Distributed generation (DG) and microgrid will play an essential role in the modern power system. They could improve energy efficiency, reduce losses, minimize environmental impacts and enhance power system reliability and stability. Most of the renewable energy applications would require two or three power conversions before power reaches the loads. If the power from DG could be utilized in DC form, the loss could be minimized and system efficiency is improved. Fuel cell, energy storage battery, photovoltaic and power electronic building block (PEBB) are used in this research to set up a DC microgrid. Simulation and hardware implementation are conducted. Techniques studied in this thesis include different power sources interconnection and DC bus voltage and microgrid power controls. Based on the studied results, DC mircogrid integration and system operation schemes are recommended.

A critical requirement of any remote microgrid is its capability to control the balance between electric generation and load within the confines of the microgrid itself. The integration of significant amounts of “as available” renewable generation to any electric grid (macro or micro) makes it more difficult to maintain this balance and can result in large frequency deviations on a microgrid. Ancillary services provide the resources required to maintain the instantaneous and ongoing balance between generation and load. Battery energy storage systems (BESS) can provide regulating reserves, a type of ancillary service, by modulating active power for frequency control, referred to as load frequency control (LFC), to reduce frequency deviations caused by sudden changes in renewable generation. Historically, the most common methodology for reducing frequency disturbances exacerbated by wind plants with BESS systems is ramp rate control and more recently lead compensation. This thesis proposed a modified lead compensator for use in microgrid applications. A PSS®E microgrid model, based upon existing validated models, was developed to test the effectiveness of the LFC controllers used to dispatch the BESS as a regulating resource to allow increased wind energy penetration levels on remote microgrids. A model of the remote microgrid of the island of Maui, Hawaii was chosen as the basis for the designs. Daily wind power data from 2012 was classified and indexed on an hourly basis by severity of variation. The worst hour for power variation from the wind plants was identified from this indexing and used as the basis for simulating the LFC controllers. The results compared the effectiveness of droop, ramp rate, lead compensation, and modified lead compensation controllers in reducing the variability in the grid frequency caused by changes in wind power generation. An RMS of variation with respect to an average over different time windows was used as the comparison metric. The combined modified lead compensator with ramp rate control showed the best performance of the overall system behavior. / text

Οι Ανανεώσιμες Πηγές Ενέργειας έχουν διεισδύσει στη ζωή μας, αποτέλεσμα της κλιματικής αλλαγής αλλά και των αυξανόμενων απαιτήσεων του ανθρώπου για ηλεκτρική ενέργεια. Όσο η τεχνολογία αναπτύσσεται, η απαίτηση για φθηνότερο κόστος ενέργειας αλλά και φιλικής με το περιβάλλον έκανε επιτακτική τη δημιουργία της κατανεμημένης παραγωγής. Η ανάπτυξη των μικροδικτύων βοήθησε να φτάσει το ηλεκτρικό ρεύμα ακόμα και στην πιο απομακρυσμένη περιοχή, όπου το κεντρικό δίκτυο δε γινόταν να φτάσει λόγω των οικονομικών αλλά και τεχνικών μειονεκτημάτων. Μέσω των αναπτυγμένων μορφών αυτομάτου ελέγχου, δόθηκε η δυνατότητα ελέγχου των συστημάτων υβριδικών μικροδικτύων, δικτύων τα οποία αποτελούνται απο ΑΠΕ και μπορούν να δρουν αυτόνομα σε μια περιοχή, χωρίς την ανάγκη του κεντρικού δικτύου. Έτσι μπορούμε να ελέγξουμε την ενεργό και άεργο ισχύ που παράγει ή καταναλώνει ένα μικροδίκτυο με τη βοήθεια του droop ελέγχου, ο οποίος μας δίνει τη δυνατότητα να ελέγχουμε την ενέργεια μέσω της τάσης και της συχνότητας. Στο κεφάλαιο 1 παρουσιάζονται τα χαρακτηριστικά του υβριδικού μικροδικτύου, περιγράφοντας τις Ανανεώσιμες Πηγές Ενέργειας. Περιγράφεται επίσης η μέθοδος ελέγχου της ενέργειας μέσω συχνότητας και τάσης, droop. Στο κεφάλαιο 2 αναλύεται το μοντέλο μιας 3Φ πηγής τάσης προερχόμενης από αντιστροφέα του οποίου η έξοδος “βλέπει” ένα LC φίλτρο που χρησιμοποιεί μετασχηματισμό Park. Έτσι επιτρέπεται ο σχεδιασμός του ελεγκτή τάσης με σκοπό την εξομάλυνση της τάσης εξόδου σε συνθήκες γραμμικού