步掌握变压器内部存在故障,正确分析诊断及遏制事故扩大。     

一种模拟退火小波网络的电力变压器故障诊断

关于电力变压器是电力系统的主要设备,变压器故障是危及电网安全的主要因素.在传统的故障诊断方法中,存在着易陷入局部最小和对初值依赖性较高的缺陷.根据油中溶解气体的故障诊断技术,为了准确及时检测电力变压器故障,提出对油中溶解的气体(H2,CH14,C2H2,C2H4,C2H6等)采用小波神经网络模型进行分析,对电力变压器进行故障诊断,同时引入了模拟退火算法对模型进行了结构和参数的优化,加快了训练收敛速度,避免了陷入局部极小值.进行仿真,结果表明了改进方法的有效性.     

基于光声光谱的变压器油中溶解气体监测系统

油中溶解气体分析技术可有效发现变压器的潜在故障,设计的基于气体光声光谱检测原理的变压器油中溶解气体检测系统,可对溶解于变压器绝缘油中的CO和CO2的体积分数进行检测.系统采用红外光源,窄带滤光片,小体积非共振式光声池与驻极体麦克风进行测量,其中斩波器的调制频率为15Hz,其对CO体积分数测量的极限灵敏度为3 ×10-6,对CO2的体积分数测量的极限灵敏度为10×10-6.该系统在满足变压器油中溶解气体分析与判断导则的同时,拓展了变压器油中溶解气体的测量手段,对维护变压器安全运行具有积极意义.     

变压器油中溶解气体色谱分析误差来源及排除

变压器油中溶解气体色谱分析法是诊断变压器及充油电力设备内部潜伏性故障的重要手段。本文论述生产一线现场工作中色谱分析时各种误差产生的原因,排除方法及建议。     

安徽电网变压器油中溶解气体在线监测管理系统的设计与实现

随着电网规模不断增大,电力系统的安全稳定问题趋于更加复杂,为保证电网稳定运行,对变压器工作状态的监视与管理提出了更高要求.该文针对安徽电网目前对变压器监视的实际情况,设计一套针对变压器油中溶解的气体含量进行监测、分析的管理系统,从而及时发现变压器存在或潜在的故障,确保电网的安全稳定运行.     

基于WSN和数据融合技术的电力变压器故障诊断系统的研究

探讨一种基于数据融合和可拓理论的电力变压器故障诊断方法,基于此方法,应用无线传感器网络技术和.NET开发平台构建和开发出一套电力变压器故障诊断系统。该系统将WSN技术用于电力变压器油中溶解气体的无线数据采集,实现变压器油中溶解气体的实时数据采集和传送;同时运用信息融合技术对数据进行优化处理,既可以降低网络能耗又保证了数据的准确和客观;在变压器进行故障诊断时,针对现有电力变压器故障诊断的气体比值法存在的编码规则不完整、诊断故障类型单一等缺陷,使用可拓诊断方法,定量与定性相结合,使变压器故障诊断方法更为精细化。在线故障诊断可视化系统可以实现变压器油中溶解气体参数的采集、显示、分析、存储和回放等功能,实现对变压器故障信息的实时分析与自动诊断,既解决了作业人员远程实时监测变压器运行状态问题,又大大提高了变压器故障诊断的性能,为变压器在线监测和故障诊断技术提供新的发展方向。     

安徽电网变压器油中溶解气体在线监测系统的研制与建设

变压器油中溶解气体在线监测装置能够提前发现变压器内部存在的潜伏性故障并可随时掌握故障的发展情况,提高了变压器的状态监测的智能化水平。但长期以来,在线监测装置厂家众多,规约不统一,无法形成一套完整的,实用的监测系统,将现场的监测数据实时的传递到主站,便于工作人员进行故障分析与决策。结合安徽省油色谱在线监测系统的建设经验,介绍了一套新型的在线监测系统,该系统统一了规约,可以无缝融入一次设备状态监测系统中,具有极强的实用性和扩展性。     

基于光声光谱技术的变压器故障在线监测系统设计

长期运行中和发生故障后的油浸电力变压器其绝缘油及有机绝缘材料会分解出一些对判断故障类型甚至故障部位有价值的气体,分析变压器油中溶解的这些气体是判断电力变压器早期潜伏性故障有效的措施之一,针对传统的变压器油中故障气体气相色谱分析存在的问题,提出利用光声光谱技术设计变压器油中故障特征气体的在线监测系统,实现变压器的真正在线实时监测及故障诊断,对系统设计中的几项关键技术采用了新方法,为变压器故障的在线监测实现了技术创新。     

基于支持向量机的变压器故障诊断方法研究

变压器作为电网核心装备,对其故障类型做出准确的诊断是电网安全运行的基础.当前主要针对变压器油中溶解的气体进行故障诊断,本文利用支持向量机(SVM)在小样本数据条件下下仍能解决非线性和局部极小点等问题的优点,提出了基于SVM的变压器故障诊断模型.     

