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[IEEE 2018 IEEE PES/IAS PowerAfrica - Cape Town (2018.6.28-2018.6.29)] 2018 IEEE PES/IAS PowerAfrica - Estimation of Inverter-Based Solar PV Penetration on Medium Voltage Networks Using Grid Impedance
摘要： Installation and control of connecting inverter-based generation to medium voltage networks are constrained by network grid structure and by technical regulations that limits its penetration into the network. Medium voltage networks form the backbone to which low-voltage inverter-based generation such as solar PV systems are connect to. However, these networks generally have inconsistent impedances that vary with line lengths, conductor types and load distribution and therefore make them not as flexible and cost effective to efficiently allow adequate penetration of solar PV type distributed generation (capacity in kW) to be integrated. A generic model that mimics a medium voltage network is analyzed in this paper to determine how inverter-based generation can be maximized on the network in terms of its location by focusing on line impedance ratios to achieve voltage regulation.
关键词： voltage regulation,Inverter-based generation,line impedance ratio,conductor type,medium voltage,line lengths
更新于2025-09-23 15:23:52
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Coordinated control of MPPT and voltage regulation using single-stage high gain DC–DC converter in a grid-connected PV system
摘要： In general, grid-connected PV system uses two stages of DC-DC converter to accomplish Maximum Power Point Tracking (MPPT) and DC voltage regulation. In order to overcome the two stage conversion, a single stage high gain DC-DC converter is presented in this paper. The operation of three switches with two different duty ratio is the main advantage of this converter to accomplish the coordinated control of MPPT and DC voltage regulation. This coordinated control also helps to provide constant DC voltage to the DC loads though the inverter is disconnected from the DC bus. A 1KW grid-connected PV system with the proposed DC-DC converter is developed and is validated using OP4500 Real-Time test platform. In addition, a decoupled control strategy with fractional order proportional-integral (FOPI) controller is implemented at the inverter end. Also, the reactive power compensation, harmonic reduction (less than 5% as per the IEEE 519 standard) and the grid power factor close to unity is obtained and the results are validated using the real-time simulator.
关键词： Solar photovoltaics,LCL filter,Coordinated control of MPPT and voltage regulation,High gain DC-DC converter,Grid integration and power quality
更新于2025-09-23 15:23:52
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Morphological regulation of all-inorganic perovskites for multilevel resistive switching
摘要： Enormous attention has been paid to all-inorganic cesium lead halide perovskites in various photoelectronic fields for their remarkable performances. However, comparing to their analogue organic-inorganic hybrid perovskites, the film morphology of such all-inorganic lead halide perovskites is difficult to control due to the low solubility of cesium salt. Here, we propose a new fabrication routine to control the film morphology of CsPbBr3. A series of CsPbBr3 thin films with big grains (≈800 nm) were successfully prepared. The memristors based on such CsPbBr3 thin films take on typical bipolar resistive switching behavior and remarkable characteristics such as high Ron/Roff ratio (≈105), very low working voltage (≈ ± 1 V), and long data retention (≥104 s). Furthermore, through modulating the film morphology, memristors with multilevel resistive switching behavior can be easily prepared. These advantages demonstrate that the all-inorganic cesium lead halide memristors possess great potential for future application.
关键词： Memristor,Morphological regulation,Multilevel resistive switching,All-inorganic perovskite
更新于2025-09-23 15:23:52
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Smart lighting as basic building block of smart city: An energy performance comparative case study
摘要： The aim of this work is to simulate and compare the energy savings potentially applicable to the consumption data of the Smart Street pilot system located at the ENEA Casaccia R.C. (Rome). The astronomical lighting system energy consumption (baseline) is compared to the simulation of a pre-defined regulation: it allows the lights dimming (and therefore a reduction of consumptions) based on a statistics average of the traffic flow rate, differentiated according to the day of the week. Then the baseline consumption is compared to the simulation of an adaptive configuration based on the traffic flow rate.
