Shipboard MVDC power systems need to support pulsed loads, which have destabilizing ef-fects on the MVDC power transmission bus voltage. Despite the reference shipboard MVDC architecture having energy storage to buffer the large power swings of pulsed loads, a large constant power still needs to be delivered to maintain the energy storage state of charge. This recharging constant power itself introduces small signal instability to the MVDC bus voltage. This thesis investigates the advantages of adding a dynamically tuneable virtual capacitor and resistor in parallel to the pulsed load for maintaining small signal stability. The stabi-lizer is implemented in a negative load configuration in the existing reference architecture hardware, where the stabilizer negatively impacts the power quality of the downstream load. To address this, a dual use is added to existing hardware by having the energy storage also cancel out the newly introduced noise. A controller was designed to control a MVDC power converter module for providing these stability services. In addition, the controller manages its internal energy storage and stabilizes its internal DC bus that powers its downstream pulsed load. / Future ships will have a special shipboard power grid and power converters to power future electronics. Most of these power converters will have an internal battery device that provides power when the generators do not provide enough power. Generators are very slow to change their power output. Some shipboard electronics may consume very large amounts of power at very quickly changing rates, causing instability to the power system. The batteries can accomodate the instability caused by these electronics. However, the batteries need to be quickly recharged, which is also unstable to the special power grid. This thesis modifies the recharging behavior so that it does not cause this instability. Also, it is preferable that the batteries will only draw power from the power grid in one direction and send power to the power consuming electronics. This setup is called negative load. This setup is preferable, because sending power back to the power grid will require extra hardware. Ships can only carry so much equipment due to constraints in weight or room, so additonal hardware is undesireable. There already exists similar research to provide this stabilizing service, but they are not designed for a shipboard power grid supporting these quick high power electronics. This thesis also makes a controls system that manages the battery and other requirements of the power system.

With the improvements in computer technology, users in utilities expect to receive more advanced functions of their power system management applications by using the data distributed among computer applications. The conventional method of point-to-point interface is not efficient for building large-scale computer systems and is especially difficult for system integration. Integration efforts are carried on to facilitate software applications communicating with others. Defining the same description for a central database and exchangeable data format among applications is the first step for integration. Since current data models in the Common Information Model (CIM) are designed mostly for analyzing the terrestrial transmission power system, they are not sufficient for Shipboard Power Systems (SPS). In order to facilitate software integration in SPS, a fundamentally common semantic for SPS applications needs to be extended from the current CIM. Therefore, these analysis applications for SPS could communicate with each other based on a standard model. In this thesis, a pulsed load model is extended from CIM. This model is a general time dependent pulsed load and the simulation of pulsed railgun load validates the proposed data model. Also, stress upon the power grid caused by the pulsed load is analyzed and the continuous railgun operation is simulated. In addition, new CIM data models are built for passive and active filters to facilitate system simulation and further application. As an active filter is a device that incorporates complicated control strategies, much work focused on finding a general data model to accommodate most common active filters. Finally the simulation for active filter validates the proposed data model.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This Master s Dissertation is proposes the development of a charge management system of a bank of 16 lead-acid batteries with 7Ah load capacity, commonly used in Uninterruptible Power Supplies (UPS). This system aims to ensure that these batteries reach a full charge status faster than the conventional way. To this, it was chosen to make the modification of the pulsed current charging method, in order to reduce problems, such as elevation of bus voltage to return the energy to it, or dissipation of that energy in a resistance, resulting in lower system efficiency, inherent in the method taken as a basis when the battery power withdrawal interval occurs. For the development of the suggested charging system the static converter Full-Bridge Isolated with modulation Phase Shift was chosen. To implement the digital control as well as its practical development in the same laboratory the simplified modeling of this converter was made. The results of simulation and experimental to validate the method are presented. / Esta dissertação de mestrado tem como proposta o desenvolvimento de um sistema de gerenciamento de carga de um banco de 16 baterias de chumbo ácido, com capacidade de carga de 7Ah, comumente utilizado em Fontes Ininterruptas de Energia (UPS). Este sistema visa garantir que estas baterias cheguem a um estado de carga completo e de forma mais rápida que a convencional. Para isto, foi escolhido fazer a modificação do método de carga de corrente pulsada, com o objetivo de reduzir problemas inerentes do método tomado como base, quando ocorre o intervalo de retirada de energia da bateria, tais como: elevação da tensão do barramento ao retornar a energia para ele, ou, dissipar esta energia em uma resistência, o que acarreta em baixa eficiência do sistema. Para o desenvolvimento do sistema de carga sugerido foi escolhido o conversor estático Full-Bridge Isolado com modulação Phase Shift. Foi feita a modelagem simplificada deste conversor, para a implementação do controle digital, assim como o desenvolvimento prático do mesmo em laboratório. São apresentados os resultados de simulação e experimentais para validar o método.

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