Z源逆变器在开关磁阻风力发电系统中的应用

根据开关磁阻风力发电系统工作原理及对并网过程分析,结合Z源逆变器的单级式升降压特性,针对发电机输出直流电压偏低的情况,采用基于SVPWM调制的Z源逆变器实现系统并网的策略,实现逆变后输出电压满足并网的要求.通过并网逆变控制器的设计实现Z源网络的电容端电压的稳定及系统的有功功率和无功功率控制.在Matlab/Simulink仿真平台下,建立开关磁阻风力发电系统和Z源逆变器的仿真模型,仿真运行结果表明Z源逆变器应用于开关磁阻风力发电并网系统中的可行性和有效性.     

并联型APF抗启动冲击的时间最优控制算法研究北大核心CSCD

针对并联型有源电力滤波器(APF)投入电网运行时,存在着启动冲击电流和冲击电压的问题,提出抗启动冲击电流、电压的时间最优控制算法.由于并网时交直流侧压差导致的电流激增,会造成直流侧电容的损害和保护装置的动作误差.现对并网交流侧电感电流的冲击,利用前馈解耦的方式,分成d,q两轴双向分析来抑制并网侧的冲击电流.而直流侧电压采用一种输出压差平方值的Bang-Bang新型控制算法以抑制电容侧的冲击电压.最后结果皆在仿真软件Matlab中进行了验证,通过与常规控制算法对比,在抑制启动冲击电流、电压方面起到了良好的效果.     

并联型APF抗启动冲击的时间最优控制算法研究

针对并联型有源电力滤波器(APF)投入电网运行时,存在着启动冲击电流和冲击电压的问题,提出抗启动冲击电流、电压的时间最优控制算法.由于并网时交直流侧压差导致的电流激增,会造成直流侧电容的损害和保护装置的动作误差.现对并网交流侧电感电流的冲击,利用前馈解耦的方式,分成d,q两轴双向分析来抑制并网侧的冲击电流.而直流侧电压采用一种输出压差平方值的Bang-Bang新型控制算法以抑制电容侧的冲击电压.最后结果皆在仿真软件Matlab中进行了验证,通过与常规控制算法对比,在抑制启动冲击电流、电压方面起到了良好的效果.     

大功率风电并网变流器系统中非线性脉冲扰动的同步控制研究

研究了一类大功率风力发电并网中具有非线性脉冲扰动的同步控制问题.利用Kirchhoff定律建立了一类风力发电系统电网侧变流器的数学模型.设计了适当的反馈同步控制器,借助Lyapunov稳定性理论,验证了该同步控制器的有效性.给出了一类最优算法来抑制并入电网电流中的非线性脉冲扰动,使得风力发电机所产生的电流和电网的电流同步.最后通过Matlab中的Simulink进行了仿真设计研究,验证了该理论结果的有效性.     

基于RBF神经网络的超导风力发电系统变速控制研究

超导同步发电机(SCSG)以其功率密度大,重量轻,体积小,寿命长的特点,已经被用来研究超大型海上风力发电机组.文章首先介绍了一种将高温超导材料应用于大型风力发电机组的技术,分析了高温超导发电机的结构和特点,基于FAST和Matlab/Simulink软件平台搭建SCSG风力发电机组的数学模型和速度控制模块,其次针对SCSG模型存在高阶,非线性时变的特性,在速度控制环中引入了基于Delta学习规则的单神经元自适应PID控制算法,其中RBF网络用于控制参数的辨识整定.模拟实验结果表明,相对于传统PID控制,该算法可以使SCSG速度更好地跟踪风速,保持稳定的最佳叶尖速比和最大功率系数,从而实现最大风能利用.     

基于飞轮储能的并网风电场有功功率及频率控制方法研究

为平缓风电场输出,实现大规模风电并网并参与系统的频率控制,设计了一个基于永磁同步电机的飞轮储能系统,利用飞轮储能系统的快速充放电能力实现了风电场并网有功功率与一次频率控制.研究了飞轮储能系统的参考功率计算方法,根据该参考功率的变化实现储能系统充放电运行状态的转化.在Matlab/Simulink中建立了该储能系统模型,进行了风电场并网的有功功率及频率控制仿真,仿真结果表明该方法可以有效地平缓风电场的有功功率输出,参与系统的一次调频.     

