A method for stable operation of a seawater hydrogen production system under variable load conditions

Abstract

The application relates to the technical field of hydrogen production system operation, in particular to a seawater hydrogen production system stable operation method under variable load conditions, which comprises the following steps: taking voltage minimization and maximum decay rate as double targets, generating a primary standby power supply group and a secondary state monitoring group through a Pareto stratification; monitoring whether the terminal voltage of the current primary standby power supply group reaches the saturation upper limit or whether the terminal voltage of the secondary state monitoring group falls below the critical early warning upper limit, serving as a one-way trigger event to execute a polling handover of the power supply state for electrical scheduling; in the electrical scheduling process, the remaining capacity of the standby battery and the residual gas pressure of the gas-liquid separator are synchronously monitored, and a system hibernation protection mechanism is triggered to terminate the electrical scheduling. The application solves the problems of switch high-frequency burning and emptying backflow caused by inaccurate prediction under variable load shutdown, and improves the stability of seawater hydrogen production system operation.

Description

Technical Field

[0001] This application relates to the field of hydrogen production system operation technology, specifically to a method for stable operation of a seawater hydrogen production system under variable load conditions. Background Technology

[0002] In industrial scenarios where seawater electrolysis is used to produce hydrogen using intermittent renewable energy sources such as offshore wind and solar power, the system frequently faces power outages due to sudden drops in wind and solar power input. After the main power is cut off, the electrodes inside the electrolyzer lose their polarization protection potential, and the high concentration of chloride ions in the seawater rapidly adsorbs onto the electrode surface, causing irreversible pitting corrosion. To slow down the corrosion process, industry practice typically involves using backup batteries to poll and maintain current to the parallel electrolyzer array when the main power is cut off, and finally draining the seawater in the final stage.

[0003] However, the discharge curve of a multi-slot parallel array exhibits high-order nonlinear distortion due to temperature differences. When traditional control logic uses single-point slope prediction or linear weighted evaluation, it is prone to dimensional bias and inaccurate time prediction. This error leads to incorrect polling scheduling, causing the switching matrix to operate at high frequency and easily burning out contacts. Furthermore, traditional venting methods also face the risk of seawater backflow caused by fluid pressure balance, ultimately reducing the stability of the seawater hydrogen production system. Summary of the Invention

[0004] To address the aforementioned technical problems, this application provides a method for stable operation of a seawater hydrogen production system under variable load conditions, thereby resolving the existing issues.

[0005] The present application provides a method for stable operation of a seawater hydrogen production system under variable load conditions, employing the following technical solution: One embodiment of this application provides a method for stable operation of a seawater hydrogen production system under variable load conditions, the method comprising the following steps: S1: Real-time acquisition of the terminal voltage of each electrolytic cell in the parallel electrolytic cell array, and generation of a feature sequence containing the absolute value of the terminal voltage and the terminal voltage decay rate by combining time-series differential operation; S2: Based on the aforementioned feature sequence, with minimizing the absolute value of the terminal voltage and maximizing the absolute value of the terminal voltage decay rate as dual optimization objectives, the electrolytic cell is Pareto-stratified using a non-dominated sorting algorithm to generate an initial backup power supply group and a secondary status monitoring group. S3: Connect the primary backup power supply group to the backup power supply and start the action shielding timer. During the timer period, suspend the boundary judgment. When the timer ends, enable the boundary judgment logic: monitor whether the terminal voltage of the current primary backup power supply group reaches the saturation limit, or whether the terminal voltage of the secondary status monitoring group falls below the critical warning limit. Perform the power supply status polling handover as a one-way trigger event for electrical dispatch. S4: During electrical dispatching, the remaining capacity of the backup battery and the residual gas pressure of the gas-liquid separator are monitored simultaneously to determine whether to trigger the system hibernation protection mechanism to terminate electrical dispatching.

