Economically efficient operation of a DRI system and additional subsystems of a global system.

Description

1 / 44 Economically Efficient Operation of a DRI System and Additional Subsystems of a Global System - Technical Field

[001] The present invention is based on a method of operation for a global system, in which The overall system comprises, as subsystems, a DRI plant, an electrolysis plant, and a hydrogen storage device. - The DRI installation and the electrolysis installation are connected directly or indirectly to a power supply network to extract electrical energy. The DRI plant, the electrolysis plant, and the hydrogen storage device are connected directly or indirectly to each other to transfer hydrogen.

[002] The present invention is further based on a control program for a control device for a global system, in which The overall system comprises, as subsystems, a DRI plant, an electrolysis plant, and a hydrogen storage device. - The DRI installation and the electrolysis installation are connected directly or indirectly to a power supply network to extract electrical energy. The DRI plant, the electrolysis plant, and the hydrogen storage device are connected directly or indirectly to each other to transfer hydrogen. The control program comprises machine code capable of being executed by the control device. The execution of machine code by the control device causes the control device to control the overall system. Petition 870250083982, dated 09 / 18 / 2025, page 11 / 78 2 / 44 in accordance with this method of operation.

[003] The present invention is further based on a control device for a global system, in which The overall system comprises, as subsystems, a DRI plant, an electrolysis plant, and a hydrogen storage device. - The DRI installation and the electrolysis installation are connected directly or indirectly to a power supply network to extract electrical energy. The DRI plant, the electrolysis plant, and the hydrogen storage device are connected directly or indirectly to each other to transfer hydrogen. The control device is programmed, by means of such a control program, so that when executing the machine code of the control program, the control device controls the overall system in accordance with such a method of operation.

[004] The present invention is also based on a global system, in which The overall system comprises, as subsystems, a DRI plant, an electrolysis plant, and a hydrogen storage device. - The DRI installation and the electrolysis installation are connected directly or indirectly to a power supply network to extract electrical energy. The DRI plant, the electrolysis plant, and the hydrogen storage device are connected directly or indirectly to each other to transfer hydrogen. The global system comprises a control device that, when executing the machine code of such a control program, will control the global system in accordance with such method. Petition 870250083982, dated 09 / 18 / 2025, page 12 / 78 3 / 44 of the operation. Previous Technique

[005] The matters mentioned are known - although not specifically for a DRI installation, but only for other installations in the steel industry - for example, from the article Green energy supply for the steel industry, Stahl and Eisen, August 2022, pages 22 to 24.

[006] Document KR 2019 0136300 A discloses an industrial process to which an energy storage device is assigned. The industrial process may be a more or less complex technical process comprising multiple subprocesses that complement and interact with each other. The industrial process presents various types of loads, namely loads that must be supplied with energy all the time, loads that can be switched off, and loads with configurable energy consumption. The effective energy consumption of the various components of the industrial plant is determined. The operation of the industrial plant and the energy storage device is coordinated in order to achieve minimum costs.

[007] US patent 10,354,297 B2 discloses an arrangement comprising a domestic consumer, a power generator, and an energy storage device. The operation of the energy storage device can be determined by taking into account the consumer's planned energy consumption. Meteorological data can also be used in conjunction. Price information for electricity consumption from a power grid can also be considered.

[008] Document TW 201 235 124 A discloses that the energy consumption of a steel industry plant - with specific mention of a rolling mill - can be predicted with good accuracy when the operating mode of the steel plant is known. Petition 870250083982, dated 09 / 18 / 2025, page 13 / 78 4 / 44

[009] US patent 8,288,888 B2 discloses an electrolysis plant coupled to a wind farm. Other loads and energy sources may also be present. The other loads and energy sources may also take the form of electrical energy storage devices. The hydrogen generated by the electrolysis plant may be transferred to an affiliated refinery or chemical plant.

[0010] Document WO 2021 / 183 022 A1 discloses a method of operation for a comprehensive system comprising, as subsystems, a DRI plant, an electrolysis plant, a hydrogen storage device, and a feeder device. The DRI plant and the electrolysis plant are connected to a feeder network. In addition, the DRI plant, the electrolysis plant, and the hydrogen storage device are interconnected to transfer hydrogen, and the DRI plant and the feeder device are interconnected to provide an additional gas to the DRI plant. The additional gas is a synthesis gas that is generated by means of an additional electrolysis plant and temporarily stored when required.

[0011] US patent 2015 / 0 259 760 A1 discloses a method of operation for a global system, wherein the global system comprises, as subsystems, a DRI plant, an electrolysis plant, a hydrogen storage device, and a feeder device. The DRI plant, the electrolysis plant, and the hydrogen storage device are directly or indirectly connected to each other to transfer hydrogen. Furthermore, the DRI plant and the feeder device are connected to each other to supply natural gas and / or ammonia to the DRI plant. The global system is controlled by predictive control. Summary of the Invention Petition 870250083982, dated 09 / 18 / 2025, page 14 / 78 5 / 44

[0012] Formerly, when determining the operation of steel industry facilities, the costs incurred in the process – including the energy costs incurred in the process – were taken into account. This applies equally to DRI facilities and other steel industry facilities. However, they were only taken into account in the sense that the total demand for electricity and the resulting electricity costs were considered. In the course of the shift to renewable energy, the availability of electricity (including the temporal fluctuations in electricity costs) must be taken into account to a considerably greater extent, since the availability and, consequently, also the costs of electricity will be subject to considerably greater fluctuations in the future than they have been in the past.

[0013] However, the operational cost of the overall system is determined by a multitude of other factors. The procedures of the prior art are therefore only slightly less than ideal.

[0014] Although the aforementioned article explains that the steel industry facility considered therein, the electrolysis plant, and an electrical energy storage device are controlled and operated by an intelligent energy management system, it does not contain more detailed explanations about the implementation of the intelligent energy management system.

[0015] The objective of the present invention is to provide possibilities that allow the cost-effective operation of a global system comprising, as subsystems, a DRI installation, an electrolysis installation and a hydrogen storage device.

[0016] The objective is achieved through a method of operation exhibiting the characteristics of claim 1. The claims Petition 870250083982, dated 09 / 18 / 2025, page 15 / 78 6 / 44 dependent actions 2 to 8 refer to advantageous configurations of the operating method.

[0017] First, the overall system comprises, as an (additional) subsystem, a power supply device – in addition to the aforementioned subsystems. The DRI installation and the power supply device are connected to each other to provide natural gas and / or ammonia to the DRI installation. Furthermore, an operating method of the type mentioned at the beginning is configured in such a way that

[0018] - a control device that controls the global system recognizes, as current states, a current state of the DRI installation, a current state of electrolysis of the electrolysis installation, a current state of hydrogen storage of the hydrogen storage device and a current state of power supply of the power supply device, - the control device recognizes, for a given forecast horizon, at least one desired production plan for the DRI installation, at least one expected price for electricity extracted through the supply network, and at least one expected price for natural gas and / or ammonia, The control device defines the operating modes for the forecast horizon and determines the expected final states at the end of the forecast horizon. - The operating modes comprise an installation operating mode for the DRI installation, an electrolysis operating mode for the electrolysis installation, a hydrogen storage operating mode for the hydrogen storage device, and a feeding operating mode for the feeding device. The expected end states comprise an installation end state determined by the use of the current installation state. Petition 870250083982, dated 09 / 18 / 2025, page 16 / 78 7 / 44 based on the defined installation operating mode, an expected final state of electrolysis determined by using the current state of electrolysis and the defined electrolysis operating mode, an expected final state of the hydrogen storage device determined by using the current state of the hydrogen storage device and the defined operating mode of the hydrogen storage device, and an expected final state of the feed determined by using the current state of the feed and the defined feed operating mode, - The control device varies the defined operating modes and, based on them, the expected final states for the forecast horizon, in order to minimize a cost function, - The cost function should include the costs of extracting electrical energy from the power grid, natural gas and / or ammonia consumption, and losses of hydrogen stored in the hydrogen storage device, as well as the operating modes of the DRI plant, the electrolysis plant, the hydrogen storage device, and the feeding device, and / or assessments of the expected end conditions, and should also include the productivity of the DRI plant, and - the control device operates the subsystems in accordance with their respective varied operating modes, at least for the beginning of the forecast horizon.

[0019] The starting point for the invention is the realization that a DRI installation can be operated alternatively with hydrogen, natural gas or ammonia and that, consequently, the consumption of natural gas and ammonia and the associated costs, as well as the operating costs of the corresponding power supply device, can also be included in the optimization.

