This project work focuses on the feasibility study of a hybrid PV-Wind System for rural electrification at the Estatuene Locality in southern Mozambique. This is in line with electricity network expansion, which, in Mozambique shows high implementation cost and low operation cost. Through field research, an analysis was made of the actual electrical demand in the Estatuene rural community. The wind data was collected from the installed weather stations in the region while the solar data were extracted internally from the HOMER software by introducing the site coordinates. All the configurations, simulations and selection of hybrid systems were also made using HOMER. For the Estatuene rural community it was estimated a scaled annual average demand of 9.4 kWh/day with a peak load of 1.4 kW for DC charge; and a total scaled annual average of 133 kWh/day with a peak load of 15.3 kW for AC Charge. The annual mean solar potential is 5.205 kWh/m2/d, and the mean wind speed is 4.84 m/s for 12 meters above the ground. Thus the calculations and the selection of the best configuration of the hybrid system were crossed out with the technical specifications and costs of photovoltaic panels, wind turbines, power converter, batteries, and the electricity network, specifically for the comparison between an optimum hybrid system solution and two separate ones. The calculations presented an analysis of the technical and the financial viability of the selected hybrid system for local electric power production.

Two key solutions to reduce the greenhouse gas emissions and increase the overall energy efficiency are to maximize the utilization of renewable energy resources (RERs) to generate energy for load consumption and to shift to low or zero emission plug-in electric vehicles (PEVs) for transportation. The present U.S. aging and overburdened power grid infrastructure is under a tremendous pressure to handle the issues involved in penetration of RERS and PEVs. The future power grid should be designed with for the effective utilization of distributed RERs and distributed generations to intelligently respond to varying customer demand including PEVs with high level of security, stability and reliability. This dissertation develops and verifies such a hybrid AC-DC power system. The system will operate in a distributed manner incorporating multiple components in both AC and DC styles and work in both grid-connected and islanding modes. The verification was performed on a laboratory-based hybrid AC-DC power system testbed as hardware/software platform. In this system, RERs emulators together with their maximum power point tracking technology and power electronics converters were designed to test different energy harvesting algorithms. The Energy storage devices including lithium-ion batteries and ultra-capacitors were used to optimize the performance of the hybrid power system. A lithium-ion battery smart energy management system with thermal and state of charge self-balancing was proposed to protect the energy storage system. A grid connected DC PEVs parking garage emulator, with five lithium-ion batteries was also designed with the smart charging functions that can emulate the future vehicle-to-grid (V2G), vehicle-to-vehicle (V2V) and vehicle-to-house (V2H) services. This includes grid voltage and frequency regulations, spinning reserves, micro grid islanding detection and energy resource support. The results show successful integration of the developed techniques for control and energy management of future hybrid AC-DC power systems with high penetration of RERs and PEVs.

On-load tap changers and static synchronous compensators (STATCOM) are the main components for voltage regulation and power quality optimization in the power system. STATCOMs are used in both industrial applications and utility to stabilize the grid and reduce downtime. STATCOM is based on power electronics that is put together as a voltage source converter. However, as STATCOMs are connected in shunt, they provide voltage regulation indirect, by the injection of reactive power. Which might be insufficient for emerging grid codes and power systems with less inertia. This thesis’s purpose is to investigate a series voltage source converter (SVSC), which is connected in series with the grid. Series connected devices may provide better voltage regulating capabilities than shunt devices with the same amount of reactive power compensation, as it can regulate the voltage directly. The SVSC can also be used for power system compensation and power flow control. The SVSC consists of a Chain-Link Modular Multilevel Converter that is connected directly in series with the power system without a coupling transformer. The SVSC injects a voltage in quadrature with the current through the SVSC, this gives the SVSC the ability to emulate a reactance, along with increasing the voltage. The maximum injected voltage from the SVSC is 30% of the system