5,444 research outputs found
The role of front-end ac/dc converters in hybrid ac/dc smart homes: Analysis and experimental validation
Electrical power grids are rapidly evolving into smart grids, with smart homes also making an important contribution to this. In fact, the well-known and emerging technologies of renewables, energy storage systems and electric mobility are each time more distributed throughout the power grid and included in smart homes. In such circumstances, since these technologies are natively operating in DC, it is predictable for a revolution in the electrical grid craving a convergence to DC grids. Nevertheless, traditional loads natively operating in AC will continue to be used, highlighting the importance of hybrid AC/DC grids. Considering this new paradigm, this paper has as main innovation points the proposed control algorithms regarding the role of front-end AC/DC converters in hybrid AC/DC smart homes, demonstrating their importance for providing unipolar or bipolar DC grids for interfacing native DC technologies, such as renewables and electric mobility, including concerns regarding the power quality from a smart grid point of view. Furthermore, the paper presents a clear description of the proposed control algorithms, aligned with distinct possibilities of complementary operation of front-end AC/DC converters in the perspective of smart homes framed within smart grids, e.g., enabling the control of smart homes in a coordinated way. The analysis and experimental results confirmed the suitability of the proposed innovative operation modes for hybrid AC/DC smart homes, based on two different AC/DC converters in the experimental validation
Comparisons between synchronizing circuits to control algorithms for single-phase active converters
This paper presents a comparative analysis between synchronizing circuits applied to control algorithms for single-phase active converters. One of these synchronizing circuits corresponds to the single-phase PLL (Phase Locked Loop), implemented in α-β coordinates, whereas the other one corresponds to the E-PLL (Enhanced PLL). These synchronizing circuits are compared in several aspects as processing and settling time and memory space requirements. Moreover, the performance of a single-phase back-to-back converter is also presented, with its control algorithm based on these Synchronizing Circuits. Each one of the control algorithms were implemented in a DSP microprocessor TMS320F2812F from Texas Instruments. Simulation and experimental results, through a back-to-back converter prototype, are presented.Fundação para a Ciência e a Tecnologia (FCT
Construction of coherent states for physical algebraic systems
We construct a general state which is an eigenvector of the annihilation
operator of the Generalized Heisenberg Algebra. We show for several systems,
which are characterized by different energy spectra, that this general state
satisfies the minimal set of conditions required to obtain Klauder's minimal
coherent states.Comment: 15 pages, 3 figure
Distributing multipartite entanglement over noisy quantum networks
A quantum internet aims at harnessing networked quantum technologies, namely by distributing bipartite entanglement between distant nodes. However, multipartite entanglement between the nodes may empower the quantum internet for additional or better applications for communications, sensing, and computation. In this work, we present an algorithm for generating multipartite entanglement between different nodes of a quantum network with noisy quantum repeaters and imperfect quantum memories, where the links are entangled pairs. Our algorithm is optimal for GHZ states with 3 qubits, maximising simultaneously the final state fidelity and the rate of entanglement distribution. Furthermore, we determine the conditions yielding this simultaneous optimality for GHZ states with a higher number of qubits, and for other types of multipartite entanglement. Our algorithm is general also in the sense that it can optimize simultaneously arbitrary parameters. This work opens the way to optimally generate multipartite quantum correlations over noisy quantum networks, an important resource for distributed quantum technologies.info:eu-repo/semantics/publishedVersio
Nonlinear Relativistic and Quantum Equations with a Common Type of Solution
Generalizations of the three main equations of quantum physics, namely, the
Schr\"odinger, Klein-Gordon, and Dirac equations, are proposed. Nonlinear
terms, characterized by exponents depending on an index , are considered in
such a way that the standard linear equations are recovered in the limit . Interestingly, these equations present a common, soliton-like,
travelling solution, which is written in terms of the -exponential function
that naturally emerges within nonextensive statistical mechanics. In all cases,
the well-known Einstein energy-momentum relation is preserved for arbitrary
values of
A control strategy for a three-phase four-wire shunt active filter
This paper presents a control strategy for a three-
phase four-wire shunt active filter. The shunt active filter is a custom-power device capable to compensate, in real time, harmonics, unbalances and power factor in an electrical
installation. In this work the power circuit is based on a three-leg
IGBT inverter, with the dc-link composed by two capacitors
connected in split. Thus the neutral point is connected directly to
the midpoint of the dc-link capacitors. Its control system is
composed by an algorithm based on the active and non-active
currents together with a synchronizing circuit, and a novel
algorithm to keep the voltages of the dc-link capacitors balanced
and regulated. Due to the applied power-inverter topology, it is
imperative to keep these voltages of the dc-link capacitors balanced in order to avoid malfunctioning of the active filter. To validate the proposed control strategy, simulation and experimental results are presented
Simulation of VUV electroluminescence in micropattern gaseous detectors: the case of GEM and MHSP
Electroluminescence produced during avalanche development in gaseous
avalanche detectors is an useful information for triggering, calorimetry and
tracking in gaseous detectors. Noble gases present high electroluminescence
yields, emitting mainly in the VUV region. The photons can provide signal
readout if appropriate photosensors are used. Micropattern gaseous detectors
are good candidates for signal amplification in high background and/or low rate
experiments due to their high electroluminescence yields and radiopurity. In
this work, the VUV light responses of the Gas Electron Multiplier and of the
Micro-Hole Strip Plate, working with pure xenon, are simulated and studied in
detail using a new and versatile C++ toolkit. It is shown that the solid angle
subtended by a photosensor placed below the microstructures depends on the
operating conditions. The obtained absolute EL yields, determined for different
gas pressures and as functions of the applied voltage, are compared with those
determined experimentally.Comment: Accepted for publication in Journal of Instrumentatio
Primary and secondary scintillation measurements in a xenon Gas Proportional Scintillation Counter
NEXT is a new experiment to search for neutrinoless double beta decay using a
100 kg radio-pure high-pressure gaseous xenon TPC. The detector requires
excellent energy resolution, which can be achieved in a Xe TPC with
electroluminescence readout. Hamamatsu R8520-06SEL photomultipliers are good
candidates for the scintillation readout. The performance of this
photomultiplier, used as VUV photosensor in a gas proportional scintillation
counter, was investigated. Initial results for the detection of primary and
secondary scintillation produced as a result of the interaction of 5.9 keV
X-rays in gaseous xenon, at room temperature and at pressures up to 3 bar, are
presented. An energy resolution of 8.0% was obtained for secondary
scintillation produced by 5.9 keV X-rays. No significant variation of the
primary scintillation was observed for different pressures (1, 2 and 3 bar) and
for electric fields up to 0.8 V cm-1 torr-1 in the drift region, demonstrating
negligible recombination luminescence. A primary scintillation yield of 81 \pm
7 photons was obtained for 5.9 keV X-rays, corresponding to a mean energy of 72
\pm 6 eV to produce a primary scintillation photon in xenon.Comment: 16 pages, 10 figures, accepted for publication in JINS
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