Environmental concerns have made more utilities to be using Renewable Energy Sources (RESs) as new power generating units. Due to much variability posed by such sources, their impacts on frequency control performance have become a great concern. As a result, Load-Frequency Control (LFC) has undergone significant changes. In this paper, in order to regulate frequency in a modern power system, a Proportional Integral Derivative (PID) controller is employed and its parameters are tuned using firefly algorithm. A three-area interconnected power system in the presence of renewable energy sources is modeled and simulation results reveal that tuning PID gains using this optimization technique gives a desirable performance in damping frequency deviations. Furthermore, different scenarios have been performed to verify its robustness against diverse perturbations.
