Redox flow batteries: a literature review oriented to automatic control

This paper presents a literature review about the concept of redox flow batteries and its automation and monitoring. Specifically, it is focused on the presentation of all-vanadium redox flow batteries which have several benefits, compared with other existing technologies and methods for energy stored purposes. The main aspects that are reviewed in this work correspond to the characterization, modeling, supervision and control of the vanadium redox flow batteries. A research is presented where redox flow batteries are contextualized in the current energy situation, compared with other types of energy storage systems. Furthermore, a presentation about the current challenges on research, and the main existing installations is view. A discussion about the main dynamic models that have been proposed during last years, as well as the different control strategies and observers, is presented.Peer ReviewedPostprint (author's final draft

Unitized regenerative polymeric fuel cell modeling

The research's objective is to have a single machine to function as fuel cell and electrolyser based and needs, that is to say, unitized regenerative fuel cell (when fed to the machine with electric power and water flows will be obtained and H2 and O2 and conversely when the machine is fuelled with H2 and O2 will get water, heat and electricity) The study focuses on polymeric fuel cells and polymeric electrolysers. The development of this machine will make a very significant cost reduction (currently to use hydrogen as an energy store needed the electrolyser and fuel cell) as a single machine may replace the fuel cell and electrolyser. The achievement of the objective mentioned above, have been going by completing a series of stages. The stages addressed in this work are: ¿ A first stage, which will be studied in detail the polymeric fuel cells and polymeric electrolysers, in order to see the similarities between the machines and to design the unitized regenerative fuel cell. ¿ A second stage of simulation, which will develop models to show the behaviour of the unitized regenerative fuel cell and compare results with those obtained from the theoretical. ¿ A third stage of model verification generated polymer fuel cells and electrolyzers polymer on the market

Disseny d'un convertidor estàtic d'energia elèctrica via PIL (Processor in the Loop)

Aquest treball tracta sobre la realització d’un convertidor estàtic d’energia elèctrica, per al processament energètic en una microxarxa, mitjançant el procés PIL (Processor In the Loop). Per a realitzar el disseny de la microxarxa, s’ha estudiat els diferents components que formen part de la mateixa, presentant una estructura formada per un bloc de generació elèctrica, seguit dels dispositius encarregats del emmagatzematge d’energia que venen governats pels convertidors estàtics d’energia elèctrica. Per tal de poder validar el correcte funcionament del sistema es pretén realitzar el disseny físic d’un convertidor que pugui ser controlat a partir de l’entorn de simulació PSIM mitjançant la tècnica PIL. Per tal de poder realitzar la supervisió i control del mateix és necessari l’ús del DSP (Discrete-time Signal Processor, Digital Signal Processor) que permet controlar el sistema a partir dels paràmetres que es troben introduïts a les diferents simulacions realitzades amb el programa PSIM que disposa de la llibreria on es troba aquest dispositiu. D’aquesta forma es pot realitzar un estudi en temps real del comportament del convertidor realitzat. També es pretén comparar diferents mètodes de simulació que existeixen per a modelitzar sistemes energètics com els convertidors. Cal destacar la metodologia utilitzada per al control dels convertidors, destacant el control per inversió de fàcil implementació un cop es té realitzada la modelització energètica i estructural del sistema. Per a realitzar aquesta modelització s’empra la tècnica de la REM(Representació Energètica Macroscòpica)

Enhanced Magnetic Anisotropy of Mn12-acetate

Thin films of the Single Molecule Magnet (Mn12-acetate) have been fabricated on a Si-substrate by the Dip-and-Dry method, a simple and robust technique. Atomic force microscopy and X-ray photoelectron spectroscopy characterizations reveal that homogeneous, thin films of a few molecular layers with smoothness at the molecular level are deposited. Significant changes in magnetic properties of Mn12-acetate exposed to the same solvent were observed in zero-field-cooled and field-cooled magnetization, as well as ac-susceptibility measurements. The blocking temperature was found to increase to TB > 10 K at low magnetic fields, indicating an enhanced magnetic anisotropy.Comment: 14 pages, 4 figure

Voltage H8 control of a vanadium redox flow battery

Redox flow batteries are one of the most relevant emerging large-scale energy storage technologies. Developing control methods for them is an open research topic; optimizing their operation is the main objective to be achieved. In this paper, a strategy that is based on regulating the output voltage is proposed. The proposed architecture reduces the number of required sensors. A rigorous design methodology that is based on linear H8 synthesis is introduced. Finally, some simulations are presented in order to analyse the performance of the proposed control system. The results show that the obtained controller guaranties robust stability and performance, thus allowing the battery to operate over a wide range of operating conditions. Attending to the design specifications, the controlled voltage follows the reference with great accuracy and it quickly rejects the effect of sudden current changes.Peer ReviewedPostprint (published version

Online state of charge estimation for a vanadium redox flow battery with unequal flow rates

