International energetic agreements define future targets to push the decarbonization process by renewables increasing. Their deep penetration in AC grids will determine limited and alternating operative modes of traditional Synchronous Generators. In such scenarios, instabilities will not intrinsically be balanced causing inertia critical conditions. In this paper a dual approach is proposed to mitigate the problem. The strategy constituted by preventive and solving actions employ DC microgrids to locally include and manage suitable Variable Energy Resources amount and to assure prompt virtual inertia provision to the AC grid. 2030 case studies for an Italian city are analyzed.
Keywords DC microgrids, energetic transition, frequency instability, inertia, RES, RoCoF, virtual inertia