Dissertations / Theses on the topic 'WOUND ROTOR INDUCTION GENERATOR'

Orientador: Dr. Alfeu J. Sguarezi Filho
Dissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Engenharia Elétrica, 2014.
Devido as preocupações com a redu¸c¿ao do uso dos recursos f'osseis e das emiss¿oes de CO2 ocasionadas pelos mesmos, o interesse no uso de energias renov 'aveis aumentou, sendo uma destas fontes a energia e'olica. O Gerador de Indu¸c¿ao de Rotor Bobinado (GIRB) tem demonstrado ser uma ferramenta capaz de otimizar o uso da energia e'olica, dada a sua alta efici¿encia, rentabilidade e robustez mec¿anica, ainda assim 'e necess'ario superar os numerosos desafios que est¿ao presentes nesta tecnologia, tais como qualidade da pot¿encia, estabilidade da rede, entre outros. O objetivo desta pesquisa se concentra no estudo de t'ecnicas de controle de pot¿encia fornecida pelo GIRB aplicado a sistemas de gera¸c¿ao e'olica. No presente caso, o sistema de gera¸c¿ao 'e composto por um GIRB com seu estator conectado diretamente 'a rede e seu rotor 'e conectado 'a rede atrav'es de um conversor bidirecional. Prop¿oe-se estudar o m'etodo de controle direto de torque (CDT) com emprego de controladores PI e por modos deslizantes (SMC) mais PI. O controle direto de torque 'e uma t'ecnica de alto desempenho din¿amico e possibilita o controle independente do torque e fluxo do gerador o que possibilitar'a o controle das pot¿encias ativa e reativa do GIRB. Da mesma forma, 'e estudado o conversor para o processamento da energia gerada. As simula¸c¿oes baseadas em modelos matem'aticos destes m'etodos de controle foram revistos, analisados e comparados com as simula¸c¿oes de textos de refer¿encia. Resultados experimentais obtidos em uma bancada validaram o prot'otipo proposto.
Due to concerns about reducing the use of fossil resources and the CO2 emissions caused by them, interest in the use of renewable energy increased, one of these sources is wind energy. The Wound Rotor Induction Generator (WRIG) has been proved to be a tool to optimize the use of wind energy, given its high efficiency, profitability and mechanical robustness, it is still necessary to overcome the many challenges that are present in this technology, such as power quality, grid stability, among others. This research focuses on the study of control techniques for power supply by WRIG applied to wind generation systems. In this case, the generation system consists of a stator WRIG is connected directly to the electrical network and its rotor too, but via a bidirectional converter. It is proposed to study the method of direct torque control (DTC) with the use of PI and sliding mode controllers (SMC) more PI. The direct torque control is a technique of high dynamic performance and enables independent control of torque and flux generator, which will enable the control of active and reactive power ofWRIG. Likewise, it is studied the converter for processing the generated power. The simulations based on mathematical models of these control methods were reviewed , analyzed and compared with simulations of reference texts . Experimental results obtained on a bench validated the proposed prototype.

Sensorless speed estimation in induction machines (IMs) presents an attractive proposition for eliminating the need for physical speed measurement sensors and thus avoiding the associated reliability and cost issues, such as the requirement of extra wiring, careful mounting, maintenance and adjustment. In this thesis, the feasibility of utilising the stator current and power signals to establish spectral search based (SSB) sensorless speed estimation schemes in wound rotor induction machines (WRIMs) operating in extended slip and open-loop controlled conditions is investigated. The research is performed on three different industrial WRIM designs. The thesis first investigates the spectral content of WRIM electrical and mechanical signals with the principal aim of identifying spectral patterns that can facilitate the development of real-time sensorless speed estimation. The examination is based on detailed harmonic models of the considered machine designs as well as experimental results obtained from tests performed on laboratory test rigs. A generalised theoretical analysis of the possible spectral content of machine signals that enables the derivation of closed form analytical expressions linking individual spectral frequencies to rotor speed is also undertaken. The results demonstrate that it is possible to clearly identify speed dependent components in the stator current and power signals and map the boundaries of the narrowbands maximised by these for extended slip and open-loop operating conditions. To enable improvement in attainable real time SSB estimation rates a dichotomous search algorithm real-time spectral processing method was employed for frequency tracking in this research. The algorithm performance is evaluated in real-time tests performed on a measured steady-state laboratory machine stator current and power signals. The results demonstrate that the dichotomous routine provides an inherent advantage in the frequency estimation rate without compromising the estimation accuracy and can therefore enable significant estimation rate improvement in SSB speed estimation algorithms. Novel sensorless speed SSB estimation techniques are then proposed for WRIM operation in extended slip and voltage/frequency controlled conditions. The algorithms utilise the reported analysis of electrical signals and are separately defined for each assessed operation mode and the stator current, phase power and three-phase power signals. It is shown that, in principle, power signal based estimation algorithms can offer an inherent capability of estimation rate reduction. A novel adaptive sliding window algorithm is defined for open-loop operating conditions that enable estimation in a wide operating speed range while minimising the potential for undesirable overlap with PWM harmonics. The proposed algorithms have been verified and their performance limitations assessed in real-time experiments on three different industrial WRIM designs. It is shown that reliable real-time speed estimation in steady-state and transient operating conditions is possible at an improved estimation rate while maintaining a low estimation error.

En esta Tesis ha sido analizado el control de la màquina sincrónica de rotor bobinado actuando en isla. Para esta configuración, la velocidad mecànica determina la frecuencia, y la tensión de rotor se utiliza para fijar la amplitud de la tensión de estator. Debido a que la constante de tiempo eléctrica es mucho más ràpida comparada con la constante de tiempo mecánica, la velocidad mecánica fue considerada constante y externamente regulada y la investigación se enfocó en la regulación de la amplitud de la tensión de estator.

Cuatro diferentes controladores basados en técnicas de modos deslizantes fueron diseñados en el marco de referencia dq. Las leyes de control obtenidas regulan la amplitud de la tensión de estator independientemte del valor de la carga. Adicionalmente, sólo las medidas de tensión y posición del rotor (para calcular la transformada dq) son necesarias. La estabilidad de los puntos de equilibrio obtenidos fueron probados al menos utilizando anàlisis de pequeña señal.

