WO2023035726A1 - Hydrogen leakage detection method and system for hydrogen fuel cell system and rail transit vehicle - Google Patents

Abstract

Disclosed in the present invention are a hydrogen leakage detection method and system for a hydrogen fuel cell system and a rail transit vehicle. The method comprises: acquiring the temperature and pressure in a high-pressure hydrogen storage tank at a vehicle stopping moment, and calculating the mass of hydrogen in the high-pressure hydrogen storage tank at the stopping moment according to the temperature and pressure in the high-pressure hydrogen storage tank at the vehicle stopping moment; when the vehicle is restarted, acquiring the temperature and pressure in the high-pressure hydrogen storage tank at a starting moment, and calculating the mass of hydrogen in the high-pressure hydrogen storage tank at the starting moment according to the temperature and pressure in the high-pressure hydrogen storage tank at the starting moment; calculating a leakage parameter during vehicle parking according to the mass of hydrogen in the high-pressure hydrogen storage tank at the vehicle stopping moment and the mass of hydrogen in the high-pressure hydrogen storage tank at the vehicle starting moment; if the leakage parameter during vehicle parking is less than or equal to a safety threshold when the vehicle is parked, determining that there is no hydrogen leakage during vehicle parking; otherwise determining that there is hydrogen leakage during vehicle parking. According to the present invention, the problem of hydrogen leakage during vehicle parking is effectively monitored.

Description

Hydrogen leak detection method and system for hydrogen fuel cell system, rail transit vehicle technical field

The invention belongs to the technical field of hydrogen fuel cell systems for rail transit vehicles, and in particular relates to a method and system for detecting hydrogen leakage in a hydrogen fuel cell system and a rail transit vehicle.

Background technique

A hydrogen fuel cell system usually includes a high-pressure hydrogen storage tank, a hydrogen supply pipeline, a hydrogen fuel cell module, and a cooling device. The high-pressure hydrogen storage tank supplies hydrogen to the hydrogen fuel cell module through the hydrogen supply pipeline, and a valve is set on the hydrogen supply pipeline. Control the opening and closing of the valve to control the gas flow from the high-pressure hydrogen storage tank to the hydrogen fuel cell module (hydrogen fuel cell stack), and use the electrochemical reaction between hydrogen and oxygen to generate electricity in the hydrogen fuel cell module. As an energy conversion device, the hydrogen fuel cell system has the advantages of zero pollution, high efficiency, and low noise, and is highly in line with the requirements of future rail transit vehicles for traction power supply systems. At present, the key technical indicators of the hydrogen fuel cell system include energy density, power density, efficiency, volume and service life, etc., which have met the demand for traction power supply of rail transit vehicles. Products such as hydrogen fuel cell locomotives, engineering vehicles, EMUs and trams have been successfully developed and put into commercial operation.

Hydrogen fuel cell systems use hydrogen gas (H ₂ ) as fuel. Hydrogen is a flammable and explosive dangerous gas. The explosion concentration limit in air is 4% to 75% (volume fraction), the spontaneous ignition point is 500°C, the minimum ignition energy is 0.019mJ, and the flame temperature is 2045°C. Once leaked, it is easy to cause a fire and explosions, posing a serious threat to the lives of drivers and passengers. Therefore, hydrogen leak detection is one of the essential safety functions for hydrogen fuel cell systems.

At present, hydrogen leakage detection of hydrogen fuel cell systems is mainly realized by hydrogen concentration sensors. When a hydrogen leak occurs, the leaked _H2 molecules react with the sensitive element of the hydrogen concentration sensor to generate an electrical signal and send it to the controller; the controller analyzes the hydrogen concentration according to the electrical signal, and sends a closing command to the shut-off valve to shut off the hydrogen circuit to stop hydrogen from leaking further. According to the reaction principle of _H2 molecules and sensitive elements, hydrogen concentration sensors can be divided into semiconductor type, pyroelectric type and electrochemical type and other types.

To detect hydrogen leakage with a hydrogen concentration sensor, the sensor needs to be installed at a location prone to leakage of the hydrogen fuel cell system (such as the mouth of a high-pressure hydrogen storage tank) and a location prone to hydrogen accumulation (such as multiple hydrogen concentration sensors arranged on the top of the device), This method has the following disadvantages:

(1) During the parking period of the vehicle, the power supply to the hydrogen concentration sensor and its controller is interrupted. The existing technology cannot effectively monitor the hydrogen leakage problem during the parking period of the vehicle. As a result, after the vehicle is parked and restarted, it cannot be started/stopped according to the hydrogen leakage situation Hydrogen fuel cells, when the hydrogen leaks, the hydrogen fuel cell system is forced to work all the time, which leads to serious safety hazards in train operation and greatly shortens the service life of the hydrogen fuel cell system;

(2) It can only detect hydrogen leakage near the installation position of the hydrogen concentration sensor, and the coverage is limited;

(3) The stability and sensitivity of the hydrogen concentration sensor are poor, the output signal is weak, and the service life is short;

(4) Multiple hydrogen concentration sensors need to be installed, the system structure is complex and the cost is high.

Contents of the invention

The purpose of the present invention is to provide a hydrogen fuel cell system hydrogen leakage detection method and system, and a rail transit vehicle to solve the problems of complex structure, high cost, limited coverage, short service life, and inability to use a hydrogen concentration sensor for leakage detection. Monitor for hydrogen leaks while vehicles are parked.

The present invention solves the above-mentioned technical problems through the following technical solutions: a hydrogen fuel cell system hydrogen leakage detection method, the hydrogen fuel cell system includes a high-pressure hydrogen storage tank, and the high-pressure hydrogen storage tank is connected to the hydrogen fuel cell electric The heap is connected; the method includes the following steps:

S1. Acquire the temperature and air pressure in the high-pressure hydrogen storage tank at the time t ₀₀ when the vehicle stops, and calculate the hydrogen mass _{m 00 in} the high-pressure hydrogen storage tank when the vehicle stops according to the temperature and air pressure in the high-pressure hydrogen storage tank at the time t 00 when the vehicle stops;

S2. When the vehicle is started again, obtain the temperature and air pressure in the high-pressure hydrogen storage tank at the starting time _t0 , and calculate the hydrogen mass in the high-pressure hydrogen storage tank at the starting time _t0 according to the temperature and air pressure in the high-pressure hydrogen storage tank at the starting time _t0 m ₀ ;

S3. According to the hydrogen mass m ₀₀ in the high-pressure hydrogen storage tank at the vehicle stop time t ₀₀ and the hydrogen gas mass m ₀ in the high-pressure hydrogen storage tank at the vehicle start time t ₀ , calculate the leakage parameter L ₀ during the parking period of the vehicle; If the leakage parameter _L0 is less than or equal to the safety threshold when the vehicle is parked, then there is no hydrogen leakage during the vehicle parking period, and the hydrogen fuel cell system is started; otherwise, there is hydrogen gas leakage during the vehicle parking period.

