Battery Cell Fault Identification Method for Energy Storage System and Energy Storage System

A battery cell fault identification method for an energy storage system, comprising:

• setting an upper threshold for a cell voltage deviation;
• acquiring a cell voltage V_n_i of each battery cell, wherein n denotes a number of battery modules, and i denotes an index of battery cells within each of the battery modules;
• performing a horizontal comparison on the battery cells to acquire a deviation ΔV_n_i of the cell voltage of each of battery cells within a same battery module relative to an average cell voltage of the battery cells within the same battery module;
• and
• performing a vertical comparison on the battery cells, calculating a difference between deviations of battery cells with a same index within each of the battery modules and a median value of the deviations of the battery cells with a same index within the each of the battery modules, and if the difference exceeds the upper threshold for the cell voltage deviation, determining that a battery cell corresponding to the difference is faulty.