Method for controlling an electrolysis system

Abstract

The invention relates to a method for controlling an electrolysis system (100) having an electrolysis module (110, 120) and a first electrolysis unit (114-116), wherein the electrolysis module (110, 120) has a second electrolysis unit and a third electrolysis unit. The method has the steps of: providing a production operating point for the electrolysis system (100); providing a respective unit efficiency characteristic curve (210, 220, 230) for each of the electrolysis units; determining a module efficiency characteristic curve using the second unit efficiency characteristic curve and the third unit efficiency characteristic curve, said module efficiency characteristic curve being determined on the basis of an efficiency-optimized distribution of respective production operating points of the second electrolysis unit and the third electrolysis unit; determining a system efficiency characteristic curve using the module efficiency characteristic curve and the first unit efficiency characteristic curve on the basis of an efficiency-optimized distribution of respective production operating points for the electrolysis module (110, 120) and for the first electrolysis unit; and determining a corresponding production operating point for the first, second and / or third electrolysis unit on the basis of the system efficiency characteristic curve and the production operating point for the electrolysis system (100) in order to control the electrolysis system (100).

Description

[0001] R.409603 - 1 - Description Title Procedure for one State of the Art: To scale the production of hydrogen, electrolysis plants typically have so-called (electrolysis) clusters, which in turn can have several electrolysis modules, which in turn can consist of several electrolysis stacks or electrolysis units. In an electrolysis plant, the quantity to be produced can be distributed across several electrolysis clusters. Within an electrolysis cluster, several electrolysis modules can be controlled in a coordinated manner to represent the quantity or rate of hydrogen to be produced. Disclosure of the Invention: Within an electrolysis module, either each electrolysis stack can be operated at its own (production) operating point, or several electrolysis stacks can be electrically interconnected (electrically in series or parallel) so that these electrolysis stacks are operated at the same production operating point. Electrolysis stacks and / or electrolysis units, i.e.Electrolysis stacks, i.e., electrolysis stacks with associated, independently controlled power electronics, can be grouped in an electrolysis plant to form electrolysis modules or electrolysis clusters, which can be operated by a control unit and / or a plurality of control units. A production operating point can be defined electrically and / or set according to a required production rate. The operating point, defined electrically by means of a supplied electrical power, for an electrolysis unit and / or a corresponding R.409603 -. 2 -A grouping of electrolysis units (module, cluster, plant) can be determined or specified independently for each electrolysis unit and / or for the corresponding grouping. In particular, the production operating point can mean a product quantity and / or a production rate, in particular of produced hydrogen, per electrolysis unit and / or per grouping (module, cluster, plant). The control unit of the electrolysis plant can control the respective electrolysis clusters, electrolysis modules, and / or electrolysis stacks such that a sum of the production operating points, or a sum of the respective unit, module, or cluster production rates, corresponds to a production operating point, or a production rate, of the entire electrolysis plant. Thus, the production rate of the electrolysis plant can be distributed accordingly among the electrolysis clusters, electrolysis modules, and / or electrolysis units, and thus among the electrolysis stacks.One criterion for the design of an electrolysis plant can be the greatest possible production efficiency of the electrolysis plant across all electrolysis units of the electrolysis plant, or for a large number of electrolysis plants. By optimizing the electrolysis plant or another grouping of electrolysis units for the greatest possible efficiency, a reduction in production costs, especially for hydrogen (levelized cost of hydrogen), can be achieved, particularly to achieve widespread use of electrolysis and / or green hydrogen. A respective production operating point optimized with respect to the efficiency of the electrolysis plant for a large number of electrolysis modules or electrolysis units, which may be operated geographically separately and controlled by respective control units, is to be determined.According to aspects of the invention, a method for controlling an electrolysis system with an electrolysis module and a first electrolysis unit and a control unit for an electrolysis system according to the features of the independent claims are proposed. Advantageous embodiments are the subject of the dependent claims and the following description. According to one aspect, a method for controlling an electrolysis system with an electrolysis module and a first electrolysis unit is proposed, wherein the R.409603 -. 