voltage. As the voltage is injected in quadrature with the current, the SVSC can change to voltage more if the power factor is low. The SVSC is able to keep the voltage on the load side constant in several different load and grid scenarios. Furthermore, the SVSC was able to emulate both a capacitance and an inductance, and control the active power flow. However, the SVSC was not able to regulate the voltage as desired when the power factor is close to 1. / Lindningsomkopplare och static synchronous compensators (STATCOM) är de huvudsakliga komponenterna för spänningsreglering och elkvalité optimering i elnätet. STATCOMs används i både industrin och av elnätsägare för att stabilisera elnätet och minska driftstopp. STATCOM är baserat på kraftelektronik som är byggt till en voltage source converter. I alla fall, eftersom STATCOMs är anslutna i shunt med elnätet, kan de endast spänningsreglera indirekt, genom att tillföra reaktiv effekt. Vilket kan vara otillräckligt med nya elnätsregler och elnät med lägre tröghet. Den här avhandlingens syfte är att undersöka en series voltage source converter (SVSC), som är ansluten i serie med elnätet. Enheter som är anslutna i serie med elnätet kan leverera bättre spänningsreglering än enheter som är anslutna i shunt med samma mängd reaktiv effekt kompensering. SVSC:n kan också användas för lednings kompensering och effektflödes kontroll. SVSC:n består av en Chain-Link Modular Multilevel Converter som är ansluten i serie med elnätet utan en kopplingstransformator. SVSC genererar en spännings som är i kvadratur med strömmen genom SVSC:n, det gör att SVSC kan emulera en reaktans, men även öka spänningen. Den maximala spänningen från SVSC:n är 30% av systemspänningen. Eftersom spänningen är i kvadratur med strömmen, så kan SVSC ändra spänningen mer om effektfaktorn är låg. SVSC:n kan hålla spänningen konstant på last sidan under flera olika last- och elnäts scenarier. Dessutom kunde SVSC:n emulera både en induktans och kapacitans, och kontrollera det aktive effektflödet. Men, SVSC:n kunde inte reglera spänningen som önskat när effektfaktorn var nära 1.

Un système hybride multi-source est étudié dans cette thèse pour la génération dispersée basée sur des sources d’énergie renouvelable et des systèmes de stockage d’énergie. Il comprend un générateur éolien comme source d’énergie primaire, des super-condensateurs comme système de stockage à dynamique rapide, des piles à combustible et des électrolyseurs comme système de stockage sur le long terme sous forme d’hydrogène. Ils sont tous connectés à un bus continu commun et un onduleur est utilisé pour la connexion du système entier au réseau. Dans ce mémoire, nous avons présenté la modélisation du système, la conception du contrôle y compris des stratégies de répartition des flux de puissance et la gestion énergétique. Cette centrale hybride peut finalement générer des puissances lissées et contrôlables comme la plupart des générateurs classiques. Les performances ont été testées en simulation numérique et aussi sur un prototype expérimental. Les contributions scientifiques principales de cette thèse sont les suivantes : l’utilisation et l’adaptation des formalismes pour la modélisation des systèmes complexes et la conception de leur commande ; la conception et la réalisation expérimentale des émulateurs pour réduire le temps et le cout du développement du prototype expérimental ; la proposition et la validation de deux stratégies de gestion des puissances pour la régulation du bus continu et le contrôle des puissances transitées au réseau et enfin la proposition des stratégies de supervision énergétique avec la définition des modes de fonctionnement pour le générateur actif éolien afin d’assurer une disponibilité énergétique / A hybrid power system is studied in this thesis for the distributed generation based on renewable energy resources and energy storage systems in microgrid applications. It consists of a wind generator as primary energy source, super-capacitors as fast-dynamic storage system, fuel cells and electrolyzers as long-term storage system in hydrogen. They are all connected to a common DC bus and an inverter is used for the connection of the whole system to the grid. In this thesis, we have presented the system modeling, the control design including the power balancing and energy management strategies. This hybrid power system can finally supply controllable smooth powers as most conventional power plants. The performances have been tested in numerical simulations and also on an experimental test bench. As result, it is able to provide ancillary services to the microgrid. The main scientific contributions of this thesis are: the use and the adaptation of the graphical tools for the modeling of complex systems and their design; the design and the experimental implementation of real-time emulators in order to reduce the time and the cost of an experimental platform; the proposition and the validation of two power balancing strategies for the DC-bus voltage regulation and the grid power control and finally the proposition of energy management strategies for the active wind generator to ensure the energy availability

