Instability of a power system can be caused by the variation of loads, this leads to changes of generator's power. Due to impedance drops, terminal voltages of generator are varied which, in some cases, are out of the rated value. If no effective regulation is applied, the this variation can affect to the power quality. In order to maintain the power system to work well, then system disturbance must be eliminated or minimized. This paper proposes a method to use two different excitation systems which are AC generator based and static based excitation systems with the utilization of power system stabilizer PSS2A. This proposed method can improve voltage quality, generator capacity and stability of power system. Simulation results show that the power system can meet the technical requirements and the designed method can be feasible in reality.