State-of-Charge Balancing Control for Optimal Cell Utilisation of a Grid-Scale Three-Phase Battery Energy Storage System Using Hybrid Modular Multilevel Converter Topology Without Redundant Cells

Cell state-of-charge (SoC) balancing within each branch of a three-phase battery energy storage system (BESS) and among three branches is crucial to overcome the inability fully utilise available capacity BESS. The proposed topology constructed with one instead take advantage its idle cells/modules (Ms) (one-third total cells/ Ms) eliminate need SoC branches. Contrary conventional topologies, Ms can serve as redundant or be dropped out BESS, thereby leading reduction in cost, control complexity, size, losses A novel strategy for BESS introduced this paper. Moreover, cell/M activation algorithm implemented minimise duration needed activate cells/Ms required generate voltage phases, an improvement operational efficiency. Based on simulation results, 3996 cells, 2664 333/222 Ms, 12 cells M lowest highest average achieved 53 min, 48 38 18 min respectively.