Improved control strategy of interlinking converters with synchronous generator characteristic in islanded hybrid AC/DC microgrid

In this paper, an improved control strategy of interlinking converters for hybrid AC/DC microgrid operated in islanding mode is proposed, which applies synchronous generator model to the converters. This enhanced scheme adopts direct frequency control method to realize active power sharing and improves the transient frequency stability by using synchronverter technology. Unlike existing droop control methods of interlinking converters that mostly just focus on power sharing, this scheme can not only maintain proportional power distributed between DC and AC subgrid, but also regulate the AC subgrid voltage directly to improve its poor frequency stability during ACside loading transitions in autonomous operation. It's noteworthy that this scheme can also keep the AC-side loads working uninterruptedly during AC subgrid faults events by using voltage-controlled method. Moreover, any additional energy storage or inverters are not required to assist interlinking converters for microgrid frequency regulation. The effectiveness of this modified control method is verified by offline time-domain simulation and real-time experiment in MATLAB/Simulink and OPAL-RT digital platform respectively.