Method for operating a hydrogen production system

Abstract

The invention relates to a method for operating a hydrogen production system (150, 550, 650, 750, 1050) having at least one wind turbine (110, 510, 610, 710) for supplying at least one electrolyzer (114, 514, 614, 714, 1014) of the hydrogen production system (150, 550, 650, 750, 1050) with electrical power, comprising supplying the electrolyzer (114, 514, 614, 714, 1014) with a predefined holding voltage lower than a minimum operating voltage of the electrolyzer (114, 514, 614, 714, 1014) if the power providable by the wind turbine (110, 510, 610, 710) to the electrolyzer (114, 514, 614, 714, 1014) is lower than a predefined minimum electrolyzer operating power.

Description

[0001] 25. November 2024

[0002] Method for operating a hydrogen production system

[0003] The invention relates to a method for operating a hydrogen production system. In addition, the invention relates to a controller and a hydrogen production system.

[0004] In the present time, electrical power generation systems are increasingly used for the provision of electrical energy, in which generating of electrical energy is based on so- called renewable energy sources. Electric power generation systems generally have at least one power generation device, preferably a plurality of power generation devices.

[0005] More particularly, wind energy systems and wind farms, respectively, comprising at least one wind turbine (preferably a plurality of wind turbines) as an energy generation device are used more and more as electrical energy generation systems. In particular, a wind turbine is configured to convert the kinetic wind energy into electrical energy. Such wind farms are not only located at onshore sites, but increasingly also at offshore sites. There are many reasons for choosing an offshore site instead of an onshore site: for example, the available space onshore may be limited. In addition, it has been shown that the energy yield can be increased at offshore wind farms, for example. Offshore locations are usually characterized by relatively continuous wind conditions and high average wind speeds (compared to onshore sites), so that offshore wind farms are increasingly being built.

[0006] In prior art, an offshore wind farm may comprise a plurality of (stationary) offshore structures (i.e., no ships or the like), such as a plurality of offshore wind turbines and at least one offshore substation (also called converter station) by which an offshore wind farm can be electrically connected, for example, to an onshore substation or a further offshore substation. In particular, an offshore wind farm has an internal grid (e.g., comprising power cables respectively energy cables in the form of submarine power cables) configured to electrically connect at least two offshore structures of a wind farm. An onshore substation, in turn, may be connected to an external grid, such as public power grid respectively an electrical distribution network.

[0007] Furthermore, hydrogen production systems having at least one wind turbine respectively a wind farm with at least one wind turbine for supplying a hydrogen production plant of the hydrogen production system with electrical power are also known from prior art. A hydrogen production system comprises at least one electrolyzer. An electrolyzer is configured to produce respectively generate hydrogen by conducting a water electrolysis.

[0008] Hydrogen production systems and hydrogen producing wind farms, respectively, may utilize at least one wind turbine as a power supply. The at least one wind turbine is either grid-connected or decoupled from an external (public) electric grid. In the case of a grid-connected hydrogen wind turbine respectively farm, power is not drawn from the grid by the at least one electrolyzer. The at least one electrolyzer acts, in particular, as an electrical load for the at least one wind turbine.

[0009] In both cases however, electric power generated by the at least one wind turbine is fed to the at least one electrolyzer for the purpose of hydrogen production in a decentral, semi-central or central system.

[0010] A decentral system means that, in particular, an electrolyzer respectively an electrolyzer stack is electrically coupled to each wind turbine, and their operations alongside that of the wind turbine they are coupled to are independent of the other wind turbines in the wind farm. Semi-central or central system means, in particular, that all the output electrical energy respectively power produced by a plurality of wind turbines of a wind farm of the hydrogen production system is synchronized and paralleled to an electrical bus via a single string or multiple strings respectively, using an array network of medium or high voltage cables to an offshore substation or onshore substation.

[0011] HB / HB 240487WO

[0012] 25. November 2024 The at least one electrolyzer operated in such a hydrogen production system needs to efficiently and effectively produce hydrogen, in particular, without human supervision (in particular, at an offshore site). They may deploy a doubly-fed induction generator with partial converter, or alternatively, electrically-excited or permanent magnet synchronous generator with full power converter. The at least one electrolyzer may be a PEM (proton exchange membrane) electrolyzer.

[0013] One concern in the prior art is to extend the service life of the at least one electrolyzer of a hydrogen production system with at least one wind turbine. A particular problem of the prior art is the abnormal and accelerated degradation in the membrane electrodes of the at least one electrolyzer of such a hydrogen production system.

[0014] Document US 7 667 343 B2 discloses a hydrogen production system having an off-grid permanent magnet wind turbine generator wherein the coupling full power converter is controlled to stay in operable range for a longer time so that the hydrogen production of hydrogen production plant, in particular, the at least one electrolyzer, is similarly sustained for a longer time. This is achieved by extending the industrystandard pitch control system to cover a wider operational angular speed range and capture more energy. Further, according to US 7 667 343 B2 energy storage is also integrated in the system to assist in the startup of the system. Document US 7 667 343 B2 is focused on increasing the availability of electrical energy production and in turn, more hydrogen production.

[0015] In addition, in US 7 667 343 B2, a controller is described for the interfacing power converter of the electrolyzer to regulate voltage and current to keep to the operating limits of the electrolyzer for optimal hydrogen production. However, document US 7 667 343 B2 did not address the topic of degradations in the electrodes of interfacing electrolyzers. In addition, the controller of US 7 667 343 B2 for the current control scheme is integrated to the full power converter and its implementation for the electrolyzer is a reactive response to the rotational speed of the generator of the wind turbine.

[0016] HB / HB 240487WO

[0017] 25. November 2024 Degradation in the membrane electrodes of the at least one electrolyzer reduces the hydrogen yield. This issue is intensified by the fact that an electrolyzer can only be operated if the wind turbine can supply respectively generate at least a predefined minimum electrolyzer operating power for the electrolyzer. In particular, it has been found that an electrolyzer should only start operation at a minimum input power (i.e., the predefined minimum electrolyzer operating power) not lower than approximately 15 % of its nominal power rating. Otherwise, rapid, accelerated low power degradations will occur in the membrane electrodes. However, shutting down and restarting the electrolyzer takes a longtime (30 minutes or more) with the prior art. Hence, the hydrogen yield is significantly reduced and / or the degradation in the membrane electrodes is increased in the prior art.

[0018] Therefore, it is an object of the present invention to provide a possibility to reduce the drawbacks of the prior art and, in particular, to increase hydrogen yield of a hydrogen production system having at least one wind turbine and preferably the service life of the at least one electrolyzer at the same time.

[0019] The object is solved according to a first aspect of the invention by a (computer implemented) method according to claim 1 for operating a hydrogen production system having at least one wind turbine for supplying at least one electrolyzer of the hydrogen production system with electrical power, comprising: supplying (respectively driving) the electrolyzer with a predefined holding voltage lower than a minimum operating voltage of the electrolyzer if the power (currently) providable by the wind turbine to the electrolyzer is lower than a predefined minimum electrolyzer operating power.

[0020] A further aspect of the invention is a controller according to claim 16 for controlling a hydrogen production system having at least one wind turbine for supplying at least one electrolyzer of the hydrogen production system with electrical power, the controller is configured to control:

[0021] HB / HB 240487WO

[0022] 25. November 2024 supplying (respectively driving) the electrolyzer with a predefined holding voltage lower than a minimum operating voltage of the electrolyzer if the power (currently) providable by the wind turbine to the electrolyzer is lower than a predefined minimum electrolyzer operating power.

[0023] In contrast to the prior art, according to the present invention, by providing a method (and a controller) supplying the at least one electrolyzer with a predefined holding voltage if the power providable by the wind turbine to the electrolyzer is lower than a predefined minimum electrolyzer operating power a possibility is provided to reduce the drawbacks of the prior art and, in particular, to increase the hydrogen yield of the hydrogen production system having at least one wind turbine and preferably the service life of the at least one electrolyzer at the same time.

[0024] According to the invention a method for increasing the hydrogen yield and, in particular, mitigating the degradations in the membrane electrode assemblies of at least one electrolyzer is provided. The method can be executed by a controller according to the invention. The controller may be implemented in a data processing device comprising one or more processors and memory means. In particular, the at least one processor of the controller may be configured to execute the computer implemented method according to the invention.

[0025] The method according to the invention serves to operate, in particular, control respectively regulate at least the operation of the at least one electrolyzer, in particular, the power supply and voltage supply, respectively.

[0026] In particular, a hydrogen production system may be provided. A hydrogen production system comprises at least one electrolyzer. Preferably, the hydrogen production system may comprise at least one hydrogen production plant. A hydrogen production plant comprises the at least one electrolyzer. The at least one electrolyzer may be configured to produce respectively generate a fluid medium, in particular, in form of hydrogen and / or ammonia.

[0027] HB / HB 240487WO

[0028] 25. November 2024 The hydrogen production system, in particular, the hydrogen production plant, may comprise at least one hydrogen power supply for the at least one electrolyzer. Furthermore, the hydrogen production system may comprise at least one electrolyzer auxiliary device. The at least one electrolyzer auxiliary device may comprise a (hydrogen) processing module respectively (hydrogen) finishing module. The at least one processing module may be configured to process (wet) hydrogen produced by the at least one electrolyzer.

[0029] In the present case, wet hydrogen refers, in particular, to hydrogen saturated with water respectively a two-phase mixture of gaseous hydrogen and liquid water. In the present case, dry hydrogen refers, in particular, to hydrogen that is not saturated with water, i.e., whose dew temperature is (significantly) below the actual temperature at the pressure present. In other words, in particular, wet hydrogen gas can be produced by the at least one electrolyzer which, when cooled, becomes a gas-liquid mixture in the form of a water-hydrogen mixture. The gas respectively gaseous phase carries the liquid phase with it.

[0030] The at least one hydrogen processing module can comprise at least one hydrogen drying module. The hydrogen drying module can be configured to dry the produced wet hydrogen. Preferably, the hydrogen drying module (e.g., after separation of the liquid phase) can be an adsorption drying module (in particular, a TSA (temperature swing adsorption) module) and / or a refrigeration drying module. The adsorption drying module may be, in particular, configured to dry the wet hydrogen by adsorption using a (suitable) adsorber, in particular silica beads. The at least one hydrogen drying module can be configured to cool the wet hydrogen to a temperature of at least less than 5°C. It shall be understood that in variants of the invention, other hydrogen drying modules can be used alternatively or additionally.

[0031] Furthermore, the at least one hydrogen processing module can comprise a catalytic deoxo stage, in particular, for treating the wet hydrogen before drying as described

[0032] HB / HB 240487WO

[0033] 25. November 2024 above. Such a stage serves to remove oxygen (<0.5%). In variants of the invention, such treatment can also take place at a later stage, for example, at a hydrogen destination structure to which the treated hydrogen can be transported, for example, via a hydrogen pipeline network.

[0034] Preferably additionally, according to a further embodiment of the method according to the invention, the at least one (hydrogen) processing module may comprise at least one (hydrogen) compression module. The compression module may be configured to compress the processed fluid medium, in particular the dried hydrogen. The compression module may comprise at least one (hydrogen) compressor (in particular a (vertical) piston compressor). The compression module can be configured to compress the produced fluid medium, such as the dried hydrogen, to at least 50 barg (and for example at most 250 barg), preferably to essentially 70 barg.

[0035] Alternatively or additionally, the at least one (hydrogen) processing module may comprise at least one transforming module configured to transform the produced hydrogen to ammonia (e.g., via the Haber-Bosch-method or the like).

[0036] Furthermore, the at least one hydrogen production system may comprise, as a further or other electrolyzer auxiliary device, at least one water treatment module. The at least one water treatment module can be configured to treat water such that it can be used by the at least one electrolyzer of the hydrogen production system to produce the fluid medium, such as hydrogen. In particular, the water treatment module can treat seawater for the electrolysis process to be performed.

[0037] Preferably, the at least one water treatment module can be a seawater desalination module with membrane-based pressure filtration. Such a seawater desalination module can carry out reverse osmosis, ultrafiltration and / or electrodialysis (also known as electrodeionization (EDI)) to treat the water respectively to treat the seawater accordingly. Such treatment can be used to treat seawater, in particular, in

[0038] HB / HB 240487WO

[0039] 25. November 2024 an energy-efficient manner, which can be used for water electrolysis. The treated water can also be referred to as ultrapure water or "demin water".

[0040] Alternatively or additionally, the hydrogen production system may comprise, as a further or other electrolyzer auxiliary device, at least one inert gas generation module configured to generate an inert gas. For example, the inert gas generation module may comprise an inert gas storage tank, in particular, in the form of a pressurized inert gas storage tank configured to (temporarily) store the generated inert gas and in particular for conveying the inert gas through an inert gas pipeline network. Preferably, a nitrogen generation module can be provided as the inert gas generation module, wherein the nitrogen generation module can be configured to generate nitrogen from air, preferably by pressure swing adsorption. It shall be understood that other inert gas generation modules can also be provided alternatively or additionally in variants of the invention.

[0041] Further, it shall be understood that the at least one hydrogen production system may comprise less modules, further modules, or other modules. Preferably, the hydrogen production system may additionally comprise a water intake device and / or a water filtration module.

[0042] The hydrogen production system may comprise at least one wind turbine. As already described, the at least one wind turbine serves to supply at least the at least one electrolyzer, preferably the whole hydrogen production plant comprising the at least one electrolyzer, with electrical energy and power, respectively. In particular, at least the at least one electrolyzer and the at least one electrolyzer auxiliary device can be supplied with electrical energy by the at least one wind turbine.

[0043] The at least one wind turbine is configured to convert the kinetic wind energy in electrical energy. The wind turbine may be an onshore wind turbine or, preferably, an offshore wind turbine. The hydrogen production system may comprise at least one

[0044] HB / HB 240487WO

[0045] 25. November 2024 (previously described offshore) wind farm with one or more wind turbines and at least one hydrogen production plant comprising the at least one electrolyzer.

[0046] In particular, the hydrogen production system may be an offshore hydrogen production system with one or more offshore structures. An (stationary) offshore structures (i.e., no ships or the like) may be configured to support the wind turbine, the electrolyzer and / or the at least one electrolyzer auxiliary device. In variants of the invention, the at least one offshore structure might also comprise a Jack-up platform floated to site. An offshore structure may be a floatable or non-floatable offshore structure. By way of example, the offshore hydrogen production system may comprise one or more offshore wind turbine structures each comprising at least the wind turbine and in the case of a decentral system, at least one electrolyzer. The offshore hydrogen production system may comprise at least one substation, e.g., comprising a transformer and one or more electrolyzer auxiliary device.

[0047] According to the invention, the electrolyzer is supplied respectively driven with a predefined holding voltage lower than a minimum operating voltage of the electrolyzer if the power (currently) providable respectively feedable by the wind turbine to the electrolyzer is lower than a predefined minimum electrolyzer operating power.

