Alternate control method and system for running state of composite electrolytic cell cluster

Abstract

The invention discloses an alternating control method and system for the running state of a composite electrolytic cell cluster, and the method comprises the steps: firstly converting electric power into direct current through a converter by employing a photovoltaic power generation and wind power generation system, transmitting the direct current into a system direct current bus, and carrying out the hydrogen production according to the load range, starting time, hydrogen production efficiency and other running characteristics of an electrolytic cell during the hydrogen production of the electrolytic cell cluster; and dividing the hydrogen production power of the electrolytic cell into a plurality of operation state intervals. According to the input power level of wind and light power generation, the total power is divided into different working conditions in a stepped mode, the operation state of the electrolytic cell is dynamically adjusted according to the current power requirement, electric power in a direct-current bus is flexibly allocated to an electrolytic cell cluster through a DC / DC converter, and cooperative power distribution between a proton exchange membrane electrolytic cell and an alkaline electrolytic cell is ensured. Based on the difference between advantages and disadvantages, a matching mechanism of the operation state and different electrolytic bath types is planned, and the load of each electrolytic bath is balanced through state alternation, so that the dynamic operation stability of the whole system is enhanced and the hydrogen production efficiency is improved.

Description

Technical Field

[0001] The present application relates to the technical field of energy hydrogen production, and in particular to a method and system for controlling the rotation of operating states of a composite electrolyzer cluster. Background Art

[0002] With the growing global demand for clean energy and the introduction of carbon neutrality goals, hydrogen, as a recognized clean and efficient energy carrier, plays a vital role in promoting green and sustainable development. In this context, the electrolysis of water to produce hydrogen using renewable energy has attracted much attention because it can significantly reduce carbon emissions in the hydrogen production process and is one of the important ways to achieve green hydrogen production.

[0003] At present, alkaline electrolyzer (AEL) and proton exchange membrane electrolyzer (PEMEL) are the two most widely used technologies in the field of hydrogen production by water electrolysis. AEL is known for its low cost and simple operation, but its long startup time and relatively slow response speed make it difficult to effectively cope with power fluctuations caused by unstable energy sources such as wind and solar energy; in contrast, PEMEL is known for its fast dynamic response capability and good adaptability to fluctuating power supply characteristics, and performs well in application scenarios combined with renewable energy.

[0004] However, in actual application, the operation characteristics of different types of electrolyzers are not fully considered to reasonably allocate power, resulting in unsatisfactory results of hydrogen production from multiple types of electrolyzers, and the problem of unstable wind and solar power output cannot be solved efficiently. Therefore, how to reasonably utilize the respective advantages of AEL and PEMEL, and optimize electrolysis efficiency, extend equipment service life, and reduce failure rate through refined control strategies has become one of the problems that people in this field need to solve. Summary of the invention

[0005] The purpose of this application is to provide a method and system for controlling the rotation of the operating status of a composite electrolyzer cluster in order to overcome the existing technical defects. Based on the operating characteristics of the electrolyzer, an electrolyzer operating status matching mechanism is set up under complex working conditions, and the load of each electrolyzer is balanced through state rotation, ultimately achieving enhanced dynamic operating stability and improved hydrogen production efficiency of the entire system.

[0006] The purpose of this application is achieved through the following technical solutions:

[0007] In a first aspect, the present application proposes a method for controlling the rotation of the operation status of a composite electrolyzer cluster, the method comprising:

[0008] Utilize photovoltaic power generation system and wind power generation system to convert electric power into direct current through converter and send it into system DC bus;

[0009] When hydrogen is produced by an electrolyzer cluster, the electrolyzers are divided into multiple operating states according to the operating power of the electrolyzers, and the electrolyzer cluster includes multiple proton exchange membrane electrolyzers and multiple alkaline electrolyzers;

[0010] According to the level of wind and solar input power, the total power is divided into multiple working conditions according to the output steps;

[0011] Based on the current power demand, the operating status of the electrolyzer is rotated dynamically according to the operating conditions. The power in the system DC bus is dynamically allocated to the electrolyzer cluster through the DC / DC converter to complete the coordinated power distribution of the proton exchange membrane electrolyzer and the alkaline electrolyzer.

[0012] In a possible implementation manner, the operating state includes a rated state, an optimal state, a fluctuation state, an overload state, a standby state, and a shutdown state;

[0013] Under rated conditions, the electrolyzer operates at the set rated power;

[0014] Under the optimal condition, the optimal operating power of the electrolyzer is set at 50% of the rated power;

[0015] Under the fluctuation state, the electrolyzer operates in an elastic fluctuation range from minimum power to overload power;

[0016] In the overload state, the power of the electrolyzer when operating exceeds the rated power, reaching 110% to 130% of the rated power;

[0017] In standby mode, the system stops producing hydrogen and consumes electricity to maintain the temperature and pressure of the electrolyzer.

[0018] In the shutdown state, the electrolytic cell is closed and cooled, and current will not flow into the electrolytic cell.

[0019] In a possible implementation, the fluctuation state only exists in the proton exchange membrane electrolyzer, the alkaline electrolyzer operates in the standby state with priority over the proton exchange membrane electrolyzer, and the proton exchange membrane electrolyzer operates in the overload state with priority over the alkaline electrolyzer.

[0020] In a possible implementation manner, the operating conditions include an overload operating condition, an optimal operating condition, a standby operating condition, and a low power operating condition, and the method further includes:

[0021] Under overload conditions, the total power of the electrolyzer exceeds the rated sum of the electrolyzers. At this time, the electrolyzers operate in the overload state, rated state, and fluctuation state. Except for the proton exchange membrane electrolyzers operating in the fluctuation state, all electrolyzers operate in the rated state. If the wind and solar power cannot be fully absorbed, the electrolyzers are successively upgraded to the overload state until the input power is fully absorbed.

