Method for demand-based closed-loop control of an electrochemical device

Abstract

This invention relates to a method for demand-based closed-loop control of an electrochemical device, the electrochemical device comprising multiple modules and a control unit, each module being individually controlled by the control unit and provided with a module-specific operating current so that each module generates a separate product stream. The product streams of the modules connected in parallel are merged to form the total product stream of the device. The method is characterized in that, when the start-up conditions are met, the control unit performs the following steps: recording the current total product stream demand 1; recording the current efficiency 2 of each module of the electrochemical device, the current efficiency depending on the ratio of the corresponding operating current to the product stream of each module; determining the operational-ready module 3; determining a module-specific target operating current for each operational-ready module within the allowable module-specific target operating current range based on the efficiency of each module and the current total product stream demand to ensure the current total product stream demand 4; and setting the operating current of each operational-ready module to the determined module-specific target operating current 5.

Description

Technical Field

[0001] The present invention relates to a method for demand-based closed-loop control of an electrochemical device comprising multiple modules and a control unit, each module being individually controlled by the control unit and provided with a module-specific operating current so that each module generates a separate product stream, and the product streams of the modules connected in parallel are merged to form the total product stream of the device. Background Technology

[0002] Chemical equipment accounts for a large portion of the overall energy demand of industry, and therefore there is a clear interest in reducing the energy demand of chemical equipment for both economic and ecological reasons.

[0003] An example of particularly energy-intensive equipment is electrolysis equipment, such as water electrolysis or chlor-alkali electrolysis. At the heart of such equipment are cells connected in series, forming modules—also known as stacks. This type of structure is also used in fuel cells or battery technology. In typical large-scale chemical plants, numerous such modules operate in parallel to generate the desired total product stream, such as a material flow or current, i.e., to perform demand-based closed-loop control of the electrochemical equipment. If the total product stream of the equipment is entirely met by renewable energy, the equipment needs to be sufficiently flexible. High flexibility ensures that the wide variation in electricity provided by renewable energy can be converted into the total product stream as comprehensively and quickly as possible. As a positive effect, such flexible equipment can also be used to buffer power spikes caused by strong winds or intense solar radiation in an efficient and practical manner to maintain grid stability. In this respect, such equipment must be particularly energy-efficient and able to respond as flexibly as possible.

[0004] Document EP2350352B1 discloses a power transmission system for producing hydrogen from wind power through electrolysis and a method for controlling the distribution of electrical energy from a wind farm to multiple electrolysis modules for hydrogen production. The control system is designed to make the module utilization rate as close as possible to the level of electrical energy provided by the wind farm—which is particularly problematic when wind intensity fluctuates significantly—thus using the highest possible proportion of renewable energy for hydrogen production. To this end, the operating current of each module is selected based on the available DC power generated by the wind farm, so as to enable the highest possible proportion of wind energy to be put into hydrogen production.

[0005] The drawback of such devices is that they operate far from their optimal energy efficiency operating point, thus increasing the overall power consumption of such existing devices, which is neither economical nor environmentally friendly. In particular, in existing technologies for known systems or closed-loop control of such systems, the individual lifespan characteristics and operating modes of each module have a considerable impact on the efficiency of the entire device, and thus on its overall power consumption, yet these factors are often overlooked.

[0006] US 2019 / 0127867 A1 and US 2018 / 0291516 A1 each describe an electrolysis system comprising: a generator that outputs a first DC power; a plurality of converters, each converter converting the first DC power into a second DC power according to a target duty cycle and outputting voltage and current information regarding the second DC power; a plurality of electrolytic cells; a control circuit; and a selection circuit. Each electrolytic cell receives the second DC current power output by its respective assigned converter. The control circuit outputs control information, by which the first DC power is approximated to a maximum power level based on the voltage and current values ​​of the first DC power. The selection circuit, based on the control information and the voltage and current information, outputs a target duty cycle and a selection signal regarding whether to select each of the plurality of electrolytic cells and each of the plurality of converters. Summary of the Invention

[0007] In this regard, the object of the present invention is to propose a method for demand-based closed-loop control of electrochemical devices, characterized by minimal total power consumption, the most economical and eco-friendly operation, and high flexibility to cope with widely fluctuating total product flow demands.

