An Estimation Method for Battery Capacity using Deviation of SOC on Battery Energy Storage System during Operation

Performance degradation of batteries needs to be measured in order to carry out their suitable maintenance for long-term use. The paper proposes an estimation method for battery capacity as a typical index of battery degradation. The proposed method is based on the fundamental relationship between charge/discharge currents and SOC (state of charge), and uses operation data of the battery which is in service. Unlike conventional methods, it does not require specific patterns of operation for the estimation, so that the availability of the battery system is maintained. The verification results using operation data from an actual battery system show that estimation errors are less than 5[%].