μ-Synthesis control with reference model for aeropropulsion system test facility under dynamic coupling and uncertainty

Due to the dynamic coupling and multi-source uncertainties,it is difficult to accurately control the pressure and temperature of the Aeropropulsion System Test Facility(ASTF)in the presence of rapid command and large disturbance.This paper presents the design ofμ-synthesis control to solve the problem.By incorporating the pressure ratio into the linear equation of the control valve,the modeling error of ASTF in the low frequency range is effectively reduced.Then,an uncertain model is established by considering various factors,including parameter variations,modeling error in the low frequency range,unmodeled dynamics,and changes in the working point.To address the dynamic coupling,a diagonal reference model with desired performance is incorporated intoμ-synthesis.Furthermore,all weighting functions are designed according to the performance requirements.Finally,theμ-controller is obtained by using the standardμ-synthesis method.Simulation results indicate that theμ-controller decouples the pressure and temperature dynamics of ASTF.Compared with the multivariable PI controller,integral-μcontroller,and double integral-μcontroller,the proposedμ-controller can achieve higher transient accuracy and better disturbance rejection.Moreover,the robustness of theμ-controller is demonstrated by Monte Carlo simulations.

振动系统鲁棒μ_(-synthesis)控制实验研究

基于结构奇异值μ-synthesis鲁棒控制理论,研究振动响应的主动控制问题,提出设计鲁棒μ-synthesis控制器的方法。采用dSPACE DS 1103为控制器硬件,建立以压电陶瓷为致动器的单输入单输出薄板振动主动控制实验系统,且附加质量被粘贴到薄板上以测试系统鲁棒性能。实验结果表明,通过对性能加权函数和鲁棒加权函数的选取,系统能在指定频带上取得良好的减振控制效果,当压电板发生一定程度的质量摄动时,系统依然能保持稳定且仍具有较好的控制效果。

基于鲁棒μ_(-synthesis)的多输入多输出振动主动控制实验

基于结构奇异值μ-synthesis鲁棒控制理论,建立多输入多输出结构振动响应的反馈控制模型,提出设计鲁棒μ-synthesis控制器的方法。以dSPACE为控制硬件核心,采用压电陶瓷为致动器,建立两输入两输出的薄板振动主动控制实验系统,且附加质量被粘贴到薄板上以测试系统鲁棒性能。实验结果表明,通过对性能加权函数和鲁棒加权函数的选取,系统能在指定频带上取得良好的减振控制效果,当薄板发生一定程度的质量摄动时,系统依然能保持稳定且仍具有较好的控制效果。

μ_(-synthesis)方法在结构—声耦合系统鲁棒控制中的应用

以在工程中普遍存在的封闭空间结构—声耦合系统为对象,基于鲁棒结构奇异值理论,建立了结构—声耦合系统鲁棒主动控制模型,提出了设计鲁棒-μsynthesis控制器的方法:通过引入虚拟的不确定块,将耦合系统响应性能的问题转化为广义系统的稳定鲁棒性问题,采用标准D-K迭代法求解该增量系统的稳定鲁棒控制器。封闭空间结构—声耦合系统的控制仿真表明,同鲁棒H∞控制结果相比,-μsynthesis方法对模型不确定性具有良好的稳定鲁棒性和性能鲁棒性。同以往的研究相比,新意在于应用-μsynthesis方法设计了结构—声耦合系统鲁棒控制器,以克服H∞控制器的不足。

结构振动噪声的鲁棒结构奇异值控制研究

以工程中普遍存在的封闭空间结构-声耦合系统为对象,基于鲁棒结构奇异值理论,建立了结构-声耦合系统鲁棒主动控制模型,提出了设计鲁棒μ-synthesis控制器的方法。通过引入虚拟的不确定块,将耦合系统响应性能的问题转化为广义系统的稳定鲁棒性问题求解,兼顾了系统的稳定鲁棒性和性能鲁棒性。封闭空间结构-声耦合系统的控制仿真表明,与鲁棒H_∞控制结果相比,μ-synthesis方法对模型不确定性具有良好的稳定鲁棒性和性能鲁棒性。

基于模型不确定性鲁棒结构奇异值控制研究

基于鲁棒结构奇异值理论,以工程中普遍存在的封闭空间结构———声耦合模型不确定性系统为对象,提出了设计鲁棒控制器的方法,建立了结构-声耦合系统鲁棒主动控制模型,与鲁棒H∞控制结果相比,μ-synthesis方法对模型不确定性具有良好的稳定鲁棒性和性能鲁棒性。

