VJ表演隱藏著一種矛盾性。VJ表演之觀眾特徵，較常表現出非主流的品味，傾向於追求與眾不同的體驗，與對於自主權的掌握展現較高的積極性。然而享受音樂表演意味著某種程度的沈浸與忘我，在觀賞表演時需暫時捨棄自身的自主權與主體性方有可能真正享受其中，這之間便產生了控制與被控制的矛盾。當互動科技的元素介入到VJ表演時，這種矛盾性就會更加明顯，甚至被揭露與強調。互動科技的加入旨在過程中使人們能夠參與，讓人們擁有做決定或影響表演的權力。故互動的VJ表演具有控制權矛盾之特徵，而這樣的矛盾性應當被表演設計者所發現並探索。本研究希望透過理論爬梳與作品實踐，探索互動加入在VJ表演時如何提高觀眾的參與感。於是如何盡量減少互動所造成的干擾性以完成一場互動表演，便成為本研究關心的一項重點。 　　在內容主題上，台灣民間信仰是關於控制與被控制一個很好的轉喻。故此計畫將設計一個以台灣民間信仰為主題的互動VJ表演，並利用台灣民間信仰來反映觀眾主體性矛盾與控制權矛盾的不同面相。

M. Tech. Electrical Engineering. / Discusses the practical management of electrical networks, no perfect monitoring of an electrical power system state is available, either because it is expensive or technically unfeasible due to the poor quality of the available measurements in the control centre. To have a stable network, the control centre must receive the network information to be able to provide a proper security in unforeseen situation. As a power system network is a complex and a non-linear system, it is important to use more advanced methods for its analysis and control in a real time environment. The aim of this research work is therefore, to apply several state estimation algorithms using artificial intelligence by developing their mathematical models for the purpose of comparing their performances in estimating the state variable of the power system. The three types of state estimation algorithms investigated for this research work are: the Particle Swarm Optimisation (PSO), the Genetic Algorithm (GA) and the Newton method for state estimation (NSE).

Research in the field of random access protocols for narrow-band systems started as early as the 1970s with the introduction of the ALOHA protocol. From the research done in slotted narrow-band systems, it is well known that contention results in all the packets involved in the contention being unsuccessful. However, it has been shown that in the presence of unequal power levels, ore of the contending packets may be successful. Ibis is a phenomenon called capture. Packet capture has been shown to improve the performance of slotted narrow-band systems. Recently, much work has been done in the analysis of spread-spectrum ALOHA type code-division multiple access (CDMA) protocols. The issue of designing power control techniques to improve the performance of CDMA systems by reducing multiple access interference (MAl) has been a subject of much research. It has been shown that in the presence of power control schemes, the performance of spread-ALOHA CDMA systems is improved. However, it is also widely documented that the design of power control schemes capable of the ideal of compensation of radio propagation techniques is not possible for various reasons, and hence the imperfections in power control. None of the research known to the author has looked at capture in spread-ALOHA systems, and to a greater extent, looked at expressions for the performance of spreadALOHA systems in the presence of capture. In this thesis we introduce spread-ALOHA systems with capture as a manifestation of the imperfections in power control. We propose novel expressions for the computation of the perfonnance ofspread-ALOHA systems with capture. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, 2005.

The objective of the proposed research is to develop a cost-effective power flow controller to improve the utilization and reliability of the existing transmission, sub-transmission, and distribution networks. Over the last two decades, electricity consumption and generation have continually grown at an annual rate of around 2.5%. At the same time, investments in the Transmission and Distribution (T&D) infrastructure have steadily declined. Further, it has become increasingly difficult and expensive to build new power lines. As a result, the aging power-grid has become congested and is under stress, resulting in compromised reliability and higher energy costs. In such an environment it becomes important that existing assets are used effectively to achieve highest efficiency. System reliability is sacrosanct and cannot be compromised. Utility system planners are moving from radial towards networked systems to achieve higher reliability, especially under contingency conditions. While enhancing reliability, this has degraded the controllability of the network, as current flow along individual lines can no longer be controlled. The transfer capacity of the system gets limited by the first line that reaches the thermal capacity, even when majority of the lines are operating at a fraction of their capacity. The utilization of the system gets further degraded as the lines are operated with spare capacity to sustain overloads under contingencies. Market efficiency is also sub-optimal, with congestion on key corridors restricting the low-cost generators to connect to the end users, resulting in higher electricity prices for the consumers. The proposed technology offers the capability to realize a controllable meshed-network, with the ability to utilize static and dynamic capacity of the grid to provide system-wide benefits, including- increased line and system-capacity utilization, increased reliability, improved operation under contingencies, and rapid implementation. It would allow a broadening of the energy market, permitting owners to direct how energy flows on their wires, and making it easier to connect to new sources of generation.