The present invention calculates the leakage parameters during the parking period of the vehicle by calculating the hydrogen gas quality in the high-pressure hydrogen storage tank when the vehicle is stopped and the hydrogen gas quality in the high-pressure hydrogen storage tank when the vehicle is restarted, and can quickly detect whether there is hydrogen leakage after the vehicle is restarted. The hydrogen leakage problem during the parking period of the vehicle has been effectively monitored. If there is a hydrogen leakage, the start of the hydrogen fuel cell can be stopped in time to prevent the hydrogen fuel cell system from being forced to work all the time when the hydrogen gas leaks, prolonging the service life of the hydrogen fuel cell system , to ensure the safety of train operation.

In the present invention, after starting the hydrogen fuel cell system, the following steps are also included:

Step 1: When the vehicle is running, set each detection cycle as Δt, take the running time t as the end time of the current detection cycle, and the running time t-Δt as the starting time of the current detection cycle, and obtain the starting time t-Δt for high-pressure hydrogen storage The temperature and air pressure in the tank, and calculate the mass mt-Δt of hydrogen in the high-pressure hydrogen storage tank at the starting time t-Δt according to the temperature and air pressure in the high-pressure hydrogen storage tank at the starting time _t-Δt ;

Obtain the temperature and air pressure in the high-pressure hydrogen storage tank at the end point t, and calculate the mass _mt of hydrogen in the high-pressure hydrogen storage tank at the end point t according to the temperature and air pressure in the high-pressure hydrogen storage tank at the end point t;

Continuously collect the output current i of the hydrogen fuel cell system according to the sampling period of the current sensor;

Step 2: According to the mass mt-Δt of hydrogen in the high-pressure hydrogen storage tank at the starting time _t-Δt and the mass mt of hydrogen in the high-pressure hydrogen storage tank at the end time _t, calculate the mass m of hydrogen output from the high-pressure hydrogen storage tank within the current detection period Δt _sup ;

Calculate the output charge Q of the hydrogen fuel cell stack in the current detection period Δt according to the waveform of the output current i of the hydrogen fuel cell system in the current detection period Δt; calculate the current detection according to the output charge Q of the hydrogen fuel cell stack in the current detection period Δt The hydrogen mass m _con consumed by the hydrogen fuel cell system for power generation within the period Δt;

Step 3: According to the hydrogen mass m _sup output by the high-pressure hydrogen storage tank in the current detection cycle Δt, the hydrogen gas mass m _con consumed by the hydrogen fuel cell system for power generation, and the hydrogen gas mass m actively discharged by the hydrogen fuel cell system in the current detection cycle Δt _ex , calculate the leakage parameter L of the hydrogen fuel cell system within the current detection period Δt;

Step 4: Judging whether the leakage parameter L is less than or equal to the hydrogen leakage safety threshold when the vehicle is running, if so, there is no hydrogen leakage in the current detection cycle Δt, otherwise there is hydrogen leakage in the current detection cycle Δt;

Step 5: Repeat steps 1 to 4 to detect hydrogen leakage in the next detection cycle until the vehicle stops running.

The method of the present invention can effectively detect the hydrogen leakage problem that occurs during the operation of the hydrogen fuel cell system in real time during the operation of the vehicle, and does not need to configure a plurality of special hydrogen concentration sensors at the positions prone to leakage and hydrogen accumulation, and the system The structure is simple and the hardware cost is reduced; the hydrogen leakage detection is not limited by the location of the sensor, and the hydrogen leakage phenomenon at any position can be detected, and the coverage is wide; compared with the hydrogen concentration sensor, the temperature sensor and the air pressure sensor have high sensitivity , stable performance, and long service life, which prolong the service life of the hydrogen fuel cell system and improve the reliability of the hydrogen fuel cell system.

Further, according to the temperature and air pressure in the high-pressure hydrogen storage tank at a certain moment, the specific calculation formula for calculating the mass of hydrogen in the high-pressure hydrogen storage tank at that moment is:

Among them, m is the mass of hydrogen in the high-pressure hydrogen storage tank at this moment, μ is the molar mass of hydrogen, R is the molar gas constant, T is the temperature of hydrogen in the high-pressure hydrogen storage tank at the corresponding moment, and p is the temperature in the high-pressure hydrogen storage tank at the corresponding moment The air pressure (pressure) of hydrogen, and V is the volume of the high-pressure hydrogen storage tank.

Further, the specific calculation formula of the hydrogen mass m _sup output by the high-pressure hydrogen storage tank within the current detection period Δt is:

m _sup =m _{t -Δt} -m _t .

Further, the specific calculation formula for the charge Q output by the hydrogen fuel cell stack within the current detection period Δt is:

Where i is the output current of the hydrogen fuel cell system collected by the current sensor.

Further, the specific calculation formula of the hydrogen mass m _con consumed by the hydrogen fuel cell system for power generation within the current detection period Δt is:

Among them, μ is the molar mass of hydrogen, Q _e is the charge carried by a single electron, and N _A is Avogadro's constant.

Further, in the step 6, the specific calculation formula of the actively discharged hydrogen mass m _ex is:

m _ex = n × m _ex0 ;

Among them, n is the number of openings of the discharge valve when hydrogen is actively discharged within the detection period Δt, and m _ex0 is the mass of hydrogen that is actively discharged when the discharge valve is opened once.

Preferably, the method of obtaining the mass m _ex0 of hydrogen actively discharged when the discharge valve is opened once is:

After the assembly of the hydrogen fuel cell system is completed and before loading into the vehicle, the hydrogen fuel cell system is operated according to the design conditions through tests, all the gases discharged when the discharge valve is opened once are collected, hydrogen is separated from all gases, and the test The mass of hydrogen separated is the mass m _ex0 of hydrogen actively discharged when the discharge valve is opened once.

Further, the leakage parameter is a leakage rate or a leakage quality, and the calculation formula of the leakage rate _R2 is:

Where _R2 is the hydrogen leakage rate of the hydrogen fuel cell system within the current detection period Δt, that is, the hydrogen leakage mass per unit time.

