Orientador: Edson Bim / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-06T02:49:03Z (GMT). No. of bitstreams: 1 Segnini_HelioHenriquedeAgostini_M.pdf: 1646244 bytes, checksum: d03ec95486ccbccae70ffedf89d964f1 (MD5) Previous issue date: 2006 / Resumo: O objetivo deste trabalho é estudar o modelo da máquina de indução duplamente alimentada no sistema de referência síncrono, bem como controlar seu fluxo de potências através de orientação de fluxo. São analisadas as orientações de fluxo de estator, de entreferro e de rotor em várias operações: compensador de reativos, gerador e motor, com fator de potência indutivo, capacitivo e unitário, nas faixas de velocidade subsíncrona, síncrona e supersíncrona / Abstract: The purpose of this work is to study the Doubly Fed Induction Machine modeling at the synchronous reference frame, as well as to control its power flux by flux oriented control The stator, rotor and air gap flux orientations with the machine operating as reactive compensator, generator and drive, with lag power factor, lead power factor and unity power factor at subsynchronous, synchronous and supersynchronous speeds are analyzed. / Mestrado / Energia Eletrica / Mestre em Engenharia Elétrica

O mancal magnético base deste trabalho é de 1-GDL(grau de liberdade) de controle uni-axial com circuito magnético híbrido do tipo atração, o qual foi desenvolvido em 2000 na Escola Politécnica da Universidade de São Paulo por Silva e Horikawa [1][2]. Nas duas extremidades do rotor são fixados ímãs, e em oposição ficam os atuadores eletromagnéticos com núcleos ferromagnéticos. Os ímãs são atraídos para os atuadores pelas forças magnéticas devido à presença dos núcleos ferromagnéticos dos dois atuadores. Devido à concorrência entre as forças magnéticas de atração, o rotor fica confinado na posição central do eixo axial resultando numa rigidez passiva para esforços radiais. E na direção axial, a posição do rotor é definida pelo controle ativo que produz o efeito da levitação magnética do rotor. Se o rotor do mancal magnético sofrer esforços na direção axial, o sistema de controle deve aplicar mais corrente elétrica nos atuadores para assegurar o correto posicionamento do rotor, isto pode gerar um enorme consumo de energia elétrica. Este trabalho estuda o princípio de controle de mancal magnético com potência nula para ser aplicado no projeto de uma bomba centrífuga mista, que tem seu rotor suspenso magneticamente. É chamada de potência nula a condição de operação com o mínimo de consumo de energia na levitação do rotor. A bomba em projeto será utilizada no auxílio da circulação sanguínea, aliviando a carga do bombeamento do ventrículo esquerdo do coração doente, por isso o projeto da bomba é chamado de Dispositivo de Assistência Ventricular (DAV). As necessidades técnicas do DAV justificam o emprego do sistema de mancal magnético e do controle de potência nula. Para se aplicar a técnica de controle de potência nula é essencial que o sistema magnético do mancal seja do tipo híbrido. Este estudo se desenvolveu a partir do sistema de mancal magnético desenvolvido por Silva e Horikawa [1][2] pela semelhança de propriedades que o mancal do DAV solicita. O Algoritmo do controle de potência nula (ZPC- zero power control) foi desenvolvido para proporcionar um código simples e pequeno sem comprometer a robustez do controle que o projeto do DAV requer. / The magnetic bearing of this work is based on the 1-DOF (degree of freedom) control uni-axial magnetic circuit with hybrid-type attraction, which was developed in 2000 at the Polytechnic School, University of São Paulo by Silva and Horikawa [1][2]. At both ends of the rotor magnets are fixed, and in opposition are the electromagnetic actuators with ferromagnetic cores. The magnets are attracted to the actuators by the forces due to the presence of ferromagnetic cores of the two actuators. Due to competition between the magnetic forces of attraction, the rotor is confined in the central position of the axial stiffness resulting in efforts to radial. And in the axial direction, the rotor position is defined by the active control that produces the effect of magnetic levitation of the rotor. If the rotor magnetic bearing suffer efforts in the axial direction, the control system should apply more electrical current in the actuators to ensure correct positioning of the rotor, this can generate a huge power consumption. This paper studies the principle of magnetic bearing control with zero power to be applied in designing a mixed centrifugal pump, which has its rotor magnetically suspended. It is called the zero power operating condition with minimal energy consumption in the levitation of the rotor. The pump design will be used to aid blood circulation, relieving the load on the pumping of the left ventricle of the heart sick, so the pump design is called a Ventricular Assist Device (VAD). The technical needs of the DAV justify the use of magnetic bearing system and zero power control. To apply the technique of zero power control is essential that the magnetic bearing system is a hybrid. This study was developed from the magnetic bearing system developed by Silva and Horikawa [1] [2] by the similarity of the bearing properties of the DAV requests. The algorithm of zero power control (ZPC-zero power control \") was developed to provide a simple and small code without compromising the robustness of the control that the project requires the VAD.

