Device assembly comprising at least two electrolysis devices and power source

Abstract

The invention relates to a device assembly (100) comprising at least two electrolysis devices (1A, 1B), a power supply (3) having a DC voltage output (7), and a central power supply line (5), the central power supply line (5) being connected to the DC voltage output (7) of the power supply (3) such that DC power can be fed into the central power supply line (5) and a central DC network based on a high-voltage design is provided. The electrolysis devices (1A, 1B) are connected to the central DC power grid via a central power supply line (5). The power supply (3) has a wind power plant (19) as a power generator, to which a rectifier (13A) having a DC voltage output (7) is connected, the DC voltage output (7) being designed on the basis of the high voltage. In this case, at least one of the electrolysis devices (1A, 1B) is arranged on the foot of the wind tower of the wind power plant (19) and is connected there directly to the central supply line (5). The invention also relates to the use of a DC network in such a system assembly, in which a plurality of electrolysis systems (1A, 1B) are connected to a central supply line (5) for direct current, in which direct current is fed into the central supply line (5) at a predetermined high voltage via a direct current voltage output (7).

Description

Technical Field

[0001] The invention relates to an apparatus complex comprising at least two electrolysis apparatuses and a power supply. The invention also relates to a use. Background Art

[0002] An electrolysis device is a device that uses electric current to convert substances (electrolysis). Depending on the electrochemical electrolysis process, there are also many types of electrolysis devices, such as electrolysis devices for electrolyzing water.

[0003] Nowadays, hydrogen is produced from water, for example, by means of proton exchange membrane (PEM) electrolysis, anion exchange membrane or alkaline electrolysis. Electrolysis plants use electrical energy to produce hydrogen and oxygen from supplied water. The process takes place in an electrolysis stack consisting of a plurality of electrolysis cells. In the electrolysis stack, which is under direct current voltage (DC voltage), water is introduced as a reactant, wherein two fluid streams consisting of water and gas bubbles (O2 or H2) emerge after passing through the electrolysis cells.

[0004] The idea is to use the excess energy of renewable energies to produce valuable substances during periods of high sunshine and high winds, i.e. when solar or wind power generation is above average. One valuable substance can be hydrogen produced by water electrolysis plants in particular. For example, so-called renewable energy gas - also called EE gas - can be produced based on hydrogen. EE gas is a combustible gas obtained using electrical energy from renewable energies.

[0005] Hydrogen is a particularly environmentally friendly and sustainable energy carrier. It has the unique potential to realize energy systems, transport and large parts of the chemical sector without CO2 emissions. But in order to achieve this, hydrogen cannot come from fossil energy sources, but must be produced from renewable energy sources. At least nowadays, more and more electricity produced from renewable energy sources is fed into the public grid. Therefore, if the electrolysis plant is operated with electricity from the public grid, it can produce green hydrogen in a corresponding proportion depending on the power mix.

[0006] In electrolysis carried out on an industrial scale, direct current is mainly supplied via rectifiers that are connected to the grid. During the rectification of the AC voltage on the grid side, harmonics may be generated due to the way the rectifiers work, which can put stress on the AC grid and / or the DC grid.

[0007] Such an electrolysis device is disclosed in the publication EP 3 723 254 A1, which is connected to a public power grid and is accordingly powered by the mains. For this purpose, the electrolysis device has a circuit structure comprising four coil mechanisms and four rectifiers. The first coil of the coil mechanism is respectively connected to the DC voltage side of one of the rectifiers. The circuit structure also includes two transformers, which respectively have a primary winding and two secondary windings. The primary winding of the transformer is connected to a power grid, such as a medium-voltage power grid or a high-voltage power grid. In this way, although the iron content in the first coil is reduced, the desired DC current smoothing or suppression of harmonics can still be achieved.

[0008] One of the sources of renewable energy is the increasing use of wind power. In particular, large amounts of electricity can be achieved by so-called offshore wind power plants close to the coast. However, the challenge is that there are still large distances to be covered to the load. Therefore, the energy should be delivered to the load with as few losses as possible. Hydrogen is very suitable as a transport medium and energy carrier. For example, it can be transported in gaseous form via pipelines. The positive aspect here is that the hydrogen-carrying pipeline can also fulfil the function of an energy storage device, since the internal pressure can be varied within a certain range.

[0009] Based on these considerations, it is of particular economic interest 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 plant on an offshore platform in the maritime sector directly on or near the offshore wind power plant and to supply it with the generated electricity.

[0010] For inland areas, it is also proposed to directly produce hydrogen using electricity from onshore wind power plants or photovoltaic power plants, at least partially by directly connecting to and feeding into an electrolysis plant. In all these applications, the electrolysis plant is part of a so-called island grid. The electrolysis current is therefore not obtained from the public grid, but is directly provided by the wind power plant or PV plant and fed into the electrolysis cell of the electrolysis plant. The electrical energy generated by the wind power plant or PV plant may also be temporarily stored in batteries, for example. Compared with the above-mentioned grid-connected operation, this brings special challenges and problems with respect to the electrical connection and interconnection of the electrolysis plant with the corresponding EE power plant (whether a wind power plant or a photovoltaic power plant), in particular in order to ensure safe and especially trouble-free operation of the electrolysis plant in a plant complex directly connected to the EE power plant.

