I. Introduction
The concept of microgrid can be expressed as an energy source and grid management technology that emerged two decades ago. It can be independently supervised and provide electrical energy with distributed generation. A microgrid system, consisting of a part of the main grid and industrial or commercial consumer applications, can operate in either off-grid or grid-connected mode [1]. Microgrids can be connected to other grids, such as a large-scale utility grid, via an interface unit such as a power electronic converter. The inclusion of power electronic converters in the system affects the power quality of the system it is connected to and makes new control regulations mandatory. In short, microgrids are networks that include a load group fed by one or more distributed energy units and a part of the medium-voltage (MV) or low-voltage (LV) distribution system [1]. For this reason, microgrids can be defined also as local power systems of different size that operate in a distribution system [2]. Potential benefits of microgrids as compared to conventional electric power grids are reduction of the environmental pollution, reduction of the new power plant investments, increased operational reliability, resilience and energy stability and provision for ride-through capability [3], [4].