电力系统非线性切换励磁控制

针对反馈线性化方法难以同时提高电力系统的功角稳定性和电压调节特性的问题,提出了基于分层设计思想的非线性切换励磁控制方法.首先采用逆系统方法实现了系统的反馈线性化,然后根据Lyapunov函数方法对包含零动态的部分线性化系统设计了切换励磁控制器.在电力系统专用仿真平台上的仿真结果证明了所设计的切换控制器能够有效改善功角稳...     

Perturbation estimation based coordinated adaptive passive control for multimachine power systems

This paper proposes a perturbation estimation based coordinated adaptive passive control (PECAPC) of generators excitation system and thyristor-controlled series capacitor (TCSC) devices for complex, uncertain and interconnected multimachine power systems. Discussion begins with the PECAPC design, in which the combinatorial effect of system uncertainties, unmodelled dynamics and external disturbances is aggregated into a perturbation term, and estimated online by a perturbation observer (PO). PECAPC aims to achieve a coordinated adaptive control between the excitation controller (EC) and TCSC controller based on the nonlinearly functional estimate of the perturbation. In this control scheme an explicit control Lyapunov function (CLF) and the strict assumption of linearly parametric uncertainties made on system structures can be avoided. A decentralized stabilizing EC for each generator is firstly designed. Then a coordinated TCSC controller is developed to passivize the whole system, which improves system damping through reshaping the distributed energies in power systems. Case studies are carried out on a single machine infinite bus (SMIB) and a three-machine system, respectively. Simulation results show that the PECAPC-based EC and TCSC controller can coordinate each other to improve the power system stability, finally a hardware-in-the-loop (HIL) test is carried out to verify its implementation feasibility.     

Nonlinear excitation controller design for power systems： an I＆I approach

The Immersion and Invariance(I&I) methodology provides a novel approach for nonlinear system control, which is distinct from the traditional feedback linearization and backstepping method.In this paper,a new excitation controller is designed for single machine infinite bus system(SMIBS) based on the I&I approach.Firstly the dynamic model of SMIBS is homeomorphously transformed to a specific form for which a stable lower-order target system is selected.Then the I&I excitation controller is designed by immersing the transformed system into the target system.Simulation results from PSCAD/EMTDC demonstrate that the proposed controller guarantees transient stability of the system after large disturbances.     

基于反馈线性化的TCSC滑模控制

针对含可控串联补偿(Thyristor Controlled Series Compensation,TCSC)的电力系统非线性强及易受外部扰动的特点,应用反馈线性化方法和滑模变结构控制理论,设计了提高系统稳定性的可控串联补偿滑模控制器。通过引入反馈控制变量,基于状态反馈线性化理论实现了对非线性模型的精确线性化。采用极点配置方法设计滑模切换函数,从理论上保证发电机转子方程具有期望的极点。为了减小抖振采用指数趋近律和准滑动模态方法求取滑模控制律,使得设计的可控串联补偿非线性控制律形式简洁,鲁棒性好。为了验证该控制策略的有效性,在Matlab/Simulink环境下建立了基于反馈线性化的可控串联补偿滑模控制系统仿真模型,进行了仿真研究。仿真结果表明,与传统的控制方式相比,设计的控制器能有效地阻尼系统振荡,增强系统的暂态稳定性。     

Adaptive RTRL based neurocontroller for damping subsynchronous oscillations using TCSC

