An electrolytic cell array system and a water electrolysis system control method

Abstract

The present application provides an electrolytic cell array system and a water electrolysis system control method, which relate to the field of water electrolysis technology. The electrolytic cell array system includes a plurality of gas-liquid separation devices and a plurality of electrolytic cell groups arranged in parallel, the electrolytic cell groups are connected to a converter, each electrolytic cell group includes a plurality of electrolytic cells arranged in series, the number of gas-liquid separation devices is the same as the number of electrolytic cells in the electrolytic cell group, wherein the electrolytic cells in the same order in the plurality of electrolytic cell groups are all connected to the same gas-liquid separation device. The electrolytic cell array system and the control method thereof provided by the present application have the effect of saving costs.

Description

Technical Field

[0001] The present application relates to the technical field of water electrolysis, and in particular to an electrolytic cell array system and a water electrolysis system control method. Background Art

[0002] With the rapid development of the new energy industry and UHV DC transmission technology, it is crucial to build a power system with new energy as the main body to increase the proportion of new energy power sources and the clean energy absorption capacity. New energy power generation is volatile and intermittent. As the proportion of new energy in the power system increases, the demand for power frequency regulation auxiliary services and power peak regulation auxiliary services has increased sharply. As a flexible and controllable load, the water electrolysis hydrogen production system can provide power auxiliary services, improve the flexibility of the power system's operation and dispatch, and enhance the absorption capacity of new energy power.

[0003] At present, water electrolysis hydrogen production equipment in the market is mainly divided into alkaline water electrolysis hydrogen production equipment, proton exchange membrane water electrolysis hydrogen production equipment, and solid oxide water electrolysis hydrogen production equipment. Generally, large-scale water electrolysis hydrogen production stations are built using alkaline water electrolysis hydrogen production equipment with a certain proportion of lithium battery energy storage.

[0004] However, since a large-scale water electrolysis hydrogen production station generally includes multiple electrolyzers, and each electrolyzer needs to be connected to a hydrogen / liquid separation device and an oxygen / liquid separation device respectively, the cost of the entire hydrogen production system is relatively high. Summary of the invention

[0005] The purpose of the present application is to provide an electrolyzer array system and a control method thereof to solve the problem of high cost of large-scale water electrolysis hydrogen production systems existing in the prior art.

[0006] In order to achieve the above purpose, the technical solution adopted in the embodiment of the present application is as follows:

[0007] In a first aspect, an embodiment of the present application provides an electrolytic cell array system, the electrolytic cell array system comprising a plurality of gas-liquid separation devices and a plurality of electrolytic cell groups arranged in parallel, the electrolytic cell groups being connected to a converter, each electrolytic cell group comprising a plurality of electrolytic cells arranged in series, the number of the gas-liquid separation devices being the same as the number of electrolytic cells in the electrolytic cell group, wherein:

[0008] The electrolytic cells in the same order in the plurality of electrolytic cell groups are all connected to the same gas-liquid separation device.

[0009] In a second aspect, an embodiment of the present application further provides a water electrolysis system, which includes a plurality of electrolytic cell array systems, wherein the plurality of electrolytic cell arrays are arranged in parallel.

[0010] In a third aspect, an embodiment of the present application further provides a method for controlling a water electrolysis system, wherein the water electrolysis system comprises a plurality of electrolytic cell array systems, wherein the plurality of electrolytic cell arrays are arranged in parallel, and the method comprises:

[0011] When receiving a power adjustment instruction, determining the external power demand of the system;

[0012] Determining an adjustment power value according to the external required power and the current operating power;

[0013] The working state of each electrolytic cell is determined according to the regulated power value, the external required power value, and the maximum power and the minimum power of each electrolytic cell.

[0014] Compared with the prior art, this application has the following beneficial effects:

[0015] The present application provides an electrolytic cell array system and an electrolytic water control method, wherein the electrolytic cell array system includes a plurality of gas-liquid separation devices and a plurality of electrolytic cell groups arranged in parallel, wherein the electrolytic cell groups are connected to a converter, wherein each electrolytic cell group includes a plurality of electrolytic cells arranged in series, wherein the number of gas-liquid separation devices is the same as the number of electrolytic cells in the electrolytic cell group, wherein electrolytic cells in the same order in the plurality of electrolytic cell groups are all connected to the same gas-liquid separation device. Since each gas-liquid separation device can be connected to a plurality of electrolytic cells in the same order, the effect of multiple electrolytic cells sharing the same gas-liquid separation device is achieved, thereby saving costs.

[0016] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, preferred embodiments are specifically cited below and described in detail with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 The present invention is a connection diagram of an electrolytic cell system provided in the prior art.

[0019] Figure 2 A schematic diagram of the modules of the electrolytic cell array system provided in an embodiment of the present application.

[0020] Figure 3 A connection diagram of the electrolytic cell array system provided in an embodiment of the present application.

[0021] Figure 4A schematic diagram of the connection of the liquid circuit between the electrolytic cell and the gas-liquid separator provided in an embodiment of the present application.

[0022] Figure 5 Another connection schematic diagram of the electrolytic cell system provided in the prior art.

[0023] Figure 6 A schematic diagram of the structure of a gas-liquid separation device provided in an embodiment of the present application.

[0024] Figure 7 A schematic diagram of the connection of the water electrolysis system provided in the embodiment of the present application.

[0025] Figure 8 A schematic flow chart of a water electrolysis system control method provided in an embodiment of the present application.

[0026] Fig. 9 for Figure 8 A schematic flow chart of a sub-step of S106.

[0027] Fig.10 for Figure 8 Schematic diagram of another sub-step of S106.

[0028] Fig.11 Another flow chart of the water electrolysis system control method provided in the embodiment of the present application.

[0029] In the figure: 100 - electrolytic cell array system; 110 - electrolytic cell; 120 - gas-liquid separation device; 121 - housing; 122 - insulation layer. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0031] In conjunction with the accompanying drawings, some embodiments of the present application are described in detail below. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0032] At present, the typical connection method of large-capacity water electrolysis hydrogen production system is to connect multiple electrolyzers in parallel, each rectifier is connected to an electrolyzer and a gas-liquid separation device, and multiple rectifiers are connected in parallel to the AC power grid. Figure 1As shown. In this system integration solution where a single electrolyzer is connected in parallel, each electrolyzer is connected to a rectifier, a hydrogen / liquid separator, and an oxygen / liquid separator, resulting in high costs for transformers, converters, and gas-liquid separators, and high investment costs for large-capacity electric hydrogen production systems. In this solution, the rectifier is a low-voltage, high-current device with a high cost; while the gas-liquid separator is a customized small-capacity device with a high cost.

[0033] Therefore, the water electrolysis hydrogen production system provided in the prior art includes at least the following problems:

[0034] 1. The parallel integration solution of a single electrolyzer results in a large number of converters required for the system, and low-voltage, high-current converter equipment is required, resulting in a large investment in the transformer and rectifier part of the large-capacity water electrolysis hydrogen production system, and large energy losses in the transformer and rectifier links. For example, as can be seen from the figure, each electrolyzer needs to be connected to a converter, resulting in the number of electrolyzers in the system must be consistent with the number of converters, and the cost of the converter equipment is high.

[0035] 2. In the single electrolyzer parallel integration solution, each electrolyzer can be independently controlled, which improves the control flexibility of the large-capacity water electrolysis hydrogen production system. Since the operation control of different electrolyzers is independent, their gas-liquid separation devices are difficult to share, resulting in each electrolyzer being equipped with a gas-liquid separation device. Therefore, this solution requires a large number of gas-liquid separation devices, and the cost of small customized gas-liquid separation devices is high.

[0036] In summary, the prior art provides a high cost problem in the water electrolysis hydrogen production system. In order to solve the above problem, the present application provides an electrolyzer array system, which arranges the electrolyzers in an array and uses a shared converter and gas-liquid separator to reduce costs.

[0037] The following is an exemplary description of the electrolytic cell array system provided in this application:

[0038] As an implementation, see Figure 2 The electrolytic cell 110 array 100 includes a plurality of gas-liquid separation devices 120 and a plurality of electrolytic cell groups arranged in parallel, each electrolytic cell group includes a plurality of electrolytic cells 110 arranged in series, the number of the gas-liquid separation devices 120 is the same as the number of the electrolytic cells 110 in the electrolytic cell group, wherein the electrolytic cells 110 in the same order in the plurality of electrolytic cell groups are all connected to the same gas-liquid separation device 120.

[0039] By setting up the electrolytic cell array system 100, multiple electrolytic cells 110 can share the same gas-liquid separation device 120, and each electrolytic cell group can be powered by a converter, thereby achieving the purpose of cost saving.

[0040] It can be understood that the electrolytic cell array system 100 may include n electrolytic cell groups connected in parallel and m electrolytic cells 110 in the electrolytic cell group connected in series, wherein m and n are integers greater than 1. A single electrolytic cell 110 may be an electrolytic cell 110 monomer with the largest scale in the market. The electrolytic cells 110 in the electrolytic cell group may be connected in series through the electrolytic chambers in the electrolytic cells 110, and the alkali solution flow channel inside the electrolytic cells 110 may be designed in sections, and the effect is similar to that of the single electrolytic cells 110 connected in series.