3 -Electrolysis module has a second electrolysis unit and a third electrolysis unit. In one step of the method, a production operating point (i.e., for example, an electrolysis production rate and / or hydrogen production rate) is provided for the electrolysis plant. In a further step, a respective unit efficiency characteristic curve is provided for the respective electrolysis unit. In a further step, a module efficiency characteristic curve, in particular for the electrolysis module, is determined by means of the second unit efficiency characteristic curve and the third unit efficiency characteristic curve, wherein the module efficiency characteristic curve is determined based on an efficiency-optimized distribution of the respective production operating points, in particular for hydrogen production, between the second electrolysis unit and the third electrolysis unit, in particular for the electrolysis module.In a further step, a plant efficiency characteristic curve is determined for the electrolysis plant using the module efficiency characteristic curve and the first unit efficiency characteristic curve, based on an efficiency-optimized distribution of the production operating points for the electrolysis module and the first electrolysis unit. In a further step, a corresponding production operating point for the first, second, and / or third electrolysis unit is determined based on the plant efficiency characteristic curve and the production operating point for the electrolysis plant, for, in particular, optimized control of the electrolysis plant, in particular according to the hydrogen production rate of the electrolysis plant. The efficiency characteristic curve of a respective element of a grouping, in particular an electrolysis grouping (unit, module, cluster, plant, or a plurality of plants) can indicate an efficiency of electrolysis production at a production operating point.The production operating point can, for example, be a value for an (electrolysis or hydrogen production rate and / or a value for an electrical power for a respective element of a grouping (unit, module, cluster, plant or plurality of plants). The efficiency can be a respective efficiency, in particular electrolysis production efficiency or hydrogen production, for a respective production operating point. For example, the electrolysis production efficiency can be an efficiency of an electrolysis production rate and / or a hydrogen production rate and / or an efficiency of standardized operating costs in electrolysis production and / or a R.409603 -. 4 -Efficiency of standardized operating costs and capital employed in electrolysis production (LCOH) for an electrical power used in electrolysis production and / or for a resulting electrolysis production rate provided to an electrolysis unit, an electrolysis module, an electrolysis cluster, an electrolysis plant, and / or a plurality of electrolysis plants for electrolytic production, in particular of hydrogen. Accordingly, the efficiency curve of an electrolysis unit, an electrolysis module, an electrolysis cluster, an electrolysis plant, and / or a plurality of electrolysis plants can describe the efficiency of an electrolysis production rate, in particular a hydrogen production rate, as a function of an electrical power used and / or a resulting electrolysis production rate.For the method, a consistent definition of the efficiency and / or efficiency characteristic curve can be used for all elements of an (electrolysis) grouping (unit, module, cluster, plant, or a plurality of plants). The efficiency characteristic curve of the respective grouping (unit, module, cluster, plant) can be determined using at least two efficiency characteristics of elements (unit, module, cluster, plant) of the respective grouping, based on an efficiency-optimized distribution of the production rates of the elements, by determining an optimal distribution of the production rates among the elements for each production operating point of the respective grouping depending on the respective element efficiency characteristic curve. An electrolysis plant can have a plurality of electrolysis clusters and / or a plurality of electrolysis modules and / or a plurality of electrolysis units.A respective unit efficiency characteristic curve can be assigned to the respective electrolysis unit. A respective module efficiency characteristic curve can be assigned to the respective electrolysis module. A respective cluster efficiency characteristic curve can be assigned to the respective electrolysis cluster. A respective system efficiency characteristic curve can be assigned to the respective electrolysis system. The respective electrolysis unit can have a plurality of electrolysis stacks and has respective power electronics that are electrically coupled to the respective electrolysis unit. The respective power electronics are configured to supply electrical power to the electrolysis unit independently of other electrolysis units. 5 -in particular, according to a production operating point of the respective electrolysis unit. The electrolysis plant, an electrolysis cluster, an electrolysis module, and / or an electrolysis unit can be operated with a specific production operating point, whereby this production operating point can be, for example, a specific production quantity, a specific electrical power, or a specific utilization. For example, the module efficiency curve can be determined using the following formulas based on the efficiency-optimized distribution of production rates between two electrolysis units as a function of the production quantity and a distribution of production rates between the two electrolysis units.The variables and parameters can be defined as follows: The unit efficiency characteristic curve can be a dependency of an efficiency, such as a production rate of the electrolysis unit per provided electrical power, depending on the production rate of the electrolysis unit, in particular hydrogen. ^^: Unit efficiency characteristic curve of an electrolysis unit 1^^: Unit efficiency characteristic curve of an electrolysis unit 2X: Total production rate (e.g. in kg / h) ^^: Production rate of electrolysis unit 1 (e.g. in kg / h)^^: Production rate of electrolysis unit 2 (e.g. in kg / h)^^,^^^ / ^^^: Minimum and maximum possible production rate of electrolysis unit 1 (e.g. in kg / h)^^,^^^ / ^^^: Minimum and maximum possible production rate of electrolysis unit 2 (e.g.in kg / h)^^^: Distribution factor (0: total production using electrolysis unit 2, 1: total production using electrolysis unit 1)^: Module efficiency^^^^: Optimized module efficiency The module efficiency ^ can be determined using the respective efficiencies of the electrolysis units as: ^(^, ^^^) = ^^^ ∗ ^^(^^^ ∗ ^) + (1 − ^^^) ∗ ^^((1 − ^^^) ∗ ^) Formula 1 R.409603 -. 