[0020] The power supply device can be constructed as Petition 870250083982, dated 09 / 18 / 2025, page 17 / 78 8 / 44 required. For example, the supply device, with respect to natural gas, may comprise a tank for natural gas and / or be connected to a gas supply network. Alternatively or additionally, the supply device, with respect to ammonia, may comprise an ammonia generation device. However, this is not absolutely necessary. An ammonia storage device is also possible.

[0021] The installation status of the DRI facility describes the state of the DRI facility to the extent required. For example, the installation status could include which materials are currently in which state in the DRI facility and the state of the DRI facility units.

[0022] A current state of electrolysis of the electrolysis plant may comprise, for example, provided there is a corresponding dependence of hydrogen production efficiency on input power, the temperature of the electrolysis plant. The state of electrolysis may also comprise other variables that may vary, for example, electrolyte concentrations.

[0023] A current state of hydrogen storage describes, to the extent necessary, the state of the hydrogen storage device. The state of the hydrogen storage device may, in particular, comprise a degree or level of filling, that is, the degree of filling (in percentage and / or absolute terms) of the hydrogen storage device.

[0024] The current feed status describes the state of the feed device to the extent required. Given that the feed device comprises tanks, the status may, for example, include fill degrees or fill levels of tanks analogous to a hydrogen storage device. Optionally, additional data such as rates may also be defined. Petition 870250083982, dated 09 / 18 / 2025, page 18 / 78 9 / 44 maximum filling or withdrawal rates, loss rates or delivery rates. The feeding status may also include a degree of wear on the feeding device.

[0025] The DRI plant's production plan defines the extent to which iron or sponge iron should be produced by the DRI plant. The production plan may also define which intermediate products should be produced. In addition, the production plan may also define planned downtime periods for the DRI plant or parts of the DRI plant. For example, a scheduled downtime period may be required for maintenance purposes.

[0026] The expression "the prices of electricity or natural gas and / or ammonia are at least expected" includes, on the one hand, the case where it is an estimate based on known facts. For example, such known facts may be historical data from comparable previous periods or – in the case of electricity, in particular – a weather forecast. However, they may also refer to a price that is actually known, so that the price is not only expected but also actually verified.

[0027] The operating mode of the installation for the DRI installation is somewhat different from the production plan. In particular, the operating mode of the installation defines, for any given time, how the DRI installation is operated (= controlled). The operating mode of the installation is therefore continuous in terms of time (the DRI installation is operated in activation state A at 17:52:43, in activation state B at 17:52:44, in activation state C at 17:52:45, etc.).The installation operating mode must be clearly defined in such a way that the production plan specifications are met.

[0028] The electrolysis operating mode for the electrolysis plant defines, for any given time, how the electrolysis plant operates. Petition 870250083982, dated 09 / 18 / 2025, page 19 / 78 10 / 44 is operated (= controlled). The electrolysis operating mode is therefore continuous in terms of time, in the same way as the plant operating mode. The electrolysis operating mode defines the extent to which power is required for the electrolysis plant and the hydrogen produced by the electrolysis plant.

[0029] The DRI plant consumes hydrogen and / or natural gas and / or ammonia. The electrolysis plant produces hydrogen. If there are no other hydrogen generators and consumers besides the DRI plant and the electrolysis plant, the hydrogen storage operating mode for the hydrogen storage device is a dependent operating mode, as it simply needs to receive or emit the difference between the hydrogen required by the DRI plant and the hydrogen produced by the electrolysis plant. When determining the plant operating mode and the electrolysis operating mode, it will only be necessary to ensure that the hydrogen storage device does not become completely empty, has only a limited capacity, and that only certain quantities of hydrogen can be stored or removed from the hydrogen storage device per unit of time.

[0030] The power supply operating mode for the power supply device defines, analogously, at any given time, how the power supply device is operated (= controlled).

[0031] The control device determines the expected final states at the end of the forecast horizon based on the respective current states, updating them according to the respective operating mode.

[0032] Varying the defined operating modes with the objective of minimizing the cost function is a typical optimization problem. Optimization problems themselves, the way optimization problems work Petition 870250083982, dated 09 / 18 / 2025, page 20 / 78 11 / 44 issues are addressed and resolved, and are known to those versed in the art. By way of example only, the following references may be consulted: - Fletcher, R.: Practical Optimization Methods. 2nd ed., John Wiley Inc., Chichester, New York, 1987. - Hintermüller, M.; Stadler, G.: Semi-smooth Newtonian methods for linear-quadratic control problems, Revista de Matemática Aplicada e Mecânica (ZAMM) 83-4, 219-237, (2003), or - Ito, K.; Kunisch, K.: Semi-smooth Newton methods for optimal control problems with state constraints, Systems and Control Letters, 50, 221-228, (2003).

[0033] It is also known, from the aforementioned references, how it is possible to formulate constraints to be met, for example, performance limits of the DRI installation. Other issues relevant to the formulation of optimization problems are also known from the aforementioned references. One example of these issues is how deviations from preferred operating states can be penalized. Another example is how it is possible to formulate conditions to be met (through secondary equality constraints). The conditions to be met allow, for example, forcing the state of subsystems of the global system at the end of the forecast horizon. In the case of the hydrogen storage device, for example, such a state could be the amount of hydrogen stored.

[0034] The term cost function has a clear meaning for those versed in the technique in the field of optimization problems. Although it can be understood in the sense of an economic evaluation, this is not necessarily the case. In this case, the cost function can incorporate several variables.

[0035] Initially, the cost function incorporates the costs of ex Petition 870250083982, dated 09 / 18 / 2025, page 21 / 78 12 / 44 drawing electrical energy from the power grid. The costs of drawing electrical energy are self-explanatory. It should only be noted that the costs can be negative in individual cases, i.e., when the price of electricity consumption becomes negative for a period, for example, due to a temporary oversupply. The cost function also incorporates the costs of natural gas and / or ammonia consumption. The cost function also incorporates the losses of hydrogen contained in the hydrogen storage device (6). The latter takes into account the fact that non-negligible losses occur when hydrogen is stored for a relatively long period of time. Depending on the type of storage, the loss rate is at least 0.1% of the amount of hydrogen stored per day, and can reach 0.5% per day.

[0036] The cost function also incorporates the operating modes of the various subsystems and / or assessments of the expected end states. The assessment of the expected end state of the plant may include costs induced by wear and tear on the DRI plant. The assessment of the expected end state of the plant may also include a component that is determined, for example, by the use of a specific energy state or product phase state located in the DRI plant. A similar assessment is possible for the electrolysis plant. With regard to the hydrogen storage device and the feed device, the assessment may, in particular, incorporate wear and tear.The evaluation of the expected end state of the hydrogen storage device may, in addition, include a component determined by the utilization of a degradation of the hydrogen storage device caused by the operating mode of the hydrogen storage device, that is, a deterioration in the performance of the hydrogen storage device. The same applies to... Petition 870250083982, dated 09 / 18 / 2025, page 22 / 78 13 / 44 any storage device of the power supply device.

[0037] The cost function also incorporates the productivity of the DRI installation.

[0038] Preferably, the overall system comprises, as an additional subsystem, an electrical energy storage device that is directly or indirectly connected to the DRI installation, the electrolysis plant, and the power grid for transmitting electrical energy. In this case, the control device recognizes, as an additional current state, a current state of the electrical energy storage device, and the operating modes defined and varied by the control device additionally comprise an operating mode of the storage device for the electrical energy storage device. Furthermore, the expected final states additionally comprise a final state of the storage device determined by using the current state of the storage device and the defined operating mode of the storage device.Finally, the control device also varies the operating mode of the storage device and, based on that, the expected final state of the storage device.

[0039] The provision of an electrical energy storage device and its incorporation into the optimization considerably improves the flexibility with which it is possible to control the electrical energy consumption from the power grid. This is because the expected future electrical energy demand of the DRI installation, on the one hand, and the expected future price of the electrical energy extracted from the power grid, on the other, are crucial for the efficient use of the electrical energy storage device and the hydrogen storage device in the context of the present invention.

[0040] The state of the energy storage device Petition 870250083982, dated 09 / 18 / 2025, page 23 / 78 14 / 44 describes – similarly to the other states – the state of the electrical energy storage device to the necessary extent. The state of the energy storage device may include, for example, the degree of charge (in percentage and / or absolute terms) of the energy storage device and the temperature of the storage cells of the energy storage device. Furthermore, the state of the energy storage device may also include the wear and tear of the energy storage device or its parts. The state of the energy storage device may also include the maximum operational variables possible in principle and the maximum operational variables possible at the current moment, for example, charging and discharging currents.

