No description available.

Orientador: Percival Bueno de Araujo / Banca: Dilson Amancio Alves / Banca: Laurence Duarte Colvara / Banca: Igor Kopcak / Banca: Carlos Roberto Mendonça da Rocha / Resumo: NESTE trabalho é proposto um modelo de injeção de potência para o controlador Generalized Unified Power Flow Controller (GUPFC) que permite representá-lo em programas de fluxo de potência e fluxo de potência ótimo. Também é proposto um modelo para a estrutura do sistema de controle do GUPFC que permite representar sua dinâmica em sistemas elétricos de potência. Todas as análises dinâmicas realizadas neste trabalho visam a estabilidade a pequenas perturbações, porém, o modelo de injeção de potência do GUPFC e o modelo de sua estrutura de controle permitem representálo também em um ambiente não linear. A partir das equações algébricas fornecidas pelo modelo de injeção de potência do GUPFC e das equações dinâmicas obtidas a partir da sua estrutura do sistema de controle, é possível analisar a influência que o controlador GUPFC causa no sistema, realizando-se inicialmente uma abordagem estática (em regime permanente), que foi realizada utilizando-se a ferramenta de fluxo de potência expandido. A ferramenta de fluxo de potência expandido trata as variáveis diferenciais como algébricas, para um dado ponto de equilíbrio, ficando o problema restrito a encontrar os zeros de um conjunto de funções não-lineares, cuja solução pode ser obtida através do método de Newton-Raphson, como em um fluxo de potência convencional. Com a solução desse fluxo de potência, pode-se incluir diretamente as correspondentes submatrizes do GUPFC no Modelo de Sensibilidade de Potência (MSP), já que este foi o modelo escolhido para representação de todos os componentes dinâmicos do sistema. Com todos os componentes modelados no MSP, foi realizada uma análise dinâmica do sistema, visando a estabilidade a pequenas perturbações. Para melhorar o desempenho dinâmico do sistema, foi essencial que controladores ESPs e POD fossem inclusos às malhas de controle dos Reguladores Automáticos ... / Abstract: THIS thesis proposes a power injection model for the GUPFC (Generalized Power Flow Controller) which is suited for the GUPFC representation in both power flows and optimal power flows analyses. It is also proposed a model for the control system GUPFC that represents its dynamics in electric power systems. This work main aim is the small signal stability analysis. However, the power injection model of the GUPFC and the structure control model could be used in nonlinear environment. The algebraic equations provided by the power injection model of the GUPFC and the dynamical equations obtained from the control model, are used to analyze the influence of the GUPFC on the system, initially executing a static approach (in steady state) using the expanded power flow tools. The expanded power flow considers the differential variables as algebraic, at a given equilibrium point, and the problem is to find the zeros of a nonlinear function set, whose solution can be obtained by a Newton Raphson method as in a conventional power flow. From the solution of the power flow, it is possible to include directly the corresponding sub matrices of the GUPFC in to the Power Sensitive Model (PSM), which is the chosen model to represent all the dynamic components of the system. Once, every component is modeled in the PSM, a small signal stability is performed. The ESP and POD controllers are included in to the control loop of the Automatic Voltage Regulators (AVR) and the GUPFC respectively, to improve the dynamical performance of the system. To provide additional damping to the unstable or little damped modes and increase the stability limits, a Particle Swarm Optimization (PSO) technique is used to provide the parameters of the supplementary damping controller. Two objective functions are proposed to lead the problem solution to good results and then compared to well known classical techniques / Doutor