Se realizó la validación por simulación y experimental de cada controlador en diferentes escenarios. Los resultados obtenidos validan los diseños y muestran las principales ventajas y desventajas de el sistema en lazo cerrado.

El capítulo 2 cubre los problemas de modelado de la màquina sincrónica de rotor bobinado. Partiendo de las ecuaciones trifásicas generales, y utilizando la transformada de Park, se encontraron el modelo en dq del generador sincrónico de rotor bobinado (WRSG) en isla, alimentando tanto carga resistiva como inductiva. Los puntos de equilibrio del sistema obtenido fueron analizados y calculados, luego se definió el objetivo de control. Finalmente, se obtuvieron modelos lineales aproximados y sus respectivas funciones de transferencia.

Los controladores PI son los más usados en la industria porque ofrecen buen desempeño y son sencillos de implementar. En el capítulo 3, se obtuvieron las reglas de sintonización para el controlador PI, y se analizaron estos resultados con el objetivo de proponer nuevos controladores que mejoraran el desempeño de la clásica aproximación PI.

El esquema de control en modos deslizantes para la WRSG conectada a una carga resistiva fue diseñado en el capítulo 4. Éste, también incluye un completo análisis de estabilidad del sistema en lazo cerrado.

El capítulo 5 presenta dos diseños basados en modos deslizantes para regular la amplitud de la tensión de estator para el WRSG actuando en isla. Ambos diseños usan la componente d de la tensión de estator en la función de conmutación. El primer caso es un control anidado, donde un lazo externo PI es añadido para proveer la referencia de la componente d de la tensión. En la segunda aproximación un término integral es añadido a la superficie de conmutación.

El caso de alimentar una carga inductiva es estudiado en el capítulo 6. El controlador requiere una extensión dinámica debido a que la amplitud de la tensión de estator es una salida de grado relativo cero. Como resultado, un controlador robusto, que no depende de los parámetros de la máquina ni de los valores de carga es obtenido.

En el capítulo 7 los resultados de simulación y experimentales para los controladores diseñados para el WRSG actuando en isla son presentados. En primer lugar, una descripción completa del banco es presentada. Esta incluye detalles de la etapa de adquisición de datos y de la DSP utilizada. En segundo lugar, se hace la descripción del procedimiento de simulación. Luego, las simulaciones y experimentos, que contienen diferentes escenarios, con cambios de referencia y variaciones de carga para cada controlador son presentados.
The control of the stand-alone the wound rotor synchronous generator has been analyzed in this dissertation. For this islanded configuration, the mechanical speed determines the frequency, and the rotor voltage is used to set the stator voltage amplitude. Due to the electrical time constant is so fast compared with the mechanical time constants, the mechanical speed was considered constant and externally regulated and the research was focused on the stator voltage amplitude regulation.

Four different controllers based on sliding mode control techniques were designed in the dq reference frame. The obtained control laws regulate the stator voltage amplitude irrespectively of the load value. Furthermore, only voltage and rotor position measures (to compute the dq transformation), are required. The stability of the obtained equilibrium points was proved at least using small-signal analysis.

Simulation and experimental validation of each controller containing several scenarios were carried out. The obtained results validate the designs and show the main advantages and disadvantages of each closed loop system.

Chapter 2 covers the modeling issues of the wound rotor synchronous machine. From the general three-phase dynamical equations, and using the Park transformation, the dq-model of the stand-alone wound rotor synchronous generator feeding both a resistive and an inductive load are obtained. Equilibrium points of the obtained systems are analyzed and, after defining the control objective, the desired equilibrium points are computed.
Finally, linear approximated models are obtained and their transfer functions are also presented.

PI controllers are the most used in the industry because they offers good performance and are easily implementables. In Chapter 3 we obtain the tuning rule for the PI controller, and we analyze these results in order to propose new controllers which improve the classic PI approach.

The sliding mode control scheme for the WRSG connected to a resistive load is designed in Chapter 4. It also includes a complete stability analysis of the closed loop system.

Chapter 5 presents two sliding mode designs to regulate the stator voltage amplitude for a stand-alone wound rotor synchronous generator. Both use the stator voltage d-component error in the switching function. The first case is a nested controller, where an outer PI loop is added to provide the proper d-voltage component reference. In the second approach an integral term is added to the switching function.

The case of feeding an inductive load is studied in Chapter 6. The controller introduces a dynamic extension because the stator voltage amplitude is a zero relative degree output. As result, a robust controller, which neither depends on the machine parameters nor on the load values, is obtained.

In Chapter 7 the simulation and the experimental results of the designed controllers for the stand-alone wound rotor synchronous generator are presented. Firstly, a complete description of the bench is provided. It also includes details of the data acquisition stage and the used DSP card. Secondly, the description of the simulation procedure is commented. Then, the simulation and experiments which contains several scenarios, with reference change and load variations evaluated for each controller are presented.

