Electrolysis device, method for operating electrolysis device, and composite device comprising electrolysis device and wind turbine

Abstract

The invention relates to an electrolysis system comprising at least one electrolysis module (3A, 3B), the electrolysis module (3A, 3B) having a plurality of electrolysis cells (5) connected in series. According to the invention, a DC-conducting switching device (6) is provided which is electrically connected in parallel and which has an accessible power resistor (7) in such a way that, in the closed state, a current path through the power resistor (7) can be activated in order to cause a bridging of the electrolytic cell (5) and excess power can be dissipated via the power resistor (7). The invention further relates to a method for operating such an electrolysis plant (1) for decomposing water into hydrogen and oxygen, and to a composite plant (100) comprising an electrolysis plant (1) which is directly connected to a wind turbine (31).

Description

Technical Field

[0001] The invention relates to an electrolysis system comprising at least one electrolysis module, a method for operating an electrolysis system for splitting water into hydrogen and oxygen, and a combined system comprising an electrolysis system and a wind energy system connected to the electrolysis system. Background Art

[0002] An electrolysis device is a device that causes a material conversion (electrolysis) by means of an electric current. There are also a variety of electrolysis devices according to a variety of different electrochemical electrolysis processes, such as electrolysis devices for water electrolysis.

[0003] Nowadays, hydrogen is produced from water, for example, by proton exchange membrane (PEM) electrolysis or alkaline electrolysis. Electrolysis equipment uses electrical energy to produce hydrogen and oxygen from supplied water. This process takes place in an electrolysis stack consisting of a plurality of electrolysis cells. A plurality of electrolysis cells are connected in series to form electrolysis modules, or modules for short. A plurality of modules connected in series are connected in turn to form an electrolysis stack. Water is introduced as a reactant into the electrolysis stack under direct current voltage (DC voltage), wherein, after the water flows through the electrolysis cells, two fluids appear as electrolysis products, which consist of water and gas bubbles (O2 or H2).

[0004] The idea is to use excess energy from renewable energy sources to produce valuable substances during periods of abundant sunlight and wind power (i.e. above-average solar or wind power generation). One valuable substance can be hydrogen produced by water electrolysis plants in particular. Based on hydrogen, for example, so-called renewable energy gas, also called EE gas, can be produced. EE gas is a combustible gas obtained with the aid of electrical energy from renewable energy sources.

[0005] Hydrogen is a particularly environmentally friendly and sustainable energy carrier. It has the unique potential to realize energy systems, transport and most chemistry without CO2 emissions. In order to achieve this, however, hydrogen must not come from fossil energy sources, but must be produced using renewable energy sources. In the meantime, at least more and more electricity generated from renewable energy sources is fed into the public grid. Therefore, if the electrolysis plant is operated with electricity from the public grid, a corresponding share of green hydrogen can be produced depending on the power mix.

[0006] In electrolysis carried out on an industrial scale, direct current is mainly provided via grid-connected rectifiers.

[0007] This circuit device for supplying direct current to a plurality of electrolyzers arranged in parallel is disclosed in document EP 3 556 905 A1. The circuit device includes a rectifier that converts an input-side AC voltage into a first DC voltage on the output side. Here, each electrolyzer is connected in parallel to the output of the rectifier via a rectifier (particularly a buck converter) that converts a first DC voltage into a second DC voltage, so that the second DC voltage is reduced on the electrolyzer. Each rectifier, particularly a buck converter, is configured to be controllable or adjustable so as to adjust the level of its second DC voltage (its output voltage). Therefore, by using a buck converter configured to be controllable and / or adjustable for each electrolyzer, the current flowing through each electrolyzer can be adjusted when necessary even when the electrolyzers are connected in parallel.

[0008] One source of renewable energy is the increasing use of wind power. In particular, large electrical powers can be achieved using so-called offshore wind power plants close to the coast. However, it is challenging to overcome the large distances to the loads. Therefore, the energy should be delivered to the loads with as few losses as possible. Hydrogen is very suitable as a transport medium and energy carrier. It can be transported in gaseous form, for example, via pipelines. The positive aspect here is that the hydrogen-carrying pipeline can also fulfill the function of an energy storage device, because the internal pressure can be varied within a certain range.

[0009] For these reasons, it is particularly economically interesting to produce hydrogen directly at the energy source, i.e. to be self-sufficient and independent of the public grid. For this purpose, it is proposed to install the electrolysis system on an offshore platform of the maritime sector directly on or near the offshore wind power plant and to supply it with the generated electricity.

[0010] For land, it is also proposed to directly produce hydrogen using the current from onshore wind power plants or photovoltaic plants, at least partially by direct connection to an electrolysis plant and feeding it into the electrolysis plant. In all these applications, the electrolysis plant is part of an independent power supply network (Inselnetz). That is, the electrolysis current is not obtained from the public power grid, but is directly provided by the wind power plant or photovoltaic plant and fed into the electrolysis cell of the electrolysis plant. Compared with the above-mentioned grid-connected operation, the direct connection brings special challenges and problems in particular in terms of the electrical technical connection and interconnection of the electrolysis plant with the corresponding EE-generation plant (whether a wind power plant or a photovoltaic plant), in particular in order to ensure reliable and especially interference-free operation of the electrolysis plant in a direct composite plant with an EE-generation plant.

[0011] There is therefore a great need for technical solutions and precautions for planned or unplanned operating situations of electrolysis plants, in which, for example, a changed load must be responded to within a short time. Such requirements can arise due to changes in the generated power when connected to an EE power plant, as far as the lines provided are concerned, which are naturally subject to fluctuations. In particular, however, sudden changes in the availability of the output power can also occur on the part of the electrolysis plant, for example if one or more electrolysis modules or an electrolysis stack with a plurality of modules connected in series fails. Summary of the invention

[0012] The object of the present invention is therefore to provide an electrolysis plant by means of which electricity, in particular from renewable energy sources, can be fed directly into the electrolysis plant, wherein a high level of operating flexibility is achieved with simultaneous plant reliability. Further objects are to provide a corresponding method for operating an electrolysis plant and to provide a composite plant having an electrolysis plant and a renewable energy plant.

[0013] According to the invention, the first mentioned object is achieved by an electrolysis device, which comprises: at least one electrolysis module, wherein the electrolysis module has a plurality of electrolysis cells connected in series; and a switching device electrically connected in parallel and capable of conducting direct current, the switching device having a power resistor that can be connected, so that in the closed state a current path through the power resistor can be activated, thereby causing the electrolysis cells to be cross-connected. And the excess power can be dissipated through the power resistor.

