Wind-solar off-grid hydrogen production system operation method capable of flexibly distributing electrolytic cell operation power instructions

Abstract

The invention discloses a wind and light off-grid hydrogen production system operation method capable of flexibly distributing electrolytic cell operation power instructions. The method comprises the steps that mathematical models of all units of a wind and light off-grid hydrogen production system are established; dividing hydrogen production conditions in different power intervals according to hydrogen production characteristics of the electrolytic cell; inputting wind speed and illumination intensity data, calculating wind-solar power generation power, and judging the working condition of the electrolytic cell; collecting an energy storage charge state in real time, and judging whether the preparation capacity of the energy storage unit is sufficient or not; formulating an energy storage power supply priority, and flexibly distributing a power instruction for the electrolytic cell; a power instruction is allocated to the energy storage unit. The method can flexibly distribute the operation power instruction of the electrolytic cell, improves the real-time hydrogen production working condition of the electrolytic cell, reserves sufficient energy for the energy storage unit to cope with the severe working condition of the electrolytic cell in the future, reduces the annual shutdown frequency of the electrolytic cell, and improves the hydrogen production stability.

Description

Technical Field

[0001] The present invention relates to the technical field of coordinated operation of renewable energy hydrogen production systems, and in particular to an operation method of a wind-solar off-grid hydrogen production system that flexibly distributes electrolyzer operation power instructions. Background Art

[0002] In recent years, wind power generation and photovoltaic power generation have developed rapidly, and a large amount of new energy power generation has been introduced into the power system, posing a threat to the power quality of the power system. Hydrogen energy is one of the most ideal energy sources in the future. It is an important guarantee for promoting the storage and consumption of new energy and improving the flexibility and reliability of new power systems. Using wind and solar power generation to electrolyze water to produce hydrogen off-grid can not only reduce the impact of wind and solar power generation on the power grid, but also improve my country's wind and solar power consumption capacity. However, due to the lack of large power grid support for wind and solar off-grid hydrogen production systems, the volatility and intermittency of wind and solar resources will lead to instability in the working power of the electrolyzer, which will not only reduce the amount of hydrogen produced and energy utilization, but even cause explosions in severe cases. Problems such as poor stability, low efficiency, and frequent shutdowns of wind and solar off-grid hydrogen production systems have seriously restricted the development of wind and solar off-grid hydrogen production.

[0003] In order to solve the problems of poor stability, low efficiency and frequent shutdowns of electrolyzers, many scholars have improved the operating status of electrolyzers from the aspects of electrolyzer equipment performance optimization, control method improvement, capacity configuration optimization, etc. However, most of the existing results adopt traditional operating strategies without considering the specific operating conditions of the electrolyzer. The rated power is used as the hydrogen production instruction of the electrolyzer at every moment. This will result in no priority when energy storage is used to power the electrolyzer. The limited energy in the energy storage is not used to avoid electrolyzer shutdown and low-power operation, which in turn leads to the electrolyzer operating power fluctuating, low average hydrogen production efficiency and frequent shutdowns.

[0004] In summary, there is still room for research on the coordinated operation of various devices in the off-grid hydrogen production system and the flexible allocation of electrolyzer operating power instructions to further improve the stability and reliability of electrolyzer hydrogen production. Summary of the invention

[0005] The problem to be solved by the present invention is to provide a method for operating a wind-solar off-grid hydrogen production system that flexibly distributes electrolyzer operating power instructions, thereby improving the stability and reliability of electrolyzer hydrogen production.

[0006] The present invention adopts the following technical solution: a method for operating a wind-solar off-grid hydrogen production system with flexible allocation of electrolyzer operating power instructions, comprising the following steps:

[0007] S1. Establish mathematical models of each unit of the off-grid wind and solar hydrogen production system, including wind power generation unit, photovoltaic power generation unit, hydrogen production unit, and hybrid energy storage unit;

[0008] S2. Based on the hydrogen production characteristics of the electrolyzer, the hydrogen production efficiency and hydrogen production rate of the electrolyzer are comprehensively considered to divide the hydrogen production conditions of the electrolyzer into different power ranges;

[0009] S3. Input wind speed and light intensity data, calculate wind and solar power generation, and determine the working condition of the electrolyzer;

[0010] S4, real-time collection of energy storage charge status, to determine whether the reserve capacity of the hybrid energy storage unit is sufficient;

[0011] S5. Establish energy storage power supply priorities for off-grid wind and solar power hydrogen production systems, and flexibly allocate power instructions to electrolyzers.

[0012] Preferably, in step S1, a mathematical model of each unit of the wind-solar off-grid hydrogen production system is established in the following manner:

[0013] S1.1. In a wind power generation unit, the calculation formula for the wind turbine generator power generation is:

[0014]

[0015] Among them, P f (t) is the power generated by the wind turbine at the tth moment, v(t) is the real-time wind speed at the hub height at the tth moment, v in is the wind turbine cut-in wind speed, v out is the cut-out wind speed, v r is the rated wind speed of the fan, P r is the rated power of the fan.

[0016] S1.2. In the photovoltaic power generation unit, the calculation formula for the photovoltaic generator power generation is:

[0017]

[0018] Among them, P g (t) is the power generated by the photovoltaic generator at the tth moment, P sta is the rated power of the photovoltaic panel under standard conditions, f pv is the power attenuation coefficient, α T is the power temperature coefficient, G sta , G(t) are the standard light intensity and the light intensity at the tth moment, T a,sta , T a (t) are the standard temperature and the photovoltaic panel temperature at the tth moment respectively.

