Routing in sensor networks is a challenging issue due to inherent constraints such as power, memory, and CPU processing capabilities. In this thesis, we assume an All to All communication mode in an N × N grid sensor network. We explore routing algorithms which load balance the network without compromising the shortest paths constrain. We analyzed the Servetto method and studied two routing strategies, namely Horizontal-Vertical routing and Zigzag routing. The problem is divided into two scenarios, one being the static case (without failed nodes), and the other being the dynamic case (with failed nodes). In static network case, we derived mathematical formulae representing the maximum and minimum loads on a sensor grid, when specific routing strategies are employed. We show improvement in performance in load balancing of the grid by using Horizontal-Vertical method instead of the existing Servetto method. In the dynamic network scenario, we compare the performance of routing strategies with respect to probability of failure of nodes in the grid network. We derived the formulae for the success-ratio, in specific strategies, when nodes fail with a probability of p in a predefined source-destination pair communication. We show that the Servetto method does not perform well in both scenarios. In addition, Hybrid strategy proposed does not perform well compared to the studied strategies. We support the derived formulae and the performance of the routing strategies with extensive simulations.

Orientador: Prof. Dr. Edmarcio Antonio Belati / Dissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Engenharia Elétrica, 2017. / Esta pesquisa propõe uma metodologia baseada no Fluxo de Potência Ótimo Reativo (FPOR), para a operação dos sistemas de transmissão sob emergência usando o mínimo corte de carga em associação com dispositivos Static VAr Compensator (SVC). O SVC é modelado pelo método da susceptância variável e inserido no problema do FPOR. A função multiobjetivo é formada em três partes, perdas de potência ativa, desvio da tensão e cortes de carga. Propõese um procedimento para calcular os valores dos pesos das funções de perdas e desvio da tensão sendo uma das contribuições deste trabalho. A função de mínimo corte de carga foi associada a uma variável que pode ser contínua ou binária, que corta uma porcentagem (contínua) ou a totalidade (binária) da potência da barra candidata, tratando-se assim como problemas de programação não linear (PNL) ou programação não linear inteira mista (PNLIM) respectivamente. O conjunto de barras candidatas ao corte de carga foi formado pelas barras críticas do sistema para cada situação de contingência e foi definido por meio de uma estratégia proposta neste trabalho para identificar as barras mais susceptíveis ao corte de carga. Para o tratamento das variáveis binárias do problema, foi usado o algoritmo Branch &Bound associado com o FPOR. A metodologia foi testada nos sistemas IEEE de 14 e 118 barras modificados para as diferentes situações de contingência simuladas neste trabalho. / This research proposes a methodology based on the Optimal Reactive Power Flow (ORPF) for the operation of the emergency transmission systems using the minimum load shedding in association with Static VAr Compensator (SVC) devices. The SVC was modeled as a variable susceptance and inserted in the ORPF problem. A multi-objective function was formed by three parts, namely, active power losses, voltage deviation and load shedding was device. Propose a procedure to calculate the values of the weights of the loss functions and the voltage deviation, one of the contributions of this research. The minimum load shedding function uses a variable that can be continuous or binary, which turns off a percentage (continuous) or all (binary) loads of candidate power buses, resulting in a Nonlinear Programming Problems (NLP) or Mixed Integer Nonlinear Programming (MINLP) respectively. The critical buses of the system for each contingency formed the candidate set of buses for the load shedding and was defined by a strategy proposed in this research to identify the bus most susceptible to the load shedding. For the treatment of the binary variables of the problem, a Branch & Bound algorithms associated with the ORPF was used. This methodology was tested in the modified IEEE 14 and 118-bus systems for the different contingency situations simulated in this research.