[0048] According to an embodiment of the method according to the invention, the power (currently) providable by the wind turbine to the electrolyzer can be measured and / or determined. Determining may be based on a wind turbine parameter. For instance, the wind turbine parameter may be the angular speed of the wind turbine. Based on said (e.g., measured) wind turbine parameter and a provided power speed characteristic curve (e.g., stored in a memory of the controller), wherein said power speed characteristic curve may define the relation between the angular speed and generatable power of the specific wind turbine operating with said angular speed, the power (currently) providable by the wind turbine to the electrolyzer can be determined. As will be described hereinafter, the power providable by the wind

[0049] HB / HB 240487WO

[0050] 25. November 2024 turbine to the electrolyzer may also be an estimated power providable by the wind turbine to the electrolyzer during a first future time window.

[0051] According to a further embodiment of the method according to the invention, the at least one electrolyzer may be a PEM (proton exchange membrane) electrolyzer. A PEM electrolyzer is particularly suitable to be used in a hydrogen production system having one of more wind turbines according to the invention. As described, the degradations of a membrane of a PEM electrolyzer can be reduced by the method according to the invention. It shall be understood that in variants of the invention, the at least one electrolyzer may alternatively or additionally be an electrolyzer of a different type, such as an alkaline electrolyzer, a high temperature electrolyzer or the like.

[0052] The minimum operating voltage is, in particular, a minimum operating cell voltage of the electrolyzer. Presently, the minimum operating voltage means, in particular, the cell voltage level which is at least required to enable a conduction of the (water) electrolysis process. By way of example, the minimum operating cell voltage may be approximately 1.5 V.

[0053] By supplying respectively driving the electrolyzer with a predefined holding voltage lower than said minimum operating voltage, the electrolyzer is set respectively operated in a hot-standby mode. It has been recognized that this saves time at restart since the electrolyzer would now need only a short time period (e.g., approximately 30 s) to resume its production respectively (full) operation state. This results, in particular, in higher hydrogen yields. Moreover, the frequency of the need to switch from the operating mode to cold-standby mode can be minimized, thereby improving opportunities for increased hydrogen production.

[0054] According to the invention, the electrolyzer may only be set to the hot-standby mode if the power providable for said electrolyzer is not sufficient to perform the electrolysis

[0055] HB / HB 240487WO

[0056] 25. November 2024 process. In other words, the power (e.g., currently) providable by the wind turbine to the electrolyzer is lower than a predefined minimum electrolyzer operating power.

[0057] The predefined minimum electrolyzer operating power means, in particular, a power level which is at least required to enable a conduction of the electrolysis process. In contrast to the prior art, if said predefined minimum electrolyzer operating power cannot be provided to the electrolyzer the electrolyzer is not shut down (to a cold stand-by mode) but set into the hot-standby mode with a predefined holding voltage lower than a minimum operating voltage (if the power providable to the electrolyzer is sufficient to provide said predefined holding voltage lower).

[0058] For instance, the controller may compare a determined power providable by the wind turbine to the electrolyzer with the predefined minimum electrolyzer operating power (e.g., stored in a memory of the controller).

[0059] According to a preferred embodiment of the method according to the invention, the predefined holding voltage may be defined such that the electrolyzer is driven (by said holding voltage) with a current density that prevents a diffusion of hydrogen from a cathode of the electrolyzer to an anode of the electrolyzer. In particular, it has been recognized that since potentiostatic control of the cell membrane can be maintained with the predefined holding voltage, the application of said predefined holding voltage, e.g., by the power supply of the electrolyzer, as holding voltage to the cell membrane may provide sufficient potential to drive a (very small) current density, e.g., in the range of ca. 0.05 % of the rated current density, to prevent the diffusion of hydrogen from the cathode to the anode. In other words, a hot-standby mode of the electrolyzer can be maintained.

[0060] According to a particular preferred embodiment of the method according to the invention, the predefined holding voltage is in a holding voltage range of 1.2 V to 1.6 V, in particular, in the holding voltage range of 1.3 V to 1.5 V. In particular, it has been recognized that a holding voltage of approximately 1.3 V may provide sufficient

[0061] HB / HB 240487WO

[0062] 25. November 2024 potential to drive said (very small) current density, in particular, needed to prevent the diffusion of hydrogen from the cathode to the anode of the electrolyzer.

[0063] According to a further embodiment of the method according to the invention, the power (currently) providable by the wind turbine to the electrolyzer may be lower (but sufficient to enable the provision of the predefined holding voltage) than a predefined minimum electrolyzer operating power if the wind speed at the wind turbine is larger than a predefined cut-in wind speed and lower than a predefined electrolyzer wind speed required for generating the predefined minimum electrolyzer operating power. The predefined cut-in wind speed is, in particular, approximately 3 m / s. The predefined electrolyzer wind speed is, in particular, approximately 5.5 m / s.

[0064] In particular, it has been recognized that that the wind energy production by a wind turbine may already start at a cut-in wind speed (e.g., 3 m / s), while an electrolyzer may only start operation at a predefined electrolyzer wind speed (e.g., 5.5 m / s) larger than said cut-in wind speed. This is, in particular, because an electrolyzer can only start its operation at respective with a minimum input power not lower than approximately 15 % of its nominal power rating. Otherwise, rapid, accelerated low power degradations will occur in the membrane electrodes of the electrolyzer.

[0065] In order to enable a more effective utilization of the wind resources in the region between the cut-in wind speed and predefined electrolyzer wind speed (e.g., >3<5.5 m / s), according to an embodiment of the method according to the invention, a power converter of the wind turbine and / or a power converter supplying a rectified DC power to the electrolyzer is controlled, in particular, by the controller, and operated to deliver the predefined holding voltage to the electrolyzer respectively the electrolyzer stacks.

[0066] According to a further preferred embodiment of the method according to the invention, the hydrogen production system may comprise at least one auxiliary power generation device. In particular, the at least one auxiliary power generation device

[0067] HB / HB 240487WO

[0068] 25. November 2024 may be a (rechargeable) battery energy storage device respectively system and / or a fuel cell. The method may further comprise: supplying, by the auxiliary power generation device, the electrolyzer with a predefined holding voltage lower than the minimum operating voltage of the electrolyzer if no power is (currently) generated by the wind turbine (in particular, if the wind speed is below the cut-in windspeed).

[0069] The battery energy storage system may be recharged, in particular, if the wind turbine generates more electrical power than needed by the electrolyzer, in particular, the electrolyzer production plant. A battery energy storage system (BESS) can, in particular, be combined with the previously described control strategy if the power (currently) providable by the wind turbine to the electrolyzer is lower than a predefined minimum electrolyzer operating power. In particular, the battery energy storage system can be incorporated into a power supply unit of the electrolyzer as for wind energy to be harvested. During idling of the wind turbine, e.g., due to wind speeds <3 m / s or above cut-out region, the stored energy in the BESS can provide the predefined holding voltage to the electrolyzer, in particular, to operate the electrolyzer in the hot-standby mode during the idling phase. Thus, this embodiment enables an even speedier and more frequent resumption of hydrogen production, in particular, at wind speeds larger than the predefined electrolyzer wind speed (e.g., >5.5 m / s). Thereby, effectively yielding more hydrogen on a longer cumulative time scale can be realized.

[0070] According to a further preferred embodiment of the method according to the invention, the method may further comprise: reducing a power consumption of at least one electrolyzer auxiliary device (of the electrolyzer production system) if the power (currently) providable by the wind turbine to the electrolyzer is in a predefined minimum electrolyzer operating power range (thereby increasing the portion of power providable to the electrolyzer of the total power generated by the wind turbine (and thereby

[0071] HB / HB 240487WO

[0072] 25. November 2024 reducing the portion of the power provided to the at least one electrolyzer auxiliary device of the total power generated by the wind turbine)).

[0073] In particular, it has been recognized that the power consumption of the at least one electrolyzer auxiliary device can be temporarily reduced in order to increase the power available respectively providable for the electrolyzer. A predefined minimum electrolyzer operating power range means, in particular, a power range from a predefined lower minimum operating power to the (higher) predefined minimum operating power (previously described). In other words, a technique is, in particular, provided to increase the net energy available for electrolysis. By this technique it can be provided to temporarily reduce the energy consumption of one, preferably all of the one or more electrolyzer auxiliary devices (which are, in particular, tied to the electrical terminals of the wind turbine) so that the available gross energy can be maximized for electrolysis and enable electrolyzer respectively an electrolyzer stack to become operable already at wind speeds lower than needed for operation according to prior art (e.g., <5.5 m / s).

[0074] By way of example, the electrolyzer auxiliary device may be at least one hydrogen compressor. For example, if the hydrogen production system provides hydrogen offtake and / or hydrogen storage, it may be possible at electrolyzer output pressure either on the platform and / or the inter-array pipes and / or the export pipeline to reduce the power consumption of the at least one compressor and / or reduce the power consumption of more than one compressor, or chose to not operate / shut down one or more compressor modules.

[0075] Alternatively or additionally, the method may further comprise: reducing a power consumption of at least one wind turbine auxiliary device if the power providable by the wind turbine to the electrolyzer is in a predefined minimum electrolyzer operating power range

[0076] HB / HB 240487WO

[0077] 25. November 2024 In particular, it has been recognized that the power consumption of the at least one wind turbine auxiliary device can be temporarily reduced in order to increase the power available respectively providable for the electrolyzer. For instance, at least one (large) wind turbine power consumer (e.g., a consumer for avoiding yawing the wind turbine or a consumer for active corrosion protection for the wind turbine foundation / s) can be deactivated for a certain time period.

[0078] An earlier start of hydrogen production may be provided by the electrolyzer when wind speeds are picking up beyond the cut-in wind speed. In addition, this may allow the electrolyzer to remain in operation during time periods where the wind speed temporarily drops below the predefined electrolyzer wind speed (e.g., 5.5 m / s). In other words, the actual predefined minimum electrolyzer wind speed needed for operation can be reduced (compared to prior art respectively without said technique).

[0079] Generally, there may be different options in the invention to reduce a power consumption of at least one electrolyzer auxiliary device. According to a preferred embodiment of the method according to the invention, the hydrogen production system may comprise at least one water storage and at least one water intake device as the at least one electrolyzer auxiliary device. The water intake device may be configured to deliver water (in particular, sea water) to the electrolyzer (in particular, via a previously water treatment module) and to the water storage (in particular, via a previously water treatment module). The water storage (e.g., one or more water tanks) may be configured to store the delivered (in particular, treated) water. Furthermore, the water storage may be connected with the electrolyzer for delivering the stored water to the electrolyzer. The method may further comprise: stopping operating of the water intake device and / or reducing operating capacity and delivering water completely or partially from the water storage to the electrolyzer if the power (currently) providable by the wind turbine to the electrolyzer is in a (previously described) predefined minimum electrolyzer operating power range.

[0080] HB / HB 240487WO

[0081] 25. November 2024 Stopping operating of the water intake device includes, in particular, stopping supplying the water intake device with electrical energy providable by the wind turbine. In other words, the portion of the generated power providable to the electrolyzer of the total generated power can be (temporarily) increased by stopping operating the water intake device. Preferably, the water intake device comprises at least one water pump and the at least one water treatment module.

[0082] In particular, at least one water storage can be integrated in the hydrogen production system. During operations at wind speeds above the minimum operable point of the electrolyzer (i.e., the predefined minimum electrolyzer operating power), the water intake device and equipment, respectively, may deliver water (e.g., pumped from the water surrounding the offshore structure and subsequently treated) (in real-time) to the electrolyzer as well as to the water storage respectively storage tank via at least one controllable manifold. When wind speeds are such that the resulting power providable to the electrolyzer is below the minimum operable point of the electrolyzer, available wind resources can be utilized to make water storage possible and readily available at the resumption of electrolysis at wind speeds in the predefined minimum electrolyzer operating power range respectively around the minimum operable point of the electrolyzer (in particular, as described hereinbefore). This may reduce the electrical loading on a central electrical bus of the hydrogen production system and consequently, more power can be delivered to said bus by not utilizing the water intake device at this operating point.

[0083] According to a further embodiment of the method according to the invention, the method may further comprise operating the water intake device such that (pumped and treated) water is delivered from the water intake device to the electrolyzer and to the water storage (e.g., until a predefined maximum fill level is reached) if the power (currently) providable by the wind turbine to the electrolyzer is larger than the predefined minimum electrolyzer operating power range.

[0084] HB / HB 240487WO

[0085] 25. November 2024 In particular, at least one manifold and / or at least one pump can be controlled by the controller accordingly.

[0086] In a similar manner as e.g., the water treatment system, the operation respectively power consumption level of at least one other auxiliary system for the electrolyzer, the wind turbine and / or the wind farm can be temporarily adjusted (e.g. HVAC and cooling systems for the electrolyzer and / or for the wind turbine and / or for the substation).

[0087] For the duration of the predicted period of lower power production, there may be further options to conserve respectively reduce power for the one or more electrolyzers, e.g. by:

[0088] - temporarily reducing the power or avoiding operating electrolysis auxiliary systems like compressors (for air, nitrogen, hydrogen), water treatment (e.g. cleaning of system), and / or

[0089] - by avoiding operating (power hungry) wind turbine components, like yaw drives, reducing or completely deactivating the 1CCP system (active corrosion protection of steel foundation structures).

[0090] Switching respectively adaptive regulating the operation of at least one of these systems based on their respective operation limits may need to happen within predetermined ranges (e.g., maximum temperatures for the cooling system, maximum acceptable wind speeds and wind direction offsets for WTG yaw drives, maximum acceptable degradation of the electrochemical potential for the 1CCP active corrosion protection system).

[0091] The control system may be configured to detect (e.g., using sensors) and / or predict (e.g., using process models) excursions from the acceptable ranges of temperatures

[0092] HB / HB 240487WO

[0093] 25. November 2024 and other parameters like wind-speeds, offset angles, states of charge, voltages or electrochemical potentials.

[0094] According to a further preferred embodiment of the method according to the invention, the hydrogen production system may comprise at least one auxiliary power generation device, in particular, a (previously described) battery energy storage system respectively device. The method may further comprise: supplying, by the auxiliary power generation device, at least one (constant power) electrolyzer auxiliary device (of the hydrogen production system) with electrical power if the power (currently) providable by the wind turbine to the electrolyzer is in a predefined minimum electrolyzer operating power range.

[0095] In particular, the BESS may be incorporated to power at least one constant power electrolyzer auxiliary device which would otherwise reduce the available gross energy if powered directly at the electrical terminals of the wind turbines (at windspeeds <5.5 m / s). Thus, at wind speeds <5.5 m / s, lower auxiliary consumptions are seen in the power network, therefore, more power is measured at said central electrical bus.

[0096] It shall be understood that in variants of the invention other auxiliary power generation devices can also be implemented, such as fuel-fired turbines, and also combinations with other renewable power generation devices, preferably with a complementary power production profile, such as e.g. offshore photovoltaic devices.

