Operating an electrolysis plant in a fault state

Abstract

The invention relates to a method for operating an electrolysis device, in particular when a fault condition occurs in the power supply, for example when a grid-side fault condition. Accordingly, a method for operating an electrolysis device is proposed, wherein the electrolysis device is provided with a product gas flow by means of a primary power supply and a primary fluid supply. According to the invention, it is provided that the primary power supply is monitored (S100) and that, when a fault condition in the primary power supply is detected (S110), the feed of the primary fluid supply (S120) and / or the output of the product flow (S130) is adapted.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for operating an electrolysis plant, in particular in the event of a fault condition in the power supply, for example in the event of a grid-side fault condition. BACKGROUND

[0002] In order to connect an electrolysis plant of industrial scale at a public grid, the electrolysis plant needs to comply with grid-connection conditions. The electrolysis plant must therefore have a so-called "Fault-Ride-Through" capability in order to prevent the electrolysis plant from being disconnected from the grid, for example in the event of a short-term voltage dip or voltage rise. In other words, the electrolysis plant needs to remain fully connected at the grid even in such a grid-side fault condition, as a result of which the grid operator can be ensured that the load or consumer is also present at the grid after the fault has been eliminated.

[0003] The grid operator would therefore face great difficulties in adapting the power supplied to the power required or consumed after the fault has been eliminated, if such an electrolysis plant were to be immediately disconnected from the grid in the event of slight fluctuations in the grid, for example in the case of a short-term short circuit. Because the power generation in the respective power plant and the distribution or loading in the grid cannot generally be adapted or scaled down in time. Accordingly, large power-consuming facilities, such as electrolysis plants, should remain connected even in the event of a fault condition in the power supply, such as a voltage dip.

[0004] Furthermore, the chemical treatment of the product stream downstream of the electrolysis, which continues (in series), has proven to be problematic in part. If the system that has to receive the product stream is unable to continue its operation as a result of a fault condition in the power supply, for example caused by the grid side, it should still be ensured that the electrolysis continues to be operated in order to be able to provide as much load as possible to the grid.

[0005] In order to demonstrate compatibility with the grid-connection conditions, specific rectifier systems can be implemented in current electrolysis plants, which have to be operated and connected even in the event of a fault condition. In addition, in particular, specific control units and pumps are also required, which have to be operated by means of an uninterruptible power supply system, such as a separate battery system, or which have to be able to be restarted quickly enough. However, such additional systems are expensive and require major adaptations in existing electrolysis plants, in particular since the facility that receives the product stream also has to be equipped accordingly.

[0006] Accordingly, there is a need to ensure that an electrolysis plant is cost-effectively connected at the power supply even in the event of a fault condition and to have a backup option in the event of a failure of the facility that receives the product stream as a result of an external fault. SUMMARY

[0007] Based on the known prior art, the object of the present invention is to provide an improved method for operating electrolysis equipment.

[0008] This objective is achieved by a method having the features of claim 1. Advantageous further improvements are derived from the dependent claims.

[0009] Accordingly, a method for operating an electrolysis unit is proposed, wherein the electrolysis unit provides a product gas flow by means of a primary power supply and a primary fluid supply. According to the invention, the primary power supply is monitored, and upon detection of a fault in the primary power supply, the feed into the primary fluid supply and / or the output of the product flow are adjusted.

[0010] Because of the adaptation to the feed of the primary fluid supply and / or the output of the product stream, at least the electrolysis can adapt to the current conditions and continue to operate at least partially under fault conditions. This also applies in particular when the supply of the primary fluid supply depends on the primary power supply. For example, it is possible to cause the primary fluid supply to be at least partially replaced by a secondary fluid supply that does not depend on the primary power supply by means of an actuating valve device.

[0011] Similarly, the output of the product stream can be specified and adapted accordingly. Therefore, for example, productivity can be temporarily reduced proportionally, and / or a portion of the product stream, particularly a portion of the byproduct gas stream, can be discharged or blown out. This can be particularly advantageous when further processing of the product stream (e.g., by chemical properties or through compression in downstream processes) is not possible under the current fault condition, for example when such further processing is particularly prone to errors during pressure fluctuations. Another reason could be: in the event of an external fault, the processing cannot continue due to unexpected grid interference. In this way, the preset system pressure can still be maintained accordingly.