[0006] Preferably, the process of generating the feature sequence is as follows: Identify whether an electrical connection state switch has occurred within a preset time window prior to the current moment. If an electrical connection state switch has occurred, set the current terminal voltage decay rate to 0. Conversely, if no electrical connection state switching has occurred, the difference between the terminal voltage of each electrolytic cell at the current moment and the terminal voltage at the adjacent previous moment is divided by the time interval between the current moment and the adjacent previous moment, and the result is taken as the terminal voltage decay rate of each electrolytic cell at the current moment. The normalized absolute value of the terminal voltage of each electrolytic cell at the current moment is combined with the normalized value of the terminal voltage decay rate into a binary pair. The sequence of binary pairs of all electrolytic cells at the current moment is denoted as the characteristic sequence.

[0007] Preferably, the process of performing Pareto stratification of the electrolytic cell using the non-dominated sorting algorithm is as follows: Electrolytic cells whose terminal voltage decay rate is less than a preset effective decay rate threshold in the feature sequence are selected to construct an effective discharge feature set. By comparing the absolute values ​​of the terminal voltages between different electrolytic cells, it can be determined whether there is a dominant relationship between the different electrolytic cells; Traverse all electrolytic cells in the effective discharge characteristic set, classify the electrolytic cells without a dominance relationship as the first Pareto front, and classify the remaining electrolytic cells as the secondary Pareto front.

[0008] Preferably, determining whether there is a dominance relationship between different electrolytic cells includes: In the effective discharge characteristic set, for electrolytic cell i and electrolytic cell j, if the absolute value of the terminal voltage of electrolytic cell i is less than or equal to the absolute value of the terminal voltage of electrolytic cell j, and the absolute value of the terminal voltage decay rate of electrolytic cell i is greater than or equal to the absolute value of the terminal voltage decay rate of electrolytic cell j, and at least one of these two inequalities has a strict less than or greater than relationship, then it is determined that electrolytic cell i dominates electrolytic cell j.

[0009] Preferably, the generation of the primary backup power supply group and the secondary status monitoring group includes: Obtain the maximum number of backup power output channels and the total number of electrolytic cells in the first Pareto front. If the total number of electrolytic cells is less than or equal to the maximum number of backup power outputs, then the set of all electrolytic cells within the first Pareto front is taken as the primary backup power supply group, and the set of all electrolytic cells within the secondary Pareto front is taken as the secondary status monitoring group. Conversely, the electrolytic cells within the first Pareto front are arranged in ascending order of absolute terminal voltage. The set of electrolytic cells with the maximum number of output channels of the backup power supply in the arrangement result is taken as the primary backup power supply group, and the remaining electrolytic cells are assigned to the secondary status monitoring group.

[0010] Preferably, the process of polling and handing over the power supply status is as follows: When the terminal voltage of any electrolyzer in the primary backup power supply group is greater than or equal to the saturation limit, or when the terminal voltage of any electrolyzer in the secondary status monitoring group is less than or equal to the critical warning limit, the seawater hydrogen production system is controlled to disconnect the electrical connection of all current primary backup power supply groups and return to step S1 to redetermine the primary backup power supply group for the next round, thereby realizing the polling handover of power supply status.

[0011] The preferred method for determining the upper limit of saturation is as follows: Electrochemical polarization curves of the electrode plates in the electrolyzer at corresponding concentrations of seawater were obtained to obtain the charging saturation voltage of the electrolyzer, which was then used as the upper limit of saturation.

[0012] The preferred method for determining the critical warning upper limit is as follows: Obtain the lower voltage limit to prevent chloride ion corrosion, and the absolute value of the maximum terminal voltage decay rate at the highest historical operating temperature; The approximation margin constant is determined based on the absolute value of the maximum terminal voltage decay rate, the preset sampling period, and the preset safety factor. The sum of the lower voltage limit for preventing chloride ion corrosion and the approximation margin constant is used as the critical warning upper limit.

[0013] Preferably, the approximation margin constant is the product of the absolute value of the maximum terminal voltage decay rate, the preset sampling period, and the preset safety factor.

[0014] Preferably, the process of determining whether to trigger the system hibernation protection mechanism to terminate electrical dispatch is as follows: In real time, determine whether the remaining capacity of the backup battery is less than or equal to the preset extremely low maintenance capacity threshold, or whether the residual gas pressure of the gas-liquid separator is less than or equal to the minimum gas pressure required to drain the seawater; when either condition is met, terminate the electrical dispatch.

