Energy conversion control method based on industrial fuel cell-steam heat pump coupling electric hydrogen steam co-production system

Abstract

The invention discloses an electric hydrogen and steam co-production system based on industrial fuel cell-steam heat pump coupling. The hybrid system mainly comprises a wind generating set, an alkaline electrolytic bath, a hydrogen tank, a proton exchange membrane fuel cell, a heat storage tank and a steam heat pump. The power generation output end of the wind driven generator is connected with the factory power grid and then connected with the alkaline electrolytic cell unit, the hydrogen output end of the alkaline electrolytic cell is connected with the hydrogen compressor and compressed into the hydrogen tank, the output end of the hydrogen tank is connected with the hydrogen input end of the fuel cell, and the power generation output end of the fuel cell is connected with the factory power grid. And industrial power energy scheduling is realized. According to the invention, heat control of the proton exchange membrane fuel cell and the alkaline electrolytic cell is realized by heat exchange between the circulating cooling water system and the heat exchanger, waste heat is upgraded by the steam heat pump and heated into saturated steam of more than 130 DEG C, and the saturated steam is connected into a chemical plant to meet steam requirements. According to the invention, unstable wind power is converted into chemical energy of hydrogen for storage.

Description

Technical Field

[0001] The present invention belongs to the technical field of wind power, thermal power, energy storage and peak-shaving power generation, and specifically relates to an electricity-hydrogen-steam trigeneration system and method. Background Art

[0002] With the vigorous development of new energy power generation in China, wind power, as a clean and environmentally friendly energy, occupies an important position in new energy power generation. In recent years, my country's wind power installed capacity has continued to rise. However, many regions still have serious problems of wind power abandonment.

[0003] After research, the inventors found that there are many problems in the application of wind power: (1) Unlike traditional coal-fired or thermal power generation, wind power generation itself has very obvious randomness. Both wind direction and wind speed often change, which has a great impact on the use status of the wind turbine itself during use. (2) Due to the intermittent and volatile nature of wind, the quality of electric energy is damaged to a certain extent, which has an adverse effect on the grid connection of wind power. (3) The peak-shaving flexibility of thermal power is poor, especially for cogeneration units. Its "heat-to-electricity" operation mode leads to a small adjustable capacity of thermal power, leaving very limited space for wind power grid connection. The structural contradiction of my country's power supply is prominent, resulting in serious problems of wind and power abandonment, and the efficiency of new energy utilization is greatly reduced. (4) In order to reduce the steam load pressure in industrial production, some existing technologies use gas boilers to produce steam, and use multi-stage energy release and improved heat dissipation to improve the utilization rate of steam. However, this technology fails to reduce the carbon emissions of steam generated by boilers, so that enterprises still face great environmental pressure while pursuing efficient energy use. (5) Some existing industrial solutions use waste heat recovery to drive steam generation systems, striving to achieve energy recycling within the factory. However, the initial heat source for driving steam generation in this system mostly comes from the combustion of traditional energy sources such as coal, and the problem of energy cleanliness has not been effectively improved. On the contrary, as the steam generation and transmission links become more complicated and the thermal cycle route is extended, the energy loss of this technology and the pollutant life cycle emissions increase. Summary of the invention

[0004] In order to solve the problems of intermittent and random wind power generation, grid connection difficulties, and the inability of existing steam generation systems to achieve carbon dioxide emission reduction in the entire life cycle cycle, the present invention proposes an electricity-hydrogen-steam trigeneration system and method, in which a wind turbine is connected to the grid, and according to the grid load instruction, non-grid-connected wind power is creatively connected to an alkaline electrolyzer, a hydrogen compressor, and a hydrogen storage tank during low electricity consumption to prepare stored hydrogen energy, and the originally wasted unstable wind power is converted into hydrogen chemical energy for storage to achieve stable output of electric energy and avoid excessive impact on the grid; during peak electricity consumption, hydrogen is used for hydrogen fuel cell power generation system to generate electricity. A high-temperature heat pump is used to effectively recover the waste heat of the proton exchange membrane fuel cell cooling system and the waste heat of the alkaline electrolyzer power generation to produce steam, meet the steam and electricity needs in the industrial field, achieve the supply of high-grade thermal products, broaden the application field of fuel cells, and reduce carbon emissions.

[0005] Specifically, the present invention is achieved through the following technical solutions:

[0006] In a first aspect, the present invention provides an electric power hydrogen steam cogeneration system, comprising: a wind turbine generator set, an alkaline electrolyzer system, a hydrogen storage tank, a heat storage tank, a steam heat pump system and a fuel cell system;

[0007] The wind turbine generator set is connected to the power grid and the alkaline electrolyzer system, the hydrogen output end of the alkaline electrolyzer system is connected to the hydrogen input end of the hydrogen storage tank, the output end of the hydrogen storage tank is connected to the fuel cell system, the thermal management system of the alkaline electrolyzer and the fuel cell is connected to the heat storage tank, and the output end of the heat storage tank is connected to the steam heat pump system.

[0008] In a second aspect, the present invention provides a method for co-generating electricity, hydrogen and steam, comprising: using wind energy to drive the wind wheel of the wind turbine unit to rotate, converting the kinetic energy of the wind into mechanical energy, and converting the mechanical energy into electrical energy through a generator. The wind turbine generator inputs the electrical energy into a power grid, and the power grid provides the chemical plant user unit with electrical energy for daily production.

[0009] When the power generation of the wind turbine unit is greater than the power demand of the chemical plant, the system enters the energy storage hydrogen production stage, and the cogeneration system needs to convert the excess electricity into hydrogen energy storage. The system starts the alkaline electrolyzer and circulating pump and other hydrogen production equipment to absorb the excess electricity of the wind turbine. The wind turbine's electricity is input into the electrolyzer, and the water in the electrolyte is electrolyzed into hydrogen and oxygen. In order to increase the energy storage density of the system, the hydrogen is compressed to a high-pressure state through multiple stages and the high-pressure hydrogen is input into the hydrogen storage tank unit.

[0010] When the power generation of the wind turbine is less than the industrial load power, the system enters the energy release and discharge stage, and the cogeneration system starts the fuel cell unit. The high-pressure hydrogen in the hydrogen storage tank is input into the fuel cell to generate electricity. In the fuel cell system, hydrogen and oxygen are passed through the filter and compressor into the positive and negative electrodes of the stack to react, generating 40-50% energy-efficient electrical power and a large amount of chemical reaction heat. This part of the waste heat is taken away by the fuel cell cooling water system to cool the stack. The remaining hydrogen from the reaction is reconnected to the hydrogen inlet to achieve hydrogen recycling, and the reaction waste heat and generated water are used to heat and humidify the inlet hydrogen, thereby improving the utilization rate of hydrogen and improving the water balance. The electrical energy generated by the fuel cell is input into the power grid, and the power grid provides electrical energy to the chemical plant.