基于扩展状态观测器的Boost变换器控制策略研究

内容针对Boost变换器系统在受到外部扰动时其动态性能不是很理想的问题,提出一种基于扩展状态观测器的Boost变换器控制策略.建立了变换器控制系统的数学模型,通过扩展状态观测器观测负载电流和输入电压变化引起的系统扰动,来估计和补偿输出电压的变化,并引入PD模糊逻辑控制器进一步改善了系统动态性能.该策略不依赖于控制系统数学模型和其具体参数,能精确估计系统的扰动和在线补偿负荷电流和输入电压的变化.进行了仿真和实验验证,结果表明了所提控制策略的有效性.     

农村小型风力发电机的控制与并网仿真

设计了双馈风力发电机组的定子磁链矢量控制系统,构造了容量为9MW的风力发电系统;通过MATLAB软件,分别在变风速和恒定风速两种情况时,对风力发电系统并网进行仿真.仿真结果表明,利用矢量变换技术的控制方法,风力发电系统可以实现有功功率和无功功率的快速解耦并且动态响应快,跟随性能好.     

一类离散系统基于偏差分离的输出反馈控制

针对一类不确定离散系统,提出一种基于偏差分离的输出反馈双控制策略,首先设计动态输出反馈控制器镇定其标称系统(即不确定性为零的情形);然后通过构造降维观测器,在线获取不确定性信息,并采用线性的补偿器实时补偿系统的不确定性.该控制策略采用线性控制,在工程中可以方便地实现,具有好的工程意义.理论分析证明了闭环指数渐近稳定的充分条件.仿真结果表明该双控制策略的有效性.     

基于图论的MPPT控制方法及仿真研究

太阳能发电系统中需要对输出最大功率点进行跟踪.介绍了几种常见的最大功率跟踪方法,分析了太阳能电池的系统原理,讨论了无阴影和在局部阴影下太阳能电池的电气特性曲线.在此基础上提出了基于图论的最大功率跟踪的新方法,方法可以有效地跟踪无阴影和局部阴影下太阳能电池输出的最大功率点.最后,根据太阳能电池的直流物理模型,在Simulink仿真环境下建立了太阳能电池的仿真模型并进行了仿真.     

Optimal feedback control of bilinear systems

Feedback synthesis of optimal constrained controls for single-input bilinear systems is considered. Quadratic cost functionals (with and without quadratic control penalization) are modified by the inclusion of additional nonnegative state penalizing functions in the respective cost integrands. The latter functions are chosen so as to regularize the problems, in the sense that feedback solutions of particularly simple form are obtained. Finite and infinite time horizon problem formulations are treated, and associated aspects of feedback stabilization of bilinear systems are discussed.     

Finding candidate singular optimal controls: A state of the art survey

Pontryagin's maximum principle gives no information about a singular optimal control if the problem is linear. This survey shows how candidate singular optimal controls may be found for linear and nonlinear problems. A theorem is given on the maximum order of a linear singular problem.This paper is based in part on the research undertaken by the author at the Hatfield Polytechnic, Hatfield, Hertfordshire, England, for the Ph.D. Degree.     

Applications of fuzzy logic in the control of robotic manipulators

Fuzzy logic has been utilized at several hierarchical levels of a typical robotic control system. Four broad levels of application may be identified - task design, system monitoring (including self-tuning and self-organization), information filtering and preprocessing, and in-loop direct control. Even though the need for fuzzy logic is felt mostly at upper levels of the control system, the present applications are mainly concentrated within the lowest level, perhaps driven by convenience rather than necessity. This paper surveys several applications of fuzzy logic in the control of robotic manipulators. Applications are grouped into four hierarchical categories, broadly corresponding to an existing architecture of a robotic control system. Such a classification can be beneficial in ascertaining the appropriateness of fuzzy logic for the specific control task.     

