PEM hydrogen production system and pressure control method thereof

Abstract

The invention relates to the technical field of hydrogen production, in particular to a PEM hydrogen production system and a pressure control method thereof. On the basis that the water inlet temperature and the water outlet temperature of the electrolytic bath and the liquid level heights of the hydrogen separator and the oxygen separator are accurately controlled through the first-stage pressure regulation and control unit, the pressure in the hydrogen separator and the oxygen separator is accurately regulated and controlled through the second-stage pressure regulation and control unit; the pressure value of the oxygen separator is accurately controlled to be 2.8 Mpa through the oxygen side pressure control module and is completely matched with the set value 2.8 Mpa, and the pressure value of the hydrogen separator is accurately controlled to be 3 Mpa through the hydrogen side pressure control module and is completely matched with the set value 3 Mpa. Therefore, the pressure in the hydrogen separator and the oxygen separator can be accurately controlled through the combined action of the first-stage pressure regulation and control unit and the second-stage pressure regulation and control unit.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen production, and in particular to a PEM hydrogen production system and a pressure control method thereof. Background Art

[0002] Proton exchange membrane (PEM) water electrolysis hydrogen production technology has become one of the important technologies in the field of hydrogen energy production due to its high efficiency, fast startup and environmental friendliness. However, during the operation of the PEM system, the operating power of the proton exchange membrane fluctuates greatly, the power variation range is large, and the pressure fluctuation in the PEM system will also increase accordingly. The pressure of the PEM hydrogen production system is a very important parameter, which directly affects the efficiency and quality of hydrogen production. Therefore, how to effectively control the pressure in the PEM hydrogen production system within a wide power operating range to ensure the safe, stable and efficient operation of the PEM hydrogen production system has become a technical problem that needs to be solved urgently.

[0003] For example, the Chinese invention patent application with application number 202111168078.0 discloses a pressure control method, system, equipment and medium for PEM pure water electrolysis hydrogen production. The method is to obtain the pressure value of the hydrogen outlet of the electrolyzer at regular intervals, calculate the parameter value of the pressure influencing parameter of each acquisition cycle, and then control the valve opening of the hydrogen outlet of the electrolyzer according to the output PID adjustment parameter. This method mainly controls the system pressure by controlling the valve opening of the hydrogen outlet. However, during the actual operation of the PEM hydrogen production system, the pressure of the system can only be stabilized in a range by relying solely on the opening of the hydrogen outlet valve, and the pressure of the PEM hydrogen production system cannot be accurately controlled. Summary of the invention

[0004] In order to overcome the above problems, the purpose of the present invention is to provide a PEM hydrogen production system and a pressure control method thereof. The pressure control method of the PEM hydrogen production system of the present invention can achieve accurate control of the system pressure within a wide power PEM operating range.

[0005] To achieve the above purpose, the technical solution designed by the present invention is as follows:

[0006] A PEM hydrogen production system comprises an electrolyzer, an oxygen separator, a hydrogen separator, a radiator, a circulating water pump and a water replenishment tank; the inlet of the electrolyzer is provided with a water inlet temperature detector, and the outlet of the electrolyzer is provided with a water outlet temperature detector; the hydrogen separator is connected to the cathode plate of the electrolyzer, the oxygen separator is connected to the anode plate of the electrolyzer, the top of the hydrogen separator is provided with a hydrogen side gas valve, the middle of the hydrogen separator is provided with a hydrogen side liquid level transmitter for detecting the liquid level height in the hydrogen separator and a hydrogen side pressure transmitter for detecting the pressure in the hydrogen separator, the drain port at the bottom of the hydrogen separator is connected to the water inlet of the oxygen separator through the hydrogen side drain valve; An oxygen side air valve is provided on the top of the oxygen separator, an oxygen side liquid level transmitter for detecting the liquid level height in the oxygen separator and an oxygen side pressure transmitter for detecting the pressure in the oxygen separator are provided in the middle of the oxygen separator, a water supply port at the bottom of the oxygen separator is connected to the water supply tank via the oxygen side water supply valve, a drain port at the bottom of the oxygen separator is connected to the radiator and the circulating water pump in sequence through a pipeline, and then connected to the water inlet of the electrolyzer to form a circulating water passage; the PEM hydrogen production system also includes a primary pressure control unit for eliminating the interference of temperature and liquid level factors on the system pressure and a secondary pressure control unit for accurately adjusting the system pressure;

[0007] The primary pressure control unit includes an inlet water temperature control module, an outlet water temperature control module, an oxygen side liquid level control module and a hydrogen side liquid level control module; the secondary pressure control unit includes an oxygen side pressure control module and a hydrogen side pressure control module; the input end of the inlet water temperature control module is connected to an inlet water temperature detector, and the output end of the inlet water temperature control module is connected to a radiator; the input end of the outlet water temperature control module is connected to an outlet water temperature detector, and the output end of the outlet water temperature control module is connected to a circulating water pump; the oxygen side liquid level control module The input end of the oxygen side liquid level control module is connected to the oxygen side liquid level transmitter, and the output end of the oxygen side liquid level control module is connected to the oxygen side water replenishment valve; the input end of the hydrogen side liquid level control module is connected to the hydrogen side liquid level transmitter, and the output end of the hydrogen side liquid level control module is connected to the hydrogen side drain valve; the input end of the oxygen side pressure control module is connected to the oxygen side pressure transmitter, and the output end of the oxygen side pressure control module is connected to the oxygen side gas valve, the input end of the hydrogen side pressure control module is connected to the hydrogen side pressure transmitter, and the output end of the hydrogen side pressure control module is connected to the hydrogen side gas valve.

[0008] As a preferred solution, the PEM hydrogen production system further includes an oxygen-in-hydrogen analyzer and an oxygen-in-oxygen analyzer. The oxygen-in-hydrogen analyzer is installed on the hydrogen separator, and the hydrogen-in-oxygen analyzer is installed on the oxygen separator.

