Large scaled cascaded battery energy storage system with charge/discharge balancing

In order to connect large scaled energy storage to high voltage bus in urban distribution network,a battery energy storage system topology for the large scaled and multi-modular systems is proposed,which combines the cascaded converter topology with the interleaved bi-directional DC / DC conversion technology.The designed system can directly connect to 10 kV bus and above without transformer and achieve better output harmonics performance under lower switching frequency.The DC voltage of each serial module can be boosted based on the battery output voltage and the parallel connection of battery groups is allowed.A simulation system based on delta configuration is built with three-level charge / discharge balancing control.The control effectiveness is verified by EMTDC simulative results.