[0014] The present invention is based on the following understanding: in an electrolytic device, the electrolytic cell of an electrolytic module is very sensitive to being applied with an impermissible high current density. Overload can cause electrolytic cell breakdown and failure, and in addition, local short circuits are caused by thermal overload caused by local high current density in the electrolytic cell and its components. In the worst case, this may lead to the loss of the entire electrolytic module, which is usually composed of a plurality of axially stacked electrolytic cells electrically contacted in series. Due to this series connection, the impermissible current will also affect multiple electrolytic cells and electrolytic modules. Therefore, precautions to avoid overload and breakdown must be taken for the operational safety and equipment safety of the electrolytic device. For example, if the absorption power or rated power is no longer available in the normal operation of the electrolytic device due to an unforeseen sudden (temporary or permanent) failure of the electrolytic cell or electrolytic module, this may be the case. If there are no protective measures, the sudden loss or instantaneous reduction of the absorption power will endanger the entire device and overload the electrolytic cell while maintaining a constant feed-in of the DC current supplied to the electrolytic device. Here, those electrolytic modules that are still in parallel operation are particularly burdened. The current density will increase until the converter has been adjusted accordingly, since the excess power previously used for the now switched-off electrolysis must be dissipated. With the invention, the excess power can be dissipated both on the generator side and on the load side via power resistors as required, which is very advantageous for protecting the device.

[0015] By means of a switching device electrically connected in parallel with the electrolysis cells or electrolysis modules, a safety technology solution is proposed by the invention directly on the electrolysis plant itself. This can advantageously reduce the response time required for switching in the power resistor by activating the current path. The advantage of this self-sufficient solution is also that, in the case of a protective function, no influence is initially exerted on the external power supply, which continues to supply the rated current. Therefore, at least for a certain time, no regulatory intervention is required by the power regulation of the power supply. Thus, the control at this time can be made simpler, for example, because the converters connected in parallel do not have to be preventively reduced at the same time as one converter is turned off. This is particularly advantageous when directly connected to slow generators (for example wind power plants). Therefore, in the case of wind power plants, tracking, in particular the necessary reduction of the feed-in power and the adaptation of the feed-in power to the absorbed power can only be carried out relatively slowly, that is, the power regulation on the generator side can only follow the new, reduced target value very slowly. On the contrary, the bridging of individual or multiple electrolysis cells can be realized and implemented immediately, or the bridging of the entire electrolysis module can also be realized and implemented immediately as required. In this case, the electrolysis plant can continue to operate, for example to produce hydrogen, with excess energy being safely dissipated via the power resistors of the switching device. In island grid operation, this also prevents a voltage increase on the external power supply side. This would be a risk if the power could not be consumed or dissipated elsewhere.

[0016] In addition, the present invention proposes a particularly reliable protection circuit in the case of overload, for example, in the case of failure of one or more electrolysis modules, so as to reliably ensure overload protection of electrolysis cells and electrolysis modules. Depending on the overload situation, the excess current available at the time cannot be distributed to the electrolysis cells or electrolysis modules that are still in operation. If individual or multiple electrolysis cells or electrolysis modules fail or are cut off, the fed power can no longer be absorbed by the electrolysis equipment without causing damage. When these components or electrical subsystems of the electrolysis equipment are cut off, the excess energy must be absorbed. Power resistors (also known as brake resistors) are used for this purpose. When the current path is activated, the power resistor absorbs all electrical energy and converts it into ohmic heat. If necessary, this heat energy can be further used as useful heat in energy technology by, for example, coupling to a heat storage device or a heat exchanger. As a power resistor, it is preferably possible to use, for example, electromechanical high-performance variable resistors for power applications. Their resistance elements are usually made of thick resistance wires, which are suitable for carrying rated currents and bridging electrolysis cells for a long time as long as their ohmic resistance is minimal. However, power resistors are also possible which only need to accept and dissipate the entire current of the electrolysis for a few seconds. This time should be sufficient to be able to regulate the external power supply used to supply the power for the electrolysis.

[0017] This problem is particularly evident when the electrolysis device is directly connected to a DC power supply, for example, provided by a photovoltaic device or a wind power device. The electrolysis device is thus particularly advantageously designed for direct connection and direct feeding of direct current from a renewable energy device. This realizes very advantageous protection measures for planned or unplanned operation of the electrolysis device, wherein, for example, a reaction to a changed load must be made within a short time. When connected to a renewable energy power generation device, this requirement arises due to changes in the power provided (which is of course affected by the natural fluctuations of power generation). However, particularly sudden changes in the availability of the absorbed power in the electrolysis device can be overcome in an advantageous manner, for example in the case of unforeseen failures of one or more electrolytic cells, one or more electrolytic modules or an electrolytic stack having a plurality of electrolytic modules connected in series. It is thus also possible to at least partially reduce the power generation peaks of the power generation (for example, renewable energy devices).

[0018] In the case of direct connection of the electrolysis plant to a wind energy plant to provide 100% green electricity, unfavorable feedback or reactions to the wind energy plant, in particular its generator, are also prevented by means of a switching device with a power resistor during the crossover. The system inertia on the generation side is thus decoupled. The electrolysis plant is thus designed such that it allows tracking and adjustment by power regulation on the generation side (e.g. in the case of direct connection to a wind energy plant) according to the inherent regulation times.

[0019] In a particularly preferred embodiment, the electrolysis device comprises at least two electrolysis modules connected in series, each electrolysis module having a plurality of electrolysis cells connected in series.

[0020] Thus, the device concept for protecting the circuit by means of an integrated DC-conducting switching device can be expanded in a modular manner. Thus, a plurality of electrolysis modules can advantageously be combined to form an electrolysis device, wherein the accessible power resistors can be used as required and in particular in a modular manner. This makes high-performance electrolysis devices on an industrial scale possible. These electrolysis devices are designed and prepared in a particularly advantageous manner for temporary overloads on the power generation side. A particularly high level of operating flexibility is achieved, while at the same time achieving device safety.

[0021] Preferably, the electrolysis modules are bridged in the closed state by means of the parallel-connected switching devices. In the case of a generally modular structure of an electrolysis stack or electrolysis cell comprising a plurality of electrolysis modules connected in series, it is particularly advantageous if the switching devices are designed for bridging the respective electrolysis modules. This allows modular adjustment and bridging to be carried out as required and the respective current paths through the power resistors to be activated.

[0022] In this case, it is preferred that the bridging of multiple electrolysis modules is achieved in the electrolysis device by a switch device in a closed state. Therefore, the electrolysis device is advantageously designed so that multiple corresponding current paths can be activated to bridge multiple corresponding electrolysis modules. One or more corresponding power resistors in the bridging current path are designed according to the power loss expected in the current path in the event of a fault or cutoff. Thus, for example, for an electrolysis stack or electrolyzer comprising five electrolysis modules in series, a fault in one electrolysis module causes a 20% power reduction on the electrolysis side. Therefore, when bridging the module, the power resistor must be designed for the rated power of the electrolysis module, or must also be designed to be far below the rated power in the case of only temporary loads. The power resistor is designed so that it can be overloaded for a short time, so it can also be used for equipment with a shorter peak current. In the electrolysis cell, each electrolysis cell is usually stacked in the axial direction to form an electrolysis module comprising multiple individual electrolysis cells, and is installed to the module or electrolysis module. The electrolysis cell as a functional structural unit of the electrolysis device usually has a plurality of electrolysis modules, which form a so-called electrolysis stack or simply referred to as a "stack" as a whole. Thus, for example, 50 electrolysis cells can be stacked axially to form a module, and for example, 5 modules can be stacked in turn in the axial direction to form a stack, so that such an electrolysis stack can thus comprise, for example, 250 cells in the axial overall complex. The electrolysis device can have a plurality of electrolysis stacks or electrolysis cells connected in parallel.

