基于扩张状态观测器的电力系统非线性鲁棒协调控制

该文提出了一种基于扩张状态观测器的非线性鲁棒协调控制方法(Extended-State-Observer based Nonlinear Robust Coordinated Control，ENRCC）；将电力系统对象归纳为一类内环为非线性系统、外环为伪线性系统的多输入多输出对象。在此基础上，完整地阐述了ENRCC的控制原理；利用一簇低阶扩张状态观测器对内环非线性系统进行动态反馈线性化和解耦设计，利用线性鲁棒控制方法对已线性化的内环系统和外环伪线性系统进行预期动力学设计，最终可实现观测器 线性化 鲁棒协调控制三者的有机结合。实例仿真结果表明：该控制规律严谨简单，方法原理直观清晰，便于工程应用，具有很强的适应性和鲁棒性，能有效地解决一类不确定 非线性 分散性的电力系统多输入多输出(MIMO)对象的控制问题。     

Extended disturbance observer for nonlinear system with time-varying disturbance gain

In control engineering, the disturbance is a major problem that deteriorates system robustness. To address this problem, a disturbance observer (DOB) has been proposed and developed. In particular, a general method of estimating high-order disturbance, expressed as a time series expansion, was studied (H-DOB). However, systems to which H-DOB are applicable are limited to those in which disturbance gain is constant. This constraint degrades the generality of H-DOB because applicable systems are limited. Therefore, by expanding to a system with a time-varying disturbance gain, we propose a more general H-DOB. The DOB proposed in this paper redesigns the dynamics of the observer based on the structure of the H-DOB. The proposed DOB is applicable even if the system is highly nonlinear. This paper verifies the convergence of the proposed DOB through proof. Using this proof, the same characteristic error dynamics can be obtained, so the same design method can be applied. The simulation for the verification of the proposed method performs disturbance estimation of the extension system. This simulation proves that, compared to H-DOB, the proposed DOB has good disturbance estimation performance.     

An adaptive sliding‐mode observer for a class of uncertain nonlinear systems

In this paper, the problem of simultaneous state and parameter estimation is studied for a class of uncertain nonlinear systems. A nonlinear adaptive sliding‐mode observer is proposed based on a nonlinear parameter estimation algorithm. It is shown that such a nonlinear algorithm provides a rate of convergence faster than exponential, ie, faster than the classic linear algorithm. Then, the proposed parameter estimation algorithm is included in the structure of a sliding‐mode state observer, providing an ultimate bound for the full estimation error and attenuating the effects of the external disturbances. Moreover, the synthesis of the observer is given in terms of linear matrix inequalities. The corresponding proofs of convergence are developed based on the Lyapunov function approach and input‐to‐state stability theory. Some simulation results illustrate the efficiency of the proposed adaptive sliding‐mode observer.     

一种不确定非线性系统的滑模变结构观测器的研究

由于工程实际中大部分工业对象均为非线性系统,滑模观测器应用研究的重点已从线性系统转至不确定非线性系统。针对一类非线性满足Lipschitz条件,而不确定部分为有界函数的不确定非线性系统,提出一种滑模变结构观测器设计方案,将基于线性系统提出的Walcott-Zak观测器用于抑制非线性对系统的影响,而滑模变结构使得观测器对系统不确定性具有鲁棒性。对所设计观测器的稳定性进行了证明,并通过仿真验证了所提方法的有效性。     

Observer‐based adaptive neural control of uncertain MIMO nonlinear systems with unknown control direction

This paper investigates adaptive neural network output feedback control for a class of uncertain multi‐input multi‐output (MIMO) nonlinear systems with an unknown sign of control gain matrix. Because the system states are not required to be available for measurement, an observer is designed to estimate the system states. In order to deal with the unknown sign of control gain matrix, the Nussbaum‐type function is utilized. By using neural network, we approximated the unknown nonlinear functions and perfectly avoided the controller singularity problem. The stability of the closed‐loop system is analyzed by using Lyapunov method. Theoretical results are illustrated through a simulation example. Copyright © 2012 John Wiley & Sons, Ltd.     

Adaptive neural prescribed performance output feedback control of pure feedback nonlinear systems using disturbance observer

In this study, an adaptive output feedback control with prescribed performance is proposed for unknown pure feedback nonlinear systems with external disturbances and unmeasured states. A novel prescribed performance function is developed and incorporated into an output error transformation to achieve tracking control with prescribed performance. To handle the unknown non-affine nonlinearities and avoid the algebraic loop problem, the radial basis function neural network (RBFNN) is adopted to approximate the unknown non-affine nonlinearities with the help of Butterworth low-pass filter. Based on the output of the RBFNN, the coupled design between sate observer and disturbance observer is presented to estimate the unmeasured states and compounded disturbances. Then, the adaptive output feedback control scheme is proposed for unknown pure feedback nonlinear systems, where a first-order filter is introduced to tackle with the issue of “explosion of complexity” in the traditional back-stepping approach. The boundedness and convergence of the closed-loop system are proved rigorously by utilizing the Lyapunov stability theorem. Finally, simulation studies are worked out to demonstrate the effectiveness of the proposed scheme.     