[0011] Whether in grid-connected operation or in island operation, technical solutions are highly desirable for the reliable and at the same time cost-effective electrical connection of one or more electrolysis plants to the corresponding power generator. This is particularly true when, in increasingly larger and more complex electrolysis plants or electrolysis systems, a large number of electrolysis cells must be supplied with power simultaneously and correspondingly connected to an external power source. This poses particular problems with regard to the cost-effective transmission of power from the corresponding power source to the electrolysis plants, which in these combined plants are partially connected together in a complex plant complex. Summary of the invention

[0012] The object of the present invention is therefore to provide a plant complex in which the most reliable and cost-effective possible electrical connection and supply of an electrolysis plant to a power source is achieved, wherein a high degree of operating flexibility is achieved, in particular with regard to the partial load capacity of the electrolysis plant.

[0013] According to the invention, this object is achieved by an installation complex comprising at least two electrolysis installations, a power supply with a DC voltage output and a central power supply line, wherein the central power supply line is connected to the DC voltage output of the power supply so that direct current can be fed into the central power supply line and a central DC grid designed based on a high voltage is provided, to which the electrolysis installations are connected via the central power supply line, wherein the power supply has a wind energy plant as an electrical power generator, to which a rectifier with a DC voltage output is connected, wherein the DC voltage output is designed based on the high voltage, and wherein the electrolysis installations are arranged at the foot of a wind tower of the wind energy plant and are directly connected thereto to the central power supply line.

[0014] The invention is based on the following problem recognition: when sometimes different external power sources are combined with the electrolysis equipment to form an equipment complex, connection problems and problems of efficient power transmission arise. This applies not only to island operation, but also to grid-connected operation when the electrolysis equipment is connected to the public power grid. Depending on the distance between the electrolyzer of the electrolysis equipment to be supplied with direct current and the corresponding power source, power transmission at low voltage can lead to very high material costs, such as the material costs of the electrical conductors used to limit transmission losses as much as possible. Especially in the case of large spatial distances, for example, if the generator in the wind power generation equipment is located in a nacelle at a high altitude, and the electrolysis equipment is arranged on the ground near the wind tower or further away. Just this simple example will easily use hundreds of meters of cables to power the electrolysis equipment and connect it to the power supply. Only the line distance and the corresponding material use lead to a large part of the cost for connecting and powering the electrolysis equipment. In addition, there are the costs of electrical facilities for connecting and transmitting power.

[0015] As a known solution, it is proposed on an industrial scale, for example, to reduce the power losses by reducing the current and increasing the voltage. In order to increase the transmission voltage, transformers are usually used. These transformers require an alternating voltage system, i.e. an AC power grid, which is designed for the current frequencies of 50 Hz to 60 Hz in grid operation. In fact, by selecting a higher transmission voltage, the transmission losses caused by the connecting lines and the power supply lines can be reduced. However, this design also has disadvantages, since the transformers are correspondingly large, heavy and expensive.

[0016] The combination of a renewable energy generator (EE device), which usually already provides a DC voltage, with an electrolyser also results in multiple conversions of the voltage form (DC-AC-DC), which increases losses and costs. Therefore, the power conversion on the path from the power source to the electrolyser should be reduced to the minimum necessary.

[0017] Especially for onshore wind and solar power plants, it is often necessary to connect the wind farm / solar farm in parallel to a public grid that operates with alternating current. This leads to the problem of finding an optimal supply topology that takes into account the number of conversions, distribution costs (e.g. material costs for copper and aluminum), grid influences and the partial load capabilities of the electrolysis system.

[0018] Previous approaches did not provide a satisfactory solution and lacked an integrated solution. Existing systems were used that were simply coupled to one another. This resulted in high conversion losses in the plant complex that were unnecessary and economically unacceptable on an industrial scale.

[0019] In order to solve the connection and transmission problems in a plant complex with multiple electrolysis plants as cost-effectively and efficiently as possible, the present invention proposes to connect the electrolysis plants via a central DC grid specially provided for this purpose. The DC grid provides a predetermined high voltage and power on a central power supply line and acts as a transmission and distribution grid for direct current. The required transmission power is led from the power supply via the central DC grid to the electrolysis plant, thereby providing the electrolysis current. The high voltage of the higher-frequency DC grid can be flexibly selected and adjusted to the required DC voltage connection value.

[0020] Therefore, the DC voltage output of the generator or solar power generation device can already be output at a predetermined high voltage with a suitable high voltage, and the DC power can be fed directly or via a DC-DC converter into the central power supply line of the DC grid. The predetermined high voltage, which is significantly higher than the conventional public grid voltage, reduces the material requirements and thus reduces the cost of the line downstream of the power supply. Therefore, depending on the required connection power of the connected electrolysis device, DC voltages of several kilovolts up to 100 kV and corresponding transmission powers are possible, based on which the DC grid is designed and these DC voltages are provided at the power supply connection of the power supply line.

[0021] The invention is particularly advantageous in that it also allows relatively large line distances between the power source and the electrolysis plant to be bridged particularly cost-effectively, without having to carry out a further AC conversion for step-up and step-down conversion. This would require a number of transformers, which would increase costs. This makes island grid operation of the electrolysis plant and the corresponding direct DC connection economically feasible, particularly in remote areas, for example in the case of remote onshore wind power plants. The transmission distance can be flexibly changed from a few kilometers to several hundred kilometers.