本文研究了多变量系统的非线性输出调节问题，并处理了机电和机械控制系统中的两个典型控制问题。 / 输出调节问题是控制中的核心问题之一。它同时处理轨迹跟踪和干扰抑制问题。参考输入和干扰是通过一定的动态系统产生，称为外部系统。因此输出调节问题和其它轨迹跟踪问题的区别在于它允许跟踪一类参考信号，而不需要精确的知道参考信号的值。而且，输出调节问题可应用于真实世界的很多控制问题，包括能源系统，交通和系统生物学。 / 众所周知，处理输出调节问题的基本框架包含两个步骤。首先把被控对象的鲁棒输 出调节问题转化成由被控对象和叫做内模的动态补偿器组成的增广系统的鲁棒镇定问题，然后鲁棒镇定增广系统。问题的关键在于如何设计一个合适的内模。这个内模不仅可以产生所有的稳态信息，而且使得增广系统可镇定。 / 虽然在过去的二十几年里关于非线性输出调节问题的研究取得了重大进展，大部分的结果只处理了单输入单输出的非线性系统。多变量非线性系统非线性输出调节问题有关的结果甚少。两大难点阻碍了多变量非线性系统非线性输出调节问题的进一步发展。一方面，由于被控对象的复杂结构，很难构造出一个合适的内模。这个内模既可以产生必需的稳态信息，又可以保证增广系统的镇定问题可解。另一方面，由于内模的引入，增广系统变成一个更加复杂的多输入多输出的非线性系统，其中既包含了动态不确定性，也包含了时变的静态不确定性。这个增广系统具有一定特殊的结构，并且从未出现在现有的文献中。增广系统的镇定问题很有挑战性。此外，关于实际系统非线性输出调节问题的研究甚少。因为输出调节方法对于未知的对象参数具有一定的鲁棒性，而且允许外部系统含有未知参数，通过输出调节方法我们可能得出更好的结果。基于以上的动机，我们将考虑具有特定结构的多变量系统的全局鲁棒输出调节问题，并解决两个典型控制问题，包括永磁同步电机的速度跟踪控制和球形倒立摆的轨迹跟踪控制。本文的贡献总结如下。 / 1. 本文考虑了一类多变量非线性系统的全周鲁棒输出调节问题。通过把内模附加到被控对象， 增广系统具有」定特殊的结构。它的镇定问题尚未有人处理过。我们把增广系统的镇定问题分解为多个单输入系统的镇定问题。然后利用changingsupply function 技术，我们通过法代的方法求解多个单输入控制问题，从而解决了这一镇定问题。理论结果可以解决面装式永磁同步电机的速度跟踪和负载干扰抑制问题。与现有的结果比较，我们的设计允许所有的电机参数未知。 / 2. 本文考虑了未知外部系统作用下的面装式永磁同步电机的速度跟踪和负载干扰抑制问题。由于外部系统未知，传统的鲁棒控制方法不能处理这一问题。而且，外部系统中的未知参数使得增广系统的镇定问题更具挑战性。因此我们需要把鲁棒控制和自适应控制相结合处理这一问题。利用changing supply function 技术和动态坐标变换技术相结合，我们用迭代的方法求解了两个单输入控制问题，进而解决了这一问题。 / 3. 本文考虑了用内模设计的方法处理永磁同步电机的速度跟踪和负载干扰抑制问题。当dq 轴电感相等时，这一问题己经得到了广泛的研究。然而dq 轴电感不等时，由于转速方程中的复杂非线性，这一问题的研究甚少。利用输出调节方法，电机参数可以具有更好的鲁棒性。由于增广系统不具有任何己知的特殊结构，我们研究出一种具体的工具来处理镇定问题。具体的说，我们研究出一种适用于non-ISS (输入到状态稳定)系统的广义changing supply function 技术。通过把这个技术与一个特殊的非线性内模相结合，这一问题得到了很好的解决。 / 4. 本文给出了一种新的方法用于处理球形倒立摆的近似输出调节问题。这一方法基于神经网络近似调节器方程的解。求解调节器方程近似解的问题被转化成一个参数优化问题，进而有助于计算机实现的方便。而且，与现有结果中的基于三阶多项式的控制比较，对于参考输入信号的不同幅值的情况，这一方法的稳态跟踪误差保持了更加平稳的性能。 / 5. 本文给出了一种新的方法用于处理球形倒立摆的近似输出调节问题。这一方法是基于神经网络的增强型设计，并采用输出反馈控制。与我们之前工作中的神经网络设计比较，我们给出了一种新的方法用于近似前馈控制，而不是调节器方程的解。求解前馈控制近似解的问题被转化成一个参数优化问题。我们采用Hooke-J eeeves 方法和Powell 方法解决了参数优化问题。当所有的状态可用的时候，我们的设计对于被控对象参数的变化具有一定的鲁棒性。 / In this thesis, we investigate nonlinear output regulation problem of multivariable systems and their applications to two typical control problems in electromechanical and mechanical control systems. / The output regulation problem is one of the central problems in control. It deals with trajectory tracking and disturbance rejection problem simultaneously. Both the reference inputs and disturbances are generated by some dynamical system called exosystem. Thus it is in contrast with some other traj ectory tracking problems in that it allows tracking of a family of reference signals which does not have to be known exactly. Moreover, it can be applied to many control problems in real world including energy systems, transportation and system biology. / It is well known that the general framework for tackling the output regulation problem consists of two steps. The first step is to convert the robust output regulation problem for the given plant into a robust stabilization problem for the so-called augmented system composed of the given plant and a dynamic compensator called internal model, and the second step aims to robustly stabilize the augmented system. The key issue lies in how to design a suitable internal model which can generate all the steady-state information and render the augmented system to be stabilizable. / Although the research on the nonlinear output regulation has made significant progress for over two decades, most of the results only deals with single-input, single-output nonlinear systems. There are few results on nonlinear output regulation of multivariable nonlinear systems. Two challenges hinder the further development of nonlinear output regulation of multivariable nonlinear systems. On the one hand, due to the complicated structure of the system, it is difficult to construct a suitable internal model which can generate the necessary steady-state information while ensuring the solvability of stabilization problem of the augmented system. On the other hand, due to the introduction of the internal model, the augmented system becomes a more complicated multi-input, multioutput nonlinear system containing both dynamic uncertainty and time-varying static uncertainty. Such augmented system takes certain special structure which has never been encountered before. The stabilization problem of such augmented system is very challenging. Moreover, t he research on the nonlinear output regulation of practical systems is very rare. Because output regulation approach offers certain robust property to unknown plant parameters and also allows unknown parameters in exosystem, better results may be achieved by using output regulation approach. Therefore we are motivated to consider global robust output regulation problem of multivariable systems with certain structures and solve two typical control problems including speed tracking control of permanent magnet synchronous motor and trajectory tracking control of spherical invert d pendulum. The main contributions of the thesis are summarized as follows. / 1. The global robust output regulation problem for a class of multivariable nonlinear systems is considered. By attaching the internal model to the given plant, the augmented system takes certain special structure and the stabilization problem of such a system has never been handled. We decompose the stabilization problem of the augmented system into the stabilization problem of several single-input systems. Then we solve the problem by solving several single-input control problems via a recursive approach utilizing the changing supply function technique. The theoretical result is applied to the speed tracking control and load torque disturbance rejection problem of a surface-mounted PM synchronous motor. Compared with existing results, our design allows all the motor parameters to be uncertain. / 2. A speed tracking and load torque disturbance rejection problem