Adaptive observer for a class of nonlinear systems with time‐varying delays

The adaptive observer design problems have been extensively studied in literature for both linear and nonlinear systems. Some researches have also been carried out on adaptive observer design for linear time‐delay systems, but there is no significant work on adaptive observer design for nonlinear time‐delay systems. In this work, the adaptive observer design problem for a class of nonlinear time‐delay systems is considered. The observer is designed for the nonlinear systems whose nonlinear functions satisfy Lipschitz condition. Like conventional adaptive observers for the systems without time delays, this observer also estimates both states and unknown parameters simultaneously. For this property, it will be very much useful for many real‐time systems where time delays cannot be avoided. The sufficient conditions for existence of the observer are derived using the linear matrix inequality approach. With the help of a numerical example, effectiveness of the proposed observer is demonstrated. Copyright © 2012 John Wiley & Sons, Ltd.     

Sliding mode control for a class of uncertain nonlinear system based on disturbance observer

In this paper, a sliding mode control (SMC) scheme is proposed for a class of nonlinear systems based on disturbance observers. For a nonlinear system, the disturbance that cannot be directly measured is estimated using a nonlinear disturbance observer. By choosing an appropriate nonlinear gain function, the disturbance observer can well approximate the unknown disturbance. Based on the output of the disturbance observer, an SMC scheme is presented for the nonlinear system, and the stability of the closed‐loop system is established using Lyapunov method. Finally, two simulation examples are presented to illustrate the features and the effectiveness of the proposed disturbance‐observer‐based SMC scheme. Copyright © 2009 John Wiley & Sons, Ltd.     

无刷直流电机速度观测器的设计

基于无刷直流电机的线性时变多输入一多输出（MIMO）模型。提出一种速度观测器的设计方案。该速度观测器是线性的全维状态观测器,具有算法简单、收敛性好、观测精度高的特点。仿真结果证明了本文所提方法的正确性和有效性。     

离散时间非线性系统的观测器设计

针对离散时间Lipschitz非线性系统的观测器设计问题,依据离散时间系统的Lyapunov稳定性理论,研究了保证观测误差渐近稳定的充分条件,并依据该条件应用线性矩阵不等式方法,得到了观测器增益矩阵的设计方法。所得方法计算简便,并通过算例说明该方法的应用。     

A new identity dimensional D‐state observer for sensorless drive of permanent‐magnet synchronous motors

A new identity dimensionless D‐state observer whose state variables are the stator reaction flux and rotor flux is proposed for the sensorless drive of permanent‐magnet synchronous motors. Furthermore, sufficient conditions are newly and analytically derived for the observer gains that guarantee stable convergence of state variable estimates. Additionally, two new methods for designing observer gain are presented; these methods, the constant and speed‐dependent gain methods, satisfy the derived analytical conditions. The observer gain conditions used in the design methods are validated through extensive numerical experiments. In addition, typical design examples of the observer gains using the proposed design methods are presented. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 181(1): 45–61, 2012; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.21200     

An adaptive robust observer for velocity estimation in an electro‐hydraulic system

This paper proposes the design of an observer to estimate the velocity of an electro‐hydraulic system by using pressure measurements only. The difficulties involved in the design of an observer for such a system include the highly nonlinear system dynamics, severe parametric uncertainties such as large variation of inertial load and unmatched model uncertainties. In order to address these issues, a nonlinear model‐based adaptive robust observer is designed to estimate the velocity. The contributions of the proposed work is twofold. First, it introduces a novel coordinate transformation to reconstruct the velocity estimate. And second, from a structural viewpoint, the design has two important features: (i) an underlying robust filter structure, which can attenuate the effect of uncertain nonlinearities such as friction and disturbances on the velocity estimation, and (ii) an adaptation mechanism to reduce the extent of parametric uncertainties. Experimental results on the swing motion control of an electro‐hydraulic robot arm demonstrate the effectiveness of the proposed observer. Copyright © 2012 John Wiley & Sons, Ltd.     

