| Network reconfigurations have been considered for stabilizing a power system subject to large transient disturbances. Recently with the improvement of power thyristor technology, TCSC (Thyristor-controlled series compensators) can be used for high-speed and flexible control of line impedances. As a result, time-optimal series-capacitor control is ready for application and time-optimal series-capacitor control based on two-machine systems has been developed.; Excitation system control also has been suggested as an effective way to improve power system stability through the rapid forcing of excitation and internal machine fluxes. The introduction of static excitation schemes with fast response and high ceiling voltage has made this practical.; This thesis consists of three main topics: time-optimal series-capacitor control, time-optimal excitation system control, and dynamic state estimation for use in time-optimal switching control.; Time-optimal series-capacitor control for a multi-machine system is developed and the strategy is extended to general systems requiring multiple series-capacitor switchings. Previously developed time-optimal techniques can be applied only to a sufficiently weak system requiring a single switching.; We also develop an approach for designing time-optimal excitation system control, for a power system modelled as a third-order nonlinear system.; To perform the time-optimal control the system states such as machine angles and speeds, must be known accurately. A nonlinear observer that estimates the necessary power system states for application to the time-optimal control design in a single-machine infinite-bus system is developed. |
