Power balance system and method for quickly starting photovoltaic alkaline hydrogen production system

Abstract

The invention relates to the technical field of hydrogen energy and water electrolysis hydrogen production, in particular to a power balance system and method for rapid starting of a photovoltaic alkaline hydrogen production system, and the method comprises the steps: a starting stage, employing a super capacitor to rapidly preheat an electrolytic cell, applying a small current for pre-activation, and then smoothly loading the current to a rated value; in the operation stage, the power difference between the photovoltaic power and the electrolytic cell is calculated in real time and decomposed into low-frequency and high-frequency components through a low-pass filter. The low-frequency component is distributed to a storage battery and subjected to change rate amplitude limiting processing, so that the power of the storage battery changes smoothly; meanwhile, a compensation instruction of the super capacitor is calculated based on the low-frequency component, the instruction after amplitude limiting and the high-frequency component, and millisecond charging and discharging are carried out through the compensation instruction. Rapid hot start of the alkaline electrolytic cell is achieved, it is ensured that the operating power change rate is always within the safety tolerance range, and the service life of equipment and the reliability of the system are effectively guaranteed.

Description

Technical Field

[0001] This invention relates to the field of hydrogen energy and water electrolysis hydrogen production technology, and in particular to a power balance system and method for rapid start-up of a photovoltaic alkaline hydrogen production system. Background Technology

[0002] While alkaline electrolyzers are a mature and cost-effective technology and one of the mainstream technologies for large-scale green hydrogen production, they still face several technical bottlenecks when applied in off-grid photovoltaic scenarios with severe power fluctuations and no stable power grid support. Their startup process is slow and energy-intensive; cold startup requires external heating to preheat the liquid electrolyte to above 50°C, which is time-consuming and power-intensive, affecting the response speed to intermittent solar energy. Hot standby methods, on the other hand, result in continuous energy consumption for heat preservation. Simultaneously, their dynamic response characteristics are poor, with a narrow power adjustment range and slow response, making it difficult to adapt to the second-level fluctuations in photovoltaic power. This can easily lead to efficiency degradation, electrode and diaphragm damage, accelerated lifespan decay, and even safety risks such as gas cross-contamination due to pressure imbalance. Furthermore, alkaline electrolyzers have extremely high requirements for operational stability; the impact of sudden power changes or interruptions is far greater than that of PEM electrolyzers, requiring highly stable and controllable front-end power supply support.

[0003] Currently, the common solution is to configure large-capacity battery packs for energy buffering and power smoothing. However, this solution has inherent drawbacks: the battery response speed (on the order of seconds) is insufficient to filter out high-frequency fluctuations, and it is difficult to control the rate of power change, which may still impact the alkaline electrolyzer; at the same time, the battery is also difficult to meet the instantaneous high power peak demand required during rapid startup.

[0004] Therefore, existing technologies cannot support the efficient, reliable, and long-life operation of alkaline electrolyzers in off-grid photovoltaic scenarios. Summary of the Invention

[0005] To overcome the above shortcomings, this invention provides a power balancing system and method for rapid startup of a photovoltaic alkaline hydrogen production system. It aims to improve the existing technology where the response speed (second-level) of the battery is insufficient to filter out high-frequency fluctuations and it is difficult to control the power change rate, which may still cause impact on the alkaline electrolyzer. At the same time, the battery is also unable to meet the instantaneous high power peak demand required for rapid startup.

[0006] In a first aspect, the present invention provides the following technical solution: a power balance system for rapid start-up of a photovoltaic alkaline hydrogen production system, the system comprising a photovoltaic power generation unit, a hybrid energy storage unit, an alkaline electrolyzer hydrogen production unit, and a control unit, wherein the hybrid energy storage unit includes a supercapacitor and a battery, the hydrogen production unit includes an alkaline electrolyzer and its thermal management system and a programmable DC power supply, and the system further includes the following modules:

[0007] The startup management and rapid preheating module is used to determine, during the system startup phase, whether the power output of the photovoltaic power generation unit and the state of charge of the supercapacitor meet the preset startup conditions. When the startup conditions are met, the module controls the supercapacitor to provide maximum heating power to the thermal management system to rapidly preheat the electrolyte in the alkaline electrolytic cell.

[0008] The pre-activation control module is used to start the programmable DC power supply when the electrolyte temperature reaches a set temperature threshold, so that the supercapacitor provides an initial small current to the alkaline electrolytic cell.

[0009] A smooth loading control module is used to switch the main power supply of the alkaline electrolyzer from the supercapacitor to the photovoltaic power generation unit and the battery after the internal state of the alkaline electrolyzer has stabilized, and to control the programmable DC power supply to increase the load current of the alkaline electrolyzer to the rated value according to a preset current ramp-up rate.

[0010] The startup completion judgment module is used to complete the startup process and enter the power balance control stage of the system operation phase when the load current of the alkaline electrolyzer reaches the rated value and the electrolyte temperature is stable within the optimal operating range.

[0011] The power difference frequency decomposition module is used to calculate the power difference between the power of the photovoltaic power generation unit and the required power of the alkaline electrolyzer in real time during the system operation phase, and decompose the power difference into low-frequency power components and high-frequency power components through a low-pass filter.

[0012] The battery power management module is used to allocate the low-frequency power component to the battery and to perform rate-of-change limiting processing on the power command allocated to the battery to obtain a smoothly changing actual battery power command.

[0013] The supercapacitor command calculation module is used to calculate the power compensation command of the supercapacitor based on the low-frequency power component, the actual power command of the battery, and the high-frequency power component.

[0014] The power compensation execution module is used to control the supercapacitor to charge and discharge rapidly according to the power compensation command in order to compensate for the power difference and ensure that the power change rate applied to the alkaline electrolytic cell is within its safe tolerance range.

[0015] Preferably, the workflow of the startup management and rapid warm-up module includes:

[0016] After system initialization, receive the startup command;

[0017] The current output power of the photovoltaic power generation unit is detected, and the current state of charge of the supercapacitor is read.

[0018] Determine whether the current output power and the current state of charge are simultaneously higher than their respective preset start-up thresholds;

[0019] If the determination result is yes, then an instruction is sent to the bidirectional DC / DC converter corresponding to the supercapacitor to control the supercapacitor to provide its maximum allowable power to the heater in the thermal management system;

[0020] The temperature of the electrolyte in the alkaline electrolyzer is continuously monitored by temperature sensors in the thermal management system.

[0021] Preferably, the workflow of the pre-activation control module includes:

[0022] The electrolyte temperature information of the alkaline electrolyzer is continuously received and compared with a set temperature threshold. When the electrolyte temperature information has reached the set temperature threshold, a trigger signal is issued.

[0023] In response to the trigger signal, a start command is sent to the programmable DC power supply, and its output current is set to 10% of the rated current of the alkaline electrolyzer.

[0024] The supercapacitor is controlled to provide electrical power corresponding to the initial small current to the programmable DC power supply through its corresponding bidirectional DC / DC converter;

[0025] The initial small current is continuously applied to the alkaline electrolyzer for a predetermined duration to establish a stable electrochemical environment inside the alkaline electrolyzer.

[0026] Preferably, the workflow of the smooth loading control module includes:

[0027] After an initial small current is applied to the alkaline electrolytic cell, the cell voltage and internal pressure of the alkaline electrolytic cell are monitored.