[0022] On the central power supply line, the high-voltage grid can be flexibly designed, adapted and regulated for the power supply, DC voltage level, transmission and distribution path and the power drawn by the connected electrolysis equipment based on the corresponding application. As a result, the corresponding electrolysis equipment can be directly powered and connected to it with DC and partial load operation can be achieved, wherein conversion losses are avoided compared to the AC intermediate circuit. The transformer can be omitted. The direct current can be fed into the central power supply line at the DC voltage output via the power supply. The electrolysis equipment in the equipment complex is connected to the central power supply line and obtains the DC power for the electrolysis process from the central DC grid.

[0023] This allows a very advantageous connection of any number of electrolysis plants to a power source via a central supply line, wherein the central DC supply line acts as a DC bus line in the plant complex. The advantage is that DC power can be transmitted with particularly low losses even over longer distances. In this way, compared with conventional connections and designs based on the available AC grid frequency, in particular material costs for lines and a large number of connecting transformers can be saved, but also installation space for plant components can be saved. In order to ensure a corresponding connected power, one or more DC branches, in particular electrically connected in parallel, can also be present, which form the central supply line in the sense of the invention.

[0024] The concept with a central DC supply line is easy to expand and is very flexible with regard to the number of electrolysis plants supplied via the DC grid and the type of power source. On the central supply line, the DC grid is also independent of or independent of the possible generation of the power fed into the central supply line. Thus, the plant complex can be designed for island grid operation, but can also be connected to the public grid. Advantageous combinations are also possible and can come from various power sources, for example from wind power, photovoltaics or hydropower.

[0025] In the plant complex according to the invention, it is provided that the power supply has as power generator at least one wind energy plant to which a rectifier having a DC voltage output is connected, wherein the DC voltage output is designed based on the high voltage.

[0026] In this way, the connection or direct current connection of the electrolysis device and the power supply to it by the wind power generation device are realized in the device complex via the central DC power supply line, wherein island grid operation is advantageously possible. If the device complex is operated in an island grid, it will not be connected to the public grid. Therefore, the grid frequency of 50 Hz to 60 Hz of the public grid is irrelevant for the design and operation of electrical components in the frequency-independent DC grid. In particular, component costs and conversion losses (such as transformers) or necessary conversion, transmission or re-rectification costs are omitted. This brings a more favorable cost position and provides flexibility for the design and selection of connecting components in the DC grid. Operation independent of grid frequency is achieved using a central power supply line designed as a DC bus.

[0027] Thus, greater distances and line distances between the power generator and the electrolysis plant can be advantageously and cost-effectively bridged without having to perform a further AC conversion for step-up and step-down conversions, which can only be accomplished using multiple transformers.

[0028] Furthermore, the respective regulation or switching on and off of the DC / DC converters preferably used allows the electrolysis units to be matched very precisely to the (fluctuating) power output of the power generator. If the individual electrolysis units fall below a critical power consumption threshold, the hydrogen concentration on the oxygen side can rise to unacceptably high levels, with the risk of explosion. Thus, critical states can be avoided and safer partial load operation can be achieved.

[0029] Furthermore, it is proposed in the invention that the electrolysis device is arranged in the plant complex at the foot of the wind tower of the wind energy plant and is directly connected there to the central supply line for direct current. In particular in the case of remote onshore wind energy plants, it is particularly advantageous to connect the electrolysis device to the DC bus line in the plant complex close to the wind energy plant. If a DC / DC converter is then preferably used, the intermediate line is designed with a high DC voltage, thereby reducing the use of materials such as copper and aluminum in particular and correspondingly reducing the manufacturing costs.

[0030] In a particularly preferred embodiment of the plant complex, the electrolysis plants are connected in parallel with one another relative to a central power supply line, wherein the electrolysis plants are connected to the central power supply line via corresponding connecting lines.

[0031] This makes use of the advantages of the DC bus principle with a central DC supply line, which enables and provides individual connection lines for the electrolysis plants. In a plant complex, the central DC supply network can be expanded flexibly as required and can be expanded to include additional electrolysis plants by adjusting the feed-in power of the power source fed into the DC grid to the required power draw of the electrolyzers.

[0032] In a preferred embodiment, a buck converter is connected in the connecting line, the input voltage of which corresponds to the high voltage in the central DC grid and the output voltage of which is designed based on the corresponding operating voltage of the electrolysis system.

[0033] It is particularly advantageous to use a plurality of modularly designed high-current DC / DC converters which are connected in parallel in a connecting line if necessary. This enables combined industrial use in a system complex with an electrolysis system.

[0034] A step-down converter converts an input voltage into a lower output voltage. It is also called a step-down chopper.

[0035] The connecting line advantageously forms a central DC branch or DC branch of a central power supply line for one or more electrolysis devices or electrolysis cells that can be operated with direct current. Thus, any number of electrolysis devices of any size can advantageously be connected to one or more such central DC branch lines by means of controllable DC / DC converters, in particular so-called step-down choppers or step-down converters.

[0036] The DC / DC converters each step down the DC voltage to the required value without significant conversion losses. In the plant complex, the electrolysis plant can therefore not only be regulated with respect to the electrolysis power, but can also be switched on and off. Partial load capacity or partial load control is achieved by regulating the electrolysis current. Island grid capacity is ensured by coordinating the power regulators, which brings significant cost advantages in the case of remote onshore or offshore plants. In order to provide higher electrolysis currents, several DC / DC converters can be connected in parallel as required and used in the connecting line.

[0037] In a preferred embodiment, the buck converter is therefore designed as a controllable buck chopper, so that the supply of the electrolysis device with electrolysis current can be adapted to the power source feeding fluctuating power into the central power supply line.

