Renewable distributed generation such as wind power and photovoltaics are gaining popularity all over the world. The overall aim of this Master thesis was to gather experience and knowledge regarding small wind power and photovoltaic with both a market based evaluation and technical description. Methods used have been literature review, interviews with market participants, evaluation of a wind mill and a photovoltaic system simulation with PVsyst 5.41. It was found that the main common incentive today for the development and spread of small wind power and photovoltaics for market participants is the symbolic value. It was also discovered that the market situation is complicated for the producing consumer. The spread of small wind power and PV today are a few per mille of a future potential, where politics largely control development and spread of small-scale solutions. The market is unclear and solutions around net charge is still an ongoing debate. Majority of the interviewed persons believes more in PV than in small wind power due to facts such as wind power is size-dependent and not optimal to build in urban areas. Results show that power quality issues are dependent on the network system as a whole and are often a matter of cost and can be prevented with different technical solutions. One conclusion was that bidirectional power flow increase complexity of problems around protection. Major energy companies are involved in projects to gather knowledge how to deal with DG both in technical aspects and how to deal with customers practically.

Electric power utilities and end users are becoming increasingly concerned about the quality of power supply. To reduce the losses caused by power service disturbances, mitigation devices are available for improving the power quality. The first step in the power quality improvement is to monitor the system behavior by using some Electronic recording devices. A design and implementation of a digital signal processor based power quality monitoring device is presented in this thesis. Several event-triggering methods are studied and implemented to detect system disturbances. Simulation and test results indicate that the proposed design can meet the requirements for power measurements and transient event recording during steady and transient states.

This work evaluates the impact of electric vehicle loads (EVs) on utility distribution secondary networks and determines the factors affecting the network voltage quality. The study is conducted using two actual distribution circuits, residential and mix residential and industrial circuits. The study reveals the following. A distant secondary network experiences a greater steady-state voltage drop than a nearby secondary network. Location of EV loads relative to the service transformer affects the secondary voltage more significantly. An EV load installed on a distant load node from a service transformer causes comparatively higher undervoltage condition (about 1.5%) than an EV on a nearby load node from the service transformer (about 0.75%). Increasing the size of EV charger increases the severity of an undervoltage condition. A 240V/30A EV charging station causes undervoltage condition to double compared to that of a 240V/16A EV charger. Also installing an EV load adjacent to the existing EV load customer approximately doubles the undervoltage condition at the EV load nodes. / text

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The present power system is loaded with sophisticated energy conversion technologies like solid state converters. With the rapid advance in semiconductor technology, power electronics have provided new devices that are highly efficient and reliable. These devices are inherently non-linear, which causes the current to deviate from sinusoidal conditions. This phenomenon is known as harmonic current distortion. Multiple consumers are connected to the utility at the point of common coupling. Harmonic currents are then transmitted into the distribution system by various solid state users and this could lead to voltage distortion. Harmonic distortion is just one of the power quality fields and is not desirable in a power system. Distortion levels could cause multiple problems in the form of additional heating, increased power losses and even failing of sensitive equipment. Utility companies like Eskom have power quality monitors on various points in their distribution system. Data measurements are taken at a single point of delivery during certain time intervals and stored on a database. Multiple harmonic measurements will not be able to describe distortion patterns of the whole distribution system. Analysis must be done on this information to translate it to useful managerial information. The aim of this project is to develop a benchmarking methodology that could aid the supply industry with useful information to effectively manage harmonic distortion in a distribution system. The methodology will implement distortion indexes set forth by the Electrical Power Research Institute [3], which will describe distortion levels in a qualitative and quantitative way. Harmonic measurements of the past two years will be used to test the methodology. The information is obtained from Eskom’s database and will benchmark the North-West Province distribution network [40]. This proposed methodology will aim to aid institutions like NERSA to establish a reliable power quality management system. / Thesis (M.Ing. (Nuclear Engineering))--North-West University, Potchefstroom Campus, 2012

