System and method for full time domain matching of photovoltaic power generation by connecting unequal volume water electrolyzers in series

Abstract

The invention provides a full-time domain matching system for photovoltaic power generation of unequal-capacity water electrolyzers in series, comprising a control system, a photovoltaic array and a water electrolyzer group; the water electrolyzer group comprises a unequal-capacity water electrolyzer A and a water electrolyzer B connected in series, which are used for electrolyzing water to produce hydrogen and are installed in a photovoltaic water electrolysis hydrogen production device room; wherein the positive electrode of the water electrolyzer A is connected to the positive electrode output by the photovoltaic array, the negative electrode of the water electrolyzer A is connected to the positive electrode of the water electrolyzer B, and the negative electrode of the water electrolyzer B is connected to the negative electrode output by the photovoltaic array; the positive and negative power input ends of an adjustable electric heater are connected in parallel at both ends of the electrodes of each of the water electrolyzers A and B, which play the role of current diversion and voltage stabilization of the water electrolyzers, power adjustment of another water electrolyzer, and photovoltaic maximum power tracking; similarly, voltage sensors are installed in parallel at both ends of the electrodes of each of the water electrolyzers A and B, and current sensors are connected in series in the loop, so that the control system monitors the working state of the water electrolyzers in real time.

Description

Technical Field

[0001] The present invention relates to the field of new energy, and in particular to a system and method for full-time domain matching of photovoltaic power generation power in series with unequal-volume water electrolyzers. Background Art

[0002] With the development of new energy power generation and hydrogen production technology, the efficiency of new energy power generation and water electrolysis hydrogen production has become a key issue: such as the volatility of photovoltaic power generation, and the load matching problem between the photovoltaic power generation power curve and the water electrolysis hydrogen production process.

[0003] Especially with the current development of photovoltaic power generation technology, the maximum voltage of photovoltaic arrays has reached 1500V, while the current maximum rated voltage of water electrolyzers is around 600V. The problem is how to improve the hydrogen production capacity of water electrolysis and adapt to the increase in photovoltaic array voltage.

[0004] At the same time, the following links also affect the efficiency of hydrogen production by water electrolysis:

[0005] Issues such as the power size of the water electrolyzer, the temperature of the water electrolyzer and the ambient temperature, the photovoltaic power generation efficiency, and the matching degree between the photovoltaic maximum power point and the water electrolyzer power. Summary of the invention

[0006] In order to solve the problem of low matching degree between the photovoltaic water electrolysis hydrogen production process and the photovoltaic power generation full-time domain power curve of the 1000V open-circuit voltage photovoltaic array, and at the same time solve the problems of hydrogen production tank temperature and ambient temperature, photovoltaic power generation comprehensive utilization, etc. that affect the efficiency of water electrolysis hydrogen production. The present invention proposes a full-time domain matching system and method for photovoltaic power generation connected in series with unequal volume water electrolyzers, which directly couples the water electrolysis hydrogen production system through the photovoltaic array, uses unequal volume water electrolyzers in series, improves the power of photovoltaic water electrolysis hydrogen production, as well as the photovoltaic maximum power point output power and the efficient utilization of photovoltaic power generation, and uses heaters + energy storage systems to participate in the regulation of the photovoltaic maximum power point and the optimal hydrogen production matching degree of unequal volume water electrolyzers in series.

[0007] The technical problems solved by the present invention include:

[0008] ① Solve the matching problem between the water electrolysis hydrogen production process and the photovoltaic power generation curve;

[0009] ② Solve the problem of adapting high-voltage photovoltaic arrays to hydrogen production by water electrolysis;

[0010] ③Solve the problem of improving the hydrogen production capacity by water electrolysis;

[0011] ④ Solve the problem of water electrolysis hydrogen production responding to the volatility of photovoltaic power generation;

[0012] ⑤ Issues such as the temperature of the hydrogen production tank and the ambient temperature that affect the efficiency of hydrogen production by water electrolysis, and the comprehensive utilization of photovoltaic power generation.

[0013] The present invention proposes to solve the mismatch problem between the maximum power point directly output by the photovoltaic array and the optimal water electrolysis hydrogen production by directly coupling unequal-volume water electrolyzers in series, utilizing unequal-volume water electrolyzers in series, single water electrolyzers in series with adjustable heaters for photovoltaic power generation maximum power point tracking, water electrolyzers in parallel with adjustable heaters for current diversion, etc., to adapt to the photovoltaic power generation power under different light conditions, as well as the photovoltaic maximum power point output power and the efficient utilization of photovoltaic power generation.

[0014] The technical solution of the present invention is: a full-time domain matching system of photovoltaic power generation in series with unequal-volume water electrolyzers, comprising: a control system, a photovoltaic array, a water electrolyzer group, a heat exchange system, electrodialysis, an adjustable electric heater, an energy storage system and a photovoltaic inverter;

[0015] The water electrolyzer group is composed of a water electrolyzer A and a water electrolyzer B of unequal volumes connected in series, which is the main equipment for photovoltaic water electrolysis hydrogen production, used for electrolysis of water to produce hydrogen, and installed in the photovoltaic water electrolysis hydrogen production device room. The positive electrode of the water electrolyzer A is connected to the positive electrode output by the photovoltaic array, the negative electrode of the water electrolyzer A is connected to the positive electrode of the water electrolyzer B, and the negative electrode of the water electrolyzer B is connected to the negative electrode output by the photovoltaic array. The positive and negative power input ends of an adjustable electric heater are connected in parallel at both ends of each water electrolyzer electrode, which plays the role of current diversion, voltage stabilization, power adjustment of another water electrolyzer, and photovoltaic maximum power tracking. Similarly, voltage sensors are installed in parallel at both ends of each water electrolyzer electrode, and current sensors are connected in series in the loop, and the control system monitors the working status of the water electrolyzer in real time.

[0016] The photovoltaic array is installed around the photovoltaic water electrolysis hydrogen production device to provide energy for water electrolysis hydrogen production; the photovoltaic array output is respectively connected to the water electrolysis cell group, electrodialysis, energy storage system and photovoltaic inverter input terminal.

[0017] The heat exchange system includes: phase change heat storage material, heat exchanger, and radiator, wherein the phase change heat storage material is filled in a sealed box and placed in the photovoltaic water electrolysis hydrogen production device room or other indoor surroundings; the heat exchanger is installed in the phase change heat storage material and the regeneration heater environment. The purpose of the heat exchanger is to release the heat energy of the heat source in the phase change heat storage material through the heat exchangers at different positions.

[0018] The radiator is installed on the wall inside the photovoltaic water electrolysis hydrogen production device. According to the ambient temperature requirements, the temperature of the heat exchanger is switched by a valve to exchange heat to the photovoltaic water electrolysis hydrogen production device room.

[0019] The energy storage system includes: a bidirectional converter and an energy storage battery, which are installed in the photovoltaic water electrolysis hydrogen production device room or other rooms, wherein the capacity of the energy storage system is to maintain the short-term and startup operation requirements of the hydrogen production auxiliary equipment.

[0020] The photovoltaic inverter is installed in the photovoltaic water electrolysis hydrogen production device room or other rooms, mainly providing AC power for water electrolysis hydrogen production auxiliary equipment, including air compressors, water pumps, etc.

[0021] The power input end of the adjustable heater is connected to the positive and negative electrodes of the water electrolyzer. The heating element of the adjustable heater is installed in the phase change material and the molecular sieve dryer respectively. Under the control of the control system, the low-grade temperature of the heating element cooperates with the phase change material to match the excess photovoltaic power generation through the phase change material heat storage, or the high-grade temperature of the heating element is directly used for the regeneration of the water-absorbing resin in the molecular sieve dryer.

[0022] Among them, since the DC power of the adjustable heater is adjustable from 0 to 100%, the greater the power, the higher the temperature of the heating element, and vice versa; the high-grade temperature of the heating element refers to when the adjustable heater works at a certain power, the heating temperature of the heating element is greater than or equal to the regeneration heating temperature, which is used for molecular sieve gas drying; the low-grade temperature of the heating element refers to when the adjustable heater works at low power, the temperature generated by the heating element is lower than the regeneration heating temperature and higher than the melting point of the phase change material, and the heat is absorbed and stored by the phase change material; when drying the molecular sieve gas, the phase change material heat storage is used as the basic temperature, which greatly reduces the regeneration heating power.

[0023] The regeneration heating temperature refers to the heating temperature during the regeneration of the water-absorbing resin in the molecular sieve dryer; the high-grade temperature is greater than the regeneration heating temperature; the low-grade temperature is lower than the regeneration heating temperature.

[0024] The electrodialysis is installed in the photovoltaic water electrolysis hydrogen production device or other indoor surroundings, mainly used for pure water preparation;

[0025] The control system is composed of a controller, various sensors, etc. The sensors are distributed and installed on various devices of the photovoltaic water electrolysis hydrogen production device, mainly collecting all parameters of the water electrolysis hydrogen production device. The input interface of the controller is connected to all sensor output ports through data lines to monitor the operating status of all devices and systems, and execute the corresponding control strategy after analysis and judgment. The output interface of the controller is connected to all actuators and equipment through control lines to control the corresponding equipment to work or stop, so as to realize the efficient operation of photovoltaic water electrolysis hydrogen production.

[0026] The working principle of the present invention is as follows: Photovoltaic electrolysis of water to produce hydrogen is to directly input the DC power generated by the photovoltaic array into the positive and negative ends of the electrolyzer group, and produce oxygen and hydrogen at the positive and negative electrodes of the electrolyzer through DC electrolysis of pure water or electrolyte aqueous solution, and then obtain hydrogen with purity that meets the requirements through the purification link for compression, storage and refueling. Photovoltaic electrolysis of water to produce hydrogen uses renewable energy, without environmental pollution and carbon emissions, so this hydrogen product is called "green hydrogen". Since the typical photovoltaic array output voltage is 1000V, and the maximum rated voltage of the water electrolyzer is about 600V, the present invention uses two water electrolyzers of different capacities in series, and an adjustable heater in parallel with the water electrolyzer has an adjustable power of 0-100%, which is adapted to the photovoltaic power generation power under different light conditions, while increasing the output of hydrogen production.

[0027] In the photovoltaic direct current hydrogen production system with unequal volume water electrolyzers in series, the water electrolyzer groups are water electrolyzer A and water electrolyzer B, which are connected in series. For example, the rated voltage of water electrolyzer A is 600V, and the rated voltage of water electrolyzer B is 400V. Based on the relationship that the photovoltaic maximum power point voltage is about 0.8 times the photovoltaic open circuit voltage, the installed photovoltaic module voltage is (600V+400V) / 0.8=1250V. Based on the local environment latitude, a 1250V open circuit voltage photovoltaic array can be selected.

