Protection of MVDC grids for the production of green hydrogen

Green hydrogen production from renewable energy sources has a big potential to reduce energy dependence on fossil fuel, contributing to the global goal set by the international community of net zero emissions by 2050. Electrolyzers are connected to grid with power stages that can be designed as active devices with high control capability and a remarkably fast operation. Nevertheless, in the present, they must overcome some challenges in order to ensure a reliable operation. This paper addresses the concept of protection of DC grids with electrolyzers fed from renewable energy sources. The topologies of the grid are discussed as well as protection features and fault clearing strategies. A new dynamic model for multi megawatt PEM electrolyzer is introduced. Finally, a case study with a PEM electrolyzer in a MVDC system is included.