Offshore wind farm

Abstract

The invention relates to an offshore wind farm (100, 200, 300), comprising at least one offshore wind turbine (102, 202, 302), and at least one auxiliary device (104, 204), at least one electrolyzer plant (106, 206, 306) electrically connected to the at least one offshore wind turbine (102, 202, 302) such that the at least one electrolyzer plant (106, 206, 306) is suppliable with electrical energy generated by the at least one offshore wind turbine (102, 202, 302), at least one storage tank (108, 208, 308) fluidably connected to the at least one electrolyzer plant (106, 206, 306) and configured to store at least a portion of the fluid medium produced by the at least one electrolyzer plant (106, 206, 306), at least one fluid-fired turbine device (110, 210, 310) with at least one electrical generator (112, 212, 312), wherein the at least one fluid-fired turbine device (110, 210, 310) is fluidably connected to the at least one storage tank (108, 208, 308) and configured to generate electrical energy, based on the fluid medium provided by the storage tank (108, 208, 308), wherein at least the at least one auxiliary device (104, 204) is electrically connected to the at least one electrical generator (112, 212, 312) such that the at least one auxiliary device (104, 204) is suppliable with the electrical energy generated by the at least one electrical generator (112, 212, 312).

Description

[0001] Offshore wind farm

[0002] The invention relates to an offshore wind farm, comprising at least one wind turbine, and at least one auxiliary device. Furthermore, the invention relates to a method (for operating an offshore wind farm), a computer program, and a controller for an offshore wind farm.

[0003] In the present time, electrical power generation systems are increasingly used for the provision of electrical energy, in which the 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.

[0004] More particularly, wind energy systems and wind farms, respectively, comprising at least one wind turbine 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.

[0005] In prior art, an offshore wind farm has 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 f 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.

[0006] An offshore wind farm generally comprises at least one auxiliary device, in particular, a plurality of auxiliary devices. Exemplified and non-exhaustive examples of auxiliary devices are hydraulics, pumps, heaters etc. for lubrication, cooling, climate conditioning and so on. The at least one auxiliary device is needed to enable an efficiently, stably and safely running of the offshore wind farm, in particular, the at least one offshore wind turbine of the offshore wind farm. During normal operation of an offshore wind farm, i.e., when all or at least a portion of the at least one offshore wind turbine generate electrical energy, the at least one auxiliary device is supplied with (a portion of) the electrical energy generated by the at least one offshore wind turbine of the offshore wind farm.

[0007] In an idling condition of the offshore wind farm, i.e., when all of the offshore wind turbines are (each) in the idling state, and thus, do not generate electrical energy, according to the prior art, the at least one auxiliary device must be supplied with electrical energy from the external grid. However, in case of off-grid respectively grid- isolated respectively grid-decoupled offshore wind farms, the integrity of the constituting wind turbines may would become compromised if the at least one auxiliary device does not receive needed energy during the idling condition. Accordingly, the installation of an off-grid offshore wind farm is hardly possible in the prior art.

[0008] Further, in a black start condition of the offshore wind farm, i.e., if a black starting of the offshore wind farm should be performed, according to prior art a connection to the external grid is also necessary in order to provide sufficient electrical energy for enabling a black start. This makes the installation and operation of an off-grid offshore wind farm even more difficult.

[0009] Document US 8000 840 B2 proposes a method to black start an offshore wind farm by providing power from a first offshore wind turbine to a further offshore wind turbine, wherein the further offshore wind turbine once started and generating electrical energy may in turn power at least one further offshore wind turbine in the offshore wind farm for their starting up. However, the solution does provide a solution which would enable an installation and operation of an off-grid offshore wind farm. According to US 8000 840 B2, electrical energy from some offshore wind turbines is always required to start others. Thus, all offshore wind turbines in the offshore wind farm cannot be black started simultaneously without a connection to an external grid. In addition to the described limitations of US 8000 840 B2, continuous supply of power to the at least one auxiliary device of the offshore wind farm is not guaranteed during idling respectively in the idling condition.

[0010] Therefore, the object of the present invention is to provide an offshore wind farm in which the issues of the prior art are at least reduced and, in particular, in which a supplying of the at least one auxiliary device of the offshore wind farm is guaranteed in the idling condition independently of an electrical connection of the offshore wind farm to an external grid.

[0011] The object is solved according to a first aspect of the invention by an offshore wind farm according to claim 1. The offshore wind farm comprises at least one offshore wind turbine. The offshore wind farm comprises at least one auxiliary device. The offshore wind farm comprises at least one electrolyzer plant electrically connected to the at least one offshore wind turbine such that the at least one electrolyzer plant is suppliable with electrical energy generated by the at least one offshore wind turbine. The offshore wind farm comprises at least one storage tank fluidably connected to the at least one electrolyzer plant. The at least one electrolyzer plant is configured to store at least a portion of the fluid medium produced by the at least one electrolyzer plant. The offshore wind farm comprises at least one fluid-fired turbine device with at least one electrical generator. The at least one fluid-fired turbine device is fluidably connected to the at least one storage tank. The at least one fluid-fired turbine device is configured to generate electrical energy based on the fluid medium provided by the storage tank. At least the at least one auxiliary device is electrically connected to the at least one electrical generator such that the at least one auxiliary device is suppliable with the electrical energy generated by the at least one electrical generator.

[0012] In contrast to the prior art, according to the present invention, by providing an offshore wind farm with a loop feed arrangement, comprising at least one electrolyzer plant, at least one storage tank and at least one fluid-fired turbine device, the issues of the prior art are at least reduced and, in particular, a supplying of the at least one auxiliary device of the offshore wind farm is guaranteed in the idling condition of the offshore wind farm independently of an electrical connection of the offshore wind farm to an external grid.

[0013] The offshore wind farm according to the invention comprises one or more offshore structure / s which is / are in particular installed at an offshore site, such as the sea. At least one of the one or more offshore structure / s may be an offshore wind turbine. The at least one offshore wind turbine may be a floatable offshore wind turbine or non-floatable offshore wind turbine.

[0014] According to one embodiment of the offshore wind farm of the invention, the offshore wind farm may comprise a plurality of offshore wind turbines. Preferably, the offshore wind farm comprises one, in particular, a plurality of strings of offshore wind turbines. In particular, each string may comprise a plurality of offshore wind turbines (e.g. between four and twelve).

[0015] According to a further embodiment of the offshore wind farm of the invention, the offshore wind farm may comprise, as a further offshore structure, at least one (floatable or non-floatable) substation. The at least one substation may comprise at least one transformer. The at least one offshore wind turbine may be electrically connected to the substation. In particular, the at least one string having a plurality of offshore wind turbines may be electrically connected to the substation.

