Device network comprising electrolysis device and power supply source

Abstract

The invention relates to a plant network (100) comprising an electrolysis plant (1, 1A, 1B), a power supply source (3) having a DC voltage output (7), and a central supply line (5), the central supply line (5) being connected to the DC voltage output (7) of the power supply source (3) such that a DC current can be fed into the central supply line (5), and providing a central DC network designed for high voltages, the electrolysis devices (1, 1A, 1B) are connected to a central DC network via a central supply line (5). The power supply source (3) as a generator comprises a wind turbine (19) to which a rectifier (13A) having a DC voltage output (7) is connected, where the DC voltage output (7) is designed for high voltages, and where a controllable energy storage system (17) is connected to a central supply line (5), where the controllable energy storage system (17) is designed for high voltages. The controllable energy storage system (17) is designed such that a direct current can be fed through the energy storage system (17) into the central supply line (5) as required, or can be discharged from the central supply line (5) and fed into the energy storage system (17). A DC power supply network is implemented in the device network (100), capable of independently applying and controlling three different DC voltage levels, a first DC voltage being provided as a battery voltage for charging and discharging a battery of the energy storage system (17), a second DC voltage being provided as a DC bus high voltage on the central supply line (5), and a third DC voltage being provided as a DC bus high voltage on the central supply line (5). And the third DC voltage is provided as a DC operating voltage of the electrolysis device (1). The invention further relates to a method for operating a corresponding network of devices (100).

Description

Field of the Invention

[0001] The present invention relates to a plant network which includes an electrolysis plant and a power supply source having a wind turbine as a generator. The present invention also relates to a method for operating such a plant network. Background Art

[0002] An electrolysis plant is a device that uses an electric current to cause a material transformation (electrolysis). Depending on the various electrochemical electrolysis processes, there are various electrolysis plants, such as an electrolysis plant for water electrolysis.

[0003] Currently, hydrogen is produced from water by proton exchange membrane (PEM) electrolysis, anion exchange membrane or alkaline electrolysis. The electrolysis plant produces hydrogen and oxygen from the supplied water by means of electrical energy. This process takes place in an electrolysis stack composed of a number of electrolysis units. In the electrolysis stack at direct current voltage (DC voltage), water is introduced as a reactant, whereby after the water passes through the electrolysis units, two fluid flows composed of water and bubbles (O 2 or H 2 ) escape.

[0004] The current research direction is to use the excess energy of renewable energy during periods of sufficient sunshine and strong wind (i.e., using solar or wind energy generation above the average level) to produce recyclable materials. Valuable materials can specifically be hydrogen, which is produced by a water electrolysis plant. For example, on the basis of hydrogen, so-called renewable energy gas, also known as renewable energy gas (RE-Gas), can be produced. RE-Gas is a combustible gas obtained from renewable resources by means of electrical energy.

[0005] Hydrogen is a particularly environmentally friendly and sustainable energy carrier. It has the unique potential to enable energy systems, transportation, and most chemical reactions without CO 2 emissions. However, to achieve this goal, hydrogen must not come from fossil energy, but must be produced by means of renewable energy. At the same time, at least an increasing proportion of the electricity generated by renewable energy is being fed into the public grid. Therefore, depending on the power mix, when operating the electrolysis plant with electricity from the public grid, a corresponding proportion of green hydrogen can be produced.

[0006] In industrial-scale electrolysis, the direct current is mainly provided by a grid-controlled rectifier. This rectification process of the AC voltage on the grid side generates harmonics due to the operating characteristics of the rectifier, which can cause load effects on the conversion grid and / or the DC grid.

[0007] This electrolysis device is disclosed in the published document EP3723254A1, which is connected to the public power grid and is thus equipped with mains power. For this purpose, the electrolysis device has a circuit arrangement including four coil groups and four rectifiers. The first coils of the coil arrangement are each connected to the DC voltage side of one of the rectifiers. The circuit arrangement also includes two transformers, each having a primary winding and two secondary windings. The primary windings of the transformers are connected to the power grid, such as a medium-voltage grid or a high-voltage grid. In this way, despite reducing the iron content in the first coils, a desired smoothing of the DC current or harmonic suppression can still be achieved.

[0008] The increasing use of wind energy is a source of renewable energy. Especially for coastal areas (so-called offshore wind farms), large-scale power output can be achieved. However, it is challenging to overcome the long-distance problem with users. Therefore, the energy should be transmitted to the users as losslessly as possible. Hydrogen is very suitable as a transport medium and an energy carrier. For example, it can be used in gaseous form through pipelines. The positive aspect here is that because the internal pressure can vary within a certain limit, the hydrogen-carrying pipeline can also function as an energy storage system.

[0009] Based on these considerations, it is of particular economic significance to produce hydrogen directly at the energy production site (i.e., self-sufficient and independent of the public power grid). For this purpose, it is proposed to install an electrolysis device directly on an offshore platform in the maritime sector or in the immediate vicinity of an offshore wind turbine and supply them with the produced electricity.

[0010] For land, a concept is also proposed, that is, at least partially using the electricity from onshore wind turbines or photovoltaic systems directly for hydrogen production by directly connecting to the electrolysis device. In all these applications, the electrolysis device is part of a so-called off-grid or stand-alone system. Therefore, the electrolysis current is not obtained from the public power grid, but is directly supplied from the wind turbine or PV system and fed into the electrolyzer of the electrolysis device. Compared with the above-mentioned grid-controlled operation, stand-alone operation poses very special challenges and problems for the electrical connection and interconnection of the electrolysis device with the corresponding renewable energy production device (whether it is a wind turbine or a photovoltaic system), especially for the electrolysis device directly connected to the RES production device to operate safely and without faults. Summary of the Invention

[0011] An object of the present invention is to propose a network of devices in which reliable operation of the electrolysis system can be achieved when the electrolysis system is connected to a wind turbine as a power supply source, where high availability and operating flexibility can be achieved, especially regarding the part-load capacity of the electrolysis system. Another object of the present invention is to propose a method for operating such a network of devices.

