Cost-efficient operation of a steel industry system and ad-ditional sub-systems of an entire system

An operating method for an overall system,

• wherein the overall system comprises, as subsystems, a steel industry installation, an electrolysis installation, an electrical energy storage device and a hydrogen storage device,
• wherein the steel industry installation, the electrolysis installation and the electrical energy storage device are connected directly or indirectly to one another and to an electrical supply grid in order to transmit electrical energy,
• wherein the steel industry installation, the electrolysis installation and the hydrogen storage device are connected directly or indirectly to one another in order to transfer hydrogen,
• wherein a control device that controls the overall system is aware, as current states (Z1, Z4, Z6, Z7), of a current installation state (Z1) of the steel industry installation, a current electrolysis state (Z4) of the electrolysis installation, a current energy storage device state (Z6) of the energy storage device and a current hydrogen storage device state (Z7) of the hydrogen storage device,
• wherein the control device is aware, for a forecast horizon (PH), of at least one desired production plan (PP) of the steel industry installation and at least one expected price (P) of electrical energy drawn from the supply grid,
• wherein the production plan (PP) of the steel industry installation defines which end products are intended to be produced from which starting materials by the steel industry installation and which characteristics the end products are intended to have,
• wherein the control device sets operating modes (B1, B4, B6, B7) for the forecast horizon (PH) and ascertains expected final states (Z1′, Z4′, Z6′, Z7′) for the end of the forecast horizon (PH),
• wherein the operating modes (B1, B4, B6, B7) comprise an installation operating mode (B1) for the steel industry installation, an electrolysis operating mode (B4) for the electrolysis installation, an energy storage device operating mode (B6) for the electrical energy storage device and a hydrogen storage device operating mode (B7) for the hydrogen storage device,
• wherein the expected final states (Z1′, Z4′, Z6′, Z7′) comprise a final installation state (Z1′) ascertained by exploiting the current installation state (Z1) and the set installation operating mode (B1), an expected final electrolysis state (Z4′) ascertained by exploiting the current electrolysis state (Z4) and the set electrolysis operating mode (B4), an expected final energy storage device state (Z6′) ascertained by exploiting the current energy storage device state (Z6) and the set energy storage device operating mode (B6), and an expected final hydrogen storage device state (Z7′) ascertained by exploiting the current hydrogen storage device state (Z7) and the set hydrogen storage device operating mode (B7),
• wherein the current and final installation state (Z1, Z1′) comprise which materials are in which state in each case in the steel industry installation and the state of units of the steel industry installation,
• wherein the control device varies the set operating modes (B1, B4, B6, B7) and, based thereon, the expected final states (Z1′, Z4′, Z6′, Z7′) for the forecast horizon (PH), taking into account the production plan (PP) and design limits of the subsystems, so as to minimize a cost function (K),
• wherein the cost function (K) incorporates the costs of drawing electrical energy from the supply grid, the operating modes (B1, B4, B6, B7) of the steel industry installation, of the electrolysis installation, of the electrical energy storage device and of the hydrogen storage device, assessments of the expected final states (Z1′, Z4′, Z6′, Z7′) and a productivity of the steel industry installation, and
• wherein the control device operates the subsystems in line with the varied operating mode (B1, B4, B6, B7), at least for the beginning of the forecast horizon (PH).