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This paper proposes an advanced substation integrated protection communication sys- tem based on the latest development in power system. The integrated protection communication system within a substation comprises a number of major components such as the merging unit, communication network and integrated protection unit. The design and capability evaluation of the communication network based on IEC61850 are focused on. Results show that huge information from 4 merging units can be transmitted real-time via adopting 100 Mbit/s optical fiber in a sub-station, and the proposed communication network is able to achieve required performance. 相似文献
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变电站自动化系统目前采用IEC60870的老设备很多,必须保证使用IEC60870标准的装置在通信上与基于IEC61850新标准的系统相互兼容.本文比较了IEC61850与IEC60870两种不同标准体系通信规约的特点,依据变电站通信功能的特点和IEC61850的映射原则,提出了IEC61850到IEC60870-5-103/104通信规约的映射方法和思路,将采用103/104规约的装置纳入新的变电站自动化系统通信体系. 相似文献
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介绍IEC61850智能变电站一体化电源系统和变电站通信网络标准,在此基础上分析了IEC61850信息模型建模的规范：基本信息模型规范和信息服务模型规范,并在一体化电源系统的建模中引入这两个规范,对一体化电源系统的逻辑装置（LD）、逻辑节点（LN）和数据对象（DO）的定义依据规范进行扩充和信息建模. 相似文献
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In order to meet the requirements of information exchange varieties and manners in wide area protection system, a communication service model based on IEC 61850 is proposed. This service model can realize communication consistency and cooperation between different types of devices. Furthermore, the communication reliability and time delay performance are guaranteed to meet the requirements of relay protection from the upper layer. Message structure of generic substation event (GSE) and its communication mechanism are discussed. General methods to communicate digital information by generic substation status event (GSSE) and communicate analog sampling information by sampling analog value (SAV) of GSE are proposed. 相似文献
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基于IEC61850电力系统自动化的探讨 总被引：1，自引：0，他引：1
随着电力系统的迅速发展,电力网络的结构及运行方式日趋复杂,为保证系统的安全经济运行,对电力系统自动化水平和调度管理功能要求越来越高。很多新的应用系统软件相继出现,如:实时系统诊断系统、维护管理系统、系统监视和资产管理系统等等,将这些独立的系统整合起来,成为一个相互联系的整体,是电力系统自动化发展的必然I。EC61850标准无疑将是今后网络通信架构的方向。依据IEC61850标准,不同厂商的各个自动化系统将具有互操作性,从而整个大系统具有同一的编程开发维护环境和同一的企业标签名数据库,方便系统建模和升级扩展。 相似文献
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介绍了数字变电站合并单元使用中的关键技术。首先对比分析了GPS,SNTP,IEEE1588时间同步方法的特点,对目前实际采用的电子式互感器与合并单元之间的数字接口方案进行归纳总结,然后分别进行了基于IEC 61850-9-1和IEC 61850-9-2的合并单元的功能模块分析,最后综述了合并单元的性能测试方案。 相似文献
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由于数字化变电站系统设计是基于IEC61850标准,即系统具有较好的开放性、互操作性和扩展性特征,表明变电站系统向自动化的方向发展。该文对数字化变电站IEC61850进行了详细介绍和分析。针对目前变电站的数字化改造的实际需要,提出了过程层测控终端的软硬件具体设计方案,该方案对于未改造的变电站进行数字化改造来说,在理论和经济方面具有重要的指导意义。 相似文献
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根据大数据技术的模块构成和电子书包所包含的系统和功能,对电子书包中教育大数据的模块内容进行分析。之后,在评价内容上从课程内容学习、参与互动交流、考试与作品和课外资源学习四个方面进行了细分和聚类．构建了基于电子书包的个性化学习评价模型。在评价结果上,依据柯氏四级评估模式和布鲁姆教学目标分类理论设计了基于教育大数据的个性化评价层次塔,该层次塔包括学习成效、概念转变、学习迁移和学习力四个层级。最后,结合教育大数据、教育云服务、个性化评价模型和评价层次塔,设计了个性化学习评价系统模型,包括信息采集模块、数据分析与处理模块、个性化评价模块和可视化反馈模块,并通过云管理层实现对教育云服务平台、云存储池和云集群计算平台的调控和管理,以期为后面开展个性化评价系统的设计与开发提供有益的指导。 相似文献
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提出了一种基于流体随机Petri网的工作流响应时间概率分布计算方法.首先讨论了利用随机工作流网建模的一些相关问题,然后描述了如何将随机工作流网模型转化为流体随机Petri网模型,最后给出了该种流体随机Petri网模型的动态方程,说明工作流响应时间的概率分布可直接由流体随机Petri网模型的暂态解得到.该方法对工作流模型的结构没有提出任何限制,且工作流任务的处理时间可取任意概率分布,通过递归地使用网化简技术可有效地处理大型工作流模型. 相似文献
