182 research outputs found
Optimal Scheduling of Energy Storage Using A New Priority-Based Smart Grid Control Method
This paper presents a method to optimally use an energy storage system (such as a battery)
on a microgrid with load and photovoltaic generation. The purpose of the method is to employ the
photovoltaic generation and energy storage systems to reduce the main grid bill, which includes
an energy cost and a power peak cost. The method predicts the loads and generation power of
each day, and then searches for an optimal storage behavior plan for the energy storage system
according to these predictions. However, this plan is not followed in an open-loop control structure
as in previous publications, but provided to a real-time decision algorithm, which also considers
real power measures. This algorithm considers a series of device priorities in addition to the storage
plan, which makes it robust enough to comply with unpredicted situations. The whole proposed
method is implemented on a real-hardware test bench, with its different steps being distributed
between a personal computer and a programmable logic controller according to their time scale.
When compared to a different state-of-the-art method, the proposed method is concluded to better
adjust the energy storage system usage to the photovoltaic generation and general consumption.Unión Europea ID 100205Unión Europea ID 26937
Analysis of the power balance In the cells of a multilevel cascaded H-Bridge converter
Multilevel cascaded H-Bridge converters (CHB)
have been presented as a good solution for high power applications.
In this way, several control and modulation techniques
have been proposed for this power converter topology. In this
paper the steady state power balance in the cells of the single
phase two cell CHB is studied. The capability to be supplied with
active power from the grid or to deliver active power to the grid
in each cell is analyzed according to the dc-link voltages and
the desired ac output voltage value. Limits of the maximum and
minimum input active power for stable operation of the CHB are
addressed. Simulation results are shown to validate the presented
analysis
Adaptive Vectorial Filter for Grid Synchronization of Power Converters Under Unbalanced and/or Distorted Grid Conditions
This paper presents a new synchronization scheme for detecting multiple positive-/negative-sequence frequency harmonics in three-phase systems for grid-connected power converters. The proposed technique is called MAVF-FLL because it is based on the use of multiple adaptive vectorial filters (AVFs) working together inside a harmonic decoupling network, resting on a frequency-locked loop (FLL) which makes the system frequency adaptive. The method uses the vectorial properties of the three-phase input signal in the αβ reference frame in order to obtain the different harmonic components. The MAVF-FLL is fully designed and analyzed, addressing the tuning procedure in order to obtain the desired and predefined performance. The proposed algorithm is evaluated by both simulation and experimental results, demonstrating its ability to perform as required for detecting different harmonic components under a highly unbalanced and distorted input grid voltage
Optimization-Based Capacitor Balancing Method with Customizable Switching Reduction for CHB Converters
This paper presents a method for switching reduction in cascaded H-bridge converters.
Given the wide applicability of this topology, it would be especially desirable to increase its efficiency with switching losses reduction techniques. Since this type of converter requires voltage
balancing methods, several modulation methods consider the possibility of combining the balancing
and switching reduction goals together. In this paper, a previously disclosed optimization-based
balance method was modified further to consider the switching losses in its objective function. Each
commutation was penalized in proportion to the phase current and the module voltage, thus avoiding
commutations that would produce the most losses but tolerating low-losses commutations. The
structure of the original method was maintained so that the algorithm could be applied with minimal
change. The results show that it is possible to reduce the switching up to 14% without any noticeable
drawback and up to 22% at the cost of a greater DC-link ripple. It is also possible to selectively reduce
the effective switching frequency of only some modules, making it significantly low. This extends
the adaptability of the converter, possibly allowing hybrid converters with modules of different
transistor technologies.Horizon 2020. Trusted European SiC Value Chain for a Greener Economy PCI2021-121986, TRANSFORM
A Model-Based Direct Power Control for Three-Phase Power Converters
Direct Power Control (DPC) technique has been
widely used as control strategy for three-phase power rectifiers
due to its simplicity and good performance. The DPC uses the
instantaneous active and reactive power to control the power
converter, the controller design has been proposed as a direct
control with a look up table (LUT), and in recent works, as an
indirect control with an inner control loop with proportional plus
integral controllers for the instantaneous active and reactive
power errors. In this paper a model-based DPC for three-phase
power converters is designed, obtaining expressions for the input