[0028] When the voltage and internal pressure of the cell fluctuate less than a preset range within a predetermined time, it is determined that the internal state of the alkaline electrolytic cell is stable, and the power source of the alkaline electrolytic cell is switched from the supercapacitor to the photovoltaic power generation unit and the battery.

[0029] At the same time, the output current of the programmable DC power supply is controlled to slowly increase from the initial small current to 100% of the rated current at a ramp rate of 1% to 3% of the rated current per second.

[0030] During the output current ramp-up process, the instantaneous power difference caused by photovoltaic power fluctuations is monitored in real time, and the supercapacitor is controlled to charge and discharge rapidly to compensate for the instantaneous power difference, ensuring that the DC bus voltage input to the programmable DC power supply is stable.

[0031] When the output current reaches 100% of the rated current, the smooth loading process is completed.

[0032] Preferably, the workflow of the startup completion determination module includes:

[0033] During the stable loading control process, after the load current of the alkaline electrolytic cell reaches 100% of the rated value, the load current and the electrolyte temperature are continuously monitored.

[0034] When the load current is maintained at 100% of the rated value and the electrolyte temperature is stable within the optimal operating range of 70°C to 90°C for a preset stable duration, the start-up process is considered complete.

[0035] Simultaneously, a startup completion signal is generated, and the startup control process executed by the startup management and rapid preheating module, the pre-activation control module, and the smooth loading control module is terminated;

[0036] Switch the system control mode to power balance control during operation.

[0037] Preferably, the workflow of the power difference frequency decomposition module includes:

[0038] During system operation, the instantaneous output power value of the photovoltaic power generation unit is collected synchronously at a fixed sampling period, and the current power demand value of the alkaline electrolyzer is obtained.

[0039] Calculate the real-time power difference between the instantaneous output power value and the current demand power value;

[0040] The sequence of the real-time power difference is input to a low-pass digital filter with a preset cutoff frequency;

[0041] The low-frequency power component of the real-time power difference is obtained from the output of the low-pass digital filter;

[0042] Subtracting the low-frequency power component from the real-time power difference yields the high-frequency power component of the real-time power difference.

[0043] Preferably, the workflow of the battery power management module includes:

[0044] The low-frequency power component is used as the initial power command for the battery.

[0045] A preset maximum power change rate limit is applied to the initial power command;

[0046] Using the maximum power change rate limit as the slope, the actual battery power command of the previous moment is smoothly transitioned to the initial power command of the current moment, generating the smoothly changing actual battery power command of the current moment.

[0047] The actual power command of the battery is sent to the bidirectional DC / DC converter connected to the battery to control the battery to charge or discharge.

[0048] Preferably, the workflow of the supercapacitor instruction calculation module includes:

[0049] Real-time acquisition of the low-frequency power component, the actual power command of the battery, and the high-frequency power component;

[0050] Calculate the instantaneous power command difference between the low-frequency power component and the actual power command of the battery;

[0051] The instantaneous power command difference is summed with the high-frequency power component to obtain the total power compensation command of the supercapacitor;

[0052] The total power compensation command is sent to the bidirectional DC / DC converter connected to the supercapacitor.

[0053] Preferably, the workflow of the power compensation execution module includes:

[0054] Receive the total power compensation command from the supercapacitor;

[0055] When the value of the total power compensation command is greater than zero, the bidirectional DC / DC converter corresponding to the supercapacitor is controlled so that the supercapacitor absorbs electrical power equal to the command value from the common DC bus connected to the photovoltaic power generation unit, the hybrid energy storage unit and the hydrogen production unit for charging.

[0056] When the value of the total power compensation command is less than zero, the bidirectional DC / DC converter corresponding to the supercapacitor is controlled to discharge the supercapacitor to the common DC bus with an electrical power equal to the absolute value of the command.

[0057] The power difference is offset by the rapid charging and discharging action of the supercapacitor, thus maintaining the voltage stability of the common DC bus.

[0058] Secondly, the present invention provides the following technical solution: a power balance method for rapid start-up of a photovoltaic alkaline hydrogen production system, the method comprising the following steps:

[0059] During the system startup phase, the control unit determines whether the power output of the photovoltaic power generation unit and the state of charge of the supercapacitor meet the preset startup conditions. When the startup conditions are met, the control unit controls the supercapacitor to provide maximum heating power to the thermal management system to rapidly preheat the electrolyte in the alkaline electrolytic cell.

[0060] When the electrolyte temperature reaches the set temperature threshold, the programmable DC power supply is activated, and the supercapacitor provides an initial small current to the alkaline electrolytic cell.

[0061] After the internal state of the alkaline electrolyzer stabilizes, the power supply of the alkaline electrolyzer is switched from the supercapacitor to the photovoltaic power generation unit and the battery, and the programmable DC power supply is controlled to increase the load current of the alkaline electrolyzer to the rated value according to the preset current ramp-up rate.

[0062] When the load current of the alkaline electrolyzer reaches the rated value and the electrolyte temperature stabilizes within the optimal operating range, the startup process is completed, and the system enters the power balance control stage of operation.

[0063] During system operation, the control unit calculates the power difference between the power of the photovoltaic power generation unit and the power demand of the alkaline electrolyzer in real time, and decomposes the power difference into low-frequency power components and high-frequency power components through a low-pass filter.

[0064] The low-frequency power component is allocated to the battery, and the rate of change of the power command allocated to the battery is limited to obtain a smoothly changing actual power command of the battery.

[0065] Based on the low-frequency power component, the actual power command of the battery, and the high-frequency power component, the power compensation command of the supercapacitor is calculated.

[0066] The supercapacitor is controlled to charge and discharge rapidly according to the power compensation command to compensate for the power difference and ensure that the power change rate applied to the alkaline electrolytic cell is within its safe tolerance range.

[0067] The present invention has the following beneficial effects:

[0068] 1. In this invention, rapid heating and low-current pre-activation are achieved through supercapacitors, reducing the cold start time of alkaline electrolyzers from hours to minutes, greatly improving the availability and flexibility of off-grid systems.

[0069] 2. In this invention, by designing a rate-of-change limiting algorithm, it is ensured that the power change that the alkaline electrolyzer can withstand is always within the safe range allowed by its mechanical structure and electrochemical characteristics, fundamentally avoiding damage caused by power mutations and significantly extending its service life.

[0070] 3. In this invention, the supercapacitor undertakes the most demanding power task, allowing the battery to avoid high current and rapid cycle operation. Its configuration capacity and power level can be appropriately reduced, resulting in a better total life cycle cost.

[0071] 4. In this invention, by suppressing high-frequency fluctuations and intelligent power scheduling, alkaline electrolyzers with large inertia can safely and efficiently track the overall trend of photovoltaic power, reduce curtailment, and increase green hydrogen production.