Cette thèse est une contribution à l'étude des systèmes hybrides éoliens-photovoltaïques avec batteries sur plusieurs aspects : évaluation des sources, modélisation, simulation, optimisation du dimensionnement et enfin commande et supervision. Ainsi, dans un premier temps, une étude d'impact sur l'évaluation du potentiel en énergies renouvelables sur un site donné en prenant en compte la consommation dans un habitat résidentiel (période et méthode d'acquisition des données, techniques d'évaluation, ...) est présentée. Puis, les modèles énergétiques des différents composants du système ainsi que les aspects économiques et écologiques sont définis. L'ensemble est représenté à l'aide du logiciel Matlab/Simulink. Ensuite, une méthodologie d'optimisation du dimensionnement du système multi-sources est développée et comparée à plusieurs approches, allant d'une optimisation mono-objective à une multi-objective et évaluant le coût économique et écologique de chacune de ces solutions. Une solution « pratique » est retenue pour les composants PV, éolien et batteries du système final afin d'en évaluer la viabilité énergétique, économique et écologique. Les résultats montrent un impact environnemental faible et un coût raisonnable du point de vue économique ainsi qu'une satisfaction de la charge dans les limites tolérées par l'usager. La méthode développée de dimensionnement est comparée à un outil commercial existant. Enfin, un banc expérimental PV-éolien avec batteries est mis en oeuvre avec une nouvelle technique de supervision basée sur le contrôle des courants et l'estimation de l'état de charge des batteries. / This thesis is a contribution to the study of photovoltaic-wind-battery hybrid systems for several aspects: source evaluation, modeling and simulation, design optimization and finally control and supervision. Thus, an impact study on the evaluation of renewable energy potential at a given site taking into account consumption in residential housing (period and method of data acquisition, evaluation techniques...) is presented. In addition, all the components of the system are modeled and economic and ecological aspects are defined in order to make an overall assessment of various system configurations. All models are represented using Matlab/Simulink tool. Then, a methodology for single and multi-objective design optimization of a multi-source system is developed to minimize system Life Cycle Cost (LCC), Embodied Energy (EE) and Loss of Power Supply Probability (LPSP). A "practice solution" is thus retained and evaluated. Results show a low environmental impact and a reasonable economic cost as well as a satisfaction of the load within the limits tolerated by the user. Besides, a very convincing comparison of the developed sizing method to an existing commercial tool is presented. At the end, an experimental PV-wind-battery tested is developed in laboratory to ensure a quasi-realistic emulation of hybrid system behavior for different configurations. Accordingly, a new supervision strategy based on currents control and battery state of charge estimation is successfully validated.

An exponentially growing global population, power demands, pollution levels and, on the other hand, rapid advances in means of communication have made the public aware of the complex energy situation. The Kingdom of Saudi Arabia has vast open land, an abundance of fossil fuel, a small population but has always been among the front-runners where the development and utilisation of clean sources of energy are concerned. Several studies on wind, solar and geothermal sources of energy have been conducted in Saudi Arabia. Solar photovoltaic (pv) has been used for a long time in many applications such as cathodic protection, communication towers and remotely located oil field installations. Recently, a 2MW grid-connected pv power plant has been put online and much larger solar desalination plants are in planning stage. Wind resource assessment, hub height optimisation, grid-connected wind farm and hybrid power system design were conducted in this study using existing methods. Historical daily mean wind speed data measured at 8 to 12metres above ground level at national and international airports in the kingdom over a period of 37 years was used to obtain long-term annual and monthly mean wind speeds, annual mean wind speed trends, frequency distribution, Weibull parameters, wind speed maps, hub height optimisation and energy yield using an efficient modern wind turbine of 2.75MW rated power. A further detailed analysis (such as estimation of wind shear exponent, Weibull parameters at different heights, frequency distribution at different heights, energy yield and plant capacity factor and wind speed