6 - where the individual production rates ^^, ^^ of the two electrolysis units are as follows: ^^ = ^^^ ∗ ^ and ^^ = (1 − ^^^) ∗ ^ Formulas 2In order to determine an efficiency-optimized distribution fac of the production rates among the electrolysis units for each possible total production rate X, which results in the maximum module efficiency ^^^^, the following optimization problem can be formulated, in which the distribution factor fac is chosen so that the module efficiency is maximized: Formel 3Where the distribution factor ^^^ is subject to the following constraints in order not to exceed the minimum and maximum production rates of the electrolysis units: Formeln 4 This maximization can be reformulated as a minimization problem with a small adjustment: ^^^^(^) = −m^^ i^n ^−^(^, ^^^)^ Formula 5 This minimization problem can now be solved using the well-known numerical methods for solving nonlinear optimization problems with constraints. For typical efficiency curves, there is only a single minimum in this optimization, which allows methods such as the extended Broyden–Fletcher–Goldfarb–Shanno algorithm (L-BFGS-B) to be used. If several local minima arise for special cases, a brute-force method can be used, for example, to determine the global minimum. One advantage of the method is that it can be applied within a grouping (unit, module, cluster, plant), even across a large number of elements. R.409603 - 7 -the respective grouping, and / or is scalable across grouping boundaries (from unit to module; from module to cluster; from cluster to plant; and / or from plant to a multitude of plants). Furthermore, the method is suitable for distributed and possibly inhomogeneous systems. The amount of data that must be exchanged between the elements of a grouping and / or different groupings can be kept low with this method. Therefore, the method can be used to specify a practical optimization method for efficient electrolysis production, which can be used for a large number of stacks, units, modules, clusters and / or plants, including decentralized or distributed electrolysis plants, in order to determine an optimal production operating point and thus ensure maximum overall efficiency. In contrast to the operation of electrolysis units that are operated according to a rigidly defined scheme, e.g.If all electrolysis units are switched on in a specific order and then operated at the same operating point, or if only local optimization of the production operating points is carried out, which only takes into account a limited number of electrolysis units or modules of an electrolysis plant based on a characterization of the respective electrolysis units, this method can be used to perform an efficiency optimization of the entire electrolysis plant. Advantageously, this method for controlling an electrolysis plant can be used to perform an efficiency optimization of the electrolysis units of the entire electrolysis plant, especially at different locations, since only a small amount of data needs to be exchanged between the groups, or in particular between locations or electrolysis plants.Furthermore, in this method for controlling the electrolysis plant, the complexity of efficiency optimization is very low, in contrast to other methods, since exchanging efficiency curves and efficiency-optimized distributions of production rates with other elements or other groups is sufficient for the process. Thus, the process can be used even if the operating characteristics of one element of a grouping change, as in the case of R.409603. 8 -For example, an electrolysis module, the corresponding production operating point can be implemented or updated quickly and with little computational effort. Therefore, this method largely eliminates the need to exchange characteristic parameters, such as efficiencies and losses, or mathematical models of components such as power electronics, pumps, heaters, coolers, gas dryers, and / or compressors, etc., which in turn can differ in each electrolysis plant, electrolysis cluster, or electrolysis module, depending on where the component is located. The implementation of this method for controlling the electrolysis plant is therefore not limited by the complexity of the electrolysis plant. Additionally or alternatively, elements of the electrolysis plant that are operated with different control units can be optimized.This method for controlling the electrolysis plant, which can have electrolysis elements in different groupings, enables the effort required for efficiency optimization to be kept to a minimum through distributed optimization within a grouping or level (module level, cluster level, plant level, etc.) and across grouping boundaries. The method can be carried out using control units for the respective level or grouping. To coordinate a large number of electrolysis plants with regard to efficiency optimization, a server can be linked to the respective control units of the electrolysis plant. To carry out the method for controlling the electrolysis plant, an efficiency curve can be transferred from a lower level of a grouping to the next higher level of a grouping.This allows an optimal production operating point to be determined for each electrolysis unit of the electrolysis plant without requiring a central control unit, such as a top-level control unit, to have information on the operating characteristics of the individual electrolysis units, thus minimizing the need for corresponding data transmission. R.409603 -. 9 -Furthermore, the method can be used to divide the efficiency-optimized distribution of production rates into a multitude of optimization problems in order to reduce the overall complexity of the determination and to distribute the required processing capacity among available control units. This can ensure that the individual control units require less computing capacity. In other words, the method for controlling the electrolysis plant can be used to group subsystems at each level, starting with the lowest level, i.e., the electrolysis unit level, for which a substitute model for an efficiency-optimized distribution of production rates (an optimized load distribution) within the subsystem is determined. For example, such a substitute model can be created for all electrolysis units of an electrolysis module.These replacement models can then be used by the next higher level to determine a replacement model for that level. For example, the replacement models of the electrolysis modules can be used to determine a replacement model for a cluster, or to determine an optimal load distribution of an electrolysis cluster among its