[0008] This objective is achieved through the general method mentioned at the beginning, characterized in that, when the startup conditions are met, the control unit executes the following steps:

[0009] - Record the current total production flow requirements;

[0010] - Record the current efficiency of each module of the electrochemical device, which depends on the ratio of the corresponding operating current of each module to the product flow.

[0011] - Determine if the module is ready for operation;

[0012] -Based on the efficiency of each module and the current total product flow requirement, determine the module-specific target operating current for each operational-ready module within the allowable module-specific target operating current range to ensure the current total product flow requirement.

[0013] - Set the operating current of each operational-ready module to the determined module-specific target operating current.

[0014] The modules discussed in the context of this invention are characterized by their ability to be characterized by their efficiency. Such modules can be, for example, electrolytic modules, whose current-voltage characteristics represent a range of different operating points for the module. Furthermore, the aging process of each module is also reflected in the current-voltage characteristics, as older and therefore less efficient modules require higher voltages to provide the same current or product flow.

[0015] The fundamental feature of the method according to the invention is that the chemical apparatus subject to demand-based closed-loop control includes, in addition to individual modules, a control unit designed to individually activate each module. This activation specifically involves the control unit providing a module-specific operating current to each module. The apparatus is designed such that the product streams of the individual modules within the apparatus are combined into a total product stream.

[0016] The method according to the invention is characterized in that: if the start-up conditions are met, the control unit performs the following steps.

[0017] The current total product flow requirement is recorded. This is necessary in the context of chemical equipment meeting the total product flow requirement.

[0018] Furthermore, the efficiency of each module is recorded. This demonstrates a necessary step in the method according to the invention for enabling closed-loop control of the chemical equipment as efficiently as possible. Module-specific efficiency depends on the ratio of the module's module-specific operating current to the corresponding generated product stream. Module efficiency is not constant but depends, for example, on module aging or also on the operating temperature.

[0019] Furthermore, as part of the method according to the invention, the available modules of the equipment are recorded. Specifically, only operationally ready modules may be considered: defective or under maintenance modules cannot contribute to the total product flow demand and are therefore ignored; thus, if possible, the missing contribution of these modules must be compensated by operationally ready modules. Non-operationally ready modules are assigned essentially zero module-specific target operating currents, and thus such modules are effectively shut down. According to the invention, it can be specified that by identifying modules, not only the module itself but also the total product flow can be determined. This information is valuable for performing closed-loop control of the equipment, for example, for buffering excessive energy (especially renewable energy) supply. As part of a preferred improvement, it can be specified that individual modules will operate at, for example, 110% overload for a period of time in order to make a particularly high contribution to grid stability.

[0020] In another step of the method according to the invention, a module-specific target operating current is determined to meet the total product flow requirements. This is determined in a module-specific manner—in other words, the method specifies that a separate target operating current is allocated to each module. The target operating current is selected from a permissible range of module-specific target operating currents. The lower limit of this range is given, for example, by the target operating current required to bring the module into full operation. The upper limit of the target operating current is given, for example, by the current required to operate the module at its maximum utilization limit without causing excessive damage (i.e., exceeding normal aging effects).

[0021] However, the module-specific target operating current is not determined solely on maintaining the allowable range of the target operating current and meeting the total product flow requirement. Instead, the module-specific target operating current is determined based on the efficiency of each module and the current total product flow requirement. While the dependence of the target operating current on the total product flow requirement is solely due to the direct dependency between providing the specific target operating current to each module and the generated total product flow—therefore the target operating current must always be determined based on the total product flow requirement—the dependence of the target operating current of each module on the efficiency of that module indicates a significant dependence. This consideration of the efficiency of each module in determining the target operating current allows for the operation of the equipment in an energy-saving mode in a particularly advantageous manner.

