A sliding mode load frequency controller is proposed for a power system with mismatch parameter uncertainties
and load disturbance. The switching surface is designed the integral function, which can improved the dynamic performance
during the hitting condition and the system robust. The sliding mode controller is derived from the reaching law, which can
assure that the hitting condition is satisfied. The one area power system model is proposed by simulation with uncertain
parameters. The simulation results show the effectiveness and robustness of the designed controller.