electrolysis modules. This procedure can be repeated up to the highest available level, such as an electrolysis plant level or a central server for coordinating multiple electrolysis plants. The replacement model can be exchanged between levels, particularly without additional operating data. It may be irrelevant how the replacement model is determined, as long as the replacement model describes the same dependencies, such as efficiency as a function of the hydrogen production rate or efficiency as a function of electrical power.This exchange can be carried out using a defined, and especially standardizable, interface between the levels or between the partial optimizations. Compared to complete operating data and / or operating characteristics of all individual electrolysis units and / or all individual electrolysis modules, a minimum of data may be sufficient to implement the process for controlling the electrolysis plant. The replacement models can be determined locally on the control units of the electrolysis modules, electrolysis clusters, and / or electrolysis plants. 10 -This allows the required computing power to be distributed among the existing control units, in particular without requiring a powerful central processing unit. Due to the two aspects mentioned, the method for controlling the electrolysis plant offers the possibility of determining a respective optimal production operating point, taking into account the operating characteristics of many electrolysis stacks and / or electrolysis units, which may be distributed across many electrolysis modules, electrolysis clusters, and electrolysis plants, whereby, in particular, a low computing time and / or low data requirements are necessary. This can make such comprehensive optimization practical and / or increase the overall efficiency of hydrogen production and / or reduce production costs, particularly for hydrogen production, using the electrolysis units.According to one aspect, it is proposed that each electrolysis unit has an electrolysis stack and a respective power electronics unit for operating the electrolysis stack with electrical power. By means of the power electronics, each electrolysis stack can be operated independently at specific production operating points in order to optimize the overall efficiency of a production rate of a second electrolysis unit and a third electrolysis unit. According to one aspect, it is proposed that the efficiency characteristic curve characterizes a dependence of an efficiency of electrolytic production on an electrolytic production rate of the respective electrolysis unit. In other words, the efficiency characteristic curve can indicate how a production quantity and / or production rate, in particular for hydrogen, depends on a provided electrical power and / or the production rate.According to one aspect, it is proposed that the efficiency-optimized distribution of the production operating points between the second electrolysis unit and the third electrolysis unit is determined by calculating, for a plurality of production operating points of the respective electrolysis unit, a sum of the efficiencies of the second electrolysis unit and the third electrolysis units, in particular hydrogen production rates, based on the respective efficiency characteristics of the electrolysis R.409603. 11 -units is determined in order to determine the efficiency-optimized distribution of the production rates between the second electrolysis unit and the third electrolysis unit. According to one aspect, it is proposed that the efficiency-optimized distribution of the production operating points between the electrolysis module and the first electrolysis unit is determined by determining a sum of the efficiencies of the first electrolysis unit and the electrolysis module based on the module efficiency characteristic curve and the first efficiency characteristic curve for a plurality of respective production operating points for operating the electrolysis module and for operating the third electrolysis unit.According to one aspect, it is proposed that the module efficiency curve is additionally determined based on a load curve of a module auxiliary unit in order to take into account an electrical power of a module auxiliary unit on the efficiency of the production rate of the module for the control of the electrolysis plant.According to one aspect, it is proposed that the plant efficiency curve is additionally determined based on a load curve of a plant auxiliary unit in order to take into account an electrical power of a plant auxiliary unit on an efficiency of the hydrogen generation of the electrolysis plant for the control of the electrolysis plant.According to one aspect, it is proposed that the efficiency of the electrolysis unit and / or the electrolysis module and / or the electrolysis plant is related to an efficiency of an electrolysis production rate per electrical power used; and / or is related to an efficiency of the electrolysis production rate per standardized operating costs in electrolysis production (LCO); and / or is related to an efficiency of the electrolysis production rate per standardized operating costs and capital employed in electrolysis production (LCOH).According to one aspect, it is proposed that the respective production operating point for the first, second, and / or third electrolysis unit is determined by: determining the production operating point of the electrolysis module and / or the production operating point of the first electrolysis unit based on the efficiency-optimized distribution of the production operating points between the electrolysis module and the first electrolysis unit and the production operating point of the electrolysis system; and R.409603 -. 