Voltage Control and Load Sharing in a DC Islanded Microgrid based on Disturbance Observer

Increasing DC loads along with DC nature of Distributed Energy Resources (DERs) raised interest to DC microgrids. Conventional droop/non-droop power sharing in microgrids suffers from load dependent voltage deviation, slow transient response, and requires the parameters of the loads, system and DERs connection status. In this paper, a new nonlinear decentralized back-stepping control strategy for voltage control and load sharing of DC islanded microgrids is proposed. The proposed method is robust against to the load variations and uncertainty in microgrid parameters and has excellent dynamic and steady state performance under different operating conditions. The local controller regulates the terminal voltage of dc-dc converter regarding to the local quantities without needs to additional data of other system components. For simplicity, the proposed method is simulated with PSIM software on a DC microgrid with two DGs. Different scenarios are studied to present the proposed method performance under different operating conditions. The results indicate the capability of the proposed method for voltage control and load sharing in DC microgrids.