[0012] According to the present invention, the object for a device network is achieved by a device network comprising an electrolysis device, a power supply source having a DC voltage output, and a central supply line, wherein the central supply line is connected to the DC voltage output of the power supply source such that a direct current can be fed into the central supply line and a central DC network designed for high voltage is provided, the electrolysis device being connected to the central DC network via the central supply line, wherein the power supply source acting as a generator has a wind turbine, a rectifier having a DC voltage output being connected to the wind turbine, wherein the DC voltage output is designed for high voltage, and wherein a controllable energy storage system is connected to the central supply line, the controllable energy storage system being designed such that in the central supply line, by means of the energy storage system, a direct current can be fed into the central supply line as required or can be released from the central supply line and fed into the energy storage system, and wherein a DC power supply network is provided which enables three different DC voltage levels to be applied and controlled independently, wherein a first DC voltage is provided as a battery voltage for charging and discharging the accumulator of the energy storage system, wherein a second DC voltage is provided as a DC bus high voltage on the central supply line, and wherein a third DC voltage is provided as a DC operating voltage of the electrolysis device.

[0013] The term "high voltage" for the DC voltage level for the central supply line at the DC voltage output should not be understood in a restrictive manner, but rather in a functional manner. The scope of the term will be explained below.

[0014] The present invention has been based on the finding that the electrolyzers in the electrolysis device operating at low partial loads, the variable energy input, and the repeated shutdowns all have a negative impact on their efficiency, lifetime, and the purity of the hydrogen. However, when the energy source powering the electrolyzers is a renewable energy source (such as a wind turbine), these situations occur frequently due to its high variability.

[0015] Currently, the electrolysis device is directly connected to the renewable energy source as well as the power grid to smooth the power generation of the renewable energy source and avoid the above problems. However, this is not possible when the system operates in island mode without a power grid connection. Implementing island mode in the device network is particularly challenging.

[0016] The invention advantageously combines, in a network of devices, the concept of a central DC network available on a central supply line with a controllable energy storage system connected to the central DC supply line. The invention thus avoids any storage device that may be directly connected to a renewable energy source (such as a wind turbine) and the direct connection to the public grid with many deficiencies. Those concepts that directly connect a battery to the rectifier output of a wind turbine have been previously proposed in the art. This direct connection complicates the integration because, in operation, the voltage level on the battery needs to follow the output voltage level of the rectifier.

[0017] However, with this network of devices according to the invention, the renewable energy power generation from a wind turbine can be smoothed very effectively and the above problems can be avoided, wherein the controllable energy storage system is connected to the central supply line and is designed such that in the central supply line, via the energy storage system, a DC current can be released from the energy storage system and fed into the central supply line as needed, or the energy storage system can be charged by being powered with electrical energy from the central supply line.

[0018] Thus, the controllable energy storage system is integrated in the DC bus of a wind-powered electrolyzer system and is capable of independently and decoupledly applying and controlling three different DC voltage levels in the network of devices, which provides high operational flexibility for energy storage as well as smooth and efficient operation and control. The DC voltage level supplied to the electrolyzer system can vary according to the load or the hydrogen production rate. The DC voltage level closer to the generator can also vary according to the energy production rate or the availability of wind. The last one is the voltage on the energy storage system, which can vary according to the battery state. This allows the connection of energy storage units to ensure better operation of the electrolyzers of the electrolyzer system by reducing power fluctuations and the number of outages. This also allows the use of a generator-side rectifier system, which is designed to be similar or identical to current wind turbines. A particular advantage is that high availability and operational flexibility related to the low partial load capacity of the electrolysis system can be achieved.

[0019] In particular, the advantage to be pointed out is that the fluctuations in wind power generation during charging and discharging of the energy storage system are smoothed, and the operation of the electrolysis equipment in the low partial load case is also stabilized.

[0020] Furthermore, in order to solve the connection and transmission problems in a network of devices with electrolysis systems as cost-effectively and efficiently as possible, the present invention proposes connecting the electrolysis devices via a specially equipped central DC network. This DC power grid provides a specific high voltage and electric power on the central supply line and serves as a transmission and distribution network for direct current. Via the central DC power grid, the required transmission power is transmitted from the power supply source to the electrolysis devices so that electrolysis current is available. The high voltage of the DC network can be flexibly selected and adjusted to the required DC connection value.

[0021] In the network of devices, the power supply source acting as a generator includes a wind turbine, and a rectifier with a DC voltage output is connected to the wind turbine, where the DC voltage output is designed for high voltage. In this way, a connection or direct current connection is achieved in the network of devices via the central DC supply line and the electrolysis devices are powered by the wind turbine, where independent grid operation can be advantageously achieved in island mode. If the network of devices operates in an independent grid, it is not connected to the public grid. Therefore, the grid frequency of the public grid from 50 Hz to 60 Hz is irrelevant to the design and operation of electrical components in the frequency-independent DC power grid. In addition, there are no costs for components and conversion losses (such as transformers), or costs for necessary realignment, transmission, or rectification. This achieves a more favorable cost position, while the design and selection of connection components in the DC network are flexible. Operation independent of the mains frequency is achieved using the central supply line designed as a DC bus.

