兆瓦级风力发电机组变桨距系统

以ECSxA系列变桨变频器为硬件平台,以非线性PID变桨控制算法为核心,设计了一种新的兆瓦级风力发电机组变桨距系统.通过软硬件的设计,较理想地实现了变桨距系统的电气控制,在实际应用中获得了良好的控制效果,实现了兆瓦级风力发电机组变桨距系统的自主开发.     

大型风力发电机变桨控制系统设计

变桨距风力发电机已成为风力发电机组的主要研究和发展方向,文章以大型风力发电机组的变桨距系统为研究对象,通过对硬件系统的功能描述,设计了变桨系统的总硬件电路和伺服电路。在此基础上,为实现硬件电路的良好调节作用,对风机启动后变桨程序和调功程序的软件流程图作了详细设计。经过以上的软硬件设计,满足了大型风力发电机组变桨的控制要求。在实际应用中,获得了良好控制效果。     

风力发电系统独立变桨距载荷优化控制研究

对风力发电系统独立变桨距控制原理进行阐述。建立了风力发电机组桨叶载荷的数学模型,利用Coleman坐标变换实现了将桨叶上的载荷转换成轮毂处倾斜方向和偏航方向的疲劳载荷,并且实现了二者的解耦,简化了控制器的设计;之后利用Coleman逆变换实现了桨距角的微调。该控制系统根据随机风速的变化,利用独立变桨控制对风力机桨叶桨距角进行实时调节,以达到减小风电机组关键部件载荷的目的。仿真结果表明,当风速达到额定值以上时,该控制策略在统一变桨距控制的基础上,不仅保证输出功率近似相等,而且减小了桨叶所承受的疲劳载荷,也减小了风力机组其他关键部件的疲劳载荷。     

风电机组电动变桨距控制系统的优化研究

由于风速的随机性、不稳定性及气动效应的影响,使得风力发电机组变桨距控制系统具有非线性、参数时变性、强耦合等特点,难于实现高精度控制,导致风电机组输出电能质量较差。为了改善系统在恒功率输出运行区域内的动态性能,分析了风电机组变桨距控制系统的现状,建立了整个风电机组模型,提出了优化的变桨距控制策略,并设计了基于模糊控制的变桨距控制器。仿真结果表明,独立变桨距控制技术的控制效果比统一变桨距好,实现了风力机各叶片的优化独立变桨距控制,优化了风力发电系统在超过额定风速时的恒功率控制,具有抗干扰能力强、控制精度高的特点。     

模型参考自适应电动变桨距控制

根据模型参考自适应控制原理(MRAC),以大型风力发电机组直流电动变桨距控制系统为研究对象,设计一个高性能电动变桨距自适应控制系统,并应用李雅谱诺夫稳定性分析法给出自适应系统控制律,通过对所设计系统的性能进行了仿真分析,分析结果表明所设计系统具有很好的跟踪性和伺服性.     

风机变桨距非线性预测控制算法

变桨控制技术是MW级大型变速变桨风力发电机组的核心控制技术之一,通过变桨控制可以保证风电机组输出功率恒定在额定功率附近.由于风轮的强非线性特性,采用常规的PID控制器往往面临参数难以设计以及参数缺乏自整定能力的问题.提出了基于遗传算法的变桨距非线性预测控制器设计方法,根据优化和反馈校正的预测控制思想,针对风轮非线性控制对象设计了一种基于智能搜索方法的带约束的非线性预测控制算法进行仿真.仿真结果表明算法对非线性对象控制中具有很好的约束预测控制性能.与传统PI算法相比,具有响应快速、超调小、抗干扰能力好的特点,并通过优化算法滚动局部寻优,减少了设计的工作量和提高了设计效率.     

MW级风电系统的变桨距控制及载荷优化

针对风速的随机性及不确定性的特性,以及大型变速变桨风电机组(Variable Speed Variable Pitch Wind Turbine,VSVP)在桨距控制过程中,由于其大转动惯量造成发电机转速响应延迟的问题,提出了一种基于卡尔曼滤波算法的风轮气动转矩观测器,并将气动转矩与参考转矩偏差作为控制器输入以及时响应外界风速变化.针对变桨过程中普遍存在的塔架前后振动和传动链扭转振动问题,提出了通过在原有控制策略的基础上采用加速度反馈和阻尼滤波的方式得到附加桨距角和转矩,从而抑制振动的控制方式.利用Bladed编制了外部控制嚣对某2MW风力发电机组进行仿真,验证了该算法的可靠性,将所提出的控制策略应用于MW级风力发电机组,能够改善桨距控制的动态特性,并有效降低关键部位疲劳载荷.     

大型风力发电机组变桨距控制技术研究

在研究风力发电控制技术中,变桨距控制因其特有的技术特点,常被用在大型风力发电机组中,以保证额定功率点以上输出功率的恒定和机组的安全运行.由于大型风力发电机组的非线性、时变、强耦合等特征,为进一步提高系统的稳定性,用加入单个神经元在线调整模糊控制查询表的变桨距控制算法;并用MATLAB软件对机组控制进行仿真.仿真结果表明,变桨距控制算法具有良好的静、动态特性,能较好地将功率限定在额定值附近.     

直驱永磁同步风电机组的PID控制器设计与仿真

该文以10 k W的直驱永磁同步风力发电机(PMSG)为具体对象,对直驱永磁同步风力发电机组进行建模及仿真研究,在Matlab/Simuliuk平台上建立永磁同步风力发电机组各个子系统的数学模型。在发电环节整体动态仿真模型的基础上,采用变转速变桨距角的控制策略,针对变桨距控制系统设计了PID控制器,并调节PID参数,较好地实现控制器的性能。     

兆瓦级同步风力发电机变桨距控制策略研究

变桨距风力发电机已成为风力发电机组的主要研究和发展方向,结合长星集团同步风力发电机组,对变桨距控制技术进行了研究,在额定风速以下时实行变速运行,控制发电机的励磁电流从而控制发电机的转速,使得风力机转速能够跟随风速变化,保持最佳叶尖速比使系统获得最大的风能利用系数;额定风速以上时,采用PID控制算法控制桨距角,使发电机输出功率恒定,并提出了实现方法;通过仿真工具进行计算机仿真,验证了本方法的有效性。     

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。     

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。     

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。