Thesis (MEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: This work investigated the influence of photo-voltaic generators on the voltage control of distribution feeders and the methods that can be used to increase the maximum penetration levels of these feeders. Initially, a brief overview of the reasons why it is necessary to increase the generation penetration levels on distribution feeders was provided. A review of various issues associated with connecting generation to the distribution network; methods and technologies that can be used to increase penetration levels; and ways to improve voltage regulation on MV feeders was given. The grid code for renewable power plants and the voltage apportionment standard were reviewed to determine what limits penetration levels and what can be done to increase them. The operation and control of a typical distribution network, without any connected generation, was initially investigated. A control strategy was implemented that provided suitable voltage regulation on the feeder during both high and low load. The influence of connecting generation to this typical distribution network, without making any modifications to the control of the feeder, was investigated. Base penetration levels, for various generation connection cases, were found. It was shown that the penetration is limited by the rapid voltage change or voltage rise. The base penetration levels were compared to the optimal amount of generation that provides the lowest losses. It was shown that the penetration needs to be increased by between 100% and 200% for the feeder’s losses to be minimised. Voltage regulator and capacitor control was influenced by the generation and they could not function as expected. It was shown that flicker will not be an issue, even with penetration limits well above the current allowable limits. Various methods that can be used to increase the amount of generation that is connected to the typical network were investigated. On-load tap changer setpoint reduction, reactive power control and electronic voltage regulators are some of the methods or technologies that can be used to increase penetration levels. It was shown that each of the technologies can assist, depending on the circumstance, in increasing penetration. The individual modifications can increase penetration up to 100% at the cost of increased tap changes and in some cases losses. Two proposed control strategies were assessed, that combine the investigated technologies. The results showed that it is possible to increase penetration levels by 50-80%, while improving power quality and reducing losses when compared to the base generation connection case. / AFRIKAANSE OPSOMMING: Hierdie werk ondersoek die invloed van die foto- voltaïes kragopwekkers op die spanning beheer van die verspreiding voerder asook die metodes wat gebruik kan word om die maksimum penetrasie vlakke van hierdie voerders te verhoog. Aanvanklik is 'n kort oorsig van die redes waarom dit nodig is om die opwekking penetrasie vlakke op die verspreiding voerders, te verhoog voorsien . Eerstens word 'n hersiening van verskeie kwessies wat verband hou met die koppeling van generasie na die verspreidingsnetwerk gegee. Tweedens word metodes en tegnologie wat gebruik kan word om penetrasie te verhoog gegee en laastens word maniere om spanning regulasie op medium spanning voerders te verbeter, gegee. Die rooster kode "grid code => probeer liewer netwerk regulasies" vir hernubare krag aanlegte en die spanning toedeling standaard is hersien om te bepaal wat beperk die penetrasie vlakke en wat gedoen kan word om dit te verhoog. Die werking en beheer van 'n tipiese verspreiding netwerk, sonder enige verbonde generasie, is aanvanklik ondersoek. 'n Beheer-strategie is toe geïmplementeer wat geskikte spanning regulasie op die voerder tydens beide hoë en lae belasting verskaf. Die invloed van die koppeling van opwekking tot hierdie tipiese verspreiding netwerk, sonder om enige veranderinge aan die beheer van die voerder, is ondersoek. Basis penetrasie vlakke, vir verskeie generasie verband gevalle, is gevind. Daar is bewys dat die penetrasie word beperk deur die vinnige spanning verandering of spanning styging. Die basis penetrasie vlakke word vergelyking met die optimale aantal generasie wat die laagste verliese bied. Daar is bewys dat die penetrasie moet met tussen 100% en 200% verhoog word sodat die voerder se verliese beperk kan word. Die spanning reguleerder en kapasitor beheer is beïnvloed deur die opwekking en hulle kon nie reageer soos verwag nie. Daar is getoon dat flikker nie 'n probleem sal wees nie; selfs al is die penetrasie vlakke ver bo die huidige toelaatbare grense. Verskillende metodes wat gebruik kan word om die aantal generasie wat gekoppel is aan die tipiese netwerk te verhoog is ondersoek. Aan-las tap wisselaar vermindering, reaktiewe krag beheer en elektroniese spanning reguleerders is 'n paar van die tegnieke wat gebruik kan word om penetrasie te verhoog. Daar is bewys dat elkeen van die tegnologieë kan help, afhangende van die omstandighede, vir toenemende penetrasie. Die individuele veranderinge kan penetrasie verhoog tot 100% by die koste van 'n verhoogde tap veranderinge en in sommige gevalle verliese. Twee voorgestelde beheer strategieë is beoordeel, wat die ondersoek tegnologie kombineer. Die resultate het getoon dat dit moontlik is om penetrasie te verhoog met 50% tot 80%, terwyl die verbetering van gehalte en die vermindering van krag verliese in vergelyking met die basis generasie verband hou.