Modern interconnected electrical power systems are complex and require perfect planning, design and operation. Hence the recent trends towards restructuring and deregulation of electric power supply has put great emphasis on the system operation and control. Flexible AC transmission system (FACTS) devices such as thyristor controlled series capacitor (TCSC) are capable of controlling power flow, improving transient stability and mitigating subsynchronous resonance (SSR). In this paper an adaptive neurocontroller is designed for controlling the firing angle of TCSC to damp subsynchronous oscillations. This control scheme is suitable for non-linear system control, where the exact linearised mathematical model of the system is not required. The proposed controller design is based on real time recurrent learning (RTRL) algorithm in which the neural network (NN) is trained in real time. This control scheme requires two sets of neural networks. The first set is a recurrent neural network (RNN) which is a fully connected dynamic neural network with all the system outputs fed back to the input through a delay. This neural network acts as a neuroidentifier to provide a dynamic model of the system to evaluate and update the weights connected to the neurons. The second set of neural network is the neurocontroller which is used to generate the required control signals to the thyristors in TCSC. This is a single layer neural network. Performance of the system with proposed neurocontroller is compared with two linearised controllers, a conventional controller and with a discrete linear quadratic Gaussian (DLQG) compensator which is an optimal controller. The linear controllers are designed based on a linearised model of the IEEE first benchmark system for SSR studies in which a modular high bandwidth (six-samples per cycle) linear time-invariant discrete model of TCSC is interfaced with the rest of the system. In the proposed controller, since the response time is highly dependent on the number of states of the system, it is often desirable to approximate the system by its reduced model. By using standard Hankels norm approximation technique, the system order is reduced from 27 to 11th order by retaining the dominant dynamic characteristics of the system. To validate the proposed controller, computer simulation using MATLAB is performed and the simulation studies show that this controller can provide simultaneous damping of swing mode as well as torsional mode oscillations, which is difficult with a conventional controller. Moreover the fast response of the system can be used for real-time applications. The performance of the controller is tested for different operating conditions.     

Energy-shaping control of synchronous generators with exciter-governor dual control loops

In this paper we extend the energy-shaping controller design technique, which has been successfully used for single-loop excitation regulation of synchronous generators in power systems, to the exciter–governor dual configuration. As in the simpler excitation problem, the aim of the controller is to shape the total energy function via modification of the energy transfer between electrical and mechanical subsystems—but in this dual scenario we also have to take into account the energy contribution of the governor control loop dynamics. Motivated by practical considerations we also present a partial state feedback version of the controller that is derived applying thoe immersion and invariance technique recently reported in the literature. Representative simulations show how the tuning parameters effectively shape the domain of attraction of the desired stable equilibrium enhancing the transient stability of the power system.     

Differential evolutionary algorithm for TCSC-based controller design

In this paper, a systematic procedure for modelling, simulation and optimal tuning the parameters of a thyristor controlled series compensator (TCSC) controller, for the power system stability enhancement is presented. The design problem of the proposed controller is formulated as an optimization problem and differential evolution (DE) is employed to search for optimal controller parameters. A detailed analysis on the selection of objective function and controller structure on the effectiveness of the TCSC controller is carried out and simulation results are presented. The dynamic performance TCSC controller under various loading and disturbance conditions are analyzed and compared. Finally, the proposed design approach is extended to a multi-machine power system for simultaneous design of multiple and multi-type controllers.     

交直流混合输电系统的新型无源性调制

交直流混合输电系统的动态响应性能直接影响电力系统的稳定性.为提高系统的动态响应速度和控制器的鲁棒性,本文基于无源性理论从具体结构出发,设计了直流输电系统的无源性调制控制器.以交直流并联的两机系统为研究对象,对系统的输入输出进行重构,并对系统的无源性进行验证.根据稳定性和无源性之间的关系,设计出反馈控制规律.对两种不同情况的仿真,显示出该控制律在保证系统的稳定性的同时.提高了系统的动态响应速度.     

基于状态反馈控制器的多无人水面船集群控制

研究在时变环境干扰和输入饱和约束条件下,基于状态反馈控制器的多无人水面船集群控制.首先,为了准确地估计时变的海洋环境干扰,提出一种有限时间干扰观测器;然后,为了处理执行机构的物理约束,采用一种辅助动态系统;最后,为了实现多无人水面船集群控制,设计一种状态反馈控制器.采用李雅普诺夫方法证明了系统的稳定性,仿真结果验证了所设计的状态反馈控制器的有效性.     