[0041] The energy storage operating mode for the electrical energy storage device defines the extent to which the electrical energy storage device must be charged and discharged, respectively. The operating mode of the energy storage device is continuous, in the same way as the installation operating mode. An amount of electrical energy withdrawn from the electrical energy storage device may – naturally, only temporarily – be so large that it exceeds the energy requirement of the DRI installation and the electrolysis installation, so that, as a result, electrical energy is fed into the power grid.

[0042] The expected price of electricity drawn from the power grid can be set individually in each case for different periods. In a spot market, the price is often fixed only for a relatively limited period, for example, just 24 hours in advance. In this case, specific quantities of energy are traded for fixed periods at a respective Petition 870250083982, dated 09 / 18 / 2025, page 24 / 78 15 / 44 spot market price. However, there are also contracts with long-term commitments, for example, a fixed price for a certain level of performance one year in advance. These two examples are obviously not the only possible ones.

[0043] In order to reliably determine costs, the forecast horizon is therefore preferably divided into several start periods and several end periods. The number of start and end periods can be determined as needed. For example, if the purchase is made 24 hours in advance and billing is quarterly, the duration of a single time period will be 15 minutes, with the forecast horizon having 96 start periods and 4 end periods.

[0044] For the initial periods, the control device determines the operating mode of the storage device in such a way that, during the initial periods, the overall system extracts a predetermined amount of electrical energy for the respective initial period from the power grid. This allows for the reliable determination of the cost of extracting electrical energy in advance for the initial periods. Furthermore, the control device also varies the operating mode of the storage device, at least for the final periods, and, based on this, the expected final state of the storage device.

[0045] The procedure described above demonstrates all its advantages in the case where the control device defines, for the final periods, the amounts of electrical energy that must be extracted from the power supply network during the last periods. As a result, the energy consumption acquired, for example, in a spot market - neither more nor less - is actually needed and consumed even for the final periods.

[0046] The determination can be made, for example, based on Petition 870250083982, dated 09 / 18 / 2025, page 25 / 78 16 / 44 operating modes of the additional subsystems (i.e., without the electrical energy storage device) during the final periods, in a target state of the electrical energy storage device and in a deviation from an expected state of the storage device at the time of transition from the initial periods to the final periods. In particular, the price of electricity may also be included in the determination and, in some cases, even the price of fossil fuel. Optionally, the control device may also actively intervene in the pricing, compare the applicant's patent application filed on the same day as the present application, with the German title Kosteneffizienter Betrieb einer Anlage der Stahlindustrie und weiterer Teil-systeme eines Gesamtsystems.

[0047] Preferably, the control device takes into account a minimum and maximum state of charge of the electrical energy storage device and / or an average state of charge of the electrical energy storage device when varying the operating mode. Considering these variables – either as constraints to be observed or by incorporating them directly into the cost function – allows achieving a situation where the electrical energy storage device has a certain capacity at all times and in both directions – both to receive electrical energy and to emit it – so that it is possible to respond to faults during the operation of the DRI installation and / or the electrolysis installation – where applicable, even in the event of faults in the power supply network or other devices – by means of an altered operating mode of the electrical energy storage device.

[0048] In some cases, the global system has, as an additional subsystem, a power generation device through which electrical energy can be generated in a renewable way. In this case, the power generation device is directly or indirectly connected Petition 870250083982, dated 09 / 18 / 2025, page 26 / 78 17 / 44 attached to the DRI installation, the electrolysis plant and the power supply network, and, in general, also to the electrical energy storage device, to transmit electrical energy. The energy generation device may be designed, in particular, as a wind turbine or as a photovoltaic installation. The method of operation is designed, in the case of an existing energy generation device, in such a way that - the control device, for the forecast horizon, additionally recognizes an expected electrical energy that can be generated by the power generation device, and - The control device should take into account the expected electrical energy that can be generated by the power generation device when varying the operating modes.

[0049] This allows for even greater optimization of the operation of the global system.

[0050] Preferably, the control device takes into account a minimum and maximum filling level of the hydrogen storage device and / or an average filling level of the hydrogen storage device when varying the operating modes. Taking these variables into account – either as constraints to be observed or by incorporating them directly into the cost function – allows a situation to be achieved where the hydrogen storage device has a certain capacity at all times and in both directions – both to receive hydrogen and to release it – so that it is possible to respond to malfunctions during the operation of the DRI plant and / or the electrolysis plant – where applicable, even in the event of malfunction of the power supply network or other devices – by means of an altered operating mode of the hydrogen storage device.

[0051] It may be advantageous for the power supply device to Petition 870250083982, dated 09 / 18 / 2025, p. 27 / 78 18 / 44 attach a generating device to produce ammonia with or without an associated ammonia storage device. In this case, the generating device is connected directly or indirectly to the DRI installation, the electrolysis plant, and the power supply network to transmit electrical energy. Furthermore, in this case, the current power supply state comprises a current operational state of the generating device, the power supply operating mode comprises the operating mode of the generating device, and the expected final power supply state comprises an expected final operational state of the generating device, wherein the expected final operational state of the generating device is determined by the control device with the updating of the current operational state according to the operating mode of the generating device. Thus, varying the power supply operating mode also comprises varying the operating mode of the generating device.

[0052] The objective is further achieved by a control program exhibiting the characteristics of claim 9. According to the invention, the overall controlled system comprises, as an (additional) subsystem, a power supply device – in addition to the aforementioned subsystems. The DRI installation and the power supply device are connected to each other to provide natural gas and / or ammonia to the DRI installation. Furthermore, the execution of the machine code by the control device causes it to control the overall system in accordance with an operating method according to the invention.

[0053] The objective is further achieved by a control device having the characteristics of claim 10. According to the invention, the overall controlled system comprises, as an (additional) subsystem, a power supply device – in addition to the aforementioned subsystems. The DRI installation and the power supply device Petition 870250083982, dated 09 / 18 / 2025, page 28 / 78 19 / 44 tation are interconnected to provide natural gas and / or ammonia to the DRI installation. Furthermore, the control device is programmed, by means of a control program according to the invention, so that the control device, when executing the machine code of the control program, controls the overall system in accordance with an operating method according to the invention.

[0054] The objective is further achieved by a global system exhibiting the characteristics of claim 11. According to the invention, it is provided that - the overall controlled system includes, as an (additional) subsystem, a power supply device - in addition to the aforementioned subsystems, - the DRI installation and the power supply device are connected to each other to provide natural gas and / or ammonia to the DRI installation and - the control device is designed as a control device according to the invention, which, when executing the machine code of the control program, will control the overall system in accordance with a method of operation according to the invention. Brief Description of the Figures

[0055] The properties, characteristics and advantages of this invention described above, and the manner in which these are achieved, will become clearer and more understandable in conjunction with the following description of an exemplary embodiment, which is explained in greater detail in conjunction with the drawings. In the figures: Figure 1 shows a global system, Figure 2 shows a flowchart, Figure 3 shows an additional global system, and Figure 4 shows a flowchart. Petition 870250083982, dated 09 / 18 / 2025, page 29 / 78 20 / 44 Figure 5 shows a timeline, Figure 6 shows a flowchart, and Figure 7 shows a flowchart. Description of the Implementations

[0056] According to Figure 1, a global system comprises a DRI (direct iron reduction) system 1 as a subsystem. In the DRI 1 plant, sponge iron is produced from iron ore. The DRI 1 plant requires a constant supply of hydrogen, natural gas and / or ammonia, as well as electrical energy, according to production.

[0057] The DRI 1 installation can draw electrical energy from a power supply network 2 to which the DRI 1 installation is connected directly (not shown) or indirectly (for example, by means of a power converter 3). The power supply network 2 is typically a three-phase network and therefore a multi-phase power supply network. The three-phase network is often operated at medium voltage in the range of 20 kV to 30 kV or at high voltage of 110 kV.

[0058] The overall system comprises an electrolysis plant 4 as an additional subsystem. The electrolysis plant 4 also consumes electrical energy during its operation. The electrolysis plant 4 is therefore also connected to the power grid 2. The electrolysis plant 4 requires a DC voltage to operate. A rectifier 5 is therefore generally located upstream of the electrolysis plant 4, thus having only an indirect connection to the power grid 2. The DRI plant 1 and the electrolysis plant 4 are connected directly or indirectly to each other to transfer hydrogen. Any pumps, valves and the like are also not illustrated in Figure 1.