[0022] After the operating current of each module has been set to the specific target operating current of that module in order to meet the total product flow requirements in an energy-saving manner, the method according to the invention can, for example, restart from scratch by monitoring the existence of new startup conditions for the equipment through the control unit.

[0023] Therefore, the method according to the invention not only enables energy-efficient operation, but also makes a significant contribution to grid stability by enabling demand-based closed-loop control of electrochemical equipment to meet total product flow demand, since voltage and / or current peaks caused by excess energy (especially energy from renewable energy sources) can be buffered by selecting the total product flow or total product flow demand generated by the method according to the invention in a manner that uses a specific amount of electrical energy (specifically, the energy to be buffered) for this purpose.

[0024] In an improvement to the method according to the invention, to determine a module-specific target operating current, individual modules are sorted according to their current efficiency levels and then increased or decreased according to the resulting order until the current total product flow requirement is met. Therefore, when the total product flow requirement increases, a higher target operating current is provided for the most efficient module, or when the total product flow requirement decreases, a lower target operating current is provided for the least efficient module. This ensures that currently particularly efficient modules operate at high utilization or target operating current, and inefficient modules operate at low utilization or target operating current.

[0025] Ranking or sorting modules based on their efficiency to orderly increase or decrease specific target operating currents can be very time-consuming, thus compromising flexibility in meeting widely fluctuating total product flow demands. This problem can be solved by a preferred improvement according to the invention, using an algorithm scaled according to n*log(n) to minimize the time required to sort n modules. For example, the so-called Quicksort algorithm can be used as the sorting algorithm, which scales as described above and allows the method according to the invention to react quickly enough to changes in total product flow demands, even when applied to devices with a large number of modules.

[0026] According to the present invention, in order to determine the module-specific target operating current (I m Each module (M) is sorted according to its specific lifecycle parameters and increased or decreased according to the resulting order until the current value of the total product flow requirement (B) is met. The lifecycle parameters are calculated based on the current efficiency of each module and a correction term that takes into account the maintenance costs of the electrochemical equipment. By considering maintenance costs, the operation of the equipment is improved in terms of total operating costs (total cost of ownership). The correction term introduces a deviation from the equipment's current most efficient operating point, which allows for uneven aging of modules in terms of efficiency. The maintenance costs of the equipment depend on the equipment's operating mode. For example, maintenance costs can be reduced by simply inspecting the equipment at specified maintenance intervals and avoiding downtime or shutdown. To reduce maintenance costs, it is therefore beneficial to periodically maintain or replace a portion of the modules, such as 10% to 25%, while the equipment is still running after the maintenance interval has expired. For this purpose, it is beneficial if the module to be replaced is more aged than the other modules in the equipment and therefore has lower efficiency. After maintenance or replacement, it is also beneficial to ensure that not only the most recently maintained module is used for partial load operation due to its higher efficiency. These advantages are achieved through a correction term that takes into account the equipment's maintenance costs.

[0027] The calibration term is preferably determined based on the total charge flowing through the corresponding module during its previous lifespan and / or based on the module's service life and / or its location within the electrochemical device. Different aging processes are active within the module's electrochemical cell, requiring maintenance or replacement at some point in time. One set of aging effects depends primarily on the total charge flowing through the module. This includes, for example, a decrease in the ionic conductivity of the separator and the quality of the electrode coating. Other aging effects, such as corrosion effects, depend primarily on the module's service life. By considering the module's location within the electrochemical device, the degree to which modules to be maintained or replaced are spatially concentrated, for example, within blocks or sections of the device. This further reduces maintenance costs.

