分相式断路器失灵保护的现场应用及调试方法探讨

断路器失灵是电力系统重大事故,其保护配置和现场试验要求安全可靠。文章就断路器失灵保护在500kV系统一个半断路器主接线方式和220kV系统双母线主接线方式中应用的启动方式、回路连接、动作逻辑及功能特点做出分析,提出增加保护可靠性的几点措施。分析对比500kV系统母线侧断路器失灵保护的两种配置模式,提出相应应用特点,同时总结失灵保护现场试验方法和验收校验失灵启动回路时的安全措施,尽量降低失灵保护现场工作的风险。     

直流消失后开关继续能保持动作的方案探讨

通过对多起变电站因直流消失导致断路器保护不能正确动作、故障点不能及时切除引起事故扩大、设备烧损的分析,考虑从断路器改造着手解决这一问题。通过在断路器机构内加装一套保护来准确判别故障电流,利用故障电流实现自能脱扣分闸。提出了解决方法,以便及时切断故障,保护变电站设备和电网,防止事故扩大。     

基于DSP2407的断路器机械特性在线监测系统

本文介绍了基于TMS32OF2407DSP的真空断路器断路器机械特性在线监测系统的研制与开发.对系统构成、硬件纽成和软件设计作了详细说明.现场试验表明该系统较好实现了测量、保护、监控与通信等功能I具有广阔的应用前景.     

试论断路器在低压配电系统应用中的选择

随着近年来断路器的广泛应用,断路器在低压配电系统的各级馈出线上,是配电输出和安全保护的关键。本文从低压断路器过流脱扣额定电流的选择及保护特性的选择等方面进行了分析。供大家参考。     

政平换流站最后断路器保护系统优化

文章介绍了政平换流站的交流系统,分析了最后断路器保护系统的原理,并针对政平换流站的换流器和线路最后断路器保护系统存在的问题提出了改进和完善建议。     

CFW45系列智能型万能式断路器在低压配电系统中的应用研究

本文针对传统的低压断路器所存在的问题,研究了新型CFW45系列智能型万能式断路器,这种断路器具有故障判断准确、灵敏度高、选择性好、小型化、智能化保护功能,能避免不必要的停电,提高供电的可靠性,同时还带有通讯接口,具有“四遥”功能,以满足控制中心和自动化系统的要求,目前的应用越来越广泛。文中研究了CFW45系列智能型万能式断路器的功能,控制原理,主要技术参数及选型,未来的发展方向,并对智能控制器的保护特性与选择应用进行了研究。     

SPD后备保护装置——断路器、熔断器设计选用浅析

本文着重分析了用断路器、熔断器两种保护元件的不同特性。就SPD前端保护元件的选择和保护整定问题进行了研究。     

关于一起直流电源故障分析及预防措施

我段管内配电所已广泛采用了微机保护及综合自动化系统,并配套安装了智能高频开关直流电源系统.随着设备的安装投运,智能高频开关直流电源系统带来的问题多次影响了铁路电力供电的安全,现对一起由直流电源引起的断路器拒动故障进行分析,以期引起重视.     

建筑配电设计问题分析

低压断路器具有断路保护、过载保护、控制和隔离的功能,适用于工业与民用建筑终端低压配电系统,在低压配电系统中广泛采用.低压断路器在配电系统中若设计不当,就会影响供电回路的正常工作,针对低压断路器,简述在低压配电系统设计中应注意的一些问题.     

变压器中性线断线智能保护装置的研究

本文提出了一种应用于低压三相四线制的中性线断线检测和保护方法及装置。该方法及装置针对含有单相负荷的低压配电系统,该方法通过在断路器跳闸前和断路器重合闸后两次检测中性线上的电流情况来判断中性线是否断线,在中性线发生断线时自动断开供电电源并进行声光报警。结构简单、易于实现,可以有效地检测出中性线断线故障并切断电源进行保护。     

