A passivity-inspired design of power-voltage droop controllers for DC microgrids with electrical network dynamics

We propose a design procedure for a power-voltage droop controller in structure-preserving DC microgrids under explicit consideration of the electrical network dynamics. Differently from most related literature, the system's controlled output is taken as the power-not the current-injection at each generation unit, yielding a nonlinear closed-loop system. This makes the output regulation problem non-trivial, yet far more appealing in a practical setting than the usual linear current-voltage droop control. Our approach is inspired by passivity-based control design in the sense that we exploit the natural port-Hamiltonian representation of the system dynamics and its associated shifted Hamiltonian to derive a control law together with sufficient conditions on the tuning gains that guarantee global asymptotic stability. The analysis is illustrated via detailed simulations, where accurate power sharing is manifested among the distributed generation units in the presence of load variations.