Control method of PEM water electrolysis hydrogen production and water supplement system

Abstract

The invention discloses a control method of a PEM water electrolysis hydrogen production and water replenishing system, which comprises the following steps: acquiring electrolytic bath operating parameters, water tank liquid level meter reading, water tank temperature reading and water tank pressure reading, calculating a predicted liquid level value and a liquid level difference value, and obtaining a root mean square error of the water tank liquid level meter reading; the predicted liquid level value is compared with the water supplementing liquid level range, and a water supplementing control signal is generated; comparing the root-mean-square error with a preset value to generate a class of fault judgment signals; the liquid level difference value is compared with a preset fault liquid level range, and a second-class fault judgment signal is generated; according to the water replenishing control signal, controlling the water purifier to be switched on or switched off for drainage; according to the first-class fault judgment signal, a fault prompt is sent out or a predicted liquid level value is corrected; and according to the second-class fault judgment signal, abnormal prompt, shutdown check and / or normal operation are sent out. Therefore, the system can recognize systematic deviation and diagnose system faults in time, potential damage is avoided, the water replenishing process is effectively optimized, and the overall safety and reliability are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen production by electrolyzing water, and particularly to a control method for a water replenishing system of PEM electrolytic water hydrogen production. Background Art

[0002] The PEM electrolytic water hydrogen production system includes a water replenishing system, which usually includes a water tank, a primary steam-water separator, and a secondary steam-water separator. The water inlet of the water tank is respectively connected to a pure water machine, the anode outlet of the electrolytic cell, the drain outlet of the primary steam-water separator, and the drain outlet of the secondary steam-water separator. The water outlet of the water tank is respectively connected to a drain valve and the anode inlet of the electrolytic cell. During actual operation, there is consumption and replenishment in the water tank. Therefore, the prediction of the liquid level in the water tank is crucial for water replenishment. Moreover, when the liquid level gauge in the water tank fails, the prediction of the water tank liquid level becomes inaccurate, seriously affecting the water replenishment and service life of the water replenishing system. Summary of the Invention

[0003] Aiming at the above deficiencies, the technical problem to be solved by the present invention is: to provide a control method for a water replenishing system of PEM electrolytic water hydrogen production, which can identify systematic deviations and diagnose system failures in a timely manner, avoid potential system damage, prevent the further deterioration of failures; and can also effectively optimize the water replenishing process, and at the same time has the functions of early failure identification and warning, which has a significant effect on improving the overall safety and reliability.

[0004] To solve the above technical problems, the technical solution of the present invention is:

[0005] A control method for a water replenishing system of PEM electrolytic water hydrogen production includes the following steps:

[0006] S10. Obtain the operating parameters of the electrolytic cell, the reading of the water tank liquid level gauge, and the readings of the water tank temperature and pressure;

[0007] S20. Calculate the predicted liquid level value L of the water tank simu ;

[0008] According to the reading of the water tank liquid level gauge, obtain the root mean square error RMSE of the reading of the water tank liquid level gauge;

[0009] Then calculate the liquid level difference L d , and the liquid level difference L d is the difference between the reading of the water tank liquid level gauge and the predicted liquid level value L simu ;

[0010] S30. Compare the predicted liquid level value L simu with a preset water replenishing liquid level range, and generate a corresponding water replenishing control signal according to the comparison result;

[0011] Compare the root mean square error RMSE with a preset value m, and generate a corresponding type of fault judgment signal according to the comparison result;

[0012] Compare the liquid level difference L d with a preset fault liquid level range, and generate a corresponding type of fault judgment signal according to the comparison result;

[0013] S40. Control the pure water machine to close, open or open the water tank drain valve according to the water replenishment control signal;

[0014] According to the type of fault judgment signal, issue a systematic error fault prompt or correct the predicted liquid level value;

[0015] According to the type of fault judgment signal, issue a water tank abnormality prompt, a water tank liquid level gauge abnormality prompt, stop for inspection and / or normal operation.

[0016] Preferably, in step S30, comparing the predicted liquid level value L simu with a preset water replenishment liquid level range, and generating a corresponding water replenishment control signal according to the comparison result, includes:

[0017] Judge whether the predicted liquid level value L simu is within the preset water replenishment liquid level range;

[0018] If the predicted liquid level value L simu is within the preset water replenishment liquid level range, the generated water replenishment control signal is a closing signal;

[0019] If the predicted liquid level value L simu is less than the minimum liquid level L l in the preset water replenishment liquid level range, the generated water replenishment control signal is an opening signal;

[0020] If the predicted liquid level value L simu is greater than the maximum liquid level L h in the preset water replenishment liquid level range, the generated water replenishment control signal is a drainage signal;

[0021] The step of controlling the pure water machine to close, open or open the water tank drain valve according to the water replenishment control signal in step S40 includes:

[0022] According to the closing signal, close the pure water machine;

[0023] According to the opening signal, open the pure water machine for water replenishment, and the opening time of the pure water machine is t;

[0024] According to the drainage signal, open the water tank drain valve to drain water.

[0025] Preferably, the root mean square error RMSE is a preset value, or the root mean square error RMSE is calculated using the following formula:

[0026]

[0027] where n is the number of samples, L test is the reading of the water tank level gauge, and L simu is the predicted level value.

[0028] Preferably, in step S30, the step of comparing the root mean square error RMSE with a preset value m and generating a corresponding type of fault judgment signal according to the comparison result includes the following steps:

[0029] S300. Determine whether the root mean square error RMSE is less than or equal to the preset value m;

[0030] S301. If the root mean square error RMSE is not less than or equal to the preset value m, generate a corresponding type of fault judgment signal as a systematic error fault signal;

[0031] S302. If the root mean square error RMSE is less than or equal to the preset value m, generate a corresponding type of fault judgment signal as a level correction signal;

[0032] In step S40, the step of issuing a systematic error fault prompt or correcting the predicted level value according to the type of fault judgment signal includes:

[0033] Issue a systematic error fault prompt according to the systematic error fault signal;

[0034] Correct the predicted level value according to the level correction signal.

