Open Access
Identification of critical parameters for the design of energy management algorithms for Li-ion batteries operating in PV power plants
(IEEE, 2020) Berrueta Irigoyen, Alberto; Soto Cabria, Adrián; Marcos Álvarez, Javier; Parra Laita, Íñigo de la; Sanchis Gúrpide, Pablo; Ursúa Rubio, Alfredo; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, ReBMS PJUPNA1904; Gobierno de Navarra / Nafarroako Gobernua, 0011-1411-2018-000029 GERA
Lithium-ion batteries are gaining importance for a variety of applications due to their price decrease and characteristics improvement. For a proper use of such storage systems, an energy management algorithm (EMA) is required. A number of EMAs, with various characteristics, have been published recently, given the diverse nature of battery problems. The EMA of deterministic battery problems is usually based on an optimization algorithm. The selection of such an algorithm depends on a few problem characteristics, which need to be identified and closely analyzed. The aim of this article is to identify the critical optimization problem parameters that determine the most suitable EMA for a Li-ion battery. With this purpose, the starting point is a detailed model of a Li-ion battery. Three EMAs based on the algorithms used to face deterministic problems, namely dynamic, linear, and quadratic programming, are designed to optimize the energy dispatch of such a battery. Using real irradiation and power price data, the results of these EMAs are compared for various case studies. Given that none of the EMAs achieves the best results for all analyzed cases, the problem parameters that determine the most suitable algorithm are identified to be four, i.e., desired computation intensity, characteristics of the battery aging model, battery energy and power capabilities, and the number of optimization variables, which are determined by the number of energy storage systems, the length of the optimization problem, and the desired time step.
Open Access
Influence of the aging model of lithium-ion batteries on the management of PV self-consumption systems
(IEEE, 2018) Berrueta Irigoyen, Alberto; Pascual Miqueleiz, Julio María; San Martín Biurrun, Idoia; Sanchis Gúrpide, Pablo; Ursúa Rubio, Alfredo; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación; Gobierno de Navarra / Nafarroako Gobernua, PI038 INTEGRA-RENOVABLES
Lithium-ion batteries are gaining importance for a variety of applications due to their improving characteristics and decreasing price. An accurate knowledge of their aging is required for a successful use of these ESSs. The vast number of models that has been proposed to predict these phenomena raise doubts about the suitability of a model for a particular battery application. The performance of three models published for a Sanyo 18650 cylindrical cell in a self-consumption system are compared in this work. Measured photovoltaic production and home consumption with a sampling frequency of 15 minutes are used for this comparison. The different aging predictions calculated by these three models are analyzed, compared and discussed. These comparison is particularized for two management strategies. The first of them maximizes the self-consumption PV energy, while the second reduces the maximum power peak demanded from the grid.
Open Access
Impact of micro-cycles on the lifetime of lithium-ion batteries - EIS analysis
(IEEE, 2024-07-30) Nováková, Katerina; Berrueta Irigoyen, Alberto; Soto Cabria, Adrián; Sanchis Gúrpide, Pablo; Ursúa Rubio, Alfredo; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC; Gobierno de Navarra / Nafarroako Gobernua
Experimental studies of lithium-ion batteries are very often based only on deep charge and discharge cycles. However, these test profiles do not fully reflect the actual operation of the battery in an electric vehicle or in stationary applications, where the battery is not only loaded during the main charging and discharging profiles, but it is also stressed by the current throughput caused by renewable power fluctuations or by auxiliary services. These cycles, which are superimposed to the main charge and discharge processes and have a depth of discharge not exceeding 2%, are called micro-cycles. Although there are several simulation studies that attempt to capture this issue, there is still no comprehensive experimental study that has the phenomena that occur during micro-cycling. This paper presents an experimental analysis of micro-cycles, providing a detailed view of the different processes taking place in the battery during aging, by means of a detailed analysis of the results from electrochemical impedance spectroscopy (EIS). By studying the single electrochemical processes in detail, this paper explains the benefits of micro-cycling in terms of extending the lifetime of the battery.