[0041] Generally, the number of electrolytic cell groups in the electrolytic cell array system 100 can be greater than or equal to 2, but the number of electrolytic cell groups in parallel is limited by the gas-liquid separation capacity of the separation device. Therefore, based on the balance between economy and performance, as an implementation method, the number of electrolytic cell groups can be 3 to 10, and preferably, the number of electrolytic cell groups is 4, 5, or 6. In addition, the number of electrolytic cells 110 connected in series in each electrolytic cell group is greater than 2, and the number of electrolytic cells 110 connected in series in a group is jointly limited by the DC voltage of the converter and the insulation capacity of the gas-liquid separation device 120. Based on the balance between economy and performance, the number of electrolytic cells 110 in each electrolytic cell group can be 3 to 10, for example, 4.

[0042] As an implementation method, in order to ensure that the voltage level of the electrolytic cell 110 is the same as that of the gas-liquid separation device 120, the electrolysis voltages of the electrolytic cells 110 with the same order in the multiple electrolytic cell groups are the same, thereby effectively ensuring that the gas-liquid outlet of the electrolytic cell 110, the alkali solution inlet, and the gas-liquid separation device 120 are the same, thereby avoiding the generation of bypass current due to the potential difference in the alkali solution circuit in the gas-liquid separation device 120; at the same time, the gas-liquid separation device 120 has insulation capability to avoid the generation of current between the electrolyte and the grounding point, which affects the safety of the equipment.

[0043] See also Figure 3 , this application takes a 4*4 electrolytic cell array system 100 as an example to specifically explain its working principle:

[0044] like Figure 3 As shown, there are four parallel electrolytic cell groups in the 4*4 electrolytic cell array system 100, and each electrolytic cell group is four electrolytic cells 110 connected in series. In the electrolytic cell array system 100, four electrolytic cells 110 with the same voltage level share one set of gas-liquid separation devices 120, and there are four sets of gas-liquid separation devices 120, so that only four gas-liquid separation devices 120 are needed for 16 electrolytic cells 110, saving costs.

[0045] It should be noted that the above sequence can be implemented according to the numbering of the electrolytic cells. For example, in the first electrolytic cell group, including electrolytic cell 11, electrolytic cell 12, electrolytic cell 13 and electrolytic cell 14, 4 electrolytic cells are connected in series, and the 4 electrolytic cells share a rectifier to save costs. The electrolysis voltages of electrolytic cell 11, electrolytic cell 12, electrolytic cell 13 and electrolytic cell 14 decrease from top to bottom. In addition, the first electrolytic cell in the second electrolytic cell group is numbered 21, the first electrolytic cell in the third electrolytic cell group is numbered 31, and the first electrolytic cell in the fourth electrolytic cell group is numbered 41, then the electrolysis voltages of electrolytic cell 11, electrolytic cell 21, electrolytic cell 31 and electrolytic cell 41 are the same, ensuring that the voltages of the electrolytic cells connected to the same gas-liquid separation device 120 are consistent.

[0046] It should also be noted that in the present application, the number of electrolytic cells 110 connected to each gas-liquid separation device 120 may also be different. For example, the first three gas-liquid separation devices 120 are connected to four electrolytic cells 110 respectively, and the last gas-liquid separation device 120 is connected to three electrolytic cells 110. Another electrolytic cell 110 at the same voltage level can be connected to a gas-liquid separator alone, which is not limited here.

[0047] Optionally, the electrolytic cell array system 100 further includes valves and conduits, each electrolytic cell 110 is connected to the conduit via a valve, and each electrolytic cell 110 is connected to the gas-liquid separation device 120 via a conduit; wherein the valve is used to control the amount of liquid flowing into / out of the electrolytic cell 110. Figure 4 The schematic diagram of the structure of the parallel electrolyzers 110 in the electrolyzer array system 100 in the water electrolysis system sharing a set of gas-liquid separation devices 120 is shown. Among them, the hydrogen / alkali liquid mixture in the parallel electrolyzers 110 in the electrolyzer array system 100 enters the hydrogen / alkali liquid separator through a pipeline for separation, the alkali liquid is in the lower part of the separator, and the hydrogen enters the subsequent hydrogen purification equipment through the upper gas outlet; the oxygen / alkali liquid mixture enters the oxygen / alkali liquid separator through a pipeline for separation, the alkali liquid is in the lower part of the separator, and the oxygen enters the subsequent oxygen purification equipment or is emptied through the upper gas outlet. The alkali liquid in the hydrogen alkali liquid separator and the oxygen alkali liquid separator converges and re-enters the parallel electrolyzer 110. An electrically controlled linkage interlocking valve is installed at the alkali liquid inlet of the electrolyzer 110, and the liquid inlet valve is started according to demand.

[0048] In the alkaline water electrolysis hydrogen production system, the system controller controls the alkali solution inlet valves of the parallel electrolyzers 110 as needed, and starts the valves in sequence at fixed time intervals t. By starting the valves in sequence at fixed time intervals, the problem of bypass current caused by deviation of the alkali solution inlet potential after the performance of the electrolyzer 110 is discrete can be solved, and it can be ensured that the shared gas-liquid separator does not affect the electrolysis hydrogen production efficiency of the electric hydrogen production system. By using a gas-liquid separator with an insulating function, the parallel electrolyzers 110 can share a gas-liquid separator, and a large gas-liquid separation device 120 can be used to replace multiple small gas-liquid separators, thereby reducing the investment cost of the gas-liquid separator.

[0049] The gas-liquid separation device 120 includes a first separation device and a second separation device, the conduit includes a first conduit, a second conduit and a third conduit, each electrolytic cell 110 includes a first outlet, a second outlet and a liquid return port, the first outlet is connected to the first separation device through the first conduit, the second outlet is connected to the second separation device through the second conduit, and the liquid return port is connected to the first separation device and the second separation device respectively through the third conduit.

[0050] For decomposing water, the first separation device and the second separation device are respectively an oxygen / liquid separator and a hydrogen / liquid separator, and the bottoms of the two separators are connected to ensure that the alkali liquid pressure on the hydrogen side and the oxygen side is the same. Optionally, the gas-liquid separation device 120 also includes an adapter, which is connected to the liquid outlets of the first separation device and the second separation device respectively, and the electrolyzer 110 is connected to the adapter through a third conduit.

[0051] Continue with Figure 3For example, during the operation of the electrolyzer array system 100, it is necessary to control the two liquid levels in the oxygen / liquid separator and the hydrogen / liquid separator to be the same to avoid the introduction of gas impurities due to the liquid level difference at the bottom connection position of the two. The oxygen-alkali liquid mixture in the electrolyzers 110 of the same voltage level in the first and second groups comes out from the electrolyzer 110 outlet A1 position and enters the oxygen-liquid separator through A2; the oxygen-alkali liquid mixture in the electrolyzers 110 of the same voltage level in the third and fourth groups comes out from the electrolyzer 110 outlet A1 position and enters the oxygen-liquid separator through A3. In the oxygen-liquid separator, the oxygen-alkali liquid mixture of the four electrolyzers 110 is separated, and the oxygen leaves the upper part of the separator and enters the downstream pipeline. The alkali liquid from the lower part of the separator is mixed with the alkali liquid from the lower part of the hydrogen separation at C1, and the alkali liquid then re-enters the electrolyzer 110 through C2. The hydrogen-alkali liquid mixture in the electrolyzers 110 of the same voltage level in the first and second groups comes out from the electrolyzer 110 outlet B1 position, and enters the hydrogen-liquid separator through B2; the hydrogen-alkali liquid mixture in the electrolyzers 110 of the same voltage level in the third and fourth groups comes out from the electrolyzer 110 outlet B1 position, and enters the hydrogen-liquid separator through B3, in which the oxygen-alkali liquid mixture of the four electrolyzers 110 is separated, the hydrogen leaves from the upper part of the separator, enters the downstream pipeline, the alkali liquid from the lower part of the separator is mixed with the alkali liquid from the lower part of the oxygen separation at C1, and the alkali liquid then re-enters the electrolyzer 110 through C2. In addition, the amount of alkali liquid in the input / output electrolyzer 110 can be regulated by the valve, and the amount of alkali liquid in the four electrolyzers 110 is kept relatively balanced, and the valve at the alkali liquid inlet of the electrolyzer 110 can receive the command of the controller to start and stop the operation, and the opening of the valve can be controlled.

[0052] In addition, the existing electrolytic water hydrogen production system faces the problem of potential difference and equipment insulation in the liquid circuit of the gas-liquid separation device 120 when the electrolytic cells 110 are connected in series. In the prior art integrated solution where multiple electrolytic cells 110 are directly connected in series and each electrolytic cell 110 is connected to a set of gas-liquid separation devices 120, there is a potential difference in the alkaline liquid circuit of the gas-liquid separation device 120, which leads to the appearance of bypass current, making it difficult to meet the design safety requirements of the electrolytic water hydrogen production system and will lead to a reduction in the efficiency of the system's electrolytic hydrogen production.

[0053] For the purpose of illustration, this application is Figure 5For example, A1, A2, and C points are all equipotential positions in the middle of the electrolytic cell 110, wherein A1 is the outlet of the oxygen and alkali mixture from the electrolytic cell 110; A2 is the outlet of the hydrogen and alkali mixture from the electrolytic cell 110; and C is the inlet of the alkali after gas-liquid separation back to the electrolytic cell 110. Due to the series connection, the potential of A1, A2, and C points is 750V, while the gas-liquid separation device 120 is grounded at 0V. Since the alkali is a good conductor, currents will be generated at A1, A2, C points, the gas-liquid separation device 120, and the grounding point.