[0028] The module-specific target operating current for the operational-ready modules used to meet the total product flow requirements is preferably determined iteratively using a predictive calculation of the achievable efficiency for each individual module and assuming a gradual change in the corresponding module-specific operating current. Iterative methods are well-suited for optimizing complex equipment under varying operating conditions because they allow for rapid and efficient adaptation to changing conditions from the current operating state.

[0029] The iteration is preferably based on a greedy algorithm, that is, an algorithm that progressively selects the next state in the sequence that ensures the efficiency of the device changes optimally at that selection.

[0030] The iteration is preferably performed with an adaptive step size, which is selected based on the current deviation between the total product flow and the total product flow demand. This allows the final state achieved through iteration to be improved from the theoretical optimum.

[0031] In a preferred improvement, when determining the module-specific target operating current, the efficiency of each module is weighted by a weighting factor that depends on the ratio of the module-specific operating current to the sum of the module-specific operating currents of all modules. By taking into account the impact of individual module efficiency variations on overall efficiency, this allows the chemical equipment to operate closer to its optimal energy efficiency.

[0032] In the actual operation of chemical equipment, based on the improvements to the method according to the invention, the focus is not only on good energy efficiency, but also on the ability to handle wide fluctuations in total product flow demand sufficiently quickly; therefore, it is about the ability to adapt the equipment utilization rate to widely changing demands with sufficient flexibility. This is achieved, as part of the improvements to the method according to the invention, by the control unit allocating a minimum operating current corresponding to the base load to all modules. Furthermore, the minimum operating current ensures that all modules, such as those in the electrolysis unit, are kept at the lowest possible temperature, which enables all modules to have a certain minimum efficiency. Otherwise, cold electrolysis modules, due to their low efficiency, might not be considered by the control unit, potentially leading to a failure to meet the total product flow demand.

[0033] In a preferred embodiment of the method according to the invention, the control unit is a device control unit. For safety reasons alone, almost all chemical equipment requires such a device control unit, meaning that no additional control hardware is needed to execute the method according to the invention. In addition to the aforementioned advantages regarding energy-efficient operation of the equipment, this makes the use of the method according to the invention particularly attractive in a wide range of chemical equipment.

[0034] The method steps according to the invention are performed only if a start-up condition is met. This start-up condition may be the fact that the currently generated product flow deviates from the total product flow demand by a predetermined amount. This start-up condition will be able to address the fluctuating efficiency of modules (which leads to changes in the total product flow) and the changing total product flow demand. The commissioning or shutdown of individual modules can also be considered a possible start-up condition. For example, if individual modules are suspended for maintenance purposes, these modules will no longer be available to meet the total product flow demand. By providing the above-described start-up condition, the method according to the invention treats modules that have been suspended as inoperable, so that the contributions of the modules that have been suspended are fulfilled by another module. This also applies to other modules that have been commissioned, for example, when the system is equipped with a new module.

[0035] In another embodiment of the method according to the invention, the temperature of each module is determined by the control unit to be above or below a predetermined maximum value, which is used as a start-up condition. This means that the method according to the invention can prevent the modules from overheating, or prevent the modules from operating at temperatures lower than the desired operating temperature and failing to provide optimal possible efficiency. The expiration of a specified time period can also be provided as a particularly simple start-up condition.

[0036] In a particularly preferred improvement of the method according to the invention, the electrochemical device is a water electrolysis device. Since energy efficiency plays a particularly important role in water electrolysis devices, and different modules can sometimes exhibit significant efficiency differences and fluctuations, the advantages of the method according to the invention can be particularly evident when applied to water electrolysis devices.

[0037] As part of another embodiment of the method according to the invention, the efficiency of individual modules can be determined based on current-voltage characteristics. This can be the case, for example, for an electrolysis module or a battery. The higher the efficiency of the electrolysis module or battery module, the lower the operating voltage at a specific target operating current. For example, module aging manifests as a shift in the current-voltage characteristic along the ordinate towards higher voltages.