[0019] S1.3. In the hydrogen production unit, the mathematical model of the electrolyzer of the hydrogen production equipment includes:

[0020] The calculation formula for the hydrogen production of the electrolyzer is:

[0021] Q ec(t) = P ecr (t)*η ec (t)

[0022] Among them, Q ec (t) is the hydrogen production of the electrolyzer, P ecr (t) and η ec (t) are the electrolyzer operating power and hydrogen production efficiency, respectively.

[0023] The calculation formula of electrolytic cell operating power is:

[0024] P ecr (t) = P N -P bre (t)

[0025] Among them, P N is the rated power of the electrolyzer, P bre (t) is the power shortage of the electrolytic cell at time t.

[0026] The calculation formula for the hydrogen production efficiency of the electrolyzer is:

[0027]

[0028] Among them, η ec (t) is the hydrogen production efficiency of the electrolyzer, U ec (t) is the electrolysis voltage, U tn is the thermal neutral voltage, η F (t) is the Faraday efficiency of the electrolytic cell.

[0029] The calculation formula of electrolytic cell electrolysis voltage is:

[0030] U ec (t) = U cell (t)*N ec

[0031] Among them, U cell (t) is the cell voltage, N ec is the number of electrolytic cell units.

[0032] U cell (t) = U rev +U ohm (t)+U con (t)

[0033] Among them, U rev is the reversible voltage of the electrolytic cell, U ohm (t), U con (t) are the ohmic polarization voltage and concentration polarization voltage of the electrolytic cell at time t, respectively.

[0034] The expression of ohmic polarization voltage is:

[0035]

[0036] Among them, r1 and r2 are the electrochemical correlation coefficients of the electrolytic cell, T ec is the electrolyte temperature of the electrolytic cell, A ec is the electrode area.

[0037] The expression of concentration polarization voltage is:

[0038]

[0039] Among them, S, t1, t2, and t3 are electrochemical parameters related to the electrolytic cell.

[0040] The formula for calculating the Faraday efficiency of an electrolytic cell is:

[0041]

[0042] Where I(t) is the electrolysis current.

[0043] The calculation formula of hydrogen production rate of electrolyzer is:

[0044]

[0045] Among them, V H2 (t) is the hydrogen production rate of the electrolyzer at time t, and F is the Faraday constant.

[0046] S1.4. In the hybrid energy storage unit, the hybrid energy storage is composed of batteries and supercapacitors. The mathematical model of the hybrid energy storage unit energy storage device (battery, supercapacitor) is:

[0047]

[0048] in, are the charge states of the energy storage device at time t and t+Δt respectively, P t ch , P t dis are the charging and discharging power of the energy storage device at time t, η is the charging and discharging efficiency of the energy storage device, Δt is the time step; E is the configuration capacity of the energy storage device.

[0049] Preferably, in step S2, dividing the hydrogen production conditions into different power intervals according to the hydrogen production characteristics of the electrolyzer includes the following contents:

[0050] According to the mathematical model of hydrogen production efficiency and hydrogen production rate of the electrolyzer established in step S1, it can be known that the hydrogen production efficiency of the alkaline electrolyzer first increases rapidly with the increase of input power, and then decreases slowly, while the hydrogen production rate of the alkaline electrolyzer increases continuously with the increase of input power.

[0051] From this, we can see that the hydrogen production efficiency is not completely positively correlated with the hydrogen production rate. During the operation of the electrolyzer, we must consider improving the hydrogen production efficiency of the electrolyzer to improve energy utilization, while at the same time hoping to increase the hydrogen production rate, increase the amount of hydrogen produced and increase profits.

[0052] The comprehensive hydrogen production efficiency and hydrogen production rate are two indicators, P N Represents the rated power of the electrolyzer, and the working conditions of different intervals of the electrolyzer hydrogen production power are divided into:

[0053] (1) [70%P N ,100%P N ]: High-efficiency and high-speed hydrogen production conditions, with hydrogen production efficiency greater than 70% and hydrogen production rate greater than 7.28 mol / s, which belongs to the most ideal operating range.

[0054] (2) [50%P N ,70%P N ]: High-efficiency medium-speed hydrogen production conditions, the hydrogen production efficiency is greater than 70%, the hydrogen production rate is moderate, this working range is ideal.

[0055] (3) [20%P N ,50%P N ]: High-efficiency and low-speed hydrogen production conditions, the hydrogen production efficiency is greater than 70%, but the hydrogen production rate is low. The power shortage rate in this operating range is high, which will affect the revenue.

[0056] (4)[0,20%P N ]: The operating condition is not allowed. Although it includes some high-efficiency hydrogen production ranges, the hydrogen production rate is lower than 2 mol / s, which is prone to explosion and is not allowed to operate.

[0057] Preferably, in step S3, calculating the sum of wind and solar power generation and determining the working condition of the electrolytic cell includes the following contents:

[0058] The wind and photovoltaic power generation are calculated according to the wind turbine power generation calculation formula and the photovoltaic power generation calculation formula in step S1, respectively. The sum of wind and photovoltaic power generation is calculated as follows:

[0059] P fg (t) = P f (t)+P g (t)

[0060] Among them, P f (t) is the power generated by the wind turbine at the tth moment, P g (t) is the power generated by the photovoltaic generator at the tth moment, P fg (t) is the sum of wind and solar power generation at moment t.

[0061] Judging the working conditions of the electrolytic cell includes:

[0062] (1) When P fg (t ) ≥P N When the electrolyzer produces hydrogen at rated power, the electrolyzer is in a high-efficiency and high-speed hydrogen production state, with the maximum hydrogen production rate and the highest profit. fg (t)>P N When the power is stored in the energy storage unit, it will be charged to absorb the excess electricity and reduce the curtailment of wind and solar power.