[0009] The pressure control method of the PEM hydrogen production system comprises the following steps:

[0010] (1) Primary anti-interference pressure control: The primary pressure control unit is used to control the inlet and outlet water temperatures of the electrolyzer, as well as the liquid levels of the hydrogen separator and oxygen separator in real time;

[0011] (1.1) Control of the inlet and outlet water temperatures of the electrolyzer: When the electrolyzer is running, the gas and entrained water generated by the cathode plate of the electrolyzer are transported to the hydrogen separator through a pipeline, and the gas and entrained water generated by the anode plate of the electrolyzer are transported to the oxygen separator through a pipeline; the inlet water temperature detector collects the temperature of the inlet water of the electrolyzer and transmits the temperature signal to the inlet water temperature control module, and the inlet water temperature control module adjusts the inlet water temperature by controlling the speed of the radiator; the outlet water temperature detector collects the temperature of the outlet water of the electrolyzer and transmits the temperature signal to the outlet water temperature control module, and the outlet water temperature control module adjusts the outlet water temperature by controlling the speed of the circulating water pump;

[0012] (1.2) Hydrogen side liquid level control: Water in the hydrogen separator accumulates continuously. The hydrogen side liquid level transmitter collects the water level signal in the hydrogen separator and transmits it to the hydrogen side liquid level control module. The hydrogen side liquid level control module adjusts the water level of the hydrogen separator by controlling the opening and closing of the hydrogen side drain valve;

[0013] (1.3) Oxygen side liquid level control: The water inlet of the oxygen separator comes from the hydrogen separator, the anode plate of the electrolytic cell and the water supply tank. The oxygen separator is drained through the bottom drain port. The oxygen side liquid level transmitter collects the water level signal in the oxygen separator and transmits it to the oxygen side liquid level control module. The oxygen side liquid level control module adjusts the water level in the oxygen separator by controlling the opening and closing of the oxygen side water supply valve;

[0014] (2) Secondary precise pressure control: The pressure in the hydrogen separator and oxygen separator is precisely controlled through the secondary pressure control unit;

[0015] (2.1) Hydrogen separator pressure control: The hydrogen side pressure transmitter collects the pressure of the hydrogen separator in real time and transmits it to the hydrogen side pressure control module. The hydrogen side pressure control module accurately controls the pressure of the hydrogen separator by controlling the opening of the hydrogen side gas valve;

[0016] (2.2) Oxygen separator pressure control: The oxygen side pressure transmitter collects the pressure of the oxygen separator in real time and transmits it to the oxygen side pressure control module. The oxygen side pressure control module accurately controls the pressure of the oxygen separator by controlling the opening of the oxygen side gas valve.

[0017] As a preferred embodiment, in step (1), the water inlet temperature of the electrolyzer is set to 55°C, and the water outlet temperature of the electrolyzer is set to 60°C; the water level of the oxygen separator is set to 60% to 67% of the total height of the oxygen separator; the water level of the hydrogen separator is set to 68% to 72% of the total height of the oxygen separator; in step (2), the pressure value in the hydrogen separator is set to 3Mpa, and the pressure value in the oxygen separator is set to 2.8Mpa.

[0018] As a preferred solution, in step (1), according to the set value of the electrolytic cell inlet water temperature of 55°C, the inlet water temperature control module adjusts the inlet water temperature by controlling the speed of the radiator. The specific process is:

[0019] In the water inlet temperature control module, the speed value of the radiator is calculated by the water inlet temperature control function model, and the water inlet temperature of the electrolyzer is controlled at 54.3-57°C by the water inlet temperature control module; the water inlet temperature control function model is constructed based on the BP neural network, and the water inlet temperature control function model is shown in formulas (13) and (14):

[0020] n in (k) = n in (k-1)+Δn in (k) (13)

[0021] In formula (13), n in (k) represents the speed of the radiator at time k, n in (k-1)+ represents the speed of the radiator at time k-1, Δn in (k) represents the increment of the rotation speed of the radiator;

[0022] The increase in the radiator speed Δn in (k) As shown in formula (14):

[0023]

[0024] In formula (14), n in Indicates the speed of the radiator; e in It represents the error between the set water inlet temperature and the actual water inlet temperature, that is, T ref in Indicates the set water inlet temperature, T in Indicates the actual inlet water temperature; K p in ,K i in ,K d in It represents the real-time parameters output by the BP neural network during water inlet temperature control.

[0025] As a preferred solution, in step (1), according to the set value of the electrolytic cell outlet water temperature of 60° C., the outlet water temperature processing module adjusts the outlet water temperature by controlling the speed of the circulating water pump. The specific process is:

[0026] In the outlet water temperature control module, the speed value of the circulating water pump is calculated by the outlet water temperature control function model, and the outlet water temperature of the electrolyzer is controlled at 59.3-62°C by the outlet water temperature control module. The outlet water temperature control function model is constructed based on the BP neural network. The outlet water temperature control function model is shown in formulas (15) and (16):

[0027] n out (k) = n out (k-1)+Δn out (k) (15)

[0028] In formula (15), n out (k) represents the speed of the circulating water pump at time k, n out (k-1) represents the speed of the circulating water pump at time k-1, +Δn out (k) represents the increment of the rotation speed of the circulating water pump;

[0029]

[0030] Where n out Indicates the speed of the circulating water pump; e out It represents the error between the set outlet temperature and the actual outlet temperature, that is, e out =T ref out -T out ,T ref out Indicates the set outlet temperature, T out Indicates the actual outlet temperature; K p out ,K i out ,K d out It represents the real-time parameters output by the BP neural network during outlet temperature control.

[0031] As a preferred solution, in step (1), according to the water level setting value of the oxygen separator of 60% to 67%, the oxygen side liquid level control module adjusts the water level in the oxygen separator by controlling the opening and closing of the oxygen side water supply valve. The specific process is:

[0032] When the water level collected by the oxygen side liquid level transmitter is lower than 60%, the oxygen side liquid level control module controls the oxygen side water supply valve to open; when the water level collected by the oxygen side liquid level transmitter is higher than 67%, the oxygen side liquid level control module controls the oxygen side water supply valve to close; the water level height of the oxygen separator is controlled at 60% to 67% through the oxygen side liquid level control module.

[0033] As a preferred solution, in step (1), according to the water level setting value of the hydrogen separator of 68% to 72%, the hydrogen side liquid level control module adjusts the water level in the hydrogen separator by controlling the opening and closing of the hydrogen side drain valve. The specific process is:

[0034] When the water level collected by the hydrogen side liquid level transmitter is lower than 68%, the hydrogen side liquid level control module controls the hydrogen side water supply valve to open; when the water level collected by the hydrogen side liquid level transmitter is higher than 72%, the hydrogen side liquid level control module controls the hydrogen side drain valve to close; the water level height of the hydrogen separator is controlled at 68% to 72% through the hydrogen side liquid level control module.

