Gómez Anccas, Edgar Diego

Utilizing multi-energy renewable microgrids is a promising prospect for decentralized electric power generation. To form a multi-energy microgrid and integrate different renewable energy sources, grid-forming inverters are the core elements. Therefore, their performance has to be tested and validated to increase the quality and reliability of the power supply. The present paper investigates the suitability of a specifically designed and implemented grid-forming inverter as the central component in such microgrid systems. Quality of black-start, frequency and voltage regulation, fast transient response, energy efficiency, low harmonic distortion, proper power factor control, synchronization and phase alignment for integration of renewable energy sources and energy storage devices such as photovoltaics and lithium-ion battery bank, respectively, fault-ride through capability, and resilience to fluctuations imposed by loads are the main features that have been tested and validated for a laboratory-scale grid-forming inverter. The study focuses on the parameters essential for ensuring the reliable and efficient operation of the inverter in dynamic and diverse energy environments, especially its adaptability to varying load profiles and its resilience towards intermittent energy inputs. The findings from this performance evaluation contribute insights for engineers, researchers, and industry professionals involved in the design, deployment, and optimization of multi-energy microgrids.

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.