[0028] When the photovoltaic power generation power is greater than or equal to the lower limit power of water electrolyzer B and less than the lower limit power of water electrolyzer A, water electrolyzer B and the adjustable heater A connected in parallel with water electrolyzer A are started to produce hydrogen. Among them, the adjustable heater A is in a short circuit state.

[0029] As the photovoltaic power generation power increases, the maximum power point of the photovoltaic power generation power changes again. The control system monitors the photovoltaic power generation power and calculates the maximum power point of the photovoltaic power generation power, and controls the adjustable heater A in parallel with the water electrolyzer A to adjust the power so that the adjusted power of the adjustable heater A plus the power of the water electrolyzer B is equal to or close to the maximum power point of the photovoltaic power generation power.

[0030] As the photovoltaic power generation power increases, when the photovoltaic power generation power is greater than the lower limit power of water electrolyzer A and less than the sum of the lower limit power of water electrolyzer A and water electrolyzer B, water electrolyzer B and the adjustable heater A connected in parallel with water electrolyzer A are turned off, and water electrolyzer A and the adjustable heater B connected in parallel with water electrolyzer B are started to produce hydrogen. Among them, the adjustable heater B is in a short-circuit state; the upper limit power of water electrolyzer B is greater than the lower limit power of water electrolyzer A.

[0031] As the photovoltaic power generation power increases, the maximum power point of the photovoltaic power generation power changes again. The control system monitors the photovoltaic power generation power and calculates the maximum power point of the photovoltaic power generation power. It controls the adjustable heater B in parallel with the water electrolyzer B to adjust the power so that the power adjusted by the adjustable heater B plus the power of the water electrolyzer A is equal to or close to the maximum power point of the photovoltaic power generation power.

[0032] When the photovoltaic power generation power is greater than or equal to the sum of the lower limit powers of the two water electrolyzers A and B and less than the sum of the upper limit powers of the two water electrolyzers, the two water electrolyzers are started to work in series and the two adjustable heaters A and B are adjusted to work at the minimum power of 1% to 5%. Through the power adjustment of the two adjustable heaters A and B, the series voltage of the two water electrolyzers A and B is guaranteed to be at the rated 600V and the rated 400V respectively.

[0033] Among them, the upper limit power of water electrolyzer A is greater than the sum of the lower limit powers of the two water electrolyzers A and B. As the photovoltaic power generation power increases, the maximum power point of photovoltaic power generation changes again. The control system monitors the photovoltaic power generation power and calculates the maximum power point of photovoltaic power generation, and controls the adjustable heater A and the adjustable heater B to adjust the power so that the adjusted power of the adjustable heater A and B plus the power of the water electrolyzers A and B are equal to or close to the maximum power point of photovoltaic power generation.

[0034] When the photovoltaic power generation power is greater than or equal to the sum of the upper limit powers of the two water electrolyzers A and B, the two water electrolyzers A and B are maintained to work in series, and the adjustable heaters A and B are adjusted according to the difference between the photovoltaic power generation power and the sum of the upper limit powers of the water electrolyzers A and B. The excess photovoltaic power generation power is converted into thermal energy through the adjustable heater. The high-grade thermal energy is directly used for regeneration heating of the molecular sieve dryer, and the low-grade thermal energy is stored through phase change heat storage to provide the ambient temperature, the basic heating temperature for regeneration of the molecular sieve dryer, etc.

[0035] Since the lower limit power of water electrolyzer B is much greater than the sum of the power of water electrolysis hydrogen production auxiliary equipment, during the period when the photovoltaic power generation power is less than the lower limit power of water electrolyzer B, the corresponding water electrolysis hydrogen production auxiliary equipment is started according to the auxiliary equipment power combination vector P and the auxiliary equipment priority, so as to achieve full time domain matching utilization of photovoltaic power generation power.

[0036] Among them, the auxiliary equipment for hydrogen production by water electrolysis has the characteristics of time-sharing operation and energy storage; priority: in the morning period, electrodialysis, energy storage, air compressor, adjustable heater, etc. in turn; in the afternoon period, adjustable heater, energy storage, air compressor, electrodialysis, etc. in turn.

[0037] 1) Related equipment information:

[0038] (1) Pure water is generally prepared using an electrodialysis device, which is generally 5% of the power of the electrolyzer hydrogen production, with an operating pressure of 0.5-3.0 kg / cm2 and an operating DC voltage of 100-250 V;

[0039] (2) The adjustable range of hydrogen production power of the electrolyzer is 40%-120% for alkaline water and 5%-150% for PEM. After the structure of the water electrolyzer is processed, when the temperature of the electrolyzer is constant, the IV curve of hydrogen production by the water electrolyzer is relatively fixed. Voltage and current sensors are installed on the electrolyzer, and the control system monitors the working power of the electrolyzer in real time;

[0040] (3) Purification stage: The gas produced by the electrolyzer contains a certain amount of humidity, which is heated by a regeneration heater and then dehumidified by a molecular sieve dryer to produce dry hydrogen. The power of the regeneration heater is 10-15% of the power of the electrolyzer hydrogen production;

[0041] (4) Since the efficiency of hydrogen production by water electrolysis is related to temperature, the heater is combined with the phase change material to store the excess photovoltaic power through the phase change material or directly use it for dry hydrogen. The adjustable heater power is adjustable from 0 to 100%.

[0042] The power output of the photovoltaic cell is related to the amount of sunlight that hits the solar panel, and the efficiency is related to the electronic characteristics of the load. When the sunlight changes, the load curve of the maximum power transmission efficiency of the photovoltaic cell also changes accordingly. The maximum power output is achieved through load coordination and adjustment, and the system obtains the best efficiency. After the photovoltaic array is installed, under the condition of a certain temperature (without considering attenuation), the photovoltaic power generation light output IV curve is relatively fixed, and the maximum power point of photovoltaic power generation is fixed, so that the power generation efficiency is highest when the load characteristics are maintained at this power point.

[0043] Since the water electrolysis hydrogen production cell requires a high-power DC power supply during the hydrogen production process, the use of solar photovoltaic + DC / DC converter to output power at the maximum power point can achieve water electrolysis hydrogen production, but the loss in the conversion process is large and the cost is high. Therefore, the photovoltaic array direct water electrolysis hydrogen production is proposed.

[0044] 2) Design of optimal matching between the volt-ampere characteristics of the electrolytic cell and the maximum power operation characteristics of the photovoltaic array:

[0045] After the water electrolyzer structure is processed, when the temperature of the electrolyzer is constant, the IV curve of hydrogen production by the water electrolyzer is relatively fixed, the power required in the hydrogen production process ranges from 40% to 120%, and the relative voltage is relatively stable. In order to adapt to the installation of typical photovoltaic arrays, the voltage of the photovoltaic array can be referred to when designing the water electrolyzer, and two electrolyzers with unequal water capacities and equal currents are connected in series. The electrolyzer power, upper and lower power limits, and photovoltaic power generation maximum power point tracking are adjusted through adjustable heaters, so that the maximum power curve of the photovoltaic array under different illumination conditions coincides with the corresponding volt-ampere characteristics of the electrolyzer, achieving a relative best match.

[0046] Therefore, it is possible to use photovoltaic arrays to directly power the water electrolysis hydrogen production tank. In order to meet the system's efficient hydrogen production, the load of auxiliary equipment is adjusted by time-sharing and dynamic allocation during the hydrogen production process, so as to achieve the fitting of the photovoltaic power generation maximum power curve and the water electrolysis hydrogen production process curve, and ensure the efficiency of photovoltaic power generation hydrogen production.

[0047] The present invention is based on the improved hydrogen production process and the photovoltaic power generation power full time domain matching utilization method of the unequal volume water electrolyzer series connection as follows:

[0048] Step 1: Parameter setting

[0049] (1) Since the output voltage of a typical photovoltaic array is 1000V, and the maximum rated voltage of a water electrolyzer is about 600V, the present invention uses two unequal-capacity water electrolyzers A and B in series, and a 0-100% power adjustable heater connected in parallel with the water electrolyzer to adapt to the photovoltaic power generation power under different light conditions.

[0050] In the photovoltaic hydrogen production system with unequal volume water electrolyzers connected in series, the water electrolyzer group is composed of a water electrolyzer A and a water electrolyzer B connected in series.

[0051] Among them, the electrical parameters of water electrolyzer A are: rated power P a , Rated voltage U a , Rated current I a ; Electrical parameters of water electrolyzer B: Rated power P b , Rated voltage U b , Rated current I a Among them, the rated current I a With rated current I b Equal, that is, I a =I b ; Water electrolyzer A rated power P a Greater than the rated power P of water electrolyzer B b , that is, P a >P b ; The upper limit power of water electrolyzer B is greater than the lower limit power of water electrolyzer A; The upper limit power of water electrolyzer A is greater than the sum of the lower limit powers of water electrolyzer A and water electrolyzer B.

[0052] (2) Define the power ratio coefficient δ under different conditions;

[0053] Considering the optimal efficiency range of the water electrolysis hydrogen production system (hydrogen production efficiency of water electrolyzer), the power ratio coefficient δ under different conditions is defined as:

[0054] ① Hydrogen production power P of water electrolyzer A a The adjustable heater B power P connected in series br The sum of the photovoltaic maximum power point P MPPT The ratio of

[0055] ② Hydrogen production power P of water electrolyzer B b The adjustable heater A power P connected in series ar The sum of the photovoltaic maximum power point P MPPT The ratio of

[0056] ③ Hydrogen production power P of water electrolyzer A a , adjustable heater A power P ar 、Hydrogen production power P of water electrolyzer B b , adjustable heater B power P br The sum of the photovoltaic maximum power point P MPPT The ratio of

[0057] Among them, δ is the power ratio coefficient, and the value range of δ≤1 is 0.8~1.

[0058] (3) Define the power combination vector P of the auxiliary equipment for water electrolysis hydrogen production;

[0059] The control system converts the electrodialysis power P s 、Energy storage system charging power P c , air compressor compressed gas power P g , Regeneration heater power P k The start and stop states of the auxiliary equipment are encoded by binary numbers to generate the auxiliary equipment operation state matrix, which is then combined with the electrodialysis power P s 、Energy storage system charging power P c , air compressor power P g , Regeneration heater power P k The power vectors of the auxiliary equipment composed are multiplied to generate a complete enumeration of the power combination vector P of the auxiliary equipment of the water electrolysis hydrogen production device.

[0060]

[0061] Among them, P x ∈P.

