In this thesis, a coordinated corrective and emergency control based on the prediction of the system trajectories after disturbance occurrence is proposed to prevent long term voltage instability and to attain to some purposes such as establishing acceptable steady state operating point and reducing deviations of weak area bus voltages and weak transmission line current, during transient interval after disturbance. Effective dynamics on long term voltage instability like load, LTC and OXL dynamics are used to predict system state trajectories due to probable disturbances. Optimum and predictive control is designed by minimizing an objective function on a interval from disturbance occurrence time to system settling time including amount of load shedding and instability indices. In this scheme, some corrective and emergency control actions like setting reference voltage of the generators and LTCs, connecting shunt capacitors to system buses and load shedding as a final solution are combined. The resulting optimization problem is solved by second order derivative algorithm as an analytical method and Tabu Search algorithm as a heuristical method for two 4 bus and 10 bus test systems.
