Nos dias de hoje, o aumento na demanda de energia no Brasil, associado a fatores econômicos e ambientais, tem dificultado a criação de novas usinas hidrelétricas, necessárias para suprir essa demanda adicional e aumentar a confiabilidade do sistema. Nesse contexto, a geração distribuída se destaca como uma solução adequada, pois economiza investimentos em redes de transmissão e distribuição, reduz perdas e diversifica a matriz energética do sistema elétrico, tornando-o mais robusto e eficiente. Dentre as fontes de energia utilizadas em sistemas de geração distribuída, a microturbina apresenta algumas vantagens em relação a outros modelos de GD, como por exemplo, a possibilidade da utilização de vários tipos de combustíveis. Para verificar as características de operação das microturbinas, foram realizadas simulações baseadas em modelos matemáticos presentes na literatura técnica. Porém, devido às altas velocidades de rotação das turbinas a gás, a energia gerada possui frequências muito altas para ser aproveitada diretamente pelos consumidores, sendo necessária uma interface eletrônica para adequação da energia elétrica. Neste trabalho é abordado o estudo, simulação e implementação da primeira etapa desta interface, um retificador trifásico com correção de fator de potência, para a geração de um barramento de corrente contínua com tensão estável, mantendo as correntes de entrada do retificador com formato senoidal e em fase com a tensão. / Nowadays, the increase in energy demand in Brazil, associated with economic and environmental factors, has hindered the creation of new power plants needed to provide this additional demand and improve system reliability. In this context, distributed generation stands out as an appropriate solution because it saves investments in transmission and distribution, reduces losses and diversify the energy matrix of the electrical system, making it more robust and efficient. Among the energy sources used in distributed generation systems, the microturbine has some advantages over other models of GD, such as the possibility of using various types of fuel. To verify the operating characteristics of microturbines, simulations were performed based on mathematical models present in literature. However, due to high rotation speeds of gas turbines, the energy generated has very high frequencies to be used directly by consumers, which requires an electronic interface to adequate the electricity. This work describe the study, simulation and implementation of the first stage of this interface, a three-phase rectifier with power factor correction, to generate a DC bus voltage stable, keeping the rectifier input current format sinusoidal and in phase with the voltage generated by the microturbine.

Submitted by Irene Nascimento (irene.kessia@ufpe.br) on 2016-11-08T17:40:29Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertacao_Moraes_ABNT.pdf: 5928696 bytes, checksum: ffd79ada8f98120795b81b1c40caf20d (MD5) / Made available in DSpace on 2016-11-08T17:40:29Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertacao_Moraes_ABNT.pdf: 5928696 bytes, checksum: ffd79ada8f98120795b81b1c40caf20d (MD5) Previous issue date: 2015-10-29 / Cnpq / Quando comparados aos retificadores tradicionais a diodo ou tiristor, os retificadores PWM têm algumas vantagens como corrente de entrada senoidal, filtro capacitivo pequeno e fator de potência controlado. No entanto, esses conversores são sensíveis a tensões desbalanceadas e transitórios de tensão. Problemas que ocorrem frequentemente em sistemas de potência trifásicos devido a cargas desbalanceadas e faltas no sistema elétrico. Sob essas condições, alguns problemas como; ripple na tensão o barramento CC e presença de harmônicos na correntes da rede podem ser evidenciados. Assim, para manter a tensão do barramento CC constante sem injetar mais correntes harmônicas na rede, surgem duas opções básicas. A primeira é a utilização de grandes filtros capacitivos para atenuar o ripple de tensão, com a possibilidade de ressonância no sistema, além do aumento dos custos e tamanho do retificador tradicional. A segunda alternativa, na qual desenvolve-se o trabalho, é a utilização de uma estratégia de controle, durante faltas no sistema. O trabalho realiza uma análise comparativa de três estratégias de controle. / When compared to traditional thyristor or diode rectifiers, the rectifiers PWM have some advantages like sinusoidal input current, small capacitive filter and power factor control. However, such converters are susceptible tensions unbalanced and transient voltage. Problems that often occur in systems three-phase power due to unbalanced loads and faults in the electrical system. Under these conditions, some problems like; ripple on the DC bus voltage and the presence of harmonic currents in the network can be evidenced. Thus, to maintain tension the constant DC bus without injecting more harmonic currents in the network, there are two basic options. The first is the use of large capacitive filters to attenuate the ripple voltage, with the possibility of resonance in the system, and increased costs and size of traditional rectifier. The second alternative, which develops in the work, is the use of a control strategy during system faults. The work carries a comparative analysis of three control strategies