Comumente, as máquinas de indução são projetadas para atuarem como motores. Assim, a presente tese objetiva estudar, analisar e construir um protótipo de máquina de indução concebida para atuar, exclusivamente, como gerador de indução, ou seja, impulsionada acima da velocidade síncrona. As características operacionais ideais em regime permanente são elaboradas intentando diretrizes de projeto. Concomitantemente, o estudo apresenta e investiga modelagens analíticas obtidas por parâmetros concentrados e, também, modelagens numéricas realizadas pelo método dos elementos finitos. Para isto, um gerador de indução trifásico de 2,2 kW tem o rotor do tipo gaiola de esquilo com ranhuras assimétricas projetado e prototipado. O protótipo do gerador de indução visa melhores características de desempenho como o fator de potência e menores perdas, por exemplo, que uma máquina de indução de mesma potência projetada para atuar como motor, mas funcionando como gerador interligado à rede em regime permanente. Os resultados analíticos, numéricos e experimentais em regime permanente do protótipo do gerador de indução e de um motor de indução de mesma potência, mas funcionando como gerador interligado à rede, são apresentados e comparados. Os resultados experimentais obtidos mostram valores nominais de 0,77 e 83,04% de fator de potência e rendimento, respectivamente, para o funcionamento da máquina convencional no ponto de operação próximo ao valor de corrente nominal. Para a máquina de indução projetada como gerador, os valores nominais de 0,82 e 81,35% de fator de potência e rendimento, respectivamente, foram obtidos no ponto de operação próximo ao valor de corrente nominal.
Commonly, induction machines are designed to act as motors. Thus, the present thesis aims to study, analyze and build a prototype of an induction machine designed to work exclusively as induction generator, i.e. driven above synchronous speed. The optimal steady state operating characteristics are elaborated by bringing design guidelines. Concomitantly, this study investigates and presents analytical modeling obtained by lumped parameters and also numerical modeling carried out by the finite element method. Thus, a three-phase squirrel cage induction generator of 2.2 kW with asymmetric rotor slots has designed and prototyped. The prototype of the induction generator aims best performance characteristics such as power factor, for example, than an induction machine of the same power designed to act as a motor, but functioning as generator parallel with the grid. Analytical, numerical and experimental results in steady state operation of the induction generator prototype and of an induction motor of the same power, but functioning as generator parallel with the grid, are presented and compared. The experimental results show nominal values 0.77 and 83.04% of power factor and efficiency, respectively, for the conventional machine in the operating point close to the value of rated current. For the induction machine designed as a generator, the nominal values 0.82 and 81.35% of power factor and efficiency, respectively, were obtained in the operating point close to the value of rated current.

This thesis investigates a novel induction machine topology that uses a rotating power electronic converter. Steady-state and dynamic performance of the topology is studied to understand its operational principle. Furthermore the potential of improving its efficiency and power factor is investigated. The topology is referred to as wound rotor induction machine with rotating power electronic converter (WRIM-RPEC).     The WRIM-RPEC topology offers the possibility to magnetize the induction machine from the rotor side by introducing a reactive voltage in the rotor. Thus, the power factor of the machine can be improved. Constant speed variable load operation can be achieved by setting the frequency of the introduced voltage. Two options of rotor winding and converter configuration in the WRIM-RPEC system are investigated. The wound rotor windings can either be open-ended and fed by a three-phase back-to-back converter or Y-connected and fed by a single three-phase converter. The dc-link in both converter configurations contains only a floating capacitor. These two configurations give different dc-link voltages at the same torque and speed.     Two analytical steady-state models of the topology are developed in this thesis. The first model can be used to analyze the operating condition of the motor at specific speed and torque. Particularly, the operating range of speed and torque of the topology is investigated. The second model is used to analyze variable power factor operation, including unity power factor operation. Analytical calculations and measurements are carried out on a 4-pole, 1.8kW induction machine and the results are compared.      A dynamic mathematic model is then developed for the WRIM-RPEC system for the back-to-back converter configuration. The mathematic model is then applied in Matlab/Simulink to study the dynamic performance of the system including starting, loading and phase-shifting. The simulation results are compared with measurements on the 4-pole, 1.8kW induction machine. Moreover, the simulation model using the existing Simulink blocks are studied to compare with the results obtained from the mathematic model. Furthermore, the dynamic performance of the WRIM-RPEC system with the single converter configuration is investigated. In addition, harmonic spectra analysis is conducted for the stator and rotor currents.     In the last part of the thesis, efficiency improvement is investigated on the 4-pole induction machine when it is assumed to drive a pump load. It is shown that the efficiency can be further improved by decreasing the rotor resistance. Due to space constraints it is however difficult to decrease the rotor resistance in a 4-pole induction machine. An investigation is thus carried out on a standard 12-pole, 17.5kW squirrel-cage induction machine with inherent low power factor. The cage rotor is redesigned to a wound rotor to enable the connection of converter to the rotor windings. An analytical model is developed to design the wound rotor induction machine. The machine performance from calculations is then compared with FEM simulations with good agreement. The analytical model is further used to design several WRIMs with different dimensions and rotor slot numbers. Power factor and efficiency improvement is then explored for these WRIMs. A promising efficiency increase of 6.8% is shown to be achievable.

QC 20161111

Dentre as fontes de energia renováveis utilizadas para geração de energia elétrica a que mais se destaca atualmente e a energia eólica. 0 crescente índice de penetração da geração eólica na matriz energética dos sistemas de potencia impõe a necessidade da revisão de conceitos anteriormente estabelecidos sobre a estabilidade de sistemas de potencia, uma vez que ainda não e perfeitamente compreendida a influencia de uma maior integração deste recurso no comportamento dos sistemas de potencia. Este trabalho tem como foco o estudo da estabilidade de sistemas com aerogeradores de velocidade fixa equipados com geradores de indução de rotor em gaiola. E estudada a estabilidade angular de um sistema de geração eólica equipado com aerogeradores desta natureza. O problema da estabilidade foi decomposto em três partes: estabilidade estática, estabilidade dinâmica e estabilidade transitória. São definidos os modelos dos componentes do aerogerador para cada um dos estudos realizados. A topologia adotada á a máquina Barramento Infinito (MBI), na qual o restante do sistema de potência a representado pelo seu equivalente de Thevenin. Esta topologia típica de analise de estabilidade de sistemas de potencia e adotada por permitir a obtenção de resultados analíticos para as analises estática e dinâmica. A analise transitória se dá através de simulações computacionais. A fim de manter um caráter mais geral para os resultados as simulações são realizados com três aerogeradores de características distintas. Os resultados obtidos permitem uma melhor compreensão da influencia sobre a estabilidade do sistema de geração eólica dos parâmetros de rede do sistema de potencia como: potencia de curto-circuito do ponto de conexão comum com o sistema de potencia, relação X/R da linha de transmissão e do capacitor de compensação de fator de potencia.
Among the renewable energy sources used to generate electric power one of the most important at this time is the wind power. The growing penetration index of wind power in the power systems energetic matrix leads to the necessity of a reevaluation of the concepts previously established about the stability of power systems, since the influence of a major integration of this resource in the behavior of power systems is not perfectly understood. This work focuses on the stability study of wind power systems equiped with fixed-speed squirrel-cage induction generators. The angular stability of a wind generation system equipped with wind generators of this nature is studied. The stability problem was decomposed in three parts: static stability, dynamic stability and transient stability. The models of the components of the wind generator are defined for each of the studies. The considered topology was an Induction Generator Infinite Bus System (IBM), where the rest of the power system is represented by it’s Thévenin equivalent. This is a typical topology in power systems stability analysis and is adopted in this work aiming at obtaining analytical and general stability results. The transient analysis is performed by computer simulations. In order to provide more generatily to the stability results, all simulations are conducted with three wind generators with distinct characteristics. The obtained results allow a better comprehension about the influence, on the stability of wind power systems, of power system network parameters as: short-circuit capacity of the common connection point with the power system, the X/R relation of the transmission line and the power factor compensation capacitor.