[0035] Preferably, S301 includes:

[0036] S3010. If the root mean square error RMSE is not less than or equal to the preset m, start timing t err , a ;

[0037] S3011. When t err , a is greater than the preset time t err , generate a corresponding type of fault judgment signal as a systematic error fault signal;

[0038] When t err , a is not greater than the preset time t err , execute S300;

[0039] S302 includes:

[0040] S3020. If the root mean square error RMSE is less than or equal to the preset value m, determine whether the liquid level compensation value L d1 is less than the preset value o, where the liquid level compensation value L d1 is the liquid level difference L d ;

[0041] S3021. If the liquid level compensation value L d1 is less than the preset value o, generate a corresponding type I fault judgment signal for liquid level value correction.

[0042] Preferably, the predicted liquid level value correction includes:

[0043] When the predicted liquid level value L simu is within the preset water replenishment liquid level range,

[0044] let L simu = L simu0 - L d0 - L d1 where L simu0 is the initial liquid level value of the water tank,

[0045] where ΔQ H2O is the volume flow rate of the water volume difference in the water tank,

[0046] where A is the bottom area of the water tank, N H2O is the amount of water in the electrolytic cathode flow channel per unit time, M H2O is the relative molecular mass of water;

[0047] When the predicted liquid level value L simu is less than the minimum liquid level L l in the preset water replenishment liquid level range,

[0048] let where L simu0 is the initial liquid level value of the water tank, Q in is the water flow rate entering the water tank after the pure water machine is turned on, A tank is the bottom area of the water tank.

[0049] Preferably, in S30, the step of comparing the liquid level difference L d with the preset fault liquid level range and generating a corresponding type II fault judgment signal according to the comparison result includes:

[0050] Determine whether the liquid level difference L d is greater than the preset values p or q;

[0051] If the liquid level difference L d is greater than the preset values p or q, the generated type II fault judgment signal is a prompt signal;

[0052] If the liquid level difference L d is not greater than the preset value p or q, the generated secondary fault judgment signal is a normal signal;

[0053] In step S40, according to the secondary fault judgment signal, the steps of normal operation, sending a water tank abnormality prompt, a water tank level gauge abnormality prompt, and / or stopping for inspection include:

[0054] According to the prompt signal, send a water tank abnormality prompt, a water tank level gauge abnormality prompt, and stop for detection;

[0055] According to the normal signal, operate normally.

[0056] Preferably, the step of judging whether the liquid level difference L d is greater than the preset value p or q includes:

[0057] Judge whether the reading of the water tank level gauge is greater than or equal to the predicted liquid level value L si,u +p;

[0058] If the reading of the water tank level gauge is greater than or equal to the predicted liquid level value L si,u +p, the generated secondary fault judgment signal is a prompt signal;

[0059] If the reading of the water tank level gauge is not greater than or equal to the predicted liquid level value L simu +p, the generated secondary fault judgment signal is a normal signal;

[0060] Judge whether the reading of the water tank level gauge is less than or equal to the predicted liquid level value L simu -q;

[0061] If the reading of the water tank level gauge is less than or equal to the predicted liquid level value L simu -q, the generated secondary fault judgment signal is a prompt signal;

[0062] If the reading of the water tank level gauge is not less than or equal to the predicted liquid level value L simu -q, the generated secondary fault judgment signal is a normal signal.

[0063] Preferably, the water volume difference ΔN of the water tank H2O is calculated using a preset heat management system water replenishment system model, and the heat management system water replenishment system model includes:

[0064] ΔN H2O＝ ΔN H2O,e +ΔN H2O,PEM +ΔN sep +ΔN vap,t +ΔN cl ;

[0065] Where: ΔNH2O,e is the amount of water electrolyzed, ΔN H2O,PEM is the amount of water transferred across the membrane to the cathode and carried away by the gas, ΔN sep is the amount of water evaporated, ΔN vap,t is the amount of recycled water, ΔN cl is to correct the amount of water in the water tank according to the changing water tank temperature and electrolyzer temperature.

[0066] Preferably, it is applied to the water replenishing system for PEM electrolytic water hydrogen production. The water replenishing system includes a water tank, an electrolyzer, a first-stage steam-water separator, and a second-stage steam-water separator; a first temperature sensor is arranged at the anode outlet of the electrolyzer, and a first pressure sensor is arranged at the cathode outlet of the electrolyzer; the first-stage steam-water separator is connected to the cathode outlet of the electrolyzer, the outlet of the first-stage steam-water separator is connected to a first drain valve, and a first liquid level gauge is arranged on the first-stage steam-water separator; the second-stage steam-water separator is connected to the first-stage steam-water separator, the outlet of the second-stage steam-water separator is connected to a second drain valve, and a second liquid level gauge is arranged on the second-stage steam-water separator; the first water inlet of the water tank is connected to a pure water machine, the second water inlet is connected to the anode outlet of the electrolyzer, and the third water inlet is respectively connected to the first drain valve and the second drain valve; the first water outlet of the water tank is connected to the anode inlet of the electrolyzer, and the second water outlet is connected to a third drain valve; a second temperature sensor, a second pressure sensor, and a water tank liquid level gauge are respectively arranged on the water tank.