[0016] According to one embodiment of the offshore wind farm of the invention, the offshore wind farm may comprise an electrical connection to at least one external grid, e.g., via the at least one substation. The offshore-substation may be connected to an onshore- substation, which may be connected to an external grid, such as a public grid. As will be described hereinafter, according to a preferred embodiment of the offshore wind farm, the offshore wind farm may be an off-grid offshore wind farm, i.e., an offshore windfarm having no electrical connection to an external grid.

[0017] Furthermore, the offshore wind farm comprises at least one auxiliary device. Preferably, the offshore wind farm comprises a plurality of auxiliary devices. The at least one auxiliary device may be a stand-alone device respectively a stand-alone structure or may be comprised by another offshore structure of the offshore wind farms, such as the at least one offshore wind turbine (or an optional offshore substation).

[0018] An auxiliary device of an offshore wind farm means, in particular, an electrically operated consumer required for the operation of the offshore wind farm, in particular, for the operation of the at least one offshore wind turbine. Exemplified and non- exhaustive examples of auxiliary devices are hydraulics, pumps, heaters etc. for lubrication, cooling, climate conditioning and so on. An auxiliary device is needed to enable an efficiently, stably and safely running of the offshore wind farm, in particular, an offshore wind turbine of the offshore wind farm. During normal operation of the offshore wind farm, i.e., when all or at least a portion of the preferably plurality of wind turbines generate electrical energy, the at least one auxiliary device may be supplied with (a portion of) the electrical energy generated by the offshore wind turbines of the offshore wind farm. According to the invention, in order to supply the at least one auxiliary device not only in the normal operation state of the offshore wind farm with sufficient electrical energy but in all possible operation states of the offshore wind farm, including an idling state of the offshore wind farm, an implementation of a specific loop feed arrangement is proposed. The loop feed arrangement may be configured to supply the at least one auxiliary device with sufficient electrical energy independently of the actual state of the at least one offshore wind turbine and in particular independently of an electrical connection of the offshore wind farm to an external grid.

[0019] The loop feed arrangement may comprise at least one electrolyzer plant, at least one storage tank, and at least one fluid-fired turbine device.

[0020] The at least one electrolyzer plant is electrically connected to the at least one offshore wind turbine, in particular via an internal grid, comprising one or more electrical energy cables. Preferably, the at least one electrolyzer plant is connected to the at least one offshore wind turbine via an optional offshore substation. The electrolyzer plant is electrically connectable to the at least one offshore wind turbine such that the at least one electrolyzer plant is suppliable with electrical energy generated by the at least one offshore wind turbine. In particular, at least a portion of the overall generated electrical energy by the preferably plurality of offshore wind turbines of the offshore wind farm can be fed to the at least one electrolyzer plant.

[0021] An electrolyzer plant may be arranged on a (central) platform or in a decentral manner, e.g., distributed on a plurality of offshore structures of the offshore wind farm, such as the offshore wind turbines and / or the substation of the offshore wind farm. The electrolyzer plant may comprise at least one electrolyzer module. The at least one electrolyzer module may be configured to produce respectively generate a fluid medium, in particular, in form of hydrogen and / or ammonia. In other words, the at least one fluid medium produced by the electrolyzer plant may hydrogen and / or ammonia. The electrolyzer module may comprise at least one electrolyzer or electrolyzer stack. For example, a proton exchange membrane (PEM) electrolyzer may be provided. 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 a high temperature electrolyzer or the like.

[0022] The electrolyzer plant may comprise at least one (hydrogen) processing module respectively (hydrogen) finishing module. The at least one processing module may be configured to process the (wet) hydrogen produced by the at least one electrolyzer module. 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 module 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.

[0023] 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. 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 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.

[0024] Preferably additionally, according to a further embodiment of the offshore wind farm of 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.

[0025] 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).

[0026] Furthermore, the at least one electrolyzer plant may comprise at least one water treatment module. 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 module of the electrolyzer plant to produce the fluid medium, such as hydrogen. In particular, the water treatment module can treat seawater for the electrolysis process to be performed.

[0027] 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 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".

[0028] Alternatively or additionally, the at least one electrolyzer plant may comprise 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.

[0029] Further, it shall be understood that the at least one electrolyzer plant may comprise less modules, further modules, or other modules. For instance, the electrolyzer plant may additionally comprise an intake and filtration module.

[0030] According to the invention, the at least one electrolyzer plant is fluidably connected (e.g., via an internal fluid network, in particular via at least one fluid pipe of the fluid network) to at least one storage tank. The at least one storage tank is configured to store at least a portion of the fluid medium (e.g., hydrogen or ammonia) produced respectively generated by the at least one electrolyzer plant. For instance, the at least one storage tank can be arranged on a stand-alone offshore structure and / or on a platform of the electrolyzer plant and / or on the offshore substation.

[0031] Further, according to the invention, the offshore wind farm comprises at least one fluid-fired turbine device with at least one electrical generator and in particular at least one fluid-fired turbine driving the electrical generator. Said at least one fluid- fired turbine device serves to generate electrical energy. The fluid-fired turbine device is fluidably connected (e.g., via the internal fluid network, in particular via at least one fluid pipe of the fluid network) to the at least one storage tank. The at least one fluid- fired turbine device with at least one electrical (synchronous) generator is configured to generate electrical energy, based on the fluid medium provided by the storage tank. In other words, the fluid-fired turbine device can be supplied with the stored hydrogen and / or ammonia as fuel. In particular, the fluid-fired turbine device is a hydrogen- or ammonia-fired turbine device.

[0032] The at least the at least one auxiliary device is electrically connected (e.g., via the internal grid, comprising power cables respectively energy) to the at least one electrical generator of the fluid-fired turbine device such that the at least one auxiliary device is suppliable with the electrical energy generated by the at least one electrical generator. In other words, the one or more auxiliary device are supplied with electrical energy generated by the fluid-fired turbine device.

[0033] According to a preferred embodiment of the offshore wind farm according to the present invention, the offshore wind farm may comprise at least one controller (with at least one processor and memory means). The at least one controller may be configured to control at least the at least one fluid-fired turbine device based on at least one wind farm condition. A controlling of the at least one fluid-fired turbine device may at least comprise an activating and deactivating of the fluid-fired turbine device. The controlling may depend on the current condition of the offshore wind farm respectively the current state of the offshore wind farm. For instance, the wind farm condition may indicate whether the at least one auxiliary device requires electrical energy from the at least one fluid-fired turbine device. In other words, the controlling by the controller may depend on the electrical energy required by the at least one auxiliary device. The operation of the fluid-fired turbine device can be controlled in an easy manner.

[0034] The controller may be implemented in the central wind farm controller or as a standalone controller. Preferably, according to a further embodiment, the at least one controller may be further configured to control the fluid flow from the storage tank to the at least one fluid-fired turbine device. In particular, the controller may be configured to control at least one valve arranged in the fluid connection (e.g., at the outlet of the storage tank and / or at the inlet of the fluid-fired turbine device) between the at least one fluid- fired turbine device and the storage tank. The controlling may comprise at least an opening and closing of the at least one valve. Preferably, the controlling by the controller may depend on the fuel required by the at least one fluid-fired turbine device. The operation of the fluid-fired turbine device can be controlled in an easy manner.