[0022] The term "high voltage" for the DC voltage level at the DC voltage output for the central supply line should not be understood in a restrictive manner. For example, preferably, when used, a DC voltage output is provided for a specific high voltage on the central supply line, the DC output voltage of which is higher than 1.5 kV, specifically, higher than 10 kV. However, the minimum voltage level of the DC high voltage needs to be higher than the required electrolyzer operating voltage. Generally, the DC voltage output is designed for the high voltage of the central supply line and outputs a specific high voltage at a corresponding voltage level (optionally, medium voltage levels of 3 kV, 6 kV, 10 kV, 15 kV, 20 kV, 30 kV, or high voltages of 60 kV or 110 kV) as required. The voltage level can be flexibly adapted and changed according to the specific applications and requirements of the network of devices.

[0023] The concept of a central DC supply line is easily scalable for the connected energy storage systems and is very flexible with respect to the number of electrolysis devices powered via the DC grid and the type of power supply source. The DC grid on the central supply line also enables decoupling and independence with respect to the possible production types of the electrical power fed into the central supply line. For example, the device network can in principle be designed for independent grid operation (island mode only) or can also be connected to the public grid. Favorable combinations are also possible and electrical power can be obtained from different power supply sources (such as wind energy, photovoltaics or hydroelectric power).

[0024] In an advantageous embodiment of the device network, the energy storage system comprises a storage unit and a bidirectional DC-DC converter, the storage unit comprises a storage battery, and the bidirectional DC-DC converter is connected to the storage unit and its DC voltage output is designed for high voltage.

[0025] This design of the energy storage system has significant advantages both for reliable and smooth discharging from the storage unit and for storing electrical energy in the storage unit. Due to the DC-DC converter, the voltage levels for discharging and storing can be flexibly adjusted. Thus, the storage voltage can be selected individually and independently compared to the high voltage applied on the central supply line according to the required DC voltage. Therefore, this decoupling via the DC-DC converter is beneficial for the stable discharging and charging of the storage device, i.e., the charging can be regulated and an appropriate charging voltage can be provided on the input side of the DC-DC converter. The storage battery is a component of the energy storage unit and is integrated therein. In addition to the storage battery, the energy storage unit can also include other types of storage devices that are not essentially battery-based. Then, the stored energy can be advantageously converted into electrical energy by the energy storage system and can also be discharged or charged via the storage battery.

[0026] In another advantageous embodiment of the device network, the storage unit comprises a storage battery, wherein the storage battery is connected to the input of the bidirectional DC-DC converter.

[0027] A battery energy storage system (BESS) connected to the central supply line via a DC-DC converter is a preferred solution because the charging and discharging of the battery can be carried out in a reliable and controlled manner. In addition, battery-based storage units (such as lithium-ion-based batteries) are reliable and commercially available in large quantities. Moreover, they can undergo many charge and discharge cycles and can also be discharged quickly and with high performance when needed. In this advantageous embodiment, the storage battery, which is part of the storage unit, is directly connected to the DC input of the bidirectional DC-DC converter.

[0028] Alternatively, nickel-cadmium-based batteries can also be used as battery energy storage devices, but nickel-cadmium batteries have a lower specific energy, which requires a larger volume for installations close to or integrated into wind turbines.

[0029] Alternatively or in combination with a BESS system, fuel cells with hydrogen storage devices can also be advantageously used, especially when hydrogen is already available in the plant network as a product of the electrolyzer.

[0030] In another advantageous embodiment of the plant network, a control device is provided by which the energy storage system can be controlled to store and release electrical energy.

[0031] The control device takes into account the current or predicted feed-in power of the wind turbine, the current or predicted power demand of the electrolysis device, and the current charge state of the energy storage system as input variables. Thus, as needed, the energy storage system can be charged or discharged by correspondingly controlling the bidirectional DC-DC converter using a control signal. The existing different DC voltage levels can be controlled, individually adjusted, and monitored by the control device, and the connected power electronics can be correspondingly adapted to the respective DC voltages, which brings particular advantages.

[0032] In another advantageous embodiment of the plant network, the electrolysis device is connected to a central supply line via a connecting line, wherein a DC-DC converter is installed in the connecting line, the input voltage of which corresponds to the high voltage in the central supply line, and the output voltage of which corresponds to the operating voltage of the electrolysis device.

[0033] With this design, the DC voltage level and thus the electrolysis power for operating the connected electrolysis system supplied via the connecting line can be individually adjusted and can be provided correspondingly at the output of the DC-DC converter or "DC chopper". Since the DC-DC converter is preferably controllable, this individual adaptation can be achieved in a controlled manner via the control device.

[0034] Furthermore, in another advantageous embodiment of the plant network, the DC-DC converter is designed as an adjustable buck converter such that the electrolysis current supplied to the electrolysis device is adaptable and adjustable, and this electrolysis current receives the fluctuating feed-in power from the power supply source in the central supply line.

[0035] Using the controllability of the buck converter, the direct current for electrolysis can be flexibly supplied to the electrolysis device via a connecting line, and the adaptation in terms of electrolysis performance can be achieved. Whether the buck converter operates continuously or intermittently depends on the inductor, switching frequency, input voltage, output voltage, and the supplied output current. Since these parameters may change rapidly in certain cases, when designing the circuit, especially when designing the controller in the DC-DC converter, the conversion between the two operating modes usually has to be considered. These two operating modes are different in terms of control characteristics (i.e., the dependence of the output voltage on the pulse duty factor) and radiation interference.

[0036] In a particularly advantageous embodiment of the device network, the DC-DC converter is designed as a controllable buck converter, which can regulate the output voltage by means of the pulse width modulation method in non-intermittent operation. In this way, the continuous operation of the buck converter and the controllability of the electrolysis current supplied to the electrolysis device can be achieved.

[0037] In another advantageous embodiment of the device network, the DC-DC converter is formed by an intermediate transformer, an inverter is connected to the intermediate transformer on the primary side, and a rectifier is connected to the intermediate transformer on the secondary side, so that the direct current can be supplied to the electrolysis device at a given operating voltage, where an AC intermediate circuit is formed.