[0062] (4) Priority for accessory equipment;

[0063] As the auxiliary equipment for hydrogen production by water electrolysis has the characteristics of time-sharing operation and energy storage, its priority in different time periods is: in the morning period, electrodialysis, energy storage, air compressor, adjustable heater, etc.;

[0064] In the afternoon, the heater, energy storage, air compressor, electrodialysis, etc. can be adjusted in sequence.

[0065] (5) Definition of high and low grade temperatures;

[0066] Since the DC power of the adjustable heater is adjustable from 0 to 100%, the greater the power, the higher the temperature of the heating element, and vice versa; the high-grade temperature of the heating element refers to the heating temperature of the heating element greater than or equal to the regeneration heating temperature when the adjustable heater works at a certain power, which is used for molecular sieve gas drying; the low-grade temperature of the heating element refers to the temperature generated by the heating element when the adjustable heater works at low power, which is lower than the regeneration heating temperature and higher than the melting point of the phase change material, and the heat is absorbed and stored by the phase change material; when drying the molecular sieve gas, the phase change material heat storage is used as the basic temperature to greatly reduce the regeneration heating power. Among them, the regeneration heating temperature refers to the heating temperature when the water-absorbing resin in the molecular sieve dryer is regenerated; the high-grade temperature is greater than or equal to the regeneration heating temperature; the low-grade temperature is lower than the regeneration heating temperature.

[0067] Step 2: Full-time domain matching control method for photovoltaic power generation power connected in series with unequal-capacity water electrolyzers

[0068] (1) When P b_min ≤P v <P a_min Considering the optimal efficiency range of photovoltaic water electrolysis hydrogen production system, according to the power ratio coefficient Thus we get P ar =δP MPPT -P b ,δI MPPT ×U MPPT =I ar U ar +I b U b ,because Simplified to get δ×U MPPT -U b =U ar , thus through P ar =I MPPT U ar The calculation results show that the heater A adjusts the power P ar Plus the water electrolyzer B power P b Equal to or close to the maximum power point P of photovoltaic power generation MPPT ,Right now

[0069] (2) When P a_min <P v <P a_min +P b_min When the water electrolyzer B and the adjustable heater A are turned off, the water electrolyzer A and the adjustable heater B are started to produce hydrogen.

[0070] Since the water electrolyzer A is connected in series with the adjustable heater B and powered by photovoltaic power generation, the power P of the adjustable heater B is br Adjust, change the current I of the adjustable heater B br and voltage U br ,make Considering the optimal efficiency range of photovoltaic water electrolysis hydrogen production system, according to the power ratio coefficient Thus we get P br =δP MPPT -P a and δI MPPT ×U MPPT =I br U br +I a U a .

[0071] Simplified to get δ×U MPPT -U a =U br , thus through P br =I MPPT U br The calculation of heater B adjustment power P is obtained. br Plus the water electrolyzer A power P a Equal to or close to the maximum power point P of photovoltaic power generation MPPT ,Right now

[0072] (3) When P a_min +P b_min <P v <P a_max +P b_max When water electrolyzer A and water electrolyzer B are started to work in series, due to I ar +I a =I br +I b By controlling the power of the adjustable heater,

[0073] Ignore the effect of current change on voltage change of water electrolyzer, and use the voltage U of water electrolyzer A as the basis a and water electrolyzer B voltage U b , respectively calculate the power P of the adjustable heater A ar =Ua I ar and the power P of the adjustable heater B br =U b I br .

[0074] As the photovoltaic power generation power P v The increase of photovoltaic power generation power maximum power point P MPPT Considering the optimal efficiency range of the water electrolysis hydrogen production system, according to the power ratio coefficient δ, we can get

[0075] when When the load power of adjustable heater A and adjustable heater B is adjusted, From this calculation, P br +P ar =δP MPPT -P b -P a , due to I ar +I a =I br +I b , where I ar < a ,I br < b , so I ar ≈I br Approximately equal, the current expression of the series circuit of adjustable heater A and adjustable heater B is obtained:

[0076] For the convenience of calculation, the influence of the current change on the voltage change of the water electrolyzer is ignored, and the voltage U of the water electrolyzer A is used as the a and water electrolyzer B voltage U b , respectively calculate the power P of the adjustable heater A ar =U a I ar and the power P of the adjustable heater B br =U b I br .

[0077] (4) When When two water electrolyzers are connected in series, the incremental current △I is calculated based on the sampling period of the control system. ar =△I br =△I abr =I abr_t2 -I abr_t1 When the control system executes the next sampling cycle, it controls the two adjustable heaters to be connected in series with a current of I ar =I br =I​​abr_t2 +△I abr , considering the optimal efficiency range of the water electrolysis hydrogen production system, we get I arn =I brn =δ(I abr_t2 +△I abr ).

[0078] And according to the voltage U across the water electrolyzer A a The voltage U across the water electrolyzer B b , respectively calculate the power P of the adjustable heater A in the next execution cycle ar =U a I arn and the power P of the adjustable heater B br =U b I brn .

[0079] The control system adjusts the adjustable heater A power P accordingly based on this power control ar and adjustable heater B power P br , so that the adjustable heater A power P ar With adjustable heater B power P br With water electrolyzer A power P a With water electrolyzer B power P b The sum is equal to or close to the maximum power point P of photovoltaic power generation MPPT ,Right now

[0080] Thus, the excess photovoltaic power is converted into thermal energy through the adjustable heater. The high-grade thermal energy is directly used for the regeneration heating of the molecular sieve dryer, and the low-grade thermal energy is stored through phase change heat storage to provide the ambient temperature, the basic heating temperature for the regeneration of the molecular sieve dryer, etc.

[0081] Among them, P v is the photovoltaic power generation power; U MPPT I is the maximum power point voltage of photovoltaic power generation; MPPT is the maximum power point current of photovoltaic power generation; U v is the photovoltaic power generation output voltage; P ar Adjust the power of the adjustable heater A; P MPPT is the maximum power point of photovoltaic power generation; P b_min is the lower limit power of water electrolyzer B; P a is the rated power of water electrolyzer A; P a_min is the lower limit power of water electrolyzer A; δ is the power ratio coefficient, δ≤1 ranges from 0.8 to 1; I arn is the current of the adjustable heater A in the next execution cycle; I brn is the current of the adjustable heater B in the next execution cycle; Iabr_t2 I is the current of the two adjustable heaters in series at the current moment; abr_t1 is the series current of the two adjustable heaters at the previous moment; △I ar is the incremental current of the adjustable heater A; △I br is the incremental current of the adjustable heater B; △I abr It is the incremental current of adjustable heater A and adjustable heater B in series.

[0082] (5) When P b_min >P c +P g +P s +P k The power combination vector P and priority of the water electrolysis hydrogen production auxiliary equipment are controlled in real time, and the corresponding water electrolysis hydrogen production auxiliary equipment is started to work, so as to achieve the full time domain matching utilization of photovoltaic power generation.

[0083] Among them, the auxiliary equipment for hydrogen production by water electrolysis has the characteristics of time-sharing operation and energy storage;

[0084] Priority: In the morning, electrodialysis, energy storage, air compressor, adjustable heater, etc.; in the afternoon, adjustable heater, energy storage, air compressor, electrodialysis, etc.

[0085] The specific control process is as follows:

[0086] (1) When P b_min ≤P v <P a_min When the water electrolyzer B produces hydrogen and the adjustable heater A regulates and matches the maximum power of photovoltaic power generation;

[0087] When the photovoltaic power generation power P v Greater than or equal to rated power P b The lower limit power P of water electrolyzer B b_min , less than the rated power P a The lower limit power P of water electrolyzer A a_min That is, P b_min ≤P v <P a_min When the water electrolyzer B and the adjustable heater A connected in parallel with the water electrolyzer A are started to produce hydrogen. Among them, the adjustable heater A is in a short-circuit state. At this time, the photovoltaic power generation power P v Act directly on water electrolyzer B.

[0088] As the photovoltaic power generation power P v The increase of photovoltaic power generation power P v Power the series circuit between water electrolyzer B and adjustable heater A. The voltage of water electrolyzer B is U b With adjustable heater A voltage U ar The sum of the series voltages is equal to the photovoltaic power generation voltage Uv , that is U b +U ar =U v . The current of water electrolyzer B is I b , adjustable heater A current I ar and photovoltaic power generation current I v Equal, that is, I ar =I b =I v .

[0089] At this time, the maximum power point of photovoltaic power generation is P MPPT changes, the control system monitors the photovoltaic power generation power P v , and calculate the maximum power point P of photovoltaic power generation MPPT =I MPPT *U MPPT .

[0090] Due to the process of water electrolysis tank B, the voltage U across the water electrolysis tank B b Relatively fixed, in order to ensure the best efficiency of photovoltaic water electrolysis hydrogen production system, the voltage U b With adjustable heater A voltage U ar The sum of the series voltages is equal to the maximum power point voltage U of photovoltaic power generation MPPT , that is U b +U ar =U MPPT .

[0091] Considering the optimal efficiency range of the photovoltaic water electrolysis hydrogen production system, let the hydrogen production power of water electrolyzer B be P b The adjustable heater A power P connected in series ar The sum of the photovoltaic maximum power point P MPPT The ratio is equal to or close to the power ratio coefficient δ, that is, Thus we get P ar =δP MPPT -P b and δI MPPT ×U MPPT =I ar U ar +I b U b .

[0092] Since the water electrolyzer B is connected in series with the adjustable heater A and powered by photovoltaic power generation, the power P of the adjustable heater A is ar Adjust, change the current I of the adjustable heater A ar and voltage U ar , so that the series current of the water electrolyzer B and the adjustable heater A approaches the maximum power point current I of the photovoltaic power generation MPPT ,Right now δIMPPT ×U MPPT =I ar U ar +I b U b Simplified to get the maximum power point voltage U of photovoltaic power generation MPPT The product of the power ratio coefficient δ minus the voltage U of the water electrolyzer B b Equal to adjustable heater A voltage U ar , that is, δ×U MPPT -U b =U ar , thus the maximum power point current I MPPT With adjustable heater A voltage U ar The product of ar =I MPPT U ar The calculation results show that the heater A adjusts the power P ar Plus the water electrolyzer B power P b Equal to or close to the maximum power point P of photovoltaic power generation MPPT ,Right now

[0093] Among them, P v is the photovoltaic power generation power; U MPPT I is the maximum power point voltage of photovoltaic power generation; MPPT is the maximum power point current of photovoltaic power generation; U v is the photovoltaic power generation output voltage; P ar Adjust the power of the adjustable heater A; P MPPT is the maximum power point of photovoltaic power generation; P b_min is the lower limit power of water electrolyzer B; P a is the rated power of water electrolyzer A; P a_min is the lower limit power of water electrolyzer A.