[0072] 5. In this invention, the integrated control strategy can cope with various complex weather conditions and has a safe and orderly shutdown function, which improves the reliability and safety of the entire system. Attached Figure Description

[0073] Figure 1 This is a schematic diagram of the start-up mode control strategy of the power balance system for rapid start-up of a photovoltaic alkaline hydrogen production system proposed in this invention;

[0074] Figure 2 This is a schematic diagram of the overall structure of a power balance system for rapid start-up of a photovoltaic alkaline hydrogen production system proposed in this invention. Detailed Implementation

[0075] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0076] Example 1:

[0077] In a first embodiment of the present invention, a power balance system for rapid start-up of a photovoltaic alkaline hydrogen production system is provided. The system comprises a photovoltaic power generation unit, a hybrid energy storage unit, an alkaline electrolyzer hydrogen production unit, and a control unit. The hybrid energy storage unit includes a supercapacitor and a battery. The hydrogen production unit includes an alkaline electrolyzer, its thermal management system, and a programmable DC power supply. Figures 1-2 As shown, the system also includes the following modules:

[0078] The startup management and rapid preheating module is used to determine whether the power output of the photovoltaic power generation unit and the state of charge of the supercapacitor meet the preset startup conditions during the system startup phase. When the startup conditions are met, the supercapacitor is controlled to provide maximum heating power to the thermal management system to rapidly preheat the electrolyte in the alkaline electrolyzer.

[0079] Furthermore, the workflow for starting the management and rapid warm-up module includes:

[0080] After system initialization, receive the startup command;

[0081] Detect the current output power of the photovoltaic power generation unit and read the current state of charge of the supercapacitor;

[0082] Determine whether the current output power and the current state of charge are both higher than their respective preset start-up thresholds;

[0083] If the judgment result is yes, then a command is sent to the bidirectional DC / DC converter corresponding to the supercapacitor to control the supercapacitor to provide its maximum allowable power to the heater in the thermal management system.

[0084] The electrolyte temperature in the alkaline electrolyzer is continuously monitored by temperature sensors in the thermal management system.

[0085] Specifically, after the system is powered on and initialized, the control unit (in this embodiment, an industrial programmable logic controller (PLC) enters standby mode and continuously monitors the system status. When the operator issues a system start command through the human-machine interface, or when the system meets the preset automatic start conditions, the control unit begins to execute the following judgment and control sequence. Specifically, the control unit collects the DC output voltage and current of the photovoltaic power generation unit in real time through its analog input module, calculates the current photovoltaic output power, and reads the current state of charge value reported by the supercapacitor management system through the communication bus (such as CAN bus). The control unit compares the current photovoltaic output power read above with a preset photovoltaic power start threshold, and compares the current state of charge of the supercapacitor with a preset SOC start threshold. Only when the current photovoltaic output power is higher than its start threshold and the state of charge of the supercapacitor is higher than its SOC start threshold, does the control unit determine that all start conditions are met and immediately enter the rapid preheating stage. If any condition is not met, the system will remain in standby or report an error and wait for the conditions to be met.

[0086] Once the startup conditions are met, the control unit sends an enable and power command to the bidirectional DC / DC converter connected to the supercapacitor via its digital output module or a specific communication protocol. This command controls the bidirectional DC / DC converter to operate in buck mode, converting the high voltage on the common DC bus to a voltage level suitable for the heater in the thermal management system. Simultaneously, the control unit instructs the converter to output its maximum allowable power to the heater. During this stage, the supercapacitor, as the sole energy source, provides instantaneous high power to the heater with its high power density and rapid discharge capability, achieving rapid heating of the electrolyte. During the rapid preheating process, the control unit continuously collects signals from the temperature sensor installed in the electrolyte circulation pipeline of the alkaline electrolytic cell via its analog input module, monitoring the electrolyte temperature in real time. The control unit compares the monitored real-time temperature with a preset first set temperature (50°C in this embodiment). When the electrolyte temperature reaches or exceeds the first set temperature, the core task of the startup management and rapid preheating module is completed. The control unit generates an internal flag signal or triggers an interrupt, marking the end of the "rapid preheating stage" and transferring process control to the subsequent pre-activation control module.

[0087] Through the above process, the supercapacitor in the hybrid energy storage is used to prioritize providing the maximum heating power to the electrolyzer after the energy conditions are met, thereby rapidly preheating it from a cold state to a temperature suitable for electrochemical activation, laying the foundation for the minute-level rapid start-up of the entire system.

[0088] The pre-activation control module is used to start the programmable DC power supply when the electrolyte temperature reaches the set temperature threshold, and the supercapacitor provides an initial small current to the alkaline electrolyzer.

[0089] Furthermore, the workflow of the pre-activation control module includes:

[0090] It continuously receives electrolyte temperature information from the alkaline electrolyzer and compares it with a set temperature threshold. When the electrolyte temperature information has reached the set temperature threshold, it sends a trigger signal.

[0091] In response to the trigger signal, a start command is sent to the programmable DC power supply, and its output current is set to 10% of the rated current of the alkaline electrolyzer.

[0092] The supercapacitor is controlled to provide electrical power corresponding to the initial small current to the programmable DC power supply through its corresponding bidirectional DC / DC converter;

[0093] The initial small current is continuously applied to the alkaline electrolyzer for a predetermined time to establish a stable electrochemical environment inside the alkaline electrolyzer.

[0094] Specifically, the control unit continuously receives signals from the temperature sensor in the electrolyte circulation pipeline. These signals are converted from analog to digital via an analog input module and read in real time. The internal program of the control unit cyclically compares the read temperature value with a preset temperature threshold (i.e., the aforementioned first set temperature, 50°C in this embodiment). Once the electrolyte temperature reaches or exceeds this threshold, the control unit generates an internal trigger signal, marking the official end of the rapid preheating phase and activating the execution logic of this pre-activated control module. In response to the trigger signal, the control unit immediately sends a series of instructions to the programmable DC power supply that powers the alkaline electrolyzer via its communication interface (such as Modbus TCP / IP or Ethernet). These instructions include a start instruction (enabling the DC power supply to prepare its output circuit), a working mode setting instruction (setting it to constant current mode), and a current value setting instruction. Specifically, the current setting command sets the output current to a low initial small current, which is set as a fixed percentage of the rated current of the alkaline electrolyzer, preferably 10%. For a system with a rated current corresponding to a power of 1.5MW and an operating voltage range, the power corresponding to this initial small current is approximately 165kW. While setting the programmable DC power supply, the control unit needs to coordinate the hybrid energy storage unit to provide energy for this initial small current. The control unit sends a new power command to the bidirectional DC / DC converter connected to the supercapacitor, instructing it to switch from the previous mode of fully powering the heater to outputting a stable power to the common DC bus that matches the aforementioned initial small current (165kW), so as to ensure that the input voltage of the programmable DC power supply is stable, thereby enabling accurate output of the set current value. At this stage, the supercapacitor remains the main energy source.

[0095] After an initial small current is applied to the alkaline electrolyzer, the system enters a brief pre-activation phase. The control unit starts an internal timer and maintains the current small current state for a predetermined duration, approximately 1 minute. During this process, the control unit monitors the cell voltage of the electrolyzer to ensure it is within a stable range corresponding to the small current. The purpose of this process is to establish a preliminary dynamic equilibrium for ion migration in the electrolyte, bubble nucleation and detachment on the electrode surface, and the chemical environment near the diaphragm before loading a large current, thereby activating the electrochemical system inside the electrolyzer and preparing for the subsequent smooth loading of a large current. When the predetermined duration is reached, the control unit determines that the small current pre-activation phase is complete. Subsequently, it generates a new internal status flag and prepares to transfer control to the next stage of the smooth loading control module.