Orientador: Edson Bim / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-21T12:34:50Z (GMT). No. of bitstreams: 1 Jacomini_RogerioVani_D.pdf: 15030828 bytes, checksum: 7c0af103e9c6a3a9527e3c25e4373e7e (MD5) Previous issue date: 2012 / Resumo: O resumo poderá ser visualizado no texto completo da tese digital / Abstract: The abstract is available with the full electronic document / Doutorado / Energia Eletrica / Doutor em Engenharia Elétrica

Der Ausbau dezentraler Energieanlagen wie fotovoltaischen Anlagen beeinflusst die Netzzustände signifikant. Dabei ist unsicher, wo und in welchem Maße deren Ausbau zukünftig erfolgt. Es ist nun an den Netzbetreibern gleichzeitig die aktuellen Herausforderungen zu meistern und die Netzplanung und -regelung für die Zukunft zu aktualisieren. Eine statistische Methode wird entwickelt, die Verteilnetzplanung unter Einsatz von quasi-stationär modellierten ”Smart Grid”-Lösungen wie Blindleistungsreglern und regelbaren Ortsnetztransformatoren ermöglicht. Durch Stichprobenverfahren werden Unsicherheiten wie Ort, Größe und Leistungsprofile der Energieanlagen in das Netzmodell eingebunden. Diese als probabilistischer Lastfluss bekannte Methode wird durch Gütemaße im Bereich geringer Kombination evaluiert. Beispiele probabilistischer Netzplanung werden an Netztopologien präsentiert. / Development of distributed energy units such as photovoltaic systems affects grid states significantly. It is uncertain, where and to what extent the development of these units is carried out in the future. It is now up to the distribution system operator to cope with todays grid challenges and to update grid planning and control for the future. A statistical method is developed, which incorporates quasi-stationary modeled ”smart grid” solutions such as reactive power controllers and on-load tap-changers. Uncertainties such as location, size and power profiles of energy systems are integrated into the grid model by sampling. This method is known as probabilistic load flow and is evaluated by quality measures at low combinations. Examples on probabilistic grid planning of different grid topologies are presented.

