Driven by economic, technical and environmental factors, the energy sector is currently undergoing a profound paradigm shift towards a smarter grid setup. Increased intake of Distributed and Renewable Generation (DG) units is one of the Smart Grid (SG) pillars that will lead to numerous advantages among which lower electricity losses, increased reliability and reduced greenhouse gas emissions are the most salient. The increase of DG units’ penetration will cause changes to the characteristics of distribution networks from being passive with unidirectional power flow towards Active Distribution Networks (ADNs) with multi-direction power flow. However, such changes in the current distribution systems structure and design will halt the seamless DG integration due to various technical issues that may arise. Voltage and reactive power control is one of the most significant issues that limit increasing DG penetration into distribution systems. On the other hand, the term microgrid has been created to be the building block of ADNs. A microgrid should be able to operate in two modes of operation, grid-connected or islanded. The successful implementation of the microgrid concept demands a proper definition of the regulations governing its integration in distribution systems. In order to define such regulations, an accurate evaluation of the benefits that microgrids will bring to customers and utilities is needed. Therefore, there is a need for careful consideration of microgrids in the assessment, operation, planning and design aspects of ADNs. Moreover, SG offers new digital technologies to be combined with the existing utility grids to substantially improve the overall efficiency and reliability of the network. Advanced network monitoring, two ways communication acts and intelligent control methods represent the main features of SG. Thus it is required to properly apply these features to facilitate a seamless integration of DG units in ADNs considering microgrids. Motivated by voltage and reactive power control issues in ADNs, the concept of microgrids, and SG technologies, three consequent stages are presented in this thesis. In the first stage, the issues of voltage and reactive power control in traditional distribution systems are addressed and assessed in order to shed the light on the potential conflicts that are expected with high DG penetration. A simple, yet efficient and generic three phase power flow algorithm is developed to facilitate the assessment. The results show that utility voltage and reactive power control devices can no longer use conventional control techniques and there is a necessity for the evolution of voltage and reactive power control from traditional to smart control schemes. Furthermore, a probabilistic approach for assessing the impacts of voltage and reactive power constraints on the probability of successful operation of islanded microgrids and its impacts on the anticipated improvement in the system and customer reliability indices is developed. The assessment approach takes into account: 1) the stochastic nature of DG units and loads variability, 2) the special philosophy of operation for islanded microgrids, 3) the different configurations of microgrids in ADNs, and 4) the microgrids dynamic stability. The results show that voltage and reactive power aspects cannot be excluded from the assessment of islanded microgrids successful operation. The assessment studies described in the first stage should be followed by new voltage and reactive power planning approaches that take into account the characteristics of ADNs and the successful operation of islanded microgrids. Feeders shunt capacitors are the main reactive power sources in distribution networks that are typically planned to be located or reallocated in order to provide voltage support and reduce the energy losses. Thus, in the second stage, the problem of capacitor planning in distribution network has been reformulated to consider microgrids in islanded mode. The genetic algorithm technique (GA) is utilized to solve the new formulation. The simulation results show that the new formulation for the problem of capacitor planning will facilitate a successful implementation of ADNs considering islanded microgrids. In the third stage, the SG technologies are applied to construct a two ways communication-based distributed control that has the capability to provide proper voltage and reactive power control in ADNs. The proposed control scheme is defined according to the concept of multiagent technology, where each voltage and reactive power control device or DG unit is considered as a control agent. An intelligent Belief-Desire-Intention (BDI) model is proposed for the interior structure of each control agent. The Foundation for Intelligent Physical Agents (FIPA) performatives are used as communication acts between the control agents. First, the distributed control scheme is applied for voltage regulation in distribution feeders at which load tap changer (LTC) or step voltage regulators are installed at the begging of the feeder. In this case, the proposed control aims to modify the local estimation of the line drop compensation circuit via communication. Second, the control scheme is modified to take into consideration the case of multiple feeders having a substation LTC and unbalanced load diversity. To verify the effectiveness and robustness of the proposed control structure, a multiagent simulation model is proposed. The simulation results show that distributed control structure has the capability to mitigate the interference between DG units and utility voltage and reactive power control devices.