[0038] The controllability of the step-down chopper makes it possible to supply the electrolysis device with electrolysis direct current in a flexible and adjustable manner in the connection line for the electrolysis power. Whether the step-down converter is operated continuously or intermittently depends on the inductance, the switching frequency, the input voltage, the output voltage and the output current flowing. Since these parameters can change rapidly in some cases, the transition between the two operating modes must usually be taken into account (e.g. prevented) when designing the circuit (especially the controller). The two operating modes differ in terms of the control characteristic curve, i.e. the relationship between the output voltage and the duty cycle (see below) and in terms of interference radiation.

[0039] The buck converter is preferably designed as a controllable buck chopper, which controls the output voltage by pulse width modulation in uninterrupted operation. In this way, continuous operation of the buck chopper and the controllability of the electrolysis current supplied to the electrolysis device are achieved.

[0040] In a particularly preferred embodiment, the wind energy plant in the plant complex is designed without a mechanical transmission (ie without a gear) and is designed to operate with a variable rotor frequency, wherein the wind energy plant has a generator whose AC output is connected to the input of the rectifier.

[0041] In a particularly preferred embodiment, the power supply has a photovoltaic power plant as power generator, which has a DC voltage output, wherein the DC voltage output is designed based on the high voltage and wherein the DC voltage output is connected to a central power supply line.

[0042] The DC voltage level at the DC voltage output can thus be flexibly matched to a predetermined high voltage on the central DC supply line. A step-up converter, a so-called step-up chopper, is connected downstream of the PV generator as required to set a predetermined DC voltage level at the DC voltage output. This is necessary when the DC output of the photovoltaic power generation device itself cannot provide a sufficiently high DC voltage level to feed into the central supply line.

[0043] With this design, an advantageous connection or connection to the electrolysis device is achieved in the device complex on the power supply line via the central DC power grid and it is powered by the power obtained from the photovoltaic power generation device. Island grid operation based on photovoltaic power generation is possible. From a similar point of view, and based on the advantages of the above-mentioned connection of the electrolysis device with the wind power generation device, operation independent of the public grid frequency is carried out in the island grid, which can achieve particularly high design flexibility and self-sufficient application possibilities away from the public grid. Therefore, the grid frequency of the public grid of 50 Hz to 60 Hz is irrelevant to the design and operation of the electrical components in the DC grid. Here, at most a step-up chopper (DC / DC converter) is provided to increase the voltage of the PV generator when necessary, so as to achieve the precise feeding of direct current with a predetermined high voltage into the central power supply line.

[0044] In a preferred embodiment, the power supply has a hydroelectric power plant as power generator, which has a generator, wherein a rectifier having a DC voltage output is connected to the generator.

[0045] It is feasible and advantageous to use a generator in a hydroelectric power plant that has already output a frequency higher than the grid frequency directly at the generator output. Therefore, the generator of the hydroelectric power plant can be advantageously designed, for example, based on the frequency of the AC voltage input of the rectifier. Conversely, the rectifier can also be flexibly adjusted and selected according to the corresponding output frequency of the generator of the hydroelectric power plant. When connected to a hydroelectric power plant, due to this lower complexity and the smaller number of components, additional cost advantages can be generated, wherein the island grid operation of the device complex is also feasible here. The output speed of the generator and therefore its AC frequency are generated by the number of poles and the rotation speed. Therefore, the generator for the hydroelectric power plant in particular can be used for a higher frequency AC output, so that the corresponding rectifier is used in the device complex, which has an input designed based on a higher frequency. It is very advantageous to carry out operation independent of the grid, that is, there is no need to consider the grid frequency of the public grid. Therefore, in the central DC grid, frequency matching coupling is not required or omitted, which requires expensive large transformers, for example.

[0046] In a further preferred embodiment, the power supply is formed by a public power grid, wherein a rectifier is provided, the DC voltage output of which is designed based on the high voltage of a central power supply line.

[0047] Thus, if necessary and advantageously, a grid connection is provided in the plant complex, via which the grid current rectified by the rectifier can be fed into the central power supply line at a predetermined high voltage. The grid connection is advantageously designed for bidirectional operation, so that power can also be fed from the central power supply line into the public grid. Such a grid feed into the public grid may be necessary in order to usefully tap off power in the event of a reduction in the power draw of the electrolysis plant or a possible temporary excess of EE power on the side of the power generation plant (i.e. a wind power plant, a photovoltaic power plant or a hydropower plant).

[0048] It is also possible and advantageous to form or feed the power supply in a plant complex from a combination of different power generators (for example wind power plants, photovoltaic power plants or hydropower plants) which are connected to a central power supply line via respective DC voltage outputs.

[0049] Therefore, the device complex is advantageously designed and arranged to be connected to the public grid as required. Therefore, both grid operation and island operation are possible. If it is to be connected to the public grid, the rectifier can and is preferably designed as a central rectifier with corresponding performance, such as a central rectifier station, in order to save components and provide a central connection point for drawing and rectifying the mains power. This central connection to the public grid via the central rectifier can be implemented particularly easily, for example, at the grid connection point of a wind power generation device or a wind farm, where bidirectional use is provided. Here, when feeding into the central power supply line, the mains power is rectified, and when feeding into the public grid, the direct current from the central power supply line obtained from the DC grid is inverted.

