Modeling and simulation of a microgrid protection system with central protection unit

In order to handle the impact of Distributed Generators (DGs) and make conventional grids suitable for large scale deployments of DGs, Microgrids are proposed. However, the introduction of microgrids brings some challenges. Protection of a microgrid and its entities is one of them. Due to the existence of generators at all levels of the distribution system and two distinct operating modes, i.e. Grid Connected and Islanded modes, the fault currents in a system vary substantially. Consequently, the traditional fixed current relay protection schemes need to be improved. This paper presents the conceptual design, modeling and simulation works of a microgrid protection system which utilizes extensive communication to monitor the microgrid and update relay fault currents according to the variations in the system. The proposed system is designed so that it can respond to dynamic changes in the system such as connection/disconnection of DGs. The modeling has been performed in MATLAB and simulation works are carried out to verify the operation of the proposed system.