[0012] In other words, the present invention ensures that electrolysis-based production does not need to be stopped, or at least not completely stopped. In this way, "Fault-Ride-Through" capability (FRT) is provided and guaranteed, even if downstream processes cannot continue operating. Advantageously, existing electrolysis systems can be utilized to provide the appropriate load to the grid, and the use of expensive additional components that would otherwise have to bear that load can be abandoned. Furthermore, if necessary, longer startup times for downstream processes can be accepted in this way, avoiding expensive and technically complex replacements there, thus eliminating the need for separate control units, pump systems, and / or uninterruptible power supply systems, at least in part.

[0013] Preferably, the primary power supply is the power grid. As mentioned above, for power grid stability, it is necessary to maintain the connection status of the electrolysis equipment or at least the electrolytic cells to prevent uneven load or overload on the power grid after troubleshooting. Here, the power grid can be connected to the electrolysis equipment, particularly by means of a conventional rectifier.

[0014] As described above, adaptation for the primary fluid supply and / or the generated product gas flow can be advantageously performed according to the corresponding valve switching. Preferably, adaptation for the primary fluid supply feed includes at least in part the use of a compressed gas storage buffer, or through this adaptation, the fluid supply is provided solely by the compressed gas storage buffer.

[0015] The feed adaptation offers the advantage that the corresponding pressure in the storage buffer enables the electrolyzer to receive an inflow. This is even in the event of a short-term power outage and when the primary fluid supply depends on, for example, the primary power supply. Here, for instance, when production is temporarily and only slightly scaled down if necessary, the inflow (particularly the inflow of water and coolant) can be the same as or reduced relative to the primary fluid supply. Depending on the starting gas and the product stream to be supplied, multiple compressed gas storage buffers can be provided, which can optionally contain different gases or gas mixtures.

[0016] To support the continued operation of the electrolysis equipment or at least the electrolytic cell, it can be further specified that when a fault condition is detected in the primary power supply section, the electrolysis equipment connects to an auxiliary generator, wherein the auxiliary generator operates by means of a gas flow from a compressed gas storage buffer and / or by means of at least a portion of a flow from a product gas flow.

[0017] In addition to or besides the compressed gas storage buffer on the inlet side for fluid supply, a gas flow can also be provided, which is then used for power generation. The auxiliary generator can therefore provide a secondary power supply that at least partially replaces the primary power supply. For example, the secondary power supply can completely replace the primary power supply when it is temporarily unavailable, wherein the secondary power supply can optionally be reduced relative to the primary power supply.

[0018] Here, the auxiliary generator can be coupled to the turbine in particular, so as to provide rotation that causes power generation according to the gas flow.

[0019] Because of the auxiliary generator, a secondary power supply can be provided, for example, for the electrolytic cell and / or fluid supply, thereby at least partially or completely eliminating the need for a separate uninterruptible power supply system relying on a battery system. However, one or more battery or capacitor banks can optionally be added. Such batteries, battery systems, or capacitors can, for example, be used for the secondary power supply or configured as a tertiary power supply, wherein these can, for example, power different parts of the electrolysis equipment or additionally support the power supply. However, even in such cases, the required battery capacity is significantly reduced by the auxiliary generator.

[0020] The auxiliary generator can also operate, at least partially, by means of a portion of the product gas stream. Here, the portion of the stream can specifically include or consist of electrolysis byproducts. In this way, a power supply can be provided based on the product gas stream itself, which in particular can support the continued operation of the electrolysis equipment or at least the electrolytic cell in the event of a short-term failure in the primary power supply.

[0021] Auxiliary generators can also provide secondary power to the heating system of electrolysis equipment. This heating capability is particularly advantageous when electrolysis equipment (e.g., electrolytic cells and / or fluid supplies) must be temperature-controlled to provide product flow. Furthermore, the power supply for the heating system is advantageous, especially for offshore and / or distributed electrolysis equipment if the equipment is electrically coupled, for example, to wind power and / or photovoltaic facilities. Therefore, heating is particularly advantageous when, for example, wind power facilities are not operating or cannot operate sufficiently for a period of time due to insufficient wind or photovoltaic facilities are not operating due to insufficient sunlight. In this way, heating is particularly advantageous to help overcome such downtime, especially during cold periods.