12 -Determining the production operating point of the second electrolysis unit and the production operating point of the third electrolysis unit based on the efficiency-optimized distribution of the production operating point between the second electrolysis unit and the third electrolysis unit and the production operating point of the electrolysis module. A control unit for an electrolysis system with a computing unit and a first interface and / or a second interface is proposed. The first interface is configured for electrically coupling the control unit to a first electrolysis unit and / or a second electrolysis unit and / or a third electrolysis unit. Alternatively or additionally, the second interface is configured for electrically coupling the control unit to a module auxiliary unit and / or a system auxiliary unit.The control unit is configured to carry out one of the methods described above. In other words, the control unit can be configured to determine an efficiency-optimized distribution of production rates between electrolysis units in order to determine respective production operating points for the electrolysis units. Embodiments Embodiments of the invention are presented with reference to Figures 1 to 6 and explained in more detail below. They show: Figure 1 shows a sketch of an electrolysis plant; Figure 2 shows a diagram with three unit efficiency curves; Figure 3 shows an efficiency-optimized production share per electrolysis unit in an electrolysis module; Figure 4 shows a diagram with a module efficiency curve; Figure 5 outlines a flowchart for determining a plant efficiency curve; and R.409603 -. 13 -Figure 6 outlines a flowchart for determining a production operating point for the electrolysis units. Figure 1 schematically outlines a plurality of electrolysis plants 150 to 160, each of which may have a plurality of electrolysis clusters 130 to 140, wherein each electrolysis cluster 130 to 140 may contain a plurality of electrolysis modules 110 to 120. The respective electrolysis module 110 to 120 may have a plurality of electrolysis units 114 to 116. This means that the electrolysis units of the electrolysis plants 150 to 160 may be combined into units or levels of electrolysis modules, electrolysis clusters, and electrolysis plants. The electrolysis plants may be spatially distributed geographically.An electrolysis module 110 to 120 can comprise a plurality of electrolysis units, each electrically coupled to power electronics to operate the respective electrolysis unit independently at a production operating point. The individual electrolysis units 114 to 116 can comprise a plurality of electrolysis stacks operated by the respective power electronics 113, wherein the electrolysis stacks are, for example, serially coupled to the power electronics 113. The respective electrolysis module 110 to 120 can comprise a control unit 112 for operating the electrolysis module 114 to 116. The electrolysis units 114 to 116 of an electrolysis module 110 to 120 may have auxiliary units 117 which may be operated jointly for at least parts of the plurality of electrolysis units 114 to 116 of the electrolysis module.Such auxiliary units 117 can be, for example, pumps, gas separators, gas dryers, or water treatment units. The plurality of electrolysis modules 110 to 120 of a respective electrolysis cluster 130 to 140 can be operated by means of a cluster control unit 132 and have auxiliary units 134 that can be operated jointly for at least some of the electrolysis modules 110 to 120. Such auxiliary units 134 can be, for example, pumps, gas separators and / or gas dryers and / or water treatment units. The respective electrolysis system 150 to 160 can have a plurality of electrolysis clusters 130 to 140 and can be controlled by means of a system control unit R.409603 -. 14 -152, 162. The respective electrolysis plant 150 to 160 can each have auxiliary units 154 with which at least some of the electrolysis clusters 130 to 140 can be operated jointly. A plurality of electrolysis plants can exchange data by means of a server 170, which is configured, for example, to coordinate the production of the electrolysis plants. Figure 2 shows three unit efficiency curves 210-230 in a diagram 200, each of which can be assigned to one of the electrolysis units 114 to 116 and can belong to one of the electrolysis modules 110 to 120. The respective unit efficiency curves 210-230 can each characterize an electrolysis unit 114 to 116 with respect to an efficiency of electrolytic production, for example of hydrogen, by means of the respective electrolysis unit 114 to 116.If a plurality of electrolysis units can be operated at different operating points and have different operating characteristics, a load distribution can be found as a function of a production operating point that maximizes a parameter to be optimized, such as overall efficiency. The load distribution can be determined such that the sum of the production rates (production operating points) of the plurality of electrolysis units results in a desired overall production rate of a module formed with the plurality of electrolysis units. Such an optimized load distribution is shown as an example in Figure 3. With the optimized load distribution, an efficiency characteristic curve of the module can be determined as a function of a production operating point, as shown in Figure 4.The determination of an operating characteristic of an electrolysis unit can be carried out by means of a control unit, in particular at the lowest level of a grouping of electrolysis units, such as by means of a module control unit 112 in Figure 1. For the determination, for example, a determined or specified IV characteristic (current-voltage characteristic) of the electrolysis stacks, the efficiency of the power electronics for operating the electrolysis stacks, the required cooling capacity, the Faraday efficiency, H2 diffusion, and operating pressures can be taken into account. R.409603 -. 