[0097] With more power in the wind as wind resources improve at near rated or rated power, the controller may be configured to send signal to the electrolyzer power supply to ramp up and / or reconnect the supply of the at least one constant power electrolyzer auxiliary device and / or water intake device to take power from the electrical terminals of the wind turbine to preserve water and battery charge levels.

[0098] The energy storage capacities and effectiveness of such a method implemented for a 5 MW stack of electrolyzer (as a mere example) is estimated in Tables 1 & 11 and, in

[0099] HB / HB 240487WO

[0100] 25. November 2024 particular, is evident in the reduction of wind speed for the operation of electrolyzer by at least 0.5 m / s, which corresponds to a significant yearly cumulative improvement of net energy available for electrolysis. Table 1: Energy capacities of the incorporated storage system

[0101] Table 11: Effectiveness of the embodiments of the method According to a further particular preferred embodiment of the method according to the invention, the method may further comprise:

[0102] HB / HB 240487WO

[0103] 25. November 2024 predicting the wind speed at the wind turbine for a first future time window, determining the estimated power providable by the wind turbine to the electrolyzer during the first future time window based on the predicted wind speed, determining whether the estimated power providable by the wind turbine to the electrolyzer during the first future time window is within a predefined minimum electrolyzer operating power range, and reducing a power consumption of at least one electrolyzer auxiliary device during the first future time window if the determined power providable by the wind turbine to the electrolyzer during the first future time window is in a predefined minimum electrolyzer operating power range.

[0104] Alternatively or additionally, (as described above) the power consumption of at least one further power consumer respectively a wind turbine auxiliary device of the wind turbine respectively the wind farm can be lowered. Examples for such options are e.g., to temporarily not operate the yaw drive(s) of the wind turbine nacelle(s) and / or to limit the power settings for e.g. HVAC and cooling system(s) of substation, wind turbine nacelle(s), etc., and / or to limit or stop the current flow of active corrosion protection system(s) for a limited period of time.

[0105] Limits for the duration of such temporary energy conserving measures may be determined by e.g. maximum allowable temperatures (e.g., for cooling & HVAC systems), maximum allowed yaw offset of a wind turbine nacelle at a certain wind speed (e.g. for yaw drives), allowed potential degradation (for e.g. active corrosion protection system) etc.

[0106] The combined predicted energy savings across the wind turbine location or the entire wind farm can then be used to keep a corresponding additional number of electrolyzers from having to be set back into a lower state of operation (i.e. from operational to hot-standy and / or from hot-standby to cold-standby).

[0107] HB / HB 240487WO

[0108] 25. November 2024 In order to be able to react in good time to changes in power generation by the wind turbine due to changing wind speeds, it is proposed, in particular, to forecast the wind speed and use this to estimate the power available from the wind turbine for a (first) future time window. Preferably, the (first) future time window may have a time length between 1 s and 120 s, preferably between 5 s and 20 s. The at least one predicted wind speed parameter is based on a wind measuring, in particular, conducted by a LIDAR equipment. In particular, the hydrogen production system may comprise a wind measuring device, in particular, the LIDAR equipment.

[0109] Based on said predicted wind speed, the estimated power generatable and, in particular, providable by the wind turbine can be predicted. As previously described, the predicted respectively estimated power can be compared with the (previously described) predefined minimum electrolyzer operating power range.

[0110] In particular, the method may comprise reducing a power consumption of at least one electrolyzer auxiliary device during the first future time window if the determined estimated power providable by the wind turbine to the electrolyzer during the first future time window is in a predefined minimum electrolyzer operating power range. This may, in particular, comprise stopping operating of the water intake device and delivering water from the water storage to the electrolyzer during the first future time window if the determined estimated power providable by the wind turbine to the electrolyzer during the first future time window is in a predefined minimum electrolyzer operating power range and / or supplying, by the auxiliary power generation device, at least one (constant power) auxiliary device with electrical power during the first future time window if the determined estimated power providable by the wind turbine to the electrolyzer during the first future time window is in a predefined minimum electrolyzer operating power range.

[0111] Predicting the providable power can provide an opportunity for the at least one electrolyzer auxiliary device to anticipate the resumption in hydrogen production when, in particular, the availability of favorable wind speed is forecasted, i.e., appr. >5

[0112] HB / HB 240487WO

[0113] 25. November 2024 m / s (as described herein before), corresponding to the actual minimum operable power of the electrolyzer. Accordingly, the controller (e.g., wind turbine controller or the wind farm (semi-central / central) controller) can proactively transmit a start signal to at least one electrolyzer auxiliary device and / or electrolyzer is supplied by the in the decentral or semi-central / central system respectively, in anticipation of forecasted promising wind speeds for the resumption of hydrogen production. In this way, the at least one electrolyzer auxiliary device can be proactively and speedily initiated to provide needed services for the resumption of hydrogen production such that the transition to production state, either from cold-standby mode or hot-standby mode is quickened, in particular, by at least 20s more, thereby increasing hydrogen production rates under frequent cyclic changing of states due to inherent intermittencies of wind resources.

[0114] The power consumption of one or more electrical consumers in the balance of stack and balance of plant of the electrolyzer, but also the wind turbine and its support structure, can be temporarily reduced. Examples for such variable consumers in the electrolyzer balance of plant (BoP) are e.g., water intake device, such as a seawater lift pumps, circulation pumps, cooling pumps, HVAC systems, compressors, etc. Similarly, power consumption of some BoP equipment of the wind turbine itself (and its substructure) can be temporarily reduced. This can apply e.g., to active corrosion protection systems (ICCPs). These can be temporarily deactivated or run at a lower power rating, as the protective effect against corrosion will not be immediately lost, but slowly decay over a period of time. HVAC systems, heaters, etc. in the wind turbine and its support structure are examples for further electrical consumers, which may be run at a reduced power level for limited (predefined) periods of time. This will not have detrimental effects for the system as long as sufficient feed water is available for electrolysis and thresholds and / or durations ofnon-allowable temperatures, fluid levels, flow-rates or pressures, moisture levels, corrosion protection, etc. are not exceeded, a temporary reduction will not have a detrimental effect on continued system operation or component integrity. A condition monitoring system can be used to detect any violations of e.g., critical temperature thresholds, flow rates, fluid levels,

[0115] HB / HB 240487WO

[0116] 25. November 2024 etc. and feed this information back to the control system, so that power set points can be adjusted.

[0117] In addition, according to a further embodiment of the method according to the invention a process model is proposed to be used for a model-predictive control of ideal power settings and power profiles for flexible BoP consumers as well as an optimized use of storage capacities for electricity and media. Further, results of this process model can be compared with medium term wind speed predictions (e.g. from weather models). The wind measuring equipment, e.g., nacelle LIDAR, can complement this with measurement for short term predictions. This may allow the controller to decide whether one or more electrolyzer modules of the electrolyzer can remain in operation instead of going into a hot-standby mode, or remain in hot- standby mode instead of going into cold standby during a period of lower wind speeds, and enable this by reducing the BoP power consumption within the allowable limits of the electrolyzer and BoP system components.

[0118] In a semi-central and / or central hydrogen production system where the wind turbines are linked by array cables, the temporary savings from several connected wind turbines as already described can be pooled to keep one or more additional electrolyzer modules in operation during temporary phases of lower wind resources. The hydrogen production system can be operated even more efficient.

[0119] According to a further preferred embodiment of the method according to the invention, the method may further comprise: determining a reference angular speed of the wind turbine based on at least one wind speed parameter predicted for the wind turbine for a second future time window, regulating the wind turbine by setting a pitch angle during the second future time window, wherein the pitch angle is determined based on the determined reference angular speed and the current angular speed of the wind turbine,

[0120] HB / HB 240487WO

[0121] 25. November 2024 determining the estimated power providable by the wind turbine to the electrolyzer during the second future time window based on the determined reference angular speed, controlling the at least one electrolyzer of the hydrogen production system by setting an at least almost constant rate of change of current during at least a portion of the second future time window, wherein the rate of change of current is based on the predicted power, in particular, if the determined estimated power providable by the wind turbine (110, 510, 610, 710) to the electrolyzer (114, 514, 614, 714, 1014) is equal or larger than the predefined minimum electrolyzer operating power.

[0122] In contrast to the prior art, according to this embodiment, by providing a method (and a controller) for regulating the at least one wind turbine based on a predicted wind speed parameter and for controlling the power demand of the at least one electrolyzer of the hydrogen production system such that the rate of change of current respectively power is kept at least almost constant respectively steady, the service life of the at least one electrolyzer of the hydrogen production system having at least one wind turbine can be even more increased. More particularly, a proactive response to be aided by forewarning wind speeds is proposed.

[0123] In particular (as will be described hereinafter in more details), the method according to the said embodiment may comprise an interplay of (a) proactive (i) active pitch regulation, (ii) turbine power control and (hi) electrolyzer power demand control, in particular, to ensure (b) a steady ramp rate of power to the at least one electrolyzer so that a constant rate of change of the current density of the electrolyzer cells is maintained regardless the intermittency of wind resources, wherein (c) the control responses of the three (a) (i), (ii) and (hi) are, in particular, coordinated in a feedforward system respectively controller according to the measured forewarning respectively predictive wind speed parameter.

[0124] HB / HB 240487WO

[0125] 25. November 2024 In particular, a system can be provided which “absorbs the transient power of wind resources” so that abrupt power variation is avoided and a steady, controlled change in current density of the at least one electrolyzer is achieved, in particular, for low wind speed region of the operation of the at least one wind turbine.

[0126] More particularly, it has been recognized that a main reason for the reduced service time of an electrolyzer of a hydrogen production system with at least one wind turbine is an abnormal and accelerated degradation in the membrane electrodes of the at least one electrolyzer caused by the fluctuating power transfer between the at least one wind turbine and the at least one electrolyzer respectively the fluctuating power generated by the at least one wind turbine.

[0127] Degradations in an electrolyzer are determined by voltage degradation rate (pV / h), i.e., the proportion at which the short circuit cell voltage of the membrane electrodes of an electrolyzer depreciates respectively reduces over the course of service lifetime. In particular, it has been recognized that there are five power operating conditions which cause cell degradations in an electrolyzer. These five power operating conditions are: maintaining operation, low power fluctuation operation, constant turning operation, high power fluctuation operation, and constant rated power operation.

[0128] Of the five power fluctuating operations, both low power fluctuations and high power fluctuations account for over 35 % of the degradations encountered. The total voltage degradation rate under power fluctuations is given by equation (a), wherein nelis the cells number of the electrolyzer, Vfand tfis the voltage degradation rate and operating times under fluctuations respectively. Based on equation (a), a reduction in the length of tfor its complete elimination will effectively mitigate or eliminate degradations due to power fluctuations. The technique to achieve this is proposed in this embodiment.

[0129] HB / HB 240487WO

[0130] 25. November 2024 AVd= nel. (tfVf) [a]

[0131] In order to regulate and / or control the power transfer from the at least one wind turbine to the at least one electrolyzer (if the power providable by the wind turbine to the electrolyzer is equal or larger than the predefined minimum electrolyzer operating power), a reference angular speed of the wind turbine (supplying the at least one electrolyzer with electrical power) can be determined based on at least one predicted wind speed parameter for the wind turbine for a future time window. In other words, based on a wind speed parameter, in particular, the wind speed and / or wind direction (at the at least one wind turbine) predicted for the (second) future time window for said wind turbine the future angular speed, namely, the reference angular speed of the wind turbine for said future time window, can be determined, in particular, predicted.

[0132] In the present case, a (first and / or second) future time window means, in particular, a time period in the near future (e.g., within the next x minutes (e.g., between 0 and 10 minutes). Preferably, at least the said angular speed respectively velocity can be determined during a (respective) current time window for the future time window immediately following the current time window. In other words, a future time window refers in particular to the (respective) time window that follows a current time window.

[0133] Furthermore, in the present case, determining a reference angular speed means, in particular, that a parameter value is determined from which the angular speed can be at least (directly) deduced for said future time period. The reference angular speed is, in particular, a speed value that can be achieved with said predicted wind parameter by respectively at said wind turbine. The reference angular speed is, in particular, determined on said predicted wind parameter such that in case of low wind speeds (e.g., smaller than 30 m / s) the reference angular speed, and thus, in particular, the generatable power, is maximized. A respective criterion can be predefined. The

[0134] HB / HB 240487WO

[0135] 25. November 2024 determining of the reference angular speed can be additionally based on said criterion respectively the rules of said criterion.

[0136] The wind turbine can be regulated by setting a pitch angle during respectively for the (second) future time window based on the determined reference angular speed and the current angular speed of said wind turbine. In particular, the pitch angle to be set by the controller is determined based on the (determined) reference angular speed and the current angular speed of the wind turbine. In particular, the current angular speed of the wind turbine can be fed-back to the controller, in particular, for performing an error adjustment. In the present case, error adjustment means, in particular, that the pitch angle will be tuned by the determined reference angular speed if the current angular speed ends up being not of the same value as the determined reference angular speed (value).

[0137] The power generatable by the at least one wind turbine during a specific time period depends on the (possible) angular speed of the wind turbine during said time period. Further, the power generatable by the wind turbine during said future time window can be determined respectively predicted based on the determined reference angular speed.

[0138] In order to further reduce cell degradations of an electrolyzer, power fluctuations at the electrolyzer should be reduced. In order to reduce the power fluctuation, it is proposed, according to said preferred embodiment, to control the at least one electrolyzer (in particular, the power demand of said electrolyzer) of the hydrogen production system by setting an at least almost constant rate of change of current during the future time window. By setting a constant rate of change of current respectively power, a constant rate of change of the current density of the at least one electrolyzer cell can be maintained regardless the intermittency of wind resources The rate of change of current can be based on the predicted power.

[0139] HB / HB 240487WO

[0140] 25. November 2024 Controlling the at least one electrolyzer of the hydrogen production plant by an at least almost constant rate of change of current at least during a part of the future time window means, in particular, that the power transfer from the at least one wind turbine to the at least one electrolyzer is controlled such that at least an almost steady ramp rate of power to the at least one electrolyzer is provided.

[0141] Further, an at least almost constant rate of change of current during the (second) future time window, in particular, during at least a portion of said future time window means, in particular, that the rate of change of during said portion is kept at least almost constant respectively steady.

[0142] In particular, a response of the controller to the interfacing electrolyzer power supply of the at least one electrolyzer can be proactively coordinated with the forewarning power control of the wind turbine to deliver the needed voltage and smoothen the current's rate of change as given equation (b), wherein V and P are the voltage and power respectively across the at least one electrolyzer.

[0143] According to a further embodiment of the method according to the invention, the at least one predicted wind speed parameter is a predicted wind speed and / or wind direction at the wind turbine. The predicted wind speed parameter is based on a wind measurement, in particular, conducted by a LIDAR equipment at the wind turbine. It shall be understood that in variants of the invention, alternatively or additionally, another wind measurement equipment can be used.

