Orientador: Prof. Dr. Edmarcio Antonio Belati / Dissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Engenharia Elétrica, 2015. / Este trabalho visa à operação ótima de um sistema de energia elétrica com a presença de aerogeradores. Considerando as injeções de potência ativa e reativa para a geração eólica, será analisado o comportamento da rede por meio de um Fluxo de Potência Ótimo Multiobjetivo (FPO - MO). A metodologia consiste na modelagem da rede elétrica, inserindo as características do gerador eólico na formulação do FPO - MO, objetivando minimizar as perdas ativas em conjunto com o perfil de tensão por meio do despacho ótimo de potência ativa e reativa. O problema modelado como um FPO - MO reativo é resolvido com auxilio do AMPL (Modeling Language for Mathematical Programming) e do solver Knitro. Estudos realizados com os sistemas IEEE de 14, 30, 57 e 118 barras evidenciam os benefícios da utilização da geração eólica aliada ao FPO - MO. / This approach aims optimal operation of power system with wind turbines. Considering the active and reactive power injections for wind generation, network behavior is analyzed using a multi-objective Optimal Power Flow (OPF - MO). The methodology consists in modeling the electrical network by entering characteristics of wind generator in the formulation of the FPO - MO, aiming to minimize active power losses in conjunction with the voltage profile through the optimal dispatch of active and reactive power. The problem modeled as a FPO - MO reactive is solved with the aid of AMPL (Modeling Language for Mathematical Programming) and Knitro solver. Studies with the IEEE 14, 30, 57 and 118 modified system show the benefits of using wind power combined with the FPO - MO.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This dissertation addresses the analysis and control of permanent magnet synchronous generators (PMSG) found in wind energy conversion system. The operation modes of the wind turbine the current and voltage constraints of a PWM rectifier are defined and a methodology to determine the generator current is presented. The generator currents obtained guarantee the maximization of wind energy extraction as well as the minimization of the PMSG and rectifier losses. In addition, a space-vector modulation technique in overmodulation region is reviewed in detail and applied aiming: (i) to maximize the generator power; (ii) to utilize the entire PWM rectifier DC link voltage resource, and (iii) to obtain a smooth transition to six-step operation. Furthermore, a single current controller is designed for all operating modes being capable to avoid the controller states overload as well as the undesired effects due to the operation in the overmodulation region. The stability analysis of the closed loop system is investigated by means of linear matrix inequality conditions to estimate a region of operation with guaranteed stability. Simulation results are presented to demonstrate the performance of the proposed system. / Esta dissertação trata da análise e do controle de geradores sincronos a íımã permanente usados em sistema de conversão de energia eólica. Os modos de operação da turbina eólica sob restrição de tensão e corrente são definidos e uma metodologia para determinar as correntes do gerador ´e apresentada. As correntes obtidas do gerador garantem a maximização da potência extraída do vento bem como a minimização das perdas do conjunto gerador e retificador PWM. Além disso, a técnica de modulação vetorial na região de sobremodulação é revisada em detalhes e aplicada com objetivo de: (i) maximizar a potência do gerador, (ii) utilizar todo o recurso do barramento CC disponível pelo retificador PWM e (iii) obter uma transição suave para operação do retificador para o modo de seis-pulsos. Uma técnica de controle vetorial é apresentada e comparada. Um único controlador de corrente é projetado para todos os modos operacionais, sendo capaz de evitar tanto sobrecarga dos estados do controlador quanto os efeitos indesejáveis provenientes da operação na região de sobremodulação. A análise da estabilidade do sistema em malha fechada é investigada por meio de desigualdades matriciais lineares para determinar uma região de estabilidade garantida. Por fim, resultados de simulação são apresentados para demonstrar o bom desempenho do sistema proposto.

