| Summary: | 碩士 === 國立交通大學 === 控制工程研究所 === 83 === In this thesis, we present a result of the bifurcation analysis and control of nonlinear dynamics of electric power system with tap changer. Based on a model of electric power system proposed by Dobson and Chinang (1988) with one extra tap changer parallel to the local nonlinear power load, conditions for the existence of saddle node bifurcation and Hopf bifurcations are obtained from bifurcation analysis of system dynamics. Occurrence of period-doubling and cyclic fold bifurcations are also observed from numerical simulations as system parameters such as reactive power demand, real power demand or tap changer ratio vary. From simulations, the appearance of period-doubling leads to the occurrence of transient chaos and static chaotic behavior as system parameters vary. The occurrence of subcritical Hopf bifurcaton and saddle node bifurcation contribute to the appearance of dynamic voltage collapse and static voltage collapse, respectively. Both direct state feedback and washout filter design are applied to develop control laws, via the dynamic setting of tap changer ratio, to delay and/or eliminate the occurrence of Hopf bifurcations as nonlinear load demand increase. These efforts will result in the delay or elimination of dynamic voltage collapse.
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