[0050] For example, if a wind farm or solar farm is additionally connected to the public grid, the grid connection to the central DC grid formed by the central supply line can be achieved with an additional rectifier or inverter provided for this purpose. The voltage level of the DC branch can already be flexibly selected here and can be connected to the grid without an additional transformer. The rectifier or inverter can independently control the voltage on the output side in the DC branch by absorbing additional power from the grid or feeding excess power into the grid.

[0051] Preferably, the rectifier or inverter is designed as a bipolar type based on IGBT (Insulated Gate Bipolar Transistor), because in this case the grid feedback is low, which can save filters and reactive power compensation equipment. In addition, grid services can be provided. This is particularly advantageous when connecting to a weak grid, for example via long branch lines.

[0052] IGBT is a frequently used component in power electronics because it combines the advantages of bipolar transistors (such as good conductivity, high cut-off voltage, robustness) and the advantages of field effect transistors (almost power-free triggering). The significant advantages of IGBT are high voltage limit and high current limit, operating voltage up to 6500V, current up to 3600A, and power up to 100MW. As a result, IGBT can be used ideally in the rectifier 15 for the working range of the electrolyzer 3. Depending on the application, it is also conceivable to use so-called IGCT, i.e. integrated gate commutated thyristor. This reduces the wiring work, increases the maximum pulse frequency for triggering, and has better switching times when connected in series, which is advantageous. The application field of IGCT is high-power current converters. A single module usually switches currents of several thousand amperes at a typical cut-off voltage of 4500V.

[0053] In a particularly preferred embodiment, the power supply has a step-up converter with a DC voltage output, via which a predetermined high voltage can be provided for the central power supply line.

[0054] A boost converter, also known as a boost chopper or a boost regulator, is a form of DC voltage converter in electronics. The amplitude of the output voltage is always greater than the amplitude of the input voltage. Therefore, the DC voltage level at the DC voltage output can be flexibly matched to a predetermined high voltage on the central DC power supply line. The use of a boost chopper is particularly advantageous when combined with a PV generator as a power supply source, where the PV DC voltage is increased to provide a predetermined high voltage at the DC voltage output for feeding into the central power supply line.

[0055] Another particularly preferred aspect of the invention relates to the use of a DC network in the described plant complex, in which a plurality of electrolysis plants are connected to a central supply line for direct current, wherein the direct current is fed into the central supply line via a DC voltage output at a predetermined connection value of a high voltage.

[0056] In this application, a high voltage direct current having a predetermined high voltage far higher than the grid voltage is provided at the connection of the central power supply line. Thus, the electrolyzers of the electrolysis plant connected to the central DC bus line can be centrally powered individually via the DC grid.

[0057] In this application, the predetermined high voltage is preferably provided on the central supply line by a step-up converter having a DC voltage output whose output voltage is higher than 1.5 kV, in particular higher than 10 kV.

[0058] In this application, the central power supply line is particularly preferably operated at a high voltage direct current voltage of 10 kV to 110 kV, preferably 30 kV to 60 kV.

[0059] Compared to power supplies based on alternating current, the use of transformers is largely eliminated by central DC branching. Due to the design and provision of the central high-voltage direct current supply network, the use of material and installation space due to the weight and size of the transformer required for the AC grid connection can be significantly reduced. This reduces the use of materials, especially iron and copper, which in turn requires less installation space.

[0060] The present invention can be particularly advantageously used for the connection or electrical connection of a preferably onshore wind power plant with an electrolysis plant in a plant complex. When connected to an AC grid in conventional applications, the generator current is usually brought to a constant output frequency of 50 Hz using an inverter (AC-DC-AC) in order to connect a wind turbine with a variable rotor frequency without a mechanical transmission (i.e., a so-called "gearless" wind power plant). If an electrolysis plant is to be connected, the electrolysis plant can now be connected directly to a central DC power supply line (DC bus line), for example, simply at the foot of a wind tower. Due to the use of a DC / DC converter, the intermediate line can be designed with a high voltage to save materials such as, in particular, copper and aluminum and reduce costs.

[0061] By connecting a plurality of electrolysis plants in parallel, each comprising an electrolysis cell connected in series, a good partial load capability of the entire electrolysis system can be achieved on the central DC supply line. When required, the power of the wind energy plant can be exported to the AC grid. This is the case if an electrolysis plant fails, if the electrolysis cells of an electrolysis plant are under maintenance, or if the electrolysis is not designed for the peak power of the wind energy plant.

[0062] In the case of use in island grids, which is particularly advantageous, the grid-side converter can be omitted and the connection to the central power supply via corresponding connecting lines is designed according to the same principle between the generator and the corresponding electrolysis system with the electrolysis cell. In this case, the need for transformers is significantly reduced. Even if necessary, at most a relatively small high-frequency transformer is required for DC decoupling in order to ensure a cost-effective connection of the electrolyzer to the generator at high voltage.

[0063] Advantages and advantageous embodiments of the device complex according to the invention are to be regarded as advantages and advantageous embodiments of the corresponding use, and vice versa.

[0064] Further advantages, features and details of the invention are apparent from the following description of preferred exemplary embodiments with reference to the drawings. The features and feature combinations mentioned above in the description of the drawings and the features and feature combinations mentioned below in the description of the drawings and / or shown individually in the individual drawings 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

[0065] Embodiments of the present invention are explained in more detail with reference to the accompanying drawings. Here, schematically and greatly simplified are:

[0066] Figure 1 A plant complex having an electrolysis plant and a wind energy plant is shown;

[0067] Figure 2A plant complex having an electrolysis plant and a photovoltaic power plant is shown.

