D.Ing. / This thesis initially reviews current empirical and probabilistic electrical load models available to distribution design engineers today to calculate voltage regulation levels in low voltage residential, commercial and light industrial consumer networks. Although both empirical and probabilistic techniques have extensively been used for residential consumers in recent years, it has been concluded that commercial and light industrial consumer loads have not been a focus area of probabilistic load study for purposes of low voltage feeder design. However, traditional empirical techniques, which include adjustments for diversity to accommodate non-coincidental electrical loading conditions, have generally been found to be applied using in-house design directives with only a few international publications attempting to address the problem. This work defines the light industrial group of consumers in accordance with its international Standard Industrial Classification (SIC) and presents case studies on a small group of three different types of light industrial sub-classes, It is proposed and proved that the electrical load models can satisfactorily be described as beta-distributed load current models at the instant of group or individual maximum power demand on typical characteristic 24-hour load cycles. Characteristic mean load profiles were obtained by recording repetitive daily loading of different sub-classes, ensuring adequate sample size at all times. Probabilistic modelling of light industrial loads using beta-distributed load current at maximum demand is a new innovation in the modelling of light industrial loads. This work is further -complemented by the development of a new probabilistic summation algorithm in spreadsheet format. This algorithm adds any selected number of characteristic load current profiles, adjusted for scale, power factor, and load current imbalance, and identifies the combined instant of group or system maximum demand. This spreadsheet also calculates the characteristic beta pdf parameters per phase describing the spread and profile of the combined system loading at maximum demand. These parameters are then conveniently used as input values to existing probabilistic voltage regulation algorithms to calculate voltage regulation in single-, bi- and three-phase low voltage distribution networks.

As redes secundárias de distribuição são item de extrema importância no processo de levar a energia produzida de uma fonte até o consumidor final. Dentro de uma Empresa Concessionária de Distribuição de Energia Elétrica o setor de planejamento, juntamente com o grupo técnico, deve realizar o planejamento dos investimentos necessários nos níveis de alta, média e baixa tensão, sendo que para a baixa tensão (redes secundárias de distribuição), normalmente utilizam-se os dados históricos e a média de investimentos dos últimos anos (de três a cinco últimos anos). Em geral não são encontrados nestas Empresas os cadastramentos das redes secundárias de distribuição ou então, quando estes existem, muitas vezes não são confiáveis. Neste ponto, esta dissertação de mestrado apresentará, aplicará e discutirá os resultados de uma metodologia de geração de redes secundárias de distribuição a partir dos dados das redes primárias de distribuição (média tensão) e dos ativos da Empresa, tendo como foco os investimentos necessários para estas dentro do planejamento agregado de investimentos. O trabalho proposto visa criar condições para que as Empresas enquadradas na situação anterior possam realizar o seu planejamento de baixa tensão valendo-se da aplicação de uma metodologia capaz de gerar tais redes. Uma vez criadas, tais redes serão inseridas dentro de um software de planejamento agregado de investimentos que fornecerá o valor total das aplicações necessárias para os próximos dez anos (planejamento decenal – longo prazo). Ao final do processo, poderá ser observado que os resultados obtidos são muito próximos dos valores esperados para as redes secundárias reais e, com isto, a dissertação discutirá como a metodologia foi implementada, os detalhes da aplicação e, até mesmo, todo o processo de planejamento para três Empresas Concessionárias de Distribuição de Energia Elétrica. Já de posse dos resultados, poderá afirmar-se que o processo produziu valores de muito boa aderência e, assim, os investimentos obtidos para as redes secundárias poderão ser aceitos pelo grupo de planejamento da Empresa. Como conseqüência dos valores de investimentos obtidos para os dez anos, poderão ser observados ainda, guardadas algumas considerações especiais, os valores dos custos marginais de baixa tensão, item de grande importância no planejamento de redes de distribuição. / The low voltage distribution networks are an item of extreme importance in the process of delivering the produced energy from a plant (supply) to the final consumer. In an Electric Power Distribution Company the planning group (sector), together with the technical group, must accomplish the planning of the necessary investments in the high voltage, medium voltage and low voltage levels, and for low voltage distribution networks, usually the historical data and the average of investments of the last years are used (from three to last five years). In general the databases of low voltage networks are not found in these Companies or then, when these exist, a lot of times they are not reliable. For this, this article will show, apply and discuss the results of a methodology for generating low voltage distribution networks starting from the database of the medium voltage distribution networks and of the assets of the Company, having as focus the necessary investments for these networks in planning of investments. The proposed work wishes to create conditions so that the