General battery modeling and simulation using non-linear open circuit voltage in power system analysis

Abstract

Battery applications are increasing day by day from a single cell to MWh range in electric vehicles, electric traction, PV systems, grid support, etc. Considering energy density and price, correctly apply, size and analyze batteries for these systems remains a major challenge and requires sufficient battery characteristics. Most battery manufacturers provide limited sets of battery charging & discharging characteristic data, which are not adequate for battery simulation in a system that different types of loads are connected, or different charging scenarios are applied. Therefore, accurate & comprehensive battery modeling is needed. A non-linear open circuit voltage (Voc) model is derived with respect to state of charge (SOC) from battery charge-discharge characteristic curves. For hysteresis, two sets of non-linear Voc data are maintained for charging and discharging. This model is general for major types of batteries and results are acceptable as simulation error is minimal.