[0054] In order to solve the problem that the voltage of some electrolytic cells 110 is too high after the electrolytic cells 110 are connected in series, resulting in insulation problems in the gas-liquid separation equipment. As an implementation method, please refer to Figure 6 The gas-liquid separation device 120 includes an insulating layer 122 connected to a shell 121, and an inlet, a gas outlet and a liquid outlet are provided at the same position of the insulating layer 122 and the shell 121, the inlet and the liquid outlet are both connected to the electrolytic cell 110, and the gas outlet is used to connect to a gas storage device.

[0055] Optionally, the insulating layer 122 is disposed on the inner surface of the shell 121 .

[0056] Among them, the insulating layer 122 can be made of insulating plastic, and the insulating plastic on the inner surface of the gas-liquid separation device 120 is used to insulate the alkali liquid from the gas-liquid separation device itself, so as to avoid leakage current between the alkali liquid and the grounding device in the high-voltage electrolyzer 110, endangering the safety of the equipment and reducing the efficiency of the electric hydrogen production system. The gas-liquid mixture inlet, gas outlet, and liquid outlet connected to the gas-liquid separation device 120 are all connected to insulating plastic pipes to avoid the conduction of the pipeline and leakage current. The main function of this type of gas-liquid separation device 120 is to avoid leakage current between the alkali liquid circuit and the gas-liquid separation device in the high-voltage electrolyzer 110, resulting in bypass current in the electrolyzer 110. The bypass current not only reduces the electric hydrogen production efficiency of the electrolyzer 110, but also affects the safety of pumps, valves, sensors and other components connected to the gas-liquid separation device 120 in the electric hydrogen production system. The heat exchanger in the gas-liquid separation device 120 is connected to the external thermal management system external machine, which is used to control the temperature of the alkali liquid in the gas-liquid separation device 120, and is an important measure for controlling the temperature of the alkali liquid in the electrolyzer 110.

[0057] As an implementation method, optionally, the shell 121 and the pipeline containing the alkaline solution in the gas-liquid separator are connected or fixed to the equipment frame using insulating materials.

[0058] The present invention proposes that the insulating material of the inner surface of the gas-liquid separation device 120 includes electrical insulating plastics such as polyvinyl chloride, polypropylene, polyethylene, polystyrene, and polyamide.

[0059] The gas-liquid separation device 120 mentioned in the present invention includes a wire mesh separator, a centrifugal separator, a microporous filtration separator, a packing separator, a baffle separator, a gravity sedimentation separator, etc. The present patent preferably uses a centrifugal separator and a baffle separator, and more preferably uses a centrifugal separator.

[0060] The centrifugal gas-liquid separation device 120 can achieve rapid separation of gas and liquid, which is beneficial to improving the separation speed and efficiency of hydrogen and alkaline liquid, oxygen and alkaline liquid in the electric hydrogen production system, so as to avoid the introduction of gas impurities in the process of alkaline liquid in the gas-liquid separation device 120 returning to the electrolytic cell 110.

[0061] In addition, the electrolytic cell array system 100 also includes a controller, a transformer, a rectifier, a gas purification device and a gas storage device. The transformer is connected to the rectifier, each electrolytic cell group is connected to a rectifier, the gas-liquid separation device 120 is connected to the gas purification device, and the gas purification device is also connected to the gas storage device. The controller is respectively connected to the transformer, the rectifier, the gas purification device, the gas storage device, the electrolytic cell 110 and the gas-liquid separation device 120.

[0062] Among them, the controller is connected to the external control command communication terminal, receives external control commands or internal production planning instructions, determines the overall operating conditions of the system, and simultaneously connects the transformer, the conditioner, the electrolyzer 110, the gas-liquid separation device 120, the gas purification device, the gas storage device, etc. to control the operating status of the system to achieve the control objectives of the electric hydrogen production system.

[0063] In addition, the controller is also used to control the power, gas-liquid separation, water replenishment, and gas-liquid purification of the electric hydrogen production system according to external control instructions or internal production plan arrangements, so that the electric hydrogen production system can be accurately and quickly adjusted according to power regulation requirements or downstream gas needs.

[0064] Based on the above implementation, please refer to Figure 7 The present application also provides a water electrolysis system, which includes the above-mentioned multiple electrolytic cell array systems 100, and the multiple electrolytic cell array systems 100 are arranged in parallel.

[0065] On the basis of the above implementation, the present application also provides a method for controlling a water electrolysis system of an electrolytic cell array system 100 to achieve control of the water electrolysis system.

[0066] As an implementation, see Figure 8 The electrolytic cell array system 100 water electrolysis system control method includes:

[0067] S102, when a power adjustment instruction is received, determining the external required power.

[0068] S104, determining an adjustment power value according to the external required power and the current operating power.

[0069] S106 , determining the working state of each electrolytic cell 110 according to the adjusted power value, the required power value, and the maximum power and the minimum power of each electrolytic cell 110 .

[0070] It can be understood that each electrolyzer array system 100 is connected to a controller, and the electrolyzer array system 100 is adjusted by the controller. Among them, the control end can receive the working condition parameters of the water electrolysis system in real time during operation, and after receiving the power adjustment instruction, adjust the electrolyzer array system 100 in real time according to the actual working condition, so that the water electrolysis system can work stably. Among them, a plurality of sensors are provided in the water electrolysis system, and operating data is collected by the sensors. For example, by providing a temperature sensor, the temperature in the water electrolysis system can be measured during operation.

[0071] It should be noted that the power adjustment range of a single electrolytic cell 110 is [P emin , P emax ], and its adjustment range is subject to the comprehensive limitations of the temperature control capability, impurity control capability and equipment performance of a single electrolytic cell 110. emin Approximately rated power P er 30%, and its power limit P emax Approximately rated power P er 120% of the m*n array electrolyzer array system 100. The electrolyzer groups in the m*n array electrolyzer array system 100 are connected in parallel, and the electrolyzers 110 in the electrolyzer group are connected in series. The electrolyzer groups are connected in parallel and share the gas-liquid separation device 120, which can improve the control flexibility between the electrolyzer groups. Therefore, the power adjustment range of the m*n array electrolyzer array system 100 is [P emin ,m*n*P emax ].

[0072] In the application of the electrolysis water system, the controller of the electrolysis water system will allocate to H electrolyzer array systems 100 arranged in m*n according to the external power dispatch or hydrogen consumption plan. The allocation principle is to reduce the number and quantity of overall start-up and shutdown of the electrolyzer array system 100, so as to improve the flexibility and reliability of power control of the large-capacity electric hydrogen production system, avoid the adverse effects of frequent start-up and shutdown on the electrolyzer 110 and the increase in energy consumption during the start-up and shutdown process. After the m*n array electrolyzer array system 100 is shut down as a whole, the alkali solution temperature in the electrolyzer array system 100 begins to drop. When it is lower than T hpminThe temperature of the alkali solution in the electrolytic cell array system 100 is lower than the normal operating temperature. When the electrolytic cell array system 100 needs to be started, the alkali solution in the electrolytic cell array system 100 needs to undergo a heating process. Therefore, under this condition, its restart speed is slow, and the duration is 0.5h to 3h. During the cold start process, the power of the electrolytic cell 110 in the startup state is slow, and the operating power of other electrolytic cell array systems 100 needs to be dynamically adjusted to ensure that the total power of the system is equal to the power value issued by the system controller. When the temperature of the alkali solution in the electrolytic cell array system 100 is higher than T hpmin , the equipment can be started quickly and the power can be adjusted accurately when it is in hot standby state.

[0073] The system controller decomposes the total operating power into the converters in the H m*n array-type electrolyzer array system 100, and distributes the operating power of the electrolyzer array system 100 to the converters as evenly as possible. The converter adjusts the current value according to the DC voltage of the electrolyzer 110 according to the power issued by the controller. The power of the electrolyzer array system 100 is evenly distributed to the converters in the array to ensure that the working power of the electrolyzers 110 in the array is in a consistent state, and to avoid problems caused by inconsistent performance attenuation of the electrolyzers 110 due to long-term different operating powers. When the electrolyzer array system 100 needs to continue to reduce power, the power value is evenly distributed to other electrolyzer groups after stopping an electrolyzer group in the array as a whole, so as to ensure that the overall operating power of the electrolyzer array system 100 is equal to the power value issued by the system. In this adjustment process, it is necessary to control the coolant in the gas-liquid separation device 120 to reduce the heat dissipation of the cooling system, ensure that the electrolyzer 110 of the electrolyzer group that is shut down is in a hot standby state, and the electrolyzer 110 can quickly start the machine unit as needed.