基于知识库的电力变压器故障诊断专家系统

针对电力变压器故障机理复杂多样的特征,提出了基于知识库为核心的电力变压器故障诊断专家系统,建立了以油中溶解气体分析(DGA)知识库、绝缘系统检测知识库及油中微水含量检测知识库三个知识库信息融合的故障确诊策略;其中,针对油中溶解气体分析知识库中知识量大的特征,使用规则置信度对一条故障信息可匹配多条规则知识的情况进行冲突消减;根据电力变压器故障种类概率呈现中间大两头小的特点,建立动态知识库模型以存入变压器近期故障,推理机进行推理时首先扫描动态知识库。在建立数据库的各个数据表时,通过设定主键和外键约束以使推理机推理更高效;实验结果表明,该专家系统在检测变压器故障时表现出了较高的准确率和较高的诊断速率。     

Only connect: teaching, technology and telesis

Abstract This paper describes an approach to the design of interactive multimedia materials being developed in a European Community project. The developmental process is seen as a dialogue between technologists and teachers. This dialogue is often problematic because of the differences in training, experience and culture between them. Conditions needed for fruitful dialogue are described and the generic model for learning design used in the project is explained.     

European Community policy and the market

Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven.     

一种自适应子融合集成多分类器方法

融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。     

Avoiding semantic and temporal gaps in developing software intensive systems

Development of software intensive systems (systems) in practice involves a series of self-contained phases for the lifecycle of a system. Semantic and temporal gaps, which occur among phases and among developer disciplines within and across phases, hinder the ongoing development of a system because of the interdependencies among phases and among disciplines. Such gaps are magnified among systems that are developed at different times by different development teams, which may limit reuse of artifacts of systems development and interoperability among the systems. This article discusses such gaps and a systems development process for avoiding them.     

Designing economic np control charts: A programmed simulation approach

This paper presents control charts models and the necessary simulation software for the location of economic values of the control parameters. The simulation program is written in FORTRAN, requires only 10K of main storage, and can run on most mini and micro computers. Two models are presented - one describes the process when it is operating at full capacity and the other when the process is operating under capacity. The models allow the product quality to deteriorate to a further level before an existing out-of-control state is detected, and they can also be used in situations where no prior knowledge exists of the out-of-control causes and the resulting proportion defectives.     

The development of robot art

Going through a few examples of robot artists who are recognized worldwide, we try to analyze the deepest meaning of what is called “robot art” and the related art field definition. We also try to highlight its well-marked borders, such as kinetic sculptures, kinetic art, cyber art, and cyberpunk. A brief excursion into the importance of the context, the message, and its semiotics is also provided, case by case, together with a few hints on the history of this discipline in the light of an artistic perspective. Therefore, the aim of this article is to try to summarize the main characteristics that might classify robot art as a unique and innovative discipline, and to track down some of the principles by which a robotic artifact can or cannot be considered an art piece in terms of social, cultural, and strictly artistic interest. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

Explanation and prediction: an architecture for default and abductive reasoning

Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given.     

Three Process Perspectives: Organizations, Teams, and People

This paper provides the author's personal views and perspectives on software process improvement. Starting with his first work on technology assessment in IBM over 20 years ago, Watts Humphrey describes the process improvement work he has been directly involved in. This includes the development of the early process assessment methods, the original design of the CMM, and the introduction of the Personal Software Process (PSP)^SM and Team Software Process (TSP){^SM}. In addition to describing the original motivation for this work, the author also reviews many of the problems he and his associates encountered and why they solved them the way they did. He also comments on the outstanding issues and likely directions for future work. Finally, this work has built on the experiences and contributions of many people. Mr. Humphrey only describes work that he was personally involved in and he names many of the key contributors. However, so many people have been involved in this work that a full list of the important participants would be impractical.     

基于复小波噪声方差显著修正的SAR图像去噪

提出了一种基于复小波域统计建模与噪声方差估计显著性修正相结合的合成孔径雷达(Synthetic Aperture Radar,SAR)图像斑点噪声滤波方法。该方法首先通过对数变换将乘性噪声模型转化为加性噪声模型,然后对变换后的图像进行双树复小波变换(Dualtree Complex Wavelet Transform,DCWT),并对复数小波系数的统计分布进行建模。在此先验分布的基础上,通过运用贝叶斯估计方法从含噪系数中恢复原始系数,达到滤除噪声的目的。实验结果表明该方法在去除噪声的同时保留了图像的细节信息,取得了很好的降噪效果。     

How do children do mathematics with LOGO?

Abstract  This paper considers some results of a study designed to investigate the kinds of mathematical activity undertaken by children (aged between 8 and 11) as they learned to program in LOGO. A model of learning modes is proposed, which attempts to describe the ways in which children used and acquired understanding of the programming/mathematical concepts involved. The remainder of the paper is concerned with discussing the validity and limitations of the model, and its implications for further research and curriculum development.