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.

Yes / Hybrid AC-DC microgrid (HMG) allows direct integration of both AC distributed generators (DGs) and DC DGs, AC and DC loads into the grid. The AC and DC sources, loads are separate out and are connected to respective subgrid mainly to reduce the power conversion, thus the overall efficiency of the system increases. This paper aims to introduce a novel hybrid AC-DC microgrid planning and design model within a microgrid market environment to maximize net social welfare (NSW). NSW is defined as present value of total demand payment minus present value of total planning cost including investment cost of distributed energy sources (DERs) and converters, operation cost of DERs and the cost of energy exchange with the utility grid subject to network constraints. Scenario Tree approach is used to model the uncertainties related to load demand, wind speed and solar irradiation. The effectiveness of the proposed model is validated through the simulation studies on a 28-bus real hybrid AC-DC microgrid.

Some communities in remote locations with high wind velocities and an unreliable utility supply, will typically install small diesel powered generators and wind generators to form a microgrid. Over the past few years, microgrid projects have been developed in many parts of the world, and commercial solutions have started to appear. Such systems face specific design issues, especially when the wind penetration is high enough to affect the operation of the diesel plant. The dynamic behavior of a medium penetration hybrid microgrid is investigated. It consists of a diesel generator set, a wind-generator and several loads. The diesel engine drives a 62.5 kVA synchronous generator with excitation control. The fixed-speed wind turbine drives a 60 kW cage rotor induction generator. The microgrid can be connected to the utility grid but can also run as an isolated system. The total load of the microgrid is about 100 kVA which varies during the day, and consists of static and dynamic loads, including an induction motor. The excitation controller and speed controller for the diesel’s synchronous generator are designed, as well as the power control of the wind turbine, and the controller for capacitor banks and dump load. The system is modeled and simulated using PSCAD. The study evaluates how the power generation is shared between the diesel generator set and the wind generator, the voltage regulation during load connections, and discusses the need of battery energy storage, the system ride- through-fault capability and frequency control, particularly at times when the utility is disconnected and the microgrid is run as an independent isolated power system. The results of several case studies are presented.

A hybrid ac/dc microgrid is a more complex but practical network that combines the advantages of an AC and a DC system. The main advantage of this network is that it connects both alternating current and direct current networks via an interlinking converter (IC) to form a unified distribution grid. The hybrid microgrid (HMG) will enable the direct integration of both alternating current (AC) and direct current (DC) distributed generators (DGs), energy storage systems (ESS), and alternating current and direct current (DC) loads into the grid. The alternating current and direct current sources, loads, and ESS are separated and connected to their respective subgrids primarily to reduce power conversion and thus increase overall system efficiency. As a result, the HMG architecture improves power quality and system reliability. Planning a hybrid microgrid entails estimating the capacities of DGs while taking technical, economic, and environmental factors into account. The hybrid ac-dc microgrid is regarded as the distribution network of the future, as it will benefit from both ac and dc microgrids. This thesis presents a general architecture of a hybrid ac-dc microgrid, which includes both planning and design. The goal of the Hybrid ac-dc microgrid planning problem is to maximise social welfare while minimising total planning costs such as investment, maintenance, and operation costs. This configuration will assist Hybrid microgrid planners in estimating planning costs while allowing them to consider any type of load ac/dc and DER type. Finally, this thesis identifies the research questions and proposes a future research plan.

Submitted by Silvana Teresinha Dornelles Studzinski (sstudzinski) on 2016-02-18T13:57:51Z No. of bitstreams: 1 Henrique Tiggemann_.pdf: 3072800 bytes, checksum: d759a40bb6ab933bb882d6a0d2eb6a92 (MD5) / Made available in DSpace on 2016-02-18T13:57:51Z (GMT). No. of bitstreams: 1 Henrique Tiggemann_.pdf: 3072800 bytes, checksum: d759a40bb6ab933bb882d6a0d2eb6a92 (MD5) Previous issue date: 2015-10-09 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / PROSUP - Programa de Suporte à Pós-Gradução de Instituições de Ensino Particulares / A busca de novas alternativas para o suprimento de energia elétrica em comunidades isoladas sempre foi um desafio motivacional tanto de âmbito cientifico quanto social. Busca-se uma solução robusta, que consiga suprir a demanda solicitada da melhor forma possível e com o menor impacto ambiental. São apresentados neste trabalho a caracterização e o desenvolvimento de uma microrrede híbrida fotovoltaica, conectada a um simulador de carga experimental com suporte a acesso remoto. A microrrede é constituída de quatro módulos fotovoltaicos de duas tecnologias, mono e multicristalino, totalizando 570 W pico de potência e com capacidade máxima de suprir um conjunto de cargas de até 1 kW em tensão alternada de 220 V. Também faz parte da microrrede um banco de estocagem inicial de energia de 200 Ah com tensão nominal de 24 V, formado por baterias seladas associadas em série/paralelo e um quadro de comando onde fica situado o controlador Arduíno e demais componentes de conversão de energia. Para avaliar a microrrede em dias que o banco de estocagem estiver em nível mínimo, foi utilizada a rede da concessionária simulando uma fonte alternativa de energia, que pode ser pilha combustível, gerador a diesel, etc. Foi observado por meio de medições elétricas obtidas pelo sistema de aquisição que a microrrede está funcionando adequadamente. As cargas conectadas nesta microrrede são alimentadas segundo um perfil de funcionamento preestabelecido no projeto, com consumo diário de 962 Wh. Este perfil foi construído segundo um número de horas diárias para o funcionamento de cada carga da residência, podendo ser modificado pelo usuário visando uma economia de energia. A interrupção das cargas não prioritárias pode ser também realizada a distância. O sistema é monitorado e gerenciado através de um controlador Arduíno, e o acesso remoto realizado através de um computador conectado à rede de dados (internet). Tal acesso remoto permite visualizar o comportamento elétrico e energético da microrrede além de possibilitar a utilização do sistema para experimentos técnicos e implementação de novas ações de controle à distância. A microrrede está instalada no prédio C02 da UNISINOS. / The search for new alternatives for energy supply in island communities has always been a motivational challenge in the scientific and societal context. The aim is a robust solution which is able to meet the demand requested in the best way as possible and with the least environmental impact. Is being presented in this work the characterization and the development of a hybrid photovoltaic microgrid, connected to an experimental load simulator that supports remote access. The microgrid consists of four photovoltaic modules of two technologies, monocrystalline and multicrystalline totaling 570 W peak power and capacity to supply loads of up to 1 kW with alternating voltage of 220 V. Is also part of the microgrid an initial storage power bank of 200 Ah with a nominal voltage of 24 V, consisting of sealed batteries linked in series / parallel, and a control panel where the Arduino controller is located and other power conversion components. To assess the microgrid in days of the storage bank is at minimum, the power line grid was used to simulate an alternative source of energy, which can be fuel cell, diesel generator, etc. Has been observed through electrical measurements obtained by the acquisition system that the microrrede is working properly. Loads connected in this microgrid are powered according to operating profile predetermined in the project, with daily consumption of 962 Wh. This profile has been built according to a number of daily hours of operation of each residence load and can be modified by the user aiming energy savings. The interruption of non-priority loads can also be performed virtually. The system is monitored and managed through an Arduino controller, and remote access done through a computer connected to the data network (internet). Such remote access allows viewing the electrical and energetic behavior of the microrrede besides enabling the use of the system for technical experiments and implementing new distance control actions. The microgrid is installed on the C02 building at UNISINOS.