Os modernos equipamentos elétricos de aquecimento de água de passagem, popularmente conhecidos como chuveiros, duchas ou aquecedores, possuem como elementos aquecedores resistências elétricas constituídas por um fio de liga metálica enrolado, geralmente em ferro-cromo-alumínio ou níquel-cromo. O controle da temperatura da água é usualmente realizado pelo controle do fluxo d'água e pela mudança das derivações ("taps") presentes na resistência. A simplicidade deste controle se opõe à sua falta de flexibilidade para impor ajuste simultâneo de temperatura e vazão d'água. Um controle eletrônico de potência é oferecido como diferencial nos modelos mais sofisticados. Os modelos atualmente existentes no mercado são implementados com controle eletrônico por ângulo de fase, e é sabido que esse tipo de controle gera problemas de distorção harmônica de corrente das redes de energia, com a presença de harmônicas superiores de corrente (acima da fundamental) cuja filtragem é de difícil implementação devido ao nível de potência envolvido e às dimensões físicas dos aparelhos de aquecimento. Como alternativa a esse tipo de controle existe o controle por ciclos inteiros, o qual não gera harmônicas superiores de corrente, mas traz outro inconveniente, que é a produção de variação de tensão da rede de energia, que acarreta variação de luminosidade nas lâmpadas da instalação em níveis de freqüência perceptíveis ao olho humano (fenômeno conhecido como cintilação ou "flicker"). O objetivo do presente trabalho é propor uma solução otimizada ao controle de potência por ciclos inteiros, onde o mesmo é implementado por semi ciclos inteiros "otimizados" de forma a não gerar distorção harmônica nem cintilação de luminosidade perceptível ao olho humano. / Modern electrical direct water heating (DWH) equipments use electrical resistances built with metal alloys (iron-chrome-aluminum or nickel-chrome) as heating elements. Water temperature control is usually made with water flow control, as well as with resistance tap changing. The simplicity of this approach conflicts with to the lack of flexibility to allow simultaneous control of both water flow and its temperature. Therefore, an electronic power control is usually found in more sophisticated models. Usually the electronic power control is implemented by using phase angle control, which causes higher order current harmonics distortion of AC line currents, and filtering is difficult due to the high level of power involved and to the limited dimensions of typical electrical DWH equipment. The alternative for this type of power control is the cycle-by-cycle power control, which does not generate higher order current harmonics but creates line voltage variation, which in turn provokes lighting level variation and resulting unsteadiness on visual sensation, also known as flicker. The aim of the present work is to present an optimized solution for a half-cycle power control, in a way that does not generate harmonic distortion nor eye perceptible level of flicker.

Os equipamentos de análise de qualidade da energia elétrica, em sua grande parte, salvam a forma de onda amostrada somente no entorno do instante onde é detectado algum distúrbio, tipicamente um transiente. Essa limitação se deve em grande parte aos limites de armazenamento das memórias retentivas e ao alto custo que estas representam para um equipamento. No entanto uma nova geração de analisadores está se tornando cada vez mais comum, os analisadores de registro contínuo. Essa família de analisadores, além de salvar relatórios baseados no cálculo de parâmetros pré-estabelecidos também realiza o armazenamento contínuo da forma de onda amostrada. Essa abordagem permite que, conforme evoluam as ferramentas matemáticas para análise da qualidade da energia elétrica, novas análises sejam feitas sobre os dados coletados, tirando assim novas conclusões sobre um sistema elétrico. No entanto, para poder aplicar esta abordagem é necessário que o armazenamento dessas informações seja feito da forma mais eficiente possível, dado o grande volume de dados amostrados ao longo de todo um período de análise. Este trabalho visa o desenvolvimento de um algoritmo de compressão de registros de qualidade da energia elétrica, bem como sua implementação em hardware reconfigurável. Os algoritmos de compressão desenvolvidos estão baseados em um sistema de compressão composto por diferentes técnicas de compressão utilizadas em conjunto. Os métodos propostos fazem uso do algoritmo Deflate como algoritmo de compressão sem perdas. Para melhorar a capacidade de compressão do algoritmo Deflate, técnicas de transformação, aproximação polinomial e codificação de dados são aplicadas como meio para diminuir a entropia dos dados e assim aumentar a eficiência de compressão. Por fim, é apresentada a implementação dos algoritmos de compressão polinomial e Deflate, os quais foram implementados em linguagem VHDL e sintetizados para uso em FPGA. / Most of the power quality analyzers, just records the waveform of the sampled signals around the moment where a transient disturbance is detected. This limitation is due to the storage limits of the retentive memories and the high cost that it represents in a equipment. However a new generation of analyzers is becoming very common, the continuous logging power quality analyzers. This family of analyzers, as well as records reports based on the calculation of pre-defined parameters also performs the continuous storage of the sampled waveform. This approach allows new analysis on the collected data, thus allowing new conclusions about an electrical system. However, in order to apply this approach is required that the storage of such information is done as efficiently as possible, given the large amount of sampled data recorded in the entire period of analysis. This work aims to develop a compression algorithm to records of power quality as well as its implementation on reconfigurable hardware. The compression algorithms were developed based on a compression system composed of different compression techniques used together. The proposed algorithms make use of the Deflate algorithm as a lossless compression algorithm. The compression rate of the Deflate algorithm it is improved through the preprocessing of the data using techniques like polynomial transformation and data encode, as a way to reduce the date entropy. It is also presented in the work the implementation of the algorithms in VHDL language for use in FPGA devices.

