252 research outputs found
Multi P2P Energy Trading Market, Integrating Energy Storage Systems and Used for Optimal Scheduling
The increasing use of renewable energy and storage systems by end users has changed the paradigm of electricity markets, with consumers changing their role from passive to active players, the so-called prosumers. Different countries have encouraged the aggregation of these prosumers in energy communities. In these communities, it is essential to create a market to manage energy exchanges between neighbors, who can sell surpluses or buy energy to reduce their bills. This paper presents the framework definition of a multi-peer-to-peer market. As contributions, it defines how storage systems can participate in the market and multiple exchanges between prosumers are possible. This market can be integrated in an optimization process to perform optimal scheduling in the community by setting an objective. All this has been tested in a community with 5 prosumers with generation and storage, where the effect of multiple exchanges and valuation of assets is observed, achieving as a result higher bill reductions
Sizing and Management of Energy Storage Systems in Large-Scale Power Plants Using Price Control and Artificial Intelligence
Energy storage systems are expected to play a fundamental part in the integration of
increasing renewable energy sources into the electric system. They are already used in power plants
for different purposes, such as absorbing the effect of intermittent energy sources or providing
ancillary services. For this reason, it is imperative to research managing and sizing methods that
make power plants with storage viable and profitable projects. In this paper, a managing method
is presented, where particle swarm optimisation is used to reach maximum profits. This method
is compared to expert systems, proving that the former achieves better results, while respecting
similar rules. The paper further presents a sizing method which uses the previous one to make the
power plant as profitable as possible. Finally, both methods are tested through simulations to show
their potential.Unión Europea Subvención 771066
Conventional Space-Vector Modulation Techniques versus the Single-Phase Modulator for Multilevel Converters
Space-vector modulation is a well-suited technique
to be applied to multilevel converters and is an important
research focus in the last 25 years. Recently, a single-phase
multilevel modulator has been introduced showing its conceptual
simplicity and its very low computational cost. In this paper,
some of the most conventional multilevel space-vector modulation
techniques have been chosen to compare their results with those
obtained with single-phase multilevel modulators. The obtained
results demonstrate that the single-phase multilevel modulators
applied to each phase are equivalent with the chosen wellknown
multilevel space-vector modulation techniques. In this
way, single-phase multilevel modulators can be applied to a
converter with any number of levels and phases avoiding the
use of conceptually and mathematically complex space-vector
modulation strategies. Analytical calculations and experimental
results are shown validating the proposed concepts
Efectos de la geometría del hombro de la herramienta sobre las propiedades mecánicas de juntas soldadas por fricción-agitación de aleación de aluminio AA1100
In this work were studied the effects of shoulder geometry of tool on microstructure evolution and mechanical properties of friction stir welded
joints of AA1100 aluminum alloy using a milling machine. Three designs of shoulder geometry were evaluated with the aim to induce different
distributions of thermal cycles in welding regions. Thermal cycles were measured using thermocouples and a data system acquisition. A
microstructural characterization and crystallographic analysis of the welded regions were carried out using optical, scanning electron microscopy,
and electron backscattering diffraction. The mechanical properties were measured by transverse tension, guided bend and hardness tests. The
weldability behavior was established based on the experimental data. Results showed that the features shoulder tools produced an important
effect on the thermal cycles, generating a plasticized wide region and biggest grain size in stir zone when compared with flat shoulder tool.En este trabajo se estudiaron los efectos de la geometría del hombro de la herramienta en la evolución de la microestructura y las propiedades
mecánicas de juntas soldadas de aleación de aluminio AA1100 obtenidos por fricción-agitación usando una máquina fresadora. Tres diseños de
hombros se evaluaron con el objetivo de inducir distribuciones diferentes de ciclos térmicos en las regiones de soldadura. Los ciclos térmicos se
midieron utilizando termopares y un sistema de adquisición de datos. Caracterización microestructural y análisis cristalográfico de las regiones
soldadas se hicieron usando, microscopía óptica y electrónica de barrido, además de difracción de electrones retrodispersados. Las propiedades
mecánicas se determinaron por ensayos de tracción, doblez guiado y pruebas de dureza. El comportamiento de la soldabilidad se estableció con base
en datos experimentales. Los resultados mostraron que las herramientas con hombro configurado tienen un efecto importante en los ciclos térmicos,
generando una amplia región plastificada y el mayor tamaño de grano en la zona de agitación en comparación con la herramienta de hombro plano
A novel space-vector algorithm for multilevel converters based on geometrical considerations using a new sequence control technique
his paper presents a fast and simple space vector modulation algorithm for voltage source multilevel converters for calculating the switching times and the space vectors using simple geometrical considerations. This method provides the nearest switching vectors sequence to the reference vector and calculates the on-state durations of the respective switching state vectors without involving trigonometric functions, look-up tables or coordinate system transformations which increase the computational load corresponding to the modulation of a multilevel converter. The low computational cost of the proposed method is always the same and it is independent of the number of levels of the converter. In addition, a new switching sequence control technique is presented for reducing the ripple of the DC-link voltage approximately in 66%
Risk Factors for Working Pregnant Women and Potential Adverse Consequences of Exposure: A Systematic Review
Objective: To assess the risk factors perceived as stressors by pregnant women in the
work environment and the possible adverse consequences of such exposure for the
normal development of pregnancy.