[0022] Under optimal operating conditions, the electrolyzer operates in the optimal state; under standby conditions, the electrolyzer operates in the standby state; under low-power conditions, the electrolyzer operates in the shutdown state. If the electrolyzer does not fully absorb the input power in the optimal state, standby state and shutdown state, the electrolyzer will be upgraded to the rated state, optimal state, and standby state until the wind and solar power are fully absorbed.

[0023] In a possible implementation, based on the current power demand, the step of dynamically rotating the operating state of the electrolyzer according to the operating conditions includes:

[0024] Step S1: Collect the electrolytic cell number k and the total renewable energy power P to be absorbed. total And the total rated power P of the electrolyzer el ;

[0025] Step S2: Determine P total Is it greater than (n+N-1)P o +P e If it is greater than, execute step S3; if it is not greater than, execute step S6;

[0026] Step S3: Determine P total Is it greater than (n+N-1)P e +σP e If it is greater than, execute step S4; if it is not greater than, execute step S5;

[0027] Step S4, determining whether the overload power number of the electrolytic cell is maximized, if so, rotating the state of the electrolytic cell according to the rotation strategy, if not, converting the kth electrolytic cell from the rated state to the overload state, and executing the conversion of the rated state to the overload state for the next electrolytic cell when it is determined that the overload power number of the electrolytic cell is not maximized next time, until the overload power number of the electrolytic cell is maximized;

[0028] Step S5, determining whether the rated power of the electrolytic cell is maximized, if so, rotating the state of the electrolytic cell according to the rotation strategy, if not, converting the kth electrolytic cell from the optimal state to the overload state, and executing the optimal state conversion to the overload state for the next electrolytic cell when it is determined that the overload power number of the electrolytic cell is not maximized next time, until the overload power number of the electrolytic cell is maximized;

[0029] Step S6: Determine P total Is it greater than (n+N-1)Ps +P e If it is greater than, execute step S7; if it is not greater than, execute step S8;

[0030] Step S7, judging whether the optimal power of the electrolytic cell is maximized, if so, rotating the state of the electrolytic cell according to the rotation strategy, if not, converting the standby state of the kth electrolytic cell to the optimal state, and executing the standby state conversion to the optimal state for the next electrolytic cell when it is judged that the overload power number of the electrolytic cell is not maximized next time, until the overload power number of the electrolytic cell is maximized;

[0031] Step S8, determine whether the standby power number of the electrolytic cell is maximized. If so, rotate the state of the electrolytic cell according to the rotation strategy. If not, the kth electrolytic cell is converted from the shutdown state to the standby state. When it is determined next time that the overload power number of the electrolytic cell is not maximized, the next electrolytic cell is converted from the shutdown state to the standby state until the overload power number of the electrolytic cell is maximized.

[0032] In a possible implementation, the rotation strategy includes:

[0033] Set a time period T, which is less than the safe power operation time of hydrogen production;

[0034] After each cycle T, the operating states of multiple proton exchange membrane electrolyzers and multiple alkaline electrolyzers are changed in turn, the operating state of the next electrolyzer inherits the operating state of the previous electrolyzer, the first electrolyzer inherits the operating state of the last electrolyzer, and the standby state is rotated among the multiple alkaline electrolyzers, and the fluctuation state is rotated among the multiple proton exchange membrane electrolyzers.

[0035] In a second aspect, the present application proposes a composite electrolytic cell cluster operation state rotation control system, the system comprising:

[0036] Photovoltaic power generation system and wind power generation system, used to convert electricity into direct current through converters;

[0037] clusters of electrolyzers to convert electricity into hydrogen;

[0038] DC / DC converter is used to adjust voltage and current and distribute electricity according to hydrogen production load demand.

[0039] In one possible embodiment, the electrolyzer cluster includes a plurality of proton exchange membrane electrolyzers and a plurality of alkaline electrolyzers.

[0040] The above-mentioned main scheme of the present application and its further options can be freely combined to form multiple schemes, all of which are schemes that can be adopted and claimed for protection in the present application; and in the present application, (non-conflicting options) options and other options can also be freely combined. After understanding the scheme of the present application, those skilled in the art can understand that there are multiple combinations based on the prior art and common knowledge, all of which are technical schemes to be protected by the present application, and they are not exhaustively listed here.

[0041] The present application discloses a method and system for controlling the rotation of the operation state of a composite electrolyzer cluster. First, photovoltaic power generation and wind power generation systems are used to convert electricity into direct current through converters and send it to the system DC bus. When the electrolyzer cluster produces hydrogen, the hydrogen production power of the electrolyzer is divided into multiple operation state intervals according to the operation characteristics of the electrolyzer such as the load range, startup time and hydrogen production efficiency. According to the input power level of wind and solar power generation, the total power is divided into different working conditions in steps. According to the current power demand, the operation state of the electrolyzer is dynamically adjusted, and the power in the DC bus is flexibly allocated to the electrolyzer cluster through the DC / DC converter to ensure the coordinated power distribution between the proton exchange membrane electrolyzer and the alkaline electrolyzer. Based on the difference in the advantages and disadvantages of the two, a matching mechanism for the operation state and different types of electrolyzers is planned. The load of each electrolyzer is balanced through state rotation, so as to realize the enhancement of the dynamic operation stability and the improvement of hydrogen production efficiency of the whole system. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0043] Figure 1 A schematic diagram of a composite electrolytic cell cluster operating state rotation control system proposed in an embodiment of the present application is shown.

[0044] Figure 2 A schematic flow chart of a method for controlling the rotation of operating states of a composite electrolytic cell cluster proposed in an embodiment of the present application is shown.

[0045] Figure 3a The hydrogen production efficiency curve of the PEMEL electrolyzer proposed in the embodiment of the present application at different input powers is shown.

[0046] Figure 3b The hydrogen production efficiency curve of the AEL electrolyzer proposed in the embodiment of the present application at different input powers is shown.