Le système de transport d’électricité doit évoluer pour satisfaire les besoins du marché de l’électricité et de l’insertion de la production renouvelable. Les systèmes de transport dits HVDC se développent. Les interfaces d’électroniques de puissance vont jouer un rôle majeur et doivent faire preuve d’une extrême fiabilité, d’une grande efficacité et rester économiquement abordables.La technologie MMC (Convertisseur Modulaire Multi-niveaux) connaît un essor par rapport à des technologies classiques, comme le convertisseur trois-niveaux. Sa topologie étant complexe, deux niveaux de contrôle peuvent être définis. Le premier niveau porte sur le contrôle des interrupteurs pour équilibrer les tensions des sous-modules. Le second niveau contrôle les courants, la puissance et l’énergie dans le système.Cette thèse est axée sur ce deuxième niveau de contrôle. Une approche hiérarchisée et formelle, basée sur l’inversion du modèle pour le contrôle de l’énergie du MMC est présentée. Pour ce contrôle, différentes méthodes ont été proposées et comparées. Cela implique de développer une modélisation, mettre en place un contrôle. Différents modèles et contrôles ont été développés.Le MMC est généralement intégré dans une liaison HVDC où deux stations AC/DC ont un contrôle différent. Un soin particulier doit être apporté à la station dédiée au contrôle de la tension. En effet, la gestion de l’énergie dans le MCC est un point critique pour la stabilité de la tension.Enfin, les différents types de contrôle évoqués ont été étudiés dans le cas d’une liaison HVDC. Il a été montré que les échanges entre le bus DC et les MMC jouent un rôle important pour la régulation de la tension du bus DC / In future, the capability of the electric power transmission continues to grow due to renewable energy production and the needs of electrical market. Consequently, many HVDC transmission systems are developed. Definitely the power electronic interfaces will play a key role to provide high reliability, good efficiency and cost effectiveness for this AC/DC conversion.Recently, the Modular Multilevel Converter (MMC) has taken the advantage over the more classical converter as three-level VSC. Since MMC topology is complex, two different control levels may be distinguished: the control of the switches mainly orientated on the balance of hundreds of voltage on the elementary submodules, the higher level control whose aim is to control the currents, power and energy in the system.This thesis is oriented mainly on the latter. It discusses a hierarchical and formal approach for the MMC to control the energy in all the storage elements. At first it is shown that an energy control is required mandatory. Secondly, it supposes to develop an energetic model which is inverted to design the energy control. Then different solutions of control have been developed and discussed.In the majority of applications, MMC is integrated in an HVDC point to point link where the two AC/DC substations have different roles. A specific attention has to be paid on the station which controls the voltage since the way to manage the energy in the MMC has a critical role in the DC voltage stability.Finally, all these types of control have been tested and discussed on an HVDC. It is shown that the exchange between the DC bus and the MMC placed on both sides play a key role in the DC bus voltage regulation.