The object of this research is to optimize the overall power system performance using FACTS devices. Particularly, it is intended to improve the reliability, and the performance of the power system considering steady state operating condition as well as the system subjected to small and large disturbances. The methodology proposed to achieve this goal corresponds to an enhanced particle swarm optimizer (Enhanced-PSO) that is proven in this work to have several advantages, in terms of accuracy and computational effort, as compared with other existing methods. Once the performance of the Enhanced PSO is verified, a multi-stage PSO-based optimization framework is proposed for optimizing the power system reliability (N-1 contingency criterion). The algorithm finds optimal settings for present infrastructure (generator outputs, transformers tap ratios and capacitor banks settings) as well as optimal control references for distributed static series compensators (DSSC) and optimal locations, sizes and control settings for static compensator (STATCOM) units. Finally, a two-stage optimization algorithm is proposed to improve the power system performance in steady state conditions and when small and large perturbations are applied to the system. In this case, the algorithm provides optimal control references for DSSC modules, optimal location and sizes for capacitor banks, and optimal location, sizes and control parameters for STATCOM units (internal and external controllers), so that the loadability and the damping of the system are maximized at minimum cost. Simulation results throughout this research show a significant improvement of the power system reliability and performance after the system is optimized.

“Hardware in the Loop” (HIL) testing is widely used in the automotive industry. The sophisticated electronic control units used for vehicle control are usually tested and evaluated using HIL-simulations. The HIL increases the degree of realistic testing of any system. Moreover, it helps in designing the structure and control of the system under test so that it works effectively in the situations that will be encountered in the system. Due to the size and the complexity of interaction within a power network, most research is based on pure simulation. To validate the performance of physical generator or protection system, most testing is constrained to very simple power network. This research, however, examines a method to test power system hardware within a complex virtual environment using the concept of the HIL. The HIL testing for electronic control units and power systems protection device can be easily performed at signal level. But performance of power systems equipments, such as distributed generation systems can not be evaluated at signal level using HIL testing. The HIL testing for power systems equipments is termed here as ‘Power Network in the Loop’ (PNIL). PNIL testing can only be performed at power level and requires a power amplifier that can amplify the simulation signal to the power level. A power network is divided in two parts. One part represents the Power Network Under Test (PNUT) and the other part represents the rest of the complex network. The complex network is simulated in real time simulator (RTS) while the PNUT is connected to the Voltage Source Converter (VSC) based power amplifier. Two way interaction between the simulator and amplifier is performed using analog to digital (A/D) and digital to analog (D/A) converters. The power amplifier amplifies the current or voltage signal of simulator to the power level and establishes the power level interaction between RTS and PNUT. In the first part of this thesis, design and control of a VSC based power amplifier that can amplify a broadband voltage signal is presented. A new Hybrid Discontinuous Control method is proposed for the amplifier. This amplifier can be used for several power systems applications. In the first part of the thesis, use of this amplifier in DSTATCOM and UPS applications are presented. In the later part of this thesis the solution of network in the loop testing with the help of this amplifier is reported. The experimental setup for PNIL testing is built in the laboratory of Queensland University of Technology and the feasibility of PNIL testing has been evaluated using the experimental studies. In the last section of this thesis a universal load with power regenerative capability is designed. This universal load is used to test the DG system using PNIL concepts. This thesis is composed of published/submitted papers that form the chapters in this dissertation. Each paper has been published or submitted during the period of candidature. Chapter 1 integrates all the papers to provide a coherent view of wide bandwidth switching amplifier and its used in different power systems applications specially for the solution of power systems testing using PNIL.

