Electrical modelling of a grid-connected battery energy storage system via EMS and BMS data
With growing popularity of grid-connected battery energy storage systems (BESSs), operators require electrical models for optimal utilisation. These models should be provided by suppliers or manufacturers based on testing methods applied to individual cells or modules in specialised laboratories. Ho...
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Elsevier
2025-06-01
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| Series: | Measurement: Energy |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S2950345025000156 |
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| author | Mirko Ledro Jan Martin Zepter Morten Paludan Mattia Marinelli |
| author_facet | Mirko Ledro Jan Martin Zepter Morten Paludan Mattia Marinelli |
| author_sort | Mirko Ledro |
| collection | DOAJ |
| description | With growing popularity of grid-connected battery energy storage systems (BESSs), operators require electrical models for optimal utilisation. These models should be provided by suppliers or manufacturers based on testing methods applied to individual cells or modules in specialised laboratories. However, operators are also interested in developing electrical models on their own. This paper explores the feasibility of modelling a grid-connected BESS without dismantling it, using only the data from its energy management system (EMS) and battery management system (BMS). The goal is to characterise a BESS directly on-site, controlling it through the available commands of its power converter system (PCS). The aim is to represent the electrical dynamics of the BESS with an equivalent Thevenin electric circuit composed of open circuit voltage, resistances, and capacitances. The overall usable capacity of the BESS and the efficiency of the PCS are also estimated. The subject of the investigation is a 300kW/652kWh Nickel-Manganese-Cobalt (NMC) Li-ion BESS composed of ten racks, each equipped with a PCS and ten battery modules. The analysis proves the feasibility of modelling the grid-connected BESS via data from EMS and BMS. An equivalent cell model is derived, with the open circuit voltage and internal impedance expressed for the entire state-of-charge range. The total resistance assumes values in the range of 1.580–2.424mΩ, whereas the total capacitance is 609.5–1,580kF. Consequently, the normalised total resistance is 3%–4%, aligned with the expectations from other NMC Li-ion cells. Finally, the energy capacity and PCS efficiency are reported as a function of the power of the PCS. The usable energy capacity per rack is approx. 59.7kWh, which is 91.5% of the rated DC energy capacity, and it is independent of the power at which the BESS is discharged. The PCS efficiency is above 94% when operating at 15% of the PCS rated power or higher, during both rectifier and inverter mode. The obtained efficiency curves differ by approx. 2% from the ones reported in the converters’ data sheet. |
| format | Article |
| id | doaj-art-6e2880b277b24c4f986cdac3e9e56e26 |
| institution | DOAJ |
| issn | 2950-3450 |
| language | English |
| publishDate | 2025-06-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Measurement: Energy |
| spelling | doaj-art-6e2880b277b24c4f986cdac3e9e56e262025-08-20T03:10:30ZengElsevierMeasurement: Energy2950-34502025-06-01610004810.1016/j.meaene.2025.100048Electrical modelling of a grid-connected battery energy storage system via EMS and BMS dataMirko Ledro0Jan Martin Zepter1Morten Paludan2Mattia Marinelli3Ørsted Wind Power A/S, HV Equipment Engineering, Nesa Allé 1, 2820 Gentofte, Denmark; Technical University of Denmark, Department of Wind and Energy Systems, Frederiksborgvej 399, 4000 Roskilde, Denmark; Corresponding author at: Technical University of Denmark, Department of Wind and Energy Systems, Frederiksborgvej 399, 4000 Roskilde, Denmark.Technical University of Denmark, Department of Wind and Energy Systems, Frederiksborgvej 399, 4000 Roskilde, DenmarkØrsted Wind Power A/S, HV Equipment Engineering, Nesa Allé 1, 2820 Gentofte, DenmarkTechnical University of Denmark, Department of Wind and Energy Systems, Frederiksborgvej 399, 4000 Roskilde, DenmarkWith growing popularity of grid-connected battery energy storage systems (BESSs), operators require electrical models for optimal utilisation. These models should be provided by suppliers or manufacturers based on testing methods applied to individual cells or modules in specialised laboratories. However, operators are also interested in developing electrical models on their own. This paper explores the feasibility of modelling a grid-connected BESS without dismantling it, using only the data from its energy management system (EMS) and battery management system (BMS). The goal is to characterise a BESS directly on-site, controlling it through the available commands of its power converter system (PCS). The aim is to represent the electrical dynamics of the BESS with an equivalent Thevenin electric circuit composed of open circuit voltage, resistances, and capacitances. The overall usable capacity of the BESS and the efficiency of the PCS are also estimated. The subject of the investigation is a 300kW/652kWh Nickel-Manganese-Cobalt (NMC) Li-ion BESS composed of ten racks, each equipped with a PCS and ten battery modules. The analysis proves the feasibility of modelling the grid-connected BESS via data from EMS and BMS. An equivalent cell model is derived, with the open circuit voltage and internal impedance expressed for the entire state-of-charge range. The total resistance assumes values in the range of 1.580–2.424mΩ, whereas the total capacitance is 609.5–1,580kF. Consequently, the normalised total resistance is 3%–4%, aligned with the expectations from other NMC Li-ion cells. Finally, the energy capacity and PCS efficiency are reported as a function of the power of the PCS. The usable energy capacity per rack is approx. 59.7kWh, which is 91.5% of the rated DC energy capacity, and it is independent of the power at which the BESS is discharged. The PCS efficiency is above 94% when operating at 15% of the PCS rated power or higher, during both rectifier and inverter mode. The obtained efficiency curves differ by approx. 2% from the ones reported in the converters’ data sheet.http://www.sciencedirect.com/science/article/pii/S2950345025000156Battery Energy Storage SystemsLithium-ion NMC cellBattery modellingPower Converter SystemBattery Management System |
| spellingShingle | Mirko Ledro Jan Martin Zepter Morten Paludan Mattia Marinelli Electrical modelling of a grid-connected battery energy storage system via EMS and BMS data Measurement: Energy Battery Energy Storage Systems Lithium-ion NMC cell Battery modelling Power Converter System Battery Management System |
| title | Electrical modelling of a grid-connected battery energy storage system via EMS and BMS data |
| title_full | Electrical modelling of a grid-connected battery energy storage system via EMS and BMS data |
| title_fullStr | Electrical modelling of a grid-connected battery energy storage system via EMS and BMS data |
| title_full_unstemmed | Electrical modelling of a grid-connected battery energy storage system via EMS and BMS data |
| title_short | Electrical modelling of a grid-connected battery energy storage system via EMS and BMS data |
| title_sort | electrical modelling of a grid connected battery energy storage system via ems and bms data |
| topic | Battery Energy Storage Systems Lithium-ion NMC cell Battery modelling Power Converter System Battery Management System |
| url | http://www.sciencedirect.com/science/article/pii/S2950345025000156 |
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