O presente trabalho apresenta uma metodologia de simulação numérica de perfis aerodinâmicos bidimensionais com foco na utilização para o projeto e otimização de pás e rotores de pequenas turbinas eólicas de eixo horizontal, bem como o emprego desses métodos em simulações nas quais efeitos de alta solidez do rotor e baixos números de Reynolds são avaliados. Essa metodologia inclui geração de malhas, seleção de métodos numéricos e validação, tendo as escolhas sido guiadas pelas práticas mais bem sucedidas na simulação de perfis aerodinâmicos, e foi aplicada na simulação dos aerofólios NACA 0012, S809 e SD7062. O código comercial ANSYS Fluent foi utilizado em todas as simulações. Na simulação de aerofólios isolados a altos números de Reynolds dos perfis NACA 0012 e S809, o modelo Transition SST (γ-Reθ) apresentou resultados mais próximos a dados experimentais do que aqueles apresentados pelo modelo k-ω SST para CL e CD, além de produzir resultados para CP que mostraram boa precisão quando comparados aos mesmos dados experimentais. Resultados de CL, CD, CF e CP são apresentados para 20 diferentes condições de operação às quais o perfil SD7062 foi submetido, com números de Reynolds variando entre 25.000 e 125.000. As distribuições dos dois últimos coeficientes sobre os dorsos do aerofólio evidenciam com clareza a presença e magnitude da bolha de separação laminar. Os coeficientes de sustentação e arrasto mostram o impacto negativo da presença da bolha nessa faixa de números de Reynolds. Além disso, nos casos simulados, o arrasto aumenta em função da diminuição do Re. Um design de pá produzido com o auxílio do código de otimização SWRDC, baseado em algoritmos genéticos, é apresentado. Três seções ao longo da envergadura dessa pá foram simuladas em uma bateria de 45 simulações, sob diversas condições de operação em função de solidez, ângulo de ataque e razão de velocidade de ponta de pá. Esses resultados mostram que a bolha de separação laminar se move na direção do bordo de ataque com o aumento da solidez, do ângulo de ataque e da TSR. Além disso, distribuições do CP mostram aumento de pressão em ambos os dorsos do perfil quando submetido aos efeitos da solidez, embora esses efeitos tenham sido responsáveis por um aumento na relação CL/CD nos casos estudados. / This thesis presents a methodology of two-dimensional airfoil simulation focusing on its application on the design and optimization of blades and rotors of small horizontal axis wind turbines, and its application in a set of numerical simulations involving high rotor solidity and low-Re effects. This methodology includes grid generation, selection of numerical methods and validation, reflecting the most successful practices in airfoil simulation, and was applied in the simulation of the NACA 0012, S809 and SD7062 airfoils. The ANSYS Fluent commercial code was used in all simulations. Results for the isolated NACA 0012 and S809 airfoils at high Reynolds numbers show that the Transition SST (γ-Reθ) turbulence model produces results closer to experimental data than those yielded by the SST k-ω model for CL and CD, having also produced CP plots that show good agreement to the same experimental data. Plots of CL, CD, CF and CP for the SD7062 airfoil are presented, for simulations at 20 different operating conditions. The CF and CP distributions evidence the negative impact of the laminar separation bubble in the range of Reynolds numbers evaluated. Results show that, for Re between 25,000 and 125,000, drag increases with decreasing Re. A blade design generated using the SWRDC optimization code, based on genetic algorithms, is presented. Three sections of the resulting blade shape were selected and were tested in a set of 45 simulations, under an array of operating conditions defined by solidity, angle of attack and TSR. Results show that the laminar separation bubble moves towards the leading edge with increasing solidity, angle of attack and TSR. Furthermore, CP plots show an increase in pressure on both surfaces when the airfoil is subject to solidity effects, although these effects show an increase in the lift-to-drag ratio at the conditions evaluated.

