Este trabalho propõe uma estratégia fuzzy, do tipo Rede de Controladores Locais, aplicável à melhoria da estabilidade dinâmica em sistemas elétricos de potência, visando compensar possíveis perdas de sintonia devido à ocorrência de variações nas condições operacionais da planta. A adaptação dos ganhos do controlador fuzzy é efetuada on-line, interpolando-se os ganhos de um conjunto finito de controladores locais fixos. Ao ocorrer variações nas condições operacionais da planta, os ganhos da lei de controle são ajustados automaticamente de modo a manter satisfatório o desempenho do sistema de controle. O desempenho do controle foi avaliado através de estudos de simulação, utilizando-se um modelo dinâmico não-linear, do tipo máquina barra infinita. Os resultados mostram que o emprego da estratégia proposta permite obter melhorias no desempenho dinâmico do sistema. This work presents a fuzzy control strategy which can be applied to improve the dynamic stability of electric power systems. The gains of fuzzy controller are smoothly adjusted by using interpolation among the gains of a set of previously designed local controllers, according to the current plant operating condition. In this way, the parameters of the fuzzy controller are automatically adjusted on-line, in order to cope with changes in the power system operating conditions. The performance of the fuzzy strategy was assessed by simulation studies, using a nonlinear machine infinite bus bar dynamic model. The results show that it is possible to improve the power system dynamic performance under time-variable operating conditions.in english. Please notice that the abstract in english comes first
This work presents a state feedback controller suitable to regulate the output voltage of DC-DC buck converters operating under input voltage disturbances and load variations. First, a state space model of the plant is given and the performance requirements are presented, in terms of bounds on rejection of disturbances, bounds on settling time of transient responses and robustness against load variations. Then, a control design procedure based on a linear quadratic regulator is proposed, having the following features: a) an H • analysis condition to certify the bound on the rejection of disturbances, b) an eigenvalue evaluation, to ensure the bound on the settling times of the slowest mode in the transient responses, and c) a Lyapunov condition to ensure the robustness of the closed-loop system under load variations. The proposed design procedure produces control gains suitable for experimental implementation. For sake of comparison, a robust state feedback H • controller with pole location constraints is given, and results in very large gains, which are not suitable for experimental implementation. Practical results with the proposed controller are shown, illustrating the very good performance of the system operating under input disturbance and load variations.
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