Modern power networks incorporate communications and information technology infrastructure into the electrical power system to create a smart grid in terms of control and operation. The smart grid enables real-time communication and control between consumers and utility companies allowing suppliers to optimize energy usage based on price preference and system technical issues. The smart grid design aims to provide overall power system monitoring, create protection and control strategies to maintain system performance, stability and security. This dissertation contributed to the development of a unique and novel smart grid test-bed laboratory with integrated monitoring, protection and control systems. This test-bed was used as a platform to test the smart grid operational ideas developed here. The implementation of this system in the real-time software creates an environment for studying, implementing and verifying novel control and protection schemes developed in this dissertation. Phasor measurement techniques were developed using the available Data Acquisition (DAQ) devices in order to monitor all points in the power system in real time. This provides a practical view of system parameter changes, system abnormal conditions and its stability and security information system. These developments provide valuable measurements for technical power system operators in the energy control centers. Phasor Measurement technology is an excellent solution for improving system planning, operation and energy trading in addition to enabling advanced applications in Wide Area Monitoring, Protection and Control (WAMPAC). Moreover, a virtual protection system was developed and implemented in the smart grid laboratory with integrated functionality for wide area applications. Experiments and procedures were developed in the system in order to detect the system abnormal conditions and apply proper remedies to heal the system. A design for DC microgrid was developed to integrate it to the AC system with appropriate control capability. This system represents realistic hybrid AC/DC microgrids connectivity to the AC side to study the use of such architecture in system operation to help remedy system abnormal conditions. In addition, this dissertation explored the challenges and feasibility of the implementation of real-time system analysis features in order to monitor the system security and stability measures. These indices are measured experimentally during the operation of the developed hybrid AC/DC microgrids. Furthermore, a real-time optimal power flow system was implemented to optimally manage the power sharing between AC generators and DC side resources. A study relating to real-time energy management algorithm in hybrid microgrids was performed to evaluate the effects of using energy storage resources and their use in mitigating heavy load impacts on system stability and operational security.

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As we are moving towards a future carbon-neutralsociety, development of residential microgrids attracts much attentionaround the world with its efficient utilization of renewableenergy. A residential microgrid is a small power system fora house, which consists of a solar photovoltaic (PV) source,a battery storage, residential loads, and an interface to thegrid. In this paper, a hybrid AC-DC microgrid is proposed,studied and simulated in Matlab/Simulink. A coordinated controlstrategy is developed so that the PV converter is controlledto maximize its power generation, the battery converter iscontrolled to stabilize the system with the battery state of chargeconstraints, and an interlinking converter is controlled to decidethe connection/disconnection and the power flow with the grid.The simulation results show the effectiveness of the proposedsolution under various operating conditions. / I det här pappret föreslås, studeras ochsimuleras ett hybrid-anpassat lokalt självförsörjande elnät iSimulink och Matlab. Solpaneler utgör den distribueradeförnyelsebara energikällan i nätet. Panelerna styrs med enMPPT-algoritm för att maximera kraftgenereringen. Batterietsladdningstillstånd används i det designade batterilagringssystemetför att garantera lång livstid och för att fatta beslut omladdning och urladdning. Kraftöverföring mellan ACoch DCnätverk sker via en dubbelriktad omvandlare. Det konstrueradehybridnätet fungerar självständigt samt vid sammankopplingtill huvudnätet. Ett koordinerat kontrollsystem implementerasför att möjliggöra kommunikationen mellan lokalnätets olikadelar. Resultaten från simuleringstestet visar att det föreslagnanätet uppfyller stabilitetskrav och god funktion under varierandedriftstillstånd. / Kandidatexjobb i elektroteknik 2021, KTH, Stockholm