[0035] According to a further embodiment of the offshore wind farm, the at least one controller may be further configured to control the fluid flow (of the produced gas and / or liquid) (through the internal fluid network) from the at least one electrolyzer plant to the at least one storage tank. In particular, the controller may be configured to control at least one valve (respectively a manifold with valve function or the like) arranged in the fluid connection (e.g., at the outlet of the electrolyzer plant and / or at the inlet of the storage tank) between the electrolyzer plant and the storage tank. The controlling may comprise at least an opening and closing of the at least one valve respectively manifold. Preferably, the controlling by the controller may depend on the storage state, in particular, the fill level, of the at least one storage tank. For instance, at least one predefined minimum fill level may be provided. For example, if a fill level detector detects that the current fill level of the storage tank is below the predefined minimum fill level, a refilling can be initiated by the detector, e.g., by transmitting a respective information to the controller. The controller can then control said valve and in particular the electrolyzer plant such that the fluid medium is produced and fed to the storage tank. The operation of the at least one storage tank can be controlled in an easy manner. Alternatively or additionally, the controller can be configured to control the at least one electrolyzer plant. The controlling may at least comprise an activating and deactivating of the electrolyzer plant. For example, the controlling by the controller may depend on the storage state, in particular, the fill level, of the at least one storage tank (as previously described). The operation of the at least one electrolyzer plant can be controlled in an easy manner. In variants of the invention, the electrolyzer plant can be continuously operated. For instance, the fluid medium produced can be continuously produced for a second target definition, i.e., fed to an external gas and / or liquid network and / or an outlet for gas and / or liquid vessels or the like.

[0036] According to a further preferred embodiment of the offshore wind farm according to the invention, the at least one wind farm condition comprises an idling condition. The idling condition is in particular a full-idling condition of the offshore wind farm. In a full-idling condition, all offshore wind turbines of the offshore wind farm are in the idling state respectively idling mode. In other words, none of the offshore wind turbines of the offshore wind farm generates electrical energy in the idling condition respectively idling state.

[0037] The at least one controller may be configured to control at least the at least one fluid- fired turbine device, e.g., by activating the at least one fluid-fired turbine device, upon detecting of the idling condition, in particular, in order to supply at least the at least one auxiliary device with the generated electrical energy for enabling an operating of the auxiliary device without the need of an energy supply from an external grid. In a particular secure manner, the operation of the at least one auxiliary device can be ensured also in the case of a provision of the idling condition of the offshore wind farm.

[0038] According to a further preferred embodiment of the offshore wind farm according to the present invention, the at least one offshore wind turbine may be electrically connected (via the internal grid) to the at least one electrical generator (of the at least one fluid-fired turbine device) such that the at least one offshore wind turbine is suppliable with the electrical energy generated by respectively from the at least one electrical generator of the fluid-fired turbine device. In other words, the at least one offshore wind turbine can be supplied with the generated electrical energy. By enabling a flow of electrical energy from the at least one electrical generator of fluid- fired turbine device to the at least one offshore wind turbine, a black starting of the at least one offshore wind turbine is enabled (independently of an electrical connection of the offshore wind farm to an electrical grid).

[0039] According to a further embodiment of the offshore wind farm according to the present invention, the at least one wind farm condition comprises a black start condition. A black start condition means, in particular, a state of the offshore wind farm respectively condition of the offshore wind farm in which a black starting of the at least one offshore wind turbine should be performed. The at least one controller may be configured to control at least the at least one fluid-fired turbine device, in particular, by activating and operating the at least one fluid-fired turbine device, upon detecting of the black start condition, in particular in order to supply at least the at least one offshore wind turbine with the generated electrical energy for enabling a black starting of the at least one offshore wind turbine.

[0040] According to a further embodiment, the at least one fluid-fired turbine device can only be activated by the at least one controller if one wind farm condition of the at least one predefined wind farm condition (e.g., an idling condition, a black start condition, and a sub-idling condition) is detected. For instance, measured sensor data of the offshore wind farm can be (continuously) evaluated by the at least one controller in order to detect a predefined wind farm condition that requires an activating of the at least one fluid-fired turbine device in order to generate electrical energy.

[0041] As has already been described, according to a preferred embodiment of the offshore wind farm according to the present invention, the offshore wind farm may comprise a plurality of offshore wind turbines. The plurality of offshore wind turbines may be electrically connected to at least one substation of the offshore wind farm. The at least one substation may comprise at least one transformer and the at least one fluid-fired turbine device. The at least one transformer may be configured to convert the generated electrical energy, in particular, between different voltage levels. Preferably, the at least one electrolyzer plant is connected to the at least one offshore wind turbine via the substation. In particular, a central electrical bus may run from the substation (e.g., the at least one transformer) to the at least one electrolyzer plant of the offshore wind farm.

[0042] According to a preferred embodiment of the offshore wind farm according to the present invention, the offshore wind farm may comprise a plurality of offshore wind turbines. The at least one wind farm condition may comprise a sub-idling condition of the offshore wind farm. In the sub-idling condition, only a portion of the plurality of offshore wind turbines of the offshore wind farm may be in an idling state. In other words, at least one first offshore wind turbine of the plurality of offshore wind turbines is in an idling condition, and thus, does not generate electrical energy, and at least one second offshore wind turbine of the plurality of offshore wind turbines is in a non-idling condition, and thus, does generate electrical energy.

[0043] The at least one controller is configured to control at least the at least one fluid-fired turbine device, in particular, by activating and operating the at least one fluid-fired turbine device, upon detecting of the sub-idling condition such that all of the at least one auxiliary device may be supplied with the electrical energy generated by the at least one electrical generator of the fluid-fired turbine device. In other words, the energy produced by the at least one offshore wind turbine of the plurality of offshore wind turbines which is in a non-idling condition is not fed to the at least one auxiliary device (but all auxiliary devices are solely supplied with electrical energy generated by the at least one electrical generator of the fluid-fired turbine device.

[0044] According to a preferred embodiment of the offshore wind farm according to the present invention, the at least one controller may be configured to control the at least one turbine not in a sub-idling state of the offshore wind farm such that all energy generated by the at least one offshore wind turbine not in the idling state is feed to the at least one electrolyzer plant and / or to an external grid.

[0045] During the idling of one or a plurality but not all of the offshore wind turbines in the offshore wind farm, the electrical (synchronous) generator may be controlled respectively operated to feed the needed power respectively energy of the at least one auxiliary device such that the total energy of the operational offshore wind turbines can be fully utilized for electricity production and / or the electrolyzer plant for te production capacity of hydrogen or ammonia and not reduced by the auxiliary consumption of the idling wind turbines.

