arXiv:2511.10401v3 Announce Type: replace Abstract: As modern power systems continue to evolve into multi-agent, converter-dominated systems that demand reliable, stable, and optimal control architectures within an expandable framework, this paper investigates scalable stability guarantees of a promising nonlinear communication-reliant control framework for DC microgrids. Particularly, relying on nested control loops, inner decentralized (primary) and outer distributed (secondary), the control configurations are designed to simultaneously achieve proportional current sharing and voltage containment within pre-specified limits, at the converged steady state. By enforcing sufficient time-scale separation at the border between the control loops, the system admits a singular perturbation formulation, allowing global exponential stability (G.E.S.) to be established via Lyapunov arguments. Although the theoretical G.E.S. certificate is structurally scalable, the stability guarantees depend on a sufficiently large permanent leakage, introduced in the primary controller. Thus, this paper emphasizes the importance of appropriate practical tuning guidelines for establishing suitable system configurations under which the DC microgrid is practically scalable and its equilibrium is G.E.S.. The effectiveness of the proposed method is validated through case studies on a low-voltage DC microgrid under load variations and topological changes, followed by a small-signal stability analysis