[0094] (2) When P a_min <P v <P a_min +P b_min When water electrolyzer produces hydrogen, water electrolyzer A produces hydrogen and adjustable heater B regulates and matches the maximum power of photovoltaic power generation;

[0095] As the photovoltaic power generation continues to increase, when the photovoltaic power generation power P v Greater than the lower power limit P of water electrolyzer A a_min , which is less than the lower power limit P of water electrolyzer A a_min The lower power P of water electrolyzer B b_min The sum of the lower power limits of the two water electrolyzers, i.e. P a_min <P v <P a_min+P b_min When the water electrolyzer B and the adjustable heater A connected in parallel with the water electrolyzer A are turned off, the water electrolyzer A and the adjustable heater B connected in parallel with the water electrolyzer B are started to produce hydrogen. Among them, the adjustable heater B is in a short-circuit state; the upper limit power P of the water electrolyzer B b_max Greater than the lower power limit P of water electrolyzer A a_min .

[0096] Among them, P v is the photovoltaic power generation power; P b is the rated power of water electrolyzer B; P b_min is the lower limit power of water electrolyzer B; P a is the rated power of water electrolyzer A; P a_min is the lower limit power of water electrolyzer A; U a is the rated voltage of water electrolyzer A; U br is the voltage across the adjustable heater B; U v is the voltage of photovoltaic power generation at a certain moment;

[0097] As the photovoltaic power generation power P v The increase of photovoltaic power generation power P v Power the series circuit between water electrolyzer A and adjustable heater B. The voltage of water electrolyzer A is U a With adjustable heater A voltage U br The sum of the series voltages is equal to the photovoltaic power generation voltage U v , that is U a +U br =U v . The current of water electrolyzer A is I a , adjustable heater B current I br and photovoltaic power generation current I v Equal, that is, I br =I a =I v .

[0098] At this time, the maximum power point of photovoltaic power generation is P MPPT changes, the control system monitors the photovoltaic power generation power P v , and calculate the maximum power point P of photovoltaic power generation MPPT =I MPPT *U MPPT .

[0099] Due to the process of water electrolysis tank A, the voltage U across the water electrolysis tank A a Relatively fixed, in order to ensure the best efficiency of photovoltaic water electrolysis hydrogen production system, the water electrolyzer A voltage U a With adjustable heater B voltage U br The sum of the series voltages is equal to the maximum power point voltage U of photovoltaic power generation MPPT, that is U a +U br =U MPPT .

[0100] Considering the optimal efficiency range of the photovoltaic water electrolysis hydrogen production system, the hydrogen production power P of the water electrolyzer A is a The adjustable heater B power P connected in series br The sum of the photovoltaic maximum power point P MPPT The ratio is equal to or close to the power ratio coefficient δ, that is, Thus we get P br =δP MPPT -P a and δI MPPT ×U MPPT =I br U br +I a U a .

[0101] Since the water electrolyzer A is connected in series with the adjustable heater B and powered by photovoltaic power generation, the power P of the adjustable heater B is br Adjust, change the current I of the adjustable heater B br and voltage U br , so that the series current of the water electrolyzer A and the adjustable heater B approaches the maximum power point current I of the photovoltaic power generation MPPT ,Right now δI MPPT ×U MPPT =I br U br +I a U a Simplified to get the maximum power point voltage U of photovoltaic power generation MPPT The product of the power ratio coefficient δ minus the voltage U of the water electrolyzer A a Equal to adjustable heater B voltage U br , that is, δ×U MPPT -U a =U br , thus the maximum power point current I MPPT With adjustable heater B voltage U br The product of br =I MPPT U br The calculation of heater B adjustment power P is obtained. br Plus the water electrolyzer A power P a Equal to or close to the maximum power point P of photovoltaic power generation MPPT ,Right now

[0102] P br Adjust the power of the adjustable heater B; PMPPT is the maximum power point of photovoltaic power generation; P b_min is the lower limit power of water electrolyzer B; P a is the rated power of water electrolyzer A; P a_min is the lower limit power of water electrolyzer A.

[0103] (3) When P a_min +P b_min <P v <P a_max +P b_max When water electrolyzers A and B produce hydrogen and adjustable heaters A and B are regulated to match the maximum power of photovoltaic power generation;

[0104] When the photovoltaic power generation power P v Greater than or equal to the sum of the lower power limits of the two water electrolyzers and less than the sum of the upper power limits of the two water electrolyzers, that is, P a_min +P b_min <P v <P a_max +P b_max When , water electrolyzer A and water electrolyzer B are started to work in series. At this time, the series voltage of water electrolyzer A and water electrolyzer B increases. Since the photovoltaic maximum power point voltage is approximately equal to 0.8 times the photovoltaic open circuit voltage, the photovoltaic maximum power point voltage may be lower than the series voltage of water electrolyzer A and water electrolyzer B. Since adjustable heater A and adjustable heater B are connected in parallel with water electrolyzer A and water electrolyzer B respectively, there is an adjustable heater A current I ar With water electrolyzer A current I a The sum is equal to the adjustable heater B current I br With water electrolyzer B current I b The sum of I ar +I a =I br +I b Thus, by controlling the power of the adjustable heater, the adjustable heater A current I ar Or adjustable heater B current I br Absorb or release photovoltaic power generation current, so that the current approaches the photovoltaic maximum power point current I MPPT ,Right now Due to the process of water electrolyzer, the voltage of water electrolyzer is relatively fixed, but it changes with the change of current. Therefore, by shunting water electrolyzer A or water electrolyzer B, the series voltage of water electrolyzer A and water electrolyzer B changes and approaches the maximum power point voltage U of photovoltaic. MPPT ,Right now

[0105] For the convenience of calculation, the influence of the current change on the voltage change of the water electrolyzer is ignored, and the voltage U of the water electrolyzer A is used as the a and water electrolyzer B voltage Ub , respectively calculate the power P of the adjustable heater A ar =U a I ar and the power P of the adjustable heater B br =U b I br .

[0106] Among them, the upper limit power P of water electrolyzer A a_max Greater than the lower power limit P of water electrolyzer B b_min The lower power P of water electrolyzer A a_min The sum of P b_min +P a_min <P a_max .

[0107] As the photovoltaic power generation power P v The increase of photovoltaic power generation power maximum power point P MPPT During the change, the control system monitors the photovoltaic power generation power P v , and calculate the maximum power point P of photovoltaic power generation MPPT =I MPPT ×U MPPT , control the adjustable heater A to adjust the power P ar , adjustable heater B adjusts power P br Considering the optimal efficiency range of the water electrolysis hydrogen production system (hydrogen production efficiency of water electrolysis cell), the hydrogen production power P of water electrolysis cell A is a , adjustable heater A power P ar 、Hydrogen production power P of water electrolyzer B b , adjustable heater B power P br The sum of the photovoltaic maximum power point P MPPT The ratio should be close to the power ratio coefficient δ, that is,

[0108] Therefore, when the hydrogen production power P of water electrolyzer A a , adjustable heater A power P ar 、Hydrogen production power P of water electrolyzer B b , adjustable heater B power P br The sum of the maximum power point of photovoltaic power generation P MPPT The ratio is less than the power ratio coefficient δ, that is, When the load power of adjustable heater A and adjustable heater B is adjusted, the hydrogen production power P of water electrolyzer A is a , adjustable heater A power P ar 、Hydrogen production power P of water electrolyzer B b , adjustable heater B power P br The sum of the maximum power point of photovoltaic power generation P MPPTThe ratio approaches the power ratio coefficient δ, that is,

[0109] Since the adjustable heater A and the adjustable heater B are connected in parallel with the water electrolyzer A and the water electrolyzer B respectively, the adjustable heater A current I ar With water electrolyzer A current I a The sum is equal to the adjustable heater B current I br With water electrolyzer B current I b The sum of I ar +I a =I br +I b Since the adjustable heater A current I ar and adjustable heater B current I br The series current is much smaller than the water electrolyzer A current I a and water electrolyzer B current I b The series current, I ar < a ,I br < b .

[0110] The heater A current I can be adjusted accordingly ar and adjustable heater B current I br Approximately equal, that is, I ar ≈I br , through P br +P ar =δP MPPT -P b -P a Formula and maximum power point voltage U MPPT The ratio of the adjustable heater A and the adjustable heater B series circuit current expression is obtained:

[0111] For the convenience of calculation, the influence of the current change on the voltage change of the water electrolyzer is ignored, and the voltage U of the water electrolyzer A is used as the a and water electrolyzer B voltage U b , respectively calculate the power P of the adjustable heater A ar =U a I ar and the power P of the adjustable heater B br =U b I br .

[0112] The control system adjusts the adjustable heater A power P accordingly based on this power control ar and adjustable heater B power P br , so that the adjustable heater A power P ar With adjustable heater B power P​​br With water electrolyzer A power P a With water electrolyzer B power P b The sum is equal to or close to the maximum power point P of photovoltaic power generation MPPT ,Right now

[0113] Among them, δ is the power ratio coefficient, δ≤1 ranges from 0.8 to 1; P ar is the adjustable heater A power; P br is the power of adjustable heater B; P a is the power of water electrolyzer A; P b is the power of water electrolyzer B; U a is the voltage across the water electrolyzer A; U b is the voltage across the water electrolyzer B; I ar is the adjustable heater A current; I br is the current of adjustable heater B; P a_max is the upper limit power of water electrolyzer A; P a_min is the lower limit power of water electrolyzer A; P b_max is the upper limit power of water electrolyzer B; P b_min is the lower limit power of water electrolyzer B; U MPPT P is the photovoltaic maximum power point tracking voltage; MPPT is the maximum power point of photovoltaic.

[0114] (4) When When water electrolyzers A and B produce hydrogen and adjustable heaters A and B are regulated to match the maximum power of photovoltaic power generation;

[0115] When the photovoltaic power generation power P v Approaching the sum of the upper power limits of the two water electrolyzers, that is, When the two water electrolyzers are maintained in series operation, the current I of the two adjustable heaters in series will be adjusted according to the sampling cycle of the control system. abr_t2 , minus the series current I of the two adjustable heaters at the previous moment abr_t1 , and get the incremental current △I ar =△I br =△I abr =I abr_t2 -I abr_t1 When the control system executes the next sampling cycle, it controls the two adjustable heaters to be connected in series with a current of I ar =I br =I abr_t2 +△I abr , while considering the optimal efficiency range of the water electrolysis hydrogen production system (hydrogen production efficiency of water electrolysis cell), connect two adjustable heaters in series with the current I ar =I br =I abr_t2+△I abr Multiply by the power ratio coefficient δ to get I arn =I brn =δ(I abr_t2 +△I abr ).