[0046] According to a further embodiment of the offshore wind farm according to the present invention, the at least one fluid-fired turbine device may be configured to generate electrical energy of at least 1 % of the rated nameplate of the offshore wind farm (e.g., between 1 % and 2 %), in particular, of approximately 1 % of the rated nameplate of the offshore wind farm. In particular, in the case that the offshore wind farm is in the idling condition, the synchronous generator may adjust its power generation to meet the full capacity of the demand of the at least one auxiliary device of the wind farm. To achieve this, it has been determined that the total auxiliary power consumption of an idling wind farm is appr. 1% of the rated nameplate of the wind farm. Therefore, the hydrogen- or ammonia-fired turbine and its (synchronous) generator of the fluid-fired turbine device can be sized according to this minimum capacity requirement (alongside the corresponding storage capacity needed for startup, e.g., commissioning, test run etc.).

[0047] According to a further embodiment of the offshore wind farm according to the application, the storage capacity of the at least one storage tank may be selected such that the at least one fluid-fired turbine device is operable for at least two days, preferably, at least seven days, particularly preferably at least fourteen days (and at most forty days). Preferably the storage tank has a fill capacity for enabling an operation of the fluid-fired turbine device (in particular, 1 % of the rated nameplate of the offshore wind farm) for generating energy for all auxiliary devices for at least 14 days, in particular, between 14 days and 21 days. A secure operation of the auxiliary devices of the offshore wind farm can be guaranteed.

[0048] As already described, the offshore wind farm may comprise an electrical connection to an external grid, e.g., via an offshore substation and an onshore substation. For instance, the offshore wind farm can transmit at least a portion of the generated electrical energy to the external grid, such as a public grid. By way of example, the main purpose of such an offshore wind farm may be to generate electrical energy and to feed said energy into an external grid.

[0049] According to a particularly preferred embodiment of the offshore wind farm according to the present invention, the offshore wind farm may be an off-grid offshore wind farm. An off-grid offshore wind farm means, in particular, an offshore wind farm without having an electrical connection to an external grid. Preferably, the off-grid offshore wind farm comprises the at least one electrolyzer plant configured to produce hydrogen and / or ammonia not only for a first target definition in the form of the (previously described) at least one storage tank respectively the (previously described) fluid-fired turbine device of the offshore wind farm but also for a second target definition, such as an external gas and / or liquid network and / or at least one gas outlet for gas and / or liquid vessels or the like. In particular, a fluid connection to an onshore external gas network may be installable with much less effort and in particular costs compared to an electrical connection of an onshore external electrical grid.

[0050] A further aspect of the invention is a method, in particular, a computer-implemented method. The method comprises: controlling a supplying of at least one electrolyzer plant of an offshore wind farm with electrically energy generated by at least one offshore wind turbine of the offshore wind farm, controlling a fluid flow of the fluid medium produced by the at least one electrolyzer plant to at least one storage tank of the offshore wind farm, controlling a fluid flow of the stored fluid medium from the at least one storage tank to at least one fluid-fired turbine device with at least one electrical generator of the offshore wind farm, and controlling the at least one fluid-fired turbine device such that at least at least one auxiliary device of the offshore wind farm is supplied with electrical energy generated by the at least one electrical generator.

[0051] The method can in particular be used for operating and / or controlling a previously described offshore wind farm, in particular, an offshore wind farm according to claim 1.

[0052] 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 (of a previously described offshore wind farm), cause the processor to execute and / or control the method previously described method, in particular, according to claim 12.

[0053] A still further aspect of the invention is a controller for an offshore wind farm, in particular, a previously described offshore wind farm (according to claim 1), comprising at least one processor configured to execute the previously described computer program (according to claim 13).

[0054] It is noted that expressions such as "first", "second", etc. do not specify a series order, but only serve to distinguish between two elements (e.g., offshore wind turbines, target definitions, etc.).

[0055] The features of the offshore wind farms, 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.

[0056] 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.

[0057] In the figures show:

[0058] Fig. 1 a schematic view of an embodiment of an offshore wind farm according to the present invention,

[0059] Fig. 2 a schematic view of a further embodiment of an offshore wind farm according to the present invention with an embodiment of a controller according to the present invention,

[0060] Fig. 3 a schematic view of a further embodiment of an offshore wind farm according to the present invention with a further embodiment of a controller according to the present invention, and

[0061] Fig. 4 a diagram of an embodiment of a method according to the present invention.

[0062] Similar reference signs in different Figures indicate similar elements.

[0063] Figure 1 shows a schematic view of an embodiment of an offshore wind farm 100 according to the present invention.

[0064] As can be seen from figure 1, the offshore wind farm 100 comprises at least one offshore wind turbine 102 and at least one auxiliary device 104. Preferably, an offshore wind farm 100 may comprise two or more offshore wind turbines 102 and / or two or more auxiliary devices 104. The at least one offshore wind farm 102 is configured to convert the kinetic wind energy into electrical energy.

[0065] Merely by way of example, the at least one auxiliary device 104 is formed as a standalone device respectively stand-alone offshore structure. In other variants of the present invention, the at least one auxiliary device can be implemented at respectively in another offshore structure respectively device, such as an offshore wind turbine, a (not shown) substation, etc. Exemplified and non-exhaustive examples of auxiliary devices 104 are hydraulics, pumps, heaters etc. for lubrication, cooling, climate conditioning and so on.

[0066] During normal operation of the offshore wind farm 100, i.e., when all or at least a portion of the plurality of offshore wind turbines 102 generate electrical energy, the at least one auxiliary device 104 may be supplied with (a portion of) the electrical energy generated by the offshore wind turbines 102 of the offshore wind farm 100, in particular, via an internal grid, e.g., via the electric connection 109.

[0067] Further, as can be seen from figure 1, the offshore wind farm 100 may comprise a loop feed arrangement 111. The loop feed arrangement 111 may be configured to supply the at least one auxiliary device 104 with sufficient electrical energy independently of the actual state of the at least one offshore wind turbine 102 of the offshore wind farm 100. In the present embodiment, the loop feed arrangement 111 comprises at least one electrolyzer plant 106, at least one storage tank 108, and at least one fluid-fired turbine device 110 with at least one electrical generator 112.

[0068] The at least one electrolyzer plant 106 is electrically connected to the at least one offshore wind turbine 102 of the offshore wind farm, in particular, via the internal grid, e.g., via an electrical connection 114. The electrolyzer plant 106 is electrically connectable such that the at least one electrolyzer plant 106 is suppliable with electrical energy generated by the at least one offshore wind turbine 102. In particular, at least a portion of the overall generated electrical energy by the at least one offshore wind turbine 102 of the offshore wind farm 100 is fed to the at least one electrolyzer plant 106 in order to enable the production of a burnable fluid medium.

