带谐波补偿的T型三电平并网逆变器控制研究

为了提高光伏逆变器并网电流质量,鉴于有源滤波器的控制算法,提出了一种新型的带谐波补偿的T型三电平并网逆变器控制策略。首先,采用锁相环分析电网电压矢量相位角,并根据光伏阵列输出的功率计算光伏并网逆变器的基波输出电流。然后,通过自校正滤波器技术提取网侧负载谐波电流。最后,根据基波输出电流与负载谐波电流确定T型三电平光伏并网逆变器的开关导通序列。为验证该控制策略,搭建了基于Matlab/Simulink的仿真模型。仿真试验结果表明:该控制策略可有效改善网侧谐波电流,提高并网电流质量,在不增加设备的前提下实现光伏并网与有源滤波双重功能。该研究对于T型三电平逆变器在光伏并网及电能质量治理领域的推广应用具有重要价值。     

不平衡电网下光伏逆变器的控制策略研究

针对不平衡电网下常规光伏逆变器的并网电流三相不对称及谐波含量大增的问题,研究了相应的控制策略。首先,从获取电压相位出发,设计了基于二阶广义积分器(Second Order Generalized Integrator,SOGI)的不平衡锁相环,以快速、准确地锁定电网正序分量的幅值和相位,并通过实验加以验证;其次,将抑制网侧负序电流作为控制目标,设计了基于电网负序电压前馈的不平衡电网下光伏逆变器的控制策略,且为减弱直流侧电压波动对并网电流的影响,在电压外环控制器后引入了二倍频陷波器。最后,利用PSCAD/EMTDC搭建出光伏并网系统仿真模型,仿真结果表明了本文理论研究的正确性。     

光伏发电系统并网逆变器控制策略研究

从光伏发电系统中并网逆变器的控制策略研究课题的背景和意义入手,对光伏发电系统中的并网逆变系统进行数学建模与分析。明确了光伏发电逆变系统的数学模型及工作原理后,针对一般的并网逆变器的控制策略没有实时更新参考信号的缺陷,提出了一种改进型的双闭环电流控制策略。在Matlab/Simulink软件环境中构建并模拟运行仿真模型。与其他常规控制策略相比,改进型双反馈闭环电流控制策略能稳定地跟踪电网电压相位,输出良好的并网电流波形。仿真成功验证了改进型策略的可行性。     

100 kW光伏并网逆变器系统设计

光伏并网发电系统具有造价低、输出电能稳定的优点,是光伏发电未来的主要趋势,而并网逆变器是并网光伏发电系统的核心装置.基于光伏并网逆变器的基本原理,提出了100 kW三相光伏并网逆变器系统设计方案.详细介绍了主回路关键元器件的选型与参数设计方法并提出了本系统的控制策略方案.样机实验结果表明,该逆变器设计合理、运行可靠、满足各项设计指标,具有很高的应用和推广价值.     

三相光伏并网电流型PWM逆变器的研究

基于三相电流型PWM逆变器装置,将直接电流控制方法应用于该逆变器中,设计了一套1kW实验装置。通过仿真分析和实验验证表明,该方法不仅实现了逆变器网侧电流正弦化并与网侧电压同相位,而且实现了直流侧电压宽范围调节,提高了系统动态性能,更适合于光伏并网。     

基于CIGS薄膜光伏电池的三相并网研究与仿真

针对光伏电池工程数学模型误差较大的问题,本文采用基于光伏电池物理等效电路模型对CIGS（铜铟镓硒）薄膜光伏电池阵列进行建模仿真,并采用牛顿插值算法对CIGS薄膜光伏电池阵列进行最大功率点跟踪,并网逆变器部分则采用直接电流控制策略,由此搭建仿真平台实现三相光伏并网仿真。仿真结果和数据表明了CIGS薄膜光伏电池阵列所建立模型的有效性和牛顿插值最大功率点跟踪算法的快速与准确性,以及直接电流控制策略的实用性。对CIGS薄膜光伏发电系统的工程分析和设计具有较高的参考价值。     

