Distributed Autonomous Control for Global Economic Operation of AC/DC Microgrid Clusters Interconnected by Flexible DC Distribution Network

This paper presents a distributed autonomous control strategy for AC/DC microgrid clusters interconnected by the flexible DC distribution network to simultaneously achieve the global economic operation and frequency/voltage control of the system while complying with the power limits of DGs and interlinking converters. First, the optimal control problem for the system is formulated and the Karush-Kuhn-Tucker (KKT) condition of the system global economic dispatch is obtained. Then, the three-layer control framework including the distributed generator layer (DG-layer), microgrid layer (MG-layer), and microgrid cluster layer (MGC-layer) is established. In the MG-layer, the distributed frequency/voltage and economic dispatch controllers are designed for each ACMG and DCMG. In the MGC-layer, a distributed peer-to-peer control method is provided to realize the coordinated control among interlinking converters while controlling the voltage of DC distribution network. The coordination method between MG-layer and MGC-layer is also designed. Finally, time-domain simulation and experiments are carried out to validate the effectiveness of the proposed methods.