Decentralized Economic Operation Control for Hybrid AC/DC Microgrid

A hybrid ac/dc microgrid, which consists of alternating current (ac) subgrid(s) and direct current (dc) subgrid(s), can efficiently integrate ac and dc loads, distributed generators (DGs) with minimum conversion stages. The ac and dc subgrids are connected by the bidirectional power converter (BPC) to realize power interaction between them. This paper proposes a decentralized economic operation control for the hybrid ac/dc microgrid, which aims to realize economic power sharing among all DGs and economic power interaction between subgrids. For the DGs, the nonlinear droop controls based on ac frequency-incremental cost and dc voltage-incremental cost are proposed, which can equalize DGs' incremental costs autonomously, and hence decrease the subgrids' generation costs with the equal incremental cost principle. For the BPC, the economic power interaction control is proposed to optimize the power interaction between the two subgrids and further decrease the total generation cost (TGC). In addition, the economic operation is categorized into different modes according to the load conditions. The hybrid microgrid with nonlinear incremental cost droops is modeled, and the overall stability analysis is conducted to ensure stable operation in all load conditions and modes. The performance of the proposed control is verified by the real-time hardware-in-loop (HIL) test.