[0038] The advantage of the AC intermediate circuit here is to isolate the primary coil and the secondary coil, and a higher voltage ratio can be achieved. Moreover, the AC frequency of this intermediate circuit here can be higher than the grid frequency and reach even kHz. This can significantly reduce the size of passive components (transformers, capacitors, inductors).

[0039] Through this very advantageous design of the DC-DC converter in the device network, an AC intermediate circuit is provided to connect the electrolysis device to the central supply line.

[0040] In the DC-DC converter, the inverter converts the DC voltage from an external DC power supply source into an AC voltage coupled to the intermediate transformer on the primary side. A rectifier is connected to the secondary side of the intermediate transformer, which ensures the reconversion into a DC voltage at the desired and predetermined voltage or current level for electrolysis. Therefore, the DC-DC converter is particularly advantageously designed with an AC intermediate circuit and is designed to be supplied with direct current from an external direct current source to supply electrolysis current to the electrolyzer of the electrolysis device. This is achieved by directly coupling or directly connecting the input to an external DC power source. As the external direct current source, preferably, a wind turbine device or a photovoltaic system can be advantageously connected to the electrolysis device, and one of them can be advantageously designed to operate in a so-called island mode and independently of the grid for both offshore applications and onshore applications.

[0041] An external DC power source can be directly connected to the input of the DC-DC converter via the AC intermediate circuit arrangement, thus enabling the supply of DC power to the electrolyzer. Due to the electrical isolation and decoupling via the AC intermediate circuit, this circuit arrangement reliably avoids the destructive interference of high-frequency stray currents and thus avoids ground fault currents and unwanted voltage losses in the electrolyzer. At the same time, a simple and reliable direct connection between the electrolysis device and a renewable energy production device (preferably a wind turbine) can be achieved, and off-grid operation is possible. In addition, due to the AC intermediate circuit, particularly good and flexible adaptation to changes in the voltage or current level on the power generation side can be advantageously achieved.

[0042] For another reason, electrical isolation by this concept in DC-DC connections is preferred, especially in electrolysis devices including alkaline electrolyzers that operate on the basis of alkaline electrolysis. Electrical isolation advantageously reduces the ground current and stray current in electrolysis. The reason is that the ground loop cannot be closed. Due to electrical isolation, the current loop is advantageously disconnected by the earth.

[0043] Preferably, the secondary side of the intermediate transformer in the AC intermediate circuit is not grounded. This design not only provides effective protection against high-frequency signal components on the connection cable of the power source, but also significantly reduces and suppresses DC stray current because it provides a closed ground loop again.

[0044] In the device network of the present invention, as electrical components, several inverter systems, transformer systems or rectifier systems can be arranged in parallel and / or in series in an input series output parallel (ISOP) or input parallel output parallel (IPOP) configuration to achieve current sharing and voltage superposition.

[0045] The voltage on the input side of the DC-DC converter is preferably selected to be higher than the voltage required for electrolysis operation. This reduces losses or the cross-sectional area required for copper or aluminum cables, which saves costs and also overcomes large line distances, for example, the line distance from the tower of a wind turbine several hundred meters high down to the electrolysis device.

[0046] In an advantageous embodiment of the device network, the rectifier is adjustable and / or designed as a three-phase rectifier, particularly designed as a B6 bridge rectifier.

[0047] Preferably, in the case where a B6 bridge rectifier is not applied, the wind turbine generator needs to be controlled by the rectifier. In this case, the rectifier is designed for bidirectional operation, which is not possible for a B6 bridge rectifier. Therefore, preferably, an active rectifier is applied together with an active control switch for bidirectional operation.

[0048] The controllability of the rectifier (advantageously designed as a three-phase regulator or a B6 bridge rectifier) enables the regulation of the total current generated by the rectifier and, thus, the operation of an electrolyzer connected to a DC-DC converter can be controlled (preferably via a control device), for example.

[0049] These controllable converters are preferably implemented as voltage source converters (VSCs) which also integrate current loop control.

[0050] Advantageously, in the device network, the AC frequency of the AC intermediate circuit in the DC-DC converter can be adjusted to a predetermined value.

[0051] By equipping the DC-DC converter with an AC intermediate circuit, it does not have to be connected to a common network and, thus, there is a high degree of freedom in the selection of the AC frequency of the transformer. Advantageously, a high-frequency transformer is provided here, enabling deviation from the usual frequency in the common network.

[0052] In another advantageous embodiment of the device network, the DC-DC converter is designed for an AC frequency in the AC intermediate circuit which is higher than the usual mains frequency of 50 Hz to 60 Hz of the public power grid. The use of a higher frequency here makes sense because it can reduce the size and weight of the intermediate transformer as well as the use of materials. This aspect is particularly advantageous for an electrolysis device directly connected to a wind turbine. Due to the more compact design and lower weight at high operating frequencies, the transformer can be accommodated, for example, in the nacelle of a wind turbine or at the bottom of the tower of a wind turbine. The DC-DC converter as a whole can also be arranged there. Thus, an electrolysis device with an electrolyzer can be installed, for example, in the immediate vicinity of a wind turbine such that the cable path for connection can be short.

[0053] In a particularly advantageous embodiment, the circuit arrangement is designed for an AC frequency of 500 Hz to 50 kHz (especially from 10 kHz to 30 kHz). This frequency is related to the frequencies of the inverter and the rectifier connected to the intermediate transformer. To exploit the advantages of installation space as well as cost, a high-frequency transformer is provided as the intermediate transformer.

[0054] Furthermore, in an advantageous embodiment of the device network, the wind turbine includes a generator, the output of which is connected to the AC voltage input of the rectifier. This means that the rectifier is directly fed by the generator of the wind turbine.

