A grid-connected micro-grid is a mode that interconnects with the external grid and exchanges electricity. When the external grid fails, the micro-grid can quickly switch to the off-grid mode to ensure the stability of power supply.
The grid-connected micro-grid can convert DC current produced by wind turbines and PVs into AC current with the same voltage amplitude, frequency, and phase as those of the main grid, and interconnect with the main grid. The flexibility of this power generation system lies in that when renewable energy is abundant, the micro-grid system supplies power to the AC load while sending surplus electricity to the main grid to obtain profits. When renewable energy is insufficient, electricity can be obtained from the main grid to power the load.