Abstarct: In the conventional power system, the frequency control is achieved by governor and automatic generation control (AGC) maintaining the balance between generation and load. On the other hand, there is a potential in demand side to control the power system frequency. In this thesis, the frequency control is performed by making use of the demand side response considering the time delay due to communication devices. In the proposed method, the frequency control is undertaken for a single area network with incorporating both AGC and demand response, simultaneously. Also, the nonlinearity due to the time delay linearized using Pade approximation and then it is used in the Heffron-Phillips model of a single machine connected to an infinite bus. The proposed method is baxsed on the model predictive control (MPC). The conventional frequency control is modified by using the MPC baxsed method with assigning different weighting coefficient for secondary and demand response controls for a single area network. The proposed method is simulated in the Matlab/Simulixnk for single area test power system and compared with conventional frequency control method. The results of the simulations show that the proposed method compare to the conventional have lower frequency deviation and settling time.