[0144] Preferably, the at least one wind measurement device may be configured to measure at least one wind parameter and to predict the at least one wind speed parameter for the future time window based on the at least one measured wind parameter.

[0145] HB / HB 240487WO

[0146] 25. November 2024 In particular, the at least one predicted wind speed parameter may be obtained from forecasting measurement or data acquisition system such a LIDAR equipment. In the i i - 1 1 i i i . i ■ ■ upwind control scheme respectively the method according to the invention, W5may be at least one predicted wind speed parameter, in particular, the measured forewarning i i rt-r upwind . .. i - i upstream wind speed. W5may be an input to the controller according to the . upwind . i i , . . i i r invention. Based on W5the controller (in particular, the determining module of the controller) may determine the reference angular speed cor refobtained from the window wherein 6 is the window length of the forecast respectively prediction.

[0147] According to a preferred embodiment of the method according to the invention, the second future time window has a time length between 1 s and 120 s, preferably between 2 s and 50 s (e.g., 20 s). A time window of a minimum of 20 s for the predicting of the at least one predicted wind speed parameter, e.g., from Lidar or a similar system, is preferably proposed according to this embodiment. In particular, the first time window and the second time window can be the same, in particular, have the same length. Such a second time window may allow, in particular, for providing sufficient time for the ramp down or ramp up to of the rated (in particular, desired) current density. This may give the latitude to look into the wind to proactively determine the possible wind energy production rates, adjust the power respectively current delivered by the at least one wind turbine and power respectively current drawn by the at least one electrolyzer, in particular, to ensure steadiness at each operating point irrespective of the prevailing wind speeds.

[0148] According to a further preferred embodiment of the method according to the invention, the rate of change of current is a stepped rate of change of current with a predefined step size (of the change step). In other words, the rate of change of current may be performed in a stepwise manner with always the same step size. This reduces the computing effort while at the same time an at least almost (in particular,

[0149] HB / HB 240487WO

[0150] 25. November 2024 sufficient) constant rate of power respectively current to the at least one electrolyzer is provided.

[0151] In an ideal scenario, the power ramp scheme respectively the current ramp scheme according to the invention to eliminate the described fluctuations would utilize a very small step change or rate of change in current (for instance, at least almost continuously) as per equation (b). However, it has been recognized that the overall efficiency of hydrogen production by the at least one electrolyzer may become poor since wind energy utilization would be low. Thus, to achieve a better efficiency for production of hydrogen while reducing fluctuations in power supply to the at least one electrolyzer (and consequently mitigate degradations in electrode membrane due to these fluctuations), a stepped change in current and consequently, current density, is proposed according to a preferred embodiment.

[0152] According to said particularly preferred embodiment of the method according to the invention, the predefined change size (of the applicable change step) may be between 2% / s and 10 % / s, preferably between 4% / s and 6% / s (e.g., 5% / s). In particular, it has been shown that with a step size between 4% / s and 6% / s a sufficiently constant rate of power respectively current to the at least one electrolyzer can be provided (while the computing effort can be reduced). In this way, the probability of unutilized wind energy can be minimized while ensuring minimal fluctuation since the electrolyzer load can be effectively controlled to respond to forecasted respectively predicted wind speeds.

[0153] According to a further embodiment of the method according to the invention, the method may further comprise: determining whether the predicted respectively estimated power satisfies a predefined power criterion, and controlling the at least one electrolyzer of the hydrogen production plant by the at least almost constant rate of change of current during the future time window only if the predicted power criterion is not satisfied.

[0154] HB / HB 240487WO

[0155] 25. November 2024 In other words, the current density of the at least one electrolyzer may be only changed if the predefined power criterion is not satisfied. In particular, it has been recognized that a reduction of the current density is only necessary in case the predicted power does not satisfy a predefined power criterion. The predefined power criterion can be stored in a data memory of the controller, or a computing equipment connected with the controller.

[0156] According to a preferred embodiment of the method according to the invention, the method may further comprise: controlling the at least one electrolyzer such that the current density is kept at least almost constant if the predicted power criterion is satisfied.

[0157] In the present case, keeping the current density at least almost constant means, in particular, that there is no rate of change of current (during the future time window).

[0158] According to a further preferred embodiment of the method according to the invention, controlling the at least one electrolyzer such that the current density is kept constant may comprise adapting respectively changing the cell voltage of the electrolyzer such that the current density is kept constant. By keeping the current density (as long as possible) constant, the service life of the at least one electrolyzer can be further increased.

[0159] According to a further preferred embodiment of the method according to the invention, the power criterion may comprise at least one predefined power range. The at least one predefined power range is, in particular, between 75 % of the rated power of the wind turbine and 100 % of the rated power of the wind turbine. It has been recognized that in a predefined power range between 75 % of the rated power of the wind turbine and 100 % the current density can be kept constant, in particular, by reducing and / or increasing the cell voltage.

[0160] HB / HB 240487WO

[0161] 25. November 2024 An electrolyzer (normally) has a predefined optimal current density, in particular, at a predefined optimal voltage range. In the present case, optimal current density means, in particular, a current density optimal for operation of the electrolyzer. In the present case, an optimal voltage range means, in particular, a voltage range optimal for operation of the electrolyzer.

[0162] Typical optimal current density for the cell membrane of an (PEM) electrolyzer may be in the range of e.g., 2 A / cm2at e.g., cell voltage between 1.5 V and 2 V. As described hereinbefore, 1.5 V may be the minimum operating voltage of an electrolyzer.

[0163] Under intermittent power supply, current drawn and the equivalent current density would become erratic. This is more visible and problematic with decreasing wind speeds because of insufficient power to keep the at least one electrolyzer running at rated or at least near rated capacity. To keep the current density at the predefined optimal current density (value), e.g., 2 A / cm2, in particular, under declining wind speeds, it is proposed that if the predefined power criterion is met, the controller may control the at least one electrolyzer such that the current density is kept constant (typically at rated maximum) while ramping down (or ramping up) the voltage within the predefined optimal voltage range, e.g., between 1.5 V and 2 V. In particular, this is possible up until the predefined minimum rated cell voltage of e.g., 1.5 V is reached. The predefined minimum rated cell voltage may be reached at 75% of rated power.

[0164] It has been recognized that below 75 % of rated power, this means, in particular, in low wind speed region (where wind turbines may operate most of the time), current density must subsequently be reduced according to the decrease in wind resources in order to keep the at least one electrolyzer functional for hydrogen production. As described herein before, this decrease in current density can be done in a planned and regulated manner to avoid degradations of the membrane(s) of the at least one electrolyzer.

[0165] HB / HB 240487WO

[0166] 25. November 2024 If the power criterion is not satisfied, in particular, if the predicted power is in the region below 75% of rated power, since changes in wind power may be inconsistent, it follows, that changes in current drawn by the at least one electrolyzer and consequently, current density would be inconsistent and abrupt, thus, leading the cell membranes to degradations due to the fluctuations. Hence, according to a preferred embodiment of the method according to the invention, it is proposed controlling the at least one electrolyzer of the hydrogen production plant by the at least almost constant rate of change of current during the future time window only if the predicted power criterion is not satisfied.

[0167] According to a further embodiment of the method according to the invention, the hydrogen production system may comprise a plurality of wind turbines for supplying the at least one electrolyzer of the hydrogen production system with electrical power. In particular, the hydrogen production system may comprise a wind farm with two or more wind turbines. The controlling of the at least one electrolyzer of the hydrogen production plant may comprise centrally coordinating the power transfer from the plurality of wind turbines to the hydrogen production plant such that the rate of change of current is kept at least almost constant.

[0168] According to a further embodiment of the method according to the invention, the hydrogen production plant of the hydrogen production system may comprise a plurality of electrolyzers (e.g., of a respective plurality of hydrogen production plants and electrolyzer units, respectively). The controlling of the plurality of electrolyzers of the hydrogen production system may comprise centrally coordinating the power transfer from the at least one wind turbine to the plurality of electrolyzers such that the rate of change of current is kept at least almost constant for each of the plurality of electrolyzers.

[0169] If there is a plurality of wind turbines, said wind turbines may be connected to an (common) electrical bus on a substation of the wind farm via strings, e.g., of medium voltage power cables or high voltage power cables. A plurality of wind turbines may

[0170] HB / HB 240487WO

[0171] 25. November 2024 be connected to form a string. Each individual wind turbine in the cable array network may preferably retain its independence in energy production by the means of the aforementioned controller, in particular, the described forewarning speed prediction.

[0172] However, power transfer between the one or more electrolyzers, arranged on e.g., a central platform, and the wind turbines via the interfacing electrical bus (e.g., a MV bus) may be centrally coordinated via (explicit) communication among the wind farm controller, the electrolyzer controllers and the wind turbine controllers such that the rate of change of current (and thus the current densities in the one or more electrolyzer(s) (e.g., electrolyzer stacks)), driven by di / dtref, is maintained. The previously described controller may at least partially be implemented in the wind farm controller and / or the respective wind turbine controllers (or as a standalone controller).

[0173] In an initial step, in order to ensure optimal energy utilization at all times, the number of electrolyzers and wind turbines in operation can be determined, e.g., by a central controller of the hydrogen production system, such as the wind farm controller. Preferably, at all times, the wind farm controller can determine all operable elements in the system, i.e., active, not faulty wind turbines and electrolyzer stacks.

[0174] In a (subsequent) step, the power transfer can be initiated using an equal allocation of system input power made available on the MV bus collector of the substation by the wind turbines according to equation (c), wherein k is the number of operational electrolyzers and n is the active power available for the window length {w5and j is the number of active wind turbines in the array network and the hydrogen production system, respectively. nj = for all i = 1, 2, . . . , k (c)

[0175] HB / HB 240487WO

[0176] 25. November 2024 The central controller and the previously described controller may send power allocation signals di / dtrefto the one or more electrolyzer controller(s), in particular, in real-time, which can be harmonized with available nj on the AC power bus of each electrolyzer over the window length 6. In this way of explicit, coordinated communication, the need to abruptly modify the electrolyzer load can be avoided since di / dtrefcan be allocated according to the power projected to be available on the AC power bus and the number of operable electrolyzers.

[0177] According to a further preferred embodiment of the method according to the invention, the hydrogen production system may comprise at least one long-range scanning-LlDAR device (also called XXL LIDARS) with at least one infrared laser unit, the method may comprise: forecasting the wind speed at one or more wind turbines for a future time period based on the sensor data of the LIDAR device, wherein the future time period is up to at least 15 minutes, preferably up to at least 30 minutes, forecasting the electrical energy providable by the wind farm during said future time period, based on the forecasted wind speeds, and controlling the at least one electrolyzer based on the forecasted electrical energy.

[0178] The long-range scanning LIDAR (Light Detection and Ranging) device (arranged at the hydrogen production system) may have a range of at least 15km, preferably 20-40km.

[0179] This enables to forecast the wind speed at the at least one wind turbine of the hydrogen production system for a future time period based on the sensor data of the LIDAR device, wherein the future time period is at least 10 minutes, preferably at least 30 minutes (and e.g. at most 60 minutes). Based on the forecasted wind speed, the providable respectively generatable energy by the one or more wind turbines can be forecasted, in particular, calculated (e.g., based on a model of the hydrogen production system (in a known manner)). The one or more electrolyzer can be controlled additionally based on the forecasted electrical energy. For example, if the predicted

[0180] HB / HB 240487WO

[0181] 25. November 2024 electrical energy indicates that this energy will not be sufficient to operate an electrolyzer with the predefined holding voltage then the electrolyzer can be shut down immediately. This may safe energy and, in particular, costs. The saved energy can be used for another purpose. For example, if there are two electrolyzers and it can be derived from the forecasted energy that in the future, only one of these electrolyzers can be supplied with the predefined holding voltage, one of the electrolyzers can directly be shut off. If, for example, an electrolyzer is already in a shut-down state and it can be deduced from the predicted electrical energy that sufficient energy for the operation of the shut-down electrolyzer will be generated in x minutes (where x can be between 10 and 30 minutes), the electrolyzer can be started up so that it is then (timely) ready for operation. The hydrogen production can thus be improved.

[0182] In particular, in a setup of the hydrogen production system with multiple electrolyzers, the method may increase the overall number of electrolyzers that can be kept in operational mode (instead of entering hot stand-by) and / or prevented from being switched off (instead of being kept in hot-stand-by).

[0183] By introducing and making use of more accurate longer term wind forecasts (i.e. for durations that are in the same order of magnitude as those electrolyzers typically need to start production from cold-stand-by, or can be kept in hot stand-by) , control strategies can be provided that proactively determine the number of electrolyzers that may successfully be kept and / or reactivated into production mode during the predicted time horizon.

[0184] As described above, long-range scanning LIDARS may enable predictions beyond the relatively short time window that can be covered by nacelle LIDARs by measuring wind fields far ahead of the wind farm, thus anticipating wind speeds e.g. for the next half hour and beyond.

[0185] HB / HB 240487WO

[0186] 25. November 2024 In particular, in cases where a long-range scanning LIDAR is not installed, or no long- range LIDAR data is available (e.g. installed long-rang LIDAR being unavailable, or in periods with no usable data, e.g. due to fog), real-time wind measurement data from at least one wind farm or at least one measurement mast, (preferably) upstream of the wind farm of the hydrogen production system, may be utilized to predict anticipated wind speeds and directions in similar or even longer time periods than achievable with measurements from the long-range LIDAR data.

[0187] The real-time wind speed and wind direction measurements from the at least one (preferably) upstream wind farm or at least one (preferably) upstream met mast may be used solely or in combination with available long-range LIDAR data, and / or nacelle LIDAR data at the location of the hydrogen production system, and / or weather model forecasts for the area, to improve the quality and / or certainty of predictions over those possible solely with measurements at the location of the hydrogen production system itself.

[0188] By correlating wind speed and wind direction measurement time series, and optionally time series of further meteorological measurement parameters from (preferably) upstream wind farms or met masts (e.g. turbulence intensity, temperature, humidity) with measurement time series from the location of the hydrogen production system itself over extended time periods of months or even years, the confidence in predictions using (also) remotely measured meteorological parameters can be successively increased over the operational lifetime of the hydrogen production system.

[0189] In particular, a (suitably configured system) controller can determine how to best use the available and predicted available wind power, as well as the flexibilities of the power consumers and / or storage media to minimize the ramp-up times of the predicted number of electrolyzers that can be expected to be put back into operation at a later point in time, in particular, based on predefined rules. The overall hydrogen yield of the system can be increased by keeping an appropriate number of

[0190] HB / HB 240487WO

[0191] 25. November 2024 electrolyzers in stand-by, i.e. the number of electrolyzers that can be expected to be operated in a future time window, based on the longer term wind prediction.

[0192] Effectively, such a control strategy may expand the time-limited "low-wind ride- through" capability of the wind turbines and hydrogen production system to a longer time scale, by taking into account the flexibilities and limitations of the power consumption in electrolyzers, the balance of plant, and power feed-in / consumption by further assets like additional renewable sources (e.g. floating photovoltaic structure(s)), or storage.

