This dissertation aims to present detailed analysis of the small scale wind energy conversion system (WECS) design and implementation. The dissertation will focus on implementing a hardware prototype to be used for testing different control strategies applied to small scale WECSs. Novel control algorithms will be proposed to the WECS and will be verified experimentally in details. The wind turbine aerodynamics are presented and mathematical modeling is derived which is used then to build wind simulator using motor generator (MG) set. The motor is torque controlled based on the turbine mathematical model and the generator is controlled using the power electronic conversion circuits. The power converter consists of a three phase diode bridge followed by a boost converter. The small signal modeling for the motor, generator, and power converter are presented in details to help building the needed controllers. The main objectives of the small scale WECS controller are discussed. This dissertation focuses on two main regions of wind turbine operation: the maximum power point tracking (MPPT) region operation and the stall region operation. In this dissertation, the concept of MPPT is investigated, and a review of the most common MPPT algorithms is presented. The advantages and disadvantaged of each method will be clearly outlined. The practical implementation limitation will be also considered. Then, a MPPT algorithm for small scale wind energy conversion systems will be proposed to solve the common drawback of the conventional methods. The proposed algorithm uses the dc current as the perturbing variable and the dc link voltage is considered as a degree of freedom that will be utilized to enhance the performance of the proposed algorithm. The algorithm detects sudden wind speed changes indirectly through the dc link voltage slope. The voltage slope is also used to enhance the tracking speed of the algorithm and to prevent the generator from stalling under rapid wind speed slow down conditions. The proposed method uses two modes of operation: A perturb and observe (PandO) mode with adaptive step size under slow wind speed fluctuation conditions, and a prediction mode employed under fast wind speed change conditions. The dc link capacitor voltage slope reflects the acceleration information of the generator which is then used to predict the next step size and direction of the current command. The proposed algorithm shows enhanced stability and fast tracking capability under both high and low rate of change wind speed conditions and is verified using a 1.5-kW prototype hardware setup. This dissertation deals also with the WECS control design under over power and over speed conditions. The main job of the controller is to maintain MPPT while the wind speed is below rated value and to limit the electrical power and mechanical speed to be within the system ratings when the wind speed is above the rated value. The concept of stall region and stall control is introduced and a stability analysis for the overall system is derived and presented. Various stall region control techniques are investigated and a new stall controller is proposed and implemented. Two main stall control strategies are discussed in details and implemented: the constant power stall control and the constant speed stall control. The WECS is expected to work optimally under different wind speed conditions. The system should be designed to handle both MPPT control and stall region control at the same time. Thus, the control transition between the two modes of operation is of vital interest. In this dissertation, the light will be shed on the control transition optimization and stabilization between different operating modes. All controllers under different wind speed conditions and the transition controller are designed to be blind to the system parameters pre knowledge and all are mechanical sensorless, which highlight the advantage and cost effectiveness of the proposed control strategy. The proposed control method is experimentally validated using the WECS prototype developed. Finally, the proposed control strategies in different regions of operation will be successfully applied to a battery charger application, where the constraints of the wind energy battery charger control system will be analyzed and a stable and robust control law will be proposed to deal with different operating scenarios. / Ph. D.

No description available.

L'orientation énergétique actuelle vers le développement de systèmes électriques isolés, s'est traduit par l'établissement de nouvelles directives sur les performances et la fiabilité des structures de puissance mises en oeuvre, en particulier ceux à base d'énergies renouvelables. C'est dans ce contexte que s'inscrivent ces travaux de thèse, qui aboutissent à l'élaboration de nouveaux outils destinés à l'amélioration de la qualité d'énergie et de la stabilité d'un micro-réseau autonome. Concernant l'optimisation énergétique des interfaces de conversion pour un réseau autonome, nous avons développé de nouveaux algorithmes de commande basés sur le concept de platitude des systèmes différentiels. L'avantage de cette technique réside dans la possibilité d'implémentation de régulateurs à une boucle. Cela garantit des propriétés dynamiques élevées en asservissement et en régulation. De plus, une prédiction exacte de l'évolution des variables d'états du système est possible. Concernant la stabilité des micro-réseaux autonomes, nous avons proposé des outils pour traiter les phénomènes d'instabilités, causés notamment par la perte d'informations de charges et par le phénomène de résonance des filtres d'interconnexion / The actual electrical energy demand focuses on the development of stand-alone electrical systems which leads to the definition of new directives on performances and reliability of the electrical structures, especially those based on renewable energy. The main objective of this work concerns the development of new tools to improve the power quality and the stability of autonomous micro-grid systems. In this aim, new control algorithms based on the concept of differential flatness have been developed. The main advantage of the proposed technique is the possibility of implementing one loop controllers ensuring high dynamic properties. In the same time, it allows accurate prediction of the evolution of all state variables of the system. Concerning the stability of the autonomous micro-grid systems, we proposed tools to deal with instability phenomena either caused by the loss of load information and the resonance phenomenon of the passive filters

