三相四线APF直流侧的T-S模糊均压控制

电容分裂中点式三相四线有源电力滤波器（APF）是解决三相四线电力系统谐波治理的有效方法,由于直流侧两组电容电压需要单独控制,增加了均压控制难度并直接影响补偿的效果。分析了该APF的电路拓扑,采用T-S模糊控制的方法对电容分裂中点式三相四线APF的直流侧均压控制进行建模,将直流侧两组电容电压分别作为输入前件变量,对电源电流实施反馈控制。设计的T-S模糊反馈控制器使APF直流侧两组电容电压实现自动均压,满足了APF对负载谐波的补偿控制要求。仿真及实验结果验证了所建立T-S模糊均压控制模型的有效性,APF直流侧两组电容的电压保持均衡,具有较高的稳态精度和良好的动态性能。     

基于并联型APF的变频设备谐波治理容量的选择与验证

变频器在工程中的应用越来越广泛,已成为电力系统中重要的谐波源。针对谐波治理通常采用并联型有源电力滤波器(APF)。实践中发现按谐波电流选择有源滤波器的容量,补偿效果往往不理想,但补偿容量过高又增加不必要的投资。如何选择适合的谐波治理容量成为困扰设计人员的一个难题。本文以某再生水厂变频设备为研究对象,采用并联型APF就地治理的方案,根据参考文献资料并结合工程经验选择APF容量,通过测量负载侧和电网侧在谐波治理前后的电气参数验证治理效果。治理后电网侧和负载侧的谐波指标均降至国标GB/T14549允许范围之内,取得理想的治理效果。该结果对工程设计中有源电力滤波器容量的选择具有一定的借鉴和指导意义。     

APF特定次谐波智能检测方法的研究

有源电力滤波器(APF,Active Power Filter)是当今重要的谐波治理和无功补偿装置,APF关键的环节是实时准确地检测出谐波电流.针对传统基于瞬时无功理论的ip-iq谐波检测方法实时性差、对系统的补偿能力要求很高等不足,提出了基于BP神经网络与锁相环相结合提取特定次谐波的方案,权值调整采用BFGS拟牛顿算法,该算法可检测出基波、各次谐波分量的幅值和相角,且神经网络的并行运算能力强大,方便应用于三相电路中.改进的特定次谐波检测系统较传统的LC滤波器和并联型APF的组合调节策略响应速度高,系统结构简单,且不易出现高频谐波.通过Matlab仿真实验证明了该算法的可行性和良好的控制效果.     

并联型有源电力滤波器Matlab仿真研究

采用有源电力滤波器(APF)治理谐波污染是一个明显趋势。介绍并联型APF工作原理,建立了其数学模型。在Matlab/Simulik仿真环境下,基于瞬时无功功率理论的i_p-i_q谐波检测法和电压、电流双闭环结构,对控制系统进行了仿真建模。实验结果表明仿真建模准确,基本实现了谐波抑制。     

超导磁体电源交流侧有源滤波器研究

为满足稳态强磁场超导磁体模型线圈电源交流侧谐波抑制及无功补偿的需求,提出将并联型有源电力滤波器(APF)应用其中的方案。对其工作原理进行了说明,给出了设计结构。提出基于FBD法的谐波电路运算方式,较传统ip-iq法而言,简化了谐波计算,引入基于空间矢量的电压控制可以有效地降低开关频率,减少功率器件的开关损耗。仿真结果表明该并联型有源电力滤波器具有良好的性能。     

VK有源电力滤波器在电源电压畸变时的谐波提取方法

分析了有源滤波器（APF）基于旋转坐标系下进行坐标变换的谐波检测方法。该方法在电网电压畸变情况下能很好地检测和补偿电网中的谐波电流和无功电流。应用于三相三线制电路时,该方法可以计算任意次谐波电流的瞬时值。仿真与实验均验证了所提出的谐波检测方法的有效性,基于旋转坐标系下进行坐标变换的谐波检测方法的有源电力滤波器具有良好的工作性能。     

基于EL模型的海洋石油平台三相APF无源性控制

利用有源电力滤波器装置(APF)的非线性特性,提出一种基于欧拉-拉格朗日(EL)模型的三相并联型APF的无源性非线性控制方法.为了确保APF直流侧平均电压稳定在设定值,提高APF的谐波补偿精度,采用基于非线性PI控制的APF直流侧电压外环控制.Matlab仿真实验证明此方法控制的APF具有很好的谐波补偿效果,在负载突变的情况下具有很好的动态响应速度.     

