Development of a lifetime model for VRLA batteries used in wind turbine generators
01 Jan 2011-pp 505
TL;DR: In this paper, an approach to predict the remaining lifetime of lead-acid battery is described, which is used to provide back-up power to keep essential devices within wind turbine generators operational under emergency conditions.
Abstract: An approach to predict the remaining lifetime of lead-acid battery is described. The battery is used to provide back-up power to keep essential devices within wind turbine generators operational under emergency conditions. The approach is developed from a circuit model of the battery. From the results of laboratory tests, changes in the model parametric values due to ambient temperature variations, battery aging effects as well as discharge current level have been quantified. Through a developed computational method, the terminal voltage and state of charge of the battery at any other discharging conditions can then be calculated. The discharge profile allows one to predict the remaining lifetime of the battery. The predicted results appear to agree most satisfactorily with that obtained from laboratory measurements.
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TL;DR: In this article, a two-dimensional mathematical model of the lead-acid cell is presented, which details nonuniformities along cell height as well as thickness, showing significant variations of current density and other variables in cell height.
Abstract: A two-dimensional mathematical model of the lead-acid cell that details nonuniformities along cell height as well as thickness is presented. The model is an extension of earlier, one-dimensional models that simulate variation across the cell thickness alone. The model results show significant variations of current density and other variables in cell height, even at relatively low rates of discharge. The local electrochemical reaction rates are lowest at the bottom center of the electrodes and highest at the top. As discharge proceeds, the distributions in reaction rates and current density become more uniform from the top to the bottom of the cell. Also, significant variations in sulfuric acid concentration throughout the cell develop during discharge. The most concentrated acid is located at the bottom center of the negative electrode, and the most dilute acid is located at the top center of the positive electrode. Predictions of cell voltage are nearly that on one-dimensional model results for the conditions studied; however, variations across cell thickness by one-dimensional models should be considered as an average of the behavior along cell height for all practical operating conditions.
56 citations
TL;DR: In this article, the dynamic behavior of VRLA batteries can be predicted using theoretical cell model for basic processes, which is applied for viewing unobservable processes in battery by observable processes.
50 citations
TL;DR: In this paper, the discharge kinetics of the porous lead electrode have been investigated experimentally as a function of extent of discharge and the concentration of lignosulphonate expander.
Abstract: The discharge kinetics of the porous lead electrode have been investigated experimentally as a function of extent of discharge and the concentration of lignosulphonate expander. The results show that the kinetic model previously suggested for the recharge reaction can also be fitted to the anodic polarization curves. The structural changes in the electrode have been studied with SEM and electron microprobe analysis. These studies show that the higher discharge capacity at higher discharge currents of electrodes with organic expander in comparison to electrodes without expander is due to the formation of larger lead sulphate crystals in the former case. The discharge capacity at high current density (1000 A m−2) is limited by depletion of sulphuric acid in the pores only at concentrations lower than the normal.
23 citations
TL;DR: In this article, the diffusion of lead ions in a dissolution-electrodeposition mechanism is the rate-determining step during recharge at higher overvoltages, which can be explained by a dissolutionprecipitation mechanism and a solid-state reaction working in parallel.
Abstract: Cathodic polarization curves for discharged and partially recharged porous lead/lead sulfate electrodes exhibit limiting current densities, which increase strongly with a decreasing concentration of sulfuric acid. Together with an order of magnitude estimate of the diffusion rate, this indicates that the diffusion of lead ions in a dissolution-electrodeposition mechanism is the rate-determining step during recharge at higher overvoltages. The addition of organic expander impedes the electrode process. The rate of discharge influences the potentiostatic recharge curves in a way, which can be explained by a dissolution-precipitation mechanism and a solid-state reaction working in parallel.
19 citations
29 Oct 1995
TL;DR: In this article, a mathematical model was applied to derive general rules for temperature compensation, that describes the effects of float conditions and kinetic cell parameters on electrode potentials and electrode reaction rates.
Abstract: Float charging of valve-regulated lead-acid batteries is a complex combination of various electrochemical reactions: internal-oxygen cycle, hydrogen evolution at the negative electrode, corrosion of the positive grid, and also discharge reactions of positive and negative electrodes that can occur in unfavourable circumstances. To derive general rules for temperature compensation, a mathematical model was applied, that describes the effects of float conditions and kinetic cell parameters on electrode potentials and electrode-reaction rates. The required kinetic parameters were determined in meticulous measurements with two quite different types of test cells, one with high, the other one with low oxygen reduction efficiency. The model assumptions were verified by experimental results within reachable accuracy. Optimum float voltage is determined by certain polarisation of positive and negative electrodes. Effects of float voltage and temperature on electrode polarisation were simulated in the range between 0 and 50/spl deg/C.
16 citations