[0015] This application has at least the following beneficial effects: This application successfully identifies the highest-risk priority power supply targets through a non-dominated sorting algorithm, establishing an objective resource peak-shifting allocation mechanism to ensure precise "rescue" of the most critical tanks when backup power is limited. Furthermore, by introducing an action shielding timer and a one-way over-limit triggering mechanism, this application effectively compensates for the physical time delay of hardware actions, ensuring stable low-frequency operation under limited backup power and greatly improving the operational stability of the seawater hydrogen production system under variable load shutdown conditions. Finally, by real-time monitoring of the backup battery charge and residual gas pressure as dual bottom lines, this application ensures reliable triggering of dry-state venting at the last moment before resource depletion, blocking the medium basis for chloride ion corrosion, achieving inherent safety protection under variable load shutdown conditions, and improving the operational stability of the seawater hydrogen production system. Attached Figure Description

[0016] To more clearly illustrate the technical solutions and advantages in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 A flowchart illustrating the steps of a method for stable operation of a seawater hydrogen production system under variable load conditions, as provided in one embodiment of this application; Figure 2 A flowchart illustrating the process of acquiring the initial backup power supply group and the secondary status monitoring group, as provided in one embodiment of this application. Detailed Implementation

[0018] To further illustrate the technical means and effects adopted by this application to achieve the intended purpose of the invention, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of a method for stable operation of a seawater hydrogen production system under variable load conditions proposed in this application. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0020] The following description, in conjunction with the accompanying drawings, details a specific scheme for a stable operation method of a seawater hydrogen production system under variable load conditions provided in this application.

[0021] This application provides a method for stable operation of a seawater hydrogen production system under variable load conditions in one embodiment. Specifically, it provides the following method for stable operation of a seawater hydrogen production system under variable load conditions. Please refer to [link to relevant documentation]. Figure 1 The method includes the following steps: Step S1: Real-time acquisition of the terminal voltage of each electrolytic cell in the parallel electrolytic cell array, and generation of a feature sequence containing the absolute value of the terminal voltage and the terminal voltage decay rate by combining time-series differential operation.

[0022] In this embodiment, the seawater hydrogen production system mainly consists of four core parts: a power supply unit, an electrolysis unit, a control unit, and a venting unit. The power supply unit includes a main rectifier cabinet and a backup battery equipped with a battery management system (BMS). It is connected to the electrolysis unit, which is composed of multiple electrolyzers connected in parallel, through a high-power DC multiplexer matrix with built-in relay contacts. The switch matrix is ​​used to realize the independent on / off control of each cell by the backup power supply. The control unit integrates voltage and pressure sensors to collect the voltage at each cell end and the gas pressure inside the gas-liquid separator in real time, which serves as the hardware basis for algorithm operation and decision-making. The venting unit consists of a gas-liquid separator that stores high-pressure gas, a pneumatic reflux valve, and a waste liquid tank with an exhaust valve on the top. It is connected to the flow channel of the electrolysis cell through pipelines. In emergency situations, the seawater in the electrolysis cell is squeezed into the waste liquid tank in one direction by utilizing the static pressure difference between the gas-liquid separator and the waste liquid tank.

[0023] When a power outage occurs due to varying loads from wind and solar power inputs, the main rectifier cabinet of the seawater hydrogen production system cuts off the main power supply to the electrolyzer array. Upon detecting the main power disconnection command, the timestamp of the detected power outage is marked as the initial power outage moment. .

[0024] Mark the time of the first power outage Then, according to the preset sampling period (In this embodiment, the preset sampling period is 0.1s, that is, data is collected once every 0.1s), and the terminal voltage of each electrolytic cell in the parallel electrolytic cell array is collected synchronously. The terminal voltage is the average voltage within the preset sampling period before the current moment.