In the present invention, when it is determined that there is a hydrogen leak, an alarm is issued, which facilitates the operator to take corresponding protection actions according to the alarm information.

The present invention also provides another method for detecting hydrogen leakage in a hydrogen fuel cell system. The hydrogen fuel cell system includes a high-pressure hydrogen storage tank, and the high-pressure hydrogen storage tank communicates with a hydrogen fuel cell stack through a pipeline; including the following steps:

Step 1. When the vehicle is running, set each detection cycle as Δt, take the running time t as the end time of the current detection cycle, and the running time t-Δt as the starting time of the current detection cycle, and obtain the starting time t-Δt for high-pressure hydrogen storage The temperature and air pressure in the tank, and calculate the mass mt-Δt of hydrogen in the high-pressure hydrogen storage tank at the starting time t-Δt according to the temperature and air pressure in the high-pressure hydrogen storage tank at the starting time _t-Δt ;

Obtain the temperature and air pressure in the high-pressure hydrogen storage tank at the end point t, and calculate the mass _mt of hydrogen in the high-pressure hydrogen storage tank at the end point t according to the temperature and air pressure in the high-pressure hydrogen storage tank at the end point t;

Continuously collect the output current i of the hydrogen fuel cell system;

Step 2: Calculate the mass m of hydrogen output from the high-pressure hydrogen storage tank within the current detection period Δt according to the mass mt-Δt of hydrogen in the high-pressure hydrogen storage tank at the starting time _t-Δt and the mass mt of hydrogen in the high-pressure hydrogen storage tank at the end time _{t sup} ;

Calculate the output charge Q of the hydrogen fuel cell stack in the current detection period Δt according to the waveform of the output current i of the hydrogen fuel cell system in the current detection period Δt; calculate the current detection according to the output charge Q of the hydrogen fuel cell stack in the current detection period Δt The hydrogen mass m _con consumed by the hydrogen fuel cell system for power generation within the period Δt;

Step 3, according to the hydrogen mass m _sup output by the high-pressure hydrogen storage tank in the current detection cycle Δt, the hydrogen gas mass m _con consumed by the hydrogen fuel cell system for power generation, and the hydrogen gas mass m actively discharged by the hydrogen fuel cell system in the current detection cycle Δt _ex , calculate the leakage parameter L of the hydrogen fuel cell system within the current detection period Δt;

Step 4, judging whether the leakage parameter L is less than or equal to the safety threshold of hydrogen leakage when the vehicle is running, if so, there is no hydrogen leakage in the current detection period Δt, otherwise there is hydrogen leakage in the current detection period Δt;

Step 5: Repeat steps 1-4 to detect hydrogen leakage in the next detection cycle until the vehicle stops running.

The present invention can effectively detect the hydrogen leakage problem that occurs during the operation of the hydrogen fuel cell system in real time during the operation of the vehicle, and does not need to configure a plurality of special hydrogen concentration sensors at the positions prone to leakage and hydrogen accumulation, and the system structure is simple. Reduce hardware costs; hydrogen leak detection is not limited by the location of the sensor, and can detect hydrogen leaks at any location with a wide coverage; compared with hydrogen concentration sensors, temperature sensors and pressure sensors have high sensitivity and stable performance , The characteristics of long service life prolong the service life of the hydrogen fuel cell system and improve the reliability of the hydrogen fuel cell system.

The method of the present invention also includes the step of hydrogen leakage detection during vehicle parking, and the specific implementation process includes:

Obtain the temperature and air pressure in the high-pressure hydrogen storage tank at the time t ₀₀ when the vehicle stops, and calculate the hydrogen mass m ₀₀ in the high-pressure hydrogen storage tank when the vehicle stops according to the temperature and air pressure in the high-pressure hydrogen storage tank at the time t ₀₀ when the vehicle stops;

Calculate the leakage parameter L ₀ during the parking period of the vehicle according _to the hydrogen mass m ₀₀ in the high-pressure hydrogen storage tank and the vehicle startup time t ₀ ; the leakage parameter L ₀ during the parking period is less than or equal to the safety threshold when parking , then there is no hydrogen leakage during the parking period of the vehicle, start the hydrogen fuel cell system, and go to step 2, otherwise there is hydrogen leakage during the parking period of the vehicle.

After the vehicle starts up again, the present invention can quickly detect whether there is hydrogen leakage, and effectively monitor the hydrogen leakage problem during the parking period of the vehicle. If there is hydrogen leakage, the startup of the hydrogen fuel cell can be stopped in time to prevent the hydrogen fuel cell from leaking hydrogen. The system is forced to work all the time, prolonging the service life of the hydrogen fuel cell system and ensuring the safety of train operation.

The present invention also provides a hydrogen fuel cell system hydrogen leakage detection system, which includes a memory and a processor; the memory stores computer programs/instructions; the processor executes the computer programs/instructions stored in the memory; the computer The programs/instructions are configured to implement the steps of the above methods of the present invention.

The present invention also provides a rail transit vehicle, including the hydrogen fuel cell system hydrogen leakage detection system as described above.

Beneficial effect

Compared with the prior art, the present invention has the advantages of:

1. The present invention effectively monitors the hydrogen leakage problem during the parking period of the vehicle, which can prevent the hydrogen fuel cell system from being forced to work all the time when the hydrogen gas leaks, prolongs the service life of the hydrogen fuel cell system, and ensures the safety of train operation;

2. During the operation of the vehicle, it is possible to detect the hydrogen leakage problem that occurs in the hydrogen fuel cell system in real time and effectively. There is no need to configure multiple special hydrogen concentration sensors at the places where leakage and hydrogen are easy to accumulate. The system structure is simple. Reduced hardware costs.

3. It is not limited by the location of the sensor when performing hydrogen leakage detection, and can detect hydrogen leakage at any position, covering a wide range; compared with hydrogen concentration sensors, temperature sensors and air pressure sensors have high sensitivity, stable performance, and easy to use The characteristics of long life extend the service life and reliability of the system.

Description of drawings

In order to illustrate the technical solution of the present invention more clearly, the accompanying drawings that need to be used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only an embodiment of the present invention. Ordinary technicians can also obtain other drawings based on these drawings without paying creative work.

Fig. 1 is a flow chart of a hydrogen leak detection method for a hydrogen fuel cell system in an embodiment of the present invention;

2 is a schematic structural diagram of a hydrogen leak detection system for a hydrogen fuel cell system in an embodiment of the present invention;

3 is a schematic diagram of a sampling period and a detection period in an embodiment of the present invention;

Fig. 4 is a layout diagram of the hydrogen leakage detection system of the hydrogen fuel cell system in the embodiment of the present invention.