[0047] Figure 4A schematic diagram showing the transition between each operating mode proposed in the embodiment of the present application is shown.

[0048] Figure 5 A schematic diagram of electrolytic cell distribution proposed in an embodiment of the present application is shown.

[0049] Figure 6 A schematic diagram of the dynamic adjustment strategy proposed in an embodiment of the present application is shown.

[0050] Figure 7 A schematic diagram of the rotation operation proposed in an embodiment of the present application is shown.

[0051] Figure 8 A schematic diagram of the wind and photovoltaic power output of wind turbines and photovoltaic generators throughout the year is shown.

[0052] Fig. 9 A schematic diagram showing the discrete degree of rated operating time under the traditional sequential start-stop method and the compound rotation method is shown.

[0053] Fig.10 A schematic diagram showing the hydrogen production of an electrolyzer cell in a composite rotation mode. DETAILED DESCRIPTION

[0054] The following describes the embodiments of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. The present application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0055] Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making any creative work shall fall within the scope of protection of this application.

[0056] In the existing technology, there are multiple types of electrolyzers mixed for hydrogen production, and the operating characteristics of different types of electrolyzers are not fully considered for power allocation, which cannot reasonably and effectively deal with the instability of wind and solar power output.

[0057] Therefore, in order to solve the above-mentioned technical problems, an embodiment of the present application proposes a method for controlling the rotation of the operating status of a composite electrolyzer cluster, which can set an electrolyzer operating status matching mechanism and a status rotation strategy under complex working conditions based on the operating characteristics of different electrolyzers to achieve enhanced dynamic operating stability and improved hydrogen production efficiency of the wind and solar power generation hydrogen production system, which is described in detail below.

[0058] Please refer to Figure 1 , Figure 1A schematic diagram of a composite electrolytic cell cluster operation state rotation control system proposed in an embodiment of the present application is shown, and the system includes:

[0059] Photovoltaic power generation system and wind power generation system, used to convert electricity into direct current through converters;

[0060] Proton exchange membrane electrolyzers and alkaline electrolyzers for converting electricity into hydrogen;

[0061] DC / DC converter is used to adjust voltage and current and distribute electricity according to hydrogen production load demand.

[0062] Photovoltaic power generation systems and wind power generation systems use solar energy and wind energy to generate electricity, convert the generated AC power into DC power through converters, and connect to the busbar of the system for subsequent use. Proton exchange membrane electrolyzers (PEMEL) and alkaline electrolyzers (AEL) are the core equipment for hydrogen production, which convert electrical energy into hydrogen energy. Among them, proton exchange membrane electrolyzers have the characteristics of fast response and high efficiency, and are suitable for handling power inputs with large fluctuations, while alkaline electrolyzers have a long startup time but low cost, and are suitable for stable power inputs. This application realizes coordinated power distribution between the two electrolyzers through a multi-state rotation control strategy to ensure efficient operation of the system under various working conditions.

[0063] The DC / DC converter is used to adjust the voltage and current, and adjust the DC power from different sources to the voltage and current level suitable for the operation of the electrolyzer, so that the power can be reasonably distributed according to the hydrogen production load demand, ensuring the effective transmission and utilization of power. The system bus connects all power generation sources and power consumption equipment, ensuring the smooth flow of power between different components and supporting the stable operation of the system.

[0064] Figure 2 A schematic flow chart of a method for controlling the rotation of the operation status of a composite electrolytic cell cluster proposed in an embodiment of the present application is shown. The method is applied to the above-mentioned system, and includes:

[0065] Step a: Utilize the photovoltaic power generation system and the wind power generation system to convert the electric power into direct current through the converter and send it into the system direct current bus.

[0066] Photovoltaic power generation systems and wind power generation systems convert solar energy and wind energy into electrical energy respectively. Photovoltaic power generation systems directly generate direct current, while the alternating current generated by wind power generation systems needs to be converted into direct current through an AC / DC converter. The converted direct current is adjusted in voltage and current by a DC / DC converter to meet system requirements before being connected to the system's DC bus. The DC bus connects various electrical devices, including electrolyzer clusters.

[0067] Step b: when the electrolyzer cluster produces hydrogen, the electrolyzers are divided into multiple operating states according to the operating power of the electrolyzers.

[0068] The electrolyzer cluster includes a plurality of proton exchange membrane electrolyzers and a plurality of alkaline electrolyzers.

[0069] In the process of hydrogen production by electrolyzer clusters, in order to optimize the operating efficiency and stability of the system, proton exchange membrane electrolyzers and alkaline electrolyzers are divided into multiple operating states according to different operating power requirements. Each type of electrolyzer performs differently under different operating states due to its different characteristics. By real-time monitoring of power input and hydrogen production demand, the control system will automatically select the most suitable operating state. For the different characteristics of proton exchange membrane electrolyzers and alkaline electrolyzers, the system can optimize their operating strategies respectively, so that the electrolyzers can be flexibly switched under different operating states, which not only ensures the efficient operation of the system, but also extends the service life of the equipment.

[0070] The operating status includes rated status, optimal status, fluctuation status, overload status, standby status and shutdown status;

[0071] Under rated conditions, the electrolyzer operates at the set rated power;

[0072] Under the optimal condition, the optimal operating power of the electrolyzer is set at 50% of the rated power;

[0073] Under the fluctuation state, the electrolyzer operates in an elastic fluctuation range from minimum power to overload power;

[0074] In the overload state, the power of the electrolyzer when operating exceeds the rated power, reaching 110% to 130% of the rated power;

[0075] In standby mode, the system stops producing hydrogen and consumes electricity to maintain the temperature and pressure of the electrolyzer.

[0076] In the shutdown state, the electrolytic cell is closed and cooled, and current will not flow into the electrolytic cell.

