Hierarchical control strategy for inverter in micro-grid based on MAS

This paper proposes a two-level hierarchical control strategy for inverter to ensure the voltage stability of micro-grid based on MAS. The lower level decentralized control adopts an improved algorithm of closed loops control framework using fractional order PID; the upper coordinated control is designed by using H∞ robust control method. The voltage stability risk index is formulated to measure the voltage stability. When micro-grid suffers slight disturbances, decentralized control is only used to maintain the voltage stability of the system. When severe disturbances arise, according to the voltage stability risk index, the coordinated controller operates together with the decentralized controller to maintain the voltage stability of the system. Finally, the proposed control strategy is tested through the simulation examples.