This thesis designs a DSP-based controller which is composed of two parts,voltage controller and current controller.A proportional controller,treated as the current controller,is designed in the inner loop to control the capacitor charging current fast and effectively,especially when the sudden load is occurred.An PI controller,treated as the voltage controller,is designed in the outer loop to improve the system response irrespectively of system¡¦s parameter variation and load disturbance.The experimental result shows the output voltage can follow a sin wave which can match command exactly under the control scheme.

This thesis proposes an uninterruptible power supply, UPS for high availability servers with fuel cells as its back up energy source. The system comprises a DC to DC converter designed to accommodate the fuel cellâ s wide output voltage range. A server power supply is specified, designed and simulated for use with this UPS. The UPS interfaces internal to the server power supply, instead of providing standard AC power. This topology affords enhanced protection from faults and increases overall efficiency of the system by removing power conversions. The UPS is simulated with the designed power supply to demonstrate its effectiveness.

Abstract High quality powering systems have become the requirements for computers and electronic devices users. Uninterruptible power systems (UPS) are needed in office automation, home and small and medium enterprise computers and governmental network projects. In 2006, total UPSs sold in PRC exceeded 1,279 thousand units, with a sales value exceeding 2.61 billion RMB. The UPS industry experienced an 8% stable growth backed by economy growth of PRC. This research served theoretical basis and the understanding of industry practices as the base, describing the business model of UPS industry in PRC. This thesis also contains an in-depth interview with the leader of Powercom Co., an UPS manufacturer in PRC, on topics such as channel structure (length, width and density), relation control, channel motivation (strategy in effect and methods used) and conflict management (reasons, forms and solutions), trying to combine theories and practices. This study found that Powercom experienced three channel transformations in PRC market. Phase 1: instead of touching the market directly, they entered PRC via an agent, plays only the role of manufacturer ¡V a longer, narrower channel structure, with a traditional marketing relation aims at short-term profits, and price is the incentive. When the relation went down, Powercom took destructive solutions. Phase 2: Retailing channels were established in provinces in PRC, and the PRC market was divided in to four independent geographic marketing sectors, no intersection selling were allowed ¡V allowing the four sections to have their own storage and selling systems and compete with each other, resulting horizontal conflicts between section sellers. Phase 3: the marketing efforts are directed by a Great China concept, although the four offices still in charge of dealing orders and selling, no geographical restrictions exist. The channel structure was turned from density to selective distribution. Their relation with distributors are thus turned in to vertical systems, thus common objective, instead of price alone is the incentive to motivate firm members. Keywords: Uninterruptible power systems, cannel transformation

No description available.

Orientador: Leonardo Nepomuceno / Banca: Marcelo Augusto Cicogna / Banca: Edlaine Martins Soler / Resumo: Neste trabalho propõe-se um modelo de leilão multiperíodo para um mercado pool do dia seguinte de sistemas hidrotérmicos, que leve em consideração as restrições intertemporais do sistema termelétrico (e.g. potência máxima disponível e limites de rampa e período mínimo de operação e desligamento) e restrições hidráulicas (e.g. defluência, volume e balanço de água, altura de queda, alturas de montante e jusante do reservatório, limites de rampa de vazão defluente e função de produção). Também foram introduzidas no modelo as restrições de rede de transmissão, tais como o balanço e limites de fluxo de potência e representação das perdas. São descritas as técnicas de linearização das funções de altura de queda líquida, função de produção e função de perdas no sistema de transmissão. O modelo proposto é formulado como um problema de programação linear inteiro-misto, tendo sido resolvido utilizando as plataformas GAMS - CPLEX e IBM ILOG CPLEX Optimization Studio. Os resultados apresentados têm como foco principal a análise do impacto das restrições hidráulicas nos preços de equilíbrio de mercado e no despacho de geração de sistemas hidrotérmicos. Mostra-se que a operação de uma cascata hidráulica para o dia seguinte é orientada com base nas ofertas fornecidas pelas companhias geradoras no mercado de energia. / Abstract: This work presents a brief description of an energy market structure, as well as its agents, economic division and service and time horizon classification. The Brazilian mar-ket, single-period and multiperiod auction are also described, as much as a concise presen-tation of a hydroelectric generation system. It's proposed for a day-ahead pool market, a multiperiod auction for hydrothermal system which takes into account the intertempo-ral constraints from a thermoelectric system (e.g. maximum available power output and ramp rate limits, minimum up and down time) and hydraulic constraints (e.g. defluence, volume and water balance, net head, forebay and tailrace levels of reservoir, water release ramp rate limits and the unit performance curves). It was also associated to the problem the transmission constraints, such as balance and flow power limits and power loss. On account of being a problem with such features, the linearization techniques of the net head, unit performance curves and power loss function are described. The proposed mo-del is based on a mixed integer linear programming problem, which used the GAMS -CPLEX and IBM ILOG CPLEX Optimization Studio to its resolution. Finally there are two reported situations to analyze the impact of the hydraulic constrains on the bidding prices, as well as the in˛uence of the selling prices on the total spillage of the hydroelectric plants. The model is projected for a hydro predominance plant cascade. / Mestre

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1994. / Vita. Abstract. Includes bibliographical references (leaves 388-392). Also available via the Internet.

Thesis (Ph. D.)--Ohio State University, 2004. / Title from first page of PDF file. Document formatted into pages; contains xviii, 224 p.; also includes graphics. Includes bibliographical references (p. 199-211).

Thesis (M. Eng.), Memorial University of Newfoundland, 1999. / Bibliography: p. 113-115.

D.Ing. / In this dissertation a pulsed DC voltage bus comprising a full wave rectified sinusoidal voltage will be investigated for use as a link voltage. A background study into existing converter topologies for single phase uninterruptable power supplies and three phase front end converters, applicable to the study, is discussed. The definition of the bus voltage will be given as well as the power handling limitations. An experimental 3.3kW single phase UPS and a 3.3kW three phase front end converter using the bus was designed, built, tested and the results presented. The design and modelling of the two systems are discussed so as to clarify the advantages, disadvantages and limits of using such a bus. The appropriate standards pertaining the two converter systems have been looked up and the impact on the design discussed. The discussion will be concluded with a summarisation and possible future work is discussed.

No description available.