[0055] The generator is preferably designed as a three - phase synchronous machine with permanent - magnet excitation. In the design of a permanent - magnet excited synchronous machine (PSM), the rotor can carry permanent magnets for excitation. This is becoming increasingly important. On the other hand, a hybrid synchronous machine (HSM) combines the action of reluctance and the action of permanent magnets for torque formation. The generator is driven by the rotor of a wind turbine and preferably provides three - phase current, i.e., three - phase alternating current, which is converted into direct current in the connected rectifier and fed into the central supply line at a specific DC high - voltage level.

[0056] Another object of the present invention is to propose a method for operating such a network of devices. According to the present invention, the object of the method is achieved by a method for operating a network of devices, wherein, in the charging phase, electrical energy from the central supply line is stored in an energy storage system, and in the discharging phase, electrical energy is released from the energy storage system and fed into the central supply line.

[0057] In an advantageous embodiment of the method, the network of devices operates in off - grid island operation.

[0058] This enables self - sufficient and completely off - grid operation, which is particularly suitable for offshore and onshore applications. In this process, independent of the grid charging and discharging of the energy storage system (especially the battery) is achieved.

[0059] The advantages of the network of devices described in detail above also apply to the method for operating such a network of devices. Description of the Drawings

[0060] In the following description of the examples and their variants, the characteristics, features, and advantages of the present invention described above and the ways to achieve them will be explained in more detail in conjunction with the drawings. The examples and corresponding variants are used to explain the present invention, rather than limiting the present invention to the combinations of features shown therein, even functional features. Furthermore, any feature disclosed in the following examples can be considered separately and appropriately combined with the features of any of the above - mentioned embodiments and their other aspects.

[0061] In which are shown:

[0062] Figure 1 A network of devices with an electrolysis device, which is connected to a wind power device via a central DC power supply line;

[0063] Figure 2 Another example of the present invention with a network of devices, wherein the electrolysis device is connected to the wind power device via an AC intermediate circuit;

[0064] Figure 3This is another example of the present invention, which shows a network of devices having a plurality of electrolysis devices connected to a wind power generation device and optionally connected to a public grid power supply device.

[0065] The same reference numerals have the same meanings in the drawings. Detailed Description

[0066] Figure 1 A schematic diagram showing an example of a device network 100 specifically designed for island mode operation is shown. The device network 100 includes an electrolysis device 1 having an electrolyzer 15, a power supply source 3 having a DC voltage output 7, and a central supply line 5. The central supply line 5 is connected to the DC voltage output 7 of the power supply source 3 such that direct current can be fed into the central supply line 5 and provides a central DC network designed for high voltage. The electrolysis device 1 is connected to the central DC network via the central supply line 5. The power supply source 3 includes a wind turbine 19 as a generator, and a rectifier 13A having a DC voltage output 7 is connected to the wind turbine 19. The wind turbine 19 has a turbine 45 with a rotor and a generator 39. The generator 39 is designed as a three-phase synchronous motor with permanent magnet excitation. The output of the generator 39 is connected to the AC voltage input 41 of the rectifier 13A via a three-phase current connection 47. The DC voltage output 7 of the rectifier 13A is designed for high voltage. A controllable energy storage system 17 is connected to the central supply line 5, which is designed such that direct current can be fed into the central supply line 5 through the energy storage system 17 as needed, or can be shunted and extracted from the central supply line 5 and fed into the energy storage system 17. The energy storage system 17 includes a storage unit 21 and a bidirectional DC-DC converter 29 such that current can pass through the DC-DC converter bidirectionally at corresponding DC voltage levels as needed. One voltage level is determined according to the charge and discharge conditions and the cycles that the storage device 21 has experienced. This first voltage level mainly depends on the battery state and operating conditions and may therefore vary during the life cycle (battery voltage). Another DC voltage is the DC high voltage (DC bus high voltage) provided on the central supply line 5. The DC voltage level on the DC bus may vary according to the amount of power generated provided by the generator 39 (fluctuating energy production from the turbine 45). Finally, another DC voltage is the operating DC voltage to be supplied to the electrolyzer 15 of the electrolysis device 1, and this operating DC voltage may vary especially according to the load of the electrolyzer 15 (operating voltage).

[0067] The electrolyzer 15 of the electrolysis device 1 is connected to the central supply line 5 via the connection line 9. A DC-DC converter 11 ("DC chopper") is installed in the connection line 9, and the input voltage of the DC-DC converter 11 corresponds to the high voltage in the central supply line 5. Therefore, the output voltage of the DC-DC converter corresponds to the operating voltage of the electrolyzer 15 in the electrolysis device 1.

[0068] The DC-DC converter 11 is designed as an adjustable buck converter. Therefore, the electrolysis current used to operate the electrolyzer 15 for the electrolysis device 1 can be adapted and regulated via the DC-DC converter 11, and this electrolysis current receives the fluctuating feed-in power in the central supply line 5 from the power supply source 3. To achieve this purpose, for example, the DC-DC converter 11 is configured as a controllable buck converter 11, which regulates the output voltage by means of the pulse width modulation method in a non-intermittent operation.

[0069] These measures allow the energy storage unit 21 to be connected and operated independently and decoupled by reducing power fluctuations and the number of shutdowns, ensuring better and smoother operation of the electrolyzer 15. This also allows the use of a rectifier 13A on the generator 39 side, and the design of the generator 39 is close to or the same as the design of today's wind turbines 19, which saves costs. Connecting the energy storage system 17 to a part of the voltage-stabilized DC supply system allows better control and coordination of the power of the converter units involved. The power input and output can be coordinated by the control device 31 controlling different DC voltages. This is not possible if the battery is connected in parallel to the rectifier in a DC system where the DC voltage changes with the energy production. This problem can be avoided in the design of the device network of the present invention. Another advantage is that hydrogen can be produced completely off-grid. This allows avoiding the high-cost electrical connection to the coast and significantly improving the efficiency by reducing the number of conversion steps.

