For determining the topology of a grid section of an AC power grid, the grid section comprising a grid connection point, at least one branch branching off from the grid connection point and including a plurality of energy consumption and/or energy generation units, and at least one measurement point in the at least one branch, dependencies of variations of a grid voltage measured at the at least one measurement point based on variations of connection power values of at least some individual ones of the energy consumption and/or energy generation units are determined.