[0035] As a preferred solution, in step (2), according to the pressure setting value of 3Mpa in the hydrogen separator, the hydrogen side pressure control module accurately controls the pressure of the hydrogen separator by adjusting the opening of the hydrogen side gas valve as follows:

[0036] The hydrogen side pressure control module calculates the opening of the hydrogen side gas valve 15 through the hydrogen side pressure control function model, and the pressure value in the hydrogen separator is accurately controlled at 3Mpa through the hydrogen side pressure control module. The hydrogen side pressure control function model is constructed based on the BP neural network. The hydrogen side pressure control function model is shown in formulas (17) and (18):

[0037] D H (k) = D H (k-1)+ΔD H (k) (17)

[0038] In formula (17), D H (k) represents the opening of the hydrogen side control valve at time k, D H (k-1) represents the opening of the hydrogen side control valve at time k-1, ΔD H (k) represents the increment of the opening of the hydrogen side exhaust valve;

[0039] The increase of the opening of the hydrogen side exhaust valve ΔD H (k) function is shown in formula (18):

[0040]

[0041] Where D H Indicates the opening of the hydrogen side valve; e H It indicates the error between the set pressure on the hydrogen side and the actual pressure on the hydrogen side, that is, e H =P ref H -P H ,P ref H Indicates the set pressure on the hydrogen side, P Hrepresents the actual pressure on the hydrogen side; (k), (k-1), (k-2) represent the time at (k), (k-1), (k-2) respectively; K p H ,K i H ,K d H It represents the real-time parameters output by the BP neural network during hydrogen side pressure control.

[0042] As a preferred solution, in step (2), according to the pressure setting value of 2.8Mpa in the oxygen separator, the process in which the oxygen side pressure control module accurately controls the pressure of the oxygen separator by adjusting the opening of the oxygen side gas valve is as follows;

[0043] The oxygen side pressure control module calculates the oxygen side valve opening through the oxygen side pressure control function model, and the pressure value of the oxygen separator is accurately controlled at 2.8 MPa through the oxygen side pressure control module. The oxygen side pressure control function model is constructed based on the BP neural network. The oxygen side pressure control function model is shown in formulas (19) and (20):

[0044] D O (k) = D O (k-1)+ΔD O (k) (19)

[0045] In formula (19), D O (k) represents the opening value of the oxygen side valve at time k, D O (k-1) represents the opening value of the oxygen side valve at time k-1, +ΔD O (k) is the opening increment of the oxygen side valve;

[0046] Increase in oxygen side exhaust valve opening + ΔD O (k) can be expressed as:

[0047]

[0048] Where D O Indicates the valve opening on the oxygen side; e O It indicates the error between the set pressure on the oxygen side and the actual pressure on the oxygen side, that is, e O =P ref O -P O ,P ref O Indicates the oxygen side set pressure, P O Indicates the actual pressure on the oxygen side; K p O ,K i O ,K d OIt represents the real-time parameters output by the BP neural network during oxygen side pressure control.

[0049] As a preferred solution, when the BP neural network is calculated for the first time, the weights of the hidden layer and the output layer are assigned and At the same time, the inertia coefficient α and the learning rate η are given; the target value r(k) and the actual output value y(k) are sampled, and the error e(k) = r(k) - y(k) is obtained; the three adjustable parameters K of the PID controller are output through the BP neural network p ,K i ,K d ; Calculate the direction error with the help of Δu(k): u(k)=u(k-1)+Δu(k); Compare the weights by target requirements and Perform optimization adjustment to achieve optimization adjustment of PID parameters; enter the next iteration and recalculate the BP neural network;

[0050] Among them, the three adjustable parameters K of the output p , K i , K d The specific determination process is:

[0051] The input function of the input layer of the BP neural network is as follows:

[0052]

[0053] The input function of the hidden layer is as follows:

[0054]

[0055] in, is the weight of the hidden layer.

[0056] The output function of the hidden layer is as follows:

[0057]

[0058] In formula (4), take

[0059] The input function of the output layer is as follows:

[0060]

[0061] In formula (5), is the weight of the output layer.

[0062] The three output functions of the output layer are as shown in formula (6):

[0063]

[0064] The value of l=1,2,3,K p , K i , K d The function is shown in formula (7):

[0065]

[0066] The weight correction function of the output layer is shown in formula (11):

[0067]

[0068] Similarly, the weight correction function of the hidden layer is shown in formula (12):

[0069]

[0070] The technical idea of ​​the present invention is: when the PEM hydrogen production system is working, the temperature rises, and the pressure of the oxygen separator also increases accordingly. This is because the temperature rise leads to the enhancement of the thermal motion of the gas molecules, which increases the partial pressure of the gas. Correspondingly, the pressure difference between the oxygen separator and the hydrogen separator will also increase. When the temperature drops, the pressure and pressure difference of the oxygen separator will decrease accordingly, because the temperature drop will weaken the thermal motion of the gas molecules, so the temperature change has a greater impact on the pressure control of the oxygen separator. In addition, the replenishment process of the circulating water will also have a greater impact on the pressure difference. The increase of water during water replenishment leads to an increase in the partial pressure of the oxygen side. Similarly, the drainage process of the hydrogen separator will also change the pressure on the hydrogen side, resulting in unstable system pressure and pressure. It can be seen that temperature and liquid level are two key pressure control factors. Compared with the pressure control method of the traditional hydrogen production system, the present invention reduces the interference of the two factors of temperature and liquid level on the pressure through the first-level pressure control unit, and then controls the opening of the gas valve through the second-level pressure control unit to achieve accurate control of the pressure in the hydrogen separator and the oxygen separator.

[0071] Compared with the traditional method, the present invention has the following advantages:

[0072] (1) The pressure control method of the PEM hydrogen production system of the present invention considers the influence of liquid level and temperature changes on pressure control, maintains the liquid level balance of the hydrogen-oxygen separator by regular water replenishment and drainage, and controls the speed of the circulating water pump and the radiator to stabilize the temperature of the inlet and outlet of the electrolyzer. After liquid level control and temperature control, the pressure in the hydrogen separator and the oxygen separator is only affected by the amount of gas, and the precise control of the pressure in the hydrogen separator and the oxygen separator is achieved by controlling the opening of the regulating valve.

[0073] (2) The control method of the PEM hydrogen production system of the present invention sets the water level in the hydrogen separator to 68% to 72% of the height of the hydrogen separator, the water level in the oxygen separator to 60% to 67% of the height of the oxygen separator, the inlet water temperature of the electrolyzer to 55°C, and the outlet water temperature to 60°C; the pressure of the hydrogen separator is set to 3Mpa, and the pressure of the oxygen separator is set to 2.8Mpa. Among them, the stable micro-positive pressure of 0.2Mpa on the hydrogen side to the oxygen side protects the proton exchange membrane and prevents excessive gas permeation to ensure the high purity of the hydrogen on the hydrogen side. In addition, the micro-positive pressure of 0.2Mpa is conducive to the flow of water in the hydrogen separator to the oxygen separator, which is conducive to the control of the liquid level in the hydrogen separator.