[0068] In the drawings, the same reference numerals have the same meaning. DETAILED DESCRIPTION

[0069] Figure 1 The device complex 100 according to the invention is shown. The device complex 100 comprises an electrolysis system 1 having two electrolysis devices 1A, 1B and a power source 3 connected to the electrolysis system 1. The power source 3 has a wind energy plant 19 as a power generator, which serves as a renewable energy plant (EE plant) and a source of green electricity. The electrolysis system 1 is supplied with electrolysis current via a central power supply line 5 to which a DC voltage is applied, so that a central DC bus line is formed by the central power supply line 5, via which the electrolysis system 1 can be directly supplied with direct current for the electrolysis process.

[0070] Each of the electrolysis devices 1A, 1B of the electrolysis system 1 is connected to a power supply connection 23A, 23B on the central power supply line 5 via a respective connecting line 9A, 9B, so that the electrolysis devices 1A, 1B are connected in parallel. Here, the electrolysis device 1A has at least one electrolysis cell 15A, and the electrolysis device 1B has at least one electrolysis cell 15B. The electrolysis cells 15A, 15B can be optionally designed as PEM electrolysis cells, AEM electrolysis cells (AEM: Anion-Exchange-Membran, anion exchange membrane) or alkaline electrolysis cells, wherein a combination is also possible. A large number of electrolysis cells 15A, 15B can be connected one after another in the branches of the corresponding electrolysis devices 1A, 1B to be supplied with power via the corresponding connecting lines 9A, 9B.

[0071] On one side of the power source 3, downstream of the wind energy plant 19, on the output side of the generator of the wind energy plant 19, a rectifier 13A is connected, which has a DC voltage output terminal 7. Therefore, the alternating current generated by the generator of the wind energy plant 19 can be fed into the central power supply line 5 at the DC voltage output terminal 7 as a DC current of a predetermined high voltage. A central DC grid based on a high voltage design is thus realized. In order to input and feed the power generated by the wind energy plant 19 into the central power supply line, no additional active components such as a transformer are required when connecting the wind energy plant 19 to the central power supply line 5, thereby realizing a particularly simple power supply topology.

[0072] The DC voltage level at the DC voltage output 7 of the rectifier 13A can be flexibly adapted to the corresponding requirements in the plant complex 100, wherein a high output voltage is selected as a predetermined high voltage, which is preferably greater than 1.5 kV. Here, when designing and laying out the central DC grid via the central power supply line 5, for example, the nominal voltages of the grid levels commonly used in energy transmission can also be used, or these values ​​can be used as a basis for the DC voltage level. Here, the electrical energy is transmitted to the high-voltage lines of various medium-voltage and high-voltage grid levels at the following common nominal voltages: 3 kV, 6 kV, 10 kV, 15 kV, 20 kV, 30 kV for medium voltage and 60 kV, 110 kV for high voltage. The central power supply line 5 is very advantageously used as a central DC bus line, through which a DC power supply based on high voltage is immediately possible for the electrolysis system 1.

[0073] For the connection and direct current supply of the electrolysis apparatus 1A, 1B to the operating voltage, the step-down converter 11A is connected in the connecting line 9A, and correspondingly, the step-down converter 11B is connected in the connecting line 9B. The input of the step-down converter 11A is connected to the central power supply line 5 via the supply connection 23A, and similarly, the input of the step-down converter 11B is connected to the central power supply line 5 via the supply connection 23B. On the output side, the step-down converters 11A, 11B are connected to the electrolysis cells 15A, 15B in the connecting lines 9A, 9B, respectively, so as to provide the electrolysis in the electrolysis cells 15A, 15B with corresponding direct current whose voltage level can be adjusted for the operating voltage. During the operation of the plant complex 100, a high-voltage direct current grid is provided on the central power supply line 5 as a central DC grid and is used to supply electrolysis current to the electrolysis apparatuses 1A, 1B connected in parallel to the central power supply line 5. By using high voltage, direct current can be provided, higher-frequency alternating current can be provided and fed into the central power supply line 5. The plant complex 100 can be designed or expanded particularly flexibly, for example by connecting additional electrolysis plants 1A, 1B including additional electrolysis cells 15A, 15B via connecting lines 9A, 9B. The plant complex 100 can advantageously realize an island grid operation independent of the grid.

[0074] The buck converters 11A, 11B connected in the connecting lines 9A, 9B are implemented as DC / DC converters (buck choppers) and are respectively designed so that their input voltage is equal to a predetermined high voltage in the central DC grid on the central power supply line 5, and their respective output voltages are adapted or set to the respective operating voltages of the electrolysis devices 1A, 1B. The buck converters 11A, 11B are designed as controllable buck choppers so that the supply of electrolysis current to the electrolysis devices 1A, 1B can be adapted and tracked by the power source 3 feeding power fluctuations into the central power supply line 5. The buck converters 11A, 11B can be designed, for example, as controllable buck choppers, which control the output voltage by means of pulse width modulation in uninterrupted operation, which enables continuous operation with particularly high performance.

[0075] exist Figure 1 In the illustrated plant complex 100, the electrolysis plants 1A, 1B can also be arranged, for example, at the foot of a wind tower of a corresponding wind energy plant 19 and directly connected there to the central power supply line 5. This is advantageous, for example, for onshore applications and installations of wind energy plants 19 in remote areas and for island grid operation. In this context, a wind energy plant 19 also refers to an onshore or offshore wind farm or wind farm with a large number of wind energy plants 19.