Input–output finite-time stability of discrete-time systems under finite-time boundedness

This paper deals with the input–output finite-time stability of discrete time-varying linear systems in the presence of finite-time boundedness. The state boundedness and output stability of this system are concerned simultaneously to avoid the large unacceptable values during certain transients. For two different classes of norm-bounded input signals, the sufficient conditions for the system satisfying both the state finite-time boundedness (FTB) and input–output finite-time stability (IO-FTS) are developed. Based on a set of linear matrix inequalities (LMIs), the controller design method via state feedback for the discrete-time system satisfying both FTB and IO-FTS is presented for the two classes of external norm-bounded input. The conditions proposed can simultaneously guarantee the state and output of closed-loop system do not exceed the boundary during the specified finite-time interval. Two examples are employed to verify the effectiveness of the proposed method.     

Time‐varying input delay compensation for nonlinear systems with additive disturbance: An output feedback approach

This paper addresses the output feedback tracking control of a class of multiple‐input and multiple‐output nonlinear systems subject to time‐varying input delay and additive bounded disturbances. Based on the backstepping design approach, an output feedback robust controller is proposed by integrating an extended state observer and a novel robust controller, which uses a desired trajectory‐based feedforward term to achieve an improved model compensation and a robust delay compensation feedback term based on the finite integral of the past control values to compensate for the time‐varying input delay. The extended state observer can simultaneously estimate the unmeasurable system states and the additive disturbances only with the output measurement and delayed control input. The proposed controller theoretically guarantees prescribed transient performance and steady‐state tracking accuracy in spite of the presence of time‐varying input delay and additive bounded disturbances based on Lyapunov stability analysis by using a Lyapunov‐Krasovskii functional. A specific study on a 2‐link robot manipulator is performed; based on the system model and the proposed design procedure, a suitable controller is developed, and comparative simulation results are obtained to demonstrate the effectiveness of the developed control scheme.     

无线网络环境下工业过程运行反馈控制方法

针对一类工业过程运行控制中采用无线网络传输运行指标反馈值时存在的噪声和丢包问题,建立了输入为过程控制的输入输出、输出为运行指标的随机过程模型;提出了由不同采样速率的过程控制与过程控制设定值反馈控制组成的运行反馈控制方法;采用Lyapunov函数和不同采样频率的提升技术设计了过程PI控制器参数和过程控制设定值反馈控制器参数,保证了双闭环控制系统的随机稳定性;同时实现了运行指标实际值与目标值稳态误差的均值为零;通过浮选过程运行反馈控制仿真实验验证了本文所提方法的有效性.     

一种推广的组合非线性输出反馈控制

针对多变量饱和线性系统的时变参考输入跟踪问题,研究了一种组合非线性输出反馈控制器的设计方法.基于原始的组合非线性反馈理论,构造了全阶和降阶输出反馈控制器.控制器由线性输出反馈项和非线性反馈项组成,使得闭环系统在包含于吸引域的不变集内渐近稳定.除了能够跟踪时变参考输入外,系统还具有良好的动态性能.仿真结果说明了所开发控制器的有效性.     

An improved Backstepping technique using sliding mode control for transient stability enhancement and voltage regulation of SMIB power system

The problem of transient stability and voltage regulation for a single machine infinite bus (SMIB) system is addressed in this paper. An improved Backstepping design method for transient stability enhancement and voltage regulation of power systems is discussed beginning with the classical Backstepping to designing the nonlinear excitation control of synchronous generator. Then a more refined version of this technique will be suggested incorporating the sliding mode control to enhance voltage regulation and transient stability. The proposed method is based on a standard third-order model of a synchronous generator connected to the grid (SMIB system). It is basically implemented on the excitation side of the synchronous generator and compared to the classical Backstepping controller as well as the conventional controllers which are the automatic voltage regulator and the power system stabiliser. Simulation results prove the effectiveness of the proposed method which ameliorates to a great extent the transient stability compared to the other methods.     

适应连续外扰的时滞加速度反馈控制器

在采用加速度传感器的振动主动控制平台中,为了有效抑制外力可用微分方程描述的含输入时滞受迫振动响应,基于积分变换和状态导数极点配置法,提出了一种适应连续外扰的时滞加速度反馈控制器设计方法.以粘贴有压电陶瓷和加速度传感器的受正弦激励的智能梁为仿真控制对象,仿真结果表明,此控制器能在任意输入时滞下有效抑制智能梁的持续受迫振动响应.与不考虑时滞的同类控制器相比,该控制器有较好的稳定性及控制效果.     

