Distributed Large Signal Stabilization for Autonomous DC Microgrids Feeding Constant Power Loads

In this paper, a composite control method is proposed to solve the voltage instability of nonlinear systems in distributed DC microgrids (MGs). The electrical coupling of each distributed generators (DGs) and the load uncertainties are considered as a lumped disturbance in each subsystem. It can be effectively estimated by the nonlinear disturbance observer (NDO). Then, a domination controller is designed for stabilizing DC/DC boost converter feeding constant power loads (CPLs). The proposed controller can guarantee fast voltage convergence in the sense of large signal stability. Moreover, by a consensus algorithm, the internal voltage state of DGs can be dynamically updated, and the voltage deviation caused by the droop control can be compensated in secondary layer. Therefore, a distributed microgrid (MG) model is established by simulation. A variety of conditions are conducted in order to verify the effectiveness of the proposed distributed large signal stabilization algorithm.