This thesis introduces a new photovoltaic (PV) system architecture employing low voltage parallel-connected PV panels interfaced to a high voltage regulated DC bus of a three-phase grid-tied inverter. The concept provides several improvements over existing technologies in terms of cost, safety, reliability, and modularity. A novel resonant mode DC-DC boost converter topology is proposed to enable the PV modules to deliver power to the fixed DC bus. The topology offers high step-up capabilities and a nearly constant efficiency over a wide operating range. A reduced sensor maximum power point tracking (MPPT) controller is developed for the converter to maximize energy harvesting of the PV panels. The reduced sensor algorithm can be generally applied to the class of converters employing pulse frequency modulation control. A ZigBee wireless communication system is implemented to provide advanced control, monitoring and protection features. A testbench for a low cost 500 $W$ smart microconverter is designed and implemented, demonstrating the viability of the system architecture.

This thesis introduces a new photovoltaic (PV) system architecture employing low voltage parallel-connected PV panels interfaced to a high voltage regulated DC bus of a three-phase grid-tied inverter. The concept provides several improvements over existing technologies in terms of cost, safety, reliability, and modularity. A novel resonant mode DC-DC boost converter topology is proposed to enable the PV modules to deliver power to the fixed DC bus. The topology offers high step-up capabilities and a nearly constant efficiency over a wide operating range. A reduced sensor maximum power point tracking (MPPT) controller is developed for the converter to maximize energy harvesting of the PV panels. The reduced sensor algorithm can be generally applied to the class of converters employing pulse frequency modulation control. A ZigBee wireless communication system is implemented to provide advanced control, monitoring and protection features. A testbench for a low cost 500 $W$ smart microconverter is designed and implemented, demonstrating the viability of the system architecture.

Made available in DSpace on 2016-08-17T14:52:41Z (GMT). No. of bitstreams: 1 Dissertacao-GuilhermeCarvalhoFarias.pdf: 1837201 bytes, checksum: 75a44efdfd7752087fd597668e388184 (MD5) Previous issue date: 2016-02-29 / This study consists in a comparative analysis of MPPT strategies for low power wind turbines and the development of a control methodology for a battery charging system. The main MPPT strategies in the literature are described and implemented, along with all of their auxiliary control loops. To perform the comparison, a simulation platform is developed. Mathematical modeling of all components in the platform is described, as well as how they relate with each other. This platform allows keeping the system parameters the same for all methods, and modifying only the necessary to implement each of them. The control method for battery charging is presented and analyzed. One of the MPPT strategies described is applied together with this methodology. The methodology of the simulations are performed with switched models to validate the project realized with the developed average models. / Este trabalho consiste na análise comparativa entre métodos MPPT para turbinas eólicas de pequeno porte e desenvolvimento de uma metodologia de controle para um sistema de carregamento de baterias. Os principais métodos de MPPT presentes na literatura são descritos e implementados, juntamente com suas malhas de controle auxiliares. Para realizar a comparação, uma plataforma de simulação é desenvolvida. O modelamento matemático de todos os componentes presentes na plataforma é descrito, bem como a forma como eles se relacionam. Essa plataforma permite manter os parâmetros do sistema iguais para todos os métodos, somente modificando o necessário para implementar cada um deles. A metodologia de controle para carregamento de baterias é apresentada e analisada. Um dos métodos de MPPT descritos é aplicado juntamente à essa metodologia. As simulações da metodologia são realizadas com modelos chaveados, para validar o projeto realizado com os modelos médios levantados.