Companies that are in the previous situation can accomplish their planning on low voltage distribution networks using a methodology capable to generate such nets. Once created, such nets will be inserted in a software of planning of investments that will supply the total amount of investments for them for the next ten years (long period planning). In the end of the process, it will be observed that the obtained results are very close to the expected values for the real low voltage distribution networks and, with this, the article will discuss how the methodology was implemented, the details of the application and, even, the whole planning process for three Electric Power Distribution Companies. With the results, it will be affirmed that the process produces values of very good adherence and, for this, the investments obtained for low voltage distribution networks can be accepted by the planning group in the Company. As a consequence of the investments values obtained for the ten years, it will be able to be observed, kept some special considerations, the values of the marginal costs of low voltage, item of great importance in the planning of distribution networks.

As redes secundárias de distribuição são item de extrema importância no processo de levar a energia produzida de uma fonte até o consumidor final. Dentro de uma Empresa Concessionária de Distribuição de Energia Elétrica o setor de planejamento, juntamente com o grupo técnico, deve realizar o planejamento dos investimentos necessários nos níveis de alta, média e baixa tensão, sendo que para a baixa tensão (redes secundárias de distribuição), normalmente utilizam-se os dados históricos e a média de investimentos dos últimos anos (de três a cinco últimos anos). Em geral não são encontrados nestas Empresas os cadastramentos das redes secundárias de distribuição ou então, quando estes existem, muitas vezes não são confiáveis. Neste ponto, esta dissertação de mestrado apresentará, aplicará e discutirá os resultados de uma metodologia de geração de redes secundárias de distribuição a partir dos dados das redes primárias de distribuição (média tensão) e dos ativos da Empresa, tendo como foco os investimentos necessários para estas dentro do planejamento agregado de investimentos. O trabalho proposto visa criar condições para que as Empresas enquadradas na situação anterior possam realizar o seu planejamento de baixa tensão valendo-se da aplicação de uma metodologia capaz de gerar tais redes. Uma vez criadas, tais redes serão inseridas dentro de um software de planejamento agregado de investimentos que fornecerá o valor total das aplicações necessárias para os próximos dez anos (planejamento decenal – longo prazo). Ao final do processo, poderá ser observado que os resultados obtidos são muito próximos dos valores esperados para as redes secundárias reais e, com isto, a dissertação discutirá como a metodologia foi implementada, os detalhes da aplicação e, até mesmo, todo o processo de planejamento para três Empresas Concessionárias de Distribuição de Energia Elétrica. Já de posse dos resultados, poderá afirmar-se que o processo produziu valores de muito boa aderência e, assim, os investimentos obtidos para as redes secundárias poderão ser aceitos pelo grupo de planejamento da Empresa. Como conseqüência dos valores de investimentos obtidos para os dez anos, poderão ser observados ainda, guardadas algumas considerações especiais, os valores dos custos marginais de baixa tensão, item de grande importância no planejamento de redes de distribuição. / The low voltage distribution networks are an item of extreme importance in the process of delivering the produced energy from a plant (supply) to the final consumer. In an Electric Power Distribution Company the planning group (sector), together with the technical group, must accomplish the planning of the necessary investments in the high voltage, medium voltage and low voltage levels, and for low voltage distribution networks, usually the historical data and the average of investments of the last years are used (from three to last five years). In general the databases of low voltage networks are not found in these Companies or then, when these exist, a lot of times they are not reliable. For this, this article will show, apply and discuss the results of a methodology for generating low voltage distribution networks starting from the database of the medium voltage distribution networks and of the assets of the Company, having as focus the necessary investments for these networks in planning of investments. The proposed work wishes to create conditions so that the Companies that are in the previous situation can accomplish their planning on low voltage distribution networks using a methodology capable to generate such nets. Once created, such nets will be inserted in a software of planning of investments that will supply the total amount of investments for them for the next ten years (long period planning). In the end of the process, it will be observed that the obtained results are very close to the expected values for the real low voltage distribution networks and, with this, the article will discuss how the methodology was implemented, the details of the application and, even, the whole planning process for three Electric Power Distribution Companies. With the results, it will be affirmed that the process produces values of very good adherence and, for this, the investments obtained for low voltage distribution networks can be accepted by the planning group in the Company. As a consequence of the investments values obtained for the ten years, it will be able to be observed, kept some special considerations, the values of the marginal costs of low voltage, item of great importance in the planning of distribution networks.