Abstract In this thesis, adaptive transmission power control algorithms for reliable communication in channels with state are explored and further developed. In channels with state, strict adherence to Shannon-sense capacity may lead to very conservative system designs. In many practical systems, error-free communication is not required because these systems can cope with decoding errors. These considerations give rise to other information-theoretic notions where the rate of reliable communications is considered a random variable which depends not only on the statistical properties of the channel but also on the adaptive transmission strategy. Numerous studies on adaptive transmission in channels with state have already been conducted using expected value of communication rate or information outage probability as the relevant performance metrics. However, these metrics, although intuitively pleasing, have usually been introduced without rigorous justification. This thesis contributes to the state of the art in a number of ways. These include the development of new conceptual viewpoints on performance assessment of adaptive communication systems in channels with state as well as a new set of adaptive transmission power control algorithms. In particular, the models and methods of rational decision theory are introduced and systematically used in developing a unified framework for analysis and optimization of adaptive transmission in channels with state. The proposed framework properly addresses the limitation of finite coding length, takes into account the decision maker's preferences, considers uncertainties relevant in a given decision, and determines the optimal decision by maximizing some numerical index. A central finding of the theoretical studies is that many of the previously proposed performance metrics can be rigorously justified within the newly proposed framework. In addition, adaptive transmission power control in parallel Gaussian channels is considered with the aim of obtaining new classes of algorithms. The safety-first approach, risk theory, and expected utility theory are applied to derive novel transmission power control algorithms. The performance of the proposed power control algorithms is evaluated by computer simulations and compared against the performance of some other well-known algorithms. / Tiivistelmä Tässä väitöskirjassa tutkitaan ja kehitetään edelleen adaptiivisia lähettimen tehonsäätöalgoritmeja luotettavaan tietoliikenteeseen kanavissa, joilla on tila. Tällaisissa kanavissa Shannonin määrittelemän kapasiteetin tiukka noudattaminen saattaa johtaa konservatiivisiin järjestelmiin. Monissa käytännön järjestelmissä virheetöntä tiedonsiirtoa ei vaadita, koska niissä voidaan helposti selviytyä dekoodausvirheistä. Nämä pohdinnat johtavat toisenlaisiin informaatioteoreettisiin näkökulmiin, joissa luotettavan tietoliikenteen nopeutta pidetään satunnaismuuttujana, joka ei riipu ainoastaan kanavan tilastollisista ominaisuuksista vaan myös adaptiivisesta lähetysstrategiasta. Adaptiivisesta siirrosta kanavissa, joilla on tila, on jo tehty lukuisia tutkimuksia käyttäen tietoliikennenopeuden odotusarvoa tai informaation katkostodennäköisyyttä asiaankuuluvina suorituskykymittareina. Näitä mittareita on käytetty tavallisesti ilman tarkkaa perustelua, vaikka ne ovat intuitiivisesti houkuttelevia. Tämä väitöskirja tuottaa uusia tuloksia alan kehityksen nykytasoon monella tavalla. Näihin kuuluvat uudet käsitteelliset näkökulmat adaptiivisten tietoliikennejärjestelmien suorituskyvyn arviointiin kanavissa, joilla on tila, sekä uusi joukko adaptiivisia tehonsäätöalgoritmeja. Erityisesti rationaalisen päätöksenteon malleja ja menetelmiä on otettu käyttöön systemaattisesti kehitettäessä yhtenäistä puitetta adaptiivisen siirron analyysiin ja optimointiin kanavissa, joilla on tila. Ehdotettu puite arvioi asianmukaisesti äärellisen koodauspituuden rajoitusta, ottaa huomioon päätöksentekijän mieltymykset, tarkastelee määrättyyn päätökseen liittyviä oleellisia epävarmuuksia ja määrittää optimaalisen päätöksen maksimoimalla jonkin numeerisen päätösmuuttujan. Keskeinen löytö on se, että monet aikaisemmin ehdotetut suorituskykymittarit voidaan perustella tarkasti uuden, tässä ehdotetun puitteen sisällä. Lisäksi tarkastellaan adaptiivista lähettimen tehonsäätöä rinnakkaisissa Gaussin jakaumaa noudattavissa kanavissa. Tavoitteena on saada aikaan uusia lähettimen tehonsäätöalgoritmien luokkia. Turvallisuus ensin -lähestymistapaa, riskiteoriaa ja odotetun hyödyn teoriaa sovelletaan uusien lähettimen tehonsäätöalgoritmien johtamiseen. Ehdotettujen tehonsäätöalgoritmien suorituskykyä on mitattu tietokonesimuloinneilla ja verrattu joidenkin muiden hyvin tunnettujen algoritmien suorituskykyyn.

In this thesis, we consider a cooperative relay-assisted communication system that uses rateless codes. When multiple relays are present, the relay with the highest channel gain to the source is the first to successfully decode a message from the source and forward it to the destination. Thus, the unique properties of rateless codes ensure that both rate adaptation and relay selection occur without the transmitting source or relays acquiring instantaneous channel knowledge. We show that in such cooperative systems, buffering messages at relays significantly increases throughput. We develop a novel analysis of these systems that combines the communication-theoretic aspects of cooperation over fading channels with the queuing-theoretic aspects associated with buffering. Closed-form expressions are derived for the throughput and end-to-end delay for the general case in which the channels between various nodes are not statistically identical. Results are also shown for the benchmark system that does not buffer messages. Though relay selection combined with buffering of messages at the relays substantially increases the throughput of a cooperative network, it also increases the end-to-end delays due to the additional queuing delays at the relay nodes. In order to overcome this, we propose a novel method that exploits a unique property of rateless codes that enables a receiver to decode a message from non-contiguous and unordered portions of the received signal. In it, each relay, depending on its queue length, ignores its received coded bits with a given probability. We show that this substantially reduces the end-to-end delays while retaining almost all of the throughput gain achieved by buffering. In effect, the method increases the odds that the message is first decoded by a relay with a smaller queue. Thus, the queuing load is balanced across the relays and traded off with transmission times. We derive conditions for the stability of this system when the various channels undergo fading. Despite encountering analytically intractable G/GI/1 queues in our system, we also gain insights about the method by analyzing a similar system with a simpler model for the relay-to-destination transmission times. Next we combine the single relay selection scheme at the source with physical layer power control at the relays (due to the diversity provided by the rateless codes, power control at the source is not needed). We derive an optimal power control policy that minimizes the relay to destination transmission time. Due to its computational and implementation complexity, we develop another heuristic easily implementable near optimal policy. In this policy, power allocated turns out to be inversely proportional to the square root of channel gain. We also see that this policy performs better than the channel inversion policy. Our power control solution substantially decreases the mean end-to-end delays with a marginal increase in throughput also. Finally, we combine bit dropping with power control at the relays which further improves the system performance.

