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Different Influence of Grid Impedance on Low- and High- frequency Stability of PV Generators
摘要： Recently, the stability issues when renewable energy sources are connected to weak grid have obtained great attention. The popular view thinks that the grid impedance is adverse to the system stability. However, in this paper, it is first found that for the photovoltaic (PV) generator, the grid impedance has different influence on the system stability depending on the frequency range when the complete model of the PV generator is taken into consideration. That is, the increase of grid impedance can suppress the low-frequency (<50 Hz) oscillation, while the increase of grid impedance degrades the high-frequency (>300 Hz) stability. Concretely, for the low-frequency range mainly dominated by the power loop and voltage loop of the PV generator, the describing function method is adopted to overcome discontinuity and nonlinearity of the power loop. Then, the low-frequency dynamics like power oscillation can be analyzed accurately. For the high-frequency range mainly dominated by the phase-locked loop and current loop of the PV generator, the impedance analysis method is adopted to reveal the high-frequency instability mechanism. Through these analyses, the different influence of grid impedance on the low- and high- frequency stability of PV generators can be clearly distinguished. All the conclusions are verified through the real-time hardware-in-loop (HIL) tests.
关键词： describing function,impedance analysis,PV generators,weak grid,stability analysis
更新于2025-09-23 15:22:29
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Nanoscale Perovskite-Sensitized Solar Cell Revisited: Is This Dye-Cell or Perovskite-Cell?
摘要： A general and straightforward way of preparing few nanometer-sized well-separated MAPbIxBr3-x perovskite photosensitizers on the surface of ~1 μm thick mesoporous TiO2 photoanode was suggested via a two-step sequential deposition of low-concentrated lead halides (0.10 ~ 0.30 M PbI2 or PbBr2) and methylammonium iodide/bromide (MAI/MABr). When those nanoscale MAPbIxBr3-x perovskites are incorporated as a photosensitizer in typical solid state dye-sensitized solar cells (ss-DSSCs), it could be verified clearly by the capacitance analysis that nano-particulate MAPbI3 perovskites are playing the same role as that of a typical dye sensitizer (MK-2 molecule) though their size, composition and structure are different.
关键词： perovskites,Impedance analysis,solid state dye-sensitized solar cells,sensitizers,nanostructures
更新于2025-09-23 15:19:57
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Investigation of the structural, optical, elastic and electrical properties of spinel LiZn <sub/>2</sub> Fe <sub/>3</sub> O <sub/>8</sub> nanoparticles annealed at two distinct temperatures
摘要： Nanoparticles of Li0.5ZnFe1.5O4 (LiZn2Fe3O8) with the spinel structure were prepared by a sol–gel auto-combustion method at two different annealing temperatures. X-ray diffractograms and Rietveld refinement confirmed the formation of the spinel structure. The morphology was analyzed by electron microscopy, which showed that the grains were composed of different crystallites. Elastic properties were determined from infrared spectroscopy. It was found that the elastic parameters increased with the increase in annealing temperatures. The band gap depends on the annealing temperature and it decreased on increasing the particle size. The conductivity of the specimen annealed at 500 °C followed either the Jonscher's model or Drude's model depending on the temperature range. This conductivity decreased when the annealing temperature was raised by 600 °C. AC conductivity was found to be controlled by the hopping model. A single relaxation phenomenon was evidenced for each sample from impedance analysis. The Nyquist diagram proved that the samples were simultaneously capacitive and resistive and also supported the presence of multiple relaxation times.
关键词： annealing temperature,spinel,conductivity,LiZn2Fe3O8,impedance analysis,band gap,elastic properties,sol–gel auto-combustion
更新于2025-09-16 10:30:52
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[Lecture Notes in Electrical Engineering] Advances in Signal Processing and Communication Volume 526 (Select Proceedings of ICSC 2018) || Analysis of Graphene/SiO2/p-Si Schottky Diode by Current–Voltage and Impedance Measurements
摘要： We explore the electrical properties of graphene–silicon dioxide–p–silicon Schottky junction diode using current–voltage characteristics and impedance analysis. Ideality factor, recti?cation ratio, and series resistance are extracted from the experimental data. A linear response of series resistance of graphene/SiO2/p-Si Schottky diode is observed with respect to change in forward bias voltage from 0 to 2 V.
关键词： Silicon,Schottky diode,Impedance analysis,Graphene
更新于2025-09-10 09:29:36