凝结水泵变频改造及节能分析

针对火力发电机组凝结水泵能耗高、效率低等问题,提出采取“一拖二”自动变频/工频切换控制的方案进行变频改造,取得了良好的节能效益.     

商业软件的多版本自动控制研究

分析了当前知识产权保护中存在的问题，针对商业软件在“拷贝数”限制和“规格”控制方面的不足，提出了硬件指纹与子许可证相结合的License解决方案。 该方案通过硬件指纹解决了软件拷贝数的唯一性限制问题，通过子许可证解决了软件多版本自动切换问题软件制造商只要控制好License的发放，就能够自动有效地控制其软件产品的“演示版”与“正式版”之间的转换问题以及软件不同运行规格之间的切换问题。     

自治供电系统的一种混合控制

研究自治供电系统(ASES)控制问题,基于"状态空间区域划分"和"切换控制"原理,提出一种混合型控制器.仿真表明,相比于近年来文献[1]中提出的动态滑模变结构控制方案,在保持系统基本性能前提下,可有效克服该方案中不可避免的抖振与高频切换等严重问题.     

基于OpenFlow的移动切换框架研究

现有移动切换的相关研究方案在实际部署时配置繁琐、工作量大、网络运维成本高,有些方案还存在三角路由问题,导致切换时延增大.为了解决移动切换过程中的这些问题,提高移动切换的性能,提出了一种基于OpenFlow的移动切换框架,通过理论分析证明了该切换框架的可行性;另外,通过搭建基于OpenFlow的移动切换实验平台,与传统移动IP方案进行性能对比分析.实验结果显示,基于OpenFlow的移动切换框架能够有效地控制数据流路径,避免三角路由问题,并且较传统方案其切换时延降低,说明提出的移动切换框架能够有效节省网络带宽资源和优化移动切换效率.     

基于观测器的切换系统反馈镇定的仿真研究

研究工程系统切换优化控制问题,为提高系统的稳定性,解决观测器子系统中存在的可观测和不可观测切换问题,提出了线性切换系统的反馈镇定的设计方案.方案根据对切换系统复杂性的认识的基础上,采用构建各种类型的误差子系统函数以及各种增广子系统函数的形式,求解一个线性矩阵不等式观测器增益矩阵的问题,从而得到了可观测子系统控制律的求解方法.进行仿真的结果说明,控制方法可使观测器子系统达到稳定,证实了方法有效性.     

非线性系统的反演自适应动态滑模控制

为削弱非线性系统中由滑模控制引起的抖振现象,提出自适应动态滑模控制方案.动态滑模方法是通过设计新的切换函数或将常规滑模变结构控制中的切换函数s通过微分环节构成新的切换函数,该切换函数与系统控制输入的一阶或高阶导数有关,可将不连续项转移到控制的一阶或高阶导数中去,得到在时间上本质连续的动态滑模控制律.该方案利用自适应技术和反演法,设计动态滑模控制器,有效地削弱了系统的抖振.最后仿真结果证明了该方案是正确的.     

UAVS通信网切换管理方案设计与分析*

针对UAVS通信网中的切换管理问题,提出了融合滞后余量与门限结合的切换判决方法、基于UAV节点自主决策的紧急切换控制策略和GCM-FIFO信道分配方案的切换管理方案.相关理论分析表明,该切换管理方案解决了UAVS通信网中节点高移动性、切换业务量高但信道数有限以及由于中继机节点遭遇威胁而带来的紧急切换等问题.     

一种基于缓冲的分层次移动IP模型——BHMIP

现有的移动IP方案在网络切换时存在着切换时延过大和丢包率过大两个问题,已提出的快速切换方案(fast handover)和分层次的IP方案(HMIP)针对切换时延和注册信令开销过大进行了一定的改进.BHMIP方案在HMIP和快速切换的基础上结合缓冲机制对切换过程中丢包率过大的问题进行了改进,并通过模拟仿真进行了验证.最后指出了进一步的研究方向.     

煤矿乳化液泵变频/工频切换控制

针对煤矿乳化液泵站采用变频器"一拖多"的多泵联动方案时存在冲击电流大的问题,提出了乳化液泵变频/工频异步切换和同步切换控制方案。现场试验结果表明,变频/工频同步切换控制能更有效地避免冲击电流,真正实现乳化液泵变频至工频的无扰切换。     

卫星移动通信网络切换算法的研究

低轨卫星移动通信网络在实现全球移动通信方面具有很大优势.切换方案对于控制低轨卫星网络通信时延,提高卫星网络服务质量和链路带宽资源利用率具有重要意义.深入分析了星地链路切换和重计算路由问题,提出了一种低轨移动通信卫星链路切换算法.仿真实验表明,提出的卫星链路切换算法有较小的端到端时延、较好的稳定性和可定制性.     

Output tracking control of nonlinear switched cascade systems using a variable structure control method

This article is concerned with the output tracking control problem for a class of nonlinear switched cascade systems under some average dwell-time-based switching laws. Firstly, stabilisation problem of this class of switched systems is considered. Then, the result is extended to the output tracking control problem. Based on the variable structure control technique and the characteristic of the system, the variable structure controllers and the average dwell-time are designed. The effectiveness of the proposed design approach is illustrated with simulation results.     