[0025] Furthermore, by combining time-series differential operations, a feature sequence containing the absolute value of the terminal voltage and the terminal voltage decay rate is generated, specifically: In this embodiment, an electrical connectivity status mapping table is maintained and updated with the control cycle. By reading the status flag bit in the mapping table, it is identified whether an electrical connectivity status switch has occurred within a preset time window before the current moment. If an electrical connectivity status switch has occurred, the terminal voltage decay rate at the current moment is set to 0. Conversely, if no electrical connection state switching has occurred, the difference between the terminal voltage of each electrolytic cell at the current moment and the terminal voltage at the adjacent previous moment is divided by the time interval between the current moment and the adjacent previous moment, and the result is taken as the terminal voltage decay rate of each electrolytic cell at the current moment. The normalized absolute value of the terminal voltage of each electrolytic cell at the current moment is combined with the normalized value of the terminal voltage decay rate into a binary pair. The sequence of binary pairs of all electrolytic cells at the current moment is denoted as the characteristic sequence.

[0026] It should be noted that the size of the preset time window is set manually. In this embodiment, the size of the preset time window is the length of 3 sampling periods. In actual applications, as other implementation methods, implementers can also set it according to specific circumstances. This embodiment does not impose any special restrictions.

[0027] Step S2: Based on the feature sequence, with minimizing the absolute value of the terminal voltage and maximizing the absolute value of the terminal voltage decay rate as dual optimization objectives, the electrolytic cell is Pareto-stratified using a non-dominated sorting algorithm to generate the initial backup power supply group and the secondary status monitoring group.

[0028] However, due to the uneven temperature distribution among the electrolytic cells in the multi-cell parallel array, the plate capacitor discharge exhibits high-order nonlinear characteristics. Therefore, it is necessary to determine the priority power supply targets and those to be temporarily deferred based on the urgency of the electrolytic cells approaching the corrosion threshold, given limited backup power channel resources. Thus, this embodiment, based on the aforementioned characteristic sequence, uses minimizing the absolute value of the terminal voltage and maximizing the absolute value of the terminal voltage decay rate as dual optimization objectives. A non-dominated sorting algorithm is used to perform Pareto hierarchical classification of the electrolytic cells to generate the initial backup power supply group and the secondary status monitoring group. The specific process is as follows: First, based on the aforementioned feature sequence, and using the minimization of the absolute value of the terminal voltage and the maximization of the absolute value of the terminal voltage decay rate as dual optimization objectives, a Pareto stratification of the electrolyzer is performed using a non-dominated sorting algorithm. Specifically: In this embodiment, electrolytic cells with a terminal voltage decay rate less than a preset effective decrease rate threshold in the feature sequence are selected to construct an effective discharge feature set; By comparing the absolute values ​​of the terminal voltages of different electrolytic cells, it is determined whether there is a dominance relationship between them. Specifically, in the effective discharge characteristic set, for electrolytic cell i and electrolytic cell j, if the absolute value of the terminal voltage of electrolytic cell i is less than or equal to the absolute value of the terminal voltage of electrolytic cell j, and the absolute value of the terminal voltage decay rate of electrolytic cell i is greater than or equal to the absolute value of the terminal voltage decay rate of electrolytic cell j, and at least one of these two inequalities has a strict less than or greater than relationship, then it is determined that electrolytic cell i dominates electrolytic cell j. Furthermore, by traversing all electrolytic cells in the effective discharge characteristic set, electrolytic cells without a dominance relationship are classified as the first Pareto front, and the remaining electrolytic cells are classified as the secondary Pareto front.

[0029] It should be noted that the preset effective descent rate threshold is set manually. In this embodiment, the preset effective descent rate threshold is set to -0.01V / s. In actual applications, as other implementation methods, implementers can also set it according to specific circumstances. This embodiment does not impose any special restrictions.