Power distribution networks (PDNs) are conducting structures employed in semiconductor systems with the aim of providing circuits with reliable and constant operating voltage. This network has non-neglible electrical parasitics. Consequently, when digital circuits inside the chip switch, the supply voltage delivered to them does not remain ideal and exhibits spatial and temporal voltage fluctuations. These fluctuations in the supply voltage, known as the power-supply noise (PSN), can affect the functionality and the performance of modern microprocessors. The design of this PDN in the chip is an important part in ensuring power integrity. Modeling and simulation of the PSN in on-chip PDNs is important to reduce the cost of processors. These PDNs have irregular geometries, which affect the PSN. As a result, they have to be modeled. The problem sizes encountered in this simulation are usually large (on the order of millions), necessitating computationally efficient simulation approaches. Existing approaches for this simulation do not guarantee at least one of the following three required properties: computationally efficiency, accuracy, and numerically robustness. Therefore, there is a need to develop accurate, numerically robust, and efficient algorithms for this simulation. For many interconnects (e.g., transmission lines, board connectors, package PDNs), only their frequency responses and SPICE circuits (e.g., nonlinear switching drivers, equivalent circuits of interconnects) terminating them are known. These frequency responses are usually available only up to a certain maximum frequency. Simulating the electrical behavior of these systems is important for the reliable design of microprocessors and for their faster time-to-market. Because terminations can be nonlinear, a transient simulation is required. There is a need for a transient simulation of band-limited frequency-domain data characterizing a multiport passive system with SPICE circuits. The number of ports can be large (greater than or equal to 100 ports). In this simulation, unlike in traditional circuit simulators, normal properties like stability and causality of transient results are not automatically met and have to be ensured. Existing techniques for this simulation do not guarantee at least one of the following three required properties: computationally efficiency for a large number of ports, causality, and accuracy. Therefore, there is a need to develop accurate and efficient time-domain techniques for this simulation that also ensure causality. The objectives of this Ph.D. research are twofold: 1) To develop accurate, numerically robust, and computationally efficient time-domain algorithms to compute PSN in on-chip PDNs with irregular geometries. 2) To develop accurate and computationally efficient time-domain algorithms for the causal cosimulation of band-limited frequency-domain data with SPICE circuits.

Thesis (M.S.)--Mississippi State University. Department of Electrical and Computer Engineering. / Title from title screen. Includes bibliographical references.

Thesis (MScEng)-- Stellenbosch University, 2013. / ENGLISH ABSTRACT: The objective of this project is to develop an electromagnetic model that can be used to accurately calculate the voltage distribution in a transformer winding structure when excited with standard impulse excitation waves. This voltage distribution is required during the design stage of a power transformer to ensure that the insulation is capable of withstanding the occurring electric field stresses during these tests. This study focuses on the modelling of a single disk-type power transformer winding without the presence of an iron-core. Methods of calculating self- and mutual-inductances of transformer windings are presented and validated by means of finite element method software simulations. The same is done for the calculation methods used for calculating the capacitances in and around the winding structure. The calculated and FEM-simulated results are compared to measured values as a final stage of validation. The methods used to calculate the various model parameters seem to produce results that agrees well with measured values. The non-linear frequency dependant dissipative nature of transformer windings is also investigated and a methodology to take this into account is proposed and implemented. The complete modelling methodology proposed in this thesis, which includes the calculation of the model parameters, model synthesis and solver algorithm, are applied to an actual case study. The case study is performed on an air-core reactor manufactured using a disk-type power transformer winding. The reactor is excited with standard lightning impulse waves and the voltages along the winding are measured. The calculated and measured voltage wave forms are compared in both the frequency and time-domain. From the comparison it is found that the model accurately represents the actual transient voltage response of the testunit for the frequency range of interest during standard factory acceptance tests. / AFRIKAANSE OPSOMMING: Die doel van hierdie projek is om 'n elektromagnetiese model te ontwikkel wat gebruik kan word om die spanningsverspreiding in 'n transformatorwindingstruktuur te bereken as standaard weerligimpulstoetse toegedien word. Hierdie spanningsverspreiding word vereis tydens die ontwerpstadium van ‘n kragtransformator om te verseker dat die isolasie in staat is om die elektriese veldsterkte tydens hierdie toetse te weerstaan. Hierdie studie fokus op die modelering van 'n enkele skyftipe-kragtransformatorwinding sonder die teenwoordigheid van 'n ysterkern. Metodes van berekening van self- n wedersydse-induktansie van transformatorwindings word aangebied en getoets deur middel van Eindige-Element-Metode (EEM) simulasies. Dieselfde word gedoen vir die metodes wat gebruik word vir die berekening van die kapasitansies in en rondom die windingstruktuur. Die berekende en EEM-gesimuleerde resultate word vergelyk met die gemeete waardes as 'n finale vlak van bekragtiging. Die metodes wat gebruik word om die verskillende modelparameters te bereken vergelyk goed met gemete waardes. Die nie-lineêre frekwensie-afhanklike verliese van transformatorwindings word ook ondersoek en 'n metode om hierdie in ag te neem is voorgestel en geïmplementeer. Die volledige voorgestelde modeleringsmetodiek in hierdie tesis, wat die berekening van die modelparameters, modelsintese en oplosingsalgoritme insluit word toegepas op 'n werklike gevallestudie. Die gevallestudie is uitgevoer op 'n lugkern-reaktor wat 'n skyftipe-kragtransformatorwinding. Die reaktor word onderwerp aan die standaard weerligimpuls golwe en die spanning al langs die winding word gemeet. Die berekende en gemete spanning golf vorms word met mekaar vergelyk in beide die frekwensie- en tyd-vlak. Uit die vergelyking blyk dit dat die model die werklike oorgangspanningsweergawe van die toetseenheid akkuraat verteenwoordig vir die frekwensie reeks van belang tydens standaard fabriekaanvaardingstoetse.