control signal which allow to design an adaptive control law
minimizing the errors introduced by the parameters uncertainties
as the smoothing inductor value or the grid frequency. Controller
design process, stability study of the system and experimental
results for a synchronous three-phase power rectifier prototype
are presented to validate the proposed controller
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
Optimization-Based Capacitor Balancing Method with Selective DC Current Ripple Reduction for CHB Converters
From its introduction to the present day, Cascaded H-Bridge multilevel converters were employed on numerous applications. However, their floating capacitor, while advantageous for some applications (such as photovoltaic) requires the usage of balancing methods by design. Over the years, several such methods were proposed and polished. Some of these methods use optimization techniques or inject a zero-sequence voltage to take advantage of the converter redundancies. This paper describes an optimization-based capacitor balancing method with additional features. It can drive each module DC-Link to a different voltage for independent maximum power point tracking in photovoltaic applications. Moreover, the user can specify the independent active power set points to modules connected to batteries or any other energy storage systems. Finally, DC current ripple can be reduced on some modules, which can extend the lifespan of any connected ultra-capacitors. The method as a whole is tested on real hardware and compared with the state-of-the-art. In its simplest configuration, the presented method shows greater speed, robustness, and current wave quality than the state-of-the-art alternative in spite of producing about 1/3 fewer commutations. Its other characteristics provide additional functionalities and improve the adaptability of the converter to other applications.European Research Council: 101007237Ministerio de Ciencia e Innovación (MICINN): BES-2017-07992
Control del Equilibrio de las Tensiones de los Condensadores Flotantes en Convertidores Multinivel de Capacidades Flotantes
SEMINARIO ANUAL DE AUTOMATICA, ELECTRONICA INDUSTRIAL E INSTRUMENTACION () (.2006.GIJON)Los convertidores de capacidades flotantes
multinivel se presentan como una alternativa a otro tipo
de topologías multinivel presentando ciertas ventajas. Sin
embargo, presentan desventajas como el desequilibrio de
tensiones de los condensadores flotantes introduciendo
distorsión en las tensiones moduladas por el convertidor.
Se presenta en este trabajo un algoritmo para controlar el
equilibrio de estas tensiones. Este algoritmo se basa en la
elección de los estados de los transistores dentro de la
secuencia de conmutación usando modulación Space
Vector. Este algoritmo es completamente general siendo
aplicable a cualquier número de niveles e independiente
de la carga. Se presentan todas las expresiones
matemáticas necesarias para el control mostrándose
resultados de simulación para demostrar el buen
funcionamiento de la estrategia de control propuesta. Se
muestran los límites de controlabilidad del algoritmo
comparándolo con los límites obtenidos para otras
topologías de convertidores multinivel
DC-Voltage-Ratio Control Strategy for Multilevel Cascaded Converters Fed With a Single DC Source
Recently, a multilevel cascaded converter fed with a single DC source has been presented. An analysis of the steady-state working limits of this type of converter is presented in this paper. Limits of the maximum output voltage and the minimum and maximum loading conditions for stable operation of the converter are addressed. In this paper, a way to achieve any DC voltage ratio (inside the stable operation area of the converter) between the H-bridges of the single-DC-source cascaded H-bridge converter is presented. The proposed DC-voltage-ratio control is based on a time-domain modulation strategy that avoids the use of inappropriate states to achieve the DC-voltage-ratio control. The proposed technique is a feedforward-modulation technique which takes into account the actual DC voltage of each H-bridge of the converter, leading to output waveforms with low distortion. In this way, the dc voltage of the floating H-bridge can be controlled while the output voltage has low distortion independently of the desired DC voltage ratio. Experimental results from a two-cell cascaded converter are presented in order to validate the proposed DC-voltage-ratio control strategy and the introduced concepts.Ministerio de Ciencia y Tecnología TEC2006-03863Junta de Andalucía EXC/2005/TIC-117
Plaguicidas y salud de la población
Los plaguicidas son la forma dominante del combate a las plagas. Su empleo conlleva diversos riesgos, tanto para el ambiente como para la salud de los trabajadores expuestos y de la población en general. Los efectos a la salud de tipo agudo eran anteriormente los más considerados; sin embargo, en las dos últimas décadas han tomado importancia los efectos crónicos, tales como daños en el sistema nervioso central, teratogénesis, mutaciones, cáncer, entre otros. En este artículo se resumen los principales efectos a la salud reportados en la literatura mundial por la exposición a plaguicidas, particularmente los de tipo crónico en la población ocupacionalmente expuesta, concluyendo con las propuestas de investigación hechas en el área
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