[0030] Furthermore, based on the first Pareto front and the second Pareto front, the primary backup power supply group and the secondary status monitoring group are divided, specifically: In this embodiment, the maximum number of output channels of the backup DC power supply is extracted through the bus communication of the seawater hydrogen production system, and the total number of electrolyzers in the first Pareto front is counted at the same time. If the total number of electrolytic cells is less than or equal to the maximum number of backup power outputs, it means that all extremely dangerous electrolytic cells within the first Pareto front are within the capacity of the backup power supply. In this case, the set of all electrolytic cells within the first Pareto front is taken as the primary backup power supply group, and the set of all electrolytic cells within the secondary Pareto front is taken as the secondary status monitoring group. Conversely, if the total number of electrolytic cells is greater than the maximum number of output channels of the backup power supply, it means that if all are connected, it will cause a serious overload of the backup battery. In this case, the electrolytic cells in the first Pareto front are arranged in ascending order of the absolute value of the terminal voltage. The set of electrolytic cells with the maximum number of output channels of the backup power supply in the arrangement result is taken as the first backup power supply group, and the remaining electrolytic cells are assigned to the secondary status monitoring group.

[0031] Preferably, the flowchart of the acquisition process of the initial backup power supply group and the secondary status monitoring group provided in this embodiment is as follows: Figure 2 As shown.

[0032] Based on the acquisition process of the initial backup power supply group and the secondary status monitoring group, it can be understood that, through a non-dominated sorting algorithm, the absolute value of the terminal voltage, which represents static risk, and the absolute value of the decay rate, which represents dynamic deterioration trend, are constructed as dual-objective optimization dimensions. This allows the set of cells that simultaneously meet the extreme danger characteristics of "lowest voltage and fastest decay" to be extracted from massive electrolyzer data as the first Pareto front. Based on the physical capacity limit of the backup power supply, the initial backup power supply group, which receives limited power rescue, is established. The set of cells with relatively lower danger and no dominant advantage is divided into the secondary status monitoring group. This process realizes a resource staggered allocation mechanism based on "criticality level stratification". It ensures that, under the constraint of limited backup power supply power, precious electrical energy can be accurately and preferentially delivered to the electrolyzers that are closest to the corrosion line and most in need of rescue, thereby maximizing the extension of the safe survival window of the entire parallel array.

[0033] Thus, this embodiment successfully identified the highest-risk priority power supply targets through a non-dominated sorting algorithm, establishing an objective resource staggered allocation mechanism to ensure that the most critical tanks can be accurately "rescued" when backup power is limited.

[0034] Step S3: Connect the primary backup power supply group to the backup power supply and start the action shielding timer. During the timer period, suspend the boundary judgment. When the timer ends, enable the boundary judgment logic: monitor whether the terminal voltage of the current primary backup power supply group reaches the saturation limit, or whether the terminal voltage of the secondary status monitoring group falls below the critical warning limit. Perform power supply status polling handover as a one-way trigger event for electrical dispatch.

[0035] To address the issue of relay burnout caused by traditional timed polling mechanisms, this embodiment connects the primary backup power supply group to the backup power supply and starts an action shielding timer, suspending out-of-bounds judgment during the timer period. After the timer ends, the out-of-bounds judgment logic is activated: it monitors whether the terminal voltage of the current primary backup power supply group reaches the saturation limit, or whether the terminal voltage of the secondary status monitoring group falls below the critical warning limit, as a unidirectional trigger event to perform power supply status polling handover for electrical dispatching. The specific process is as follows: When the terminal voltage of any electrolyzer in the primary backup power supply group is greater than or equal to the saturation limit, or when the terminal voltage of any electrolyzer in the secondary status monitoring group is less than or equal to the critical warning limit, the seawater hydrogen production system is controlled to disconnect the electrical connection of all current primary backup power supply groups and return to step S1 to redetermine the primary backup power supply group for the next round, thereby realizing the polling handover of power supply status.

[0036] It should be further explained that the method for determining the upper limit of saturation is as follows: obtain the electrochemical polarization curve of the electrode plates in the electrolyzer in seawater of the corresponding concentration, obtain the charging saturation voltage of the electrolyzer, and take the charging saturation voltage of the electrolyzer as the upper limit of saturation (for example, calibrated to 1.8V); the process of obtaining the electrochemical polarization curve and the process of obtaining the saturation voltage from the electrochemical polarization curve are well-known techniques and will not be described in detail here.