[0011] The thermal management unit is used to output the heat in the fuel cell and the alkaline electrolyzer to the heat storage tank unit to achieve temperature control of the fuel cell and the alkaline electrolyzer. The oily wastewater with an average temperature of 60°C enters the hot water tank after the initial separation, sedimentation, filtration, sterilization, anti-scaling and other treatment processes. The hot water tank is connected to the steam heat pump unit for waste heat recovery. The steam heat pump uses 60°C industrial waste heat to treat water, 80°C waste heat cooling water from the fuel cell and 80°C waste heat from the electrolyzer, and upgrades the heat flow to saturated steam above 130°C, reducing the energy consumption of battery ancillary equipment, and outputs steam to meet industrial production needs.

[0012] The specific steps include:

[0013] Step 1: Establish a mathematical model of the power, hydrogen and steam cogeneration system.

[0014] Step 2: Establish a system performance analysis model.

[0015] Step 3: Using the output thermal power, COP, output net power and SSR of the fuel cell-heat pump as the target quantities, and the operating temperature, current density, waste heat energy density and heat flow ratio of the heat pump as the decision variables, the data set is obtained using matlab / simulink software.

[0016] Step 4: By monitoring the difference between wind turbine power and power consumption and the operating status of hydrogen storage tanks, establish the control strategy of the power-hydrogen-steam cogeneration system, and perform simulation calculation and analysis based on wind speed and power consumption. Efficiency Assessment of the energy conversion capacity of power, hydrogen and steam cogeneration systems and equipment.

[0017] In general, the above technical solution conceived by the present invention has the following beneficial effects compared with the prior art:

[0018] The present invention discloses a mathematical model and a performance analysis model for an electricity, hydrogen and steam cogeneration system, and realizes refined management and control of multi-energy collaboration. On the one hand, by using MATLAB / Simulink software to accurately obtain data sets, and taking multiple key indicators as target quantities and decision variables, it is possible to deeply explore the optimal parameter combination for system operation, greatly improving the accuracy and stability of system operation, and effectively avoiding energy waste and inefficiency caused by unreasonable parameter settings in traditional modes. On the other hand, the unique control strategy can be adjusted in real time according to the difference between wind turbine power and power consumption and the status of hydrogen storage tanks, adapting to complex and changeable energy supply and demand scenarios, and ensuring a continuous and stable supply of energy. Through the efficiency of the electricity-hydrogen-steam cycle and The energy conversion capacity evaluation based on efficiency provides an intuitive and reliable quantitative basis for system optimization and helps to improve accurately. Compared with existing technologies, it not only significantly improves the comprehensive utilization efficiency of energy and reduces operating costs, but also enhances the adaptability of the entire system to different working conditions, providing strong technical support for promoting clean and efficient use of energy and achieving sustainable development, and has broad market application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of an embodiment of the system of the present invention;

[0020] Figure 2 It is the influence diagram of key operating parameters on COP and system heating supply;

[0021] Figure 3 It is the influence diagram of key operating parameters on the system power generation capacity and SSR;

[0022] Figure 4 is the system control strategy diagram;

[0023] Figure 5 It is systematic Efficiency and Damage map;

[0024] In the figure: 1. Wind turbine; 2. Alkaline electrolyzer; 3. Hydrogen storage tank; 4. Fuel cell; 5. Heat storage tank; 6. High-temperature heat pump; 7. Factory load. DETAILED DESCRIPTION

[0025] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thoroughly understood.

[0026] Figure 1 Schematic diagram of the structure of the system embodiment of the present invention, Figure 1 As shown, it includes: 1 wind turbine unit, 2 alkaline electrolyzer units, 3 hydrogen storage tank units, 4 fuel cell units, 5 heat storage tank units, 6 steam heat pump units and 7 chemical plant user units.

[0027] The overall technical process of the system described in the present invention is as follows: Figure 1 As shown, the specific steps include:

[0028] Step 1: Establish a mathematical model of the power, hydrogen and steam cogeneration system.

[0029] Step 1.1: Establish a mathematical model of wind turbine generator set.

[0030] The wind speed model divides the wind speed into two parts: quasi-steady-state wind speed and turbulent wind speed. The wind speed data can be obtained in real time by superimposing the quasi-steady-state wind speed and turbulent wind speed. The formula is:

[0031] v W =v1+v2 (1)

[0032] In the formula, v w is the wind speed, in m / s; v1 is the turbulent wind speed, in m / s; v2 is the quasi-static wind speed, in m / s;

[0033] The turbulent wind speed uses a standard normal distribution white noise generator to simulate the turbulent wind speed changes. The turbulent wind speed satisfies the following equation:

[0034]

[0035]

[0036] Where, T v is a time constant, which is related to the hub height of the wind turbine and the medium wind speed; w is the hub height of the wind turbine rotor, in m; v0 is the medium wind speed of the wind turbine, in m / s; m w is the standard normally distributed white noise, unit is m / s.

[0037] The output power of a wind turbine is related to wind speed, air density and the area swept by the rotor; based on aerodynamic theory, the output power of a wind turbine is:

[0038]

[0039] Where P wt is the output power of the wind turbine, in kW; ρ1 is the air density, in kg / m 3 ; R w is the length of the wind turbine blade; C p(λ,β) is the wind energy utilization coefficient of the wind turbine, where λ is the tip speed ratio and β is the pitch angle of the wind rotor, in degrees.

[0040] The tip speed ratio λ is the ratio of the tip linear velocity of the wind turbine blade to the wind speed. The calculation formula is:

[0041]

[0042] Where ω is the angular velocity of the wind turbine rotor, in rad / s; n w is the wind turbine speed, in r / min. The wind energy utilization coefficient is the ratio of the mechanical power output of the wind turbine to the wind energy power input into the wind wheel surface, C p The specific expression of (λ,β) is as follows:

[0043]

[0044]

[0045] Step 1.2: Establish a mathematical model of the alkaline electrolyzer stack.

[0046] The catalyst of the anode of the alkaline electrolyzer is composed of nickel, cobalt and iron, and the cathode is composed of nickel and platinum activated carbonizer. The reaction formula for hydrogen production by electrolysis of water is:

[0047] 2H2O=2H2+O2 (8)

[0048] The voltage of a single electrolytic cell of an alkaline electrolytic cell is related to parameters such as operating current, operating temperature, and electrode surface area. The output voltage of an alkaline electrolytic cell is:

[0049]

[0050] Where U el is the working voltage of the electrolytic cell, in V; U rev is the reversible voltage of the electrolytic cell that changes with temperature, in V; I el is the working current of the electrolytic cell, in A; r1, r2 are the ohmic resistance parameters of the electrolyte; T el is the working temperature of the electrolytic cell, in °C; k el , is the overvoltage parameter on the electrolytic cell electrode; S el is the surface area of ​​the electrolytic cell electrodes, in m 2 .