[0023] In a particularly preferred embodiment of the electrolysis device, the switching device has a mechanically closable switching element, which is designed in particular as an electrically or electromagnetically activatable switch or contactor.

[0024] Furthermore, a combination of a plurality of switching elements, in particular a combination of two switching elements, can be provided in the switching device, wherein the switching elements are preferably designed for switching in a time-staggered manner.

[0025] In this combination, the first switching element switches on the current path through the power resistor. The second switching element separates the main power supply line for providing the electrolysis current to the electrolysis device. The resistance value of the power resistor is designed so that it is approximately equal to the resistance in the electrolysis path cut by the power resistor. Advantageously, there is no short circuit, and otherwise the current will not be commutated into the parallel path with the power resistor or will be evenly distributed in a maximum ratio of about 50:50.

[0026] In an advantageous and cost-effective embodiment, this can also be achieved by means of only one switching element (designed similar to a changeover switch) which has two current-carrying switching states, which in one position supplies the electrolysis power and in the second position loads the power resistor when bridging. This changeover switch solution is preferably used if, for example, a faulty electrolysis module is to be disconnected and parallel cells are to be switched as little as possible.

[0027] Alternatively, as described above, it is also possible to operate with only one corresponding switching element. The switching element is then preferably designed and activated so that, for example, the faulty cell to be bridged is hard disconnected and the load resistors are then connected for a period of time in the remaining parallel cells in order to intercept or capture current peaks on the generator side.

[0028] Advantageously, the switching element is designed as a contactor or also as a switching contactor. This is an electrically or electromagnetically actuated switch for high electrical powers, similar to a relay. The contactor has two switching positions and normally switches monostable without requiring special precautions. An electromechanical design is particularly advantageous for switching in the required high powers via power resistors in a very short time. In this case, a magnetic coil is provided in the switching element.

[0029] If a control current flows through the electromagnetic coil of the electromechanical contactor, the magnetic field pulls the mechanical contacts into the activated state. When there is no current, the springs establish a resting state again and all contacts return to their initial position. The connections for the control current of the electromagnetic coil and the contacts for the auxiliary circuit (if any) and the current to be switched are constructed to be insulated from each other in the contactor: there is no conductive connection between the control contacts and the switching contacts. Basically, the contactor is a relay with a significantly higher switching power. Typical loads start from about 500 watts and can reach up to hundreds of kilowatts or even thousands of kilowatts. By connecting multiple switching elements or switching contactors in parallel, correspondingly higher powers can be switched, which can be flexibly adapted to the power to be consumed by the power resistor according to the application. Accordingly, multiple power resistors with corresponding power consumption connected in parallel can also be provided.

[0030] In a particularly preferred embodiment of the electrolysis device, the switching device has a thyristor as a switching element, so that the current path via the power resistor can be activated when the thyristor is switched on.

[0031] Thyristors can be used particularly advantageously as switching elements for high power. Thyristors are semiconductor elements made of four or more semiconductor layers that are alternately doped. Thyristors are switchable elements, that is, they are non-conductive in the initial state and can be switched on by a small current on the gate. After switching on, the thyristor remains on even without a gate current. When the current drops below a minimum value, the so-called holding current, the thyristor will turn off. By injecting current into the third layer (gate control), the thyristor can be switched on, i.e. turned on. This closes the current path through the power resistor, i.e. activated. The prerequisite is a positive voltage between the anode and the cathode and a minimum current flowing through the intermediate barrier layer. Either by falling below the holding current (English: Holding Current), which usually occurs when the voltage in the load circuit is cut off or reversed, or when the current in the load circuit passes through zero (for example in a rectifier), or by reversing the polarity in the cut-off direction, the thyristor is erased, i.e. enters the cut-off state. The speed of this process is limited by the so-called release time, which is necessary for the thyristor to regain its full control and blocking capabilities after the current conduction phase has ended.

[0032] It is also possible that thyristors and electromagnetically triggerable switches are present in the switching device as switching elements. Various combinations are possible, depending on the design and application of the electrolysis plant and the specific load conditions in the current paths to be switched.

[0033] Alternatively, in the switching device, the switching element is preferably designed as a semiconductor element having an insulated gate bipolar transistor (IGBT) so that a current path through the power resistor can be activated when a gate of the IGBT is opened.

[0034] The IGBT is a frequently used device in power electronics because it combines the advantages of bipolar transistors (e.g. good conduction behavior, high cut-off voltage, robustness) with the advantages of field effect transistors (almost power-free control). The significant advantages of the IGBT are the high voltage and current limits, with an operating voltage of up to 6500V and a current of up to 3600A at powers of up to 100MW. This makes it ideal to use the IGBT in the rectifier 15 for the working area of ​​the electrolyzer 3. Depending on the application, it is also conceivable to use so-called IGCTs, i.e. integrated gate-commutated thyristors. It reduces the wiring effort, increases the maximum pulse frequency for control, and has better switching times when connected in series, which is advantageous. The field of application of the IGCT is high-power rectifiers. A single module switches currents of typically several thousand amperes at a typical cut-off voltage of 4500V.

[0035] In a preferred design, the power resistor is settable or adjustable. Here, the design will be set to an adjustable high-load resistor, which for example has a high rated current of 10 to 30 amperes, particularly 15.0 to 20.0 amperes, and a rated power of 1.5 to 10.0 kilowatts, usually 2.0 kilowatts. In order to achieve higher power and larger rated current when bridging, it is flexibly specified when necessary that a plurality of power resistors are connected in parallel on the corresponding current path to form a total power resistor. Depending on the electrolysis technology, the current actually consumed by the electrolysis equipment is usually several thousand amperes, that is, about 100 times larger than the current that may be specified or available for a single power resistor. Therefore, a device and a circuit composed of a plurality of power resistors are also included. When necessary, depending on the application, the power resistor can also be designed as a pool or have a pool. So simply dissipate the current through the pool when necessary.

[0036] More preferably, the power resistor is designed for overload so that the power resistor can operate with current decay when powered on for up to 5 seconds, especially up to 10 seconds, and can dissipate excess power.

[0037] Since load resistors regulate the current when connected across the brake resistor, these brake resistors should by definition be designed for a continuous current, i.e. the rated current. However, load resistors can also be overloaded for a short time and can therefore also be used in plants with brief peak currents, for example with particular advantage in electrolysis plants. Depending on the load profile, for example for a braking energy of 2 kW to be dissipated (which exists for a maximum of 4 seconds), power resistors can be used with a maximum continuous load of between 800 and 1000 watts, which is approximately 200% to 250% of the rated value of the rated current or rated power. Therefore, power resistors with overload capacity are advantageously used, which have the highest possible limit voltage of up to 5000 volts and a high rated current.

[0038] The overload capacity of the power resistor is preferably 200% to 300%, in particular approximately 250%, in the case of a decay current of up to 5 seconds. This is a particularly interesting operating range, in which, on the source side, in particular in the case of a wind power plant, a corresponding power regulation can be carried out on the feed side within the same time of approximately 5 seconds and the necessary tracking of the DC power that can be supplied to the electrolysis plant or its reduction to a reduced value can be carried out. In this way, an adaptation is very advantageously achieved, which enables the electrolysis plant to be directly connected to the wind power plant with high operational reliability.