φορτίου. Για να λάβουμε μηδενικό σφάλμα μόνιμης κατάστασης χρησιμοποιούμε ελεγκτές PID και τους εφαρμόζουμε στο block PWM , οι οποίοι βοηθούν στην επιτάχυνση της μεταβατικής απόκρισης του αντιστροφέα. Ο 7 αντιστροφέας συνδέεται με 3Φ ωμικό φορτίο του οποίου οι τιμές αλλάζουν για να εξετάσουμε τις διαταραχές οι οποίες δημιουργούνται. Η προσομοιίωση γίνεται στο περιβάλλον Matlab/Simulink και παρουσιάζονται οι γραφικές αποκρίσεις συνοδεία σχολίων. Στο κεφάλαιο 3 ο αντιστροφέας αντί να συνδεθεί με το 3Φ ωμικό φορτίο, συνδέεται με το δίκτυο και εξετάζουμε τη συμπεριφορά του συστήματος μας. Προσομοιώνεται στο περιβάλλον Matlab/Simulink και παρουσιάζονται οι γραφικές αποκρίσεις συνοδεία σχολίων. / Renewable Energy Sources (RES) have slowly filter in our lives as a result of climate change and growing human demands for electricity. As technology develops , the demand for less expensive energy, but also environmentally friendly , made imperative the creation of distributed generation. The development of microgrids helped to have electricity even in the most remote areas , where the central network could not reach due to economic and technical disadvantages. Via developed forms of automatic control ,we were granted control of hybrid microgrid systems. These networks are consisted of RES and may act autonomously in an area without the need of the central network. So we were able to control the active and reactive power that a microgrid produces or consumes, using the droop control, that enables us to control energy through frequency and voltage. Chapter 1 presents the characteristics of the hybrid microgrid , describing the Renewable Energy Sources . What is also described is the power control method through frequency and voltage (droop control). Chapter 2 analyzes the model of a three phase voltage source derived from the inverter which is connected to an LC filter that uses Park's transformation. This allows the design of the voltage controller in order to normalize the output voltage in linear load conditions. To obtain zero steady-state error we use PID controllers and we also apply PWM. The PID controllers accelerate the inverter transient response. The inverter is connected to a three phase resistive load whose values vary in order to observe the disturbances that are created. The simulation takes part in the Matlab/Simulnik environment and graphic comments are presented and followed by responses.

In recent years, the share of renewable energy sources (RESs) has been increasing in the electricity generation mix with a mandate to reduce greenhouse gas emissions that are released from burning fossil fuels. Indeed, a large share of electricity from renewable resources is required to de-carbonize the electricity sector. With the evolution of smart grids and microgrids, effective and efficient penetration of renewable generation such as wind and solar can possibly be attained. However, the intermittent nature of wind and solar generation makes microgrid operation and planning a complex problem and there is a need for a flexible grid to cope with the variability and uncertainty in their generation profiles. This research focuses on the coordination of distributed energy resources, such as energy storage systems (ESSs) and demand response (DR) to present an efficient solution towards improving the flexibility of microgrids, and supporting high levels of renewables generation. The overall goal of this research is to examine the influence of coordinated operation of ESS and DR on microgrid operations in the presence of high penetration levels of renewable generation. Deterministic and stochastic short-term operational planning models are developed to analyze the effects of coordinating ESS and DR, vis-à-vis their independent operation, on microgrids with high renewable generation. Special focus is on operation costs, scheduling and dispatching of controllable distributed generators, and levels of renewable generation. A set of valid probabilistic scenarios is considered for the uncertainties of load, and intermittency in wind and solar generation sources. The numerical results considering a benchmark microgrid indicate that coordinated operation of ESS and DR is beneficial in terms of operation costs, vis-à-vis their independent presence in the microgrid, when there is sufficient renewable generation. The coordinated operation reduces the risk in scheduling and increases the flexibility of the microgrid in supporting high levels of renewable generation.