[Truncated abstract] This thesis studies current sensing techniques that are designed to meet the requirements for the next generation of power converters. Power converters are often standardised, so that they can be replaced with a model from another manufacturer without an expensive system redesign. For this reason, the power converter market is highly competitive and relies on cutting-edge technology, which increases power conversion efficiency and power density. High power density and conversion efficiency reduce the system cost, and thus make the power converter more attractive to the customer. Current sensing is a vital task in power converters, where the current information is required for monitoring and control purposes. In order to achieve the above-mentioned goals, existing current sensing techniques have to be improved in terms of cost, power loss and size. Simultaneously, current information needs to be increasingly available in digital form to enable digital control, and to allow the digital transmission of the current information to a centralised monitoring and control unit. All this requires the output signal of a particular current sensing technique to be acquired by an analogue-to-digital converter, and thus the output voltage of the current sensor has to be sufficiently large. This thesis thoroughly reviews contemporary current sensing techniques and identifies suitable techniques that have the potential to meet the performance requirements of the next-generation of power converters. After the review chapter, three novel current sensing techniques are proposed and investigated: 1) The usefulness of the resistive voltage drop across a copper trace, which carries the current to be measured, to detect electrical current is evaluated. Simulations and experiments confirm that this inherently lossless technique can measure high currents at reasonable measurement bandwidth, good accuracy and low cost if the sense wires are connected properly. 2) Based on the mutual inductance theory found during the investigation of the copper trace current sense method, a modification of the well-known lossless inductor current sense method is proposed and analysed. This modification involves the use of a coupled sense winding that significantly improves the frequency response. Hence, it becomes possible to accurately monitor the output current of a power converter with the benefits of being lossless, exhibiting good sensitivity and having small size. 3) A transformer based DC current sense method is developed especially for digitally controlled power converters. This method provides high accuracy, large bandwidth, electrical isolation and very low thermal drift. Overall, it achieves better performance than many contemporary available Hall Effect sensors. At the same time, the cost of this current sensor is significantly lower than that of Hall Effect current sensors. A patent application has been submitted. .... The current sensing techniques have been studied by theory, hardware experiments and simulations. In addition, the suitability of the detection techniques for mass production has been considered in order to access the ability to provide systems at low-cost.

Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: The digital control of UPS systems has been difficult in the past due to a lack of DSP technology. It was for this reason not possible to establishing the necessary control to regulate the voltages and currents of the UPS systems. Recent advances in DSP technology have however provided the means of establishing central control of the UPS system as well as incorporating more complex closed-loop control algorithms by utilising a single floating-point DSP. Closed-loop control strategies are investigated and the central control of a line-interactive UPS is established in this study. Both the status of the physical system as well as various system parameters are controlled. The system both regulates and charges the storage batteries when the main utility supply is maintained. In the event that the utility fails, the converter instantaneously changes power flow towards the load with the aim of maintaining an uninterrupted voltage supply. Several closed-loop deadbeat based control strategies are investigated for the regulation of the inductor current. A solution for the regulation of the DC-link is also developed and implemented. Furthermore, an intensive study is done on the regulation of the voltage supplied to the load in the event that the utility supply fails. The investigation is initially approached by considering classical control theory. Although these control strategies provided sufficient results, a predictive strategy that is based on the physical conditions of the switching converter is finally investigated to establish closed loop control of the output voltage. This resulted in a high-bandwidth voltage controller capable of maintaining control under a wide-array of load conditions. / AFRIKAANSE OPSOMMING: Die digitale beheer van UPS stelsels was moeilik in the verlede as gevolg van 'n gebrek aan DSP tegnologie. Dit was vir hierdie rede nie moontlik om beheer te kon bewerkstelling ten einde die spannings and strome in the UPS stelsels te kon reguleer nie. Onlangse vordering in DSP tegnologie het egter dit moontlik gemaak om sentrale beheer van die UPS stelsel te bewerkstellig sowel as om meer komplekse geslote lus beheer algoritmes te inkorporeer met behulp van 'n enkele DSP. Geslote lus beheer strategiëe word ondersoek en die sentrale beheer van die line-interaktiewe UPS word bewerkstellig in hierdie studie. Beide die huidige toestand van die fisiese stelsel sowel as die verskeie parameters word beheer. Die stelsel beide laai en reguleer die batterye terwyl die hooftoevoer onderhou word. In die geval dat die hooftoevoer faal, word die omsetter se rigting van drywingsvloei verander om die las te voorsien van 'n ononderbroke spannings toevoer. Verskeie geslote-lus “deadbeat” beheer strategiëe word ondersoek vir die regulasie van die induktor stroom. 'n Oplossing vir die regulasie van die GS-koppervlak word ook ontwikkel en geïmplementeer. Verder word 'n intensiewe studie gedoen op regulasie van die spanning wat aan die las gevoer word in die geval dat die hooftoevoer faal. Hierdie ondersoek word aanvanklik benader deur klassieke beheer teorie te bestudeer. Alhoewel hierdie beheer strategiëe voldoene resultate gebied het, was 'n voorspel beheerstrategie gebaseer op die fisiese toestand van die omsetter finaal ondersoek. Die resultaat is 'n hoë-bandwydte spannings beheerder wat daartoe instaat is om beheer te handhaaf onder 'n verskeidenheid van lastoestande.