abstract: There has been a considerable growth in distributed photovoltaic (PV) genera-tion and its integration in electric power distribution systems. This has led to a change in the distribution system infrastructure. Properly planned distributed gen-eration can offer a variety of benefits for system operations and enhance opera-tional performance of the distribution system. However, high penetration of PV resources can give rise to operating conditions which do not arise in traditional systems and one of the potential issues that needs to be addressed involves impact on power quality of the system with respect to the spectral distortion in voltages and currents. The test bed feeder model representing a real operational distribution feeder is developed in OpenDSS and the feeder modeling takes into consideration the ob-jective of analysis and frequency of interest. Extensive metering infrastructure and measurements are utilized for validation of the model at harmonic frequencies. The harmonic study performed is divided into two sections: study of impact of non-linear loads on total harmonic voltage and current distortions and study of impact of PV resources on high frequency spectral distortion in voltages and cur-rents. The research work incorporates different harmonic study methodologies such as harmonic and high frequency power flow, and frequency scan study. The general conclusions are presented based on the simulation results and in addition, scope for future work is discussed. / Dissertation/Thesis / Masters Thesis Electrical Engineering 2014

Made available in DSpace on 2014-06-11T19:22:34Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-08-19Bitstream added on 2014-06-13T20:29:07Z : No. of bitstreams: 1 terrazas_tm_me_bauru.pdf: 4348012 bytes, checksum: 27e94d130fad8ef6a3527dccde1db635 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Dentre as muitas topologias de condicionadores de energia disponíveis na literatura, destaque especial tem sido dado aos filtros ativos de potência, dispositivos tipicamente eletrônicos, controlados digitalmente. Neste sentido, as topologias mais estudadas são as de filtros ativos paralelos, filtros ativos série e filtros ativos universais (série-paralelo). Neste trabalho, foi dada atenção especial ao estudo de um filtro ativo universal, também conhecido coo Condicionador Unificado de Qualidade de Energia (CUQE) ou em inglês, Unified Power Quality Conditioner (UPQC). Assim, dentre os muitos assuntos que permeiam o projeto e implementação deste dispositivo, este trabalho propõe novos algoritmos para a geração de referência dos conversores eletrônicos, bem como algoritmos de inicialização e proteção do CUQE. Os algoritmos de referênciasão baseados em técnicas de álgebra vetorial e filtragem digital, enquantoas rotinas de inicialização e proteção visam à solução de problemas de ordem prática, para que o dispositivo possa ser utilizado em ambiente industrial, como produto. Um estudo sobre os controladores de tensão e corrente também foi realizado e as técnicas mais adequadas estão descritas no trabalho. Destaca-se que todos os algoritmos de geração de referência, proteção, inicialização e os controladores foram avaliados e validados por meio de simulações computacionais e resultados experimentais. No caso dos resultados experimentais, foram realizados ensaios em malha aberta para validação dos algoritmos de referência, bem como ensaios em um protótipo de CUQE, de potência igual a 75 KVA, os quais validaram o desempenho de todos os algoritmos desenvolvidos em um dispositivo real para aplicações industriais / Among different topologies of power conditioners found in literature, special emphasis has been given to active power filters (typically power electronic devices with digital control). In this sense, the most studied topologies have been the parallel active filters, the series active filters and the unified active filters (series-parallel). In this work, special attention was given to the study of a Unified Power Quality Conditioner (UPQC). Thus, among many issues that underline the design and implementation of this device, this dissertation proposes new algoritmos for the generation of voltage and current references to the applied power converters, as well algoritmos for the initialization and protection of the UPQC. The reference algorithms are based on vector algebra and digital filtering techniques, while the initialization and protection routines aimed to solve practical problems, so the device can be used in and industrial environment, as a commercial product. The voltage and current controllers were also studied and the most suitable techniques are described. It is noteworthy that all proposed algorithms and controllers have been evaluated and validated by means of computer simulations and experimental results. The experimental validation were performance by means of open loop tests, as well as considering an UPQC prototype (75 KVA rated) in order to validate the overall UPQC development and the performance of the proposed algorithms