[0037] In addition, the method for determining the critical warning upper limit is to obtain the lower limit of the voltage to prevent chloride ion corrosion and the absolute value of the maximum terminal voltage decay rate at the highest historical operating temperature. Based on the absolute value of the maximum terminal voltage decay rate, the preset sampling period, and the preset safety factor, the approximation margin constant is determined, that is: the product of the absolute value of the maximum terminal voltage decay rate, the preset sampling period, and the preset safety factor is used as the approximation margin constant. Furthermore, the sum of the lower voltage limit for preventing chloride ion corrosion and the approximation margin constant is used as the critical warning upper limit.

[0038] It should be noted that the preset safety factor is 3 in this embodiment, which is intended to ensure that the calculated approximation margin constant can cover the voltage drop risk under extreme operating conditions. In actual applications, as other implementation methods, implementers can also set it according to specific circumstances. This embodiment does not impose any special restrictions.

[0039] Based on the above polling handover process, it can be understood that this embodiment abandons the traditional timed polling mechanism based on fixed time intervals and instead constructs an event-triggered scheduling logic with the actual voltage state exceeding the limit as the core. By setting two mutually exclusive unidirectional triggering conditions, namely "first group voltage saturation (stop when fully charged)" and "secondary group voltage bottoming out (cut off when critical)," the critical state points of each electrolytic cell during the charging and discharging process are accurately captured. At the same time, with the introduction of the action shielding timer, the logic judgment is forcibly frozen during the execution of hardware actions, which effectively compensates for the delay of relay mechanical action and the physical time delay of the plate capacitor charging establishment process. This mechanism fundamentally eliminates the risk of high-frequency oscillation caused by sampling discreteness or prediction inaccuracy, ensuring that each action of the switching matrix has a clear physical meaning and sufficient safety margin, and realizing a low-frequency, robust and efficient electrical scheduling closed loop under limited reserve power.

[0040] Thus, by introducing an action shielding timer and a one-way over-limit triggering mechanism, this embodiment effectively compensates for the physical time delay of hardware actions, ensures stable low-frequency operation under limited backup power, and greatly improves the operational stability of the seawater hydrogen production system under variable load shutdown conditions.

[0041] Step S4: During electrical dispatching, the remaining capacity of the backup battery and the residual gas pressure in the gas-liquid separator are monitored simultaneously to determine whether to trigger the system's hibernation protection mechanism to terminate electrical dispatching. As the electrical polling dispatching in Step S3 continues, the backup battery power is gradually consumed, and the residual gas pressure in the gas-liquid separator continuously decreases due to natural leakage. Maintaining electrical emergency response depends on these limited hardware resources. Once these resources are exhausted, the seawater hydrogen production system will lose its ability to perform venting protection actions. Therefore, in this embodiment, during electrical dispatching, the remaining capacity of the backup battery and the residual gas pressure in the gas-liquid separator are monitored simultaneously to determine whether to trigger the system's hibernation protection mechanism to terminate electrical dispatching. The specific process is as follows: The remaining capacity of the current backup battery is read through the battery management system (BMS). Subsequently, the residual gas pressure currently used for pneumatic work is read in real time via a pressure transmitter installed on top of the gas-liquid separator in the seawater hydrogen production system. After acquiring the above two real-time resource data sets, the pre-defined extremely low sustaining capacity threshold in the read-only memory of the seawater hydrogen production system is retrieved. and the minimum air pressure required to drain seawater .

[0042] After retrieving the threshold value, the system enters the parallel logical condition comparison branch: Branch 1 (Battery Limit Determination): Determine the current remaining capacity of the backup battery. Is it less than or equal to the extremely low maintenance capacity threshold? When judged When the condition is met, it means that the remaining available power of the backup battery has been exhausted and cannot continue to support the DC switching matrix to complete the next group polling switch action. The seawater hydrogen production system will soon face a complete power failure of the entire array. Continuing to maintain electrical connection will cause the seawater hydrogen production system itself to completely shut down.

[0043] Branch 2 (Aerodynamic baseline determination): Determine the current residual pressure Is it less than or equal to the minimum air pressure required to drain seawater? When judged When the conditions are met, it means that the high-pressure gas accumulated inside the gas-liquid separator has reached its lower limit in terms of expansion and work capacity. If the residual gas pressure continues to drop, the expansion thrust of the released gas will not be able to overcome the gravity of the seawater and the fluid resistance of the pipeline, causing seawater to remain on the surface of the electrode plate and causing large-area pitting corrosion.