[0059] The overall system comprises a hydrogen storage device 6 as an additional subsystem. The device Petition 870250083982, dated 09 / 18 / 2025, page 30 / 78 21 / 44 of hydrogen storage 6 can be conceived as a storage device in a more restricted sense, that is, as a dedicated hydrogen storage device. However, the pipeline network through which hydrogen is transported also has a certain storage capacity and can serve as a hydrogen storage device 6 for the purposes of the present invention. In the case of a separate dedicated storage device, the storage device can alternatively be installed above ground or underground. The hydrogen storage device 6 is connected directly or indirectly to the electrolysis plant 4 to receive hydrogen and connected directly or indirectly to the DRI plant 1 to produce hydrogen. The operation of the DRI plant 1 and the electrolysis plant 4 can be more flexible due to the hydrogen storage device 6.

[0060] It is possible that the hydrogen generated by the electrolysis plant 4 is always supplied to the hydrogen storage device 6 and that the hydrogen required by the DRI plant 1 is always supplied by the hydrogen storage device 6, so that the hydrogen storage device 6 serves as a hydrogen transfer station, so to speak. However, a direct connection between the DRI plant 1 and the electrolysis plant 4 is also possible.

[0061] The overall system comprises a power supply device 7 as an additional subsystem. Installation DRI 1 and the power supply device 7 are connected to each other to provide natural gas and / or ammonia to installation DRI 1.

[0062] Figure 1 shows a simple configuration of the feed device 7, in which storage devices 7a and 7b are present to store natural gas and ammonia, respectively. However, alternative configurations are also possible. By Petition 870250083982, dated 09 / 18 / 2025, page 31 / 78 22 / 44 For example, the power supply device 7 may comprise a connection to a natural gas supply network. In this case, the storage device 7a may – but not necessarily – be omitted. Similarly, the power supply device 7 may comprise a generating device to produce ammonia. In this case, the storage device 7b may – but not necessarily – be omitted. Furthermore, Figure 1 shows a configuration of the power supply device 7 capable of supplying both natural gas and ammonia to the DRI 1 installation. However, it is also possible that the power supply device 7 of the DRI 1 installation is capable of supplying only natural gas or ammonia.

[0063] If the generating device for generating ammonia is included, the generating device will also generally be connected, directly or indirectly, to the DRI 1 installation, the electrolysis installation 4, and the power supply network 2 to transmit electrical energy. It is possible that this generating device for the production of ammonia from nitrogen and hydrogen may be connected to the electrolysis installation 4 and / or the hydrogen storage device 6.

[0064] The overall system further comprises a control device 8. The control device 8 is programmed with a control program 9. The control program 9 comprises machine code 10 executable by the control device 8. Programming with the control program 9 causes the control device 8 to execute the machine code 10. Execution of the machine code 10 by the control device 8 causes the control device 8 to control the overall system in accordance with a method of operation which is explained in greater detail below, in conjunction with Figure 2. However, even before explaining the method of operation according to the invention, it is noted that the control device 8 is explained below as being a single device of Petition 870250083982, dated 09 / 18 / 2025, page 32 / 78 23 / 44 control 8 that jointly controls subsystems 1, 4, 6, and 7 of the overall system. However, control device 8 may also have its own sub-control device to control each of the subsystems 1, 4, 6, and 7. In this case, proper information exchange and coordination must occur between the sub-control devices.

[0065] According to Figure 2, in a step S1, the control device 8 recognizes a current state Z of the global system. The current state Z comprises a respective current substate Z1, Z4, Z6, Z7 for subsystems 1, 4, 6 and 7. The number in the respective current substate Z1, Z4, Z6, Z7 corresponds to the reference signal of the respective subsystem 1, 4, 6 and 7.

[0066] For example, substate Z1 may encompass the production progress of plant DRI 1. Substate Z1 may also encompass which materials are in which state at the current moment in plant DRI 1.

[0067] Substate Z4 may include, for example, the temperature and chemical composition of the electrolysis fluid of electrolysis plant 4 and the wear status of electrolysis plant 4.

[0068] Substate Z6 comprises at least the filling level of the hydrogen storage device 6, i.e., the measure to which the hydrogen storage device 6 is filled. Substate Z6 may also include other variables, for example, a temperature and / or pressure of the hydrogen storage device 6 gas or the maximum possible or permissible flow of hydrogen during filling and emptying of the hydrogen storage device 6.

[0069] Similar explanations can be applied to the Z7 substate of power supply device 7. If power supply device 7 comprises the generating device for generating ammonia, the state Petition 870250083982, dated 09 / 18 / 2025, page 33 / 78 The current 24 / 44 power supply Z7 will also include the current operational state of the generating device.

[0070] In a step S2, control device 8 recognizes a desired production plan PP from the DRI 1 plant. As an example, the production plan PP can be specified to control device 8 by an operator (not shown). The production plan PP defines which final products should be produced from which raw materials by the DRI 1 plant and what characteristics the final products should have. In general, the production plan PP also defines which intermediate products should be produced and when a specific product should be produced. The production plan PP extends over a forecast horizon PH. The forecast horizon PH is usually at least several hours, often even on the order of several days.

[0071] For example, the PP production plan may include a quantity of pig iron that must be produced per hour or per day using the DRI 1 installation. The PP production plan may also specify the minimum amount of carbon that must be contained in the pig iron or sponge iron produced and / or the maximum amount of nitrogen that must be contained in the pig iron or sponge iron produced.

[0072] In a step S3, the control device 8 recognizes the data D. The data D will be used to determine at least one expected price P1 of electricity for the forecast horizon PH, if the electricity is obtained from the supply network 2. The data D is also used to determine at least the expected prices P2, P3 for natural gas and / or ammonia. Prices P1 to P3 are defined at least as a function of time t. They may also depend on other circumstances.

[0073] If necessary, control device 8 can initially Petition 870250083982, dated 09 / 18 / 2025, page 34 / 78 25 / 44 recognize the production plan PP and the data D for prices P1 to P3 for different time horizons in steps S2 and S3. In this case, the forecast horizon PH is determined by the shorter of the time horizons.

[0074] In step S4, control device 8 defines an operating mode B for the global system for the forecast horizon PH. Operating mode B comprises – analogously to the current state Z – a respective partial operating mode B1, B4, B6, B7 for subsystems 1, 4, 6, and 7. The partial operating modes B1, B4, B6, B7 define, for any given time, how the respective subsystem 1, 4, 6, 7 is operated (= controlled). The partial operating modes B1, B4, B6, B7 can be resolved in time in seconds. The defined operating modes B, B1, B4, B6, B7 are initially only provisional.

[0075] Partial operating mode B1 for installation DRI 1, hereinafter also referred to as installation operating mode B1, is defined by control device 8 in such a way that the specifications of the production plan PP are met. In particular, installation operating mode B1 may include the quantities of materials and energy supplied to installation DRI 1, for example, the quantity of iron ore, the quantity of hydrogen, the quantity of natural gas, the quantity of ammonia and the quantity of electric current.

[0076] Partial operating mode B4 for electrolysis plant 4 – hereinafter also referred to as electrolysis operating mode B4 – can often be set separately and relatively flexibly by control device 8. Control device 8 only needs to ensure that the hydrogen requirement of the DRI plant 1 is met, that the filling level of the hydrogen storage device 6 does not fall below 0% and does not exceed 100%, and that the design limits of the electrolysis plant are also met. Petition 870250083982, dated 18 / 09 / 2025, page 35 / 78 26 / 44 electrolysis 4 should be observed. As an alternative to a virtually free approach to the B4 electrolysis operating mode, it is also possible to specify, also for the electrolysis plant, a production plan that should be taken into account when determining the B4 electrolysis operating mode. Depending on the specific case, a more or less uniform operation of the electrolysis plant 4 may make sense. However, it may also make sense to vary the operation of the electrolysis plant 4 over time, particularly if electricity costs fluctuate significantly.

[0077] The partial operating mode B6 for the hydrogen storage device 6 – hereinafter also referred to as the hydrogen storage device operating mode B6 – can no longer be freely defined by the control device 8. Instead, it is defined by the plant operating mode B1 (and therefore by hydrogen consumption) and the electrolysis operating mode B4 (and therefore by hydrogen generation). However, the hydrogen storage device 6 allows, at least to some extent, the dissociation of the operation of the DRI plant 1 and the electrolysis plant 4, thus allowing flexible operation of the electrolysis plant 4.

[0078] Partial operating mode B7 for power supply device 7 - hereinafter also referred to as power supply operating mode B7 - optionally also includes the operating mode of the generating device.

