An novel hierarchical control of microgrid composed of multi-droop controlled distributed power resources

To improve power sharing and power quality in ac microgrid composed of distributed power resources based on droop controlled voltage source converter, a novel hierarchical control of ac micro-grid according to different time scales is proposed in this paper. In short time scale, larger droop gains is adopted to improve power sharing. In larger time scale, the no load frequency and voltage set points of droop characteristics are adjusted, improving the voltage and frequency quality. The proposed hierarchical control can both limit the reactive power sharing errors and improve the power quality, which can be applied in complex microgrid configurations. Finally, the performance of the proposed control strategy is verified by digital time-domain simulation in PSCAD/EMTDC software.