Virtual Resistor Based Harmonic Sharing of DC Active Power Filter in Hybrid AC-DC Microgrid

DC loads and DC sources are predicted to play an important role in the DC subgrid of the hybrid AC-DC microgrid. However, the low order harmonic in DC subgrid, which are usually caused by AC subgrid, need to be addressed. To mitigate the low order harmonics on DC bus, the DC active power filter (DC APF) is considered to be a promising solution but its harmonic control scheme has to be designed considering that the DC-APFs should be distributed throughout the DC microgrid. This paper proposes a virtual resistor based control strategy which ensures the operation of single DC APF and enables the autonomous harmonic sharing. The design methods of the control parameters, including the controller parameter and the virtual resistor, are given in this paper. Both simulation results and experimental results are provided to validate the parameter design method and the effectiveness of the control method.