Study on the modeling and simulation of a grid-connected battery energy storage system based on cascaded h-bridge converter

Abstract

Battery energy storage system (BESS) is evolving to be a major part of the modern power systems due to high controllability and simple implementation. In this paper, the general structure of the BESS and its components are reviewed focusing mainly on the battery storage unit in hierarchal order from cell to pack in terms of modeling, design, and wiring. The effect of the weakest cell and cell-to-cell variations are also mentioned in perspective of the battery charging and their effects on the wiring topology. Moreover, cascaded h-bridge (CHB) converter topology is also discussed and compared with other power electronic interfaces in terms of storage capacity and switching elements. It is shown that CHB converter topology can be utilized in BESS to minimize the number of series connected batteries. Finally, a 1 MWh 34.5 kV grid-connected BESS based on CHB converter topology is designed and simulated to test the capabilities of the BESS to supply active power to the power grid under closed-loop control.