Theses focuses on the evaluation of the possible means of active and reactive power control of generating units connected to medium voltage. First part summarizes analysis of Czech Republic medium voltage distribution grid. It summarizes means of autonomous and dispatcher control of generating units with respect to European Comission directive RfG, standard ČSN EN 50549-2 and national implementation PPDS. Following parts provide description of generating unit and distribution grid models used for simulation in PSCAD. Last part focuses on evaluation of results obtained via simulating steady-state scenarios as well as continuous simulation.

This work deals with the deployment of distributed power sources into the electric power grid. The nature of these sources causes that the massive integration may experience problems with power quality in the local context, and also overall reliability of supply in the range of interconnected power systems may be endangered. Work is focused on local voltage quality problems with special emphasis on analysis and design of tools (e.g. reactive power compensation units of power plants or dynamic voltage control by transformers 110/22kV) for voltage control in power distribution systems. These tools should be used as a part of uniform concept of voltage control. The proposed concept is involved.

With ambitions of reducing the environmental pollution, power systems integrate larger shares of Renewable Energy Sources (RES) to phase out conventional thermal and nuclear generators. Since RES (such as wind and solar power) are connected to the grid through power electronics devices, they do not inherently contribute to system inertia. With decreasing inertia, the Instantaneous Frequency Deviation (IFD), which follows a power unbalance, is significantly impacted. Frequency Containment Reserves (FCR) are designed to provide a fast dynamic response, counteract power imbalances and stabilize the frequency within a short time interval. Besides inertia, the significant factors affecting frequency behavior are the available amount of FCR and the capability of their fast and stable response. System operators define the list of requirements that a generating unit has to satisfy to participate in FCR. Generators, which are the major part of FCR, have different governors and turbines properties. This study assesses the dynamical performance of typical generators in both open-loop testing and closed-loop varying inertia systems. The goal is to evaluate if specific FCR requirements present a sufficient condition for the desired response, and which governor properties are capable of satisfying them. As an additional, and sometimes necessary, support to FCR, HVDC interconnections are utilized in the form of Emergency Power Control (EPC). This thesis investigates which of the EPC methods performs appropriately in terms of IFD improvement, closed-loop stability, and power and energy provided. The analysis is a continuation from the previous investigation on FCR, and mainly compare two EPC methods related to Nordic Power System (NPS) test case: ramp/step method which is currently implemented in the NPS, and droop frequency-based EPC, proposed by this study for the future operation in the NPS. Apart from ensuring a proper system frequency response, the influence of implemented HVDC supplementary active power control is analyzed to rotor angle stability. In further, this thesis presents a comprehensive analysis of the impact that proposed HVDC supplementary power control has on the linearized dynamics of power systems. By building a generic system, this analytical study is the first of its kind that includes both higher order generator dynamics, and local angle/frequency input of the controller. The methodological approach here analytically formulates the impact the HVDC supplementary control has mainly on the generator synchronizing and damping torque components. The positive impact of the droop frequency-based HVDC power support is highlighted using both single and multi-machine systems. In that way, the implementation of desired droop frequency-based HVDC control to mainly improve system frequency is motivated furthermore. It shows that a proper HVDC supplementary control may impose the various positive impacts for future variable and low inertia scenarios, and ensure a proper power system sustainability. / <p>QC 20200907</p> / multiDC - Advanced Control and Optimization Methods for AC and HVDC Grids