Among them, 1-high pressure hydrogen storage tank, 2-hydrogen supply pipeline, 3-hydrogen fuel cell stack, 4-current sensor, 5-signal line, 6-controller, 7-alarm module, 8-DC/DC regulator Pressurizer, 9-vehicle, 10-speaker, 11-temperature sensor, 12-pressure sensor, 13-warning light.

Detailed ways

The technical solutions in the present invention are clearly and completely described below in combination with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

The technical solution of the present application will be described in detail below with specific embodiments. The following specific embodiments may be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments.

As shown in Figure 1, a hydrogen fuel cell system hydrogen leakage detection method provided by an embodiment of the present invention includes the following steps:

S1. Acquire the temperature and air pressure in the high-pressure hydrogen storage tank at the time t ₀₀ when the vehicle stops, and calculate the hydrogen mass _{m 00 in} the high-pressure hydrogen storage tank when the vehicle stops according to the temperature and air pressure in the high-pressure hydrogen storage tank at the time t 00 when the vehicle stops;

As shown in Figure 2, a temperature sensor 11 and a pressure sensor 12 are integrated in the bottle mouth valve of the high-pressure hydrogen storage tank 1, and the temperature and pressure of hydrogen in the high-pressure hydrogen storage tank 1 can be collected through the temperature sensor 11 and the pressure sensor 12. When the vehicle stops, the temperature sensor 11, the pressure sensor 12 and the controller 6 collect the temperature and air pressure of the hydrogen in the high-pressure hydrogen storage tank 1 at the vehicle stop time _t00 , and calculate the hydrogen mass m in the high-pressure hydrogen storage tank 1 at the vehicle stop time _{t00 00} , the hydrogen mass m ₀₀ is stored in the controller 6, and the hydrogen mass m ₀₀ stored in the controller 6 is used for judging whether there is hydrogen leakage during the vehicle parking period when the vehicle is started next time.

In this embodiment, the hydrogen mass is calculated according to the ideal gas state equation, specifically:

Among them, m ₀₀ is the mass of hydrogen in the high-pressure hydrogen storage tank at the time t ₀₀ when the vehicle stops, μ is the molar mass of hydrogen, R is the molar gas constant, T ₀₀ is the temperature of hydrogen in the high-pressure hydrogen storage tank at the time t ₀₀ when the vehicle stops, and p ₀₀ is the pressure of hydrogen in the high-pressure hydrogen storage tank at the time of vehicle stop _t00 , and V is the volume of the high-pressure hydrogen storage tank.

Multiple high-pressure hydrogen storage tanks can be configured according to the hydrogen storage requirements of the vehicle, and the rated pressure of each high-pressure hydrogen storage tank is usually 35Mpa. When the hydrogen fuel cell system includes multiple high-pressure hydrogen storage tanks, the mass of hydrogen in the high-pressure hydrogen storage tanks at different moments is equal to the sum of the mass of hydrogen in all high-pressure hydrogen storage tanks at that moment. For example, Figure 2 shows that the device includes three high-pressure hydrogen storage tanks tank 1, the hydrogen mass in the high-pressure hydrogen storage tank at the vehicle stop time t ₀₀ is equal to the sum of the hydrogen mass in the three high-pressure hydrogen storage tanks at the vehicle stop time t ₀₀ .

S2. When the vehicle is started again, obtain the temperature and air pressure in the high-pressure hydrogen storage tank at the starting time _t0 , and calculate the hydrogen mass in the high-pressure hydrogen storage tank at the starting time _t0 according to the temperature and air pressure in the high-pressure hydrogen storage tank at the starting time _t0 m ₀ ;

When _the vehicle starts again after stopping at the last time _t00 , the temperature and pressure in the high-pressure hydrogen storage tank are collected by the temperature sensor and the pressure sensor at the starting time t0, and the mass of hydrogen in the high-pressure hydrogen storage tank at the starting time _t0 of the vehicle is m The specific calculation formula of ₀ is:

Among them, m ₀ is the mass of hydrogen in the high-pressure hydrogen storage tank at the vehicle startup time t ₀ , T ₀ is the hydrogen temperature in the high-pressure hydrogen storage tank at the vehicle startup time t ₀ , and p ₀ is the hydrogen temperature in the high-pressure hydrogen storage tank at the vehicle startup time t ₀ Air pressure (the air pressure of the hydrogen in the high-pressure hydrogen storage tank, that is, the air pressure in the high-pressure hydrogen storage pipe).

S3. According to the hydrogen mass m ₀₀ in the high-pressure hydrogen storage tank at the vehicle stop time t ₀₀ and the hydrogen gas mass m ₀ in the high-pressure hydrogen storage tank at the vehicle start time t ₀ , calculate the leakage parameter L ₀ during the parking period of the vehicle; If the leakage parameter _L0 is less than or equal to the safety threshold when the vehicle is parked, then there is no hydrogen leakage during the vehicle parking period, and the hydrogen fuel cell system is started; otherwise, there is hydrogen gas leakage during the vehicle parking period.

In this embodiment, the leakage parameter L ₀ is the leakage rate or leakage quality. During the parking period of the vehicle, the various valves on the hydrogen supply pipeline are closed, and the hydrogen in the high-pressure hydrogen storage tank cannot be discharged, and the difference between the hydrogen quality in the high-pressure hydrogen storage tank at the time t ₀₀ of the last vehicle stop and the restart time t ₀ Determine whether there is a hydrogen leak.

The difference between the hydrogen mass in the high-pressure hydrogen storage tank at the last vehicle stop time t ₀₀ and the restart time t ₀ is:

Δm ₀₀ =m ₀₀ -m ₀ (3)

Among them, Δm ₀₀ is the difference between the hydrogen mass in the high-pressure hydrogen storage tank at the last vehicle stop time t ₀₀ and the restart time t ₀ , and Δm ₀₀ is the leakage mass in the corresponding time period.

The leakage rate is expressed by the hydrogen leakage mass per unit time, then the leakage rate is:

Among them, R ₀ is the hydrogen leakage rate during the parking period of the vehicle. Both the leak rate and the leak quality can be used to judge whether there is a leak.

The hydrogen leakage safety threshold R _th0 when the vehicle is parked is related to the number, volume, and rated hydrogen storage pressure of the high-pressure hydrogen storage tanks of the on-board hydrogen fuel cell system, and is usually defined by the manufacturer. In this embodiment, the safety threshold R _th0 when the vehicle is parked is 8.9×10 ⁻⁵ g/h.

