Power Sharing Algorithm for Voltage Regulation in Islanded DC Multi-Microgrid System

Direct Current(DC) systems are more efficient than alternating current(AC) systems because of fewer power conversion steps. Furthermore, due to increasing DC-based distributed energy resources(DERs) and loads, studies and applications for DC microgrid(MG) are increasing. Since there is no frequency and reactive power in the DC MG, only voltage control is required in terms of stability. If voltage stability is not taken into consideration, unnecessary power losses increase, and in severe cases, blackout may occur. Hence, voltage control should be required using active power. In this paper, power sharing algorithm for voltage stability in islanded DC multimicrogrid(MMG) system is proposed. The DERs of each single DC MG primarily perform droop control for voltage regulation. If the voltage level cannot be recovered even though droop control is applied, power sharing is performed from neighboring MGs. The amount of power sharing required and the available amount of power sharing are calculated based on droop curve. To verify proposed algorithm, islanded DC multi-MG consisting of two single DC MGs are designed. The simulation results prove the efficiencies of the proposed method.