并网光伏逆变器鲁棒分数阶滑模控制设计

本文设计了一款基于扰动观测器的鲁棒分数阶滑模控制(POFO–SMC)来实现光伏逆变器的最大功率跟踪(MPPT).首先,将光伏逆变器的非线性、参数不确定性以及未建模动态聚合成一个扰动,并通过扰动观测器对其进行在线估计.随后,采用分数阶滑模控制(FOSMC)对该扰动估计进行实时完全补偿,从而实现不同工况下全局一致的控制性能.同时,POFO–SMC采用扰动实时估计而非传统滑模控制(SMC)中所使用的扰动上限值进行补偿,因此可有效解决传统SMC过于保守的缺点,使得控制成本更为合理.最后,POFO–SMC无需精确的系统模型,仅需测量光伏逆变器的q轴电流和直流侧电压,因此易于硬件实现.本文进行了两个算例的研究,即光照强度变化和电网电压跌落.仿真结果表明,与传统PI控制、反馈线性化控制(FLC)、SMC和FOSMC相比,POFO–SMC在各类工况下均具有最好的动态特性及最高的鲁棒性.基于dSpace的硬件在环实验(HIL)验证了其硬件可行性.     

Design and Robust Performance Evaluation of a Fractional Order PID Controller Applied to a DC Motor

This paper proposes a methodology for the quantitative robustness evaluation of PID controllers employed in a DC motor. The robustness analysis is performed employing a 23 factorial experimental design for a fractional order proportional integral and derivative controller (FOPID), integer order proportional integral and derivative controller (IOPID) and the Skogestad internal model control controller (SIMC). The factors assumed in experiment are the presence of random noise, external disturbances in the system input and variable load. As output variables, the experimental design employs the system step response and the controller action. Practical implementation of FOPID and IOPID controllers uses the MATLAB stateflow toolbox and a NI data acquisition system. Results of the robustness analysis show that the FOPID controller has a better performance and robust stability against the experiment factors.      

Local Bifurcation Analysis of a Delayed Fractional-order Dynamic Model of Dual Congestion Control Algorithms

In this paper, we propose a delayed fractional-order congestion control model which is more accurate than the original integer-order model when depicting the dual congestion control algorithms. The presence of fractional orders requires the use of suitable criteria which usually make the analytical work so harder. Based on the stability theorems on delayed fractionalorder differential equations, we study the issue of the stability and bifurcations for such a model by choosing the communication delay as the bifurcation parameter. By analyzing the associated characteristic equation, some explicit conditions for the local stability of the equilibrium are given for the delayed fractionalorder model of congestion control algorithms. Moreover, the Hopf bifurcation conditions for general delayed fractional-order systems are proposed. The existence of Hopf bifurcations at the equilibrium is established. The critical values of the delay are identified, where the Hopf bifurcations occur and a family of oscillations bifurcate from the equilibrium. Same as the delay, the fractional order normally plays an important role in the dynamics of delayed fractional-order systems. It is found that the critical value of Hopf bifurcations is crucially dependent on the fractional order. Finally, numerical simulations are carried out to illustrate the main results.      

两个分数阶复杂动态网络的函数投影同步

复杂网络的同步问题是复杂网络研究的热点之一, 本文研究了两个分数阶复杂网络间的函数投影同步问题.分别针对网络模型参数已知和参数未知两种情况, 利用自适应控制技术和分数阶系统稳定性理论, 设计自适应控制器, 使两个分数阶复杂动态网络实现函数投影同步.最后利用数值仿真验证所提出方法的有效性.     