[0044] When the above or If either of these two conditions is met, it is confirmed that the corrosion maintenance resources of the current seawater hydrogen production system have reached the hardware safety limit. Once the limit is reached, a global power failure interlock signal with the highest interruption priority is immediately generated to prepare to trigger subsequent venting protection actions.

[0045] Upon receiving the global power failure interlock signal, all operating processes from front-end S1 to S3 are forcibly terminated, the main contactor of the DC multiplexer matrix in the seawater hydrogen production system is disconnected, and the pneumatic reflux valve connecting the gas-liquid separator and the electrolyzer's inlet manifold, as well as the normally closed exhaust valve on the top of the waste tank, are opened to connect the waste tank to the atmosphere. The residual gas pressure in the gas-liquid separator is used to force the seawater in the electrolyzer into the waste tank until there is no liquid residue in the electrolyzer.

[0046] Thus, this embodiment ensures reliable dry venting at the last moment before resources are exhausted by real-time monitoring of both backup battery power and residual gas pressure, blocking the medium basis for chloride ion corrosion, achieving inherent safety protection under variable load shutdown conditions, and improving the operational stability of the seawater hydrogen production system.

[0047] It should be noted that the order of the embodiments described above is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. Furthermore, specific embodiments of this specification have been described above. Additionally, the processes depicted in the accompanying drawings do not necessarily require a specific or sequential order to achieve the desired results. In some implementations, multitasking and parallel processing are possible or may be advantageous.

[0048] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0049] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them; modifications to the technical solutions described in the foregoing embodiments, or equivalent substitutions of some of the technical features, do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for stable operation of a seawater hydrogen production system under variable load conditions, characterized in that, The method includes the following steps: S1: Real-time acquisition of the terminal voltage of each electrolytic cell in the parallel electrolytic cell array, and generation of a feature sequence containing the absolute value of the terminal voltage and the terminal voltage decay rate by combining time-series differential operation; S2: Based on the aforementioned feature sequence, with minimizing the absolute value of the terminal voltage and maximizing the absolute value of the terminal voltage decay rate as dual optimization objectives, the electrolytic cell is Pareto-stratified using a non-dominated sorting algorithm to generate an initial backup power supply group and a secondary status monitoring group. S3: Connect the primary backup power supply group to the backup power supply and start the action shielding timer. During the timer period, suspend the boundary judgment. When the timer ends, enable the boundary judgment logic: monitor whether the terminal voltage of the current primary backup power supply group reaches the saturation limit, or whether the terminal voltage of the secondary status monitoring group falls below the critical warning limit. Perform the power supply status polling handover as a one-way trigger event for electrical dispatch. S4: During electrical dispatching, the remaining capacity of the backup battery and the residual gas pressure of the gas-liquid separator are monitored simultaneously to determine whether to trigger the system hibernation protection mechanism to terminate electrical dispatching.

2. The method for stable operation of a seawater hydrogen production system under variable load conditions as described in claim 1, characterized in that, The process of generating the feature sequence is as follows: Identify whether an electrical connection state switch has occurred within a preset time window prior to the current moment. If an electrical connection state switch has occurred, set the current terminal voltage decay rate to 0. Conversely, if no electrical connection state switching has occurred, the difference between the terminal voltage of each electrolytic cell at the current moment and the terminal voltage at the adjacent previous moment is divided by the time interval between the current moment and the adjacent previous moment, and the result is taken as the terminal voltage decay rate of each electrolytic cell at the current moment. The normalized absolute value of the terminal voltage of each electrolytic cell at the current moment is combined with the normalized value of the terminal voltage decay rate into a binary pair. The sequence of binary pairs of all electrolytic cells at the current moment is denoted as the characteristic sequence.

