Dynamic tube control for DC microgrids

This paper proposes a dynamic tube control approach for DC Microgrids (MGs) connected to constant power loads (CPL) that guarantees boundedness of the system dynamics, satisfaction of the desired operational constraints and closed-loop stability. Contrary to many approaches in the literature, we consider an explicit model of the dynamics to investigate the geometric effect of the load demand perturbations on the behaviour of the closed loop system. Combined with the use of nominal dynamics, i.e. dynamics parametrized by a constant load demand, this allows us to formulate, for the first time, necessary conditions for the existence of a tube around a nominal solution that bounds all possible uncertain trajectories stemming from perturbations of the load demand. Furthermore, we show that the computation of the tube follows a fully decentralized approach and its size is dependent on the nominal dynamics, which we use in the regulation of the nominal solution to reduce the conservativeness of the controller. The effectiveness of the proposed control architecture is illustrated in a simulated scenario.