[0022] The electrical energy provided by the auxiliary generator can be further used, at least in part, to charge the batteries configured as a secondary or tertiary power supply unit in an electrolysis unit. For example, if the power of the electrolyzer is reduced and there is a surplus of electrical energy provided by the auxiliary generator, this surplus can be used efficiently to charge one or more batteries, which can then be used as a secondary or tertiary power supply unit at a later time.

[0023] While the auxiliary generator is preferably connected in the event of a fault in the primary power supply, it is also possible to specify that the auxiliary generator is connected during normal operation of the electrolysis equipment. Specifically, a portion of the product stream can be diverted for the operation of the auxiliary generator. In other words, it is also possible to specify that the stream of electrolysis byproducts is used to operate the auxiliary generator, enabling the charging of one or more batteries during normal operation of the electrolysis equipment, even when there is no fault in the primary power supply. This is particularly advantageous in the case of distributed or offshore electrolysis equipment, in order to provide sufficient secondary or tertiary power supplies for coupled, non-operational wind power and / or photovoltaic facilities.

[0024] Adapting the output of the product stream upon detection of a fault in the primary power supply section can also include discharging and / or storing at least a portion of the product stream in a compressed gas storage buffer. This portion of the stream can, in particular, include byproducts of electrolysis. Preferably, the electrolysis equipment is designed to provide hydrogen or other products that can be used as potential fuel. Therefore, it is particularly possible to specify that the portion of the stream includes or consists of the generated oxygen.

[0025] A potential advantage of the discharged portion of the flow is that, at least electrolysis can continue to operate when, for example, downstream chemical processing or other processes (such as compression) are interrupted. Here, the discharged portion of the flow can be further used to operate an auxiliary generator to provide secondary power, as described above. Alternatively or additionally, the portion of the flow, or another portion of the flow, can also be stored in a compressed gas storage buffer, wherein the contents of the compressed gas storage buffer are preferably also usable for operating the auxiliary generator.

[0026] This is particularly advantageous when there is no (additional) central power supply in addition to the primary power supply (e.g., in the case of offshore wind power generation equipment). Therefore, as described above, when the power generation of the electrically coupled wind power generation facility, which serves as the primary power supply, is interrupted, a portion of the flow stored in the compressed gas storage buffer can at least partially provide a secondary or tertiary power supply for the electrolysis equipment. In this way, the power required by expensive battery-based auxiliary systems can be significantly reduced.

[0027] The partial flow provided for the auxiliary generator and the compressed gas storage buffer can be formed from different byproducts. It can also be formed from the same byproducts, wherein the corresponding partial flow can be provided, for example, by actuation of a valve device downstream of the electrolyzer. Here, oxygen, as a byproduct in the production of hydrogen or other fluids used as potential fuels, can be particularly advantageously used for the partial flow. Because oxygen is typically provided as the main byproduct, it allows for a sufficient quantity to be provided to the auxiliary generator, thus providing a sufficiently stable partial flow.

[0028] Here, the use of the partial flow can optionally and / or additionally be specified during normal operation in order to achieve further efficiency improvements compared to the typically high losses in conventional electrolysis equipment.

[0029] Even if the electrolysis equipment is temporarily unable to be powered by the primary power supply, it is preferably stipulated that the electrolysis equipment remains at least partially connected to the primary power supply when a fault condition is detected. Preferably, for example, when downstream chemical processing or compression fails or is interrupted, at least the electrolyzer remains connected to the primary power supply. In other words, the electrolysis equipment is preferably able to continue to be connected to the power grid, even when, for example, the electrolyzer is operating by means of a secondary power supply. In this way, the consumer remains connected to the power grid, enabling it to contribute to grid stability or power balance during grid-side troubleshooting.

[0030] Here, the switching state of the electrolysis equipment and the primary power supply can be selected based on the characteristics of the fault state determined from the detected fault states and / or based on the type of the primary power supply. Therefore, for example, when a fault state is detected within preset limits, the electrolysis equipment or electrolytic cell can be shut down or interrupted. For example, the primary power source can be the power grid, where preset grid conditions in the grid connection conditions refer to the time interval during which the fault state occurs and / or until which voltage drops or rises, the electrolysis equipment should be connected to the grid and remain in operation. However, if the time interval is exceeded, the electrolysis equipment can, in principle, be decoupled or shut down. Preferably, however, the electrolysis equipment according to the invention continues to operate, operating independently of downstream processes in emergency situations, for example by means of secondary and / or tertiary power supplies, wherein this operation is supported by adaptation to the feed and / or product streams.