In this embodiment, the leakage rate is used to judge whether there is a leakage phenomenon. When the leakage rate R ₀ is less than or equal to the safety threshold R _th0 when the vehicle is parked, it indicates that there is no hydrogen leakage problem during the parking period of the vehicle, the hydrogen fuel cell system is started, and the vehicle is in running condition; when the leakage rate R ₀ is greater than the safety threshold R th0 when the vehicle is parked When _th0 , it indicates that there is a hydrogen leakage problem during the parking period of the vehicle, and the alarm module electrically connected to the controller sends out an alarm to remind the driver and passengers to take emergency measures for hydrogen leakage, which can effectively detect the hydrogen leakage during the parking period of the vehicle.

In the embodiment of the present invention, it is also possible to use the leakage mass Δm ₀₀ to judge whether there is a leakage phenomenon. When the leakage mass Δm ₀₀ is less than or equal to the safety threshold Δm _th0 when parking, it indicates that there is no hydrogen leakage problem during the parking period of the vehicle, and the hydrogen fuel is started. The battery system, the vehicle is in running condition; when the leakage mass Δm ₀₀ is greater than the safety threshold Δm _th0 during parking, it indicates that there is a hydrogen leakage problem during the parking period of the vehicle, and the alarm module electrically connected to the controller sends out an alarm.

The leakage quality is used as an index to evaluate hydrogen leakage, ignoring the influence of time, and it is suitable for rail transit vehicles with relatively fixed parking time and running time. The leakage rate or leakage quality can be selected according to the actual situation to evaluate the hydrogen leakage.

In another embodiment of the present invention, after starting the hydrogen fuel cell system, hydrogen leakage detection is continued, specifically including:

Step 1: When the vehicle is running, set each detection cycle as Δt, take the running time t as the end time of the current detection cycle, and the running time t-Δt as the starting time of the current detection cycle; obtain the starting time t-Δt for high-pressure hydrogen storage The temperature and air pressure in the tank, and according to the temperature and air pressure in the high-pressure hydrogen storage tank at the starting time t-Δt, calculate the mass m _{t-Δt of hydrogen in the high-pressure hydrogen storage tank at the starting time t-Δt} ; obtain the high-pressure hydrogen storage tank at the end time t The temperature and pressure in the tank, and according to the temperature and pressure in the high-pressure hydrogen storage tank at the end time t, the mass m _t of hydrogen in the high-pressure hydrogen storage tank at the end time t is calculated. The calculation formula is similar to formula (2).

Step 2: When the vehicle is running, continuously collect the output current i of the hydrogen fuel cell system according to the sampling period of the current sensor.

As shown in FIG. 3 , a current sensor 4 is installed at the output end of the hydrogen fuel cell stack 3 , and the output current i of the hydrogen fuel cell system is continuously collected according to the sampling period of the current sensor 4 .

According to the waveform of the output current i of the hydrogen fuel cell system within the current detection period Δt of the system, the charge Q output by the hydrogen fuel cell stack within the current detection period Δt is calculated, and the specific calculation formula is:

Calculating the output charge of the hydrogen fuel cell stack according to the output current is only one way to obtain the output charge, and other existing methods can also be used to obtain the output charge.

In the embodiment of the present invention, the sampling period t _int of the current sensor and the current detection period Δt of the system are respectively set according to the response characteristics of the current sensor and the dynamic characteristics of the hydrogen fuel cell system, as shown in FIG. 3 . Specifically, the sampling period t _int of the current sensor is set to 20 μs, and the current detection period Δt of the system is set to 30 s.

Step 3: Based on the principle of charge conservation, calculate the hydrogen mass m _con consumed by the hydrogen fuel cell system for power generation within the current detection cycle Δt according to the charge Q output by the hydrogen fuel cell stack within the current detection cycle Δt. The specific calculation formula is:

Among them, μ is the molar mass of hydrogen, Q _e is the charge carried by a single electron, and N _A is Avogadro's constant.

Step 4: When the vehicle is running, according to the temperature and air pressure in the high-pressure hydrogen storage tank at the starting time t-Δt and the ending time t of the current detection cycle, based on the method provided by formula (2), calculate the starting time t-Δt high-pressure storage tank The mass of hydrogen in the hydrogen tank m _{t - Δt} and the mass of hydrogen in the high-pressure hydrogen storage tank at the terminal time t m _t , the specific calculation formula is:

Among them, m _i is the hydrogen mass in the high-pressure hydrogen storage tank at the vehicle running time t _i , T _i is the hydrogen temperature in the high-pressure hydrogen storage tank at the vehicle running time t _i , p _i is the hydrogen temperature in the high-pressure hydrogen storage tank at the vehicle running time t _i air pressure.

And calculate the hydrogen mass m _sup output by the high-pressure hydrogen storage tank within the current detection period Δt, the specific calculation formula is:

m _sup =m _{t -Δt} -m _t (8)

Step 5: According to the consumed hydrogen mass m _con , the output hydrogen mass m _sup , and the hydrogen mass m _ex actively discharged by the hydrogen fuel cell system within the current detection period Δt of the system, calculate the leakage parameter L of the system within the current detection period Δt .

During the operation of the hydrogen fuel cell system, components such as _N2 in the air circuit will pass through the membrane electrode and permeate into the hydrogen circuit in a small amount, becoming impurities in the hydrogen circuit. In order to improve the utilization rate of hydrogen, hydrogen will be circulated in the hydrogen loop, resulting in the continuous enrichment of impurities such as _N2 which cannot be discharged in time. In order to reduce the content of impurities such as _N2 , the hydrogen circuit is equipped with a tail valve (i.e. discharge valve), which is opened periodically or irregularly in a pulsed manner to discharge impurities such as _N2 in the hydrogen circuit and reduce the concentration of impurities. When the exhaust valve is opened, a small amount of hydrogen will be discharged at the same time. This part of hydrogen is actively discharged by the hydrogen fuel cell system, not leaked. When calculating the mass of hydrogen leaked from the hydrogen fuel cell system when the vehicle is running, the mass of hydrogen that is actively discharged must be subtracted.