Robust Controller Synthesis and Analysis in Inverter-Dominant Droop-Controlled Islanded Microgrids

This work investigates the problem of controller design for the inverters in an islanded microgrid.Robust-synthesis controllers and local droop controllers are designed to regulate the output voltages of inverters and share power among them,respectively.The designed controllers alleviate the need for additional sensors to measure the states of the system by relying only on output feedback.It is shown that the designed-synthesis controller properly damps resonant oscillations,and its performance is robust to the control-loop time delay and parameter uncertainties.The stability of a droop-controlled islanded microgrid including multiple distributed generation(DG)units is analyzed by linearizing the nonlinear power flow model around the nominal operating point and applying theorems from linear algebra.It is indicated that the droop controller stabilizes the microgrid system with dominantly inductive tie-line impedances for all values of resistive-inductive loads,while for the case of resistive-capacitive loads the stability is conditioned on an upper bound on the load susceptances.The robust performance of the designed-synthesis controller is studied analytically,compared with the similar analysis in an control(benchmark)framework,and verified by simulations for a four DG benchmark microgrid.Furthermore,the robustness of the droop controllers is analyzed by Monte Carlo simulations in the presence of local voltage fluctuations and phase differences among neighboring DGs.

Integrated Fuzzy Robust Controller for Flight Control Design

μ-synthesis is a practical design approach and has been applied successfully to achieve a nominal and robust performance objectives. However, this design method suffers from the complexity of its practical implementation and high computational demand due to its high order dynamics. To overcome this problem, the interaction between fuzzy logic control which is a part of intelligence control theory and p-synthesis controller is carried out. This is called integrated fuzzy robust controller in this paper. It is obtained by coupling fuzzy pd with p-synthesis controller through the outer loop. Using this design strategy, we can keep the system performance and robustness even a high order p-synthesis controller is reduced into second order model. In order to test the effectiveness of this design method, the linear simulation results for a launch vehicle＇s attitude control motion are presented at the end of this paper.

FIRST-ORDER METHODS FOR SOLVING THE OPTIMAL STATIC H∞-SYNTHESIS PROBLEM

In this paper, we consider the static output feedback （SOF） H∞-synthesis problem posed as a nonlinear semi-definite programming （NSDP） problem. Two numerical algorithms are developed to tackle the NSDP problem by solving the corresponding Karush- Kuhn-Tucker first-order necessary optimality conditions iteratively. Numerical results for various benchmark problems illustrating the performance of the proposed methods are given.

Robust subsynchronous interaction damping controller for DFIG-based wind farms

This paper proposes a robust controller to improve power system stability and mitigate subsynchronous interaction(SSI)between doubly-fed induction generator(DFIG)-based wind farms and series compensated transmission lines.A robust stability analysis is first carried out to show the impact of uncertainties on the SSI phenomenon.The uncertainties are mainly due to the changes in the power system impedance(e.g.,transmission line outages)and the variations of wind farm operating conditions.Then,using theμ-synthesis technique,a robust SSI damping controller is designed and augmented to the DFIG control system to effectively damp the SSI oscillations.The output signals of the supplementary controller are dynamically limited to avoid saturating the converters and to provide DFIG with the desired fault-ride-through(FRT)operation during power system faults.The proposed controller is designed for a realistic test system with multiple series capacitor compensated lines.The frequency of the unstable SSI mode varies over a wide range due to the changes in power system topologies and wind farm operating conditions.The performance of the proposed controller is verified through electromagnetic transient(EMT)simulations using a detailed wind farm model.Simulation results also confirm the grid compliant operation of the DFIG.

Double-loop robust tracking control for micro machine tools

This paper addresses double-loop robust tracking controller design of the miniaturized linear motor drive precision stage with mass and damping ratio uncertainties. As an inner-loop, a disturbance observer （DOB） is employed to suppress exogenous low frequency disturbances such as friction and cutting force. To further eliminate the residual disturbance and to guarantee the robust tracking to the reference input, μ-synthesis outer-loop controller is designed. For eliminating the steady state error, a technique is proposed to design the μ-synthesis outer-loop controller with an integrator. A guideline to select the bandwidth of the Q-filter in the DOB is provided. Simulations using a model of a prototype micro-milling machine indicate that the proposed outer-loop synthesis scheme is superior to the H∞ suboptimal control in disturbance rejection performance and steady state tracking performance. Furthermore, it is shown experimentally that the proposed double-loop robust tracking controller improves the tracking performance of the stage by 29.6% over PID control with a DOB inner-loop.