Open Access
Combined dynamic programming and region-elimination technique algorithm for optimal sizing and management of lithium-ion batteries for photovoltaic plants
(Elsevier, 2018) Berrueta Irigoyen, Alberto; Heck, Michael; Jantsch, Martin; Ursúa Rubio, Alfredo; Sanchis Gúrpide, Pablo; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute for Advanced Materials and Mathematics - INAMAT2; Ingeniería Eléctrica, Electrónica y de Comunicación; Gobierno de Navarra / Nafarroako Gobernua PI038 INTEGRA-RENOVABLES
The unpredictable nature of renewable energies is drawing attention to lithium-ion batteries. In order to make full utilization of these batteries, some research works are focused on the management of existing systems, while others propose sizing techniques based on business models. However, in order to optimise the global system, a comprehensive methodology that considers both battery sizing and management at the same time is needed. This paper proposes a new optimisation algorithm based on a combination of dynamic programming and a region elimination technique that makes it possible to address both problems at the same time. This is of great interest, since the optimal size of the storage system depends on the management strategy and, in turn, the design of this strategy needs to take account of the battery size. The method is applied to a real installation consisting of a 100 kWp rooftop photovoltaic plant and a Li-ion battery system connected to a grid with variable electricity price. Results show that, unlike conventional optimisation methods, the proposed algorithm reaches an optimised energy dispatch plan that leads to a higher net present value. Finally, the tool is used to provide a sensitivity analysis that identifies key informative variables for decision makers
Open Access
Influence of renewable power fluctuations on the lifetime prediction of lithium-ion batteries in a microgrid environment
(IEEE, 2019) Soto Cabria, Adrián; Berrueta Irigoyen, Alberto; Sanchis Gúrpide, Pablo; Ursúa Rubio, Alfredo; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación; Gobierno de Navarra / Nafarroako Gobernua
This contribution analyses lifetime estimation errors due to the effect of power fluctuations in lithium-ion batteries connected to microgrids when different time steps are used for the calculations. Usually, not every second data are available or the computational cost is excessively high. Those facts result in the use of larger time steps. However, the increase of the time steps may turn out in too optimistic predictions. Data from a real microgrid make it possible to optimize calculation times while keeping low errors. The results show that when 1 minute time step is set, the computation time is reduced by 14.4 times while the lifetime overstatement is only 3.5-5.2% higher, depending on the aging model.
Open Access
Experimental assessment of first- and second-life electric vehicle batteries: performance, capacity dispersion, and aging
(IEEE, 2021) Braco Sola, Elisa; San Martín Biurrun, Idoia; Berrueta Irigoyen, Alberto; Sanchis Gúrpide, Pablo; Ursúa Rubio, Alfredo; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa; Gobierno de Navarra / Nafarroako Gobernua
Nowadays, the reuse of electric vehicle batteries is considered to be a feasible alternative to recycling, as it allows them to benefit from their remaining energy capacity and to enlarge their lifetime. Stationary applications, such as self-consumption or off-grid systems support, are examples of second-life (SL) uses for retired batteries. However, reused modules that compose these batteries have heterogeneous properties, which limit their performance. This article aims to assess the influence of degradation in modules from electric vehicles, covering three main aspects: performance, capacity dispersion, and extended SL behavior. First, a complete characterization of new and reused modules is carried out, considering three temperatures and three discharge rates. In the second stage, intra- and intermodule capacity dispersions are evaluated with new and reused samples. Finally, the behavior during SL is also analyzed, through an accelerated cycling test so that the evolution of capacity and dispersion are assessed. Experimental results show that the performance of reused modules is especially undermined at low temperatures and high current rates, as well as in advanced stages of aging. The intramodule dispersion is found to be similar in reused and new samples, while the intermodule differences are nearly four times greater in SL.
Open Access
Critical comparison of energy management algorithms for lithium-ion batteries in renewable power plants
(IEEE, 2019) Berrueta Irigoyen, Alberto; Soto Cabria, Adrián; García Solano, Miguel; Parra Laita, Íñigo de la; Sanchis Gúrpide, Pablo; Ursúa Rubio, Alfredo; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Lithium-ion batteries are gaining importance for a variety of applications due to their price decrease and characteristics improvement. A good energy management strategy is required in order to increase the profitability of an energy system using a Li-ion battery for storage. The vast number of management algorithms that has been proposed to optimize the achieved profit, with diverse computational power requirements and using models with different complexity, raise doubts about the suitability of an algorithm and the required computation power for a particular application. The performance of three energy management algorithms based on linear, quadratic, and dynamic programming are compared in this work. A realistic scenario of a medium-sized PV plant with a constraint of peak shaving is used for this comparison. The results achieved by the three algorithms are compared and the grounds of the differences are analyzed. Among the three compared algorithms, the quadratic one seems to be the most suitable for renewableenergy applications, given the undue simplification of the battery aging required by the linear algorithm and the discretization and computational power required by a dynamic algorithm.