[0039] In a particularly preferred embodiment of the electrolysis device, a further current path is provided in the switching device in parallel with the current path via the switchable power resistor, the further current path having a further switching element and a forward diode and / or a low-ohmic resistor connected in series with the further switching element, wherein the further current path has a lower resistance than the electrolytic cell in the closed state, so that the polarity and the protective voltage of the electrolytic cell are maintained when the electrolytic cell is bridged.

[0040] By means of a further current path which can be connected in parallel with the current path when necessary, further protection requirements can be very advantageously identified and implemented in the switching device. In particular, this protection circuit in the further current path is very advantageous and flexible for the operation of an electrolytic cell or a plurality of electrolytic modules in partial load operation. Thus, if the availability and feed-in of the electrolytic power (in particular the electrolytic current) from the external power source is insufficient, it is provided to establish a further current path for the targeted and at the same time reliable bridging of individual or multiple electrolytic cells for reliable partial load operation, thereby advantageously expanding the operating window of the electrolytic device. By means of a switching device designed in this way, the electrolytic device is designed both for the risk of overload in the event of a failure or disconnection of an electrolytic cell, and for underload situations, for example due to a reduction in power generation, or for the temporary outage of selected electrolytic cells or electrolytic modules, for example for planned maintenance purposes. By means of bridging in this way, these components are actually short-circuited. The electrolytic cells or electrolytic modules that can be powered on can be operated substantially at rated load, which is more efficient than operating all electrolytic cells or electrolytic modules at partial load.

[0041] Here, a protection circuit is provided in another current path, which ensures that a protection voltage is used as a bias voltage, and the bias voltage has the corresponding polarity of the electrolytic cell or optionally the entire electrolytic module that is bridged in the electrolysis device. This protection circuit leads to a significant improvement in the operational safety in partial load operation, because the protective bias voltage on the diode and / or the low-ohm resistor very effectively offsets the risk of damaging the fuel cell operation in the bridged electrolysis module. If there is no such protective measure, by the residual product gas, hydrogen and oxygen in the cathode chamber or anode chamber of the bridged electrolysis module, due to the electrochemical potential, a very unfavorable fuel cell process will occur, which should be avoided. This danger is specifically overcome by this advantageous improvement of the electrolysis device. In addition, by avoiding undesirable fuel cell operation (the reverse process of electrolysis operation), the service life of the relevant components of the electrolytic cell is significantly improved. Thus, life-optimized operation management can also be achieved.

[0042] In a preferred embodiment, the electrolysis device has a plurality of electrolysis cells connected in series to form an electrolysis module, so that when a further current path is activated by closing a further switching element, the electrolysis module is bridged, wherein the polarity and the protection voltage of the electrolysis module are maintained.

[0043] Thus, in the event of an overload, provision is made to bridge the entire electrolysis module via the current path and the switchable power resistor, or alternatively, the further current path can be activated by closing the further switching element, thereby achieving an improved and particularly economical partial load operation, effectively protecting the short-circuited electrolysis module. When the further current path is activated for partial load operation, the current path with the power resistor is not energized, but rather bypassed.

[0044] For this purpose, the resistance of the further current path is preferably selected such that the resulting current distribution leads to the electrolysis module being sufficiently energized in the relevant current range in order to prevent undesired fuel cell operation.

[0045] In a particularly preferred design, the electrolysis device has an interface unit having an input end for connecting to an external DC power supply and an output end connected to the electrolysis module, wherein the interface unit has a transformer, to which an inverter is connected on the primary side and a rectifier is connected on the secondary side, so that DC power can be supplied to the electrolysis module.

[0046] This advantageous improvement of the electrolysis device implemented by the interface unit provides an AC intermediate circuit, which provides for the current decoupling between the external DC power supply and the electrolysis device. In the AC intermediate circuit, the inverter is responsible for converting the DC voltage of the external DC source into an AC voltage, which is coupled to the transformer on the primary side. A rectifier is connected to the secondary side of the transformer, which ensures the conversion back to the DC voltage at the voltage or current level required and predetermined for electrolysis. Therefore, the interface unit is particularly advantageously constructed as an AC intermediate circuit and is designed to provide direct current through an external DC power supply to supply electrolysis current to the electrolysis device. This is done by directly coupling or connecting the input end to the external DC power supply. As an external DC power supply, a wind energy device or a photovoltaic device can be advantageously connected to the electrolysis device, which can be advantageously designed to be independent of the grid in so-called island operation for both offshore applications and onshore applications.

[0047] In this case, an external DC power source can be directly and immediately connected via the input of the interface unit, thereby realizing a DC power supply for the electrolysis device. Due to the galvanic isolation and decoupling via the AC intermediate circuit, the interface unit also reliably avoids the harmful intrusion of stray currents, thereby also avoiding ground fault currents and undesirable voltage losses in the electrolysis device. At the same time, a simple and reliable direct connection of the electrolysis device to a renewable energy power generation device, in particular a wind power device, can be realized, and operation independent of the power grid is facilitated.

[0048] In a preferred embodiment, the rectifier can be designed to be adjustable and / or to be designed as a three-phase rectifier, in particular as a B6 bridge rectifier.

[0049] The controllability of one or more rectifiers, which are advantageously designed as three-phase rectifiers or B6 bridge rectifiers, makes it possible to adjust the total current generated via the one or more rectifiers and thus control the operation of one or more electrolyzers connected to the interface unit, for example.

[0050] Preferably, it is provided that the frequency of the alternating current in the interface unit can be set to a predetermined value. By designing the circuit arrangement as an AC intermediate circuit, it does not have to be connected to the public grid and the alternating current frequency in the transformer can therefore be selected freely to a large extent. Advantageously, a high-frequency transformer is provided here so that deviations from the usual frequency in the public grid can be made if necessary. For example, the interface unit can then be set to an alternating current frequency of 500 Hz to 50 kHz, in particular 10 kHz to 30 kHz, in a transformer designed as a high-frequency transformer. However, for operation at grid frequency, a corresponding design and use of the transformer can still be used.

[0051] In a preferred design of the electrolysis device, the interface unit is set to an alternating current frequency that is greater than the common grid frequency of 50 Hz to 60 Hz in the public grid. High frequencies are suitable here because the size and weight of the transformer can be reduced and the use of materials can be reduced. This aspect is particularly advantageous when the electrolysis device is directly connected to a wind energy device. Due to the more compact construction and lighter weight at high operating frequencies, the transformer can be placed, for example, in a nacelle of the wind energy device, or in the floor of the wind energy device tower. The circuit device can also be arranged there as a whole. Therefore, the electrolysis device, for example, can be located in the vicinity of the wind energy device, so that a short-distance line connection can be achieved.