[0193] According to an embodiment of the controller according to the invention, the controller may be configured to control a reducing a power consumption of at least one electrolyzer auxiliary device if the power (currently) providable by the wind turbine to the electrolyzer is in a predefined minimum electrolyzer operating power range (thereby increasing the portion of power providable to the electrolyzer of the total power generated by the wind turbine (and thereby reducing the portion of the power provided to the at least one electrolyzer auxiliary device of the total power generated by the wind turbine)).

[0194] According to a further embodiment of the controller according to the invention, the controller may be configured to control a stopping operating of the water intake device and delivering water from the water storage to the electrolyzer if the power (currently) providable by the wind turbine to the electrolyzer is in a predefined minimum electrolyzer operating power range.

[0195] According to a further embodiment of the controller according to the invention, the controller may be configured to control an operating the water intake device such that water is delivered from the water intake device to the electrolyzer and to the water storage (e.g., until a predefined maximum fill level is reached) if the power (currently) providable by the wind turbine to the electrolyzer is larger than the predefined minimum electrolyzer operating power range.

[0196] HB / HB 240487WO

[0197] 25. November 2024 According to a further embodiment of the controller according to the invention, the controller may be configured to control a supplying, by the auxiliary power generation device, of at least one (constant power) auxiliary device with electrical power if the power (currently) providable by the wind turbine to the electrolyzer is in a predefined minimum electrolyzer operating power range.

[0198] According to a further embodiment of the controller according to the invention, the controller may be configured: at least one determining module configured to determine a reference angular speed of the wind turbine based on at least one predicted wind speed parameter for the wind turbine for a second future time window, at least one regulating module configured to regulate the wind turbine by setting a pitch angle during the second future time window, wherein the pitch angle is determined based on the determined reference angular speed and the current angular speed of the wind turbine, at least one power predicting module configured to predict power generatable by the wind turbine during the second future time window based on the reference angular speed, and at least one controlling module configured to control the at least one electrolyzer of the hydrogen production system by setting an at least almost constant rate of change of current during at least a portion of the second future time window, wherein the rate of change of current is based on the predicted power, if the power providable by the wind turbine to the electrolyzer is equal or larger than the predefined minimum electrolyzer operating power.

[0199] A further aspect of the invention is a (previously described) hydrogen production system. The hydrogen production system comprises at least one hydrogen production plant having at least one electrolyzer. The hydrogen production system comprises at least one wind turbine configured to supply the hydrogen production plant with

[0200] HB / HB 240487WO

[0201] 25. November 2024 electrical power. The hydrogen production system comprises at least one previously described controller (according to claim 16 or 17).

[0202] According to an embodiment of the hydrogen production system, the hydrogen production system may be an offshore-hydrogen production system having at least one electrical submarine cable connected to an onshore grid, wherein the at least one electrical submarine cable is designed to enable a power transfer (only) for the one or more auxiliary devices of the hydrogen production system. The offshore-hydrogen production system may comprise at least one cable monitoring device configured to: determine the current applied at a connection point of the submarine cable, determining a maximum permissible current for the submarine cable as a function of a predetermined value of a maximum permissible temperature parameter at a reference point located at a predetermined depth of the seabed, the maximum permissible current being determined as a function of the distance of the submarine cable, and controlling the current fed into and / or received from the submarine cable in such a way that the fed-in respectively received current does not exceed the determined maximum permissible current. In particular, the cable monitoring device can control the current received via the at least one submarine cable such that the electrolyzer is supplied with a predefined holding voltage lower than a minimum operating voltage of the electrolyzer if the power providable by the wind turbine to the electrolyzer is lower than a predefined minimum electrolyzer operating power wherein the current does not exceed the determined maximum permissible current In variants of the invention, the cable monitoring device can maximize the utilization of the at least one submarine cable for an increased hydrogen conversion (power import), or an increased power export in case of high wind speeds and / or high electricity prices.

[0203] In case of a (partial) grid connection, i.e. a grid connection designed for power transfer needed only for the auxiliary device(s), a temperature monitoring system of the electrical export and optionally may allow to maximize power import during times of low wind to operate as many electrolyzers as possible without violating the maximum

[0204] HB / HB 240487WO

[0205] 25. November 2024 temperature rating of the cable, as in particular described above. Additionally, environmental criteria like the 2K criterion in Germany can be fulfilled by using cable temperature monitoring in combination with a predictive heat dissipation model for the surrounding soil. Analogously, the use of cable temperature monitoring may allow to maximize the export of power in times of high wind power production and / or high power prices. This in turn may enable to maximize overplanting, which enables a lower installed electrolyzer capacity to wind turbine capacity ratio.

[0206] According to an embodiment of the hydrogen production system according to the invention, the hydrogen production system may further comprise at least one water intake device configured to deliver water (in particular, sea water) to the electrolyzer and to at least one water storage of the hydrogen production system. The water storage is configured to store the delivered water. As described above, the water intake device may comprise a water pump and, in particular, a water treatment module.

[0207] According to an embodiment of the hydrogen production system according to the invention, the hydrogen production system may further comprise at least one auxiliary power generation device, in particular, a battery energy storage device.

[0208] According to an embodiment of the hydrogen production system according to the invention, the hydrogen production system may further comprise at least one wind measurement device configured to measure at least the wind speed and / or wind direction at the wind turbine. The wind measurement device may comprise at least one LIDAR equipment.

[0209] A further aspect of the invention is a computer program comprising instructions which, when the computer program is executed by at least one processor of a controller, cause the processor to execute and / or control the previously described method, in particular, according to claim 1.

[0210] HB / HB 240487WO

[0211] 25. November 2024 It is noted that expressions such as "first", "second", etc. do not specify a series order, but only serve to distinguish between two elements.

[0212] The features of the hydrogen production systems, controllers, methods and computer programs can be freely combined with one another. In particular, features of the description and / or the dependent claims, even when the features of the dependent claims are completely or partially avoided, may be independently inventive in isolation or freely combinable with one another.

[0213] These and other aspects of the present patent invention become apparent from and will be elucidated with reference to the following figures. The features of the present application and of its exemplary embodiments, as presented above, are understood to be disclosed also in all possible combinations with each other.

[0214] In the figures show:

[0215] Fig. 1 a schematic view an embodiment of the hydrogen production system according to the present invention,

[0216] Fig. 2 a diagram of an embodiment of the method according to the present invention,

[0217] Fig. 3 a diagram of an exemplified power-speed characteristics of a wind turbine,

[0218] Fig. 4 a diagram of an exemplified course of the cell voltage at an electrolyzer and an exemplified course of a current density at said electrolyzer,

[0219] Fig. 5 a schematic view of a further embodiment of the hydrogen production system according to the present invention,

[0220] HB / HB 240487WO

[0221] 25. November 2024 Fig. 6 a schematic view of a further embodiment of the hydrogen production system according to the present invention,

[0222] Fig. 7 a schematic view an embodiment of the hydrogen production system according to the present invention with an embodiment of the controller according to the present invention,

[0223] Fig. 8 a diagram of a further embodiment of the method according to the present invention,

[0224] Fig. 9 a diagram of a further embodiment of the method according to the present invention, and

[0225] Fig. 10 a schematic view of a further embodiment of the hydrogen production system according to the present invention.

[0226] Similar reference signs in different Figures indicate similar elements.

[0227] Figure 1 shows a schematic view of an embodiment of the hydrogen production system 150 according to the present invention with an embodiment of a controller 100 according to the present invention.

[0228] The hydrogen production system 150 comprises at least one wind turbine 110, the at least one controller 100 and at least one electrolyzer 114.

[0229] The controller 100 may comprise at least one processor 116 and memory means 118.

[0230] The processor 116 and the memory means 118 are configured to execute software modules respectively software code. The controller 100 is at least configured to control supplying the electrolyzer 114 with a predefined holding voltage lower than a minimum operating voltage of the electrolyzer 114 if the power providable by the

[0231] HB / HB 240487WO

[0232] 25. November 2024 wind turbine 110 to the electrolyzer 114 is lower than a predefined minimum electrolyzer operating power.

[0233] In particular, the hydrogen production system 150 comprises at least one hydrogen production plant 144 having the at least one electrolyzer 114. Preferably, the at least one electrolyzer 114 is a PEM electrolyzer. As schematically indicated, an electrolyzer 114 respectively an electrolyzer module of an electrolyzer 114 comprises an anode 111 and a cathode 113. The predefined holding voltage can be defined such that the electrolyzer 114 can be driven with a current density that prevents a diffusion of hydrogen from the cathode 113 of the electrolyzer 114 to the anode 111 of the electrolyzer 114.

[0234] The at least one wind turbine 110 is configured to convert the kinetic wind energy into electrical energy respectively electrical power. The at least one wind turbine 110 is configured to supply at least the at least one electrolyzer 114 with electrical power, which is generated by the at least one wind turbine 110. The depicted wind turbine 110 comprises a power generating unit 122. The power generating unit 122, e.g., arranged in a nacelle of the wind turbine 122, may comprise a generator, switches, power converters, a wind turbine controller 120 and the like. The wind turbine controller 120 may be communicatively connected at least to the controller 100 via a (wired and / or wireless) data network 142. In particular, the pitch angle p can be send by the controller 100 to the wind turbine controller 120 via the data network 142.

[0235] The electrolyzer 114 respectively a stack of electrolyzers 114 may be configured to produce hydrogen at e.g., 30 bar. The at least one electrolyzer 114 may be arranged outside the wind turbine 110, for instance, in a housing on a (not shown) main access platform of an offshore structure.

[0236] The hydrogen production system 150 may further comprise at least one electrolyzer power supply 124. The electrolyzer power supply 124 may comprise power converters, switches, an electrolyzer power supply converter 126 and the like. The

[0237] HB / HB 240487WO

[0238] 25. November 2024 electrolyzer power supply 124 may be configured to supply the at least one electrolyzer 114 and further hydrogen auxiliary devices 130, 132, 138 of the hydrogen production plant 144 via power lines respectively power cables 140. The electrolyzer power supply controller 126 may be communicatively connected at least to the controller 100 via a (wired and / or wireless) data network 142. The at least one electrolyzer power supply 124 may be arranged outside the wind turbine 110, for instance, in a housing on the main access platform.

[0239] The hydrogen production system 150may comprise, as a hydrogen auxiliary device 130, at least one (hydrogen) processing module respectively (hydrogen) finishing module, e.g., arranged on a main access platform. The processing module may be configured to process the produced (wet) hydrogen.

[0240] The at least one hydrogen processing module can comprise at least one (not shown) hydrogen drying module. The hydrogen drying module can be configured to dry the generated wet hydrogen. Preferably, the hydrogen drying module (after separation of the liquid phase) can be an adsorption drying module (in particular, a TSA (temperature swing adsorption) module) and / or a refrigeration drying module. The adsorption drying module may be, in particular, configured to dry the wet hydrogen by adsorption using a (suitable) adsorber, in particular silica beads. The at least one hydrogen drying module can be configured to cool the wet hydrogen to a temperature of at least less than 5°C. Furthermore, the at least one hydrogen processing module can comprise a (not shown) catalytic deoxo stage, in particular, for treating the wet hydrogen before drying as described above. Such a stage serves to remove oxygen (<0.5%). In variants of the invention, such treatment can also take place at a later stage, for example, at a hydrogen destination structure to which the treated hydrogen can be transported, for example, via a hydrogen pipeline network.

[0241] Preferably additionally, the at least one hydrogen processing module may comprise at least one hydrogen compression module. The hydrogen compression module may be configured to compress the (processed) hydrogen, in particular, the dried hydrogen.

[0242] HB / HB 240487WO

[0243] 25. November 2024 The hydrogen compression module may comprise at least one hydrogen compressor (in particular, a (vertical) piston compressor). The hydrogen compression module 130 can be configured to compress the dried hydrogen to at least 50 barg (and for example at most 250 barg), preferably to essentially 70 barg.

[0244] As can be seen from Figure 1, the hydrogen compression module may comprise at least one hydrogen compression controller 134. The hydrogen compression controller may be communicatively connected at least to the hydrogen controller 128 and / or the controller 100 via the data network 142. The at least one hydrogen compression module 130 may be arranged outside the wind turbine 110, for instance, in a housing on the main access platform.

[0245] In further variants of the invention, the at least one hydrogen processing module may comprise at least one (not shown) transforming module configured to transform the produced hydrogen to ammonia (e.g., via the Haber-Bosch-method or the like).

[0246] The hydrogen production system 150 may comprise, as a hydrogen auxiliary device 132, at least one water intake device, in particular, comprising at least one water treatment module. The water intake device may be arranged in a housing on the main access platform.

[0247] The water treatment module may be connected with a water a pump of the water intake device for pumping seawater to the water treatment module of the water intake device. The at least one water treatment module can be configured to treat the water such that it can be used by the at least one electrolyzer 114 to produce hydrogen. In particular, the water treatment module can treat seawater for the electrolysis process. Preferably, the at least one water treatment module can be a seawater desalination module with membrane-based pressure filtration. Such a seawater desalination module can carry out reverse osmosis, ultrafiltration and / or electrodialysis (also known as electrodeionization (EDI)) to treat the water respectively to treat the seawater accordingly. Such treatment can be used to treat

[0248] HB / HB 240487WO

[0249] 25. November 2024 seawater, in particular, in an energy-efficient manner, which can be used for water electrolysis. The treated water can also be referred to as ultrapure water or "demin water". The treated water can be fed to the electrolyzer module 114 via at least one fluid pipe of a (not shown) internal fluid network.

[0250] Alternatively or additionally, the hydrogen production system 150 may comprise at least one (not shown) inert gas generation module configured to generate an inert gas.

[0251] As can be further seen from Figure 1, the depicted hydrogen production system 150 comprises at least one (constant power) auxiliary device 138, in particular, a plurality of such auxiliary devices 138. Exemplified and non-exhaustive examples of (constant power) auxiliary devices 138 are hydraulics, pumps, heaters etc. for lubrication, cooling, climate conditioning and so on.

[0252] Figure 2 shows a diagram of an embodiment of a method according to the present invention. The method serves for operating a hydrogen production system (such as shown in Figure 1) having at least one wind turbine for supplying at least one electrolyzer of the hydrogen production system with electrical power.

[0253] In a first step 201, the power providable by the wind turbine to the electrolyzer can be determined. The power providable by the wind turbine to the electrolyzer may be the power currently providable by the wind turbine to the electrolyzer or an estimated power providable by the wind turbine to the electrolyzer during a first future time window. For instance, the power currently providable by the wind turbine to the electrolyzer can be measured by a measuring device and / or determined from a measured wind turbine parameter.