[Truncated abstract] This thesis analyses the problem of Intelligent Control for large industrial plants and suggests a hierarchical, distributed, object-oriented architecture for Intelligent Control. The architecture is called MLIAC (Multi Level Intelligent Adaptive Control) Architecture. The MLIAC architecture is inspired by biological control systems (which are flexible, and are capable of adapting to unstructured environments with ease) and the success of the distributed architecture SCADA (Supervisory Control and Data Acquisition) Systems. The MLIAC Architecture structures the decision and control mechanism for the real-time properties namely safety, liveliness, and timeliness . . . In addition, three case studies have been reported. The case studies cover the control of a Flexible Manufacturing System and the Mine Products Quality Control. The results show that MLIAC Knowledge Representation model meets the requirements of the Roth-Hayes benchmark regarding Knowledge Representation. The decisions taken are logically tractable. The software architecture is effective and easily implemented. The actual performance has been found to depend upon a number of factors discussed in this thesis. For the specification and design of Potline MLIAC software, a CASE package ("Software Through Pictures") has been used. The Potline MLIAC software has been developed using C⁄C++, SQL, 4 GL and RDBMS based on a Client-Server model. For computer simulation the Potline MLIAC software has been integrated with the MATLAB⁄SIMULINK package.

Les réseaux de capteurs sans fils (WSN) ont connu un succès important ces dernières années, en particulier grâce à l’émergence de l’Internet des Objets (IoT), qui a permis des applications beaucoup plus intéressantes. Les réseaux de capteurs sont utilisés dans presque toutes les applications de maisons et villes intelligentes et des objets connectés personnels. Beaucoup de ces applications nécessitent que les nœuds de capteurs constituant le réseau soient autonomes et donc efficaces en énergie. Le thème de l'efficacité énergétique pour les WSN est riche et adressé par de nombreuses équipes de recherches. L'une des solutions les plus prometteuses est l'intégration de blocs adaptatifs dans le nœud, qui peuvent ajuster leurs performances et leurs dépenses énergétiques selon les besoins de l'application, son environnement ou l’énergie disponible. L’objectif est de permettre à un nœud de fonctionner à un point d'énergie optimal et d'atteindre l'efficacité énergétique la plus élevée possible. Le travail présenté dans cette thèse traite du contrôle de ces blocs adaptatifs. Un nœud de WSN doit être capable de se réveiller et de se remettre en veille rapidement ce qui impose l'utilisation d'un réseau de contrôle efficace. Les données de contrôle peuvent être analogiques ou numériques. Ceci entraîne le besoin d'un réseau de communication complémentaire au réseau qui sert à transmettre les données numériques. Dans ce travail, un premier réseau de communication asynchrone est proposé pour adresser ce besoin de transfert de données de configuration dans un nœud. Cette communication basée sur événement utilise la logique asynchrone QDI. Ce premier réseau est numérique et deux versions ont été conçues, une série et une hybride. La version série a été implémentée en silicium et testée. Les deux se sont avérées efficaces en énergie ; le réseau série n’utilise que 1pJ/bit, tandis que l'hybride consomme 0,07pJ/bit à 0.6V en technologie FDSOI de 28nm.Dans la deuxième partie de ce travail, une amélioration visant des circuits plus simples et mixtes a été réalisée, incluant la conception et l'analyse d'un réseau capable de transférer efficacement des données analogiques. / Wireless sensor network (WSN) have experienced an incredible success these past years, especially due to the Internet of Thing (IoT) paradigm, which opened the door to much more interesting applications. The wireless sensor network nodes (WSNN) are used in nearly all smart houses applications, as a network of wearables or as entertainment devices. This keen interest in WSN is not without consequences, as many of these applications require from the node to be autonomous and thus energy efficient. The topic of energy efficiency for the WSN is rich and many teams are proposing as many solutions as there are applications. One of the most promising solutions is the integration of adaptive blocks in the node, which can adapt their performances and thus their energy expenditure according to the application, environment or the energy budget. This would allow any type of WSNN to operate at an optimum energy point and achieve the highest energy efficiency possible. However, this solution has its own issues. The work presented in this thesis deals with the control of these adaptive blocks.The aim of this work is to efficiently transfer the control data and the sense&react data throughout the node to and from the corresponding adaptive blocks. The nature of WSNN itself imposes the use of a communication network capable of a fast and independent wake and sleep mode, while the nature of the data dictate the need for a complementary communication network, as the data can be either analog or digital, and as such, a typical network is not capable of handling it without the help of secondary conversion blocks.In this manuscript, a first asynchronous communication network is proposed to deal with the issue at hand, mainly the transfer of configuration data throughout a network, in an event-driven fashion, hence the use of the QDI asynchronous logic. This network is digital only and two versions were designed, a serial and a hybrid one, and the serial version was implemented in silicon. Both proved to be energy efficient, as the serial network only needs 1pJ/bit, while the hybrid one consumes 0,07pJ/bit at 0.6V in a 28nm FDSOI technology.In the second part of this work, an improvement targeting simpler and mixed-signals circuits was carried out, including the design and analysis of a network capable of efficiently transferring analog data.