Nos dias de hoje, o aumento na demanda de energia no Brasil, associado a fatores econômicos e ambientais, tem dificultado a criação de novas usinas hidrelétricas, necessárias para suprir essa demanda adicional e aumentar a confiabilidade do sistema. Nesse contexto, a geração distribuída se destaca como uma solução adequada, pois economiza investimentos em redes de transmissão e distribuição, reduz perdas e diversifica a matriz energética do sistema elétrico, tornando-o mais robusto e eficiente. Dentre as fontes de energia utilizadas em sistemas de geração distribuída, a microturbina apresenta algumas vantagens em relação a outros modelos de GD, como por exemplo, a possibilidade da utilização de vários tipos de combustíveis. Para verificar as características de operação das microturbinas, foram realizadas simulações baseadas em modelos matemáticos presentes na literatura técnica. Porém, devido às altas velocidades de rotação das turbinas a gás, a energia gerada possui frequências muito altas para ser aproveitada diretamente pelos consumidores, sendo necessária uma interface eletrônica para adequação da energia elétrica. Neste trabalho é abordado o estudo, simulação e implementação da primeira etapa desta interface, um retificador trifásico com correção de fator de potência, para a geração de um barramento de corrente contínua com tensão estável, mantendo as correntes de entrada do retificador com formato senoidal e em fase com a tensão. / Nowadays, the increase in energy demand in Brazil, associated with economic and environmental factors, has hindered the creation of new power plants needed to provide this additional demand and improve system reliability. In this context, distributed generation stands out as an appropriate solution because it saves investments in transmission and distribution, reduces losses and diversify the energy matrix of the electrical system, making it more robust and efficient. Among the energy sources used in distributed generation systems, the microturbine has some advantages over other models of GD, such as the possibility of using various types of fuel. To verify the operating characteristics of microturbines, simulations were performed based on mathematical models present in literature. However, due to high rotation speeds of gas turbines, the energy generated has very high frequencies to be used directly by consumers, which requires an electronic interface to adequate the electricity. This work describe the study, simulation and implementation of the first stage of this interface, a three-phase rectifier with power factor correction, to generate a DC bus voltage stable, keeping the rectifier input current format sinusoidal and in phase with the voltage generated by the microturbine.

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.

Made available in DSpace on 2016-12-12T17:38:38Z (GMT). No. of bitstreams: 1 JULIO KENDI NISHIOKA.pdf: 8294340 bytes, checksum: 28a4178bb0ec559b2db43a1aa6676188 (MD5) Previous issue date: 2011-08-25 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This dissertation proposes a digital control system for a three-phase four-wire high input power factor PWM rectifier with LCL filter. The proposed control system includes an inner control loop for active damping of the LCL filter peak resonance, which uses a lead-lag compensator. In addition, the control system presents an independent current loop for each rectifier phase, which employs resonant compensators tuned at the fundamental frequency of the utility grid voltage. Finally, other two outer loops are used to maintain the voltages across the dc bus capacitors regulated and balanced. This work also proposes a design methodology to obtain the parameter of the LCL filter, which is based on maximum harmonic currents allowed by technical standards and on the minimization of the reactive energy of the LCL filter capacitors. Simulation and experimental results are presented to validate the developed analysis and demonstrate the performance of the proposed controllers. / Esta Dissertação de Mestrado propõe um sistema de controle digital para um retificador PWM trifásico a quatro fios com filtro LCL e elevado fator de potência de entrada. O sistema de controle proposto inclui uma malha interna de amortecimento ativo do pico de ressonância do filtro LCL, fazendo uso de um compensador em avanço. Além da malha de amortecimento ativo, o sistema de controle apresenta uma malha de corrente independente para cada fase do retificador, as quais empregam compensadores ressonantes sintonizados na frequência fundamental da tensão de entrada. Por fim, outras duas malhas externas são utilizadas para manter as tensões dos capacitores que compõem o barramento CC reguladas e equilibradas. Este trabalho também propõe uma metodologia de projeto para os parâmetros do filtro LCL, a qual é baseada nos limites máximos de harmônicos de corrente permitidos pelas normas e na minimização da energia reativa do capacitor do filtro LCL. Resultados de simulação e experimentais são apresentados para validar as análises desenvolvidas e demonstrar o desempenho dos controladores propostos.