[0067] After adopting the above technical solution, the beneficial effects of the present invention are:

[0068] Due to the control method of the water replenishment system for PEM electrolytic water hydrogen production of the present invention, first obtain the water volume difference of the water tank and the reading of the water tank level gauge; calculate the predicted liquid level value of the water tank according to the water volume difference of the water tank; obtain the root mean square error of the reading of the water tank level gauge according to the reading of the water tank level gauge; then calculate the liquid level difference, and the liquid level difference is the difference between the reading of the water tank level gauge and the predicted liquid level value; compare the predicted liquid level value with the preset water replenishment liquid level range, and generate a corresponding water replenishment control signal according to the comparison result; compare the root mean square error with the preset value, and generate a corresponding type I fault judgment signal according to the comparison result; compare the liquid level difference with the preset fault liquid level range, and generate a corresponding type II fault judgment signal according to the comparison result; control the pure water machine to close, open or open the water tank drain valve according to the water replenishment control signal; issue a systematic error fault prompt or correct the predicted liquid level value according to the type I fault judgment signal; issue a water tank abnormality prompt, a water tank level gauge abnormality prompt, shutdown inspection and / or normal operation according to the type II fault judgment signal. It can be seen that after adopting the control method of the present invention, it is possible to identify systematic deviations and timely diagnose system faults, avoid potential system damage, and prevent the further deterioration of faults; it can effectively optimize the water replenishment process of the PEM electrolytic water hydrogen production system, and at the same time has the functions of early fault identification and early warning, which has a significant effect on improving the overall safety and reliability. Brief Description of the Drawings

[0069] Figure 1 is a schematic diagram of the water replenishment system of the PEM electrolytic water hydrogen production system in the present invention;

[0070] Figures 2 to 3 is a schematic flow chart of the control method of the PEM electrolytic water hydrogen production water replenishment system in the present invention;

[0071] In the figure: 1 - electrolytic cell, 2 - water tank, 3 - first stage steam-water separator, 4 - second stage steam-water separator, 5 - water pump, 6 - first drain valve, 7 - second drain valve, 8 - third drain valve, 9 - pure water machine, 10 - first level gauge, 11 - second level gauge, 12 - water tank level gauge, 13 - first pressure sensor, 14 - first temperature sensor, 15 - second temperature sensor, 16 - second pressure sensor. Detailed Description of the Invention

[0072] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0073] It should be noted that in the description of the present invention, the terms indicating the direction or positional relationship such as "upper", "lower", "left", "right", "inner", "outer", etc. are based on the direction or positional relationship shown in the drawings. This is only for convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention.

[0074] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installation", "connection", and "coupling" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0075] The control method of the PEM electrolytic water hydrogen production water replenishment system of the present invention is applied to the PEM electrolytic water hydrogen production water replenishment system. Refer to Figure 1 , the water replenishment system includes a water tank 2, an electrolytic cell 1, a primary steam-water separator 3, and a secondary steam-water separator 4. A first temperature sensor 14 is provided at the anode outlet of the electrolytic cell 1, and a first pressure sensor 13 is provided at the cathode outlet of the electrolytic cell 1; the primary steam-water separator 3 is connected to the cathode outlet of the electrolytic cell 1, the outlet of the primary steam-water separator 3 is connected to a first drain valve 6, and a first liquid level gauge 10 is provided on the primary steam-water separator 3; the secondary steam-water separator 4 is connected to the primary steam-water separator 3, the outlet of the secondary steam-water separator 4 is connected to a second drain valve 7, and a second liquid level gauge 11 is provided on the secondary steam-water separator 4; the first water inlet of the water tank 2 is connected to a pure water machine 9, the second water inlet is connected to the anode outlet of the electrolytic cell 1 through a water pump 5, and the third water inlet is respectively connected to the first drain valve 6 and the second drain valve 7; the first water outlet of the water tank 2 is connected to the anode inlet of the electrolytic cell 1, and the second water outlet is connected to a third drain valve 8; a second temperature sensor 15, a second pressure sensor 16, and a water tank liquid level gauge 12 are respectively provided on the water tank 2.

[0076] As Figure 2 and Figure 3 shown, the control method of the PEM electrolytic water hydrogen production water replenishment system of the present invention includes the following steps:

[0077] Step S10: Obtain the operating parameters of the electrolytic cell, the reading L test of the water tank liquid level gauge

[0078] and the readings of the water tank temperature and pressure; simu ;

[0079] It should be noted that: the predicted liquid level value Lsimu It can be calculated by using a preset water replenishment system model of the thermal management system. Input the electrolyzer current, voltage, target temperature, the flow temperature of the coolant at the electrolyzer outlet, and the pressure at the cathode outlet of the electrolyzer. The flow temperature of the coolant at the electrolyzer outlet can be detected by a first temperature sensor, and the pressure at the cathode outlet of the electrolyzer can be detected by a first pressure sensor.

[0080] L simu = L simu0 + L d0 , specifically, the predicted liquid level value L simu is the predicted liquid level value L of the previous second simu0 plus the difference, where

[0081] ΔQ H2o is the volume flow rate of the water quantity difference in the water tank,

[0082] A is the bottom area of the water tank, N H2O is the amount of water in the electrolytic cathode flow channel per unit time, M H2O is the relative molecular mass of water.

[0083] where the water quantity difference ΔN in the water tank H2O , can be calculated by using a preset water replenishment system model of the thermal management system. The water replenishment system model of the thermal management system specifically includes:

[0084] ΔN H2O＝ ΔN H2O,e + ΔN H2O,PEM + ΔN sep + ΔN vap,t + ΔN cl ;

[0085] where: ΔN H2O,e is the amount of water electrolyzed, ΔN H2O,PEM is the amount of water transferred across the membrane to the cathode and carried away by the gas, ΔN sep is the amount of evaporated water, ΔN vap,t is the amount of recycled water, ΔN cl is to correct the water quantity in the water tank according to the changing water tank temperature and electrolyzer temperature. Additionally, referring to Figure 2 , the operating parameters of the electrolyzer can be input into the electrolyzer temperature model to calculate ΔN H2O,PEM . The actual temperature of the coolant is detected by a first temperature sensor, the coolant flow rate is calculated by using the electrolyzer temperature model, and then the actual temperature of the coolant and the input coolant flow rate are input into the saturated vapor pressure equation to calculate the amount of water vapor ΔN at the cathode outlet sep ; The liquid level values detected by the first liquid level gauge and the second liquid level gauge, and the water tank parameters are input into the water tank model to calculate ΔN vap,t and ΔNcl 。

[0086] According to the reading of the water tank level gauge, obtain the root mean square error RMSE of the reading of the water outlet tank level gauge; where the reading of the water tank level gauge is the measured liquid level value L detected by the water tank level gauge set in the water tank test 。

[0087] It should be noted that: the root mean square error RMSE can be a preset value, and a reasonable RMSE value is calibrated according to the operating data of the selected sensor accuracy to simulate the operating conditions.