Thesis (MEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: The development of fast and efficient processors, programmable devices and high power semiconductors has led to the increased use of semiconductors directly in the power supply path in order to achieve strict power quality standards. New and advanced algorithms are used in the process and calculated on-line to bring about the required fast response to voltage variations. Losses in high voltage semiconductors increase with increased operating frequencies. A balance between semiconductor power losses and power quality is achieved through control of power semiconductor switching frequencies. A predictive control algorithm to achieve high power quality and limit the power losses in the high power semiconductor switches through switching frequency control is discussed for a tap switched voltage regulator. The quality of power, voltage regulator topology and the control algorithm are discussed. Simulation results of output voltage and current are shown when the control algorithm is used to control the regulator. These results are verified by practical measurements on a synchronous buck converter. / AFRIKAANSE OPSOMMING: Die ontwikkeling van vinnige en doeltreffende verwerkers, programmeerbare toestelle en hoëdrywings halfgeleiers het gelei tot 'n groter gebruik van halfgeleiers direk in die kragtoevoer pad om streng elektriese toevoer kwaliteit standaarde te bereik. Nuwe en gevorderde algoritmes word gebruik in die proses en word aan-lyn bereken om die nodige vinnige reaksie tot spanningswisselinge te gee. Verliese in hoë-spannings halfgeleiers verhoog met hoër skakel frekwensies. 'n Balans tussen die halfgeleier drywingsverliese en spanningskwalteit is behaal deur die skakel frekwensie in ag te neem in die beheer. 'n Voorspellinde-beheer algoritme om ‘n hoë toevoerkwaliteit te bereik en die drywingsverliese in die hoëdrywingshalfgeleier te beperk, deur skakel frekwensie te beheer, is bespreek vir 'n tap-geskakelde spanning reguleerder. Die toevoerkwaliteit, spanningsreguleerder topologie en die beheer algoritme word bespreek. Simulasie resultate van die uittree-spanning en stroom word getoon wanneer die beheer algoritme gebruik word om die omsetter te beheer. Hierdie resultate is deur praktiese metings op 'n sinkrone afkapper.

abstract: The modern era of consumer electronics is dominated by compact, portable, affordable smartphones and wearable computing devices. Power management integrated circuits (PMICs) play a crucial role in on-chip power management, extending battery life and efficiency of integrated analog, radio-frequency (RF), and mixed-signal cores. Low-dropout (LDO) regulators are commonly used to provide clean supply for low voltage integrated circuits, where point-of-load regulation is important. In System-On-Chip (SoC) applications, digital circuits can change their mode of operation regularly at a very high speed, imposing various load transient conditions for the regulator. These quick changes of load create a glitch in LDO output voltage, which hamper performance of the digital circuits unfavorably. For an LDO designer, minimizing output voltage variation and speeding up voltage glitch settling is an important task. The presented research introduces two fully integrated LDO voltage regulators for SoC applications. N-type Metal-Oxide-Semiconductor (NMOS) power transistor based operation achieves high bandwidth owing to the source follower configuration of the regulation loop. A low input impedance and high output impedance error amplifier ensures wide regulation loop bandwidth and high gain. Current-reused dynamic biasing technique has been employed to increase slew-rate at the gate of power transistor during full-load variations, by a factor of two. Three design variations for a 1-1.8 V, 50 mA NMOS LDO voltage regulator have been implemented in a 180 nm Mixed-mode/RF process. The whole LDO core consumes 0.130 mA of nominal quiescent ground current at 50 mA load and occupies 0.21 mm x mm. LDO has a dropout voltage of 200 mV and is able to recover in 30 ns from a 65 mV of undershoot for 0-50 pF of on-chip load capacitance. / Dissertation/Thesis / Masters Thesis Electrical Engineering 2016