Submitted by Irene Nascimento (irene.kessia@ufpe.br) on 2016-09-28T18:48:45Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Controle de Turbinas Eólicas_Eduardo_Menezes.pdf: 2248110 bytes, checksum: b04563e9c8a7cc3ae7a8af844c3aa9c7 (MD5) / Made available in DSpace on 2016-09-28T18:48:45Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Controle de Turbinas Eólicas_Eduardo_Menezes.pdf: 2248110 bytes, checksum: b04563e9c8a7cc3ae7a8af844c3aa9c7 (MD5) Previous issue date: 2016-02-29 / CNPQ / As turbinas eólicas são as máquinas responsáveis pela conversão de energia a partir de uma fonte primária profundamente irregular e variável, o vento. Para extrair energia do vento e transformá-la em energia elétrica de maneira eficiente e segura, os sistemas de controle são componentes essenciais das turbinas eólicas. Eles são responsáveis por regular velocidade e/ou potência e por reduzir as cargas mecânicas e as vibrações na estrutura. O crescente tamanho das atuais turbinas eólicas, que constituem estruturas de grande porte e cada vez mais flexíveis, faz com que a interação da dinâmica estrutural com os sistemas de controle se torne uma questão fundamental. O controle de pitch é utilizado para mitigar as cargas mecânicas e controlar a potência. Os sistemas de controle utilizados como padrão na indústria eólica são sistemas de uma entrada-uma saída (single-input, single-output, SISO). Sistemas avançados de múltiplas entradas e múltiplas saídas (multiple-input, multiple-output, MIMO) baseados no método de espaço de estados e no Controle por Acomodação de Distúrbios (DAC) podem melhorar a performance e resolver alguns problemas de instabilidade dinâmica que surgem com os sistemas de controle padrão. O uso de sistemas de controle avançados foi proposto e testado em trabalhos anteriores para uma turbina de médio porte, a CART-750kW, e bons resultados foram obtidos. No entanto, a mesma metodologia ainda não foi testada em turbinas de grande porte. Neste trabalho, a metodologia MIMO em espaço de estados é aplicada à turbina de grande porte NREL 5 MW, com o objetivo de controle estável de velocidade na Região 3 e de mitigação de cargas mecânicas através da adição de amortecimento ativo aos modos estruturais. Foram implantados e simulados os sistemas de controle padrão e avançados para esta turbina. Assim, é possível analisar a evolução da performance que os sistemas de controle avançados proporcionam em turbinas de grande porte e avaliar as diferenças entre as turbinas de médio porte (CART -750kW) e de grande porte (NREL 5 MW). / Wind turbines are the machines that extract energy from the wind, a primary source deeply irregular and variable. Control systems are essential for extracting wind energy and transforming it into electrical energy in a efficient and safe manner. They are responsible for regulating speed/power and reducing mechanical loads/vibrations on the structure. The increasing size of wind turbines, which are becoming large-scale and flexible structures, makes the interaction of control systems and structural dynamics a main concern. The pitch control is used to mitigate mechanical loads and to regulate power. The standard control systems used in the wind industry are single-input, single-output control systems (SISO). Advanced multipleinput, multiple-output systems (MIMO) using state-space techniques and Disturbance Accomodating Control (DAC) can improve performance and solve some problems of dynamic instability of standard control systems. The use of advanced control systems was proposed and tested in previous works for a medium-scale turbine, CART-750kW, and good results were obtained. However, the same methodology has not yet been tested in large-scale turbines. In this work, MIMO control systems are applied to the large-scale turbine NREL 5 MW, with the goal of stable speed control in Region 3 and mitigation of mechanical loads by adding active damping to the structural modes. Standard and advanced control systems were implemented and simulated. Thus, it is possible to analyze the evolution of performance provided by advanced control systems in large-scale turbines and evaluate the differences between mediumscale turbines (CART -750kW) and large-scale (NREL 5 MW).