[0088] Or, it is calculated using the following formula:

[0089] where n is the number of samples, that is, n measured data collected within a certain period of time, L test is the reading of the water tank level gauge, L simu is the predicted liquid level value.

[0090] Then calculate the liquid level difference L d , the liquid level difference L d is the difference between the reading of the water tank level gauge and the predicted liquid level value L simu ; that is, L d = L test - L simi 。

[0091] Step S30: Compare the predicted liquid level value L simu with the preset water replenishment level range, and generate a corresponding water replenishment control signal according to the comparison result to obtain a reasonable water replenishment plan, where the water replenishment level range can be [L l , L h .

[0092] Compare the root mean square error RMSE with the preset value m, and generate a corresponding type-I fault judgment signal according to the comparison result to diagnose the systematic error fault;

[0093] Compare the liquid level difference L d with the preset fault liquid level range, and generate a corresponding type-II fault judgment signal according to the comparison result to diagnose the water tank and water tank level gauge faults;

[0094] Step S40: Control the pure water machine to close, open or open the water tank drain valve according to the water replenishment control signal;

[0095] Send a systematic error fault prompt or correct the predicted liquid level value according to the type-I fault judgment signal;

[0096] Send a water tank abnormality prompt, a water tank level gauge abnormality prompt, stop for inspection and / or normal operation according to the type-II fault judgment signal.

[0097] The control method of the PEM electrolytic water hydrogen production water replenishment system of the present invention utilizes preset thermal management water replenishment models, electrolytic cell temperature models, water tank models, etc. to obtain the water volume difference in the water tank, calculate the predicted liquid level value and liquid level difference of the water tank, and then calculate the root mean square error of the water tank liquid level gauge reading. By judging the change trend of the liquid level in the current water tank through the predicted liquid level value, reasonable water replenishment, drainage and maintenance are carried out to provide the service life of the water tank, and then extend the service life of the water replenishment system and the PEM electrolytic water hydrogen production system. That is, by constructing mathematical models of the electrolytic cell, thermal management and water replenishment system, the present invention can predict the change trend of the liquid level in the water tank, obtain the water replenishment strategy, and ensure the long-term operation of the water replenishment system;

[0098] The present invention also utilizes the liquid level difference and the root mean square error to diagnose systematic error faults and water tank and water tank liquid level gauge faults, so as to process them in a timely manner and avoid the further expansion of faults. It can be seen that the present invention can identify systematic deviations and diagnose system faults in a timely manner, avoid potential system damage, and prevent the further deterioration of faults; it can effectively optimize the water replenishment process of the PEM electrolytic water hydrogen production system, and at the same time has the function of early fault identification and warning, which plays a significant role in improving the overall safety and reliability. Moreover, the operation of the present invention is simple and easy to implement.

[0099] As Figure 2 shown, in step S30 of this embodiment, the predicted liquid level value L simu is compared with the preset water replenishment liquid level range, and according to the comparison result, the corresponding water replenishment control signal is generated. The specific steps are as follows:

[0100] Judge whether the predicted liquid level value L simu is within the preset water replenishment liquid level range; that is, whether L simu is within the interval of [L l , L h ;

[0101] If the predicted liquid level value L simu is within the preset water replenishment liquid level range, the generated water replenishment control signal is a closing signal; that is, at this time, no water replenishment is required, so the pure water machine is turned off.

[0102] If L simu is not within the interval of [L l , L h , and the predicted liquid level value L simu is less than the minimum liquid level L l in the preset water replenishment liquid level range, the generated water replenishment control signal is an opening signal; indicating that the water level in the water tank is lower than the minimum value at this time and water replenishment is required.

[0103] If L simu is not within the interval of [Ll , L h within the interval, predict the liquid level value L simu is greater than the maximum liquid level L in the pre-set water replenishment liquid level range h , the generated water replenishment control signal is a drainage signal; indicating that there is excess water in the water tank.

[0104] In step S40, according to the water replenishment control signal, the steps of controlling the pure water machine to close, open or open the water tank drain valve include:

[0105] According to the closing signal, close the pure water machine;

[0106] According to the opening signal, open the pure water machine for water replenishment, and the opening time of the pure water machine is t;

[0107] According to the drainage signal, open the water tank drain valve to drain water.

[0108] Through the above steps, the present invention realizes reasonable water replenishment and drainage of the water tank, enables the water tank to continuously and stably supply water to the electrolytic cell, ensures an effective water seal, and guarantees the airtightness and safety of the water replenishment system.

[0109] Such as Figure 2 and Figure 3 As shown, in step S30 of this embodiment, comparing the root mean square error RMSE with a pre-set value m, and generating corresponding first-class fault judgment signals according to the comparison result, that is, the first-class fault diagnosis includes the following steps:

[0110] Step S300, determine whether the root mean square error RMSE is less than or equal to the pre-set value m;

[0111] Step S301, if the root mean square error RMSE is not less than or equal to the pre-set value m, generate the corresponding first-class fault judgment signal as a systematic error fault signal;

[0112] Step S302, if the root mean square error RMSE is less than or equal to the pre-set value m, generate the corresponding first-class fault judgment signal as a liquid level correction signal;

[0113] In step S40, according to the first-class fault judgment signal, the steps of issuing a systematic error fault prompt or performing prediction liquid level value correction include:

[0114] According to the systematic error fault signal, issue a systematic error fault prompt;

[0115] According to the liquid level correction signal, perform prediction liquid level value correction.