[0079] In step S5, the control device determines an expected overall final state Z' for the end of the forecast horizon PH. The expected overall final state Z' comprises – in the same way as the current state Z – an expected final substate Z1', Z4', Z6', Z7' for each of the subsystems 1, 4, 6 and 7. The respective expected final substate Petition 870250083982, dated 09 / 18 / 2025, page 36 / 78 27 / 44 Z1', Z4', Z6', Z7' is determined by using the respective current substate Z1, Z4, Z6, Z7 and the respective partial operating mode B1, B4, B6, B7. Specifically, control device 8 determines the respective expected final substate Z1', Z4', Z6', Z7' by updating the respective current substate Z1, Z4, Z6, Z7 based on the respective partial operating mode B1, B4, B6, B7. The expected final substate Z7' optionally also comprises an expected final operating state of the generating device. The expected final operating state is optionally determined by control device 8 by updating the current operating state in accordance with the operating mode of the generating device.

[0080] In a step S6, the control device 8 determines the value of a cost function K. The cost function K can incorporate several cost factors. The cost function K is defined as a weighted or unweighted sum of the individual cost factors. For example, cost factors include the cost of extracting electrical energy from the power grid 2 and the consumption of natural gas and / or ammonia. In addition, the operating modes B1, B4, B6, and B7 of subsystems 1, 4, 6, and 7 also represent these cost factors. Alternatively to the operating modes B1, B4, B6, and B7 of subsystems 1, 4, 6, and 7, or in addition to them, evaluations of the expected end states Z1', Z4', Z6', and Z7' are also possible. Finally, the productivity of the DRI 1 plant also represents this cost factor. In addition to the quantity of pig iron or sponge iron produced, the productivity of the DRI 1 plant can also be determined by the quality characteristics of the pig iron or sponge iron produced.

[0081] To determine the costs of extracting electrical energy from the power grid 2, the control device 8 can, for example, determine the electrical energy consumption of the power grid 2 based on the partial operating modes B1, B4, B6 and B7. Petition 870250083982, dated 09 / 18 / 2025, page 37 / 78 28 / 44 of the and, based on this, determine the associated costs together with the known price P1. The determination can occur with the same temporal resolution with which the partial operating modes B1, B4, B6 and B7 are also determined, for example, for the second. The determination can also be carried out with a more approximate temporal resolution, for example, with a resolution of 1 minute or 15 minutes. It is also possible to initially work with high temporal resolution, for example, in seconds, but, based on this, perform statistical evaluations for longer periods (for example, 1 minute, 5 minutes, 15 minutes), for example, to determine average values, maximum values, minimum values, dispersion, etc.

[0082] The operating mode of installation B1 can be evaluated, for example, in terms of productivity, resource-saving operation, wear assessment of installation DRI 1, etc. Similar evaluations are also possible for the electrolysis operating mode B4, the hydrogen storage device operating mode B6, and the feed operating mode B7.

[0083] The assessment of the expected end state of the Z1' installation may include a component that is determined, for example, by using an energy state of the DRI 1 installation – this also includes the energy state of the products located in the DRI 1 installation. The control device 8 is therefore capable of determining the assessment of the expected end state of the Z1' installation taking into account the amount of energy that needs to be applied during the subsequent operation of the DRI 1 installation beyond the forecast horizon PH.

[0084] The assessment of the expected final state of the Z1' plant may also take into account the wear caused by the operation of the DRI 1 plant, i.e., the costs resulting from the wear that occurs during the PH production horizon due to the operating mode of Petition 870250083982, dated 09 / 18 / 2025, page 38 / 78 29 / 44 installation B1.

[0085] The assessment of the expected end state of electrolysis Z4' may also include a component that is determined by the use of an energy state of the electrolysis plant 4, in particular, in the case of an electrolysis plant 4 operating at high temperature. The assessment may also incorporate electrolytic fluid concentrations and wear states.

[0086] Evaluating the expected end state of the Z6' hydrogen storage device is generally very straightforward. It is usually just a constant.

[0087] The evaluation of the expected final state of the Z7' feed is also normally very simple. Analogous to the final state of the Z6' hydrogen storage device, it is normally just a constant.

[0088] Evaluating the productivity of the DRI 1 plant is also relatively simple. Typically, it is better (i.e., the corresponding cost factor is lower) the greater the quantity of initial product produced in a given unit of time. In the simplest case, the corresponding cost factor is proportional to the time required to produce a previously defined quantity of initial product on a single basis.

[0089] The cost function K also includes costs that take into account hydrogen losses in the hydrogen storage device 6. An analogous procedure is also optionally possible for the feed device 7.

[0090] The cost function K may also incorporate other cost factors. Some possible additional cost factors will be discussed below by way of example.

[0091] As an example, it is possible to consider a cost factor that represents the costs of the remainder of the DRI facility's operation. Petition 870250083982, dated 09 / 18 / 2025, page 39 / 78 30 / 44 1, that is, the costs q for the forecast horizon PH in question, but without taking into account the costs of electricity. The costs of the remainder of the operation of the DRI 1 plant may, for example, include the costs of additional input materials required (raw materials) or the costs of preparing process media or costs due to environmental pollution, for example, carbon tax costs. The cost factor for the remainder of the operation of the DRI 1 plant may also include depreciation.

[0092] Similarly, it is also possible to consider cost factors that represent the costs of the remainder of the operation of the electrolysis plant 4 and the hydrogen storage device 6.

[0093] Other costs of the global system may also be considered, if such costs are incurred. Examples of such costs are environmental fees or government subsidies.

[0094] The cost function K therefore incorporates all free control variables for all subsystems 1, 4, 6 and 7. In particular, the quantities of hydrogen and / or natural gas and / or ammonia and the associated costs are also incorporated into the cost function K.

[0095] In a step S7, the control device 8 solves an optimization problem. The solution to the optimization problem is the combination of partial operating modes B1, B4, B6, and B7 – each considered along the production horizon PH – for which the overall cost function K is minimal. The cost function K is therefore a functional that must be minimized and is calculated based on an initial value problem with final conditions. As part of the solution to the optimization problem, the control device 8 varies the partial operating modes B1, B4, B6, and B7 defined for the forecast horizon PH. The variation is performed taking into account the production plan PP and other constraints, such as, for example, the Petition 870250083982, dated 09 / 18 / 2025, page 40 / 78 31 / 44 design limits of the different subsystems 1, 4, 6 and 7. This also applies, in particular, to the operational limits of the feed device 7, for example, to the possibilities for the production, storage and feeding of ammonia. If specified, a production plan for the electrolysis plant 4 will also be taken into account. Furthermore, when solving the optimization problem, the control device 8 takes into account the limitation of the rates at which the hydrogen, natural gas and ammonia components supplied to the DRI plant 1 can be changed. The control device 8 therefore takes into account that changes to these components require a certain amount of time. In principle, however, any desired division into hydrogen, natural gas and ammonia is possible.Furthermore, control device 8 can also take into account that a change in the split into hydrogen, natural gas and ammonia can influence the carbon ratio in the sponge iron produced by the DRI 1 plant and that subsequent processes are consequently influenced, for example, thermally and then in terms of their energy needs, in particular. Often, it is advantageous to use a minimum proportion of natural gas. This can be ensured by a corresponding secondary inequality constraint. In view of this, the variation of the feed operating mode B7 also includes the variation of the operating mode of the generating device.

[0096] By varying the operating modes B1, B4, B6 and B7, control device 10 can also take into account other conditions. Examples of such conditions may be, for example, specifications for the expected end substates Z1', Z4', Z6' and Z7'.For example, it is possible to define, as a specification, that the hydrogen storage device 6 has a somewhat specific degree of filling at the end of the PH forecast horizon, or that the degree of filling of the hydrogen storage device 6 is... Petition 870250083982, dated 09 / 18 / 2025, page 41 / 78 32 / 44 is set within a predetermined range at the end of the PH forecast horizon. Similar specifications may optionally be provided for power supply device 7. Such conditions may be considered, in particular, using so-called secondary equality constraints and / or secondary inequality constraints. Other conditions are also possible, for example, that the energy drawn from the power supply network 2 does not exceed a specified maximum value or that the production of certain products is completed within a specified time.

[0097] Optimization problems themselves, their approach and procedures for solving such optimization problems are well known to those versed in the technique. They are also approached in this way in terms of the approach in the aforementioned technique.

[0098] When step S7 is executed, the varied and therefore optimized partial operating modes B1, B4, B6 and B7 will be defined. The control device 8 can therefore, in a step S8, operate subsystems 1, 4, 6 and 7 in accordance with the various partial operating modes B1, B4, B6 and B7. This is done initially for the beginning of the forecast horizon PH.

