Droop Control Based Strategy for Photovoltaic Sources in an Islanded Microgrid

Abstract

To integrate more renewable energy (RE) into the power grid, an effective control strategy for photovoltaic (PV) sources in an islanded microgrid is investigated. A power sharing scheme is designed to give PV sources the priority of power supply. Based on the scheme, adjusted droop control strategy is employed for voltage source inverters (VSI). Considering PV power characteristics, a DC/DC converter controller is also designed for PV panels. There are two operating modes of PV sources: maximum power point tracking (MPPT) mode and power curtailment (PC) mode. MPPT mode is supported by MPPT technique combining with a frequency increment on the VSI droop controller. The traditional droop controller and DC bus voltage tracking loop support PC mode. Stability analysis is conducted. Simulation results show the control strategy can share power demand effectively among different kinds of power sources even under varying weather conditions.