Le Cambodge est un pays situé en Asie du Sud-Est, avec grand potentiel de ressources en énergies renouvelables. Même fort de ce potentiel, la puissance électrique actuellement installée n'est pas suffisante pour tout le pays. Environ 80% de la population vit dans les zones rurales et 75% des ménages sont sans réseau électrique. Ils utilisent une batterie, le moteur diesel, des bougies ou du kérosène pour l'éclairage, la télévision, les multimédia et autres appareils ménagers. Une minorité des citoyens, dans la partie nord utilise des modules pico hydro électriques acheté dans les pays voisins pour éclairage. Mais la tension de sortie et la fréquence ne sont pas vraiment stables en cas de modification de la charge ou de la vitesse de rotation de la turbine. La durée de vie des appareils électroménagers peut ainsi être réduite et des réparations locales sont nécessaires. Des millions de Cambodgiens ne peuvent pas accéder à l'énergie électrique en raison de deux facteurs principaux : les barrières technologiques et les coûts d'investissement élevés. Nos activités de recherche visent à éliminer ces barrières technologiques en concevant des systèmes de production d'énergie pico-hydroélectrique avec une installation rapide et peu coûteuse, simple et adaptée à une application locale tout en gardant une qualité de l'alimentation électrique satisfaisante. La première partie de cet ouvrage décrit la situation de l'énergie dans les zones rurales du Cambodge où les gens sont confrontés à un manque d'alimentation électrique. En conséquence, ils ne peuvent ni améliorer leur niveau de vie, ni développer leur communauté. Les villageois riches utilisent une batterie de voiture, des systèmes photovoltaïques ou pico-hydroélectriques alors que les villageois pauvres utilisent des bougies ou du kérosène pour l'éclairage. Des entreprises locales fournissent des solutions électriques basées sur des énergies renouvelables, mais les prix sont inabordables et loin de leurs attentes. Par conséquent, une solution originale est proposée dans cette thèse avec la récupération de composants électriques d'occasion en vue de la mise en œuvre d'un nouveau système de génération d'électricité pour les zones rurales isolées. Il s'agit ici d'innovation frugale pour le bas de la pyramide sociale. Les composants utilisés sont : machine asynchrone, alimentation sans interruption (UPS), alimentation de PC et d'autres équipements électroniques, etc. Ces composants recyclés peuvent être rassemblés pour former ainsi une solution technologique intéressante permettant de délivrer la puissance de sortie nécessaire. La deuxième partie de ce mémoire présente la modélisation de l'étage de puissance de la machine asynchrone triphasée utilisée comme un générateur asynchrone monophasé avec une phase d'excitation et les deux autres phases connectées en série pour alimenter la charge. Cette configuration est nommée 'Excited Induction Generator (EIG)'
Cambodia is a country located in Southeast Asia, with its high potential of renewable energy resource. Even if this country has a high potential for renewable, the installed power is still not high enough to cover the whole country. About 80% of population living in rural areas and 75% of the households live without electricity. They survive by using battery, diesel engine, candle, kerosene for lighting, TV, multimedia and some other household appliances. A few of residents in northern part of the country use pico-hydro power units bought from neighbor countries in order to electrify their houses. In these systems, the output voltage and frequency are not really stable while the load under load or speed variations. Consequently, the lifetime of household appliances could be reduced or the items damaged and local repairs are needed. Moreover, millions of Cambodian people cannot access neither take an advantage from the available energy resources due to two main factors: technology barriers and high investment cost. This research aims to remove technology barriers by designing simple systems for pico-hydro power generation with fast and simple installation, suitable for local applications with high quality of electrical supply. The first part of this work briefly describes the energy situation in rural areas of Cambodia where people are facing the lack of electrical supply which. They cannot neither improve their living standard nor develop their community. Rich villagers use car battery, solar PV applications, pico-hydro power while poor villagers use candle/kerosene for lighting. Local enterprises can provide renewable energy solutions but the prices are unaffordable and far from their expectations. Therefore, an original solution is proposed in this thesis by using wasted electric and electronic equipment (second-life components) to form the new power generation systems for remote rural areas. This is frugal innovation to serve the bottom of the social pyramid. The used components are: induction machine, Uninterrupted Power Supply (UPS), power supply of a computer and other electronic equipment, etc. These wasted components can be arranged together to form a good solution with an interesting output power. The second part of this thesis presents the modelling of the power stage of three-phase induction machine as a single-phase induction generator by using one phase for excitation while the other two phases are connected in series to supply load, named "Excited Induction Generator (EIG)". Capacitor banks are added to EIG for compensating the reactive power. Capacitor values influence poles and zeros locations which are described and analyzed in the root locus according to the parameter variations. The third part of this thesis is devoted to onsite modelling of losses in induction machine. The method should achieve results simply, rapidly, without any prior information on the machine, in order to further integrate this model into energy optimization algorithms. Design of experiments is a good candidate. Experimental models of the total loss (iron loss and rotor copper losses) are proposed for motor operation and generator mode for different machines of different powers. The last part of this thesis describes output voltage/current response for both simulation results and experimental results of the induction generators. Proportional-integral and proportional-resonant controllers are tested. The implementation of closed loop controller is first achieved in an analog circuit and then, with dSPACE/MATLAB Simulink environment

Orientador: Prof. Dr. Alfeu Joãzinho Sguarezi Filho
Coorientador: Prof. Dr. José Alberto Torrico Altuna
Tese (doutorado) - Universidade Federal do ABC. Programa de Pós-Graduação em Energia, Santo André, 2018.