[0116] And according to the voltage U across the water electrolyzer A a The voltage U across the water electrolyzer B b , respectively calculate the power P of the adjustable heater A in the next execution cycle ar =U a I arn and the power P of the adjustable heater B br =U b I brn The control system adjusts the adjustable heater A power P accordingly based on this power control. ar and adjustable heater B power P br , so that the adjustable heater A power P ar With adjustable heater B power P br With water electrolyzer A power P a With water electrolyzer B power P b The sum is equal to or close to the maximum power point P of photovoltaic power generation MPPT ,Right now

[0117] Thus, the excess photovoltaic power is converted into thermal energy through the adjustable heater. The high-grade thermal energy is directly used for the regeneration heating of the molecular sieve dryer, and the low-grade thermal energy is stored through phase change heat storage to provide the ambient temperature, the basic heating temperature for the regeneration of the molecular sieve dryer, etc.

[0118] Where δ is the power ratio coefficient, δ≤1 ranges from 0.8 to 1; I arn is the current of the adjustable heater A in the next execution cycle; I brn is the current of the adjustable heater B in the next execution cycle; I abr_t2 I is the current of the two adjustable heaters in series at the current moment; abr_t1 is the series current of the two adjustable heaters at the previous moment; △I ar is the incremental current of the adjustable heater A; △I br is the incremental current of the adjustable heater B; △I abr It is the incremental current of adjustable heater A and adjustable heater B in series.

[0119] (5)P b_min >P c +P g +P s +P kControl the power combination vector P and priority of the auxiliary equipment for water electrolysis hydrogen production to match the maximum power of photovoltaic power generation;

[0120] Since the lower limit power P of water electrolyzer B b_min Greater than the sum of the power of the auxiliary equipment for hydrogen production by water electrolysis, that is, P b_min >P c +P g +P s +P k , in the photovoltaic power generation power P v Less than the lower power limit P of water electrolyzer B b_min During this time period, the controller starts the corresponding water electrolysis hydrogen production auxiliary equipment according to the auxiliary equipment power combination vector P and the auxiliary equipment priority, thus achieving full time domain matching utilization of photovoltaic power generation.

[0121] Among them, the auxiliary equipment for hydrogen production by water electrolysis has the characteristics of time-sharing operation and energy storage;

[0122] Priority: In the morning, electrodialysis, energy storage, air compressor, adjustable heater, etc.; in the afternoon, adjustable heater, energy storage, air compressor, electrodialysis, etc.

[0123] Among them, P s To control the electrodialysis power; P c Charging power for energy storage system; P g P is the power of compressed gas by air compressor; k is the power of the regeneration heater; P is the power combination vector of the auxiliary equipment of the water electrolysis hydrogen production device.

[0124] Beneficial effects:

[0125] ① Since the voltage of the water electrolyzer is lower than 600V, the output voltage of 1000V can be adapted to the current mainstream photovoltaic array installation in the market by connecting unequal-capacity water electrolyzers in series;

[0126] ② Due to the volatility of photovoltaic power generation, the combination of unequal volume water electrolyzers and adjustable heaters, with the cooperation of electrodialysis, energy storage, air compressors and other auxiliary equipment, can achieve photovoltaic power generation characteristics under different light conditions and the corresponding water electrolyzer electrolysis hydrogen production characteristics, adjustable heaters and auxiliary equipment load matching, avoid the reduction of water electrolyzer electrolysis hydrogen production efficiency and photovoltaic energy loss due to photovoltaic power generation fluctuations, and ensure the maximization of photovoltaic power generation and electrolysis hydrogen production. BRIEF DESCRIPTION OF THE DRAWINGS

[0127] Figure 1 The structural diagram of the full-time domain matching system of the unequal-capacity water electrolyzers connected in series with photovoltaic power generation in the present invention;

[0128] Figure 2 The photovoltaic array of the present invention is a schematic diagram of power supply for hydrogen production by series water electrolysis;

[0129] Figure 3 Schematic diagram of the series-parallel connection of the photovoltaic array, water electrolyzer and adjustable heater of the present invention;

[0130] Figure 4 The water electrolyzer power of the present invention is matched with the photovoltaic power curve. DETAILED DESCRIPTION

[0131] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0132] like Figure 1 , Figure 2 and Figure 3 As shown, according to one embodiment of the present invention, a full-time domain matching system for unequal-volume water electrolyzers connected in series with photovoltaic power generation is proposed, comprising: a control system, a photovoltaic array, a water electrolyzer group, a heat exchange system, electrodialysis, an adjustable electric heater, an energy storage system and a photovoltaic inverter;

[0133] like Figure 3 As shown, the water electrolyzer group is composed of a water electrolyzer A and a water electrolyzer B of unequal volumes connected in series, which is the main equipment for photovoltaic water electrolysis hydrogen production, used for electrolysis of water to produce hydrogen, and installed in the photovoltaic water electrolysis hydrogen production device room. The positive electrode ETA+ of the water electrolyzer A is connected to the positive electrode PV+ output of the photovoltaic array, the negative electrode ETA- of the water electrolyzer A is connected to the positive electrode ETB+ of the water electrolyzer B, and the negative electrode ETB- of the water electrolyzer B is connected to the negative electrode PV- output of the photovoltaic array. The positive electrode ETA+ and the negative electrode ETA- of the water electrolyzer A are connected in parallel to the positive electrode HtrA+ and the negative electrode HtrA- of the power supply of the adjustable electric heater A; the positive electrode ETB+ and the negative electrode ETB- of the water electrolyzer B are connected in parallel to the positive electrode HtrB+ and the negative electrode HtrB- of the power supply of the adjustable electric heater B, which play the role of shunting the water electrolyzer, stabilizing the voltage, adjusting the power of another water electrolyzer, and tracking the maximum power of photovoltaics. Similarly, voltage sensors are installed in parallel at both ends of each water electrolyzer electrode, and current sensors are connected in series in the loop. The control system monitors the working status of the water electrolyzer in real time.

[0134] The photovoltaic array is installed around the photovoltaic water electrolysis hydrogen production device to provide energy for water electrolysis hydrogen production; the positive electrode PV+ and negative electrode PV- outputs of the photovoltaic array are respectively connected to the input ends of the water electrolyzer group (positive electrode ETA+ and negative electrode PV-), electrodialysis, energy storage system and photovoltaic inverter.

[0135] The heat exchange system includes: phase change heat storage material, heat exchanger, and radiator. The phase change heat storage material is filled in a sealed box and placed in the photovoltaic water electrolysis hydrogen production device room or other indoor surroundings; the heat exchanger is installed in the phase change heat storage material and the regeneration heater environment respectively. The purpose of the heat exchanger is to release the heat energy of the heat source in the phase change heat storage material through the heat exchangers at different positions.

[0136] The radiator is installed on the wall inside the photovoltaic water electrolysis hydrogen production device. According to the ambient temperature requirements, the temperature of the heat exchanger is switched by a valve to exchange heat to the photovoltaic water electrolysis hydrogen production device room.

[0137] The energy storage system includes: a bidirectional converter and an energy storage battery, which are installed in the photovoltaic water electrolysis hydrogen production device room or other rooms, wherein the capacity of the energy storage system is to maintain the short-term and startup operation requirements of the hydrogen production auxiliary equipment.

[0138] The photovoltaic inverter is installed in the photovoltaic water electrolysis hydrogen production device room or other rooms, mainly providing AC power for water electrolysis hydrogen production auxiliary equipment, including air compressors, water pumps, etc.

[0139] The positive and negative input terminals of the adjustable heater are connected to the positive and negative electrodes of the corresponding water electrolyzer. The heating element of the adjustable heater is installed in the phase change material and the molecular sieve dryer respectively. Under the control of the control system, the low-grade temperature of the heating element cooperates with the phase change material to store the excess photovoltaic power through the phase change material, or the high-grade temperature of the heating element is directly used for the regeneration of the water-absorbing resin in the molecular sieve dryer.

[0140] Among them, since the DC power of the adjustable heater is adjustable from 0 to 100%, the greater the power, the higher the temperature of the heating element, and vice versa; the high-grade temperature of the heating element refers to when the adjustable heater works at a certain power, the heating temperature of the heating element is greater than or equal to the regeneration heating temperature, which is used for drying molecular sieve gas; the low-grade temperature of the heating element refers to when the adjustable heater works at a low power, the temperature generated by the heating element is lower than the regeneration heating temperature and higher than the melting point of the phase change material, and the heat is absorbed and stored by the phase change material; when drying the molecular sieve gas, the phase change material heat storage is used as the basic temperature to greatly reduce the regeneration heating power. The regeneration heating temperature refers to the heating temperature when the water-absorbing resin in the molecular sieve dryer is regenerated; the high-grade temperature is greater than the regeneration heating temperature; the low-grade temperature is lower than the regeneration heating temperature. The electrodialysis is installed in the photovoltaic water electrolysis hydrogen production device room or other indoor surroundings, and is mainly used for pure water preparation;

[0141] The control system is composed of a controller, various sensors, etc. The sensors are distributed and installed on various devices of the photovoltaic water electrolysis hydrogen production device, and mainly collect all parameters of the water electrolysis hydrogen production device; the controller is installed in the photovoltaic water electrolysis hydrogen production device or on the control cabinet, and the input interface of the controller is connected to all sensor output ports through a data line to monitor the operating status of all equipment and systems, and execute the corresponding control strategy after analysis and judgment. The output interface of the controller is connected to all actuators, equipment, etc. through a control line to control the corresponding equipment to work or stop, so as to realize the efficient operation of photovoltaic water electrolysis hydrogen production.

[0142] The basic hydrogen production process of the present invention and the photovoltaic power generation curve matching control process are as follows: Figure 4 shown.

[0143] 1) Parameter settings

[0144] (1) Since the output voltage of a typical photovoltaic array is 1000V, and the maximum rated voltage of a water electrolyzer is about 600V, the present invention uses two water electrolyzers of different capacities connected in series, and an adjustable heater connected in parallel with the water electrolyzer with an adjustable power of 0 to 100% to adapt to the photovoltaic power generation power under different light conditions.

[0145] In the photovoltaic direct current hydrogen production system in which unequal volume water electrolyzers are connected in series, the water electrolyzer group is composed of a water electrolyzer A and a water electrolyzer B connected in series.

[0146] Among them, the electrical parameters of water electrolyzer A are: rated power P a , Rated voltage U a , Rated current I a ; Electrical parameters of water electrolyzer B: Rated power P b , Rated voltage U b , Rated current I a Among them, the rated current I a With rated current I b Equal, that is, I a =I b ; Water electrolyzer A rated power P a Greater than the rated power P of water electrolyzer B b , that is, P a >P b ; Upper limit power P of water electrolyzer B b_max Greater than the lower power limit P of water electrolyzer A a_min That is, P b_max >P a_min ; Upper limit power P of water electrolyzer A a_max Greater than the sum of the lower power limits of water electrolyzer A and water electrolyzer B, that is, P a_min +P b_min <P a_max .