[0063] (2) When P fg (t)<P N When relying solely on wind and solar power generation, the electrolyzer may be in a high-efficiency high-speed hydrogen production condition, a high-efficiency medium-speed hydrogen production condition, a high-efficiency low-speed hydrogen production range, or even a non-permitted operating condition. At this time, the energy storage unit needs to discharge to improve the electrolyzer operating condition. For different operating conditions, it is necessary to flexibly allocate the electrolyzer's optimal power instructions in combination with the current energy storage charge state, so that the energy storage reserves sufficient capacity while discharging to avoid electrolyzer shutdown and low-speed hydrogen production conditions.

[0064] Further, in step S4, determining whether the reserve capacity of the energy storage unit is sufficient includes the following contents:

[0065] Before flexibly allocating the electrolyzer operating power instructions, it is necessary to determine whether the battery and supercapacitor have sufficient backup capacity based on the energy storage charge state. Sufficient reserve capacity means that after the energy storage is completed, it is still able to avoid possible electrolyzer shutdowns.

[0066] Judging whether the energy storage reserve capacity is sufficient is the premise for formulating the optimal power instruction for the electrolyzer. When the energy storage charge state is greater than 0.5, the reserve capacity is considered sufficient.

[0067] Using SOC(t) and SOC c (t) represents the charge state of the battery and supercapacitor at time t. According to whether the reserve capacity of the battery and supercapacitor is sufficient, it can be divided into the following four situations:

[0068] (1) SOC(t)>0.5 and SOC c (t)>0.5: The reserve capacity of the battery and supercapacitor is sufficient;

[0069] (2) SOC(t)>0.5 and SOC c (t)≤0.5: The battery reserve capacity is sufficient, but the supercapacitor reserve capacity is insufficient;

[0070] (3) SOC(t)≤0.5 and SOC c (t)>0.5: The battery reserve capacity is insufficient, but the supercapacitor reserve capacity is sufficient;

[0071] (4) SOC(t)≤0.5 and SOC c (t)≤0.5: The reserve capacity of the battery and supercapacitor is insufficient.

[0072] S5. Formulate energy storage power supply priorities and flexibly allocate power instructions to electrolyzers, including the following:

[0073] Combined with the hybrid energy storage reserve capacity obtained in step S4, the power supply priority is formulated to flexibly allocate the optimal power to the electrolyzer. The specific situations are as follows:

[0074] (1) When the energy storage reserve capacity is sufficient, that is, in the cases (1) to (3) in step S4, when at least one of the battery and supercapacitor has sufficient reserve capacity, no matter what operating condition the electrolyzer is in at this time, the energy storage has the ability to make the electrolyzer enter a high-efficiency and high-speed operating condition. Therefore, in order to make the hydrogen production rate higher, when the energy storage reserve capacity is sufficient, no matter what operating condition the electrolyzer is in, the power instruction is P N .

[0075] (2) When the energy storage reserve capacity is insufficient, that is, in case (4) of step S4, the capacity of both the battery and the supercapacitor is insufficient, it is necessary to consider the energy storage power supply priority under each working condition:

[0076] 1) When the electrolyzer is in a condition where operation is not allowed, first of all, the electrolyzer must not be shut down, and secondly, the electrolyzer must be made to enter a relatively ideal high-efficiency medium-speed hydrogen production condition as much as possible. Therefore, the electrolyzer operating power instruction under this condition is set to 0.5P N ;

[0077] 2) When the electrolyzer is in a less than ideal high-efficiency low-speed hydrogen production condition, the electrolyzer operating power instruction is set to 0.5P N , making it enter a relatively ideal high-efficiency medium-speed hydrogen production condition;

[0078] 3) When the electrolyzer is in an ideal high-efficiency medium-speed hydrogen production condition, the electrolyzer operating power instruction is set to 0.7P N , making it enter the most ideal high-efficiency and high-speed hydrogen production condition;

[0079] 4) When the electrolyzer is already in the most ideal high-efficiency and high-speed hydrogen production condition, the electrolyzer operating power instruction is set as P fg (t), maintaining efficient and high-speed hydrogen production conditions, storing energy and retaining energy without discharging.

[0080] In this way, when the energy storage reserve capacity is not sufficient, it is only necessary to meet the priority power supply needs of the electrolyzer under each operating condition, so as to improve the electrolyzer's ability to cope with severe operating conditions throughout the year.

[0081] The technical solution of the present invention also provides: an electronic device, comprising:

[0082] one or more processors;

[0083] a storage device having one or more programs stored thereon;

[0084] When the one or more programs are executed by the one or more processors, the one or more processors implement any of the above-mentioned methods for operating a wind-solar off-grid hydrogen production system with flexible allocation of electrolyzer operating power instructions.

[0085] The technical solution of the present invention also provides a computer-readable storage medium on which a computer program is stored. When the program is executed by a processor, the steps in any of the above-mentioned wind-solar off-grid hydrogen production system operation methods for flexibly allocating electrolyzer operating power instructions are implemented.

[0086] Compared with the prior art, the present invention adopts the above technical solution and has the following technical effects:

[0087] 1. The coordinated operation method of the off-grid hydrogen production system in this paper can flexibly allocate the electrolyzer operating power instructions, formulate energy storage power supply priorities for different hydrogen production conditions of the electrolyzer, and flexibly allocate the electrolyzer operating power instructions. It can improve the real-time electrolyzer hydrogen production conditions while reserving sufficient energy for the energy storage unit to cope with the harsh working conditions of the electrolyzer in the future, thereby reducing the number of electrolyzer shutdowns and power fluctuations throughout the year and improving the average hydrogen production efficiency.