[0074] (3) The present invention adjusts the inlet water temperature by controlling the rotation speed of the radiator through the inlet water temperature control module, and controls the inlet water temperature of the electrolyzer at 54.3-57°C, which is quite close to the set value of 55°C. The outlet water temperature control module controls the outlet water temperature of the electrolyzer at 59.3-62°C, which is quite close to the set value of 60°C. The oxygen side liquid level control module 130 controls the water level of the oxygen separator 2 at 60%-67%, which is exactly the same as the set value of 60%-67%. The hydrogen side liquid level control module 140 controls the water level of the hydrogen separator 3 at 68%-72%, which is exactly the same as the set value of 68%-72%. It can be seen that the primary pressure control unit can realize relatively accurate control of the inlet water temperature and outlet water temperature of the electrolyzer, as well as the liquid level heights of the hydrogen separator and the oxygen separator.

[0075] (4) The present invention uses a primary pressure control unit to control the inlet and outlet water temperatures of the electrolyzer, as well as the liquid level heights of the hydrogen separator and the oxygen separator more accurately, and uses a secondary pressure control unit to accurately control the pressure in the hydrogen separator and the oxygen separator. The oxygen side pressure control module controls the pressure value of the oxygen separator to 2.8Mpa, which is completely consistent with the set value of 2.8Mpa. The hydrogen side pressure control module controls the pressure value in the hydrogen separator to 3Mpa, which is completely consistent with the set value of 3Mpa. It can be seen that the combined action of the primary pressure control unit and the secondary pressure control unit can accurately control the pressure in the hydrogen separator and the oxygen separator, and the pressure control is more accurate compared with the traditional pressure range. BRIEF DESCRIPTION OF THE DRAWINGS

[0076] Figure 1 This is a schematic diagram of the PEM hydrogen production system;

[0077] Among them, electrolyzer 1, oxygen separator 2, hydrogen separator 3, circulating water pump 4, water supply pump 5, radiator 6, water supply tank 7, oxygen side pressure transmitter 8, hydrogen side pressure transmitter 9, oxygen side liquid level transmitter 10, hydrogen side liquid level transmitter 11, water inlet temperature detector 12, water outlet temperature detector 13, oxygen side air valve 14, hydrogen side air valve 15, hydrogen side drain valve 16, oxygen side water supply valve 17, oxygen-hydrogen analyzer 18, hydrogen-oxygen analyzer 19;

[0078] Figure 2 It is a curve diagram of liquid level variation in the hydrogen separator during hydrogen production;

[0079] Figure 3 It is a curve diagram of liquid level variation in the oxygen separator during hydrogen production;

[0080] Figure 4 It is a curve diagram of water inlet temperature during hydrogen production;

[0081] Figure 5 It is a curve diagram of the outlet water temperature during the hydrogen production process;

[0082] Figure 6 It is a pressure curve diagram of the hydrogen separator and the oxygen separator in the hydrogen production process;

[0083] Figure 7 It is a schematic diagram of the structure of BP neural network PID controller;

[0084] Figure 8 This is the algorithm flow chart of BIPID;

[0085] Fig. 9 This is the control connection diagram of the PEM hydrogen production system;

[0086] Among them, the primary pressure control unit 100, the water inlet temperature control module 110, the water outlet temperature control module 120, the oxygen side liquid level control module 130, the hydrogen side liquid level control module 140, the secondary pressure control unit 200, the oxygen side pressure control module 210, the hydrogen side pressure control module 220;

[0087] Fig.10 It is a curve diagram of the hydrogen content in the oxygen separator and the oxygen content in the hydrogen separator. DETAILED DESCRIPTION

[0088] In order to better understand the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific examples.

[0089] Example 1 PEM hydrogen production system

[0090] Combination Figure 1As shown, the PEM hydrogen production system includes an electrolyzer 1, an oxygen separator 2, a hydrogen separator 3, a circulating water pump 4, a water supply pump 5, a radiator 6 and a water purifier 7. The anode plate of the electrolyzer 1 is connected to the oxygen separator 2; the cathode plate of the electrolyzer 1 is connected to the hydrogen separator 3. A hydrogen-side regulating valve 15 is provided on the top of the hydrogen separator 3. The hydrogen separator 3 is also provided with a hydrogen-side liquid level transmitter 11 for detecting the liquid level height in the hydrogen separator 3, a hydrogen-side pressure transmitter 9 for detecting the pressure in the hydrogen separator 3, and a hydrogen-oxygen analyzer 19 for detecting the oxygen concentration in the hydrogen separator 3. The drain outlet at the bottom of the hydrogen separator 3 is drained by the hydrogen-side drain valve. The valve 16 is connected to the water inlet of the oxygen separator 2; the oxygen separator 2 is provided with an oxygen side liquid level transmitter 10 for detecting the liquid level height in the oxygen separator 2, an oxygen side pressure transmitter 8 for detecting the pressure in the oxygen separator 2, and an oxygen-hydrogen analyzer 18 for detecting the hydrogen concentration in the oxygen separator 2. The top of the oxygen separator 2 is provided with an oxygen side regulating valve 14, the bottom of the oxygen separator 2 is connected to the water supply tank 7 through the oxygen side water supply valve 17 and the water supply pump 5, and the drainage port at the bottom of the oxygen separator 2 is connected to the radiator 6 and the circulating water pump 4 in sequence through a pipeline, and then connected to the water inlet of the electrolyzer 1 to form a circulating water passage. The water inlet of the electrolyzer 1 is provided with a water inlet temperature detector 12, the cathode plate of the electrolyzer 1 is connected to the hydrogen separator 3 through the cathode plate pipeline, the anode plate of the electrolyzer 1 is connected to the oxygen separator 2 through the anode plate pipeline, and the anode plate pipeline is provided with a water outlet temperature detector 13.

[0091] Combination Fig. 9As shown, the PEM hydrogen production system also includes a primary pressure control unit 100 for reducing the interference of temperature and liquid level factors on pressure and a secondary pressure control unit 200 for accurately adjusting the system pressure; the primary pressure control unit 100 includes an inlet water temperature control module 110, an outlet water temperature control module 120, an oxygen side liquid level control module 130 and a hydrogen side liquid level control module 140; the secondary pressure control unit 200 includes an oxygen side pressure control module 210 and a hydrogen side pressure control module 220; the input end of the inlet water temperature control module 110 is connected to the inlet water temperature detector 12, and the output end of the inlet water temperature control module 110 is connected to the radiator 6; the input end of the outlet water temperature control module 120 is connected to the outlet water temperature detector 13 The output end of the outlet water temperature control module 120 is connected to the circulating water pump 4; the input end of the oxygen side liquid level control module 130 is connected to the oxygen side liquid level transmitter 10, and the output end of the oxygen side liquid level control module 130 is connected to the oxygen side water replenishment valve 17; the input end of the hydrogen side liquid level control module 140 is connected to the hydrogen side liquid level transmitter 11, and the output end of the hydrogen side liquid level control module 140 is connected to the hydrogen side drain valve 16; the input end of the oxygen side pressure control module 210 is connected to the oxygen side pressure transmitter 8, and the output end of the oxygen side pressure control module 210 is connected to the oxygen side gas valve 14, the input end of the hydrogen side pressure control module 220 is connected to the hydrogen side pressure transmitter 9, and the output end of the hydrogen side pressure control module 220 is connected to the hydrogen side gas valve 15.