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针对通信信号的非线性时域滤波问题,研究了量子随机滤波器的原理和性能.将神经网络与非线性Schroedinger方程相结合,把方程的解作为信号时变的概率密度函数,进而实现滤波功能.研究发现,通过调整势场权系数的取值,可使滤波器具有明显不同的性能.根据此性质,构造了一种新的滤波算法,该算法可使滤波器在信号波形估计的非线性失真程度与它的抗噪能力之间进行折衷,这将大大推广量子随机滤波器的应用,例如,用于通信信号处理.仿真结果表明了量子随机滤波器的优越性能. 相似文献
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Development criteria observed as time series on nominal variables pose a problem for research design. Markov chains are attractive in the first instance because they can handle such multivariate multinomial data sets, with results that are described and demonstrated on Career Development Study data. The power of the formal probability model is purchased at the expense of assumptions that may be unrealistic. It is argued and demonstrated that where the Markov chain theory for the data breaks down is precisely where the most interesting part of the message contained in the data resides. The Markov chain is shown to be a better null hypothesis against which to array the psychometric or other prediction model than is the usually employed random walk. A new prediction system that combines information from the Markov chain with the psychometric predictors is described and operated. 相似文献
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图卷积网络由于能够直接处理图结构数据的优点而受到广泛研究。当前的多数图卷积网络是基于图信号的平滑性(低频信息),且不能根据各节点适合的接受域生成对应的节点嵌入,随着网络层数的增加,易出现图卷积网络特有的过平滑问题而导致性能下降。为此,提出了基于自适应频率和动态节点嵌入的图卷积网络模型(adaptive frequency and dynamic node embedding based graph convolutional network, FDGCN)。FDGCN模型能够自适应聚合不同频率的信息,同时利用每层网络的输出,平衡每个节点来自全局和局部领域的信息,动态地调节节点嵌入。通过在4个公共数据集上进行实验,对比了6个现有模型,证明了FDGCN模型的有效性。 相似文献
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Reliability of substation protection system based on IEC61850 总被引：1，自引：0，他引：1
Although the new technology of protection and automation system of substation based on IEC61850 standard has developed rapidly in China, reliability measures depending on this technology need to be further research＇ed. By taking advantage of convenient information sharing, two kinds of new schemes, shared backup protection unit （SBPU） and signal backup （SB）, have been proposed to solve the failure problem of protective devices and current/voltage transducers respectively, and the working principle of these two schemes are also described. Furthermore, the key technologies of on-line diagnosis of protective devices＇ failure and on-line status diagnosis of optical or electronic current/voltage transducers to realize the two schemes are proposed. 相似文献
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Response accuracy and response time data can be analyzed with a joint model to measure ability and speed of working, while accounting for relationships between item and person characteristics. In this study, person‐fit statistics are proposed for joint models to detect aberrant response accuracy and/or response time patterns. The person‐fit tests take the correlation between ability and speed into account, as well as the correlation between item characteristics. They are posited as Bayesian significance tests, which have the advantage that the extremeness of a test statistic value is quantified by a posterior probability. The person‐fit tests can be computed as by‐products of a Markov chain Monte Carlo algorithm. Simulation studies were conducted in order to evaluate their performance. For all person‐fit tests, the simulation studies showed good detection rates in identifying aberrant patterns. A real data example is given to illustrate the person‐fit statistics for the evaluation of the joint model. 相似文献
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CHAKARESKI Jacob 《浙江大学学报(A卷英文版)》2006,7(5):773-783