This master thesis deals with use grid-off photovoltaic system for recharging electric vehicle. First is explained the principle of converting solar energy into electric energy and theoretically describes the components of the system. Furthermore, is presented a real application of the photovoltaic power plants in the world for recharging electric vehicles but also for other uses. The next section theoretically describes the grid-off system how it shout look like in real and there are presented the possibilities of choice of components. The main part is the actual construction of the grid-off system for recharging electric vehicle and measurement. The conclusion of this thesis is made up for the expected economic recovery of the entire system.

Energy harvesting is becoming increasingly important in low-power applications where energy from the environment is used to power the system alone, or to supplement a battery. For example, pulse oximeter sensors inside helmets of road racing cyclists are powered by the sun. These sensors have become smaller and more practical without the limitation of a finite energy supply. Harvested energy from an energy transducer (solar, piezoelectric, etc.) must be maximized to ensure these devices can survive periods where environmental energy is scarce. The conversion process from the transducer to usable power for the device is not perfectly efficient. Specifically, the output voltage of a solar cell is a function of the light intensity, and by extension the load it powers. A small perturbation of the light source quickly diminishes the available power. The wasted power reduces the energy available for the application, and can be improved using an approach called maximum power point tracking (MPPT). This technique maximizes harvesting efficiency by dynamically impedance matching the transducer to its load. This report introduces the Maximum Efficient Solar Harvester (MESH), an MPPT algorithm tuned for a specific Wireless Sensor Network (WSN) application. MESH specifically controls the operation of the DC-DC converter in a solar power management unit (PMU). The control is done by monitoring the available light and feeding that information to choose the optimal operating point DC-DC converter. This operating point has a direct dependency on the overall efficiency of the system. For MESH to be practical, the cost and power overhead of adding this functionality must be assessed. Empirical results indicate that MESH improves the maximum efficiency of the popular Texas Instruments (TI) RF2500-SEH WSN platform by an average of 20%, which far exceeds the power overhead it incurs. The cost is also found to be minimal, as WSN platforms already include a large portion of the hardware required to implement MESH. The report was done in collaboration with Stephen Kobdish. It covers the software implementation and MESH architecture definition; Kobdish's companion report focuses on hardware components and the bench automation environment. / text

Tese de Mestrado Integrado. Engenharia Electrotécnica e de Computadores. Área de Especialização de Automação. Faculdade de Engenharia. Universidade do Porto. 2012

El presente proyecto detalla el desarrollo de un sistema de control que tiene como objetivo mejorar el performance de aplicaciones solares para electrificación rural. La idea fundamental es que el sistema realiza el seguimiento del máximo punto de potencia en paneles solares estabilizando su funcionamiento en esta zona. Para poder diseñar y construir el sistema, se hará uso de técnicas de control, conocimientos de conversores DC-DC y además de programación de microcontroladores. Esta tesis consta de cinco capítulos. En el primer capítulo se presenta la problemática y justificación del desarrollo del proyecto, así como los objetivos buscados. En el segundo capítulo se trata el marco teórico de la tesis, una explicación de las técnicas de control utilizadas, conceptos aplicados a fuentes DC-DC y una descripción de los elementos que conforman Sistema Fotovoltaico. En el tercer capítulo se trata de la descripción del hardware, en el cual se describe el diseño del conversor DC-DC elegido. En el cuarto capítulo se presenta la descripción de la etapa de control, la cual muestra el algoritmo usado para el control, así como la simulación y los resultados. Por último, en el quinto capítulo, se muestra los resultados experimentales de la construcción del circuito y su operación, así como un informe de costos de la tesis. / The present project details the development of a control system that aims to improve the performance of solar applications for rural electrification. The designed system monitors the maximum power point in a solar panel stabilizing its operation in this area. In order to design and build the system, control techniques, knowledge of DC-DC converters and programming of microcontrollers were use. This thesis consists of five chapters. In the first chapter the problem and justification of the development of the project is presented, as well as the objectives sought. The second chapter deals with the theoretical framework of the thesis, an explanation of the control techniques used, concepts applied of DC-DC sources and a description of the elements that make up the Photovoltaic Autonomous System. The third chapter deals with the hardware description, in which the design of the chosen DC-DC converter is detail. In the fourth chapter the description of the control stage is presented, which shows the fuzzy algorithm used for the control, as well as the simulation and the results. Finally, in the fifth chapter, the experimental results of the developed prototyped are shown in a 100W photovoltaic panel control scenario then conclusion of the development process are presented as well. / Tesis