Abstract— Integration of Proton Exchange Membrane Fuel Cell (PEMFC) with electrical power grid (EPG) can improve the power quality (PQ) of EPG by injecting the required power. However, this makes the PQ issue more complicated due to the negative impact of voltage sag on EPG. Unfortunately, the classical P-I controllers fail in eliminating the voltage sag. In this context, this paper, attempts to mitigate the voltage sag in an interconnected PEMFC-EPG system by utilizing advanced equilibrium optimizer (AEO) and particle swarm optimization (PSO) controllers, and their efficiency is demonstrated by comparison with conventional P-I controllers. To achieve this goal, the AEO-PEMFC and PSO-PEMFC are employed in the EPG line with different fault scenarios. The obtained results unveil that both AEO-PEMFC and PSO-PEMFC provide the needed boost of voltage in the single line-to-ground faults (SLGF) scenario by 100.00%. For double line-to-ground faults (DLGF) scenario, a voltage boost of 99.56% and 98.39% is achieved while a voltage boost of 98.50% and 97.45% for the three line-to-ground faults (TLGF) scenario is obtained by the AEO-PEMFC and PSO-PEMFC, respectively.