[0038] In a preferred improvement of the method according to the invention, the efficiency of each module is stored in the control unit as a record of module aging. This has the advantage that module aging is continuously recorded, and the procurement of new modules or the refurbishment of old modules can be initiated in a timely manner. This effectively prevents module failure and inefficient operation due to excessive aging. Furthermore, this storage function makes it particularly simple to assign the latest stored efficiency value to cold and therefore inefficient modules, thus providing a more realistic value for module efficiency by taking into account the temperature dependence of the electrochemical reaction compared to using the efficiency of cold modules.

[0039] Preferably, the measured efficiency in the control unit is added as data points to a module-specific model to predict the current-voltage characteristics of the corresponding module. As the module ages, the addition of data points updates the model. The model used to predict the current current-voltage characteristics allows for the prediction and consideration of the efficiency of each module at any operating point.

[0040] In another preferred embodiment of the method according to the invention, specific modules are powered with a predetermined balanced operating current for a predetermined time to improve the efficiency of the operation-ready modules, and this predetermined balanced operating current is taken into account when determining the specific target operating current of the modules. This balanced operating current allows for a more accurate determination of the individual efficiency of each module, further improving the accuracy of the method.

[0041] Preferred improvements to the present invention will become apparent from the following description and figures. Attached Figure Description

[0042] The invention is described in more detail below with reference to exemplary embodiments and the accompanying drawings. In the drawings:

[0043] Figure 1 : A diagram illustrating the method steps according to the present invention;

[0044] Figure 2 The illustration shows the method steps of a preferred improved method according to the present invention, wherein modules are ordered according to their current efficiency and are increased or decreased according to the resulting order;

[0045] Figure 3 The illustration shows the method steps of an alternative preferred improvement method according to the invention, wherein the determined module-specific target operating current is modified by multiplying by a weighting factor; and

[0046] Figure 4 The diagram illustrates a water electrolysis device based on the method according to the present invention, which includes a control unit and a plurality of parallel-connected modules, the plurality of modules being formed by electrolytic cells connected in series.

[0047] In each drawing, the same parts are always represented by the same reference numerals and are therefore usually named or mentioned only once in each case. Detailed Implementation

[0048] The method for demand-based closed-loop control of an electrochemical device according to the present invention can be applied to a device comprising multiple modules and a control unit. Each module is individually controlled by the control unit and is provided with a module-specific operating current. Product streams are generated by providing operating currents to each module. For example, in the case of chlor-alkali electrolysis, this product stream may contain chlorine and caustic soda, or in the case of water electrolysis, this product stream may contain hydrogen. If the device is in the form of a battery, the product stream is simply current. In any case, the product streams generated by the individual modules are combined to form a total stream.

[0049] exist Figure 1 In this diagram, the necessary method steps executed by the control unit are schematically visualized. If the startup conditions are met, the method steps include:

[0050] Record the current total production flow demand (1). The current total production flow demand may change significantly. The total production flow demand may fluctuate greatly, especially in the case of batteries.

[0051] Once the total product flow requirement is recorded, the efficiency of each module of the electrochemical device is recorded (2). This efficiency depends on the ratio of the corresponding operating current of each module to the product flow.

[0052] In a further step, modules (3) are identified, specifically which modules are actually available. Optionally, operationally ready modules may also be identified: non-operationally ready modules are, for example, defective modules or modules that are out of service for maintenance purposes. Non-operationally ready modules may also be assigned a fixed operating current of essentially zero, for example, during a fault or maintenance activity.

[0053] The following method steps according to the invention involve determining a module-specific target operating current for each operational-ready module to meet the current total product flow requirement. The module-specific target operating current is determined from an allowable range of module-specific target operating currents, which, for example, can prevent damage to the module due to selecting an excessively high operating current. Alternatively, the module-specific target operating current is determined based on the module's efficiency and the current total product flow requirement (4). Taking the module's efficiency into account is an important step in the method according to the invention, as it enables the chemical device to operate near the point of minimum total power consumption.