Since the tail valve is opened in a pulsed manner, the mass m _ex of the hydrogen gas actively discharged by the hydrogen fuel cell system when the vehicle is running is calculated according to the number of times the tail valve is opened. The specific formula is:

m _ex =n×m _ex0 (9)

Among them, n is the number of times the discharge valve is opened during the active discharge of hydrogen in the current detection period Δt, and m _ex0 is the mass of hydrogen that is actively discharged when the discharge valve is opened once. The hydrogen mass m _ex0 actively discharged when the exhaust valve is opened once is a characteristic parameter of the hydrogen fuel cell system, which can be obtained through test calibration, specifically:

After the hydrogen fuel cell system is assembled and before loading, the hydrogen fuel cell system is operated according to the design conditions through the test, a pulse opening signal is sent to the exhaust valve, the exhaust valve is opened, and when the exhaust valve is opened once All gases discharged, hydrogen is separated from all gases, the quality of hydrogen separated by testing is the mass of hydrogen actively discharged when the tail valve is opened for a single time, and the mass of hydrogen actively discharged when the tail valve is opened for a single time m _ex0 is stored into the controller.

The formula for calculating the hydrogen leakage rate _R2 of the hydrogen fuel cell system within the current detection period Δt of the system is:

The leakage mass Δm ₂ is: Δm ₂ =m _sup -m _con -m _ex .

Step 6: Determine whether the leakage parameter L is less than or equal to the safety threshold during operation. If yes, there is no hydrogen leakage in the current detection period Δt of the system, otherwise there is hydrogen leakage in the current detection period Δt of the system.

In the embodiment of the present invention, the leakage rate is used to judge whether there is a leakage phenomenon. When the leakage rate R ₂ is less than or equal to the safety threshold R _th2 during operation, it indicates that there is no hydrogen leakage problem within the current detection period Δt of the system; when the leakage rate R ₂ is greater than the safety threshold R _th2 during operation, it indicates that the current detection period of the system is There is a hydrogen leakage problem in Δt, and the alarm module electrically connected to the controller sends out an alarm to prompt the passengers to take emergency measures for hydrogen leakage, such as sounding an alarm or automatically taking protective measures such as closing the shut-off valve on the hydrogen supply pipeline according to the amount of hydrogen leakage.

The hydrogen leakage safety threshold R _th2 when the vehicle is running is related to the number of joints and valves in the hydrogen circulation circuit of the hydrogen fuel cell system, the sealing level, and the number of monomers contained in the hydrogen fuel cell module, air tightness and working pressure, etc., usually Defined by the manufacturer. In the present embodiment, R _th2 is 587.4mg/h.

In the embodiment of the present invention, it is also possible to use the leakage mass Δm ₂ to determine whether there is a leakage phenomenon.

Step 7: After completing the hydrogen leakage detection of a system detection cycle, including data collection, calculation, judgment and early warning, the hydrogen leakage detection of the next detection cycle is automatically performed, and the starting time t-Δt of the system detection cycle Δt is synchronized with the end time t Increase Δt ₀ , repeat steps 1 to 6 until the vehicle stops running. Wherein Δt ₀ is an integer multiple of the sampling period t _int of the current sensor. In this embodiment, Δt ₀ is 50 times of the sampling period t _int of the current sensor.

After the vehicle is stopped, the hydrogen fuel cell system is switched off.

When a hydrogen leak is detected, an alarm is issued.

This embodiment also provides a hydrogen fuel cell system hydrogen leakage detection system. In the system, after the data is collected by the collection unit, the processor processes the data collected by the collection unit. Specifically, the detection system of this embodiment includes:

The acquisition unit is used to collect and obtain the temperature and air pressure in the high-pressure hydrogen storage tank at the time _t00 of the last vehicle stop; it is used to collect and obtain the temperature and air pressure in the high-pressure hydrogen storage tank at the start time _t00 when the vehicle is started again; It is used to collect the temperature and air pressure in the high-pressure hydrogen storage tank at the starting time t-Δt when the vehicle is running; it is used to collect and obtain the temperature and air pressure in the high-pressure hydrogen storage tank at the end time t when the vehicle is running; Collect and obtain the output current i of the hydrogen fuel cell stack.

Each detection cycle is Δt, the running time t is the end point of the current detection cycle, and the running time t-Δt is the starting point of the current detection cycle. The hardware structure of the hydrogen leakage detection system of the hydrogen fuel cell system is shown in Fig. 2. A plurality of high-pressure hydrogen storage tanks 1 communicate with the hydrogen fuel cell stack 3 through the hydrogen supply pipeline 2, and the electric energy generated by the hydrogen fuel cell stack 3 is passed through the DC The /DC voltage regulator 8 supplies the vehicle 9 after voltage regulation; a current sensor 4 is provided at the output end of the hydrogen fuel cell stack 3, and a temperature sensor 11 and a pressure sensor 12 are integrated in the bottle mouth valve of each high-pressure hydrogen storage tank 1 , the current sensor 4 , the temperature sensor 11 and the pressure sensor 12 are electrically connected to the controller 6 through the signal line 5 , and the alarm module 7 is electrically connected to the controller 6 . Various valves (such as pressure reducing valves, flow valves, electromagnetic/manual stop valves, and safety valves) are installed on the hydrogen supply pipeline 2, and the flow valve is controlled by the controller 6 to control the flow of the high-pressure hydrogen storage tank 1 to hydrogen fuel. The amount of hydrogen passing through the battery stack 3 uses the electrochemical reaction between hydrogen and oxygen in the hydrogen fuel cell stack 3 to generate electric energy. The hydrogen comes from the high-pressure hydrogen storage tank 1 and the oxygen comes from the air.

In this embodiment, the temperature sensor 11 and the air pressure sensor 12 can also be arranged on the body or tail of the high-pressure hydrogen storage tank 1 .

The acquisition unit includes a current sensor 4, a temperature sensor 11 and a pressure sensor 12. The output current of the hydrogen fuel cell stack 3 is collected by the current sensor 4, and the temperature of the hydrogen in the high-pressure hydrogen storage tank 1 is collected by the temperature sensor 11 and the pressure sensor 12 respectively. and air pressure.