[0069] An electrolyzer plant 106 may be arranged on a (not shown) (central) platform or a plurality of modules of the electrolyzer plant 106 may be arranged in a (not shown) decentral manner, e.g., distributed on at least two offshore structures of the offshore wind farm 100. The electrolyzer plant 106 may be configured to produce respectively generate hydrogen and / or ammonia. In other words, the at least one fluid medium produced by the electrolyzer plant may hydrogen and / or ammonia.

[0070] According to the invention, the at least one electrolyzer plant 106 is fluidably connected (e.g., via at least one fluid pipe 116) to at least one storage tank 108. The storage tank 108 is configured to store at least a portion of the fluid medium produced respectively generated by the at least one electrolyzer plant 106. For instance, the at least one storage tank 108 can be arranged as a stand-alone offshore structure and / or on a platform of the electrolyzer plant 106 and / or an optional offshore substation.

[0071] Further, according to the invention, the offshore wind farm 100 comprises at least one fluid-fired turbine device 110 with at least one electrical generator 112. Said at least one fluid-fired turbine device 110 serves to generate electrical energy. The fluid-fired turbine device 110 is fluidably connected (e.g., via at least one fluid pipe 118 of an internal fluid network) to the at least one storage tank 108. The at least one fluid-fired turbine device 110 with at least one electrical generator 112 is configured to generate electrical energy based on the fluid medium provided by the storage tank 108. In other words, the fluid-fired turbine device 110 can be supplied with the stored hydrogen and / or ammonia as fuel. Said fuel is burned in the fluid-fired turbine of the fluid-fired turbine device 110 in order to drive the electrical generator 112.

[0072] The at least the at least one auxiliary device 104 is electrically connected (e.g., via at least one energy cable 120 of the internal electrical grid) to the at least one electrical generator 112 of the fluid-fired turbine device 110 such that the at least one auxiliary device 104 is suppliable with the electrical energy generated by the at least one electrical generator 112.

[0073] Figure 2 shows a schematic view of a further embodiment of an offshore wind farm 200 according to the present invention with an embodiment of a controller 250 according to the present invention. In order to avoid repetitions, in the following only the differences between the embodiment of Figure 1 and the embodiment of Figure 2 are essentially described. With regard to the other elements of the offshore wind farm 200 it is essentially referred to the previous embodiment.

[0074] The depicted offshore wind farm 200 comprises a plurality of offshore wind turbines 202 connected to at least one substation 222. The at least one substation 222 may comprise at least one transformer 224 and preferably the at least one fluid-fired turbine device 210 with at least one electrical generator 212 arranged on a platform of the substation 222.

[0075] As can be further seen from figure 2, by way of example only, each offshore wind turbine 202 comprises at least one auxiliary device 204. It shall be understood that each offshore wind turbine may comprise two or more auxiliary devices and / or that further (not shown) auxiliary devices can be provided, e.g., on the substation 222, and / or as stand-alone structures.

[0076] The at least one electrolyzer plant 206 is electrically connected to the at least one offshore wind turbine 202 via the substation 222 and at least one electrical connection 214 of the internal grid. The at least one auxiliary device 204 is electrically connected to the at least one fluid-fired turbine device 210 via at least one electrical connection 220 of the internal grid.

[0077] The electrolyzer plant 206 may be formed by a plurality of modules arranged on a central platform 236 or distributed on at least two offshore structures of the offshore wind farm 200. The depicted electrolyzer plant 206 comprises at least one electrolyzer module 226. The at least one electrolyzer module 226 may be configured to produce respectively generate hydrogen. The electrolyzer module 226 may comprise at least one electrolyzer or electrolyzer stack. For example, a proton exchange membrane (PEM) electrolyzer may be provided.

[0078] The electrolyzer plant 226 may comprise at least one (hydrogen) processing module respectively (hydrogen) finishing module, e.g., arranged on a platform 228. 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. 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.

[0079] Preferably additionally, the at least one hydrogen processing module may comprise at least one hydrogen compression module 234. The hydrogen compression module 234 may be configured to compress the processed hydrogen, in particular the dried hydrogen. The hydrogen compression module 234 may comprise at least one hydrogen compressor (in particular a (vertical) piston compressor). The hydrogen compression module 234 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. As can be seen form Figure 2, the compressed hydrogen be provided for a second target definition 246, such as an external gas and / or liquid network and / or an outlet for gas and / or liquid vessels (e.g., for hydrogen export).

[0080] 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).

[0081] The at least one electrolyzer plant 206 may comprise at least one water treatment module 232, e.g., arranged on the platform 228. The at least one water treatment module 232 can be configured to treat the water such that it can be used by the at least one electrolyzer module 226 to produce hydrogen. In particular, the water treatment module 232 can treat seawater for the electrolysis process. Preferably, the at least one water treatment module 232 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 an energyefficient 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 226 via at least one fluid pipe 242 of an internal fluid network.

[0082] Alternatively or additionally, the at least one electrolyzer plant 206 may comprise at least one (not shown) inert gas generation module configured to generate an inert gas.

[0083] Furthermore, the at least one electrolyzer plant 206 may comprise at least one air intake and filtration module 230, e.g., arranged on the platform 228. The filtered air can be fed to the electrolyzer module 226 via at least one fluid pipe 242 of an internal fluid network. As can be further seen from figure 2, a (controllable) manifold 238 with a valve function is arranged at the outlet of the electrolyzer module 226 between the electrolyzer module 226 and the storage tank 208 and the compression module 234.

[0084] As already described, in the present embodiment, the offshore wind farm 200 may comprise a controller 250, comprising at least one processor 248 configured execute a computer program with the following steps (see also Figure 4): controlling a supplying of the at least one electrolyzer plant 206 of the offshore wind farm 200 with electrically energy generated by the at least one offshore wind turbine 202 of the offshore wind farm 200 (step 401), controlling a fluid flow of the fluid medium produced by the at least one electrolyzer plant 206 to at least one storage tank 208 of the offshore wind farm 200 (step 403), controlling a fluid flow of the stored fluid medium from the at least one storage tank 208 to at least one fluid-fired turbine device 210 with at least one electrical generator 212 of the offshore wind farm 200 (step 405), and controlling the at least one fluid-fired turbine device 210 such that at least at least one auxiliary device 204 of the offshore wind farm 200 is supplied with electrical energy generated by the at least one electrical generator 212 (step 407).

[0085] As shall be understood that the steps 401, 403, 405 and / or 407 can be executed at least in part in parallel to each other. Further, there may be an (internal) (wireless and / or wired) data network 252 for controlling the offshore wind farm 200, as described.

[0086] In particular, the at least one controller 250 may be configured to control at least the at least one fluid-fired turbine device 210, in particular based on at least one wind farm condition. A controlling of the at least one fluid-fired turbine device 210 may at least comprise an activating and deactivating of the fluid-fired turbine device 210. The controlling may depend on the electrical energy required by the at least one auxiliary device 204. In other words, the at least one wind farm condition may indicate that the at least one auxiliary device 204 requires electrical energy from the at least one fluid- fired turbine device 210.