[0077] The fluctuation state only exists in the proton exchange membrane electrolyzers of the electrolyzer cluster. The alkaline electrolyzers give priority to the proton exchange membrane electrolyzers and operate in the standby state, and the proton exchange membrane electrolyzers give priority to the alkaline electrolyzers and operate in the overload state.

[0078] Combining the different characteristics of proton exchange membrane electrolyzers and alkaline electrolyzers, the electrolyzers are divided into multiple states according to the operating power during the hydrogen production process. Under the rated state, the electrolyzer works stably, safely and efficiently under the rated power. Under the optimal state, in order to ensure high electrolysis efficiency and reduce the probability of shutdown and improve the adjustment sensitivity, the optimal operating power is set constant at 50% of the rated power. Figure 3a and Figure 3bThe hydrogen production efficiency curves of the PEMEL electrolyzer and AEL electrolyzer proposed in the embodiments of the present application at different input powers are shown respectively. The results show that with the increase of input power, the hydrogen production efficiency increases rapidly. When the input power is close to 0.2pu, the hydrogen production efficiency reaches a peak value and then slowly decreases. Specifically, with the rated power of the electrolyzer as a reference, the electrolysis efficiency is highest when the input power of the electrolyzer is 19%. However, when the input power of the electrolyzer is adjusted to 50% of the rated power, the purity of hydrogen in oxygen will reach the upper limit of the safe operation of the hydrogen production system in 2 hours. Therefore, it is necessary to comprehensively consider the hydrogen production efficiency, operational safety and hydrogen production of the electrolyzer to determine the optimal operating power of the electrolyzer.

[0079] In the fluctuating state, the electrolyzer can adapt to the fluctuations in the output power of renewable energy sources such as wind power and photovoltaics, and can operate flexibly in the range of its minimum power to overload power. It is worth noting that the fluctuating state only exists in proton exchange membrane electrolyzers; in the overload state, the rated power is exceeded for a short time, up to 110%-130% of the rated power. In addition, the overload power is stipulated to be σ (1.26) times the rated power; in the standby state, the system suspends hydrogen production, but still needs to consume electrical energy to maintain a specific temperature and pressure in the electrolyzer (set to 2% of the rated power) so that it can be restarted quickly; in the shutdown state, the electrolyzer is closed and gradually cooled, and current will not flow into the electrolyzer.

[0080] The operation and scheduling process of hydrogen production by electrolyzer can be divided into three modes: standby, idle and production. Among them, fluctuating operation, rated operation, optimal operation and overload operation can be uniformly classified as production mode (NO); standby operation is classified as standby mode (STB); shutdown operation is idle mode (OFF). The relationship between each variable and power is as follows: At the same time, only one of the three modes can be satisfied, so: The transition time between different modes is represented by binary variables as startup interval (Y) and shutdown interval (Z). Figure 4 A schematic diagram showing the transition between each operating mode proposed in the embodiment of the present application is shown.

[0081] Based on the above relationship between electrolyzer power and hydrogen production, the resulting input-output correlation is combined with the binary variables of different operating mode switching to calculate the hydrogen production in each state. t , which means the transition from standby mode to production mode in a continuous time interval, and the linearized function of hydrogen production rate can be expressed as: W t Need to meet Among them, A1 and A2 are the electrolyzer power-hydrogen production rate characteristic parameters respectively; A3 is the penalty coefficient for hydrogen production from standby to production state; is the electrolytic power of the electrolytic cell at time t, in kW; PS is the standby power, in kW; is the hydrogen production rate of the electrolyzer at time t.

[0082] Step c: According to the level of wind and solar input power, the total power is divided into multiple working conditions according to the output steps.

[0083] The operating conditions include overload conditions, optimal conditions, standby conditions, and low power conditions. The method further includes:

[0084] Under overload conditions, the total power of the electrolyzer exceeds the rated sum of the electrolyzers. At this time, the electrolyzers operate in the overload state, rated state, and fluctuation state. Except for the proton exchange membrane electrolyzers operating in the fluctuation state, all electrolyzers operate in the rated state. If the wind and solar power cannot be fully absorbed, the electrolyzers are successively upgraded to the overload state until the input power is fully absorbed.

[0085] Under optimal operating conditions, the electrolyzer operates in the optimal state; under standby conditions, the electrolyzer operates in the standby state; under low-power conditions, the electrolyzer operates in the shutdown state. If the electrolyzer does not fully absorb the input power in the optimal state, standby state and shutdown state, the electrolyzer will be upgraded to the rated state, optimal state, and standby state until the wind and solar power are fully absorbed.

[0086] First, set 5 thresholds from small to large: 0, (n+N-1)P s +P e (threshold 1), (n+N-1)P o +P e (Threshold 2), (n+N-1)P e +σP e (Threshold 3),σP el (Threshold 4), which is divided into four operating conditions, including overload condition, optimal condition, standby condition, and low power condition. Threshold 0 is defined as the lowest limit, indicating the situation when the total input power is insufficient for any electrolyzer to work effectively. Threshold 1 marks the transition point from low power condition to standby condition. Before this, most electrolyzers may be in shutdown or low power state, and only some electrolyzers maintain the minimum necessary power. Threshold 2 marks the transition point from standby condition to optimal condition. At this time, as the input power increases, more electrolyzers begin to enter the optimal efficiency operation mode. Threshold 3 marks the transition point from optimal condition to rated condition. When the input power is further increased, all working electrolyzers will reach their rated power as much as possible. Threshold 4 marks the transition point from rated condition to overload condition, which means that the input power exceeds the sum of the rated powers of all electrolyzers, and some electrolyzers need to enter the overload state to handle the excess energy.