[0254] Determining an estimated power can comprise predicting the wind speed at the wind turbine for a first future time window, in particular, based on a measured wind parameter at the wind turbine, such as a wind speed and / or wind direction. For instance, a LIDAR can be used as a wind measurement device. As the power

[0255] HB / HB 240487WO

[0256] 25. November 2024 providable by the wind turbine to the electrolyzer the estimated power providable by the wind turbine during the first future time window can be determined based on the predicted wind speed.

[0257] Preferably, the hydrogen production system may comprise at least one LIDAR device (also called XXL LIDAR) with at least one infrared laser unit, as described above. Determining an estimated power may comprise: forecasting the wind speed at the wind turbine for a future time period based on the sensor data of the LIDAR device, wherein the future time period is at least 15 minutes, preferably at least 30 minutes, forecasting the electrical energy providable by the wind turbine during said future time period, based on the forecasted wind speed.

[0258] This LIDAR enables to forecast the wind speed at the at least one wind turbine of the hydrogen production system for a future time period based on the sensor data of the LIDAR device, wherein the future time period is at least 15 minutes, preferably at least 30 minutes (and e.g. at most 60 minutes). Based on the forecasted wind speed, the providable respectively generatable energy by the one or more wind turbines can be forecasted, in particular, calculated (e.g., based on a model of the hydrogen production system (in a known manner)).

[0259] In step 203, supplying, e.g., under the control of a controller, the electrolyzer with a predefined holding voltage lower than a minimum operating voltage of the electrolyzer is performed if the power providable by the wind turbine to the electrolyzer is lower than a predefined minimum electrolyzer operating power. This may comprise comparing the determined power providable by the wind turbine to the electrolyzer with the predefined minimum electrolyzer operating power.

[0260] In an optional step 205, a supplying, by an auxiliary power generation device (e.g., BESS), of the electrolyzer with a predefined holding voltage lower than the minimum operating voltage of the electrolyzer can be performed if no power is generated by the

[0261] HB / HB 240487WO

[0262] 25. November 2024 wind turbine. In other words, if the power (e.g., determined in step 201) providable by the wind turbine to the electrolyzer is zero, an auxiliary power generation device may supply the predefined holding voltage to the electrolyzer. This step may comprise comparing the determined power providable by the wind turbine to the electrolyzer with the predefined minimum electrolyzer operating power.

[0263] In a further optional step 207, a reducing of a power consumption of at least one electrolyzer auxiliary device can be performed if the power (e.g., determined in step 201) providable by the wind turbine to the electrolyzer is in a predefined minimum electrolyzer operating power range. Preferably, this may comprise stopping operating of the water intake device and delivering water from the water storage to the electrolyzer if the power (e.g., determined in step 201) providable by the wind turbine to the electrolyzer is in a predefined minimum electrolyzer operating power range. This step may comprise comparing the determined power providable by the wind turbine to the electrolyzer with predefined minimum electrolyzer operating power range.

[0264] During operations at wind speeds above the minimum operable point of the electrolyzer (i.e., the predefined minimum electrolyzer operating power), the water intake device and equipment, respectively, may deliver water (e.g., pumped from the water surrounding the offshore structure) (in real-time) to the electrolyzer as well as to the water storage respectively storage tank via manifolds. When wind speeds are such that the resulting power providable to the electrolyzer is below the minimum operable point of the electrolyzer, available wind resources can be utilized to make water storage possible and readily available at the resumption of electrolysis at wind speeds in the predefined minimum electrolyzer operating power range respectively around the minimum operable point of the electrolyzer. This may reduce the electrical loading on a central electrical bus of the hydrogen production system and consequently, more power is delivered to said bus by not utilizing the water intake device at this operating point.

[0265] HB / HB 240487WO

[0266] 25. November 2024 Alternatively or additionally, step 207 may comprise supplying, by the auxiliary power generation device, at least one (constant power) auxiliary device with electrical power if the power providable by the wind turbine to the electrolyzer is in a predefined minimum electrolyzer operating power range.

[0267] The battery energy storage device may be recharged, in particular, if the wind turbine generates more electrical power than needed by the electrolyzer, in particular, the electrolyzer production plant. A battery energy storage system (BESS) can, in particular, be combined with the previously described control strategy if the power (currently) providable by the wind turbine to the electrolyzer is lower than a predefined minimum electrolyzer operating power. In particular, the battery energy storage system can be incorporated into power supply units of the electrolyzers as for wind energy to be harvested. During idling of the wind turbine, e.g., due to wind speeds <3 m / s or above cut-out region, the stored energy in the BESS can provide the predefined holding voltage to the electrolyzer, in particular, to operate the electrolyzer in the hot-standby during the idling phase. Thus, this embodiment enables an even speedier and more frequent resumption of hydrogen production, in particular, at wind speeds larger than the predefined electrolyzer wind speed (e.g., >5.5 m / s). Thereby, effectively yielding more hydrogen on a longer cumulative time scale can be realized.

[0268] Optionally, the one or more electrolyzer(s) can be controlled additionally based on the forecasted electrical energy. For example, if the predicted electrical energy indicates that this energy will not be sufficient to operate an electrolyzer with the predefined holding voltage then the electrolyzer can be shut down immediately. For example, if there are two electrolyzers and it is clear from the forecasted energy that in the future, only one of these electrolyzers can be supplied with the predefined holding voltage, one of the electrolyzers can directly be shut off. If, for example, an electrolyzer is already in a shut-down state and it can be deduced from the predicted electrical energy that sufficient energy for the operation of the shut-down electrolyzer will be

[0269] HB / HB 240487WO

[0270] 25. November 2024 generated in x minutes (where x can be between 10 and 30 minutes), the electrolyzer can be started up so that it is then (timely) ready for operation.

[0271] Figure 3 shows a diagram of an exemplified power-speed characteristics of a wind turbine. Reference sign 317 denotes the cut-in wind speed. Reference sign 315 denotes the predefined electrolyzer wind speed required for generating the predefined minimum electrolyzer operating power. The predefined cut-in wind speed is, for instance, approximately 3 m / s and / or the predefined electrolyzer wind speed is, for instance, approximately 5.5 m / s.

[0272] Figure 4 shows a diagram of an exemplified course of the cell voltage V at an electrolyzer (e.g., electrolyzer 114) and an exemplified course of a current density la at said electrolyzer. P (%) means the rated power.

[0273] As can be seen from Figure 4, if a power criterion is satisfied (in the present example, if the predicted power is in the power range of 75 % of rated power to 100% of rated power), the current density la can be kept constant at the predefined optimal current density of e.g., 2 A / cm2by varying the voltage V (in particular, by ramping down respectively ramping up the voltage V).

[0274] Peiy.min is the predefined minimum electrolyzer operating power (e.g., appr. 15 %). Prange is, in particular, the predefined minimum electrolyzer operating power range (e.g., 10 % to 15 %).

[0275] Furthermore, as can be seen from Figure 4 the holding voltage Vhoi is, for example, approximately 1,3 V.

[0276] As can be further seen from Figure 4, if the power criterion is not satisfied (in the present example, if the predicted power is outside the power range of 75 % of rated power to 100% of rated power), the current density la must be reduced. According to the invention, this is performed in an at least almost constant manner, as described

[0277] HB / HB 240487WO

[0278] 25. November 2024 hereinbefore. In particular, this means that the gradient of Id is constant, as can be directly seen from Figure 4.

[0279] Figure 5 shows a schematic view of a further embodiment of the hydrogen production system 550 according to the present invention. As can be seen, the embodiment of Figure 5 is similar to the embodiment of Figure 1. The main difference between Figure 1 and Figure 5 can be found in the design of the power generation unit 522 and the electrolyzer power supply 524.

[0280] In particular, only in favour of a better overview, the details of the controller 500 are not shown. The controller 500 can, in particular, be formed as in Figure 1.

[0281] The hydrogen production system 550 comprises at least one wind turbine 510, at least one controller 500 and preferably at least one wind measurement device 512.

[0282] The depicted wind turbine 510 comprises a power generating unit 522. The power generating unit 522, e.g., arranged in a nacelle of the wind turbine 510, may comprise a generator, a switch, a power converter, and a wind turbine controller 520. The wind turbine controller 520 may be communicatively connected at least to the controller 500 via a (wired and / or wireless) data network 542, at least for receiving the pitch angle p from the controller 500.

[0283] The depicted hydrogen production system 550 comprises at least one hydrogen production plant 544 having at least one electrolyzer 514. The electrolyzer 514 respectively a stack of electrolyzers 514 may be configured to produce hydrogen at e.g., 30 bar. The at least one electrolyzer 514 may be arranged outside the wind turbine 510, for instance, in a housing on a (not shown) main access platform.

[0284] The hydrogen production system 550 may further comprise at least one electrolyzer power supply 524. The electrolyzer power supply 524 may comprise a power converter, switches, and an electrolyzer power supply converter 526. The electrolyzer

[0285] HB / HB 240487WO

[0286] 25. November 2024 power supply 524 is configured to supply the at least one electrolyzer 514 and further hydrogen processing modules 530, a water treatment module 532 as well as at least one auxiliary device 538 via power lines respectively power cables 540.

[0287] The electrolyzer power supply controller 526 may be communicatively connected at least to the controller 400 via the data network 542. The at least one electrolyzer power supply 524 may be arranged outside the wind turbine 510, for instance, in a housing on the main access platform.

[0288] The hydrogen production system 550 may comprise one or more electrolyzer auxiliary devices 530, 532, 538. For instance, the hydrogen production system 550 comprises, as an electrolyzer auxiliary device, at least one (hydrogen) processing module respectively (hydrogen) finishing module, e.g., arranged on a main access platform. The processing module may be configured to process the produced (wet) hydrogen. The at least one hydrogen processing module can comprise at least one (not shown) hydrogen drying module, as described hereinbefore.

[0289] Preferably additionally, the at least one hydrogen processing module may comprise at least one hydrogen compression module. The hydrogen compression module may be configured to compress the processed hydrogen, in particular the dried hydrogen, as descried hereinbefore. The hydrogen compression module may comprise at least one hydrogen compression controller 534. The hydrogen compression controller 534 may be communicatively connected at least to the hydrogen controller 528 via the data network 542. The at least one hydrogen compression module 530 may be arranged outside the wind turbine 510, for instance, in a housing on the main access platform.

[0290] In further variants of the invention, the at least one hydrogen processing module may comprise at least one (not shown) transforming module configured to transform the produced hydrogen to ammonia (e.g., via the Haber-Bosch-method or the like).

[0291] HB / HB 240487WO

[0292] 25. November 2024 The hydrogen production system 550 may comprise, as an electrolyzer auxiliary device, at least one water intake device having a water treatment module with at least one water pump. The water intake device may be arranged in a housing on the main access platform, in particular, as described hereinbefore. The water treatment module comprises at least one water treatment controller. The water treatment controller may be communicatively connected at least to the hydrogen controller via the data network.

[0293] Alternatively or additionally, the hydrogen production system 550 may comprise at least one (not shown) inert gas generation module configured to generate an inert gas.

[0294] The hydrogen production system 550 comprises at least one constant power auxiliary device 538, in particular, a plurality of constant power auxiliary devices 538, as in particular previously described.

[0295] Figure 6 shows a schematic view of a further embodiment of the hydrogen production 650 system according to the present invention. As can be seen, the embodiment of Figure 6 is similar to the embodiments of Figure 1 and 5. The main difference between Figure 6 and Figure 1 respectively 5 is that there are a plurality of wind turbines 61O.n and a plurality of electrolyzers 614, in particular, of a plurality of hydrogen production plants 644.1, 644.n.

[0296] In particular, only in favour of a better overview, the details of the controller 600 are not shown. The controller 600 can, in particular, be formed as in Figure 1 or 5.

[0297] The hydrogen production system 650 comprises a plurality of wind turbines 61O.n. In particular, the hydrogen production system 650 may comprise at least one string with a plurality of wind turbines 61O.n, preferably a plurality of strings, wherein each string may comprise a plurality of wind turbines 610. n.

[0298] HB / HB 240487WO

[0299] 25. November 2024 The plurality of wind turbines 61O.n, in particular, the one or more strings, may be electrically connected to a substation 654 of the hydrogen production system 650 via at least one power cable.

[0300] The depicted substation 654 comprises a (middle voltage) collector bus system respectively a (common) (middle voltage) electrical bus 656 configured to electrically connect the one or more strings (e.g., between two and twelve) of (offshore) wind turbines 61O.n. Each string may comprise a plurality of offshore wind turbines 610. n (e.g., between four and twelve).

[0301] Furthermore, the depicted substation 654 may have one or more electrical outputs. An exemplified first output may be configured to supply the at least one electrolyzer plant 644.1, 644.n with electrical energy. An exemplified second output may be configured to connect the substation 654 respectively the offshore wind farm of the hydrogen production system 650 with an external grid 662 via an electrical connection. It shall be understood that a (not shown) onshore substation may be provided. A third output may connect the substation 654 via a connection 658 to at least one (not shown) auxiliary device of the hydrogen production system 650.

[0302] The hydrogen production system 650 comprises at least one controller 600, preferably a plurality of controllers 600.n, and preferably at least one (not shown) wind measurement device. Each wind turbine 610. n comprises a (not shown) power generating unit, as in particular described hereinbefore.

[0303] Further, the hydrogen production system 650 may comprise at least one central controller 652, in particular, in the form of a wind farm controller of the wind farm of the hydrogen production system 650. By means of a data network 642, the at least one controller 600.n may be communicatively connected to the central controller 652.

[0304] The depicted hydrogen production system 650 may comprise two or more hydrogen production plants 644.1, 644.n each having at least one electrolyzer 614. The

[0305] HB / HB 240487WO

[0306] 25. November 2024 respective electrolyzer 614 or the respective stack of electrolyzers 614 may be configured to produce hydrogen at e.g., 30 bar. The respective electrolyzer 614 may be arranged outside the wind turbines 61O.n, for instance, in a housing on a central or semi-central platform.

[0307] Each hydrogen production plant 644.1, 644.n (in favor of a better overview, only one hydrogen production plant 644.1 is depicted in more details) may further comprise at least one electrolyzer power supply 624. Each electrolyzer power supply 624 may comprise a power converter, switches, and an electrolyzer power supply converter 626.

[0308] A respective electrolyzer power supply 624 is configured to supply the at least one respective electrolyzer 614 and further hydrogen processing modules 630, water treatment modules 632 as well as at least one auxiliary device 638 of the respective electrolyzer power supply 624 via power lines respectively power cables 640. It shall be understood that there may also be at least one central electrolyzer auxiliary device, such as a central further hydrogen processing module for a plurality of electrolyzers and / or electrolyzer power plant, such as a central water intake device.

[0309] Each electrolyzer power supply controller 626 may be communicatively connected at least to the central controller 652 via the data network 642. The respective electrolyzer power supply 624 may be arranged outside the wind turbines 61O.n, for instance, in a housing on the central or semi-central platform.