[0087] As described, the at least one controller 250 may be further configured to control the fluid flow from the storage tank 208 to the at least one fluid-fired turbine device 210, preferably by controlling at least one (not show) valve arranged in the fluid connection 218 (e.g., at the outlet of the storage tank 208 and / or at the inlet of the fluid-fired turbine device 210) between the at least one fluid-fired turbine device 210 and the storage tank 208. The controlling may comprise at least an opening and closing of the at least one valve. The controlling may depend on the fuel required by the at least one fluid-fired turbine device 210. In other words, the controlling may depend on the condition of the at least one fluid-fired turbine device 210 (e.g., activated or deactivated).

[0088] Preferably, the at least one controller 250 may be configured to control the fluid flow (of the produced gas and / or liquid) from the at least one electrolyzer plant 206 to the at least one storage tank 208. In particular, the controller 250 may be configured to control the at least one manifold 238 with a valve function arranged in the fluid connection 216. The controlling may comprise at least an opening and closing of the at least one valve such that at least a portion of the produced gas and / or liquid is fed to the storage tank 208. Preferably, the controlling may depend on the storage state, in particular, the fill level, of the at least one storage tank 208. In other words, the controlling may depend on the condition of the at least one storage tank 208 (e.g., sufficiently filled or underfilled).

[0089] Alternatively or additionally, the controller 250 can be configured to control the at least one electrolyzer plant 206, in particular, the described modules of the electrolyzer plant 206. For example, the controlling may depend on the storage state, in particular, the fill level, of the at least one storage tank 208 (and / or the gas and / or liquid demand for the second target definition 246).

[0090] Further, as described, the controlling may depend on the at least one wind farm condition. The at least one wind farm condition may at least comprise an idling condition. In such a (full-) idling condition, all offshore wind turbines 202 of the offshore wind farm 200 are in the idling state respectively idling mode. In other words, none of the offshore wind turbines 202 of the offshore wind farm 200 generates electrical energy in the idling condition respectively idling state.

[0091] The at least one controller 250 may be configured to control at least the at least one fluid-fired turbine device 210 by activating the at least one fluid-fired turbine device 210 upon detecting of the idling condition, in particular, in order to supply at least the at least one auxiliary device 204 with the generated electrical energy for enabling an operating of the auxiliary device 204 without the need of an energy supply from an (not provided) external electric grid. In particular, this controlling may comprise a controlling of a fluid flow from the storage tank 208 to the fluid-fired turbine device 210 in order to supply the fluid-fired turbine device 210 with sufficient fuel (in form of the stored gas and / or liquid, in particular, the stored hydrogen).

[0092] As can be further seen from figure 2, the at least one offshore wind turbine 202 may be electrically connected to the at least one electrical generator 212 of the at least one fluid-fired turbine device 210 such that the at least one offshore wind turbine 202 is suppliable with the electrical energy generated by respectively from the at least one electrical generator 212. By enabling a flow of electrical energy from the at least one electrical generator 212 of fluid-fired turbine device 210 and the at least one offshore wind turbine 202, a black starting of the at least one offshore wind turbine 202 is enabled. In particular, the at least one wind farm condition comprises a black start condition. The at least one controller 250 may be configured to control at least the at least one fluid-fired turbine device 210, in particular by activating the at least one fluid-fired turbine device 210 upon detecting of the black start condition, in particular in order to supply at least the at least one offshore wind turbine 202 with the generated electrical energy for enabling a black starting of the at least one offshore wind turbine 202.

[0093] According to a further embodiment, the at least one fluid-fired turbine device 210 can only be activated by the at least one controller 250 if one wind farm condition of the at least one predefined wind farm condition (e.g., idling condition, black start condition and sub-idling condition) is detected by the controller 250. For instance, sensor data measured in the offshore wind farm 200 by one or more (not shown) sensors can be (continuously) evaluated by the at least one controller 250 in order to detect a predefined wind farm condition that requires an activating of the at least one fluid- fired turbine device 210 in order to generate electrical energy. In particular, this controlling may comprise a controlling of a fluid flow from the storage tank 208 to the fluid-fired turbine device 210 in order to supply the fluid-fired turbine device 210 with sufficient fuel (in form of the stored gas and / or liquid).

[0094] As can be further seen in figure 2, the offshore wind farm 200 may comprise a plurality of offshore wind turbines 202. The at least one wind farm condition may comprise a sub-idling condition. In the sub-idling condition, at least one first offshore wind turbine 202 of the offshore wind farm 204 is in an idling condition, and thus, does not generate electrical energy, and at least one second offshore wind turbine 202 of the offshore wind farm 200 is in a non-idling condition, and thus, does generate electrical energy.

[0095] The at least one controller 250 is configured to control at least the at least one fluid- fired turbine device 210, e.g., by activating the at least one fluid-fired turbine device 210, upon detecting of the sub-idling condition such that all of the at least one auxiliary device 204 may be supplied with the electrical energy generated by the at least one electrical generator 212. In particular, this controlling may comprise a controlling of a fluid flow from the storage tank 208 to the fluid-fired turbine device 210 in order to supply the fluid-fired turbine device 210 with sufficient fuel (in form of the stored gas and / or liquid).

[0096] Further, the at least one controller 250 may be configured to control the at least one offshore wind turbine 202 not in a sub-idling state of the offshore wind farm 200 such that all energy generated by the at least one offshore wind turbine 202 not in the idling state is fed to the at least one electrolyzer plant 206. In other words, in the subidling state of the offshore wind farm 200, all energy produced by the offshore wind turbines 202 of the offshore wind farm 200 is fed to the electrolyzer plant 206 and no energy from said offshore wind turbines 202 of the offshore wind farm 200 is fed to the auxiliary devices 204 of the offshore wind farm 200.

[0097] The depicted offshore wind farm 200 is preferably an off-grid offshore wind farm, i.e., an offshore wind farm without an electrical connection to an external grid, as shown in figure 2.

[0098] Figure 3 shows a schematic view of a further embodiment of an offshore wind farm 300 according to the present invention with an embodiment of a controller 350 according to the present invention. In order to avoid repetitions, in the following only the differences between the embodiments of Figure 1 and 2 and the embodiment of Figure 3 are essentially described. With regard to the other elements of the offshore wind farm 300 it is essentially referred to the previous embodiments.

[0099] As can be seen, the offshore wind farm 300 comprises a substation 322. The substation 322 comprises a (middle voltage) collector bus system 356 configured to electrically connect the one or more strings (e.g., between two and twelve) of offshore wind turbines 302. By way of example two electrical connections 314.1, 314.2 are shown for a respective number of strings. Each string may comprise a plurality of offshore wind turbines 302 (e.g., between four and twelve). By way of example, a power generating unit 354 of an exemplified offshore wind turbine 302 is shown in figure 3. The power generating unit 354, e.g., arranged in a nacelle of the offshore wind turbine 302, may comprise a generator, switches, a transformer, a connection 320 to at least one (not shown) auxiliary device, and the like.