[0052] In a particularly preferred embodiment, the circuit arrangement is set to an AC frequency of 500 Hz to 50 kHz, in particular 10 kHz to 30 kHz. This AC frequency is related to the frequency of the inverter and rectifier connected to the transformer. In order to fully utilize the installation space advantages and cost advantages, a high-frequency intermediate circuit transformer is provided as the transformer.

[0053] The transformer preferably has a transformation ratio of less than 10, in particular between 1.5 and 7.5. This can be flexibly adapted to the requirements of the electrolyzer or the voltage level required for the electrolysis process, so that larger transformation ratios can also be achieved, depending on the application.

[0054] The ratio of the number of turns, or the ratio of the voltage on the primary side to the voltage on the secondary side, is also called the transformation ratio. By appropriately selecting the transformation ratio (i.e. the number of turns), the AC voltage can be stepped up or stepped down using a transformer. This can advantageously achieve adjustments in terms of electrolysis.

[0055] Voltage amplitudes greater than 10 are also possible, specifically depending on the application and design of the electrolysis equipment, especially the transformer used. Known electrolysis equipment is usually operated with a maximum DC voltage of 1500V, which still corresponds to the low voltage range. However, in order to be connected to a power generation equipment, a DC voltage exceeding 15kV can be set and provided. Therefore, the upper limit of the voltage amplitude can also preferably be selected to be up to 70. Then, the available connection voltage (for example, if the electrolysis equipment is operated at a DC voltage of only 1000V) can be up to about 70kV. Currently available wind energy equipment can, for example, produce an output voltage of 66kV AC voltage.

[0056] A further aspect of the invention relates to a method for operating an electrolysis plant with a high degree of operating flexibility while maintaining the safety of the plant.

[0057] According to the invention, the objects associated therewith are achieved by a method for operating an electrolysis plant for decomposing water into hydrogen and oxygen, wherein, according to the invention, an electrolysis plant according to the invention is provided, wherein in normal operation at least two electrolysis modules are supplied with an electrolysis current, wherein hydrogen and oxygen are produced in the electrolysis modules, wherein in the event of a fault in one of the electrolysis modules a bridging operation is introduced, wherein a current path via a power resistor is activated, thereby bridging the faulty electrolysis module, wherein excess power is absorbed via the power resistor.

[0058] With this method, in particular in the case of an unforeseen failure or emergency shutdown of one or more electrolysis modules, or of a part of an electrolysis stack or electrolysis cell comprising one or more electrolysis modules, or even of the entire electrolysis device, a protection program is immediately activated on the electrolysis device side. In this protection program, the failed electrolysis module or multiple failed electrolysis modules are stopped or powered off by immediately bridging them, depending on the reduction in power consumption. The entire electrolysis device is thus protected from overload. On the generator side, which is slow, for example due to mechanical reasons, the external power regulation on the generator side is usually unable to adjust the power output quickly enough, that is, to reduce the power output so that the power output is adapted to the reduced absorbed power of the electrolysis device and tracks the power output. Wind power plants are an example, for example, when the power loss in the electrolysis cell reaches 20%, the wind power plant needs several seconds to adjust the angle of attack of the rotor blades accordingly. Depending on the previous operating point, the excess current generated during this period cannot be distributed to the electrolysis modules that are still in operation, so that an impermissibly high current density will not be generated there.

[0059] In the crossover operation, in the method according to the invention, excess energy is therefore advantageously dissipated by activating a current path via a power resistor in the electrolysis plant, in particular until the power plant has been adjusted to the new situation, if necessary.

[0060] Preferably, in the method the supplied electrical power is adapted to the reduced absorbed power of the electrolysis device, wherein the electrolysis current decreases and causes the current intensity through the power resistor to decay over time.

[0061] In this case, the supplied electrical power is preferably fed in from a wind power installation to which the electrolysis installation is connected, wherein in the bridging operation the pitch angle of the rotor blades is adapted to the absorbed power of the electrolysis installation.

[0062] It is further preferred that the supplied electrolysis current is adapted to the reduced absorbed power of the electrolysis system within a maximum of 10 seconds, in particular within a maximum of 5 seconds. In the case of wind power plants, up to 5 seconds is generally particularly advantageous in order to adapt the output power to the absorbed power of the electrolysis system and to achieve power regulation. At the same time, during this period, a decaying high current intensity can be transmitted via a power resistor with overload capacity, so that in the bridging operation an advantageous adaptation of the output power to the absorbed power is achieved, while at the same time effective overload protection of the electrolysis system is achieved.

[0063] Another aspect of the invention relates to a composite device comprising an electrolysis device, which has a high level of operating flexibility while ensuring the operating reliability of the composite device.

[0064] According to the invention, the object in this connection is achieved by a composite plant comprising an electrolysis plant and a wind energy plant, wherein an output is provided for providing direct current, wherein the output is connected to an input of the electrolysis plant.

[0065] Here, the composite device according to the invention is to be understood functionally in such a way that the AC voltage originally generated by the wind energy device on the generator is in any case rectified, i.e. rectified in a rectifier for use and connected to an electrolysis device. Depending on the device technology design of the composite device, the output of the rectifier for providing direct current can be spatially arranged in the electrolysis device, for example in a container of the electrolysis device or in a container or housing of an electrolytic cell. The wind energy device itself then preferably only outputs an AC voltage, which is rectified accordingly for electrolysis purposes. The output for providing direct current can be formed by the wind energy device itself, which has a rectifier or is assigned a rectifier. However, the rectifier can also be assigned to the electrolysis device.

[0066] This makes it possible to achieve island operation in the complex, independent of the public grid, and to use the electricity directly from the wind energy plant alone for electrolysis, thus forming 100% green hydrogen.

[0067] It is further preferred that the wind energy installation has a rectifier which is connected to the input of the electrolysis device on the DC side or is electrically connected to the input. The rectifier converts the original alternating current from the generator of the wind energy installation into direct current and advantageously provides the desired input DC voltage level for connection to the electrolysis device at the same time. In an alternative design, the electrolysis device can also have a rectifier, so that the alternating current is fed in from the wind energy installation. Rectification in the application of the advantageous direct connection of the wind energy installation to the electrolysis device is to be understood from a functional point of view.

[0068] In an alternative embodiment, it is also possible that in the composite plant the renewable energy plant is a photovoltaic plant. The photovoltaic plant already provides direct current during operation. However, it can then preferably be provided that in the composite plant the photovoltaic plant has a DC regulator or a DC voltage converter which is connected on the output side to the input of the electrolysis plant. It is particularly preferred that in the composite plant the renewable energy plant is a wind energy plant.

[0069] The advantages and advantageous configurations of the electrolysis plant according to the invention are to be regarded as advantages and advantageous configurations of the method for operating the electrolysis plant as well as advantages and advantageous configurations of the composite plant, and vice versa.

[0070] Further advantages, features and details of the invention are apparent from the following description of preferred exemplary embodiments and with the aid of the drawings. The features and feature combinations mentioned above in the description and the features and feature combinations mentioned below in the description of the figures and / or shown individually in the individual figures can be used not only in the respectively indicated combination but also in other combinations or alone without departing from the scope of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] Embodiments of the present invention will be explained in more detail with the aid of the accompanying drawings. Here, schematically and greatly simplified:

[0072] Figure 1 A composite device having an electrolysis device and a wind energy device, wherein the electrolysis device comprises a plurality of electrolysis cells;

[0073] Figure 2 It is a part of an electrolysis plant with an electrolysis cell and a plurality of DC switching devices.