Orientador: Prof. Dr. Alfeu J. Sguarezi Filho
Tese (doutorado) - Universidade Federal do ABC. Programa de Pós-Graduação em Energia, 2017.
Nesta pesquisa são propostos dois novos algoritmos de controle, operando a velocidade variável e robustos às variações nos parâmetros para um sistema eólico baseado no gerador de indução duplamente alimentado, cuja aplicação é realizada em condições normais de operação. Os controladores propostos são nomeados de Controle Direto de Potência (CDP) Deadbeat e do Controle Preditivo Generalizado com Horizonte Deslizante (CPG¿hd). O primeiro possui duas malhas de controle: uma para o desacoplamento do fluxo do estator e o controle das potências e a outra para o controle da corrente, essa malha é chamada de Deadbeat. O CDP calcula o vetor de tensão fornecido ao rotor a fim de garantir que a potência ativa e reativa atinjam seus valores de referência desejados. A dependência do algoritmo a parâmetros que tenham que ser sintonizados por meio de procedimentos heurísticos é nula quando é comparado com o controle Proporcional¿Integral ou Controle PI, sendo preciso somente calcular o coeficiente Gc. O segundo controlador, calcula os preditores para a corrente do rotor usando um horizonte de predição definido e assim obter as novas tensões do rotor que devem ser injetadas no sistema para controlar as potências ativa e reativa do estator com base nas equações do gerador. O CPG¿hd precisa de um parâmetro para sua sintonização chamado fator de peso do controlador, esse parâmetro faz parte da função de custo quadrática que deve ser minimizada, para obter um valor ótimo das tensões do rotor. Testes são feitos usando Matlab¿Simulink para os dois controladores operando sob condições normais de operação, ou seja: teste a velocidade fixa e teste a velocidade variável do rotor. Os mesmos testes são repetidos por meio de um protótipo de escala pequena disponível no LEPS . A dependência dos dois algoritmos às variações dos parâmetros foi também investigada, assim como a influência dos erros na estimativa desses parâmetros, obtendo-se um desempenho superior do controlador preditivo generalizado CPG¿hd sobre o CDP Deadbeat.
In this research two new control algorithms for a wind power system based on the Double Fed Induction Generator (DFIG) are proposed. The wind energy system is operating under normal conditions i.e. fixed rotor speed, variable rotor speed and under variations in DFIG parameters. The proposed controllers are named Direct Power Control (DPC) Deadbeat and Long¿range Generalized Predictive Control (GPC¿dq). The DPC calculates the sup- plied voltage vector to the rotor to ensure that the active and reactive power reaches their desired reference values. The algorithm dependence on parameters that have to be tuned by means of heuristic procedures is zero when its compared with the Proportional¿Integral (PI) Control, being necessary only estimate the Gc coeficient. The second controller evalu- ates the DFIG predictive rotor currents, using a defined long-range prediction horizon and thus obtain the new rotor voltages that have to be injected to controlling the active and reactive stator powers. The GPC¿dq needs a parameter for been tuned, this is called as a weighting factor and is a part of the quadratic cost function that has to be minimized, to obtain an optimal value of the rotor voltages. Tests are done using Matlab¿Simulink for the two controllers operating under normal operating conditions, ie: a fixed speed test and a variable rotor speed test. The same tests are repeated using a small scale prototype avai- lable in the LEPS. The dependence of the two algorithms on the parameter variations was also investigated, as well as the influence of the errors in the estimation of these parame- ters, obtaining a superior performance for the long¿range generalized predictive controller over the other one.

Orientador: Prof. Dr. Alfeu Joãozinho Sguarezi Filho
Dissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Engenharia Elétrica, 2015.
This research project presents the active and reactive power control of the Doubly Fed Induction Generator (DFIG) employing fuzzy logic for a wind power generation system, the proposed controller is a Fuzzy Logic Controller Takagi Sugeno type (TS FLC) which determines the rotor voltage by the rules base dened by a linear combination of the membership sets of the rotor current error, that reduces the complexity of the structure and consequently a lower computational cost and its easy to implement on a experimental set compared to other controllers such as Fuzzy Mamdani type. System control is accomplished using Stator Flux Field Oriented Control with Space Vector Modulation and computer simulation using mathematical models implemented in Matlab/Simulink. The results indicates that the FLC TS could be an interesting alternative to conventional controllers in the power control of the DFIG during normal operation conditions and under balanced voltage sags conditions.

Hybrid electric vehicles significantly reduce exhaust emissions and increase fuel economy. Power packs are the most fundamental components in a series powertrain configuration of a hybrid vehicle, which produce the necessary power to run the vehicle. The aim of this project is to design a compact power pack for a series hybrid vehicle, using virtual prototyping. The hybrid electric vehicle characteristics and configurations are analysed, followed by an explanation of the principles of induction machines. A new type of rotary induction machine with an outer rotor construction is designed to be coupled with the novel rotary internal combustion engine with rotating crankcase in order to form the compact power unit for the hybrid vehicle. The starting and generation performance of the designed machine is analysed by an electric machine simulator, called JMAG. ADVISOR software is studied and utilised to simulate the overall vehicle performance, employing different categories of power packs in the powertrain. Results show that the proposed compact power pack has the best performance in terms of fuel economy, emissions and battery charging compared to the existing power unit options. Over the city cycle, fuel economy is increased by up to 47 % with emission reduced by up to 36 % and over the highway cycle, fuel economy is increased by up to 69 % with emission reduced by up to 42 %.

The thesis focuses on constructing dynamic model - synchronous generator with using magnetic equivalent circuit diagrams. The model construction is based on knowledge of geometric parameters, magnetic characteristic of used material and fyzical deployment of vindings placed in stator slots. Computed reults are compared with results optained from model created with finite element method.