of surface-mounted PM synchronous motor subject to an unknown exosystem is considered. Because the exosystem is unknown, traditional robust control approach cannot be used to tackle this problem. Moreover, the unknown parameters in the exosystem make the stabilization problem of augmented system even more challenging. Therefore we need to incorporate robust control with adaptive control to t ackle the problem. We solve the problem by solving two single-input control problems via a recursive approach utilizing the changing supply function and dynamic coordinate transformation techniques. / 3. A speed tracking and load torque disturbance rejection problem of PM synchronous motor by internal model design is considered. When dq axes inductances are equal, the problem has been extensively studied. However, when dq axes inductances are not equal, such problem has received little attention for the complicated nonlinearity in speed equation. By using output regulation approach, a better robust property with respect to motor parameters can be achieved. As the augmented system does not take any known special form, we develop a specific tool to deal with the stabilization problem. In particular, a generalized changing supply function technique applicable to non-ISS (input-to-state stable) systems is developed. This technique, in conjunction with a particular nonlinear internal model leads to an effective solution to the problem. / 4. An alternative approach to the approximate output regulation problem of spherical inverted pendulum is considered. This method is based on a neural network approximation of the solution of the regulator equations. The problem of seeking approximate solution of the regulator equations has been converted into a parameter optimization problem which has lent itself to a convenient implementation in computer. Moreover, compared with a third order polynomial based control in existing results, the steady-state tracking errors of the method maintains a more uniform performance over different amplitudes of the reference input signals. / 5. An alternative approach to the approximate output regulation problem of spherical inverted pendulum is considered. This method has been based on the neural network enhanced design with output feedb ack control. Different from the neural network design in our previous work, we present a novel method to approximate the feedforward control instead of the solution of regulator equations. The problem of seeking approximate solutions of feedforward control is converted into a parameter optimization problem. We solve the parameter optimization problem by both Hooke-Jeeves method and Powell method. When all the states are available, our design also offers certain robustness to plant parameter variations. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Ping, Zhaowu. / "October 2011." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 160-170). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / Abstract --- p.i / Acknowledgement --- p.VI / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Literature Overview --- p.1 / Chapter 1.2 --- Contribution of Thesis --- p.7 / Chapter 1.3 --- Organization of Thesis --- p.9 / Chapter 2 --- Background and Preliminaries --- p.10 / Chapter 2.1 --- Fundamentals of Nonlinear Systems --- p.10 / Chapter 2.1.1 --- Lyapunov Stability --- p.11 / Chapter 2.1.2 --- Input-to-state Stability --- p.13 / Chapter 2.2 --- Framework of Robust Output Regulation --- p.15 / Chapter 2.3 --- Stabilization of Nonlinear Systems --- p.19 / Chapter 2.3.1 --- Technical Lemmas for ISS Systems --- p.20 / Chapter 2.3.2 --- Technical Lemmas for Non-ISS Systems --- p.23 / Chapter 2.4 --- Feedforward Control of Nonlinear Output Regulation --- p.28 / Chapter 2.4.1 --- Polynomial Based Approximation Method --- p.31 / Chapter 2.4.2 --- Neural Network Based Approximation Method --- p.32 / Chapter 3 --- Global Robust Output Regulation for a Class of Multivariable Systems --- p.39 / Chapter 3.1 --- Introduction --- p.40 / Chapter 3.2 --- Preliminaries --- p.42 / Chapter 3.3 --- Main Results --- p.48 / Chapter 3.4 --- Application to Speed Control of Surface-Mounted PM Synchronous Motor --- p.56 / Chapter 3.5 --- Conclusion --- p.71 / Chapter 4 --- Speed Tracking Control of Surface-Mounted PM Synchronous Motor Subject to an Unknown Exosystem --- p.72 / Chapter 4.1 --- Problem Formulation and Preliminaries --- p.73 / Chapter 4.2 --- Solvability of The Motor Control Problem --- p.79 / Chapter 4.3 --- Evaluation of The Control Law --- p.87 / Chapter 4.4 --- Conclusion --- p.99 / Chapter 5 --- Speed Tracking Control of PM Synchronous Motor by Internal Model Design --- p.100 / Chapter 5.1 --- Problem Formulation and Preliminaries --- p.101 / Chapter 5.2 --- Solvability of the Motor Control Problem --- p.107 / Chapter 5.3 --- Evaluation of the Control Law --- p.110 / Chapter 5.4 --- Conclusion --- p.119 / Chapter 6 --- Approximate Output Regulation of Spherical Inverted Pendulum by Neural Network Control --- p.120 / Chapter 6.1 --- Introduction --- p.121 / Chapter 6.2 --- Neural Network Based Approximate Solution of the Regulator Equations --- p.124 / Chapter 6.3 --- Approximate Control Law --- p.131 / Chapter 6.4 --- Conclusion --- p.135 / Chapter 7 --- Neural Network Enhanced Output Regulation of Spherical Inverted Pendulum --- p.136 / Chapter 7.1 --- Neural Network Based Output Feedback Control Law --- p.137 / Chapter 7.1.1 --- Hooke-J eeves Method --- p.139 / Chapter 7.1.2 --- Powell Method --- p.143 / Chapter 7.2 --- Robustness Analysis --- p.149 / Chapter 7.2.1 --- Hooke-Jeeves Method --- p.149 / Chapter 7.2.2 --- Powell Method --- p.153 / Chapter 7.3 --- Conclusion --- p.156 / Chapter 8 --- Conclusions --- p.157 / Bibliography --- p.160 / Biography --- p.171