INTRODUCTION According to yearly statistics the demand for multimedia traffic over computer networks is con- stantly on the increase (Nielsen//NetRatings, http:// www.nielsen-netratings.com/). Therefore, it is inevi- table that situations where different media streams will need to share communication resources will be- come commonplace. In such cases, it would be of interest to optimize the overall performance of the network. In other words, resources should be allo- cated across the com… 相似文献
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In psychological, social, behavioral, and medical studies, hidden Markov models (HMMs) have been extensively applied to the simultaneous modeling of heterogeneous observation and hidden transition in the analysis of longitudinal data. However, the majority of the existing HMMs are developed in a parametric framework without latent variables. This study considers a novel semiparametric HMM, which comprises a semiparametric latent variable model to investigate the complex interrelationships among latent variables and a nonparametric transition model to examine the linear and nonlinear effects of potential predictors on hidden transition. The Bayesian P-splines approach and Markov chain Monte Carlo methods are developed to estimate the unknown, a Bayesian model comparison statistic, is employed to conduct model comparison. The empirical performance of the proposed methodology is evaluated through simulation studies. An application to a data set derived from the National Longitudinal Survey of Youth is presented. 相似文献
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高翔 《安徽师范大学学报(人文社会科学版)》2019,47(1):134-141
我国跨境电商规模由2013年的2.9万亿元升至2017年的7.5万亿元,增幅158%。当前跨境电商B2C进口市场主要有直购进口、保税进口、集货进口以及海淘进口四种模式,这四种跨境电商B2C进口模式绩效差异较大。以《中国企业供应链管理绩效水平评价参考模型(SCPR1.0)构成方案》为基础,结合跨境电商B2C进口供应链的特征,筛选出17个绩效评价指标。通过对151份有效问卷数据进行因子分析发现:一是跨境电商B2C进口供应链绩效由高到低分别是保税进口、直购进口、集货进口和海淘进口;二是经过因子分析,在17个绩效评价指标中筛选出了2个公共因子,两者成为影响跨境电商B2C进口供应链的核心因素。 相似文献
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This paper describes the procedure of using the GM (1,1) weighted Markov chain (GMWMC) to forecast the utility water supply, a quantity that usually has significant temporal variability. The GMWMC is formulated into five steps: (1) use GM (1,1) to fit the trend of the data, and obtain the relative error of the fitted values; (2) divide the relative error into ‘state’ data based on pre-set intervals; (3) calibrate the weighted Markov chain model: herein the parameters are the pre-set interval and the step of transition matrix (TM); (4) by using auto-correlation coefficient as the weight, the Markov chain provides the prediction interval. Then the mid-value of the interval is selected as the relative error for the data. Upon combining the data and its relative error, the predicted magnitude in a specific time period is obtained; and, (5) validate the model. Commonly, static intervals are used in both model calibration and validation stages, usually causing large errors. Thus, a dynamic adjustment interval (DAI) is proposed for a better performance. The proposed procedure is described and demonstrated through a case study, which shows that the DAI can usually achieve a better performance than the static interval, and the best TM may exist for certain data. 相似文献
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随着现代信息技术和海洋开发技术的飞速发展,人们对水声通信的需求日益增加。本文针对水声信道可用通信带宽有限、传输时延大的特性,提出了一种基于马尔科夫链的认知水声通信中的频谱预测方法,并用MATLAB对其性能进行了仿真。仿真结果显示与无频谱预测及随机接入情况下相比,本文所提方法可以合理地动态分配水下的频谱资源、有效的减少数据碰撞概率,从而提高频道利用率以及节点接入频道的准确率。 相似文献