The necessity to incorporate renewable energy systems into existing electric power grid and need of efficient utilization of electrical energy are growing every day. A shunt connected Voltage Source Inverter(VSI) capable of bidirectional power flow and fast control has become one of the building block to address such requirements. However with growing number of grid connected VSI, new requirements related to harmonic injection, higher overall efficiency and better performances during short term grid disturbances have emerged as challenges. For this purpose a grid connected three phase four wire VSI with LCL filter can be considered as a general module to study different control approaches and system behavior under ideal and non-ideal grid conditions. This work focuses on achieving enhanced performance by analyzing effect of non-ideal conditions on system level and relating it to individual control blocks. In this work a phase locked loop structure has been proposed which is capable of extracting positive sequence fundamental phase information under non-ideal grid conditions. It can also be used in a single phase system without any structural modification. The current control for the three phase four wire VSI system has been implemented using Proportional Resonant (PR) controller in a per phase basis in stationary reference frame. A simplified controller design procedure based on asymptotic representation of the system transfer function is proposed. Using this method expressions for controller gains can be derived. A common mode model of the inverter system has been derived for low frequencies. Using this model a controller is designed to mitigate DC bus imbalance caused by sensor and ADC channel offsets. A multi-rate approach for digital implementation of PR controller with low resource consumption, that is suitable for an FPGA like digital controller ,is proposed. This multi-rate method can maintain resonance frequency accuracy even at low sampling frequency and can easily be frequency adaptive. Anti-wind up methods for PI controller have been studied to find suitable anti-wind up methods for PR controller. The tracking anti-wind up method is shown to be suitable for use with a PR controller. The effectiveness of this method under sudden disconnection and reconnection of VSI from grid is experimentally verified. A resonant integrator based second order filter is shown to be useful for active damping of LCL filter resonance with a wide range of grid inductance variation. The proposed method utilizes the LCL filter capacitor voltage to estimate resonance frequency current. Suitability of fundamental current PR controller for active damping alone, and with the proposed method show the superiority of the proposed method especially for low switching frequencies. Design oriented analysis of the above topics are included in the thesis. The theoretical understandings developed have been verified through experiments in the laboratory and can be readily implemented in industrial power electronic systems.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Este trabalho apresenta o estudo, desenvolvimento e aplicação de novas técnicas de controle aos sistemas de geração de energia fotovoltaica, conectados à rede elétrica monofásica, visando a melhoria da eficiência destes sistemas em relação aos métodos de controle tipicamente utilizados. O trabalho é dividido em duas partes principais, as quais estão relacionadas ao rastreamento do ponto de máxima potência (Maximum Power Point Tracking – MPPT) e, depois, ao controlador interno dos conversores boost-quadrático – lado dos painéis fotovoltaicos – assim como aos controladores do inversor de tensão, no lado da rede elétrica monofásica. A primeira parte do trabalho consiste no desenvolvimento de um algoritmo de meta heurística para o MPPT, o qual é baseado no método do recozimento simulado (Simulated Annealing - SA) e tem como objetivo a determinação do ponto de máximo global, buscando soluções fora de uma vizinhança próxima, de modo a evitar o atracamento em máximos locais da curva de potência de saída do arranjo de painéis fotovoltaicos, melhorando, assim, o aproveitamento da energia em situações de sombreamento parcial. A segunda parte do trabalho apresenta o projeto de controladores baseados no modelo interno (Internal Model Control – IMC) com 1 grau de liberdade (1 Degree of Freedom – 1 DOF) aplicados, primeiramente, ao conversor CC-CC Boost Quadrático, utilizado para o MPPT, e, posteriormente, a um inversor de tensão com filtro LCL, conectado à rede elétrica monofásica, operando no modo de injeção de corrente. É apresentada a modelagem matemática de ambos os conversores e analisada a compensação da realimentação interna ao sistema do inversor de tensão, correspondente ao desacoplamento da tensão da rede, através da estratégia de alimentação à frente (Feedforward). Visando-se uma base de comparação, para a análise de desempenho do conversor IMC – 1DOF, também é aplicado ao sistema de injeção de corrente, o controlador Proporcional-Ressonante (P+Res). São apresentados resultados de simulação computacional e experimentais de ambos os 8 controladores, os quais permitem verificar o desempenho do sistema em situação de rede fraca e carga local não-linear. / This paper presents the study, development and application of new control techniques for photovoltaic power generation systems, connected to single-phase power grid in order to improve the efficiency of these systems in relation to control methods typically used. The work is divided into two main parts, which are