The objective of the proposed research is to investigate the design of Self-Aware Radio Frequency Circuits and Wireless Communication Systems that can adapt to environmental and process variations to always operate at minimum power levels possible, extending battery life. The explosive growth of portable battery operated devices has mandated design of low power circuits and systems to prolong battery life. These devices fabricated in modern nanoscale CMOS technologies suffer from severe process variation due to the reduced controllability of the fabrication process, causing yield loss. This calls for integrated low power and process tolerant design techniques, or design of systems that can adapt to its process and environment to maintain its performance while minimizing power consumption. Currently, most of the wireless circuits are designed to meet minimum quality-of-service requirements under worst-case wireless link conditions (interference, noise, multi-path effects), leading to high power consumption when the channel is better than worst-case. In this research, we develop a multi-dimensional adaptation approach for wireless transmitters and receivers that optimally trades-off power vs. performance across temporally changing operating conditions by concurrently tuning control parameters in the RF front end to lower power consumption. Tunable circuits (e.g. LNA) with built-in tuning knobs providing independent controllability of important specifications allow optimal adaptation. Process sensing using intelligent test and calibration facilitates yield improvement and the design of process tolerant environment adaptive systems. Low cost testing methodologies are developed for identification of the health of the wireless circuit/system. These are used in conjunction with tuning algorithms that tune a wireless system under process variation to meet performance specifications and recover yield loss. This testing and adaptation is performed once during the post manufacture test/tune phase to compensate for manufacturing variations. This can also be applied periodically during in field operation of a device to account for performance degradation due to ageing. Finally, process tolerant environment adaptive systems are designed.

Dissertation (PhD)--University of Stellenbosch, 2000. / ENGLISH ABSTRACT: The purpose of this dissertation is to provide methods for designing and managing low voltage residential feeders. These methods can be applied to the problem of planning residential networks under uncertainty while ensuring least life-cycle costs. By analysing collected load data from various communities in South Africa, a new probabilistic model for representing the load uncertainty of residential consumers was derived. This model uses the beta probability distribution to describe individual consumer loads over a period of time. Methods for combining the loads in linear combinations were used to derive a new probabilistic voltage regulation calculation procedure. This new method is different from previously developed voltage calculation methods in that it can be used to estimate the probable voltage performance of a feeder over a period of time. A simplification of the method is proposed which allows it to be implemented in any commercial spreadsheet program. The new probabilistic load model was also applied to the problem of calculating resistive losses in residential low voltage feeders. A new probabilistic method was formulated and this method can be used to estimate the probable range of resistive loss in a feeder for a period of time. This method is simple enough to implement in a commercial spreadsheet program. Probabilistic information about network and load parameter uncertainty is seldom available and these uncertainties are best modelled using fuzzy numbers. The probabilistic calculation methods cannot represent these uncertainties and only after applying a fuzzy-probabilistic approach can both types of uncertainties be used. This is a significant enhancement to the current methods and ensures that the uncertainty about the calculated results is realistically represented. The specification of load parameters for the methods was significantly simplified