Hybrid Transformers with Virtual Inertia for Future Distribution Networks

Future distribution grids will require to integrate renewable energies in higher penetration levels than we are used to today in conventional power systems. To make this possible, key aspects of their operation such as reliability and robustness must been in safe levels. To accomplish the latter, two different technologies have been proposed: (a) Virtual Synchronous Machines and (b) Smart Transformers. Despite all the benefits that each one of these technologies provide, solid-state transformers have not been very successful in operating as smart transformers. Then, hybrid transformers were proposed as a more feasible solution and with the capability of providing ancillary services to the distribution grid. In this paper, a new type of hybrid transformer that incorporate features of a virtual synchronous machine is proposed. The proposed transformer is capable of emulating virtual inertia as an ancillary service, and, at the same time, providing other basic services such as reactive power injection and voltage compensation. Simulation results provide evidence of the advantages of using this type of hybrid transformers in distribution grids.