This study presents a detailed investigation aimed at enhancing load frequency control (LFC) within a three-area non-reheat power system through the integration of energy storage devices. The primary objective is to evaluate the impact of minimizing power flow across tie lines between areas versus allowing it to fluctuate freely based on demand. This comparison seeks to determine the effects on LFC parameters under both scenarios. Additionally, the research examines the potential benefits of incorporating or excluding power tie lines in the objective function to achieve superior LFC performance. To conduct this analysis, two controller designs were employed: a Proportional-Integral-Derivative Filter (PIDF) optimized using the Mountain Gazelle Optimizer (MGO) and a hybrid controller that merges fuzzy logic with MGO (Fuzzy PI-PIDF). The performance of the LFC system was assessed using the Integral Time-Absolute Error (ITAE) as the objective function, which considers area control error, including frequency deviations and power tie-line interactions. The ITAE was also utilized to evaluate frequency deviations independently, excluding power tie lines from the objective function. Simulation results demonstrate the effectiveness of the proposed controllers in improving LFC system performance. Notably, the PIDF controller, tuned by MGO and based on ITAE that focuses solely on frequency deviation, significantly outperformed the other controllers, achieving substantial reductions in overshoot, undershoot, and settling time............................... Keywords: .................load frequency control, Mountain Gazelle Optimizer, Integral Time-Absolute Error, power tie line.