[0092] Example 2 Pressure Control Method for PEM Hydrogen Production System

[0093] Take the 200kW electrolysis hydrogen production system as an example:

[0094] The electrolyzer 1 is in operation: the gas generated on the cathode plate of the electrolyzer 1 is transported to the hydrogen separator 3 through the cathode plate pipeline, and the hydrogen separator 3 contains hydrogen, water and a small amount of oxygen; the gas generated on the anode plate of the electrolyzer 1 is transported to the oxygen separator 2 through the anode plate pipeline, and the oxygen separator 2 contains oxygen, water and a small amount of hydrogen.

[0095] Hydrogen side liquid level control: Water in the hydrogen separator 3 accumulates continuously, and the signal of the water level in the hydrogen separator 3 is collected through the hydrogen side liquid level transmitter 11, and the measurement signal is converted into a 4-20mA DC signal and sent to the hydrogen side liquid level control module 140; when the height of the water level in the hydrogen separator 3 collected exceeds 72% of the height of the hydrogen separator 3, the hydrogen side liquid level control module 140 controls the hydrogen side drain valve 16 to open, and the water in the hydrogen separator 3 is injected into the oxygen separator 2 until the water level drops to 68% of the height of the oxygen separator 2. Figure 2 As shown, during the entire PEM hydrogen production process, the water level in the hydrogen separator is controlled at 68% to 72% of the height of the hydrogen separator 3 .

[0096] Oxygen side liquid level control: part of the water in the oxygen separator 2 comes from the electrolyzer 1 and the hydrogen separator 3, and the other part comes from the water supply tank 7. The water in the oxygen separator 2 is discharged through the drain port, and the water level information in the oxygen separator 2 is collected through the oxygen side liquid level transmitter 10, and the measurement signal is converted into a 4-20mA DC signal and sent to the oxygen side liquid level control module 130; as the system runs, the circulating water is continuously consumed, and when the water level in the oxygen separator 2 is detected to account for 60% of the height of the oxygen separator, the oxygen side water supply valve 17 is controlled to open, and pure water is injected into the oxygen separator 2 until it reaches 67% of the height of the oxygen separator, and then the oxygen side water supply valve 17 is closed. Combined with Figure 3 As shown, during the entire PEM hydrogen production process, the water level in the oxygen separator is controlled at 60% to 67% of the oxygen separator height. Temperature control: The inlet water temperature of the electrolyzer is set to 55°C. The inlet water temperature control module 110 adjusts the inlet water temperature by controlling the speed of the radiator 6. Figure 4 As shown in FIG. 1 , during the entire PEM hydrogen production process, the inlet water temperature is controlled at 54.3 to 57°C. The outlet water temperature of the electrolyzer is set to 60°C. The outlet water temperature processing module 120 adjusts the outlet water temperature by controlling the speed of the circulating water pump 4. Figure 5 As shown, during the entire PEM hydrogen production process, the outlet water temperature is controlled at 59.3-62°C.

[0097] Pressure control: Set the pressure of hydrogen separator 3 to 3Mpa and the pressure of oxygen separator 2 to 2.8Mpa, ensuring that the pressure of hydrogen separator 3 is continuously higher than the pressure of oxygen separator 2 by 0.2Mpa. The slight positive pressure of 0.2Mpa on the hydrogen side to the oxygen side can improve the purity of hydrogen in hydrogen separator 3. Fig.10 As shown, the concentration of oxygen in the hydrogen separator 3 is as low as 0.06-0.08%. After the above liquid level control and temperature control, the pressure in the hydrogen separator 3 and the oxygen separator 2 is only affected by the gas volume. The opening of the hydrogen side gas valve 15 of the hydrogen separator 3 and the opening of the oxygen side gas valve 14 in the oxygen separator 2 can be controlled accurately by controlling the oxygen side liquid level control module 130 and the hydrogen side liquid level control module 140 respectively. Figure 6 As shown, the PEM hydrogen production system of the present invention realizes precise control of the pressure in the hydrogen separator 3 and the oxygen separator 2 through liquid level control, temperature control and pressure control, and the pressure of the hydrogen separator 3 is precisely controlled at 3Mpa, and the pressure of the oxygen separator 2 is precisely controlled at 2.8Mpa.

[0098] Example 3 constructs a water inlet temperature control function model, a water outlet temperature control function model, a hydrogen side pressure control function model, and an oxygen side pressure control function model:

[0099] In the water inlet temperature control module 110, the rotation speed value of the radiator 6 is calculated by the water inlet temperature control function model, and the water inlet temperature of the electrolyzer 1 is controlled at 54.3-57°C through the water inlet temperature control module 110; in the water outlet temperature control module 120, the rotation speed value of the circulating water pump 4 is calculated by the water outlet temperature control function model, and the water outlet temperature of the electrolyzer 1 is controlled at 59.3-62°C through the water outlet temperature control module 120; in the hydrogen side pressure control module 220, the opening of the hydrogen side gas valve 15 is calculated by the hydrogen side pressure control function model, and the pressure value in the hydrogen separator 3 is accurately controlled at 3Mpa through the hydrogen side pressure control module 220; in the oxygen side pressure control module 210, the opening of the oxygen side gas valve 14 is calculated by the oxygen side pressure control function model, and the pressure value of the oxygen separator 2 is accurately controlled at 2.8Mpa through the oxygen side pressure control module 210.

[0100] based on Figure 7 The BP neural network PID controller structure shown in the figure constructs the inlet water temperature control function model, the outlet water temperature control function model, the hydrogen side pressure control function model and the oxygen side pressure control function model. The construction process includes the following steps:

[0101] (1) Real-time parameter K output by BP neural network p , K i , K d The specific determination process is:

[0102] The input function of the input layer of the BP neural network is as follows:

[0103]

[0104] The input function of the hidden layer is as follows:

[0105]

[0106] in, is the weight of the hidden layer.

[0107] The output function of the hidden layer is as follows:

[0108]

[0109] In formula (4), take

[0110] The input function of the output layer is as follows:

[0111]

[0112] In formula (5), is the weight of the output layer.