[0076] according to Figure 1 Alternatively or additionally, in the plant complex 100, the power source 3 can be connected to the public grid 25. For this purpose, Figure 1 As shown by the dotted line in , a separate power supply connection 23C is provided in the central power supply line 5. The connection with the public power grid 25 is realized via a connecting transformer 27 and a downstream rectifier 13B having a DC voltage output terminal 7. The rectifier 13B is designed so that its DC voltage output terminal 7 is designed based on the high voltage of the central power supply line 5 and outputs a predetermined high voltage based on the corresponding voltage level, that is, optionally, a medium voltage level of 3kV, 6kV, 10kV, 15kV, 20kV, 30kV, or a high voltage of 60kV or 110kV. The voltage level can be flexibly adjusted and changed. In addition, when the power supply connection 23C is used as a grid connection, bidirectional operation can be performed, so that if necessary, direct current can be fed into the central power supply line 5 from the public power grid 25, and direct current can also be output from the DC grid of the central power supply line 5.

[0077] Thus, if necessary, the current from the public grid 25 can also be fed into the central power supply line 5 at the supply connection 23C in a voltage-matched manner and provided for electrolysis purposes in the electrolysis system 1. It has been shown here that it is advantageous that by providing a connection to the public grid 29, for example, replacement requirements are met, for example when the wind energy plant 19 is not generating electricity due to maintenance or only generating electricity to a very limited extent or during dark periods, so that a backup solution is available to ensure the most continuous power supply to the electrolysis devices 1A, 1B for hydrogen production and their smooth operation. Sometimes, even in the case of insufficient DC power supply on the central power supply line 5, one or more electrolysis devices 15A, 15B can also be operated at partial load or disconnected from the DC grid. If necessary, a matched partial load operation is achieved in the corresponding connecting lines 9A, 9B by means of a controllable buck converter 11A, 11B, by which the DC power can be respectively controlled via the output voltage at the output of the buck converter 11A, 11B. In pure island grid operation of a system complex, replacement requirements cannot usually be taken into account due to the lack of an available connection to the public grid 29 .

[0078] In another embodiment of the device complex 100 according to the invention, Figure 2 An alternative power source 3 is shown for supplying direct current to the electrolysis system 1. Here, the power source 3 has a photovoltaic power generation device 21, which has a large number of PV modules (not shown in detail). The photovoltaic power generation device 21 can preferably be designed as a large-scale and powerful open-air device in sunny areas, for example, so that PV power with an electrical power of 10 MW and above is available for electrolysis. On one side of the electrolysis system 1, a DC power supply is used. Figure 1 The electrical connection and power supply of the substantially similar device concepts and corresponding device components, i.e. the electrolysis devices 1A, 1B, are carried out via a central power supply line 5, which is in turn designed as a central DC bus line or DC connecting branch. To achieve this, the electrolysis device 1A is electrically connected to the power supply connection 23A via a corresponding connecting line 9A, and the electrolysis device 1B is correspondingly electrically connected to the power supply connection 23B via a corresponding connecting line 9B.

[0079] In the plant complex 100 configured in this way, the power supply source 3 therefore has a photovoltaic power plant 21, a so-called PV generator, as an electric power generator. The PV generator already provides a DC voltage at the generator output, which can already be designed for a predetermined high voltage, in which case the DC voltage output 7 is formed by the PV generator output and is directly connected to the central power supply line 5.

[0080] However, for the photovoltaic power generation device 21 as the power source 3, in order to obtain a desired and favorable DC voltage level to feed the DC power into the central power supply line 5, as shown in FIG. Figure 2 As shown in the embodiment of FIG. 2 , a boost converter 17 may also be connected to the DC output terminal of the generator of the photovoltaic power generation device 21 .

[0081] The boost converter 17 is also called a boost chopper or a boost regulator (English: Boost-Converter or Step-Up-Converter), and is a special form of a DC voltage converter in power electronics. Here, the amplitude of the output voltage is always greater than the amplitude of the input voltage, so that a predetermined high voltage of a desired DC voltage level is provided at the DC voltage output terminal 7 by using the boost converter 17 for feeding. Higher voltage reduces material requirements and thus reduces line costs after being fed in by the power supply 3.

[0082] The boost converter 17 is designed based on the voltage level operating frequency and provides a predetermined high voltage at the output. Here, the boost converter 17 is designed to be controllable so that the output voltage provided can be flexibly adjusted. The power of the photovoltaic power generation device 21 is directly coupled at the DC voltage output 7 of the boost converter 17 and fed into the central power supply line 5. In order to transmit and receive power through the electrolysis system 1, the electrolysis devices 1A, 1B are connected to the central power supply line 5 via corresponding connecting lines 9A, 9B as described in more detail above. Through the corresponding step-down converters 11A, 11B, it is also possible to decouple the regulation of the electrolysis current demand in the connecting lines 9A, 9B, and thus achieve separate operating modes of these DC connection branches, which is particularly important for partial load requirements. It is also possible to feed the mains power from the public grid 23 into the central power supply line 5 in PV applications, and in a manner similar to Figure 1 to implement the design described in .

