This research work focuses on the reactive power compensation of the permanent magnet synchronous generator (PSG) in wind power plants. PSG feeds a fixed voltage dc grid through a rectifier bridge. In variable speed operation, the PSG will be able to build torque only in small speed range. This is due to the fixed magnet of the PSG. External reactive power compensation provides an attractive solution to overcome this problem. Different reactive power compensation configurations were examined. Statics synchronous series compensation and a shunt passive filter were chosen as a compensation method. Simulation and implementation of small wind power plant were performed. The wind power plant consists of the synchronous generator, inverter, rectifier, coupling transformers and shunt passive filter. The experimental results agree to the proposed theory and simulation results. / Der Schwerpunkt meiner Promotion ist die Blindleistungskompensation bei einem permanenterregten Synchrongenerator. Der Synchrongenerator speist das Gleichsspannungsnetz über ein Gleichrichter. In der Drehzahlvariablen Betriebsverhalten können Nachteile auftreten. Die Folge ist, dass bei konstanter Gleichspannung und fester Erregung durch die Permanenterregung nur ein sehr kleiner Drehzahlbereich mit vernünftiger Drehmomentausbeute bedienbar ist. Ein möglicher Ausweg wäre eine variable Kompensationsspannung. Verschiedene Kompensationsverfahren wurden untersucht. Ein Series Active Filter und ein Shunt Passive-Filter wurden als Blindleistungskompensation gewählt. Im Rahmen meiner Dissertation beschäftige ich mich mit dem Aufbau und der Simulation einer Windkraftanlage. Diese besteht aus einem permanenterregten Synchrongenerator, einem Wechselrichrter, einem Gleichrichter, drei Transformatoren und einem passiven Filter. Das Versuchsergebnis zeigt, dass die Theorie mit der Simulation übereinstimmt.

Shunt compensation devices have been a powerful candidate for expanding the limits of transmission facilities, allowing more active power transport and supporting voltage and overall stability of the network. An example of such devices is the Static Synchronous Compensator (STATCOM) which is based on Voltage Source Converter (VSC) which synthesizes output voltage and current for mainly reactive power compensation. STATCOMs might be accompanied with a Thyristor Switched Capacitor (TSC) or Reactor (TSR) which are controllable shunt devices for extra VARs required, along with passive filters for absorbing the switching harmonics generated by the VSC. Such STATCOM topology is referred as the Hybrid STATCOM.However, such configuration typically results in parallel resonances with the maingrid’s passive elements at different harmonic frequencies. This leads to amplification of background harmonics, if any exist, at the Point of Common Coupling (PCC) where the Hybrid STATCOM is connected. This thesis deals with the VSC control in the STATCOM to mitigate the harmonic amplification behavior by active filtering,which is based on emulating an impedance by the control. Also, the overall system passivity is essentially studied, which ensures a passive system with respect to harmonics. / Shunt-kompensationsanordningar har varit en kraftfull kandidat för att öka gränserna för överföringsanläggningar, vilket möjliggör högre aktiv effekt och understöderspännings-stabilitet och övergripande stabilitet i kraftnätet. Ett exempel på sådana enheter är Static Synchronous Compensator (STATCOM) som är baserat på Voltage Source Converter (VSC) som syntetiserar utspänning och ström för huvudsakligen reaktiv effektkompensation. STATCOMs kan åtföljas av en Thyristor Switched kapacitor (TSC) eller Reaktor (TSR) som är kontrollerbara shunt-apparater som ökar kapaciteten för reaktiv effekt (VARs), tillsammans med passiva filter för att absorbera övertoner som genereras av VSC. Sådan STATCOM-topologi kallas HybridSTATCOM. Emellertid, en sådan konfiguration resulterar i parallella resonanser med huvudnätets passiva element vid olika övertoner. Detta leder till förstärkning av bakgrundsövertoner, om någon existerar, vid Point of Common Coupling (PCC) där Hybrid STATCOM är ansluten. Denna avhandling behandlar hur VSC kontrolleras i STATCOM för att mildra förstärkningen av nivåer för övertoner genom aktivfiltrering, vilket är baserat på att VSC kontrollen emulerar en impedans. Dessutom studeras övergripande systempassivitet, vilket säkerställer ett passivt system med avseende på övertoner.

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.

This master´s thesis deals with the design of the control circuits for digital potentiometers and their application in analog systems. Digital potentiometers are three-terminal resistors with an adjustable center connection. The digital potentiomneters enable to drive logic gates, LED drivers, LCD drivers, analog switches etc. Controlling of these mentioned devices is possible by the I2C 2- wire serial bus (invented by Philips). The digital potentiometers are used to control of the primary parameters like cut-off frequency and quality factor in the state variable filter and cut-off frequency in a passive filter. Both filters are simulated in PSpice and then compared with the measured results. Next parts of this master's thesis are a computer program and a exemplary protocol.

This diploma thesis deals with transformation of passive elements in filter structures onto substitutes with new active element CFTA. A basic characteristic, types of filters, their frequency characteristics and a form of transfer functions are listed in an introduction. After it is introduced a development of signal flow graphs, single type of graphs and their modifications. There is specified the method Mason-Coates graphs which proves as optimal for analysis circuits. There are listed rules for a correct evaluation and make-up the graphs. Further are described active elements CFTA, CDTA and a current conveyor. There are defined active substitutes to a floating and grounded inductance, a floating capacitor and also a floating and grounded resistor in this thesis. Here, there are also designed substitutes to parallel combinations of floating passive elements. All substitutes use CFTA as an active element and the grounded capacitor as a passive element of substitute. There are presented forms of M-C graphs, transfer functions and equations for calculation passive elements of substitute at created equivalents. Functionality of designed substitutes is always verified on second order passive filters by the help of a PC simulation. There are tabular listed defined equivalents with corresponding signal graphs, transfer functions and equations for calculation capacitor of substitute are here tabular listed too. In this work there are defined two ways of connecting defined substitutes within the scope of one circuit that can be used as a simple connection or integration bounded elements. In the case of usage of the integration bounded elements it is possible to reduce total number used active elements. The usage defined substitutions are verified by way of both methods on known higher order passive frequency filter structures. Third order low pass filter is here realized and scaled in frequency scope from 100 Hz to 100 MHz.