The first calculation unit is used to calculate the hydrogen mass _m 00 in the high-pressure hydrogen storage tank at the last vehicle stop time t ₀₀ according to the temperature and air pressure in the high-pressure hydrogen storage tank at the last vehicle stop time t ₀₀ , as shown in formula (1) ; used to calculate the hydrogen mass m ₀ in the high-pressure hydrogen storage tank at the start-up time t ₀ according to the temperature and pressure in the high-pressure hydrogen storage tank at the start-up time t ₀ , as shown in formula (2); The temperature and air pressure in the hydrogen tank are calculated at the starting time t-Δt, and the hydrogen mass m _t-Δt in the high-pressure hydrogen storage tank is used to calculate the high-pressure hydrogen storage tank at the end time t according to the temperature and air pressure in the high-pressure hydrogen storage tank at the end time t. The internal hydrogen mass m _t is shown in formula (7); it is used to calculate the output charge Q of the hydrogen fuel cell stack in the current detection period Δt according to the output current i of the hydrogen fuel cell stack in the current detection period Δt of the system, as shown in the formula shown in (5); used to calculate the hydrogen mass m _con consumed by the hydrogen fuel cell stack for power generation in the current detection period Δt of the system according to the output charge Q of the hydrogen fuel cell stack, as shown in formula (6); and used for According to the mass mt-Δt of hydrogen in the high-pressure hydrogen storage tank at the starting time _t-Δt and the mass m _t of hydrogen in the high-pressure hydrogen storage tank at the end time t, calculate the hydrogen mass m _sup output by the high-pressure hydrogen storage tank within the current detection period Δt, as shown in Formula (8) shows.

The second calculation unit is used to calculate the hydrogen leakage rate R ₀ during the parking period of the vehicle according to the hydrogen mass m ₀₀ and m ₀ in the high-pressure hydrogen storage tank, as shown in formula (4); it is used to calculate the consumed hydrogen mass m _con , The output hydrogen mass m _sup and the hydrogen mass m _ex actively discharged by the hydrogen fuel cell system within the system detection period Δt are used to calculate the hydrogen leakage rate R ₂ within the current detection period Δt of the system, as shown in formula (10).

Judging unit, used to judge whether the leakage rate R ₀ during the parking period of the vehicle is less than or equal to the safety threshold R _th0 during parking, if yes, there is no hydrogen leakage during the parking period of the vehicle, otherwise there is hydrogen leakage during the parking period of the vehicle; Whether the leakage rate R ₂ during operation is less than or equal to the safety threshold R _th2 during operation, if yes, there is no hydrogen leakage in the current detection period Δt of the system, otherwise there is hydrogen leakage in the current detection period Δt of the system.

The program instructions corresponding to the first computing unit, the second computing unit and the judging unit are stored in the memory, and the hardware structure for executing the program instructions is the controller 6 (ie, the processor).

Alarm unit for alarming in the event of a hydrogen leak. The alarm unit is the alarm module 7, and the alarm module 7 is at least one of alarm devices such as a buzzer, a loudspeaker 10, an alarm lamp 13, and a display screen. After the controller 6 sends the alarm instruction to the alarm unit, the alarm unit sends out an alarm.

As shown in Figure 4, the partial structure of the hydrogen leakage detection system of the hydrogen fuel cell system (such as the high-pressure hydrogen storage tank 1, the hydrogen fuel cell stack 3, various sensors, the hydrogen supply pipeline 2 and the valves on the hydrogen supply pipeline) is generally Arranged on the roof of the vehicle, when hydrogen leakage occurs, it is beneficial for the hydrogen to escape upwards and prevent hydrogen from accumulating at the bottom of the vehicle and inside the vehicle. The preferred solution of the controller 6 is to be arranged in the screen cabinet of the driver's cab, and it can also be arranged in the side ceiling of the passenger compartment or in the seat screen cabinet of the passenger compartment. The preferred solution of the alarm module 7 is to adopt the loudspeaker 10, the warning light 13 and the display screen, which are arranged in the front of the driver's cab or the driver's station, so that the driver can find the leakage problem in time.

Part of the structure of the hydrogen leak detection system of the hydrogen fuel cell system can also be arranged in the special equipment compartment in the vehicle.

What is disclosed above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Anyone familiar with the technical field can easily think of changes or modifications within the technical scope disclosed in the present invention. Should be covered within the protection scope of the present invention.

Claims (12)

1. A method for detecting hydrogen leakage in a hydrogen fuel cell system, the hydrogen fuel cell system includes a high-pressure hydrogen storage tank, and the high-pressure hydrogen storage tank communicates with a hydrogen fuel cell stack through a pipeline; it is characterized in that the method includes the following steps:

   S1. Acquire the temperature and air pressure in the high-pressure hydrogen storage tank at the time t ₀₀ when the vehicle stops, and calculate the hydrogen mass _{m 00 in} the high-pressure hydrogen storage tank when the vehicle stops according to the temperature and air pressure in the high-pressure hydrogen storage tank at the time t 00 when the vehicle stops;

   S2. When the vehicle is started again, obtain the temperature and air pressure in the high-pressure hydrogen storage tank at the starting time _t0 , and calculate the hydrogen mass in the high-pressure hydrogen storage tank at the starting time _t0 according to the temperature and air pressure in the high-pressure hydrogen storage tank at the starting time _t0 m ₀ ;

   S3. According to the hydrogen mass m ₀₀ in the high-pressure hydrogen storage tank at the vehicle stop time t ₀₀ and the hydrogen gas mass m ₀ in the high-pressure hydrogen storage tank at the vehicle start time t ₀ , calculate the leakage parameter L ₀ during the parking period of the vehicle; If the leakage parameter _L0 is less than or equal to the safety threshold when the vehicle is parked, then there is no hydrogen leakage during the vehicle parking period, and the hydrogen fuel cell system is started; otherwise, there is hydrogen gas leakage during the vehicle parking period.
2. The method for detecting hydrogen leakage in a hydrogen fuel cell system according to claim 1, wherein after starting the hydrogen fuel cell system, the method further comprises the following steps:

   Step 1: When the vehicle is running, set each detection cycle as Δt, take the running time t as the end time of the current detection cycle, and the running time t-Δt as the starting time of the current detection cycle, and obtain the starting time t-Δt for high-pressure hydrogen storage The temperature and air pressure in the tank, and calculate the mass mt-Δt of hydrogen in the high-pressure hydrogen storage tank at the starting time t-Δt according to the temperature and air pressure in the high-pressure hydrogen storage tank at the starting time _t-Δt ;

   Obtain the temperature and air pressure in the high-pressure hydrogen storage tank at the end time t, and calculate the mass mt of hydrogen in the high-pressure hydrogen storage tank at the end time t according to the temperature and air pressure in the high-pressure hydrogen storage tank at the end time _t ; continuously collect the hydrogen fuel cell system output current i;

   Step 2: According to the mass mt-Δt of hydrogen in the high-pressure hydrogen storage tank at the starting time _t-Δt and the mass mt of hydrogen in the high-pressure hydrogen storage tank at the end time _t, calculate the mass m of hydrogen output from the high-pressure hydrogen storage tank within the current detection period Δt _sup ;

