Coordinated optimal control and dispatching operation of grid-connected AC/DC hybrid microgrid group

For an AC-DC hybrid microgrid group connected to multi-node system, a management and control integration strategy with the cooperation of upper energy dispatching and lower electrical control is proposed. In the lower AC/DC hybrid microgrid group, a virtual synchronous generator-error tracking controller(VSG-ETC) strategy is proposed for AC/DC bidirectional converters, which can maintain the balance of power at both AC and DC sides and suppress the fluctuation of frequency and voltage without normalization processing; A Q-V control method based on virtual phase angle is proposed for the DC microgrid, which realizes proportional current sharing and bus voltage regulation. When the hybrid microgrid group is overloaded with large load, the optimal dispatching of the upper distribution network will be triggered. The upper layer redistributes the power flow according to the updated power demand, and the communication network transmits the new reference value to the lower layer, thus realizing the linkage between dispatching and control. The AC/DC hybrid microgrid group connected to the low-voltage distribution network is used as a simulation example to verify the strategy and method. The results show that when the load changes, the lower control method achieves the dynamic balance of AC and DC power, suppresses the fluctuations of voltage and frequency, and achieves better dynamic performance; Under the impact of overload load, the coordination and integration strategy of dispatching and control ensures the safety of the system and improves the stability and anti-interference ability of the system .