[0096] Through the above process, the system adds an electrochemical pre-activation step on the basis of thermal preheating. By pre-energizing with low current and short time, the damage that may be caused to the electrodes and diaphragm by the cold-state high current impact is greatly avoided, ensuring that the start-up process is both fast and safe.

[0097] The smooth loading control module is used to switch the main power supply of the alkaline electrolyzer from the supercapacitor to the photovoltaic power generation unit and the battery after the internal state of the alkaline electrolyzer has stabilized, and to control the programmable DC power supply to increase the load current of the alkaline electrolyzer to the rated value according to the preset current ramp-up rate.

[0098] Furthermore, the workflow for smoothly loading the control module includes:

[0099] After an initial small current is applied to the alkaline electrolytic cell, the cell voltage and internal pressure of the alkaline electrolytic cell are monitored.

[0100] When the cell voltage and internal pressure fluctuate less than the preset range within a predetermined time, it is determined that the internal state of the alkaline electrolytic cell is stable, and the power supply source of the alkaline electrolytic cell is switched from the supercapacitor to the photovoltaic power generation unit and the battery.

[0101] At the same time, the output current of the programmable DC power supply is controlled to slowly increase from an initial small current to 100% of the rated current at a ramp rate of 1% to 3% of the rated current per second.

[0102] During the output current ramp-up process, the instantaneous power difference caused by photovoltaic power fluctuations is monitored in real time, and the supercapacitor is controlled to charge and discharge rapidly to compensate for the instantaneous power difference, ensuring the stability of the DC bus voltage input to the programmable DC power supply.

[0103] When the output current reaches 100% of the rated current, the smooth loading process is completed.

[0104] Specifically, after an initial small current (e.g., 10% of the rated current) is continuously applied to the alkaline electrolyzer for a predetermined duration, the control unit begins monitoring key parameters characterizing the electrochemical and physical states inside the electrolyzer. Specifically, the control unit continuously acquires the cell voltage signal across the alkaline electrolyzer via its analog input module. Simultaneously, it acquires the internal pressure signal of the electrolyzer system via a pressure sensor. The control unit's internal program calculates the fluctuation range (e.g., standard deviation or peak-to-peak value) of these parameters within a predetermined time period (e.g., 30 seconds). When the fluctuation amplitudes of both the cell voltage and internal pressure are less than their respective preset stability threshold ranges, the control unit determines that the internal state of the alkaline electrolyzer has stabilized and is suitable for load loading. This determination is a safety prerequisite for subsequent loading operations. If the internal state is determined to be stable, the control unit immediately executes two parallel operations. One is that the control unit begins adjusting the power output structure of the hybrid energy storage unit, which refers to… The system gradually reduces the output power of the bidirectional DC / DC converter corresponding to the supercapacitor. At the same time, it instructs the bidirectional DC / DC converter corresponding to the battery to start replacing the supercapacitor and work with the photovoltaic power generation unit as the main power source of the system, providing a continuously increasing load power to the electrolyzer. This process is a smooth transition rather than an instantaneous switch to avoid impacting the power grid (the DC bus in this case). Secondly, the control unit sends a new instruction to the programmable DC power supply through the communication interface to set the ramp rate of its output current. This rate is set within a slow range, preferably 1% to 3% of the rated current per second. For example, for a system with a rated current of 1000A, if the ramp rate is set to 1% / second, the current will increase at a slope of 10A / second. After receiving the instruction, the power supply starts from the current initial small current value (such as 100A) and linearly increases its output current according to the set slope.

[0105] During the current ramp-up process, the power balance on the common DC bus is affected by fluctuations in photovoltaic power generation (on the order of seconds or minutes) and the dynamic switching of power supply entities. To ensure that the current applied to the electrolyzer strictly follows the preset smooth ramp, the control unit performs the following real-time compensation: The control unit calculates the instantaneous power difference between the photovoltaic output power and the electrolyzer's required power (i.e., the instantaneous input power of the programmable power supply). This instantaneous power difference is rapidly compensated by the supercapacitor at the millisecond level. When there is excess power, the control unit absorbs the excess power; when there is a power shortage, the control unit... The power is released to supplement the voltage. This dynamic compensation mechanism ensures that the voltage of the common DC bus is highly stable, thereby providing a high-quality power input for the programmable DC power supply. This enables the programmable DC power supply to accurately execute the slow current ramp-up command, avoiding sudden changes in the current of the electrolyzer due to bus voltage fluctuations. The control unit continuously monitors the actual current value output by the programmable DC power supply. When the current value reaches 100% of the rated current of the alkaline electrolyzer, the control unit determines that the smooth loading process is complete. It then terminates the current ramp-up command, allowing the system to operate stably under rated conditions, and prepares to transfer control to the final start-up completion judgment module.

[0106] Through the above process, the system achieves smooth and controlled loading of the load current of the alkaline electrolyzer, and isolates the direct impact of front-end power fluctuations on the electrolyzer through real-time compensation by supercapacitors, fundamentally avoiding power surges and ensuring the safety of the startup process and the long-term operating life of the electrolyzer.

[0107] The startup completion judgment module is used to complete the startup process and enter the power balance control stage when the load current of the alkaline electrolyzer reaches the rated value and the electrolyte temperature is stable within the optimal operating range.

[0108] Furthermore, the workflow of the completion judgment module includes:

[0109] After the load current of the alkaline electrolyzer reaches 100% of the rated value during the stable loading control process, the load current and electrolyte temperature are continuously monitored.

[0110] When the load current is maintained at 100% of the rated value and the electrolyte temperature is stable within the optimal operating range of 70°C to 90°C for a preset stable duration, the start-up process is considered complete.

[0111] Simultaneously, a startup completion signal is generated, and the startup control process executed by the startup management and rapid warm-up module, the pre-activation control module, and the smooth loading control module is terminated;

[0112] Switch the system control mode to power balance control during operation.

[0113] Specifically, after the smooth loading control module increases the load current of the alkaline electrolyzer to 100% of its rated value, the startup completion judgment module is activated. The control unit then begins to continuously monitor and judge key parameters indicating that the system has entered a stable operating state. These parameters include the load current and the electrolyte temperature. The load current is confirmed by the actual output current value fed back from the programmable DC power supply to ensure that it is stably maintained at 100% of the rated current value and that its fluctuation range is within the allowable error band. The electrolyte temperature is continuously read from the temperature sensor in the thermal management system. The control unit applies a comprehensive judgment logic to the above monitoring data to confirm whether the startup process has been successfully completed. The logic must simultaneously meet the following three conditions and maintain a preset stable duration (preferably 5 minutes). Condition 1 is that the load current is stable at 100% of the rated value. Condition 2 is that the electrolyte temperature reaches and stabilizes within its optimal operating range. For alkaline electrolyzers, this optimal operating range is defined as 70℃ to 90℃. Preferably, the system can set a target value, such as 85℃, and allow fluctuations within ±5℃. Condition 3 is that the above two states (full load current and suitable temperature) must be maintained simultaneously and maintained for a preset stable duration (e.g., 5 minutes). The introduction of duration judgment is to avoid misjudgment due to the instantaneous attainment of parameters and to ensure that the system has truly entered a thermodynamic and electrochemical stable state.