AN ABSTRACT OF THE THESIS OF PRASHANTHI BANALA, for the Master of Science degree in ELECTRICAL AND COMPUTER ENGINEERING, presented on 31 October 2011, at Southern Illinois University Carbondale. TITLE: OUTPUT FEEDBACK H-inf CONTROL DESIGN FOR MULTI-AGENT SYSTEMS MAJOR PROFESSOR: Dr. Farzad Pourboghrat In this thesis, the design of distributed control for identical multi-agent systems is considered based on the optimization of H-inf cost function. Identical dynamically coupled but interacting systems (agents) are considered where control action of each agent is based on relative output measurement of their neighboring agents and a subset of their own output. The agents communicate with each other to achieve a common goal. A distributed dynamic output feedback control strategy that satisfies H-inf performance for multi-agent systems is developed and corresponding H-inf performance region is analyzed. An example illustrates the necessary and sufficient condition for dynamic output feedback controller synthesis to obtain desired H-inf performance.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A distributed power supply composed of multiple DC-DC converters connected in parallel offers several advantages in comparison to a centralized solution. Among these benefits are the following: redundancy, system modularity, increased reliability, improved thermal ow on the system and reduction in the physical size of the units. Its main purpose is to evenly share the output current between the converters. In practice, this specification is rarely achieved without the use of a specific control strategy for sharing, since each converter produces output dependent on the tolerances of the components and the line impedance that connects the unit to the load bus. This imbalance in the shared current can cause excessive stress on the units operating outside of their specifications, increasing their chances of failure. Also, it is desirable that any points of failure are minimized or eliminated by adopting a decentralized control strategy, minimizing connections between units. In this work, the generalized model of output current for a i -th converter from a source with n converters connected in parallel is obtained. To obtain this model, each converter present in the system is modeled as a controlled voltage source, connected to the load bus through an individual line resistance. As the main contribution, two strategies to control current sharing between converters are proposed, based on parallelism without communication between modules, specifically the droop control. To validate the design, the simulation results for a power supply containing three converters in parallel applied to a LED street lamp fixture are shown and analyzed. At the end of this document, the conclusions and suggestions for future work involving the subject are developed. / Uma fonte distribuída de potência composta por vários conversores CC-CC conectados em paralelo oferece diversas vantagens em comparação a uma solução centralizada. Entre esses benefícios, destacam-se os seguintes: redund^ancia, modularidade do sistema, aumento da confiabilidade, melhoria no uxo térmico do sistema e redução no tamanho físico das unidades. Seu principal objetivo é compartilhar uniformemente a corrente de saída entre os conversores. Na prática, esta especificação é raramente atingida sem o emprego de uma estratégia de controle específica para o compartilhamento, visto que cada conversor produz saída dependente das tolerâncias de seus componentes e da impedância de linha que o conecta ao barramento de carga. Este desequilíbrio nas correntes compartilhadas pode ocasionar estresse excessivo nas unidades operando fora de suas especificações, aumentando suas chances de falha. Ainda, é desejável que quaisquer pontos de falha sejam minimizados ou eliminados através da adoção de uma estratégia de controle descentralizada, minimizando conexões entre os conversores. Neste trabalho, o modelo generalizado de corrente para um i -ésimo conversor constituinte de uma fonte com n conversores conectados em paralelo é obtido. Para obtenção deste modelo, modelou-se cada conversor presente no sistema como uma fonte de tens~ao controlada, conectado ao barramento de carga através de uma resistência de linha individual. Como principal contribuição, são apresentadas duas estratégias de controle para compartilhamento de corrente entre conversores, baseados no paralelismo sem comunicação entre módulos, mais especificamente o controle por decaimento. Para validar o projeto, são mostrados e analisados os resultados de simulação para uma fonte de potência contendo três conversores em paralelo aplicados a uma lâmpada de LEDs para iluminação pública. No final deste documento, as conclusões e sugestões para futuros trabalhos envolvendo o tema são elaboradas.