[0088] 2. The coordinated operation method of the off-grid hydrogen production system in this article can improve the hydrogen production efficiency of the electrolyzer, significantly reduce the number of shutdowns throughout the year, and thus improve the stability, safety and reliability of hydrogen production by the electrolyzer. BRIEF DESCRIPTION OF THE DRAWINGS

[0089] Figure 1 This is a structural diagram of the wind-solar off-grid hydrogen production system of the present invention;

[0090] Figure 2 This is a flow chart of the operation method of the wind-solar off-grid hydrogen production system of the present invention;

[0091] Figure 3 This is a full-year operation power diagram of the electrolyzer according to an embodiment of the present invention;

[0092] Figure 4 This is a graph of the annual hydrogen production efficiency of the electrolyzer according to an embodiment of the present invention. DETAILED DESCRIPTION

[0093] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the application is further elaborated in detail below in conjunction with the accompanying drawings. The described embodiments are only a part of the embodiments involved in the present invention. All non-innovative embodiments of other researchers in the field on this embodiment belong to the protection scope of the present invention. At the same time, for the step numbering in the embodiment of the present invention, it is only set for the convenience of explanation, and the order between the steps is not limited in any way. The execution order of each step in the embodiment can be adaptively adjusted according to the understanding of those skilled in the art.

[0094] The working principle of the wind and solar off-grid hydrogen production system is as follows: wind turbines and photovoltaic generators generate electricity to supply electrolyzers to electrolyze water to produce hydrogen. The electrolyzers use the power instructions as working power. When wind and solar power generation cannot meet the electrolyzer operating power instructions, the hybrid energy storage unit (battery, supercapacitor) is discharged to supplement the energy.

[0095] In one embodiment of the present invention, a wind-solar off-grid hydrogen production system, such as Figure 1 As shown, it includes: wind turbine, photovoltaic generator, electrolyzer, battery, supercapacitor, and there is power transmission between the various devices in the system. The specific parameters of the system are:

[0096] Table 1 Specific parameters of wind and solar off-grid hydrogen production system

[0097] parameter Value Wind turbine capacity / MW 200 Photovoltaic generator capacity / MW 180 Total rated capacity of electrolyzer / MW 180 Battery capacity / MWh 82.73 Supercapacitor capacity / MWh 25.35

[0098] Furthermore, this embodiment proposes a wind-solar off-grid hydrogen production system operation method for flexibly allocating electrolyzer operation power instructions, respectively formulating energy storage power supply priorities for different hydrogen production conditions of the electrolyzer, and flexibly allocating electrolyzer operation power instructions, and the specific steps are as follows:

[0099] S1. Establish mathematical models of each unit of the off-grid wind and solar hydrogen production system, including wind power generation unit, photovoltaic power generation unit, hydrogen production unit, and hybrid energy storage unit; the specific contents are as follows:

[0100] In the wind power generation unit, the calculation formula for the wind turbine generator power generation is:

[0101]

[0102] Among them, P f (t) is the power generated by the wind turbine at the tth moment, v(t) is the real-time wind speed at the hub height at the tth moment, v in is the wind turbine cut-in wind speed, v out is the cut-out wind speed, v r is the rated wind speed of the fan, P r is the rated power of the fan.

[0103] In the photovoltaic power generation unit, the calculation formula for the photovoltaic generator power generation is:

[0104]

[0105] Among them, P g (t) is the power generated by the photovoltaic generator at the tth moment, P sta is the rated power of the photovoltaic panel under standard conditions, f pv is the power attenuation coefficient, α T is the power temperature coefficient, G sta , G(t) are the standard light intensity and the light intensity at the tth moment, T a,sta , T a (t) are the standard temperature and the photovoltaic panel temperature at the tth moment respectively.

[0106] In the hydrogen production unit, the mathematical model of the electrolyzer of the hydrogen production equipment includes:

[0107] The calculation formula for the hydrogen production of the electrolyzer is:

[0108] Q ec (t) = P ecr (t)*η ec (t)

[0109] Among them, Q ec (t) is the hydrogen production of the electrolyzer, P ecr (t) and η ec (t) are the electrolyzer operating power and hydrogen production efficiency, respectively.

[0110] The calculation formula of electrolytic cell operating power is:

[0111] P ecr (t) = P N -P bre (t)

[0112] Among them, P N is the rated power of the electrolyzer, P bre (t) is the power shortage of the electrolytic cell at time t.

[0113] The calculation formula for the hydrogen production efficiency of the electrolyzer is:

[0114]

[0115] η ec (t) is the hydrogen production efficiency of the electrolyzer, U ec (t) is the electrolysis voltage, U tn is the thermal neutral voltage, the theoretical value is 1.23V, η F (t) is the Faraday efficiency of the electrolytic cell.

[0116] The calculation formula of electrolytic cell electrolysis voltage is:

[0117] U ec (t) = U cell (t)*N ec

[0118] Among them, U cell (t) is the cell voltage, N ec is the number of electrolytic cell units.

[0119] U cell (t) = U rev +U ohm (t)+U con (t)

[0120] Among them, U rev is the reversible voltage of the electrolytic cell, which is a constant, here it is 12V, U ohm (t), U con (t) are the ohmic polarization voltage and concentration polarization voltage of the electrolytic cell at time t, respectively.