关键词： pre-defined regulation,adaptive regulation,energy performance,TAI,smart street,smart lighting,smart city
更新于2025-09-23 15:22:29
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DC-Bus Dual-Level Control Strategy for PV Power System with Dual-Mode Operation
摘要： An autonomous dc-bus dual-level control (DDLC) strategy is proposed for the two-stage three-phase photovoltaic (PV) power system. During the grid-fault situation, the second-stage inverter may lose the ability to regulate the dc-bus voltage and the first-stage boost converter has to change its mode from maximum power point tracking (MPPT) mode to dc-bus voltage control (DCVC) mode. However, the communication between the two-stage circuits must be established. The circuit complexity and cost will increase while the system’s scalability and flexibility will be reduced. With the proposed DDLC strategy, the dc-bus voltage is controlled into different levels for different operation modes, without the need of communication mechanism. No extra sensors or circuits are required. Two important design parameters for the proposed DDLC are derived thoroughly. The computer simulations and hardware experimental results of a 4 kVA prototype circuit are presented to validate the performance of the proposed DDLC strategy.
关键词： Optimal AC Line Current Regulation,Maximum Power Point Tracking (MPPT),PV Power System,DC-Bus Voltage Control (DCVC)
更新于2025-09-23 15:21:21
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Non-oxidation reduction strategy for highly selective detection of ascorbic acid with dual-ratio fluorescence and colorimetric signals
摘要： Ascorbic acid (AA), one of the most important vitamins, acts a critical role in various physiological reactions and is involved in many diseases. Thus, the development of highly selectivity methods for detecting AA level with the presence of different reducing substances is of great significance in complicated serum matrix. In this paper, a non-oxidation reduction regulation (NRR) strategy was designed to construct a novel dual-ratio fluorescence and colorimetric dual-readout assay for highly selective detection of AA. The strategy involves three processes: Ag+ oxidated o-phenylenediamine (OPD) to 2,3-diaminophenazine (OPDox), AA inhibited the generation of OPDox and the AA was oxidized to dehydroascorbic acid (DHAA). The specific performance of DHAA NRR, due to the condensation reaction between dicarbonyl group of DHAA and diamine group of OPD, that is confirmed by ESI-MS and 1H NMR spectra analysis, can remarkably enhance the selectivity of AA detection. Additionally, the proposed method based on NRR strategy not only provides a sensing platform for probing AA but also shows promising outlook in biomedical studies.
关键词： O-phenylenediamine,Non-oxidation reduction regulation,Ascorbic acid,Dual-ratio,Dual-readout
更新于2025-09-23 15:21:21
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[Advances in Experimental Medicine and Biology] || Photoresponsive Hydrogels with Photoswitchable Stiffness: Emerging Platforms to Study Temporal Aspects of Mesenchymal Stem Cell Responses to Extracellular Stiffness Regulation
摘要： An extensive number of cell-matrix interaction studies have identi?ed matrix stiffness as a potent regulator of cellular properties and behaviours. Perhaps most notably, matrix stiffness has been demonstrated to regulate mesenchymal stem cell (MSC) phenotype and lineage commitment. Given the therapeutic potential for MSCs in regenerative medicine, signi?cant efforts have been made to understand the molecular mechanisms involved in stiffness regulation. These efforts have predominantly focused on using stiffness-de?ned polyacrylamide (PA) hydrogels to culture cells in 2D and have enabled elucidation of a number of mechano-sensitive signalling pathways. However, despite proving to be a valuable tool, these stiffness-de?ned hydrogels do not re?ect the dynamic nature of living tissues, which are subject to continuous remodelling during processes such as development, ageing, disease and regeneration. Therefore, in order to study temporal aspects of stiffness regulation, researchers have developed and exploited novel hydrogel substrates with in situ tuneable stiffness. In particular, photoresponsive hydrogels with photoswitchable stiffness are emerging as exciting platforms to study MSC responses to extracellular stiffness regulation. This chapter provides an introduction to the use of PA hydrogel substrates, the molecular mechanisms of mechanotransduction currently under investigation and the development of these emerging photoresponsive hydrogel platforms.
