Power Electronics is expected to become a major component in the field of the global electric power management, as it is already today within most of electric power applications like variable speed drives or other conventional user applications. From the end of the sixties, up to the beginning of the 21st century, high power electronic converters have been used more and more for many usages connected to the grid, from the reactive power compensation to the long distance transmission lines. More recent examples have shown a large potential of new flexible management systems like UPFC’s, or other Flexible AC Transmission Systems. The paper presents the actual state of the art of the use of large power electronic converters within the grid interconnection, and for different fast growing new techniques of decentralized generation and within the context of the integration of renewable energy sources. Dedicated DC grids for energy collection from multiple medium size generators or for electric energy distribution are intended to play a major role in the future, as other new flexible structures based on the use of MF transformations.