Driven by technical, economic and environmental benefits for different stakeholders in the power industry, the electric distribution system is currently undergoing a major paradigm shift towards having an increasing portion of its growing demand supplied via distributed generation (DG) units. As the number of DG units increase; microgrids can be defined within the electric distribution system as electric regions with enough generation to meet all or most of its local demand. A microgrid should be able to operate in two modes, grid-connected or islanded. The IEEE standard 1547.4 enumerates a list of potential benefits for the islanded microgrid operation. Such benefits include: 1) improving customers’ reliability, 2) relieving electric power system overload problems, 3) resolving power quality issues, and 4) allowing for maintenance of the different power system components without interrupting customers. These benefits motivate the operation of microgrid systems in the islanded mode. However the microgrid isolation from the main grid creates special technical challenges that have to be comprehensively investigated in order to facilitate a successful implementation of the islanded microgrid concept. Motivated by these facts, the target of this thesis is to introduce new analysis and operational control algorithms to tackle some of the challenges associated with the practical implementation of the islanded microgrid concept. In order to accomplish this target, this study is divided into four perspectives: 1) developing an accurate steady-state analysis algorithm for islanded microgrid systems, 2) maximizing the possible utilization of islanded microgrid limited generation resources, 3) allowing for the decentralized operation of islanded microgrid systems and 4) enabling the islanded microgrid operation in distribution systems with high penetration of plug-in electric vehicles (PEVs). First for the steady-state analysis of islanded microgrid systems, a novel and generalized algorithm is proposed to provide accurate power flow analysis of islanded microgrid systems. Conventional power flow tools found in the literature are generally not suitable for the islanded microgrid operating mode. The reason is that none of these tools reflect the islanded microgrid special philosophy of operation in the absence of the utility bus. The proposed algorithm adopts the real characteristics of the islanded microgrid operation; i.e., 1) Some of the DG units are controlled using droop control methods and their generated active and reactive power are dependent on the power flow variables and cannot be pre-specified; 2) The steady-state system frequency is not constant and is considered as one of the power flow variables. The proposed algorithm is generic, where the features of distribution systems i.e. three-phase feeder models, unbalanced loads and load models have been taken in consideration. The effectiveness of the proposed algorithm, in providing accurate steady-state analysis of islanded microgrid systems, is demonstrated through several case studies. Secondly, this thesis proposes the consideration of a system maximum loadability criterion in the optimal power flow (OPF) problem of islanded microgrid systems. Such consideration allows for an increased utilization of the islanded microgrid limited generation resources when in isolation from the utility grid. Three OPF problem formulations for islanded microgrids are proposed; 1) The OPF problem for maximum loadability assessment, 2) The OPF for maximizing the system loadability, and 3) The bi-objective OPF problem for loadability maximization and generation cost minimization. An algorithm to achieve a best compromise solution between system maximum loadability and minimum generation costs is also proposed. A detailed islanded microgrid model is adopted to reflect the islanded microgrid special features and