Improvement of Fuel Cells Dynamic Response in Micro-Grids Using Ultra Capacitors

Fuel Cells do not respond to higher frequency contents of load changes due to their inherent large time constants; thus, if any disturbance occurs in the system loading, it would cause negative effects on power quality of the system. This is especially of high importance in microgrids which contain critical loads with low inertia requirements. Sudden changes in load points could cause significant frequency and voltage variations. Hence, proper measures such as energy storage systems should be taken into microgrids for improving their stability. In this paper, a new method based on Ultra-Capacitor (UC) with bidirectional converter has been proposed to solve this drawback of fuel cells. The UC is used to modify the system's frequency response with a fast and efficient controller. The proposed method is simulated for a sample test system in MATLAB/SIMULINK environment and results are presented to illustrate its performance. Based on the results, the system can manage its frequency and voltage variations effectively by the proposed configuration.