Predictive direct power control of multilevel direct current link converter for grid connected battery energy storage systems.

This paper proposes the adoption of a multilevel dc link converter for a grid connected battery energy storage system in low voltage applications. The multilevel dc link converter is the simple upgrade of a typical two level voltage source converter with the incorporation of some cascaded modular chopper cells which constitute a switched-battery circuit. With the additional chopper cells, more candidates of voltage vectors are available for switching vector selection in power control. Compared to two level voltage source converter using a look-up-table direct power control or finite control set model predictive direct power control, the multilevel dc link converter which employed the latter power control tracks the reference power with much lower power ripple, as well as results in much lower total harmonic distortion in grid current. Therefore, the power quality can be improved significantly. Simulation results are presented to verify that a 3 level dc link converter is more effective than a two level voltage source converter for the grid-connected battery energy storage systems in both generating mode and charging mode. [ABSTRACT FROM AUTHOR]