<p>This report treats two assignments that concerns the biofuel furnace at Billerud Skärblacka AB and how these assignments were solved. The assignments were: reducing the number of CO-spikes and tuning the overfire air control loop. To reduce the number of CO-spikes the possibility that skewness in mass distribution affects the number of CO-spikes were study. The skewnwss of mass distribution was controled and adjusted with two experiments. The conclusion that was made is that the skewness of mass distribution were not sufficient enough to affect the number of CO-spikes. Most likely because there are other factor that affects the number of CO-spikes more than the skewness of mass distribution.</p><p>The objective with tuning the overfire air control loop was to find a faster and better interplayed control loop. To solve the assignment the first thought was to make a model of the furnace. But this idea was too much work for a single master thesis. Therefore a Simulink-model and a control strategy were produced instead. During the work with tuning the overfire air control loop the changes were issued from the control strategy and the Simulink-model were used for the tuning of the air valves. The result from tuning the overfire air control loop were faster regulators and a better tracking of the reference value for the secondary and tertiary air valve along with a reduced levels of carbon monoxide.</p>

This thesis presents the development of dynamic control strategies for the brushless doubly-fed machine (BDFM). A simple open-loop scalar controller is first investigated and its response is found to be oscillatory. Using the speed feedback signal, an improved closed loop scalar control algorithm is designed. Steady state performance is controlled by the magnitude of the BDFM control winding current. Simulation and experimental results demonstrate that the closed loop algorithm has a slow response and is suitable for low performance drive applications. A model reference adaptive control algorithm is investigated in simulation, attempting to improve the BDFM dynamic response and assure its robustness against system parameter variations. Further investigations reveal that the field orientation principle for conventional induction machines can be adapted for the BDFM. This enables the design of a rotor flux oriented control algorithm, based on a newly established synchronous reference frame model. Simulation results illustrate the algorithm's fast dynamic response and robustness against parameter variations. The verification of various control algorithms is carried out on a laboratory system consisting of an experimental BDFM, a power converter and associated control hardware. An Intel 80196Kr microprocessor is used to implement inverter switching and current regulation for the BDFM control winding. The rotor flux oriented control algorithm is implemented using an Intel 80960KB floating point microprocessor, achieving a control bandwidth in the kHz-order. Evaluation of a BDFM synchronous angle shows its significance in control design, and it is incorporated into the later control algorithm development in order to eliminate electric torque estimation. This simplifies control algorithm design and is verified experimentally. Consequently, the control algorithm for the BDFM can approach the simplicity of equivalent induction machine control techniques. / Graduation date: 1996