[0087] If all electrolyzers are operating at rated conditions but have not yet fully absorbed the wind and solar output power, check whether more electrolyzers can be brought to an overload state until demand is met or the maximum allowable overload capacity is reached. If only some electrolyzers can operate at rated conditions, the rest should be adjusted to the optimal power state as much as possible to ensure efficiency while being as close to the rated power as possible. When wind and solar fluctuations result in low input power, priority should be given to keeping as many electrolyzers as possible in the optimal power state, while the rest remain in standby or fluctuating states, which can reduce unnecessary energy waste while ensuring a certain output. In order to ensure a quick response to higher power inputs that may occur in the future, AEL-type electrolyzers should be maintained in standby mode rather than completely shut down so that they are ready to accept new work tasks at any time.

[0088] In order to ensure that the system can flexibly respond to different power levels, maximize the use of renewable energy, and ensure the safety and stability of the system, the real-time monitoring data of wind and solar input power is used to divide the working conditions. The proton exchange membrane electrolyzer operates in three states: overload, rated, and fluctuating. The fluctuating state only exists in the PEM electrolyzer cluster to adapt to the rapid changes in wind and solar power. The alkaline electrolyzer maintains the rated state. If it still cannot fully absorb the wind and solar power, some PEM electrolyzers will be raised to the overload state in turn until the input power is fully absorbed.

[0089] Figure 5 The schematic diagram of electrolyzer allocation proposed in the embodiment of the present application is shown. Different levels of working conditions will allocate multi-state electrolyzer operation. Under overload conditions, the total power of the electrolyzer will exceed its rated sum. At this time, the electrolyzer operates in three states: overload, rated, and fluctuating. Except for the PEM electrolyzer operating in the fluctuating state, the rest of the electrolyzers operate in the rated state. If the wind and solar power cannot be fully absorbed, the electrolyzers will be upgraded to the overload state in sequence until the input power is fully absorbed. Under optimal working conditions, standby working conditions, and low-power working conditions, the electrolyzers will all operate in the optimal state, standby state, and shutdown state. The excess power will gradually upgrade the electrolyzers to the rated state, optimal state, and standby state until the wind and solar power are fully absorbed.

[0090] Step d: Based on the current power demand, the operating status of the electrolyzer is rotated dynamically according to the working conditions, and the power in the system DC bus is dynamically allocated to the electrolyzer cluster through the DC / DC converter to complete the coordinated power distribution of the proton exchange membrane electrolyzer and the alkaline electrolyzer.

[0091] The dynamic adjustment strategy proposed in the embodiment of the present application is to dynamically allocate the power in the system DC bus to the electrolyzer cluster through a DC / DC converter, ensuring that under different operating conditions, PEMEL and AEL can efficiently and flexibly respond to changes in wind and solar input power.

[0092] Figure 6 A schematic diagram of a dynamic adjustment strategy proposed in an embodiment of the present application is shown, and the steps of rotating the operating state of the electrolyzer according to the working conditions dynamically based on the current power demand include:

[0093] Step S1: Collect the electrolytic cell number k and the total renewable energy power P to be absorbed. total And the total rated power P of the electrolyzer el ;

[0094] Step S2: Determine P total Is it greater than (n+N-1)P o +P e If it is greater than, execute step S3; if it is not greater than, execute step S6;

[0095] Step S3: Determine P total Is it greater than (n+N-1)P e +σP e If it is greater than, execute step S4; if it is not greater than, execute step S5;

[0096] Step S4, determining whether the overload power number of the electrolytic cell is maximized, if so, rotating the state of the electrolytic cell according to the rotation strategy, if not, converting the kth electrolytic cell from the rated state to the overload state, and executing the conversion of the rated state to the overload state for the next electrolytic cell when it is determined that the overload power number of the electrolytic cell is not maximized next time, until the overload power number of the electrolytic cell is maximized;

[0097] Step S5, determining whether the rated power of the electrolytic cell is maximized, if so, rotating the state of the electrolytic cell according to the rotation strategy, if not, converting the kth electrolytic cell from the optimal state to the overload state, and executing the optimal state conversion to the overload state for the next electrolytic cell when it is determined that the overload power number of the electrolytic cell is not maximized next time, until the overload power number of the electrolytic cell is maximized;

[0098] Step S6: Determine P total Is it greater than (n+N-1)P s +P e If it is greater than, execute step S7; if it is not greater than, execute step S8;

[0099] Step S7, judging whether the optimal power of the electrolytic cell is maximized, if so, rotating the state of the electrolytic cell according to the rotation strategy, if not, converting the standby state of the kth electrolytic cell to the optimal state, and executing the standby state conversion to the optimal state for the next electrolytic cell when it is judged that the overload power number of the electrolytic cell is not maximized next time, until the overload power number of the electrolytic cell is maximized;

[0100] Step S8, determine whether the standby power number of the electrolytic cell is maximized. If so, rotate the state of the electrolytic cell according to the rotation strategy. If not, the kth electrolytic cell is converted from the shutdown state to the standby state. When it is determined next time that the overload power number of the electrolytic cell is not maximized, the next electrolytic cell is converted from the shutdown state to the standby state until the overload power number of the electrolytic cell is maximized.

[0101] P total is the total power of renewable energy to be absorbed, P e is the rated power of the electrolyzer, P el is the total rated power of the electrolyzer, P s is the standby power of the electrolyzer, P o is the optimal power of the electrolyzer, P b is the power during fluctuating operation, σ is the overload factor, n is the number of AELs; N is the number of PEMELs.

[0102] When setting the threshold ((n+N-1)P o +P e 、(n+N-1)P e +σP e 、(n+N-1)P s +P e ,σP el , 0) and then collect the electrolytic cell number k and the total renewable energy power P to be consumed total And the total rated power P of the electrolyzer el In P total >(n+N-1)P s +P e , and satisfy (n+N-1)P e +σP e <P total <σP el When the overload condition is met, the electrolyzers are all running at rated conditions, but the wind and solar output power is not fully absorbed. Determine whether the overload power of the electrolyzer is maximized. If the condition is not met, P el ,k=σP e (k is the serial number of the electrolytic cell) The rated power of the electrolytic cell gradually increases until it is overloaded, and the overload power number of the electrolytic cell is continued to be maximized. If it is not maximized yet, the state of the next electrolytic cell is switched, and so on, until the overload power number of the electrolytic cell is maximized, and the conditions are met, then rotation is performed.