[0121] The expression of ohmic polarization voltage is:

[0122]

[0123] Among them, r1 and r2 are the electrochemical correlation coefficients of the electrolytic cell, T ec is the electrolyte temperature of the electrolytic cell, A ec is the electrode area.

[0124] The expression of concentration polarization voltage is:

[0125]

[0126] Among them, S, t1, t2, and t3 are electrochemical parameters related to the electrolytic cell.

[0127] The formula for calculating the Faraday efficiency of an electrolytic cell is:

[0128]

[0129] Where I(t) is the electrolysis current.

[0130] The calculation formula of hydrogen production rate of electrolyzer is:

[0131]

[0132] Among them, V H2 (t) is the hydrogen production rate of the electrolyzer at time t, and F is the Faraday constant.

[0133] In the hybrid energy storage unit, the hybrid energy storage consists of batteries and supercapacitors. The mathematical model of the hybrid energy storage unit includes:

[0134] The mathematical model of energy storage equipment (battery, supercapacitor) is:

[0135]

[0136] in, are the charge states of the energy storage device at time t and t+Δt respectively, P t ch , P t dis are the charging and discharging power of the energy storage device at time t, η is the charging and discharging efficiency of the energy storage device, Δt is the time step; E is the configuration capacity of the energy storage device.

[0137] S2. Divide the hydrogen production conditions in different power ranges according to the hydrogen production characteristics of the electrolyzer; the specific contents are:

[0138] According to the mathematical model of hydrogen production efficiency and hydrogen production rate of the electrolyzer established in step S1, it can be known that the hydrogen production efficiency of the alkaline electrolyzer first increases rapidly with the increase of input power, and then decreases slowly, while the hydrogen production rate of the alkaline electrolyzer increases with the increase of input power. It can be seen that the hydrogen production efficiency and the hydrogen production rate are not completely positively correlated, and during the operation of the electrolyzer, it is necessary to consider improving the hydrogen production efficiency of the electrolyzer to improve energy utilization, and at the same time hope to increase the hydrogen production rate, increase the amount of hydrogen produced and increase revenue.

[0139] The comprehensive hydrogen production efficiency and hydrogen production rate are two indicators, P N Represents the rated power of the electrolyzer, and the working conditions of different intervals of the electrolyzer hydrogen production power are divided into:

[0140] (1) [70%P N ,100%P N ]: High-efficiency and high-speed hydrogen production conditions, with hydrogen production efficiency greater than 70% and hydrogen production rate greater than 7.28 mol / s, which belongs to the most ideal operating range.

[0141] (2) [50%P N ,70%P N ]: High-efficiency medium-speed hydrogen production conditions, the hydrogen production efficiency is greater than 70%, the hydrogen production rate is moderate, this working range is ideal.

[0142] (3) [20%P N ,50%P N ]: High-efficiency and low-speed hydrogen production conditions, the hydrogen production efficiency is greater than 70%, but the hydrogen production rate is low. The power shortage rate in this operating range is high, which will affect the revenue.

[0143] (4)[0,20%P N]: The operating condition is not allowed. Although it includes some high-efficiency hydrogen production ranges, the hydrogen production rate is lower than 2 mol / s, which is prone to explosion and is not allowed to operate.

[0144] S3. Input wind speed and light intensity data, calculate wind and solar power generation, and determine the working condition of the electrolyzer; the specific contents are:

[0145] In this embodiment, the wind and photovoltaic power generation are calculated according to the wind generator power calculation formula and the photovoltaic generator power calculation formula in step S1, respectively. The wind and photovoltaic power generation are calculated as follows:

[0146] P fg (t) = P f (t)+P g (t)

[0147] Among them, P f (t) is the power generated by the wind turbine at the tth moment, P g (t) is the power generated by the photovoltaic generator at the tth moment, P fg (t) is the sum of wind and solar power generation at moment t.

[0148] Judging the working conditions of the electrolytic cell includes:

[0149] (1) When P fg (t)≥P N When the electrolyzer produces hydrogen at rated power, the electrolyzer is in a high-efficiency and high-speed hydrogen production state, with the maximum hydrogen production rate and the highest profit. fg (t)>P N When the power is stored in the energy storage unit, it will be charged to absorb the excess electricity and reduce the curtailment of wind and solar power.

[0150] (2) When P fg (t ) <P N When relying solely on wind and solar power generation, the electrolyzer may be in a high-efficiency high-speed hydrogen production condition, a high-efficiency medium-speed hydrogen production condition, a high-efficiency low-speed hydrogen production range, or even a non-permitted operating condition. At this time, the energy storage unit needs to discharge to improve the electrolyzer operating condition. For different operating conditions, it is necessary to flexibly allocate the electrolyzer's optimal power instructions in combination with the current energy storage charge state, so that the energy storage reserves sufficient capacity while discharging to avoid electrolyzer shutdown and low-speed hydrogen production conditions.

[0151] S4, real-time collection of energy storage charge status, to determine whether the energy storage unit reserve capacity is sufficient; the specific content is:

[0152] Operation method of off-grid hydrogen production system of wind and solar power, such as Figure 2 As shown, Figure 2It includes step S4, which is a process for determining whether the reserve capacity of the energy storage unit is sufficient, and step S5, which is a process for determining power supply priorities according to different operating conditions of the electrolytic cells and flexibly allocating power instructions to the electrolytic cells.

[0153] Before flexibly allocating the electrolyzer operating power command, it is necessary to determine whether the battery and supercapacitor have sufficient reserve capacity based on the energy storage charge state. Sufficient reserve capacity means that after the energy storage completes this discharge, it is still able to avoid the possible electrolyzer shutdown phenomenon that may occur later.

