METHOD, DEVICE, AND SYSTEM FOR CONTROLLED ENERGIZING OF A TRANSFORMER IN A POWER GRID

The invention relates to a method for energizing a transformer (11) in a three-phase power grid (10), wherein the phases (L1, L2, L3) of the transformer (11) are switched-on asynchronously in a manner to reduce inrush-currents flowing in the power grid (10).To avoid high inrush currents with any possible transformer configuration, the following steps are performed:- determining a remanent magnetic flux in the respective phases (L1, L2, L3) of the transformer (11);- determining a sequence for switching-on the respective phases of the transformer (11), wherein the sequence depends on mechanical construction properties of the transformer (11) ;- calculating a phase angle of an electric voltage at which at least one phase is to be switched-on first;- calculating, for the remaining phases, a respective time delay after switching-on of the at least one first phase; and- generating switching signals to switch-on the at least one first phase at the determined phase angle of the electric voltage signal and to switch-on the remaining phases at the time defined by the determined respective time-delay.The invention is also related to a corresponding device and system to perform such a method.