[0103] In P total >(n+N-1)P s +P e , and satisfy (n+N-1)P o +P e <P total ≤(n+N-1)P e+σP e When the optimal working condition is met, in addition, the number of electrolyzers in the rated state is less than N+n-1, and the power is not enough for all electrolyzers to operate at rated power, some electrolyzers will operate at the optimal power state. It is necessary to determine whether the rated power of the electrolyzer is maximized. If the condition is not met, execute P el,k =P e , the optimal power of the electrolyzer gradually increases to the rated power, and rotation is carried out if the conditions are met.

[0104] When P total <(n+N-1)P s +P e And (n+N-1)P s +P e <P total ≤(n+N-1)P o +P e When the low power condition is met, the wind and solar input power is low, and the electrolyzers are generally in the rated state, which will cause a large area of ​​electrolyzers to stagnate. Therefore, the electrolyzers are maximized in the optimal power state of low power and high efficiency, and the remaining electrolyzers are in standby and fluctuating states. It is necessary to determine whether the optimal power number of the electrolyzer is maximized. If the condition is not met, P el,k =P o , the standby power of the electrolyzer gradually increases to the optimal power, and rotation is carried out when the conditions are met.

[0105] When P total <(n+N-1)P s +P e And 0≤P total ≤(n+N-1)P s +P e When the standby condition is met, in order to ensure that the electrolyzer can be restarted quickly, the alkaline electrolyzer will be operated in the standby state first. At this time, it is necessary to determine whether the standby power of the electrolyzer is maximized. If the condition is not met, P el,k =P s , the electrolyzer is shut down and gradually increases to standby power, and if the conditions are met, it is rotated. The operating state of the electrolyzer can be effectively adjusted dynamically according to different working conditions to ensure the efficient use of power resources and the safe and stable operation of the equipment.

[0106] Rotation strategies include:

[0107] Set a time period T, which is less than the safe power operation time of hydrogen production;

[0108] After each cycle T, the operating states of multiple proton exchange membrane electrolyzers and multiple alkaline electrolyzers are changed in turn, the operating state of the next electrolyzer inherits the operating state of the previous electrolyzer, the first electrolyzer inherits the operating state of the last electrolyzer, and the standby state is rotated among the multiple alkaline electrolyzers, and the fluctuation state is rotated among the multiple proton exchange membrane electrolyzers.

[0109] Figure 7 The schematic diagram of the rotation operation proposed in the embodiment of the present application is shown. The electrolyzer cluster will be divided into n proton exchange membrane electrolyzers of equal specifications and N alkaline electrolyzers. One proton exchange membrane electrolyzer is designated to be in a fluctuating operation state, and the remaining electrolyzers are arranged to work in other states according to the wind and solar output power. Among them, the alkaline electrolyzer is preferentially in a standby state rather than a shutdown state, and the proton exchange membrane electrolyzer is preferentially operated in an overload state. In order to balance the operating load of each module, a time period T is set (the period T is less than the hydrogen production safety power operation time). After each period T, the operating states of the two types of electrolyzers are changed in turn, that is, the operating state of the next electrolyzer inherits the operating state of the previous electrolyzer, and the first electrolyzer inherits the operating state of the last electrolyzer, but the standby and fluctuating states will be fixed in rotation within the range of their respective electrolyzer clusters, that is, the fluctuating state is only rotated in the proton exchange membrane electrolyzer array, and the standby state is also only rotated in the alkaline electrolyzer.

[0110] In a possible embodiment, in order to verify the effectiveness of the composite electrolyzer cluster operation state rotation control method proposed in the embodiment of the present application, it is compared with the traditional sequential start-stop control strategy, and the wind and light data of a certain area in the southwest are selected as the case basis. A 200kW wind turbine and a 300kW photovoltaic generator are planned to be installed. Figure 8 The schematic diagram of wind power generation group and photovoltaic power generation group's wind and solar power output throughout the year is shown. Through the analysis of the output power of each electrolyzer monomer mentioned above, the operating time proportion of each state of the electrolyzer monomer in Table 1 is:

[0111] Table 1

[0112] Operation Mode AEL1 AEL2 AEL3 AEL4 AEL5 AEL6 PEM1 PEM2 PEM3 Fluctuating operation 0 0 0 0 0 0 32.01％ 34％ 33％ Overload operation 0 0 1.66％ 1.41％ 1.86％ 1.20％ 3.23％ 3.04％ 2.42％ Rated operation 49.30％ 47.72％ 51.71％ 51.18％ 45.59％ 42.76％ 48.85％ 47.5％ 51.43％ Optimal operation 43.85％ 49.25％ 36.63％ 33.15％ 37.60％ 45.79％ 19.91％ 15.46 18.15％ Standby operation 6.85％ 3.03％ 10.00％ 14.26％ 14.94％ 10.05％ 0 0 0 Shutdown operation 0 0 0 0 0 0 0 0 0

[0113] The control strategy proposed in this application prevents the AEL electrolyzer from fluctuating and shutting down. The PEM electrolyzer bears the main fluctuating power, accounting for 331%. This ensures that the system not only reduces frequent start-stop conditions, but also fully utilizes the advantages of the PEMEL electrolyzer's strong ability to adapt to fluctuating power sources;

[0114] The rated operating time of the AEL electrolyzer is between 42.76% and 51.71%, while the PEMEL electrolyzer is also between 46.85% and 51.43% most of the time. This shows that the system as a whole operates at rated power most of the time, ensuring safe and efficient production;

[0115] Compared with the PEMEL electrolyzer, the optimal operation time of the AEL electrolyzer is relatively high, ranging from 33.15% to 49.25%, indicating that the AEL electrolyzer operates in the optimal state more frequently, effectively improving the hydrogen production efficiency;

[0116] Setting the standby state reduces the probability of electrolytic cell shutdown and ensures the production continuity of the system.