[0074] In addition, according to the external power dispatch or hydrogen consumption plan, the electric hydrogen production system controller confirms the power adjustment cycle and then adopts different power control strategies. If the external adjustment demand belongs to millisecond-level and minute-level power adjustment, it is achieved by all electrolyzer groups in the electric hydrogen production system jointly increasing or decreasing the power to follow the load balancing principle. If the external adjustment demand belongs to hourly power adjustment, if the time scale adjustment process is in the normal power adjustment of the electrolyzer array system 100, the adjustment strategy of synchronously increasing or decreasing the power of different electrolyzer groups is implemented; when the power adjustment range exceeds the normal power supply adjustment range of the electrolyzer group, the power reduction is achieved by shutting down some electrolyzer groups in the electric hydrogen production system, and the power increase control is achieved by running some electrolyzer groups at over-rated power. The number and power values ​​of the actually operating electrolyzer groups in different electrolyzer array systems 100 are kept as the same as possible to follow the load balancing principle. Among them, the normal power adjustment range of the electrolyzer array system 100 is [P emin ,m*n*P emax]. If the external regulation demand belongs to the power regulation of several days and weeks, the power reduction operation is realized by stopping part of the electrolytic cell array system 100, and the power value of different electrolytic cell groups is ensured to be as consistent as possible during the power increase process. If it exceeds the normal power regulation range of the electrolytic cell 110, it is realized by controlling the over-power operation of some electrolytic cell groups in the electrolytic cell array system 100, wherein the number of electrolytic cell groups that need to be operated at overpower in different electrolytic cell array systems 100 is kept as the same as possible, and the over-powered electrolytic cell groups in the electrolytic cell array system 100 are rotated within the specified time to avoid the long-term overload operation of a single electrolytic cell group, which leads to the accelerated performance degradation of the electrolytic cells 110 in the group, wherein the duration of the electrolytic cell 110 that needs to be overloaded is 0.5h. The time interval can be set as needed, taking into account the performance degradation characteristics of the electrolytic cell 110.

[0075] On this basis, the power adjustment instructions include power increase instructions and power reduction instructions. When a power reduction instruction is received, please refer to Fig. 9 , when the step of S106 includes:

[0076] When the external power requirement meets H*m*n*P emin ≤P≤H*m*n*P emax When , the adjusted power value is evenly distributed to each electrolytic cell group to balance the load of each electrolytic cell group;

[0077] When the external power requirement meets η*H*m*n*P emin ≤P≤H*m*n*P emin When the power is on, control some or all of the electrolytic cell groups in one or more electrolytic cell array systems to shut down;

[0078] When the external power requirement meets η*m*n*P emin ≤P≤η*H*m*n*P emin When the power is off, some electrolyzer array systems are controlled to shut down, and the external power demand is distributed to the remaining electrolyzer array systems;

[0079] When the external power requirement meets m*P emin ≤P≤η*m*n*P emin When one of the electrolytic cell array systems is in operation, the number of electrolytic cell groups in the electrolytic cell array system in operation is adjusted;

[0080] When the external power requirement meets P <m*P emin When the water electrolysis system is determined to be unable to respond to the instruction;

[0081] Where n represents the number of electrolytic cell groups, m represents the number of electrolytic cells in each electrolytic cell group, H represents the number of electrolytic cell array systems in operation, η represents a coefficient greater than 0 and less than 1, and Pemin represents the minimum power of each electrolyzer, P emax Indicates the maximum power of each electrolyzer.

[0082] It should be made clear that for the controller, its actual control method is a layer-by-layer judgment method, that is, first determine whether the external demand power meets the

[0083] H*m*n*P emin ≤P≤H*m*n*P emax If it is satisfied, the adjusted power value is evenly distributed to each electrolytic cell group and the adjustment process ends. If it is not satisfied, it is necessary to continue to determine whether the external required power is met, η*H*m*n*P emin ≤P≤H*m*n*P emin And so on. The control process algorithm in the power reduction mode of the electrolyzer array system is as follows: Fig. 9 shown.

[0084] Among them, when the power value P sent by the controller in the electrolysis water system is in [H*m*n*P emin ,H*m*n*P emax ] range, the power value Δp needs to be adjusted and evenly distributed to each electrolyzer group in the electrolyzer array system to ensure load balance between the electrolyzer array systems. At this stage, the power range of the electric hydrogen production system can be adjusted to [H*m*n*P emin ,H*m*n*P emin In other words, when the reduced power meets the above range, all the electrolytic cell groups currently in operation will have their power reduced by a portion of the power at the same time, and after the power reduction, the power of each electrolytic cell group will be equal.

[0085] When the operating power value P (i.e. external demand power) of the hydrogen production system is lower than H*m*n*P emin and greater than or equal to η*H*m*n*P emin , it is necessary to start shutting down the electrolyzer groups in the electrolyzer array system to meet the need to adjust the power value Δp, and the power deviation value generated during the shutdown of the electrolyzer group will be synchronously adjusted by other electrolyzer groups in the electrolyzer array system to ensure load balance. When some electrolyzer groups are shut down in the H m*n matrix electrolyzer array system of the electric hydrogen production system, according to the load balancing principle, try to ensure the power balance between the H electrolyzer array systems. At this stage, the electrolysis water system can adjust the power range to [η*H*m*n*P emin ,H*m*n*P emin ] Wherein η is the ratio of the number of operating electrolytic cell groups required to ensure the thermal insulation of the shared gas-liquid separation device in the array in the electrolytic cell array system / the total number of electrolytic cell groups in the array, and its value can be obtained through experimental tests.

[0086] When the operating power value P of the electric hydrogen production system is lower than η*H*m*n*P emin and greater than or equal to η*m*n*P emin , it is necessary to start shutting down part of the electrolyzer array system as a whole to meet the required power adjustment value Δp, and to synchronize the power deviation of the electrolyzer array system during shutdown by the electrolyzer array system in other operating states to ensure load balancing. When the operating power of the electric hydrogen production system is lower than η*(Ho-1)*m*n*P emin When the number of electrolyzer array systems is 1, Ho is the number of electrolyzer array systems in operation. By analogy, the minimum operating power of the hydrogen production system can be reduced to η*m*n*P emin .

[0087] When the operating power value P of the electric hydrogen production system is lower than η*m*n*P emin and greater than or equal to m*P emin , it is necessary to start adjusting the electrolytic cell group in the electrolytic cell array system to meet the required adjustment power value Δp, and the minimum operating power of the electrolytic water system can be reduced to m*P emin When the operating power P of the hydrogen production system needs to be lower than m*P emin , the electric hydrogen production system cannot respond to the regulation requirements, and the feedback cannot respond to instructions, for example, alarm processing is performed at this moment.

[0088] By providing the control method, load balancing can be achieved during the power reduction adjustment process, and the system stability is improved. At the same time, the shutdown of the electrolytic cell group is avoided as much as possible, saving energy consumption.

[0089] As another implementation, when receiving a power increase command, refer to Fig.10 , the step of S106 includes:

[0090] When the external power requirement meets m*P emin ≤P≤m*n*P er When the current electrolytic cell array system is in operation, other electrolytic cell groups in the system are controlled to work;

[0091] When the external power requirement meets m*n*P er ≤P≤2*m*n*P er When the next electrolytic cell array system is controlled to work;

[0092] When the external power requirement meets H0*m*n*P er ≤P≤(H0+1)*m*n*P er When the next electrolytic cell array system is controlled, the whole system works;

[0093] When the external power requirement meets H*m*n*P er≤P≤H*m*n*P emax When it is satisfied, control all electrolytic cell array systems to work synchronously;

[0094] When the external demand power satisfies H*m*n*P emax <P, it is determined that the electrolyzed water system cannot respond to the instruction;

[0095] Among them, n represents the number of electrolytic cell groups, m represents the number of electrolytic cells in each electrolytic cell group, H represents the number of operating electrolytic cell array systems, H0 represents the number of currently working electrolytic cell array systems, P emin represents the minimum power of each electrolytic cell, P emax represents the maximum power of each electrolytic cell, P er represents the rated power of each electrolytic cell.

[0096] During the power increase process of the electrolyzed water system in the cold start mode, the lye in the electrolytic cell and the gas-liquid separation device needs to be heated up, and its power adjustment speed is relatively slow; during the power increase process in the hot start mode, its power adjustment speed is relatively fast. The control process algorithm in the power increase mode of the electrolytic cell array system is as Fig.10 shown.

[0097] When the operating power value P of the electrolyzed water system is greater than or equal to m*P emin and less than m*n*P er , it is necessary to start other electrolytic cell groups in the electrolytic cell array system to meet the required adjusted power value Δp. During the cold start process of this electrolytic cell group in the electrolytic cell array system, the other operating electrolytic cells determine their operating powers according to the actual operating power of the cold start electrolytic cell group to ensure that the instruction value issued by the control system is reached. When the power of the electrolytic cell array system is greater than η*m*n*P emin , the other electrolytic cell groups in the array are in the hot start state and can quickly track the control instruction issued by the controller to reach the set operating power.

[0098] When the operating power value P of the electrolyzed water system is greater than or equal to m*n*P er and less than 2*m*n*P er, it is necessary to start the next electrolytic cell array system to meet the need to adjust the power value Δp. During the overall cold start process of the electrolytic cell array system, all electrolytic cell groups in the electrolytic cell array system are started synchronously to increase the alkali solution temperature in the electrolytic cell and the gas-liquid separation device to the normal operating temperature range as soon as possible. The normal operating range of the alkali solution in the electrolytic cell is 50℃~95℃. According to the actual operating power of the electrolytic cell array system in the cold start state, adjust the operating power of other operating electrolytic cell groups, and evenly distribute power to the electrolytic cell groups in the operating state to ensure balanced load, and at the same time achieve the power of the electrolytic water system equal to the power value issued by the system controller. When the alkali solution temperature in the electrolytic cell array system in the cold start state reaches 50℃, start the temperature control system in the electrolytic cell array system to ensure that the coolant circulation system can operate effectively. When the alkali solution temperature in the electrolytic cell array system reaches 80℃, control the temperature control system to achieve heat generation and heat dissipation balance in the electrolytic cell array system.

