I. Introduction
Micro-grids are the building blocks of Smart-grids. They are essentially an active low voltage (LV) distribution system consisting of distributed energy resources (DERs), storage devices and flexible loads. The basic objectives of micro-grids being improved reliability, promotion of high penetration of renewable energy sources, dynamic islanding and improved generation efficiency. Micro-grids have two operation modes, the normal (grid connected) state and the emergency (islanded) state and differ from passive grids penetrated by micro-sources in their ability to manage and coordinate available resources [1]. The DERs used in micro-grids are mainly renewable for environmental purposes and are selected in such a way as to maximize the use of the locally available renewable source in the distribution network.