This paper investigates how effectively a fractional order controller (FOPID) works for Automatic Generation Control (AGC) issues in a multi area power system. Fractional order controllers gives better dynamic response results than the widely used conventional integer order controllers like IOPI or IOPID controller. Optimal gain setting of the integer and fractional order controllers are obtained by using Bacterial Foraging Optimization Algorithm (BFOA) by minimizing an integral of time-weighted absolute error (ITAE) performance index. For the improvement of dynamic responses in a multi area power system, Capacitive Energy storage (CES) units are also implemented in its all control areas. The test system simulations are carried out in a Matlab/Simulink environment validates that BFOA based FOPID controller give better results than conventional controllers. © 2015 School of Electrical Engineering and Informatics. All rights reserved.