following a regression analysis of collected load data from South African communities. By specifying the distribution of the consumption of individual consumers in a community, the other load parameters can be estimated using a set of fitted linear regression equations. This greatly reduces the burden of specifying the load parameters and makes it possible for the proposed calculation methods to be applied to the design of new feeders in practice. The distribution of the consumption of individual consumers can be specified using the average and the standard deviation of the consumptions of individual consumers. Accurate estimates of these parameters can be obtained from sales information and can be used to manage existing networks effectively. Using the sales information with the proposed methods enables more cost-effective upgrades of existing feeders low voltage feeders. The identification of potential problems in existing low voltage networks is also possible if the layout of the feeders in a community is known. The use of the proposed methods is illustrated in step-by-step fashion. Typical input parameters are used and all the required calculations with intermediate results are presented. / AFRIKAANSE OPSOMMING: Die doel van hierdie proefskrif is die daarstelling van residensiële laagspanningsnetwerk ontwerp- en bestuursmetodes. Hierdie metodes kan toegepas word vir die beplanning van residensiële laagspanningsnetwerke waar onsekerheid bestaan oor toekomstige kragverbruik en die spesifikasie van die netwerkparameters. Lasdata, wat versamel is in verskeie Suid Afrikaanse gemeenskappe, is geanaliseer en 'n nuwe probabilistiese modellering van die onsekerheid oor die kragverbruik van residensiële verbruikers is ontwikkel. Gebruik is gemaak van die beta waarskynlikheidsdightheidsfunksie om die tydsgebonde kragverbruik van die verbruikers voor te stel. 'n Nuwe probabilistiese spanningsvalberekeningsmetode is ontwikkel en die metode maak gebruik van liniêre kombinasies van die lasstrome van die verbruikers. Die verskil tussen hierdie metode en bestaande metodes is dat dit die tydsgebonde waarskynlikheid van die spanningsregulasie van 'n kabel kan bereken. 'n Vereenvoudiging van die metode is ook verkry en dit kan in enige kommersiële sigblad geïmplementeer word. Die probabilistiese lasstroommodel is ook gebruik om 'n nuwe probabilistiese energieverliesberekeningsmetode te ontwikkel. Hierdie metode kan gebruik word om die tydsgebonde waarskynlikhede van 'n reeks van moontlike energieverlieswaardes te bereken. Die metode is eenvoudig genoeg om in enige kommersiële sigblad te implementeer. Onsekerheid oor die spesifikasie van die parameters van die nuwe metodes asook die netwerkparameters kan nie met probabilistiese metodes voorgestel word nie, aangesien inligting oor die waarskynlikhede van parameters selde beskikbaar is. Hierdie onsekerhede kan beter voorgestel word deur die gebruik van sogenaamde "fuzzy"-metodes. Die voorgestelde probabilistiese metodes is aangepas om hierdie tipe onsekerhede ook in ag te neem. "Fuzzy-probabilistic" metodes is gebruik vir dié aanpassings en word beskou as 'n noemenswaardige verbetering van die metodes. Die verbeterde metodes verkaf meer realistiese voorstellings van die onsekerheid oor berekende resultate. 'n Statisitiese analise van Suid Afrikaanse lasdata het 'n vereenvoudiging van die spesifisering van die parameters van die nuwe metodes tot gevolg gehad. Die waarskynlikheidsverspreiding van die energieverbruik van huishoudelike verbruikers kan gebruik word om akkurate skattings van die ander parameters te verkry. Hierdie vereenvoudiging het tot gevolg dat die nuwe metodes vir praktiese netwerkontwerp gebruik kan word. Die waarskynlikheidsverpreiding van die energieverbruik van verbuikers is beskikbaar in die vorm van energieverkope en kan gebruik word vir die effektiewe bestuur en opgradering van bestaande netwerke. As die uitleg van die bestaande netwerke in 'n gemeenskap beskikbaar is, kan die inligting wat bevat is in die energieverkope gebruik word om probleme in bestaande netwerke te identifiseer. Al die voorgestelde metodes is stap vir stap uiteengesit met voorbeelde van al die berekeninge met tipiese waardes.