[0154] Judging whether the energy storage reserve capacity is sufficient is the premise for formulating the optimal power instruction for the electrolyzer. When the energy storage charge state is greater than 0.5, the reserve capacity is considered sufficient. c (t) represents the charge state of the battery and supercapacitor at time t. According to whether the reserve capacity of the battery and supercapacitor is sufficient, it can be divided into the following four situations:

[0155] (1) SOC(t)>0.5 and SOC c (t)>0.5: The reserve capacity of the battery and supercapacitor is sufficient;

[0156] (2) SOC(t)>0.5 and SOC c (t)≤0.5: The battery reserve capacity is sufficient, but the supercapacitor reserve capacity is insufficient;

[0157] (3) SOC(t)≤0.5 and SOC c (t)>0.5: The battery reserve capacity is insufficient, but the supercapacitor reserve capacity is sufficient;

[0158] (4) SOC(t)≤0.5 and SOC c (t)≤0.5: The reserve capacity of the battery and supercapacitor is insufficient.

[0159] Furthermore, in step S5, the energy storage power supply priority is formulated, and the power instructions for the electrolyzers are flexibly allocated, including the following contents:

[0160] Combined with the energy storage reserve capacity obtained in step S4, power supply priorities are formulated to flexibly allocate optimal power to the electrolyzer. Specifically, it is divided into the following situations:

[0161] (1) When the energy storage reserve capacity is sufficient, that is, in cases (1) to (3) in step S4, when at least one of the battery and the supercapacitor has sufficient reserve capacity, no matter what operating condition the electrolyzer is in at this time, the energy storage is capable of enabling the electrolyzer to enter an efficient and high-speed operating condition.

[0162] Therefore, in order to increase the hydrogen production rate, when the energy storage reserve capacity is sufficient, no matter what the working condition of the electrolyzer is, the power command is PN .

[0163] (2) When the energy storage reserve capacity is insufficient, that is, in case (4) of step S4, the capacity of both the battery and the supercapacitor is insufficient, it is necessary to consider the energy storage power supply priority under each working condition:

[0164] 1) When the electrolyzer is in a condition where operation is not allowed, first of all, the electrolyzer must not be shut down, and secondly, the electrolyzer must be made to enter a relatively ideal high-efficiency medium-speed hydrogen production condition as much as possible. Therefore, the electrolyzer operating power instruction under this condition is set to 0.5P N ;

[0165] 2) When the electrolyzer is in a less than ideal high-efficiency low-speed hydrogen production condition, the electrolyzer operating power instruction is set to 0.5P N , making it enter a relatively ideal high-efficiency medium-speed hydrogen production condition;

[0166] 3) When the electrolyzer is in an ideal high-efficiency medium-speed hydrogen production condition, the electrolyzer operating power instruction is set to 0.7P N , making it enter the most ideal high-efficiency and high-speed hydrogen production condition;

[0167] 4) When the electrolyzer is already in the most ideal high-efficiency and high-speed hydrogen production condition, the electrolyzer operating power instruction is set as P fg (t), maintaining efficient and high-speed hydrogen production conditions, storing energy and retaining energy without discharging.

[0168] In this way, when the energy storage reserve capacity is not sufficient, it is only necessary to meet the priority power supply needs of the electrolyzer under each operating condition, so as to improve the electrolyzer's ability to cope with severe operating conditions throughout the year.

[0169] The final annual shutdown times and average hydrogen production efficiency of the electrolyzer are shown in Table 2.

[0170] Table 2 Annual shutdown times and average hydrogen production efficiency of electrolyzer

[0171] parameter Value Annual shutdown times of electrolyzer 232 Average hydrogen production efficiency of electrolyzer 0.6779

[0172] As can be seen from Table 2, the number of electrolyzer shutdowns throughout the year is relatively low, only 232 times, and the average hydrogen production efficiency of the electrolyzer is relatively high, at 0.6779, indicating that this method can significantly reduce the number of electrolyzer shutdowns.

[0173] The final annual operating power diagram of the electrolyzer is as follows: Figure 3As shown, it can be seen that except for the shutdown of the electrolyzer (the operating power of the electrolyzer is zero), most of the operating power of the electrolyzer is concentrated between 50% and 100% of the rated power. In other words, the electrolyzer is rarely in a harsh operating condition during the year, and the number of shutdowns (the operating power of the electrolyzer is zero) is also very small. This shows that this method can improve the operating conditions of the electrolyzer and enhance the reliability, stability and safety of hydrogen production by the electrolyzer.

[0174] The annual hydrogen production efficiency of the electrolyzer is shown in the figure below: Figure 4 As shown in the figure, it can be seen that the hydrogen production of the electrolyzer is relatively stable. Except for the shutdown of the electrolyzer (the operating power of the electrolyzer is zero), the hydrogen production efficiency is mostly maintained above 0.7, indicating that the method proposed in this article can improve the hydrogen production efficiency of the electrolyzer.

[0175] In an embodiment of the present invention, an electronic device is also provided, including: one or more processors; a storage device on which one or more programs are stored; when the one or more programs are executed by the one or more processors, the one or more processors implement the wind-solar off-grid hydrogen production system operation method for flexibly allocating electrolyzer operating power instructions as described in any of the above embodiments.

[0176] In an embodiment of the present invention, a computer-readable storage medium is further provided, on which a computer program is stored. When the program is executed by a processor, the steps in the wind-solar off-grid hydrogen production system operation method for flexibly allocating electrolyzer operating power instructions in any of the above embodiments are implemented.

