Virtual active power filter: a notable feature for hybrid ac/dc microgrids

The coexistence of ac and dc subgrids is going to be inevitable in microgrids (MGs). This study introduces a virtual active power filter (APF) to improve the power quality of a grid connected hybrid ac/dc MG. In this approach, the dc subgrid and the IC are integrated to form a virtual APF. Thus, an enhanced control method for IC is proposed that improves the performance of hybrid ac/dc MG under non-linear load conditions considering power quality of both ac and dc subgrids. The proposed control ensures acceptable power quality for both inverter-based and rectifier-based power transfer between ac and dc subgrids. Furthermore, the IC provides stable dc bus voltage for the dc subgrid and exchange power between the ac and dc buses, properly. A hybrid ac/dc MG is simulated using PSCAD/EMTDC software and various set of simulation studies is presented to validate the effectiveness and advantages of the proposed control method. Furthermore, experimental results are provided to validate the mentioned properties. These features have not been previously discussed in the literature for virtual APF in hybrid ac/dc MGs, where existing APFs are mostly presented for unidirectional power flow applications such as distributed generators.