[0099] In a step S9, the control device 8 checks if new information is available to it. Otherwise, the control device 8 returns to step S8. By executing step S8 again, the control device 8 continues to operate subsystems 1, 4, 6, and 7 in accordance with the various partial operating modes B1, B4, B6, and B7. In doing so, it takes into account time t.

[00100] If new information becomes available to control device 8, control device 8 will advance to step S10. In step S10, control device 8 checks if the information is a command to interrupt the operation of the global system. If it is Petition 870250083982, dated 09 / 18 / 2025, page 42 / 78 33 / 44 In this case, control device 8 will interrupt the operation of the global system at step S11. Otherwise, control device 8 returns to step S1. Depending on the type of new information, control device 8 may alternatively return to step S2 or step S3.

[00101] As a result, the procedure according to Figure 2 means that the partial operating modes B1, B4, B6 and B7 continue to be checked repeatedly with a certain forecast horizon PH. The check is therefore carried out in the sense of a permanent forecast and is continuously adapted to the expected price P and the production plan PP.

[00102] The overall system in Figure 3 comprises the same components as the overall system in Figure 1. In addition, however, the overall system includes an electrical energy storage device 11, as shown in Figure 3. The energy storage device 11 is connected directly or indirectly to the power grid 2, at least to receive electrical energy, possibly also to generate electrical energy. The energy storage device 11 is additionally connected to the DRI installation 1 and the electrolysis installation 4 to generate electrical energy. If the energy storage device 11 receives electrical energy, it will always be drawn from the power grid 2. If the energy storage device 11 generates electrical energy, it will be used primarily to meet the demands of the DRI installation 1 and the electrolysis installation 4 and only secondarily to power the power grid 2.Consequently - depending on whether the electrical energy produced by the energy storage device 11 is greater or less than the electrical energy consumed by the DRI installation 1 and the electrolysis installation 4 - the electrical energy may be temporarily fed into the power supply network 2 or... Petition 870250083982, dated 09 / 18 / 2025, page 43 / 78 34 / 44 extracted from power supply network 2.

[00103] It must be possible to determine whether, and to what extent, electrical energy is supplied to the energy storage device 11 or whether, and to what extent, the electrical energy storage device 11 generates electrical energy. For this purpose, a bidirectionally operable power converter unit is usually present. This power converter unit is also not illustrated in Figure 1. Instead, it is considered part of the energy storage device 11.

[00104] The exact manner in which the DRI installation 1, the electrolysis installation 4, and the energy storage device 11 are electrically connected to each other and to the power grid 2 is of minor importance. In particular, the rectifiers 5, inverters, and other energy converters 3 can be assigned to the various subsystems 1, 4, and 11 as needed. However, it must be ensured that it is possible to transfer electrical energy from the energy storage device 11 to the DRI installation 1 and to the electrolysis installation 4 without a diversion through the power grid 2.

[00105] The electrical energy storage device 11 is an additional subsystem of the overall system and is also treated as such by the control device 8. The integration of the electrical energy storage device 11 into the operating method is shown in Figure 4.

[00106] Steps S21 to S31 of Figure 4 correspond, in terms of approach, to steps S1 to S11 of Figure 2. According to the illustration in Figure 4, however, the control device 8 recognizes a current state of the electrical energy storage device Z11 as another current state Z11. The substate Z11 comprises at least the charge state of the energy storage device 11, that is, the charge level of the weapon device. Petition 870250083982, dated 09 / 18 / 2025, page 44 / 78 35 / 44 Energy storage 11. Substate Z11 may also comprise other variables, for example, a temperature of the energy storage device 11 or a maximum possible or permitted charge and discharge current. In addition, substate Z11 may comprise a wear state of the energy storage device 11.

[00107] For the same reasons, the operating modes defined and varied by the control device 8 additionally comprise an operating mode B11 for the electrical energy storage device 11. The partial operating mode B11 for the energy storage device 11 – hereinafter also referred to as the operating mode B11 of the energy storage device – can, in some cases, be determined independently and often relatively flexibly by the control device 8. The control device 8 only needs to ensure that the state of charge of the energy storage device 11 does not fall below 0% and does not exceed 100%, and also that the design limits of the energy storage device 11 (e.g., the maximum charging current and the maximum discharging current) are observed.

[00108] Similarly, the expected end states additionally comprise an end state of storage device Z11', determined by the use of the current state of storage device Z11 and the defined operating mode of storage device B11.

[00109] Finally, control device 8 also varies the operating mode B11 of the storage device within the scope of optimization and, based on this, the expected final state Z11' of the storage device. By varying the partial operating modes B1, B4, B6, B7 and B11so, control device 8 also takes into account Petition 870250083982, dated 09 / 18 / 2025, page 45 / 78 36 / 44 preferably a minimum and maximum state of charge of the electrical energy storage device 11 and / or an average state of charge of the electrical energy storage device 1. This can be taken into account because deviations from the average state of charge are incorporated into the cost function K in a weighted manner with a factor, albeit relatively small – and are therefore penalized. There may also be a requirement that no energy be fed into the power grid 2 or that the energy drawn from the power grid 2 does not exceed a specified maximum value. The assessment of the expected final state of the energy storage device Z11' may comprise a component with which the wear caused by the operation of the energy storage device 11 is taken into account, i.e., the costs resulting from the wear that occurs during the production horizon PH due to the operating mode B11 of the storage device.

[00110] A particularly advantageous configuration of the present invention is explained below in conjunction with Figures 5 and 6. The energy storage device 11 is required within the scope of this configuration.

[00111] According to Figure 5, the PH forecast horizon is divided into numerous initial periods 12 and numerous final periods 13. For example, with a typical PH forecast horizon of 24 hours, periods 12 and 13 may each last 15 minutes, and 92 initial periods 12 and 4 final periods may still be present. However, the mentioned duration and also the mentioned numbers of initial and final periods 12 and 13 should be understood as merely illustrative in each case.

[00112] In the case of a division of the PH forecast horizon into initial and final periods 12 and 13, step S26 of Figure 4 can be configured according to the illustration in Figure 6. Petition 870250083982, dated 09 / 18 / 2025, page 46 / 78 37 / 44

[00113] According to Figure 6, step S26 of Figure 4 is divided into steps S41 and S42. In step S41, the control device 8 optimizes the operating modes B1, B4, B6, B7, and B11 for the initial periods 12. In step S42, the control device 8 optimizes the operating modes B1, B4, B6, B7, and B11 for the final periods 13. The difference between steps S41 and S42 lies in the fact that the control device 8, in the optimization performed during step S41, takes into account the additional boundary condition that, during the initial periods 12, the system as a whole consumes a predetermined quantity E12 of electrical energy from the power grid 2 for the respective initial period 12. Although the quantity E12 could be determined individually for the respective initial period 12, it is known.The operating mode B11 of the electrical energy storage device 11 is therefore determined so that the respective quantity E of electrical energy consumed from the power grid 2 during the respective initial period 12 corresponds to this value. Conversely, no boundary conditions are considered in step S42. The amount of electrical energy that the overall system draws from the power grid 2 is therefore adjusted during the final periods 13 in accordance with the optimization of operating modes B1, B4, B6, B7 and B11. Consequently, the control device 8 also varies the operating mode B11 of the storage device within the scope of the optimization for the final periods 13 and, based on this, the expected final state of the storage device Z11'.

[00114] The final periods 13 are often so far in the future that the energy quantities for the final periods 13 can be firmly ordered in an energy exchange. Therefore, it is possible to supplement the procedure in Figure 6 with steps S43 and S44. In step S43, the control device 8 orders quantities Petition 870250083982, dated 09 / 18 / 2025, page 47 / 78 38 / 44 energy des for the final periods 13 in an energy exchange. In step S44, the control device 8 assigns the corresponding amounts of energy to the corresponding final periods 13, thus determining, for the final periods 13, the corresponding amounts of electrical energy that must be drawn from the power grid 2 during each of the last 13 time periods.

[00115] Figure 3 also shows a further extension of the global system of Figure 1. According to Figure 3, the global system has a power generation device 14 as an additional subsystem. The power generation device 14 can be used to generate electricity in a renewable way, i.e., using solar or wind energy, possibly also using hydroelectric or geothermal energy. In this case, the power generation device 14 is connected directly or indirectly to the other electrical energy receiving or emitting subsystems 1, 4, 11, and also to the power grid 2, to transmit electrical energy. A power converter, normally required for the power generation device 14, can be considered part of the power generation device 14. This is also not illustrated in Figure 3.Preferably, it is possible to supply electrical power from power generation device 14 to subsystems 1, 4, 11 without diversion through the power supply network 2.