[0074] The same reference numerals in the figures have the same meaning. DETAILED DESCRIPTION

[0075] Figure 1A composite device 100 according to the present invention is shown. The composite device 100 comprises an electrolysis device 1 and a wind energy device 31 connected to the electrolysis device 1 as a renewable energy device (EE device) and a green power source. The electrolysis device 1 has three electrolytic cells 35A, 35B, 35C connected in parallel and an interface unit 19 electrically connected to the electrolytic cells 35A, 35B, 35C. The interface unit 19 is used to supply electrolysis current to the electrolytic cells 35A, 35B, 35C. The connection of the interface unit 19 to the electrolytic cells 35A, 35B, 35C is carried out via the corresponding output terminals 23. In addition, the interface unit 19 has an input terminal 21, via which direct current can be supplied to the electrolysis device 1, in particular to the electrolytic cells 35A, 35B, 35C. The supply of direct current from the direct current power source is carried out through the interface unit 19. For this purpose, the interface unit 19 has an inverter 27, a transformer 25 and a rectifier 29. Here, the corresponding rectifier 29 is connected to the electrolysis cells 35A, 35B, 35C, so that the corresponding rectifier 29 supplies direct current for electrolysis to one of the electrolysis cells 35A, 35B, 35C. By means of the interface unit 19, an AC intermediate circuit is thus provided in the electrolysis device 1, by which the input 21 is electrically decoupled from the output 23. On the primary side, an inverter 27 is connected to the transformer 25. On the secondary side, a rectifier 23 is connected to the transformer 25. A direct current, an electrolysis current, is supplied to the electrolysis cells 35A, 35B, 35C via the rectifier 23 of the interface unit 19. The electrolysis cells 35A, 35B, 35C can be configured as PEM electrolysis cells, AEM electrolysis cells (AEM: anion exchange membrane) or alkaline electrolysis cells.

[0076] In order to supply the electrolysis process with direct current, the electrolysis plant 1 is directly connected to the wind energy plant 31. The connection is here made directly via the input 21 of the interface unit 19, which is correspondingly designed to receive direct current and pass it on to the inverter 27. The wind energy plant 31 first generates alternating current in the generator of the wind energy plant 31. In order to be able to transmit direct current to the electrolysis plant 1, a rectifier 33 is provided, so that the connection is made via this rectifier 33, wherein the rectifier 33 is advantageously a power device of the wind energy plant 33.

[0077] In the embodiment shown, each of the electrolysis cells 35A, 35B, 35C comprises a plurality of electrolysis modules 3A, 3B respectively connected in series. Thus, for example, one or more electrolysis modules 3A, 3B can be connected successively to form corresponding electrolysis cells 35A, 35B, 35C. Each of the electrolysis modules 3A, 3B has numerous, in particular multiple, electrolysis cells 5, which are stacked in the axial direction and are both electrically contacted and fluidically connected to each other, so that separation water can be supplied and the product gas flow can be led out for further use. For example, fifty electrolysis cells 5 can be constructed in one electrolysis module 3A, 3B, so that two hundred and fifty or more electrolysis cells 5 are constructed in the electrolysis cells 35A, 35B, 35C. The electrolysis cells 35A, 35B, 35C designed in this way, which include a plurality of electrolysis modules 3A, 3B, are also referred to as electrolysis stacks, which can be regarded as a functional unit in the electrolysis device 1. In the embodiment of the electrolytic cell 35A as an alkaline electrolytic cell, it is possible to provide only one electrolytic module 3A due to the high performance of the alkaline electrolytic cell.

[0078] The electrolysis module 3A comprises a switching device 6 electrically connected in parallel and capable of direct current conduction. The switching device 6 has an accessible power resistor 7. As a result, in the closed state of the switching device 6, a current path flowing through the power resistor 7 can be activated, thereby achieving a plurality of electrolysis cells 5 of the electrolysis module 3A to be bridged and the excess power can be dissipated through the power resistor. In the present case, the electrolysis module 3A can be bridged, and therefore all the electrolysis cells 5 of the electrolysis module 3A can be bridged. It is also possible that all electrolysis modules 3A, 3B in the electrolysis cells 35A, 35B, 35C are provided with a switching device 6, or that the switching device 6 is designed so that individual or multiple electrolysis cells 5 can be bridged. Combinations are also possible, so that the bridging current path can be closed individually and specifically designed for the electrolysis device 1 at the level of the electrolysis cell 5, the electrolysis module 3A, 3B or at the level of one of the electrolysis cells 35A, 35B, 35C. Various designs of the switching device 6 are possible here.

[0079] In the electrolysis cell 35A, for example, the switching device 6 has a mechanically closable switching element 9A, which is designed as an electromagnetically triggerable switch with a short switching time in the range of only a few milliseconds, in particular between 2 ms and 10 ms, for example 4 milliseconds. In the electrolysis cell 35A, when the switching element 9A is closed, the electrolysis module 3A can be completely bridged. In the electrolysis cell 35B connected in parallel with the electrolysis cell 35A, the switching device 6 has a thyristor 11 as a switching element 9B. The thyristor 11 is designed as a power component for large switching currents and has a short switching time of only a few milliseconds, in particular about 3 ms, so that the electrolysis module 3B can be bridged in a short time when the thyristor 11 is triggered. In the electrolysis cell 35C, the following circuit is selected: the switching device 6 bridges all electrolysis modules 3A, 3B and thus bridges the entire electrolysis cell 35C. Directly at the output 23 of the rectifier 29, the two supply lines on the positive and negative poles can be bridged by means of a switching device 6, that is, can be joined to form a short circuit if necessary. For illustration purposes only, Figure 1 In the example, both the design of the switching element 9B with a thyristor 11 and a power resistor 7 and the switching element 9A with an electromagnetically triggerable switch or contactor are shown. Both designs can be implemented individually or in combination in the switching device 6. It is preferably provided here (in Figure 1 (not shown in detail), according to the bridging situation, for the desired complete bridging, the switch contacts are constructed so that the first electrical contact leads to the electrolytic tank 35C and the second electrical contact leads to the power resistor 7. Thus, the complete bridging of the electrolyzer 35C can be achieved.

[0080] The power resistor 7 is designed for overload and its resistance value is settable or adjustable so that it can be adapted to the respective application. The overload design allows the power resistor 7 to operate when it is powered for up to five seconds, in particular up to 10 seconds, and the load current decays. Thus, even short-term operation above the rated current is possible, and very high power can be drawn via the power resistor 7 during the bridging period.

