Adaptive droop control for current sharing and bus voltage stability in DC microgrids

摘要

In order to achieve current sharing and bus voltage stability in distributed resources (DR) if a conventional drop control is used, a trade-off must always be considered. When the bus voltage is restored to the nominal level, the desired current sharing is sacrificed. This paper proposes an adaptive and robust droop controller to achieve the goals of current sharing and bus voltage stability. This droop controller is a model reference adaptive control (MRAC) in which the second-order reference transfer function is derived from the transfer function showing the dynamical behavior of DRs. In the proposed adaptive droop controller, the Lyapunov stability theory is used to extract the adaption law. The suggested adaptive droop controller is implemented in the secondary control layer and modifies the droop resistance adaptively. The effectiveness of the proposed method is validated by the experimental and simulation results.