[0177] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for operating a wind-solar off-grid hydrogen production system with flexible allocation of electrolyzer operating power instructions, characterized in that: The steps include: S1. Establish mathematical models of each unit of the off-grid wind and solar hydrogen production system, including wind power generation unit, photovoltaic power generation unit, hydrogen production unit, and hybrid energy storage unit; S2. Based on the hydrogen production characteristics of the electrolyzer, the hydrogen production efficiency and hydrogen production rate of the electrolyzer are comprehensively considered to divide the hydrogen production conditions of the electrolyzer into different power ranges; S3. Input wind speed and light intensity data, calculate wind and solar power generation, and determine the working condition of the electrolyzer; S4, real-time collection of energy storage charge status, to determine whether the reserve capacity of the hybrid energy storage unit is sufficient; S5. Establish energy storage power supply priorities for off-grid wind and solar power hydrogen production systems, and flexibly allocate power instructions to electrolyzers.

2. The method for operating a wind-solar off-grid hydrogen production system with flexible allocation of electrolyzer operating power instructions according to claim 1 is characterized in that: In step S1, a mathematical model of each unit of the wind-solar off-grid hydrogen production system is established as follows: S1.

1. In a wind power generation unit, the calculation formula for the wind turbine generator power generation is: Among them, P f (t) is the power generated by the wind turbine at the tth moment, v(t) is the real-time wind speed at the hub height at the tth moment, v in is the wind turbine cut-in wind speed, v out is the cut-out wind speed, v r is the rated wind speed of the fan, P r is the rated power of the fan; S1.

2. In the photovoltaic power generation unit, the calculation formula for the photovoltaic generator power generation is: Among them, P g (t) is the power generated by the photovoltaic generator at the tth moment, P sta is the rated power of the photovoltaic panel under standard conditions, f pv is the power attenuation coefficient, α T is the power temperature coefficient, G sta , G(t) are the standard light intensity and the light intensity at the tth moment, T a,sta , T a (t) are the standard temperature and the photovoltaic panel temperature at the tth moment respectively. S1.

3. In the hydrogen production unit, the mathematical model of the electrolyzer of the hydrogen production equipment includes: The calculation formula for the hydrogen production of the electrolyzer is: Q ec (t)=P ecr (t)*η ec (t) Among them, Q ec (t) is the hydrogen production of the electrolyzer, P ecr (t), η ec (t) are the electrolyzer operating power and hydrogen production efficiency, respectively; The calculation formula for the hydrogen production efficiency of the electrolyzer is: Among them, U ec (t) is the electrolysis voltage of the electrolytic cell, U tn is the thermal neutral voltage, η F (t) is the Faraday efficiency of the electrolytic cell; The calculation formula for the hydrogen production rate of the electrolyzer is: Among them, V H2 (t) is the hydrogen production rate of the electrolyzer at time t, F is the Faraday constant, I(t) is the electrolysis current, N ec is the number of electrolytic cell units; S1.

4. In a hybrid energy storage unit, the energy storage device includes a battery and a supercapacitor. The state of charge formula of the energy storage device is: in, are the charge states of the energy storage device at time t and t+Δt respectively, P t ch , P t dis are the charging and discharging power of the energy storage device at time t, η is the charging and discharging efficiency of the energy storage device, Δt is the time step, and E is the configuration capacity of the energy storage device.

3. The method for operating a wind-solar off-grid hydrogen production system with flexible allocation of electrolyzer operating power instructions according to claim 2 is characterized in that: In step S1.3, the electrolytic cell operating power P ecr (t), the calculation formula is: P ecr (t)=P N -P bre (t) Among them, P N is the rated power of the electrolyzer, P bre (t) is the power shortage of the electrolytic cell at time t; Electrolytic cell electrolysis voltage U ec (t), the calculation formula is: U ec (t)=U cell (t)*N ec Among them, U cell (t) is the cell voltage, N ec is the number of electrolytic cell units; Electrolyzer cell voltage U cell (t), the calculation formula is: U cell (t)=U rev +U ohm (t)+U con (t) Among them, U rev is the reversible voltage of the electrolytic cell, U ohm (t), U con (t) are the ohmic polarization voltage and concentration polarization voltage of the electrolytic cell at time t, respectively; Ohmic polarization voltage U ohm (t), the calculation formula is: Among them, r1 and r2 are the electrochemical correlation coefficients of the electrolytic cell, T ec is the electrolyte temperature of the electrolytic cell, A ec is the electrode area; Concentration polarization voltage U con (t), the calculation formula is: Among them, S, t1, t2, and t3 are electrochemical parameters related to the electrolytic cell; The formula for calculating the Faraday efficiency of an electrolyzer is: Where I(t) is the electrolysis current.

4. The method for operating a wind-solar off-grid hydrogen production system with flexible allocation of electrolyzer operating power instructions according to claim 2 is characterized in that: In step S2, the hydrogen production characteristics of the electrolyzer are obtained based on the mathematical model of the electrolyzer hydrogen production efficiency and hydrogen production rate of the hydrogen production unit established in step S1, which is manifested as follows: the hydrogen production efficiency of the alkaline electrolyzer first increases and then decreases with the increase of input power, and the hydrogen production rate of the alkaline electrolyzer continues to increase with the increase of input power; the hydrogen production efficiency is not completely positively correlated with the hydrogen production rate. During the operation of the electrolyzer, it is necessary to improve the hydrogen production efficiency of the electrolyzer to improve energy utilization, and also to increase the hydrogen production rate to increase the hydrogen production amount and increase revenue.