[0051] Reversible voltage U of the electrolytic cell rev and the electrolytic cell temperature T el The relationship is shown as follows:

[0052]

[0053] In the formula, is the reversible voltage under standard conditions; k rev is the empirical temperature coefficient of the reversible voltage.

[0054] In the large-scale hydrogen production process, it is often necessary to convert several (n el ) The single electrolyzers work in series, then the output voltage U EL for:

[0055] U EL =n el ·U el (11)

[0056] The hydrogen production rate of an alkaline electrolyzer is proportional to the operating current density. The hydrogen production rate is:

[0057]

[0058] In the formula, is the rate of hydrogen generation, in mol / s; η el is the electrolytic cell current efficiency, unit: %.

[0059] The current efficiency of the alkaline electrolyzer can be calculated according to the empirical formula:

[0060]

[0061] The heat generated by the alkaline electrolyzer is consumed by maintaining its own temperature, dissipating heat to the environment, and absorbing heat from cooling water. According to the law of conservation of thermodynamic energy, the thermal model of the alkaline electrolyzer is:

[0062]

[0063] In the formula, is the rate of heat generation during hydrogen production in an alkaline electrolyzer, in J / s; is the rate of heat generation during hydrogen production in an alkaline electrolyzer, in J / s; is the rate of heat generation during hydrogen production in an alkaline electrolyzer, in J / s; It is the rate of heat generation during hydrogen production in an alkaline electrolyzer, in J / s.

[0064] The heat generation of an alkaline electrolytic cell is related to the operating current, operating voltage, and power efficiency. The heat generation rate of an alkaline electrolytic cell is:

[0065]

[0066]

[0067]

[0068] Where η ef is the power efficiency, unit is %; U th is the thermal neutral voltage, unit V; η ef It is the electrical energy efficiency, unit is %.

[0069] The operating temperature of the alkaline electrolyzer meets the following requirements:

[0070]

[0071] In the formula, C el is the heat capacity of the alkaline electrolytic cell, in J / K.

[0072] The ambient heat dissipation of the alkaline electrolyzer is:

[0073]

[0074] In the formula, R el It is the thermal resistance value of alkaline electrolytic cell, unit is K / W.

[0075] The heat flow rate removed by the cooling water system is related to the temperature difference between the cooling water inlet and outlet:

[0076]

[0077] The hydrogen production efficiency is proportional to the quality of hydrogen produced and inversely proportional to the power consumption, that is:

[0078]

[0079] Where η hy is the hydrogen production efficiency of the alkaline electrolyzer, unit: %; W el is the power consumption of the alkaline electrolyzer, in J; M1 is the mass of hydrogen produced, in mol.

[0080] Step 1.3: Establish a mathematical model of the proton exchange membrane fuel cell stack.

[0081] The stack system can calculate the output power of the PEMFC and some inevitable losses in the battery. Output voltage of a single cell:

[0082] V cell =E nernst -η act -η ohmic -η conc (twenty two)

[0083] In the formula, E nernst is the Nernst voltage, in V; η act is the activation overvoltage, unit V; η ohmic is the ohmic overvoltage, unit V; ηconc is the mass concentration overvoltage, in V.

[0084] The Nernst equation is used to confirm the reversible potential generated by the chemical reactions inside the PEMFC:

[0085]

[0086] Where, T stack is the internal temperature of the battery stack; and are the partial pressures on the hydrogen side and the partial pressures on the oxygen side, respectively;

[0087] The partial pressures of hydrogen and oxygen are expressed as:

[0088]

[0089]

[0090] Where T stack is the reaction temperature; P Anode is the anode partial pressure, unit is atm; P Cathode is the cathode partial pressure; i is the current density; P H2O is the saturation pressure of water.

[0091]

[0092] T s =T stack -273.15 (27)

[0093] The activation overvoltage is the energy consumed by the cathode and anode to start the chemical reaction by crossing the electrolyte, overcoming the activation energy required for the reaction:

[0094]

[0095]

[0096]

[0097] Among them, β1, β2, β3, and β4 are empirical constants of fuel cells; are the effective partial pressures on the anode and cathode catalysts, respectively; A is the effective activation area of ​​a single cell.

[0098] The total ohmic loss of the resistor can be divided into electron ohmic loss and proton ohmic loss, of which the electron loss is smaller and is not considered. According to Ohm's law, we can get:

[0099] η ohm =iAR int (31)

[0100] Among them, R int is the equivalent resistance of the proton exchange membrane. It is determined by conductivity, temperature and humidity:

[0101]

[0102] Where t0 represents the membrane thickness; σ represents the influence of membrane conductivity on temperature, membrane water content and current density:

[0103]

[0104] Where λ is the water content of the proton exchange membrane.

[0105] As the battery power increases, the current density increases, and the reaction rate on the catalyst exceeds the gas supply rate flowing into the cell, resulting in voltage loss.

[0106]

[0107] Among them, i max is the maximum current density that a fuel cell can achieve.

[0108] When modeling the fuel cell stack, assuming that the performance of each single cell in the fuel cell stack is consistent, the fuel cell stack voltage can be calculated as follows:

[0109] V fc =N·V cell (35)

[0110] The total electrical power and thermal power of the stack can be obtained by the following formula:

[0111] P fc =V fc ·i·A cell (36)

[0112] The heat generated in the stack is taken away from the stack by cooling water and reaction gas. The heat balance equation of the stack temperature can be derived from the law of conservation of energy as follows:

[0113]

[0114] The total power of the electrochemical reaction is expressed as:

[0115]

[0116] The heat taken away from the stack by cooling water is:

[0117]

[0118] The amount of hydrogen consumed by a hydrogen fuel cell during operation is determined by the operating state. The power generation efficiency of a hydrogen fuel cell is related to the amount of electricity output and the quality of hydrogen consumed, namely:

[0119]

[0120] Where η fc is the power generation efficiency of the fuel cell, in %; W fc is the power generation of the fuel cell, in J; M2 is the mass of hydrogen consumed, in mol.

[0121] Step 1.4: Establish a mathematical model of the steam heat pump.

[0122] The coefficient of performance (COP) of a steam heat pump is an indicator to measure the energy efficiency of a heat pump system, which indicates the ratio of heat or cooling that can be provided per unit of energy consumed in the process of converting primary energy into thermal energy.