15 -During operation, the control unit can continuously determine an operating characteristic to be optimized, for example, an efficiency curve for a plurality of electrolysis units, whereby data from further calculations and models, such as pumping and cooling capacity, aging models of the respective stack, energy for gas drying, etc., can also be incorporated. According to one aspect, Figure 3 shows three load-share curves 322, 324, 326, for example, of respective electrolysis units 114 to 116 of an electrolysis module in a diagram 320. In the diagram 320, a share of a production rate, in particular of hydrogen, of a respective electrolysis unit is plotted against the respective production operating point of the electrolysis module. This means that the load-share curves 322, 324, 326 result from an efficiency-optimized distribution of the production rates between the three electrolysis units of the electrolysis module.The respective electrolysis units are configured to be operated at different production operating points using respective power electronics and can have different operating characteristics, which can be characterized by the efficiency curves 210, 220, 230 shown in Figure 3. A respective production operating point of the electrolysis module, i.e., a production rate of the electrolysis module, is plotted on the x-axis of diagram 320, which corresponds to a sum of the production rates of the three electrolysis units. The fraction of a production rate of the respective electrolysis unit is plotted on the y-axis with the respective curve profile 322, 324, 326.This respective course of curves 322, 324, and 326 results from an efficiency-optimized distribution of the production rate between the three electrolysis units in order to maximize the efficiency of the electrolysis module's production rate at each production operating point of the electrolysis module. It can be seen that at a low module production rate, corresponding to the efficiency-optimized distribution, only one electrolysis unit is operated with curve 322 (circle symbol). At a higher electrolysis module production rate, it can be concluded from the course of curve 324 that another electrolysis unit is supporting the production rate. At an even higher module production rate, the course of curve 326 indicates further support of the production rate by the third electrolysis unit.At the module's maximum production rate, all three electrolysis units contribute equally to the production rate, particularly of hydrogen. R.409603 -. 16 -Figure 4 schematically outlines an example of a module efficiency characteristic curve, where the module efficiency characteristic curve can be based on the efficiency-optimized distribution of production rates between the three electrolysis units presented above. The module efficiency characteristic curve can be used to characterize the electrolysis module in a model, corresponding to the unit efficiency characteristic curve for the respective electrolysis unit. For a plurality of electrolysis modules of an electrolysis cluster, the respective module efficiency characteristics can be used to determine an efficiency-optimized distribution of production rates between the plurality of electrolysis modules, as described for the efficiency-optimized distribution of the production rates of the electrolysis units. To determine a cluster efficiency characteristic curve, it may be sufficient to use a control unit of the electrolysis cluster, i.e.to transfer the module efficiency curves of the electrolysis modules to a cluster level. The determined or determined unit efficiency curves of the electrolysis units of the electrolysis stack do not need to be transferred to the control unit of the electrolysis cluster in order to determine an efficiency-optimized distribution of production rates in the next higher grouping of electrolysis units, here the cluster level. The respective efficiency curves can thus represent a sufficient description for an efficiency-optimized distribution of production rates in the lower grouping of electrolysis units. In particular, it is not necessary to transfer the efficiency-optimized distribution itself to the next higher grouping of electrolysis units.In other words, the control unit at the cluster level can repeat the previously described process steps accordingly by using the module efficiency curves of the modules to determine an efficiency-optimized distribution for respective production operating points and / or production rates according to a load distribution among the electrolysis modules and to determine a cluster efficiency curve for the electrolysis cluster. The cluster efficiency curves of the electrolysis clusters can be forwarded to a control unit at the plant level, and so on. This process can be repeated analogously with any number of groupings and corresponding levels. R.409603 -. 17 -In other words, the method can be used to implement an efficiency-optimized distribution for respective production operating points or load distributions across groups (unit, module, cluster, plant, or multiple plants) or levels using the respective efficiency curves. If a quantity of hydrogen to be produced is specified as the plant's production operating point, or a target value, for example, at the plant level, a distribution to a lower level can be determined at each level. This means that at a plant level, a load distribution can be determined among the clusters, at the cluster level, a load distribution among the modules, and then, finally, within a module, a load distribution among individual electrolysis units.This allows the determination of an optimal load distribution suitable for a current production operating point to be carried out decentrally at the respective levels, without a control unit at the highest level requiring information about the respective efficiency-optimized distributions. Figure 5 schematically outlines a flowchart 500 for determining a cluster efficiency characteristic curve 546 for two electrolysis modules, wherein each electrolysis module has two electrolysis units. A distribution of the individual production rates of the respective electrolysis units can be determined in an efficiency-optimized manner between the two electrolysis units and / or the two electrolysis modules. The starting point is the four unit efficiency characteristic curves of the respective electrolysis unit, as shown in diagram 510, corresponding to the diagram 200 described above in Figure 2.The efficiency-optimized distribution of production rates described above is carried out in one step for each electrolysis module using two of the four unit efficiency curves, corresponding to diagrams 522 and 532 of diagram 510. The respective result of the efficiency-optimized distribution of the production rates of the respective modules is shown in diagrams 524 and 534. The determination of this efficiency-optimized distribution corresponds to the description in Figure 3. Based on the respective efficiency-optimized distribution of the respective electrolysis modules, a module efficiency curve 526 and 536 can be determined. The starting point for determining the cluster efficiency curve is the module efficiency curves 526 and 536, as shown in diagram 542. Based on R.409603. 