Small-Signal Stability Analysis and Optimal Parameters Design of Microgrid Clusters

The two-layer distributed control architecture, including the microgrid (MG) control layer and MG cluster (MGC) control layer, can be used for interconnecting multiple MGs to form the MGC. However, the coupling among multiple elements and the interaction between two control layers may introduce new low-damping oscillatory modes and even reduce the stability margin. Unfortunately, the detailed small-signal stability analysis and stability enhancement method of the MGC with the two-layer distributed control strategy have not been reported. To fill this gap, this paper first presents a unified small-signal dynamic model of the MGC. Subsequently, a comprehensive small-signal stability analysis based on the model is presented to analyze: 1) the mechanism of coupling/interaction among MGs and multiple control layers; 2) the participation factors of the low-damping modes; and 3) the sensitivity of the distributed control parameters. Moreover, the design of the distributed control parameters is formulated as an optimization problem, where the particle swarm optimization is employed to search for an optimal combination of parameters to enhance system stability. Finally, the stability assessment and time-domain simulation are carried out to validate the effectiveness of the proposed method.