[0116] It should be noted that: according to the n test data points collected from the feedback signal of the liquid level gauge and the n simulation values calculated by the model, substitute them into the RMSE calculation formula to evaluate the RMSE value. If the RMSE value is greater than m, it is considered that there is a systematic fault, and the collected data has an overall deviation. It is recommended to check the layout of the liquid level gauge and whether there is a leak in the system.

[0117] In step S301 of this embodiment, it specifically includes:

[0118] Step S3010: If the root mean square error RMSE is not less than or equal to the preset m, start timing t err , a ;

[0119] Step S3011: When t err , a is greater than the preset time t err , generate a corresponding type of fault judgment signal as a systematic error fault signal;

[0120] When t err , a is not greater than the preset time t err , execute step S300;

[0121] In step S302 of this embodiment, it specifically includes:

[0122] Step S3020: If the root mean square error RMSE is less than or equal to the preset value m, judge whether the liquid level compensation value L d1 is less than the preset value o, where the liquid level compensation value L d1 is the liquid level difference L d ;

[0123] Step S3021: If the liquid level compensation value L d1 is less than the preset value o, generate a corresponding type of fault judgment signal as liquid level value correction, that is, when there is a type of fault, do not perform prediction liquid level value correction - compensation, and when there is no type of fault, perform prediction liquid level value correction to reasonably predict the change trend of the liquid level in the water tank.

[0124] In the present invention, the prediction liquid level value correction specifically includes:

[0125] When the predicted liquid level value L simu is within the preset water replenishment liquid level range,

[0126] Let L simu = L simu0 - L d0 - L d1 , where L simu0 is the initial liquid level value of the water tank,

[0127] where ΔQ H2O is the volume flow rate of the difference in water volume in the water tank,

[0128] where A is the bottom area of the water tank, and N H2O is the amount of water in the electrolytic cathode flow channel per unit time, and M H2O is the relative molecular mass of water;

[0129] When the predicted liquid level value L simu is less than the minimum liquid level L in the preset water replenishment liquid level range l at this time,

[0130] let where L simu0 is the initial liquid level value of the water tank, and Q in is the water flow rate entering the water tank after the pure water machine is turned on; A tank is the bottom area of the water tank.

[0131] By comparing the predicted value output by the system model with the actual value and analyzing their root mean square error RMSE, the present invention can identify systematic deviations and diagnose system faults in a timely manner, avoid potential system damage, and prevent the further deterioration of faults. The control strategy proposed by the present invention can effectively optimize the water replenishment process of the PEM electrolytic water hydrogen production system, and at the same time has the functions of early fault identification and warning, which plays a significant role in improving the overall safety and reliability of the system.

[0132] By comparing the simulated liquid level value with the actual test value and supplementing with the quantitative analysis of RMSE, potential faults in the system can be discovered in advance, and the causes of the faults can be analyzed. This early warning mechanism can timely identify abnormalities at the component or system level, avoid the sudden outbreak of faults, and plays a significant role in maintaining system safety and extending system life.

[0133] As Figure 2 and Figure 3 shown, in step S30 of the present invention, the liquid level difference L d is compared with the preset fault liquid level range, and according to the comparison result, the corresponding secondary fault judgment signal step is generated, which specifically includes:

[0134] Judge whether the liquid level difference L d is greater than the preset values p or q;

[0135] If the liquid level difference L d is greater than the preset values p or q, the generated secondary fault judgment signal is a prompt signal;

[0136] If the liquid level difference L d is not greater than the preset values p or q, the generated secondary fault judgment signal is a normal signal;

[0137] In step S40, according to the secondary fault judgment signal, the steps of normal operation, giving a water tank abnormality prompt, a water tank liquid level gauge abnormality prompt, and / or stopping for inspection include:

[0138] According to the prompt signal, give a water tank abnormality prompt, a water tank liquid level gauge abnormality prompt, and stop for detection;

[0139] According to the normal signal, operate normally.

[0140] As Figure 3 shown, the step of judging whether the liquid level difference L d is greater than the preset value p or q includes:

[0141] Judge whether the reading of the water tank liquid level gauge is greater than or equal to the predicted liquid level value L simu +p;

[0142] If the reading of the water tank liquid level gauge is greater than or equal to the predicted liquid level value L simu +p, the generated secondary fault judgment signal is a prompt signal;

[0143] If the reading of the water tank liquid level gauge is not greater than or equal to the predicted liquid level value L simu +p, the generated secondary fault judgment signal is a normal signal;

[0144] Judge whether the reading of the water tank liquid level gauge is less than or equal to the predicted liquid level value L simu -q;

[0145] If the reading of the water tank liquid level gauge is less than or equal to the predicted liquid level value L simu -q, the generated secondary fault judgment signal is a prompt signal;

[0146] If the reading of the water tank liquid level gauge is not less than or equal to the predicted liquid level value L simu -q, the generated secondary fault judgment signal is a normal signal.

[0147] Through the above precise control and fault warning mechanism, the present invention significantly improves the working safety of the PEM electrolytic water hydrogen production system. The improvement of safety not only reduces the maintenance cost and downtime, but also ensures the safety of operators, and has a positive impact on the long-term operation and economic benefits of the system.