[0117] The comprehensive indicators of the electrolyzer cluster can effectively reflect its service life and safety. In order to more intuitively express the degree of balance in the operating time, the standard deviation (SD) and coefficient of variation (CV) are used to measure the use of the electrolyzer. Specifically, the larger the standard deviation and coefficient of variation, the greater the inconsistency of the operating status of the electrolyzer cluster; conversely, the smaller the standard deviation and coefficient of variation, the smaller the inconsistency of the operating status of different electrolyzers. This method helps to evaluate the balance and consistency of the electrolyzer cluster under different operating conditions, so as to better understand the performance of the electrolyzer and the factors that may affect its life and safety.

[0118] Since rated operation is the most common and ideal state of electrolyzer operation, special attention is paid to the dispersion of the operating time distribution in this state. Fig. 9 A schematic diagram of the discrete degree of the rated operating time under the traditional sequential start-stop method and the compound rotation method is shown. The standard deviation and coefficient of variation of the compound rotation method are 2.82min and 0.06 respectively, while the standard deviation and coefficient of variation of the traditional sequential start-stop method are 30.53min and 47.10. Compared with the traditional sequential start-stop method, the standard deviation and coefficient of variation of the compound rotation method are reduced by 27.71min and 47.04 respectively.

[0119] In addition, the effectiveness of the optimization control method for electrolyzer cluster hydrogen production is analyzed:

[0120] The electrolysis efficiency of the PEMEL electrolyzer using the method proposed in this application is significantly higher than that of the traditional method, and the shutdown probability is lower. When the wind and solar power fluctuate drastically, the traditional method causes the electrolyzers at the rear to shut down frequently, and the hydrogen production efficiency is low. In contrast, the composite rotation method can effectively smooth out these fluctuations when the wind and solar input power jumps significantly, and significantly reduce the system shutdown probability through rotation. The control method proposed in this article not only significantly reduces the shutdown probability of the electrolyzer, but also effectively improves the overall hydrogen production efficiency of the system.

[0121] Fig.10The schematic diagram of hydrogen production of electrolyzer monomers under the composite rotation mode shows that under the condition of fluctuating wind and solar power input, the two types of electrolyzers with optimized power distribution show significant uniformity in hydrogen production. AEL's hydrogen production is 0.395Nm 3 Up to 0.425Nm 3 The hydrogen production of PEMEL was maintained at 0.652-0.01Nm 3 In contrast, when the wind and solar input power is low, the front-end electrolyzer of the traditional sequential start-stop method is in operation for a long time, while the rear-end electrolyzer stops working on a large scale, resulting in significant differences in hydrogen production. The hydrogen production of AEL is 0.404Nm 3 Up to 0.577Nm 3 Between, PEM electrolyzer at 0.058Nm 3 Up to 0.517Nm 3 Although the hydrogen production of the front-end electrolyzers under the traditional sequential start-stop mode is generally higher than that of the electrolyzers under the compound rotation mode, the difference is not significant and gradually decreases until the hydrogen production of the AEL6 electrolyzer under the compound rotation mode exceeds that of the traditional sequential start-stop mode. At the same time, the hydrogen production of PEMEL under the compound rotation mode is significantly higher than that of PEMEL under the traditional sequential start-stop mode.

[0122] In summary, the consistency of hydrogen production of each electrolyzer under the composite rotation mode is much higher than that of the electrolyzer under the traditional sequential start-stop mode, and the average hydrogen production is higher than that of the electrolyzer under the traditional sequential start-stop mode. In the simulation scenario of this paper, the total hydrogen production of the traditional sequential start-stop mode is 3.822Nm 3 , and the total hydrogen production after power optimization of this strategy can reach 4.232Nm 3 , an overall increase of 10.73%. The power optimization allocation method proposed in this paper fully considers the operating characteristics of the two types of electrolyzers, realizes the reasonable allocation of power among the electrolyzers and improves the hydrogen production efficiency of the system, while improving the balance of electrolyzer operation.

[0123] Compared with the prior art, the embodiments of the present application have the following beneficial effects:

[0124] First, by introducing multiple operating states and dynamically adjusting the operating state of the electrolyzer according to different working conditions, it can better adapt to the fluctuating characteristics of wind and solar power generation. Under overload conditions, the electrolyzer can also be flexibly upgraded to an overload state to absorb excess power and ensure the stable operation of the system.

[0125] Second, under low-power conditions and when the fluctuating input power is low, the electrolyzer should be adjusted to the optimal power state first, thereby ensuring high electrolysis efficiency and reducing the probability of downtime.

[0126] Third, by setting different levels of operating conditions, the output power of wind and solar power can be maximized, so that electricity can be reasonably distributed regardless of high power or low power conditions, ensuring that all renewable energy is effectively utilized and reducing energy waste.

[0127] Fourth, in view of the fluctuating operating state of the proton exchange membrane electrolyzer, its operating range is strictly controlled to ensure that the hydrogen concentration in oxygen does not approach the lower explosion limit, while avoiding damage to the battery stack materials due to high-power operation, thereby improving the safety performance of the system.

[0128] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for controlling the rotation of the operation status of a composite electrolytic cell cluster, characterized in that: The method comprises: Utilize photovoltaic power generation system and wind power generation system to convert electric power into direct current through converter and send it into system DC bus; When hydrogen is produced by an electrolyzer cluster, the electrolyzers are divided into multiple operating states according to the operating power of the electrolyzers, and the electrolyzer cluster includes multiple proton exchange membrane electrolyzers and multiple alkaline electrolyzers; According to the level of wind and solar input power, the total power is divided into multiple working conditions according to the output steps; Based on the current power demand, the operating status of the electrolyzer is rotated dynamically according to the operating conditions. The power in the system DC bus is dynamically allocated to the electrolyzer cluster through the DC / DC converter to complete the coordinated power distribution of the proton exchange membrane electrolyzer and the alkaline electrolyzer.

