In this paper, frequency and voltage control schemes are presented for conventional power systems. Using those control loops, a model identification was performed in order to obtain relationships between frequency and power variations in active and reactive power on the IEEE 9 bus benchmark. The use of Bode plots as an analysis tool for determine system frequency sensitivity to load disturbances is illustrated through simulation. The results show that the study of system sensitivities could lead to the development of disturbance rejection strategies that enhance system operation and reliability.