Este trabalho apresenta o desenvolvimento e adaptação de técnicas para minimizar os efeitos das variações de carga e de frequência da rede em controladores repetitivos aplicados a filtros ativos de potencia. Para minimizar os efeitos provenientes de sinais aperiódicos decorrentes da conexão ou desconexão de cargas não lineares é elaborada uma técnica que diferencia cargas lineares de não lineares. Esta técnica opera de forma a só reinicializar o controlador quando o erro devido ao transitório for de valor considerável ou quando ocorrer a transição de carga não linear para linear. Também é desenvolvido um algoritmo de adaptação do ganho do controlador repetitivo baseado em uma função de adaptação sigmóide, com intuito de minimizar os efeitos provocados por ruído aleatório no sistema de medição. Na sequência, são analisados os efeitos da variação de frequência e apresentados os principais métodos de compensação deste problema. Entre as soluções apresentadas, encontra-se o método da alteração do número de amostras por período e o método da variação da taxa de amostragem. O primeiro possui a vantagem de utilizar técnicas de projeto lineares e invariantes no tempo. Já o segundo método, por variar a frequência de amostragem, deve ser analisado sob um aspecto de sistema variante no tempo, o que acarreta em maior complexidade na prova de estabilidade. Os algoritmos de reinicialização e adaptação do ganho do controlador repetitivo são analisados sob variação da frequência da rede. Para a compensação da variação da rede, utiliza-se o método do truncamento do número de amostras e o da variação da taxa de amostragem. Por fim, para validar os algoritmos desenvolvidos s˜ao realizados testes em uma plataforma experimental. / This work presents the development and modification of techniques to reduce the effects of load variation and mains frequency deviation in repetitive controllers applied to active power filters. To minimize the effects of aperiodic signals resulting from the connection or disconnection of non-linear loads is developed a technique which recognizes linear and nonlinear loads, and operates to reset the controller only when the error due to the transition of considerable value, and the transition is from non-linear to linear load. An algorithm to adapt the gain of the repetitive controller, based on a sigmoid function adaptation, in order to minimize the effects caused by random noise in the measurement system is also used. This work also analyzes the effects of frequency variation and presents the main methods to cope with this situation. Some solutions are the change in the number of samples per period and the variation of the sampling rate. The first has the advantage of using linear design techniques and results in a time invariant system. The second method changes the sampling frequency and leads to a time variant system that demands a difficult analysis of stability. The proposed algorithms were tested using the methods of truncation of the number of samples and the method of changing the sampling rate of the system to compensate possible frequency variations of the grid. Experimental results are presented to validate the proposal.

Orientador: Júlio Borges de Souza / Resumo: O transformador de estado sólido tem se apresentado como uma ferramenta indispensável na construção das novas redes elétricas inteligentes, uma vez que essa nova estrutura de rede altera o layout tradicional, viabilizando a conexão de fontes de energia descentralizadas. Contudo, essa conexão de sistemas de geração distribuída na rede originou a bidirecionalidade do fluxo de potência, resultando em um novo panorama para as atividades de operação e manutenção das redes para as distribuidoras de energia. A análise dos possíveis impactos técnicos gerados na rede de distribuição deve ser realizada, com o intuito de garantir um nível de qualidade energética dentro dos padrões estabelecidos pela Agência Nacional de Energia Elétrica – ANEEL. Dentre os impactos, destacam-se a elevação do nível de tensão e a alteração do fator de potência, ambos, produzidos pelo excesso de potência injetada na rede por este novo cenário de geração de energia. Nesse contexto, esta dissertação tem como principal objetivo analisar o comportamento de uma rede de distribuição genérica com penetração de geração distribuída e avaliar o perfil de tensão diante de diferentes níveis de inserção dessa geração na rede. As características de ajuste de tensão instantânea e capacidade de interação com sistemas de armazenamento que o transformador de estado sólido possui foram empregadas no auxílio da regulação dos níveis de tensão que se apresentaram fora dos padrões determinados pela resolução 794/2018 da ANEEL, qua... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The solid state transformer has been presented as an essential tool in the construction of new intelligent electric grids, since this new network structure changes the traditional layout, making possible the connection of decentralized energy sources. However, this connection of distributed generation systems in the network created the bidirectionality of the power flow, resulting in a new panorama for the power distributors concerning the networks activities of operation and maintenance. The analysis of the possible technical impacts generated in the distribution network should be carried out with the purpose of guaranteeing a level of energy quality within the standards established by the National Electric Energy Agency (ANEEL). Among the impacts, we highlight the elevation of the voltage level and the change in the power factor, both produced by the excess power injected into the grid by this new energy generation scenario. In this context, the main objective of this dissertation is to analyze the behavior of a generic distribution network with distributed generation penetration and to evaluate the voltage profile before different levels of insertion of this generation in the network. The solid state transformer has instantaneous voltage adjustment characteristics and interaction capacity with storage systems, which were used to aid in the regulation of voltage levels that were out of the standards determined by ANEEL resolution 794/2018, when a high level of distributed g... (Complete abstract click electronic access below) / Mestre