real operational characteristics in the proposed OPF problem formulations. The importance and consequences of considering the system maximum loadability in the operational planning of islanded microgrid systems are demonstrated through comparative numerical studies. Next, a new probabilistic algorithm for enabling the decentralized operation of islanded microgrids, including renewable resources, in the absence of a microgrid central controller (MGCC) is proposed. The proposed algorithm adopts a constraint hierarchy approach to enhance the operation of islanded microgrids by satisfying the system’s operational constraints and expanding its loading margin. The new algorithm takes into consideration the variety of possible islanded microgrid configurations that can be initiated in a distribution network (multi-microgrids), the uncertainty and variability associated with the output power of renewable DG units as well as the variability of the load, and the special operational philosophy associated with islanded microgrid systems. Simulation studies show that the proposed algorithm can facilitate the successful implementation of the islanded microgrid concept by reducing customer interruptions and enhancing the islanded microgrid loadability margins. Finally, this research proposes a new multi-stage control scheme to enable the islanded microgrid operation in the presence of high PEVs penetration. The proposed control scheme optimally coordinates the DG units operation, the shedding of islanded microgrid power demand (during inadequate generation periods) and the PEVs charging/discharging decisions. To this end, a three-stage control scheme is formulated in order to: 1) minimize the load shedding, 2) satisfy the PEVs customers’ requirements and 3) minimize the microgrid cost of operation. The proposed control scheme takes into consideration; the variability associated with the output power of renewable DG units, the random behaviour of PEV charging and the special features of islanded microgrid systems. The simulation studies show that the proposed control scheme can enhance the operation of islanded microgrid systems in the presence of high PEVs penetration and facilitate a successful implementation of the islanded microgrid concept, under the smart grid paradigm.

Recently, the concept of Microgrids (MG) has been introduced in the distribution network. Microgrids are defined as small power systems that consist of various distributed micro generators that are capable of supplying a significant portion of the local demand. Microgrids can operate in grid-connected mode, in which they are connected to the upstream grid, or in isolated mode, where they are disconnected from the upstream grid and the local generators are the only source of power supply. In order to maximize the benefits of the resources available in a microgrid, an optimal scheduling of the power generation is required. Renewable resources have an intermittent nature that causes uncertainties in the system. These added uncertainties must be taken into consideration when solving the generation scheduling problem in order to obtain reliable solutions. This research studies the scheduling of power generation in a microgrid that has a group of dispatchable and non-dispatchable generators. The operation of a microgrid during grid-connected mode and isolated mode is analyzed under variable demand profiles. Two mixed integer linear programming (MILP) models for the day-ahead unit commitment problem in a microgrid are proposed. Each model corresponds to one mode of operation. Uncertainty handling techniques are integrated in both models. The models are solved using the General Algebraic Modeling System (GAMS). A number of study cases are examined to study the operation of the microgrid and to evaluate the effects of uncertainties and spinning reserve requirement on the microgrid’s expenses.