[0113] The three output functions of the output layer are as shown in formula (6):

[0114]

[0115] The value of l=1,2,3,K p , K i , K d The function is shown in formula (7):

[0116]

[0117] PID three parameters K p , K i , K d are all positive values, so the non-negative activation function sigmoid function is selected as the output layer activation function, as shown in formula (8):

[0118]

[0119] The performance index function is taken as the square of error, and the output layer activation function is shown in formula (9):

[0120]

[0121] The weights are corrected using the gradient descent method, and an inertia term is added to make the global minimum converge quickly. The function of the corrected weights of the output layer is as shown in formula (10):

[0122]

[0123] Among them, η is the learning rate, α is the inertia coefficient, Can be decomposed into:

[0124]

[0125] in, is the negative value of the error -e(k); It is impossible to determine, and the approximate value is obtained through the sgn function, that is, It can be expressed as the sigmoid function: is the output of the hidden layer It can be obtained from the expression formula of incremental PID:

[0126] According to the above analysis, the weight correction function of the output layer is shown in formula (11):

[0127]

[0128] Similarly, the weight correction function of the hidden layer is shown in formula (12):

[0129]

[0130] The algorithm flow of BIPID is as follows: Figure 8 As shown, in the first calculation, the weights of the hidden layer and the output layer are assigned and At the same time, the inertia coefficient α and the learning rate η are given; the target value r(k) and the actual output value y(k) are sampled, and the error e(k) = r(k) - y(k) is obtained; the three adjustable parameters K of the PID controller are output through the BP neural network p ,K i ,K d ; Calculate the direction error with the help of Δu(k): u(k)=u(k-1)+Δu(k); Compare the weights by target requirements and Perform optimization adjustment to achieve optimization adjustment of PID parameters; enter the next iteration and re-calculate the BP neural network.

[0131] (2) Function model of the controlled object:

[0132] When K p , K i , K d When is an adjustable parameter that changes with the system, the function model formula of the controlled object is as follows:

[0133]

[0134] (3) The controlled object is inlet temperature control. The function model of inlet temperature control is shown in formula (13) and formula (14):

[0135] Inlet temperature control, at time k, the radiator speed n in (k) As shown in formula (13):

[0136] n in (k) = n in (k-1)+Δn in (k) (13)

[0137] The increase in the radiator speed Δn in (k) As shown in formula (14):

[0138]

[0139] In formula (14), n in Indicates the speed of the radiator; e in It represents the error between the set inlet temperature and the actual inlet temperature, that is T ref inIndicates the set inlet temperature, T in Indicates the actual inlet temperature; K p in ,K i in ,K d in It represents the real-time parameters output by the BP neural network as shown in step (1) during inlet temperature control.

[0140] (4) The controlled object is outlet temperature control. The function model of outlet temperature control is shown in formula (15) and formula (16):

[0141] When the outlet temperature is controlled, at time k, the circulating water pump n out The speed is:

[0142] n out (k) = n out (k-1)+Δn out (k) (15)

[0143] The increment of the speed of the circulating water pump can be expressed as:

[0144]

[0145] Where n out Indicates the speed of the circulating water pump; e out It represents the error between the set outlet temperature and the actual outlet temperature, that is, e out =T ref out -T out ,T ref out Indicates the set outlet temperature, T out Indicates the actual outlet temperature; K p out ,K i out ,K d out It represents the real-time parameters of the BP neural network output obtained in step (1) during inlet temperature control.

[0146] (5) The controlled object is the hydrogen side pressure, and the hydrogen side pressure control function model is shown in formula (17) and formula (18):

[0147] When the hydrogen side pressure is controlled, at time k, the function model of the hydrogen side control valve opening is shown in formula (17):

[0148] D H (k) = D H (k-1)+ΔD H (k) (17)

[0149] The increase of the opening of the hydrogen side exhaust valve ΔD H (k) function is shown in formula (18):

[0150]

[0151] Where D H Indicates the opening of the hydrogen side valve; e H It indicates the error between the set pressure on the hydrogen side and the actual pressure on the hydrogen side, that is, e H =P ref H -P H ,P ref H Indicates the set pressure on the hydrogen side, P H represents the actual pressure on the hydrogen side; (k), (k-1), (k-2) represent the time at (k), (k-1), (k-2) respectively; K p H ,K i H ,K d H It represents the real-time parameters output by the BP neural network as shown in step (1) during hydrogen side pressure control.

[0152] (6) The controlled object is the oxygen side pressure, and the oxygen side pressure control function model is shown in formula (19) and formula (20):

[0153] When the oxygen side pressure is controlled, at time k, the opening of the control valve is:

[0154] D O (k) = D O (k-1)+ΔD O (k) (19)

[0155] The increment of the oxygen side exhaust valve opening can be expressed as:

[0156]

[0157] Where D O Indicates the valve opening on the oxygen side; e O It indicates the error between the set pressure on the oxygen side and the actual pressure on the oxygen side, that is, e O =P ref O -P O ,P ref O Indicates the oxygen side set pressure, P O Indicates the actual pressure on the oxygen side; K p O ,K i O ,K dO It represents the real-time parameters of the BP neural network output obtained in step (1) during oxygen side pressure control.

Claims

1. A PEM hydrogen production system, comprising an electrolyzer (1), an oxygen separator (2), a hydrogen separator (3), a radiator (6), a circulating water pump (4), and a water replenishment tank (7); the inlet of the electrolyzer (1) is provided with a water inlet temperature detector (12), and the outlet of the electrolyzer (1) is provided with a water outlet temperature detector (13); the hydrogen separator (3) is connected to the cathode plate of the electrolyzer (1), the oxygen separator (2) is connected to the anode plate of the electrolyzer (1), the top of the hydrogen separator (3) is provided with a hydrogen side gas valve (15), and the middle of the hydrogen separator (3) is provided with a hydrogen side liquid level transmitter (11) and a hydrogen side pressure transmitter (13). The hydrogen separator (3) is provided with a water inlet (9) at the bottom, the water outlet (16) at the bottom is connected to the water inlet (17) of the oxygen separator (2); the top of the oxygen separator (2) is provided with an oxygen side air valve (14); the middle of the oxygen separator (2) is provided with an oxygen side liquid level transmitter (10) and an oxygen side pressure transmitter (8); the water replenishment port (17) at the bottom of the oxygen separator (2) is connected to the water replenishment tank (7) via an oxygen side water replenishment valve (17); the water outlet (17) at the bottom of the oxygen separator (2) is connected to the radiator (6) and the circulating water pump (4) in sequence through a pipeline, and then connected to the water inlet (17) of the electrolytic cell (1) to form a circulating water passage; the characteristics are as follows: The PEM hydrogen production system also includes a primary pressure control unit (100) for reducing the interference of temperature and liquid level factors on pressure and a secondary pressure control unit (200) for accurately adjusting the system pressure; The primary pressure control unit (100) comprises a water inlet temperature control module (110), a water outlet temperature control module (120), an oxygen side liquid level control module (130) and a hydrogen side liquid level control module (140); the secondary pressure control unit (200) comprises an oxygen side pressure control module (210) and a hydrogen side pressure control module (220); the input end of the water inlet temperature control module (110) is connected to a water inlet temperature detector (12), and the output end of the water inlet temperature control module (110) is connected to a radiator (6); the input end of the water outlet temperature control module (120) is connected to a water outlet temperature detector (13), and the output end of the water outlet temperature control module (120) is connected to a circulating water pump (4); the oxygen side liquid level control module (130) and the hydrogen side liquid level control module (140) are connected to the oxygen side liquid level control module (210) and the hydrogen side liquid level control module (220) are connected to the oxygen side liquid level control module (210) and the hydrogen side liquid level control module (220) are connected to the oxygen side liquid level control module (210) and the hydrogen side liquid level control module (220) are connected to the oxygen side liquid level control module (130) and the hydrogen side liquid level control module (14 ... The input end of the module (130) is connected to the oxygen side liquid level transmitter (10), and the output end of the oxygen side liquid level control module (130) is connected to the oxygen side water replenishment valve (17); the input end of the hydrogen side liquid level control module (140) is connected to the hydrogen side liquid level transmitter (11), and the output end of the hydrogen side liquid level control module (140) is connected to the hydrogen side drainage valve (16); the input end of the oxygen side pressure control module (210) is connected to the oxygen side pressure transmitter (8), and the output end of the oxygen side pressure control module (210) is connected to the oxygen side gas valve (14); the input end of the hydrogen side pressure control module (220) is connected to the hydrogen side pressure transmitter (9), and the output end of the hydrogen side pressure control module (220) is connected to the hydrogen side gas valve (15).

