Renewable/Fuel Cell Hybrid Power System Operation Using Two Search Controllers of the Optimal Power Needed on the DC Bus

Nicu Bizon,Mircea Raceanu,Emmanuel Karapidakis,Emmanouel Koudoumas,Adriana Marinoiu,Elena Carcadea

doi:10.3390/en13226111

Abstract

In this paper, the optimal and safe operation of a hybrid power system based on a fuel cell system and renewable energy sources is analyzed. The needed DC power resulting from the power flow balance on the DC bus is ensured by the FC system via the air regulator or the fuel regulator controlled by the power-tracking control reference or both regulators using a switched mode of the above-mentioned reference. The optimal operation of a fuel cell system is ensured by a search for the maximum of multicriteria-based optimization functions focused on fuel economy under perturbation, such as variable renewable energy and dynamic load on the DC bus. Two search controllers based on the global extremum seeking scheme are involved in this search via the remaining fueling regulator and the boost DC–DC converter. Thus, the fuel economy strategies based on the control of the air regulator and the fuel regulator, respectively, on the control of both fueling regulators are analyzed in this study. The fuel savings compared to fuel consumed using the static feed-forward control are 6.63%, 4.36% and 13.72%, respectively, under dynamic load but without renewable power. With renewable power, the needed fuel cell power on the DC bus is lower, so the fuel cell system operates more efficiently. These percentages are increased to 7.28%, 4.94% and 14.97%.

Highlights

With the rapid increase in electricity consumption and the depletion of fossil fuel reserves, additional demands have emerged in national electricity generation networks
If the hydrogen consumption is measured in liters per minute [lpm], a gain of 1/3 (=20 s/60 s) is necessary to be used because the load cycle used has 20 s, not one minute
The strategies were analyzed from the point of view of consumed hydrogen by an fuel cell (FC) hybrid power source (HPS) without and with power from renewable energy sources (RES)

Summary

Introduction

With the rapid increase in electricity consumption and the depletion of fossil fuel reserves, additional demands have emerged in national electricity generation networks. To eliminate this disadvantage, the use of alternative energy sources that are sustainable and environmentally friendly is considered [1]. If an extra surplus of electricity appears, to avoid any problems in managing this intermittent energy, it can be consumed by an electrolyzer to produce hydrogen, which can be further converted into electricity through a fuel cell when there is a need for surplus energy or renewable. The proton exchange membrane fuel cell (PEMFC) can be used to manage the electrical load curve of the final consumers, offering in this way a proper option of balancing the frequency of the AC grid [5,6]

Methods

Results

Discussion

Conclusion