18 -Based on the two module efficiency curves 526 and 536, an efficiency-optimized distribution of the production rates among the respective electrolysis modules can be determined, as shown in diagram 544. The cluster efficiency curve 546 can be determined using the efficiency-optimized distribution of the production rates among the respective electrolysis modules, in accordance with the description for Figure 4. Figure 6 schematically outlines a flow chart 600 for determining the respective production operating point of the respective electrolysis units 633, 635, 637, 639 of the electrolysis system 610. The starting point for the determination can be a production operating point of the electrolysis system 610, which is shown with a circle in diagram 612, or a production rate, in particular of hydrogen, for the electrolysis system.The respective production operating points of clusters 622 and 624 can be determined based on the efficiency-optimized distribution 614 of the production rate for clusters 622, 624 of cluster level 620 of electrolysis plant 610. For the production rate of electrolysis cluster 622, the proportion of the efficiency-optimized distribution 614 at the production operating point of the electrolysis plant can be read in the form of an open diamond. For the production rate of the electrolysis cluster 624, the proportion of efficiency optimized in distribution 614 at the production operating point of the electrolysis plant (open circle) can be read in the form of an open triangle. For the module level 630 with the modules 632, 634, 636, and 638, the production operating points for the modules 632, 634 can be determined based on the efficiency-optimized distribution of the production rate 622.For this purpose, the share for module 632 at the production operating point of electrolysis cluster 622 (open diamond) can be read and determined in the form of a closed square. The share for module 634 can be read and determined at the production operating point of the electrolysis cluster (open diamond) in the form of a closed triangle. The share for module 636 at the production operating point of electrolysis cluster 624 (open triangle) can be read and determined in the form of a closed inverted triangle. The share for module 638 can be read and determined at the production operating point of the electrolysis cluster (open triangle) in the form of a closed diamond. R.409603 -. 19 -The production operating points for the electrolysis units 632, 634, 636, and 638 can be determined according to the efficiency-optimized distributions of the production rate of the respectively assigned modules, analogously to the method described above. In other words, Figure 6 describes a determination of a load distribution of a production operating point of the electrolysis plant across multiple levels to the individual electrolysis units, each of which has at least one electrolysis stack. Based on the plant efficiency curve, the corresponding production operating points for the next lower level can be determined. In the corresponding next lower level, further production operating points can then be determined based on the efficiency-optimized distribution of the production rates.The determination of the corresponding efficiency curves and the corresponding efficiency-optimized distribution of the production rates (load distribution maps) can be carried out continuously during operation of the electrolysis plant or at certain discrete time intervals. In particular, the determination of an efficiency-optimized distribution of the production rates can be carried out when the respective efficiency curve changes, for example, due to aging and / or technical changes to a respective sub-unit of the electrolysis plant, or load distribution maps. Furthermore, the determination of an efficiency-optimized distribution or a load distribution map can be carried out when electrolysis units are no longer available, e.g., due to failure and / or maintenance, or when the plant is expanded with new electrolysis units. Furthermore, the determination of an efficiency-optimized distribution orof the load distribution map when changing operating parameters that affect the efficiency to be optimized, e.g., changing the anode pressure, cathode pressure, and / or operating temperature, etc. If an electrolysis module has a large number of electrolysis units (>= 3 electrolysis units), several electrolysis units within a module can be copied to smaller (virtual) units using the method described above, and group efficiency curves and efficiency-optimized distributions of the R.409603 can be created for these smaller groups (>= 2 stacks per group). 20 -Production rates of the group are determined. This may increase the storage requirements for the determination, since a large number of corresponding efficiency curves and / or efficiency-optimized production rate distributions must be stored; however, the complexity of determining the efficiency-optimized production rate distribution can be reduced. The same procedure can also be carried out for electrolysis clusters with a large number of electrolysis modules or for electrolysis systems with many electrolysis clusters. The description in Figure 5 can also be interpreted as a single electrolysis module with four electrolysis units, each with two (virtual) groups of two electrolysis units, in order to simplify the determination of the efficiency-optimized distribution of the production rates across the four electrolysis units.In other words, the described method can be implemented starting from a single control unit for the operation of a plurality of electrolysis units by virtually grouping the electrolysis units / modules / clusters, etc., on a single control unit as described above, with the corresponding determinations and calculations being performed centrally on a single control unit. In such a case, however, only the complexity of the calculation can be reduced, since in this application of the method, all data must be collected and processed by the individual control unit.

