Thesis (M.Eng.)--Chulalongkorn University, 2008

In power system operation and control, large load variation greatly influences the system's stability and the dynamic performances such as the rotor angle, the terminal voltage, the speed deviation of the generator, and the voltages of nearby buses. This thesis presents the design of compensators for power systems subject to random load voltage fluctuation by using the principle of matching and the method of inequalities. In the design, all possible load voltage variations are treated as persistent disturbances having uniform bounds on the magnitude and the slope. The principal design objective is to ensure that the magnitudes of the outputs of interest do not deviate from their nominal values more than the allowable bounds for all time in the presence of all the possible disturbances. Any violation of the bounds may cause the system's instability and unacceptable consequences. Once a solution is found, the system is guaranteed to operate satisfactorily for all time. The numerical results demonstrate that the framework adopted here is suitable and effective, thereby giving a realistic formulation of the design problem.