[0081] During the operation of the composite device 100, green electricity is generated in the wind power device 31. The alternating current generated in the generator is converted into direct current in the rectifier 33. As a result, a direct current power supply is provided by the wind power device 31, so that the direct current is directly fed into the input end 21 of the electrolysis device 1 via the output end of the rectifier 33, and is first transmitted to the interface unit 19. In the interface unit 19, the circuit is galvanically isolated by the transformer 25, so that stray currents and ground faults that may damage the electrolyzer 5 in the composite device 100 are also effectively suppressed or even avoided. First, in order to connect to the primary side of the transformer 25, it is converted into an alternating voltage. The transformer 25 transforms the alternating voltage so that the desired voltage level is achieved on the secondary side according to the set transformation ratio. The rectifier 29 provides an electrolysis direct current voltage without interference or ripple on the output side of the output end 23, so that the electrolysis cells 35A, 35B, 35C in the electrolysis device 1 are stably operated with the electrolysis direct current voltage, wherein the separated water is decomposed into hydrogen and oxygen. Ground loops are effectively avoided by galvanic decoupling. In addition, due to the advantageous direct DC connection of the electrolysis system 1 to the wind energy system 31, island operation independent of the grid is possible and, depending on the application, green electricity can be generated decentralized onshore or offshore. In this case, the share of green hydrogen produced is 100%.

[0082] In principle, the electrolysis device 1 can also be connected in a DC manner to a photovoltaic device or another renewable energy device, such as a so-called CSP device (Concentrated Solar Power) or to an energy storage device in a complex device 100 that is charged with renewable energy. However, for operation in the complex device 100 with direct connection to the wind energy device 31, the electrolysis device 1 is advantageously designed and can be operated reliably and flexibly, in particular due to the DC-conducting switching device 6. During operation of the electrolysis device 1, separated water is supplied to the electrolysis cell 5 via the electrolysis modules 3A, 3B and decomposed into hydrogen and oxygen.

[0083] Figure 2 FIG. 1 shows a detail of an electrolysis device 1 having an electrolysis cell 35, which has four electrolysis modules 3A, 3B, 3C, 3D and three switching devices 6 capable of direct current conduction. Figure 2 Compared to the illustrated switching device 6 , the switching device 6 is further designed for flexible operation of the electrolysis system 1 , in particular for partial load operation of the electrolysis cells 35 of the electrolysis system 1 .

[0084] Each of the electrolysis modules 3A, 3B, 3C, 3D includes a plurality of axially stacked electrolysis cells 5. These electrolysis cells 5 are arranged between two pressure plates 37. The pressure plate 37 presses the electrolysis cells 5, which particularly include proton exchange membranes, tightly and firmly together, so as to achieve electrical contact between adjacent electrolysis cells 5 and the liquid-tight battery stack. The pressure plate 37 arranged at the axial end (i.e., the edge) of the electrolysis cell 35 is electrically connected to a DC power supply via an electrical connector 39. Three switch devices 6 are arranged in parallel with the electrolysis modules 3B, 3C, and 3D of the electrolysis cell 35. The switch device 6 is arranged in electrical parallel with the electrolysis module 5. In this example, the corresponding electrolysis modules 3B, 3C, and 3D can be electrically bridged by the corresponding switch devices 6. Here, each switch device 6 is electrically connected to the pressure plates 37 that define the corresponding electrolysis modules 3B, 3C, and 3D.

[0085] In this exemplary embodiment, in the switching state shown, electrolysis, in particular the decomposition of water into hydrogen and oxygen, takes place in all electrolysis modules 3A, 3B, 3C, 3D of the electrolysis cell 35, since all switching devices 6 are open. The electrolysis is carried out with direct current. The switching devices 6 are each designed as switching devices 6 that can conduct direct current, so that different current paths are available for bridging.

[0086] and Figure 2 The electrolysis device 1 Figure 1 Compared with the embodiment of the present invention, an additional current path is established in the switching device 6 in parallel with the current path through the accessible power resistor 7. The additional current path has an additional switching element 13 and a forward diode 15 and / or a low-resistance resistor 17 connected in series with the additional switching element 13. In the closed state, the additional current path has a lower resistance than the electrolytic cell 5, so that when the electrolytic cell 5 is bridged, the polarity and protection voltage of the electrolytic cell 5 are maintained. Various circuit technology implementations and combinations for the additional current path are possible. For example, the electrolysis modules 3B and 3C can be bridged via corresponding additional current paths, wherein, through the additional switching element 13, the current path can only be closed in the forward direction via the corresponding diode 13. When the additional switching element 13 is closed, the electrolysis module 3D can be bridged via the low-resistance resistor 17, thereby closing the corresponding additional current path. The diode 15 is connected in series with the additional switching element 13 in the forward direction. Advantageously, when the additional current path is closed, the polarity and the protection voltage of the electrolysis cell 5 or the electrolysis module 3B, 3C, 3D are maintained. A combination of a diode 13 and a low-resistance resistor 17 may also be provided in the additional current path, which is Figure 2 Possibly advantageous circuit variants are not specifically shown in FIG.

[0087] The electrolysis device 1 has a plurality of electrolysis cells 5 connected in series, thereby forming electrolysis modules 3A, 3B, 3C, 3D. When another current path is activated by closing another switching element 13, the corresponding electrolysis modules 3B, 3C, 3D are bridged, wherein the polarity and protection voltage are maintained for the bridged electrolysis modules 3B, 3C, 3D. This is particularly advantageous for the partial load operation of the electrolysis device 1, which is thereby improved. Then, as required, individual or multiple electrolysis cells 5, one or more electrolysis modules 35 can be short-circuited by another current path provided by the switching device 6, and thus no hydrogen is produced, that is, the operation can be stopped. This should only be done in the case of avoiding harmful fuel cell operation, for example, by using a pole rectifier that advantageously supplies power to each cell individually. Therefore, in conjunction with the current path provided in parallel in the switching device 6 by the power resistor 7, the electrolysis device 1 can be overloaded, for example, in the case of high wind power feeding, and the electrolysis device 1 can be operated at partial load, with great operational flexibility and operational reliability. A temporary shutdown can also be used to safely carry out any necessary emergency shutdown of the electrolysis module by bridging operation or planned shutdown, for example for maintenance purposes.

[0088] The electrolysis equipment 1 is in the switch device 6 Figure 2 The switching state shown is full load operation. If the electrical power in the network decreases, in particular due to low wind and sunlight, at least one switching device 6 can be closed. Thus, the electrolysis modules 3B, 3C and 3D can be switched off in a modular manner or bridged via other current paths. Figure 2In the example of , when the electrolysis device 1 is running, the electrolysis module 3A is always running. However, a bridging current path can also be set by a switch device 6 connected to the electrolysis module 3A. If the individual electrolysis modules 3B, 3C, 3D are now cut off or bridged according to the available feed power during operation, the electrolysis module 3A can continue to operate at a constant power density, for example, at full load. Thus, advantageously, the electrolysis modules 3A, 3B, 3C, 3D or the electrolysis cell 5 are not operated under partial load. It is particularly advantageous to bridge the electrolysis modules 3B, 3C, 3D one after another in time. In particular, the module 3B can first be bridged for a predetermined time period. Then the electrolysis module 3C or the electrolysis module 3D can be bridged for the corresponding time period. The electrolysis modules 3B, 3C, 3D are therefore uniformly operated and loaded. By bridging via another current path, the electrolysis cell 5 is prevented from aging rapidly. In addition, it is also ensured that the product gas quality, especially hydrogen, always remains at a high level. At the same time, however, during operation, the supplied electrical power can also be flexibly adapted to the reduced input power of the electrolysis device 1, wherein the electrolysis current is reduced and causes the current intensity via the power resistor 7 to decrease over time, in that the current path via the power resistor 7 is then optionally closed. The further parallel current path via the low-resistance resistor 17 then remains open.

