High gain observer for a class of nonlinear systems with coupled structure and sampled output measurements: application to a quadrotor

This paper proposes a new high gain observer for a class of non-uniformly observable nonlinear systems with coupled structure driven by sampled outputs. The considered class of systems is particularly constituted by several subsystems where each subsystem is associated to a subset of the output variables. The observer design is carried out through two steps. First, a high-gain observer is proposed in the continuous-time output case under the assumption that an adequate persistent excitation condition is satisfied by each subsystem. Then, the proposed observer is redesigned to handle the case of sampled outputs leading thereby to a continuous-discrete time observer. The latter property is achieved thanks to the approach pursued along the convergence analysis. The effectiveness of the proposed observer is emphasised in a realistic simulation framework involving a mathematical model of a quadrotor which is diffeomorphic to the proposed class of considered systems.     

基于ATmega64L的128点实时FFT

利用ATmega64L单片机的大容量flash存储器和高速数据处理能力,研究了按时间抽取基2FFT算法在ATmega64L单片机中的实现方法,实现了以ATmega64L为核心的手持式振动信号采集器128点浮点格式采样数据的嵌入式实时快速傅里叶变换。验证了该方法对采样数据进行精确有效的快速傅里叶变换(FFT)分析的有效性和准确性,从而实现对设备运行状态及故障的初步诊断。     

Sampled‐data adaptive control of a class of nonlinear systems

The paper considers the discrete‐time implementation of a class of backstepping adaptive controllers for uncertain nonlinear systems in the parametric strict‐feedback form. The stability of the resultant sampled‐data system cannot be guaranteed when the direct discretization of the continuous‐time backstepping controller is applied to the same system via a sampling and hold device. Therefore, the paper has presented a sampled‐data control scheme which involves first modifying the existing continuous‐time controller and then discretizing it using the forward Euler method. It has been shown that the proposed control guarantees in a semi‐global sense the boundedness of all the variables of the overall sampled‐data system under some conditions. Particularly, the state of the nonlinear system to be controlled can converge to any arbitrarily small neighbourhood of the origin. Copyright © 2011 John Wiley & Sons, Ltd.     

Inductor Current Sampled Feedback Control of Chaos in Current-Mode Boost Converter

A chaos control strategy for chaotic current-mode boost converter is presented by using inductor current sampled feedback control technique.The quantitative analysis of control mechanism is performed by establishing a discrete alterative map of the controlled system.The stability criterion,feedback gain,and corresponding critical duty ratio are obtained from the eigenvalue of the map.The simulation results verify the t heoretical analysis results of the control strategy.     

Generalized predictive control for improving intersample performance

This paper proposes a design method of the Generalized Predictive Control (GPC) strategy which can take account of intersample behavior as well as sampled behavior. To this end, a discrete‐time equivalent plant model and cost function for a continuous‐time plant incorporated with zero‐order hold and discrete‐time controller are derived, and the modified discrete‐time GPC is designed. To verify the effectiveness of our proposed method, the controller is applied to a benchmark problem of a hard‐disk drive. Copyright © 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

大型风电机组脉动风场建模与数值仿真

分析了风电机组风场模型与普通建筑风场模型的异同,指出叶片的周期性运动将改变风速谱的频率成分分布,使相当部分的频率成分集中到风轮旋转频率及其倍频处。根据标准von Karman模型和旋转采样谱模型,分别推导并建立了风电机组固定部件和叶片上脉动风速谱功率矩阵,并在此基础上采用谐波叠加法模拟了风电机组各部件的风速时序数。     

采样值差动在线路差动保护中的应用

在简要介绍基于采样值的线路差动保护的基础上,结合具体案例重点分析了采样值差动在线路保护中的2个重要作用:一是解决传统变电站中的电流互感器饱和问题;二是提高数字化变电站中抗异常数据的能力.采样值差动保护的引入可以同时解决这2个问题,从而使传统变电站和数字化变电站的线路差动保护得到有机统一.     

高压相电流纵差保护的研究

基于故障分量采样值的差动保护判据,不受负荷分量的影响,灵敏度、可靠性高;又由于基于瞬时采样值判定,故速动性好。该保护弥补了高压线路常规相电流差动保护判据及采样值电流差动保护判据的不足,并将二者的优点合二而一,较好地满足了高压输电线路继电保护的要求。选择光纤作为保护通道,是因为光纤通道的抗电磁干扰能力强,传输容量和传输速率远远优于电力线载波通道。     

基于IEC 61850-9-2采样值传输模型的研究

IEC 61850标准定义了采样值传输的抽象模型,应用于采样值传输及相关服务。为了满足该标准对变电站自动化系统以及智能设备所提出的灵活性、互操作性的要求,在研究IEC 61850信息模型内涵的基础上,对合并单元的信息模型及其映射进行了介绍,构建了合并单元的采样值传输模型;通过预配置采样值控制块,进行IEC 61850-9-2采样值传输,分析了合并单元配置信息的灵活性,通过实验验证了信息配置的正确性。     

基于采样值相关度比较的母线保护方案

对母线各支路电流采样值在每个采样点进行数据处理,将处理结果作为计算相关度的依据,利用其在母线区内外故障及电流互感器饱和时的波形相关度特点,构造出具有自适应制动特性的母线保护判据。该判据基于瞬时采样值并综合多个采样值的信息来区分母线区内外故障,计算数据窗长较短,对频率偏移和谐波的影响也有一定的抵御能力。大量的动模实验表明:该判据能够快速、可靠地判别母线区内外故障,并具有一定的抗电流互感器饱和能力,在母线区内故障有汲出电流的情况下,保护灵敏度不受影响,定值整定借鉴传统比率差动的整定思想,简单易行,配合形态滤波等快速前置滤波单元,可构成一种较理想的母线主保护方案。