[0148] As Figure 1As shown in the figure, the change in the water volume of the water tank 2 in the water replenishment system of the present invention is mainly affected by the water volume of the electrolyte solution, the water volume transferred across the membrane to the cathode, the water volume carried away by the gas, and the water replenishment volume of the two-stage steam-water separator. The electrolyzed water refers to the water volume consumed by the electrochemical reaction of PEM electrolyzed water driven by electric energy; the water transferred across the membrane to the cathode refers to the water volume transferred from the anode to the cathode due to the pressure difference; the water in the hydrogen gas at the cathode outlet is collected in the two-stage steam-water separator, and this part of the water is replenished back into the water tank 2. In addition, it is also affected by the temperature changes of the water tank 2 and the electrolytic cell 1. The temperature of the water tank 2 affects the water volume evaporated into the gas above the water tank 2, and the temperature of the electrolytic cell 1 affects the water volume required for each cycle of cooling water.

[0149] Through the electrolytic cell temperature control model and the readings of the temperature and pressure sensors, calculate the water flow rate consumed for electrolyzing water and the cooling circulating water flow rate. According to the opening and closing states of the drain valves (the first drain valve 6 and the second drain valve 7) of the two-stage steam-water separator, judge the water volume replenished from the two-stage water separator into the water tank 2, and then calculate the evaporation water volume according to the readings of the temperature and pressure sensors of the water tank 2 and the geometric parameters of the water tank 2 to correct the water flow rate consumed for each cycle. Thus, according to the water tank model, the liquid level value of the water inside the water tank 2 during water addition and drainage is calculated in real time.

[0150] When the predicted liquid level value is lower than the lower limit L of the water tank liquid level threshold l , open the opening valve supplied by the pure water machine and set the opening time t. When the predicted liquid level value is higher than the upper limit L of the water tank service threshold h , close the opening valve supplied by the pure water machine.

[0151] For fault diagnosis, simulate the operating conditions with the sensor accuracy to obtain a reasonable RMSE value denoted as m. Collect n measured data within a certain period of time and perform RMSE calculation. When the RMSE value exceeds the m value, judge the early systematic error fault type of the first-level fault. If the abnormal value stability time exceeds the terr value and the liquid level difference L d1 is less than the preset value o value, dynamically adjust the liquid level calculation model, and compensate the difference L d1 into the liquid level calculation formula to calibrate the liquid level calculation model in real time; further, when the feedback reading L of the liquid level gauge test and the calculated value L simu have a difference greater than p or qq, report the secondary fault of the liquid level gauge and water tank abnormal fault or system leakage fault, where o, p, and q are empirical values obtained from system debugging.

[0152] To understand the present invention more fully, the following supplementary description is provided: The heat management water replenishment system model is as follows:

[0153] The formula for the PEM hydrogen production chemical reaction:

[0154] 2H 2 O - 4e- →2H 2 +O 2

[0155] (1) The calculation of the water volume in the water tank consists of the water volume electrolyzed, the water volume transferred across the membrane to the cathode, the water volume carried away by the gas, the evaporation water volume, and the difference in the circulating water volume.

[0156] ΔN H2O＝ ΔN H2O,e +ΔN H2O,PEM +ΔN sep +ΔN vap,t +ΔN cl ;

[0157] Where: ΔN H2O,e is the water volume electrolyzed, ΔN H2O,PEM is the water volume transferred across the membrane to the cathode and carried away by the gas, ΔN sep is the evaporation water volume, ΔN vap,t is the circulating water volume, ΔN cl is to correct the water volume in the water tank according to the changing water tank temperature and electrolyzer temperature.

[0158] L simu =L simu0 +L d0 Specifically, the predicted liquid level value is the predicted liquid level value of the previous second plus the difference, where ΔQ H2O is the volume flow rate of the difference in the water volume in the water tank,

[0159] A is the bottom area of the water tank, N H2O is the amount of water in the electrolysis cathode flow channel per unit time, M H2O is the relative molecular mass of water.

[0160] Input the working current, and the electrolyzed water volume ΔN H2O,e can be calculated in real time according to Faraday's law. The calculation formula:

[0161]

[0162] ΔN H2O,PeM Input the working voltage, working current, and the volumes of the cathode and anode flow channels, and calculate the water volume carried away by the gas according to the saturated vapor pressure formula.

[0163] The change situation of the water in the cathode flow channel model, and their relationship can be expressed by the following dynamic equation:

[0164] The amount of hydrogen flow rate in the cathode is equal to the amount of hydrogen gas at the outlet minus the amount of hydrogen gas generated. The hydrogen gas and water in the cathode can be calculated as:

[0165]

[0166] The amount of water flow rate in the cathode is equal to the amount of water at the inlet minus the amount of water at the outlet, the amount of water dragged by electrons, and the amount of water diffused from the cathode to the anode. The water in the cathode can be calculated as:

[0167]

[0168] n d = 0.0029λ 2 + 0.05λ - 3.4×10 -19

[0169] n d is the electron drag constant;

[0170] N H2O is the amount of water in the cathode flow channel of the electrolytic cell per unit time, mol / s;

[0171] λ is the arithmetic square root of the water content of the anode and cathode membranes;

[0173] λ = 0.043 + 17.81α - 39.85α 2 + 36α 3 , 0 ≤ α ≤ 1

[0174] λ = 14 + 1.4(α - 1), 1 ≤ α ≤ 3

[0175] According to Fick's first diffusion law, the diffusion value of water through the membrane is:

[0176]

[0177] (2) Input the readings of the voltmeter and the coolant outlet temperature sensor, and calculate the difference in the cooling circulating water flow rate according to the electrolytic cell temperature model formula:

[0178] Q el = (U el - V th )In cell

[0179]

[0180] (3) Input the geometric parameters of the water tank, the readings of the temperature sensor, and the inlet and outlet water flow rates, and calculate the water tank liquid level value according to the water tank model, denoted as L simu .