2. A pressure control method for a PEM hydrogen production system as claimed in claim 1, characterized in that: Includes steps: (1) Primary anti-interference pressure control: The primary pressure control unit (100) is used to control the inlet and outlet water temperatures of the electrolyzer (1) and the liquid levels of the hydrogen separator (3) and the oxygen separator (2) in real time: (1.1) Control of the inlet water temperature and outlet water temperature of the electrolytic cell (1): the electrolytic cell (1) is in operation, the gas and entrained water generated by the cathode plate of the electrolytic cell (1) are transported to the hydrogen separator (3) through a pipeline, and the gas and entrained water generated by the anode plate of the electrolytic cell (1) are transported to the oxygen separator (2) through a pipeline; the inlet water temperature detector (12) collects the temperature of the inlet water of the electrolytic cell (1) and transmits the temperature signal to the inlet water temperature control module (110), and the inlet water temperature control module (110) adjusts the inlet water temperature by controlling the rotation speed of the radiator (6); the outlet water temperature detector (13) collects the temperature of the outlet water of the electrolytic cell (1) and transmits the temperature signal to the outlet water temperature control module (120), and the outlet water temperature control module (120) adjusts the outlet water temperature by controlling the rotation speed of the circulating water pump (4); (1.2) Hydrogen side liquid level control: Water in the hydrogen separator (3) accumulates continuously, and the water level signal in the hydrogen separator (3) is collected by the hydrogen side liquid level transmitter (11) and transmitted to the hydrogen side liquid level control module (140). The hydrogen side liquid level control module (140) adjusts the water level height of the hydrogen separator (3) by controlling the opening and closing of the hydrogen side drain valve (16); (1.3) Oxygen side liquid level control: The water inlet of the oxygen separator (2) comes from the hydrogen separator (3), the anode plate of the electrolytic cell (1) and the water supply tank (7). The oxygen separator (2) is drained through the bottom drain port. The oxygen side liquid level transmitter (10) collects the water level signal in the oxygen separator (2) and transmits it to the oxygen side liquid level control module (130). The oxygen side liquid level control module (130) adjusts the water level in the oxygen separator (2) by controlling the opening and closing of the oxygen side water supply valve (17). (2) Secondary precise pressure control: The pressure in the hydrogen separator (3) and the oxygen separator (2) is precisely controlled by the secondary pressure control unit (200): (2.1) Hydrogen separator pressure control: The hydrogen side pressure transmitter (9) collects the pressure of the hydrogen separator (3) in real time and transmits it to the hydrogen side pressure control module (220). The hydrogen side pressure control module (220) accurately controls the pressure of the hydrogen separator (3) by controlling the opening of the hydrogen side gas valve (15); (2.2) Oxygen separator pressure control: The oxygen side pressure transmitter (8) collects the pressure of the oxygen separator (2) in real time and transmits it to the oxygen side pressure control module (210). The oxygen side pressure control module (210) accurately controls the pressure of the oxygen separator (2) by controlling the opening of the oxygen side gas valve (14).

3. The pressure control method of the PEM hydrogen production system according to claim 2, characterized in that: In step (1), the water inlet temperature of the electrolyzer (1) is set to 55° C., and the water outlet temperature of the electrolyzer (1) is set to 60° C.; the water level of the oxygen separator (2) is set to account for 60% to 67% of the total height of the oxygen separator; the water level of the hydrogen separator (3) is set to account for 68% to 72% of the total height of the oxygen separator; in step (2), the pressure value in the hydrogen separator (3) is set to 3 Mpa, and the pressure value in the oxygen separator (2) is set to 2.8 Mpa.

4. The pressure control method of the PEM hydrogen production system according to claim 3, characterized in that: In step (1), according to the set value of 55° C. of the inlet water temperature of the electrolytic cell (1), the inlet water temperature control module (110) adjusts the inlet water temperature by controlling the rotation speed of the radiator (6). The specific process is: In the water inlet temperature control module (110), the rotation speed value of the radiator (6) is calculated by the water inlet temperature control function model, and the water inlet temperature of the electrolytic cell (1) is controlled at 54.3-57° C. by the water inlet temperature control module (110); the water inlet temperature control function model is constructed based on the BP neural network, and the water inlet temperature control function model is shown in formulas (13) and (14): n in (k)=n in (k-1)+Δn in (k) (13) In formula (13), n in (k) represents the speed of the radiator at time k, n in (k-1) represents the speed of the radiator at time k-1, Δn in (k) represents the increment of the rotation speed of the radiator; The increase in the radiator speed Δn in (k) As shown in formula (14): In formula (14), n in Indicates the speed of the radiator; e in It indicates the error between the set water inlet temperature and the actual water inlet temperature, that is, e in =T refin -T in ,T refin Indicates the set water inlet temperature, T in Indicates the actual inlet water temperature; K p in ,K i in ,K d in It represents the real-time parameters output by the BP neural network during inlet water temperature control.