智能变结构状态观测器的研究

针对一类非线性系统 ,研究了智能变结构状态观测器的设计问题。文中首先提出采用B样条模糊神经网络对系统不确性进行补偿并减少观测器抖动的方法 ,然后给出网络的在线自学习算法 ,最后将所提出的方法应用到感应电动机的转子磁通观测器设计中。实验结果验证了该设计方法的有效性     

基于扩张状态观测器的水轮发电机组非线性控制

提出了一种基于扩张状态观测器的水轮发电机组非线性控制。将被控对象看成是内环为非线性系统、外环为伪线性系统的多输入多输出对象，利用低阶扩张状态观测器对内环非线性系统进行动态反馈线性化，利用线性控制方法对已线性化的外环伪线性系统进行预期动态性能设计，最终可实现观测器和线性化的有机结合。计算机仿真表明：这种控制方法不仅能较好地解决开度控制和励磁控制的协调性，而且对模型的内外扰表现出了很好的适应性和鲁棒性；同时，这种控制方法严谨简单，原理直观清晰。     

Robust stabilization of a class of non‐minimum‐phase nonlinear systems in a generalized output feedback canonical form

In this paper, a globally robust stabilizer for a class of uncertain non‐minimum‐phase nonlinear systems in generalized output feedback canonical form is designed. The system contains unknown parameters multiplied by output‐dependent nonlinearities and output‐dependent nonlinearities enter such a system both additively and multiplicatively. The proposed method relies on a recently developed novel parameter estimator and state observer design methodology together with a combination of backstepping and small‐gain approach. Our design has three distinct features. First, the parameter estimator and state observer do not necessarily follow the classical certainty‐equivalent principle any more. Second, the design treats unknown parameters and unmeasured states in a unified way. Third, the technique by combining standard backstepping and small‐gain theorem ensures robustness with respect to dynamic uncertainties. Finally, two numerical examples are given to show that the proposed method is effective, and that it can be applied to more general systems that do not satisfy the cascading upper diagonal dominance conditions developed in recent papers, respectively. Copyright © 2008 John Wiley & Sons, Ltd.     

一类四阶非线性系统的滑模模糊控制

针对一类非线性系统的稳定控制问题，提出了带有模糊状态观测器滑模模糊控制器的设计方法。对二阶非线性系统设计滑模模糊控制器，以滑模面作为模糊控制器的输入设计模糊控制规则；研究四阶非线性系统，将它分解成两个二阶子系统，设计两个子系统各自的滑模面；然后将一个子系统的控制目标嵌入到另一个子系统的控制目标中，用一个控制量使两个子系统同时向各自的滑模面趋近，使该四阶系统稳定。倒立摆的仿真结果表明，这种滑模模糊控制器对于参数变化和初始条件具有很强的鲁棒性。     

一类不确定非线性系统的鲁棒状态观测器设计

本文研究了一类具有参数不确定性的非线性系统鲁棒状态观测器的设计问题。提出了一种新的非线性鲁棒渐近状态观测器设计方案,证明了状态观测误差的指数渐近收敛性。最后将所得结果应用于一轴盘传动系统,仿真结果表明本文提出的设计方案是有效的。     

Hyperstability of the full-order observer for vector-controlled induction motor drive without speed sensor

Vector-controlled induction motor drive systems without speed sensors have been widely studied. Speed estimation can be treated as a problem of parameter estimation under the theory of MRAS (model reference adaptive systems). In such cases, the convergence and robustness of the system are major issues. In this paper, we discuss the stability of an MRAS, that includes a full-order adaptive observer of the induction motor and is used for estimating the rotor speed and identifying the stator resistance. It is verified that, under some conditions, the transfer matrix in the forward path of the MRAS is strictly positive-real and that the non-linear block in the feedback path satisfies Popov's criterion. As a result, the system is hyperstable. The influence of the set error of the rotor resistance is discussed and the design criterion for the feedback gain of the observer is presented. Finally, the system is linearized for the parameter design of the speed estimator.     

基于非线性观测器的永磁同步电机位置估计算法研究

为提高表贴式永磁同步电机无位置传感器控制中转子位置和速度的估计精度,提出了一种改进型非线性观测器。通过重构非线性观测器的数学模型,构建了误差方程,利用Lyapunov理论对误差方程进行了稳定性分析。并基于稳定性条件提出了一种误差项步长优化方法,实现了非线性观测器的步长增益自调节。仿真与试验结果表明,改进型非线性观测器具有良好的动态性能,验证了其可行性。     

Luenberger-type cubic observers for state estimation of linear systems

This article introduces a new nonlinear observer for state estimation of linear time invariant systems. The proposed observer contains a (nonlinear) cubic term to enhance observer response. Unlike previously proposed observers, the cubic observer has nonlinear estimation error dynamics. Convergence criteria, performance advantages, and observer-based feedback control with cubic observers are addressed. Simulation examples demonstrating performance improvement compared with linear observers, are included.