Due to the growing number of PV and wind power plants, stable grid operation in Germany is currently achieved by so-called »congestion management«. Its goal is to minimize the throttling of electricity fed in from renewable sources and to make use of flexibility in the electricity grid. The costs for the national congestion management currently exceed 1.4 thousand million euros and are paid by the final customers via their grid service charges. The transmission grid operators are responsible for grid stability and the integration of the distribution grids into the congestion management via the so-called »coordination cascade«. Therefore, determining the flexibility potential of the subordinate grids plays a central role, but the conventional feedback from distribution grid operators no longer meets the increasingly complex requirements.