一类时滞复杂动态网络的鲁棒自适应同步问题

针对一类耦合时滞复杂网络,基于变结构控制研究其同步问题.首先,利用系统的左特征向量函数设计切换面,使网络的运动轨线在期望的同步轨道保持稳定;然后,针对网络中的非线性项已知和未知时,分别设计相应的滑模控制器,使从任意时刻出发的动态网络轨线都能在有限时间内同步到达期望的轨道;最后,利用所设计的控制器对两个算例进行仿真,仿真结果说明了所设计控制器的有效性.     

Output feedback variable structure control for a class of uncertain switched systems

This paper considers the output feedback variable structure control problem for a class of uncertain switched systems. A single sliding surface is constructed using only output information. Robust stability of the sliding motion restricted to the sliding surface is achieved and complete invariance to the matched and the mismatched uncertainties is guaranteed via a hysteresis switching law based on a reduced order observer. Output feedback variable structure controllers are given to guarantee that the redefined sliding surface is reached in finite time. A numerical example illustrates the effectiveness of the proposed design method. Copyright © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

无刷双馈电机滑模变结构直接转矩控制

针对无刷双馈电机直接转矩控制系统磁链和转矩脉动大的问题,引入滑模变结构控制策略.以转矩和磁链两个滑模控制器来代替传统直接转矩控制中的两个滞环控制器,电压矢量开关的输出采用空间电压矢量PWM调制的方法,保证了逆变器开关频率恒定,应用指数趋近率方法设计滑模控制器,由Lyapunov方法求得相应的滑模变结构控制律,建立了MATLAB/Simulink环境下直接转矩控制系统的仿真模型,仿真结果表明,新型控制方案能有效减小转矩脉动,改善定子磁链和电流波形,同时仍可保持直接转矩控制固有的转矩快速响应的优点,提高系统的稳定性和鲁棒性.     

An analysis and design method for uncertain variable structure systems with bounded controllers

We present a method for estimating the asymptotic stability region(ASR) of uncertain variable structure systems with bounded switching feedback controllers. Using linear matrix inequalities(LMIs) we estimate the ASR and we show the exponential stability of the closed-loop control system in the estimated ASR. We also give a simple LMI-based method for designing switching surfaces that will make the estimated ASR big. Finally, we give numerical examples in order to show the effectiveness of our method.     

离散时间系统的滑模控制器设计与仿真研究

针对不确定性离散时间系统,分析和设计了一类变结构控制器。当存在外界干扰和不确定性时,系统状态也是全局有界稳定的。一个新的切换面作为系统的输出信号被提出,特别用来设计滑模控制器。系统状态一旦进入到准滑动模态,就对设备参数变化和外界干扰显示出强的鲁棒性,因为控制器的设计完全考虑了边界层的影响。外推法被用来估计不确定离散时间系统的不确定值。两种方法均有效地消除了系统的抖振,确保了系统的稳定性,且保证了变结构控制系统良好的品质。最后,仿真结果证实了所提出方法的有效性。     

Robust H-infinity integral sliding mode control for a class of uncertain switched nonlinear systems

This paper develops a new method to deal with the robust H-infinity control problem for a class of uncertain switched nonlinear systems by using integral sliding mode control. A robust H-infinity integral sliding surface is constructed such that the sliding mode is robust stable with a prescribed disturbance attenuation level γ for a class of switching signals with average dwell time. Furthermore, variable structure controllers are designed to maintain the state of switched system on the sliding surface from the initial time. A numerical example is given to illustrate the effectiveness of the proposed method.     

Nonlinear variable structure excitation and steam valving controllers for power system stability

A set of novel nonlinear variable structure excitation and steam-valving controllers are proposed in this paper. On the basis of the classical dynamic equations of a generator, excitation control and steam valving control are simultaneously considered. Design of these controllers combines the differential geometry theory with the variable structure controlling theory. The mathematical model in the form of ＂an affine nonlinear system＂ is set up for the control design of a large-scale power plant. The dynamic performance of the nonlinear variable structure controllers proposed for a single machine connected to an infinite bus power system is simulated. Simulation results show that the nonlinear variable structure excitation and steam-valving controllers give satisfactory dynamic performance and good robustness.     

Observer‐Based Reliable Control for Discrete‐Time Switched Linear Systems with Faulty Actuators

This paper deals with the issue of reliable control for discrete‐time switched linear systems with faulty actuators by utilizing a multiple Lyapunov functions method and estimate state‐dependent switching technique. A solvability condition for the reliable control problem is given in terms of matrix inequality with an extra matrix variable. This condition allows the reliable control problem for each individual subsystem to be unsolvable. For each subsystem of such a switched system, we design an observer and an observer‐based controller. A switching rule depending on the observer state is designed which, together with the controllers, can guarantee the stability of the closed‐loop switched system for all admissible actuator failures. The observers, controllers, and switching law are explicitly computed by solving linear matrix inequalities (LMIs). The proposed design method is illustrated by two numerical examples.