Stability of a Distributed Controller for Optimal Current Sharing and Voltage Containment in DC Microgrids

In converter-dominated power grids, proportional current sharing and voltage containment within pre-specified limits are two commonly desired control objectives. In this study, we explore the stability guarantees of a promising control proposal for cyber-physical DC microgrids (MGs), specifically designed to achieve these two objectives simultaneously. Our scalable stability result relies on singular perturbation theory to prove global exponential stability by imposing a sufficient time scale separation at the border between the inner/decentralized and outer/distributed nested loops, and thus, ensuring that the system reaches the desired (optimal) steady state under appropriate tuning verifying some stability conditions. To prove the effectiveness of our method, our findings are supported by testing the control method in a time-domain simulation case study involving a low-voltage DC microgrid.