[0147] Among them, P v is the photovoltaic power generation power; U MPPT I is the maximum power point voltage of photovoltaic power generation; MPPT is the maximum power point current of photovoltaic power generation; U v is the photovoltaic power generation output voltage; P ar Adjust the power of the adjustable heater A; P MPPT is the maximum power point of photovoltaic power generation; P b_min is the lower limit power of water electrolyzer B; P b_max is the upper limit power of water electrolyzer B; Pa is the rated power of water electrolyzer A; P b is the rated power of water electrolyzer B; P a_min is the lower limit power of water electrolyzer A; P a_max is the upper limit power of water electrolyzer A.

[0148] (2) Considering the optimal efficiency range of the water electrolysis hydrogen production system, the power ratio coefficient δ under different conditions is defined as follows: Hydrogen production power P of water electrolysis cell A a The adjustable heater B power P connected in series br The sum of the photovoltaic maximum power point P MPPT The ratio of Hydrogen production power P of water electrolyzer B b The adjustable heater A power P connected in series ar The sum of the photovoltaic maximum power point P MPPT The ratio of Hydrogen production power P of water electrolyzer A a , adjustable heater A power P ar 、Hydrogen production power P of water electrolyzer B b , adjustable heater B power P br The sum of the photovoltaic maximum power point P MPPT The ratio of

[0149] Among them, the δ power ratio coefficient, δ≤1, ranges from 0.8 to 1.

[0150] (3) Define the power combination vector P of the auxiliary equipment for water electrolysis hydrogen production;

[0151] The control system converts the electrodialysis power P s 、Energy storage system charging power P c , air compressor compressed gas power P g , Regeneration heater power P k The start and stop states of the auxiliary equipment are encoded by binary numbers to generate the auxiliary equipment operation state matrix, which is then combined with the electrodialysis power P s 、Energy storage system charging power P c , air compressor power P g , Regeneration heater power P k The power vectors of the auxiliary equipment composed are multiplied to generate a complete enumeration of the power combination vector P of the auxiliary equipment of the water electrolysis hydrogen production device.

[0152]

[0153] Among them, P x ∈P.

[0154] (4) Priority for accessory equipment;

[0155] As the auxiliary equipment for hydrogen production by water electrolysis has the characteristics of time-sharing operation and energy storage, its priority in different time periods is: in the morning period, electrodialysis, energy storage, air compressor, adjustable heater, etc.;

[0156] In the afternoon, the heater, energy storage, air compressor, electrodialysis, etc. can be adjusted in sequence.

[0157] (5) Definition of high and low grade temperatures;

[0158] Since the DC power of the adjustable heater is adjustable from 0 to 100%, the greater the power, the higher the temperature of the heating element, and vice versa. The high-grade temperature of the heating element refers to the heating temperature of the heating element being greater than or equal to the regeneration heating temperature when the adjustable heater works at a certain power, which is used for drying molecular sieve gas. The low-grade temperature of the heating element refers to the temperature generated by the heating element being lower than the regeneration heating temperature and higher than the melting point of the phase change material when the adjustable heater works at low power, and the heat is absorbed and stored by the phase change material. When drying the molecular sieve gas, the heat storage of the phase change material is used as the basic temperature, which greatly reduces the regeneration heating power.

[0159] Among them, the regeneration heating temperature refers to the heating temperature when the water-absorbing resin in the molecular sieve dryer is regenerated; the high-grade temperature is greater than the regeneration heating temperature; and the low-grade temperature is lower than the regeneration heating temperature.

[0160] 2) Specific control process

[0161] (1) When P b_min ≤P v <P a_min The water electrolyzer B produces hydrogen and the adjustable heater A regulates and matches the maximum power of photovoltaic power generation

[0162] When the photovoltaic power generation power P v Greater than or equal to rated power P b The lower limit power P of water electrolyzer B b_min , less than the rated power P a The lower limit power P of water electrolyzer A a_min That is, P b_min ≤P v <P a_min When the water electrolyzer B and the adjustable heater A connected in parallel with the water electrolyzer A are started to produce hydrogen. Among them, the adjustable heater A is in a short-circuit state. At this time, the photovoltaic power generation power P v Act directly on water electrolyzer B.

[0163] As the photovoltaic power generation power P v The increase of photovoltaic power generation power P v Power the series circuit between water electrolyzer B and adjustable heater A. The voltage of water electrolyzer B is U bWith adjustable heater A voltage U ar The sum of the series voltages is equal to the photovoltaic power generation voltage U v , that is U b +U ar =U v . The current of water electrolyzer B is I b , adjustable heater A current I ar and photovoltaic power generation current I v Equal, that is, I ar =I b =I v .

[0164] At this time, the maximum power point of photovoltaic power generation is P MPPT changes, the control system monitors the photovoltaic power generation power P v , and calculate the maximum power point P of photovoltaic power generation MPPT =I MPPT *U MPPT .

[0165] Due to the process of water electrolysis tank B, the voltage U across the water electrolysis tank B b Relatively fixed, in order to ensure the best efficiency of photovoltaic water electrolysis hydrogen production system, the voltage U b With adjustable heater A voltage U ar The sum of the series voltages is equal to the maximum power point voltage U of photovoltaic power generation MPPT , that is U b +U ar =U MPPT .

[0166] Considering the optimal efficiency range of the photovoltaic water electrolysis hydrogen production system, let the hydrogen production power of water electrolyzer B be P b The adjustable heater A power P connected in series ar The sum of the photovoltaic maximum power point P MPPT The ratio is equal to or close to the power ratio coefficient δ, that is, Thus we get P ar =δP MPPT -P b and δI MPPT ×U MPPT =I ar U ar +I b U b .

[0167] Since the water electrolyzer B is connected in series with the adjustable heater A and powered by photovoltaic power generation, the power P of the adjustable heater A is ar Adjust, change the current I of the adjustable heater A ar and voltage U ar, so that the series current of the water electrolyzer B and the adjustable heater A approaches the maximum power point current I of the photovoltaic power generation MPPT ,Right now δI MPPT ×U MPPT =I ar U ar +I b U b Simplified to get the maximum power point voltage U of photovoltaic power generation MPPT The product of the power ratio coefficient δ minus the voltage U of the water electrolyzer B b Equal to the adjustable heater A series voltage U ar , that is, δ×U MPPT -U b =U ar , thus the maximum power point current I MPPT With adjustable heater A voltage U ar The product of ar =I MPPT U ar The calculation results show that the heater A adjusts the power P ar Plus the water electrolyzer B power P b Equal to or close to the maximum power point P of photovoltaic power generation MPPT ,Right now

[0168] Among them, P v is the photovoltaic power generation power; U MPPT I is the maximum power point voltage of photovoltaic power generation; MPPT is the maximum power point current of photovoltaic power generation; U v is the photovoltaic power generation output voltage; P ar Adjust the power of the adjustable heater A; P MPPT is the maximum power point of photovoltaic power generation; P b_min is the lower limit power of water electrolyzer B; P a is the rated power of water electrolyzer A; P a_min is the lower limit power of water electrolyzer A.

[0169] (2) When P a_min <P v <P a_min +P b_min When the water electrolyzer A produces hydrogen and the adjustable heater B regulates and matches the maximum power of photovoltaic power generation

[0170] As the photovoltaic power generation continues to increase, when the photovoltaic power generation power P v Greater than the lower power limit P of water electrolyzer A a_min , which is less than the lower power limit P of water electrolyzer A a_min The lower power P of water electrolyzer Bb_min The sum of the lower limit power of the two water electrolyzers is:

[0171] P a_min <P v <P a_min +P b_min When the water electrolyzer B and the adjustable heater A connected in parallel with the water electrolyzer A are turned off, the water electrolyzer A and the adjustable heater B connected in parallel with the water electrolyzer B are started to produce hydrogen. Among them, the adjustable heater B is in a short-circuit state; the upper limit power P of the water electrolyzer B b_max Greater than the lower power limit P of water electrolyzer A a_min .

[0172] Among them, P v is the photovoltaic power generation power; P b is the rated power of water electrolyzer B; P b_min is the lower limit power of water electrolyzer B; P a is the rated power of water electrolyzer A; P a_min is the lower limit power of water electrolyzer A; U a is the rated voltage of water electrolyzer A; U br is the voltage across the adjustable heater B; U v is the voltage of photovoltaic power generation at a certain moment;

[0173] As the photovoltaic power generation power P v The increase of photovoltaic power generation power P v Power the series circuit between water electrolyzer A and adjustable heater B. The voltage of water electrolyzer A is U a With adjustable heater A voltage U br The sum of the series voltages is equal to the photovoltaic power generation voltage U v , that is U a +U br =U v . The current of water electrolyzer A is I a , adjustable heater B current I br and photovoltaic power generation current I v Equal, that is, I br =I a =I v .

[0174] At this time, the maximum power point of photovoltaic power generation is P MPPT changes, the control system monitors the photovoltaic power generation power P v , and calculate the maximum power point P of photovoltaic power generation MPPT =I MPPT *U MPPT .

[0175] Due to the process of water electrolysis tank A, the voltage U across the water electrolysis tank A aRelatively fixed, in order to ensure the best efficiency of photovoltaic water electrolysis hydrogen production system, the water electrolyzer A voltage U a With adjustable heater B voltage U br The sum of the series voltages is equal to the maximum power point voltage U of photovoltaic power generation MPPT , that is U a +U br =U MPPT .

[0176] Considering the optimal efficiency range of the photovoltaic water electrolysis hydrogen production system, the hydrogen production power P of the water electrolyzer A is a The adjustable heater B power P connected in series br The sum of the photovoltaic maximum power point P MPPT The ratio is equal to or close to the power ratio coefficient δ, that is, Thus we get P br =δP MPPT -P a and δI MPPT ×U MPPT =I br U br +I a U a .

