Grid-forming fuel cell system for a multi-energy-microgrid in islanding operation

Inhalt:
A promising method to tackle spatial and temporal challenges of an increasing share of renewables is the coupling of different energy sectors. Especially gas and electricity systems profit from possible bidirectional energy flows in order to support the sensitive electric grid through gas-to-power technologies such as fuel cells and the possibility to store surplus electrical energy using power-to-gas technologies such as electrolyzers. The grid connection is usually realized using power electronics leading to dynamic and transient interactions between gas sector, conversion technology, power electronics and electric sector. Thus, a good understanding of the operation of the conversion technologies under these new circumstances is necessary. In this paper a model of a multi-energy microgrid consisting of a fuel cell system, a battery, a photovoltaic system each connected through power electronics to an AC load is presented. The model is investigated in island mode with volatile solar irradiation and load. The aim is to investigate the fuel cell system aptitude as a grid-forming unit and the benefits of using a battery as grid-supporting unit to enhance grid resilience. The simulation results show that the transient behaviour of the fuel cell system during a load step on fuel cell and grid side could be enhanced by using the fuel cell system‘s DC bus voltage as a reference, in addition to the AC side’s active power, for the battery inverter control.