LCL filter design and robust converter side current feedback control for grid-connected Proton Exchange Membrane Fuel Cell system

Abstract

Proton Exchange Membrane Fuel Cell (PEMFC) systems are environment-friendly systems that can be used as distributed power generation (DPG) system. As DPG units are usually utilized in weak power distribution systems, the grid inductance variations should be investigated during the control design stage of the grid-tied fuel cell systems. In recent years, LCL filter is broadly utilized to grid connection of DPG units, and the proper design of this filter is an important issue. In this paper, converter side current feedback (CSCF) method has been applied due to its innate damping feature to integrate PEMFC fuel cell system through LCL filter into weak power distribution system. The impact of delay should be considered as it limits the stability region of the resonance frequency of the CSCF control method especially, in the presence of wide variations of the grid inductance. Precise-tuned LCL filter design and consequently, the proper choice of the resonance frequency can remarkably affect the performance of the CSCF control. An adequate-tuned design procedure for LCL filter parameters has been proposed in this paper. Step-by-step tuning of the PR controller parameters has also been included to enhance the power quality. The grid-tied fuel cell system with modified-Y-Source inverter and LCL filter as an interface between inverter and grid has been simulated to analyze the quality of the injected power. Simulation results in MATLAB/Simulink environment verify the suitable performance of the proposed power conditioning system as well as its stable operation versus wide variation of weak grid inductance.