Tradicionalmente, la detección de faltas en máquinas eléctricas se basa en el uso de la Transformada Rápida de Fourier ya que la mayoría de las faltas pueden ser diagnosticadas con ella con seguridad si las máquinas operan en condiciones de régimen estacionario durante un intervalo de tiempo razonable. Sin embargo, para aplicaciones en las que las máquinas operan en condiciones de carga y velocidad fluctuantes (condiciones no estacionarias) como por ejemplo los aerogeneradores, el uso de la Transformada Rápida de Fourier debe ser reemplazado por otras técnicas. La presente tesis desarrolla una nueva metodología para el diagnóstico de máquinas de inducción de rotor de jaula y rotor bobinado operando en condiciones no estacionarias, basada en el análisis de las componentes de falta de las corrientes en el plano deslizamiento frecuencia. La técnica es aplicada al diagnóstico de asimetrías estatóricas, rotóricas y también para la falta de excentricidad mixta. El diagnóstico de las máquinas eléctricas en el dominio deslizamiento-frecuencia confiere un carácter universal a la metodología ya que puede diagnosticar máquinas eléctricas independientemente de sus características, del modo en el que la velocidad de la máquina varía y de su modo de funcionamiento (motor o generador). El desarrollo de la metodología conlleva las siguientes etapas: (i) Caracterización de las evoluciones de las componentes de falta de asimetría estatórica, rotórica y excentricidad mixta para las máquinas de inducción de rotores de jaula y bobinados en función de la velocidad (deslizamiento) y la frecuencia de alimentación de la red a la que está conectada la máquina. (ii) Debido a la importancia del procesado de la señal, se realiza una introducción a los conceptos básicos del procesado de señal antes de centrarse en las técnicas actuales de procesado de señal para el diagnóstico de máquinas eléctricas. (iii) La extracción de las componentes de falta se lleva a cabo a través de tres técnicas de filtrado diferentes: filtros basados en la Transformada Discreta Wavelet, en la Transformada Wavelet Packet y con una nueva técnica de filtrado propuesta en esta tesis, el Filtrado Espectral. Las dos primeras técnicas de filtrado extraen las componentes de falta en el dominio del tiempo mientras que la nueva técnica de filtrado realiza la extracción en el dominio de la frecuencia. (iv) La extracción de las componentes de falta, en algunos casos, conlleva el desplazamiento de la frecuencia de las componentes de falta. El desplazamiento de la frecuencia se realiza a través de dos técnicas: el Teorema del Desplazamiento de la Frecuencia y la Transformada Hilbert. (v) A diferencia de otras técnicas ya desarrolladas, la metodología propuesta no se basa exclusivamente en el cálculo de la energía de la componente de falta sino que también estudia la evolución de la frecuencia instantánea de ellas, calculándola a través de dos técnicas diferentes (la Transformada Hilbert y el operador Teager-Kaiser), frente al deslizamiento. La representación de la frecuencia instantánea frente al deslizamiento elimina la posibilidad de diagnósticos falsos positivos mejorando la precisión y la calidad del diagnóstico. Además, la representación de la frecuencia instantánea frente al deslizamiento permite realizar diagnósticos cualitativos que son rápidos y requieren bajos requisitos computacionales. (vi) Finalmente, debido a la importancia de la automatización de los procesos industriales y para evitar la posible divergencia presente en el diagnóstico cualitativo, tres parámetros objetivos de diagnóstico son desarrollados: el parámetro de la energía, el coeficiente de similitud y los parámetros de regresión. El parámetro de la energía cuantifica la severidad de la falta según su valor y es calculado en el dominio del tiempo y en el dominio de la frecuencia (consecuencia de la extracción de las componentes de falta en el dominio de la frecuencia). El coeficiente de similitud y los parámetros de regresión son parámetros objetivos que permiten descartar diagnósticos falsos positivos aumentando la robustez de la metodología propuesta. La metodología de diagnóstico propuesta se valida experimentalmente para las faltas de asimetría estatórica y rotórica y para el fallo de excentricidad mixta en máquinas de inducción de rotor de jaula y rotor bobinado alimentadas desde la red eléctrica y desde convertidores de frecuencia en condiciones no estacionarias estocásticas.
Vedreño Santos, FJ. (2013). Diagnosis of electric induction machines in non-stationary regimes working in randomly changing conditions [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/34177
TESIS

Orientador: Prof. Dr. Alfeu Joãozinho Sguarezi Filho
Dissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Engenharia Elétrica, 2015.
Inicialmente, este trabalho apresenta aspectos de viabilidade e técnicos para a construção de sistemas de geração eólicos. Nele é disposto uma breve literatura de alguns dos conversores elétricos utilizados para diferentes tipos de geradores. Por fim, este trabalho propõe um método de ajuste de ganhos dos controladores proporcionais-integrais através do emprego do método por compensação de polos da função de transferência do sistema em malha fechada, para o conversor do lado do rotor, com objetivo de garantir controle estável do fluxo das potências ativa e reativa de estator do GIRB. Também, serão apresentadas as malhas de controle do conversor conectado à rede elétrica. Resultados obtidos através de simulação computacional deste sistema de controle são apresentados para validar a proposta.
This work includes feasibility and technical aspects for the construction of wind generation systems. In it, there is disposed a brief literature some electrical converters used for different types of generators. It also presents a design method for the gains of the proportional-integral controllers used in power vector control of DFIG connected to the grid in wind power generation systems where GIRB is connected directly to the power grid and its rotor through a converter called "back to back". The rotor controllers will be adjusted with the use of the method for compensating poles of the system's transfer function in closed loop. Also, the converter control loops connected to the grid will be displayed. Results from computer simulation of this control system are presented to validate the proposal.

The number of large-scale wind farms integrated to the power system in Sweden is increasing. Two generator concepts that are widely used are Doubly-Fed Induction Generators (DFIG) and Full Power Converters (FPC). The study is of a quantitative character and the aim of the Master thesis is to compare DFIG-models with FPC-models integrated in an area with high concentration of hydropower. Then it is possible to examine how the dynamics in the power system change depending on the selection of technology (DFIG or FPC) when connecting a wind farm. The power system is simulated during a summer night, i.e., a low load is connected. The Master thesis covers stability analysis of the power system by using rotor angle stability that are split into small-signal stability and transient stability (time-domain simulations) and finally voltage stability to see how the hydropower generators react when varying the power production in the wind farm. The Master thesis concludes that independently of wind turbine technique, integration of a wind farm has slight impact on the stability in the power system compared to a power system without a wind farm, even though the load is low. Further, an integration of a wind farms affects the reactive power production in neighbouring hydropower plants. Finally, when increasing the size of the wind farm the neighbouring hydropower station consume less reactive power which can induce problem with the voltage stability.