[0089] exist Figure 2 In the embodiment of the invention, the electrolysis cell 35 has four electrolysis modules 3A, 3B, 3C, 3D. This is a simplified diagram. It is also within the meaning of the invention to connect more electrolysis modules in series. It is also possible to arrange further staggered interconnections of the switching devices 6 in order to provide a sufficient number of switching devices 6 on the one hand and to prevent an excessive number of switching devices 6 and thus complexity on the other hand. It is also very advantageous to integrate the electrolysis cell 35 into a complex electrolysis device 1 with a plurality of corresponding electrolysis cells 35A, 35B, 35C, such as Figure 1 For this purpose, Figure 2 The electrical connector 39 and Figure 1 The output terminal 23 of the rectifier 29 of the electrolysis device shown in FIG. 1 is connected so that the electrolysis cell 35 is supplied with direct current.

[0090] Similar to Figure 1The manner shown is also very advantageous in that it is integrated into the entire composite device 100, which includes an electrolysis device 1 and a wind energy device 31 directly connected to the electrolysis device 1. For this purpose, the wind energy device 31 has an output for providing direct current, wherein the output is connected to the input 21 of the electrolysis device 1. In the composite device 100, the wind energy device 31 has a rectifier 33, which is connected to the input 21 of the electrolysis device 1 on the DC side. Alternatively, it is also feasible that the required rectification of the alternating current originally generated by the wind energy device 31 in the generator is carried out near the electrolysis device itself. As a result, the rectifier 33 can be placed at or near the electrolysis device 1. Therefore, the rectifier 33 with an output for direct current for electrolysis can also be a device component of the electrolysis device 1 itself, or can be functionally regarded as such in the structural design of the composite device 100.

[0091] Although the present invention has been described in detail by means of preferred embodiments, the present invention is not limited to the disclosed examples. Variations thereof may be made by those skilled in the art without departing from the scope of the invention defined by the accompanying claims.

Claims

1. An electrolysis device (1), comprising: An electrolysis module (3A, 3B), wherein the electrolysis module (3A, 3B) has a plurality of electrolysis cells (5) connected in series; and a switch device (6) electrically connected in parallel and capable of conducting direct current, wherein the switch device has an accessible power resistor (7), so that in a closed state, a current path through the power resistor (7) can be activated, thereby causing the electrolysis cells (5) to be bridged and being able to dissipate excess power through the power resistor (7).

2. The electrolysis device (1) according to claim 1, comprising at least two electrolysis modules (3A, 3B) connected in series, each of which has a plurality of electrolysis cells (5) connected in series.

3. The electrolysis device (1) according to claim 2, wherein: The switching devices (6) connected in parallel in the closed state bring about a bridging of the electrolysis modules (3A).

4. The electrolysis device (1) according to claim 2 or 3, wherein: In the closed state, the switching device (6) causes a plurality of electrolysis modules (3A, 3B) to be bridged.

5. The electrolysis apparatus (1) according to any one of the preceding claims, wherein: The switching device (6) has a mechanically closable switching element (9A), which is in particular designed as an electrically or electromagnetically activatable switch or contactor.

6. The electrolysis apparatus (1) according to any one of the preceding claims, wherein: The switching device (6) has a thyristor (11) as a switching element (9B), so that a current path through the power resistor (7) can be activated when the thyristor (11) is turned on.

7. The electrolysis apparatus (1) according to any one of the preceding claims, wherein: In the switching device (6), the switching element (9) is designed as a semiconductor element having an insulated gate bipolar transistor (IGBT), so that a current path through the power resistor (7) can be activated when the gate is open.

8. The electrolysis apparatus (1) according to any one of the preceding claims, wherein: The power resistor (7) is settable or adjustable.

9. The electrolysis apparatus (1) according to any one of the preceding claims, wherein: The power resistor (7) is designed for overload, so that the power resistor (7) can operate under current decay when powered on for up to 5 seconds, in particular up to 10 seconds, and can dissipate excess power.

10. The electrolysis apparatus (1) according to any one of the preceding claims, wherein: In the switching device (6), a further current path is arranged in parallel with the current path through the switchable power resistor (7), the further current path having a further switching element (13) and a forward diode (15) and / or a low-ohmic resistor (17) connected in series with the further switching element (13), and the further current path has a smaller resistance than the electrolytic cell (5) in the closed state, so that when the electrolytic cell (5) is bridged, the polarity and the protection voltage of the electrolytic cell (5) are maintained.

11. The electrolysis device (1) according to claim 10, comprising a plurality of electrolysis cells (5) connected in series to form an electrolysis module (3A), so that when the further current path is activated by closing the further switching element (13), a bridging of the electrolysis module (3A) is caused, wherein: The polarity and protection voltage of the electrolytic cell (5) are maintained.

12. The electrolysis device (1) according to any one of the preceding claims, comprising an interface unit (19) having an input (21) for connection to an external DC power source and an output (23) connected to the electrolysis module (3A), wherein: The interface unit (19) has a transformer (25) to which an inverter (27) is connected on the primary side and a rectifier (29) is connected on the secondary side, so that the electrolysis modules (3A, 3B) can be supplied with direct current.

13. A method for operating an electrolysis device (1) for splitting water into hydrogen and oxygen, wherein: An electrolysis device (1) according to any of the preceding claims is provided, wherein in normal operation at least two electrolysis modules (3A, 3B) are supplied with an electrolysis current, wherein hydrogen and oxygen are produced in the electrolysis modules (3A, 3B), wherein in the event of a failure of one of the electrolysis modules (3A, 3B), a bridging operation is introduced, wherein a current path through a power resistor (7) is activated, thereby bridging the faulty electrolysis module (3A, 3B), and wherein excess power is absorbed by the power resistor (7).

14. The method according to claim 13, wherein: The supplied electrical power is adapted to the reduced absorbed power of the electrolysis device (1), wherein the electrolysis current is reduced and causes the current intensity through the power resistor (7) to decay over time.

15. The method according to claim 14, wherein: The supplied electrical power is fed in from a wind power installation (31) to which the electrolysis installation (1) is connected, wherein in crossover operation the pitch angle of the rotor blades is adapted to the absorbed power of the electrolysis installation (1).

16. The method according to claim 13 or 14, wherein: Within a maximum of 10 seconds, in particular within a maximum of 5 seconds, the supplied electrolysis current is adapted to the reduced absorbed power of the electrolysis device (1).

17. A composite device (100) comprising an electrolysis device (1) according to any one of claims 1 to 12 and a wind energy device (31), wherein: An output terminal for providing direct current is provided, wherein the output terminal is connected to an input terminal (21) of the electrolysis device (1).

18. The composite device (100) according to claim 17, wherein: The wind energy installation has a rectifier (33) which is connected to the input (21) on the DC side.

Images