In this study, an automatic excitation control system design and simulation has been realized. Especially on the energy generation power plants, generator terminal voltage is increased by the step-up transformers and equalized for the parallel connection to the grid. Terminal voltage of the synchronous generators is adjusted according to the field current and the rotor speed, therefore these two variable has to be controlled at simultaneously. So in this study generator voltage and the speed are controlled at the same time. Mechanical control is realized by PI for the constant frequency. Thyristor Controlled rectifier is connected to the output of the transformer that is connected to the generator terminal voltage and controlled closed loop. On static excitation an external DC voltage source is required. In this work as external DC source solar energy has preferred. For the field flashing DC voltage has taken from solar panels. When generator has excited enough for the TCR, field flashing has stopped. Firing angle of the TCR is controlled by PI. Hence, generator terminal voltage is equalized reference voltage that is determined before. For block the over excitation failure a software has been realized. Excitation system will be operated between two determined frequencies that are lower and upper limits. Excitation and frequency system control has been realized with MATLAB/Simulink.