[0114] Once the control unit determines that all the above-mentioned start-up completion conditions have been met, it performs the following operations: it sets a start-up completion status flag inside the system, which can be used to update the display status of the human-machine interface and record the system operation log. The control unit calls the program to terminate all start-up stage-specific control logic carried by the start-up management and rapid preheating module, the pre-activation control module, and the smooth loading control module. For example, it stops the power output control of the heater and exits the current ramp-up mode. The control unit switches its core control algorithm from the start-up sequence to the power fluctuation balancing and safety protection mode designed for long-term operation. Subsequently, the system will no longer execute the special start-up-related processes, but will begin to execute the control strategies of the operation stage as described in the claims, such as power difference calculation, frequency decomposition, and hybrid energy storage power allocation, in order to cope with the fluctuation of photovoltaic power.

[0115] Through the above process, the system achieves a smooth and uninterrupted transition from startup to operation. By comprehensively judging multiple parameters and duration, it ensures that the alkaline electrolyzer is put into full-load operation only after it has fully reached thermal and electrical steady state, thereby ensuring equipment safety and officially starting the efficient and long-life hydrogen production operation phase.

[0116] The power difference frequency decomposition module is used to calculate the power difference between the power of the photovoltaic power generation unit and the power demand of the alkaline electrolyzer in real time during the system operation phase, and decompose the power difference into low-frequency power components and high-frequency power components through a low-pass filter.

[0117] Furthermore, the workflow of the power difference frequency decomposition module includes:

[0118] During system operation, the instantaneous output power value of the photovoltaic power generation unit is collected synchronously at a fixed sampling period, and the current power demand value of the alkaline electrolyzer is obtained.

[0119] Calculate the real-time power difference between the instantaneous output power value and the current demand power value;

[0120] The sequence of real-time power difference is input to a low-pass digital filter with a preset cutoff frequency.

[0121] Obtain the low-frequency power component of the real-time power difference from the output of the low-pass digital filter;

[0122] Subtracting the low-frequency power component from the real-time power difference yields the high-frequency power component of the real-time power difference.

[0123] Specifically, after the system enters the operation phase, the control unit synchronously performs the following data acquisition operation at a fixed sampling period (e.g., 100 milliseconds), wherein it acquires the output voltage of the DC side of the photovoltaic power generation unit through its analog input module. With output current The instantaneous output power value of the photovoltaic power generation unit is calculated in real time. Simultaneously, obtain the current power requirement value of the alkaline electrolyzer. This value is determined by the operating state of the programmable DC power supply. In constant current operation mode, it can be considered as a slowly changing or constant setpoint. The control unit calculates the real-time power difference of the system at each sampling time k. The calculation follows the formula:

[0124] ;

[0125] in, A value greater than 0 indicates that the system has excess power, which needs to be absorbed by energy storage units or discarded. <0 indicates a power deficit in the system, which needs to be supplemented by energy storage units;

[0126] To separate the slow trend of power change, the real-time power difference sequence is... The input is fed to a low-pass digital filter with a preset cutoff frequency. In a preferred embodiment of the present invention, a first-order low-pass infinite impulse response filter is used, and its discrete-time domain recursive calculation formula is as follows:

[0127] ;

[0128] in, It is the low-frequency power component output at the current time k. It is the low-frequency power component value of k-1 at the previous moment. These are filter coefficients, which are constants between 0 and 1, and their values ​​are determined by the desired cutoff frequency. and sampling period Joint decision;

[0129] in addition, The cutoff frequency is preferably set to 0.1Hz (time constant of about 1.6 seconds) to effectively separate the power fluctuation trend from the second to the minute level;

[0130] The output of the filter This represents the slowly changing base or DC component of the power difference, whose inertia is suitable for tracking by a battery. By subtracting its low-frequency component from the original power difference, all the fast, abrupt fluctuations, i.e., the high-frequency power components, can be obtained. The calculation is as follows:

[0131] ;

[0132] This component It contains all the fluctuation components above the cutoff frequency, and its changes are drastic, requiring processing by supercapacitors with extremely fast response speeds;

[0133] Through the above process, the system can decompose complex power fluctuations into two orthogonal components: low frequency and high frequency. This provides a precise input basis for the subsequent implementation of optimized energy storage allocation strategies, such as batteries handling low frequencies and supercapacitors handling high frequencies, thus providing the foundation for the efficient and safe operation of the entire power balance system.

[0134] The battery power management module is used to allocate low-frequency power components to the battery and to perform rate-of-change limiting processing on the power commands allocated to the battery to obtain a smoothly changing actual battery power command.

[0135] Furthermore, the workflow of the battery power management module includes:

[0136] Use the low-frequency power component as the initial power command for the battery.

[0137] A preset maximum power change rate limit is imposed on the initial power command;

[0138] Using the maximum power change rate limit as the slope, the battery actual power command of the previous moment is smoothly transitioned to the initial power command of the current moment, generating the battery actual power command that changes smoothly at the current moment.

[0139] The actual power command of the battery is sent to the bidirectional DC / DC converter connected to the battery to control the battery to charge or discharge.

[0140] Specifically, the control unit will receive the low-frequency power component from the power difference frequency decomposition module. Directly used as the initial power command for the battery. ,Right now: , among which, when When >0, it indicates an instruction to charge the battery (absorb excess power). When <0, it indicates that the battery is being instructed to discharge (to replenish the power deficit).

[0141] To prevent sudden changes in the initial power command from impacting the downstream electrolytic cell, the control unit... Apply a preset maximum power change rate limit This limit value is set based on the safety tolerance of the alkaline electrolyzer. In one embodiment of the present invention, It is set to ±2% / second to ±5% / second of the system's rated power; for example, for a 1.5MW system, The value range is ±30kW / s to ±75kW / s;

[0142] The control unit calculates the actual battery power command based on the previous control cycle. Initial power command for the current cycle and the maximum rate of change The smoothing instruction for the current cycle is calculated using a limiting function. The mathematical description of this process is as follows:

[0143] , × ), - × );

[0144] in, , The structure ensures that the amount of variation in power command is limited to Within the range;

[0145] This ensures that, regardless of How to perform a step jump, and what is the final output? They are all based on This is a signal with the maximum slope, smoothly transitioning from the previous time value. For example, if the initial command suddenly requests the battery to discharge 100kW, but after limiting, the actual command may only increase by 45kW compared to the previous time (assuming...). ), and gradually approached 100kW in subsequent cycles;

[0146] The control unit will calculate the smoothly varying actual power command of the battery. The command is sent to a bidirectional DC / DC converter connected to the battery via a communication bus (such as a CAN bus). After receiving the command, the converter controls its power electronic switching devices to precisely adjust its output / input power, so that the battery can charge or discharge according to this smooth command.

[0147] Through the above process, it is ensured that the battery always transmits and receives power at a smooth rate, protecting the battery itself and avoiding high-current charging and discharging. More importantly, it makes the power changes from the battery channel to the alkaline electrolyzer extremely slow and gentle, fundamentally avoiding safety risks such as electrode damage and gas cross-contamination that may be caused by sudden power command changes, thus ensuring the long life and safe operation of the electrolyzer.

[0148] The supercapacitor command calculation module is used to calculate the power compensation command of the supercapacitor based on the low-frequency power component, the actual power command of the battery, and the high-frequency power component.

