Research on battery SOH estimation algorithm of energy storage frequency modulation system

Abstract Based on the experimental data, the life characteristics of lithium-ion battery were analyzed. According to the experimental data statistics, the battery life changes with the number of cycles, the performance of the battery after repeated use is studied, and the changes of battery capacity, discharge efficiency, energy efficiency, internal resistance and other parameters with the battery life are explored. The mathematical model of battery life and battery usage times is established by curve fitting, and the SOH of battery is predicted according to this model. Finally, the SOH of Li ion battery is estimated according to the voltage curve fitting method. Firstly, the battery charging curves under different discharge rates and different SOH are normalized, and the charging voltage error after normalization calculation is compared. According to the existing experimental data, the SOH estimation algorithm of 92Ah lithium-ion battery is verified, the estimation accuracy of voltage curve fitting method is verified, and the estimation results of SOH are analyzed.