related to tracking the maximum power point (Maximum Power Point Tracking - MPPT) and then the internal controller of boost quadratic converters - side of the photovoltaic panels - as well as the controllers the voltage inverter, the side of the single-phase mains. The first part of the work is the development of a heuristic goal algorithm for MPPT, which is based on the method of simulated annealing (Simulated Annealing - SA) and aims at determining the overall maximum point, seeking out solutions in a close vicinity, so as to prevent the docking local maxima in the curve of power output of the photovoltaic array, thereby improving the utilization of energy in partial shading situations. The second part presents the design of controllers based on internal model (Internal Model Control - IMC) with 1 degree of freedom (1 Degree of Freedom - 1 DOF) applied, first, the DC-DC Boost Quadratic converter, used for MPPT, and thereafter, a voltage inverter with LCL filter connected to the single phase power supply operating in current injection mode. A mathematical modeling of both converters and analyzed the compensation of internal feedback to the voltage inverter system corresponding to the disconnection of the mains voltage through the power strategy a head (feedforward). A basis of comparison for the performance analysis of IMC-1DOF converter is aiming at, is also applied to the current injection system, Proportional-Resonant Controller (P + Res). They are presented computer simulation and experimental results of both controllers, which allow you to check the system performance in low and non-linear local load network situation. / Tese (Doutorado)

Submitted by isabela.moljf@hotmail.com (isabela.moljf@hotmail.com) on 2017-07-03T11:17:42Z No. of bitstreams: 1 mateusfreitasbraga.pdf: 1732565 bytes, checksum: f8ebb1cc4fe4d9ecbd9cc50ba3eb3f2a (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-08-07T21:17:21Z (GMT) No. of bitstreams: 1 mateusfreitasbraga.pdf: 1732565 bytes, checksum: f8ebb1cc4fe4d9ecbd9cc50ba3eb3f2a (MD5) / Made available in DSpace on 2017-08-07T21:17:21Z (GMT). No. of bitstreams: 1 mateusfreitasbraga.pdf: 1732565 bytes, checksum: f8ebb1cc4fe4d9ecbd9cc50ba3eb3f2a (MD5) Previous issue date: 2017-03-20 / Cresce a cada dia o n úmero de cargas não lineares conectadas aos diversos sistemas el étricos, seja em ní vel de transmissão ou distribui ção. Como consequência desse crescimento, e possí vel encontrar casos de consumidores enfrentando problemas relacionados a desarmes de disjuntores e sobreaquecimento de condutores, entre outros efeitos indesejados. Tomando um desses casos como base para este estudo, esta disserta ção tem o objetivo de avaliar e propor uma solu ção para uma rede monof asica real, que possivelmente e comum a outros consumidores. A carga monof ásica composta por lumin árias a LED (t picas cargas não lineares) e cargas indutivas se apresenta aos terminais da fonte com um comportamento de elevado conte udo harmônico (THD) de corrente e baixo fator de potência. Essa condi ção adversa pode ser mitigada de diversas maneiras, como por exemplo pela a ção de um fi ltro passivo,fi ltro ativo ou ainda fi ltro h brido (o qual e composto por uma combina ção dos dois primeiros). Ser a proposto nesta disserta ção uma metodologia de projeto relacionada a aplica ção de um fi ltro hi brido monof ásico visando corrigir o fator de potência e reduzir o conte udo harmônico de corrente presente na fonte, tomando como base as caracterí sticas do sistema avaliado em uma ind ústria gr áfi ca t ípica. Serão investigadas algumas con gura ções de filtros com o objetivo de mitigar problemas de Qualidade de Energia El étrica. Como consequência, ser a desenvolvida a an álise matem atica da topologia adotada e o projeto do controlador, baseado em um controlador proporcional-ressonante e na Teoria p-q Monof asica. A veri ca ção da solu ção proposta e sustentada pelos resultados de simula ção obtidos via software PSIM. / The amount of non-linear loads connected to the various electrical systems grows on a daily basis, regardless those loads are tied to a transmission or distribution bar. As a consequence of this growth, it is possible to nd cases of consumers facing problems such as tripping of breakers and cables overheating, among other undesired e ects. Taking one of these cases as the focus of this study, this dissertation aims to evaluate and propose a solution to a real single-phase system, which could be considered similar to other consumers. The single-phase load composed of LED luminaires (typical non-linear load) and inductive loads presents high THD and low power factor behavior at source terminals. This condition can be mitigated by using some well-known techniques, such as passive lters, active lters or hybrid lters, (which are composed by the combination of the former two). This Master document Thesis proposes a design methodology of a single-phase hybrid lter aiming power factor correction and reduction of the harmonic content of the current delivered by the AC power supply when feeding a typical printing factory. It will be reviewed and discussed some possible lter con gurations aimed to solve the case under evaluation. It is also included the mathematical analysis of the proposed topology, along with the design of the control system of the inverter. The Single-Phase p-q Theory is reviewed in order to design the control. The closed-loop control is desinged by a proportional-resonant compensator. Simulation results, by employing the PSIM software, are provided aiming to validate the solution proposed.