In this work, the converter topologies for BESS are divided into two groups: with Transformers and transformerless. This work is focused on MV applications. Thus, only three-phase topologies are addressed in the following subsections. Different control strategies can be applied to BESS [7, 33, 53]. However, most of them are based on the same principles of power control cascaded with current control, as shown in Fig. 8. When the. The viability of the installation of BESS connected to MV grids depends on the services provided and agreements with the local power system operator. The typical services provided are illustrated in. Since this work is mainly focused on the power converter topologies applied to BESSs, the following topologies were chosen to compare the aspects of a 1 MVA BESS: 1. Two-level VSC with transformer (2 L + Tx), shown in Fig. 2; 2. Three-level NPC with transformer (3 L + Tx), shown in Fig. 4; 3. MMC, shown in Fig. 7(a). 4. MMC with insulation grid.