[0149] Furthermore, the workflow of the supercapacitor instruction calculation module includes:

[0150] Real-time acquisition of low-frequency power components, actual battery power commands, and high-frequency power components;

[0151] Calculate the instantaneous power command difference between the low-frequency power component and the actual power command of the battery;

[0152] The total power compensation command of the supercapacitor is obtained by summing the instantaneous power command difference with the high-frequency power component.

[0153] The total power compensation command is sent to the bidirectional DC / DC converter connected to the supercapacitor.

[0154] Specifically, in each control cycle, the control unit acquires three key input variables from the upstream module in real time, including the low-frequency power component from the power difference frequency decomposition module. This represents a slow trend in power change, derived from the actual battery power command from the battery power management module. This is a smoothly varying power command after rate of change limiting, also originating from the high-frequency power component of the power difference frequency decomposition module. This represents the rapid fluctuation in power due to the battery's power command. It is to slowly track low-frequency components. During the dynamic process, there is an instantaneous difference between the two, and the control unit calculates this instantaneous power command difference. :

[0155] ;

[0156] The difference This quantifies the portion of low-frequency power that the battery "failed to provide or absorb in a timely manner" due to its limited response speed at the current moment. For example, when During a sudden step jump, Unable to keep up immediately A non-zero value will appear immediately;

[0157] The control unit will calculate the instantaneous power command difference as described above. With all high-frequency fluctuation components Summing yields the final total power compensation command that the supercapacitor needs to handle. The calculation formula is as follows:

[0158] ;

[0159] Expanding the formula gives:

[0160] ;

[0161] This formula indicates that supercapacitors need to compensate for two parts of power simultaneously, specifically including the instantaneous power deficit or excess caused by battery inertia. ), all the original high-frequency power fluctuations ( );

[0162] The control unit will calculate the total power compensation command. The signal is transmitted via a high-speed communication interface or a dedicated analog output channel to a bidirectional DC / DC converter connected to the supercapacitor. This converter, based on the received command, controls the supercapacitor to perform precise charging within microseconds to milliseconds. >0) or discharge ( <0), to instantly fill the system power gap;

[0163] Through the above process, the response delay of the battery and its inherent high-frequency fluctuations can be transformed into the specific task of the supercapacitor, accurately and quickly offsetting all power differences that are not immediately balanced by the battery, thereby jointly ensuring that the rate of power change applied to the electrolyzer is strictly limited within a safe range.

[0164] The power compensation execution module is used to control the supercapacitor to charge and discharge rapidly according to the power compensation command in order to compensate for the power difference and ensure that the power change rate applied to the alkaline electrolyzer is within its safe tolerance range.

[0165] Furthermore, the workflow of the power compensation execution module includes:

[0166] Receive total power compensation command from the supercapacitor;

[0167] When the total power compensation command value is greater than zero, the bidirectional DC / DC converter corresponding to the supercapacitor is controlled so that the supercapacitor absorbs electrical power equal to the command value from the common DC bus connected to the photovoltaic power generation unit, the hybrid energy storage unit and the hydrogen production unit for charging.

[0168] When the total power compensation command value is less than zero, control the bidirectional DC / DC converter corresponding to the supercapacitor to discharge the supercapacitor to the common DC bus with an electrical power equal to the absolute value of the command value.

[0169] The rapid charging and discharging of the supercapacitor offsets the power difference and maintains the voltage stability of the common DC bus.

[0170] Specifically, the control unit receives total power compensation commands in real time from the supercapacitor command calculation module. This command is a signed power value, the sign and magnitude of which directly determine the direction and intensity of the supercapacitor's operation. The control unit then... The value sends precise control commands to the bidirectional DC / DC converter connected to the supercapacitor, when When the value is greater than 0, it indicates that the system has instantaneous power excess. The control unit instructs the bidirectional DC / DC converter to operate in buck charging mode. This converter draws power from the common DC bus by controlling the duty cycle of its power switches (such as IGBTs or MOSFETs). It delivers an equal amount of electrical power and stores the electrical energy in a supercapacitor bank. This action is equivalent to adding an instantaneous load to the bus and absorbing the excess energy.

[0171] when When the voltage is less than 0, it indicates a momentary power deficit in the system. The control unit instructs the bidirectional DC / DC converter to operate in boost discharge mode. This converter controls the supercapacitor bank to release its stored energy and inject it into the common DC bus by boosting the voltage. With equal electrical power, this action is equivalent to adding an instantaneous generator on the bus to fill the power gap. With its inherent millisecond-level or even faster response speed, the supercapacitor performs the above charging or discharging operation after receiving the converter command. This rapid power throughput can offset the total system power difference ΔP caused by photovoltaic fluctuations and battery response lag in real time and accurately.

[0172] Through the rapid compensation of the supercapacitor, the voltage of the common DC bus is maintained within an extremely stable and narrow range. The programmable DC power supply draws power from this stable DC bus, so its input voltage is stable, and it can supply power to the alkaline electrolyzer according to its set value. This ensures that, although the front-end photovoltaic power may fluctuate drastically, the current / power curve actually applied to the alkaline electrolyzer is smooth and the rate of change is controlled. Its power change rate is strictly limited to the range that the electrolyzer can safely tolerate, as defined by the current ramp-up rate of the programmable DC power supply.

[0173] Through the above process, the control algorithm can be ultimately transformed into a direct protection effect on the electrolyzer, ensuring that the alkaline electrolyzer can achieve efficient, safe and long-life operation in the highly volatile off-grid photovoltaic power environment.

[0174] Example 2:

[0175] Currently, a common solution is to configure large-capacity battery banks for energy buffering and power smoothing. However, this solution has inherent drawbacks: the battery response speed (on the order of seconds) is insufficient to filter out high-frequency fluctuations, and it is difficult to control the power change rate, which may still impact the alkaline electrolyzer; at the same time, the battery cannot meet the instantaneous high-power peak demand required for rapid startup. To solve the above problems, this invention provides a power balancing method for rapid startup of a photovoltaic alkaline hydrogen production system, the structure of which is as follows: Figures 1-2 As shown. The specific implementation process of this method is as follows:

[0176] During the system startup phase, the control unit determines whether the power output of the photovoltaic power generation unit and the state of charge of the supercapacitor meet the preset startup conditions. When the startup conditions are met, the control unit controls the supercapacitor to provide maximum heating power to the thermal management system to rapidly preheat the electrolyte in the alkaline electrolytic cell.

[0177] When the electrolyte temperature reaches the set temperature threshold, the programmable DC power supply is activated, and an initial small current is provided to the alkaline electrolytic cell by the supercapacitor.

[0178] After the internal state of the alkaline electrolyzer stabilizes, the main power supply of the alkaline electrolyzer is switched from the supercapacitor to the photovoltaic power generation unit and the battery, and the programmable DC power supply is controlled to increase the load current of the alkaline electrolyzer to the rated value according to the preset current ramp-up rate.

[0179] When the load current of the alkaline electrolyzer reaches the rated value and the electrolyte temperature stabilizes within the optimal operating range, the startup process is completed, and the system enters the power balance control stage of operation.

