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With the increasing integration of renewable energy sources into modern power grids, the dynamic and operational complexity of power systems has grown significantly, rendering traditional control and modeling approaches insufficient. Virtual Synchronous Generator (VSG) technology has emerged as a critical solution, replicating the dynamics of synchronous generators to enhance the stability of inverter-based systems. Aggregation of VSG units is essential for efficient modeling and analysis of large-scale systems, especially in addressing challenges like power oscillations, dynamic stability, and control interactions. This paper proposes an improved homological equivalent method tailored for VSGs, incorporating a precise definition of critical parameters such as the time window and threshold to enhance its applicability. Additionally, aggregation methods for VSG control and circuit parameters are developed to facilitate the representation of complex systems. The proposed methods are validated through Matlab/Simulink simulations, where the performance of the aggregated VSG model is compared with the original VSG group. Results confirm the reliability and effectiveness of the approach in retaining dynamic characteristics while reducing modeling complexity. This research provides a theoretical foundation and practical methodology for VSG aggregation, contributing to enhanced stability analysis and operational efficiency in high-renewable-penetration power systems. [ABSTRACT FROM AUTHOR]

In recent years, Cu2ZnSnS4 (CZTS)-based thin-film solar cells have received extensive attention for the optimization of grain growth and the suppression of defects by cation replacement. In this work, we report for the first time the replacement of stannum (Sn) atoms with antimony (Sb) doped into the lattice by solution treatment. Cu2ZnSbxSn1–x(S, Se)4 (0 ≤ x ≤ 0.2) (CZTSSSe) thin films are synthesized on soda lime glass substrates by sol–gel and two-step annealing techniques. The Sb doping strategy and the structural, morphological, optical, and electrical properties of CZTSSSe films are described. According to SEM results, it was found that the CZTSSSe (x = 0) thin film is composed of nanoscale small grains, and the right amount of Sb doping encourages grain growth, allowing for the fabrication of dense CZTSSSe films with bigger grain sizes and fewer holes. When x = 0.10, the best outcomes were attained. Sb successfully replaces the Sn sites, which decreases the production of harmful defects associated with Sn and enhances the electrical properties of thin films to improve carrier mobility. The open circuit voltage (VOC) of the CZTSSSe (x = 0.10) device increased by 29 mV as compared to the pure Cu2ZnSn-(S, Se)4 (CZTSSe) device, and its power conversion efficiency (PCE) increased from 5.06 to 6.82%. These outcomes exhibit the potential of Sb in enhancing the PCE of CZTSSe-based devices. [ABSTRACT FROM AUTHOR]

The Cu2Ni0.05Zn0.95Sn(S,Se)4 (CNZTSSe) films were synthesized by sol-gel combined with selenidation treatment. To further enhance the crystal quality of the film, the selenidation conditions were optimized, and the effects of selenidation time on the properties of the CNZTSSe films and devices were systematically studied. The results show that the crystallinity of the films increased remarkably with the increase of selenidation time. Under the optimum selenidation time of 15 min, smooth and dense films were obtained. Through the analysis of EDS results, it is found that Se occupies more S positions with the increase of selenidation time, which decreases the band gap of the film from 1.14 eV to 1.0 eV. In addition, the formation of Zn-related defects is effectively suppressed by Ni doping to enhance the open circuit voltage (Voc) of the CNZTSSe solar cells. When the selenidation time is 15 min, the CNZTSSe film has the highest carrier concentration of 1.68 × 1016 cm−3, and the best efficiency of the device prepared based on the film as the absorption layer is 5.0%, and the Voc is 337 mV. [ABSTRACT FROM AUTHOR]

Cu2ZnSn(S,Se)4 (CZTSSe) films are considered to be promising materials in the advancement of thin-film solar cells. In such films, the amounts of S and Se control the bandgap. Therefore, it is crucial to control the concentration of S/Se to improve efficiency. In this study, Cu2MnxZn1−xSnS4 (CMZTS) films were fabricated using the sol-gel method and treated in a Se environment. The films were post-annealed in a Se atmosphere at various temperature ranges from 300 °C to 550 °C at intervals of 200 °C for 15 min to obtain Cu2MnxZn1−xSn(S,Se)4 (CMZTSSe). The elemental properties, surface morphology, and electro-optical properties of the CMZTSSe films were investigated in detail. The bandgap of the CMZTSSe films was adjustable in the scope of 1.11–1.22 eV. The structural propeties and phase purity of the CMZTSSe films were analyzed by X-ray diffraction and Raman analysis. High-quality CMZTSSe films with large grains could be acquired by suitably changing the selenization temperature. Under the optimized selenization conditions, the efficiency of the fabricated CMZTSSe device reached 3.08%. [ABSTRACT FROM AUTHOR]

Cu2Ni0·05Zn0·95Sn(S,Se)4 (CNZTSSe) films were synthesized on Mo-coated glass substrates by the simple sol–gel means combined with the selenization process, and CNZTSSe-based solar cells were successfully prepared. The effects of selenization temperature on the performance and the photoelectric conversion efficiency (PCE) of the solar cells were systematically studied. The results show that the crystallinity of films increases as the selenization temperature raises based on nickel (Ni) doping. When the selenization temperature reached 540 °C, CNZTSSe films with a large grain size and a smooth surface can be obtained. The Se doping level gradually increased, and Se occupied the S position in the lattice as the selenization temperature was increased so that the optical band gap (Eg) of the CNZTSSe film could be adjusted in the range of 1.14 to 1.06 eV. In addition, the Ni doping can inhibit the deep level defect of SnZn and the defect cluster [2CuZn + SnZn]. It reduces the carrier recombination path. Finally, at the optimal selenization temperature of 540 °C, the open circuit voltage (Voc) of the prepared device reached 344 mV and the PCE reached 5.16%. [ABSTRACT FROM AUTHOR]