[0099] When the number of operating electrolytic cells is Ho and the operating power of the electrolytic water system is greater than or equal to Ho*m*n*P er and less than (Ho+1)*m*n*P er , start the next electrolyzer array system to meet the need to adjust the power value Δp. During the overall cold start of the electrolyzer array system, the power deviation is synchronously adjusted by other electrolyzer groups in operation. Before all electrolyzer array systems are in hot operation, the load increase process of the water electrolysis system uses this power control strategy.

[0100] When all H electrolyzer array systems in the electrolysis water system are in hot operation, the system further increases the power control mode to increase the power of each electrolyzer array system synchronously, and each electrolyzer group in the electrolyzer array system increases the power synchronously to ensure balanced load and achieve system operation power equal to the power value issued by the system controller. At this stage, the electrolysis water system can adjust the power range to [H*m*n*P emin ,H*m*n*P er ].

[0101] When the operating power of the water electrolysis system is greater than or equal to H*m*n*P er and less than H*m*n*P emax , the system can enter the super-power operation state to meet the need to adjust the power value Δp. During the power increase process, all electrolyzer groups are controlled synchronously. In this state, the heat generation of the electrolyzer increases and the hydrogen production efficiency decreases. It is necessary to increase the cooling capacity of the temperature control system to ensure the balance of heat generation and heat dissipation in the electrolytic water system, thereby ensuring that the alkali solution temperature in the system is in the range of 80℃ to 95℃. The electrolyzer has the highest efficiency within this temperature range, reducing the additional energy loss caused by the alkali solution temperature and avoiding equipment performance damage caused by overheating of the equipment. The maximum operating power of the electrolytic water system can reach H*m*n*Pemax When the operating power of the electrolysis water system needs to be greater than H*m*n*P emax , the water electrolysis system cannot respond to the adjustment requirements, and the feedback cannot respond to the instructions.

[0102] As an optional implementation, each gas-liquid separation device is also connected to a water replenishment device, see Fig.11 , the control method further includes:

[0103] S108, obtaining the operating power and hydrogen production efficiency of each electrolyzer array system;

[0104] S110, determining the amount of water replenishment according to the operating power and the hydrogen production efficiency, wherein the amount of water replenishment satisfies the formula:

[0105]

[0106] Where W i-j represents the water replenishment amount of the jth gas-liquid separation device in the i-th electrolyzer array system, η eh represents the efficiency of hydrogen production from electricity of the i-th electrolyzer array system.

[0107] Among them, S108-S110 and S102-S106 are in a parallel relationship, so the step numbers are only for distinguishing different steps, and do not mean that the two must be executed in this order.

[0108] Among them, the current control strategy for alkali liquid replenishment in the electrolyzer and gas-liquid separation device in the industry is generally that when the liquid level in the gas-liquid separation device is lower than the lower limit, the replenishment valve is opened to replenish water, and when the liquid level reaches the upper limit, the replenishment valve is closed to stop replenishing water. This control strategy is relatively simple, but it causes the replenishment control process to be discontinuous, and will affect the alkali liquid temperature in the electrolyzer and gas-liquid separation device during the replenishment state, causing the alkali liquid temperature to change rapidly, and affecting the temperature control strategy of the electric hydrogen production system.

[0109] In the present application, according to the structural characteristics of each electrolyzer array system operating independently, a control strategy for continuous water replenishment is implemented based on the water consumption for hydrogen production in the m*n matrix electrolyzer array system. The alkali solution water replenishment control strategy is to calculate the water consumption of the i-th m*n matrix electrolyzer array system based on its operating power and then determine the replenishment quantity of the electrolyzer array system, and then control the water replenishment valves of the m gas-liquid separators in the array to replenish water, and the flow control of each water replenishment valve in the array is the same value and equal to the total required water replenishment flow. The alkali solution water replenishment strategy can achieve a relatively gentle response to the alkali solution temperature and avoid the error of the temperature control strategy caused by the rapid change of the alkali solution.

[0110] Moreover, the current method for controlling the temperature of the electrolyzer in the industry is to use the outlet temperature of the electrolyzer as an input parameter to control the valve of the coolant in the separator of the enterprise, so as to control the flow of the coolant and then control the temperature of the alkali solution in the gas-liquid separator. Due to the large heating area in the electrolyzer and the large volume of alkali solution in the gas-liquid separator and the pipeline, the relatively low heat exchange efficiency in the heat exchanger leads to a large hysteresis in the temperature control of the alkali solution at the outlet of the electrolyzer, resulting in large fluctuations in the alkali solution temperature and easy to exceed the upper limit of the operating temperature. When the alkali solution temperature exceeds the upper limit of the operating temperature, it will affect the performance of the diaphragm in the electrolyzer, resulting in reduced performance or damage to the electrolyzer. When the alkali solution temperature is too low, the resistance of the alkali solution increases, which increases the heat loss of the alkali solution in the electrolyzer, resulting in a decrease in the hydrogen production efficiency of the electrolyzer. Therefore, improving the stability of the alkali solution temperature in the electric hydrogen production system is of great significance to improving the overall efficiency of the system.

[0111] In view of this, in order to avoid the above problems, a heat exchanger is provided in the gas-liquid separation device provided in the present application, and the control method further includes:

[0112] S112, according to formula T ijn-out =T ijn-in +k t1 *P i-mn +k t2 *P cij Adjust the working state of the heat exchanger, where T ijn-out is the average value of the alkali solution temperature at the outlet of the n electrolytic cells connected to the j-th gas-liquid separation device in the i-th electrolytic cell array system; T ijn-in is the average alkali solution temperature at the inlet of the n electrolytic cells connected to the j-th gas-liquid separation device in the i-th electrolytic cell array system; P i-mn is the operating power of the i-th electrolyzer array system, P cij is the heat transferred by the heat exchanger in the jth gas-liquid separation device in the i-th electrolyzer array system, and P cij =W cij *Cc*(t1-t2),W cij represents the flow rate of the coolant in the heat exchanger in the gas-liquid separation device, Cc is the isobaric specific heat capacity of the coolant; t1 and t2 are the outlet and inlet temperatures of the heat exchanger, k t1 With k t2 Represents the parameters of the electrolyzer array system determined during testing.

[0113] Of course, S112 is also in parallel with the above steps.

[0114] Among them, the m*n matrix electrolyzer array system has m gas-liquid separators and n electrolyzers share one gas-liquid separator, and the gas-liquid separators are independently controlled. However, the electrolyzer group is m electrolyzers connected in series, so when the electric hydrogen production system controls the converter power or gas output, the mass of the gas-liquid mixture connected to the m gas-liquid separators is the same. Therefore, the m gas-liquid separators in the m*n matrix electrolyzer array system are also independently controlled, and the control strategy is the same.

[0115] In the m*n matrix electrolyzer array system, a gas-liquid separator is connected to n electrolyzers, and the n electrolyzers are connected to the AC power grid through n converters. In the electrolyzer array system, the n electrolyzers connected by the gas-liquid separator, the oxygen / alkali liquid mixture and the hydrogen / alkali liquid mixture in these electrolyzers enter the oxygen liquid separator and the hydrogen liquid separator through pipelines for gas-liquid separation, and the separated liquids are mixed together through the pipelines at the lower ends of the oxygen liquid separator and the hydrogen liquid separator, and then re-enter the n electrolyzers through the pipelines to continuously circulate the alkali liquid. The alkali liquid temperature control function in the electric hydrogen production system collects the alkali liquid temperature at the inlet of n electrolyzers, the alkali liquid temperature at the outlet of n electrolyzers, and the power value of the converter of n electrolyzers. The converter power value and the inlet temperature of the electrolyzer are used as input values ​​to control the outlet temperature of the electrolyzer to reach the set temperature value, so as to ensure that the outlet temperature of the electrolyzer alkali liquid does not exceed the rated upper temperature limit of the electrolyzer equipment, and at the same time, the inlet temperature of the electrolyzer alkali liquid is kept as stable as possible.

[0116] It should be noted that in the above formula, P i-mn The data is obtained by calculating the average value of the power values ​​obtained by n converters in the electrolyzer array system. The temperature of the outlet and inlet of the heat exchanger in the gas-liquid separator is obtained by sensors at corresponding positions. ijn-out , which can be adjusted in real time. For example, when T ijn-out When it is larger, the flow rate of the coolant in the heat exchanger is changed, thereby reducing the temperature.

[0117] Moreover, the gas-liquid separation device generally includes a first separation device and a second separation device. In the water electrolysis system, the first separation device and the second separation device are a hydrogen / alkaline solution separation device and an oxygen / alkaline solution separation device, respectively.