This study presents an observer-based methodology to estimate, in real-time, the state of charge of a Vanadium redox flow battery. Different from the available results in the literature, this work presents a new estimator that distinguishes between the concentration in the tank and cell parts of the system. Moreover, it presents an estimation of the state of charge that can deal with both balanced and unbalanced situations. The model used for the observer design is a nonlinear electrochemical model. A nonlinear observer is proposed, designed and validated through simulation and in an experimental prototype.Peer ReviewedPostprint (published version

Estimación del estado de carga y coeficientes de difusión en baterías de flujo redox

Estimation of the state of charge and diffusion coefficients in redox flow batteries. This paper presents an observer for the estimation of the state of charge of redox flow batteries. The observer is high gain and is based on a non-linear dynamic model, which uses a realistic approach differentiating between the total electrolyte concentrations in the two parts of the system. It is shown that the state of charge can be estimated by measuring cell voltage and a high gain observer. However, the precision of the estimate is affected by the uncertainty in the diffusion coefficients of the system. For this reason, the observer is strengthened by estimating adaptive parameters of immersion and invariance. Finally, the results are validated in a numerical simulationPeer ReviewedPostprint (published version

Relación entre el clima organizacional y la satisfacción del cliente en una empresa de servicios telefónicos

El propósito de este estudio fue determinar el grado de relación entre el clima organizacional y la satisfacción del cliente. Con este fin se aplico una escala de Clima Organizacional a un grupo de 200 empleados de la empresa Telefónica del Perú y un Cuestionario de Satisfacción a sus respectivos clientes. La Hipótesis Principal señalaba que existía relación entre el Clima Organizacional y la Satisfacción del Cliente en el sentido que al mejorar el Clima Organizacional se incrementa la Satisfacción del Cliente. La principal conclusión comprobó que hay relación entre las dos variables, es decir, el clima organizacional se relaciona con la satisfacción del cliente. A nivel de las hipótesis específicas se comprobó que las Relaciones Interpersonales, el Estilo de Dirección, el Sentido de Pertenencia, la Retribución, la Estabilidad, la Claridad y Coherencia de la Dirección y los Valores Colectivos se relacionaban significativamente con la satisfacción del cliente en la empresa Telefónica del Perú. No se encontró relación entre la Distribución de Recursos y la satisfacción del cliente en la empresa Telefónica del Perú. Palabras Claves: Clima Organizacional; Satisfacción del Cliente; Atención al Cliente; Calidad del Servicio.The purpose of this study was to determine the relationship grade between the organizational climate and the client's satisfaction. With this end you applies a scale of Organizational Climate to a group of 200 employees of the company Telefónica of the Peru and a Questionnaire of Satisfaction to their respective clients. The Main Hypothesis pointed out that relationship existed between the Organizational Climate and the Client's Satisfaction in the sense that is increased when improving the Organizational Climate the Client's Satisfaction. The main conclusion checked that there is relationship among the two variables, that is to say, the organizational climate is related with the client's satisfaction. At level of the specific hypotheses he/she was proven that the Interpersonal Relationships, the Style of Address, the Sense of Ownership, the Retribution, the Stability, the Clarity and Coherence of the Address and the Collective Values were related significantly with the client's satisfaction in the company Telefónica of the Peru. He/she was not relationship between the Distribution of Recur-sos and the client's satisfaction in the company Telefónica of the Peru. Key Words: Organizational climate; Satisfaction of the Client; Attention to the Client; Quality of the Service.Tesi

Las "Músicas" de Augusto Villabrille (Clotaldo)

Copia digital. Valladolid : Junta de Castilla y León. Consejería de Cultura y Turismo, 2009-201

Modelling and estimation of vanadium redox flow batteries: a review

Redox flow batteries are one of the most promising technologies for large-scale energy storage, especially in applications based on renewable energies. In this context, considerable efforts have been made in the last few years to overcome the limitations and optimise the performance of this technology, aiming to make it commercially competitive. From the monitoring point of view, one of the biggest challenges is the estimation of the system internal states, such as the state of charge and the state of health, given the complexity of obtaining such information directly from experimental measures. Therefore, many proposals have been recently developed to get rid of such inconvenient measurements and, instead, utilise an algorithm that makes use of a mathematical model in order to rely only on easily measurable variables such as the system’s voltage and current. This review provides a comprehensive study of the different types of dynamic models available in the literature, together with an analysis of the existing model-based estimation strategies. Finally, a discussion about the remaining challenges and possible future research lines on this field is presented.The research that gave rise to these results received support from “la Caixa” Foundation (ID 100010434. Fellowship code LCF/BQ/DI21/11860023) , the CSIC program for the Spanish Recovery, Transformation and Resilience Plan funded by the Recovery and Resilience Facility of the European Union, established by the Regulation (EU) 2020/2094, CSIC Interdisciplinary Thematic Platform (PTI+) Transición Energética Sostenible+ (PTI-TRANSENER+ project TRE2103000), the Spanish Ministry of Science and Innovation (project PID2021-126001OB-C31 funded by MCIN/AEI/10.13039/501100011033 / ERDF,EU) and the Spanish Ministry of Economy and Competitiveness under Project DOVELAR (ref. RTI2018-096001-B-C32).Peer ReviewedPostprint (published version