Due to the sheer global energy crisis, concerns about fuel exhaustion, electricity shortages, and global warming are becoming increasingly severe. Solar and wind energy, which are clean and renewable, provide solutions to these problems through distributed generators. Microgrids, as an essential interface to connect the power produced by renewable energy resources-based distributed generators to the power system, have become a research hotspot. Modern research in the field of microgrids has focused on the integration of microgrid technology at the load level. Due to the complexity of protection and control of multiple interconnected distributed generators, the traditional power grids are now outmoded. Microgrids are feasible alternatives to the conventional grid since they provide an integrating platform for micro-resources-based distributed generators, storage equipment, loads, and voltage source converters at the user end, all within a compact footprint. A microgrid can be architected to function either in grid-connected or standalone mode, depending upon the generation, integration potential to the main grid, and consumers' requirements. The amalgamation of distributed energy resources-based microgrids to the conventional power system is giving rise to a new power framework. Nevertheless, the grids' control, protection, operational stability, and reliability are major concerns. There has yet to be an effective real-time implementation and commercialization of micro-grids. This review article summarizes various concerns associated with microgrids' technical and economic aspects and challenges, power flow controllers, microgrids' role in smart grid development, main flaws, and future perspectives.
The adsorptions of toxic gas molecules (CO2, CO, H2S, HF and NO) on pristine and Ti atom doped hexagonal boron nitride (hBN) monolayer are investigated by density functional theory. Ti atom doping significantly enhances the adsorption ability.
Hydrogen adsorption on titanium (Ti) atom-doped single vacancy silicene (SV-SL) is investigated through first principles density functional theory (DFT) study. Strong hybridization of d-orbitals of Ti atom to p-orbitals of Si atoms results in a tight bond to the silicene sheet with energy of À6.48 eV and keeps away from metal clustering. Maximum 8 H 2 molecules firmly bind to Ti atomdoped SV-SL sheet with an adsorption energy ranging from À0.481 to À0.201 eV per H 2 molecule and hydrogen storage capacity (HSC) of 6.3 wt%.Double-side H 2 adsorptions on hollow sites of Ti atom-doped SV-SL sheet are verified by structural and electronic properties. The partial density of states (PDOS) analysis shows the kubas interaction mainly caused the molecular H 2 adsorption. Further, the absence of spin-up and spin-down channels in electronic band structures of nH 2 molecule adsorption to Ti atom-doped SV-SL systems indicates its nonmagnetic nature. Conclusively, this study reveals that the Ti atom-doped SV-SL can be a promising candidate for hydrogen storage applications.
This study shows density functional theory (DFT) investigations that 3d transition metals (TM) doping in silicene can greatly alter the geometric, spintronic, and optoelectronic properties of the pristine silicene (p‐Si) layer. Significant Bader charge transfer from 3d TM atoms to surrounding Si atoms ensures the tight bonding between dopant and substrate; hence, all the 3d transition metal‐doped silicene (3d TM‐Si) systems are said geometrically strong and stable. Sc‐ and Ti‐doped systems show the lowest formation energies of −84.72 and −84.21 eV, respectively, while Zn‐Si bears the highest (−70.89 eV). 3d TMs from V to Co doping induces magnetic moment (MM) in the silicene layer which mainly comes from d‐orbitals of 3d TM atoms and partly from p‐orbitals of Si atoms, meanwhile Mn‐Si has MM as high as 3.0 μB. Among 3d TM‐Si systems studied, Cr‐Si and Mn‐Si systems became half metals, Ti‐Si became indirect semiconductor, whereas rest others convert into metals. Sc and V doping is found to be p‐type doping as the Fermi level shifts into the valence band. Moreover, multiple and broader peaks in the absorption coefficient plot indicate the significant photoabsorption of 3d TM‐Si systems. The present study of electronic, magnetic, and optical properties of 3d TM‐Si systems extend a helpful proposal for further experimental work to fabricate silicene‐based single‐spin electron source and other nano‐electronic devices.
Concerns about fuel exhaustion, electrical energy shortages, and global warming are growing due to the global energy crisis. Renewable energy-based distributed generators can assist in meeting rising energy demands. Micro-energy grids have become a research hotspot as a crucial interface for connecting the power produced by renewable energy resources-based distributed generators to the power system. The integration of micro-energy grid technology at the load level has been the focus of recent studies. Direct Current Micro-energy-grids have been one of the major research fields in recent years due to the inherent advantages of DC systems over AC systems, such as compatibility with renewable energy sources, storage devices, less losses, and modern loads. Nevertheless, control and stability of the grid are the paramount constituents for the reliable operation of power systems, whether at generation or load level. This research article focuses on the power flow between DC feeders of an autonomous DC micro-energy grid. To achieve this objective, a mathematical model and classical control strategy for power flow between two DC feeders are proposed using a conventional dual active bridge converter. The control objective is to minimize the DC element in the High-Frequency Transformer. Firstly, the non-linear-switched converter model and generalized average model for converter control are presented. Then, these mathematical models are used to get a small-signal linear model so a classical control strategy can be implemented. The control method enables output voltage regulation while abstaining from the high-frequency transformer's winding saturation. The stability analysis endorses the validity of the proposed control scheme. Also, the system response to load changes and varying control parameters is consistent. The simulation results validate the proposal's performance for changing converter and control parameters.
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