CAPES / Este trabalho apresenta o desenvolvimento de um algoritmo de controle baseado em controle ótimo para um sistema de condicionamento de energia. Para o projeto do controlador, propõe-se uma nova modelagem deste sistema, onde se inclui as dinâmicas impostas pela tensão da rede no ponto de conexão. O sistema de condicionamento de energia é capaz de atuar como um controlador de qualidade de energia, fornecendo potência reativa e não-ativa, mesmo submetido a cargas lineares e/ou não-lineares desequilibradas. Além disso, este trabalho propõe uma solução para a redução da defasagem inserida pelo filtro analógico passa-baixas de segunda ordem, anti-aliasing. O sistema de condicionamento de energia faz uso de um inversor de tensão (VSI do inglês Voltage Source Inverter ) trifásico a três fios. A geração das referências de corrente é obtida através de um método recentemente proposto e baseia-se na teoria de filtragem ótima. Este algoritmo, aliado às técnicas de controle escolhidas, permite que se obtenha um compromisso satisfatório entre resposta transitória e rejeição às perturbações na geração destes sinais e controle do sistema como um todo. No final do trabalho, a técnica de controle apresentada é comparada à outras duas técnicas aplicadas a este tipo de sistema, a saber, Proporcional-Integral (PI) e Regulador Linear Quadrático com parcela integral (LQRI), de forma a verificar a eficácia do método desenvolvido. Nesta comparação, verifica-se o desempenho destes controladores e do controlador proposto de acordo com diversos critérios de desempenho: rastreamento das referências, taxa de distorção harmônica de tensão e corrente bem como robustez a variações da impedância da rede. / This work presents the development of a control system, based on optimum control theory, applied for an energy conditioner device, where it is included, on its model, the dynamics imposed by the grid voltages at the connection point. The power conditioner system acts as a quality energy controller, supplying reactive and non-active power, even under unbalance linear and non-linear loads. Moreover, the present work proposes a solution for reducing the phase deviation problem inserted by a second order low-pass filter, used for mitigating the aliasing problem, showing an instrumentation alternative to solve this problem. The energy conditioner topology uses a three-phase three-legs shunt voltage source inverter (VSI). The current reference generation is obtained from a recently proposed method, based on optimum filtering theory. This algorithm, together with the chosen control strategy, allows to obtain a satisfactory compromise between transient response and perturbation rejection on the generation of the reference signals and control of the whole system. At the end of this work, a comparison among the proposed control structure and two others controllers, namely Proportional-Integral (PI) and Linear Quadratic Regulator with Integral action (LQRI), is made in order verify the efficacy of the developed methodology. On this comparison, its presented the performance of these 3 controllers, considering several performance criteria: reference tracking, voltage and current harmonic distortion as well as robustness of the system under grid impedance changes.