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The constant human need for electricity, as well as the increasing demand for energy causes the use of finite sources, as oil and coal. The search for alternative energy sources as wind harvesting is the motivation for this master dissertation. Wind energy is a consolidated technology, mostly based on three blades wind turbine. This master thesis constitutes an analysis of a non-conventional wind machine, named Magnus wind turbine. The turbine s operation is based on the Magnus effect and its difference with respect to the traditional type is that it has rotating cylinders instead of fixed blades, which benefits an increase of generated power, since this turbine can produce power from low wind speeds. A method to track the maximum power point based on the control of the cylinders rotation is proposed, whereas in literature only fixed values were found for this variable. This Magnus turbine is used to drive a permanent magnet synchronous generator as a way to prove the theoretical predictions. The electrical generator also uses a specific method to track the maximum power point for the whole set. Simulated and practical results are demonstrating the performance of the Magnus wind turbine driving a permanent magnet synchronous generator. / A constante necessidade de energia elétrica, assim como o aumento de demanda, implica no uso de fontes de energia que são finitas, como o petróleo e o carvão. A busca por fontes alternativas de energia como a eólica é a motivação para este trabalho, também por a energia eólica ser uma tecnologia já consolidada, utilizando principalmente turbinas de três pás para a geração de energia. Esta dissertação trata da análise de uma turbina eólica não convencional, conhecida como turbina eólica Magnus para acionamento de geradores elétricos. A operação desta turbina é baseada no efeito Magnus e seu grande diferencial é que ao invés de pás fixas possui cilindros giratórios que ajudam no incremento de potência, já que a turbina pode produzir potência mesmo com baixas velocidades de vento. Um método de rastreamento de máxima potência é proposto baseando no controle da velocidade de rotação dos cilindros, já que na literatura são considerados apenas valores fixos para esta variável. A turbina Magnus é acoplada a um gerador síncrono a imã permanente, como forma de demonstração da precisão do método proposto na determinação do seu ponto de máxima potência. Paralelo a isto, o gerador também utiliza um método de rastreamento de máxima potência para que o conjunto inteiro trabalhe no ponto de máxima potência. Os resultados de simulação e práticos são apresentados para demonstrar o desempenho da turbina Magnus acoplada a um gerador síncrono a imã permanente.

Abstract<p><p>This thesis deals with the operation of and winding short-circuit fault detection in a Doubly-Fed Induction Generator (DFIG) based Wind Turbine Generator System (WTGS). Both the faulted and faultless condition of operation has been studied, where the focus is on the electrical part of the system. The modelled electrical system is first simulated and the developed control system is then validated on a test bench. The test-bench component dimensioning is also discussed.<p><p>The faultless condition deals with the start-up and power production mode of operation. Control design based on the Proportional Integral (PI) control technique has been compared for power and torque control strategies against the Linear Quadratic Gaussian (LQG) control technique, at different operating points through the variable-speed region of WTGS operation following the maximum power curve of the system. It was found that the torque control strategy offered less degradation in performance for both the control techniques at operating points different for the one for which the control system was tuned. The start-up procedure of the DFIG based WTGS has been clarified and simplified. The phase difference between the stator and the grid voltage, which occurs due to the arbitrary rotor position when the rotor current control is activated, is minimized by using a sample-and-hold technique which eliminates the requirement of designing an additional controller. This method has been validated both in simulation and experiments.<p><p>The faulted condition of operation deals with the turn-turn short-circuit fault in the phase winding of the generator. The model of the generator, implemented using the winding-function approach, allows the fault to be created online both in a stator and a rotor phase. It has been demonstrated that the magnitude of the current harmonics, used extensively in literature for the Machine Current Signature Analysis (MCSA) technique for winding short-circuit fault detection, is very different when the location of the fault is changed to another coil within the phase winding. This makes the decision on the threshold selection for alarm generation difficult. Furthermore, the control system attenuates the current harmonics by an order of magnitude. This attenuation property is also demonstrated through experiments. The attention is then shifted to the negative-sequence current