[0070] In Figure 2 it shows a device network 100 with further improved operating behavior. This is an example of the present invention with the device network 100, where the electrolysis device 1 is connected to the wind power device 19 via an AC intermediate circuit. In order to implement the AC intermediate circuit most effectively and at reasonable cost, a DC-DC conversion is formed via the intermediate transformer 37, and the inverter 33 is connected to the intermediate transformer 37 on the primary side. The rectifier 35 is connected to the secondary side of the intermediate transformer so that a direct current can be supplied to the electrolyzer 15 of the electrolysis device 1 at a given operating voltage. The rectifier 35 is adjustable and is designed as a three-phase rectifier, especially designed as a B6 bridge rectifier. With this configuration of the AC intermediate circuit, a favorable electrical isolation is achieved, which realizes many advantages.

[0071] In Figure 1 the embodiment (not shown inFigure 1 (shown in detail therein), can also be applied to the Figure 2 intermediate transformer 37 similarly in the Figure 2 and the intermediate transformer 37 has been incorporated into the DC-DC converter 11. With this configuration, electrical isolation and decoupling similar to those in the Figure 1 are achieved, which reduces the stray current in the device network 100, and this stray current may endanger the operation of the electrolyzer 15, especially causing the electrolysis unit to deteriorate faster. Therefore, the AC current frequency of the AC intermediate circuit can be adjusted to a predetermined value, which provides further cost-saving opportunities and flexibility in selecting electrical components. Due to the AC intermediate circuit activated by the intermediate transformer 37, the DC-DC converter 11 (see

[0072] In Figure 3 Another example is schematically shown, which shows a device network 100 having a plurality of electrolysis devices 1A, 1B forming an electrolysis system 1, the electrolysis system 1 being connected to a wind power device 19, and wherein it can also be connected to the public grid 25 in the device network as an additional power supply option.

[0073] The device network 100 includes an electrolysis system 1 having two electrolysis devices 1A, 1B and a power supply source 3 connected to the electrolysis system 1. The power supply source 3 has a wind turbine 19 as a generator, which serves as a renewable energy source device (RES device) and a source of green power. The electrolysis current is supplied to the electrolysis system 1 via a central supply line 5, and the central supply line 5 is respectively loaded with a DC voltage and a DC current, so the central DC bus is formed by the central supply line 5, and the direct current for the electrolysis process can be directly supplied to the electrolysis system 1 through the central supply line 5.

[0074] Each of the electrolysis devices 1A, 1B of the electrolysis system 1 is connected to the power supply connections 23A, 23B via respective connection lines 9A, 9B and is connected to the central supply line 5, thereby realizing the parallel connection of the electrolysis systems 1A, 1B. The electrolysis device 1A has at least one electrolyzer 15A, and the electrolysis device 1B has at least one electrolyzer 15B. The electrolyzers 15A, 15B can optionally be designed as PEM electrolyzers, AEM electrolyzers (AEM: anion exchange membrane) or alkaline electrolyzers, and combinations thereof are also possible. More electrolyzers 15A, 15B can be connected in series or in parallel in the respective electrolysis devices 1A, 1B to be powered via the corresponding connection lines 9A, 9B.

[0075] On the power supply source 3 side, the wind turbine 19 is connected to the rectifier 13A via the generator of the wind turbine 19 (not shown in detail), and the rectifier 13A has a DC voltage output 7. Thus, the alternating current generated by the generator of the wind turbine 19 can be fed into the central supply line 5 as a direct current with a specific high voltage at the DC voltage output 7 via the rectifier 13A. Therefore, a central DC network designed for a high DC voltage is achieved. To couple the electric power generated by the wind turbine 19 and feed the power into the central supply line 5, no other active components (such as additional transformers, etc.) are required when connecting the wind turbine 19 to the central supply line 5, thus realizing a particularly simple power supply topology in the device network 100.

[0076] The DC voltage level at the DC voltage output 7 of the rectifier 13A can be flexibly adapted to the corresponding requirements in the device network 100, where the high output voltage is selected as a specific high voltage, which is preferably greater than 1.5 kV. Here, for example, in the design of the central DC network through the central supply line 5, the nominal voltages of the grid levels commonly used in the power transmission industry standards can in principle be applied, or these values can be used as an indication of the preferred DC voltage levels. Here, electrical energy is transmitted to the high-voltage line at different grid levels of medium voltage and high voltage, and the medium voltage and high voltage have the following typical nominal voltages: the medium voltage is 3 kV, 6 kV, 10 kV, 15 kV, 20 kV, 30 kV, and the high voltage is 60 kV, 110 kV. The central supply line 5 is very advantageously used as a central DC bus, which directly realizes the high-voltage-based direct current supply of the electrolysis system 1 and the connected electrolysis devices 1A, 1B.

[0077] The electrolysis devices 1A, 1B are connected and the DC power supply is adjusted to the operating voltage. Correspondingly, the step-down DC-DC converter 11A is connected to the connection line 9A, and the step-down DC-DC converter 11B is connected to the connection line 9B. The input of the step-down DC-DC converter 11A is connected to the power supply connection 23A, and similarly, the input of the step-down DC-DC converter 11B is connected to the central supply line 5 via the power supply connection 23B. On the output side, the step-down DC-DC converters 11A, 11B are each connected to the respective electrolyzers 15A, 15B via the connection lines 9A, 9B, so that a corresponding direct current can be provided for electrolysis in the electrolyzers 15A, 15B at an adjustable voltage level required for the operating voltage. In the operation of the device network 100, a high-voltage direct current is provided on the central supply line 5 which serves as the central DC network, and this high-voltage direct current is used to supply electrolysis current to the electrolysis devices 1A, 1B connected in parallel to the central supply line 5. The device network 100 can be designed or extended particularly flexibly, for example by connecting other electrolysis devices 1A, 1B including other electrolyzers 15A, 15B via the connection lines 9A, 9B. Advantageously, for the device network 100, independent operation independent of the power grid is possible in island mode operation.