[0180] During system operation, the control unit calculates the power difference between the power of the photovoltaic power generation unit and the power demand of the alkaline electrolyzer in real time, and decomposes the power difference into low-frequency power components and high-frequency power components through a low-pass filter.

[0181] The low-frequency power component is allocated to the battery, and the rate of change of the power command allocated to the battery is limited to obtain a smooth-changing actual power command of the battery.

[0182] Based on the low-frequency power component, the actual power command of the battery, and the high-frequency power component, the power compensation command of the supercapacitor is calculated.

[0183] The supercapacitor is controlled to charge and discharge rapidly according to the power compensation command to compensate for the power difference and ensure that the power change rate applied to the alkaline electrolyzer is within its safe tolerance range.

[0184] Specifically, after the system is powered on and initialized, the control unit receives the start command. The control unit first detects the current output power of the photovoltaic power generation unit and reads the current state of charge of the supercapacitor. The power value and state of charge value are compared with their respective preset start thresholds. In an embodiment of a 1.5MW system, the available photovoltaic power is required to exceed 450kW, and the SOC of the supercapacitor is required to be higher than 80%. If the above conditions are met at the same time, the control unit determines that the start conditions are met and immediately enters the rapid preheating process. The control unit instructs the supercapacitor to provide its maximum allowable power (e.g., 150kW) to the heater in the thermal management system of the alkaline electrolyzer through its corresponding bidirectional DC / DC converter. During this stage, the supercapacitor acts as the only energy source to rapidly heat the electrolyte. The control unit continuously monitors the electrolyte temperature through a temperature sensor.

[0185] When the electrolyte temperature reaches the first set temperature (e.g., 50°C), the control unit activates the programmable DC power supply to power the electrolyzer and sets its output current to an initial small current, which is 10% to 15% (e.g., 10%) of the electrolyzer's rated current. The power required for this small current is still provided by the supercapacitor. This small current state is maintained for a predetermined duration (e.g., 1 minute) to establish a stable electrochemical environment inside the electrolyzer and avoid cold shocks during subsequent high current loading. After the initial small current is applied and the electrolyzer's cell voltage, internal pressure, and other parameters tend to stabilize, the control unit begins to smoothly switch the power supply from the supercapacitor to the photovoltaic power generation unit and battery. At the same time, the control unit instructs the programmable DC power supply to slowly increase its output current at a preset current ramp-up rate (e.g., 1% to 3% of the rated current per second). During this current ramp-up process, the supercapacitor continuously compensates for the instantaneous power difference caused by small fluctuations in photovoltaic power, ensuring that the current curve applied to the electrolyzer is strictly smooth. The thermal management system continues to operate until the electrolyte temperature rises to the optimal operating range (e.g., 70°C to 90°C).

[0186] When the control unit detects that the load current of the alkaline electrolyzer reaches 100% of the rated value, and the electrolyte temperature stabilizes within the optimal operating range for a preset stable duration (e.g., 2 minutes), the startup process is deemed complete. Subsequently, the system automatically exits the startup control logic and enters the following operating phase: power balance control. The control unit calculates the system power difference ΔP in real time with a fixed sampling period (e.g., 100ms), where ΔP = ,in, This represents the current photovoltaic power generation capacity. To determine the current power requirement of the alkaline electrolyzer, the real-time power difference ΔP is decomposed using a low-pass digital filter (such as a first-order IIR filter with a cutoff frequency of 0.1Hz), and the low-frequency power component is obtained from the filter output. This represents a slow trend in power change, calculated... High-frequency power components are obtained. This represents a sudden and violent fluctuation in power;

[0187] Low-frequency power components The power command allocated to the battery is initially processed by limiting the rate of change of the power command allocated to the battery, and a maximum power change rate threshold is set. This ensures that, regardless of How it changes ultimately affects the power command applied to the battery. They are all based on The signal represents the maximum slope and a smooth change.

[0188] Calculate the power compensation command for the supercapacitor The instruction consists of two parts, including the instantaneous power instruction difference caused by battery power limiting. ) and all high-frequency fluctuation components ( Therefore, the total power compensation command for the supercapacitor is:

[0189] ;

[0190] Control the supercapacitor according to The command enables millisecond-level rapid charging and discharging. Charge when >0. <Discharge at 0), accurately compensate for all power differences that are not immediately responded to by the battery;

[0191] Through the aforementioned coordinated control, although photovoltaic power Despite constant fluctuations, the hybrid energy storage system (batteries and supercapacitors) together maintains the stability of the common DC bus voltage. The alkaline electrolyzer is powered by a programmable DC power supply from this stable bus, so its actual operating power / current change rate is strictly limited within a safe range, fundamentally avoiding power surges and ensuring the safe operation and service life of the electrolyzer.

[0192] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A power balancing system for rapid start-up of a photovoltaic alkaline hydrogen production system, characterized in that, The system comprises a photovoltaic power generation unit, a hybrid energy storage unit, an alkaline electrolyzer hydrogen production unit, and a control unit. The hybrid energy storage unit includes a supercapacitor and a battery. The hydrogen production unit includes an alkaline electrolyzer, its thermal management system, and a programmable DC power supply. The system also includes the following modules: The startup management and rapid preheating module is used to determine, during the system startup phase, whether the power output of the photovoltaic power generation unit and the state of charge of the supercapacitor meet the preset startup conditions. When the startup conditions are met, the module controls the supercapacitor to provide maximum heating power to the thermal management system to rapidly preheat the electrolyte in the alkaline electrolytic cell. The pre-activation control module is used to start the programmable DC power supply when the electrolyte temperature reaches a set temperature threshold, so that the supercapacitor provides an initial small current to the alkaline electrolytic cell. A smooth loading control module is used to switch the main power supply of the alkaline electrolyzer from the supercapacitor to the photovoltaic power generation unit and the battery after the internal state of the alkaline electrolyzer has stabilized, and to control the programmable DC power supply to increase the load current of the alkaline electrolyzer to the rated value according to a preset current ramp-up rate. The startup completion judgment module is used to complete the startup process and enter the power balance control stage of the system operation phase when the load current of the alkaline electrolyzer reaches the rated value and the electrolyte temperature is stable within the optimal operating range. The power difference frequency decomposition module is used to calculate the power difference between the power of the photovoltaic power generation unit and the required power of the alkaline electrolyzer in real time during the system operation phase, and decompose the power difference into low-frequency power components and high-frequency power components through a low-pass filter. The battery power management module is used to allocate the low-frequency power component to the battery and to perform rate-of-change limiting processing on the power command allocated to the battery to obtain a smoothly changing actual battery power command. The supercapacitor command calculation module is used to calculate the power compensation command of the supercapacitor based on the low-frequency power component, the actual power command of the battery, and the high-frequency power component. The power compensation execution module is used to control the supercapacitor to charge and discharge rapidly according to the power compensation command in order to compensate for the power difference and ensure that the power change rate applied to the alkaline electrolytic cell is within its safe tolerance range.

2. The power balance system for rapid start-up of a photovoltaic alkaline hydrogen production system according to claim 1, characterized in that, The workflow of the startup management and rapid warm-up module includes: After system initialization, receive the startup command; The current output power of the photovoltaic power generation unit is detected, and the current state of charge of the supercapacitor is read. Determine whether the current output power and the current state of charge are simultaneously higher than their respective preset start-up thresholds; If the determination result is yes, then an instruction is sent to the bidirectional DC / DC converter corresponding to the supercapacitor to control the supercapacitor to provide its maximum allowable power to the heater in the thermal management system; The temperature of the electrolyte in the alkaline electrolyzer is continuously monitored by temperature sensors in the thermal management system.

