Design of a dynamic phasors-based droop controller for PV-based islanded microgrids

Abstract

This paper presents a novel autonomous droop-based power sharing scheme for parallel inverter-connected photovoltaic (PV)–based islanded microgrids, in which both resistive and inductive distribution lines are taken into account. The proposed control strategy contains a compensating approach with a view to adding a power offset to the real power owing to the fact of balancing the inverter output power during the variation in the output of solar energy. A derivative term is also included in the designed controller, which damps the oscillatory modes of the controller so that better dynamic performance is ensured. Proportional power sharing among inverter-interfaced PV generators is maintained by including a novel voltage control law in the control algorithm, in which the reference values of the voltage sources are kept the same. The stable range of droop-based control parameters are determined by the extended dynamic phasors model analysis. Finally, the performance of the designed controller is verified on a PV-based islanded test microgrid, and superior dynamic performance is obtained compared with the generalized droop-based controller.