关键词： Photoswitchable stiffness,Biophysical regulation,Photoresponsive,Cell-matrix interaction,Regenerative medicine,Polyacrylamide,Mechanotransduction,Stiffness regulation,Mesenchymal stem cells,Cell adhesion,Temporal,Hydrogel substrates
更新于2025-09-23 15:21:01
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Cd12O12 cage cluster-assembled nanowires and band gap regulation: A first-principles investigation
摘要： Based on the first-principle calculation, the stability and electronic properties of Cd12O12 cluster-assembled nanowires and Na-doped Cd12O12 nanowire are studied. The results show that both Cd12O12 nanowire and Na-doped Cd12O12 nanowire are thermodynamically stable (at least at room temperature). The most stable Cd12O12 nanowire exhibits semiconducting properties with a direct energy gap. After doping Na atoms into the nanowire, the electronic properties of the Cd12O12-based nanowire present dramatic changes, and the system transforms from semiconducting to metallic. It can provide a theoretical guidance for the potential application of Cd12O12-based semiconductor devices.
关键词： Assembly,Band gap regulation,Na doped,Cd12O12 cage cluster,Cd12O12 nanowire
更新于2025-09-23 15:21:01
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Surface Regulation of CsPbBr <sub/>3</sub> Quantum Dots for Standard Blue-Emission with Boosted PLQY
摘要： It is demonstrated that, via surface treatment of CsPbBr3 perovskite quantum dots (PeQDs) by introducing small amount of organic ammonium chlorides possessing short alkyl chain (C ≤ 4) in methyl acetate in the typical purification process, the emission can be tuned from green to blue region with boosted photoluminescence quantum yield (PLQY). The Cl? mainly works on the surface of PeQDs to fill bromide vacancy, which generates a passivated mixed-halide surface and avoids formation of defects deep within bandgap. Meanwhile, the replacement of initial long-chain ligands with short chain ammonium moiety benefits the film PLQY. Accordingly, a standard blue emission of 461 nm with a high film PLQY of 52% is accessed and the corresponding colloidal shows a PLQY of 80% at 456 nm. This method is also proved to be a versatile tool to boost the PLQY of PeQDs by using short chain ammonium halides bearing the same X with the initial CsPbX3. A near-unity colloidal PLQY of 97% and 98% is achieved for CsPbBr3 and CsPbI3 respectively. Quantum dots light-emitting diode (QLED) with treated CsPbBr3 affords a standard blue electroluminescence of 459 nm and a maximum external quantum efficiency of 0.3%.
关键词： perovskite quantum dots,vacancy passivation,surface regulation,standard blue emission
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE 15th Brazilian Power Electronics Conference and 5th IEEE Southern Power Electronics Conference (COBEP/SPEC) - Santos, Brazil (2019.12.1-2019.12.4)] 2019 IEEE 15th Brazilian Power Electronics Conference and 5th IEEE Southern Power Electronics Conference (COBEP/SPEC) - Optimal Voltage Coordinated Control for Grid-connected Photovoltaic Systems
摘要： The intermittent penetration of Grid-connected photovoltaic systems and load changing in distribution feeders can cause voltage ?uctuation. This paper aims to analyze the performance of different power control strategies to avoid overvoltage in MV feeders. The strategies use Volt/Var control and Volt/Watt control techniques to ?nd the optimal active or reactive power to be injected/absorbed by the PV inverters with the aim to minimize the voltage deviation and power losses and also coordinate the grid-connected photovoltaic system with the voltage regulation devices of distribution feeders. The strategies are tested in the IEEE 13 node test feeder.
关键词： active and reactive power control,grid-connected photovoltaic systems,Voltage regulation
更新于2025-09-23 15:21:01