variation with height) was conducted using wind speed measurements made at 20, 30 and 40metres above ground level. As a first attempt, an empirical correlation was developed for the estimation of near-optimal hub height (HH = 142.035 * (α) + 40.33) as a function of local wind shear exponent (α) with a correlation coefficient of 97%. This correlation was developed using the energy yield from a wind turbine of 1 000kW rated power and wind speed and local exponent for seven locations in Saudi Arabia. A wind-pv-diesel hybrid power system was designed and specifications were made for a remotely located village, which is being fed 100% by diesel power generating units. The proposed system, if developed, will offset around 35% of the diesel load and therefore will result in decreased air pollution by almost the same amount. The developed wind speed maps, the frequency distributions and estimated local wind shear exponents for seven locations and energy yield will be of great help in defining the further line of action and policy-building towards wind power development and utilisation in the kingdom. The study also recommends conducting a wind measurement campaign using tall towers with wind measurements at more than one height and estimating the local wind shear exponents and developing a wind atlas for the kingdom. The study further states that a grid-connected wind farm of moderate capacity of 40MW should be developed using turbines of varying rated powers. The wind speed data was also analysed using wavelet transform and Fast Fourier Transform (FFT) to understand the fluctuation in wind speed time series for some of the stations. It is also recommended that policy-makers should take firm decision on the development of hybrid power systems for remotely located populations which are not yet connected with the grid. There are two challenges which need research: one is the effect of dust on the moving and structural elements of the wind turbines and the second is the effect of high prevailing temperatures on the performance and efficiency of the same. / Thesis (PhD)--University of Pretoria, 2012. / Mechanical and Aeronautical Engineering / PhD / Unrestricted

Globally, there are approximately 900 000 telecommunication radio base station sites (RBS-sites)located in areas without access to the electrical grid. Traditionally, these sites are powered by dieselgenerators, consuming large amounts of fossil diesel fuel. Diesel combustion is connected both toenvironmental impacts and high economical expenses for the mobile operators. As the mobilenetwork expansion is increasingly located in off-grid areas of developing countries, the search forrenewable power alternatives has been intensified. This Master thesis presents results from a life cycle assessment (LCA) of photovoltaic and windturbine hybrid power configurations for off-grid RBS-sites. The LCA covers environmental impactsfrom all life cycle activities of the hybrid system: from raw material extraction, manufacturing, andtransportation, to on-site usage, and disposal. To enable assessment of variable hybrid configurations, four scalable sub-models were constructed:one diesel sub-model including the generator and yearly diesel consumption, one back-up batterysub-model, one PV module sub-model and one wind turbine sub-model. Included in the sub-modelswere required site equipment; e.g. foundations for generators, PV modules and battery banks, powerconverters, fuel tanks and possible housings. The number of generators, liters of fuel consumed peryear, number of battery cells, square meters of PV module and number of wind turbines were set asvariables. Hereby RBS-sites with different capacities and availability of renewable source could bemodeled. A hybrid configuration including 21 square meters photovoltaic modules, one wind turbine, a storageof 36 (12 V) batteries and one generator back-up consuming 1500 liters of diesel fuel per year wasevaluated. The hybrid site represents between 11 and 16 percent of the different environmentalimpact potentials, global warming potential specifically representing 13 percent, caused by acorresponding traditional diesel site consuming 20000 liters of fuel per year. The most importantparameters influencing the environmental performance of the renewable hybrid site following thediesel fuel production and combustion are the production energy mix and energy intensive processesincluding the up-stream silicon and lead processing. The thesis confirmed great environmental benefits of using wind and solar power at RBS-sites. Theadditional gain of applying wind power when feasible to decrease the PV module area or batterycapacity required was also demonstrated. The great importance of manufacturing location andelectricity mix should encourage Ericsson to map supplier manufacturing locations, searchingpossibilities to decrease the environmental impacts from the manufacturing phase of the differentsub-systems. / Idag finns det