[pt] A agregação dinâmica de reguladores de tensão de unidades geradoras coerentes, visando o cálculo de equivalentes dinâmicos para estudos de estabilidade transitória de sistemas de energia elétrica, é o objeto desta dissertação. A metodologia empregada para o cálculo de equivalentes dinâmicos apresenta três etapas: a identificação de geradores coerentes, a redução estática da rede e a agregação dinâmica dos modelos das unidades geradoras coerentes. A agregação dinâmica de um grupo de geradores coerentes consiste em representar este grupo através de uma ou mais unidades geradoras equivalentes. As unidades geradoras coerentes podem ser representadas por diferentes modelos de máquina síncrona, regulador de tensão, estabilizador, turbina e regulador de velocidade. Haverá, então, um modelo equivalente para cada componente da unidade geradora. Os parâmetros lineares de cada modelo equivalente são ajustados numericamente através do método de Levenberg-Marquardt para resolver o problema de otimização multivariável. O objetivo principal é a determinação do melhor modelo equivalente para uma dada composição de modelos de reguladores de tensão num grupo de unidades geradoras coerentes. O sistema teste New England é utilizado para avaliar a metodologia empregada, observando-se os desempenhos dinâmicos dos equivalentes propostos. Serão considerados modelos do banco de dados de estabilidade do sistema elétrico brasileiro. / [en] This dissertation deals with the problem of dynamic aggregation of voltage regulators of coherent generating units to calculate dynamic equivalents for power system transient stability studies. The methodology used to calculate coherencybased dynamic equivalents has three basic steps: the identification of the coherent groups of generating units, the static reduction of the external network and the dynamic aggregation of coherent generating unit models. The dynamic aggregation of a group of coherent generating units consists of the representation of this group by one or more equivalent generating units. The coherent generating units can be represented by different models of synchronous machine, voltage regulator, stabilizer, turbine and speed governor. There will be an equivalent model for each component of the generating unit. The linear parameters of the equivalent models are numerically adjusted using the Levenberg-Marquardt method in order to solve the multivariable optimization problem. The main objective is the determination of the best equivalent model for a given composition of voltage regulator models in a group of coherent generating units. The New England system is used to evaluate the dynamic performance of the equivalents. The voltage regulator models considered in this work are in the Brazilian electrical system stability database. The swing curves of the internal system generators obtained with the equivalent system are compared with those obtained with the simulation of the complete system.

The reactive power and voltage level control in distribution networks are routine in a power. The customer s voltage levels legislation, allows to the customers with voltage levels out of the limits stipulated by Brazilian Electricity Regulatory Agency receive financial compensation by inadequate service. The coordinated adjust of the equipment, capacitor banks and voltage regulators allocation along the feeders are usual actions to ensure proper voltage levels to the customers. In Brazil, distribution networks are usually large with numerous and long low-voltage circuits. Based on the networks geo-referenced registers, the proposed algorithm uses computational intelligence techniques to optimize voltage levels and reactive power, considering the primary and secondary network distribution. This work provides a tool that will allow the specialist obtain the most cost-effective to simultaneous capacitor banks and voltage regulators allocation, optimizing the primary and secondary voltage levels in distributions networks, minimizing operating costs and losses. / O controle do perfil de tensão nas redes de distribuição é uma tarefa rotineira em distribuidoras de energia. Com uma legislação rígida sobre os níveis de tensão, as unidades consumidoras que estão com o fornecimento fora dos padrões estipulados pela ANEEL (Agência Nacional de Energia Elétrica) recebem compensação financeira pelo serviço inadequado. O ajuste coordenado dos equipamentos e a alocação de banco de capacitores e reguladores de tensão ao longo dos alimentadores são ações práticas para garantir níveis de tensão adequados aos consumidores. No Brasil, as redes de distribuição são longas com inúmeros circuitos de baixa tensão igualmente extensos. Tendo como base o cadastro georeferenciado das redes, o algoritmo proposto neste trabalho utiliza técnicas de inteligência computacional para otimizar os níveis de tensão e reativos no sistema de distribuição, considerando as redes primárias e secundárias de distribuição. Este trabalho traz uma ferramenta que permitirá ao especialista obter a melhor relação custo-benefício na alocação simultânea de bancos de capacitores e reguladores de tensão, otimizando os níveis de tensão nas redes primárias e secundárias, minimizando custos operacionais e perdas.