L’augmentation de la consommation pour soutenir la croissance, le souci de réduction des gaz à effet de serre et les avancées technologiques ont favorisé le développement des sources d’énergie renouvelables depuis les années 90. L’implantation de ces générateurs décentralisés a progressivement modifié l’architecture du réseau en passant d’un modèle vertical à une situation davantage clusterisée. Ce réseau maillé voit ainsi apparaitre de nouveaux acteurs, à la fois producteurs et consommateurs (en anglais, les « prosumers»). Pour ce type de structures, la stratégie classique actuelle consiste à acheter l'ensemble de l'énergie consommée alors que la totalité de la production est vendue séparément à des tarifs intéressants. Avec les progrès réalisés sur les différentes technologies de stockage, de nouveaux degrés de liberté apparaissent et des opérations plus intelligentes deviennent possibles. L’objet de l’étude est un microréseau comprenant un générateur photovoltaïque et un consommateur tertiaire associés à un moyen de stockage. Deux technologies sont envisagées avec des volants d’inertie dans un premier temps et une batterie électrochimique (Li-ion) par la suite. Les domaines d’étude relatifs à ce type de système sont la gestion énergétique par planification, la commande temps réel et le dimensionnement. Les travaux de cette thèse se concentrent d’abord sur la problématique de gestion par optimisation des flux d’énergie. Différents algorithmes sont ainsi utilisés et comparés pour planifier le fonctionnement du microréseau. L’objectif est de diminuer la facture énergétique en tenant compte des données de consommation et production mais également des politiques tarifaires en vigueur et d’éventuelles contraintes de fonctionnement imposées par le fournisseur d’énergie. Dans un second temps la problématique de dimensionnement est abordée avec une démarche de conception optimale intégrant la boucle de gestion dès la phase de design. Nous montrons plus particulièrement comment l’adéquation entre les méthodes d’optimisation utilisées et le modèle du microréseau employé peut permettre la réduction significative des temps de calcul. Une configuration optimale du microréseau, valable sur des horizons temporels longs intégrant les alternances saisonnières, peut finalement se dégager. Les travaux se concluent sur une phase d’analyse avec des dimensionnements établis pour différents contextes tarifaires. Le but est de dégager des domaines permettant de valoriser et justifier l’installation d’un moyen de stockage qui s’avère indispensable pour soutenir le développement des sources d’énergies renouvelables et assurer la transition énergétique. / To face the increasing demand of electrical power in compliance with the liberalization of the electricity market and the need of reducing CO2 emissions, many distributed energy resources have emerged and especially the generation systems that utilize renewable energy sources. In the nearfuture, the grid could be described as an aggregation of several microgrids both consumer and producer. For those "prosumers", a classical strategy consists in selling all the highly subsidized production at important prices while all consumed energy is purchased. Smarter operations now become possible with developments of energy storage technologies and evolving prices policies. The microgrid considered in the thesis is composed of an industrial load and a photovoltaic generator associated to an energy storage. Two technologies are considered with high speed flywheels on one hand and a Li-ion electrochemical battery on the other. The common study referring to such systems allude to the optimal scheduling, the real-time management and the sizing methodology. Firstly in the thesis, the optimal power flow dispatching is performed using various algorithms. Those operations aim at reducing the electrical bill taking account of consumption and production forecasts as well as the different fares and possible constraints imposed by the power supplier. Then the design strategy is investigated. The approach consists in simultaneously integrating the energy management and the sizing of the system. We particularly underline the complexity of the resulting optimization problem and how it can be solved using suitable optimization methods in compliance with relevant models of the microgrid. We specifically show the reduction of the computational time allowing the microgrid simulation over long time durations in the optimization process in order to take seasonal variations into account. In the last part a cost analysis is performed, and different design are computed depending on the prices policies. The goal is to determine a financial context that would encourage the deployment of storage systems that are necessary to favor the development of intermittent renewable energy sources.