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

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)

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

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

SoC estimation in lithium-ion batteries with noisy measurements and absence of excitation

Accurate State-of-Charge estimation is crucial for applications that utilise lithium-ion batteries. In real-time scenarios, battery models tend to present significant uncertainty, making it desirable to jointly estimate both the State of Charge and relevant unknown model parameters. However, parameter estimation typically necessitates that the battery input signals induce a persistence of excitation property, a need which is often not met in practical operations. This document introduces a joint state of charge/parameter estimator that relaxes this stringent requirement. This estimator is based on the Generalized Parameter Estimation-Based Observer framework. To the best of the authors’ knowledge, this is the first time it has been applied in the context of lithium-ion batteries. Its advantages are demonstrated through simulations.This research received support from the Spanish Ministry of Science and Innovation under projects MAFALDA (PID2021-126001OBC31 funded by MCIN/AEI/10.13039/501100011033/ ERDF,EU) This work is part of the project MASHED (TED2021-129927B-I00), funded by MCIN/ AEI/10.13039/501100011033 and by the European Union Next GenerationEU/PRTR. This research was funded by FI Joan Oró grant (code 2023 FI-1 00827), cofinanced by the European Union.Peer ReviewedPostprint (published version

Influence of Proton Conducting Cations on the Structure and Properties of 2D Anilate-Based Magnets

The syntheses, structures, magnetic, and proton conductivity properties of a family of bimetallic anilate-based compounds with inserted alkylammonium cations are presented. The structures of (Me2NH2)[MnIICrIII(Br2An)3]·2H2O (1), (Et2NH2)[MnIICrIII(Br2An)3] (2), (Et3NH)[MnIICrIII(Cl2An)3] (3), and [(Et)(i-Pr)2NH]-[MnIICrIII(Br2An)3]·(CHCl3)0.5·(H2O) (4) contain a 2D anionic network formed by Mn(II) and Cr(III) ions linked through anilate ligands. In 1, 2, and 3, the hexagonal holes of this network are occupied by Me2NH2+, Et2NH2+, or Et3NH+ cations. Interestingly, the small increase of size of the templating cation in 4 ([(Et)(i-Pr)2NH]+ in the place of Me2NH2+, Et2NH2+ or Et3NH+), gives rise to a different structure with half of the cations placed within the layers and the other one in the space between the layers. This leads to bilayers with an interlayer separation similar to those of 1, 2, and 3 separated by larger interbilayer distances. Compounds 1, 2, and 3 show a ferrimagnetic ordering with a Tc of 8.0 K (1), 8.9 K (2), and 8.0 K (3). In 4, the presence of different interlayer distances leads to a metamagnetic behavior when the sample is measured in contact with the mother liquor. The behavior changes in the dry sample, which shows a ferrimagnetic ordering as that of 1, 2, and 3 due to collapse of the structure as confirmed by powder X-ray diffraction. Interestingly, the metamagnetic behavior is recovered after reimmersing the crystals in the mother liquor proving the reversibility of the process. All solids are Grotthuss-type proton conductors with conductivity values ranging between 2.3 × 10−6 S·cm−1 for 3 and 2.4 × 10−5 S·cm−1 for 1 measured at 70 °C and 95% relative humidity and activation energies of ∼0.2 eV.EU (ERC Advanced Grant SPINMOL) CTQ2014-52758-P, MAT-2014-56143-R y MAT2016-77648-R del MINECO Unidad de Excelencia María de Maeztu MDM-2015-0538 de la Generalitat Valenciana P12-FQM-1656 de la Junta de Andalucí

How Poor Workstation Design Causes Musculoskeletal Disorders: Research from QOC Matrix the Workers’ Voice

An ergonomic intervention method based on QOC Matrix the workers’ voice was implemented in a study case. The diagnosis and analysis developed are used in improvement proposals for workstation redesign. The workers’ voice resulting from reports of the employee’ complaints and symptomatology was the base for a standardized method that comprises: (a) QOC questionnaire application, (b) risk factor categorization, (c) determination of unsafe and unhealthy ergonomic metrics, (d) figuring out the task content impact in the workers’ body, and (e) work system diagnosis. Since workers’ voice, the risk identification made included: (1) the task content linked to work method: repetitiveness associated with the sensor activation using the fingers and the repetitive movements include twist and the stretch of wrist, (2) workplace design regarding container height and injuries caused in wrists and elbows due to hits, (3) task developed regarding risk time exposition and workers position, and (4) workplace design regards to housing collector distance from filling area linked to workers position adopted for reach bags. Improvements included redesign of the workstation with a system of 90° exit discharge curve, one elevation system, and a photoelectric sensor in filling nozzle for automatic filling. As an improvement result, the activity called bags provision was eliminated from the task