[0310] Each electrolyzer plant 644., 644.n may comprise at least one electrolyzer auxiliary device 630, such as a (hydrogen) processing module respectively (hydrogen) finishing module, e.g., arranged on the central or semi-central platform. The processing module may be configured to process the produced (wet) hydrogen. The respective hydrogen processing module can comprise at least one (not shown) hydrogen drying module, as described hereinbefore.

[0311] HB / HB 240487WO

[0312] 25. November 2024 Preferably additionally, a hydrogen processing module may comprise at least one hydrogen compression module. A hydrogen compression module may be configured to compress the processed hydrogen, in particular the dried hydrogen, as descried hereinbefore. A hydrogen compression module may comprise at least one hydrogen compression controller 634. The hydrogen compression controller 634 may be communicatively connected at least to the hydrogen controller 628 and the central controller 652 via the data network 642.

[0313] In further variants of the invention, the hydrogen processing modules may comprise at least one (not shown) transforming module configured to transform the produced hydrogen to ammonia (e.g., via the Haber-Bosch-method or the like).

[0314] Each electrolyzer plant 644.1, 644.n may comprise, as an electrolyzer auxiliary device 632, at least one water intake device, e.g., arranged on the central or semi-central platform, in particular, as described hereinbefore. Each water intake device comprises at least one water treatment controller 636. The water treatment controller 636 may be communicatively connected at least to the hydrogen controller 628 and to the central controller 652 via the data network 642.

[0315] Alternatively or additionally, each electrolyzer plant 644.1, 644.n may comprise at least one (not shown) inert gas generation module configured to generate an inert gas.

[0316] The hydrogen production system 650 comprises at least one constant power auxiliary device 638, in particular, a plurality of constant power auxiliary devices 638, as in particular previously described.

[0317] Figure 7 shows a schematic view an embodiment of the hydrogen production system 750 according to the present invention with a preferred embodiment of the controller 700 according to the present invention.

[0318] HB / HB 240487WO

[0319] 25. November 2024 The hydrogen production system 750 comprises at least one hydrogen production plant having at least one electrolyzer 714. Preferably, the at least one electrolyzer 714 is a PEM electrolyzer.

[0320] Further, the hydrogen production system 750 comprises at least one wind turbine 710. The at least one wind turbine 710 is configured to convert the kinetic wind energy into electrical energy respectively electrical power. The at least one wind turbine 710 is configured to supply at least the at least one electrolyzer 714 with electrical power, which is generated by the at least one wind turbine 710.

[0321] Optionally, the hydrogen production system 150 may comprise at least one wind measurement device 712 configured to measure at least one wind speed parameter, such as the wind speed and / or wind direction, in particular, at the at least one wind turbine 710. The wind measurement device 712 may comprise at least one LIDAR equipment. Based on the at least one measured wind speed parameter, the measurement device 712 (or another prediction equipment, e.g., of the controller 100) can be configured to predict a wind speed parameter for the wind turbine 710 for a first and, in particular, second future time window, such as the predicted wind speed and / or the predicted wind direction, in particular, at the at least one wind turbine 710 during said future time window.

[0322] In particular, the at least one predicted wind speed parameter may be obtained from the measurement device 712 in form of a forecasting measurement or data acquisition system. In the control scheme respectively the method according to the present i i . upwind I , , 1 - 1 - 1 i embodiment, W5may be the at least one predicted wind speed parameter, in i i i r ■ ■ i i upwind particular, the measured forewarning upstream wind speed. W5may be an i ii i upwind .. „ „ „ , . , input to the controller. Based on W5the controller 700 may determine the reference angular speed cor refobtained from the window wherein 6 is the window length of the forecast.

[0323] HB / HB 240487WO

[0324] 25. November 2024 The second future time window may have a time length respectively window length 6 between 1 s and 120 s, preferably between 20 s and 50 s (e.g., 20 s). A time window of a minimum of 20 s for the predicting of the at least one predicted wind speed parameter is preferred. The first time window may be identical with the second time window.

[0325] As has been already described, the hydrogen production system 750 may comprise at least one controller 700. As described above, the controller 100 may comprise at least one processor 716 and memory means 718. The controller 700 is at least configured to control supplying the electrolyzer 714 with a predefined holding voltage lower than a minimum operating voltage of the electrolyzer 714 if the power providable by the wind turbine 710 to the electrolyzer 714 is lower than a predefined minimum electrolyzer operating power (as described hereinbefore).

[0326] Furthermore, in the present embodiment, the processor 716 and the memory means 718 are additionally configured to execute software modules 702, 704, 706, 710 respectively software code.

[0327] The controller 700 may comprise at least one determining module 702 configured to determine a reference angular speed of the wind turbine 700 based on the predicted wind speed parameter.

[0328] Further, the controller 700 may comprise at least one regulating module 704 configured to regulate the wind turbine 710 by setting a pitch angle p during the (first and / or second) future time window, wherein the pitch angle p is determined based on the determined reference angular speed and the current angular speed of the wind turbine 710. For instance, the regulating module 704 or a further (not shown) determining module is configured to determine the pitch angle p.

[0329] The controller 700 may comprise at least one power predicting module 706 configured to predict the power generatable by the wind turbine 710 during the (first

[0330] HB / HB 240487WO

[0331] 25. November 2024 and / or second) future time window based on the determined reference angular speed. In particular, the power predicting module 706 may predict and estimate, respectively, the power providable by the wind turbine 710 to the electrolyzer 714 during the (first and second) future time window (see also step 201 in Figure 2).

[0332] Furthermore, the controller 700 may comprise at least one controlling module 708 configured to control the at least one electrolyzer 714 of the hydrogen production system 750 by setting an at least almost constant rate of change of current during the second future time window, wherein the rate of change of current is based on the predicted power, if the predicted power providable by the wind turbine 710 to the electrolyzer 714 is equal to or larger than the predefined minimum electrolyzer operating power.

[0333] Further, Tgis torque for control and pitch angle p of the rotor blades and regulates angular speed cor, wherein mechanical power = cor x Tg(equation (d)). Torque may implicitly be controlled by the controller 700. Normally, only speed of a wind turbine may be controlled via pitch p respectively pitch angle p to deliver the needed power. Torque can be calculated by the aforementioned equation (d).

[0334] In particular, the controller 700 can be used both for controlling the at least one wind turbine 710 with respect to the generated power and for controlling the power demand of the at least one electrolyzer 714. Hereby, a constant rate of change of the current density of the electrolyzer cells can be achieved. In particular, said rate of change is smoothened.

[0335] The functioning, in particular, of the controller 700 will be described in more details with the aid of Figure 8. Figure 8 shows a diagram of an embodiment of the (computer-implemented) method according to the present invention. In particular, said embodiment of Figure 8 can be combined with the embodiment of Figure 2. The method serves for operating a hydrogen production system 750 having at least one

[0336] HB / HB 240487WO

[0337] 25. November 2024 wind turbine 710 for supplying the at least one electrolyzer 714 of the hydrogen production system 750 with electrical power.

[0338] In step 801, a determining of a reference angular speed of the wind turbine can be performed based on a wind speed parameter predicted for the wind turbine for a second future time window.

[0339] In step 803, a regulating of the wind turbine 710 can be performed by setting the pitch angle p during respectively for the second future time window. In particular, the controller can send the pitch angle p to the wind turbine controller which will set the pitch angle of the wind turbine 710 accordingly.

[0340] The pitch angle p can be determined based on the determined reference angular speed and the current angular speed of the wind turbine. In particular, the current angular speed of the wind turbine 710 can be fed-back to the controller 700, in particular, for performing an error adjustment. Error adjustment means, in particular, that the pitch angle p will be tuned by the determined reference angular speed if the current angular speed ends up being not of the same value as the determined reference angular speed.

[0341] Furthermore, in step 805, a predicting of power generatable by the wind turbine 710 during the first and / or second future time window can be performed, in particular, based on the determined reference angular speed. The predicting of the power generatable by the wind turbine 710 may comprise, in particular, predicting the power providable by the wind turbine to the electrolyzer during the first future time window. In particular, in step 805 it may be determined by the controller whether power providable by the wind turbine to the electrolyzer is lower than a predefined minimum electrolyzer operating power, in particular, by conducting a comparison operation.

[0342] HB / HB 240487WO

[0343] 25. November 2024 The predicting of the power providable by the wind turbine 710 to the electrolyzer 714 may be based on the reference angular speed and a predefined power speed characteristic curve. For instance, the power speed characteristic curve can be stored in a (not shown) data memory of the controller 700 or a computing equipment connected with the controller).

[0344] The power speed characteristic curve may define the relation between the reference angular speed and generatable or providable power of the specific wind turbine 710 operating with said reference angular speed. For instance, the power speed characteristic curve is provided as an assignment table. A power (value) can be assigned to each reference angular speed (value). Based on the determined reference angular speed (value), the power (value) assigned to said determined reference angular speed (value) can be determined by the controller 700. As has been described above, the wind turbine 710 is operated with said reference angular speed during said future time window by regulating said wind turbine 710 by setting a respective pitch angle p (see step 803). Further, the controller 700 may know the amount of power that can be supplied to the electrolyzer 714 based on the specific power that can be generated by the wind turbine 710.

[0345] In step 807, a controlling of the at least one electrolyzer 714 of the hydrogen production system 750 can be performed by setting an at least almost constant rate of change of current (see also equation (b)) during at least a portion of the second future time window, if the predicted power providable by the wind turbine 710 to the electrolyzer 714 is equal to or larger than the predefined minimum electrolyzer operating power. If the predicted power providable by the wind turbine 710 to the electrolyzer 714 is lower than the predefined minimum electrolyzer operating power, steps 203, 205 and / or 207 of Figure 2 can be performed, as previously described.

[0346] The rate of change of current can be based on the predicted respectively estimated power. In particular, the power transfer from the at least one wind turbine 710 to the at least one electrolyzer 714 can be controlled such that at least an almost steady

[0347] HB / HB 240487WO

[0348] 25. November 2024 ramp rate of power to the at least one electrolyzer 714 can be provided. The rate of change of current preferably during the full second time window can be kept at least almost constant respectively steady.

[0349] Preferably, the rate of change of current may be (only) changeable for the second future time window by a predefined change step. In other words, the rate of change of current can be a stepped rate of change of current wherein the step change has a predefined (and fixed) step size. The predefined step size may be between 2% / s and 10 % / s, preferably between 4% / s and 6% / s (e.g., 5% / s). With a step size between 4% / s and 6% / s a sufficiently constant rate of power respectively current to the at least one electrolyzer can be provided (while the computing effort can be reduced). In this way, the probability of unutilized wind energy can be minimized while ensuring minimal fluctuation since the electrolyzer load can be effectively controlled to respond to forecasted respectively predicted wind speeds.

[0350] It is noted that the described steps can be at least partly performed in parallel to each other.

[0351] In a preferred embodiment, prior to step 807, it can be checked in an optional (not shown) step whether the predicted power satisfies a predefined power criterion. The predefined power criterion can be stored in the (not shown) data memory.

[0352] Step 807 may only be performed if the predicted power criterion is not satisfied, e.g., the predicted power does not lie within the predefined power range. In a further (not shown) optional step of the method, a controlling of the at least one electrolyzer 714 can be performed such that the current density is kept at least almost constant if the predicted power criterion is satisfied. Controlling of the at least one electrolyzer 714 such that the current density is kept at least almost constant may depend on the predicted power. Keeping the current density at least almost constant means, in particular, that there is no rate of change of current during the future time window or from a current time window to a subsequent time window. Controlling the at least one

[0353] HB / HB 240487WO

[0354] 25. November 2024 electrolyzer 714 such that the current density is kept constant may preferably comprise adapting the cell voltage of the electrolyzer? 14 such that the current density is kept constant, in particular, depending on the predicted power.

[0355] For instance, an optimal current density for the cell membrane of an electrolyzer 714 may be in the range of e.g., 2 A / cm2at e.g., cell voltage between 1.5 V and 2 V. To keep the current density at the predefined optimal current density (value), e.g., 2 A / cm2, in particular, under declining wind speeds, it is proposed that if the predefined power criterion is met (e.g., if the predicted power is in the range of 75 % of rated power to 100% rated power), the controller 700 may control the at least electrolyzer 714 such that the current density is kept constant (typically at rated maximum), in particular, by varying the cell voltage within the predefined optimal voltage range, e.g., between 1.5 V and 2 V, such that the current density (value) remains constant. In particular, this is possible up until the predefined minimum rated cell voltage of e.g., 1.5 V is reached. The predefined minimum rated cell voltage may be reached at 75% of rated power.

[0356] If the power criterion is not satisfied, in particular, if the predicted power is in the region below 75% of rated power since changes in wind power may be inconsistent, it follows that changes in current drawn by the at least one electrolyzer 714 and consequently, current density would be inconsistent and abrupt, thus, leading the cell membranes to degradations due to the fluctuations. If the predicted power criterion is not satisfied, a controlling of the at least one electrolyzer 714 of the hydrogen production system 750 can be performed according to step 807.

[0357] Figure 9 shows a diagram of a further embodiment of the method according to the present invention. The operation of the hydrogen production system 650 (or a similar system) will be described hereinafter with the aid of Figure 9. The method of Figure 9 can, in particular, be combined with the method of Figure 2 and, in particular, Figure 8.

[0358] HB / HB 240487WO

[0359] 25. November 2024 In the system 650, as shown in figure 6, where the wind turbines 610. n are connected to a common electrical bus on the substation 654 via one or more strings of medium or high voltage power cables 642, each individual wind turbine 610. n in the cable array network retains its independence in energy production by the means of the aforementioned forewarning speed prediction of the decentral system, in particular, based on the respective controllers 600. n. However, power transfer between the hydrogen power plants 644.1, 644.n on the central or semi-central platform and the wind turbines 61O.n via e.g., a MV (middle voltage) bus may be centrally coordinated via explicit communication among the controllers 600. n, the central controller 652, the electrolyzer controllers 628 and / or the (not shown) wind turbine controllers such that the rate of change of current densities in the electrolyzers, driven by di / dtref, is maintained.

[0360] After starting the method, in step 901, the central controller 652 initializes the index i as per equation (c) to determine k. In particular, in order to ensure optimal energy utilisation at all times, the number of electrolyzers 614.n and wind turbines 61O.n in operation may be determined by means of the central controller 652. Preferably, at all times, the central controller can determine all operable elements in the system, i.e., active, not faulty wind turbines and electrolyzer units / stacks.

[0361] In particular, in step 903 an obtaining may be performed, by means of an (explicit) communication of the central controller 652 with those of the wind turbines 61O.n in the array network: i.) the value of n for the (first and / or second) window length 8 for each j to determine nj and ii.) the corresponding di / dtreffor each k.