有源滤波器直流侧电压控制仿真分析

首先指出有源滤波器的研究价值,讲述了有源电力滤波器谐波采集的基本原理,并在谐波控制环节增加直流侧电压控制环节,通过对直流侧为直流电源及电容两种电路结构进行仿真,给出了控制效果。之后,对直流侧电容电压控制策略进行了误差分析,为有源滤波器的研究提供了进一步的理论依据。     

航空串联式有源电力滤波器的仿真研究

提高航空交流电网供电品质,对于确保飞机安全具有重要意义.有源电力滤波器(APF)因其谐波补偿动态性能好,成为治理谐波污染的一种有效装置.分析了串联式有源电力滤波器(SAPF)谐波补偿的基本原理,着重介绍了基于瞬时无功功率理论的谐波电压检测方法.在Matlab/Simulik环境下,基于瞬时无功功率理论的ip-iq谐波检测方法,采用直流电压、补偿电流的双闭环控制结构,建立了SAPF系统仿真模型,包括三相400 Hz飞机电源、非线性电压负载、谐波检测以及补偿跟踪电路等模型.实验结果表明SAPF实现了对负载谐波的显著抑制,证明了SAPF应用于航空电网谐波治理是可行的.     

一种简单实用的APF谐波电流检测实验系统

现有的多种有源电力滤波器(Active Power Filter,APF)单相电路谐波电流检测方法,它们的有效性均采用仿真验证,而缺少实验环节.针对此问题,将UA206 A/D数据采集卡通过PCI口与计算机相连,以电源电压和负载电流作为输入信号可以构成一种简单实用的APF谐波电流检测实验系统.该系统具有结构简单、稳定性...     

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。     

煤矿井下安全监控分站的设计及其仿真实现

为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.     

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     

View-based model-driven architecture for enhancing maintainability of data access services

In modern service-oriented architectures, database access is done by a special type of services, the so-called data access services (DAS). Though, particularly in data-intensive applications, using and developing DAS are very common today, the link between the DAS and their implementation, e.g. a layer of data access objects (DAOs) encapsulating the database queries, still is not sufficiently elaborated, yet. As a result, as the number of DAS grows, finding the desired DAS for reuse and/or associated documentation can become an impossible task. In this paper we focus on bridging this gap between the DAS and their implementation by presenting a view-based, model-driven data access architecture (VMDA) managing models of the DAS, DAOs and database queries in a queryable manner. Our models support tailored views of different stakeholders and are scalable with all types of DAS implementations. In this paper we show that our view-based and model driven architecture approach can enhance software development productivity and maintainability by improving DAS documentation. Moreover, our VMDA opens a wide range of applications such as evaluating DAS usage for DAS performance optimization. Furthermore, we provide tool support and illustrate the applicability of our VMDA in a large-scale case study. Finally, we quantitatively prove that our approach performs with acceptable response times.     

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.     

A pragmatic multi-method investigation of discrepant technological events: Coping,attributions, and ‘accidental’ learning

Discrepant technological events or situations that entail a problem, a misunderstanding or a difficulty with the Information Technology (IT) being employed, are common in the workplace, and can lead to frustration and avoidance behaviors. Little is known, however, about how individuals cope with these events. This paper examines these events by using a multi-method pragmatic approach informed by coping theory. The results of two studies – a critical incident study and an experiment – serve to build and test, respectively, a theoretical model that posits that individuals use a variety of strategies when dealing with these events: they experience negative emotions, make external attributions, and adopt engagement coping strategies directed at solving the event, eventually switching to a disengagement coping strategy when they feel they have no control over the situation. Furthermore, users’ efforts may result in ‘accidental’ learning as they try to overcome the discrepant IT events through engagement coping. The paper ends with a discussion of the results in light of existing literature, future opportunities for research, and implications for practice.