I am trying to review the structures of Islanded microgrid, its economic analysis, and improving its efficiency and stability. so I need to know the best structure that is existing now.
Perhaps you should read the paper included in Jakopo2017.pdf (murdoch.edu.au) entitled "CONTROL OF AN ISLANDED MICROGRID" or the paper included in Article Hierarchical control structure in microgrids with distribute...
You must read this article in order to have a better grasp of the construction of an islanded microgrid. https://terraverde.energy/best-practices-for-microgrid-project-feasibility-assessments/
Chapter Design of an Energy Management System for Secure Integration...