[0181] Calculate the corrected liquid level value of the saturated water volume above the water tank through the measured value of the water tank temperature sensor. Due to the change in the amount of water vapor that can be accommodated in the steam separator, the change in the evaporation water volume brought to the water in the water tank is corrected in real time.

[0182] When Lh ≥L simu ≥L l When, the liquid level calculation formula is:

[0183]

[0184] When L simu <L l When the water addition valve is opened, the liquid level calculation formula is:

[0185]

[0186] L simu0 is the initial liquid level of the water tank, m;

[0187] L d1 is the liquid level difference compensated to the calculation model after the systematic error judgment of the first-level fault alarm is completed.

[0188] Among them, based on the water tank temperature, Δm vap The calculation process is as follows:

[0189] The evaporation water volume corrects the water volume change in the water tank according to the changing water tank temperature and electrolyzer temperature. The mvp calculation process is as follows:

[0190] The fitting equation of the saturated vapor pressure is shown in the formula:

[0191]

[0192] The calculation of the condensate difference is shown in the formula:

[0193]

[0194] Among them, the calculation of the gas volume above the water tank is shown in the formula:

[0195] V vap =V tank -L w, A tank

[0196] V tank is the water tank volume, m 3 ;

[0197] A tank is the bottom area of the water tank, m 2 ;

[0198] V vap is the gas volume above the liquid water in the water tank, m 2 .

[0199] (4) The two-stage steam-water separator at the electrolyzer outlet will collect the condensed liquid water. When the preset liquid level value is reached, the drain valve will be opened to supplement the liquid water into the water tank.

[0200] According to the corollary of Bernoulli's equation, the water outlet flow equation can be obtained as shown in formula (2).

[0201]

[0202] N sep is the mass flow rate of water at the water outlet of the steam-water separator, kg / s -1 ;

[0203] S out, is the cross-sectional area of the water outlet of the steam-water separator, m² 2 ;

[0204] L sep is the water level of the steam-water separator, m.

[0205] In summary, the present invention constructs a thermal management system model for PEM hydrogen production and a mathematical model for the water replenishment system. This model comprehensively analyzes the water consumption per cycle, and provides data support for subsequent control strategies by real-time monitoring and calculating the change in the stock of liquid water in the water tank.

[0206] Based on the model and the preset dual water level thresholds, the system can dynamically adjust the water replenishment strategy according to the current water level; the present invention can automatically calculate the start and stop times of the drain valve to ensure that the water tank water level is within a safe range, avoiding performance fluctuations and equipment risks.

[0207] By comparing the RMSE value of the measured water level with the reasonable RMSE value, and by comparing the measured and calculated water level values, system failures can be identified in advance, and the system can be shut down for maintenance in a timely manner to ensure the tightness and high reliability of the system.

[0208] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent improvements to the control method of a PEM electrolytic water hydrogen production water replenishment system, etc., made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A control method for a PEM water electrolysis hydrogen production and water replenishment system, characterized in that: The following steps are involved: S10, obtaining electrolytic cell operating parameters, water tank level gauge readings, and water tank temperature and pressure readings; S20, calculate the predicted liquid level value L of the water tank simu ; According to the reading of the water tank level gauge, the root mean square error RMSE of the reading of the water tank level gauge is obtained; Then calculate the liquid level difference L d , liquid level difference L d is the water tank level gauge reading and predicted level value L simu difference; S30, predict the liquid level value L simu Compare with the preset water replenishment level range, and generate a corresponding water replenishment control signal according to the comparison result; The root mean square error RMSE is compared with a preset value m, and a corresponding type of fault judgment signal is generated according to the comparison result; The liquid level difference L d Compare with the preset fault liquid level range, and generate corresponding second-class fault judgment signal according to the comparison result; S40, according to the water replenishment control signal, control the water purifier to close, open or open the water tank drain valve; According to a type of fault judgment signal, a systematic error fault prompt is issued or the predicted liquid level value is corrected; According to the second type of fault judgment signal, a water tank abnormality prompt, a water tank level gauge abnormality prompt, a shutdown inspection and / or normal operation are issued.

2. The control method of the PEM water electrolysis hydrogen production and water replenishment system according to claim 1, characterized in that: In S30, the liquid level value L is predicted. simu The step of comparing the water level with the preset water replenishment liquid level range and generating a corresponding water replenishment control signal according to the comparison result includes: Determine the predicted liquid level value L simu Whether it is within the preset water replenishment level range; If the predicted liquid level value L simu Within the preset water replenishment level range, the generated water replenishment control signal is a closing signal; If the predicted liquid level value L simu Less than the minimum liquid level L in the preset water replenishment level range l , the generated water replenishment control signal is an opening signal; If the predicted liquid level value L simu Greater than the maximum value L of the preset water replenishment level range h , the generated water replenishment control signal is a drainage signal; The step of controlling the water purifier to close, open or open the water tank drain valve according to the water replenishment control signal in S40 includes: According to the shutdown signal, the water purifier is turned off; According to the start signal, the pure water machine is turned on to replenish water, and the pure water machine is turned on for a time of t; According to the drainage signal, open the water tank drain valve to drain the water.

3. The control method of the PEM water electrolysis hydrogen production and water replenishment system according to claim 1, characterized in that: The root mean square error RMSE is a preset value, or the root mean square error RMSE is calculated using the following formula: Where n is the number of samples, L test is the water tank level gauge indication, L simu To predict the liquid level value.

