Behavior of transformers interconnecting microgrid and prosumers

The recent evolution in electricity distribution systems has led to the development of new intelligent structures, better known as Smart Grids, Microgrids and Prosumers. The consequent advantages regard mainly both economy aspects and environmental safeguard. In a microgrid, producers and consumers can exchange energy in peer-to-peer way. Normally, the microgrid is connected to a Smart Grid in a single common point. In this case, the microgrid can be easily disconnected from the external grid and continue to work in 'island' mode. In this condition, local production must be equal to the energy consumed, unless local storage systems are installed on site. In case of a bidirectional management, the source may change in load and vice versa. In this situation, a traditional transformer may work in an overload condition and the protection system may trip, provoking, in the worst conditions, a blackout. In order to avoid this condition, some solutions are here proposed and commented.