Digital twin of a MWh-scale grid battery system for efficiency and degradation analysis

Abstract

Large-scale grid-connected lithium-ion batteries are increasingly being deployed to support renewable energy roll-out on the power grid. These battery systems consist of thousands of individual cells and various ancillary systems for monitoring and control. Although many studies have focused on the behaviour of single lithium-ion cells, the impact of system design choices and ancillary system controls on long-term degradation and efficiency of system, containing thousands of cells, has rarely been considered in detail.Here, we simulate a 1 MWh grid battery system consisting of 18900 individual cells, each represented by a separate electrochemical model, as well as the thermal management system and power electronic converters.Simulations of the impact of cell-to-cell variability, thermal effects, and degradation effects were run for up to 10000 cycles and 10 years. It is shown that electrical contact resistances and cell-to-cell variations in initial

Parallel-Connected Battery Current Imbalance Dynamics

“…oped equivalent-circuit based models enabling simulation of current dynamics in parallel-connected systems. Similar models have also recently been applied to develop SOC estimators (Zhang et al, 2020), study the influence of cellto-cell variances on the thermal design of battery packs (Fill and Birke, 2021), and simulate the aging behavior of grid battery systems (Reniers and Howey, 2022). However, despite the existing literature, fundamental analysis of such systems remain challenging due to a lack of first-principles descriptions of current-sharing behavior in parallel-connected batteries.…”