Distributed Secondary Control of Multibus DC Microgrids Through the Averaging of Virtual Voltage Drop

A fundamental control objective of dc microgrids is to achieve simultaneous current sharing and voltage restoration. This has been accomplished in single-bus dc microgrids through the concept of virtual voltage drop (VVD). A natural question arises: can this concept be effectively applied to controller design for multibus dc microgrids? This article addresses this question by presenting a novel distributed secondary control scheme for multibus dc microgrids based on the dynamic averaging of VVDs. This control scheme exhibits two distinct features. 1) It does not rely on the dc bus voltage as a feedback signal, thereby simplifying implementation and distinguishing itself from existing approaches; and 2) the proposed controller only requires the transmission of the estimated average value of VVDs among neighboring DGs, reducing the number of transmitted signals and thus lowering bandwidth requirements. Simulation and physical experimental studies are conducted to validate the proposed control scheme.