Orientador: José Antonio Siqueira Dias / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-26T13:53:46Z (GMT). No. of bitstreams: 1 Tercariol_WalterLuis_D.pdf: 1322557 bytes, checksum: 4f45518a1a62907cd9a61afa627408c3 (MD5) Previous issue date: 2014 / Resumo: Este trabalho visa compilar três contribuições na melhoria dos projetos de reguladores de tensão com unidades de bombeamento de carga embutidos (células elevadoras de tensão Dickson - BC). A primeira aborda uma técnica inovadora de arranque na partida deste módulo elevador quando habilitado. Este projeto se refere à aceleração da inicialização do modulo BC, tendo como objetivo a diminuição do intervalo de tempo da rampa ascendente da tensão de saída Vo até atingir o nível alvo de regulação. A técnica consiste em gerenciar o aumento da freqüência do relógio de bombeamento entregue as unidades de bombeamento durante a fase de subida, quando a regulação estiver estabelecida o sistema se regenera voltando ao estado original de freqüência de bombeamento natural. Uma segunda proposta inovadora de projeto é referente à homogeneização e redução da aleatoriedade da ondulação da tensão de saída Vo, referente ao regulador com o modulo BC embutido, baseado em comparadores com trava, com proposta de redução do erro de comparação devido ao efeito aleatório durante o estagio de comparação comumente encontrado neste tipo de abordagem, a técnica consiste em suprimir o acoplamento capacitivo nocivo durante a fase de isolamento elétrico no processo de comparação mantendo o espelho de corrente do comparador na região de saturação. Esta técnica visa proporcionar uma redução significativa da capacitância de desacoplamento utilizada para filtragem da tensão Vo. Uma terceira e última contribuição é referente a uma inovadora técnica de medição indireta da tensão de saída Vo do regulador com módulo BC baseada em uma medida simples e precisa dos pares tensão da porta e fonte (VPS) e corrente elétrica do dreno (Idreno) de um dispositivo NMOS de alta tensão adicionado de modo que duas tensões conhecidas (preestabelecidas) são aplicadas na porta do dispositivo e as respectivas correntes de dreno são mensuradas e uma terceira desconhecida (oriunda do regulador elevador BC) desconhecida pode ser extrapolada de forma simples. Esta técnica visa ser útil para medição de reguladores de baixa potencia pois o carregamento do regulador (Vo) é quase nulo.Todas as inovações e melhorias propostas foram analisadas em veículos de teste (silício) e com as provas de conceito, feitas em simulações elétricas / Abstract: This work aims to compile contributions in improving designs based on voltage regulators with voltage elevator with built-in charge pump CP. The first deals with an innovative technique rump-up this module when enabled. This project refers to the acceleration of startup the CP module, aiming at the reduction of the period of stabilization of the ramp output voltage Vo to the level of regulation target. The technique is to manage increasing the frequency of pumping clock during the phase of rump up and when the setting established the system regenerates back to the original state pumping frequency. A second innovative project proposal was made on the homogenization and reduction of the ripple of the output voltage Vo, referring to the regulator with the |CP module, based on latch comparators , alignment error reduction proposal because of the random effect during the stage comparison commonly found in this type of approach, the technique is to remove the harmful capacitive coupling during electrical isolation phase on the comparison keeping the comparator current mirror in saturation region. This technique aims to provide a significant reduction in the decoupling capacitance used for filtering the voltage Vo. A third and final contribution is related to an innovative technique of indirect measurement of the output voltage Vo of the regulator module CP, based on a simple and accurate measure of the gate voltage and couples the drain electric current of a high voltage NMOS device / Doutorado / Eletrônica, Microeletrônica e Optoeletrônica / Doutor em Engenharia Elétrica

This master’s thesis deals with the design of integrated voltage regulator. Topologies of linear voltage regulators and their stability are discussed. Part of the thesis deals with description and simulation of blocks of selected regulator topology. The thesis describes the difficulties of integrated circuit design in the automotive industry. The electrical scheme of the designed regulator is explained. The work also focuses on the stability of designed regulator. Then presents simulations. It discusses the layout of integrated circuits and the designed voltage regulator.