2. The method for controlling the operation state rotation of a composite electrolytic cell cluster according to claim 1, characterized in that: The operating state includes rated state, optimal state, fluctuation state, overload state, standby state and shutdown state; Under rated conditions, the electrolyzer operates at the set rated power; Under the optimal condition, the optimal operating power of the electrolyzer is set at 50% of the rated power; Under the fluctuation state, the electrolyzer operates in an elastic fluctuation range from minimum power to overload power; In the overload state, the power of the electrolyzer when operating exceeds the rated power, reaching 110% to 130% of the rated power; In standby mode, the system stops producing hydrogen and consumes electricity to maintain the temperature and pressure of the electrolyzer. In the shutdown state, the electrolytic cell is closed and cooled, and current will not flow into the electrolytic cell.

3. The method for controlling the operation status rotation of a composite electrolytic cell cluster according to claim 2, characterized in that: The fluctuation state only exists in the proton exchange membrane electrolyzer. The alkaline electrolyzer takes precedence over the proton exchange membrane electrolyzer in the standby state, and the proton exchange membrane electrolyzer takes precedence over the alkaline electrolyzer in the overload state.

4. The method for controlling the operation status rotation of a composite electrolytic cell cluster according to claim 3, characterized in that: The operating conditions include overload conditions, optimal conditions, standby conditions, and low power conditions. The method further includes: Under overload conditions, the total power of the electrolyzer exceeds the rated sum of the electrolyzers. At this time, the electrolyzers operate in the overload state, rated state, and fluctuation state. Except for the proton exchange membrane electrolyzers operating in the fluctuation state, all electrolyzers operate in the rated state. If the wind and solar power cannot be fully absorbed, the electrolyzers are successively upgraded to the overload state until the input power is fully absorbed. Under optimal operating conditions, the electrolyzer operates in the optimal state; under standby conditions, the electrolyzer operates in the standby state; under low-power conditions, the electrolyzer operates in the shutdown state. If the electrolyzer does not fully absorb the input power in the optimal state, standby state and shutdown state, the electrolyzer will be upgraded to the rated state, optimal state, and standby state until the wind and solar power are fully absorbed.

5. The method for controlling the operation status rotation of a composite electrolytic cell cluster according to claim 4, characterized in that: Based on the current power demand, the steps of rotating the operating state of the electrolyzer according to the working conditions include: Step S1: Collect the electrolytic cell number k and the total renewable energy power P to be absorbed. total And the total rated power P of the electrolyzer el ; Step S2: Determine P total Is it greater than (n+N-1)P o +P e If it is greater than, execute step S3; if it is not greater than, execute step S6; Step S3: Determine P total Is it greater than (n+N-1)P e +σP e If it is greater than, execute step S4; if it is not greater than, execute step S5; Step S4, determining whether the overload power number of the electrolytic cell is maximized, if so, rotating the state of the electrolytic cell according to the rotation strategy, if not, converting the kth electrolytic cell from the rated state to the overload state, and executing the conversion of the rated state to the overload state for the next electrolytic cell when it is determined that the overload power number of the electrolytic cell is not maximized next time, until the overload power number of the electrolytic cell is maximized; Step S5, determining whether the rated power of the electrolytic cell is maximized, if so, rotating the state of the electrolytic cell according to the rotation strategy, if not, converting the kth electrolytic cell from the optimal state to the overload state, and executing the optimal state conversion to the overload state for the next electrolytic cell when it is determined that the overload power number of the electrolytic cell is not maximized next time, until the overload power number of the electrolytic cell is maximized; Step S6: Determine P total Is it greater than (n+N-1)P s +P e If it is greater than, execute step S7; if it is not greater than, execute step S8; Step S7, judging whether the optimal power of the electrolytic cell is maximized, if so, rotating the state of the electrolytic cell according to the rotation strategy, if not, converting the standby state of the kth electrolytic cell to the optimal state, and executing the standby state conversion to the optimal state for the next electrolytic cell when it is judged that the overload power number of the electrolytic cell is not maximized next time, until the overload power number of the electrolytic cell is maximized; Step S8, determine whether the standby power number of the electrolytic cell is maximized. If so, rotate the state of the electrolytic cell according to the rotation strategy. If not, the kth electrolytic cell is converted from the shutdown state to the standby state. When it is determined next time that the overload power number of the electrolytic cell is not maximized, the next electrolytic cell is converted from the shutdown state to the standby state until the overload power number of the electrolytic cell is maximized.

6. The method for controlling the operation status rotation of a composite electrolytic cell cluster according to claim 5, characterized in that: Rotation strategies include: Set a time period T, which is less than the safe power operation time of hydrogen production; After each cycle T, the operating states of multiple proton exchange membrane electrolyzers and multiple alkaline electrolyzers are changed in turn, the operating state of the next electrolyzer inherits the operating state of the previous electrolyzer, the first electrolyzer inherits the operating state of the last electrolyzer, and the standby state is rotated among the multiple alkaline electrolyzers, and the fluctuation state is rotated among the multiple proton exchange membrane electrolyzers.

7. A composite electrolytic cell cluster operation state rotation control system, characterized in that: The system comprises: Photovoltaic power generation system and wind power generation system, used to convert electricity into direct current through converters; clusters of electrolyzers to convert electricity into hydrogen; DC / DC converter is used to adjust voltage and current and distribute electricity according to hydrogen production load demand.

8. A composite electrolytic cell cluster operation state rotation control system, characterized in that: The electrolyzer cluster includes a plurality of proton exchange membrane electrolyzers and a plurality of alkaline electrolyzers.

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