[0100] Furthermore, the depicted substation 322 may have one or more electrical outputs. A exemplified first output may be configured to supply the at least one electrolyzer plant 306 with electrical energy. An exemplified second output may be configured to connect the substation 322 respectively the offshore wind farm 300 with an external grid 362 via an electrical connection 360. It shall be understood that a (not shown) onshore substation may be provided. A third output may connect the substation 322 via a connection 320 to at least one (not shown) auxiliary device.

[0101] In the present case, the substation 322 may also support the at least one storage tank 308 and the fluid-fired turbine device 310 with a fluid-fired turbine 364 and at least one electrical (synchronous) generator 312. The at least one electrical (synchronous) generator 312 is electrically connected via the substation 322 (and a transformer 358 with a switch) to the at least one (not shown) auxiliary device and / or the at least one offshore wind turbine 302 (via a connection 314).

[0102] As can be further seen from figure 3, the at least one controller 350 having a processor 348 may be configured to control the offshore wind farm 300 und the respective elements via at least one data network 352.

[0103] The at least one fluid-fired turbine device 310 may be configured to generate electrical energy of at least 1 % of the rated nameplate of the offshore wind farm 300, in particular, of approximately 1 % of the rated nameplate of the offshore wind farm 300. In particular, in the case that the offshore wind farm 300 is in the idling condition, the synchronous generator 312 may adjust its power generation to meet the full capacity of the demand of the at least one auxiliary device of the wind farm 300. In addition, the storage capacity of the at least one storage tank 308 may be selected such that the at least one fluid-fired turbine device 310 is operable for at least two days, preferably, at least seven days, particularly preferably at least fourteen days (and at most forty days). Preferably the storage tank 308 has a fill capacity for enabling an operation of the fluid-fired turbine device 310 for generating energy for all auxiliary devices for at least 14 days, in particular, between 14 days and 21 days.

[0104] Further, the offshore wind farm 300 may comprise an optional switch 370. The switch 370 may be configured to change the mode of the offshore wind farm 300 between off-grid mode and grid mode. The switch can be controlled by controller 350.

[0105] As has been described, figure 4 shows a diagram of an embodiment of a method according to the present invention. The at least one controller 350 with at least one processor 348 may be configured to execute a computer program with the following steps: controlling a supplying of the at least one electrolyzer plant 306 of the offshore wind farm 300 with electrically energy generated by the at least one offshore wind turbine 302 of the offshore wind farm 300 (step 401), controlling a fluid flow of the fluid medium produced by the at least one electrolyzer plant 306 to at least one storage tank 308 of the offshore wind farm 300 (step 403), controlling a fluid flow of the stored fluid medium from the at least one storage tank 308 to at least one fluid-fired turbine device 310 with at least one electrical generator 312 of the offshore wind farm 300 (step 405), and controlling the at least one fluid-fired turbine device 310 such that at least at least one auxiliary device 304 of the offshore wind farm 300 is supplied with electrical energy generated by the at least one electrical generator 312 (step 407). The described offshore wind farm, comprising preferably a plurality of wind turbines may or may not be electrically isolated from the external electric grid but continuous power supply to the auxiliaries is maintained in either case, and without drawing any electrical energy from the grid in the case of grid connected wind farms. The method incorporates in particular (a) "loop feed" approach, e.g., hydrogen-in-the-loop or ammonia-in-the-loop which includes (b) whole or partial conversion of the electrical energy from the plurality of wind turbines to hydrogen or ammonia, [c] transmission and storage of the hydrogen or ammonia within the wind farm and (d) reconversion of the stored hydrogen or ammonia to electricity to feed the auxiliaries of a plurality of wind turbines of the idling wind turbines in parts or whole of the wind farm, whereby power balance and security are achieved.

[0106] Offshore wind farms may now conceive to serve other purposes beside the integration of the generated electricity to the electric grid, such as but not limited to the production of green hydrogen or ammonia in a grid-connected or an off-grid mode. In this invention, a system has been described which may provide continuous power supply to a plurality of wind turbines in either grid-connected or an off-grid wind farm. In a grid-connected wind farm, the auxiliaries may be powered by drawing power from the grid it is connected to. But in the event of grid failure or in the case of an off-grid wind farm, grid-independent power supplies to the auxiliaries are typically supplied by diesel generators in the prior art. This is problematic for wind farms due to associated carbon emissions and consenting challenges. Another proposed method of the prior art is the use of battery energy storage system but the problem of capacity and costs, especially periodic retrofitting costs hamper such solution as well. And meeting the continuous energy needs of auxiliaries using battery storage may be impractical due to large energy requirements. Off-grid operations of wind farms lead to the formation of power islands, and in power island mode, it is vital that the wind farms be self-sustained, i.e., able to provide for all the needs of the auxiliaries of the wind turbines without the aid of an external electric grid. In this invention, a semi-central or central production of gas or liquid such as hydrogen, ammonia etc. in the wind farm is in particular proposed. Semi-central or central production means in particular that all the output electrical energy produced by in particular a plurality of wind turbines in the offshore wind farm is synchronized and paralleled to an electrical bus via a single or multiple strings respectively using an array network of medium or high voltage cables to an offshore or onshore platform, where the gas or liquid, e.g., hydrogen or ammonia producing plants and their auxiliaries such as water intake and demineralization units, air intake pumps etc. are connected as electrical loads. Also, coupled to the electrical bus may be one or more synchronous generators driven by hydrogen- or ammonia-fired turbines. The fuel for the hydrogen- or ammonia-fired turbines is derived from the produce of the hydrogen or ammonia producing plants via a "loop feed" mode.

[0107] The "hydrogen-in-the-loop" or "ammonia-in-the-loop" is in particular described in Figure 2 where it is shown by way of example how the energy produced from the offshore wind turbines connected to an electrical bus on the substation is fed to the hydrogen or ammonia producing plants and their auxiliaries. Some of the hydrogen or ammonia produced are collected in storage tank(s) and subsequently looped to hydrogen- or ammonia-fired turbines to drive one or more synchronous generators.

[0108] During the idling of one or plurality but not all of the wind turbines in the wind farm, the synchronous generator can be operated to feed the needed power of the auxiliaries such that the total energy of the operational wind turbines can be fully utilized for electricity production or the production capacity of hydrogen or ammonia and not reduced by the auxiliary consumption of the idling wind turbines.

[0109] A similar operation can be projected for all of the offshore wind turbines in idling state. In this case, the synchronous generator may adjust its power generation to meet the full capacity of the auxiliary demands of the wind farm. To achieve this, it has been determined that the total auxiliary power consumption of an idling wind farm is appr. 1% of the rated nameplate of the wind farm. An effective control of the reconversion of the stored green hydrogen or ammonia to electricity to match the energy demands of the auxiliaries of the idling wind turbines in parts or whole of the wind farm, whereby power balance and security are achieved is proposed to be performed by industry-standard nonlinear control-oriented, first principles-based state-space model controller.