[0177] Since the water electrolyzer A is connected in series with the adjustable heater B and powered by photovoltaic power generation, the power P of the adjustable heater B is br Adjust, change the current I of the adjustable heater B br and voltage U br , so that the series current of the water electrolyzer A and the adjustable heater B approaches the maximum power point current I of the photovoltaic power generation MPPT ,Right now δI MPPT ×U MPPT =I br U br +I a U a Simplified to get the maximum power point voltage U of photovoltaic power generation MPPT The product of the power ratio coefficient δ minus the voltage U of the water electrolyzer A a Equal to the adjustable heater B series voltage U br , that is, δ×U MPPT -U a =U br , thus the maximum power point current I MPPT With adjustable heater A voltage U br The product of ar =I MPPT U br The calculation of heater B adjustment power P is obtained. br Plus the water electrolyzer A power P aEqual to or close to the maximum power point P of photovoltaic power generation MPPT ,Right now

[0178] P br Adjust the power of the adjustable heater B; P MPPT is the maximum power point of photovoltaic power generation; P b_min is the lower limit power of water electrolyzer B; P a is the rated power of water electrolyzer A; P a_min is the lower limit power of water electrolyzer A.

[0179] (3) When P a_min +P b_min <P v <P a_max +P b_max When water electrolyzer A, B produces hydrogen and adjustable heater A, B regulates and matches the maximum power of photovoltaic power generation

[0180] When the photovoltaic power generation power P v Greater than or equal to the sum of the lower power limits of the two water electrolyzers and less than the sum of the upper power limits of the two water electrolyzers, that is, P a_min +P b_min <P v <P a_max +P b_max When , water electrolyzer A and water electrolyzer B are started to work in series. At this time, the series voltage of water electrolyzer A and water electrolyzer B increases. Since the photovoltaic maximum power point voltage is approximately equal to 0.8 times the photovoltaic open circuit voltage, the photovoltaic maximum power point voltage may be lower than the series voltage of water electrolyzer A and water electrolyzer B. Since adjustable heater A and adjustable heater B are connected in parallel with water electrolyzer A and water electrolyzer B respectively, there is an adjustable heater A current I ar With water electrolyzer A current I a The sum is equal to the adjustable heater B current I br With water electrolyzer B current I b The sum of I ar +I a =I br +I b Thus, by controlling the power of the adjustable heater, the adjustable heater A current I ar Or adjustable heater B current I br Absorb or release photovoltaic power generation current, so that the current approaches the photovoltaic maximum power point current I MPPT ,Right now Due to the process of water electrolyzer, the voltage of water electrolyzer is relatively fixed, but it changes with the change of current. Therefore, by shunting water electrolyzer A or water electrolyzer B, the series voltage of water electrolyzer A and water electrolyzer B changes and approaches the maximum power point voltage U of photovoltaic. MPPT ,Right now

[0181] For the convenience of calculation, the influence of the current change on the voltage change of the water electrolyzer is ignored, and the voltage U of the water electrolyzer A is used as the a and water electrolyzer B voltage U b , respectively calculate the power P of the adjustable heater A ar =U a I ar and the power P of the adjustable heater B br =U b I br .

[0182] Among them, the upper limit power P of water electrolyzer A a_max Greater than the lower power limit P of water electrolyzer B b_min The lower power P of water electrolyzer A a_min The sum of P b_min +P a_min <P a_max .

[0183] As the photovoltaic power generation power P v The increase of photovoltaic power generation power maximum power point P MPPT During the change, the control system monitors the photovoltaic power generation power P v , and calculate the maximum power point P of photovoltaic power generation MPPT =I MPPT ×U MPPT , control the adjustable heater A to adjust the power P ar , adjustable heater B adjusts power P br Considering the optimal efficiency range of the water electrolysis hydrogen production system (hydrogen production efficiency of water electrolysis cell), the hydrogen production power P of water electrolysis cell A is a , adjustable heater A power P ar 、Hydrogen production power P of water electrolyzer B b , adjustable heater B power P br The sum of the photovoltaic maximum power point P MPPT The ratio should be close to the power ratio coefficient δ, that is,

[0184] Therefore, when the hydrogen production power P of water electrolyzer A a , adjustable heater A power P ar 、Hydrogen production power P of water electrolyzer B b , adjustable heater B power P br The sum of the maximum power point of photovoltaic power generation P MPPT The ratio is less than the power ratio coefficient δ, that is, When the load power of adjustable heater A and adjustable heater B is adjusted, the hydrogen production power P of water electrolyzer A is a , adjustable heater A power Par 、Hydrogen production power P of water electrolyzer B b , adjustable heater B power P br The sum of the maximum power point of photovoltaic power generation P MPPT The ratio approaches the power ratio coefficient δ, that is,

[0185] Since the adjustable heater A and the adjustable heater B are connected in parallel with the water electrolyzer A and the water electrolyzer B respectively, the adjustable heater A current I ar With water electrolyzer A current I a The sum is equal to the adjustable heater B current I br With water electrolyzer B current I b The sum of I ar +I a =I br +I b Since the adjustable heater A current I ar and adjustable heater B current I br The series current is much smaller than the water electrolyzer A current I a and water electrolyzer B current I b Series current, thus adjustable heater A current I ar and adjustable heater B current I br Approximately equal, that is, I ar ≈I br , thus through P br +P ar =δP MPPT -P b -P a Formula and maximum power point voltage U MPPT The ratio of the adjustable heater A and the adjustable heater B series circuit current expression is obtained:

[0186] For the convenience of calculation, the influence of the current change on the voltage change of the water electrolyzer is ignored, and the voltage U of the water electrolyzer A is used as the a and water electrolyzer B voltage U b , respectively calculate the power P of the adjustable heater A ar =U a I ar and the power P of the adjustable heater B br =U b I br .

[0187] The control system adjusts the adjustable heater A power P accordingly based on this power control ar and adjustable heater B power P br , so that the adjustable heater A power P ar With adjustable heater B power P brWith water electrolyzer A power P a With water electrolyzer B power P b The sum is equal to or close to the maximum power point P of photovoltaic power generation MPPT ,Right now

[0188] Among them, δ is the power ratio coefficient, δ≤1 ranges from 0.8 to 1; P ar is the adjustable heater A power; P br is the power of adjustable heater B; P a is the power of water electrolyzer A; P b is the power of water electrolyzer B; U a is the voltage across the water electrolyzer A; U b is the voltage across the water electrolyzer B; I ar is the adjustable heater A current; I br is the current of adjustable heater B; P a_max is the upper limit power of water electrolyzer A; P a_min is the lower limit power of water electrolyzer A; P b_max is the upper limit power of water electrolyzer B; P b_min is the lower limit power of water electrolyzer B; U MPPT P is the photovoltaic maximum power point tracking voltage; MPPT is the maximum power point of photovoltaic.

[0189] (4) When When water electrolyzer A, B produces hydrogen and adjustable heater A, B regulates and matches the maximum power of photovoltaic power generation

[0190] When the photovoltaic power generation power P v Approaching the sum of the upper power limits of the two water electrolyzers, that is, When the two water electrolyzers are maintained in series operation, the current I of the two adjustable heaters in series will be adjusted according to the sampling cycle of the control system. abr_t2 , minus the series current I of the two adjustable heaters at the previous moment abr_t1 , and get the incremental current △I ar =△I br =△I abr =I abr_t2 -I abr_t1 When the control system executes the next sampling cycle, it controls the two adjustable heaters to be connected in series with a current of I ar =I br =I abr_t2 +△I abr , while considering the optimal efficiency range of the water electrolysis hydrogen production system (hydrogen production efficiency of water electrolysis cell), connect two adjustable heaters in series with the current I ar =I br =I abr_t2 +△Iabr Multiply by the power ratio coefficient δ to get I arn =I brn =δ(I abr_t2 +△I abr ).

[0191] And according to the voltage U across the water electrolyzer A a The voltage U across the water electrolyzer B b , respectively calculate the power P of the adjustable heater A in the next execution cycle ar =U a I arn and the power P of the adjustable heater B br =U b I brn The control system adjusts the adjustable heater A power P accordingly based on this power control. ar and adjustable heater B power P br , so that the adjustable heater A power P ar With adjustable heater B power P br With water electrolyzer A power P a With water electrolyzer B power P b The sum is equal to or close to the maximum power point P of photovoltaic power generation MPPT ,Right now

[0192] Thus, the excess photovoltaic power is converted into thermal energy through the adjustable heater. The high-grade thermal energy is directly used for the regeneration heating of the molecular sieve dryer, and the low-grade thermal energy is stored through phase change heat storage to provide the ambient temperature, the basic heating temperature for the regeneration of the molecular sieve dryer, etc.

[0193] Where δ is the power ratio coefficient, δ≤1 ranges from 0.8 to 1; I arn is the current of the adjustable heater A in the next execution cycle; I brn is the current of the adjustable heater B in the next execution cycle; I abr_t2 I is the current of the two adjustable heaters in series at the current moment; abr_t1 is the series current of the two adjustable heaters at the previous moment; △I ar is the incremental current of the adjustable heater A; △I br is the incremental current of the adjustable heater B; △I abr It is the incremental current of adjustable heater A and adjustable heater B in series.

[0194] (5)P b_min >P c +P g +P s +P kControl the power combination vector P and priority of water electrolysis hydrogen production auxiliary equipment to match the maximum power of photovoltaic power generation

[0195] Since the lower limit power P of water electrolyzer B b_min Greater than the sum of the power of the auxiliary equipment for hydrogen production by water electrolysis, that is, P b_min >P c +P g +P s +P k , in the photovoltaic power generation power P v Less than the lower power limit P of water electrolyzer B b_min During this time period, the controller starts the corresponding water electrolysis hydrogen production auxiliary equipment according to the auxiliary equipment power combination vector P and the auxiliary equipment priority, thus achieving full time domain matching utilization of photovoltaic power generation.

[0196] Among them, the auxiliary equipment for hydrogen production by water electrolysis has the characteristics of time-sharing operation and energy storage;

[0197] Priority: In the morning, electrodialysis, energy storage, air compressor, adjustable heater, etc.; in the afternoon, adjustable heater, energy storage, air compressor, electrodialysis, etc.

[0198] Although the above describes the illustrative specific embodiments of the present invention to facilitate those skilled in the art to understand the present invention, and it should be clear that the present invention is not limited to the scope of the specific embodiments, for those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations using the concept of the present invention are protected.