Methods: Systematic review, guided by the PRISMA guidelines, and using Pubmed,
Web of Science, Dialnet, SciELO, and REDIB databases. Methodological quality was
assessed using the critical appraisal tools for non-randomised studies of the Joanna
Briggs Institute.
Results: A total of 38 studies were included. The main risk factors found in the work
environment of pregnant women were chemical, psychosocial, physical-ergonomicmechanical
factors, and other work-related factors. The main adverse consequences
of exposure to these factors include low birth weight, preterm birth, miscarriage,
hypertension and pre-eclampsia, as well as various obstetric complications.
Conclusion: During pregnancy, working conditions that are considered acceptable in
normal situations may not be so during this stage due to the major changes that occur
during pregnancy. Many obstetric effects may have an important impact in the mother’s
psychological status; therefore, it is important to optimise working conditions during this
stage and to reduce or eliminate possible risksFunding for open access charge: Foundation for Science and Technology, Portugal (FCT)
Educational software interface for power electronic applications
The design of friendly user tools for power electronics applications is a hot topic among the researchers all over the world. In fact, the digital signal processors programming is a hard task which requires a deep knowledge of the specific hardware platform where the user control program is implemented. In this paper, a user interface for programming digital signal processors (DSP) to control a power electronic converter is presented. The proposed program, called jscomm, is currently used as a useful tool to understand how the DSP is programmed, to control a power converter safely and to monitor all the interesting variables of the power converter operation
Effects of shoulder geometry of tool on microstructure and mechanical properties of friction stir welded joints of AA1100 aluminum alloy
In this work were studied the effects of shoulder geometry of tool on microstructure evolution and mechanical properties of friction stir welded joints of AA1100 aluminum alloy using a milling machine. Three designs of shoulder geometry were evaluated with the aim to induce different distributions of thermal cycles in welding regions. Thermal cycles were measured using thermocouples and a data system acquisition. A microstructural characterization and crystallographic analysis of the welded regions were carried out using optical, scanning electron microscopy, and electron backscattering diffraction. The mechanical properties were measured by transverse tension, guided bend and hardness tests. The weldability behavior was established based on the experimental data. Results showed that the features shoulder tools produced an important effect on the thermal cycles, generating a plasticized wide region and biggest grain size in stir zone when compared with flat shoulder tool.En este trabajo se estudiaron los efectos de la geometría del hombro de la herramienta en la evolución de la microestructura y las propiedades mecánicas de juntas soldadas de aleación de aluminio AA1100 obtenidos por fricción-agitación usando una máquina fresadora. Tres diseños de hombros se evaluaron con el objetivo de inducir distribuciones diferentes de ciclos térmicos en las regiones de soldadura. Los ciclos térmicos se midieron utilizando termopares y un sistema de adquisición de datos. Caracterización microestructural y análisis cristalográfico de las regiones soldadas se hicieron usando, microscopía óptica y electrónica de barrido, además de difracción de electrones retrodispersados. Las propiedades mecánicas se determinaron por ensayos de tracción, doblez guiado y pruebas de dureza. El comportamiento de la soldabilidad se estableció con base en datos experimentales. Los resultados mostraron que las herramientas con hombro configurado tienen un efecto importante en los ciclos térmicos, generando una amplia región plastificada y el mayor tamaño de grano en la zona de agitación en comparación con la herramienta de hombro plano
Multi-dimensional modulation technique for cascaded multilevel converters
Multilevel cascaded H-bridge converters have found industrial application in the medium voltage high power range. In this paper, a generalized modulation technique for this type of converters based on a multi-dimensional control region is presented. Using the multi-dimensional control region, it is shown that all previous modulation techniques are particularized versions of the proposed method. Several possible solutions to develop a specific implementation of the modulation method are addressed in order to show the potential possibilities and the flexibility of the proposed technique. In addition, a feed-forward version of this technique is also introduced to determine the switching sequence and the switching times avoiding low harmonic distortion with unbalanced dc voltages. Experimental results are shown in order to validate the proposed concepts.Ministerio de Educación TEC2007-6187
Unidimensional modulation technique for cascaded multilevel converters
This paper presents a simple and low computational
cost modulation technique for multilevel cascaded H-bridge
converters. The technique is based on geometrical considerations
considering an unidimensional control region to determine the
switching sequence and the corresponding switching times. In
addition, a simple strategy to control the dc voltage ratio between
the H-bridges of the multilevel cascaded converter is presented.
Examples for the two-cell topology are shown but the proposed
technique can be applied to develop modulation methods for a
higher number of H-bridges. Experimental results are presented
to validate the proposed technique
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