[0118] At present, the liquid level difference between the hydrogen side and the oxygen side in the separator used for alkali separation in the industry is an important indicator for early warning of the electrolyzer. The reason is that a large liquid level difference on both sides will lead to pressure imbalance on both sides, which will in turn make the amount of alkali in the hydrogen production circuit and the oxygen production circuit inconsistent, and increase the amount of liquid that passes through the diaphragm in the electrolyzer. The alkali liquid passing through the diaphragm will cause the gas impurities in the alkali liquid to be carried to the other side, reducing the overall efficiency of the electrolyzer. Although the indicator of the liquid level difference between the hydrogen side and the oxygen side is critical, the current electric hydrogen production equipment mainly collects this data for early warning to remind the equipment operator to adjust the control parameters of the equipment. There is no technology to automatically control the liquid level difference.

[0119] In view of this, the control method provided by the present application also includes:

[0120] S114, adjust the alkali solution flow rate of the first separation device and the second separation device according to the formula ΔW=Δh*S*ρ*Δt; wherein ΔW represents the alkali solution flow rate that needs to be adjusted between the first separation device and the second separation device; Δh represents the liquid level difference between the first separation device and the second separation device, S is the equivalent cross-sectional area in the corresponding separation device, ρ is the density of the alkali solution, and Δt is the setting time for leveling the liquid level difference between the first separation device and the second separation device.

[0121] The present application automatically adjusts the circulation volume of alkali solution on the hydrogen side and oxygen side by monitoring the liquid level difference on the hydrogen side and oxygen side, so as to automatically adjust the liquid level difference on both sides. In the electric hydrogen production system, the m*n matrix electrolyzer array system has the structural characteristics of independent operation, and the gas-liquid separator liquid in the electrolyzer array system is relatively independent and flexible to adjust. Therefore, the liquid level difference control function of the hydrogen side and oxygen side in the system controller monitors the liquid level height on both sides, and when a deviation occurs, adjusts the flow rate of alkali solution in the hydrogen side or oxygen side circulation.

[0122] The liquid level on the hydrogen side and the liquid level on the oxygen side of the gas-liquid separator both have a normal height range. Under the condition that the liquid levels on both sides are within the operating range, when the liquid level on the hydrogen side of the gas-liquid separator is higher than the liquid level on the oxygen side, the alkali liquid flow rate in the oxygen side circulation is increased according to the above formula to increase the liquid level on the oxygen side; when the liquid level on the oxygen side of the gas-liquid separator is higher than the liquid level on the hydrogen side, the alkali liquid flow rate in the hydrogen side circulation is increased according to the above formula to increase the liquid level on the hydrogen side. When the liquid level on the hydrogen side or the oxygen side deviates from the normal height range of the equipment, the corresponding alkali liquid circulation volume is adjusted to adjust it to the normal liquid level height specified by the equipment as soon as possible.

[0123] It should be noted that the gas outlet flow of the gas-liquid separation device of the electric hydrogen production system in the industry is currently controlled by an outlet valve. Since the alkali liquid in the gas-liquid separation device is connected at the lower end of the hydrogen side and oxygen side separation device, the hydrogen pressure and oxygen pressure in the gas-liquid separation device are related. Usually, the oxygen pressure is adjusted by the oxygen side outlet valve, thereby determining the pressure of the entire electric hydrogen production system, and the hydrogen flow is adjusted by controlling the hydrogen side valve.

[0124] However, the rapid change in gas volume caused by adjusting the oxygen and hydrogen side valves causes drastic fluctuations in the alkali liquid level in the gas-liquid separation device, affecting the liquid level balance control in the gas-liquid separation device. Therefore, it is necessary to improve the continuity of gas flow control and reduce the fluctuation amplitude of the alkali liquid level caused by gas flow regulation. At present, the outlet valves in the gas-liquid separation device in the industry are usually electrically controlled pneumatic valves, which automatically adjust the valve opening by gas pressure. The pneumatic regulating valve usually has an opening range of 30% to 80%, resulting in poor connectivity in valve opening regulation.

[0125] The gas-liquid separation device of the electric hydrogen production system provided in the present application uses a common gas-liquid separation device, which increases the volume of the gas-liquid separation device and the stability of the alkali liquid level. At the same time, by using a valve parallel group and different valves using different valve gas pressures, the continuity of the outlet valve flow is improved. The valve group uses three parallel valves, and the back pressure of the pneumatic valve is based on the provisions of the hydrogen outlet pressure of the electric hydrogen production system. For example, the hydrogen outlet pressure of the electric hydrogen production system is set to 1.5MPa~2.4MPa, and the back pressures of the three valves are selected as 2.2MPa, 2.3MPa, and 2.4MPa, respectively, which can improve the flow adjustment range of the valve group and the continuity of flow adjustment.

[0126] The gas outlet flow rate in the gas-liquid separation device of the electric hydrogen production system is analyzed in real time by the operating power of the electrolyzer array system, and the gas production is calculated by using the model, and then the feedforward gas outlet valve is adjusted to avoid delays in gas flow control under operating conditions where the power of the electrolyzer array system fluctuates greatly, resulting in large fluctuations in the alkali liquid level in the gas-liquid separation device. The gas outlet flow rate of the electric hydrogen production system adjusts the opening of the outlet valve group according to the gas production in the electrolyzer and the gas separation capacity of the gas-liquid separation device to ensure stable gas pressure and stable alkali liquid level in the gas-liquid separation device.

[0127] Among them, the outlet flow rate in the gas-liquid separation device satisfies the formula:

[0128] Q out =Q in +Q sep

[0129] Among them, Q out is the outlet flow rate of the gas-liquid separation device, in m 3 / h;Q in is the gas flow rate of the gas-liquid mixture entering the gas-liquid separation device, in m 3 / h;Q sep It is the gas output separated from the liquid dissolved gas in the gas-liquid separation device, in m 3 / h.

[0130] By monitoring the operating power of the electrolyzer array system, the gas production is calculated in advance according to the model, and the flow of the gas outlet valve is adjusted in advance to ensure the relative stability of the pressure in the gas-liquid separation device. The gas flow in the gas-liquid mixture entering the gas-liquid separation device satisfies the formula:

[0131] Q in =∫P i-mn dt / η eh

[0132] Among them, P i-mn is the operating power of the i-th electrolyzer array system, in kW; η eh is the efficiency of the hydrogen production system of the electrolyzer array system, in Nm 3 H2 / kWh.

[0133] It should also be noted that, in order to make the outlet gas impurities of the electrolytic water system meet the requirements and the electrolytic water system operates more stably, as an implementation method, the gas-liquid separation device is also connected to the gas purification device, and the gas-liquid separation device includes a first separation device and a second separation device. The method also includes:

[0134] The water electrolysis system is controlled to operate under constraints, wherein the constraints include:

[0135] Control each electrolytic cell to operate within the preset voltage, current and temperature range;

[0136] Controlling the impurity content of the gas separated by the gas-liquid separation device to be within a preset range;

[0137] Control the gas pressure at the outlet of the gas-liquid separation device to be lower than the pressure threshold of the gas purification device;

[0138] The gas-liquid separation capacity of the gas-liquid separation device is controlled to be lower than the capacity threshold;

[0139] The liquid level difference between the first separation device and the second separation device is controlled to be smaller than a preset value.

[0140] At present, oxygen sensors are installed in the oxygen alkali liquid separator and the hydrogen separator in the gas-liquid separator of the electric hydrogen production system. The oxygen impurity content in hydrogen and the hydrogen impurity content in oxygen are monitored in real time. The operation status of the electrolyzer is analyzed by monitoring the impurity content in the gas, and corresponding early warnings are issued to notify the equipment operator to adjust the operating power and alkali liquid circulation volume of the electrolyzer to reduce impurities in the gas production and ensure the safe and reliable operation of the system. Since the gas-liquid separator currently used in the industry is a gravity separation type equipment, it does not have the ability to externally adjust the gas-liquid separation process. The alkali liquid circulation volume uses an alkali liquid pump with a relatively fixed speed, which can only adjust the alkali liquid valve group at the inlet of the electrolyzer to adjust the alkali liquid circulation volume, and the adjustment ability of the alkali liquid flow is limited. The operating power of the electrolyzer is manually adjusted, resulting in relatively poor adjustment accuracy and speed.

[0141] The gas-liquid separator of the electric hydrogen production system adopts a spiral centrifugal separator. The gas-liquid separation capacity in the gas-liquid separator can be adjusted by adjusting the centrifugal speed, thereby finely adjusting the gas-liquid separation process. The alkali liquid circulation volume of the matrix electric hydrogen production system can be improved by controlling the frequency conversion pump and the inlet valve to improve the adjustment range and accuracy of the alkali liquid circulation volume. The operating power of the electrolyzer in the matrix electric hydrogen production system can automatically adjust the equipment operating power according to the impurities at the outlet of the gas-liquid separator to ensure that the purity of the produced gas meets the requirements of process production.

[0142] The system controller of the matrix-type electric hydrogen production system automatically adjusts the speed of the rotating equipment in the gas-liquid separator, the opening of the alkali liquid pump and the inlet valve to adjust the circulation volume of the alkali liquid and the operating power of the electrolyzer array system by monitoring the impurity content in the oxygen alkali liquid separator and the hydrogen alkali liquid separator, so as to achieve comprehensive measures to control the impurity content of the gas at the outlet of the system. When the oxygen impurity content in hydrogen or the hydrogen impurity content in oxygen increases and reaches the upper limit of the impurity set by the equipment, the speed of the rotating equipment in the gas-liquid separator is increased to improve the separation capacity, while the speed of the alkali liquid pump and the opening of the inlet valve are reduced to reduce the circulation volume, and at the same time, the operating power of the electric hydrogen production equipment is increased.