3. The method for stable operation of a seawater hydrogen production system under variable load conditions as described in claim 1, characterized in that, The process of performing Pareto stratification of the electrolytic cell using the non-dominated sorting algorithm is as follows: Electrolytic cells whose terminal voltage decay rate is less than a preset effective decay rate threshold in the feature sequence are selected to construct an effective discharge feature set. By comparing the absolute values ​​of the terminal voltages between different electrolytic cells, it can be determined whether there is a dominant relationship between them. Traverse all electrolytic cells in the effective discharge characteristic set, classify the electrolytic cells without a dominance relationship as the first Pareto front, and classify the remaining electrolytic cells as the secondary Pareto front.

4. The method for stable operation of a seawater hydrogen production system under variable load conditions as described in claim 3, characterized in that, The determination of whether there is a dominance relationship between different electrolytic cells includes: In the effective discharge characteristic set, for electrolytic cell i and electrolytic cell j, if the absolute value of the terminal voltage of electrolytic cell i is less than or equal to the absolute value of the terminal voltage of electrolytic cell j, and the absolute value of the terminal voltage decay rate of electrolytic cell i is greater than or equal to the absolute value of the terminal voltage decay rate of electrolytic cell j, and at least one of these two inequalities has a strict less than or greater than relationship, then it is determined that electrolytic cell i dominates electrolytic cell j.

5. A method for stable operation of a seawater hydrogen production system under variable load conditions as described in claim 3, characterized in that, The generation of the primary backup power supply group and the secondary status monitoring group includes: Obtain the maximum number of backup power output channels and the total number of electrolytic cells in the first Pareto front. If the total number of electrolytic cells is less than or equal to the maximum number of backup power outputs, then the set of all electrolytic cells within the first Pareto front is taken as the primary backup power supply group, and the set of all electrolytic cells within the secondary Pareto front is taken as the secondary status monitoring group. Conversely, the electrolytic cells within the first Pareto front are arranged in ascending order of absolute terminal voltage. The set of electrolytic cells with the maximum number of output channels of the backup power supply in the arrangement result is taken as the primary backup power supply group, and the remaining electrolytic cells are assigned to the secondary status monitoring group.

6. The method for stable operation of a seawater hydrogen production system under variable load conditions as described in claim 1, characterized in that, The process of polling and handing over the power supply status is as follows: When the terminal voltage of any electrolyzer in the primary backup power supply group is greater than or equal to the saturation limit, or when the terminal voltage of any electrolyzer in the secondary status monitoring group is less than or equal to the critical warning limit, the seawater hydrogen production system is controlled to disconnect the electrical connection of all current primary backup power supply groups and return to step S1 to redetermine the primary backup power supply group for the next round, thereby realizing the polling handover of power supply status.

7. A method for stable operation of a seawater hydrogen production system under variable load conditions as described in claim 6, characterized in that, The method for determining the upper limit of saturation is as follows: Electrochemical polarization curves of the electrode plates in the electrolyzer at corresponding concentrations of seawater were obtained to obtain the charging saturation voltage of the electrolyzer, which was then used as the upper limit of saturation.

8. A method for stable operation of a seawater hydrogen production system under variable load conditions as described in claim 6, characterized in that, The method for determining the critical warning upper limit is as follows: Obtain the lower voltage limit to prevent chloride ion corrosion, and the absolute value of the maximum terminal voltage decay rate at the highest historical operating temperature; The approximation margin constant is determined based on the absolute value of the maximum terminal voltage decay rate, the preset sampling period, and the preset safety factor. The sum of the lower voltage limit for preventing chloride ion corrosion and the approximation margin constant is used as the critical warning upper limit.

9. A method for stable operation of a seawater hydrogen production system under variable load conditions as described in claim 8, characterized in that, The approximation margin constant is the product of the absolute value of the maximum terminal voltage decay rate, the preset sampling period, and the preset safety factor.

10. A method for stable operation of a seawater hydrogen production system under variable load conditions as described in claim 1, characterized in that, The process of determining whether the system hibernation protection mechanism is triggered to terminate electrical dispatch is as follows: In real time, determine whether the remaining capacity of the backup battery is less than or equal to the preset extremely low maintenance capacity threshold, or whether the residual gas pressure of the gas-liquid separator is less than or equal to the minimum gas pressure required to drain the seawater; when either condition is met, terminate electrical dispatch.

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