DC power systems have a constant DC-link voltage, as well as the advantages such as high stability, high efficiency, small size and light weight; therefore, they are widely used in stand-alone power systems, e.g. the power systems in aircrafts and automobiles, isolated wind power generation systems, etc. Permanent-Magnet Synchronous Generators (PMSGs) possess the advantages including high power density, high efficiency, and high control precision, and have obtained great attention and have been widely used in military, inductry, and daily life. Pulse Width Modulation (PWM) rectifier has been one of the main power conversion topologies thanks to its full controllability. The key point in the dissertation is to study the DC power system consisting of a PMSG to be the main power input device and a PWM rectifier to be the main power conversion topology. The objective of control is to output a constant DC-link voltage in a wide PMSG speed range. Since the PM-excited flux linkage is constant, when the PMSG is working at a high speed, field-weakening is needed to stabilize the stator voltage, further to stabilize the DC-link voltage. Hybrid excitation may be used to realize the field-weakening, but it has complex structure; no auxiliary devices are needed in the field regulation with the armature current, and can be easily realized with the PWM recifier and field-regulation control strategies. In this dissertation, the typical applications of the DC power systems are first introduced, with a comprehensive analysis and elaboration on the relevant research throughout the world. The research work is focused on the DC power system and its stabilization control, which is composed of a PMSG and a PWM rectifier. The involved research content in this dissertation includes the following aspects: 1. DC power system design with a wide-speed-range PMSGAs for the common DC power systems, PMSG with high power density, high efficiency is selected to the system power input device, usually with a variable-speed prime mover. The PWM rectifier with fully controlled switches is chosen to be the power conversion topology, which converts the AC power generated by PMSG into DC power, and supplies the DC load after the DC filter. The matching between the system requirements and the generator parameters are determined. Through finite-element analysis (FEA), a PMSG with strong field-weakening ability and suitable for wide-speed-range operation has been designed and manufactured, and the system test bench has been built based on dSPACE. 2. Study, analysis, optimization and experimental verification of the traditional control strategiesAccording to the PMSG designed in part 1, the DC-link model has been built, as well as the control model of the traditional control strategies, e.g. field-oriented control (FOC), direct torque control (DTC), and the effectiveness of the DC-link voltage stabilization control has been verified in a wide speed range. The theory of active damping has been proposed and analyzed, and has been utilized in the DC-link voltage control. When the load on the DC-link changes, the dynamic response of the DC-link voltage has been greatly accelerated, and it recovers quickly to its reference value. In the meantime, the performance influence of the prime mover speed on the actual system test bench should be considered. Finally, the performance of FOC and DTC has been compared and analyzed. 3. Analysis and experimental verification of the direct voltage control (DVC), and the comparative study of all the studied control strategiesThe derivation process of DVC has been theoretically analyzed: the inner current loops in FOC have been eliminated to obtain the direct voltage field-oriented control (DVFOC); the reference value of d-axis voltage in DVFOC has been replaced by the product of the stator voltage calculated by the speed and the load condition, and the sine value of load angle generated by the DC-link voltage PI controller, in order to form the DVC-1. Further, the DC-link voltage PI controller directly outputs the reference value of load angle and it becomes DVC-2. Finally, the comparative study has been carried out among all the studied control strategies. / Doctorat en Sciences de l'ingénieur et technologie / info:eu-repo/semantics/nonPublished

IGBT based power converters acts as front end in the present day Adjustable Speed Drive (ASD). This offers many advantages and makes regenerative action possible. PWM rectifier operation produces electrically noisy DC bus on common mode basis. This results in higher ground current as compared to three phase diode bridge rectifier. Due to fast turn-ON and turn-OFF time of IGBT, the inverter output voltage dv/dt is high during switching transients and voltage waveform is rich in harmonics. As a result, in applications involving long cable the motor terminal voltage during the switching transient is as high as twice the applied voltage. This voltage stress reduces the life of insulation in motors. The high dv/dt output voltage applied at the motor terminal excites the parasitic capacitive coupling resulting in increased ground currents and causes Electric Discharge Machining (EDM) which reduces the life of motor bearings. The common mode voltage due to PWM rectifier and the inverter appear at the motor terminals exacerbating these problems. The common mode voltage due to PWM inverter with PWM rectifier is analyzed. An integrated approach for filter design is proposed wherein the adverse effects due to common mode voltage of both AFE converter and the inverter is addressed. The proposed topology addresses the problems of common mode voltage, common mode current and voltage doubling due to ASD. The design procedure for proposed filter topology is discussed with experimental results that validate the effectiveness of the filter. Inclusion of such higher order filter in the converter topology leads to problems such as resonance. Passive methods are investigated for damping the line resonance due to LCL filter and common mode resonance due to common mode filter. The need for active damping technique for resonance due to common mode filter is presented. State space based damping technique is proposed to effectively damp the resonance due to line filter and the common mode filter. Experimental results are presented that validate the effectiveness of active damping both on the line basis (differential mode) and line to ground basis (common mode) of the filter.