电流型多重化光伏并网逆变器的研究

在光伏发电系统光伏逆变器的研究中,针对太阳能电池的电流源特性,在光伏发电系统中采用电流型逆变器可以获得良好的控制效果。为了适应大功率的应用场合,以电流型多重化逆变器为研究对象,论述了电流型逆变器多重叠加的原理,并采用移相控制的方法对输出电流的进行调节。在上述基础上,研究了整个系统的控制策略。最后在MATLAB/SIMULINK环境下进行了系统的建模与仿真,通过FFT分析了并网电流,仿真结果证明了改进控制方法的可行性,为大功率光伏并网逆变器的研究奠定了基础。     

并网系统逆变器锁相环的研究

在太阳能光伏发电系统中,并网逆变器是实现光伏电能馈送电网的重要环节,并网光伏逆变器的控制目标为：控制逆变电路的输出为稳定的、高品质的正弦波,且与电网电压同频、同相。鉴于此,本文提出了一种数字电流锁相的方法,并且进行了系统仿真。仿真结果表明,TMS320C2000系列DSP芯片适用于该数字锁相技术,其并网输出电流波形良好...     

光伏发电系统并网逆变器电压电流双闭环控制仿真研究

为实现光伏发电系统MPPT要求,参考扰动观测和电导增量法建立了一种电压电流双闭环并网逆变器控制策略,搭建了该策略的MATLAB/Simulink模型并进行了仿真,仿真结果显示该策略可满足逆变器并网要求。     

不对称故障下两级式光伏逆变器的LVRT策略

为提升基于Boost电路的两级式光伏逆变器的并网运行稳定性,研究了不对称故障下光伏逆变器的运行特性,提出了以Boost调节直流母线电压配合负序电压前馈的电流控制策略,来实现低电压穿越(Low Voltage Ride Through,LVRT)。首先,分析了两级式光伏逆变器的常规Boost电压控制模式和电流控制策略。在电网故障时通过引入基于故障前光伏阵列最大功率点电压前馈的母线电压控制外环改变Boost电压控制模式,以稳定直流母线电压和防止逆变器过流。接着,为在不对称故障期间控制并网电流三相对称,提出了基于电网负序电压前馈的电流控制策略;结合根据电压跌落深度直接给定参考值的方式调节输出电流,为电网提供无功功率支撑;为实现前述电流控制,设计了基于二阶广义积分器(Second Order Generalized Integrator,SOGI)的正负序分离锁相模块。最后,利用PSCAD/EMTDC仿真软件搭建100 kW光伏逆变器模型进行控制策略验证,结果表明该策略在单相电压跌落至0.2 p.u时仍能快速有效地抑制直流母线电压升高,使光伏逆变器安全地实现低电压穿越。     

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.     

基于QTE的蒙古文显示机制研究与实现

蒙古语言是中国蒙古族使用的通用语言,由于蒙古文区别于其他文字的书写方式和其自身变形机制等特点,在很多通用的文字处理引擎中都不被支持。在嵌入式产品开发与应用领域中Linux加QTE已经成为流行方式。该文给出了一种在QTE环境上实现基于标准Unicode的蒙古文点阵显示和变形算法, 并自定义了支持蒙古文的QTE组件,扩展了QTE功能,为在Linux加QTE方式的嵌入式体系结构中处理蒙古文提供了一种解决方法。     

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.     

基于AD9626的模拟信号采集存储卡设计

自然界的绝大部分信号都是以模拟的形式存在,因此模拟信号的采集转换存储在数字时代十分关键。文章讨论了在雷达信号处理领域基于AD9626的AD采集存储卡的设计原理、硬件结构和程序设计与芯片配置等问题,为今后相关领域的研究提供了可参考的方案。     

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     

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.     

A human-computer interface for non-computer specialists

The COM teleconferencing system was designed to be easy to use for both beginners and people with much computer experience. A number of design choices in organizing the human-computer interface were considered very carefully. These design problems are not unique for teleconferencing applications, but will appear in many other developments of human-computer interfaces for non-computer specialists. This report discusses naming conventions, menu format, user commands, help facility and the treatment of ‘type ahead’ from the users.