omkring 5 miljoner radiobasstationer i det i det globala telekomnätet, varav 900000 ärbelägna i områden utan tillgång till elektricitet. Traditionellt drivs dessa stationer av dieselgeneratorersom konsumerar stora mängder diesel. Dieselförbränningen bidrar både till lokala och globalamiljöeffekter samt höga driftkostnader för mobiloperatörerna. Expansionen av mobilnätet sker i alltstörre utsträckning i områden i utvecklingsländer utan elförsörjning, vilket har ökat intresset föralternativa kraftkällor. Inom examensarbetet har ett redskap för jämförande livscykelanalys (LCA) av förnyelsebara krafthybridlösningarför radiobasstationer utvecklats. Hybriderna kombinerar solceller och vindturbinermed dieselförbränning och batterier. Genom att använda LCA inkluderas miljöeffekter från alla steg i hybridsystemets livscykel; frånutvinning av råmaterial och tillverkning av sub-system, transport, användning på RBS-siten till denslutliga avvecklingen. För att kunna utvärdera olika hybridkonfigurationer skapades 4 olika delmodeller: en delmodell fördieselförbränning innefattande generator och dieselkonsumption, en batteri-delmodell, en PVdelmodellsamt en vindturbin-delmodell. Delmodellerna inkluderar även nödvändiga komponentersom betonggrund till generatorer, PV-modulerna och batteribanken. Antal dieselgeneratorer,battericeller, vindturbiner samt PV-moduler och liter dieselkonsumption kan varieras för att simuleraen specifik anläggning. En hybridlösning med 21 m2 solceller, en vindturbin, 36 stycken (12V) battericeller och endieselgenerator som konsumerar 1500 liter diesel per år analyserades. Hybridlösningen ger upphovtill miljöeffekter motsvarande mellan 11 och 16 procent, global uppvärmning motsvarande 13procent, av miljöeffekterna orsakade av en traditionell dieselkonfiguration som konsumerar omkring20000 liter diesel per år. Betydelsefulla parametrar som påverkar miljöeffekterna frånhybridlösningen förutom produktion och förbränning av diesel är vilken elektricitetsmix somanvänds vid tillverkning av de olika komponenterna och energiintensiva processer som kisel- ochblyframställning. Resultaten tydliggör de stora minskningar av miljöeffekterna som en övergång från dieselförbränningtill sol- och vindkraft på RBS-anläggningar kan ge. Den relativa förbättringen av att installeravindturbiner för att minimera mängden sol- och battericeller har även visats. Betydelsen avproduktionsplats och elektricitetsmix för den totala miljöpåverkan bör motivera Ericsson attkartlägga och välja tillverkare som innebär ett litet bidrag till de totala miljöeffekterna.

Ce mémoire présente le travail de recherche effectué pour la conception d'une stratégie de commande originale, destinée aux systèmes de puissance hybrides en sites isolés. Le système considéré, voué à l'alimentation électrique d'une habitation, comprend deux sources, un groupe de panneaux photovoltaïques et une petite éolienne, et deux types de stockage, un banc de batteries lithium-ion et un de supercondensateurs. Face au problème de gestion de l'énergie dans un système hybride, et aux enjeux de maximisation de sa puissance produite, nous proposons de développer une stratégie de commande basée sur les flux d'énergie. pour cela, nous présentons dans un premier temps les modélisations d'Euler-Lagrange et hamiltonienne du système. Ces modèles permettent d'utiliser la propriété de passivité de celui-ci, et ainsi de synthétiser des commandes par injection d'amortissement pour chaque source, afin de maximiser sa production, et pour les supercondensateurs, dans le but d'assurer une répartition cohérente des flux d'énergie entre eux et les batteries. Les commandes sont finalement mises en œuvre dans un simulateur, puis dans un banc d'essai expérimental, afin d'une part de comparer leurs performances à celles de solutions préexistantes, et d'autre part de valider le bon fonctionnement du système hybride complet les utilisant. / This thesis presents the research about design of a new control strategy for stand-alone hybrid power systems. The considered system is composed of two sources, a group of photovoltaic panels and a low-power wind generator, and of two kinds of storage, a bank of lithium-ion batteries and one of supercapacitors. Faced with the problem of energy management in a hybrid power system, and with necessity of maximizing the produced power, we intend to develop an energy-based control strategy.For this purpose, we present the system's Euler-Lagrange modeling and Hamiltonian modeling. These models allow the use of the passivity property, and then the design of Passivity-Based Controllers for each source, in order to maximize its production, and for the supercapacitors, to ensure a fitted power sharing between batteries and them. The controllers are finally implemented in a simulator, and then in a experimental test bench, in order to compare their performances to pre-existent solutions, and tovalidate the control law for the global hybrid system.