Droop Control for PV Sources in DC Microgrids

Abstract

Direct current (dc) microgrids are highly compatible with photovoltaic (PV) sources due to their dc nature. However, as PV penetration increases, conventional current-source control configurations tracking the maximum power point may encounter the overvoltage problem, among others. This paper presents a $V$ – ${d}p/{d}v$ droop control strategy, which enables the PV sources to work in the maximum power point tracking (MPPT) mode, as well as behave as voltage sources to participate in dc-bus voltage regulating. The $V$ – ${d}p/{d}v$ droop method unifies MPPT and dc-bus voltage regulating in the sense of using the same control configuration, which avoids the controller reconfiguration during the PV mode switching. Further, the coordinated operation of multiple PV sources in the dc microgrid, including autonomous mode switching and primarily power sharing, is achieved by the proposed control strategy without any communication. Hardware-in-loop tests are presented to demonstrate the effectiveness of the proposed control scheme.