Claims

1. A full-time domain matching system for photovoltaic power generation in series with unequal-volume water electrolyzers, characterized in that: include: Control systems, photovoltaic arrays, water electrolyzer groups, heat exchange systems, electrodialysis, adjustable electric heaters, energy storage systems and photovoltaic inverters; The water electrolyzer group comprises a water electrolyzer A and a water electrolyzer B of unequal volumes connected in series, which are used for electrolyzing water to produce hydrogen and are installed in a photovoltaic water electrolysis hydrogen production device room; wherein the positive electrode of the water electrolyzer A is connected to the positive electrode output by the photovoltaic array, the negative electrode of the water electrolyzer A is connected to the positive electrode of the water electrolyzer B, and the negative electrode of the water electrolyzer B is connected to the negative electrode output by the photovoltaic array; the positive and negative power input ends of an adjustable electric heater are connected in parallel at both ends of the electrodes of each water electrolyzer A and B, which plays the role of current diversion and voltage stabilization of the water electrolyzer, power adjustment of another water electrolyzer, and photovoltaic maximum power tracking; similarly, voltage sensors are installed in parallel at both ends of the electrodes of each water electrolyzer A and B, and current sensors are connected in series in the loop, so that the control system monitors the working status of the water electrolyzer in real time; The photovoltaic array is installed around the photovoltaic water electrolysis hydrogen production device to provide energy for water electrolysis hydrogen production; the photovoltaic array output is respectively connected to the water electrolysis cell group, electrodialysis, energy storage system and photovoltaic inverter input end; The heat exchange system comprises: a phase change heat storage material, a heat exchanger, and a radiator, wherein the phase change heat storage material is filled in a sealed box and placed in or around the photovoltaic water electrolysis hydrogen production device; the heat exchangers are respectively installed in the phase change heat storage material and in the regeneration heater environment, and are used to release the heat energy of the heat source in the phase change heat storage material through the heat exchangers at different positions; The radiator is installed on the wall inside the photovoltaic water electrolysis hydrogen production device. According to the ambient temperature requirements, the temperature of the heat exchanger is switched by the valve to exchange heat to the photovoltaic water electrolysis hydrogen production device room; The energy storage system includes: a bidirectional converter and an energy storage battery, which are installed in the photovoltaic water electrolysis hydrogen production device room or other rooms; The power input end of the adjustable heater is connected to the positive and negative electrodes of the water electrolyzer, and the heating element of the adjustable heater is respectively installed in the phase change material and the molecular sieve dryer. Under the control of the control system, the low-grade temperature of the heating element cooperates with the phase change material to store heat through the phase change material to match the excess photovoltaic power generation, or the high-grade temperature of the heating element is directly used for the regeneration of the water-absorbing resin in the molecular sieve dryer; the high-grade temperature is greater than the regeneration heating temperature; the low-grade temperature is lower than the regeneration heating temperature.

2. The full-time domain matching system for photovoltaic power generation in series with unequal-volume water electrolyzers according to claim 1 is characterized in that: The DC power of the adjustable heater is adjustable from 0 to 100%. The greater the power, the higher the temperature of the heating element, and vice versa. The high-grade temperature of the heating element refers to the heating temperature of the heating element being greater than or equal to the regeneration heating temperature when the adjustable heater works at a certain power, which is used for drying molecular sieve gas. The low-grade of the heating element refers to the temperature generated by the heating element being lower than the regeneration heating temperature and higher than the melting point of the phase change material when the adjustable heater works at low power, and the heat is absorbed and stored by the phase change material. When drying the molecular sieve gas, the heat storage of the phase change material is used as the basic temperature to reduce the regeneration heating power. Among them, the regeneration heating temperature refers to the heating temperature when the water-absorbing resin in the molecular sieve dryer is regenerated. The high-grade temperature is greater than or equal to the regeneration heating temperature; the low-grade temperature is lower than the regeneration heating temperature.

3. The full-time domain matching system for photovoltaic power generation in series with unequal-volume water electrolyzers according to claim 1 is characterized in that: The photovoltaic inverter is installed in the photovoltaic water electrolysis hydrogen production device room or other rooms to provide AC power for the water electrolysis hydrogen production auxiliary equipment; The electrodialysis is installed in the photovoltaic water electrolysis hydrogen production device or other indoor surroundings, mainly used for pure water preparation; The control system includes a controller and sensors. The sensors are distributed and installed on various devices of the photovoltaic water electrolysis hydrogen production device, and mainly collect all parameters of the water electrolysis hydrogen production equipment. The input interface of the controller is connected to all sensor output ports through data lines to monitor the operating status of all devices and systems, and execute corresponding control strategies after analysis and judgment; the output interface of the controller is connected to all actuators and equipment through control lines to control the corresponding equipment to work or stop, thereby realizing efficient operation of photovoltaic water electrolysis hydrogen production.

4. A method for full-time domain matching of photovoltaic power generation power in series with unequal-volume water electrolyzers, characterized in that: The steps include: Step 1: Set parameters, define the power ratio coefficient under different conditions, define the power combination vector of the auxiliary equipment for hydrogen production by water electrolysis, and set the priority of the auxiliary equipment; Step 2, performing full time domain matching control of photovoltaic power generation power in series with unequal volume water electrolyzers; The step 1 specifically comprises the following steps: (1) Two unequal-volume water electrolyzers A and B are connected in series, and a 0-100% power adjustable heater is connected in parallel with the water electrolyzers to adapt to the photovoltaic power generation power under different light conditions; in the unequal-volume water electrolyzer series photovoltaic hydrogen production system, the water electrolyzer group is composed of a water electrolyzer A and a water electrolyzer B connected in series; Among them, electrical parameters of water electrolyzer A: rated power , Rated voltage , Rated current ; Electrical parameters of water electrolyzer B: Rated power , Rated voltage , Rated current ; Among them, the rated current With rated current Equal, that is ; Water electrolyzer A rated power Greater than the rated power of water electrolyzer B ,Right now ; The upper limit power of water electrolyzer B is greater than the lower limit power of water electrolyzer A; The upper limit power of water electrolyzer A is greater than the sum of the lower limit powers of water electrolyzer A and water electrolyzer B; (2) Define the power ratio coefficient under different conditions ; Considering the optimal efficiency range of the water electrolysis hydrogen production system, define the power ratio coefficient under different conditions They are: ① Hydrogen production power of water electrolyzer A The power of the adjustable heater B connected in series The sum of the photovoltaic maximum power point The ratio of ; ② Hydrogen production power of water electrolyzer B The adjustable heater A power in series The sum of the photovoltaic maximum power point The ratio of ; ③ Hydrogen production power of water electrolyzer A , adjustable heater A power 、Hydrogen production power of water electrolyzer B , adjustable heater B power The sum of the photovoltaic maximum power point The ratio of ; in, is the power ratio coefficient, The value range is 0.8~1; (3) Define the power combination vector of the auxiliary equipment for water electrolysis hydrogen production ; The control system converts the electrodialysis power , Energy storage system charging power , Air compressor compressed gas power , Regeneration heater power The start and stop states of the auxiliary equipment are encoded by binary numbers to generate the auxiliary equipment operation state matrix, which is then combined with the electrodialysis power , Energy storage system charging power , air compressor power , Regeneration heater power The auxiliary equipment power vector composed of the power vectors is multiplied to generate a complete enumeration of the auxiliary equipment power combination vectors of the water electrolysis hydrogen production device : in, ; (4) Setting priority for auxiliary equipment; The priorities in the morning period are electrodialysis, energy storage, air compressor, and adjustable heater; The priorities in the afternoon period are adjustable heater, energy storage, air compressor, and electrodialysis; The step 2 comprises the following steps: (1) When Considering the optimal efficiency range of photovoltaic water electrolysis hydrogen production system, according to the power ratio coefficient , thus we get , ,because Simplified , through which The calculation of heater A is used to adjust the power Plus water electrolyzer B power Equal to or close to the maximum power point of photovoltaic power generation ,Right now ; (2) When When the water electrolyzer B and the adjustable heater A are turned off, the water electrolyzer A and the adjustable heater B are started to produce hydrogen; Since the water electrolyzer A is connected in series with the adjustable heater B and is powered by photovoltaic power generation, the power of the adjustable heater B is Adjust, change the current of adjustable heater B and voltage ,make ; Considering the optimal efficiency range of photovoltaic water electrolysis hydrogen production system, based on the power ratio coefficient , thus we get and ; Simplified , through which The calculation of heater B is used to adjust the power Plus water electrolyzer A power Equal to or close to the maximum power point of photovoltaic power generation ,Right now ; (3) When When water electrolyzer A and water electrolyzer B are started to work in series, By controlling the power of the adjustable heater, , ; Ignore the effect of current change on voltage change of water electrolyzer, and use the voltage of water electrolyzer A as the and water electrolyzer B voltage , respectively calculate the power of the adjustable heater A and the power of adjustable heater B ; With the photovoltaic power The increase in photovoltaic power generation power maximum power point In the change, considering the optimal efficiency range of the water electrolysis hydrogen production system, according to the power ratio coefficient ,get ; when When the load power of adjustable heater A and adjustable heater B is adjusted, , calculated from this ,because ,in , so , we get the current expression of the series circuit of adjustable heater A and adjustable heater B: ; Ignore the effect of current change on voltage change of water electrolyzer, and use the voltage of water electrolyzer A as the and water electrolyzer B voltage , respectively calculate the power of the adjustable heater A and the power of adjustable heater B ; (4) When When two water electrolyzers are connected in series, the incremental current is calculated based on the sampling period of the control system. ; When the control system executes the next sampling cycle, it controls the series current of the two adjustable heaters to be , considering the optimal efficiency range of the water electrolysis hydrogen production system, we get ; And according to the voltage across the water electrolyzer A The voltage across the water electrolyzer B , respectively calculate the power of the adjustable heater A in the next execution cycle and the power of adjustable heater B ; The control system adjusts the power of adjustable heater A accordingly based on this power control and adjustable heater B power , so that the adjustable heater A power With adjustable heater B power A power of water electrolyzer With water electrolyzer B power The sum is equal to or close to the maximum power point of photovoltaic power generation ,Right now ; Thus, the excess photovoltaic power is converted into thermal energy through the adjustable heater. The high-quality thermal energy is directly used for the regeneration heating of the molecular sieve dryer, and the low-quality thermal energy is stored through phase change heat storage to provide the ambient temperature and the basic heating temperature for the regeneration of the molecular sieve dryer. in, is the photovoltaic power generation power; The maximum power point voltage of photovoltaic power generation; is the maximum power point current of photovoltaic power generation; is the photovoltaic power generation output voltage; Adjust the power for adjustable heater A; is the maximum power point of photovoltaic power generation; is the lower limit power of water electrolyzer B; is the rated power of water electrolyzer A; is the lower limit power of water electrolyzer A; is the power ratio coefficient, The value range is 0.8~1; is the current of the adjustable heater A in the next execution cycle; is the current of the adjustable heater B in the next execution cycle; is the series current of the two adjustable heaters at the current moment; The series current of the two adjustable heaters at the previous moment; is the incremental current of the adjustable heater A; is the incremental current of adjustable heater B; is the incremental current of the adjustable heater A and the adjustable heater B in series; (5) When Control the power combination vector of auxiliary equipment for hydrogen production by water electrolysis and priority, start the corresponding water electrolysis hydrogen production auxiliary equipment; realize the full time domain matching utilization of photovoltaic power generation.

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