Adaptive Droop Control of Coupled Microgrids for Enhanced Power Sharing and Small-Signal Stability

With the increasing integration of distributed energy resources in the distribution system, coupled microgrids can enhance the system reliability and stability and help accommodate higher penetration of renewable sources. This paper proposes an operating condition based adaptive control framework for coupled microgrid systems to achieve effective load sharing and improved system wide small signal stability. The proposed framework consists of three levels of hierarchical control performed at different time scales. Device level control which tracks a provided voltage and angle reference set-point is used at the primary level. At the secondary level, the power exchange between the microgrids is regulated by an adaptive gain based droop control which adapts with the system operating condition and considers the coupled relation between |V|, δ and P, Q. At the tertiary level, an AC power flow based supervisory control updates the active and reactive power flow reference setpoints to control the power transfer between the coupled microgrids. Simulation results on a coupled microgrid system based on the modified IEEE 123-node test feeder demonstrate the effectiveness of the proposed adaptive control framework at the secondary level for improved stability of coupled microgrids.