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-02-17T19:02:33Z No. of bitstreams: 1 JoaoTeixeiraDeCarvalhoNeto_TESE.pdf: 8174076 bytes, checksum: abcf3b6d3686c5b762d15c468555b83d (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-02-17T22:15:43Z (GMT) No. of bitstreams: 1 JoaoTeixeiraDeCarvalhoNeto_TESE.pdf: 8174076 bytes, checksum: abcf3b6d3686c5b762d15c468555b83d (MD5) / Made available in DSpace on 2017-02-17T22:15:43Z (GMT). No. of bitstreams: 1 JoaoTeixeiraDeCarvalhoNeto_TESE.pdf: 8174076 bytes, checksum: abcf3b6d3686c5b762d15c468555b83d (MD5) Previous issue date: 2016-07-22 / A integra??o de unidades com fontes de energia prim?ria, com armazenamento de energia e cargas, ? esperada para desempenhar um papel promissor no futuro para o fornecimento de energia el?trica. A interliga??o em rede destas unidades fornecendo m?dia e baixa tens?o forma um sistema denominado de microgrid. As fontes de energia distribu?da s?o as unidades b?sicas para armazenamento e distribui??o de energia em microgrids. Estas fontes podem ser de um tipo h?brido que inclui uma fonte de energia prim?ria e armazenamento simultaneamente. Uma unidade de tipo h?brido ? proposta neste trabalho e consiste de um conversor Buck-Boost CC-CC que rastreia a pot?ncia m?xima fornecida por um painel fotovoltaico, um conversor Boost CC-CC que regula a tens?o do barramento CC do microgrid e um conversor Buck-Boost bidirecional CC-CC que controla o fluxo de energia na unidade, carregando ou descarregando um banco de baterias. O controle desses conversores deve considerar a prote??o da bateria contra picos de tens?o e transit?rios, assim como a prote??o das cargas conectadas ao barramento principal do microgrid, quando a bateria fornece a energia armazenada. As t?cnicas de controle convencionais utilizadas nos conversores destas unidades utilizam a modula??o por largura de pulso que tem a desvantagem de produzir transit?rios indesej?veis devido ? resposta lenta ?s varia??es na fonte de entrada do sistema ou nas cargas conectadas ao barramento principal do microgrid. Estes transit?rios podem vir a danificar outras cargas e baterias que estejam conectadas ao barramento principal do microgrid. A t?cnica de controle de um ciclo ? aplicada aos conversores chaveadores para permitir uma resposta r?pida a transit?rios, sem overshoots e erro nulo em regime permanente. O objetivo deste trabalho ? a utiliza??o desta t?cnica no controlador desses conversores, a fim de rastrear rapidamente o ponto de pot?ncia m?xima do painel fotovoltaico, carregar as baterias quando elas est?o descarregadas, e fornecer a energia das baterias para as cargas quando necess?rio, garantindo a prote??o das baterias e das cargas ligadas ao barramento principal do microgrid. / The integration of units with primary energy sources, energy storage and loads, is expected to play a promising role in the future for the electricity supply. The interconnection of such units providing medium and low voltage makes a microgrid system. The distributed energy sources are the basic units for storage and distribution in microgrids. These sources can be of a hybrid type, which includes a primary energy source and storage simultaneously. A hybrid type proposed in this paper consists of a DC-DC Buck-Boost converter that tracks the maximum power supplied by a photovoltaic panel, a DC-DC Boost converter that regulates the microgrid DC bus voltage and a DC-DC bidirectional Buck-Boost converter that controls the energy flow in the system, charging or discharging a battery bank. The control of these converters should consider the protection of the battery against voltage transients and spikes, as well as the protection of loads connected to the microgrid main bus when the battery supplies the stored energy. Conventional control techniques used on the converters of these units use the pulse width modulation, which has the disadvantage of produce undesirable transient due to the slow response to changes in the system input source, or the loads resistance connected to microgrid the main bus. These transients can damage other loads and batteries connected to the microgrid main bus. Thus, one-cycle control technique is applied to the switching converters to allow fast response to transient without overshoots and zero steady-state error. The objective of this work is to use this technique in controlling these converters in order to quickly track the maximum power point of the photovoltaic panel, charge the batteries when they are discharged, and provide power from the batteries to the loads when needed, ensuring the protection of the batteries and the loads connected to the microgrid main bus.