Bang-bang control of a plant with one positive real pole and one negative real pole

In this paper, a relay-controlled plant, possessing one positive real pole and one negative real pole, is studied. First, a regulating system is considered; we investigate the design of the controller for simultaneous reduction of error and error derivative to zero. It is seen that this can be achieved provided the initial values of error and error derivative fall inside an admissible (or controllable) region. Attention is then focused on the tracking system. It is shown that, provided the input to the system is of a form similar to the impulse response of the plant, and provided the initial values of error and error derivative of the system fall inside the same admissible region, then the controller used for regulating the system can also be used for tracking the system so as to force the output of the plant to follow the input perfectly; in both cases with at mostone switching reversal of the relay.     

Time-optimal control of multivariable systems near the origin

This article deals with bang-bang solutions of linear time-optimal control problems. Linear multivariable systems are considered which have one or more control components. It is shown in which way the control components act together to make the system achieve the ultimate aim (namely, the origin in the state space) as quickly as possible. The theory only applies to initial positions sufficiently near the origin. Criteria are given which give the number of switches per control component.Asymptotic dependences of the switching times and the final time on the distance of the initial position from the origin are established. The theory provides a numerical procedure to calculate the time-optimal control. These calculations are very simple. Basic to the proof of these results is a generalized implicit function theorem due to Artin (Ref. 1).     

Optimal control of a large turboalternator

The optimal torque and voltage control for a large turbogenerator is found by using the minimum norm formulation. It should be noted that the model used is highly nonlinear. Numerical results are presented.This work was supported in part by the National Research Council of Canada, Grant No. A4146.     

Revisit of Linear-Quadratic Optimal Control

The classical finite-dimensional linear-quadratic optimal control problem is revisited. A new linear-quadratic control problem with linear state penalty terms but without quadratic state penalty terms, is introduced. An optimal control exists and the closed-form optimal solution is given. It is remarkable that feedback action plays no role and state information does not feature in the optimal control. The optimal cost function, rather than being quadratic, is linear in the initial state.     

Model-based and model-free control of flexible-link robots: A comparison between representative methods

The paper presents a comparative study on representative methods for model-based and model-free control of flexible-link robots. Model-based techniques for the control of flexible-link robots can come up against limitations when an accurate model is unavailable, due to parameters uncertainty or truncation of high order vibration modes. On the other hand, several research papers argue that suitable model-free control methods result in satisfactory performance of flexible-link robots. In this paper two model-free approaches of flexible-link robot control are examined: (i) energy-based control, and (ii) neural adaptive control. The performance of the aforementioned methods is compared to the inverse dynamics model-based control, in a simulation case study for planar 2-DOF manipulators.     

孵化控制系统的模糊免疫PID控制算法研究

家禽孵化是一个复杂的生物学过程,实现其自动控制水平有着重大意义.针对孵化系统是一个多变量、强耦合、大滞后的复杂动态系统,提出一种模糊免疫P ID控制方法,该方法根据模糊控制原理对P ID参数进行在线修改,利用生物免疫机理调整非线性函数,然后用免疫修正进一步调整P ID系统参数,使被控对象具有良好的性能,实现了家禽孵化设备中温度、湿度和含氧量的智能控制.系统投入运行表明,动态响应好,控制精度高,鲁棒性高,易于各种孵化的实现,从而提高了孵化率.     

The Optimal Control of a Train

We consider the problem of determining an optimal driving strategy in a train control problem with a generalised equation of motion. We assume that the journey must be completed within a given time and seek a strategy that minimises fuel consumption. On the one hand we consider the case where continuous control can be used and on the other hand we consider the case where only discrete control is available. We pay particular attention to a unified development of the two cases. For the continuous control problem we use the Pontryagin principle to find necessary conditions on an optimal strategy and show that these conditions yield key equations that determine the optimal switching points. In the discrete control problem, which is the typical situation with diesel-electric locomotives, we show that for each fixed control sequence the cost of fuel can be minimised by finding the optimal switching times. The corresponding strategies are called strategies of optimal type and in this case we use the Kuhn–Tucker equations to find key equations that determine the optimal switching times. We note that the strategies of optimal type can be used to approximate as closely as we please the optimal strategy obtained using continuous control and we present two new derivations of the key equations. We illustrate our general remarks by reference to a typical train control problem.