A hierarchical control strategy of micro-grid based on grid-friendly distributed generation technology

To solve the operation and control problems of islanded micro-grid better, this paper proposed a novel hierarchical control strategy according to different time scales. In the primary control, proposed a novel grid-friendly DG topology structure, the power of the islanded system is automatically shared between micro-sources. In the secondary control, the no-load frequency and voltage set points of droop characteristics are adjusted according to different output power range of the DG, which can effectively improve the power quality and stability of the islanded system. In the tertiary control, the slop of droop characteristics are adjusted according to power forecasting and state of charge (SOC) of storage system, implementing economic operation of the system. Finally, to verify the validity of the proposed theory, a distributed renewable energy generation digital/physical hybrid simulation platform based on NI-PXI is designed and implemented. Experimental results demonstrate the effectiveness of the control strategy.