In this paper, load frequency control problem for power system is discussed. In the proposed method, we consider power system model including generator and battery. Also, saturation is taken into account as a constraint on the input to the model for generator and battery. Then, a cost function considering the storage capacity constraint is formulated. The connected power system cooperatively determines control input that minimize the cost function and keep the power system stable. Furthermore, we propose to consider the economic dispatch methodology considering the suppression of the fuel cost in power system. Therefore, load frequency control and economic dispatch methodology considering constraints of generator and battery are proposed in this paper. Finally, we confirm the effectiveness of our proposed method through numerical simulation.