Storage system control for fault protections of single phase loads in inverter-dominated grids

Nowadays micro-grids are taking a important role in power systems design, control and management. One of the key features of actual micro-grids is the predominant presence of power electronic converters, which limit the inertia of the system and the ability to provide high short circuit currents. In fact, power electronic converters limit the fault current to approximately 1.5 times their rated current. This could lead to a failure of traditional protections, based on high current detection. Different solutions to this problem have been proposed in literature. Among others, the exploitation of a storage system to increase the short circuit current and, thus, reach the pick-up value of traditional relays has been investigated. This paper deals with the results of tests on such an arrangement, carried out on a real micro-grid test facility at Politecnico di Milano premises.