Need for grid-forming units in the distribution grid and their impact on protection, automation and control

To achieve a carbon-neutral but still stable power system, the substitution of grid-forming functionalities from big, centralized power plants with directly coupled synchronous generators by decentralized inverter-based generation or storage systems is necessary for inverter-dominated networks. In this context, the requirements for system protection functionalities and the objectives of the grid and plant protection of the German distribution grid are compared. With increasing inverter-based generation and the development of grid-forming capabilities during the next years, the contribution to voltage support and inertia from the distribution grids might also increase. The in parts contradictory timelines and interests of network protection in the distribution grids and of the grid-forming functionalities for the system stability have to be considered from distribution and transmission system operators for future concepts. Potential conflicts and challenges are identified for further discussions, developments and detailed investigations.