[0083] The invention proposes a plant complex 100 with which electricity, in particular from a renewable energy source 3, can be fed into an electrolysis system 1 having a plurality of electrolysis plants 1A, 1B, so that 100% green hydrogen can be produced in the electrolysis cells 15A, 15B. This is done very advantageously in the described plant complex 100, which comprises at least two electrolysis plants 1A, 1B, an energy source 3 and a central power supply line 5, which is designed as a central AC bus line and provides alternating current with an operating frequency higher than the grid frequency of the public grid. Thus, a higher-frequency AC grid is provided and used in the plant complex 100, wherein a plurality of electrolysis plants 1A, 1B are connected to and operated in the central power supply line 5, into which the higher-frequency alternating current is fed.

[0084] In order to operate the plant complex 100, a plurality of electrolysis plants 1A, 1B are connected to a central power supply line 5 for direct current, wherein the direct current is fed into the central power supply line 5 via a direct current voltage output 7 at a predetermined high voltage. In this case, a DC grid is formed by the central power supply line 5, and a central DC grid is used as a power supply topology for the electrolysis plants 1A, 1B. In the case of a photovoltaic power generation plant 21 as a power source 3, the predetermined high voltage on the central power supply line can be provided by a step-up converter 17 having a direct current voltage output 7, which has an output voltage higher than 1.5 kV, in particular higher than 10 kV. The central power supply line 5 can also be operated at a high voltage of 10 kV to 110 kV, preferably 30 kV to 60 kV with a direct current voltage. The predetermined high voltage can selectively correspond to a medium voltage level of, for example, 3 kV, 6 kV, 10 kV, 15 kV, 20 kV, 30 kV, or a high voltage of 60 kV or 110 kV. In particular, the voltage level can be flexibly adjusted and varied by using a controllable DC voltage converter as step-up chopper 17 and / or step-down converter 11A, 11B. This also applies in the plant complex 100 to the optional additional connection of the rectifier 13B to the public grid 25, which is advantageously designed as a controllable rectifier 13B and is used for bidirectional operation.

Claims

1. A plant complex (100) comprising at least two electrolysis plants (1A, 1B), a power source (3) with a DC voltage output (7) and a central power supply line (5), wherein: The central power supply line (5) is connected to the DC voltage output (7) of the power source (3), so that direct current can be fed into the central power supply line (5) and a central DC grid designed based on high voltage can be provided, and the electrolysis equipment (1A, 1B) is connected to the central DC grid via the central power supply line (5), wherein the power source (3) has a wind power generation device (19) as an electric power generator, a rectifier (13A) with a DC voltage output (7) is connected to the wind power generation device, wherein the DC voltage output (7) is designed based on the high voltage, and wherein the electrolysis equipment (1A, 1B) is arranged at the foot of the wind tower of the wind power generation device (19) and is directly connected thereto to the central power supply line (5).

2. The device complex (100) according to claim 1, wherein: The electrolysis devices (1A, 1B) are connected in parallel with one another relative to the central power supply line (5), wherein the electrolysis devices (1A, 1B) are connected to the central power supply line (5) via corresponding connecting lines (9A, 9B).

3. The device complex (100) according to claim 2, wherein: A buck converter (11A, 11B) is connected to the connecting line (9A, 9B), the input voltage of which corresponds to the high voltage in the central DC grid and the output voltage of which is designed based on the corresponding operating voltage of the electrolysis device (1A, 1B).

4. The device complex (100) according to claim 3, wherein: The step-down converter (11A, 11B) is designed as a controllable step-down chopper so that the electrolysis current supplied to the electrolysis device (1A, 1B) can be adapted to the fluctuation of the power supply (3) and feed power into the central power supply line (5).

5. The device complex (100) according to claim 4, wherein: The step-down converter (11A, 11B) is designed as a controllable step-down chopper which controls the output voltage by means of a pulse width modulation method in continuous operation.

6. The device complex (100) according to any one of the preceding claims, wherein: The wind energy generation device (19) is designed without a mechanical transmission and is designed to operate with a variable rotor frequency, and the wind energy generation device (19) has a generator, the AC output of which is connected to the input of the rectifier (13A).

7. The device complex (100) according to any one of the preceding claims, wherein: The power supply (3) has a photovoltaic power generation device (21) as a power generator, the DC voltage output terminal (7) of the photovoltaic power generation device is based on the high voltage design, wherein the DC voltage output terminal (7) is connected to the central power supply line (5).

8. The device complex (100) according to any one of the preceding claims, wherein: The power source (3) has a hydroelectric power plant as an electric power generator, the hydroelectric power plant having a generator, wherein a rectifier (13B) having a DC voltage output terminal (7) is connected to the generator.

9. The device complex (100) according to any one of the preceding claims, wherein: The power supply (3) is formed by a public power grid (25), wherein a rectifier (13B) is provided, the DC voltage output (7) of which is designed based on the high voltage of the central power supply line (5).

10. The device complex (100) according to any one of the preceding claims, wherein: The power supply (3) has a step-up converter (17) with a DC voltage output (7), via which a predetermined high voltage can be provided for the central power supply line (5).

11. Use of a DC grid in a plant complex (100) according to any one of the preceding claims, wherein: A plurality of electrolysis devices (1A, 1B) are connected to a central supply line (5) for direct current, wherein the direct current is fed into the central supply line (5) at a predetermined high voltage via a direct current voltage output (7).

12. The use according to claim 11, wherein: The predetermined high voltage on the central power supply line (5) is provided by a step-up converter (17) having a DC voltage output (7) with an output voltage greater than 1.5 kV, in particular greater than 10 kV.

13. The use according to claim 12, wherein: The central power supply line is operated at a high voltage DC voltage of 10 kV to 110 kV, preferably 30 kV to 60 kV.

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