Frente a abrangente presença da internet no ambiente acadêmico e residencial, a literatura relata, na última década, um número crescente de experiências de ensino a distância na área de automação e controle industrial, nas quais desde procedimentos teóricos até aulas práticas podem ser realizados através de acesso remoto. Neste contexto, este trabalho apresenta o estado da arte sobre as experiências acadêmicas no emprego de laboratórios on-line relacionados à teoria de controle e introduz uma nova proposta de arquitetura de acesso remoto, que será aplicada ao ensino de sistemas de controle distribuídos via rede de campo no protocolo FOUNDATION Fieldbus em ambiente simulado. / Due to the increasing presence of the internet in the academic and residential environment, the literature shows an increasing number of experiences of distance learning in the automation and industrial control area in the last decade, in which theoretical procedures as well as practical lessons can be carried out through remote access. In this context, this dissertation presents a brief survey on the academic experiences in the application of on-line laboratories and introduces a new proposal of remote access architecture that will be applied on a distance learning experience in the networked control systems area based on the FOUNDATION Fieldbus protocol using a simulated environment.

Sistemas de controle distribuídos cujas malhas são fechadas através de uma rede de comunicação são chamados de sistemas de controle distribuídos em redes de comunicação (NCS - Networked Control System). Este tipo de arquitetura permite a divisão do sistema de controle em módulos interconectados através da rede de comunicação, proporcionando a divisão do processamento, a redução de custo e de peso, além de facilitar o diagnóstico e manutenção do sistema e de aumentar a sua exibilidade e agilidade; e por isso seu emprego na indústria está se tornando comum (e.g., y-by-wire e drive-by-wire). Porém, a distribuição do processamento e a inserção de uma rede de comunicação aumenta a complexidade da análise e do projeto deste tipo de sistema. Um dos fatores que contribui para esse aumento da complexidade é a presença de atrasos aleatórios nos sinais de controle, causados pela dinâmica do sistema computacional (conjunto de hardware e software) que serve como plataforma para implementação do sistema de controle digital. Este trabalho faz um estudo sobre este tipo de sistema sob a perspectiva destes sinais com atrasos. Para isso, faz-se uso dos toolboxes para MATLAB: TrueTime e Jitterbug. Através destas ferramentas, mostra-se a existência de uma relação de compromisso entre o desempenho do controle e o desempenho do sistema computacional. Através deste estudo, é proposto uma solução de um sistema de controle do tipo NCS para um ROV (do inglês Remotely Operated Vehicle), modelado através de 6 equações diferenciais desacopladas não-lineares. Este tipo de veículo tem uma relevância econômica significativa para o Brasil, visto que é utilizado em operações de manutenção e instalação de plataformas de extração do petróleo que está depositado em profundidades que variam de mil a 2 mil metros. Para este NCS proposto, são utilizados controladores do tipo PI com estrutura feedback-feedfoward cujos parâmetros de projeto são obtidos em função dos atrasos inseridos pelo sistema computacional. / Distributed control systems wherein the control loops are closed through a communication network are called Networked Control Systems (NCSs). This type of architecture allows the control systems division into modules interconnected through the communication network, providing the processing division, reduction of cost and weight, and facilitates the systems diagnosis and maintenance, and increases their exibility and agility. Therefore its use in industry is becoming common (eg, y-by-wire and drive-by-wire). However, the processing distribution and the communication network insertion increase the system analysis and design complexity. One of the factors that contributes to this increased complexity is the presence of random time delays, caused by the dynamics of the computer system (set of hardware and software) used as a platform for digital control system implementation. This work deals with the networked control systems under these random time delays view. For this, it is used two MATLAB toolboxes: Jitterbug and TrueTime. With these tools, it is shown the existence of a relationship between the performance of control and performance of computer system. With this study, it proposed a solution of a NCS for a ROV (Vehicle Operated Remotely), modeled by 6 differential nonlinear decoupled equations. This type of vehicle has a significant economic relevance for Brazil, as it is used in maintenance and installation of platforms for oil extraction deposited at depths ranging from thousand to 2 thousand meters. For this proposed NCS are adopted PI controllers with feedfoward-feedback structure whose parameters design are given in terms of delay inserted by the computer system.

