State of the Art of Hybrid AC-DC Medium Voltage Grids

In the last decades, DC technologies have become more accessible through the development of the power electronics sector. Most of the existing applications are in the high voltage range for transferring power over long distances. As a natural succession of events, DC technologies are trickling down into the medium and low voltage grids because of their potential contributions for grid controllability, integration of converter-based renewable energy sources, higher power density and their improved compatibility with underground cables. The importance of the emerging hybrid MVAC-MVDC grids is represented by the ability to profit from the advantages of both technologies. This paper presents a review of the scientific literature available regarding the state of the art of hybrid medium voltage AC (MVAC) and DC (MVDC) grids by focusing on the latest available technologies and equipment and their challenges, the necessity of hybrid MVAC-MVDC grids, current and future applications.