IntoNews: Online news retrieval using closed captions

We present IntoNews, a system to match online news articles with spoken news from a television newscasts represented by closed captions. We formalize the news matching problem as two independent tasks: closed captions segmentation and news retrieval. The system segments closed captions by using a windowing scheme: sliding or tumbling window. Next, it uses each segment to build a query by extracting representative terms. The query is used to retrieve previously indexed news articles from a search engine. To detect when a new article should be surfaced, the system compares the set of retrieved articles with the previously retrieved one. The intuition is that if the difference between these sets is large enough, it is likely that the topic of the newscast currently on air has changed and a new article should be displayed to the user. In order to evaluate IntoNews, we build a test collection using data coming from a second screen application and a major online news aggregator. The dataset is manually segmented and annotated by expert assessors, and used as our ground truth. It is freely available for download through the Webscope program.¹ Our evaluation is based on a set of novel time-relevance metrics that take into account three different aspects of the problem at hand: precision, timeliness and coverage. We compare our algorithms against the best method previously proposed in literature for this problem. Experiments show the trade-offs involved among precision, timeliness and coverage of the airing news. Our best method is four times more accurate than the baseline.     

基于VB的滑动轴承试验系统

利用传统的滑动轴承试验台与PC机相结合，设计出了一种新型的滑动轴承试验系统。文中介绍了系统的硬件组成及软件设计。采用模块化结构设计了系统工作的软件部分；采用VB调用动态链接库的方法实现试验数据的采集与处理。系统工作稳定可靠，操作界面简单，试验精度比传统试验台高。     

配电网网损动态潮流计算方法的探讨

利用几种动态潮流算法以提高配电网网损计算的精度,较好地解决了实际配电网运行状态时变性对网损计算精度影响的问题,通过与常规网损算法在计算量、计算精度、灵活性等方面的比较和分析,说明动态潮流算法的有效性和实用性。     

博罗水文站流量资料整编方法探讨

博罗水文站属国家一类精度水文站,是东江干流的控制站。近年来由于东江下游河道大规模的采砂活动,导致河床不断下切,潮水上溯,现测验河段已成感潮河段。同时又受惠州东江水利枢纽蓄放水发电影响,这两个原因致使博罗站的流量测验及资料整编造成严重影响,使得传统的流量测验及整编方法解决不了博罗站的主要问题。为此博罗站引进了在线测流系统,进行流量连续实时监测。文章结合水文资料整编软件HDPS就博罗站采用在线测流系统的流量资料整编方法进行探讨。     

Application of active disturbance rejection control in tank gun control system

The problem of position tracking for a tank gun control system with inertia uncertainty and external disturbance is investigated in this paper. The tank gun control system, demanding high tracking precision and stabilization precision, is a nonlinear system. Classical control methods are commonly used in the actual system, which is difficult to ensure high precision and high disturbance rejection capability. An active disturbance rejection control (ADRC) scheme is applied to guarantee the state variables of the closed loop system to converge to the reference state with the help of the extended state observer by estimating the inertia uncertainty and external disturbance. The basic theory of the ADRC is introduced here. According to the mathematical model, the parameters of ADRC are designed. Also, simulation results show that ADRC controller has advantages of high precision and high disturbance rejection ability. A comparison between ADRC and PID is also presented to show the effectiveness of the ADRC control strategy.     

路基压实密度水囊检测方法

介绍了新型水囊式容积测定仪的结构和原理，提出了用新型水囊式容积测定仪测试密度的方法．通过室内和现场对比试验，对新型水囊式容积测定仪测试精度进行了研究，并分析了测试精度对干密度计算值的影响．研究表明，新型水囊式容积测定仪具有仪器轻便、操作简单、测试精度较高的特点，具有较大的应用前景。     

Configuration of inclusive innovation systems: Function,agents and capabilities

Social exclusion represents a major challenge to policies advocating sustainable development in the Global South. Although this is a problem not prioritized in the realms of innovation policy focused on economic growth and competitiveness, it is now widely accepted that innovation may contribute significantly to the well-being of the social excluded. However, it is debated whether the innovation system approach is capable of informing transformational innovation policies aiming at overcoming social exclusion and other global challenges. This paper argues that the system innovation approach is adequate for facing this endeavour and identifies key constituent elements of innovation systems which are necessary for inclusion to emerge from the system dynamics. We illustrate the elements of this system configuration drawing upon the case of the appropriation of biorational approaches in pest management and precision agriculture techniques by a group of peasants in a rural village in Colombia. The proposal considers new elements that configure inclusive innovation systems in an agent-based, bottom-up perspective, such as new agents, capabilities, directionalities, and the integration of traditional knowledge with scientific and technology knowledge, elements that enable a new system function. In terms of policy implications, some reflections are made on favouring the sustainability paradigm and promoting inclusive learning processes.     

