Nowadays, Load frequency control (LFC) in electrical power system has become mandatory in regulating frequency due to load disturbance. Electrical power system contains multi-subsystems tied to each other by a tie line. The subsystems are defined by areas and each area can affect the other areas if load perturbation occurs. This paper presents three different kinds of classical controllers which are Proportional Integral Derivative (PID), Tilted Integral Derivative (TID), Fractional Order Proportional Integral Derivative (FOPID) to control the interconnected electrical power system frequency. The optimization algorithm which is Dandelion Optimizer (DO) is applied to Integral Square Error (ISE) fitness function in order to best tune the controller parameters. The simulation results using Dandelion Optimizer (DO) are compared to the simulation results of older optimization algorithms which are Beluga Whale Optimizer (BWO), and Grey Wolf Optimizer (GWO). The results are examined and compared between the three types of controllers PID, TID, and FOPID. From results obtained, DO with TID has the finest performance for time settling and error minimizing.