[0362] In step 905, an initiating is performed of a check to ensure equal power allocation: is k and j still the same as at start? If no, it is returned to step 901. If yes, the method can be continued with step 907. In particular, the power transfer may be initiated using an equal allocation of system input power made available on the bus collector 656 of the substation 654 by the wind turbines 61O.n according to equation (c). As already described, k is the number of operational electrolyzers 614 (respectively hydrogen

[0363] HB / HB 240487WO

[0364] 25. November 2024 production plants 644., 644.n) and n is the active power available for the window length {w5^_iand j is the number of active wind turbines 61O.n in the array network and the hydrogen production system 650, respectively.

[0365] In step 907, the central controller 652 may relay nj and di / dtrefto each controller of k, and in step 909, for each of k, load control is implemented by the respective electrolyzer power supply units 624 according to di / dtref. The central controller 652 may send power allocation signals di / dtrefto the electrolyzer controllers 628 in realtime, which is harmonized with available n; on the AC power bus 640 of each hydrogen production plant 644.1, 644.n over the window length 8. In this way of explicit, coordinated communication, the need to abruptly modify the electrolyzer load may be avoided since di / dtrefis allocated according to the power projected to be available on the AC power bus 640 and the number of operable electrolyzer 614.

[0366] Figure 10 shows a schematic partial view of a further embodiment of the hydrogen production system 1050 according to the present invention. As can be seen from the partial view, the hydrogen production system 1050 comprises an electrolyzer 1014 and optional electrolyzer auxiliary devices 1030, 1032, such as a compressor 1030 and a (previously described) water intake device 1032.

[0367] In addition, the hydrogen production system 1050 comprises at least one water storage 1098. As can be seen from Figure 10, the at least one water storage is fluid- technically connected with the water intake device 1032 by means of a controllable manifold 1096 and a water pipe network 1092. In particular, the (presently not shown) controller can control said manifold 1096. The elements 1014, 1032, 1098 can be arranged on a decentral, semi-central or central platform. The generated hydrogen is fed via line 1094 to a compressor 1030. The compressed hydrogen (e.g., more than 70 bar) can be fed from the compressor 1030 to a pipeline network or the like.

[0368] (Treated) Water can be delivered by the water intake device 1032 to the electrolyzer 1014 and the water storage 1098 at the same time, in particular, if the power

[0369] HB / HB 240487WO

[0370] 25. November 2024 providable by the wind turbine to the electrolyzer 1014 is at least larger than the predefined minimum electrolyzer operating power (and the fill level of the water storage 1098 is below a maximum allowed fill level).

[0371] As described hereinbefore, the operating of the water intake device 1032 can be stopped and water from the water storage 1098 can be delivered to the electrolyzer 1014 if the power providable by the wind turbine to the electrolyzer 1014 is in a predefined minimum electrolyzer operating power range. In particular, the controller can control the at least one manifold accordingly.

[0372] It is noted that it can also be provided to keep the voltage above the minimum operating voltage of one or more electrolyzers for an extended period of time, thus increasing the productive time of the electrolyzer(s) and the related hydrogen output. The (combined) predicted power production as well as the (combined) predicted possible power savings in the BoP and auxiliary systems of both the wind turbine and the electrolyzer(s) as well as the (combined) predicted available power supply from storage systems and / or additional renewable energy sources as e.g. photovoltaic systems can be used to determine a predicted maximum number of electrolyzers that can be expected to be successfully kept above a minimum required holding voltage threshold for a) electrolyzer stand-by, or b) electrolyzer operation. Also, a prediction can be made about the availability and expected price of external power supply via an optional (partial) grid connection and the control logic can be set up to determine whether this is an economically favorable solution to keep the electrolyzer(s) above the minimum required holding voltage threshold for a) electrolyzer stand-by, or b) electrolyzer operation.

[0373] HB / HB 240487WO

[0374] 25. November 2024

Claims

25. November 2024C l a i m s1. A method for operating a hydrogen production system (150, 550, 650, 750, 1050) having at least one wind turbine (110, 510, 610, 710) for supplying at least one electrolyzer (114, 514, 614, 714, 1014) of the hydrogen production system (150, 550, 650, 750, 1050) with electrical power, comprising: supplying the electrolyzer (114, 514, 614, 714, 1014) with a predefined holding voltage lower than a minimum operating voltage of the electrolyzer (114, 514, 614, 714, 1014) if the power providable by the wind turbine (110, 510, 610, 710) to the electrolyzer (114, 514, 614, 714, 1014) is lower than a predefined minimum electrolyzer operating power.

2. The method according to claim 1, wherein the predefined holding voltage is defined such that the electrolyzer (114, 514, 614, 714, 1014) is driven with a current density that prevents a diffusion of hydrogen from a cathode (113, 513, 613, 1013) of the electrolyzer (114, 514, 614,714. 1014) to an anode (111, 511, 611, 1011) of the electrolyzer (114, 514, 614,714. 1014).

3. The method according to claim 1 or 2, wherein the predefined holding voltage is in a holding voltage range of 1.2 V to 1.6 V, in particular, in the holding voltage range of 1.3 V to 1.5 V.

4. The method according to any of the preceding claims, wherein the power providable by the wind turbine (110, 510, 610, 710) to the electrolyzer (114, 514, 614, 714, 1014) is lower than a predefined minimum electrolyzer operating power if the wind speed at the wind turbine (110, 510, 610, 710) is larger than a predefined cut-in wind speed and lower than a predefinedelectrolyzer wind speed required for generating the predefined minimum electrolyzer operating power, wherein the predefined cut-in wind speed is, in particular, approximately 3 m / s and / or the predefined electrolyzer wind speed is, in particular, approximately 5.5 m / s.

5. The method according to any of the preceding claims, wherein the hydrogen production system (150, 550, 650, 750, 1050) comprises at least one auxiliary power generation device, in particular, a battery energy storage device, wherein the method further comprises: supplying, by the auxiliary power generation device, the electrolyzer (114, 514, 614, 714, 1014) with a predefined holding voltage lower than the minimum operating voltage of the electrolyzer (114, 514, 614, 714, 1014) if no power is generated by the wind turbine (110, 510, 610, 710).

6. The method according to any of the preceding claims, further comprising: reducing a power consumption of at least one electrolyzer auxiliary device if the power providable by the wind turbine (110, 510, 610, 710) to the electrolyzer (114, 514, 614, 714, 1014) is in a predefined minimum electrolyzer operating power range, and / or reducing a power consumption of at least one wind turbine auxiliary device if the power providable by the wind turbine (110, 510, 610, 710) to the electrolyzer (114, 514, 614, 714, 1014) is in a predefined minimum electrolyzer operating power range.

7. The method according to any of the preceding claims, wherein the hydrogen production system (150, 550, 650, 750, 1050) comprises at least one water storage (1098) and at least one water intake device configured to deliver water to the electrolyzer (114, 514, 614, 714, 1014) and to the water storage (1098), wherein the method further comprises:HB / HB 240487WO25. November 2024stopping operating of the water intake device and / or reducing operating capacity and delivering water completely or partially from the water storage (1098) to the electrolyzer (114, 514, 614, 714, 1014) if the power providable by the wind turbine (110, 510, 610, 710) to the electrolyzer (114, 514, 614, 714, 1014) is in a predefined minimum electrolyzer operating power range.

8. The method according to any of the preceding claims, wherein the hydrogen production system (150, 550, 650, 750, 1050) comprises at least one auxiliary power generation device, in particular, a battery energy storage device and / or a fuel cell, wherein the method further comprises: supplying, by the auxiliary power generation device, at least one auxiliary device with electrical power if the power providable by the wind turbine (110, 510, 610, 710) to the electrolyzer (114, 514, 614, 714, 1014) is in a predefined minimum electrolyzer operating power range.

9. The method according to any of the preceding claims, further comprising: predicting the wind speed at the wind turbine (110, 510, 610, 710) for a first future time window, determining, as the power providable by the wind turbine (110, 510, 610, 710) to the electrolyzer an estimated power providable by the wind turbine (110, 510, 610, 710) during the first future time window based on the predicted wind speed, determining whether the estimated power providable by the wind turbine during the first future time window is within a predefined minimum electrolyzer operating power range, and reducing a power consumption of at least one electrolyzer auxiliary device during the first future time window if the determined power providable by the wind turbine (110, 510, 610, 710) to the electrolyzer (114, 514, 614, 714, 1014) during the first future time window is in a predefined minimum electrolyzer operating power range.

10. The method according to any of the preceding claims, further comprising:HB / HB 240487WO25. November 2024determining a reference angular speed of the wind turbine (110, 510, 610, 710) based on at least one wind speed parameter predicted for the wind turbine (110, 510, 610, 710) for a second future time window, regulating the wind turbine by setting a pitch angle during the second future time window, wherein the pitch angle is determined based on the determined reference angular speed and the current angular speed of the wind turbine (110, 510, 610, 710), predicting power providable by the wind turbine during the second future time window based on the determined reference angular speed, controlling the at least one electrolyzer (114, 514, 614, 714, 1014) of the hydrogen production system (150, 550, 650, 750, 1050)by setting an at least almost constant rate of change of current during at least a portion of the second future time window, wherein the rate of change of current is based on the predicted power, if the power providable by the wind turbine (110, 510, 610, 710) to the electrolyzer (114, 514, 614, 714, 1014) is equal or larger than the predefined minimum electrolyzer operating power.

11. The method according to claim 10, wherein the at least one predicted wind speed parameter is a predicted wind speed and / or wind direction at the wind turbine (110, 510, 610, 710), and wherein the at least one predicted wind speed parameter is based on a wind measuring, in particular, conducted by a LIDAR equipment.

11. The method according to any of the preceding claims, wherein the first future time window and / or the second future time window has a time length between 1 s and 120 s, preferably between 20 s and 50 s.

12. The method according to claim 10 or 11, wherein the rate of change of current is a stepped rate of change of current with a predefined step size,HB / HB 240487WO25. November 2024wherein the predefined step size is, in particular, between 2% / s and 10 % / s, preferably between 4% / s and 6% / s.

13. The method according to any of the preceding claims 10 to 12, further comprising: providing a predefined power speed characteristic curve, and wherein the predicting of power providable by the wind turbine (1) to the electrolyzer during the second future time window is based on the reference angular speed and the predefined power speed characteristic curve.

14. The method according to any of the preceding claims 10 to 13, further comprising: determining whether the predicted power satisfies a predefined power criterion, and controlling the at least one electrolyzer (114, 514, 614, 714, 1014) of the hydrogen production system (150, 550, 650, 750, 1050) by the at least almost constant rate of change of current during the second future time window only if the predicted power criterion is not satisfied, wherein the controlling of the at least one electrolyzer (114, 514, 614, 714, 1014) is, in particular, performed such that the current density is kept at least almost constant if the predicted power criterion is satisfied.

15. The method according to any of the preceding claims 10 to 14, wherein the hydrogen production system (150, 550, 650, 750, 1050) comprises a plurality of wind turbines (110, 510, 610, 710) for supplying the at least one electrolyzer (114, 514, 614, 714, 1014) with electrical power, wherein the controlling of the at least one electrolyzer (114, 514, 614, 714, 1014) of the hydrogen production system (150, 550, 650, 750, 1050) comprises centrally coordinating the power transfer from the plurality of wind turbines to the electrolyzer (114, 514, 614, 714, 1014) such that the rate of change of current is kept at least almost constant,HB / HB 240487WO25. November 2024and / or the hydrogen production system (150, 550, 650, 750, 1050) comprises a plurality of electrolyzers (114, 514, 614, 714, 1014), wherein the controlling of the plurality of electrolyzers (114, 514, 614, 714, 1014) of the hydrogen production system (150, 550, 650, 750, 1050)comprises centrally coordinating the power transfer from the at least one wind turbine (110, 510, 610, 710) to the plurality of electrolyzers (114, 514, 614, 714, 1014) such that the rate of change of current is kept at least almost constant for each of the plurality of electrolyzers (114, 514, 614, 714, 1014).

16. The method according to any of the preceding claims, wherein the hydrogen production system (150, 550, 650, 750, 1050) comprises at least one LIDAR device with at least one infrared laser unit and at least one forecasting device, configured to, the method comprising: forecasting the wind speed at the wind turbine (110, 510, 610, 710) for a future time period based on the sensor data of the LIDAR device, wherein the future time period is at least 15 minutes, preferably 30 minutes, forecasting the electrical energy providable by the wind turbine (110, 510, 610, 710) during said future time period, and controlling the electrolyzer (114, 514, 614, 714, 1014) based on the forecasted electrical energy.

17. A controller (100, 500, 600, 700) for controlling a hydrogen production system (150, 550, 650, 750, 1050) having at least one wind turbine (110, 510, 610, 710) for supplying at least one electrolyzer (114, 514, 614, 714, 1014) of the hydrogen production system (150, 550, 650, 750, 1050) with electrical power, the controller (100, 500, 600, 700) is configured to control: supplying the electrolyzer (114, 514, 614, 714, 1014) with a predefined holding voltage lower than a minimum operating voltage of the electrolyzer (114, 514, 614, 714, 1014) if the power providable by the wind turbine (110, 510, 610, 710)HB / HB 240487WO25. November 2024to the electrolyzer (114, 514, 614, 714, 1014) is lower than a predefined minimum electrolyzer operating power.

18. The controller according to claim 17, further comprising: at least one determining module (702) configured to determine a reference angular speed of the wind turbine (110, 510, 610, 710) based on at least one predicted wind speed parameter for the wind turbine (110, 510, 610, 710) for a second future time window, at least one regulating module (704) configured to regulate the wind turbine (110, 510, 610, 710) by setting a pitch angle during the second future time window, wherein the pitch angle is determined based on the determined reference angular speed and the current angular speed of the wind turbine (110, 510, 610, 710), at least one power predicting module (706) configured to predict power providable by the wind turbine during the second future time window based on the determined reference angular speed, and at least one controlling module (708) configured to control the at least one electrolyzer (114, 514, 614, 714, 1014) of the hydrogen production system (150, 550, 650, 750, 1050)by setting an at least almost constant rate of change of current during at least a portion of the second future time window, wherein the rate of change of current is based on the predicted power, if the power providable by the wind turbine (110, 510, 610, 710) to the electrolyzer (114, 514, 614, 714, 1014) is equal or larger than the predefined minimum electrolyzer operating power.

19. A hydrogen production system (150, 550, 650, 750, 1050), comprising: at least one hydrogen production plant having the at least one electrolyzer (114, 514, 614, 714, 1014), at least one wind turbine (110, 510, 610, 710) configured to supply at least the at least one electrolyzer (114, 514, 614, 714, 1014) with electrical power, and at least one controller (100, 500, 600, 700) according to claim 17 or 18.HB / HB 240487WO25. November 202420. The hydrogen production system (150, 550, 650, 750, 1050) according to claim 19, further comprising: at least one water intake device (1098) configured to deliver water to the electrolyzer (114, 514, 614, 714, 1014) and to at least one water storage (1098) of the hydrogen production system (150, 550, 650, 750, 1050), wherein the water storage is configured to store the delivered water, and / or at least one auxiliary power generation device, in particular, a battery energy storage device.HB / HB 240487WO25. November 2024

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