[0110] The solution is proposed for both liquid- and gas-producing offshore wind farms and conventional wind farms supplying electricity to the grid, whereby a micro or mini gas turbine can be powered by the hydrogen or ammonia produced on the semi-central or centralized platform.

Claims

C l a i m s1. An offshore wind farm (100, 200, 300), comprising: at least one offshore wind turbine (102, 202, 302), and at least one auxiliary device (104, 204), characterized in that the offshore wind farm (100, 200, 300) further comprises: at least one electrolyzer plant (106, 206, 306) electrically connected to the at least one offshore wind turbine (102, 202, 302) such that the at least one electrolyzer plant (106, 206, 306) is suppliable with electrical energy generated by the at least one offshore wind turbine (102, 202, 302), at least one storage tank (108, 208, 308) fluidably connected to the at least one electrolyzer plant (106, 206, 306) and configured to store at least a portion of the fluid medium produced by the at least one electrolyzer plant (106, 206, 306), at least one fluid-fired turbine device (110, 210, 310) with at least one electrical generator (112, 212, 312), wherein the at least one fluid-fired turbine device (110, 210, 310) is fluidably connected to the at least one storage tank (108, 208, 308) and configured to generate electrical energy, based on the fluid medium provided by the storage tank (108, 208, 308), wherein at least the at least one auxiliary device (104, 204) is electrically connected to the at least one electrical generator (112, 212, 312) such that the at least one auxiliary device (104, 204) is suppliable with the electrical energy generated by the at least one electrical generator (112, 212, 312).

2. The offshore wind farm (100, 200, 300) according to claim 1, characterized in that the offshore wind farm (100, 200, 300) further comprises:at least one controller (250, 350) configured to control at least the at least one fluid-fired turbine device (110, 210, 310), based on at least one wind farm condition.

3. The offshore wind farm (100, 200, 300) according to claim 2, characterized in that the at least one wind farm condition comprises an idling condition, wherein the at least one controller (250, 350) is configured to control at least the at least one fluid-fired turbine device (110, 210, 310) by activating the at least one fluid-fired turbine device (110, 210, 310) upon detecting of the idling condition.

4. The offshore wind farm (100, 200, 300) according to any of the previous claims, characterized in that the at least one offshore wind turbine (102, 202, 302) is electrically connected to the at least one electrical generator (112, 212, 312) such that the at least one offshore wind turbine (102, 202, 302) is suppliable with the electrical energy generated by the at least one electrical generator (112, 212, 312).

5. The offshore wind farm (100, 200, 300) according to claim 2 and 4, characterized in that the at least one wind farm condition comprises a black start condition, wherein the at least one controller (250, 350) is configured to control at least the at least one fluid-fired turbine device (110, 210, 310) by activating the at least one fluid-fired turbine device (110, 210, 310) upon detecting of the black start condition (in order to supply at least the at least one offshore wind turbine (102, 202, 302) with the generated electrical energy for enabling a black start of the at least one offshore wind turbine (102, 202, 302)).

6. The offshore wind farm (100, 200, 300) according to any of the previous claims, characterized in thatthe offshore wind farm (100, 200, 300) comprises a plurality of offshore wind turbines (102, 202, 302) electrically connected to at least one substation (222, 322) of the offshore wind farm (100, 200, 300), wherein the at least one substation (222, 322) comprises at least one transformer (224) and the at least one fluid-fired turbine device (110, 210, 310).

7. The offshore wind farm (100, 200, 300) according to any of the previous claims, characterized in that the offshore wind farm (100, 200, 300) comprises a plurality of offshore wind turbines (102, 202, 302), wherein the at least one wind farm condition comprises a sub-idling condition, in which only a portion of the plurality of offshore wind turbines (102, 202, 302) is in an idling state, wherein the at least one controller (250, 350) is configured to control at least the at least one fluid-fired turbine device (110, 210, 310) by activating the at least one fluid-fired turbine device (110, 210, 310) upon detecting of the sub-idling condition such that all of the at least one auxiliary device (104, 204) are supplied with the electrical energy generated by the at least one electrical generator (112, 212, 312).

8. The offshore wind farm (100, 200, 300) according to claim 7, characterized in that the at least one controller (250, 350) is configured to control the at least one turbine not in a sub-idling state of the offshore wind farm (100, 200, 300) such that all energy generated by the at least one offshore wind turbine not in the idling state is feed to the at least one electrolyzer plant (106, 206, 306) and / or to an external grid (362).

9. The offshore wind farm (100, 200, 300) according to any of the previous claims, characterized in thatthe at least one fluid-fired turbine device (110, 210, 310) is configured to generate electrical energy of at least 1 % of the rated nameplate of the offshore wind farm (100, 200, 300), in particular, of approximately 1 % of the rated nameplate of the offshore wind farm (100, 200, 300).

10. The offshore wind farm (100, 200, 300) according to any of the previous claims, characterized in that the storage capacity of the at least one storage tank (108, 208, 308) is selected such that the at least one fluid-fired turbine device (110, 210, 310) is operable for at least two days, preferably, at least seven days, particularly preferably at least fourteen days (and at most forty days). Preferably between 14 and 21 days.

11. The offshore wind farm (100, 200, 300) according to any of the previous claims, characterized in that the offshore wind farm (100, 200, 300) is an off-grid offshore wind farm (100, 200, 300).

12. A method, in particular, a computer-implemented method, comprising: controlling a supplying of at least one electrolyzer plant (106, 206, 306) of an offshore wind farm (100, 200, 300) with electrically energy generated by at least one offshore wind turbine (102, 202, 302) of the offshore wind farm (100, 200, 300), controlling a fluid flow of the fluid medium produced by the at least one electrolyzer plant (106, 206, 306) to at least one storage tank (108, 208, 308) of the offshore wind farm (100, 200, 300), controlling a fluid flow of the stored fluid medium from the at least one storage tank (108, 208, 308) to at least one fluid-fired turbine device (110, 210, 310) with at least one electrical generator (112, 212, 312) of the offshore wind farm (100, 200, 300), and controlling the at least one fluid-fired turbine device (110, 210, 310) such that at least at least one auxiliary device (104, 204) of the offshore wind farm (100, 200,300) is supplied with electrical energy generated by the at least one electrical generator (112, 212, 312).

13. A computer program comprising instructions which, when the computer program is executed by at least one processor of a controller (250, 350), cause the processor to execute and / or control the method according to claim 12.

14. A controller (250, 350) for an offshore wind farm (100, 200, 300), in particular, an offshore wind farm (100, 200, 300) according to any of the previous claims 1 to 11, comprising at least one processor (248, 348) configured to execute the computer program according to claim 13.

Images