<p>There are many aspects to consider when designing system identification experiments in control applications. Input design is one important issue. This thesis considers input design both for identification of linear time-invariant models and for stability validation.</p><p>Models obtained from system identification experiments are uncertain due to noise present in measurements. The input spectrum can be used to shape the model quality. A key tool in input design is to introduce a linear parametrization of the spectrum. With this parametrization a number of optimal input design problems can be formulated as convex optimization programs. An Achilles' heel in input design is that the solution depends on the system itself, and this problem can be handled by iterative procedures where the input design is based on a model of the system. Benefits of optimal input design are quantified for typical industrial applications. The result shows that the experiment time can be substantially shortened and that the input power can be reduced.</p><p>Another contribution of the thesis is a procedure where input design is connected to robust control. For a certain system structure with uncertain parameters, it is shown that the existence of a feedback controller that guarantees a given performance specification can be formulated as a convex optimization program. Furthermore, a method for input design for multivariable systems is proposed. The constraint on the model quality is transformed to a linear matrix inequality using a separation of graphs theorem. The result indicates that in order to obtain a model suitable for control design, it is important to increase the power of the input in the low-gain direction of the system relative to the power in the high-gain direction.</p><p>A critical issue when validating closed-loop stability is to obtain an accurate estimate of the maximum gain of the system. This problem boils down to finding the input signal that maximizes the gain. Procedures for gain estimation of nonlinear systems are proposed and compared. One approach uses a model of the system to design the optimal input. In other approaches, no model is required, and the system itself determines the optimal input sequence in repeated experiments.</p>

<p>Periodic oscillations underlie many intracellular functions, such as circadian time keeping, cell cycle control and locomotor pattern generation in nerve cells. These intracellular oscillations are generated in intricate biochemical reaction networks involving genes, proteins and other biochemical components. In most cases, robust oscillations are of pivotal importance for the organism,<i> i.e.</i>, the oscillations must be maintained in the presence of internal and external perturbations.</p><p>Model based analysis of robustness in intracellular oscillators has attracted considerable attention in recent years. The analysis has almost exclusively been based on either complete removal of network components,<i> e.g.</i>, single genes, or perturbation of model parameters. In this thesis, a control theoretic approach to analyze structural robustness of intracellular oscillators is proposed. The method is based on adding dynamic perturbations to the network interactions. Determination of the smallest perturbation translating the underlying steady-state into a Hopf bifurcation point is used to quantify the robustness. The method can be used to determine critical substructures within the overall network and to identify specific network fragilities. Also, an approach to nonlinear model reduction based on the robustness analysis is proposed.</p><p>The proposed robustness analysis method is applied to elucidate mechanisms underlying robust oscillations in circadian clocks. Circadian clocks, molecular oscillators generating 24 hour rhythms in many organisms, are known to display a striking robustness towards internal and external perturbations. The underlying networks involve a large number of genes that are transcribed into mRNA which produce proteins subsequently regulating the activity of other genes, together forming an intricate network with a large number of embedded feedback loops. An often recurring hypothesis is that the interlocked feedback loop structure of circadian clocks serves the purpose of robustness. From analysis of several recently published models of circadian clocks, it is found in this thesis that the robustness of circadian clocks primarily results from a high gain in a single gene regulatory feedback loop generating the oscillations. This gain can be elevated by additional feedback loops, involving either gene regulation or post-translational feedback, but a similar robustness can be achieved by simply increasing the amplification within the master feedback loop.</p>

Not available / text

Not available / text

published_or_final_version / Electrical and Electronic Engineering / Master / Master of Philosophy