A Novel Droop-Based Average Voltage Sharing Control Strategy for DC Microgrids

Abstract

This paper introduced a decentralized voltage control strategy for dc microgrids that is based on the droop method. The proposed distributed secondary voltage control utilizes an average voltage sharing scheme to compensate the voltage deviation caused by the droop control. Through nonexplicit communication, the proposed control strategy can perform precise terminal voltage regulation and enhance the system reliability against system failures. The distributed voltage compensators that resemble a centralized secondary voltage controller are implemented with the bi-proper anti-wind-up design method to solve the integration issues that necessarily lead to the saturation of the controller output efforts. The proposed concept of pilot bus voltage regulation shows the possibility of managing the terminal voltage without centralized structure. Moreover, the network dynamics are illustrated with a focus on cable resonance mode based on the eigenvalue analysis and small-signal modeling; analytical explanations with the development of equivalent circuits give a clear picture regarding how the controller parameters and droop gains affect the system damping performance. The proposed derivative droop control has been demonstrated to damp the oscillation and to improve the system stability during transients. Finally, the effectiveness and feasibility of the proposed control strategy are validated by both simulation and experimental evaluation.