This paper introduces a tilt integral derivative controller as the supplementary controller for load frequency control of a two-area interconnected power system. The optimal value of parameters of the tilt integral derivative controller is evaluated using constrained nonlinear optimization by means of a performance index-based method. The proposed tilt integral derivative control offers superior properties such as simple parameter tuning and its performance does not compromise the occurrence of any parameter variations in the system. To verify these features of the controller, the test system is subjected to step load disturbance and parameter variations that ensure the robustness of the tilt integral derivative controller. Comparative analysis with previously published work indicates that the proposed tilt integral derivative controller gives better performance and holds the property of robustness. Simulations have been performed using Matlab®.