Fully decentralized robust backstepping voltage control of photovoltaic systems for DC islanded microgrids based on disturbance observer method

Abstract In this paper, a new backstepping-based nonlinear technique for control of photovoltaic systems in DC islanded microgrids (MGs) is proposed. In contrast to most existing droop/non-droop control strategies that require an exact model of the system including line impedances, loads, other distributed generation units (DGUs) parameters, and even the MG configuration, the proposed method is taking dynamics and uncertainties into account using a designed disturbance observer. Moreover, the proposed method rapidly reaches the reference values and exhibits a more accurate robust performance using local quantities measurement, irrespective of parametric uncertainties, unmodeled dynamics, unknown loads, disturbances, and the number/structure of DGs within the MG. Finally, a low-voltage DC MG is built where the robust performance of the proposed method for different operating conditions including load variation, tracking capability, nonlinear loads, and plug-play of DGs is verified.