Robust non-fragile power system stabilizer

This paper presents a step towards the design of robust non-fragile power system stabilizers (PSSs) for single-machine infinite-bus systems. To ensure resiliency of a robust PSS, the proposed approach presents a characterization of all stabilizers that can guarantee robust stability (RS) over wide range of operating conditions. A three-term controller (x₁ + x₂s)/(1 + x₃s) is considered to accomplish the design. Necessary and sufficient stability constraints for existing of such controller at certain operating point are derived via Routh–Hurwitz criterion. Continuous variation in the operating point is tackled by an interval plant model where RS problem is reduced to simultaneous stabilization of finite number of plants according to Kharitonov theorem. Controller triplets that can robustly stabilize vertex plants are characterized in a similar manner. The most resilient controller is computed at the center of maximum-area inscribed rectangle. Simulation results confirm robustness and resiliency of the proposed stabilizer.     

H robust stabilizability

In this paper, we improve on the results of robust stabilizability obtained by Kimura. We do this in a constructive way by using an H^∞-approach, and exhibit an upper bound for the order of robust controllers.     

Performance enhancement of two-degree-of-freedom controllers via adaptive techniques

This paper generalizes earlier results on adaptive disturbance estimate (innovations) feedback regulation to the case of adaptive tracking, refining some of the techniques and formulations in the process. The adaptations proposed search within the class of all stabilizing two-degree-of-freedom controllers for a nominal plant and minimize a reference signal/disturbance rejection measure. The emphasis in the paper is on issues relevant to the tracking task and simulation results to demonstrate the effectiveness of the approach. The adaptive scheme is based on results concerning the convenient characterization of the class of all stabilizing two-degree-of-freedom controllers in terms of an arbitrary filter Q with a stable proper transfer function matrix Q(s). The fact that the closed-loop transfer matrices are affine in Q(s) permits a straightforward on-line least-squares update of the parameters of the filter Q on-line. The theory for the class of stabilizing controllers is used to set up appropriate signal preprocessing. The direct adaptive schemes proposed turn out to be recursive prediction error schemes which have local convergence properties. When convergent, they ensure enhancement of the performance of a fixed controller in other than the nominal plant case.     

High-gain robust adaptive controllers for multivariable systems

This paper extends the switching free high-gain stabilizing adaptive control rules of Byrnes and Willems to a wide class of adaptive schemes capable of tolerating nonlinear state feedback perturbations.     

Integral controller design based on disturbance cancellation: Partial LTR approach for non-minimum phase plants

For non-minimum phase plants, the loop transfer recovery (LTR) design of integral controllers based on the disturbance cancellation is considered. Since the design requires an unstabilizable extended plant, the standard LTR method cannot be applied. A new partial LTR method is proposed to overcome the difficulty. The target of the proposed design is a fictitious controller including a disturbance estimator based on the measurement of the minimum phase state. It is shown that the Riccati equation including the gain matrix of the disturbance estimator in the target can be used to recover the target feedback property in the output feedback controller. A simple design example is presented to show the effectiveness of the proposed method.     

Direct adaptive tuning of robust controllers with guaranteed stability properties

We address the following problem: given a fixed regulator that insures closed-loop stability for a partially known plant, design a mechanism to adaptively tune the controller parameters in order to improve performance. Our main concern is to insure that global _∞-stability of the overall system is preserved. The proposed parameter update law includes a signal normalization [1] and a σ-modification [2]. The condition for global _∞-stability relates the margin of stability of the closed-loop linear system, the speed of adaptation and the size of the residual set for the tracking error.     

Model-based optimal and robust control of renewable hydrogen gas production in a fed-batch microbial electrolysis cell

Microbial electrolysis cell (MEC) is a fundamental type of bio-electrochemical system. MEC is a novel and emerging renewable energy technology that is based on biomass. The behavior of the MEC system is highly nonlinear due to the complexity of its dynamics. For the desired optimal production of hydrogen, feedback control of MEC processes is necessary. Due to the novelty of MEC, limited research is available on its control. Studies on linear model-based robust control of MEC processes are missing. In this article, we develop a nonlinear dynamic model for MEC, linearize this model, and calculate a linear time-invariant transfer function. Based on this linearization, a fixed-structure, optimal and robust controller is proposed to achieve a fast-settling time exhibiting no overshoot and having zero steady-state error. The robustness of the developed controller is evaluated for parameter uncertainty, measurement noise, and disturbance rejection. Batch biomass processes are fed only at the start of each process cycle. The output does not follow the desired response when the substrate or biomass is consumed. Then, the error accumulates, and it causes the control effort to increase unboundedly. The existing literature on control of fed-batch MEC processes does not consider this integral windup phenomenon. In this article, we also develop an anti-windup control strategy to eliminate the integral windup error and to avoid any possible instability or destruction. The overall conclusion of our study is that the developed robust controller achieves a faster and more robust response than the existing controllers. We provide an anti-integral windup solution to eliminate windup errors in feedback control of fed-batch MEC processes.     

State feedback control of continuous-time T-S fuzzy systems via switched fuzzy controllers

This paper studies the problem of state feedback control of continuous-time T-S fuzzy systems. Switched fuzzy controllers are exploited in the control design, which are switched based on the values of membership functions, and the control scheme is an extension of the parallel distributed compensation (PDC) scheme. Sufficient conditions for designing switched state feedback controllers are obtained with meeting an H_∞ norm bound requirement and quadratic D stability constraints. It is shown that the new control design method provides less conservative results than the corresponding ones via the parallel distributed compensation (PDC) scheme. A numerical example is given to illustrate the effectiveness of the proposed method.     

多媒体教室智能管理系统的设计与实现

针对高校多媒体教室电能浪费严重、资源利用不合理以及用电设备、教学管理不足等问题,利用恩智浦公司的Cortex M0芯片,设计了以智能网关控制器为核心的教学楼智能管理系统,实现了合理使用教室用电设备,达到了节约电能、改善教学管理的目的。     

一种新的全镇定控制器的参数设计法研究

Youla参数化方法广泛应用于控制系统的分析和设计;此方法使得系统闭环稳定的全部的镇定控制器均以一个稳定传递函数作为待定参数来表达;建立另外一种不同的参数化方法,这种方法尤其适用于主动振动控制系统:它不仅参数化所有镇定控制器,同时能够给控制性能变量以非常直观的几何图形解释;讨论这种新方法的特性及其设计,并将该设计方法应用于一个三自由度的主动振动隔离系统中,仿真结果表明,所提出的方法可以有效地达到主动振动隔离的设计目的。