Apparatus for controlling a load flow in an AC voltage network, comprising: - a first module series circuit comprising two-pole switching modules, characterized by - a second module series circuit comprising two-pole switching modules, wherein the two module series circuits (9, 10) are connected to one another in a parallel circuit (3A, B, C) which can be inserted in series into a phase line of the AC voltage network, at least one switching module of each module series circuit (9, 10) has an energy store and also semiconductor switches which can be switched on and off and which can be controlled in such a way that a switching module voltage, which corresponds to a positive or negative energy store voltage (Vc) or to a zero voltage, can be generated at terminals (AC1, 2) of the switching module, wherein the apparatus further comprises a control device for controlling the switching modules, which control device is set up to generate an equalizing current between the module series circuits (9, 10) in order to balance the energy store voltages (Vc), wherein the equalizing current is an alternating current which has a current frequency that corresponds to a multiple of a line frequency of the AC voltage network. - a first module series circuit comprising two-pole switching modules, - a second module series circuit comprising two-pole switching modules, wherein the two module series circuits (9, 10) are connected to one another in a parallel circuit (3A, B, C) which can be inserted in series into a phase line of the AC voltage network, at least one switching module of each module series circuit (9, 10) has an energy store and also semiconductor switches which can be switched on and off and which can be controlled in such a way that a switching module voltage, which corresponds to a positive or negative energy store voltage (Vc) or to a zero voltage, can be generated at terminals (AC1, 2) of the switching module, wherein the apparatus further comprises a control device for controlling the switching modules, which control device is set up to generate an equalizing current between the module series circuits (9, 10) in order to balance the energy store voltages (Vc), wherein the equalizing current is an alternating current which has a current frequency that corresponds to a multiple of a line frequency of the AC voltage network. the two module series circuits (9, 10) are connected to one another in a parallel circuit (3A, B, C) which can be inserted in series into a phase line of the AC voltage network, at least one switching module of each module series circuit (9, 10) has an energy store and also semiconductor switches which can be switched on and off and which can be controlled in such a way that a switching module voltage, which corresponds to a positive or negative energy store voltage (Vc) or to a zero voltage, can be generated at terminals (AC1, 2) of the switching module, wherein the apparatus further comprises a control device for controlling the switching modules, which control device is set up to generate an equalizing current between the module series circuits (9, 10) in order to balance the energy store voltages (Vc), wherein the equalizing current is an alternating current which has a current frequency that corresponds to a multiple of a line frequency of the AC voltage network.