In this paper, different point of load frequency control (LFC) has presented. A two area interconnected systems have developed with different type of area control characteristics namely as supplementary control loop and primary control loop. Developed LFC model is scrutinize for overall stability with the effects of primary and supplementary control loop.Tuning methods of PID controllers for the load frequency control of interconnected power system is presented. This model examined for overall stability and the effect of the different parameter tuning method in PID controller. The performance of various tuning methods of PID controller is validated on MATLAB software.