基于相关查询的搜索引擎查询自动分类研究

如何准确理解用户提交的查询成为搜索引擎面临的一个难题,对查询进行自动分类是尝试解决问题的一种方法。提出基于相关查询对查询进行自动分类的方法。首先介绍此方法的设计思路和流程,同时对关键处理步骤进行说明,然后选择百度风云榜的数据作为测试集进行测试验证,查准率可达到71.74%,最后分析和总结方法不足之处以及下一步研究计划。     

A generic construct based workload model for web search

Benchmarks are vital tools in the performance measurement, evaluation, and comparison of computer hardware and software systems. Standard benchmarks such as the TREC, TPC, SPEC, SAP, Oracle, Microsoft, IBM, Wisconsin, AS³AP, OO1, OO7, XOO7 benchmarks have been used to assess the system performance. These benchmarks are domain-specific and domain-dependent in that they model typical applications and tie to a problem domain. Test results from these benchmarks are estimates of possible system performance for certain pre-determined problem types. When the user domain differs from the standard problem domain or when the application workload is divergent from the standard workload, they do not provide an accurate way to measure the system performance of the user problem domain. System performance of the actual problem domain in terms of data and transactions may vary significantly from the standard benchmarks.In this research, we address the issue of generalization and precision of benchmark workload model for web search technology. The current performance measurement and evaluation method suffers from the rough estimate of system performance which varies widely when the problem domain changes. The performance results provided by the vendors cannot be reproduced nor reused in the real users’ environment. Hence, in this research, we tackle the issue of domain boundness and workload boundness which represents the root of the problem of imprecise, ir-representative, and ir-reproducible performance results. We address the issue by presenting a domain-independent and workload-independent workload model benchmark method which is developed from the perspective of the user requirements and generic constructs. We present a user-driven workload model to develop a benchmark in a process of workload requirements representation, transformation, and generation via the common carrier of generic constructs. We aim to create a more generalized and precise evaluation method which derives test suites from the actual user domain and application setting.The workload model benchmark method comprises three main components. They are a high-level workload specification scheme, a translator of the scheme, and a set of generators to generate the test database and the test suite. They are based on the generic constructs. The specification scheme is used to formalize the workload requirements. The translator is used to transform the specification. The generator is used to produce the test database and the test workload. We determine the generic constructs via the analysis of search methods. The generic constructs form a page model, a query model, and a control model in the workload model development. The page model describes the web page structure. The query model defines the logics to query the web. The control model defines the control variables to set up the experiments.In this study, we have conducted ten baseline research experiments to validate the feasibility and validity of the benchmark method. An experimental prototype is built to execute these experiments. Experimental results demonstrate that the method based on generic constructs and driven by the perspective of user requirements is capable of modeling the standard benchmarks as well as more general benchmark requirements.     

Using profile expansion techniques to alleviate the new user problem

Collaborative Filtering techniques have become very popular in the last years as an effective method to provide personalized recommendations. They generally obtain much better accuracy than other techniques such as content-based filtering, because they are based on the opinions of users with tastes or interests similar to the user they are recommending to. However, this is precisely the reason of one of its main limitations: the cold-start problem. That is, how to recommend new items, not yet rated, or how to offer good recommendations to users they have not information about. For example, because they have recently joined the system. In fact, the new user problem is particularly serious, because an unsatisfied user may stop using the system before it could even collect enough information to generate good recommendations. In this article we tackle this problem with a novel approach called “profile expansion”, based on the query expansion techniques used in Information Retrieval. In particular, we propose and evaluate three kinds of techniques: item-global, item-local and user-local. The experiments we have performed show that both item-global and user-local offer outstanding improvements in precision, up to 100%. Moreover, the improvements are statistically significant and consistent among different movie recommendation datasets and several training conditions.