分数阶Rossler混沌系统的模糊同步控制

采用分数阶T-S模糊模型对分数阶Rossler混沌系统建模．使用并行分布式补偿方法设计模糊状态反馈控制器,使得闭环系统极点位于稳定区域内,从而保证闭环系统满足渐近稳定性条件．利用所设计的模糊状态反馈同步控制器实现了两个具有不同初始条件的分数阶Rossler混沌系统的同步．数值仿真结果表明该方案的有效性．     

绳驱动空中机械臂的自适应分数阶终端滑模控制

针对集总干扰下绳驱动空中机械臂关节空间内高精度轨迹跟踪控制问题,提出了一种基于时延估计技术的自适应鲁棒控制策略。在控制框架中,引入时延估计技术来补偿系统未建模特性、外界扰动及动力学耦合效应;采用分数阶非奇异终端滑模面来加快系统状态量的收敛速度和保证轨迹跟踪控制的精度;添加自适应律来增加控制器的鲁棒性。同时,基于李雅普诺夫稳定性理论分析了闭环系统的稳定性。最后,通过可视化仿真和地面试验对本文所设计控制器的有效性进行了验证,结果表明：与其他两种控制器相比,本文控制器具有较高的轨迹跟踪精度、较好的鲁棒性和较强的抗干扰能力。     

基于分数阶忆容器的有源滤波器设计

在分析研究整数阶忆容器模型和分数阶忆容器模型的基础上,提出了一种具有两个分数阶阶次的忆容器模型,并对其相关特性进行了分析。将此模型应用于有源低通滤波电路中,仿真分析了含有分数阶忆容器的有源低通滤波电路的时域和频域特性。实验结果表明,与整数阶忆容器模型相比,提出的分数阶忆容器模型可以通过改变分数阶阶次来调整低通滤波电路的截止频率,进而改变低通滤波电路的滤波效果。     

Adaptive fractional-order nonsingular fast terminal sliding mode formation control of multiple quadrotor UAVs-based distributed estimator

This paper mainly solves two major problems that are unavoidable in leader–follower formation process of quadrotor UAV group: the existence of external uncertainty disturbance and communication limited between quadrotor unmanned aerial vehicle (UAV) group. To solve the problem that only one of the followers in the leader–follower formation can obtain the leader's information, an improved distributed estimator is proposed in this paper, which can accurately estimate the leader's information for each follower. In addition, in order to eliminate the influence of uncertain external disturbance on the performance of quadrotor UAV, an adaptive estimation law is designed based only on velocity and position variables. For the attitude and position subsystem of the quadrotor UAV, a sliding surface with fractional-order term is designed. Which makes the quadrotor UAV tracking error system obtain good robustness at the stage of reaching the sliding surface and fast convergence and accurate tracking performance in the sliding stage. Based on Lyapunov stability theory, the convergence results are analyzed strictly. The results show that the algorithm can make the position distance between leader and followers converge to the desired offset. Simulation results verify the effectiveness and superiority of the control algorithm.     

计及温控负荷响应的二维云模型分布式频率控制

为改善电力系统频率稳定性,充分调用需求侧可控负荷资源,本文提出一种计及温控负荷响应的二维云模型分布式频率控制方法。建立了多区域互联电力系统负荷频率控制模型,设计了基于福克普朗克方程的温控负荷分布式控制策略,同时采用云模型算法与分数阶微积分理论,设计了二维云模型分数阶PID分布式频率控制器。最后通过控制仿真比较与分析,验证了在不同运行场景下所提出的综合控制方法具有较优的动稳态性能。结果表明该控制方法是可行和有效的。     

一种分数阶忆阻器的Verilog-A模型及应用

近年来,科研人员为研究忆阻器的电气特性及其在电路中的应用,建立了多种整数阶忆阻器的Verilog-A模型,但分数阶忆阻器的Verilog-A模型还未见报道。文章提出了一种分数阶忆阻器的Verilog-A模型,对其相关特性进行了分析,总结了参数对忆阻器电气特性影响的规律,并将此模型应用于脉冲宽度调制(PWM)电路中,通过改变分数阶阶次来调整PWM电路的占空比。实验结果证明了分数阶忆阻器Verilog-A模型的正确性和实用性。