Microgrid is an emerging technology in the eld of electrical engineering which employs the concept of Distributed Energy Resources (DERs) in order to generate electricity in a small sized power system. The main objectives of this dissertation are to: 1- design a new control for lower level control of DERs in microgrids, 2- implement distributed upper level control for DERs in microgrids and 3- apply analytical approaches in order to analyze DERs in microgrids. The control in each DER can be divided into two main categories: lower and upper level. Lower level control is the main objective of control in each DER. For example, the lower level control in Photovoltaic (PV) is in charge of transferring the maximum power from sun into the main grid. Unlike the lower level control, the upper level control is an additional control loop on top of the lower level controls. For example, Voltage/Frequency (VF) controllers are installed on top of Active/Reactive (PQ) power controller in energy storage devices as upper level control. In this dissertation, for the lower level control improvements, two widely used DERs are selected (PV, and oshore wind farm) and new control algorithms are developed in order to improve the performance of lower level controllers in these DERs. For the PV lower level improvement, a new control methodology is proposed in order to minimize the maximum power tracking error in PV lower level controller. Second contribution in lower level control is for the oshore wind farm applications based on Multi-Terminal High Voltage Direct Current (MTDC) transmission; a new control is designed in order to minimize the losses in transmission lines through lower level control of High Voltage Direct Current (HVDC) converters. For the upper level control, this dissertation considers the energy storage as another mostly used type of DER in microgrids. The lower level control for energy storage is in charge of controlling the PQ of the energy storage. The main contribution in the upper level control is to implement the distributed control algorithm based on consensus theory for battery energy storages in order to maximize the efficiency, energy management as well as synchronizing the performance of parallel energy storage devices in microgrids. In this case, the consensus based distributed control algorithm with limited information exchange between neighboring energy storage units is proposed and implemented to validate the claim. The third contribution of this research is to apply advanced analysis techniques to evaluate the performance of the DERs in microgrids. Two approaches are introduced for microgrid modeling in this research. Firstly, an impedance modeling technique is used to model the oshore wind farm connected to the main AC grid through HVDC transmission line. Multiple Input Multiple Output (MIMO) Nyquist analysis and singular value analysis are used to assess the interactions between HVDC converter and grid. Secondly, an unbalanced microgrid is considered and Dynamic Phasor (DP) analysis is applied in order to nd the stability limitations under different scenarios. This dissertation has led to seven journal papers (five published, one journal in revision process and one journal submitted recently) and four conference papers.

The rapidly expanding power system grid infrastructure and the need to reduce the occurrence of major blackouts and prevention or hardening of systems against cyber-attacks, have led to increased interest in the improved resilience of the electrical grid. Distributed and decentralized control have been widely applied to computer science research. However, for power system applications, the real-time application of decentralized and distributed control algorithms introduce several challenges. In this dissertation, new algorithms and methods for decentralized control, protection and energy management of Wide Area Monitoring, Protection and Control (WAMPAC) and the Active Distribution Network (ADN) are developed to improve the resiliency of the power system. To evaluate the findings of this dissertation, a laboratory-scale integrated Wide WAMPAC and ADN control platform was designed and implemented. The developed platform consists of phasor measurement units (PMU), intelligent electronic devices (IED) and programmable logic controllers (PLC). On top of the designed hardware control platform, a multi-agent cyber-physical interoperability viii framework was developed for real-time verification of the developed decentralized and distributed algorithms using local wireless and Internet-based cloud communication. A novel real-time multiagent system interoperability testbed was developed to enable utility independent private microgrids standardized interoperability framework and define behavioral models for expandability and plug-and-play operation. The state-of-theart power system multiagent framework is improved by providing specific attributes and a deliberative behavior modeling capability. The proposed multi-agent framework is validated in a laboratory based testbed involving developed intelligent electronic device prototypes and actual microgrid setups. Experimental results are demonstrated for both decentralized and distributed control approaches. A new adaptive real-time protection and remedial action scheme (RAS) method using agent-based distributed communication was developed for autonomous hybrid AC/DC microgrids to increase resiliency and continuous operability after fault conditions. Unlike the conventional consecutive time delay-based overcurrent protection schemes, the developed technique defines a selectivity mechanism considering the RAS of the microgrid after fault instant based on feeder characteristics and the location of the IEDs. The experimental results showed a significant improvement in terms of resiliency of microgrids through protection using agent-based distributed communication.

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