   Calculate the output charge Q of the hydrogen fuel cell stack in the current detection period Δt according to the waveform of the output current i of the hydrogen fuel cell system in the current detection period Δt; calculate the current detection according to the charge Q output by the hydrogen fuel cell stack in the current detection period Δt The hydrogen mass m _con consumed by the hydrogen fuel cell system for power generation within the period Δt;

   Step 3: According to the hydrogen mass m _sup output by the high-pressure hydrogen storage tank in the current detection cycle Δt, the hydrogen gas mass m _con consumed by the hydrogen fuel cell system for power generation, and the hydrogen gas mass m actively discharged by the hydrogen fuel cell system in the current detection cycle Δt _ex , calculate the leakage parameter L of the hydrogen fuel cell system within the current detection period Δt;

   Step 4: Judging whether the leakage parameter L is less than or equal to the hydrogen leakage safety threshold when the vehicle is running, if so, there is no hydrogen leakage in the current detection cycle Δt, otherwise there is hydrogen leakage in the current detection cycle Δt;

   Step 5: Repeat steps 1 to 4 to detect hydrogen leakage in the next detection cycle until the vehicle stops running.
3. The method for detecting hydrogen leakage in a hydrogen fuel cell system according to claim 2, wherein the specific calculation formula for calculating the mass of hydrogen in the high-pressure hydrogen storage tank at a certain moment is as follows: :

   

   Among them, m is the mass of hydrogen in the high-pressure hydrogen storage tank at this moment, μ is the molar mass of hydrogen, R is the molar gas constant, T is the temperature of hydrogen in the high-pressure hydrogen storage tank at the corresponding moment, and p is the temperature in the high-pressure hydrogen storage tank at the corresponding moment The air pressure, V is the volume of the high-pressure hydrogen storage tank.
4. According to the hydrogen fuel cell system hydrogen leakage detection method according to claim 2, it is characterized in that the specific calculation formula of the hydrogen mass m _sup output by the high-pressure hydrogen storage tank within the current detection period Δt is:

   m _sup =m _{t -Δt} -m _t .
5. The hydrogen fuel cell system hydrogen leakage detection method according to claim 2, characterized in that the specific calculation formula of the charge Q output by the hydrogen fuel cell stack in the current detection cycle Δt is:

   
6. According to the hydrogen fuel cell system hydrogen leakage detection method according to claim 5, it is characterized in that the specific calculation formula of the hydrogen mass m _con consumed by the hydrogen fuel cell system for power generation within the current detection period Δt is:

   

   Among them, μ is the molar mass of hydrogen, Q _e is the charge carried by a single electron, and N _A is Avogadro's constant.
7. According to the hydrogen fuel cell system hydrogen leakage detection method according to claim 2, it is characterized in that the specific calculation formula of the mass m _ex of hydrogen actively discharged within the current detection period Δt is:

   m _ex = n × m _ex0 ;

   Among them, n is the number of opening times of the discharge valve on the pipeline when hydrogen is actively discharged in the current detection period Δt, and m _ex0 is the mass of hydrogen that is actively discharged when the discharge valve is opened for a single time.
8. The hydrogen fuel cell system hydrogen leakage detection method according to any one of claims 1 to 7, wherein the leakage parameter is a leakage rate or a leakage mass, and the calculation formula of the leakage rate is:

   

   Where _R2 is the hydrogen leakage rate of the hydrogen fuel cell system within the current detection period Δt, that is, the hydrogen leakage mass per unit time.
9. The method for detecting hydrogen gas leakage in a hydrogen fuel cell system according to any one of claims 1 to 7, characterized in that when it is determined that there is hydrogen gas leakage, an alarm is issued.
10. A method for detecting hydrogen leakage in a hydrogen fuel cell system, the hydrogen fuel cell system includes a high-pressure hydrogen storage tank, and the high-pressure hydrogen storage tank communicates with a hydrogen fuel cell stack through a pipeline; it is characterized in that it includes the following steps:

    Step 1. When the vehicle is running, set each detection cycle as Δt, take the running time t as the end time of the current detection cycle, and the running time t-Δt as the starting time of the current detection cycle, and obtain the starting time t-Δt for high-pressure hydrogen storage The temperature and air pressure in the tank, and calculate the mass mt-Δt of hydrogen in the high-pressure hydrogen storage tank at the starting time t-Δt according to the temperature and air pressure in the high-pressure hydrogen storage tank at the starting time _t-Δt ;

    Obtain the temperature and air pressure in the high-pressure hydrogen storage tank at the end time t, and calculate the mass mt of hydrogen in the high-pressure hydrogen storage tank at the end time t according to the temperature and air pressure in the high-pressure hydrogen storage tank at the end time _t ; continuously collect the hydrogen fuel cell system output current i;

    Step 2: Calculate the mass m of hydrogen output from the high-pressure hydrogen storage tank within the current detection period Δt according to the mass mt-Δt of hydrogen in the high-pressure hydrogen storage tank at the starting time _t-Δt and the mass mt of hydrogen in the high-pressure hydrogen storage tank at the end time _{t sup} ;

    Calculate the output charge Q of the hydrogen fuel cell stack in the current detection period Δt according to the waveform of the output current i of the hydrogen fuel cell system in the current detection period Δt; calculate the current detection according to the charge Q output by the hydrogen fuel cell stack in the current detection period Δt The hydrogen mass m _con consumed by the hydrogen fuel cell system for power generation within the period Δt;

    Step 3, according to the hydrogen mass m _sup output by the high-pressure hydrogen storage tank in the current detection cycle Δt, the hydrogen gas mass m _con consumed by the hydrogen fuel cell system for power generation, and the hydrogen gas mass m actively discharged by the hydrogen fuel cell system in the current detection cycle Δt _ex , calculate the leakage parameter L of the hydrogen fuel cell system within the current detection period Δt;

    Step 4, judging whether the leakage parameter L is less than or equal to the safety threshold of hydrogen leakage when the vehicle is running, if so, there is no hydrogen leakage in the current detection period Δt, otherwise there is hydrogen leakage in the current detection period Δt;

    Step 5: Repeat steps 1-4 to detect hydrogen leakage in the next detection cycle until the vehicle stops running.
11. A hydrogen fuel cell system hydrogen leakage detection system, characterized in that it includes a memory and a processor; the memory stores computer programs/instructions; the processor executes the computer programs/instructions stored in the memory; the computer program The /instructions are configured to implement the steps of the method described in one of claims 1-9; or, the computer program/instructions are configured to implement the steps of the method described in claim 10.
12. A rail transit vehicle, characterized in that it comprises the hydrogen fuel cell system hydrogen leakage detection system according to claim 11.

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