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-09-05T21:38:16Z No. of bitstreams: 1 LeonardoDuarteDeAlbuquerque_DISSERT.pdf: 36580121 bytes, checksum: bba04c74111ace6c5ffb8a39be098f1e (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-09-18T21:19:25Z (GMT) No. of bitstreams: 1 LeonardoDuarteDeAlbuquerque_DISSERT.pdf: 36580121 bytes, checksum: bba04c74111ace6c5ffb8a39be098f1e (MD5) / Made available in DSpace on 2017-09-18T21:19:25Z (GMT). No. of bitstreams: 1 LeonardoDuarteDeAlbuquerque_DISSERT.pdf: 36580121 bytes, checksum: bba04c74111ace6c5ffb8a39be098f1e (MD5) Previous issue date: 2017-06-23 / A escassez dos recursos naturais e a busca por fontes de energia alternativa promovem uma r?pida mudan?a na matriz energ?tica mundial. Dentre as fontes de energia renov?veis a energia solar ? a mais promissora, visto que ela apresenta a maior taxa de crescimento na atualidade. Pesquisadores de todo o mundo t?m buscado formas de viabiliza??o do seu progresso, desenvolvendo tecnologias com maior efici?ncia e menor custo. Como forma de contribuir para o avan?o desta tecnologia, neste trabalho prop?e-se o desenvolvimento de uma microgrid em corrente cont?nua interligando os pain?is fotovoltaicos atrav?s de um dispositivo com estrat?gia de rastreamento elaborada a partir do m?todo perturba??o e observa??o, que atuar? junto a um circuito eletr?nico de pot?ncia e um sistema de comunica??o sem fio para acompanhamento da gera??o individual. Simula??es foram desenvolvidas para a escolha da topologia de liga??o e compara??o entre o m?todo de controle proposto e o tradicional, atribuindo-se diferentes n?veis de entrada e constatando-se graficamente as respostas de sa?da. Com o projeto e desenvolvimento dos circuitos, firmware e placa de circuito impresso do dispositivo proposto, p?de-se efetuar experimentos para constatar sua capacidade de convers?o de energia e verificar as respostas dos m?todos de controle supracitados, colocando-o como uma poss?vel op??o vi?vel e somando uma pequena contribui??o ?s tecnologias embarcadas na ?rea de energias renov?veis. / The scarcity of natural resources and the search for alternative energy sources promote a rapid change in the global energy matrix. Among the renewable energy sources solar energy is the most promising, since it has the highest growth rate at present. Researchers around the world have sought ways of enabling their progress, developing technologies with greater efficiency and lower cost. As a contribution to the advancement of this technology, this document proposes the development of a microgrid in continuos current connecting the photovoltaic panels through a device with tracking strategy developed based on the method perturbation and observation that will advise the electronic circuit power and a wireless communication system for monitoring of individual generation. Simulations have been developed for to choice of connection topology and comparison between the proposed and traditional control method, assigning different input levels and graphically checking the output responses. With the design and development of the circuits, firmware and printed circuit board of the proposed device, it was possible to carry out experiments to verify its capacity of energy conversion and to verify responses of control methods mentioned above, placing it as an viable option and adding a small contribution to technologies of embedded system in the of renewable energy field.

abstract: As renewable energy becomes more prevalent in transmission and distribution systems, it is vital to understand the uncertainty and variability that accompany these resources. Microgrids have the potential to mitigate the effects of resource uncertainty. With the ability to exist in either an islanded mode or maintain connections with the main-grid, a microgrid can increase reliability, defer T&D; infrastructure and effectively utilize demand response. This study presents a co-optimization framework for a microgrid with solar photovoltaic generation, emergency generation, and transmission switching. Today unit commitment models ensure reliability with deterministic criteria, which are either insufficient to ensure reliability or can degrade economic efficiency for a microgrid that uses a large penetration of variable renewable resources. A stochastic mixed integer linear program for day-ahead unit commitment is proposed to account for uncertainty inherent in PV generation. The model incorporates the ability to trade energy and ancillary services with the main-grid, including the designation of firm and non-firm imports, which captures the ability to allow for reserve sharing between the two systems. In order to manage the computational complexities, a Benders' decomposition approach is utilized. The commitment schedule was validated with solar scenario analysis, i.e., Monte-Carlo simulations are conducted to test the proposed dispatch solution. For this test case, there were few deviations to power imports, 0.007% of solar was curtailed, no load shedding occurred in the main-grid, and 1.70% load shedding occurred in the microgrid. / Dissertation/Thesis / M.S. Electrical Engineering 2013