Traditionnellement, les éoliennes fonctionnaient de manière à extraire le maximum d’énergie du vent dans différentes conditions de fonctionnement. Par conséquent, les éoliennes ont été conçues pour fonctionner en mode connecté au réseau ou en mode autonome. En outre, les innovations récentes dans les micro-réseaux ont suscité l’intérêt pour le fonctionnement autonome de l’éolienne, dans le cadre de réseaux isolés, ou pour les générateurs distribués dans les réseaux faibles.Un autre domaine d’application intéressant concerne les parcs éoliens offshores connectés au réseau via une liaison à courant continu haute tension (HVDC). Dans ces systèmes, le parc éolien offshore est isolé du réseau. Alors que, dans la technologie à convertisseur de tension (VSC) -HVDC, la tension du parc éolien est fournie par le redresseur VSC, si un redresseur HVDC à convertisseur de ligne est utilisé, la tension doit être générée par les éoliennes, qui fonctionnent maintenant de manière isolée.Contrairement aux modes connectés au réseau, une éolienne en fonctionnement autonome et en îlot doit imposer et maintenir une tension et une fréquence tout en faisant correspondre la production et la charge, malgré les variations de la vitesse du rotor dues aux variations de la vitesse du vent et des charges. Lorsque la génération dépasse les charges demandées, elle doit être réduite en contrôlant l'angle de pas des pales. D'autre part, si la génération n'est pas suffisante pour alimenter les charges, le mécanisme de délestage doit être utilisé. Ainsi, les exigences de fonctionnement autonome impliquent que les éoliennes doivent avoir un contrôle actif de la puissance via un contrôle aérodynamique et un contrôle des convertisseurs électroniques de puissance. Les technologies d'éoliennes qui répondent à ces exigences sont celles basées sur des générateurs à vitesse variable et le contrôle du tangage. De nos jours, parmi ces technologies, les GADA ont été utilisés comme la meilleure option. La GADA a plus de liberté pour contrôler les deux convertisseurs. Le contrôle du convertisseur côté grille (GSC) permet de réguler la tension du bus CC et le convertisseur du côté rotor (RSC) commande la machine.Dans cette thèse, la commande du DFIG fournissant une charge isolée est présentée. De plus, le système de contrôle vectoriel (FOC) est utilisé pour fournir une tension et une fréquence constantes du GADA en fonctionnement autonome lorsque les variations de la charge et de la vitesse du rotor sont très fiables et robustes
Traditionally, wind turbines have been operated to extract maximum energy output from wind under different operating conditions. Therefore, wind turbines have been designed to work either in the grid connected mode or stand-alone mode. In addition, recent innovations in micro-grids have aroused the interest in the stand-alone operation of the wind turbine, as part of isolated grids, or the distributed generators in weak networks.Furthermore, another interesting application of the wind energy system is the offshore wind farms grid connected via a High-Voltage Direct Current (HVdc) link. In these applications, the offshore wind farm is isolated from the grid. Whereas in Voltage-Sourced Converter (VSC)-HVdc technology the wind farm voltage is supplied by the VSC rectifier, if a line-commutated converter HVdc rectifier is utilized, the voltage must be generated by the wind turbine generators, which are now operating in the isolated grid.Unlike in grid-connected modes, a wind turbine in stand-alone and islanding operation must impose and maintain voltage and frequency while matching generation and load, even with varying rotor speed and loads variations. When generation exceeds the demanded loads, generation must be reduced by controlling the pitch angle of blades. Besides, the load shedding mechanism should be used if the generation is not enough to supply the loads. Thus, stand-alone operation requirements must have active power control through power electronic converters control. The wind turbine technologies that meet these requirements are those based on variable speed generators and pitch control. Nowadays, among these technologies, DFIGs has been used as the best option. The DFIG has more freedom to control the two converters. Grid Side Converter (GSC) control to regulate the DC bus voltage and the Rotor Side Converter (RSC) controls the machine.In this thesis, the control of the DFIG supplying an isolated load is presented. Moreover, Field Oriented Control (FOC) Vector Control (VC) scheme is used to provide constant voltage and frequency of the DFIG in stand-alone operation when variations in both load and rotor speed in a very reliable and robust way

With the growth of power system interconnections, the economic drivers encourage the electric companies to load the transmission lines near their limits, therefore it is critical to know those limits well. One important limiting issue is the damping of inter-area oscillation (IAO) between groups of synchronous machines. In this Ph.D. thesis, the contribution of power system components such as load and static var compensators (SVC) that affect the IAO of the power system, are analysed. The original contributions of this thesis are as follows: 1-Identification of eigenvalues and mode shapes of the IAO: In the first contribution of this thesis, the eigenvalues of the IAO are identified using a correlation based method. Then, the mode shape at each identified resonant frequency is determined to show how the synchronous generators swing against each other at the specific resonant frequencies. 2-Load modelling and load contribution to damping: The first part of this contribution lies in identification of the load model using cross-correlation and autocorrelation functions . The second aspect is the quantification of the load contribution to damping and sensitivity of system eigenvalues with respect to the load. 3- SVC contribution to damping: In this contribution the criteria for SVC controller redesign based on complete testing is developed. Then the effect of the SVC reactive power on the measured power is investigated. All of the contributions of this thesis are validated by simulation on test systems. In addition, there are some specific application of the developed methods to real data to find a.) the mode shape of the Australian electricity network, b.) the contribution of the Brisbane feeder load to damping and c.) the effect of the SVC reactive power of the Blackwall substations on the active power supplying Brisbane.