5. The method for operating a wind-solar off-grid hydrogen production system with flexible allocation of electrolyzer operating power instructions according to claim 4 is characterized in that: In step S2, according to the hydrogen production characteristics of the electrolyzer, the two indicators of hydrogen production efficiency and hydrogen production rate are comprehensively considered, P N Represents the rated power of the electrolyzer, and divides the hydrogen production conditions of the electrolyzer into different power ranges, including: [70%P N ,100%P N ]: High-efficiency and high-speed hydrogen production conditions, with hydrogen production efficiency greater than 70% and hydrogen production rate greater than 7.28 mol / s; [50%P N ,70%P N ]: High-efficiency and medium-speed hydrogen production conditions, with hydrogen production efficiency greater than 70% and moderate hydrogen production rate; [20%P N ,50%P N ]: High-efficiency and low-speed hydrogen production conditions, hydrogen production efficiency greater than 70%, low hydrogen production rate, high power shortage rate, affecting revenue; [0,20%P N ]: The operating condition is not allowed. The hydrogen production rate is lower than 2 mol / s. An explosion may occur and operation is not allowed.

6. The method for operating a wind-solar off-grid hydrogen production system with flexible allocation of electrolyzer operating power instructions according to claim 5 is characterized in that: In step S3, the sum of wind and solar power generation is calculated using the following formula: P fg (t)=P f (t)+P g (t) Among them, P fg (t) is the sum of wind and solar power generation at the tth moment, P f (t) is the power generated by the wind turbine at the tth moment, P g (t) is the power generated by the photovoltaic generator at the tth moment; Determine the working condition of the electrolytic cell as follows: When P fg (t)≥P N When the electrolyzer produces hydrogen at rated power, the electrolyzer is in a high-efficiency and high-speed hydrogen production condition, with the maximum hydrogen production rate and the highest profit; and when P fg (t)>P N When the energy storage unit is charged, it absorbs the excess energy; When P fg (t)<P N When relying solely on wind and solar power generation, the electrolyzer is in a high-efficiency, high-speed hydrogen production condition, a high-efficiency, medium-speed hydrogen production condition, a high-efficiency, low-speed hydrogen production condition, or a condition that does not allow operation. It is necessary to discharge through the hybrid energy storage unit to improve the operating condition of the electrolyzer.

7. The method for operating a wind-solar off-grid hydrogen production system with flexible allocation of electrolyzer operating power instructions according to claim 6 is characterized in that: In step S4, according to the energy storage charge state, it is determined whether the battery and supercapacitor in the hybrid energy storage unit have sufficient reserve capacity, and the SOC(t) and SOC c (t) represents the charge state of the battery and supercapacitor at time t, respectively. The energy storage reserve capacity is divided into: SOC(t)>0.5 and SOC c (t)>0.5: The reserve capacity of the battery and supercapacitor is sufficient; SOC(t)>0.5 and SOC c (t)≤0.5: The battery reserve capacity is sufficient, but the supercapacitor reserve capacity is insufficient; SOC(t)≤0.5 and SOC c (t)>0.5: The battery reserve capacity is insufficient, but the supercapacitor reserve capacity is sufficient; SOC(t)≤0.5 and SOC c (t)≤0.5: The reserve capacity of the battery and supercapacitor is insufficient.

8. The method for operating a wind-solar off-grid hydrogen production system with flexible allocation of electrolyzer operating power instructions according to claim 7 is characterized in that: In step S5, based on the obtained energy storage reserve capacity, the energy storage power supply priority is formulated to flexibly allocate power instructions to the electrolyzer, and the method is as follows: S5.

1. Sufficient reserve capacity of energy storage: At least one of the battery and supercapacitor has sufficient reserve capacity. The energy storage of the hybrid energy storage unit is capable of enabling the electrolyzer to enter a high-efficiency and high-speed operating condition. Regardless of the operating condition of the electrolyzer, the electrolyzer operating power instruction is set to P N ; S5.

2. Insufficient reserve capacity of energy storage: The capacity of batteries and supercapacitors is insufficient. Specifically consider the priority of energy storage power supply under each working condition: When the electrolyzer is in a condition where operation is not allowed, first ensure that the electrolyzer does not stop, then make the electrolyzer enter a high-efficiency medium-speed hydrogen production condition, and set the electrolyzer operating power instruction to 0.5P N ; When the electrolyzer is in the high-efficiency and low-speed hydrogen production condition, the electrolyzer operating power instruction is set to 0.5P N , so that the electrolyzer enters the high-efficiency medium-speed hydrogen production condition; When the electrolyzer is in the high-efficiency medium-speed hydrogen production condition, the electrolyzer operating power instruction is set to 0.7P N , so that the electrolyzer enters the high-efficiency and high-speed hydrogen production state; When the electrolyzer is in high-efficiency and high-speed hydrogen production condition, the electrolyzer operation power instruction is set as P fg (t), maintaining efficient and high-speed hydrogen production conditions, storing energy and retaining energy without discharging.

9. An electronic device, characterized in that: include: one or more processors; a storage device having one or more programs stored thereon; When the one or more programs are executed by the one or more processors, the one or more processors implement the wind-solar off-grid hydrogen production system operation method with flexible allocation of electrolyzer operating power instructions as described in any one of claims 1 to 8.

10. A computer-readable storage medium, characterized in that: A computer program is stored thereon, and when the program is executed by a processor, the steps in the wind-solar off-grid hydrogen production system operation method with flexible allocation of electrolyzer operation power instructions as described in any one of claims 1 to 8 are implemented.

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