Approved for public release, distribution is unlimited / 100 m/s). Low voltage electrical contact was not maintained for some experimental shots and non-parallel rails were the suspected cause. In this thesis, we used a non-contact capacitive sensor to determine rail spacing to within 2/kAcm10mael, so that the rails will be parallel within small tolerances. Several rails were used in these experiments: 75-25 copper-tungsten, chromium-plated 75-25 Cu-W, and chromium-plated pure copper rails. Improving the control of rail spacing and parallelity did not ensure low-voltage electrical contact for our configurations. The largest damage was observed for chromium-plated copper rails and the least damage occurred for chromium-plated 75-25 Cu-W rails. / Lieutenant, United States Navy

A dissertation submitted to the Faculty of Engineering, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science in Engineering. Johannesburg 1996 / The use of computer-based tools in the design of electrical distribution networks results in the cost effective production and implementation of designs. This is because they help automate time-consuming routine tasks and enable the optimisation of certain aspects of a network design. The production of a tool that performs an optimisation on the low voltage (LV) portion of a distribution network is discussed. It uses the influence that a network's topology has on its associated cost, by applying a search that modifies the topology to result in a minimum cost. The modification of the network's topology is achieved through changing junction positions to alternative locations. It operates on an entire radial LV network, and therefore considers the coupling between junctions in the same network. The user of the tool must specify the alternative locations for each junction in the network, as well as information about the network, such as cable lengths and cable types. The search algorithm is based on an adaptation of the branch and bound method, which is a reduced search algorithm. It has been chosen as opposed to an exhaustive search algorithm to reduce computational requirements. The tool Is most useful for optimising completely underground distribution systems. Test results revealed a 7% saving in the cost of cables for a specific case study. The software has been developed with the application of object-oriented analysis and design within an ISO 9001 accredited software development environment. iii / GR2017

Chan Shek-Hang. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (leaves 94-97). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgement --- p.iv / Table of Contents --- p.v / List of Figures --- p.ix / List of Tables --- p.xiii / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Overview --- p.1 / Chapter 1.2 --- Significance of the research --- p.2 / Chapter 1.3 --- Objectives --- p.3 / Chapter 1.4 --- Thesis outline --- p.4 / Chapter Chapter 2 --- Background theory --- p.5 / Chapter 2.1 --- Introduction --- p.5 / Chapter 2.2 --- Electrical properties of MOS transistors --- p.5 / Chapter 2.2.1 --- Strong inversion --- p.5 / Chapter 2.2.2 --- Weak inversion --- p.6 / Chapter 2.2.3 --- Moderate inversion --- p.8 / Chapter 2.2.4 --- The transistors biased in this work --- p.8 / Chapter 2.3 --- Rail-to-rail signals --- p.8 / Chapter 2.4 --- Rail-to-rail operational amplifier --- p.10 / Chapter 2.4.1 --- Rail-to-rail differential input pairs --- p.10 / Chapter 2.4.1.1 --- Principle --- p.10 / Chapter 2.4.1.2 --- Two stage operational amplifier --- p.13 / Chapter 2.4.2 --- Folded-cascode gain stage --- p.14 / Chapter 2.5 --- The nature of operational amplifier distortion --- p.16 / Chapter 2.5.1 --- The total harmonic distortion --- p.17 / Chapter Chapter 3 --- Constant transconductance rail-to-rail input stage --- p.20 / Chapter 3.1 --- Introduction --- p.20 / Chapter 3.2 --- Review of constant-gm input stage --- p.20 / Chapter 3.2.1 --- Rail-to-rail input stages with current-based gm control --- p.20 / Chapter 3.2.1.1 --- gm controlled by three-times current mirror --- p.21 / Chapter 3.2.1.2 --- gm controlled by square root current control --- p.23 / Chapter 3.2.1.3 --- gm controlled by using current switches only --- p.25 / Chapter 3.2.2 --- Rail-to-rail input stages with voltage-based gm control --- p.28 / Chapter 3.2.2.1 --- gm controlled by an ideal zener diode --- p.28 / Chapter 3.2.2.2 --- gm controlled by two diodes --- p.30 / Chapter 3.2.2.3 --- gm controlled by an electronic zener --- p.31 / Chapter 3.3 --- Conclusion --- p.32 / Chapter Chapter 4 --- Proposed constant transconductance rail-to-rail input stage --- p.34 / Chapter 4.1 --- Introduction --- p.34 / Chapter 4.2 --- Principle of the conventional input stage --- p.35 / Chapter 4.2.1 --- Translinear circuit --- p.35 / Chapter 4.3 --- Previous work --- p.36 / Chapter 4.3.1 --- Input bias circuit --- p.36 / Chapter 4.3.2 --- Weak inversion operation --- p.38 / Chapter 4.3.3 --- Power up problem --- p.43 / Chapter 4.4 --- Operational transconductance amplifier with proposed input biased stage --- p.47 / Chapter 4.4.1 --- Proposed input biased stage architecture --- p.47 / Chapter 4.4.2 --- Proposed input biased stage with 2 gm control circuits --- p.50 / Chapter 4.4.3 --- OTA with proposed input biased stage --- p.51 / Chapter Chapter 5 --- Simulation Results --- p.54 / Chapter 5.1 --- Introduction --- p.54 / Chapter 5.2 --- DC bias simulation --- p.54 / Chapter 5.2.1 --- Total transconductance variation --- p.54 / Chapter 5.2.2 --- Power consumption --- p.56 / Chapter 5.3 --- AC simulation --- p.56 / Chapter 5.3.1 --- Open-loop gain --- p.57 / Chapter 5.3.2 --- Gain-bandwidth product --- p.59 / Chapter 5.3.3 --- Phase margin --- p.59 / Chapter 5.4 --- Transient simulation --- p.60 / Chapter 5.4.1 --- Voltage follower --- p.60 / Chapter 5.4.2 --- Total harmonic distortion --- p.62 / Chapter 5.4.3 --- Step response --- p.65 / Chapter 5.5 --- Conclusion --- p.67 / Chapter Chapter 6 --- Layout Consideration --- p.68 / Chapter 6.1 --- Introduction --- p.68 / Chapter 6.2 --- Substrate tap --- p.68 / Chapter 6.3 --- Input protection circuitry --- p.69 / Chapter 6.4 --- Die micrographs of the OTA --- p.71 / Chapter Chapter 7 --- Measurement Results --- p.74 / Chapter 7.1 --- Introduction --- p.74 / Chapter 7.2 --- DC bias measurement results --- p.74 / Chapter 7.2.1 --- Total transconductance variation --- p.74 / Chapter 7.2.2 --- Power consumption --- p.77 / Chapter 7.3 --- AC measurement results --- p.78 / Chapter 7.3.1 --- Open-loop gain --- p.78 / Chapter 7.3.2 --- Gain-bandwidth product --- p.81 / Chapter 7.3.3 --- Phase margin --- p.81 / Chapter 7.4 --- Transient measurement result --- p.82 / Chapter 7.4.1 --- Voltage follower --- p.82 / Chapter 7.4.2 --- Total harmonic distortion --- p.85 / Chapter 7.4.3 --- Step response --- p.87 / Chapter 7.5 --- Conclusion --- p.88 / Chapter Chapter 8 --- Conclusion --- p.90 / Chapter 8.1 --- Contribution --- p.90 / Chapter 8.2 --- Further development --- p.91 / Chapter Chapter 9 --- Appendix --- p.92 / Chapter Chapter 10 --- Bibliography --- p.94

Ho, Marco. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Sun, Lei. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.