[0054] After determining the module-specific target operating current, the operating current of each operational ready module is set to the determined module-specific target operating current (5).

[0055] Preferred improvements to the method according to the invention are as follows: Figure 2The diagram illustrates this improvement. The improvement is characterized in that, to determine a specific target operating current for a module, each module is sorted according to its current efficiency and then increased or decreased according to the resulting order until the current total product flow requirement is met (3a). In this way, when the total product flow requirement increases, a higher operating current can be allocated to efficient modules, or when the total product flow requirement decreases, a lower operating current can be allocated to inefficient modules, thereby reducing the power consumption of the device. Sort the modules according to efficiency so that they can subsequently be increased or decreased according to the resulting order. Since this sorting can involve a significant amount of computational work or time, the improvement to the method according to the invention specifies that, in order to sort the n modules by efficiency, an algorithm scaled according to n*log(n) is used, thus ensuring manageable computation time even for large devices with a large number of modules. For example, this could be a Quicksort algorithm.

[0056] According to the present invention—and also according to Figure 2 The method is illustrated in the diagram—to determine the module-specific target operating current in step (3a), each module is sorted according to module-specific lifetime parameters and increased or decreased according to the resulting order until the current total product flow requirement is met. The lifetime parameters are calculated based on the current efficiency of the module (M) and a correction term that takes into account the maintenance costs of the electrochemical device. The correction term is preferably determined based on the total charge flowing through the corresponding module during its previous lifetime and / or based on the service life of the corresponding module and / or based on the location of the corresponding module within the electrochemical device.

[0057] The module-specific target operating current (I) of the operation-ready module (M) used to meet the total product flow requirement (B) in the above method is... m The process is preferably determined iteratively using a predicted calculation of the achievable efficiency for each individual module (M) and assuming a gradual change in the specific operating current of the corresponding module. A greedy algorithm is particularly preferred for this iteration. The iteration is preferably performed with an adaptive step size, which is selected based on the current deviation between the total product flow and the total product flow demand (B).

[0058] When the specific target operating current (I) of the module is determined m When determining the module-specific target operating current (I0), the efficiency of module (M) is preferably weighted using a weighting factor that depends on the ratio of the module-specific operating current to the sum of the module-specific operating currents of all modules (M). This means that when determining the module-specific target operating current (I0), m When calculating the efficiency of a single module, the impact of its efficiency variation on the overall efficiency has already been considered.

[0059] Preferred alternative improvements to the method according to the invention are as follows: Figure 3As shown in the diagram. In this case, the determined module-specific target operating current is modified by multiplying it by a weighting factor that depends on the ratio of the module-specific operating current to the sum of the module-specific operating currents of all modules (4a). This brings the device's operating point closer to its optimal energy efficiency.

[0060] Figure 4 A schematic diagram of a water electrolysis device (E) according to the method of the present invention is shown. This device includes a control unit (C) and multiple modules (M) connected in parallel, each module (M) consisting of an electrolytic cell connected in parallel for producing hydrogen (H2). The control unit (C) records the total product flow demand (B) and the efficiency of each module (M), sorts the modules (M) according to their efficiency, and determines the operational readiness of each module (M) (indicated by a checkmark or cross). Then, the target operating current (I) of each module is determined. m The target operating current (I0) is determined and multiplied by a weighting factor to obtain the weighted target operating current (I0) for each module. m,g This brings the entire device closer to its maximum energy efficiency operating point. The control unit sets each operating current to a weighted target operating current (I0). m,g Then you can monitor whether new startup conditions appear in the system.

[0061] Reference Symbol List

[0062] 1. Record the current total production flow requirements.

