A novel fuzzy logic controller based on T-S model is proposed for automatic generation control (ACC) system after deregulation. Since the AGC system is now exposed to sudden, larger changes introduced by deregulation policy, the nonlinearity must be concerned. In this paper, the generation rate constraint (GRC) is firstly constructed in T-S model to design the fuzzy logic controller, while the valve position limits on the governor are under consideration as well. Sufficient conditions for the asymptotic convergence of the whole system are provided in terms of linear matrix inequalities (LMI). The current control scheme is compared with conventional proportional and integral (PI) controller, and the comparison study indicates that the proposed fuzzy logic controller has better performance than the other while nonlinearity is concerned.