4. The control method of the PEM water electrolysis hydrogen production and water replenishment system according to claim 3 is characterized in that: The step of comparing the root mean square error RMSE with a preset value m in S30 and generating a corresponding type of fault judgment signal according to the comparison result includes the following steps: S300, determining whether the root mean square error RMSE is less than or equal to a preset value m; S301, if the root mean square error RMSE is not less than or equal to a preset value m, a corresponding type of fault judgment signal is generated as a systematic error fault signal; S302, if the root mean square error RMSE is less than or equal to a preset value m, generating a corresponding type of fault judgment signal as a liquid level correction signal; The step of issuing a systematic error fault prompt or performing a predicted liquid level value correction step according to a type of fault judgment signal in S40 includes: According to the systematic error fault signal, a systematic error fault prompt is issued; According to the liquid level correction signal, the predicted liquid level value is corrected.

5. The control method of the PEM water electrolysis hydrogen production and water replenishment system according to claim 4 is characterized in that: The S301 includes: S3010: If the root mean square error RMSE is not less than or equal to the preset m, start the timing t err , a ; S3011, when t err , a Greater than the preset time t err When , the corresponding type of fault judgment signal generated is a systematic error fault signal; When t err , a Not longer than the preset time t err When , execute S300; The S302 includes: S3020, if the root mean square error RMSE is less than or equal to the preset value m, determine the liquid level compensation value L d1 Is it less than the preset value o, where the liquid level compensation value L d1 is the liquid level difference L d ; S3021, if the liquid level compensation value L d1 If the value is less than the preset value o, a corresponding type of fault judgment signal is generated, which is liquid level correction.

6. The control method of the PEM water electrolysis hydrogen production and water replenishment system according to claim 5, characterized in that: Predicted level value correction, including: When the predicted liquid level value L simu When the water level is within the preset range, Let L simu =L simu0 -L d0 -L d1 , where L simu0 is the initial liquid level value of the water tank, Where ΔQ H2O is the volume flow rate of the water volume difference in the water tank, Where A is the bottom area of ​​the water tank, N H2O is the amount of water in the electrolytic cathode flow channel per unit time, M H2O is the relative molecular mass of water; When the predicted liquid level value L simu Less than the minimum liquid level L in the preset water replenishment level range l hour, make Where L simu0 is the initial liquid level of the water tank, Q in A is the water flow rate entering the water tank after the water purifier is turned on; tank is the bottom area of ​​the water tank.

7. The control method of the PEM water electrolysis hydrogen production and water replenishment system according to claim 1, characterized in that: In S30, the liquid level difference L d The steps of comparing the liquid level with the preset fault liquid level range and generating the corresponding second-class fault judgment signal according to the comparison result include: Determine the liquid level difference L d Is it greater than the preset value p or q? If the liquid level difference L d If it is greater than the preset value p or q, the generated second-class fault judgment signal is a prompt signal; If the liquid level difference L d is not greater than the preset value p or q, the generated second-class fault judgment signal is a normal signal; In the step S40, according to the second type of fault judgment signal, the steps of normal operation, issuing a water tank abnormality prompt, issuing a water tank liquid level gauge abnormality prompt and / or stopping for inspection include: According to the prompt signal, the water tank abnormality prompt and the water tank liquid level gauge abnormality prompt are issued, and the machine is shut down for inspection; According to normal signal, normal operation is carried out.

8. The control method of the PEM water electrolysis hydrogen production and water replenishment system according to claim 7, characterized in that: The determination of the liquid level difference L d Is it greater than a preset value p or q steps, including: Determine whether the water tank level gauge reading is greater than or equal to the predicted level value L simu +p; If the water tank level gauge reading is greater than or equal to the predicted level value L simu +p, the generated second-class fault judgment signal is a prompt signal; If the water tank level gauge reading is not greater than or equal to the predicted liquid level value L simu +p, the generated second-class fault judgment signal is a normal signal; Determine whether the water tank level gauge reading is less than or equal to the predicted level value L simu -q; If the water tank level gauge reading is less than or equal to the predicted level value L simu -q, the generated second-class fault judgment signal is a prompt signal; If the water tank level gauge reading is not less than or equal to the predicted liquid level value L simu -q: The generated second-class fault judgment signal is a normal signal.

9. The control method of the PEM water electrolysis hydrogen production and water replenishment system according to claim 1, characterized in that: Water tank water volume difference ΔN H2O Calculated using a preset thermal management system water replenishment system model, the thermal management system water replenishment system model includes: ΔN H2O＝ ΔN H2O,e +ΔN H2O,PEM +ΔN sep +ΔN vap,t +ΔN cl ; Where: ΔN H2O,e is the amount of water electrolyzed, ΔN H2O,PEM is the amount of water transferred across the membrane to the cathode and carried away by the gas, ΔN sep is the amount of evaporated water, ΔN vap,t is the circulating water volume, ΔN cl To correct the amount of water in the tank according to the changing tank temperature and electrolyzer temperature.

10. The control method of the PEM water electrolysis hydrogen production and water replenishment system according to any one of claims 1 to 9, characterized in that: Applicable to the PEM electrolysis water hydrogen production water replenishment system, the water replenishment system includes a water tank, an electrolyzer, a primary steam-water separator and a secondary steam-water separator; The anode outlet of the electrolytic cell is provided with a first temperature sensor, and the cathode outlet of the electrolytic cell is provided with a first pressure sensor; The first-stage steam-water separator is connected to the cathode outlet of the electrolytic cell, the outlet of the first-stage steam-water separator is connected to the first drain valve, and the first-stage steam-water separator is provided with a first liquid level gauge; The secondary steam-water separator is connected to the primary steam-water separator, the outlet of the secondary steam-water separator is connected to the second drain valve, and the secondary steam-water separator is provided with a second liquid level gauge; The first water inlet of the water tank is connected to the water purifier, the second water inlet is connected to the anode outlet of the electrolytic cell, and the third water inlet is connected to the first drain valve and the second drain valve respectively; the first water outlet of the water tank is connected to the anode inlet of the electrolytic cell, and the second water outlet is connected to the third drain valve; the water tank is respectively provided with a second temperature sensor, a second pressure sensor and a water tank liquid level gauge.

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