In-situ Parameter Identification of Cells in Grid-Connected Batteries

Grid-connected batteries typically consist of 10’s of thousands of cells, where the Battery Management System (BMS) reports cell level voltage data which is normally used to protect the system against voltage limit violations. The work presented in this paper proposes a methodology to use this data to identify key model parameters (capacity and impedance) of the cells within the system. It is discussed how the method is reached, before experimentally demonstrating it using two battery systems to test the procedure at different scales, with comparison to individual cell tests. Results validate the theory, with data from a large number of cells measured in-situ (1584) being presented.