[0078] The step-down DC-DC converters 11A, 11B connected to the connection lines 9A, 9B serve as DC / DC converters and are each designed such that their input voltage corresponds to a specific high voltage required in the central DC network on the central supply line 5, and their respective output voltages are individually adapted or adjusted to the respective operating voltages of the electrolysis devices 1A, 1B. The step-down converters 11A, 11B are designed as controllable step-down converters such that the supply of electrolysis current to the electrolysis systems 1A, 1B can be adapted or traced from the fluctuating feed-in power of the power supply source 3 in the central supply line 5. The step-down converters 11A, 11B can be designed as, for example, adjustable step-down converters that regulate the output voltage by means of a pulse width modulation method in a non-intermittent operation mode, which enables continuous operation at a selected performance. To control the active components in the network device 100, a control device 31 is integrated.

[0079] In Figure 3 the device network 100 shown, for example, the electrolysis devices 1A, 1B can also be arranged at the base of the tower of the respective wind turbines 19 and directly connected to the central supply line 5 at the base of the tower. This is advantageous for onshore applications and installations of wind turbines 19 in remote areas as well as for independent power grid operation in island mode. The wind turbines 19 also refer to a wind farm with various wind turbines 19 or an onshore or offshore wind farm.

[0080] As already in Figure 1 andFigure 2 As described in detail, for continuous operation in island mode, Figure 3 the device network 100 further includes a controllable energy storage system 17, and the controllable energy storage system 17 includes a storage unit and a bidirectional DC-DC converter 29. During operation, the discharge and charge modes of the energy storage system 17 are controlled by the control device 31. In addition to storage control, the control device 31 is designed and equipped with further control functions, such as active components in the device network 100. In particular, with the aid of the control device 31, DC current can be fed into the central supply line 5 through the energy storage system 17 as needed, or can be released from the central supply line 5 and fed into the energy storage system. Fluctuations from the wind turbine 19 can be sufficiently smoothed to improve the conditions for hydrogen production and maintain the stable operation of the electrolyzers 15A, 15B. For a typical large wind turbine 19 with a rated power of, for example, 3 MW to 5 MW, the energy storage system 17 is equipped with a battery having a capacity that is sufficiently high, higher than about 1.0 MWh, preferably about 5.0 MWh to 25 MWh. In particular, considering the predicted local wind conditions, the rated power of the wind turbine 19, the availability of the wind turbine 19, and the overall acquisition factor, the capacity can be pre-adapted and designed. It is also possible (most likely), preferably in the case where the battery will only process and compensate for large power gradients of the wind energy and will not store too much energy in the battery mainly, the battery can also have a capacity lower than the capacity indicated above. Therefore, in the energy storage system 17, if necessary, a fuel cell connected to the hydrogen storage container can also be used in parallel with or alternatively to the battery storage device for delivering energy over a longer period of time. For the energy storage system 17, this would be an advantageous combined solution that provides high flexibility.

[0081] According to Figure 3 the embodiment of, on the power supply source 3 side in the device network 100, it can also be connected to the public grid 25. To achieve this purpose, as Figure 3As shown by the dashed line in the middle, a separate power supply connection 23C is provided in the central supply line 5. The connection to the public grid 25 is realized via a connection transformer 27 and a downstream rectifier 13B with a DC voltage output 7. The rectifier 13B is designed in such a way that its DC voltage output 7 is designed for the required high voltage in the central supply line 5 and a specific high voltage is provided at the corresponding voltage level (optionally, the medium voltage level of 3 kV, 6 kV, 10 kV, 15 kV, 20 kV, 30 kV or the high voltage of 60 kV or 110 kV). The voltage level can be flexibly adapted and changed. In addition, when the power supply connection 23C is used as a grid connection, bidirectional operation is possible, so that DC current can be fed from the public grid 25 into the central supply line 5 in a demand-driven manner, and DC current can be supplied from the DC network of the central supply line 5. Another interesting and advantageous operation in this embodiment is, for example, in the case of supporting the grid, if necessary, using the energy storage system 17 to feed power to the public grid for a certain period of time. The connection to the energy storage system 17 is also shown, which can be activated by a controllable switching device 43, so that the DC current at the DC voltage output 7 of the rectifier 13B can be easily supplied to the bidirectional DC-DC converter 29 at the same voltage level to load the storage device when needed.

[0082] Therefore, in addition to the load storage device 21, as needed, the power from the public grid 25 can also be directly fed into the central supply line 5 in a voltage-adapted manner at the power supply connection 23C and provided for the electrolysis purposes of the electrolysis devices 1A, 1B. The particular advantage here is that by providing a connection to the public grid 25, for example, if the wind turbine 19 does not generate electricity due to maintenance, or only generates electricity to a very limited extent, or is in a long and continuous windless environment, it can meet the alternative demand, so that in addition to the storage device, another second backup solution is provided to ensure the most continuous supply and stable operation of the electrolysis devices 1A, 1B for hydrogen production. However, the energy storage system 21 is mainly used for smoothing fluctuations and outages (whether the public grid 25 is used or not), or for pure island mode deployment without backup supply from the public grid 25.