[0123]

[0124] Where, T co is the outlet temperature of the heat pump condenser, in K; T eo is the outlet temperature of the heat pump evaporator, unit K;

[0125] The heat transferred by the steam heat pump is the energy that the steam heat pump absorbs from the heat storage tank and transfers to the steam tank after compression and circulation. The heat transferred depends on the energy efficiency and working performance of the heat pump:

[0126] Q c =COP*E wp (42)

[0127] Q e =Q c -E wp =(COP-1)*E wp (43)

[0128] In the formula, Q c is the heat supply of the heat pump, unit W; E wp is the power consumption of the heat pump, in W; COP is the coefficient of performance of the heat pump; Q e Heat pump removes heat.

[0129] The output temperature of a steam heat pump depends on factors such as its operating mode (heating or cooling), input heat and output heat load requirements.

[0130]

[0131]

[0132] in, are the mass flow rates of waste heat cooling water at the condensing end and evaporating end and steam tank water vapor respectively; c w 、c avgare the specific heat capacities of cooling water and steam, respectively.

[0133] The specific heat capacity of water vapor requires additional calculation:

[0134] The heat transfer during the water heating phase is:

[0135]

[0136] The heat transfer during the water evaporation stage is:

[0137]

[0138] The heat transfer during the water evaporation stage is:

[0139]

[0140] Total heat transfer (Q s )for:

[0141] Q s =Q1+Q2+Q3

[0142] The average specific heat capacity is:

[0143]

[0144] Where, T ci is the inlet temperature of the heat pump condenser, unit K; ΔT c Indicates the temperature difference between the inlet and outlet of the condenser; ΔT1 and ΔT3 indicate the temperature difference at each stage in the condenser;

[0145] Step 2: Establish a system performance analysis model.

[0146] From energy conversion efficiency, Efficiency and The performance of the system is objectively evaluated in three aspects of loss.

[0147] The net output power of the system is defined as:

[0148] W=W fc -W HP (50)

[0149] The electrical conversion rate of the system is:

[0150]

[0151] The power self-sufficiency ratio (SSR) is the ratio of the power provided by the PEMFC to the power consumed by the heat pump:

[0152]

[0153] Where W fcis the power generation of the fuel cell, in J; W HP is the power consumption of the steam heat pump, unit is J.

[0154] The power-hydrogen-steam cycle efficiency of the system is defined as:

[0155]

[0156] Where, η is the system's electricity-hydrogen-steam cycle efficiency, unit: %; W el It is the power consumption of alkaline electrolytic cell, unit is J.

[0157] system Efficiency (E x_s )and Loss (E x_loss ) is calculated according to the following formula:

[0158]

[0159]

[0160] In the formula, E x_in For input system Value, unit J; E x_out For outflow system Value, unit J; Water for hydrogen production Value, unit J; Hydrogen output for the system Value, unit J; Oxygen output for the system Value, unit J; E x_Stream Steam output for the system Value, unit is J.

[0161] Alkaline electrolyzer Efficiency (E x_el )and Loss (E x_loss_el ) are:

[0162]

[0163]

[0164] In the formula, Producing hydrogen for alkaline electrolyzers Value, unit J; Producing oxygen for alkaline electrolyzers Value, unit J; Water for hydrogen production Value, unit is J.

[0165] Fuel Cell Efficiency (E x_fc )and Loss (E x_loss_fc ) are:

[0166]

[0167]

[0168] In the formula, Hydrogen consumption for fuel cells Value, unit J; Consuming oxygen for fuel cells Value, unit J; To generate water for fuel cells Value, unit is J.

[0169] Steam heat pump Efficiency (E x_HP )and Loss (E x_loss_HP ) are:

[0170]

[0171]

[0172] In the formula, E x_Stream Generating steam for steam heat pumps Value, unit J; For water consumption in steam heat pumps Value, unit is J.

[0173] Step 3: Using the output thermal power, COP, output net power and SSR of the fuel cell-heat pump as the target quantities, and the operating temperature, current density, waste heat energy density and heat flow ratio of the heat pump as the decision variables, the data set is obtained using matlab / simulink software.

[0174] Furthermore, the code was written in the matlab editor to make the temperature (60-90°C), heat flux ratio (0-1.2), waste heat energy density (41.57-83.14 kJ / kg) and current density (0.6-1.2 A / cm 2 ) Generate several uniform random arrays within the specified range, and then substitute these decision variables into the simulink model to obtain the corresponding output thermal power, COP, output net power and SSR values, and save these decision variables and target quantities as data sets in the matlab workspace. Table 1 lists all system parameters under standard conditions in the simulation.

[0175] Table 1 System performance under different working conditions

[0176]

[0177] further, Figure 2 The relationship between the key operating parameters of the system and its COP and heating capacity is illustrated. With the increase of energy density, the heating capacity of the system increases significantly. With the increase of energy density, the extraction of heat from the thermal storage tank becomes more efficient, thus reducing the power consumption of the compressor. COP and heating capacity are affected by the change of current density, such as Figure 2 (a). As the current density increases, the heat output capacity of the system increases significantly, while the COP remains stable. This phenomenon is mainly due to the decrease in the cell output voltage as the current density increases. Especially at high current density, the concentration polarization effect intensifies, causing the cell output voltage to drop sharply, thereby generating more heat. The stable COP of the heat pump is attributed to the increase in waste heat provided by the proton exchange membrane fuel cell, which leads to an increase in the mass flow rate of the working fluid in the heat pump subsystem. The power consumption of the compressor and the system heating capacity both increase by the same multiple, thereby maintaining a stable COP.

[0178] Figure 2 (b) illustrates the effect of the heat circuit flow ratio on the system COP and heating capacity under different energy densities. As the heat circuit flow ratio increases, the heating capacity of the system increases, but the COP shows a downward trend. The main reason for this phenomenon is that as the heat flow ratio increases, the system absorbs more heat from the heat storage tank, thereby increasing the heat provided. The enhancement of the system's heating capacity is due to the larger heat flow ratio resulting in more heat being absorbed from the heat storage tank. However, the increase in the heat circuit flow means that more working fluid passes through the waste heat absorption circuit, thereby increasing the load on the compressor. Since the increase in the compressor load is greater than the increase in the system heating capacity, the system's COP decreases with the increase in the heat circuit flow ratio.

[0179] Figure 2 (c) shows the effect of the stack operating temperature on the system COP and heat generation capacity at different energy densities. As the temperature increases from 333.15K to 363.15K, the heating capacity decreases steadily, the rate of change gradually slows down, and the COP continues to increase. The output voltage of the fuel cell initially increases with temperature until it reaches a peak of 348.15K, and then gradually decreases. In contrast, the heat generated by the fuel cell first decreases with increasing temperature, and then slowly increases. As the operating temperature of the fuel cell increases, the heat dissipation from the gas and the environment also increases. Although the heat output of the fuel cell initially increases with the increase in operating temperature, when the operating temperature exceeds 348.15K, the rate of increase in the heat dissipation from the gas and the environment exceeds the waste heat output, resulting in a decrease in the overall heat output. As the temperature of the fuel cell increases, the power consumption of the compressor decreases, so the COP of the heat pump system increases.

