The invention discloses an electric power system. The electric power system includes an OLTC transformer including a plurality of primary and secondary windings inductively coupled to each other. Theelectric power system includes at least one on-load tap changer that is coupled to at least one of the primary and secondary windings and selectively configurable to regulate the portion of the primary and secondary windings inductively coupled to each other. The electric power system also includes a plurality of buses coupled to the transformer and positioned downstream therefrom. The electric power system further includes at least one processor coupled to the tap changer and configured to regulate a voltage bandwidth of the tap changer as a function of estimated voltage values of at least one bus as estimated based on a priori values of the power/current transmitted through each bus. The a priori values are substantially based on measured power/current transmission through the on-load tap changer.