Grid-connected Control Strategy for Bidirectional A C-DC Interlinking Converter in AC-DC Hybrid Microgrid

When the DC microgrid is interconnected with the AC microgrid, the output voltage of the Bidirectional AC/DC Interlinking Converter (BIC) connected to the AC and DC subnets should have the same amplitude, frequency and phase as the AC microgrid voltage. Therefore, fast and accurate detection of AC voltage frequency, phase and amplitude is the premise of grid-connected synchronization. For this reason, a synchronous grid-connecting method is proposed. Firstly, the principle of the bidirectional AC/DC converter is introduced, and the problem of impulse current in the process of grid connection is analyzed. At the same time, the power transmission relationship of the BIC is analyzed, and the control strategy suitable for the interconnection between AC-DC microgrid in island mode is proposed. Finally, the proposed control algorithm is verified by the simulation on the Matlab/Simulink platform.