[0031] However, if the primary power supply is provided, for example, by wind power generation facilities, alternative boundary conditions can be preset, and faster disconnection and switching to auxiliary systems can be introduced, for example.

[0032] To support the continued operation of the electrolysis equipment, it can be further specified that the operation of the electrolysis equipment changes from regulation operation to control operation upon detection of a fault condition, or a pre-control operation is superimposed on regulation operation. Here, the duration of the fault condition can be determined based on the detected fault condition, and operation can be adapted based on the duration of the fault condition. This has particular advantages in enabling rapid adaptation to the feed and / or product flow. Similarly, based on the predicted duration of the fault condition (which can be determined, for example, based on a voltage sag and / or the type of fault condition), a specific control loop can be interrupted or stopped. This is especially true when the time required for the corresponding control loop is not significantly shorter than the predicted duration of the fault condition. Therefore, overcompensation during subsequent normal operation can be avoided. Attached Figure Description

[0033] Preferred further embodiments of the invention will be explained in more detail below with reference to the accompanying drawings. Herein lies:

[0034] Figure 1 A schematic diagram showing the power grid conditions and preset switching states; and

[0035] Figure 2 A schematic diagram of the method flow according to the present invention, with preferred process steps, is shown. Detailed Implementation

[0036] In the following description, preferred embodiments are illustrated with reference to the accompanying drawings. Here, identical, similar, or functionally equivalent elements in different drawings are given the same reference numerals, and repeated descriptions of these elements are partially omitted to avoid redundancy.

[0037] exist Figure 1 The diagram illustrates the power grid conditions for connected or to-be-connected electrolysis equipment. Here, lines represent the limiting conditions that the electrolysis equipment must adhere to, including pre-defined switching states that must be observed within or above the lines.

[0038] Here, in the current exemplary example for an undervoltage event, voltage (U) is depicted relative to time (t) in seconds. It is shown that, in the event of a voltage drop, as shown in region A1, the electrolytic equipment should, in principle, remain in the connected state. However, if a strong voltage drop is involved, for example in the 0V direction, as shown by the bottom dashed line, the connected and ready-to-operate state must only be maintained for a short time. In the current example, the time limit for this fault state is approximately 0.2 seconds. In the case of smaller voltage drops, the time to maintain the switching state should increase linearly. Above a preset threshold, as shown by the top dashed line for region A2, the switching state should generally be maintained independently of the duration of the existing fault state or the deviation of the voltage from the set value.

[0039] However, if the duration of the fault condition exceeds zone A1, as shown in zone B, then in principle, the electrolysis equipment is permitted to be disconnected from the grid at least temporarily, or its operation may be altered or stopped. If the electrolysis equipment meets these limiting conditions, it is grid compatible and, accordingly, possesses "Fault-Ride-Through" capability.

[0040] exist Figure 2 The diagram illustrates how a fault condition can be detected in the primary power supply section and what steps can be introduced to ensure the continued operation of the electrolysis equipment in the event of a fault.

[0041] Accordingly, in the first step S100, the primary power supply section of the electrolysis equipment is monitored, wherein in step S110, it is determined whether a fault condition exists in the primary power supply section. If no fault condition exists ("No"), the electrolysis equipment can continue to operate normally, S112.

[0042] However, if a fault condition is confirmed (“Yes”), the electrolysis unit can optionally be switched from regulated operation to controlled operation, S114. Furthermore, according to the invention, adaptations S120 for the feeding of primary fluid supply and / or adaptations S130 for the output of product stream can be performed. In particular, the primary fluid supply can be reduced here, S122, wherein, for example, the inlet-side water supply to the electrolyzer can be reduced. In this way, the fluid supply can be advantageously adapted to a reduction in the electrolyzer's productivity.

[0043] Alternatively or additionally, it can be specified here that the fluid supply at least partially includes the use of compressed gas storage buffers, S124, wherein each compressed gas storage buffer is capable of supplying a corresponding gas or gas mixture to the electrolyzer. Here, both the reduction of the primary fluid supply S122 and the use of the compressed gas storage buffers S124 can be achieved by corresponding actuation of the valve device.

