Robust Voltage Stabilization Controller for Uncertain DC Microgrids

In this paper, we propose a new voltage stabilizing controller for a DC microgrid. The microgrid under consideration is composed of Distributed Generation Units (DGUs), power lines, and local loads. The parameters of DGUs and power lines are assumed to be unknown but belong to known bounded sets and the loads, which are modeled by constant current loads, are assumed to be unknown. The proposed controller adopts the disturbance observer based controller which is known to be robust against parameter uncertainties and external disturbances. One benefit of this controller is to make the real uncertain closed-loop system behave like a nominal model, and in this work this nominal model is a desired dynamics relating the voltage reference and output voltages of DGUs. A rigorous stability proof is provided and the results are validated through numerical simulations.