Abstract—This paper aims to design an optimal controller in order to regulate the frequency in restructured power grid utility. Integral (I), Proportional-Integral (PI) and Proportional Integral Derivative (PID) controllers have been employed for frequency control. A two-area power system in a restructured environment is studied for the proposed approach. Gain tuning of the controllers is achieved through Ant Lion Optimization (ALO) algorithm by employing three objective functions, namely, Integral Absolute Error (IAE), Integral Squared Error (ISE) and Integral Time Absolute Error (ITAE). The objective functions are tested with I, PI and PID controllers for two cases, namely, bilateral contracts with and without violation respectively. Comparison of different combinations is done in terms of the performance indices. PID-ITAE combination gives acceptable results. An optimal combination approach is effective for finding the best combination of controller and objective function which helps to achieve improved steady-state performance.