[0044] Furthermore, the adaptation of the product stream output S130 can be achieved by discharging or blowing out a portion or the entire product stream S132. In this way, for example, even if further chemical processing or compression of the product stream downstream of the electrolyzer is interrupted, it can be ensured that the preset pressure conditions in the system are met, and the electrolyzer can continue to operate. Here, the portion or the entire stream can be stored in a compressed gas storage buffer, S134.

[0045] To support the operation of the electrolysis equipment, or at least the electrolytic cell, in the event of the primary power supply failure, a secondary power supply, S140, can be further specified. For this purpose, an auxiliary generator, S142, can be advantageously connected, which operates according to the coupled turbine and gas flow. In this respect, the discharged (partial) flow S132 is also particularly advantageous, especially because the (partial) flow S132 can be directly used for the operation of the auxiliary generator S142 to provide the secondary power supply for the electrolysis equipment, S140.

[0046] Here, the (partial) flow S132 provided to the auxiliary generator in step 142 can be the same (partial) flow used to fill the compressed gas storage buffer S134, or an alternative (partial) flow, for example, when different and (clearly) separable byproducts are provided in the product flow. Similarly, the compressed gas storage buffer filled in step S134 can provide a gas flow for the operation of the auxiliary generator in step S142, thereby providing a tertiary power supply unit, for example, if a sufficient partial flow or even no product flow is provided.

[0047] Furthermore, it can also be advantageous if the auxiliary generator connected and operated in step S142 is not used, or only used, for the secondary power supply of the electrolysis equipment, but for the heating system and / or for charging the battery system of the electrolysis equipment. Connecting the auxiliary generator according to a partial flow or compressed gas storage buffer can also be advantageous, independent of the presence of a fault condition in the primary power supply, to achieve more efficient use of the existing product flow, particularly for decentralized or grid-decoupled electrolysis equipment, such as electrolysis equipment electrically coupled to offshore wind power facilities.

[0048] Where applicable, all the various features shown in the embodiments can be combined and / or interchanged with each other without departing from the scope of the invention.

Claims

1. A method for operating an electrolysis device, wherein, The electrolysis equipment provides the product gas flow via a primary power supply and a primary fluid supply. Its features are, The primary power supply unit is monitored (S100), and when a fault condition is detected in the primary power supply unit (S110), the feed of the primary fluid supply is adapted (S120) and / or the output of the product stream is adapted (S130).

2. The method according to claim 1, wherein, The primary power supply unit is the power grid.

3. The method according to claim 1 or 2, wherein, The adaptation of the primary fluid supply feed (S120) includes at least in part the use of a compressed gas storage buffer (S124), or wherein, through the adaptation, the fluid supply is provided solely by the compressed gas storage buffer.

4. The method according to any one of the preceding claims, wherein, When the electrolysis equipment detects a fault in the primary power supply unit, it connects to an auxiliary generator (S142), wherein the auxiliary generator operates by means of a gas flow from a compressed gas storage buffer (S134) and / or by means of at least one portion of the product gas flow (S132).

5. The method according to claim 4, wherein, The auxiliary generator provides a secondary power supply (S140), which at least partially replaces the primary power supply.

6. The method according to claim 4 or 5, wherein, The auxiliary generator provides a secondary power supply for the heating system of the electrolysis equipment.

7. The method according to any one of claims 4 to 6, wherein, The electrical energy provided by the auxiliary generator is used at least in part to charge the batteries configured as the secondary or tertiary power supply unit of the electrolysis equipment.

8. The method according to any one of the preceding claims, wherein, Upon detection of a fault condition (S110), at least a portion of the product stream or the entire product stream is discharged (S132) and / or stored (S134) in a compressed gas storage buffer.

9. The method according to any one of claims 4 to 8, wherein, The partial flow includes generated oxygen or consists of generated oxygen.

10. The method according to any one of the preceding claims, wherein, The electrolysis equipment remains connected to the primary power supply unit at least partially when a fault condition (S110) is detected.

11. The method according to claim 10, wherein, The switching state of the electrolysis equipment and the primary power supply is selected based on the characteristics determined from the detected fault states and / or based on the type of the primary power supply unit.

12. The method according to any one of the preceding claims, wherein, When a fault condition is detected (S110), the operation of the electrolysis equipment changes from regulation operation (S114) to control operation, or a pre-control operation is superimposed on the regulation operation.

13. The method according to claim 12, wherein, The duration of the fault state is determined based on the detected fault state (S110), and the operation is adapted based on the duration of the fault state.

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