[0143] Among them, the operating constraints of the electrolyzer array system in the matrix water electrolysis system are as follows:

[0144] 1) Electrolyzer voltage constraint: The DC voltage of each electrolyzer needs to be lower than the voltage range specified by the equipment

[0145] V vmin ≤V ij ≤V vmax

[0146] Among them, V ij is the cell voltage of the jth cell in the i-th group of the m*n matrix cell array system, in V; V vmin 、V vmax They are the maximum and minimum voltages limited by the electrolyzer, in V. The voltage of the electrolyzer is the voltage on the DC side of the converter, obtained through the converter equipment sensor, and its value is equal to the sum of the voltages of all electrolytic cells and the DC conductor voltage. At present, the cell voltage threshold of the electrolyzer in the industry varies according to the equipment model, and is not limited here. For example, the maximum and minimum voltages of a certain model of 5MW alkaline electrolyzer equipment are 750V and 500V respectively.

[0147] 2) Electrolytic cell current constraint: The DC current of each electrolytic cell needs to be lower than the maximum current limited by the equipment:

[0148] I ij ≤I max

[0149] Among them, Iij is the current of the jth electrolytic cell in the i-th group of the m*n matrix electrolytic cell array system, in A; I max The maximum current of the electrolyzer is in A. The current of the electrolyzer is the current on the DC side of the converter, which is obtained by the sensor of the converter equipment. The current threshold of the electrolyzer in the industry varies according to the equipment model, and is not limited here. For example, the maximum current of a certain model of 5MW alkaline electrolyzer equipment is 6500A.

[0150] 3) Electrolyzer temperature constraint: Each electrolyzer needs to be within the equipment’s limited temperature operating range

[0151] T min ≤T ij ≤T max

[0152] Among them, T ij is the temperature of the jth electrolytic cell in the i-th group of the m*n matrix electrolytic cell array system, in °C, which is equal to the average of the electrolytic cell inlet temperature and the gas-alkali mixture outlet temperature; T min With T max are the maximum and minimum temperatures of the electrolytic cell, respectively, in °C. min With T max They are 45°C and 95°C respectively. When the equipment temperature is lower than 45°C, the poor conductivity of the alkali solution causes the internal resistance in the electrolytic cell to increase, resulting in increased power consumption. When the equipment temperature is higher than 95°C, the performance of the diaphragm and sealing materials in the electrolytic cell deteriorates, and long-term over-temperature operation will cause equipment damage.

[0153] The m*n matrix electrolytic cell array system uses a shared gas-liquid separator to improve the consistency of the alkali solution temperature in the electrolytic cell and the gas-liquid separator. In the parallel electrolytic cells, the power reduction of a certain electrolytic cell leads to a reduction in heat production, but the electrolytic cell group connected in parallel with it can still generate sufficient heat, thereby improving the power adjustment range and control flexibility of the electrolytic cell group.

[0154] It should be noted that in the water electrolysis system, the gas-liquid separation device includes a hydrogen / liquid separation device and an oxygen / liquid separation device, which can separate hydrogen and oxygen respectively. Therefore, it is necessary to control the impurity content of hydrogen gas and oxygen gas respectively within a preset range. On this basis, the constraints also include:

[0155] 4) The oxygen impurities in the hydrogen in the hydrogen alkali liquid separator need to be lower than the specified threshold of the equipment

[0156] V jh-o ≤V h-omax

[0157] Among them, V jh-oV is the oxygen impurity content in the hydrogen in the jth hydrogen-alkali liquid separator in the m*n matrix electrolyzer array system, and its value is collected by the sensor in the oxygen-alkali liquid separator; h-omax Specify maximum thresholds for oxygen impurities in hydrogen in hydrogen production systems.

[0158] 5) The hydrogen impurity in the oxygen in the oxygen alkali liquid separator needs to be lower than the specified threshold of the equipment

[0159] V jo-h ≤V o-hmax

[0160] Among them, V jo-h is the hydrogen impurity content in oxygen in the j-th oxygen-alkali liquid separator in the m*n matrix electrolyzer array system, and its value is collected by the sensor in the oxygen-alkali liquid separator; V o-hmax Establish maximum thresholds for hydrogen impurities in oxygen in hydrogen production systems.

[0161] 6) The gas pressure at the outlet of the gas-liquid separator needs to be lower than the maximum pressure threshold of the subsequent gas purification device

[0162] p jp ≤p gmax

[0163] Among them, p jp is the pressure at the outlet of the jth gas-liquid separator in the m*n matrix electrolyzer array system, in Pa, and its value is collected by the outlet sensor in the gas-liquid separator; p gmax The maximum pressure threshold limited by the gas purification device in the electric hydrogen production system is 2.95Mpa.

[0164] 7) The gas-liquid separation capacity of the gas-liquid separator needs to be lower than the specified threshold of the equipment

[0165] S j ≤S max

[0166] Among them, S j is the gas-liquid separation capacity at the outlet of the jth gas-liquid separator in the m*n matrix electrolyzer array system, in Nm 3 / h, the value is calculated according to the power correlation formula of all electrolytic cells connected to the gas-liquid separator; S max The maximum gas-liquid separation capacity of the gas-liquid separator in the electric hydrogen production system.

[0167] The electric power is distributed limitedly between the electrolytic cell groups in the m*n matrix electrolytic cell array system. Since the shared gas-liquid separation device limits the adjustment flexibility of a single electrolytic cell group, a single electrolytic cell group needs to consider the performance constraints of the shared gas-liquid separator. In a single m*n matrix electrolytic cell array system, the electrolytic cell groups have the same current in series, so the converter that controls the electrolytic cell group can achieve synchronous control of the electric power of the m electrolytic cells in the electrolytic cell group, and the n parallel electrolytic cell groups can perform limited power distribution, and the power distribution constraint is the gas-liquid separation capacity S of the shared gas-liquid separation device.

[0168] The gas-liquid separation capacity of the gas-liquid separation device is the mass of gas separated from the gas-liquid mixture per unit time. Its capacity is affected by the inlet gas-liquid mixture flow rate, gas content of the mixture, bubble diameter, liquid phase density, liquid phase dynamic viscosity, gas phase density, and gas phase dynamic viscosity. The gas-liquid separation capacity of different types of gas-liquid separation devices has a maximum value S max In the process of power regulation between different electrolytic cell groups, it is necessary to ensure that the gas-liquid separation capacity required for the operation of the shared gas-liquid separation device is less than the device-limited threshold x.

[0169] S(j)=P(j)*k1*P(j) 2 *k2*k3

[0170]

[0171] Where S(j) is the gas-liquid separation capacity of the j-th gas-liquid separator in the m*n matrix electrolyzer array system, Nm3 / h; P(j) is the sum of the powers of all electrolyzers connected to the j-th gas-liquid separator in the m*n matrix electrolyzer array system, in kW; k1, k2 and k3 are correlation coefficients determined by laboratory equipment tests.

[0172] 8) Liquid level difference between the hydrogen side and the oxygen side of the gas-liquid separator

[0173] ΔH ho ≤ΔH homax

[0174] Where ΔH ho ΔH is the absolute value of the liquid level difference between the hydrogen side and the oxygen side of the jth gas-liquid separator in the m*n matrix electrolyzer array system, in mm, and its value is calculated based on the data of the hydrogen side and oxygen side liquid level sensors; homax The maximum threshold of the liquid level difference between the hydrogen side and the oxygen side defined for the gas-liquid separator device.

[0175] In summary, the electrolytic cell array system and control method thereof provided by the present application have the following beneficial effects:

[0176] 1. The efficient integration of large-capacity hydrogen production systems has been achieved, and the system scale can reach the GW level. By connecting the electrolyzer array system in parallel, the independent and flexible scheduling of different electrolyzer array systems can be achieved. At the same time, the investment cost of the converter is reduced by connecting the electrolyzer groups in parallel within the electrolyzer array system, and the investment cost of the gas-liquid separation device is reduced by sharing the gas-liquid separation device through the parallel electrolyzers. This large-capacity hydrogen production system integration technology solution can effectively reduce system investment redundancy, reduce system investment costs, and improve the benefits of large-capacity hydrogen production systems.

[0177] 2. This application proposes to use a gas-liquid separation device with an inner surface insulation, which can solve the problem of gas-liquid separation device equipment. It is to solve the problem that after the electrolytic cells are connected in series, the potential of some electrolytic cells is high, which is easy to cause short-circuit current between alkali solution, gas-liquid separation device and grounding. This technical solution can realize the connection of large-capacity electrolytic cells, and is also a key technology for sharing gas-liquid separation devices.

[0178] 3. Based on the structural characteristics of the H-mn matrix hydrogen production system and the characteristics of the electrolyzer equipment, this application proposes a hierarchical power control method based on the electrolyzer array system and the electrolyzer group, which improves the power regulation range and power regulation accuracy of the hydrogen production system, and improves the regulation ability of the large-capacity hydrogen production system in response to power auxiliary service scheduling or production plan scheduling, which can effectively reduce the system operation and maintenance costs.