Open Access
Impact of micro-cycles on the lifetime of lithium-ion batteries: an experimental study
(Elsevier, 2022) Soto Cabria, Adrián; Berrueta Irigoyen, Alberto; Mateos Inza, Miren; Sanchis Gúrpide, Pablo; Ursúa Rubio, Alfredo; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa Gobierno de Navarra / Nafarroako Gobernua
Experimental aging studies are commonly conducted on lithium-ion batteries by full charge and discharge cycles. However, such profiles may differ from the actual operation of batteries in electric vehicles and stationary applications, where they are subjected to different partial charges and discharges. These partial cycles, which take place during a main charge or discharge process, are called micro-cycles if their depth of discharge is <2 %. A number of authors have pointed out the relevance of the time resolution to estimate the energy throughput of a battery due to these micro-cycles in applications such as renewable microgrids. However, to the best of our knowledge, there are no experimental studies in the literature that assess the impact of these micro-cycles on battery degradation. In this article, the impact of micro-cycles on the loss of performance of a lithium-ion battery is experimentally studied. The results show that micro-cycles have a negligible, or even positive effect on the aging of lithium-ion cells compared to the aging caused by full cycles. In fact, if charge throughput or equivalent full cycles are used to measure the use of a battery, then cells subjected to micro-cycles exhibit a 50 % extended lifetime compared to cells only subjected to full cycles. More precisely, cells including micro-cycles with depth of discharge of 0.5 % lasted for nearly 3000 equivalent full cycles, whereas cells aged under standard deep cycles lasted for no >1500. Nevertheless, if the number of deep cycles, disregarding micro-cycles, is the unit to measure battery use, then the degradation of cells with and without micro-cycles is similar. Based on this result, the number of cycles can be identified as a more accurate variable to measure the use of a cell, in comparison to charge throughput.
Open Access
On the technical reliability of lithium-ion batteries in a zero emission polar expedition
(IEEE, 2020) Soto Cabria, Adrián; Berrueta Irigoyen, Alberto; Sanchis Gúrpide, Pablo; Ursúa Rubio, Alfredo; Oficialdegui, Ignacio; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, PJUPNA1904
This contribution presents a technical analysis of the Lithium-ion batteries (LIBs) used in the WindSled project. In this project, an expedition has been carried out by means of a 0-emission vehicle that have covered more than 2500 kilometers in Antarctica Eastern Plateau pulled by kites. This adventure allowed the performance of 10 scientific experiments with a minimal disturbance of the polar environment. The required electricity for the survival and the scientific experimentation was delivered by flexible PV panels installed on the sled and commercial LIBs. The study performed in this contribution aims at the quantification of the LIBs degradation after the expedition. The results show a capacity fade of 5 % and an internal resistance increase of 30 %. Based on these results, it can be claimed that the LIBs used in the WindSled Project can successfully operate under -40°C. Moreover, these batteries can be used in upcoming expeditions, entailing an improvement from an economical and environmental point of view compared to primary batteries.
Open Access
Experimental assessment of cycling ageing of lithium-ion second-life batteries from electric vehicles
(Elsevier, 2020) Braco Sola, Elisa; San Martín Biurrun, Idoia; Berrueta Irigoyen, Alberto; Sanchis Gúrpide, Pablo; Ursúa Rubio, Alfredo; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación; Gobierno de Navarra / Nafarroako Gobernua, 0011–1411–2018–000029 GERA; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, ReBMS PJUPNA1904
The reutilization of batteries from electric vehicles allows to benefit from their remaining energy capacity and to increase their lifespan. The applications considered for the second life of these batteries are less demanding than electric vehicles regarding power and energy density. However, there is still some uncertainty regarding the technical and economic viability of these systems. In this context, the study of the ageing and lifetime of reused batteries is key to contribute to their development. This paper assesses the experimental cycle ageing of lithium-ion modules from different Nissan Leaf through accelerated cycling tests on their second life. The evolution of the internal parameters during ageing and the correlation between them are shown, including the analysis of best fitting curves. In addition, a second-life end-of-life criterion is proposed, based on capacity and internal resistance measurements during cells ageing, which can be applied to real application in order to prevent safety issues. By estimating future values from degradation trends and checking latter measurements, the ageing knee is identified. Results show that the modules operate for at least 2033 equivalent full cycles before reaching their ageing knee. This would mean more than 5 years of operation in a real second-life application, such as a photovoltaic self-consumption installation with daily cycling. Moreover, it is shown that a traditional cell characterisation based on capacity and internal resistance measurements is not enough to predict the durability of a cell during its second life.