[0180] Figure 3 The influence of various operating parameters on the power consumption characteristics of the system is shown. The power axis 0-400kW represents the power supplied to the grid. The trend in the chart represents the difference in the power consumption performance of the system at different energy densities. As the energy density increases, the self-sufficiency rate of the system decreases, while the power consumption of the system itself increases. As the energy density increases, more heat is extracted from the thermal storage tank, thereby increasing the power consumption of the compressor.

[0181] from Figure 3 As can be seen in (a), as the PEMFC current density increases, the amount of electricity supplied to the grid gradually increases. As the current density increases, the demand for reactants also increases, resulting in higher power consumption by the compressor. In addition, the heat expansion provided by the fuel cell causes the refrigerant flow rate to increase, causing the load on the compressor to rise, thereby increasing the total power consumption of the system. As the current density increases further, the PEMFC power decreases, resulting in a gradual increase in system power consumption and a decrease in SSR.

[0182] exist Figure 3 In (b), the increase in heat flow ratio upgrades the power consumption of the system. For example, at a waste heat energy density of 41.57 kJ / kg, as the heat flow ratio of the system increases from 0 to 1.2, its power consumption increases from 115.1 kW to 184.8 kW. The increase in heat flow ratio means an increase in the refrigerant that absorbs heat from the industrial wastewater, resulting in an increase in the load on the compressor, which increases the power consumption of the system and reduces its self-sufficiency.

[0183] Figure 3 The results in (c) show that as the operating temperature of the PEMFC gradually increases, the power consumption of the system decreases, while the self-sufficiency rate increases. For example, when the waste heat energy density is 41.57 kJ / kg, 62.36 kJ / kg, and 83.14 kJ / kg, the self-sufficiency rate of the system increases by 200.4%, 182.6%, and 162.9%, respectively, when the operating temperature increases from 333.15 K to 363.15 K. As the operating temperature of the fuel cell increases, the power output of the fuel cell increases. In addition, the temperature of the fuel cell cooling water increases, resulting in a reduction in the compressor load, thereby reducing the power consumption of the system and improving the self-sufficiency rate.

[0184] Step 4: By monitoring the difference between wind turbine power and power consumption and the operating status of hydrogen storage tanks, the control strategy of the power-hydrogen-steam cogeneration system was established, and the system was simulated and analyzed based on wind speed and power consumption. Efficiency evaluates the energy conversion capabilities of power-hydrogen-steam cogeneration systems and equipment.

[0185] The control strategies of the power, hydrogen and steam cogeneration system can be divided into energy storage strategies and energy release strategies. The power generated by wind turbines is first supplied to users for consumption, and the excess power is provided to alkaline electrolyzers, hydrogen compressors, circulation pumps and other equipment to realize the energy storage process of the system. The electric energy that is not consumed by the power, hydrogen and steam cogeneration system is regarded as abandoned power. When the output power of the wind turbine is less than the electrical power consumption, the hydrogen storage tank supplies hydrogen energy to the hydrogen fuel cell. The fuel cell is put into operation to supplement the power generation of the system and converts hydrogen energy into electrical energy to realize the energy release process of the system. The control strategies for the energy storage process and the energy release process of the power, hydrogen and steam cogeneration system are as follows: Figure 4 .

[0186] There may be a difference between the output power of the wind turbine and the power consumption. Energy management timely adjusts the operating status of the hydrogen production equipment in the power hydrogen steam cogeneration system according to the real-time power difference, absorbing the power generation of the wind turbine as much as possible. S for:

[0187] P S =P wt -P L (65)

[0188] Where P wt is the output power of the wind turbine, W; P L is the electrical power used in the chemical plant, W.

[0189] When the output power of the wind turbine generator is greater than the power consumption, the power difference of the power hydrogen steam cogeneration system is used to determine whether to start the alkaline electrolyzer to produce hydrogen. S When it is greater than 0, the power hydrogen steam cogeneration system determines whether to produce hydrogen based on the pressure of the hydrogen in the storage tank. The pressure of the hydrogen storage tank should meet

[0190] p st <p max (66)

[0191] In the formula, p st is the pressure of hydrogen in the hydrogen storage tank, Pa; p max is the maximum safe working pressure limit of the hydrogen storage tank, Pa.

[0192] Considering the service life and startup time of the alkaline electrolyzer, frequent start and stop should be avoided as much as possible. At present, the alkaline electrolyzer has the ability to work with wide power fluctuations within a certain range, and the power operation range is usually 20% to 100% of the rated power. Whether the alkaline electrolyzer has the startup conditions is related to the size of the power difference of the power hydrogen steam cogeneration system. When the power difference meets the operating power demand of the alkaline electrolyzer for hydrogen production, the remaining power is supplied to the alkaline electrolyzer, steam heat pump and other equipment.

[0193] PS =P el +P HP (67)

[0194] Where P el is the input power of the alkaline electrolyzer, W; P HP The power consumed by the steam heat pump to recover the waste heat from the alkaline electrolyzer and fuel cell, W.

[0195] When the power difference of the power hydrogen steam cogeneration system is less than the minimum starting power of the alkaline electrolyzer, the alkaline electrolyzer is in shutdown state. When the power difference of the WHES system is greater than the minimum starting power of the alkaline electrolyzer and less than the maximum operating power, the alkaline electrolyzer can absorb all the power difference; when the power difference of the power hydrogen steam cogeneration system is greater than the maximum operating power of the alkaline electrolyzer, the alkaline electrolyzer operates at maximum power, that is,

[0196]

[0197] Where P el,min is the minimum starting power of the alkaline electrolyzer, W; P el,max is the maximum operating power of the alkaline electrolyzer, W.