3. The power balance system for rapid start-up of a photovoltaic alkaline hydrogen production system according to claim 2, characterized in that, The workflow of the pre-activation control module includes: The electrolyte temperature information of the alkaline electrolyzer is continuously received and compared with a set temperature threshold. When the electrolyte temperature information has reached the set temperature threshold, a trigger signal is issued. In response to the trigger signal, a start command is sent to the programmable DC power supply, and its output current is set to 10% of the rated current of the alkaline electrolyzer. The supercapacitor is controlled to provide electrical power corresponding to the initial small current to the programmable DC power supply through its corresponding bidirectional DC / DC converter; The initial small current is continuously applied to the alkaline electrolyzer for a predetermined duration to establish a stable electrochemical environment inside the alkaline electrolyzer.

4. The power balance system for rapid start-up of a photovoltaic alkaline hydrogen production system according to claim 1, characterized in that, The workflow of the smooth loading control module includes: After an initial small current is applied to the alkaline electrolytic cell, the cell voltage and internal pressure of the alkaline electrolytic cell are monitored. When the voltage and internal pressure of the cell fluctuate less than a preset range within a predetermined time, it is determined that the internal state of the alkaline electrolytic cell is stable, and the power source of the alkaline electrolytic cell is switched from the supercapacitor to the photovoltaic power generation unit and the battery. At the same time, the output current of the programmable DC power supply is controlled to slowly increase from the initial small current to 100% of the rated current at a ramp rate of 1% to 3% of the rated current per second. During the output current ramp-up process, the instantaneous power difference caused by photovoltaic power fluctuations is monitored in real time, and the supercapacitor is controlled to charge and discharge rapidly to compensate for the instantaneous power difference, ensuring that the DC bus voltage input to the programmable DC power supply is stable. When the output current reaches 100% of the rated current, the smooth loading process is completed.

5. The power balance system for rapid start-up of a photovoltaic alkaline hydrogen production system according to claim 4, characterized in that, The workflow of the startup completion determination module includes: During the stable loading control process, after the load current of the alkaline electrolytic cell reaches 100% of the rated value, the load current and the electrolyte temperature are continuously monitored. When the load current is maintained at 100% of the rated value and the electrolyte temperature is stable within the optimal operating range of 70°C to 90°C for a preset stable duration, the start-up process is considered complete. Simultaneously, a startup completion signal is generated, and the startup control process executed by the startup management and rapid preheating module, the pre-activation control module, and the smooth loading control module is terminated; Switch the system control mode to power balance control during operation.

6. The power balance system for rapid start-up of a photovoltaic alkaline hydrogen production system according to claim 1, characterized in that, The workflow of the power difference frequency decomposition module includes: During system operation, the instantaneous output power value of the photovoltaic power generation unit is collected synchronously at a fixed sampling period, and the current power demand value of the alkaline electrolyzer is obtained. Calculate the real-time power difference between the instantaneous output power value and the current demand power value; The sequence of the real-time power difference is input to a low-pass digital filter with a preset cutoff frequency; The low-frequency power component of the real-time power difference is obtained from the output of the low-pass digital filter; Subtracting the low-frequency power component from the real-time power difference yields the high-frequency power component of the real-time power difference.

7. The power balance system for rapid start-up of a photovoltaic alkaline hydrogen production system according to claim 1, characterized in that, The workflow of the battery power management module includes: The low-frequency power component is used as the initial power command for the battery. A preset maximum power change rate limit is applied to the initial power command; Using the maximum power change rate limit as the slope, the actual battery power command of the previous moment is smoothly transitioned to the initial power command of the current moment, generating the smoothly changing actual battery power command of the current moment. The actual power command of the battery is sent to the bidirectional DC / DC converter connected to the battery to control the battery to charge or discharge.

8. The power balance system for rapid start-up of a photovoltaic alkaline hydrogen production system according to claim 1, characterized in that, The workflow of the supercapacitor instruction calculation module includes: Real-time acquisition of the low-frequency power component, the actual power command of the battery, and the high-frequency power component; Calculate the instantaneous power command difference between the low-frequency power component and the actual power command of the battery; The instantaneous power command difference is summed with the high-frequency power component to obtain the total power compensation command of the supercapacitor; The total power compensation command is sent to the bidirectional DC / DC converter connected to the supercapacitor.

9. A power balance system for rapid start-up of a photovoltaic alkaline hydrogen production system according to claim 8, characterized in that, The workflow of the power compensation execution module includes: Receive the total power compensation command from the supercapacitor; When the value of the total power compensation command is greater than zero, the bidirectional DC / DC converter corresponding to the supercapacitor is controlled so that the supercapacitor absorbs electrical power equal to the command value from the common DC bus connected to the photovoltaic power generation unit, the hybrid energy storage unit and the hydrogen production unit for charging. When the value of the total power compensation command is less than zero, the bidirectional DC / DC converter corresponding to the supercapacitor is controlled to discharge the supercapacitor to the common DC bus with an electrical power equal to the absolute value of the command. The power difference is offset by the rapid charging and discharging action of the supercapacitor, thus maintaining the voltage stability of the common DC bus.

10. A power balance method for rapid start-up of a photovoltaic alkaline hydrogen production system, characterized in that, A power balancing system for rapid start-up of a photovoltaic alkaline hydrogen production system according to any one of claims 1-9, the method comprising the following steps: During the system startup phase, the control unit determines whether the power output of the photovoltaic power generation unit and the state of charge of the supercapacitor meet the preset startup conditions. When the startup conditions are met, the control unit controls the supercapacitor to provide maximum heating power to the thermal management system to rapidly preheat the electrolyte in the alkaline electrolytic cell. When the electrolyte temperature reaches the set temperature threshold, the programmable DC power supply is activated, and the supercapacitor provides an initial small current to the alkaline electrolytic cell. After the internal state of the alkaline electrolyzer stabilizes, the power supply of the alkaline electrolyzer is switched from the supercapacitor to the photovoltaic power generation unit and the battery, and the programmable DC power supply is controlled to increase the load current of the alkaline electrolyzer to the rated value according to the preset current ramp-up rate. When the load current of the alkaline electrolyzer reaches the rated value and the electrolyte temperature stabilizes within the optimal operating range, the startup process is completed, and the system enters the power balance control stage of operation. During system operation, the control unit calculates the power difference between the power of the photovoltaic power generation unit and the power demand of the alkaline electrolyzer in real time, and decomposes the power difference into low-frequency power components and high-frequency power components through a low-pass filter. The low-frequency power component is allocated to the battery, and the rate of change of the power command allocated to the battery is limited to obtain a smoothly changing actual power command of the battery. Based on the low-frequency power component, the actual power command of the battery, and the high-frequency power component, the power compensation command of the supercapacitor is calculated. The supercapacitor is controlled to charge and discharge rapidly according to the power compensation command to compensate for the power difference and ensure that the power change rate applied to the alkaline electrolytic cell is within its safe tolerance range.

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