[0179] 4. Based on the structural characteristics of the H-mn matrix electric hydrogen production system and the characteristics of the electrolyzer equipment, this application proposes a control method for a large-capacity electric hydrogen production system, including a power control method, an alkali water replenishment control method, an alkali temperature control method, a hydrogen side and oxygen side liquid level difference control method, a gas outlet flow control method, and an outlet gas impurity control method. This system control method can improve the control accuracy of the electric hydrogen production system, so that the electric hydrogen production system can operate at the maximum efficiency point of the system, reduce the auxiliary power consumption during the control process of power change, temperature, alkali circulation, gas flow, impurities, etc., and reduce the system operation and maintenance costs.

[0180] 5. The present application proposes an alkali solution temperature control method based on converter power and electrolyzer inlet temperature feedforward, which can improve the alkali solution temperature stability, effectively ensure that the electrolyzer outlet temperature does not exceed the set temperature, and at the same time reduce the extra power consumption of the electrolyzer caused by the low alkali solution temperature under variable operating conditions, thereby improving the overall performance of the electric hydrogen production system.

[0181] 6. The alkali liquid water replenishment control method proposed in this application analyzes the real-time water consumption based on the water consumption model of hydrogen production by electricity and uses it as a feedforward parameter, which can reduce the impact of traditional water replenishment methods on alkali liquid temperature control.

[0182] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

[0183] It will be apparent to those skilled in the art that the present application is not limited to the details of the exemplary embodiments described above, and that the present application can be implemented in other specific forms without departing from the spirit or essential features of the present application. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the present application is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present application. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

Claims

1. An electrolytic cell array system, characterized in that: The electrolytic cell array system comprises a plurality of gas-liquid separation devices and a plurality of electrolytic cell groups arranged in parallel, the electrolytic cell groups are connected to the converter, each electrolytic cell group comprises a plurality of electrolytic cells arranged in series, the number of the gas-liquid separation devices is the same as the number of electrolytic cells in the electrolytic cell group, wherein: The electrolytic cells in the same order in the plurality of electrolytic cell groups are all connected to the same gas-liquid separation device; The electrolysis voltages of the electrolytic cells in the same order in the plurality of electrolytic cell groups are the same, so as to avoid the generation of bypass current due to the potential difference in the alkali solution circuit in the gas-liquid separation device; The gas-liquid separation device includes an insulating layer and a shell, the insulating layer is connected to the shell, and an inlet, a gas outlet and a liquid outlet are provided at the same position of the insulating layer and the shell, the inlet and the liquid outlet are both connected to the electrolytic cell, and the gas outlet is used to connect to a gas storage device.

2. The electrolytic cell array system according to claim 1, characterized in that: The electrolytic cell array system further includes a valve and a conduit, each of the electrolytic cells is connected to the conduit via a valve, and each of the electrolytic cells is connected to the gas-liquid separation device via a conduit; wherein, The valve is used to control the amount of liquid flowing into / out of the electrolytic cell, and the valve is used to be connected to a controller, wherein the controller is used to control the start / stop state and opening degree of the valve.

3. A water electrolysis system control method, characterized in that: The water electrolysis system comprises a plurality of electrolytic cell array systems as claimed in claim 1 or 2, wherein the plurality of electrolytic cell array systems are arranged in parallel, and the method comprises: When receiving a power adjustment instruction, determining the external power demand of the system; Determining an adjustment power value according to the external required power and the current operating power; The working state of each electrolytic cell is determined according to the regulated power value, the external required power value, and the maximum power and the minimum power of each electrolytic cell.

4. The water electrolysis system control method according to claim 3, characterized in that: When a power reduction instruction is received, the step of determining the working state of each electrolytic cell according to the adjusted power value, the external required power value, and the maximum power and the minimum power of each electrolytic cell comprises: When the external power requirement satisfies H*m*n*P emin ≤P≤H*m*n*P emax When the power is adjusted, the adjusted power value is evenly distributed to each electrolytic cell group to balance the load of each electrolytic cell group; When the external power requirement satisfies η*H*m*n*P emin ≤P≤H*m*n*P emin When the electrolytic cell array system is closed, control part or all of the electrolytic cell groups in the electrolytic cell array system to be closed; When the external power requirement satisfies η*m*n*P emin ≤P≤η*H*m*n*P emin When the power required by the external power source is 1, part of the electrolyzer array systems are controlled to be shut down, and the external power required is distributed to the remaining electrolyzer array systems; When the external power requirement satisfies m*P emin ≤P≤η*m*n*P emin When one of the electrolytic cell array systems is in operation, the number of electrolytic cell groups in the electrolytic cell array system in operation is adjusted; When the external power requirement meets P <m*P emin When the water electrolysis system is determined to be unable to respond to the instruction; Where n represents the number of electrolytic cell groups, m represents the number of electrolytic cells in each electrolytic cell group, H represents the number of electrolytic cell array systems, η represents a coefficient greater than 0 and less than 1, and P emin represents the minimum power of each electrolyzer, P emax Indicates the maximum power of each electrolyzer.

5. The water electrolysis system control method according to claim 3, characterized in that: When a power increase instruction is received, the step of determining the working state of each electrolytic cell according to the adjusted power value, the external required power value, and the maximum power and the minimum power of each electrolytic cell comprises: When the external power requirement satisfies m*P emin ≤P≤m*n*P er When the current electrolytic cell array system is in operation, other electrolytic cell groups in the system are controlled to work; When the external power requirement satisfies m*n*P er ≤P≤2*m*n*P er When the next electrolytic cell array system is controlled to work; When the external power requirement satisfies H0*m*n*P er ≤P≤(H0+1)*m*n*P er When the next electrolytic cell array system is controlled, the whole system works; When the external power requirement satisfies H*m*n*P er ≤P≤H*m*n*P emax When the electrolyzer array system is controlled to work synchronously; When the external required power satisfies H*m*n*P emax <When P, it is determined that the electrolyzed water system cannot respond to the instruction; Where n represents the number of electrolytic cell groups, m represents the number of electrolytic cells in each electrolytic cell group, H represents the number of electrolytic cell array systems, H0 represents the number of electrolytic cell array systems currently in normal operation, and P emin represents the minimum power of each electrolyzer, P emax Indicates the maximum power of each electrolyzer, P er Indicates the rated power of each electrolyzer.

6. The water electrolysis system control method according to claim 3, characterized in that: Each of the gas-liquid separation devices is also connected to a water replenishment device, and the water electrolysis system control method further includes: Obtain the operating power and hydrogen production efficiency of each electrolyzer array system; The water replenishment amount is determined according to the operating power and hydrogen production efficiency, wherein the water replenishment amount satisfies the formula: Where W i-j represents the water replenishment amount of the jth gas-liquid separation device in the i-th electrolyzer array system, η eh represents the efficiency of hydrogen production from electricity of the i-th electrolyzer array system, P i-mn For operating power.

7. The water electrolysis system control method according to claim 3, characterized in that: A heat exchanger is provided in the gas-liquid separation device, and the method further comprises: According to the formula T ijn-out =T ijn-in +k t1 *P i-mn +k t2 *P cij Adjust the working state of the heat exchanger, where T ijn-out is the average alkali solution temperature at the outlet of the n electrolytic cells connected to the j-th gas-liquid separation device in the i-th electrolytic cell array system; T ijn-in is the average alkali solution temperature at the inlet of the n electrolytic cells connected to the j-th gas-liquid separation device in the i-th electrolytic cell array system; P i-mn is the operating power of the i-th electrolyzer array system, P cij is the heat transferred by the heat exchanger in the jth gas-liquid separation device in the i-th electrolyzer array system, and P cij =W cij *Cc*(t1-t2),W cij represents the flow rate of the coolant in the heat exchanger in the gas-liquid separation device, Cc is the isobaric specific heat capacity of the coolant; t1 and t2 are the outlet and inlet temperatures of the heat exchanger, k t1 With k t2 Represents the parameters of the electrolyzer array system determined during testing.

8. The water electrolysis system control method according to claim 3, characterized in that: The gas-liquid separation device comprises a first separation device and a second separation device, and the method further comprises: The alkali solution flow rate of the first separation device and the second separation device is adjusted according to the formula ΔW=Δh*S*ρ*Δt; wherein ΔW represents the alkali solution flow rate that needs to be adjusted between the first separation device and the second separation device; Δh represents the liquid level difference between the first separation device and the second separation device, S is the equivalent cross-sectional area in the corresponding separation device, ρ is the density of the alkali solution, and Δt is the setting time for leveling the liquid level difference between the first separation device and the second separation device.

9. The water electrolysis system control method according to claim 3, characterized in that: The gas-liquid separation device is also connected to the gas purification device, and the gas-liquid separation device includes a first separation device and a second separation device. The method further includes: Controlling the water electrolysis system to operate under constraint conditions, wherein the constraint conditions include: Control each electrolytic cell to operate within the preset voltage, current and temperature range; Controlling the impurity content of the gas separated by the gas-liquid separation device to be within a preset range; Controlling the gas pressure at the outlet of the gas-liquid separation device to be lower than the pressure threshold of the gas purification device; Controlling the gas-liquid separation capacity of the gas-liquid separation device to be lower than the device capacity threshold; The liquid level difference between the first separation device and the second separation device is controlled to be smaller than a preset value.

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