An LMI approach to design extended predictor feedback controllers for dynamical systems with input delay

The stabilisation of dynamical systems with input delay by an extended predictor feedback controller is investigated. After considering a more general case of the predictor feedback controllers, the design procedure is transformed into the stabilisation problem of the system controlled by a dynamic output feedback controller. By proposing appropriate Lyapunov-Krasovskii functionals, the predictor feedback gains are then synthesised from the stability conditions which are obtained in form of linear matrix inequalities. Such design approach is more flexible and extendable in comparison to one used by the conventional predictor feedback control. As a simulation example, the designed extended predictor feedback controller is applied on an active suspension system and is used to stabilise an unstable system with input delays. The obtained results demonstrate the effectiveness of the design method.     

A Saturating Extension of an Output Feedback Controller for Internally Damped Euler‐Lagrange Systems

In this research, a novel extension of the passivity‐based output feedback trajectory tracking controller is developed for internally damped Euler‐Lagrange systems with input saturation. Compared with the previous output feedback controllers, this new design of a combined adaptive controller‐observer system will reduce the risk of actuator saturation effectively via generalized saturation functions. Semi‐global uniform ultimate boundedness stability of the tracking errors and state estimation errors is guaranteed by Lyapunov stability analysis. An application of the proposed saturated output feedback controller is the stabilization of a nonholonomic wheeled mobile robot with saturated actuators towards desired trajectories. Simulation results are provided to illustrate the efficiency of the proposed controller in dealing with the actuator saturation.     

Observer-based robust control giving consideration to transient behaviour for linear systems with

In this paper, we present an observer-based controller design method which achieves performance robustness together with robust stability for linear multivariable systems with structured uncertainties. The performance robustness means that the deterioration of control performance is suppressed when we compare the transient behaviour for the uncertain system with a desired one generated by using the nominal system directly and at the same time excessive control input is avoided. In this approach, we adopt a similar way to the model-following technique and assume that the control law consists of a state feedback law for the nominal system and a compensation input for the purpose of preventing the error between the transient behaviour for the uncertain system and the desired one. The compensation input is additional modification term given by feedback form of an estimated error signal and is determined so that an upper bound of a quadratic cost function for the error system between the real trajectory for the plant and the desired one is minimized. We show that a condition for the existence of the compensation input which minimizes an upper bound of the quadratic cost function for the error system is given in terms of linear matrix inequalities (LMIs). Finally, numerical examples are presented.     

The Lyapunov direct method for the stabilisation of the ball on the actuated beam

This article deals with the stabilisation of a ball on an actuated beam independently of whether or not the force acts on the non-actuated coordinate. The feedback control law is deduced via application of the traditional Lyapunov stability method. The balancing strategy consists of shaping a convenient energy function that allows us to derive the required asymptotic stabilising controller. To this end, we introduce an auxiliary control input variable in order to algebraically obtain the kinetic metric and the potential energy of the entire system. The formed positive energy function along with the proposed feedback controller assures that the overall system is a dissipative one.     

Robust PI controller design for nonlinear systems via fuzzymodeling approach

The design problem of proportional and proportional-plus-integral (PI) controllers for nonlinear systems is studied. First, the Takagi-Sugeno (T-S) fuzzy model with parameter uncertainties is used to approximate the nonlinear systems. Then a numerically tractable algorithm based on the technique of iterative linear matrix inequalities is developed to design a proportional (static output feedback) controller for the robust stabilization of the system in T-S fuzzy model. Next, we transform the problem of PI controller design to that of proportional controller design for an augmented system and thus bring the solution of the former problem into the configuration of the developed algorithm. Finally, the proposed method is applied to the design of robust stabilizing controllers for the excitation control of power systems. Simulation results show that the transient stability can be improved by using a fuzzy PI controller when large faults appear in the system, compared to the conventional PI controller designed by using linearization method around the steady state