[0198] The remaining electricity is supplied to steam heat pumps and other equipment. The abandoned power not absorbed by the WHES system is

[0199] P ab =P S -P el -P HP (69)

[0200] When the output power of the wind turbine is less than the power consumption, the power difference is used to determine whether to start the hydrogen fuel cell system to generate electricity. At this time, the power difference of the electricity, hydrogen and steam cogeneration system is only less than 0, and the pressure of the hydrogen in the hydrogen storage tank is monitored. When the hydrogen pressure in the hydrogen storage tank is greater than the minimum hydrogen supply pressure, hydrogen is supplied to the hydrogen fuel cell. Hydrogen fuel cells have the ability to operate with wide power fluctuations within a certain range, and the power operating range is usually 10% to 100% of the rated power. The hydrogen pressure in the hydrogen storage tank should meet

[0201] p min <p st (70)

[0202] In the formula, p st is the minimum hydrogen pressure of the hydrogen storage tank, Pa

[0203] The output power of the hydrogen fuel cell depends on the size of the power difference. S When the starting power is less than the minimum starting power of the hydrogen fuel cell, the starting condition of the hydrogen fuel cell is not met and it is in a shutdown state; when -PS When it is greater than the minimum starting power of the hydrogen fuel cell and less than the maximum power generation power, the power generation power of the fuel cell is -P S ; When -P S When it is greater than the maximum power generation of the hydrogen fuel cell, the hydrogen fuel cell operates at maximum power. The power generation of the hydrogen fuel cell is

[0204]

[0205] Where P fc,min is the minimum starting power of the fuel cell, W; P fc,max is the maximum operating power of the fuel cell, W.

[0206] The power hydrogen steam cogeneration system supplements the power generation through fuel cells, and its loss power is

[0207] P d =-P S -P fc -P HP (72)

[0208] The electric power hydrogen steam system mainly involves the mutual conversion of electric energy, hydrogen energy and thermal energy, and its system can be evaluated by the electric-hydrogen-steam cycle efficiency. The energy utilization and conversion of the electric power hydrogen steam system are shown in Table 2. The alkaline electrolyzer produces 221.57kg of hydrogen, which consumes a total of 10901.14kWh of electricity. The hydrogen produced by the electric power hydrogen steam system is not completely consumed by the hydrogen fuel cell. The mass of hydrogen consumed in the power generation process of the hydrogen fuel cell is 145.94kg. The steam heat pump produces 9.81t of steam from the waste heat recovery of the alkaline electrolyzer and the fuel cell. The electric-hydrogen-steam cycle efficiency of the system should be calculated based on 145.94kg of hydrogen as shown in Table 3. The power consumption of the alkaline electrolyzer to produce 145.94kg of hydrogen is about 7134kWh. The power generation of the fuel cell consuming 145.94kg of hydrogen is 2554kWh. The power consumption of the steam heat pump to recover waste heat is about 1087.5kWh. Therefore, the power-hydrogen-steam cycle efficiency of the power-hydrogen-steam system is 31.06%.

[0209] Table 2 Energy conversion of main equipment in the system

[0210]

[0211] Table 3 System electricity-hydrogen-steam cycle efficiency

[0212]

[0213] Analyze the power hydrogen steam system. Efficiency and Loss Figure 5 . System Efficiency is related to the amount of electricity consumed and the quality of hydrogen generated. Calculations show that the efficiency of the power hydrogen steam system is about 63.46%. The loss value is 672.4kWh. The reason for the efficiency is that there is a lot of energy loss in its working process. The main equipment of the power hydrogen steam system is analyzed, among which the alkaline electrolyzer The efficiency is about 37.3%. The loss is 656.4 kWh. The reason is that the alkaline electrolyzer generates a lot of waste heat during operation, which cannot be used by the electrolyzer. The electrical energy is lost in the form of heat, resulting in a decrease in the efficiency of the alkaline electrolyzer. The efficiency is about 51.3%. The loss is 427.1kWh. The reason is that the internal polarization of the hydrogen fuel cell consumes energy, and the waste heat generated during the working process cannot be used by the fuel cell. The efficiency is low. Steam heat pumps can significantly improve the system's efficiency by utilizing the waste heat from alkaline electrolyzers and fuel cells. Efficiency, The efficiency is about 55.48%. The loss is 304.1kWh. The reason is that steam heat pump production involves multiple heat exchanges and multi-stage compression, which leads to certain energy losses.

[0214] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

Claims

1. A control method for an industrial fuel cell heat pump coupled power hydrogen steam cogeneration system, characterized in that: The following steps are involved: Step 1: Establish a mathematical model of the power, hydrogen and steam cogeneration system; Step 2: Establish a system performance analysis model; Step 3: Using the output thermal power, COP, output net power and SSR of the fuel cell-heat pump as the target quantities, and the operating temperature, current density, waste heat energy density and heat flow ratio of the heat pump as the decision variables, the data set is obtained using matlab / simulink software; Step 4: By monitoring the difference between wind turbine power and power consumption and the operating status of hydrogen storage tanks, establish the control strategy of the power hydrogen steam cogeneration system, and perform simulation calculation and analysis based on wind speed and power consumption; Efficiency Assessment of the energy conversion capacity of power, hydrogen and steam cogeneration systems and equipment.

2. The method according to claim 1, characterized in that In the Step 1, the mathematical model of the power hydrogen steam cogeneration system is established, including the following contents: Step 1.1: Establish a mathematical model of wind turbine generator set; The wind speed model divides the wind speed into two parts: quasi-steady-state wind speed and turbulent wind speed. The wind speed data can be obtained in real time by superimposing the quasi-steady-state wind speed and turbulent wind speed. The formula is: v W =v1+v2 In the formula, v w is the wind speed, in m / s; v1 is the turbulent wind speed, in m / s; v2 is the quasi-static wind speed, in m / s; The turbulent wind speed uses a standard normal distribution white noise generator to simulate the turbulent wind speed changes; the turbulent wind speed satisfies the following equation: Where, T v is a time constant, which is related to the hub height of the wind turbine and the medium wind speed; w is the hub height of the wind turbine rotor, in m; v0 is the medium wind speed of the wind turbine, in m / s; m w is the standard normally distributed white noise, unit is m / s; The output power of a wind turbine is related to wind speed, air density and the area swept by the rotor; based on aerodynamic theory, the output power of a wind turbine is: Where P wt is the output power of the wind turbine, in kW; ρ1 is the air density, in kg / m 3 ; R w is the length of the wind turbine blade; C p (λ,β) is the wind energy utilization coefficient of the wind turbine, where λ is the tip speed ratio and β is the pitch angle of the wind rotor, in degrees; The tip speed ratio λ is the ratio of the tip linear velocity of the wind turbine blade to the wind speed. The calculation formula is: Where ω is the angular velocity of the wind turbine rotor, in rad / s; n w is the wind turbine speed, in r / min; the wind energy utilization coefficient is the ratio of the mechanical power output of the wind turbine to the wind energy power input into the wind wheel surface, C p The specific expression of (λ,β) is as follows:

3. The method according to claim 1, characterized in that In the Step 1, the mathematical model of the power hydrogen steam cogeneration system is established, including the following contents: Step 1.2: Establish a mathematical model of the alkaline electrolyzer stack; The catalyst of the anode of the alkaline electrolyzer is composed of nickel, cobalt and iron, and the cathode is composed of nickel and platinum activated carbonizer; the reaction formula for hydrogen production by electrolysis of water is: 2H2O=2H2+O2 The voltage of a single electrolytic cell of an alkaline electrolytic cell is related to parameters such as the operating current, operating temperature, and electrode surface area; the output voltage of an alkaline electrolytic cell is: Where U el is the working voltage of the electrolytic cell, in V; U rev is the reversible voltage of the electrolytic cell that changes with temperature, in C; I el is the working current of the electrolytic cell, in A; r1, r2 are the ohmic resistance parameters of the electrolyte; T el is the working temperature of the electrolytic cell, in °C; k el , is the overvoltage parameter on the electrolytic cell electrode; S el is the surface area of ​​the electrolytic cell electrodes, in m 2 ; Reversible voltage U of the electrolytic cell rev and the electrolytic cell temperature T el The relationship is shown as follows: In the formula, is the reversible voltage under standard conditions; k rev is the empirical temperature coefficient of the reversible voltage; In the large-scale hydrogen production process, it is often necessary to convert several (n el ) The single electrolyzers work in series, then the output voltage U EL for: U EL =n el ·U el The hydrogen production rate of the alkaline electrolyzer is proportional to the working current density; the hydrogen production rate is: In the formula, is the rate of hydrogen generation, in mol / s; η el is the electrolytic cell current efficiency, unit: %; The current efficiency of the alkaline electrolyzer can be calculated according to the empirical formula: The heat generated by the alkaline electrolyzer is consumed by maintaining its own temperature, dissipating heat to the environment, and absorbing heat from cooling water. According to the law of conservation of thermodynamic energy, the thermal model of the alkaline electrolyzer is: In the formula, is the rate of heat generation during hydrogen production in an alkaline electrolyzer, in J / s; is the rate of heat generation during hydrogen production in an alkaline electrolyzer, in J / s; is the rate of heat generation during hydrogen production in an alkaline electrolyzer, in J / s; is the rate of heat generation during hydrogen production in an alkaline electrolyzer, in J / s; The heat generation of an alkaline electrolytic cell is related to the operating current, operating voltage, and power efficiency. The heat generation rate of an alkaline electrolytic cell is: Where η ef is the electric energy efficiency, unit: %; U th is the thermal neutral voltage, unit V; η ef is the power efficiency, unit %; the working temperature of the alkaline electrolyzer meets: In the formula, C el is the heat capacity of the alkaline electrolytic cell, in J / K; The ambient heat dissipation of the alkaline electrolyzer is: In the formula, R el is the thermal resistance of the alkaline electrolytic cell, unit K / W; The heat flow rate removed by the cooling water system is related to the temperature difference between the cooling water inlet and outlet: The hydrogen production efficiency is proportional to the quality of hydrogen produced and inversely proportional to the power consumption, that is: Where η hy is the hydrogen production efficiency of the alkaline electrolyzer, unit: %; W el is the power consumption of the alkaline electrolyzer, in J; M1 is the mass of hydrogen produced, in mol.

4. The method according to claim 1, characterized in that: In the Step 1, the mathematical model of the power hydrogen steam cogeneration system is established, including the following contents: Step 1.3: Establish a mathematical model of the proton exchange membrane fuel cell stack; The stack system can calculate the output power of the PEMFC and some inevitable losses in the battery; the output voltage of a single battery: V cell =E nernst -or act -or ohmic -or conc In the formula, E nernst is the Nernst voltage, in V; η act is the activation overvoltage, in V; η ohmic is the ohmic overvoltage, in V; η conc is the mass concentration overvoltage, in V; The Nernst equation is used to confirm the reversible potential generated by the chemical reactions inside the PEMFC: Where, T stack is the internal temperature of the battery stack; and are the partial pressures on the hydrogen side and the partial pressures on the oxygen side, respectively; The partial pressures of hydrogen and oxygen are expressed as: Where T stack is the reaction temperature; P Anode is the anode partial pressure, unit is atm; P Cathode is the cathode partial pressure; i is the current density; is the saturation pressure of water; T s =T stack -273.15 The activation overvoltage is the energy consumed by the cathode and anode to start the chemical reaction by crossing the electrolyte, overcoming the activation energy required for the reaction: Among them, β1, β2, β3, and β4 are empirical constants of fuel cells; are the effective partial pressures on the anode and cathode catalysts, respectively; A is the effective activation area of ​​a single cell; The total ohmic loss of the resistor can be divided into electron ohmic loss and proton ohmic loss, of which the electron loss is smaller and is not considered; according to Ohm's law: or ohm =iAR int Among them, R int is the equivalent resistance of the proton exchange membrane; it is determined by conductivity, temperature and humidity: Where t0 represents the membrane thickness; σ represents the influence of membrane conductivity on temperature, membrane water content and current density: Wherein, λ is the water content of the proton exchange membrane; As the battery power increases, the current density increases, and the reaction rate on the catalyst exceeds the gas supply rate flowing into the medium, resulting in voltage loss; Among them, i max is the maximum current density that the fuel cell can achieve; When modeling the fuel cell stack, assuming that the performance of each single cell in the fuel cell stack is consistent, the fuel cell stack voltage can be calculated as follows: V stack =N·V cell The total electrical power and thermal power of the stack can be obtained by the following formula: P stack =V stack ·i·A cell The heat generated in the stack is taken away from the stack by cooling water and reaction gas respectively; the heat balance equation of the stack temperature can be derived from the law of conservation of energy as follows: The total power of the electrochemical reaction is expressed as: The heat taken away from the stack by cooling water is: The amount of hydrogen consumed by a hydrogen fuel cell during operation is determined by the operating state; the power generation efficiency of a hydrogen fuel cell is related to the amount of electricity output and the quality of hydrogen consumed, namely: Where η fc is the power generation efficiency of the fuel cell, unit: %; W fc is the power generation of the fuel cell, in J; M2 is the mass of hydrogen consumed, in mol.

