Arrangement for receiving electrical energy from a power grid and for discharging electrical energy to the power grid, having - at least one converter to convert from alternating current into direct current and vice versa, wherein the converter has - a direct current input and output, - an alternating current input and output, and - a power unit having power semiconductor devices, the power unit being connected on one side to the direct current input and output and on the other side to the alternating current input and output, - at least one energy storage device, in particular a battery storage comprising secondary cells, and - at least one energy converter, in particular having a heat generator, - at least one changeover mechanism to which either the energy storage device or the energy converter is connected using the direct current input and output, characterised in that - the arrangement has a control device for controlling the at least one changeover mechanism, said control device being configured such that - in the arrangement according to the invention, a neutral state is determined at a state of charge of the energy storage device greater than 50% and less than 100%, preferably at a state of charge of between 80% and 95%, - wherein the neutral state is the state of charge of the energy storage device in which the arrangement for receiving electrical energy from a power grid and for discharging electrical energy to the power grid can both provide the guaranteed primary regulating power and receive the guaranteed primary regulating power, and wherein the arrangement is adapted to operate in the following way: - in the neutral state or in a state of charge higher than the neutral state yet lower than the 100% state of charge, the changeover mechanism connects the direct current input and output of the converter - to the energy storage device at a network frequency that is lower than the nominal network frequency, - to the energy storage device or to the energy converter at a network frequency that is higher than the nominal network frequency but lower than the nominal network frequency plus a predetermined, non-zero amount, and - to the energy converter at a network frequency that is at least the predetermined, non-zero amount higher than the nominal network frequency, wherein, when the network frequency is above the nominal network frequency, power should be received, and when the network frequency is below the nominal network frequency, power should be provided. - at least one converter to convert from alternating current into direct current and vice versa, wherein the converter has - a direct current input and output, - an alternating current input and output, and - a power unit having power semiconductor devices, the power unit being connected on one side to the direct current input and output and on the other side to the alternating current input and output, - at least one energy storage device, in particular a battery storage comprising secondary cells, and - at least one energy converter, in particular having a heat generator, - at least one changeover mechanism to which either the energy storage device or the energy converter is connected using the direct current input and output, - the arrangement has a control device for controlling the at least one changeover mechanism, said control device being configured such that - in the arrangement according to the invention, a neutral state is determined at a state of charge of the energy storage device greater than 50% and less than 100%, preferably at a state of charge of between 80% and 95%, - wherein the neutral state is the state of charge of the energy storage device in which the arrangement for receiving electrical energy from a power grid and for discharging electrical energy to the power grid can both provide the guaranteed primary regulating power and receive the guaranteed primary regulating power, and - in the neutral state or in a state of charge higher than the neutral state yet lower than the 100% state of charge, the changeover mechanism connects the direct current input and output of the converter - to the energy storage device at a network frequency that is lower than the nominal network frequency, - to the energy storage device or to the energy converter at a network frequency that is higher than the nominal network frequency but lower than the nominal network frequency plus a predetermined, non-zero amount, and - to the energy converter at a network frequency that is at least the predetermined, non-zero amount higher than the nominal network frequency,