component, resulting from the winding unbalance, as a possible fault residual. Its suitability is tested in the presence of noise for scenarios with different fault locations, fault severity in terms of the number of shorted-turns and grid voltage unbalance. It is found that due to the presence of a control system the magnitude of the negative-sequence current, resulting from the fault, remains almost the same for all fault locations and fault severity. Thus, it was deemed more suitable as a fault residual. In order to obtain a fast detection method, the Cumulative Sum (CUSUM) algorithm was used. The test function is compared against a threshold, determined on the basis of expected residual magnitude and the time selected for detection, to generate an alarm. The validation is carried out with noise characteristics different from the ones used during the design and it is shown that the voltage unbalance alone is not able to trigger a false alarm. In all the scenarios considered, the detection was achieved within 40 ms despite the presence of measurement filters. / Doctorat en Sciences de l'ingénieur / info:eu-repo/semantics/nonPublished

Among the renewable energies, wind energy presents the highest growth in installed capacity and penetration in modern power systems. This is why reliability of wind turbines becomes an important topic in research and industry. To this end, condition monitoring (or health monitoring) systems are needed for wind turbines. The core of any condition monitoring system (CMS) are fault diagnosis algorithms whose task is to provide early warnings upon the occurrence of incipient (small magnitude) faults. Thanks to the use of CMS we can avoid premature breakdowns and reduce significatively maintenance costs.<p><p>The present thesis deals with fault diagnosis in sensors of a doubly-fed induction generator (DFIG) for wind turbine (WT) applications. In particular we are interested in performing fault detection and isolation (FDI) of incipient faults affecting the measurements of the three-phase signals (currents and voltages) in a controlled DFIG. Although different authors have dealt with FDI for sensors in induction machines and in DFIGs, most of them rely on the machine model with<p>constant parameters. However, the parameter uncertainties due to changes in the operating conditions will produce degradation in the performance of such FDI systems.<p><p>In this work we propose a systematic methodology for the design of sensor FDI systems with the following characteristics: i) capable of detecting and isolating incipient additive (bias, drifts) and multiplicative (changes in the sensor<p>gain) faults, ii) robust against changes in the references/disturbances affecting the controlled DFIG as well as modelling/parametric uncertainties, iii) residual generation system based on a multi-observer strategy to enhance the isolation process, iv) decision system based on statistical-change detection algorithms to treat the entire residual and perform fault detection and isolation at once.<p><p>Three novel sensor FDI approaches are proposed. The first is a signal-based approach, that uses the model of the balanced three-phase signals (currents or voltages) for residual generation purposes. The second is a model-based approach<p>that accounts for variation in the parameters. Finally, a third approach that combines the benefits of both the signal- and the model-based approaches is proposed. The designed sensor FDI systems have been validated using measured voltages, as well as simulated data from a controlled DFIG and a speed-controlled induction<p>motor. <p><p>In addition, in this work we propose a discrete-time multiple input multiple output (MIMO) regulator for each power converter, namely for the rotor side converter (RSC) and for the grid side converter (GSC). In particular, for RSC<p>control, we propose a modified feedback linearization technique to obtain a linear time invariant (LTI) model dynamics for the compensated DFIG. The novelty of this approach is that the compensation does not depend on highly uncertain parameters such as the rotor resistance. For GSC control, a LTI model dynamics<p>is derived using the ideas behind feedback linearization. The obtained LTI model dynamics are used to design Linear Quadratic Gaussian (LQG) regulators. A single design is needed for all the possible operating conditions. / Doctorat en Sciences de l'ingénieur / info:eu-repo/semantics/nonPublished

Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2016-04-13T12:14:28Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Henrique Azevedo - Tese de Mestrado - Finalizada_Rev13_Hen_Alex_Nad_Rob_ABNT_Gus_Bib-1.pdf: 2536238 bytes, checksum: 092410d49ebfec82ff6f89b7a23f93e3 (MD5) / Made available in DSpace on 2016-04-13T12:14:28Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Henrique Azevedo - Tese de Mestrado - Finalizada_Rev13_Hen_Alex_Nad_Rob_ABNT_Gus_Bib-1.pdf: 2536238 bytes, checksum: 092410d49ebfec82ff6f89b7a23f93e3 (MD5) Previous issue date: 2015-08-28 / Desde a década de 1980, a tecnologia de energia eólica sofreu um imenso crescimento em relação tanto ao tamanho da turbina quanto à capacidade instalada a nível mundial. Como a demanda por turbinas eólicas de grande escala e de custo mais baixos de operação e manutenção continua a crescer, o interesse nos sistemas de monitoramento de condição (CMS, do inglês Condition Monitoring System) tem aumentado rapidamente. Os principais componentes (MC, do inglês Main Components) das turbinas eólicas são o foco de praticamente todos CMS já que eles provocam um elevado custo de reparo e tempo de parada. Entretanto, uma grande parte das falhas em MC é causada por danos secundários devido a uma falha de um subcomponente. O objetivo deste trabalho é apresentar e propor um método de análise para identificar defeitos em componentes principais ou subcomponentes de uma turbina eólica. O método de análise proposto se baseia em técnicas de sinais temporais de vibração, nas transformadas rápidas de Fourier e análises envelope obtidas através da transformada de Hilbert. A aplicação do método, em uma turbina eólica instalada em um parque eólico real, permitiu a identificação, com sucesso, de um defeito no rolamento, o qual foi substituído confirmando a falha. / Since the decade of 1980s, wind energy technology has undergone tremendous growth over both turbine size and worldwide installed capacity. As the demand for wind turbines of large-scale and lower cost of operation and maintenance continues to grow, interest in condition monitoring system (CMS) has increased rapidly. The main components (MC) of the wind turbines are the focus of almost all CMS since they cause a high repair cost and downtime. However, a large portion of the MC faults are caused by secondary damages due to a subcomponent failure. The objective of this work is to present and propose a method of analysis to identify defects in major components or subcomponents of a wind turbine. The proposed analysis method is based on time wave analysis, fast Fourier transforms analysis and envelope analysis through Hilbert transforms. The application of the method in a wind turbine installed in a real wind farm, identified a bearing defect successfully, which was replaced confirming the failure.

Texas currently maintains the highest installed nameplate capacity and does not require publicly available post-construction monitoring studies that examine the impacts of wind energy production on surrounding fauna. This thesis examines potential wind energy impacts on avian and bat species in Texas through a three-part objective. The first two objectives synthesize literature on variables attractive to species within wind development areas and estimate impacted ranges outside of Texas, based on studies examining wind energy's environmental impacts. The third objective focuses on Texas wind development potential for interaction with rare, threatened and endangered species of birds and bats using GIS analysis with a potential hazard index (PHI) model, which addresses broad-spectrum, high risk variables examined within the first two objectives. Assuming areas with higher wind speeds have potential for wind development, PHI values were calculated for 31 avian and ten bat species, based on an analysis of species range data obtained from the Texas Parks and Wildlife Department and wind data obtained from the National Renewable Energy Laboratory. Results indicate one avian species, Tympanuchus pallidicinctus, is at high risk for wind development interaction on an annual basis, with 20 species of birds and nine species of bats at higher risk during the spring season. This macro-scale approach for identifying high risk species in Texas could be used as a model to apply to other conterminous states' preliminary evaluation of wind energy impacts.

This thesis validates SIMLOX as a simulation tool for wind energy operation and maintenance (O&amp;M). SIMLOX have been used for modeling O&amp;M in other sectors since 2002 but have recently begun to be used for simulating wind energy. This study validates SIMLOX for the newly introduced sector by creating a model of an existing offshore wind farm. The model used real historical data as input and the output was compared to real system response quantities (SRQs). Example of SRQs which were compared was time based availability, energy based availability, energy production, weather days, and item replacements. The study showed that SIMLOX is very well suited for this type of studies. It also showed that the major difficulty lies in obtaining proper input data. All models simulated the exact right number of major item replacements. The time based availability was considered to be the most important SRQ. The time based availability turned out to be between 0.11 - 0.66 percentage points too high compared to reference data. This most certainly depended on an overestimated work schedule for the technicians. Validation is the process of determining the degree to which a model is an accurate representation of the real world from the perspective of the intended uses of the model. This report presents all necessary knowledge to validate SIMLOX as a tool for wind energy simulations but it is thus up to the user to decide whether or not the output is accurate enough for their intended use.