[0083] If necessary, even in the case of insufficient DC electrical power supply on the central supply line 5, one or more electrolyzers 15A, 15B can still operate at partial load or be disconnected from the DC grid. By means of adjustable step-down DC-DC converters 11A, 11B, adapted partial load operation is achieved in the respective connection lines 9A, 9B as required, by means of which the DC current power and the output voltage at the output of the step-down DC-DC converters 11A, 11B are adjustable in each case. In the pure stand-alone system operation of the plant network 100, there is usually no alternative requirement due to the lack of the option of a connection to the public grid 25. Therefore, the controllable energy storage system 17 is also very advantageous in the Figure 3 installation shown in order to maintain a high and smooth hydrogen production level during short-term fluctuations and during longer interruptions.

[0084] All the examples of the plant network 100 shown above enable, during the operation of the plant network 100, during the charging phase, electrical energy from the central supply line 5 to be stored in the storage unit 21 of the energy storage system 17, and during the discharging phase, the electrical energy to be released from the storage unit 21 and fed into the central supply line 5. The plant network 100 is understood to be available at any time in a fully off-grid island operation. A further advantage is that hydrogen can be produced completely off-grid. This allows the avoidance of a costly electrical connection to the coast and a significant increase in efficiency by reducing the number of conversion steps.

Claims

1. A device network (100), the device network (100) comprising electrolysis devices (1, 1A, 1B), a power supply source (3) having a DC voltage output (7), and a central supply line (5), wherein, the central supply line (5) is connected to the DC voltage output (7) of the power supply source (3) such that a direct current can be fed into the central supply line (5), and a central DC network designed for high voltage is provided, the electrolysis devices (1, 1A, 1B) are connected to the central DC network via the central supply line (5), wherein the power supply source (3) as a generator comprises a wind turbine (19), a rectifier (13A) having a DC voltage output (7) is connected to the wind turbine (19), wherein the DC voltage output (7) is designed for high voltage, and wherein a controllable energy storage system (17) is connected to the central supply line (5), the controllable energy storage system (17) being designed such that a direct current can be fed into the central supply line (5) through the energy storage system (17) as required, or can be released from the central supply line (5) and fed into the energy storage system (17), and wherein a DC power supply network is provided, the DC power supply network enabling three different DC voltage levels to be applied and controlled independently, wherein a first DC voltage is provided as a battery voltage for charging and discharging the battery of the energy storage system (17), wherein a second DC voltage is provided as a DC bus high voltage on the central supply line (5), and wherein a third DC voltage is provided as a DC operating voltage of the electrolysis device (1).

2. The device network (100) according to claim 1, wherein, the energy storage system (17) has a storage unit (21) and a bidirectional DC-DC converter (29), the storage unit (21) comprises a battery, the bidirectional DC-DC converter (29) is connected to the storage unit (21), and the DC voltage output (7) of the bidirectional DC-DC converter (29) is designed for high voltage.

3. The device network (100) according to claim 2, wherein, the storage unit (21) comprises a battery, wherein the battery is connected to the input of the bidirectional DC-DC converter (29).

4. The device network (100) according to any one of claims 1 to 3, wherein, control means (31) are provided, by means of which the energy storage system (17) can be controlled for storing and releasing electrical energy.

5. The device network (100) according to any one of the preceding claims, wherein, The electrolysis devices (1, 1A, 1B) are connected to the central supply line (5) via connection lines (9, 9A, 9B), wherein DC-DC converters (11, 11A, 11B) are installed in the connection lines (9, 9A, 9B), the input voltage of the DC-DC converters (11, 11A, 11B) corresponds to the high voltage in the central supply line (5), and the output voltage of the DC-DC converters (11, 11A, 11B) corresponds to the operating voltage of the electrolysis devices (1, 1A, 1B).

6. The device network (100) according to claim 5, wherein, the DC-DC converters (11, 11A, 11B) are designed as adjustable step-down converters such that the supply of electrolysis current to the electrolysis devices (1, 1A, 1B) is adaptable and adjustable, and the electrolysis current receives the fluctuating feed-in power from the power supply source (3) in the central supply line (5).

7. The device network (100) according to claim 6, wherein, the DC-DC converters (11, 11A, 11B) are designed as controllable step-down converters, and the controllable step-down converters are capable of adjusting the output voltage by a pulse width modulation method in non-intermittent operation.

8. The device network (100) according to claim 5, wherein, the DC-DC converter (11) is formed by an intermediate transformer (37), an inverter (33) is connected to the intermediate transformer (37) on the primary side, and a rectifier (35) is connected to the intermediate transformer (37) on the secondary side such that a direct current can be supplied to the electrolysis devices (1, 1A, 1B) at a given operating voltage, wherein an AC intermediate circuit is formed.

9. The device network (100) according to claim 8, wherein, the rectifier (35) is adjustable and / or is designed as a three-phase rectifier, in particular as a B6 bridge rectifier.

10. The device network (100) according to claim 8 or 9, wherein, in the DC converter (11), the AC frequency of the AC intermediate circuit can be adjusted to a predetermined value.

11. The device network (100) according to any one of claims 8 to 10, wherein, the DC-DC converter (11) is designed for the AC frequency in the AC intermediate circuit, and the AC frequency is higher than the normal mains frequency of 50 Hz to 60 Hz of the public power grid (25).

12. The device network (100) according to any one of the preceding claims, wherein, the wind turbine (19) includes a generator (39), and the output of the generator (39) is connected to the AC voltage input (41) of the rectifier (13A).

13. The device network (100) according to claim 12, having a generator (39), and the generator (39) is designed as a three-phase synchronous motor with permanent magnet excitation.

14. A method for operating a device network (100) according to any one of the preceding claims, wherein, During the charging phase, electrical energy from the central supply line (5) is stored in the energy storage system (17), and during the discharging phase, the electrical energy is released and fed into the central supply line (5).

15. The method according to claim 14, wherein, the device network (100) operates in off-grid island operation.

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