输电线路运行常见故障原因分析与防治

输电线路是电力系统中最基本的组成部分。近年来,由于输电线路故障引发了多次大面积的停电事故。为避免或减少线路故障的发生,提高送电可靠率,需深入分析输电线路故障原因并制定不同防治措施。根据我国近年来输电线路故障跳闸类型及故障数据分析,总结了以下几方面故障原因,包括雷击、覆冰舞动、风偏放电、鸟害、污闪、山火等。本文重点分析了几类常见的输电线路故障跳闸原因,同时提出了有效的且具有针对性的防治措施,供输电线路运行维护人员参考。     

基于复频特性分析的输电线路故障监测方法

为了实现对输电线路的状态监测与故障诊断,提出了基于复频特性分析的输电线路故障监测方法。给定了分段传递函数及其模值的相对偏差的定义,针对输电线路故障的在线监测,建立了基于分段传递函数的故障分析方法,该分析方法的核心是以文中所定义的相对偏差作为反映输电线路状态的故障特征量。运用此方法对单条10kV架空输电线路进行了接地短路故障的仿真研究。仿真实验结果验证了该分析方法在输电线路故障监测中的有效性。     

输电线路常见故障分析与检测方法综述

在常年的使用过程中,用于电力传输的输电线路常常受到外界环境的影响,使得输电线路部件容易出现不同程度的破损,这给输电网络的安全运行带来了极大的挑战。对输电线路常见故障分析与检测方法进行研究。分析了输电线路中常见的部件故障类型,并调研了输电线路故障检测的代表性方法。其中,基于深度学习的检测方法在输电线路故障检测中扮演着重要的角色。最后指出了当前输电线路故障检测存在的困难点以及未来的发展趋势。     

高压交流输电线路故障检修技术研究

对高压交流输电线路故障检修技术进行研究,可以提高电力质量,减少因线路故障产生的一系列人财有损情况的发生;当前方法将短期的输电线路检修当作单重不确定性的优化问题,对其进行建模以及求解;而在现场运行过程中,架空线路可靠性指标不能准确表达线路故障发生的可能性,其理论基础相对薄弱,仅考虑了单重不确定性的问题,无法对高压交流输电线路进行高精度地检修;为此,提出一种基于层次分析的高压交流输电线路故障检修方法;该方法先将高压交流输电线路故障划分为:单相接地故障、高压交流输电线路短路故障、高压交流输电线路导线断路故障;然后利用多个电流测量点,通过FFT程序对电流故障分量相位进行求解,根据比较相邻测点相位差判别故障区域,最后利用图论实现高压交流输电线路故障检修时间控制函数,以及线路故障检修经济控制目标函数的制定,与分类和定位结果结合完成高压交流输电线路故障的检修;实验结果证明,所提方法可以有效地对高压交流输电线路故障进行检修,具有一定的利用价值。     

电网行波故障定位信息主站系统的组网应用

通过总结超高压公司贵阳局在输电线路故障查找和故障定位系统应用中存在的问题，根据现场实际应用需求，实施建立一套电网行波故障定位信息主站系统。该系统以超高压贵阳局所管辖线路为监测对象，以调度统一联系的变电站和输电线路运行维护部门为服务对象，直接从电力数据网获取相关站点数据，从而有效提高输电线路故障查找效率和运行维护水平。     

基于多源数据融合技术的输电线路安全监控研究

输电线路周边的环境较为复杂，以保障输电线路安全，防止输电线路故障产生为目的，研究基于多源数据融合技术的输电线路安全监控方法。在输电线路监控点设置不同类型传感器，采用分布式多点测量方式，获取输电线路监测数据。将同类传感器所采集的数据划分为两份，对每份数据实施自适应加权融合，利用加权融合算法对同类传感器数据实施一级加权融合；采用BP神经网络对数据一级融合结果进行二级融合，在确定输入层、隐含层、输出层节点数量与各函数后，通过数据训练获取全局融合结果，输出输电线路安全状态。实验结果表明，该方法在加权因子为0.3、隐含层节点数量为6的条件下，可获取最优监控结果，并显著降低输电线路故障率。     

基于图像处理的架空输电线路绝缘故障诊断方法

传统架空输电线路绝缘故障诊断方法以故障信号诊断为主,由于故障信号会受到噪声影响,导致线路绝缘故障诊断的准确性降低。针对此问题,提出基于图像处理的架空输电线路绝缘故障诊断方法。首先,基于图像处理提取架空输电线路绝缘故障特征,将架空输电线路绝缘故障图像进行灰度化、滤波、边缘检测等处理,并从中提取绝缘变化情况。其次,诊断输电线路绝缘故障类别,根据绝缘故障特征划分输电线路绝缘故障类别,确保线路绝缘故障诊断的有效性。最后,进行实验分析。实验结果表明,该方法的绝缘故障诊断准确性更高,优于对照组。     

山地环境输电线路故障分类及巡检措施分析

针对输电线路在山地环境运行过程中,由环境因素、气象条件和线路负荷等引起的故障,进而影响输电线路和电网稳定运行的问题.本文首先收集了历史运维数据,分析了引发输电线路故障的各种因素,选取特征参数并将其归一化,然后通过优化参数完成训练学习,最后建立了支持向量机故障分类模型.结果表明,该模型能够准确地对输电线路各种故障进行分类...     

基于改进型蚁群算法的输电线路故障测距模型研究

为了解决输电线路运行过程中容易出现的单相短路、两相接地、相间短路、三相短路等故障,构建一种基于改进型蚁群算法的输电线路故障测距模型,以实现输电线路故障测距优化。通过在常规蚁群算法的基础上优化寻优路径,以解耦方式消除三相线路中的互感作用。利用阻抗矩阵与导纳矩阵获取电力系统的相模矩阵。根据相模变化结合傅氏补偿算法,解决影响输电线路故障测距精度的多项因素,并以此为基础构建输电线路故障测距模型最优解。采用MATLAB仿真软件对所构建的模型进行了仿真试验。试验结果表明,所设计的模型受故障测距影响因素的影响较小,测距精度更高。该研究为后续的输电线路故障测距算法改进奠定了理论基础。     

基于集成神经网络的高压输电线路断线故障检测方法

常规的高压输电线路断线故障检测大多采用序电流比值原理设计而成,检测范围有限,断线故障检测定位百分比误差较大,检测精度较低。为解决该问题,本文引入集成神经网络,开展了基于集成神经网络的高压输电线路断线故障检测方法的研究。首先,利用冲击闪络采样方法采集高压输电线路断线故障数据。其次,基于集成神经网络原理,建立高压输电线路断线故障检测模型,输出断线故障识别代码。在此基础上,对断线故障代码对应的高压输电线路区段进行故障检测定位,实现断线故障检测目标。由实验分析可知,利用该方法检测线路断线故障,其故障检测定位百分比误差较小,检测精度显著提升。     

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.