[00116] If power generation device 14 is present, the procedure in Figure 4, according to Figure 7, will initially be modified so that a step S51 is additionally present. Step S51 precedes step S24. It may immediately precede step S24, as shown in Figure 7. However, this is not absolutely necessary. In step S51, the control device 8 recognizes, for the forecast horizon PH, an amount of electrical energy that can be generated (provisionally) by power generation device 14. Such a forecast may, for example, be Petition 870250083982, dated 09 / 18 / 2025, page 48 / 78 39 / 44 made using a local weather forecast for the location of the power generation device 14.

[00117] Furthermore, the procedure in Figure 4 is modified so that, in step S26, the expected electrical energy that can be generated by the energy generation device 14 is considered in the cost function K. This gives rise, in step S27, to other partial operating modes B1, B4, B6, B7, B11 for which the cost function K becomes minimal.

[00118] Next, for the DRI 1 installation, the electrolysis installation 4 (including the hydrogen storage device 6) and the power generation device 14, an explanation of possible models that can be used to determine the respective cost factor is presented. These models are implemented in the control device 8 and evaluated by it as part of step S6 or S26.

[00119] For the DRI 1 installation, a function v and a nominal electrical power P* are defined, each for the forecast horizon PH. The function v is a function of time t. The nominal power P* can be a constant. The nominal power P* is multiplied by the function v. The result is the actual electrical power P with which the DRI 1 installation is operated: P = v(t)P*. (1)

[00120] The function v is defined for positive time values ​​and presents a range of values ​​from vmin to 1, where vmin itself has a value between 0 and 1. vmin is a function of the state of the DRI 1 installation. The current value of vmin takes into account the fact that it is not possible to arbitrarily reduce the actual power P in any state of the DRI 1 installation. On the contrary, this depends on the state of the DRI 1 installation. The control device 8 must therefore recognize the state of the DRI 1 installation. As a rule, an attempt will be made to operate the DRI 1 installation as uniformly as possible. The value of vmin Petition 870250083982, dated 09 / 18 / 2025, page 49 / 78 40 / 44 will normally be just slightly below 1.

[00121] The total electrical energy requirement of the DRI 1 installation is a function of the v-function profile. The control device 8 can independently determine the total electrical energy requirement of the DRI 1 installation. Alternatively, the total electrical energy requirement of the DRI 1 installation can, for example, be specified or determined through the energy balance (radiation) of the DRI 1 installation.

[00122] The function v can be used by the control device 8 to influence the operating mode of the DRI 1 installation. Obviously, the amount of sponge iron produced will be reduced if the function v has a value less than 1. The control device 8 can therefore determine the associated time delay T and, consequently, evaluate: Ka = k1 + k2T. (2)

[00123] k1 is a constant with the unit currency, for example, 2000 euros. k2 is a constant with the unit currency per time, for example, 1000 euros per minute. T is the time difference by which the production of the DRI 1 installation is reduced to produce a given quantity of sponge iron, for example, in minutes.

[00124] The cost factor Ka is, however, confronted by a considerable potential for savings in terms of energy costs, provided that it is possible to shift a high consumption of electrical energy from the DRI 1 installation to times when the electrical energy obtained from the power grid 2 has a low cost. Here, the advantages of the present invention are shown, that is, when the operation of the DRI 1 installation, the electrolysis installation 4, the hydrogen storage device 6, the power supply device 7 and, optionally, also the electrical energy storage device 11 are optimized Petition 870250083982, dated 09 / 18 / 2025, page 50 / 78 41 / 44 together. The advantages could be even greater if energy could also be generated independently by the energy generation device 14.

[00125] The cost portion Kb caused for the DRI 1 installation due to the supplied electrical energy can be determined by integrating the respective instantaneous costs over the production horizon PH. The instantaneous costs can be determined as k3(t)P(t) (3)

[00126] In this case, k3 is a factor, dependent at least on time t, that reflects the costs of extracting electrical energy from the power grid 2.

[00127] Similarly, the additional cost components Kc, Kd and Ke caused for the DRI 1 installation due to the hydrogen, natural gas and ammonia provided can also be determined.

[00128] In addition, direct reduction also produces carbon dioxide, for which certificates will often be required when released into the environment. This cost component must also be taken into account.

[00129] The total cost breakdown for the DRI 1 installation is the sum of the cost breakdowns explained above.

[00130] Electrolysis plant 4 produces and emits hydrogen, and hydrogen storage device 6 receives and emits hydrogen. The fact that some of the stored hydrogen escapes is taken into account. As already mentioned, losses can reach up to 0.5% of the amount of hydrogen stored per day. Furthermore, energy is required to compress the hydrogen under pressure in hydrogen storage device 6. This energy is normally no longer recoverable once the hydrogen is removed from hydrogen storage device 6. The costs – common to the operation of electrolysis plant 4 and the weapon device – are also included. Petition 870250083982, dated 09 / 18 / 2025, page 51 / 78 42 / 44 hydrogen storage 6 can be determined, for example, by integrating the respective instantaneous costs over the production horizon PH. The instantaneous costs can be determined as k3(t)P'(t) + k4H'(t) (4)

[00131] In this case, k3 is the factor already explained in conjunction with Equation 3. P' is the electrical energy extracted from the power grid 2. In the simplest case, the factor k5 is a constant. The factor k5 may also be time-dependent, when applicable. H' is the amount of hydrogen being lost at the moment, that is, the derivative of the amount of hydrogen stored as a function of time t. If necessary, the wear and tear of the electrolysis plant 4 may also be considered in the costs.

[00132] Similarly, the costs of generating ammonia from hydrogen and storing ammonia, for example, can also be considered. It should also be considered that ammonia production requires not only energy but also hydrogen. As a general rule, the necessary nitrogen can be extracted from the air. However, under certain circumstances, costs may be incurred for separating oxygen and other gases from the air. Any potential wear and tear on the generating device can also be taken into account.

[00133] If the power generation device 14 is directly assigned to the other subsystems 1, 4, 6, 7 and, optionally, 11, that is, in particular, if the electrical energy generated by the power generation device 14 can be supplied to subsystems 1, 4, 6, 7 and, optionally, 11 without a diversion through the power grid 2, the generation of electrical energy will be free of charge. If (temporarily) it exceeds the electrical energy consumption of the other subsystems 1, 4, 6, 7 and, optionally, 11, the electrical energy will be fed into the power grid 2. In this particular case, the costs of the generation device Petition 870250083982, dated 09 / 18 / 2025, page 52 / 78 43 / 44 of energy 14 can even be negative.

[00134] The present invention offers numerous advantages. In particular, it is possible to comprehensively optimize the operation of the overall system consisting of subsystems 1, 4, 6 and 7, and possibly also subsystems 11 and 14.

[00135] Although the invention has been illustrated and described more particularly by the preferred exemplary embodiments, the invention is not limited to the examples disclosed, and other variations may be derived therefrom by those skilled in the art without departing from the scope of protection of the invention. List of reference symbols 1 Installation 2 Power supply network 3 Power converter 4 Electrolysis installation 5 Rectifier 6 Hydrogen storage device 7 Feeding device 7a, 7b Storage devices 8 Control device 9 Control program 10 Machine code 11 Energy storage device 12, 13 Time periods 14 Energy generation device B, B1, B4, B6, B7, B11 Operating modes D Data E; E12, E13 Energy quantities K Cost function Petition 870250083982, dated 09 / 18 / 2025, page 53 / 78 44 / 44 P1 to P3 Prices PH Forecast horizon PP Production plan S1 to S51 Stages t Time Z, Z1, Z4, Z6, Z7, Z11 Current states Z', Z1', Z4', Z6', Z7', Z11' Expected final states Petition 870250083982, dated 09 / 18 / 2025, page 54 / 78

