Voltage reference varying-based adaptive IDA-PBC design and stability analysis for DC microgrids

Abstract

Constant Power Loads (CPLs), which are widely present in DC microgrids, exhibit negative impedance characteristics, reducing the system’s stability margin and posing significant challenges to grid control and stability. To address this issue, we propose an Interconnection and Damping Assignment Passivity-Based Control (IDA-PBC) strategy. By reshaping system energy and injecting damping, the proposed controller ensures the attainment of the desired equilibrium point and dynamic performance, thereby enhancing the microgrid’s stability margin. Unlike conventional IDA-PBC methods, which typically modify the interconnection matrix by introducing a parameter $K$ to obtain a unique control law solution, our approach achieves a unique solution by redefining the reference voltage. This strategy effectively eliminates singularity issues at the equilibrium point. Furthermore, we conduct a comprehensive stability analysis of the proposed IDA-PBC, derive the system’s stability margin, and design a trajectory-tracking controller to validate its advantages in improving stability. Finally, numerical simulations and experiments are performed to verify both the effectiveness of the proposed controller and the accuracy of the stability analysis.