5. The method according to claim 1, characterized in that: In the Step 1, the mathematical model of the power hydrogen steam cogeneration system is established, including the following contents: Step 1.4: Establish a mathematical model of the steam heat pump; The coefficient of performance (COP) of a steam heat pump is an indicator to measure the energy efficiency of a heat pump system, indicating the ratio of the amount of heat or cooling that can be provided per unit of energy consumed in the process of converting primary energy into thermal energy by the heat pump system; Where, T co is the outlet temperature of the heat pump condenser, in K; T eo is the outlet temperature of the heat pump evaporator, unit K; The heat transferred by the steam heat pump is the energy absorbed by the steam heat pump from the heat storage tank and transferred to the steam tank after compression and circulation; the heat transferred depends on the energy efficiency and working performance of the heat pump: Q c =COP*E wp Q e =Q c -E wp =(COP-1)*E wp In the formula, Q c is the heat supply of the heat pump, unit W; E wp is the power consumption of the heat pump, in W; COP is the coefficient of performance of the heat pump; Q e The heat removed by the heat pump; The steam heat pump output temperature depends on factors such as its operating mode (heating or cooling), input heat and output heat load requirements; in, are the mass flow rates of waste heat cooling water at the condensing end and evaporating end and steam tank water vapor respectively; c w 、c avg are the specific heat capacities of cooling water and steam, respectively; The specific heat capacity of water vapor requires additional calculation: The heat transfer during the water heating phase is: The heat transfer during the water evaporation stage is: The heat transfer during the water evaporation stage is: Total heat transfer (Q s )for: <h2 style=";text-align:left;direction:ltr">Q<h2 style=";text-align:left;direction:ltr"> s <h2 style=";text-align:left;direction:ltr"> =Q1+Q2+Q3 The average specific heat capacity is: Where, T ci is the inlet temperature of the heat pump condenser, unit K; ΔT c It indicates the temperature difference between the inlet and outlet of the condenser; ΔT1 and ΔT3 indicate the temperature difference of each stage in the condenser.

6. The method according to claim 1, characterized in that In step 2, establishing a system performance analysis model includes the following contents: From energy conversion efficiency, Efficiency and Objectively evaluate the performance of the system in three aspects of loss; The net output power of the system is defined as: W=W fc -IN HP The electrical conversion rate of the system is: The power self-sufficiency ratio (SSR) is the ratio of the power provided by the PEMFC to the power consumed by the heat pump: Where W fc is the power generation of the fuel cell, in J; W HP is the power consumption of the steam heat pump, in J; The power-hydrogen-steam cycle efficiency of the system is defined as: Where, η is the power-hydrogen-steam cycle efficiency of the system, unit: %; W el is the power consumption of the alkaline electrolytic cell, in J; system Efficiency (E x_s )and Loss (E x_loss ) is calculated according to the following formula: In the formula, E x_in For input system Value, unit J; E x_out For outflow system Value, unit J; Water for hydrogen production Value, unit J; Hydrogen output for the system Value, unit J; Oxygen output for the system Value, unit J; E x_Stream Steam output for the system Value, unit J; Alkaline electrolyzer Efficiency (E x_el )and Loss (E x_loss_el ) are: In the formula, Producing hydrogen for alkaline electrolyzers Value, unit J; Producing oxygen for alkaline electrolyzers Value, unit J; Water for hydrogen production Value, unit J; Fuel Cell Efficiency (E x_fc )and Loss (E x_loss_fc ) are: In the formula, Hydrogen consumption for fuel cells Value, unit J; Consuming oxygen for fuel cells Value, unit J; To generate water for fuel cells Value, unit J; Steam heat pump Efficiency (E x_HP )and Loss (E x_loss_HP ) are: In the formula, E x_Stream Generating steam for steam heat pumps Value, unit J; For water consumption in steam heat pumps Value, unit is J.

7. The method according to claim 1, characterized in that The input is the operating temperature and current density of the proton exchange membrane fuel cell stack and the waste heat energy density and heat flow ratio recovered by the high-temperature heat pump. The output is thermal power, COP, net power and SSR.

8. The method according to claim 1, characterized in that In Step 4, the control strategy of the power hydrogen steam cogeneration system includes the following: According to the difference between the output power of the wind turbine and the power consumption, the energy management timely adjusts the operating status of the hydrogen production equipment of the power hydrogen steam cogeneration system according to the real-time power difference, in order to absorb the power generation of the wind turbine as much as possible; the power difference P of the power hydrogen steam cogeneration system S for: P S =P wt -P L Where P wt is the output power of the wind turbine; P L Electricity for chemical plants; When the output power of the wind turbine generator is greater than the power consumption, it is determined whether to start the alkaline electrolyzer to produce hydrogen according to the power difference of the electricity, hydrogen and steam cogeneration system; When the power difference P S When it is greater than 0, the power hydrogen steam cogeneration system determines whether to produce hydrogen based on the pressure of the hydrogen in the storage tank; the pressure of the hydrogen storage tank should meet the following requirements: p st <p max In the formula, p st is the pressure of hydrogen in the hydrogen storage tank; p max It is the maximum safe working pressure limit of the hydrogen storage tank; When the power difference meets the operating power demand of the alkaline electrolyzer for hydrogen production, the remaining power is supplied to the alkaline electrolyzer, steam heat pump and other equipment: P S =P el +P HP Where P el is the input power of the alkaline electrolyzer; P HP The power consumed by the steam heat pump to recover waste heat; When the power difference of the power hydrogen steam cogeneration system is less than the minimum starting power of the alkaline electrolyzer, the alkaline electrolyzer is in a shutdown state; when the system power difference is greater than the minimum starting power of the alkaline electrolyzer and less than the maximum operating power, the alkaline electrolyzer absorbs all the power difference; when the power difference of the power hydrogen steam cogeneration system is greater than the maximum operating power of the alkaline electrolyzer, the alkaline electrolyzer operates at maximum power, that is Where P el,min is the minimum starting power of the alkaline electrolyzer; P el,max is the maximum operating power of the alkaline electrolyzer; The remaining electricity is supplied to equipment such as steam heat pumps; The abandoned power not absorbed by the system is P ab =P S -P el -P HP 9. The method according to claim 8, characterized in that When the output power of the wind turbine is less than the power consumption, the power difference is used to determine whether to start the hydrogen fuel cell system to generate electricity; at this time, the power difference of the electricity, hydrogen and steam cogeneration system is only less than 0, and the pressure of the hydrogen in the hydrogen storage tank is monitored; when the hydrogen pressure in the hydrogen storage tank is greater than the minimum hydrogen supply pressure, hydrogen is supplied to the hydrogen fuel cell; the hydrogen fuel cell has the ability to work with wide power fluctuations within a certain range, and the power operation range is usually 10% to 100% of the rated power; the hydrogen pressure in the hydrogen storage tank should meet p min <p st In the formula, p st is the minimum hydrogen pressure of the hydrogen storage tank; When-P S When the starting power is less than the minimum starting power of the hydrogen fuel cell, the starting condition of the hydrogen fuel cell is not met and it is in a shutdown state; when -P S When it is greater than the minimum starting power of the hydrogen fuel cell and less than the maximum power generation power, the power generation power of the fuel cell is -P S ; When -P S When it is greater than the maximum power generation of the hydrogen fuel cell, the hydrogen fuel cell operates at maximum power; the power generation of the hydrogen fuel cell is Where P fc,min is the minimum starting power of the fuel cell; P fc,max is the maximum operating power of the fuel cell; The system supplements the power generation through fuel cells, and the power loss caused by insufficient power supply is P d =-P S -P fc -P HP 。

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