Droop-controlled single phase AC micrigrid using SOGI-PLL

Abstract

A microgrid (MG) is defined as a low or medium voltage distribution network that is also connected to a number of distributed generation sources, energy storage elements, and con- trollable loads. A MG can operate both in grid-tied mode, when its bus is connected to the main grid, or in islanded more, when it’s disconnected. MG control strategy is considerably different than that of the traditional grid. A hierarchi- cal control architecture consisting of primary, secondary, and tertiary control is adopted to regulate voltage and frequency and ensure a stable and reliable network. In order to offer a good power quality for end users in islanded microgrids, the power sharing between distributed generators (DGs) is the first challenge that must be dealt with. In this report, a droop control method based primary control for two parallel single-phase VSIs forming an islanded microgrid is presented. The controller aims to ensure optimal power sharing between different DGs using mod- ified droop-control technique and introducing SOGI-PLL for parameter estimation and DC- offset rejection, during islanded operation.