Distributed Secondary Control of Direct Current Microgrids for Optimal Power Sharing and Voltage Restoration

Power sharing and voltage restoration are critical in direct current (dc) microgrids. While conventional secondary control methods address these issues, they often limit power sharing to a fixed ratio. However, the optimal power sharing ratio, e.g., the one that minimizes generation cost, can vary with time. To address this issue, a new distributed secondary control scheme is proposed in this article to achieve optimal real-time power sharing and voltage restoration simultaneously. A key component of the scheme is to design an adaptive droop gain, which enables the real-time optimal allocation of power to minimize total generation cost, even amid load fluctuations. Additionally, the concept of virtual voltage drop, derived from the adaptive droop gain and line resistance, is integrated into the scheme to achieve voltage restoration. Case studies are conducted to demonstrate the effectiveness of the proposed scheme.