[0063] 2. Record module efficiency

[0064] 3. Recognition Module

[0065] 3a Sort and change based on efficiency / lifecycle parameters

[0066] 4a Multiply the module-specific target operating current by the weighting factor.

[0067] 4. Determine the specific target operating current of the module.

[0068] 5. Set the specific target operating current of the module

[0069] B Total Product Flow Requirements

[0070] C Control Unit

[0071] E Water Electrolysis Equipment

[0072] M module

[0073] I m Target operating current of the module

[0074] I m,g The module's weighted target operating current

Claims

1. A method for demand-based closed-loop control of an electrochemical device, the electrochemical device comprising multiple modules (M) and a control unit (C), each module (M) being individually controlled by the control unit and provided with a module-specific operating current so that each module (M) generates a separate product stream, the product streams of the modules (M) connected in parallel being merged to form a total product stream of the device, wherein, When the startup conditions are met, the control unit (C) performs the following steps: - Record the current total production flow requirement (B) (1); - Record the current efficiency of each module (M) of the electrochemical device, the current efficiency depending on the ratio of the corresponding operating current of each module to the product flow (2). - Determine if the operation is ready (M) (3); -Based on the efficiency of each module (M) and the current total product flow requirement (B), the allowable module-specific target operating current (I) is determined. m Within the range of ) for each operation-ready module (M), a module-specific target operating current is determined to ensure the current total product flow requirement (B) (4), wherein, in order to determine the module-specific target operating current (I m Each module (M) is sorted according to its specific lifecycle parameters and is raised or lowered according to the resulting order until the current total product flow requirement (B) is met (3a). - setting the operating current of each operating ready module (M) to the determined module specific target operating current (I m )(5), The lifecycle parameter is calculated based on the current efficiency of each module and a correction term that takes into account the maintenance cost of the electrochemical device. The correction term produces a deviation from the current most efficient operating point of the electrochemical device, thereby allowing for uneven aging of the modules in terms of efficiency.

2. The method of claim 1, wherein, The correction term is determined based on the total charge flowing through the corresponding module during its previous lifespan and / or based on the service life of the corresponding module and / or based on the location of the corresponding module in the electrochemical device.

3. The method according to claim 1 or 2, characterized in that, the module-specific target working current (I m ) of each operating-ready module (M) for meeting the total product stream demand (B) is determined iteratively using a predictive calculation of the efficiency achievable for each individual module (M) and assuming a stepwise change of the respective module-specific working current.

4. The method of claim 3, wherein, The iteration is based on a greedy algorithm.

5. The method of claim 3, wherein, The iteration is performed using an adaptive step size, which is selected based on the current deviation between the total product flow and the total product flow demand (B).

6. The method of any one of claims 1 to 2, wherein, When determining the module-specific target operating current, the efficiency of each module (M) is weighted using a weighting factor (4a), which depends on the ratio of the corresponding module-specific operating current to the sum of the module-specific operating currents of all modules (M).

7. The method of any one of claims 1 to 2, wherein, All modules are assigned a minimum operating current corresponding to the base load by the control unit.

8. The method of any one of claims 1 to 2, wherein, The control unit is the equipment monitoring unit.

9. The method of any one of claims 1 to 2, wherein, The deviation between the currently generated product stream and the total product stream demand is a predetermined amount and is used as the start-up condition.

10. The method of any one of claims 1 to 2, wherein, The commissioning or shutdown of individual modules is used as the startup condition.

11. The method of any one of claims 1-2, wherein, The temperature of each module is determined by the control unit to be above or below a predetermined maximum value, which is used as the start-up condition.

12. The method of any one of claims 1 to 2, wherein, The electrochemical device is a water electrolysis device.

13. The method of any one of claims 1-2, wherein, The efficiency of each module is determined by its current-voltage characteristics.

14. The method of any one of claims 1 to 2, wherein, The efficiency of each module is stored in the control unit as a record of the aging of the corresponding module.

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