Claims

R.409603 - 21 -Claims 1. A method for controlling an electrolysis plant (100) with an electrolysis module (110, 120) and a first electrolysis unit (114-116), wherein the electrolysis module (110, 120) has a second electrolysis unit (114-116) and a third electrolysis unit (114-116); comprising: providing a production operating point for the electrolysis plant (100); providing a respective unit efficiency characteristic curve (210, 220, 230) for each of the electrolysis units; determining a module efficiency characteristic curve using the second unit efficiency characteristic curve and the third unit efficiency characteristic curve, wherein the module efficiency characteristic curve is determined based on an efficiency-optimized distribution for respective production operating points of the second electrolysis unit and the third electrolysis unit;Determining a plant efficiency characteristic curve using the module efficiency characteristic curve and the first unit efficiency characteristic curve, based on an efficiency-optimized distribution for respective production operating points for the electrolysis module (110, 120) and the first electrolysis unit;and determining a corresponding production operating point for the first, second, and / or third electrolysis unit based on the plant efficiency characteristic curve and the production operating point for the electrolysis plant (100) for controlling the electrolysis plant (100).

2. Method according to claim 1, wherein the respective electrolysis unit has an electrolysis stack and a respective power electronics unit (113) for operating the electrolysis stack (114, 115, 116) with electrical power.

3. Method according to claim 1 or 2, wherein the efficiency characteristic curve (210, 220, 230) characterizes a dependence of an efficiency of electrolytic production on an electrolytic production rate of the respective electrolysis unit. R.409603 - 22 -4. The method according to any one of the preceding claims, wherein the efficiency-optimized distribution of the production operating points between the second electrolysis unit and the third electrolysis unit is determined by determining a sum of the efficiencies of the second electrolysis unit and the third electrolysis units based on the respective efficiency curves (210, 220, 230) for a plurality of respective production operating points of the respective electrolysis unit in order to determine the efficiency-optimized distribution of the production rates between the second electrolysis unit and the third electrolysis unit.5.Method according to one of the preceding claims, wherein the efficiency-optimized distribution of the production operating points between the electrolysis module (110, 120) and the first electrolysis unit is determined by determining a sum of the efficiencies of the first electrolysis unit and the electrolysis module based on the module efficiency characteristic curve and the first efficiency characteristic curve for a plurality of respective production operating points of the electrolysis module (110, 120) and the third electrolysis unit.

6. Method according to one of the preceding claims, wherein the module efficiency curve is additionally determined based on a load curve of a module auxiliary unit (134) in order to take into account an electrical power of the module auxiliary unit (134) on the efficiency of the electrolytic production of the electrolysis module (110, 120) for the control of the electrolysis plant (100).7.Method according to one of the preceding claims, wherein the plant efficiency curve is additionally determined based on a load curve of a plant auxiliary unit (154) in order to take into account an electrical power of the plant auxiliary unit (154) on an efficiency of the electrolytic production of the electrolysis plant (100) for the control of the electrolysis plant (100).

8. Method according to one of the preceding claims, wherein the efficiency of the electrolysis unit and / or of the electrolysis module (110, 120) and / or of the electrolysis plant (100) is related to an efficiency of an electrolysis production rate per electrical power used; and / or is related to an efficiency of the electrolysis production rate per standardized operating costs of the electrolysis production (LCO); and / or is related to an efficiency of the electrolysis production rate per standardized operating costs and capital used of the electrolysis production (LCOH). R.409603 - 23 -9. The method according to any one of the preceding claims, wherein the respective production operating point for the first, second, and / or third electrolysis unit is determined by: determining the production operating point of the electrolysis module (110, 120) and / or the production operating point of the first electrolysis unit based on the efficiency-optimized distribution of the production operating points of the electrolysis module (110, 120) and the first electrolysis unit and the production operating point of the electrolysis system; and determining the production operating point of the second electrolysis unit and the production operating point of the third electrolysis unit based on the efficiency-optimized distribution of the production operating points of the second electrolysis unit and the third electrolysis unit and the production operating point of the electrolysis module (110, 120).10.Control unit (170, 152, 162) for an electrolysis system, comprising: a computing unit; a first interface for electrically coupling the control unit to a first electrolysis unit; and / or a second electrolysis unit; and / or a third electrolysis unit; and / or a second interface for electrically coupling the control unit to a module auxiliary unit (134) and / or a system auxiliary unit (154); wherein the control unit (170, 152, 162) is configured to carry out one of the methods according to claims 1 to 9.

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