Abstract-In this paper a Posicast controller is designed to improve the power system stability containing the transient and the small signal stability. Unlike most of the recently published excitation control schemes, Posicast control is an unsophisticated and easy to implement control method that can effectively improve the stability of the system without increasing the complexity of the control system. The proposed controller is simulated under several large and small sudden 3-phase faults occurred in the different parts of the lines. It is also shown that the proposed controller increases the capability of the system in damping the oscillations caused by changing the exciter reference signal. In other words only one controller is used to improve the transient and small signal stability as well as the voltage stability. The results from extensive time domain simulations using MATLAB/Simulink demonstrate that the offered control strategy is superior to the conventional excitation control methods and can improve performance of the system in the all testing conditions. A performance index is also used to validate the effectiveness of the proposed controller in improving the system stability. I.