Claims

1 / 8 CLAIMS 1. Method of operation for a global system, characterized in that - the global system comprises, as subsystems, a DRI installation (1), an electrolysis installation (4), a hydrogen storage device (6) and a power supply device (7), - the DRI installation (1) and the electrolysis installation (4) are connected directly or indirectly to an electrical power supply network (2) to extract electrical energy, - the DRI installation (1), the electrolysis installation (4) and the hydrogen storage device (6) are connected directly or indirectly to each other to transfer hydrogen, - the DRI installation (1) and the power supply device (7) are connected to each other to provide natural gas and / or ammonia to the DRI installation (1), - a control device (8) that controls the global system recognizes, as current states, a current installation state (Z1) of the DRI installation (1), a current electrolysis state (Z4) of the electrolysis installation (4),a current state of hydrogen storage (Z6) of the hydrogen storage device (6) and a current state of feed (Z7) of the feed device (7), - the control device (8) recognize, for a forecast horizon (PH), at least one desired production plan (PP) of the DRI installation (1), at least one expected price (P1) for the electrical energy obtained through the feed network (2) and at least one expected price (P2, P3) for natural gas and / or ammonia, - the control device (8) define operating modes (B1, B4, B6, B7) for the forecast horizon and determine the expected final states (Z1', Z4', Z6', Z7') for the end of the forecast horizon (PH), Petition 870250083982, dated 09 / 18 / 2025, p. 55 / 78 2 / 8 - the operating modes (B1, B4, B6, B7) comprise an installation operating mode (B1) for the DRI installation (1), an electrolysis operating mode (B4) for the electrolysis installation (4),a hydrogen storage device operating mode (B6) for the hydrogen storage device (6) and a feed operating mode (B7) for the feed device (7), - the expected end states (Z1', Z4', Z6', Z7') comprise an installation end state (Z1') determined by using the current installation state (Z1) and the defined installation operating mode (B1), an expected electrolysis end state (Z4') determined by using the current electrolysis state (Z4) and the defined electrolysis operating mode (B4), an expected hydrogen storage device end state (B6') determined by using the current hydrogen storage device state (Z6) and the defined hydrogen storage device operating mode (B6), and an expected feed end state (Z7') determined by using the current feed state (Z7) and the defined feed operating mode (B7),- the control device (8) vary the defined operating modes (B1, B4, B6, B7) and, based on them, the expected final states (Z1', Z4', Z6', Z7') for the forecast horizon (PH) in order to minimize a cost function (K), - the cost function (K) include the costs for extracting electrical energy from the power grid (2), consumption of natural gas and / or ammonia and losses of hydrogen stored in the hydrogen storage device (6), and also include the operating modes (B1, B4, B6, B7) of the DRI installation (1), the electrolysis installation (4), the hydrogen storage device (6) and the power supply device (7) and / or assessments of the expected final conditions Petition 870250083982, dated 09 / 18 / 2025, p. 56 / 78 3 / 8 (Z1', Z4', Z6', Z7') and also a productivity of the DRI installation (1), and - the control device (8) operates the subsystems (1, 4, 6, 7) in accordance with the respective varied operating mode (B1, B4, B6, B7),at least for the beginning of the forecast horizon (PH).

2. Method of operation according to claim 1, characterized in that: - the overall system comprises an electrical energy storage device (11) as an additional subsystem; - the electrical energy storage device (11) is connected directly or indirectly to the DRI installation (1), the electrolysis installation (4), and the power grid (2) to transmit electrical energy; - the control device (8) recognizes, as an additional current state (Z11), a storage current state (Z11) of the electrical energy storage device (11); and the operating modes defined and varied by the control device (8) additionally comprise a storage operating mode (B11) for the electrical energy storage device (11).- the expected final states additionally comprise a final state of the storage device (Z11') determined by using the current state of the storage device (Z11) and the defined operating mode of the storage device (B11), - the control device (8) also varies the operating mode of the storage device (B11) and, based on this, the expected final state of the storage device (Z11').

3. Method of operation, according to claim 2, characterized in that Petition 870250083982, dated 09 / 18 / 2025, page 57 / 78 4 / 8 - the forecast horizon (PH) is divided into numerous initial periods (12) and numerous final periods (13), - the control device (8) determines the operating mode of the storage device (B11) for the initial periods (12) in such a way that, during these periods (12), the system as a whole extracts an amount of electrical energy (E12) that is predetermined for the respective initial period (12) from the power grid (2), and - the control device (8) also varies the operating mode of the storage device (B11) at least for the final periods (13) and, based on it, the expected final state of the storage device (Z11').

4. Method of operation, according to claim 3, characterized in that, for the final periods (13), the control device (8) determines quantities (E13) of electrical energy that must be extracted from the power supply network (2) during each of the last time periods (13).

5. Method of operation, according to any one of claims 2 to 4, characterized in that the control device (8) takes into account a minimum and maximum state of charge of the electrical energy storage device (11) and / or an average state of charge of the electrical energy storage device (11) when varying the operating modes (B1, B4, B6, B7, B11).

6. Method of operation, according to any of the preceding claims, characterized in that - the global system has, as an additional subsystem, a power generation device (14) by means of which electrical energy can be generated in a renewable manner, Petition 870250083982, dated 09 / 18 / 2025, page 58 / 78 5 / 8 - the power generation device (14) is connected directly or indirectly to the DRI installation (1), to the electrolysis installation (4) and to the power grid (2) to transmit electrical energy, - the control device (8), for the forecast horizon (PH), additionally recognizes an expected electrical energy that can be generated by the power generation device (14), and - the control device (8) takes into account the expected electrical energy that can be generated by the power generation device (14) when varying the operating modes (B1, B4, B6, B7).

7. Method of operation, according to any of the preceding claims, characterized in that the control device (8) takes into account a minimum and maximum filling level of the hydrogen storage device (6) and / or an average filling level of the hydrogen storage device (6) when varying the operating modes (B1, P4, B6, B7).

8. Method of operation, according to any of the preceding claims, characterized in that - the power supply device (7) comprises a generating device for generating ammonia, with or without an associated storage device (7b) for ammonia, - the generating device is connected directly or indirectly to the DRI installation (1), the electrolysis installation (4) and the power supply network (2) for transmitting electrical energy, - the current power supply state (Z7) comprises a current operational state of the generating device, - the power supply operating mode (B7) comprises the operating mode of the generating device, - the expected final power supply state (Z7') comprises an expected final operational state of the generating device, which is Petition 870250083982, dated 09 / 18 / 2025, p.59 / 78 6 / 8 determined by the control device (8) with the update of the current operating state in accordance with the operating mode of the generating device, and - the variation of the power supply operating mode (B7) also includes the variation of the operating mode of the generating device.

9. Control program for a control device (8) for a global system, characterized in that: - the global system comprises, as subsystems, a DRI plant (1), an electrolysis plant (4), a hydrogen storage device (6) and a power supply device (7); - the DRI plant (1) and the electrolysis plant (4) are connected directly or indirectly to a power supply network to extract electrical energy; - the DRI plant (1), the electrolysis plant (4) and the hydrogen storage device (6) are connected directly or indirectly to each other to transfer hydrogen; - the DRI plant (1) and the power supply device (7) are connected to each other to supply natural gas and / or ammonia to the DRI plant (1); - the control program comprises a machine code (10) that can be executed by the control device (8).- the execution of the machine code (10) by the control device (8) causes the control device (8) to control the overall system in accordance with a method of operation, as defined in any of the preceding claims.

10. Control device for a global system, characterized in that - the global system comprises, as subsystems, a DRI installation (1), an electrolysis installation (4), a Petition device 870250083982, dated 18 / 09 / 2025, page.60 / 78 7 / 8 hydrogen storage (6) and a power supply device (7), - the DRI installation (1) and the electrolysis installation (4) being connected directly or indirectly to a power supply network to extract electrical energy, - the DRI installation (1), the electrolysis installation (4) and the hydrogen storage device (6) being connected directly or indirectly to each other to transfer hydrogen, - the DRI installation (1) and the power supply device (7) being connected to each other to provide natural gas and / or ammonia to the DRI installation (1), - the control device being programmed, by means of a control program (9), as defined in claim 9, so that the control device, when executing the machine code (10) of the control program (9), controls the overall system in accordance with an operating method, as defined in any of claims 1 to 8.

11. Global system, characterized in that - the global system comprises, as subsystems, a DRI installation (1), an electrolysis installation (4), a hydrogen storage device (6) and a power supply device (7), - the DRI installation (1) and the electrolysis installation (4) are connected directly or indirectly to a power supply network to extract electrical energy, - the DRI installation (1), the electrolysis installation (4) and the hydrogen storage device (6) are connected directly or indirectly to each other to transfer hydrogen, - the DRI installation (1) and the power supply device (7) are connected to each other to provide natural gas and / or ammonia to the DRI installation (1), - the global system comprises a control device Petition 870250083982, dated 09 / 18 / 2025, page.61 / 78 8 / 8 (8), according to claim 10, that when executing the machine code (10) of a control program (9) of claim 9, it will control the overall system in accordance with a method of operation, as defined in any of claims 1 to 8. Petition 870250083982, dated 09 / 18 / 2025, p. 62 / 78.

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