5. The pressure control method of the PEM hydrogen production system according to claim 3, characterized in that: In step (1), according to the set value of 60° C. of the outlet water temperature of the electrolytic cell (1), the outlet water temperature processing module (120) adjusts the outlet water temperature by controlling the rotation speed of the circulating water pump (4). The specific process is: In the outlet water temperature control module (120), the speed value of the circulating water pump (4) is calculated by the outlet water temperature control function model, and the outlet water temperature of the electrolytic cell (1) is controlled within the range of 59.3 to 62° C. by the outlet water temperature control module (120). The outlet water temperature control function model is constructed based on the BP neural network, and the outlet water temperature control function model is shown in formulas (15) and (16): n out (k)=n out (k-1)+Δn out (k) (15) In formula (15), n out (k) represents the speed of the circulating water pump at time k, n out (k-1) represents the speed of the circulating water pump at time k-1, Δn out (k) represents the increment of the rotation speed of the circulating water pump; Where n out Indicates the speed of the circulating water pump; e out It represents the error between the set outlet temperature and the actual outlet temperature, that is, e out =T ref out -T out ,T ref out Indicates the set outlet temperature, T out Indicates the actual outlet temperature; K p out ,K i out ,K d out It represents the real-time parameters output by the BP neural network during outlet temperature control.

6. The pressure control method of the PEM hydrogen production system according to claim 3, characterized in that: In step (1), according to the water level setting value of 60% to 67% of the oxygen separator (2), the oxygen side liquid level control module (130) adjusts the water level in the oxygen separator (2) by controlling the opening and closing of the oxygen side water supply valve (17) as follows: When the water level collected by the oxygen side liquid level transmitter (10) is lower than 60%, the oxygen side liquid level control module (130) controls the oxygen side water replenishment valve (17) to open; when the water level collected by the oxygen side liquid level transmitter is higher than 67%, the oxygen side liquid level control module (130) controls the oxygen side water replenishment valve (17) to close; the water level height of the oxygen separator (2) is controlled at 60% to 67% by the oxygen side liquid level control module (130).

7. The pressure control method of the PEM hydrogen production system according to claim 3, characterized in that: In step (1), according to the water level setting value of 68% to 72% of the hydrogen separator (3), the hydrogen side liquid level control module (140) adjusts the water level in the hydrogen separator (3) by controlling the opening and closing of the hydrogen side drain valve (16) as follows: When the water level collected by the hydrogen side liquid level transmitter (11) is lower than 68%, the hydrogen side liquid level control module (140) controls the hydrogen side water replenishment valve (16) to open; when the water level collected by the hydrogen side liquid level transmitter (11) is higher than 72%, the hydrogen side liquid level control module (140) controls the hydrogen side water drain valve (16) to close; and the water level height of the hydrogen separator (3) is controlled at 68% to 72% by the hydrogen side liquid level control module (140).

8. The pressure control method of the PEM hydrogen production system according to claim 3, characterized in that: In step (2), according to the pressure setting value of 3Mpa in the hydrogen separator (3), the hydrogen side pressure control module (220) accurately controls the pressure of the hydrogen separator (3) by adjusting the opening of the hydrogen side gas valve (15) as follows: The hydrogen side pressure control module (220) calculates the opening of the hydrogen side gas valve (15) through the hydrogen side pressure control function model, and the pressure value in the hydrogen separator (3) is accurately controlled at 3Mpa through the hydrogen side pressure control module (220). The hydrogen side pressure control function model is constructed based on the BP neural network, and the hydrogen side pressure control function model is shown in formulas (17) and (18): D H (k)=D H (k-1)+ΔD H (k) (17) In formula (17), D H (k) represents the opening of the hydrogen side control valve at time k, D H (k-1) represents the opening of the hydrogen side control valve at time k-1, ΔD H (k) represents the increment of the opening of the hydrogen side exhaust valve; The increase of the opening of the hydrogen side exhaust valve ΔD H (k) function is shown in formula (18): Where D H Indicates the opening of the hydrogen side valve; e H It indicates the error between the set pressure on the hydrogen side and the actual pressure on the hydrogen side, that is, e H =P ref H -P H ,P ref H Indicates the set pressure on the hydrogen side, P H represents the actual pressure on the hydrogen side; (k), (k-1), (k-2) represent the time at (k), (k-1), (k-2) respectively; K p H ,K i H ,K d H It represents the real-time parameters output by the BP neural network during hydrogen side pressure control.

9. The pressure control method of the PEM hydrogen production system according to claim 3, characterized in that: In step (2), according to the pressure setting value of 2.8 Mpa in the oxygen separator, the oxygen side pressure control module (210) accurately controls the pressure of the oxygen separator (2) by adjusting the opening of the oxygen side gas valve (14); The oxygen side pressure control module (210) calculates the opening of the oxygen side gas valve (14) through the oxygen side pressure control function model, and the pressure value of the oxygen separator (2) is accurately controlled at 2.8 MPa through the oxygen side pressure control module (210). The oxygen side pressure control function model is constructed based on the BP neural network, and the oxygen side pressure control function model is shown in formulas (19) and (20): D O (k)=D O (k-1)+ΔD O (k) (19) In formula (19), D O (k) represents the opening value of the oxygen side valve at time k, D O (k-1) represents the opening value of the oxygen side valve at time k-1, ΔD O (k) is the opening increment of the oxygen side valve; The increase of oxygen side exhaust valve opening ΔD O (k) can be expressed as: Where D O Indicates the valve opening on the oxygen side; e O It indicates the error between the set pressure on the oxygen side and the actual pressure on the oxygen side, that is, e O =P ref O -P O ,P ref O Indicates the oxygen side set pressure, P O Indicates the actual pressure on the oxygen side; K p O ,K i O ,K d O It represents the real-time parameters output by the BP neural network during oxygen side pressure control.

10. The pressure control method of a PEM hydrogen production system according to any one of claims 4, 5, 8 and 9, characterized in that: When the BP neural network is calculated for the first time, the weights of the hidden layer and the output layer are assigned and At the same time, the inertia coefficient α and the learning rate η are given; the target value r(k) and the actual output value y(k) are sampled, and the error e(k) = r(k) - y(k) is obtained; the three adjustable parameters K of the PID controller are output through the BP neural network p ,K i ,K d ; Calculate the direction error with the help of Δu(k): u(k)=u(k-1)+Δu(k); Compare the weights by target requirements and Carry out optimization adjustment to achieve optimization adjustment of PID parameters; Enter the next iteration and recalculate the BP neural network; Among them, the three adjustable parameters K of the output p , K i , K d The specific determination process is: The input function of the input layer of the BP neural network is as follows: The input function of the hidden layer is as follows: in, is the weight of the hidden layer; The output function of the hidden layer is as follows: In formula (4), take The input function of the output layer is as follows: In formula (5), is the weight of the output layer; The three output functions of the output layer are as shown in formula (6): The value of l=1,2,3,K p , K i , K d The function is shown in formula (7): The weight correction function of the output layer is shown in formula (11): Similarly, the weight correction function of the hidden layer is shown in formula (12):

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