Documentos apresentados no âmbito do reconhecimento de graus e diplomas estrangeiros
Induction machines are one the most important electrical equipment in industrial plants and manufacturers. They have a great variety of features, structures and performance. So, proper and secure protection design and fault detection are important issues. The induction machines are divided into two categories as squirrel-cage and wound-rotor types. Due to many advantages of squirrel cage motors (e.g. simplicity, lower cost, less maintenance and etc.) they are the most common choice for industries. However, wound rotor induction motors have their own applications, where they have high start-up torque for industries such as hoist, cement and steel ones. According to the fault destructive effects on induction motors, fault detection and the related region identification in early stages are the most important protection criteria. In this thesis, monitoring of the air-gap flux and measuring the rotational magnetic field distortion and asymmetricity caused by stator or rotor Turnto-Turn fault is regarded as the main parameter to detect such faults. To achieve such aim, some simple flux sensors are installed in the specified stator slots, so that each phase equipped by two flux sensors aligned with the magnetic axis of the related coils. In motor healthy condition, passing fluxes from the corresponding sensors are equal, which results in the identical induced voltages in them and then difference of them (i.e. Δ ) is equal to zero. In case of stator or rotor winding Turn-to-Turn fault, Δ will no longer be zero due to rotational magnetic field distortion and such phenomenon is the main criterion to detect the faulty condition and discriminate the stator or rotor winding faults, in this thesis. To demonstrate the capability of this method, not only the simulation results but also the experimental test results have been used. The ability to detect and discriminate rotor and stator winding Turn-to-Turn fault, faulty phase detection in the cases of stator faults, low processing burden and high sensitivity in the face of permissible voltage unbalance and mechanical load variation are the undeniable advantages of this method, which can be pointed out.

碩士
國立臺灣大學
電機工程學研究所
104
Design of rotor side current regulator of a doubly-fed induction generator (DFIG) connected to a power system is investigated in this thesis. In conventional design of the decoupled direct-axis and quadrature-axis current regulators for the rotor side converter of a DFIG, the derivative of the stator flux was usually neglected. In this thesis, a new feedforward compensator and a new proportional-integral (PI) regulator are derived by taking the derivative of the stator flux into account. By using the new rotor-side feedforward compensator and the new PI regulator, the dynamic responses of the generator subject to wind speed change and different voltage dips are studied. The MATLAB/Simulink simulation software is used to simulate the dynamic performance of the grid-connected DFIG. The control parameters of the rotor-side PI regulator were designed by using pole-zero cancellation. The simulation results indicate that the proposed compensator and PI regulator offer better dynamic responses than the conventional current regulator neglecting stator flux transient when the DFIG is subjected to wind speed change and different voltage dips.

碩士
國立臺北科技大學
電機工程系研究所
98
Currently, most of Doubly-Fed Induction Generators(DFIGs) were controlled by the rotor voltage commands. This thesis directly inputs rotor current commands to control the real and imaginery powers of DFIGs. First, the vector control principle is used to develop the real power、imaginery power and capacitor voltage controls. In order to effectively control DFIGs, the model of DFIGs are transformed from the a-b-c frame to the d-q axis frame. Then both the PI linear control and Backstepping nonlinear control theories are adopted to realize the control of the real and imaginery powers. The PSCAD/EMTDC and Matlab/Simulink are used to simulate and verified the proposed PI control and Backstepping nonlinear control respectively. Meanwhile, the PSCAD/EMTDC and Matlab/Simulink are compared in the simulation chapter. The results confirm the performances of the proposed real power、imaginery power and capacitor voltage controllers

Student Number : 0004041J - MSc dissertation - School of Electrical and Information Engineering - Faculty of Engineering
Slip energy recovery (SER) drives are used extensively in industry as they offer cost effective speed control of large wound rotor induction motors. The biggest disadvantage associated with the use of SER drives is the vulnerability of the rotor circuit converters to power system disturbances such as voltage dips. The failure of converters as a result of voltage dips is a problem associated with the use of these particular drives. The aim of this research is to better understand the stresses on rotor circuit converters as a result of voltage dips at the terminals of the motor. The rotor transients developed by a wound rotor induction motor are investigated for a range of three phase and single phase voltage dips. Simulations conducted in the Alternative Transients Program (ATP) supplement measurements conducted on a simplified SER circuit. The results confirm that voltage dips cause significant stresses on the converters in the rotor circuit. Good correlation was obtained between simulated and measured results. This work allows for a better understanding of the response of wound rotor induction motors to voltage dips and identifies the threat that voltage dips impose on the SER rotor circuit converters.

abstract: An advantage of doubly fed induction generators (DFIGs) as compared to conventional fixed speed wind turbine generators is higher efficiency. This higher efficiency is achieved due to the ability of the DFIG to operate near its optimal turbine efficiency over a wider range of wind speeds through variable speed operation. This is achieved through the application of a back-to-back converter that tightly controls the rotor current and allows for asynchronous operation. In doing so, however, the power electronic converter effectively decouples the inertia of the turbine from the system. Hence, with the increase in penetration of DFIG based wind farms, the effective inertia of the system will be reduced. With this assertion, the present study is aimed at identifying the systematic approach to pinpoint the impact of increased penetration of DFIGs on a large realistic system. The techniques proposed in this work are tested on a large test system representing the Midwestern portion of the U.S. Interconnection. The electromechanical modes that are both detrimentally and beneficially affected by the change in inertia are identified. The combination of small-signal stability analysis coupled with the large disturbance analysis of exciting the mode identified is found to provide a detailed picture of the impact on the system. The work is extended to develop suitable control strategies to mitigate the impact of significant DFIG penetration on a large power system. Supplementary control is developed for the DFIG power converters such that the effective inertia contributed by these wind generators to the system is increased. Results obtained on the large realistic power system indicate that the frequency nadir following a large power impact is effectively improved with the proposed control strategy. The proposed control is also validated against sudden wind speed changes in the form of wind gusts and wind ramps. The beneficial impact in terms of damping power system oscillations is observed, which is validated by eigenvalue analysis. Another control mechanism is developed aiming at designing the power system stabilizer (PSS) for a DFIG similar to the PSS of synchronous machines. Although both the supplementary control strategies serve the purpose of improving the damping of the mode with detrimental impact, better damping performance is observed when the DFIG is equipped with both the controllers.
Dissertation/Thesis
Ph.D. Electrical Engineering 2010